JP2010122670A - Anisotropic film, viewing angle compensation membrane, viewing angle compensation element, polarization element and liquid crystal display apparatus - Google Patents

Abstract

（上記式（１）において、ｘ及びｙは膜面内の直交する光学主軸を表し、ｚは膜厚方向の光学主軸を表す。）
【選択図】なし
PROBLEM TO BE SOLVED: To provide an anisotropic film useful for a viewing angle compensation film and the like which has no color change and is low in cost and high in durability.
A and the thickness direction of the extinction coefficient k _z, extinction coefficient k _x and k _y in the film plane direction, the anisotropic film, which satisfies the following formula (1) at a wavelength of 550 nm.

(In the above formula (1), x and y represent orthogonal optical principal axes in the film plane, and z represents the optical principal axis in the film thickness direction.)
[Selection figure] None

Description

  The present invention relates to an anisotropic film, a viewing angle compensation film, a viewing angle compensation element, a polarizing element, and a liquid crystal display device that are useful mainly for viewing angle compensation films used in liquid crystal display devices.

  In recent years, liquid crystal display devices (hereinafter sometimes referred to as “liquid crystal displays”) have increased in screen size and image quality, and there has been an increasing demand for improving viewing angle characteristics. The viewing angle characteristic means a characteristic in which the contrast or color of an image changes depending on the viewing direction with respect to the display screen, and has been regarded as a fundamental structural problem of a liquid crystal display. As a result of this improvement in characteristics, for example, in liquid crystal television applications, display modes with improved viewing angle characteristics of liquid crystal cells, such as a vertical alignment (VA) mode and a horizontal electric field (IPS) mode, have become mainstream.

  With the improvement of the viewing angle characteristics of such liquid crystal cells, the viewing angle characteristics of O-type polarizing plates represented by iodine polarizing plates have recently been regarded as a problem (see Non-Patent Document 1, etc.). As a method for improving this, a method of using an E-type polarizing plate (see Non-Patent Document 2, etc.) or an elliptical polarizing plate (see Patent Document 1, etc.) instead of an O-type polarizing plate, a plurality of retardation films as compensation plates A combination method (see Non-Patent Documents 3 to 11, etc.) is known.

  However, the method using an E-type polarizing plate or an elliptical polarizing plate is difficult to obtain a higher degree of polarization than an iodine polarizing plate, and currently, a method using a retardation film as a compensation plate in combination with an iodine polarizing plate is mainly used. It has become. On the other hand, since retardation films have problems such as color shift, recently, in order to control the hue when viewed obliquely, a co-polymer consisting of monomer units having positive and negative molecular polarizability anisotropy is used. A method of controlling the wavelength dispersion of the refractive index using a coalescence (see Non-Patent Document 10, etc.), a method of using two biaxial films whose three-dimensional refractive index is precisely controlled (see Non-Patent Document 11, etc.), etc. Has been proposed.

Japanese Patent Laid-Open No. 10-332934

P. Yeh and C. Gu, "Optics of Liquid Crystal Displays", J. Wiley & Sons, Inc. (1999), p.70-74. P. Yeh and M. Paukshto, "Molecular Crystalline Thin Film E-Polarizer", Mol. Materials, 14, p1-19, (2001). K. Ohmuro et.al., SID’97 Dig. Of Tech. Papers, 28 (1997), 845. J. Chen et.al., SID’98 Dig. Of Tech. Papers, 29 (1998), 315. Y. Saitoh et.al., SID’98 Dig. Of Tech. Papers, 29 (1998), 706. M.Fukumoto et.al., IDW’00 (2000), 137. T. Ishinabe et.al. Jpn. J. Appl. Phys., 41 (2002), 4553. T. Houryu et.al., Proc. IDW’03 (2003), 121. X.Zhu et.al. SID’05 Dig. Of Tech. Papers, 36 (2005), 1164. Akihiko Uchiyama, “Chromatic dispersion control of birefringence in retardation film and its application to liquid crystal display”, Journal of the Japanese Liquid Crystal Society, vol.9, No.4, p.209, (2005) "Progress in viewing-angle properties of liquid-crystal displays", T. Uchida and T. Ishinabe, J. SID 12/3 (2004), 309.

However, the method of precisely performing the wavelength dispersion control and the three-dimensional refractive index control of the retardation film as described above relates to the durability that it is liable to cause performance deterioration due to environmental changes in addition to difficulties in the manufacturing process. Had drawbacks. There was also a problem of cost increase.
The present invention has been made in view of the above circumstances. That is, an object of the present invention is to provide an anisotropic film that is useful for a viewing angle compensation film and the like that has no color change and is low in cost and high in durability.

When the present inventors examined the above problems, in the first place, the problem of viewing angle characteristics of the O-type polarizing plate based on the imaginary part anisotropy of the three-dimensional complex refractive index was controlled. It has been found that the conventional idea of compensating with a birefringent retardation plate based on the principle is a detour, and as a result, a large load is imposed on the manufacturing process and optical design.
As a result of intensive studies, it was found that viewing angle characteristics can be remarkably improved by using an anisotropic film in which the anisotropy of the imaginary part of the three-dimensional complex refractive index in the visible light wavelength region is controlled to a specific range. . Furthermore, it has been found that the anisotropic film thus obtained has no color change, can be produced at low cost, and has high durability, and has completed the present invention.

That is, the present invention provides an extinction coefficient k _z corresponding to the imaginary part of the three-dimensional complex refractive index in the film thickness direction, an extinction coefficient k _x corresponding to the imaginary part of the three-dimensional complex refractive index in the in-plane direction, and k _y is consists in an anisotropic film, which satisfies the following formula (1) at a wavelength of 550 nm.

(In the above formula (1), x and y represent orthogonal optical principal axes in the film plane, and z represents the optical principal axis in the film thickness direction.)

Here, the anisotropic film of the present invention is characterized in that k _z / k _x ≧ 2 and k _z / k _y ≧ 2.
Further, the stimulation purity of transmitted light when p-polarized light is incident from the polar angle of 45 degrees is 40% or less.
Furthermore, it contains an azo compound having an excitation purity of 20% or less.
Furthermore, the azo compound is characterized in that the form of the free acid is represented by the following general formula (2) and is an azo compound having lyotropic liquid crystallinity.

(In the general formula (2), A represents an aromatic hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent.
B represents an aromatic hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent.

m represents 0 or 1.
p represents an integer of 0 to 3. When p is 2 to 3, a plurality of B present in one molecule may be the same or different from each other.
R ¹ and R ² each independently represent a hydrogen atom, an alkyl group that may have a substituent, a phenyl group that may have a substituent, or an acyl group that may have a substituent. To express. )

Another gist of the present invention resides in a viewing angle compensation film comprising the anisotropic film of the present invention.
Still another subject matter of the present invention lies in a viewing angle compensation element comprising the viewing angle compensation film of the present invention and another member.
The gist of the present invention resides in a polarizing element comprising the anisotropic film of the present invention, the viewing angle compensation film of the present invention or the viewing angle compensation element of the present invention, and a polarizing film.
Further, the gist of the present invention is a liquid crystal display device comprising the anisotropic film of the present invention, the viewing angle compensation film of the present invention, the viewing angle compensation element of the present invention or the polarizing element of the present invention. Exist.

  According to the present invention, it is possible to provide an anisotropic film that is useful for a viewing angle compensation film and the like that has no color change and is low in cost and high in durability. In addition, a viewing angle compensation film, a viewing angle compensation element, a polarizing element, and a liquid crystal display device including the anisotropic film can be provided.

It is a schematic diagram showing the viewing angle characteristic problem of an O-type polarizing plate. It is a schematic diagram showing the case where the anisotropic film | membrane of this invention is used in combination with an O-type polarizing plate. 6 is a graph showing the relationship between the contrast ratio (CR) and the polar angle (θ) of the polarizing element 1 of Example 1 and the polarizing element 2 of Comparative Example 1.

Hereinafter, embodiments of the present invention will be described in detail.
The description of the constituent requirements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not specified in these contents unless it exceeds the gist.
In the present specification, “may have a substituent” means that one or more substituents may be present.
Further, in this specification, the term “carbon number” of a substituent represents the number of carbon atoms contained in the substituent, and when the substituent has a further substituent, In the case of “carbon number”, it means all the carbon numbers including the carbon number contained in the further substituent.

1. Anisotropic film In the present specification, the anisotropic film means a total of 3 in a three-dimensional coordinate system in the film thickness direction (hereinafter sometimes referred to as “film thickness direction”) and in two directions in an arbitrary orthogonal film plane. It means a film having anisotropy in electromagnetic properties in any two directions selected from directions. Examples of electromagnetic properties include optical properties such as absorption and refraction, and electrical properties such as resistance and capacitance. Examples of films having optical anisotropy such as absorption and refraction generally include a viewing angle compensation film, a linearly polarizing film, a circularly polarizing film, a retardation film, and a conductive anisotropic film.

The anisotropic film of the present invention is characterized in that the imaginary part of the three-dimensional complex refractive index, that is, the three-dimensional extinction coefficient is in a specific range described later.
Here, the complex refractive index N is defined as N≡n−ik from the refractive index n which is the ratio of the propagation speed of light in vacuum and the material and the extinction coefficient k representing the light absorption by the material. The real part represents the refractive index and the imaginary part represents the extinction coefficient. When the substance is an anisotropic substance, the three-dimensional complex refractive index is expressed by the following formula (3) by expanding the complex refractive index.

(In the above formula (3), x and y represent orthogonal optical principal axes in the film plane, and z represents the optical principal axis in the film thickness direction.
N _x , N _y and N _z represent a three-dimensional complex refractive index.
n _{x, n y} and _{n z} represent the three-dimensional refractive _{index, k x,} k _y and _{k z} is the number of three-dimensional extinction coefficient. )

In the present invention, the three directions in the three-dimensional solid coordinate system are defined as x, y, and z, respectively, and x and y are defined as the in-film direction and z is defined as the film thickness direction. That is, x and y are arbitrary two optical principal axes orthogonal to each other in the film plane. k _x and k _y represent extinction coefficients in the x and y directions, respectively, and k _z represents the extinction coefficient in the film thickness direction.

The three-dimensional refractive index and the three-dimensional extinction coefficient are measured by a spectroscopic ellipsometer, a single wavelength ellipsometer, a prism coupler, a reflection spectral film thickness meter, or the like. Among these, in order to calculate the value of the three-dimensional complex refractive index of the anisotropic film of the present invention with high accuracy, it is preferable to perform measurement with a spectroscopic ellipsometer. Examples of the spectroscopic ellipsometer include “UVISEL” manufactured by Horiba Joban Yvon.
Hereinafter, the case where each optical constant (three-dimensional refractive index and three-dimensional extinction coefficient) of the anisotropic film of the present invention is calculated by a spectroscopic ellipsometer will be described as an example.

(Measurement)
In the measurement, it is preferable that the anisotropic film is installed so that the optical axis is parallel or perpendicular to the incident light because analysis described later becomes easy. The measurement wavelength range is preferably from the visible light wavelength region to the near infrared wavelength region in order to obtain the optical constant with high accuracy.
Further, the appropriate incident angle depends on the material and is not particularly limited. However, when the anisotropic film is laminated on the substrate, the substrate may be a substrate such as glass or polymer film generally used for optical materials. If it is 60 degrees, it is preferable. Furthermore, it is preferable to measure only the substrate in order to increase the accuracy of the analysis described later.

(analysis)
When the anisotropic film is in a state of being laminated on the substrate, in order to improve the analysis accuracy, after calculating the optical constant of only the substrate first, the anisotropic film is laminated on the substrate having the optical constant. It is preferable to analyze. Since the anisotropic film of the present invention has biaxial anisotropy, the optical constant can be calculated by optimally fitting measurement data with a model having a three-dimensional complex refractive index. For example, it can be calculated using known analysis software such as analysis software “DeltaPsi2” manufactured by Horiba Joban Yvon.

Here, in order to describe the complex refractive index components in each of the three directions, a plurality of Lorentz oscillator dispersion formulas are used. In determining the appropriateness of the obtained optimum fitting result, not only the value of χ ² is sufficiently small, but also the film thickness value obtained at the same time as the optical constant is reasonable, and the obtained k _x , It is also based on the fact that the absorption spectrum of the film calculated from k _y and k _z is not significantly different from the absorption spectrum actually measured with a spectrophotometer.

Examples of preferable measurement and analysis conditions for the anisotropic film of the present invention are as follows.
<Preferable measurement and analysis conditions>
・ Measurement equipment: Spectroscopic ellipsometer “UVISEL” (manufactured by Horiba Joban Yvon)
・ Analysis software: Software DeltaPsi2 (Horiba Joban Yvon) ・ Sample: Anisotropic film formed on glass substrate covered with polyimide alignment film ・ Optical axis: Application of anisotropic film Installation so that the direction is parallel to the incident light. Incident angle of incident light: 60 °
・ Measurement range: Wavelength range of photon energy of 0.6 to 3.1 eV ・ Measurement method (a) First, measure only the substrate and use a single Lorentz vibrator dispersion formula for the polyimide alignment film. Analyze to obtain the optical constant of the substrate.
(B) Next, the anisotropic film on the substrate is measured, and the biaxiality difference having a three-dimensional complex refractive index laminated on the substrate having the optical constant obtained previously is measured with respect to the anisotropic film. Analyze as isotropic membrane. At this time, the coating parallel direction is the x-axis, the vertical direction is the y-axis, the film depth direction is the z-axis, one Lorentz vibrator for the x-axis component, two Lorentz vibrators for the y-axis component, and 3 for the z-axis component. Optimal fitting of measurement data is performed as a model having two Lorentz oscillators. The vibration frequency given as the initial value in the Lorentz vibrator dispersion formula is determined based on the absorption spectrum by the spectrophotometer.
Analysis of (c) (a) above, to obtain anisotropic films x, y, the complex refractive index of the z-axis _{n x -ik x, n y -ik} y, a n z -ik _z.

Anisotropic film of the present invention, the extinction coefficient k _z in the thickness direction, the extinction coefficient k _x and k _y in the film plane direction, and satisfies the following formula (1) at a wavelength of 550nm .

(In the above formula (1), x and y represent orthogonal optical principal axes in the film plane, and z represents the optical principal axis in the film thickness direction.)
The above formula (1) means that the anisotropic film of the present invention has larger absorption in the film thickness direction than in the in-film direction. The anisotropic film of the present invention has greater absorption in the in-plane direction of the film, so it is almost transparent when the film is viewed from the front, but appears colored when viewed from an oblique direction. Such a function does not adversely affect the display in a display device such as a liquid crystal display, and is useful for purposes such as viewing angle compensation, control of diffused light and scattered light, and visible angle control.

In order to describe the function of the anisotropic film of the present invention, first, the viewing angle characteristic problem of the O-type polarizing plate described in Non-Patent Document 1 and the like will be described below.
As shown in FIG. 1A, two square O-type polarizing plates having absorption axes on a diagonal line are arranged in parallel so that the absorption axes are vertical, and light is incident vertically. When viewed from the emission side, the two polarizing plates appear square, and the two absorption axes on different diagonal lines are vertical, so there is no leakage light if the polarizing plate is ideal.

On the other hand, as shown in FIG. 1B, when the light is incident obliquely on the polarizing plate and similarly observed from the emission side, the square polarizing plate looks like a parallelogram or a rectangle. For this reason, the two absorption axes on different diagonal lines are not generally vertical, and leak light is generated. In addition, in the direction where the overlapping polarizing plates appear to be diamond-shaped, the two absorption axes are perpendicular to each other, but light absorption is also reported because the absorption axis of one polarizing plate is tilted (Iimura and Suzuki, “Optical compensation technology for crossed polarizing plates using negative A plate”, Monthly Display, 2006 (7), p.16, Fig. 4).

When an O-type polarizing plate is used in a liquid crystal display device, such oblique light leakage is a major factor that deteriorates viewing angle characteristics.
Next, the schematic diagram which combined the anisotropic film | membrane of this invention with the O-type polarizing plate by the side of emission is shown in FIG. The anisotropic film of the present invention is expressed as a rectangular parallelepiped having a square bottom surface. Since the anisotropic film of the present invention has absorption mainly in the film thickness direction and does not have large absorption in the film in-plane direction, only absorption in the film thickness direction is schematically described. That is, it has absorption in the height direction of the rectangular parallelepiped. This is disposed between two O-type polarizing plates arranged in parallel so that the absorption axes of the incident-side O-type polarizing plate and the outgoing-side O-type polarizing plate are perpendicular to each other.

First, in FIG. 2A, when light is vertically incident, absorption in the film thickness direction is not visible from the emission side, so that the two polarizing plates appear square as in FIG. 1A, and are on different diagonal lines. The two absorption axes are perpendicular to each other, and there is no light leakage if the polarizing plate is ideal.
On the other hand, when light is incident obliquely in FIG. 2 (B), absorption in the height direction of the rectangular parallelepiped is visible unlike FIG. 1 (B), but as shown schematically in the figure, An absorption axis perpendicular to the absorption axis on the incident side can be appropriately selected. Therefore, there is no light leakage even in an oblique direction. Moreover, since the absorption of the reduced polarizing plate can be supplemented by the absorption of the anisotropic film of the present invention even in the direction where it looks like a diamond, light leakage can be prevented.

Anisotropic film of the present invention having such a function, three-dimensional extinction coefficient k _x, but k _y and k _z are those satisfying the formula (1), preferably, k _z ≧ 0.3 And more preferably k _z ≧ 0.4. Preferably, k _x and k _y are both 0.3 or less, more preferably 0.2 or less. k _x and k _y are preferably close to each other, and preferably 0.5 ≦ k _x / k _y ≦ 2.0.

Further, preferably k _z / k _x ≧ 2 and k _z / k _y ≧ 2, more preferably k _z / k _x ≧ 3 and k _z / k _y ≧ 3.
Anisotropic film of the present invention, the above as a three-dimensional extinction coefficient _k x, _{k y} and _{k z} are but satisfies the formula at a wavelength 550nm to (1), 450 nm, 550nm, neither the 650nm It is preferable to satisfy the formula (1). In addition, it is more preferable to have the above characteristics over the entire visible light wavelength region from the viewpoint of viewing angle compensation efficiency.

In the anisotropic film of the present invention, it is preferable that the stimulation purity of transmitted light when p-polarized light is incident from a 45 ° polar angle direction is 40% or less regardless of the azimuth angle.
Here, the polar angle is an angle between an incident light beam and a perpendicular perpendicular to the film surface, and a polar angle of 0 ° means normal incidence. The azimuth angle is an angle between a straight line obtained by projecting incident light rays perpendicularly to the film surface and an arbitrary straight line parallel to the film surface in the film. The p-polarized light is a polarized component in which the electric field of incident light is parallel to the incident surface.

Stimulus purity refers to the ratio of each point with the wavelength corresponding to the intersection of the chromaticity coordinate N of the standard light and the chromaticity coordinate C obtained from the chromaticity diagram as a straight line, and the intersection with the extended spectral locus. Calculate from The chromaticity coordinate C of the anisotropic film is a CIE1964 XYZ color system, chromaticity under a D65 standard light source, measured with a spectrophotometer when visible light wavelength transmittance is incident from 45 degrees polar angle. xy can be calculated and obtained. As a calculation method thereof, a known method described in pages 104 to 105, etc. of the New Color Science Handbook (published by the University of Tokyo Press, November 25, 1989 (2nd revision)) edited by the Japan Color Society It can ask for. An anisotropic film having a stimulus purity of 0 (zero) is an achromatic film having the same chromaticity as the light source.
The stimulus purity of transmitted light when p-polarized light is incident on the anisotropic film of the present invention from the 45 ° polar angle direction is preferably 40% or less, more preferably 30% or less. Such a film is an anisotropic film particularly useful for a viewing angle compensation film.

  The thickness of the anisotropic film of the present invention is usually 0.05 μm or more, preferably 0.1 μm or more, and usually 10 μm or less, preferably 5 μm or less, more preferably 2 μm, although it depends on the film forming method described later. It is as follows. If it exceeds this range, orientation defects may occur or brightness may be reduced. Also, if it falls below this range, functions such as viewing angle compensation may become insufficient.

[Azo compound contained in anisotropic film of the present invention]
In this specification, the anisotropic film is different from the electromagnetic property in any two directions selected from a total of three directions in the three-dimensional coordinate system of the film thickness direction and any two directions in the orthogonal film plane as described above. It is a film having anisotropy. The anisotropic film usually includes an anisotropic material that imparts anisotropy.

The anisotropic film of the present invention preferably contains an azo compound as an anisotropic material.
(I) Stimulus purity The anisotropic film of the present invention preferably contains an azo compound having a stimulus purity of 20% or less. The stimulating purity of the azo compound means that the azo compound is measured as an aqueous solution having a concentration of 1000 ppm by adding water and calculated according to a known method in the same manner as in the above film. The stimulating purity of the azo compound used in the anisotropic film of the present invention is preferably 20% or less, more preferably 12% or less. By using such an azo compound, an anisotropic film particularly useful for a viewing angle compensation film can be provided.

Here, the azo compound is a compound that also has a function as a so-called dye, and the anisotropic film of the present invention can also function as a dye film. The term “dye” as used herein generally means a compound having absorption in the visible light wavelength region.
An azo compound having an excitation purity of 20% or less is a low-saturation, achromatic, black-colored azo compound having absorption over the entire visible light wavelength region. For example, by mixing multiple types of compounds having absorption at various wavelengths, absorption can be achieved over the entire visible light wavelength range, but from the viewpoint of molecular orientation, a single compound can be used for visible light wavelengths. It is preferable to use a material having a wide absorption over the entire region. For example, when a plurality of azo compounds having an excitation purity of 20% or less are used in combination for the purpose of improving the hue of the anisotropic film, the anisotropy formed is not reduced without lowering the orientation degree or liquid crystallinity of the azo compound used mainly. It is preferable to use a combination of other azo compounds as appropriate as long as the film satisfies the formula (1).

(Ii) Angle formed by absorption axis and molecular long axis The azo compound contained in the anisotropic film of the present invention is, for example, J.A. Phys. Chem. A, 1999, 103, p2251 and the like, and the compound is preferably a compound in which the angle formed by the absorption axis and the molecular major axis is 10 degrees or less. When such a compound is selected, the three-dimensional extinction coefficient of the anisotropic film of the present invention easily satisfies the relationship of the above formula (1), and k _z / k _x ≧ 2 and k _z / k _y ≧ This is preferable because it tends to be 2. Preferably it is 5 degrees or less, More preferably, it is 2 degrees or less.
A compound having such properties is also preferable because it does not lower the luminance of the liquid crystal display device.

(Iii) An azo compound represented by the general formula (2) and having lyotropic liquid crystallinity In the anisotropic film of the present invention, preferably, the form of the free acid is represented by the following general formula (2), and An azo compound having lyotropic liquid crystallinity is used. This makes it easier for the three-dimensional extinction coefficient of the film to satisfy the formula (1).

(In the general formula (2), A represents an aromatic hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent.
B represents an aromatic hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent.
m represents 0 or 1.
p represents an integer of 0 to 3. When p is 2 to 3, a plurality of B present in one molecule may be the same or different from each other.
R ₁ and R ₂ each independently represent a hydrogen atom, an alkyl group that may have a substituent, a phenyl group that may have a substituent, or an acyl group that may have a substituent. To express. )

  Here, the compound represented by the form of the free acid is not limited to the acid compound represented by the general formula (2), but can be liberated in the solution or in the composition to become the acid compound. Including, for example, salts and the like. Specific examples include alkali metal salts such as Na, Li, and K, ammonium salts, quaternary ammonium salts, and organic amine salts. Further, in the composition or the anisotropic film, the compound may be mixed in an acid form and a salt form, or may be salt exchanged with other additives added.

Known compounds that are said to have a wide absorption over the entire visible light wavelength range include, for example, biolanthrone compounds, H acid azo compounds (Abeda, Imada, “Explanation Dye Chemistry”, Color dyeing company, (1989). In particular, from the viewpoint of liquid crystallinity, an azo compound represented by the above general formula (2) and having lyotropic liquid crystallinity is preferable.
Even azo compounds that do not have lyotropic liquid crystallinity, for example, "Self-Assembled Monolayers and Multilayered Stacks of Lyotropic Chromonic Liquid Crystalline Dyes with In-Plane Orientational Order", T. Schneider and OD Lavrentovich, Langmuir, 16, 5227 , (2000), the LBL (Layer By Layer) method or the like can be used for precise orientation. However, for example, in order to develop sufficient viewing angle compensation capability, it is necessary to repeat the stacking process several tens of times or more, which is not realistic. By using an azo compound having lyotropic liquid crystallinity, an anisotropic film in which compound molecules are uniformly oriented can be produced by a simple process.

Whether or not the azo compound has lyotropic liquid crystallinity is determined by, for example, dissolving the azo compound in distilled water at an appropriate concentration according to a known method described in JP-A-2008-145901, etc. For example, it can confirm by observing by Eclipse E600-POL etc. made from Nikon. Specifically, an aqueous solution of an azo compound is dropped on a slide glass, covered with a cover glass, and then observed in a crossed Nicol state using a polarizing microscope. Here, as described in J. Lydon, "Chapter XVIII. Chromonics", in "Handbook of Liquid Crystals", vol. 2B: Low Molecular Weight Liquid Crystals II, p981, Wiley-VCH, (1998). If a schlieren-like texture can be observed, it turns out that it has liquid crystallinity.

Hereinafter, the azo compound represented by the above formula (2) will be described in detail.
<A>
A represents an aromatic hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent.
As the aromatic hydrocarbon group for A, a phenyl group which may have a substituent and a naphthyl group which may have a substituent are preferable.

  Examples of the substituent that the aromatic hydrocarbon group of A may have include a hydrophilic group introduced to increase the solubility of the azo compound and an electron donating property introduced to adjust the color tone as a dye. Or an electron-withdrawing group is preferable, and specifically, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an alkenyl group which may have a substituent An amino group, an alkylamino group which may have a substituent, an arylamino group which may have a substituent, an acylamino group which may have a substituent, a carbamoyl group, and a substituent An optionally substituted alkylcarbamoyl group, an optionally substituted arylcarbamoyl group, a sulfamoyl group, an optionally substituted alkylsulfamoyl group, and an optionally substituted arylsulfamoyl group. Amoiru group, a nitro group, a carboxy group, a sulfo group, a hydroxyl group, a cyano group and a halogen atom.

  In the alkyl group, the total number of carbon atoms of the substituent is usually 1 or more, usually 6 or less, preferably 4 or less. Examples of the group that may be substituted on the alkyl group include an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, a halogen atom, a sulfo group, and a carboxy group. Specific examples of the alkyl group include a lower alkyl group which may have a substituent such as a methyl group, an ethyl group, an n-propyl group, a hydroxyethyl group, or a 2,3-dihydroxypropyl group.

  In the alkoxy group, the total carbon number of the substituent is usually 1 or more, usually 6 or less, preferably 3 or less. Examples of the group that may be substituted on the alkoxy group include an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, a halogen atom, a sulfo group, and a carboxy group. Specific examples of the alkoxy group include a lower alkoxy group which may have a substituent such as a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, a hydroxyethoxy group, and a 2,3-dihydroxypropoxy group. Can be mentioned.

  In the alkenyl group, the total number of carbon atoms of the substituent is usually 1 or more, usually 10 or less, preferably 8 or less. Examples of the group that may be substituted on the alkenyl group include an alkyl group having 1 to 4 carbon atoms, a phenyl group, a halogen atom, a sulfo group, and a carboxy group. Specific examples of the alkenyl group include a trans-2-carboxyethenyl group and a trans- (2-sulfophenyl) ethenyl group.

The alkylamino group is represented by —NR ⁶¹ R ⁶² , R ⁶¹ represents an alkyl group which may have a substituent, and R ⁶² represents a hydrogen atom or an alkyl group which may have a substituent. Represents. In the alkyl group, the total carbon number of the substituent is usually 1 or more, usually 4 or less, preferably 2 or less. Examples of the group that may be substituted on the alkyl group include an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, a sulfo group, a carboxy group, and a halogen atom. Specific examples of the alkylamino group include a methylamino group, an ethylamino group, a propylamino group, and a dimethylamino group.

The arylamino group is represented by —NR ⁶³ R ⁶⁴ , R ⁶³ represents a phenyl group or naphthyl group which may have a substituent, and R ⁶⁴ may have a hydrogen atom or a substituent. It represents a good alkyl group, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent. Examples of the total number of carbon atoms of the preferred substituents of the alkyl group and the substituents that may be present are the same as those exemplified for the alkyl groups of R ⁶¹ and R ⁶² . In the phenyl group, the total carbon number of the substituent is usually 6 or more, usually 10 or less, preferably 8 or less. In the naphthyl group, the total carbon number of the substituent is usually 10 or more, usually 14 or less, preferably 12 or less. Examples of the group that may be substituted on the phenyl group and the naphthyl group include an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, a sulfo group, a carboxy group, and a halogen atom. Specific examples of the phenylamino group include a phenylamino group, a diphenylamino group, and a phenylmethylamino group.

The acylamino group is represented by —NH—COR ⁶⁵ , and R ⁶⁵ may have an alkyl group which may have a substituent, a phenyl group which may have a substituent, or a substituent. Represents a good naphthyl group. In the alkyl group, the total carbon number of the substituent is usually 1 or more, usually 4 or less, preferably 2 or less. The phenyl group generally has 6 or more, usually 10 or less, preferably 8 or less carbon atoms in the substituent. In the naphthyl group, the total carbon number of the substituent is usually 10 or more, usually 14 or less, preferably 12 or less. Examples of the group which may be substituted on the alkyl group, the phenyl group and the naphthyl group include an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, a sulfo group, a carboxy group and a halogen atom. Specific examples of the acylamino group include an acetylamino group and a benzoylamino group.

The alkylcarbamoyl group is represented by —CO—NHR ⁶⁶ , and R ⁶⁶ represents an alkyl group which may have a substituent. Examples of the total number of carbon atoms of the preferred substituents of the alkyl group and the substituents that may be present are the same as those exemplified for the alkyl groups of R ⁶¹ and R ⁶² . Specific examples of the alkylcarbamoyl group include a methylcarbamoyl group and an ethylcarbamoyl group.

The arylcarbamoyl group is represented by —CO—NHR ⁶⁷ , and R ⁶⁷ represents a phenyl group which may have a substituent or a naphthyl group which may have a substituent. Examples of the total carbon number of the preferred substituents of the phenyl group and naphthyl group, and the substituents that may be present, are the same as those exemplified for the phenyl group and naphthyl group of R ⁶³ and R ⁶⁴ . Specific examples of the arylcarbamoyl group include a phenylcarbamoyl group and a naphthylcarbamoyl group.

The alkylsulfamoyl group is represented by —CO—NHR ⁶⁸ , and R ⁶⁸ represents an alkyl group which may have a substituent. Examples of the total number of carbon atoms of the preferred substituents of the alkyl group and the substituents that may be present are the same as those exemplified for the alkyl groups of R ⁶¹ and R ⁶² . Specific examples of the alkylsulfamoyl group include a methylsulfamoyl group and an ethylsulfamoyl group.

The arylsulfamoyl group is represented by —CO—NHR ⁶⁹ , and R ⁶⁹ represents a phenyl group which may have a substituent or a naphthyl group which may have a substituent. Examples of the total carbon number of the preferred substituents of the phenyl group and naphthyl group, and the substituents that may be present, are the same as those exemplified for the phenyl group and naphthyl group of R ⁶³ and R ⁶⁴ . Specific examples of the arylsulfamoyl group include a phenylsulfamoyl group and a naphthylsulfamoyl group.

The aromatic hydrocarbon group may have 1 to 5 of these substituents, preferably 1-2.
It is to have.
As the heterocyclic group, a group derived from a monocyclic or bicyclic heterocyclic ring is preferable. Examples of the atoms other than carbon constituting the heterocyclic group include a nitrogen atom, a sulfur atom, and an oxygen atom. When the heterocyclic group has a plurality of atoms constituting a ring other than carbon, these may be the same or different. Specific examples of the heterocyclic group include a pyridyl group, a quinolyl group, a thiazolyl group, a benzothiazolyl group, a quinolonyl group, a naphthalimidoyl group, a naphthostyryl group, and a group represented by the following formula.

In the above formula, R ⁴¹ represents a hydrogen atom, an alkyl group which may have a substituent, or a phenyl group which may have a substituent. Examples of the substituent include an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an amino group, an alkylamino group having 1 to 4 carbon atoms, a phenylamino group, and 1 to 7 carbon atoms. Acylamino group, nitro group, carboxy group, hydroxyl group, sulfo group, cyano group, halogen atom and the like. Of these, a pyridyl group, a quinolyl group or a phthalimidoyl group is preferred.

  Examples of the substituent that the heterocyclic group may have include an alkyl group that may have a substituent, an alkoxy group that may have a substituent, an amino group, and a substituent. And an alkylamino group which may have a substituent, an arylamino group which may have a substituent, an acylamino group which may have a substituent, a nitro group, a carboxy group, a hydroxyl group, a cyano group, a sulfo group, a halogen atom, etc. It is done. The total number of carbon atoms of the preferred substituents of the alkyl group, alkoxy group, alkylamino group, arylamino group, and acylamino group, examples of preferred substituents that may have, and preferred specific examples thereof include those in which A is an aromatic hydrocarbon group This is the same as those exemplified as the substituent that may be present. The substituent is preferably a hydroxyl group, a sulfo group or a carboxy group.

  The anisotropic film of the present invention is preferably formed by a wet film formation method as will be described later. In this film formation method, a solution containing an azo compound (hereinafter referred to as “coating liquid”). A step) of applying to a substrate. At this time, a polar group ρ is previously introduced into the surface of the substrate to be coated, and a structure having an interaction with the polar group ρ in A, specifically, an azo compound having a polar group σ and / or a heterocyclic group is prepared. It is preferable to use it. As the heterocyclic group, A itself may be a heterocyclic group which may have a substituent, or A may have a group containing a heterocyclic group as a substituent. Due to the non-covalent interaction between the polar group ρ and the polar group σ and / or the heterocyclic group, the azo compound molecule binds to the substrate at the site A which is the end of the molecule and is oriented perpendicular to the substrate. It becomes easy to do.

As a result, the tendency of the extinction coefficient k _z in the thickness direction in the anisotropic film of the present invention, the extinction coefficient k _x and k _y in the film plane direction is easily satisfied the formula (1) at a wavelength of 550nm There is.
Examples of the polar groups ρ and σ can each independently include a heteroatom or an atomic group having a heteroatom. Examples of the heteroatom include an oxygen atom, a nitrogen atom, a silicon atom, and a halogen atom. Can do. Specific examples of the atomic group having a hetero atom include a hydroxyl group, a carboxy group, an oxy group, an epoxy group, a glycidyl group, an oxycarbonyl group, a carbonyloxy group, a carbonyl group, an amino group, an ester group, a halogen group, and a cyano group. Group, amide group, imide group, sulfo group, carbonyloxycarbonyl group and the like.

Preferred combinations of polar groups ρ and σ include, for example, JM. Lehn, “Supramolecular
Chemistry ", VCH Verlagsgesellschaft (1995), M. Oh-e, H. Yokoyama, D. Kim," Mapping molecular conformation and orientation of polyimide surfaces for homeotropic liquid crystal alignment by nonlinear optical spectroscopy ", Physical Review E, 69, 051705, (2004), supervised by Haruo Kiryu, “Water-Based Coating”, CMC Publishing (2004)
And the like having combinations of interaction complementarity (international complementarity).

  For example, ether group-amino group, ether group-guanidinium group, ether group-imidazolium group, carboxy group-amino group, carboxy group-guanidinium group, carboxy group-pyridinium group, carboxy group-amide group, carboxy group-aziridine group Carboxy group-oxazoline group, carboxy group-carbodiimide group, carboxy group-carboxy group, amide group-amide group, phosphate group-amino group, phosphate group-guanidinium group, phosphate group-pyridinium group, barbituric acid group -2,4,6-triaminopyrimidine group, 2,6-diaminopyridine group-uracil group, hydroxyl group-amino group, cyano group-imide group, epoxy group-amino group, epoxy group-carboxy group, isocyanate group-hydroxyl group , Isocyanate group-amino group, carbonyl group-hydra Combination of emissions group preferably.

  Among these, in order for the interaction to work effectively even in an aqueous solution, a combination of relatively hydrophobic polar groups such as a combination of an amide group-amide group, a carbonyl group-hydrazine group, and a cyano group-imide group is more preferable. As a particularly preferred combination of polar groups, the polar group σ introduced into the molecular end of the azo compound is a cyano group, and the polar group ρ introduced into the substrate is an imide group possessed by the polyimide. Note that the polyimide may function as an alignment film provided on the substrate.

According to such a combination, the molecular long axis is easily oriented perpendicularly to the substrate by the interaction of the imide group and the cyano group, the extinction coefficient k _z in the film thickness direction, and the extinction coefficient in the in-film direction. k _x and _{k y} are easily satisfied the formula (1) at a wavelength of 550 nm.
Examples of the heterocyclic group that may have a substituent that interacts with the polar group ρ are the same as those in the case where A is a heterocyclic group. What has an interaction with the polar group ρ is a partial structure such as a pyridinium group, a 2,4,6-triaminopyrimidine group, a 2,6-diaminopyridine group, and an imide group which the heterocyclic group has. Therefore, among the combinations of polar groups described above, pyridinium group, 2,4,6-triaminopyrimidine group, 2,6-diaminopyridine group, imide group and the like are read as partial structures of the heterocyclic group, and the same manner. Preferred combinations can be selected.

  Specific examples of particularly preferable A are given below.

<B>
B represents a divalent aromatic hydrocarbon group which may have a substituent, or a divalent heterocyclic group.
As the aromatic hydrocarbon group for B, a phenylene group and a naphthylene group are preferable.
Examples of the substituent that the aromatic hydrocarbon group may have include an alkyl group that may have a substituent, an alkoxy group that may have a substituent, a hydroxyl group, a nitro group, a sulfo group, A carboxy group, a halogen atom, an amino group, an alkylamino group which may have a substituent, an arylamino group which may have a substituent, an acylamino group which may have a substituent, a carbamoyl group, Examples thereof include an alkylcarbamoyl group which may have a substituent, an arylcarbamoyl group which may have a substituent, and a cyano group.

  In addition, the alkyl group which may have the substituent, the alkoxy group which may have the substituent, the alkylamino group which may have the substituent, the substituent Preferred arylamino group, acylamino group optionally having substituent (s), alkylcarbamoyl group optionally having substituent (s), preferred carbon number of arylcarbamoyl group optionally having substituent (s) Examples of the substituents that may be present and specific examples thereof are the same as those described in the case where the A is an aromatic hydrocarbon group. Among them, a group having a small polarity such as an alkyl group, an alkoxy group, a hydroxyl group, or a halogen atom or a group having hydrogen bonding property is preferable from the viewpoint of improving the associative property by interaction in forming a lyotropic liquid crystal, and from the viewpoint of water solubility Is preferably a sulfo group.

The aromatic hydrocarbon group may be unsubstituted or may have 1 to 5 of these substituents, and preferably has 1 to 2 substituents.
The heterocyclic group for B is preferably a monocyclic or bicyclic heterocyclic ring-derived group. Examples of the atoms other than carbon constituting the heterocyclic group include a nitrogen atom, a sulfur atom and an oxygen atom, and a nitrogen atom is particularly preferable. When the heterocyclic group has a plurality of atoms constituting a ring other than carbon, these may be the same or different.

Specific examples of the heterocyclic group include a pyridinediyl group, a quinolinediyl group, an isoquinolinediyl group, a benzothiadiazolediyl group, and a phthalimidodiyl group. Among these, a quinoline diyl group and an isoquinoline diyl group are preferable.
Examples of the substituent that the heterocyclic group may have include an alkyl group that may have a substituent, an alkoxy group that may have a substituent, an amino group, and a substituent. And an alkylamino group which may have a substituent, an arylamino group which may have a substituent, an acylamino group which may have a substituent, a nitro group, a carboxy group, a hydroxyl group, a cyano group, a sulfo group, a halogen atom, etc. It is done. Among these, a hydroxyl group, a sulfo group, and a carboxy group are preferable. The total number of carbon atoms of the preferred substituents of the alkyl group, alkoxy group, alkylamino group, arylamino group, and acylamino group, examples of preferred substituents that may have, and preferred specific examples thereof include those in which A is an aromatic hydrocarbon group This is the same as those exemplified as the substituent that may be present. The heterocyclic group may be unsubstituted or may have 1 to 5 of these substituents, and is preferably unsubstituted or has 1 to 2 of the substituents.

  Specific examples of particularly preferable B are given below.

<R ¹ and R ² >
R ¹ and R ² are each independently a hydrogen atom, an optionally substituted alkyl group, an optionally substituted phenyl group, an optionally substituted acyl group, Or the triazinyl group which may have a substituent is represented.
In the alkyl group, the total carbon number of the substituent is usually 1 or more and 6 or less, preferably 4 or less. In the phenyl group, the total carbon number of the substituent is usually 6 or more, usually 12 or less, preferably 10 or less, more preferably 8 or less.

Examples of the substituent that the alkyl group and the phenyl group may have include a hydroxyl group, a carboxy group, and a sulfo group.
The acyl group which may have a substituent for R ¹ and R ² is represented by —NH—COR ⁷¹ , and R ⁷¹ has an alkyl group which may have a substituent and a substituent. Represents a good phenyl group. In the alkyl group, the total carbon number of the substituent is usually 1 or more, usually 4 or less, preferably 2 or less. The phenyl group generally has 6 or more, usually 10 or less, preferably 8 or less carbon atoms in the substituent. Examples of the group which may be substituted on the alkyl group and the phenyl group include an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, a sulfo group and a carboxy group. Specific examples of the acyl group include an acetyl group and a benzoyl group.

The triazinyl group which may have a substituent of R ¹ and R ² has a total carbon number of the substituent of usually 3 or more, usually 21 or less, preferably 12 or less. Examples of the group which may be substituted on the triazinyl group include an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an amino group, an alkylamino group having 1 to 8 carbon atoms, phenylamino Group, phenoxy group and hydroxyl group. These substituents may be further substituted with a sulfo group, a hydroxyl group, an amino group, a carboxy group, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms.

In particular, —NR ¹ R ² includes an amino group in which R ¹ and R ² are hydrogen atoms, an alkylamino group in which R ¹ is a hydrogen atom and R ² is an alkyl group, R ¹ is a hydrogen atom, and R ² is phenyl. A phenylamino group which is a group is preferable, and from the viewpoint that lyotropic liquid crystallinity is easily developed, an alkyl group having a hydrogen atom, a carboxy group or a sulfo group, or an acyl group having a carboxy group or a sulfo group is preferable. In particular, from the viewpoint of easily exhibiting lyotropic liquid crystal properties at a relatively low concentration and excellent process suitability, both R ¹ and R ² are preferably hydrogen atoms.

<M>
m represents 0 or 1.
<P>
p represents an integer of 0 to 3. When p is 2 to 3, a plurality of B present in one molecule may be the same or different from each other.
A larger p is preferred because the stimulating purity of the azo compound tends to be smaller, but a smaller p is preferred from the viewpoint of orientation. Therefore, p is preferably 1 from the balance of hue and orientation.
Particularly preferable examples of the azo compound represented by the general formula (2) include those described in the following general formula (3). In the following formula, (B ¹ ) represents an arbitrary one of B described above.

In addition, azo compounds represented by the following general formulas (4) to (9) are preferable specific examples. In the following ^{formulas, (B 2) ~ (B} 7) shows any of the above-mentioned B.

Among the azo compounds, compounds represented by the above general formula (3) or (9) having a cyano group at the molecular end are more preferable.
Among these, more specifically, the following azo compounds are preferably mentioned because they have high associative properties and lyotropic liquid crystallinity and low stimulation purity.

(Iv) Other azo compounds In the anisotropic film of the present invention, examples of the azo compound that can be used in addition to the azo compound represented by the general formula (2) described in (iii) above include (i) And an azo compound having excellent lyotropic liquid crystallinity and the like, such as the stimulation purity, the angle between the absorption axis and the molecular long axis, and the like described in detail in (ii).
For example, the following azo compounds are not necessarily small in excitation purity, but have high associative properties and lyotropic liquid crystal properties, and can be used for the anisotropic film of the present invention. Anisotropic films containing these azo compounds also satisfy the above formula (1). However, in order to further improve the properties of the anisotropic film, the azo compounds represented by the above general formula (2) and other azo compounds When used in combination with a compound, the stimulation purity is suppressed, and it can be used more preferably.

  When the anisotropic film of the present invention is produced by a wet film-forming method described later, the azo compound as described in detail in (iii) or (iv) is usually converted into a free acid. The concentration is 20% by weight or more, preferably 30% by weight or more, and more preferably 40% by weight or more. When there is little content of the compound of this invention, the orientation in a lyotropic liquid crystal state will become inadequate, and it may show the property which is not preferable as an anisotropic film | membrane.

[Other components contained in the anisotropic film of the present invention]
The anisotropic film of the present invention may further contain other compounds as components unless the effects are significantly impaired. For example, in the case of being produced using a wet film formation method described later, a surfactant added for the purpose of improving wettability during film formation, the purpose of improving orientation, etc. Added for the purpose of imparting insolubility to water, sugar compounds, amino acids, polymer compounds added for the purpose of imparting film strength and the like, monomers thereof, or polymerization initiators. May be contained. These compounds may contain 1 type, and may contain 2 or more types by arbitrary combinations and ratios.
Among these, it is preferable to contain sugar alcohols or saccharides, and these will be described in more detail in the method for producing an anisotropic film described later. For example, the saccharides described in JP-A-2006-098958 Can be mentioned.

  Further, it may further contain another compound that functions as a dye as long as the orientation of the azo compound is not lowered. Thereby, anisotropic films having various hues can be produced. Examples of preferable compounds as a coloring matter include C.I. I. Direct Yellow 12, C.I. I. Direct Yellow 34, C.I. I. Direct Yellow 86, C.I. I. Direct Yellow 142, C.I. I. Direct Yellow 132, C.I. I. Acid Yellow 25, C.I. I. Direct Orange 39, C.I. I. Direct Orange 72, C.I. I. Direct Orange 79, C.I. I. Acid Orange 28, C.I. I. Direct Red 39, C.I. I. Direct Red 79, C.I. I. Direct Red 81, C.I. I. Direct Red 83, C.I. I. Direct Red 89, C.I. I. Acid Red 37, C.I. I. Direct Violet 9, C.I. I. Direct Violet 35, C.I. I. Direct Violet 48, C.I. I. Direct Violet 57, C.I. I. Direct Blue 1, C.I. I. Direct Blue 67, C.I. I. Direct Blue 83, C.I. I. Direct Blue 90, C.I. I. Direct Green 42, C.I. I. Direct Green 51, C.I. I. Direct Green 59, Alizarin Red S and the like can be mentioned.

  By appropriately adjusting such various components, the three-dimensional extinction coefficient of the anisotropic film of the present invention can be adjusted so as to satisfy the formula (1).

[Method for producing anisotropic film]
Hereinafter, a typical method for producing an anisotropic film of the present invention will be described, but the present invention is not limited to the following as long as the effects of the present invention are not significantly impaired.
The anisotropic film may be produced using any known method as long as the anisotropic material such as the azo compound can be formed into a film shape. It is preferable to obtain a film by a wet film forming method using a solution or a dispersion liquid (hereinafter sometimes simply referred to as “coating liquid”).
<Coating solution>
The concentration of the anisotropic material in the coating liquid depends on the solubility of the anisotropic material and the formation concentration of the supramolecular structure such as the lyotropic liquid crystal state, but is usually 0.1% by weight or more, preferably 0.5 % By weight or more, usually 50% by weight or less, preferably 30% by weight or less. Below this range, a uniform anisotropic film may not be formed. On the other hand, if it exceeds this range, the viscosity of the coating solution may increase, making it difficult to handle.

The coating liquid contains a solvent in addition to the anisotropic material. The solvent may be selected in consideration of the operability of the coating liquid in the wet film forming method described later, the manifestation of the liquid crystal state of the anisotropic material, and the like.
Examples of solvents are water, water-miscible organic solvents, or mixtures thereof. Specific examples of water-miscible organic solvents include lower alcohols having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; polyhydric alcohols such as ethylene glycol, diethylene glycol, and glycerin; methyl cellosolve, ethyl Cellosolves such as cellosolve; aprotic solvents such as N-methylpyrrolidone and N, N-dimethylformamide, or a mixture of two or more of them. In addition, a solvent may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

The coating liquid may contain other components in addition to the solvent. Moreover, these other components may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.
Examples of other components include those similar to the other components that may be contained in the anisotropic film of the present invention. For example, water-soluble additives such as sugars and amino acids are preferred. Can be mentioned. Among these, sugar alcohols such as threitol, meso-erythritol, ribitol, arabitol, xylitol, and inositol, and sugars such as maltose and maltotriose are preferable.
These additives, for example, interact with the azo compound having the lyotropic liquid crystal property represented by the general formula (2) and help the long axis of the compound molecule be aligned perpendicular to the substrate. There is work. This action makes it easy for the three-dimensional extinction coefficient of the anisotropic film of the present invention to satisfy the formula (1).
For example, when a compound having an elongated molecular shape represented by the general formula (2) is used as an anisotropic material, the compound must be used without any external factor or action in the anisotropic film forming process. The long axis of the molecule is easily oriented in parallel to the substrate, and it is difficult to satisfy the formula (1). These additives are considered to interact with the hydroxyl group of the compound to make the elongated molecular shape of the compound close to a disk-like molecule. This pseudo effect suppresses the long axis of the compound molecule from being oriented parallel to the substrate, and the long axis of the compound molecule with respect to the substrate in the anisotropic film formation process, particularly the drying process. This is considered to have the effect of vertically aligning.
Among sugar alcohols or sugars, those having 5 or more carbon atoms, such as ribitol, arabitol, xylitol, inositol, maltose, maltotriose, etc., are difficult to bleed out (deposit) on the anisotropic film surface after drying. Therefore, it is more preferable. In addition, the larger the number of hydroxyl groups in the sugar alcohol or saccharide molecule, the stronger the function of orienting the long axis of the compound molecule perpendicular to the substrate. Therefore, oligosaccharides such as maltose and maltotriose are used. However, it is possible to select an appropriate one from the viewpoint of cost and availability. Further, different sugar alcohols and sugars may be mixed and used. From the viewpoint of suppressing bleed-out to the anisotropic film surface after drying, it is preferable to use a mixture.

The concentration of the additive in the coating solution is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 1% by weight or more, preferably 2% by weight or more, and usually 30% by weight or less, preferably 20%. % By weight or less. Further, from the viewpoint of interaction with the azo compound represented by the general formula (2), 10 to 100 parts by weight of the additive is added to the azo compound 100 in the coating solution. It is preferable. If it is too little or too much, the orientation may be impaired.

Examples of other components include additives such as surfactants. The surfactant is used as necessary in order to improve the wettability to the substrate surface and the coating property when the coating liquid is applied to the substrate in forming the anisotropic film.
As the surfactant, any of an anionic surfactant, a cationic surfactant, and a nonionic surfactant can be used. Moreover, surfactant may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
The concentration of the surfactant in the coating solution is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.01% by weight or more, preferably 0.05% by weight or more, and usually 0.5% by weight. % Or less, preferably 0.2% by weight or less.

  Further, the coating liquid may contain other anisotropic materials. Examples thereof include chromonic liquid crystal compounds described in R. Hentschke, P.J.B. Edwards, N. Boden, R.J. Bushby, Macromol. Symp., 81, 361-367 (1994) and the like. These anisotropic materials may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

<Wet deposition method>
The anisotropic film of the present invention is preferably formed by a wet film forming method.
The wet film forming method is a process including a film forming process for forming the coating liquid, a drying process for removing the solvent, and an insolubilizing process for water. Another process may be performed between the film forming process and the drying process, and the insolubilization process may be omitted. In the anisotropic film, the anisotropic material is usually oriented in the film, but the anisotropic material may be oriented in any of the film forming process and the drying process.

Specifically, a known method such as a method of forming a coating solution after forming the coating solution and drying and removing the solvent can be used. Hereinafter, this method will be described in more detail.
(Film formation process)
The film forming step is a step of forming a film by applying the coating liquid. Here, a case where an anisotropic film is formed on a substrate such as a glass plate by the film forming process will be described as an example. Note that as long as film formation is possible, the film is not limited to a substrate and can be formed on an arbitrary base material.

Although there is no restriction | limiting in a base material, For example, glass, a triacetate, an acryl, polyester, a triacetyl cellulose, a urethane-type film, or cyclic polyolefin etc. are mentioned.
For example, when the azo compound represented by the general formula (2) is used as the anisotropic material, the polar surface σ and / or the heterocyclic group which the molecular end A of the azo compound has on the surface of the base material It preferably has a polar group ρ having an action. By utilizing such an interaction, the three-dimensional extinction coefficient of the anisotropic film of the present invention easily satisfies the formula (1).

  The method for introducing the polar group ρ into the substrate is described in, for example, “Surface and Interface Engineering System” (Fuji Techno System, (2005), upper volume, p.51 and lower volume, p.689). As described above, there are dry processing such as discharge processing, high energy ray irradiation, flame processing, vapor deposition and ion implantation and wet processing such as chemical processing, graft polymerization, polymer coating and electrodeposition. Among them, a polymer coating is preferable from the viewpoint that an arbitrary polar group ρ can be introduced, surface uniformity, and easy orientation treatment.

In addition, in order to control the orientation direction, an orientation treatment layer is formed on the surface of the base material by a known method described in “Liquid Crystal Handbook” (Maruzen Co., Ltd., issued on October 30, 2000), pages 226 to 239. It is preferable to perform an alignment treatment to form the film. By performing the alignment treatment, it is possible to suppress undesirable effects such as the anisotropic material forming minute domains having different alignment directions to scatter visible light.
In addition, when the said polar group (rho) is an imide group which a polyimide has, the polyimide layer provided as an orientation processing layer may serve as this. Since the polyimide layer has been used for a long time in the field of liquid crystal displays, the alignment treatment technology has been completed, and since it has high durability, it is particularly preferable as the alignment treatment layer.

  There is no restriction | limiting in the specific method of apply | coating a coating liquid on a base material. Specific examples of the coating method include Yuji Harasaki, “Coating Engineering” (Asakura Shoten Co., Ltd., published on March 20, 1971) pp. 253-277, supervised by Kunihiro Ichimura, “Creation and Application of Molecular Cooperative Materials” ( CMC Publishing Co., Ltd., published March 3, 1998) Known methods described on pages 118-149, etc., and Yuji Harasaki's "Coating Method" (Tsubaki Shoten, published October 30, 1979) 3 pages ( Table 1-2) and each coater system described on pages 6 to 154, and spin coating, spray coating, bar coating, roll coating, blade coating, free span coating, die coating, and the like. .

The operating conditions for performing the coating are arbitrary, but it is preferable to control so as to maintain a high-order molecular alignment state formed based on high liquid crystallinity due to self-organization of the anisotropic material. .
Specifically, the temperature at the time of application on the substrate is usually preferably 0 ° C. or higher, and is usually 80 ° C. or lower, and particularly preferably 40 ° C. or lower. Moreover, the humidity at the time of application is usually 10% RH or more, preferably 30% RH or more, and usually 80% RH or less.
Note that RH is an abbreviation for Relative humidity, and% RH is relative humidity.

(Drying process)
After the coating step, the coating film formed on the substrate is dried to remove the solvent. At this time, it is preferable that the anisotropic material is aligned with the removal of the solvent and exhibits lyotropic liquid crystallinity.
In particular, when the azo compound represented by the general formula (2) is used, the interaction between the polar group σ and / or the heterocyclic group at the molecular end A of the azo compound and the polar group ρ of the substrate is a short-range mutual interaction. Since the liquid crystallinity is applied in advance, the orientation state is fixed without approaching both polar groups, and the three-dimensional extinction coefficient of the anisotropic film of the present invention is not necessarily strong. Is considered to be difficult to satisfy the formula (1). Therefore, when the solution showing lyotropic liquid crystallinity is applied with an isotropic phase by diluting with a solvent or the like, and the lyotropic liquid crystal phase is shown as the solvent is removed in the drying step, the molecular end A of the azo compound is obtained. Interaction between the polar group σ and / or the heterocyclic group and the polar group ρ of the substrate tends to occur. As a result, a liquid crystal phase domain is formed and grown in a state where the polar group σ and / or the heterocyclic group of the molecular end A of the azo compound faces the substrate, and the three-dimensional extinction coefficient of the anisotropic film of the present invention Is considered to satisfy the formula (1).

The drying conditions are arbitrary, and may be natural drying, heat drying, reduced pressure drying, or a combination thereof, but a higher-order molecular alignment state formed based on high lyotropic liquid crystallinity due to self-organization of anisotropic material It is preferable to control so as to maintain the above.
Specifically, the temperature during drying in the drying step is usually 0 ° C. or higher, preferably 10 ° C. or higher, and usually 120 ° C. or lower, particularly preferably 110 ° C. or lower. Further, the humidity during drying in the drying step is usually 10% RH or more, preferably 30% RH or more, and usually 90% RH or less. It is more preferable to avoid a rapid temperature rise when the temperature is raised during drying.

(Insolubilization process)
The insolubilization step means a treatment step in which ions having a lower valence are replaced with ions having a higher valence (for example, monovalent ions are replaced with multivalent ions). More specifically, for example, known methods such as processing steps described in Yutaka Hosoda, “Theoretical Manufacturing Dye Chemistry” (Gihodo, 1957), pages 435 to 437, etc. are used. Preferably, the obtained anisotropic film is treated by a method described in JP-A No. 2007-241267, etc. to form a film that is insoluble in water, such as ease of post-processing and durability. It is preferable from the viewpoint.

As described above in detail, the anisotropic film characterized in that the three-dimensional extinction coefficient of the present invention satisfies the formula (1) is, for example,
-Use an azo compound having an excitation purity of 20% or less.
An azo compound represented by the general formula (2) and having lyotropic liquid crystallinity is used.
-An azo compound whose angle between the absorption axis and the molecular long axis is 10 degrees or less is used.
In particular, when a film is formed by a wet film forming method, an azo compound having a polar group or a heterocyclic group at the molecular end is used, and a polar group that interacts with the polar group or the heterocyclic group is introduced to the substrate surface.
-An orientation treatment layer is provided on the substrate surface, particularly when the film is formed by a wet film formation method.
In particular, when a film is formed by a wet film forming method, a component having a function of helping the long axis of the azo compound molecules to be aligned perpendicularly to the substrate is added to the coating solution.
In particular, when a film is formed by a wet film forming method, an azo compound having an isotropic property is adjusted at the time of coating so that it is aligned with the removal of the solvent in the drying process and exhibits lyotropic liquid crystallinity.
It can obtain by using methods, such as these, combining suitably.

The anisotropic film of the present invention is preferably formed by a wet film formation method, and among the various methods described above, (a) an azo compound having a polar group at the molecular end is formed using the wet film formation method. A method of forming a film on a substrate in which a polar group that interacts with the polar group is introduced into the substrate; and (b) a component having a function of helping the long axis of the azo compound molecule to be oriented perpendicular to the substrate. A combination of techniques for adding to the coating solution is preferably used. Further, (c) a method of providing an alignment treatment layer on the substrate surface and / or (d) an azo compound having isotropic properties at the time of coating is adjusted so as to exhibit lyotropic liquid crystal properties by aligning with the removal of the solvent in the drying process. The techniques to be combined can be preferably combined.
In particular, an isotropic coating solution containing an azo compound represented by the following general formula (3) or (9) and having lyotropic liquid crystallinity and a sugar alcohol or a saccharide is applied to the alignment-treated polyimide layer, By forming a film so as to exhibit lyotropic liquid crystallinity in the drying step, an anisotropic film having high orientation and a three-dimensional extinction coefficient that satisfies the above formula (1) can be obtained.

[Use of anisotropic film of the present invention]
The anisotropic film of the present invention can be applied to various optical elements by adding various post processes as necessary.
The anisotropic film of the present invention is preferably used for applications such as a viewing angle compensation film, a polarizing film, a retardation film, and a conductive anisotropic film, and is used for a viewing angle compensation film, a retardation film, and a polarizing film. More preferably, it is particularly preferable to use for a viewing angle compensation film. In particular, if _k z / _{k x} and _k z / _{k y} anisotropic film is large, _{specifically,} in the case of _k z / k _x ≧ 2 and _k z / _{k y} ≧ 2, of the present invention Since the effect obtained by using an anisotropic film becomes large, it is desirable.

  When used as such an optical element, for example, the anisotropic film of the present invention can be used with a protective layer provided if necessary. This protective layer is formed by lamination with a transparent polymer film such as triacetate, acrylic, polyester, polyimide, triacetylcellulose, norbon-based, cyclic polyolefin-based or urethane-based film, and is practically used as an optical element. be able to.

The anisotropic film of the present invention can be formed on a high heat resistant substrate such as glass. Accordingly, optical elements such as a high heat resistance viewing angle compensation film, a polarizing film, and a retardation film can be obtained, so that not only a liquid crystal display, an organic EL display, etc., but also a high heat resistance such as a liquid crystal projector, an in-vehicle display panel, etc. It can also be suitably used for applications where properties are required.
In addition, since the anisotropic film of the present invention is excellent in durability, application to an In-Cell type polarizing film, an In-Cell type retardation film, or the like of a liquid crystal element can be expected.

  Furthermore, functionalization as various anisotropic films such as refractive anisotropy and conduction anisotropy can be performed by selecting a film forming process, a substrate, and a coating liquid containing an anisotropic material as necessary. It becomes possible and can be applied to various types of optical elements that can be used for various purposes.

2. Viewing Angle Compensation Film The viewing angle compensation film of the present invention is formed of the anisotropic film of the present invention.
The viewing angle compensation film of the present invention is usually produced on a suitable substrate in the same manner as the above-mentioned anisotropic film production method and used as an element (hereinafter referred to as “viewing angle compensation element”). There is). As a base material, what was illustrated as a base material used for preparation of the said anisotropic film | membrane is mentioned, for example. The substrate is preferably subjected to an orientation treatment in the same manner as in the method for producing the anisotropic film.

Moreover, as a structure of a viewing angle compensation element, you may equip 1 or 2 or more members other than the said base material. For example, a protective layer is mentioned. This protective layer is a layer provided as necessary when the mechanical strength of the viewing angle compensation film is low. Although there is no restriction | limiting in the specific structure, For example, it forms similarly to the case of the said anisotropic film | membrane.
Further, the viewing angle compensation element is, for example, an adhesive layer, an antireflection layer, an alignment film, a polarizing film, a layer having a function as a retardation film, a layer having a function as a brightness enhancement film, or a function as a reflecting film. A layer having various optical functions such as a layer having a function as a transflective film and a layer having a function as a diffusion film may be laminated and used as a laminate. In this case, the layers and films can be stacked by, for example, a wet film forming method. Moreover, you may laminate | stack the said layer and film | membrane in what order according to a use. When laminated in this way, the optical element of the present invention is configured as a laminate. Of these, the viewing angle compensation element of the present invention preferably has a polarizing film.

These layers having an optical function can be formed, for example, by the following method.
The layer having a function as a retardation film is subjected to, for example, a stretching process described in JP-A-2-59703, JP-A-4-230704, or a process described in JP-A-7-230007. Or can be formed.
In addition, the layer having a function as a brightness enhancement film may be formed by, for example, a method of forming micropores described in JP-A Nos. 2002-169025 and 2003-29030, and / or a central wavelength of selective reflection. Can be formed by superimposing two or more cholesteric liquid crystal layers having different values.

Furthermore, the layer which has a function as a reflective film or a transflective film can be formed using the metal thin film obtained by vapor deposition, sputtering, etc., for example.
The layer having a function as a diffusion film can be formed, for example, by coating the protective layer with a resin solution containing fine particles.
The layer having a function as a retardation film or an optical compensation film can be formed by applying and aligning a liquid crystal compound such as a discotic liquid crystal compound or a nematic liquid crystal compound.

3. Polarizing Element The polarizing element of the present invention comprises the anisotropic film of the present invention, the viewing angle compensation film or viewing angle compensation element of the present invention, and a polarizing film (polarizing plate).
By combining the anisotropic film of the present invention or the viewing angle compensation film of the present invention with, for example, a stretched polarizing plate using iodine or a dye, a wire grid polarizing plate, etc., as a polarizing element having excellent viewing angle characteristics Function.
Although there is no restriction | limiting in these combinations, For example, the protective film (it serves also as a base material in this case) provides an orientation layer by methods, such as rubbing and photo-alignment, On this, the anisotropic film or viewing angle of this invention After the formation of the compensation film, it is preferable that the polarizing plate and the protective film are laminated in order via the adhesive layer. By such a method, a polarizing element including the polarizing plate and the anisotropic film or the viewing angle compensation film of the present invention can be constituted by sandwiching the upper and lower sides with two protective films.

  In addition to the anisotropic film of the present invention or the viewing angle compensation film and the polarizing film of the present invention, the polarizing element of the present invention may further include another member or the like. Examples of the other member include the same members as those in the case of the viewing angle compensation element.

4). Liquid crystal display device The liquid crystal display device of the present invention comprises the anisotropic film of the present invention, the viewing angle compensation film of the present invention, the viewing angle compensation element of the present invention or the polarizing element of the present invention. Features.
In the following, a configuration example and a manufacturing method will be described with reference to an example in which the anisotropic film of the present invention is formed by a wet film formation method and used as a viewing angle compensation film. However, the present invention is limited to these examples. Without being done, it can be inserted at an arbitrary position according to its use and process.
In the case of the so-called in-cell type having the anisotropic film of the present invention in the liquid crystal cell, a pixel electrode formed on the flattening layer on the TFT side like the in-cell type polarizer described in JP-A-2006-184325 The coating liquid may be applied on the top, or the coating liquid may be applied on the planarizing layer before forming the pixel electrode as described in JP-A-2008-151817. In addition, as described in JP-A-2006-330215, a coating solution may be applied on the overcoat layer of the color filter, or on the TFT side and the color filter side as described in JP-A-2006-309185. It may be provided on both sides.

  In the case of the so-called out-cell type having the anisotropic film of the present invention outside the liquid crystal cell, the polarizing element of the present invention may be used instead of a normal polarizing plate. Further, as described in JP-A-2006-330215, a coating solution may be applied to a diffusion plate or the like on the light source unit side, or a coating solution may be applied to a glass substrate of a liquid crystal cell.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, and can be arbitrarily modified and implemented without departing from the gist of the present invention. . In the following description of the examples, “parts” means “parts by weight” unless otherwise specified.
[Example 1]
<1> Synthesis of Azo Compound From 4-aminobenzonitrile and 8-amino-2-naphthalenesulfonic acid (1,7-Cleaves acid), a conventional method (for example, “New Dye Chemistry” written by Yutaka Hosoda, 12 The monoazo compound was produced through a diazotization and coupling process according to (published by Gihodo on May 21) (see page 396, page 409). Similarly, the obtained monoazo compound was diazotized by a conventional method, subjected to a coupling reaction with 7-amino-1-naphthol-3,6-disulfonic acid (RR acid), and salted out with sodium chloride. The aqueous solution of the azo compound obtained in the salt form is treated with a strongly acidic ion exchange resin, the azo compound is acidified in the form of a free acid, and then the azo compound acidic group is neutralized with an aqueous lithium hydroxide solution to perform salt exchange. Thus, a lithium salt of an azo compound represented by the following formula (10) was obtained.

<2> Calculation of stimulation purity of azo compound 0.1 part of lithium salt of the azo compound represented by the above formula (10) is added to 99.9 parts of water to obtain a concentration of 1000 ppm, and after stirring and dissolving, the solution is filtered to obtain an aqueous solution of the azo compound. Got. This aqueous solution was poured into a quartz square cell (cuvette) having an optical path length of 0.1 mm. The visible light wavelength transmittance (single transmittance: Ts) of the aqueous solution of the azo compound injected into this cuvette was measured with a spectrophotometer, and was measured under the CIE1964 XYZ color system, D65 standard light source according to the method of JIS-Z-8701. Chromaticity xy was calculated and used as chromaticity coordinates C1.
Further, from the chromaticity diagram, the chromaticity coordinate N of the D65 standard light source and the obtained chromaticity coordinate C1 of the aqueous solution of the azo compound are each connected by a straight line, and the wavelength corresponding to the intersection with the extended spectral locus is defined as the main wavelength, The stimulation purity (pe1) of the aqueous solution of the azo compound was calculated from the ratio of the points (N, C1 and the intersection). As shown in Table 1 below, the obtained stimulus purity was 9%, and it was an azo compound having a low chroma and achromatic color.

<3> Preparation of anisotropic film 71.8 parts of water, 20 parts of lithium salt of the azo compound represented by the above formula (10), 1 part of Aldrich Red S manufactured by Aldrich after desalting and purification, Tokyo After stirring and dissolving 7.2 parts of meso-erythritol manufactured by Kasei Co., Ltd., filtered and observed with a polarizing microscope, it was confirmed from the schlieren texture that the azo compound represented by the above formula (10) exhibits lyotropic liquid crystallinity.

60 parts of the lyotropic liquid crystal solution of the obtained azo compound and 4650.1 parts of Surfinol manufactured by Nissin Chemical Industry Co., Ltd. were diluted with 39.9 parts of water to obtain a coating liquid for producing an anisotropic film. When the obtained coating solution was observed with a polarizing microscope, no texture was seen and the solution was isotropic and uniform.
A glass substrate (75 mm × 75 mm, thickness 1 mm) was prepared by forming a polyimide alignment film (film thickness of about 800 mm) on the surface by rubbing with a cloth. The above coating solution was spin-coated on this, and then naturally dried in an environment of 23 ° C. and 50% RH to obtain an anisotropic film 1. The spin coating was performed at a rotational speed of 1,000 rpm for 5 seconds, followed by 2,500 rpm for 15 seconds.
About the obtained anisotropic film | membrane, when the film thickness was measured from the level | step difference of the part with a film | membrane on a board | substrate using the scanning interferometry surface shape measuring device New View 100 by Zygo, a film thickness was 390 nm. Met.

<4> Calculation of Stimulus Purity of Anisotropic Film The optical principal axis y in the film of the anisotropic film is set at 0 azimuth, azimuth (φ) 0, 45, 90 degrees, polar angle (θ) 45 After measuring the transmittance in a p-polarized light incident optical system with a spectrophotometer, the chromaticity xy under a D65 standard light source was calculated according to the method of JIS-Z-8701 and set as the chromaticity coordinate C2.

Further, from the chromaticity diagram, the chromaticity coordinate N of the D65 standard light source and the obtained chromaticity coordinate C2 of the anisotropic film are respectively connected by a straight line, and the wavelength corresponding to the intersection with the extended spectral locus is set as the main wavelength, The stimulation purity (pe2) of the anisotropic film was calculated from the ratio of points (N, C2 and the intersection). The obtained stimulus purity is shown in Table 1.
The anisotropic film of the present invention has a low saturation achromatic color, and was preferable as a viewing angle compensation film.

<5> Calculation of three-dimensional complex refractive index A spectroscopic ellipsometer ("UVISEL" manufactured by Horiba Joban Yvon) was used to calculate the three-dimensional complex refractive index of the anisotropic film of the present invention. A sample was placed in a state where the application direction of the anisotropic film was parallel to the incident light, and a wavelength region of photon energy of 0.6 to 3.1 eV was measured at an incident angle of 60 °.

  First, only the substrate was measured. Since the substrate used in this example is a glass substrate covered with a polyimide alignment film, the polyimide alignment film is analyzed with a model using a single Lorentz vibrator dispersion formula, and the optical constant of the substrate is determined. Obtained. Then, the measurement of the substrate provided with the anisotropic film was performed, and the biaxial anisotropy having a three-dimensional complex refractive index laminated on the substrate having the optical constant obtained previously with respect to the anisotropic film It was analyzed as a membrane. At this time, the measurement data was optimally fitted with a model using a plurality of Lorentz vibrator dispersion formulas, where the coating parallel direction was the x axis, the vertical direction was the y axis, and the film depth direction was the z axis. The vibration frequency given as the initial value in the Lorentz vibrator dispersion type was determined based on the absorption spectrum by the spectrophotometer.

The result of this analysis, was calculated anisotropic film x, y, the complex refractive index of the z-axis _{n x -ik x, n y -ik} y, a n z -ik _z.
Table 3 below shows the three-dimensional extinction coefficients k _x , k _y, and k _z at a wavelength of 550 nm. Similarly, k _x , k _y , and k _z were obtained at wavelengths of 450 nm and 650 nm, and the obtained values are shown in Table 2. Anisotropic film of the present invention _is a k z> _{k x} and _k z> _{k y, further} found to have a _{k z / k x> 2,} k z / k y> 2 and high anisotropy It was.

<6> Preparation and Analysis of Polarizing Element On the anisotropic film, an iodine polarizing plate “HEG-1425” manufactured by Nitto Denko Corporation was attached so that the absorption axis overlapped with the y axis of the anisotropic film, and polarizing element 1 Was made.

The absorption axis of the iodine polarizing plate and the y-axis of the anisotropic film are set at an azimuth angle (φ) of 0 degrees, and non-polarized light is incident from the substrate side of the anisotropic film at polar angles of 0, 15, and 30 degrees. The single transmittance (Ts) in the light wavelength region was measured. Furthermore, s-polarized light and p-polarized light were incident from the same direction, and the respective transmittance ratios were obtained as contrast ratios (CR).
Table 3 shows the obtained single transmittance and contrast ratio. It has been found that the polarizing element of the present invention has a good viewing angle characteristic with a contrast ratio of nearly 10,000 even at a polar angle of 30 degrees. It was also found that the decrease in single transmittance was sufficiently suppressed despite the incidence of light from the anisotropic film side.
[Comparative Example 1]
A polarizing element 2 was produced by pasting an iodine polarizing plate “HEG-1425” manufactured by Nitto Denko Corporation on a glass substrate instead of an anisotropic film. With respect to this polarizing element 2, the single transmittance (Ts) and the contrast ratio (CR) were measured in the same manner as in Example 1.

Table 3 shows the obtained single transmittance and contrast ratio. The polarizing element 2 had a contrast ratio of less than 10,000 from a polar angle of 15 degrees and a low viewing angle characteristic.
The relationship between the contrast ratio (CR) and the polar angle (θ) of the polarizing element 1 of Example 1 and the polarizing element 2 of Comparative Example 1 is shown in the graph of FIG. From the results of Example 1 and Comparative Example 1, it was found that viewing angle characteristics can be improved by combining the anisotropic film of the present invention with an O-type polarizing plate.

[Example 2]
In 58.8 parts of water, 24 parts of the lithium salt of the azo compound represented by the above formula (10), 1.2 parts of Alzalin Red S manufactured by Aldrich, and 16 parts of Xylitol manufactured by Sigma were stirred and dissolved. Filtration and observation under a polarizing microscope confirmed that lyotropic liquid crystallinity was exhibited.
50 parts of the obtained lyotropic liquid crystal solution and 0.1 part of Surfinol 465 manufactured by Nissin Chemical Industry Co., Ltd. were diluted with 49.9 parts of water to obtain a coating liquid for producing an anisotropic film. When the obtained coating solution was observed with a polarizing microscope, no texture was seen and the solution was isotropic and uniform.
Using the coating solution, an anisotropic film 2 was obtained by coating the same base material as in Example 1 under the same conditions. The obtained film is almost transparent with no scattering when viewed from the front, but appears colored when viewed obliquely (θ = about 45 °), and a film similar to Example 1 can be obtained. I understood that I was able to do it.

[Example 3]
In 66.8 parts of water, 24 parts of a lithium salt of an azo compound represented by the above formula (10), 1.2 parts of alizarin red S manufactured by Aldrich and desalted and purified, and D-(+)-maltose manufactured by Tokyo Chemical Industry Co., Ltd. After stirring and dissolving 8 parts of monohydrate, it was filtered to obtain a lyotropic liquid crystalline solution.
50 parts of the obtained lyotropic liquid crystal solution and 0.1 part of Surfinol 465 manufactured by Nissin Chemical Industry Co., Ltd. were diluted with 49.9 parts of water to obtain an isotropic coating solution.
An anisotropic film 3 was obtained by forming a film in the same manner as in Examples 1 and 2. The obtained film is almost transparent with no scattering when viewed from the front, but appears colored when viewed from an oblique direction (θ = about 45 °), and a film similar to that of Examples 1 and 2 is obtained. I understood that I was able to.

[Example 4]
In 66.8 parts of water, 24 parts of a lithium salt of an azo compound represented by the above formula (10), 1.2 parts of alizarin red S manufactured by Aldrich, and D-(+)-malto manufactured by Tokyo Chemical Industry Co., Ltd. After stirring and dissolving 8 parts of triose hydrate, the mixture was filtered to obtain a lyotropic liquid crystalline solution.
50 parts of the obtained lyotropic liquid crystal solution and 0.1 part of Surfinol 465 manufactured by Nissin Chemical Industry Co., Ltd. were diluted with 49.9 parts of water to obtain an isotropic coating solution.
An anisotropic film 4 was obtained by forming a film in the same manner as in Examples 1 to 3. The obtained film is almost transparent with no scattering when viewed from the front, but appears colored when viewed obliquely (θ = about 45 °), and the same film as in Examples 1 to 3 is obtained. I understood that I was able to.

[Example 5]
In 74 parts of water, 18 parts of the sodium salt of an azo compound represented by the following formula (11) and 8 parts of meso-erythritol manufactured by Tokyo Chemical Industry Co., Ltd. were stirred and dissolved, followed by filtration to obtain a lyotropic liquid crystalline solution. 50 parts of the obtained lyotropic liquid crystal solution and 0.1 part of Surfinol 465 manufactured by Nissin Chemical Industry Co., Ltd. were diluted with 49.9 parts of water to obtain an isotropic coating solution.
An anisotropic film 5 was obtained by forming a film in the same manner as in Examples 1 to 4. The obtained film is almost transparent with no scattering when viewed from the front, but appears colored when viewed obliquely (θ = about 45 °), and the same film as in Examples 1 to 4 is obtained. I understood that I was able to.

[Example 6]
In 68 parts of water, 22 parts of a sodium salt of an azo compound represented by the following formula (12) and 10 parts of meso-erythritol manufactured by Tokyo Chemical Industry Co., Ltd. were stirred and dissolved, followed by filtration to obtain a lyotropic liquid crystalline solution. 50 parts of the obtained lyotropic liquid crystal solution and 0.1 part of Surfinol 465 manufactured by Nissin Chemical Industry Co., Ltd. were diluted with 49.9 parts of water to obtain an isotropic coating solution.
An anisotropic film 6 was obtained by forming a film in the same manner as in Examples 1-5. The obtained film is almost transparent with no scattering when viewed from the front, but appears colored when viewed from an oblique direction (θ = about 45 °), and a film similar to Examples 1 to 5 is obtained. I understood that I was able to.

Claims (9)

And the extinction coefficient k _z in the thickness direction, the extinction coefficient of the membrane plane direction k _x and k _y are anisotropic film, which satisfies the following formula (1) at a wavelength of 550 nm.

(In the above formula (1), x and y represent orthogonal optical principal axes in the film plane, and z represents the optical principal axis in the film thickness direction.) The anisotropic film according to claim 1, wherein k _z / k _x ≧ 2 and k _z / k _y ≧ 2.   The anisotropic film according to claim 1 or 2, wherein the stimulus purity of transmitted light when p-polarized light is incident from a polar angle of 45 degrees is 40% or less.   The anisotropic film according to any one of claims 1 to 3, comprising an azo compound having an excitation purity of 20% or less. The anisotropic film according to claim 4, wherein the azo compound is an azo compound having a free acid form represented by the following general formula (2) and having lyotropic liquid crystallinity.

(In the general formula (2), A represents an aromatic hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent.
B represents an aromatic hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent.
m represents 0 or 1.
p represents an integer of 0 to 3. When p is 2 to 3, a plurality of B present in one molecule may be the same or different from each other.
R ¹ and R ² each independently represent a hydrogen atom, an alkyl group that may have a substituent, a phenyl group that may have a substituent, or an acyl group that may have a substituent. To express. )   A viewing angle compensation film comprising the anisotropic film according to claim 1.   A viewing angle compensation element comprising the viewing angle compensation film according to claim 6 and another member.   It comprises the anisotropic film according to any one of claims 1 to 5, the viewing angle compensation film according to claim 6, or the viewing angle compensation element according to claim 7, and a polarizing film. A polarizing element. A anisotropic film according to any one of claims 1 to 5, a viewing angle compensation film according to claim 6, a viewing angle compensation element according to claim 7, or a polarizing element according to claim 8. A liquid crystal display device comprising:

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