JP5587391B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to an FFS (fringe field switching) mode liquid crystal display device having a cellulose acylate film having predetermined characteristics.

  A so-called in-plane switching (IPS) mode liquid crystal display device that applies a lateral electric field to liquid crystal has been proposed and put into practical use. In recent years, these panels have been developed not only for monitor use but also for TV use, and accordingly, the brightness of the screen needs to be greatly improved. However, the IPS mode has a problem that the transmittance is lower than other modes. As a method in which this problem is solved, a fringe field switching (FFS) mode (Patent Documents 1 to 3) has been proposed.

Japanese Patent No. 3114065 USP 6,388,726B Japanese Patent No. 3465835

However, the FFS mode liquid crystal display device also has a problem in that the display quality is not perfect, and the color of the image changes depending on the viewing angle characteristics, particularly the viewing angle.
The present invention has been made in view of the above-described problems, and provides an FFS type liquid crystal display device with a simple configuration and improved viewing angle characteristics, in particular, an image color change depending on the viewing angle is reduced. The issue is to provide.

As a result of intensive studies by the present inventors, it has been found that the above-described problems can be solved by the following means. Specifically, the above problem has been solved by the following means.
[1] A pair of first and second substrates disposed opposite to each other; a pixel electrode formed on at least one of the pair of substrates via an insulating layer and capable of applying different potentials; An electrode; a liquid crystal layer that is disposed between the pair of substrates, includes a liquid crystal material, and in which liquid crystal molecules are aligned substantially parallel to the surface of the substrate when no voltage is applied; FFS (fringe field switching) mode for controlling the orientation of the liquid crystal layer by an electric field formed on the pixel electrode and the common electrode. A liquid crystal display device,
A cellulose acylate film satisfying the following formula (I) is provided between the first polarizing film and the first substrate disposed closer to the first polarizing film among the pair of substrates. FFS mode liquid crystal display:
(I) 0 nm ≦ Re ≦ 10 nm and | Rth | ≦ 25 nm
In the formula, Re represents the front retardation value (nm) at a wavelength of 550 nm, and Rth represents the retardation value (nm) in the film thickness direction at a wavelength of 550 nm.

[2] The liquid crystal display device according to [1], wherein the liquid crystal material is a liquid crystal material having negative dielectric anisotropy.
[3] The in-plane slow axis of the cellulose acylate film intersects at least one of the absorption axis of the first polarizing film and the orientation control direction of the opposing surface of the first substrate [1] ] Or [2] liquid crystal display device.
[4] The cellulose acylate film is further provided between the second polarizing film and a second substrate disposed closer to the second polarizing film among the pair of substrates [1]. Liquid crystal display device in any one of-[3].
[5] The in-plane slow axis of the cellulose acylate film intersects at least one of the absorption axis of the second polarizing film and the orientation control direction of the facing surface of the second substrate [4] ] Liquid crystal display device.
[6] The liquid crystal display device according to any one of [1] to [3], which has at least one optically anisotropic layer between the second polarizing film and the liquid crystal layer.

[7] A first optical anisotropic layer satisfying the following formula (II) and a second optical anisotropic layer satisfying the following formula (III) are provided between the second polarizing film and the liquid crystal layer. The liquid crystal display device according to [6], wherein the in-plane slow axes are orthogonal or parallel to each other:
(II) −135 nm ≦ Rth ≦ −35 nm and 0 nm ≦ Re ≦ 10 nm
(III) 117 nm ≦ Re ≦ 157.5 nm and 58.5 nm ≦ Rth ≦ 78.8 nm
In the above formula, Re represents the front retardation value (nm) at a wavelength of 550 nm, and Rth represents the retardation value (nm) in the film thickness direction at a wavelength of 550 nm.
[8] A first optical anisotropic layer satisfying the following formula (IV) and a second optical anisotropic layer satisfying the following formula (V) are provided between the second polarizing film and the liquid crystal layer. The liquid crystal display device according to [6], wherein the in-plane slow axes are orthogonal or parallel to each other:
(IV) 35 nm ≦ Rth ≦ 135 nm and 0 nm ≦ Re ≦ 10 nm
(V) 117 nm ≦ Re ≦ 157.5 nm and −78.8 nm ≦ Rth ≦ −58.5 nm
In the above formula, Re represents the front retardation value (nm) at a wavelength of 550 nm, and Rth represents the retardation value (nm) in the film thickness direction at a wavelength of 550 nm.

[9] An optically anisotropic layer satisfying the following formula (VI) between the second polarizing film and the liquid crystal layer has an in-plane slow axis orthogonal to the absorption axis of the second polarizing film. Or the liquid crystal display device of [6] arrange | positioned in parallel:
(VI) 252.5 nm ≦ Re ≦ 292.5 nm and | Rth | ≦ 25 nm
In the above formula, Re represents the front retardation value (nm) at a wavelength of 550 nm, and Rth represents the retardation value (nm) in the film thickness direction at a wavelength of 550 nm.
[10] A first optical anisotropic layer satisfying the following formula (VII) and a second optical anisotropic layer satisfying the following formula (VIII) are provided between the second polarizing film and the liquid crystal layer. The liquid crystal display device according to [6], wherein the in-plane slow axes are orthogonal or parallel to each other:
(VII) 252.5 nm ≦ Re ≦ 292.5 nm and −118.1 nm ≦ Rth ≦ −18.1 nm
(VIII) 252.5 nm ≦ Re ≦ 292.5 nm and 18.1 nm ≦ Rth ≦ 118.1 nm
In the above formula, Re represents the front retardation value (nm) at a wavelength of 550 nm, and Rth represents the retardation value (nm) in the film thickness direction at a wavelength of 550 nm.

[11] Two optically anisotropic layers satisfying the following formula (IX) are disposed between the second polarizing film and the liquid crystal layer, with their in-plane slow axes orthogonal to each other. 6] Liquid crystal display device:
(IX) 252.5 nm ≦ Re ≦ 292.5 nm and −118.1 nm ≦ Rth ≦ −18.1 nm
In the above formula, Re represents the front retardation value (nm) at a wavelength of 550 nm, and Rth represents the retardation value (nm) in the film thickness direction at a wavelength of 550 nm.
[12] Between the second polarizing film and the liquid crystal layer, two optically anisotropic layers satisfying the following formula (X) are arranged with their in-plane slow axes orthogonal to each other. 6] Liquid crystal display device:
(X) 252.5 nm ≦ Re ≦ 292.5 nm and 18.1 nm ≦ Rth ≦ 118.1 nm
In the above formula, Re represents the front retardation value (nm) at a wavelength of 550 nm, and Rth represents the retardation value (nm) in the film thickness direction at a wavelength of 550 nm.

In this specification, the “FFS mode” refers to a structure in which a pixel electrode is formed on a common pixel electrode through an interlayer insulating film.
In the present specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) is an arbitrary value within the film plane when Re (λ) is an in-plane slow axis (determined by KOBRA 21ADH or WR) and an inclined axis (rotation axis). The direction of the rotation axis is the rotation axis), and the light of wavelength λ nm is incident from each inclined direction in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction, and a total of 6 points are measured. KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed average refractive index, and the input film thickness value.
In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative.

In addition, the retardation value is measured from the two inclined directions, with the slow axis as the tilt axis (rotation axis) (in the absence of the slow axis, the arbitrary direction in the film plane is the rotation axis), Based on the value, the assumed value of the average refractive index, and the input film thickness value, Rth can also be calculated from the following equations (1) and (2).
Rth = ((nx + ny) / 2−nz) x d −−−- formula (2)
Note:
The above Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. In the formula, nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, and nz represents the refractive index in the direction perpendicular to nx and ny.

When the film to be measured is a film that cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optical axis, Rth (λ) is calculated by the following method.
Rth (λ) is the above-mentioned Re (λ), and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotation axis) from −50 degrees to +50 degrees with respect to the film normal direction. The light of wavelength λ nm is incident from each inclined direction in 10 degree steps and measured at 11 points. Based on the measured retardation value, the assumed average refractive index, and the input film thickness value, KOBRA 21ADH or WR is calculated.
In the above measurement, the assumed value of the average refractive index may be a value in a polymer handbook (John Wiley & Sons, Inc.) or a catalog of various optical films. Those whose average refractive index is not known can be measured with an Abbe refractometer. Examples of the average refractive index values of main optical films are given below:
Cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).
By inputting these assumed values of average refractive index and film thickness, KOBRA 21ADH or WR calculates nx, ny, and nz. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

  In the present specification, unless otherwise specified, for example, “45 °”, “parallel”, or “vertical” means that the angle is within a range of strictly less than ± 5 degrees. That is, it means approximately 45 degrees, approximately parallel, and approximately vertical. The error from the exact angle is preferably less than 4 degrees, more preferably less than 3 degrees. Regarding the angle, “+” means the clockwise direction, and “−” means the counterclockwise direction. Further, the “slow axis” means a direction in which the refractive index is maximized. The “visible light region” means 380 nm to 780 nm. Further, the measurement wavelength of the refractive index is a value at λ = 550 nm in the visible light region unless otherwise specified.

In the present invention, by using cellulose acylate having predetermined optical characteristics (for example, as a protective film of a polarizing plate), the viewing angle characteristics are improved, and particularly the color change of the image depending on the viewing angle is reduced. An FFS mode liquid crystal display device is provided.
Furthermore, in the aspect having a liquid crystal layer made of a liquid crystal material having a negative dielectric anisotropy, the above effect, that is, the color change of the image depending on the viewing angle is reduced, and the contrast is improved as compared with the conventional case. An FFS mode liquid crystal display device can be provided.

It is a cross-sectional schematic diagram which shows a structure of an example of the liquid crystal display device of the FFS mode of this invention. It is a plane schematic diagram which shows the example of electrode structure which can be utilized for the liquid crystal display device of the FFS mode of this invention. FIG. 2 is a schematic cross-sectional view illustrating (a) voltage OFF state (black display) and (b) voltage ON state (white display) of the liquid crystal display device having the configuration illustrated in FIG. 1. 6 is a graph showing applied voltage-transmittance curves of an FFS mode liquid crystal display device having the same configuration using a liquid crystal material (P-type LC) having a positive dielectric anisotropy Δε and a negative liquid crystal material (N-type LC), respectively. is there. It is a cross-sectional schematic diagram which shows the structure of the other example of the liquid crystal display device of the FFS mode of this invention. It is a cross-sectional schematic diagram which shows the structure of the other example of the liquid crystal display device of the FFS mode of this invention.

Hereinafter, the present invention will be described in detail. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.
FIG. 1 is a schematic cross-sectional view of an example of the FFS mode liquid crystal display device of the present invention. The liquid crystal display device shown in FIG. 1 includes a pair of polarizing plates P1 and P2, and an FFS mode liquid crystal cell LC therebetween. The absorption axis of the polarizing plate P1 and the absorption axis of the polarizing plate P2 are arranged orthogonal to each other. The liquid crystal cell LC has a liquid crystal layer 24 containing a nematic liquid crystal having negative dielectric anisotropy between the pair of substrates 16 and 26. On the opposite surface of the substrate 16, the common electrode 18 and the plurality of pixel electrodes 22 are disposed via the insulating layer 20. The opposing surfaces of the substrates 16 and 26 have rubbing axes for controlling the alignment of liquid crystal molecules in the liquid crystal layer 24, and the rubbing axes of the opposing surfaces of the substrates 16 and 26 are parallel to each other. The axes obtained by projecting the absorption axes of the polarizing plate P1 on the same plane are parallel to each other. That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is the direction of 0 °, the absorption axis of the polarizing film 30 is the direction of 90 °, and the substrates 16 and 26 The rubbing shaft formed on the facing surface is in the direction of 0 °.

The common electrode 18 of the substrate 16 may be an unpatterned electrode or a linear electrode. An electrode layer made of a transparent material is preferable, and an ITO electrode or the like is preferable. Although the detailed structure of the pixel electrode 22 is not shown in FIG. 1, it is preferable that a plurality of pixel electrodes 22 are formed in a linear shape. Moreover, as long as the electric field from the common electrode 18 disposed in the lower layer can pass, any shape such as a mesh shape, a spiral shape, or a dot shape may be used. A floating electrode having a neutral potential may be further added. 2A and 2B show a configuration example of the pixel electrode 22. The pixel electrode 22 may have a configuration in which a plurality of linear electrode layers are arranged in parallel as shown in FIG. 2A, or domains having different orientation directions are formed as shown in FIG. 2B. As possible, a configuration in which a plurality of linear electrode layers are arranged at ± θ (for example, θ is about 10 °) with respect to the rubbing direction may be employed. In the liquid crystal display device of FIG. 1, nematic liquid crystal having negative dielectric anisotropy is used, so the rubbing direction is substantially perpendicular to the slit line of the pixel electrode 22, but the liquid crystal is rotated in a certain direction. For this reason, the alignment stability of the liquid crystal can be improved by setting the rubbing azimuth inclined by a certain angle (˜20 °) from the slit orthogonal azimuth. Moreover, in order to rotate and switch rod-shaped liquid crystalline molecules in an inclined state, the interval between the linear electrode layers is preferably about 1 to 30 μm, more preferably 2 to 10 μm.
The insulating layer 20 may be made of an inorganic material such as an oxide such as SiO ₂ or a nitride such as SiN, or may be an organic material such as acrylic or epoxy.

In FIG. 1 again, the polarizing plate P1 includes the polarizing film 12 and protective films 10 and 14 protecting the surface thereof. Similarly, the polarizing plate P2 includes the polarizing film 30 and the protective film 28 protecting the surface thereof and 32. Further, the protective films 14 and 28 arranged between the liquid crystal cell LC are made of a cellulose acylate film satisfying the following formula (I).
(I) 0 nm ≦ Re ≦ 10 nm and | Rth | ≦ 25 nm
In the formula, Re represents the front retardation value (nm) at a wavelength of 550 nm, and Rth represents the retardation value (nm) in the film thickness direction at a wavelength of 550 nm. The in-plane slow axis of the protective film 14 made of a cellulose acylate film satisfying the formula (I) is orthogonal to the absorption axis of the polarizing film 12 at 90 ° ± 5 ° or parallel at 0 ° ± 5, The polarizing film 12 is parallel to the absorption axis of the polarizing film 12 and the alignment control direction (rubbing axis) of the facing surface of the substrate 16 in the range of 0 ° ± 5 °. The in-plane slow axis of the protective film 28 made of a cellulose acylate film satisfying the formula (I) is orthogonal to the absorption axis of the polarizing film 30 at 90 ° ± 5 ° or parallel at 0 ° ± 5, It intersects the absorption axis of the polarizing film 30 and the orientation control direction (rubbing axis) of the facing surface of the substrate 26 in the range of 90 ° ± 5 °.
The protective films 10 and 32 disposed on the outside are not particularly limited as long as the polarizing films 12 and 30 can be protected, and commercially available cellulose acylate films, Fujitac made by Fuji Photo Film Co., Ltd., and the like are used.

The switching operation of black display (drive voltage OFF) and white display (drive voltage ON) of the liquid crystal display device of FIG. 1 will be described with reference to FIG.
The liquid crystal layer 24 is made of a nematic liquid crystal material having negative dielectric anisotropy. In the OFF state in which no voltage is applied, the rod-like liquid crystal molecules in the liquid crystal layer 24 are aligned with the major axis direction of the molecules with the rubbing direction of the alignment film (not shown) formed on the opposing surfaces of the substrates 16 and 26. Horizontal alignment is performed (FIG. 3A). As shown in FIG. 2A, the rubbing axis has an orientation that is substantially orthogonal to the electrode. Since the direction of the absorption axis of the polarizing plate P1 and the direction of the rubbing axis of the substrate 22 coincide with each other, linearly polarized light that has passed through the polarizing plate P1 does not change its polarization state even when it passes through the liquid crystal layer 24, and is absorbed. The light is shielded by the polarizing plate P2 whose axes are orthogonal. At this time, the display is black. In the ON state in which a voltage higher than the threshold is applied, an electric field including a component parallel to the substrate surface is formed with respect to the substrate 12 by the pixel electrode 22 composed of a plurality of linear electrode layers. The direction is oriented in a direction perpendicular to the direction of the electric field (FIG. 3B). That is, the long axis direction is aligned with the direction substantially perpendicular to the direction of the rubbing axis. As a result, the linearly polarized light that has passed through the polarizing plate P1 passes through the polarizing plate P2 with the polarization plane rotated by 90 ° due to the retardation of the liquid crystal layer 24. At this time, white display is performed. The liquid crystal display layer of FIG. 1 uses a cellulose acylate film satisfying the formula (I) as the protective films 14 and 28 of the polarizing plates P1 and P2 disposed on the liquid crystal cell side, and thus depends on the viewing angle. The color change of the image is reduced. Details of materials and methods used for producing a cellulose acylate film satisfying the formula (I) will be described later.

  Further, in the liquid crystal display device of FIG. 1, by using a liquid crystal material having a negative dielectric anisotropy, an image with a higher contrast can be displayed than using a liquid crystal material having a positive dielectric anisotropy. It has become. FIG. 4 shows an applied voltage for an FFS mode liquid crystal cell having the same configuration using a nematic material (a) exhibiting positive dielectric anisotropy and a nematic material (b) exhibiting negative dielectric anisotropy. -The result of having measured the transmittance | permeability characteristic is shown. From the results shown in FIG. 4, the applied voltage-transmittance curve (N-type LC) of a liquid crystal cell using a liquid crystal material having a negative dielectric anisotropy is a liquid crystal using a liquid crystal material exhibiting a positive dielectric anisotropy. It can be understood that a higher transmittance can be obtained at a lower voltage compared to the applied voltage-transmittance curve (P-type LC) of the cell. Therefore, the liquid crystal display device of FIG. 1 having a liquid crystal layer made of a liquid crystal material having negative dielectric anisotropy not only reduces the color change of the image depending on the viewing angle, but also has a high contrast image. Can be displayed.

In FIG. 1, a predetermined optical characteristic is exhibited as either one of the protective films 14 and 28 disposed between the liquid crystal cell LC and the polarizing plates P1 and P2 or on the liquid crystal cell side of the polarizing plates P1 and P2. By disposing the optically anisotropic layer, a liquid crystal display device capable of displaying an image with a higher contrast and a color change of the image depending on the viewing angle is further reduced.
Hereinafter, preferable examples in which the optically anisotropic layer is disposed will be described.
In FIG. 1, as the protective film 28, an optically anisotropic layer that satisfies the following formula (VI) may be arranged with the slow axis perpendicular or parallel to the absorption axis of the polarizing film 30.
(VI) 252.5 nm ≦ Re ≦ 292.5 nm and | Rth | ≦ 25 nm
In the above formula, Re represents the front retardation value (nm) at a wavelength of 550 nm, and Rth represents the retardation value (nm) in the film thickness direction at a wavelength of 550 nm.
Further, the same effect can be obtained by arranging an optically anisotropic layer satisfying the above formula (VI) as the protective film 14 so that the slow axis thereof is orthogonal or parallel to the absorption axis of the polarizing film 12. However, when an optically anisotropic layer satisfying the above formula (VI) is disposed as the protective film 14, the liquid crystal alignment control direction (generally the rubbing axis) of the opposing surfaces of the substrates 16 and 26 is set to the light source side. The orientation is perpendicular to the absorption axis of the polarizing film 12 of the polarizing plate P1.
The optically anisotropic layer satisfying the above formula (VI) is not particularly limited, and can be made from various materials. For example, as an optically anisotropic layer satisfying the formula (VI), a cellulose acylate composition to which a component having an action of developing or increasing retardation is added is formed as a film, and then uniaxially or biaxially stretched. The cellulose acylate film produced by this can be used. In addition, a polycarbonate film (trade name; Nitto Denko NRZ film) or a norbornene film (trade names: Zeonoa, Arton) can be used.

Two or more optically anisotropic layers may be disposed. FIG. 5 shows another configuration example of the liquid crystal display device of the present invention in which two optically anisotropic layers are arranged. In FIG. 5, the same members as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
In the liquid crystal display device of FIG. 5, instead of the polarizing plate P2 on the display surface side in FIG. 1, an elliptically polarizing plate P2 integrated with the first optical anisotropic layer 27 and the second optical anisotropic layer 28 ′. The liquid crystal display device has the same configuration as that shown in FIG. The second optical anisotropic layer 28 ′ also functions as a protective film that protects the polarizing film 30. The first optical anisotropic layer 27 and the second optical anisotropic layer 28 ′ satisfy predetermined optical characteristics and are arranged with their slow axes orthogonal or parallel to each other. The liquid crystal display device of FIG. 5 in which optically anisotropic layers satisfying the following conditions are arranged in a predetermined axial relationship has the same effect as the liquid crystal display device having the configuration shown in FIG. 1, and further depends on the viewing angle. The liquid crystal display device can display an image with a higher contrast ratio while suppressing the color change.

Hereinafter, a preferable combination example of the first optical anisotropic layer 27 and the second optical anisotropic layer 28 ′ in the configuration of FIG. 5 will be described. In the following formula, Re represents the front retardation value (nm) at a wavelength of 550 nm, and Rth represents the retardation value (nm) in the film thickness direction at a wavelength of 550 nm.
First Example The second optically anisotropic layer 28 ′ exhibits optical characteristics satisfying the following formula (III), and its slow axis is orthogonal to the absorption axis of the polarizing film 30 and the substrate 26 Parallel to the orientation control direction (rubbing axis) of the opposing surface. The first optical anisotropic layer 27 satisfies the following formula (II), and its slow axis is perpendicular or parallel to the slow axis of the second optical anisotropic layer 28 ′. That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is 0 °, and the rubbing axis formed on the opposing surfaces of the substrates 16 and 26 is 0 °. The slow axis of the first optical anisotropic layer 27 is in the direction of 0 ° or 90 °, the slow axis of the second optical anisotropic layer 28 ′ is in the direction of 0 °, and the absorption axis of the polarizing film 30 is 90 °. It is arranged in the direction of °.
(II) −135 nm ≦ Rth ≦ −35 nm and 0 nm ≦ Re ≦ 10 nm
(III) 117 nm ≦ Re ≦ 157.5 nm and 58.5 nm ≦ Rth ≦ 78.8 nm
Second Example The first optically anisotropic layer 27 exhibits optical characteristics satisfying the above formula (III), and its slow axis is parallel to the absorption axis of the polarizing film 30 and the substrate 26 It is orthogonal to the orientation control direction (rubbing axis) of the opposing surface. The second optically anisotropic layer 28 ′ satisfies the above formula (II), and its slow axis is orthogonal or parallel to the slow axis of the first optically anisotropic layer 27. That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is 0 °, and the rubbing axis formed on the opposing surfaces of the substrates 16 and 26 is 0 °. The slow axis of the first optical anisotropic layer 27 is in the direction of 90 °, the slow axis of the second optical anisotropic layer 28 ′ is in the direction of 0 ° or 90 °, and the absorption axis of the polarizing film 30 is 90 °. It is arranged in the direction of °.

  The optically anisotropic layer satisfying the above formula (II) and the optically anisotropic layer satisfying the above formula (III) are not particularly limited, and can be made from various materials. For example, as an optically anisotropic layer satisfying the above formula (II) or (III), a cellulose acylate composition to which a component having an action of developing or increasing retardation is added is formed as a film, and then uniaxially stretched. Alternatively, a cellulose acylate film produced by biaxial stretching can be used. In addition, a polycarbonate film (trade name; Nitto Denko NRZ film) or a norbornene film (trade names: Zeonoa, Arton) can be used. Further, it can be formed from a liquid crystalline composition. For example, an optically anisotropic layer satisfying the formula (II) can be formed by vertically aligning a long axis of a rod-like liquid crystal, and the formula (III) A satisfactory optically anisotropic layer can be formed by horizontally aligning the long axis of the rod-like liquid crystal.

Third Example The second optically anisotropic layer 28 ′ exhibits optical characteristics satisfying the following formula (V), and its slow axis is parallel to the absorption axis of the polarizing film 30 and the substrate 26. It is orthogonal to the orientation control direction (rubbing axis) of the opposing surface. The first optical anisotropic layer 27 exhibits optical characteristics satisfying the following formula (IV), and its slow axis is orthogonal or parallel to the slow axis of the second optical anisotropic layer 28 '. It is. That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is 0 °, and the rubbing axis formed on the opposing surfaces of the substrates 16 and 26 is 0 °. The slow axis of the first optical anisotropic layer 27 is in the direction of 0 ° or 90 °, the slow axis of the second optical anisotropic layer 28 ′ is in the direction of 90 °, and the absorption axis of the polarizing film 30 is 90 °. It is arranged in the direction of °.
(IV) 35 nm ≦ Rth ≦ 135 nm and 0 nm ≦ Re ≦ 10 nm
(V) 117 nm ≦ Re ≦ 157.5 nm and −78.8 nm ≦ Rth ≦ −58.5 nm
Fourth Example The first optical anisotropic layer 27 exhibits optical characteristics that satisfy the above formula (V), and its slow axis is orthogonal to the absorption axis of the polarizing film 30 and the substrate 26 It is parallel to the orientation control direction (rubbing axis) of the opposing surface. The second optically anisotropic layer 28 ′ satisfies the above formula (IV), and its slow axis is orthogonal or parallel to the slow axis of the first optically anisotropic layer 27. That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is 0 °, and the rubbing axis formed on the opposing surfaces of the substrates 16 and 26 is 0 °. The slow axis of the first optical anisotropic layer 27 is in the direction of 0 °, the slow axis of the second optical anisotropic layer 28 ′ is in the direction of 0 ° or 90 °, and the absorption axis of the polarizing film 30 is 90 °. It is arranged in the direction of °.

  The optically anisotropic layer satisfying the above formula (IV) and the optically anisotropic layer satisfying the above formula (V) are not particularly limited, and can be prepared from various materials. For example, as an optically anisotropic layer satisfying the above formula (IV) or (V), a cellulose acylate composition to which a component having an action of developing or increasing retardation is added is formed as a film, and then uniaxially stretched. Alternatively, a cellulose acylate film produced by biaxial stretching can be used. In addition, a polycarbonate film (trade name; Nitto Denko NRZ film) or a norbornene film (trade names: Zeonoa, Arton) can be used. The optically anisotropic layer that can be formed from a liquid crystalline composition and satisfies the above formula (V) is oriented with the disc surface of the discotic liquid crystalline molecules perpendicular to the layer surface, and its optical axis. Can be formed in a horizontal direction with respect to the layer surface. Further, the optically anisotropic layer satisfying the above formula (IV) is formed by aligning the disc surface of the discotic liquid crystalline molecule so that it is parallel to the layer surface, and making the optical axis perpendicular to the layer surface. it can.

Fifth Example The second optical anisotropic layer 28 ′ exhibits optical characteristics that satisfy the following formula (VII), and its slow axis is perpendicular to the absorption axis of the polarizing film 30 and the substrate 26 Parallel to the orientation control direction (rubbing axis) of the opposing surface. The first optically anisotropic layer 27 satisfies the following formula (VIII), and its slow axis is parallel to the slow axis of the second optically anisotropic layer 28 '. That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is 0 °, and the rubbing axis formed on the opposing surfaces of the substrates 16 and 26 is 0 °. The slow axis of the first optical anisotropic layer 27 is the direction of 0 °, the slow axis of the second optical anisotropic layer 28 ′ is the direction of 0 °, and the absorption axis of the polarizing film 30 is the direction of 90 °. Is arranged.
(VII) 252.5 nm ≦ Re ≦ 292.5 nm and −118.1 nm ≦ Rth ≦ −18.1 nm
(VIII) 252.5 nm ≦ Re ≦ 292.5 nm and 18.1 nm ≦ Rth ≦ 118.1 nm
Sixth Example The second optically anisotropic layer 28 ′ exhibits optical characteristics that satisfy the above formula (VIII), and its slow axis is parallel to the absorption axis of the polarizing film 30, and the substrate 26. It is orthogonal to the orientation control direction (rubbing axis) of the opposing surface. The first optical anisotropic layer 27 satisfies the above formula (VII), and its slow axis is parallel to the slow axis of the second optical anisotropic layer 28 '. That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is 0 °, and the rubbing axis formed on the opposing surfaces of the substrates 16 and 26 is 0 °. The slow axis of the first optical anisotropic layer 27 is 90 °, the slow axis of the second optical anisotropic layer 28 ′ is 90 °, and the absorption axis of the polarizing film 30 is 90 °. Is arranged.

Seventh Example Both the second optically anisotropic layer 28 ′ and the first optically anisotropic layer 27 exhibit optical characteristics satisfying the above formula (VIII), and their slow axes are orthogonal to each other. Are stacked. Further, the slow axis of the second optical anisotropic layer 28 ′ is parallel to the absorption axis of the polarizing film 30 and perpendicular to the orientation control direction (rubbing axis) of the opposing surface of the substrate 26. That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is 0 °, and the rubbing axis formed on the opposing surfaces of the substrates 16 and 26 is 0 °. The slow axis of the first optical anisotropic layer 27 is the direction of 0 °, the slow axis of the second optical anisotropic layer 28 ′ is the direction of 90 °, and the absorption axis of the polarizing film 30 is the direction of 90 °. Is arranged.
Eighth Example Both the second optical anisotropic layer 28 ′ and the first optical anisotropic layer 27 exhibit optical characteristics satisfying the above formula (VII), and their slow axes are orthogonal to each other. Are stacked. Further, the slow axis of the second optically anisotropic layer 28 ′ is perpendicular to the absorption axis of the polarizing film 30 and parallel to the orientation control direction (rubbing axis) of the opposing surface of the substrate 26. That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is 0 °, and the rubbing axis formed on the opposing surfaces of the substrates 16 and 26 is 0 °. The slow axis of the first optical anisotropic layer 27 is 90 °, the slow axis of the second optical anisotropic layer 28 ′ is 0 °, and the absorption axis of the polarizing film 30 is 90 °. Is arranged.

  The optically anisotropic layer exhibiting optical characteristics satisfying the above formula (VII) and the optically anisotropic layer exhibiting optical characteristics satisfying the above formula (VIII) are not particularly limited, and are prepared from various materials. Can do. For example, as an optically anisotropic layer satisfying the above formula (VII) or (VIII), a cellulose acylate composition to which a component having an action of developing or increasing retardation is added as a film, and then uniaxially stretched Alternatively, a cellulose acylate film produced by biaxial stretching can be used. In addition, a polycarbonate film (trade name; Nitto Denko NRZ film) or a norbornene film (trade names: Zeonoa, Arton) can be used. Is

  In the liquid crystal display device of FIG. 5, a configuration example in which the absorption axis of the polarizing film 12 of the light source side polarizing plate P1 and the orientation control direction (rubbing axis) of the facing surfaces of the substrates 16 and 26 are parallel to each other. Although shown, the liquid crystal display device of the present invention is not limited to this configuration, and the absorption axis of the polarizing film 12 of the light source side polarizing plate P1 and the alignment control directions of the opposing surfaces of the substrates 16 and 26 are orthogonal to each other. The mode may be such that the absorption axis of the polarizing film 30 of the display surface side polarizing plate P2 and the alignment control direction of the opposing surfaces of the substrates 16 and 26 are arranged in parallel to each other. Hereinafter, various preferable structural examples in which the optically anisotropic layer is disposed in this embodiment will be described with reference to FIG. In FIG. 6, the same members as those in FIGS. 1 and 5 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the liquid crystal display device shown in FIG. 6, an elliptically polarizing plate P1 'integrated with the third optical anisotropic layer 15 and the fourth optical anisotropic layer 14' is disposed on the light source side. The fourth optical anisotropic layer 14 ′ also functions as a protective film that protects the polarizing film 12. The third optical anisotropic layer 15 and the fourth optical anisotropic layer 14 'satisfy the predetermined optical characteristics and are arranged with their slow axes orthogonal or parallel to each other. In addition, the absorption axis of the polarizing film 12 of the light source side polarizing plate P1 ′ and the orientation control direction of the opposing surfaces of the substrates 16 ′ and 26 ′ are in directions orthogonal to each other, and the polarization of the display surface side polarizing plate P2. The absorption axis of the film 30 and the orientation control direction of the facing surfaces of the substrates 16 ′ and 26 ′ are parallel to each other.

Hereinafter, a preferable combination example of the third optical anisotropic layer 15 and the fourth optical anisotropic layer 14 ′ in the configuration of FIG. 6 will be described. In the following formula, Re represents the front retardation value (nm) at a wavelength of 550 nm, and Rth represents the retardation value (nm) in the film thickness direction at a wavelength of 550 nm.
Ninth Example The third optically anisotropic layer 15 exhibits optical characteristics satisfying the above formula (III), and its slow axis is parallel to the absorption axis of the polarizing film 12, and the substrate 16 It is orthogonal to the orientation control direction (rubbing axis) of the opposing surface. The fourth optically anisotropic layer 14 ′ exhibits optical characteristics satisfying the above formula (II), and its slow axis is orthogonal or parallel to the slow axis of the third optically anisotropic layer 15. It is. That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is 0 °, and the slow axis of the fourth optical anisotropic layer 14 ′ is 0 ° or 90 °. Direction, the slow axis of the third optically anisotropic layer 15 is 0 °, the rubbing axis formed on the opposing surfaces of the substrates 16 and 26 is 90 °, and the absorption axis of the polarizing film 30 is 90 °. It is arranged in the direction of °.
Tenth Example The fourth optically anisotropic layer 14 ′ exhibits optical characteristics satisfying the above formula (III), and its slow axis is orthogonal to the absorption axis of the polarizing film 12, and the substrate 26. Parallel to the orientation control direction (rubbing axis) of the opposing surface. The third optical anisotropic layer 15 exhibits optical characteristics satisfying the above formula (II), and its slow axis is orthogonal or parallel to the slow axis of the fourth optical anisotropic layer 14 ′. It is. That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is the direction of 0 °, and the slow axis of the fourth optical anisotropic layer 14 ′ is the direction of 90 °. The slow axis of the third optical anisotropic layer 15 is in the direction of 0 ° or 90 °, the rubbing axis formed on the opposing surfaces of the substrates 16 and 26 is in the direction of 90 °, and the absorption axis of the polarizing film 30 is 90 °. It is arranged in the direction of °.
For the optical anisotropic layer satisfying the above formula (II) and the material of the optical anisotropic layer satisfying the above formula (III), etc., the optical anisotropic layer of the liquid crystal display device of FIG. As described above.

Eleventh Example The first optically anisotropic layer 15 exhibits optical characteristics satisfying the above formula (V), and its slow axis is orthogonal to the absorption axis of the polarizing film 12 and the substrate 16 It is parallel to the orientation control direction (rubbing axis) of the opposing surface. The second optically anisotropic layer 14 ′ satisfies the above formula (IV) and is arranged with its slow axis orthogonal or parallel to the slow axis of the first optically anisotropic layer 15. . That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is 0 °, and the slow axis of the fourth optical anisotropic layer 14 ′ is 0 ° or 90 °. Direction, the slow axis of the third optically anisotropic layer 15 is 90 °, the rubbing axis formed on the opposing surfaces of the substrates 16 and 26 is 90 °, and the absorption axis of the polarizing film 30 is 90 °. It is arranged in the direction of °.
Twelfth Example The second optically anisotropic layer 14 ′ exhibits optical characteristics satisfying the above formula (V), has its slow axis parallel to the absorption axis of the polarizing film 12, and the substrate 16 Are arranged orthogonal to the orientation control direction (rubbing axis) of the opposite surface. The first optically anisotropic layer 15 satisfies the above formula (IV) and is arranged with its slow axis orthogonal or parallel to the slow axis of the second optically anisotropic layer 14 ′. . That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is the direction of 0 °, and the slow axis of the fourth optical anisotropic layer 14 ′ is the direction of 0 °. The slow axis of the third optical anisotropic layer 15 is in the direction of 0 ° or 90 °, the rubbing axis formed on the opposing surfaces of the substrates 16 and 26 is in the direction of 90 °, and the absorption axis of the polarizing film 30 is 90 °. It is arranged in the direction of °.
For the optical anisotropic layer satisfying the above formula (IV) and the material of the optical anisotropic layer satisfying the above formula (V), the optical anisotropic layer of the liquid crystal display device of FIG. As described above.

Thirteenth Example The first optically anisotropic layer 15 exhibits optical characteristics satisfying the above formula (VII), and its slow axis is parallel to the absorption axis of the polarizing film 12 and the substrate 16 They are arranged perpendicular to the orientation control direction (rubbing axis) of the opposing surface. The second optically anisotropic layer 14 ′ satisfies the above formula (VIII) and is arranged with its slow axis parallel to the slow axis of the first optically anisotropic layer 15. That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is the direction of 0 °, and the slow axis of the fourth optical anisotropic layer 14 ′ is the direction of 0 °. The slow axis of the third optical anisotropic layer 15 is the direction of 0 °, the rubbing axis formed on the opposing surfaces of the substrates 16 and 26 is the direction of 90 °, and the absorption axis of the polarizing film 30 is the direction of 90 °. Is arranged.
14th Example The second optically anisotropic layer 14 ′ exhibits optical characteristics satisfying the above formula (VIII), and its slow axis is orthogonal to the absorption axis of the polarizing film 12, and the substrate 16 Are arranged in parallel to the orientation control direction (rubbing axis) of the opposing surface. The first optically anisotropic layer 15 satisfies the above formula (VII) and is arranged with its slow axis parallel to the slow axis of the second optically anisotropic layer 14 '. That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is the direction of 0 °, and the slow axis of the fourth optical anisotropic layer 14 ′ is the direction of 90 °. The slow axis of the third optical anisotropic layer 15 is in the direction of 90 °, the rubbing axis formed on the opposing surfaces of the substrates 16 and 26 is in the direction of 90 °, and the absorption axis of the polarizing film 30 is in the direction of 90 °. Is arranged.

Fifteenth Example Both the second optical anisotropic layer 14 ′ and the first optical anisotropic layer 15 exhibit optical characteristics satisfying the above formula (VIII), and the second optical anisotropic layer 14 ′. Is arranged such that its slow axis is parallel to the absorption axis of the polarizing film 12 and perpendicular to the orientation control direction (rubbing axis) of the opposing surface of the substrate 16, and the first optically anisotropic layer No. 15 is arranged with its slow axis orthogonal to the slow axis of the second optically anisotropic layer 14 '. That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is the direction of 0 °, and the slow axis of the fourth optical anisotropic layer 14 ′ is the direction of 0 °. The slow axis of the third optical anisotropic layer 15 is in the direction of 90 °, the rubbing axis formed on the opposing surfaces of the substrates 16 and 26 is in the direction of 90 °, and the absorption axis of the polarizing film 30 is in the direction of 90 °. Is arranged.
Sixteenth Example Both the second optical anisotropic layer 14 ′ and the first optical anisotropic layer 15 exhibit optical characteristics that satisfy the above formula (VII), and the second optical anisotropic layer 14 ′. Is arranged with its slow axis perpendicular to the absorption axis of the polarizing film 12 and parallel to the orientation control direction (rubbing axis) of the opposing surface of the substrate 16, and the first optically anisotropic layer No. 15 is arranged with its slow axis orthogonal to the slow axis of the second optically anisotropic layer 14 '. That is, when the horizontal direction of the screen is 0 ° and the vertical direction is 90 °, the absorption axis of the polarizing film 12 is the direction of 0 °, and the slow axis of the fourth optical anisotropic layer 14 ′ is the direction of 90 °. The slow axis of the third optical anisotropic layer 15 is the direction of 0 °, the rubbing axis formed on the opposing surfaces of the substrates 16 and 26 is the direction of 90 °, and the absorption axis of the polarizing film 30 is the direction of 90 °. Is arranged.
5 for the optical anisotropic layer exhibiting optical characteristics satisfying the above formula (VII) and the material of the optical anisotropic layer exhibiting optical characteristics satisfying the above formula (VIII). The optically anisotropic layer is as described above.

  The liquid crystal display device of the present invention is not limited to the configuration shown in FIGS. 1, 5, and 6, and for example, a color filter may be disposed between the liquid crystal cell and the polarizing film. In the case of use as a transmission type, a cold cathode or a hot cathode fluorescent tube, or a backlight having a light emitting diode, a field emission element, or an electroluminescent element as a light source can be disposed on the back surface. Of course, it is also possible to provide a front light using the light source on the liquid crystal cell observation side.

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

Hereinafter, materials and manufacturing methods used for various members of the liquid crystal display device of the present invention will be described.
[Liquid crystal layer]
In the present invention, the liquid crystal material used for the liquid crystal layer is preferably a nematic liquid crystal material exhibiting negative dielectric anisotropy. Usually, in an FFS mode liquid crystal display device, nematic liquid crystal having a positive dielectric anisotropy Δε is used as a liquid crystal material. The larger the value of the dielectric anisotropy Δε, the lower the driving voltage, and the smaller the refractive index anisotropy Δn, the thicker the liquid crystal layer (gap), the shorter the liquid crystal sealing time, and the gap. Variation can be reduced. When a negative dielectric anisotropy nematic liquid crystal material is used for the liquid crystal display device of the present invention, the γ characteristic and the luminance characteristic are further improved. More specifically, when a liquid crystal material exhibiting negative dielectric anisotropy is used, an image with high transmittance during white display can be obtained, and an image with higher contrast can be displayed.

  In the present invention, the product Δn · d of the thickness d (μm) of the liquid crystal layer and the refractive index anisotropy Δn is about 0.2 to 1.2 μm, and should be 0.2 to 0.5 μm. preferable. In these ranges, since the white display luminance is high and the black display luminance is low, a bright and high-contrast image can be obtained. Note that the above range is a preferable range in the transmissive mode, and in the reflective mode, the optical path in the liquid crystal cell is doubled. Therefore, the preferable range of Δnd is about the above half value. The thickness (gap) of the liquid crystal layer is not particularly limited, but is generally about 2.5 μm to 4.5 μm. Within the above range, a transmittance characteristic having almost no wavelength dependence within the visible light range can be obtained more easily. By the combination of the alignment film and the polarizing plate described later, the maximum transmittance can be obtained when the liquid crystalline molecules are rotated 45 degrees from the rubbing direction to the electric field direction. The thickness (gap) of the liquid crystal layer may be controlled by polymer beads. Of course, the same gap can be obtained with glass beads, fibers, and resin columnar spacers.

[Cellulose acylate film]
In the present invention, a cellulose acylate film satisfying the following formula (I) is disposed between at least one of the pair of polarizing films and the liquid crystal cell. The cellulose acylate film may be bonded to the surface of the polarizing film as a protective film for the polarizing film, and may be incorporated in a liquid crystal display device as one member of a polarizing plate. ,
(I) 0 nm ≦ Re ≦ 10 nm and | Rth | ≦ 25 nm
In the formula, Re represents the front retardation value (nm) at a wavelength of 550 nm, and Rth represents the retardation value (nm) in the film thickness direction at a wavelength of 550 nm.
The liquid crystal display device of the present invention is an FFS mode liquid crystal display device in which liquid crystal materials are aligned substantially parallel during black display, and displays black by aligning liquid crystal molecules parallel to the substrate surface in the absence of voltage. By using a cellulose acylate film satisfying the above characteristics (preferably used as a protective film for a polarizing film disposed on the liquid crystal cell side), it is possible to reduce the color change of the image depending on the viewing angle. Contributes to widening corners and improving contrast. In the liquid crystal display device of the present invention, of the protective films of the polarizing plates above and below the liquid crystal cell, the protective film (the protective film on the cell side) disposed between the liquid crystal cell and the polarizing film is the cellulose acylate film. The polarizing plate is preferably used on at least one side. In the FFS type liquid crystal display device of the present invention, one protective film made of the cellulose acylate film is provided between the protective film of the lower polarizing film and the liquid crystal layer and between the upper polarizing film and the liquid crystal layer. The arrangement is preferable because the change in color of the image depending on the leakage light and the viewing angle during black display is reduced.

The cellulose acylate film preferably satisfies any of the following conditions (1) and (2).
(1) Cellulose acylate film satisfying the following formulas (1-a) and (1-b) (1-a) 0 ≦ Re (630) ≦ 10 and | Rth (630) | ≦ 25
(1-b) | Re (400) −Re (700) | ≦ 10 and | Rth (400) −Rth (700) | ≦ 35.
(2) Cellulose acylate film containing a compound that lowers Rth such that Rth in the film thickness direction satisfies the following formulas (2-a) and (2-b) (2-a) (Rth (A) -Rth (0)) / A ≦ −1.0
(2-b) 0.01 ≦ A ≦ 30.
In the above formulas (2-a) and (2-b), Rth (A) represents Rth (nm) of a cellulose acylate film containing a compound that lowers Rth, and Rth (0) represents the cellulose acylate. Rth (nm) of a film that is a rate film and does not contain a compound that lowers Rth, and represents the weight (%) of the compound that lowers Rht relative to the weight of the film raw material polymer. Here, the polymer of the film raw material refers to the raw material polymer of the main component constituting the film, and is cellulose acylate.

  The cellulose acylate used in the production of the cellulose acylate film used in the present invention is not particularly limited. For example, cellulose acylate obtained from any raw material cellulose such as cotton linter and wood pulp (hardwood pulp, conifer pulp) Can be used. If desired, a mixture may be used. Detailed descriptions of these raw material celluloses can be found in, for example, Plastic Materials Course (17) Fibrous Resin (Maruzawa, Uda, Nikkan Kogyo Shimbun, published in 1970) and Invention Association Open Technical Report 2001-1745 (page 7). To page 8) can be used.

  The cellulose acylate that can be used as a raw material for the cellulose acylate film is, for example, an acylated hydroxyl group of cellulose, and the substituent is any acetyl group having 2 to 22 carbon atoms in the acyl group. Can be used. The degree of substitution of the cellulose acylate that can be used in the present invention with the hydroxyl group of the cellulose is not particularly limited, but the degree of binding of acetic acid and / or a fatty acid having 3 to 22 carbon atoms to replace the cellulose with a hydroxyl group is measured, The degree of substitution is obtained by calculation. As a measuring method, it can carry out according to ASTM D-817-91.

  In the cellulose acylate, the degree of substitution of the cellulose with a hydroxyl group is not particularly limited, but the degree of acyl substitution with the hydroxyl group of cellulose is preferably 2.50 to 3.00. Furthermore, the substitution degree is more preferably 2.75 to 3.00, and further preferably 2.85 to 3.00.

  Among the acetic acid and / or fatty acid having 3 to 22 carbon atoms substituted for the hydroxyl group of cellulose, the acyl group having 2 to 22 carbon atoms may be an aliphatic group or an allyl group, and may be a single or a mixture of two or more types. Good. Examples thereof include cellulose alkylcarbonyl ester, alkenylcarbonyl ester, aromatic carbonyl ester and aromatic alkylcarbonyl ester. Each of these may further have a substituted group. These preferred acyl groups include acetyl group, propionyl group, butanoyl group, heptanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group , Iso-butanoyl group, tert-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like. Among these, acetyl group, propionyl group, butanoyl group, dodecanoyl group, octadecanoyl group, tert-butanoyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like are preferable, and acetyl group, propionyl group, butanoyl group are preferable. Groups are more preferred.

  Among the acyl substituents substituted on the hydroxyl group of cellulose described above, in the case of substantially consisting of at least two kinds of acetyl group, propionyl group and butanoyl group, the total substitution degree is 2.50 to 3.00 In addition, the optical anisotropy of the cellulose acylate film can be reduced. The degree of acyl substitution is more preferably 2.60 to 3.00, still more preferably 2.65 to 3.00.

The degree of polymerization of cellulose acylate preferably used in the present invention is 180 to 700 in terms of viscosity average polymerization degree, and in cellulose acetate, 180 to 550 is more preferable, 180 to 400 is more preferable, and 180 to 350 is particularly preferable. . By setting the degree of polymerization to a certain value or less, the viscosity of the cellulose acylate dope solution is increased, and it is possible to more effectively prevent film production from becoming difficult due to casting. By making the degree of polymerization a certain level or more, it is possible to more effectively prevent the strength of the produced film from being lowered. The average degree of polymerization can be measured, for example, by the intrinsic viscosity method of Uda et al. (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. 18, No. 1, pages 105-120, 1962). This method is described in detail in JP-A-9-95538.
Further, the molecular weight distribution of cellulose acylate preferably used in the present invention is evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is mass average molecular weight, Mn is number average molecular weight) is small, and molecular weight distribution. Is preferably narrow. The specific value of Mw / Mn is preferably 1.0 to 3.0, more preferably 1.0 to 2.0, and most preferably 1.0 to 1.6. preferable.

  When the low molecular component is removed, the average molecular weight (degree of polymerization) increases, but the viscosity becomes lower than that of normal cellulose acylate, which is useful. Cellulose acylate having a small amount of low molecular components can be obtained by removing low molecular components from cellulose acylate synthesized by a usual method. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent. In addition, when manufacturing a cellulose acylate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 mass parts of cellulose. When the amount of the sulfuric acid catalyst is within the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized. When used in the production of cellulose acylate that can be used in the present invention, the water content is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly 0.7% by mass. It is a cellulose acylate having a moisture content of not more than%. In general, cellulose acylate contains water and is known to be 2.5 to 5% by mass. In order to obtain the moisture content of the cellulose acylate in the present invention, it is necessary to dry, and the method is not particularly limited as long as the desired moisture content is obtained. The cellulose acylate is described in detail on pages 7 to 12 of the raw material cotton and the synthesis method in the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society for Invention). Yes.

  When preparing the cellulose acylate film, it is preferable to select one or two or more different types from cellulose acylate in the above-mentioned ranges such as substituent, substitution degree, polymerization degree, and molecular weight distribution. .

In the cellulose acylate solution used to produce the cellulose acylate film, various additives (for example, a compound that reduces optical anisotropy, a wavelength dispersion adjusting agent, an ultraviolet ray inhibitor, a plasticizer, Deterioration inhibitors, fine particles, optical property modifiers, etc.) can be added, and these are described below. Further, the addition may be performed at any time in the dope preparation step, but may be performed by adding a preparation step by adding an additive to the final preparation step of the dope preparation step.
The cellulose acylate film that can be used in the present invention decreases Rth such that Rth in the film thickness direction satisfies the above formulas (2-a) and (2-b) so as to satisfy the above condition (2). It is preferable to contain the compound to be made.
The above formulas (2-a) and (2-b) are: (2-a) ′ (Rth (A) −Rth (0)) / A ≦ −2.0
(2-b) ′ 0.1 ≦ A ≦ 20
More preferably.

  The compound that reduces the optical anisotropy of the cellulose acylate film will be described. By using a compound that suppresses the orientation of cellulose acylate in the film in the plane and in the film thickness direction, the optical anisotropy is sufficiently reduced, and a film in which Re is zero and Rth is close to zero is produced. Can do. Here, being close to zero means, for example, ± 2 nm or less at an arbitrary wavelength. For this purpose, it is advantageous that the compound for reducing the optical anisotropy is sufficiently compatible with cellulose acylate, and the compound itself does not have a rod-like structure or a planar structure. Specifically, when a plurality of planar functional groups such as aromatic groups are provided, a structure having these functional groups in a non-planar rather than the same plane is advantageous.

In producing a cellulose acylate film that can be used in the present invention, as described above, the compound that reduces the optical anisotropy by inhibiting the cellulose acylate in the film from being oriented in the plane and in the film thickness direction. Of these, compounds having an octanol-water partition coefficient (log P value) of 0 to 7 are preferred. By adopting a compound having a log P value of 7 or less, compatibility with cellulose acylate is improved, and the cloudiness and powder blowing of the film can be more effectively prevented. Moreover, since the hydrophilicity is high by adopting a compound having a log P value of 0 or more, it is possible to more effectively prevent the water resistance of the cellulose acetate film from deteriorating. A more preferable range for the logP value is 1 to 6, and a particularly preferable range is 1.5 to 5.
The octanol-water partition coefficient (log P value) can be measured by a flask immersion method described in JIS Japanese Industrial Standard Z7260-107 (2000). Further, the octanol-water partition coefficient (log P value) can be estimated by a computational chemical method or an empirical method instead of the actual measurement. As a calculation method, Crippen's fragmentation method (J. Chem. Inf. Comput. Sci., 27, 21 (1987)), Viswanadhan's fragmentation method (J. Chem. Inf. Comput. Sci., 29,). 163 (1989).), Broto's fragmentation method (Eur. J. Med. Chem.-Chim. Theor., 19, 71 (1984).) And the like are preferably used, but the Crippen's fragmentation method (J. Chem. Inf. Comput. Sci., 27, 21 (1987). When the log P value of a certain compound varies depending on the measurement method or calculation method, it is preferable to determine whether or not the compound is within a predetermined range by the Crippen's fragmentation method.

The compound that reduces optical anisotropy may or may not contain an aromatic group. In addition, the compound that decreases the optical anisotropy preferably has a molecular weight of 150 to 3000, more preferably 170 to 2000, and even more preferably 200 to 1000. A specific monomer structure may be used as long as these molecular weights are within the range, and an oligomer structure or a polymer structure in which a plurality of the monomer units are bonded may be used.
The compound that reduces optical anisotropy is preferably liquid at 25 ° C. or a solid having a melting point of 25 to 250 ° C., more preferably liquid at 25 ° C. or a melting point of 25 to 200 ° C. It is a solid. Moreover, it is preferable that the compound which reduces optical anisotropy does not volatilize in the process of dope casting for cellulose acylate film production and drying.
The addition amount of the compound that decreases the optical anisotropy is preferably 0.01 to 30% by mass of the cellulose acylate, more preferably 1 to 25% by mass, and 5 to 20% by mass. Is particularly preferred.
The compound that decreases the optical anisotropy may be used alone, or two or more compounds may be mixed and used in an arbitrary ratio.
The timing for adding the compound for reducing the optical anisotropy may be any time during the dope preparation process, or may be performed at the end of the dope preparation process.

  The compound that reduces the optical anisotropy is such that the average content of the compound in the portion from the surface on at least one side to 10% of the total film thickness is the average content of the compound in the central portion of the cellulose acylate film. It is preferable that it exists so that it may become 80 to 99% of. The amount of the compound that reduces the optical anisotropy can be determined by measuring the amount of the compound at the surface and in the central portion, for example, by a method using an infrared absorption spectrum described in JP-A-8-57879.

Although the specific example of the compound which reduces the optical anisotropy of the cellulose acylate film preferably used by this invention below is shown, it is not limited to these compounds.
The example of the compound which reduces the said optical anisotropy is a compound represented by following General formula (13).

In the general formula (13), R ¹¹ represents an alkyl group or an aryl group, and R ¹² and R ¹³ each independently represent a hydrogen atom, an alkyl group, or an aryl group. Further, it is particularly preferable that the total number of carbon atoms of R ¹¹ , R ¹² and R ¹³ is 10 or more. R ¹¹ , R ¹² and R ¹³ may have a substituent, and the substituent is preferably a fluorine atom, an alkyl group, an aryl group, an alkoxy group, a sulfone group or a sulfonamide group, an alkyl group, an aryl group, Alkoxy groups, sulfone groups and sulfonamido groups are particularly preferred. Further, the alkyl group may be linear, branched or cyclic, and preferably has 1 to 25 carbon atoms, more preferably 6 to 25, and more preferably 6 to 20 (For example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, amyl, isoamyl, t-amyl, hexyl, cyclohexyl, heptyl, octyl, bicyclo Octyl, nonyl, adamantyl, decyl, t-octyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, didecyl) are particularly preferred . As the aryl group, those having 6 to 30 carbon atoms are preferable, and those having 6 to 24 carbon atoms (for example, phenyl group, biphenyl group, terphenyl group, naphthyl group, binaphthyl group, triphenylphenyl group) are particularly preferable.
Although the preferable example of a compound represented by General formula (13) below is shown below, this invention is not limited to these specific examples. In the compounds, Pr ⁱ means an isopropyl group (hereinafter the same).

Another example of the compound that lowers the optically anisotropic layer is a compound represented by the following general formula (18).

In General Formula (18), R ¹⁴ represents an alkyl group or an aryl group, and R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom, an alkyl group, or an aryl group.
R ¹⁴ is preferably a phenyl group or a cyclic alkyl group. R ¹⁵ and R ¹⁶ are each preferably a phenyl group or an alkyl group. As the alkyl group, both a cyclic alkyl group and a linear alkyl group are preferable.
These groups may have a substituent, and the substituent is preferably a fluorine atom, an alkyl group, an aryl group, an alkoxy group, a sulfone group, or a sulfonamide group. The alkyl group, aryl group, alkoxy group, sulfone group is preferable. Groups and sulfonamido groups are particularly preferred.

The compound represented by the general formula (18) is more preferably a compound represented by the general formula (19).

In the general formula (19), R ¹¹⁴ , R ¹¹⁵ and R ¹¹⁶ each independently represents an alkyl group or an aryl group. The alkyl group is preferably a cyclic alkyl group or a linear alkyl group, and the aryl group is preferably a phenyl group.
Although the preferable example of a compound represented by General formula (18) (and General formula (19)) below is shown below, this invention is not limited to these specific examples. In the compounds, Bu ⁱ means an isobutyl group.

Moreover, the said cellulose acylate film may contain the compound which reduces the wavelength dispersion of an optical characteristic. Hereinafter, the compound for reducing the wavelength dispersion of the cellulose acylate film (hereinafter also referred to as a wavelength dispersion adjusting agent) will be described. In order to improve the Rth wavelength dispersion of the cellulose acylate film, a compound that reduces the Rth wavelength dispersion ΔRth = | Rth (400) −Rth (700) | represented by the following formula (3): It is preferable to contain at least one kind within a range satisfying the following formulas (3-a) and (3-b).
(3) ΔRth = | Rth (400) −Rth (700) |
(3-a) (ΔRth (B) −ΔRth (0)) / B ≦ −2.0
(3-b) 0.01 ≦ B ≦ 30
The above formulas (3-a) and (3-b) are expressed as follows: (3-a) ′ (ΔRth (B) −ΔRth (0)) / B ≦ −3.0
(3-b) ′ 0.05 ≦ B ≦ 25
More preferably,
(3-a) ”(ΔRth (B) −ΔRth (0)) / B ≦ −4.0
(3-b) ”0.1 ≦ B ≦ 20
More preferably.

  The cellulose acylate film satisfies the above conditions as a wavelength dispersion adjusting agent, has absorption in the ultraviolet region of 200 to 400 nm, and has | Re (400) -Re (700) | and | Rth (400) of the film. It is preferable to contain 0.01 to 30% by mass of at least one compound that lowers —Rth (700) | with respect to the solid content of cellulose acylate.

  In general, the Re and Rth values of the cellulose acylate film have a wavelength dispersion characteristic that the longer wavelength side is larger than the shorter wavelength side. Therefore, it is required to smoothen the chromatic dispersion by increasing Re and Rth on the relatively small short wavelength side. On the other hand, a compound having absorption in the ultraviolet region of 200 to 400 nm has a wavelength dispersion characteristic in which the absorbance on the long wavelength side is larger than that on the short wavelength side. If the compound itself is isotropically present inside the cellulose acylate film, it is assumed that the birefringence of the compound itself, and thus the wavelength dispersion of Re and Rth, is large on the short wavelength side as well as the wavelength dispersion of absorbance. .

  Therefore, as described above, by using the compound having absorption in the ultraviolet region of 200 to 400 nm and assuming that the wavelength dispersion of Re and Rth of the compound itself is large on the short wavelength side, the Re and Rth of the cellulose acylate film are used. Chromatic dispersion can be prepared. For this purpose, the compound for adjusting the wavelength dispersion is required to be sufficiently homogeneously compatible with the cellulose acylate. The absorption band range in the ultraviolet region of such a compound is preferably 200 to 400 nm, more preferably 220 to 395 nm, and even more preferably 240 to 390 nm.

  In recent years, liquid crystal display devices such as televisions, notebook personal computers, and mobile portable terminals have been required to have excellent transmittance of optical members used in liquid crystal display devices in order to increase luminance with less power. In that respect, a compound having absorption in the ultraviolet region of 200 to 400 nm and reducing | Re (400) -Re (700) | and | Rth (400) -Rth (700) | When it is added, it is required that the spectral transmittance is excellent. In the cellulose acylate film, the spectral transmittance at a wavelength of 380 nm is preferably 45% to 95%, and the spectral transmittance at a wavelength of 350 nm is preferably 10% or less.

  The wavelength dispersion adjusting agent preferably used in the present invention preferably has a molecular weight of 250 to 1000 from the viewpoint of volatility, more preferably 260 to 800, still more preferably 270 to 800, and particularly preferably 300. ~ 800. A specific monomer structure may be used as long as these molecular weights are within the range, and an oligomer structure or a polymer structure in which a plurality of the monomer units are bonded may be used.

  It is preferable that the wavelength dispersion adjusting agent does not volatilize in the process of dope casting for cellulose acylate film production and drying described later.

The added amount of the wavelength dispersion adjusting agent preferably used in the present invention described above is preferably 0.01 to 30% by mass, more preferably 0.1 to 20% by mass with respect to cellulose acylate, It is especially preferable that it is 0.2-10 mass%.
These wavelength dispersion adjusting agents may be used alone or in combination of two or more compounds at an arbitrary ratio.
In addition, the timing of adding these wavelength dispersion adjusting agents may be any time during the dope preparation process, or may be performed at the end of the dope preparation process.

  Specific examples of the wavelength dispersion adjusting agent preferably used in the present invention include, for example, benzotriazole compounds, benzophenone compounds, compounds containing a cyano group, oxybenzophenone compounds, salicylic acid ester compounds, nickel complex compounds, and the like. However, the present invention is not limited to these compounds.

As the benzotriazole-based compound, those represented by the following general formula (101) are preferably used as a wavelength dispersion adjusting agent.
Formula (101)
Q ¹¹ -Q ¹² -OH
(In the general formula (101), Q ¹¹ represents a nitrogen-containing aromatic heterocycle, and Q ¹² represents an aromatic ring.)

Q ¹¹ represents a nitrogen-containing aromatic heterocycle, preferably a 5- to 7-membered nitrogen-containing aromatic heterocycle, more preferably a 5- or 6-membered nitrogen-containing aromatic heterocycle, , Imidazole ring, pyrazole ring, triazole ring, tetrazole ring, thiazole ring, oxazole ring, selenazole ring, benzotriazole ring, benzothiazole ring, benzoxazole ring, benzoselenazole ring, thiadiazole ring, oxadiazole ring, naphthothiazole ring Naphthoxazole ring, azabenzimidazole ring, purine ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, triazine ring, triazaindene ring, tetrazaindene ring, etc., more preferably a 5-membered ring. Nitrogen-containing aromatic heterocycle, specifically imidazole ring, pyrazo Le ring, triazole ring, tetrazole ring, thiazole ring, oxazole ring, benzotriazole ring, benzothiazole ring, benzoxazole ring, thiadiazole ring, oxadiazole ring are preferred, particularly preferably a benzotriazole ring.

The aromatic ring represented by Q ¹² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.
The aromatic hydrocarbon ring is preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms, more preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 20 carbon atoms. More preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 12 carbon atoms, and most preferably a benzene ring.
The aromatic heterocycle is preferably an aromatic heterocycle containing a nitrogen atom or a sulfur atom. Specific examples of the heterocyclic ring include, for example, thiophene ring, imidazole ring, pyrazole ring, pyridine ring, pyrazine ring, pyridazine ring, triazole ring, triazine ring, indole ring, indazole ring, purine ring, thiazoline ring, thiazole ring, thiadiazole. Ring, oxazoline ring, oxazole ring, oxadiazole ring, quinoline ring, isoquinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinazoline ring, cinnoline ring, pteridine ring, acridine ring, phenanthroline ring, phenazine ring, tetrazole ring, benz Examples include an imidazole ring, a benzoxazole ring, a benzthiazole ring, a benzotriazole ring, and a tetrazaindene ring. The aromatic hetero ring is preferably a pyridine ring, a triazine ring or a quinoline ring.
The aromatic ring represented by Q ¹² is preferably an aromatic hydrocarbon ring, more preferably a naphthalene ring or a benzene ring, and particularly preferably a benzene ring. Q ¹² may have a substituent, and the substituent T described below is preferable as the substituent.
Examples of the substituent T include an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably 1 to 8 carbon atoms. For example, a methyl group, an ethyl group, an isopropyl group, tert- Butyl group, n-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (preferably having 2-20 carbon atoms, more preferably carbon number). 2 to 12, particularly preferably 2 to 8 carbon atoms, such as vinyl group, allyl group, 2-butenyl group, 3-pentenyl group, etc.), alkynyl group (preferably 2 to 20 carbon atoms, more Preferably they are C2-C12, Most preferably, it is C2-C8, for example, a propargyl group, 3-pentynyl group, etc. are mentioned. A group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include a phenyl group, a p-methylphenyl group, and a naphthyl group), substitution Or an unsubstituted amino group (preferably having 0 to 20 carbon atoms, more preferably 0 to 10 carbon atoms, particularly preferably 0 to 6 carbon atoms, such as an amino group, a methylamino group, a dimethylamino group, a diethylamino group, A dibenzylamino group, etc.), an alkoxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methoxy group, ethoxy group, butoxy Group), an aryloxy group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, and particularly preferably 6 to 12 carbon atoms). , For example, phenyloxy group, 2-naphthyloxy group, etc.), acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, An acetyl group, a benzoyl group, a formyl group, a pivaloyl group, etc.), an alkoxycarbonyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, and particularly preferably 2 to 12 carbon atoms, For example, a methoxycarbonyl group, an ethoxycarbonyl group, etc.), an aryloxycarbonyl group (preferably having a carbon number of 7 to 20, more preferably a carbon number of 7 to 16, particularly preferably a carbon number of 7 to 10, such as phenyl Oxycarbonyl group, etc.), acyloxy group (preferably having 2 to 20 carbon atoms, more preferably carbon It has 2 to 16 primes, particularly preferably 2 to 10 carbons, and examples thereof include an acetoxy group and a benzoyloxy group. ), An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include an acetylamino group and a benzoylamino group), alkoxycarbonyl. An amino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as a methoxycarbonylamino group), an aryloxycarbonylamino group (preferably Has 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as a phenyloxycarbonylamino group, and a sulfonylamino group (preferably 1 to 1 carbon atom). 20, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms. Nylamino group, benzenesulfonylamino group, etc.), sulfamoyl group (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms, such as sulfamoyl group, methyl A sulfamoyl group, a dimethylsulfamoyl group, a phenylsulfamoyl group, etc.), a carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to carbon atoms). 12 and examples thereof include a carbamoyl group, a methylcarbamoyl group, a diethylcarbamoyl group, a phenylcarbamoyl group, etc.), an alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably carbon atoms). Examples thereof include methylthio group and ethylthio group. ), An arylthio group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as a phenylthio group), a sulfonyl group (preferably C1-C20, More preferably, it is C1-C16, Most preferably, it is C1-C12, For example, a mesyl group, a tosyl group, etc. are mentioned), a sulfinyl group (preferably C1-C20, More preferably, it is C1-C16, Most preferably, it is C1-C12, for example, a methanesulfinyl group, a benzenesulfinyl group, etc.), a ureido group (preferably C1-C20, more preferably carbon) The number is 1 to 16, particularly preferably 1 to 12, and examples thereof include a ureido group, a methylureido group, and a phenylureido group. ), Phosphoric acid amide groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as diethyl phosphoric acid amide and phenylphosphoric acid amide. ), Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, Heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom and a sulfur atom, specifically, for example, an imidazolyl group, a pyridyl group, a quinolyl group, Furyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, etc. ), A silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, and examples thereof include a trimethylsilyl group and a triphenylsilyl group. ) And the like. These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

The general formula (101) is preferably represented by the following general formula (101-A).
General formula (101-A)

In general formula (101-A), R < ¹ >, R < ² >, R < ³ >, R < ⁴ >, R < ⁵ >, R < ⁶ >, R <^7> , and R < ⁸ > each independently represents a hydrogen atom or a substituent.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , and R ⁹ each independently represent a hydrogen atom or a substituent, and the above-mentioned substituent T is applied as the substituent. it can. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.
R ¹ and R ³ are each preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom, more preferably a hydrogen atom. , An alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, more preferably a hydrogen atom and an alkyl group having 1 to 12 carbon atoms, particularly preferably an alkyl group having 1 to 12 carbon atoms (preferably carbon). 4 to 12).

R ² and R ⁴ are each preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom, more preferably a hydrogen atom. , An alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, more preferably a hydrogen atom and an alkyl group having 1 to 12 carbon atoms, particularly preferably a hydrogen atom and a methyl group, most preferably hydrogen. Is an atom.

R ⁵ and R ⁸ are each preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom, more preferably a hydrogen atom. , An alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, more preferably a hydrogen atom and an alkyl group having 1 to 12 carbon atoms, particularly preferably a hydrogen atom and a methyl group, most preferably hydrogen. Is an atom.

R ⁶ and R ⁷ are each preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom, more preferably a hydrogen atom. , An alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, more preferably a hydrogen atom and a halogen atom, and particularly preferably a hydrogen atom and a chlorine atom.

  The general formula (101) is more preferably represented by the following general formula (101-B).

General formula (101-B)

In General Formula (101-B), R ¹ , R ³ , R ⁶ and R ⁷ have the same meanings as those in General Formula (101-A), and preferred ranges are also the same.

  Specific examples of the compound represented by formula (101) are listed below, but the present invention is not limited to the following specific examples.

  Among the benzotriazole compounds mentioned in the above examples, when the cellulose acylate film was produced without including those having a molecular weight of 320 or less, it was confirmed that the retention was advantageous.

In addition, as a benzophenone-based compound that is an example of the wavelength dispersion adjusting agent used in the present invention, a compound b represented by the following general formula (102) is preferably used.
General formula (102)

In General Formula (102), Q ¹ and Q ² each represent an aromatic ring. X represents NR (R represents a hydrogen atom or a substituent), an oxygen atom, or a sulfur atom.

The aromatic ring represented by Q ¹ or Q ² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.
The aromatic hydrocarbon ring represented by Q ¹ and Q ² is preferably (preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, a benzene ring, a naphthalene ring, etc.). More preferably an aromatic hydrocarbon ring having 6 to 20 carbon atoms, and still more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms.) More preferably, it is a benzene ring.
The aromatic heterocycle represented by Q ¹ and Q ² is preferably an aromatic heterocycle containing at least one of an oxygen atom, a nitrogen atom or a sulfur atom. Specific examples of the heterocyclic ring include, for example, furan ring, pyrrole ring, thiophene ring, imidazole ring, pyrazole ring, pyridine ring, pyrazine ring, pyridazine ring, triazole ring, triazine ring, indole ring, indazole ring, purine ring, thiazoline. Ring, thiazole ring, thiadiazole ring, oxazoline ring, oxazole ring, oxadiazole ring, quinoline ring, isoquinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinazoline ring, cinnoline ring, pteridine ring, acridine ring, phenanthroline ring, phenazine Ring, tetrazole ring, benzimidazole ring, benzoxazole ring, benzthiazole ring, benzotriazole ring, tetrazaindene ring and the like. The aromatic hetero ring is preferably a pyridine ring, a triazine ring or a quinoline ring.
The aromatic ring represented by Q ¹ or Q ² is preferably an aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 10 carbon atoms, and further preferably a substituted or unsubstituted benzene. It is a ring.
Q ¹ or Q ² may further have a substituent, and the substituent T described later is preferable, but the substituent does not contain a carboxylic acid, a sulfonic acid, or a quaternary ammonium salt. Further, if possible, substituents may be linked to form a ring structure.

  X represents NR (R represents a hydrogen atom or a substituent. As the substituent, the above-mentioned substituent T can be applied), an oxygen atom or a sulfur atom, X is preferably NR (R is preferably an acyl group) , A sulfonyl group, and these substituents may be further substituted.) Or an oxygen atom, particularly preferably an oxygen atom.

The general formula (102) is preferably represented by the following general formula (102-A).
Formula (102-A)

In Formula (102-A), represents a ^{R 21, R 22, R 23} , R 24, R 25, R 26, R 27, R 28, and R ²⁹ each independently represent a hydrogen atom or a substituent.

R ²¹ , R ²³ , R ²⁴ , R ²⁵ , R ²⁶ , R ²⁸ , and R ²⁹ each independently represent a hydrogen atom or a substituent, and the above-described substituent T can be applied as the substituent. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ²¹ , R ²³ , R ²⁴ , R ²⁵ , R ²⁶ , R ²⁸ , and R ²⁹ are preferably a hydrogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, amino group, alkoxy group, aryloxy group , A hydroxy group and a halogen atom, more preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, still more preferably a hydrogen atom and an alkyl group having 1 to 12 carbons. Preferred are a hydrogen atom and a methyl group, and most preferred is a hydrogen atom.

R ²² is preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom, more preferably a hydrogen atom or a C 1-20 carbon atom. An alkyl group, an amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and a hydroxy group, more preferably an alkoxy group having 1 to 20 carbon atoms, Preferably it is a C1-C12 alkoxy group.

Preferably a hydrogen atom R ^27, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a hydroxyl group, a halogen atom, more preferably a hydrogen atom, an alkyl group having 1 to 20 carbon atoms , An amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and a hydroxy group, more preferably a hydrogen atom and an alkyl group having 1 to 20 carbon atoms (preferably C1-C12, More preferably, it is C1-C8, More preferably, it is a methyl group, Especially preferably, they are a methyl group and a hydrogen atom.

The general formula (102) is more preferably represented by the following general formula (102-B).
General formula (102-B)

In General Formula (102-B), R ¹⁰ represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, or an aryl group.

R ¹⁰ represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, or an aryl group, and these may have a substituent. As the substituent, the above-described substituent T can be applied.
R ¹⁰ is preferably an alkyl group, more preferably an alkyl group having 5 to 20 carbon atoms, and still more preferably an alkyl group having 5 to 12 carbon atoms (n-hexyl group, 2-ethylhexyl group, n-octyl group). Group, n-decyl group, n-dodecyl group, benzyl group, etc.), particularly preferably a substituted or unsubstituted alkyl group having 6 to 12 carbon atoms (2-ethylhexyl group, n-octyl group). N-decyl group, n-dodecyl group, benzyl group).

The compound represented by the general formula (102) can be synthesized by a known method described in JP-A-11-12219.
Specific examples of the compound represented by the general formula (102) are given below, but the present invention is not limited to the following specific examples.

Moreover, as a compound containing a cyano group which is one of the wavelength dispersion adjusting agents used in the present invention, a compound represented by the general formula (103) is preferably used.
General formula (103)

In the general formula (103), Q ³¹ and Q ³² each independently represents an aromatic ring. X ³¹ and X ³² each represent a hydrogen atom or a substituent, and at least one of them represents a cyano group, a carbonyl group, a sulfonyl group, or an aromatic heterocycle.
The aromatic ring represented by Q ³¹ and Q ³² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.

  The aromatic hydrocarbon ring is preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, a benzene ring or a naphthalene ring), more preferably 6 to 20 carbon atoms. It is an aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms, and most preferably a benzene ring.

  The aromatic heterocycle is preferably an aromatic heterocycle containing a nitrogen atom or a sulfur atom. Specific examples of the heterocyclic ring include, for example, thiophene ring, imidazole ring, pyrazole ring, pyridine ring, pyrazine ring, pyridazine ring, triazole ring, triazine ring, indole ring, indazole ring, purine ring, thiazoline ring, thiazole ring, thiadiazole. Ring, oxazoline ring, oxazole ring, oxadiazole ring, quinoline ring, isoquinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinazoline ring, cinnoline ring, pteridine ring, acridine ring, phenanthroline ring, phenazine ring, tetrazole ring, benz Examples include an imidazole ring, a benzoxazole ring, a benzthiazole ring, a benzotriazole ring, and a tetrazaindene ring. The aromatic hetero ring is preferably a pyridine ring, a triazine ring or a quinoline ring.

The aromatic ring represented by Q ³¹ and Q ³² is preferably an aromatic hydrocarbon ring, more preferably a benzene ring.
Q ³¹ and Q ³² may further have a substituent, and the above-described substituent T is preferable.

X ³¹ and X ³² each represent a hydrogen atom or a substituent, and at least one of them represents a cyano group, a carbonyl group, a sulfonyl group, or an aromatic heterocycle. The substituent T described above can be applied to the substituents represented by X ³¹ and X ³² . In addition, the substituent represented by X ³¹ and X ³² may be further substituted with another substituent, and X ³¹ and X ³² may each be condensed to form a ring structure.

X ³¹ and X ³² are preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group, or an aromatic heterocycle, and more preferably a cyano group, a carbonyl group, a sulfonyl group, An aromatic heterocycle, more preferably a cyano group or a carbonyl group, and particularly preferably a cyano group or an alkoxycarbonyl group (—C (═O) OR (R is an alkyl group having 1 to 20 carbon atoms, 6 carbon atoms). ~ 12 aryl groups and combinations thereof).

The general formula (103) is preferably represented by the following general formula (103-A).
General formula (103-A)

In formula (103-A), represents a ^{R 31, R 32, R 33} , R 34, R 35, R 36, R 37, R 38, R 39 and R ³⁰ are each independently a hydrogen atom or a substituent. X ³¹ and X ³² have the same meanings as those in formula (103), and preferred ranges are also the same.

R ³¹ , R ³² , R ³⁴ , R ³⁵ , R ³⁶ , R ³⁷ , R ³⁹ and R ³⁰ each independently represent a hydrogen atom or a substituent, and the substituent T described above can be applied as the substituent. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ³¹ , R ³² , R ³⁴ , R ³⁵ , R ³⁶ , R ³⁷ , R ³⁹ and R ³⁰ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group Group, a hydroxy group, and a halogen atom, more preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, still more preferably a hydrogen atom and a carbon 1-12 alkyl group, Particularly preferred are a hydrogen atom and a methyl group, and most preferred is a hydrogen atom.

R ³³ and R ³⁸ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom, more preferably a hydrogen atom or a carbon number. An alkyl group having 1 to 20 carbon atoms, an amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and a hydroxy group, and more preferably a hydrogen atom and 1 to 12 carbon atoms. And an alkyl group having 1 to 12 carbon atoms, particularly preferably a hydrogen atom.

The general formula (103) is more preferably represented by the following general formula (103-B).
General formula (103-B)

In Formula (103-B), R ³³ and R ³⁸ have the same meanings as those in formula (103-A), and the preferred scopes are also same. X ³³ represents a hydrogen atom or a substituent.

X ³³ represents a hydrogen atom or a substituent. As the substituent, the above-described substituent T can be applied, and if possible, the substituent may be further substituted with a substituent. X ³³ is preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group or an aromatic heterocycle, more preferably a cyano group, a carbonyl group, a sulfonyl group or an aromatic heterocycle. A ring, more preferably a cyano group or a carbonyl group, and particularly preferably a cyano group or an alkoxycarbonyl group (—C (═O) OR ³⁰¹ (R ³⁰¹ is an alkyl group having 1 to 20 carbon atoms, 6 to 6 carbon atoms). 12 aryl groups and combinations thereof)).

The general formula (103) is more preferably represented by the general formula (103-C).
General formula (103-C)

In General Formula (103-C), R ³³ and R ³⁸ have the same meanings as those in General Formula (103-A), and preferred ranges thereof are also the same. R ³⁰² represents an alkyl group having 1 to 20 carbon atoms.

R ³⁰² is preferably an alkyl group having 2 to 12 carbon atoms, more preferably an alkyl group having 4 to 12 carbon atoms, and more preferably when both R ³³ and R ³⁸ are hydrogen atoms, An alkyl group having 6 to 12 carbon atoms, particularly preferably an n-octyl group, a tert-octyl group, a 2-ethylhexyl group, an n-decyl group or an n-dodecyl group, most preferably 2-ethyl Hexyl group.

R ³⁰² is preferably an alkyl group having a molecular weight of 300 or more and a carbon number of 20 or less and a compound represented by the general formula (103-C) when R ³³ and R ³⁸ are other than hydrogen. Is preferred.

  The compound represented by the general formula (103) of the present invention can be synthesized by the method described in Journal of American Chemical Society 63, 3452 (1941).

  Specific examples of the compound represented by the general formula (103) are given below, but the present invention is not limited to the following specific examples.

  The cellulose acylate film used in the present invention may contain fine particles as a matting agent. Examples of the fine particles include silicon dioxide (silica), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, and magnesium silicate. And calcium phosphate. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / liter or more, and more preferably 100 to 200 g / liter or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

  These fine particles usually form secondary particles having an average particle size of 0.1 to 3.0 μm, and these fine particles exist in the film as aggregates of primary particles, and 0.1 to 0.1 μm on the film surface. An unevenness of 3.0 μm is formed. The secondary average particle size is preferably 0.2 μm to 1.5 μm, more preferably 0.4 μm to 1.2 μm, and most preferably 0.6 μm to 1.1 μm. For the primary and secondary particle sizes, the particles in the film were observed with a scanning electron microscope, and the diameter of a circle circumscribing the particles was defined as the particle size. In addition, 200 particles were observed at different locations, and the average value was taken as the average particle size.

  As fine particles of silicon dioxide, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.) can be used. Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

  Among these, Aerosil 200V and Aerosil R972V are fine particles of silicon dioxide having a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more, and a coefficient of friction while keeping the turbidity of the optical film low. It is particularly preferable because it has a great effect of reducing the effect.

In order to obtain a cellulose acylate film having particles having a small secondary average particle size in the present invention, several methods are conceivable when preparing a dispersion of fine particles. For example, a method of preparing a fine particle dispersion in which a solvent and fine particles are mixed with stirring in advance, adding this fine particle dispersion to a small amount of cellulose acylate solution separately prepared, stirring and dissolving, and further mixing with the main cellulose acylate dope solution There is. This method is a preferable preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are more difficult to reaggregate. In addition, after adding a small amount of cellulose ester to the solvent and dissolving with stirring, add the fine particles to this and disperse with a disperser to make this fine particle additive solution, and mix this fine particle additive solution with the dope solution using an in-line mixer. There is also a way to do it. Although this invention is not limited to these methods, 5-30 mass% is preferable, as for the density | concentration of silicon dioxide when silicon dioxide microparticles | fine-particles are mixed and disperse | distributed with a solvent etc., 10-25 mass% is more preferable, 15-20 Mass% is most preferred. A higher dispersion concentration is preferable because the liquid turbidity with respect to the added amount is lowered, and haze and aggregates are improved. The addition amount of the matting agent in the final cellulose acylate dope solution is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and 0.08 to 0.16 g per 1 m ^2. Most preferred.

  The solvent used is preferably lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the solvent used at the time of film forming of a cellulose ester. Examples thereof include a solvent selected from halogenated hydrocarbons having 1 to 7 carbon atoms. One type of solvent may be used, or two or more types may be used in combination.

  In addition to the above-mentioned compound for reducing optical anisotropy and wavelength dispersion adjusting agent, the cellulose acylate film has various additives (for example, plasticizers, ultraviolet inhibitors, deterioration inhibitors, release agents, infrared rays). Absorbent) and the like, which can be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of ultraviolet absorbing material at 20 ° C. or lower and 20 ° C. or higher, and similarly, mixing of a plasticizer is described in, for example, JP-A-2001-151901. Furthermore, infrared absorbing dyes are described, for example, in JP-A No. 2001-194522. Moreover, the addition time may be added at any time in the dope preparation step, but may be added by adding an additive to the final preparation step of the dope preparation step. Furthermore, the amount of each material added is not particularly limited as long as the function is manifested. Moreover, when a cellulose acylate film is formed from a multilayer, the kind and addition amount of the additive of each layer may differ. For example, although it describes in Unexamined-Japanese-Patent No. 2001-151902 etc., these are techniques conventionally known. For these details, materials described in detail on pages 16 to 22 in the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical No. 2001-1745, published on March 15, 2001, Japan Institute of Invention) are preferably used.

  In the cellulose acylate film used in the present invention, the total content of compounds having a molecular weight of 3000 or less is preferably 5 to 45% based on the weight of the cellulose acylate. More preferably, it is 10-40%, More preferably, it is 15-30%. As described above, these compounds include compounds that reduce optical anisotropy, wavelength dispersion modifiers, ultraviolet inhibitors, plasticizers, deterioration inhibitors, fine particles, release agents, infrared absorbers, etc. Is preferably 3000 or less, more preferably 2000 or less, and still more preferably 1000 or less. When the total amount of these compounds is 5% or less, the properties of the cellulose acylate alone are likely to be produced, and there are problems such that the optical performance and physical strength are likely to fluctuate with changes in temperature and humidity. Moreover, when the total amount of these compounds is 45% or more, problems such as exceeding the limit of compound compatibility in the cellulose acylate film and depositing on the film surface to cause the film to become cloudy (crying out of the film) occur. It becomes easy.

  In the present invention, it is preferable to use a cellulose acylate film produced by a solvent cast method. Specifically, it is preferable to use a film produced using a solution (dope) obtained by dissolving cellulose acylate in an organic solvent. The main solvent used for the preparation of the dope is selected from organic solvents, preferably selected from esters having 3 to 12 carbon atoms, ketones, ethers, and halogenated hydrocarbons having 1 to 7 carbon atoms. . Esters, ketones and ethers may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and COO—) can also be used as a main solvent. It may have a functional group of In the case of the main solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

  As described above, the cellulose acylate film that can be used in the present invention may use a chlorinated halogenated hydrocarbon as a main solvent, and is described in JIII Journal of Technical Disclosure 2001-1745 (pages 12 to 16). As described above, a non-chlorine solvent may be used as the main solvent, and the cellulose acylate film that can be used in the present invention is not particularly limited.

  In addition, the cellulose acylate solution, the solvent thereof, the dissolution method thereof, and the like are disclosed in the following publications and are preferred embodiments. For example, JP-A-2000-95876, JP-A-12-95877, JP-A-10-324774, JP-A-8-152514, JP-A-10-330538, JP-A-9-95538, and JP-A-9 JP-A-95557, JP-A-10-235664, JP-A-12-63534, JP-A-11-21379, JP-A-10-182853, JP-A-10-278056, JP-A-10-279702, JP-A-10- No. 323853, JP-A-10-237186, JP-A-11-60807, JP-A-11-152342, JP-A-11-292988, JP-A-11-60752, JP-A-11-60752, and the like. ing. These publications describe not only a preferable solvent for preparing a cellulose acylate solution, but also a physical property of the solution and coexisting substances to coexist, which is also a preferable embodiment in the present invention.

  The dissolution method used when preparing the cellulose acylate solution (dope) is not particularly limited, and may be room temperature, and further, a cooling dissolution method or a high temperature dissolution method, or a combination thereof. Regarding the preparation of the cellulose acylate solution, and further the solution concentration and filtration steps involved in the dissolution step, 22 of the Japan Society for Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Invention Association) Production processes described in detail on pages 25 to 25 are preferably used.

  The transparency of the cellulose acylate solution (dope) is preferably 85% or more, more preferably 88% or more, and further preferably 90% or more. It is preferable that various additives are sufficiently dissolved in the cellulose acylate dope solution. As a specific method for calculating the dope transparency, the dope solution was poured into a 1 cm square glass cell, and the absorbance at 550 nm was measured with a spectrophotometer (UV-3150, Shimadzu Corporation). Only the solvent is measured in advance as a blank, and the transparency of the cellulose acylate solution can be calculated from the ratio to the absorbance of the blank.

Next, a method for producing a cellulose acylate film using the cellulose acylate solution will be described. As a method and equipment for producing a cellulose acylate film that can be used in the present invention, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film can be used. For example, the dope (cellulose acylate solution) prepared from a dissolving machine (kettle) is temporarily stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is sent from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of rotations, and the dope is run endlessly from the die (slit) of the pressure die. The dry-dried dope film (also referred to as web) is peeled off from the metal support at a peeling point that is uniformly cast on the metal support and substantially rounds the metal support. The both ends of the obtained web are sandwiched between clips, transported by a tenter while holding the width and dried, and then the obtained film is mechanically transported by a roll group of a drying device, dried, and then rolled by a winder. Wind up to a predetermined length. The combination of the tenter and the roll group dryer varies depending on the purpose. Furthermore, the cellulose acylate film used in the present invention is often provided with a coating device for surface processing to a polarizing film. These are described in detail on pages 25 to 30 in the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Inventions). Including), metal support, drying, peeling and the like, and can be preferably used in the present invention.
Moreover, 10-120 micrometers is preferable, as for the thickness of a cellulose acylate film, 20-100 micrometers is more preferable, and 30-90 micrometers is more preferable.

Regarding the change in optical performance due to the environmental change of the cellulose acylate film, the amount of change in Re and Rth of the cellulose acylate film treated at 60 ° C. and 90% RH for 240 hours is preferably 15 nm or less. More preferably, it is 12 nm or less, and further preferably 10 nm or less.
Moreover, it is preferable that the change amount of Re and Rth of the cellulose acylate film treated at 80 ° C. for 240 hours is 15 nm or less. More preferably, it is 12 nm or less, and further preferably 10 nm or less.
In the cellulose acylate film used in the present invention, the volatilization amount of the compound from the cellulose acylate film treated at 80 ° C. for 240 hours is preferably 30% or less for the compound for reducing Rth and the compound for reducing ΔRth. More preferably, it is 25% or less, and more preferably 20% or less.
The volatilization amount from the cellulose acylate film was determined by dissolving the film treated at 80 ° C. for 240 hours and the untreated cellulose acylate film in a solvent, detecting the compound by liquid high-speed chromatography, and detecting the peak area of the compound Was calculated by the following formula as the amount of the compound remaining in the film.
Volatilization amount (%) = {(remaining compound amount in untreated product) − (remaining compound amount in treated product)} / (remaining compound amount in untreated product) × 100

  The cellulose acylate film has a glass transition temperature Tg of 80 to 165 ° C. From the viewpoint of heat resistance, Tg is more preferably 100 to 160 ° C, and particularly preferably 110 to 150 ° C. The measurement of the glass transition temperature (Tg) was carried out using a differential scanning calorimeter (DSC 2910, TA in) with a cellulose acylate film sample of 10 mg that can be used in the present invention at a temperature rising / falling rate of 5 ° C./min from room temperature to 200 ° C. The calorimetric measurement can be carried out with a (strument), and the glass transition temperature (Tg) can be calculated.

  The haze of the cellulose acylate film is preferably 0.01 to 2.0%. More preferably, it is 0.05 to 1.5%, and further preferably 0.1 to 1.0%. The haze is measured, for example, by using a cellulose acylate film sample 40 mm × 80 mm that can be used in the present invention at 25 ° C. and 60% RH, using a haze meter (HGM-2DP, Suga Test Instruments) and JIS K-6714. Can be measured according to.

  It is preferable that both the in-plane retardation (Re) and the retardation in the film thickness direction (Rth) of the cellulose acylate film are small in change due to humidity. Specifically, the difference ΔRth (= Rth10% RH−Rth80% RH) between the Rth value at 25 ° C. and 10% RH and the Rth value at 25 ° C. and 80% RH is preferably 0 to 50 nm. More preferably, it is 0-40 nm, More preferably, it is 0-35 nm.

The cellulose acylate film has an equilibrium water content of 0 to 4% at 25 ° C. and 80% RH regardless of the film thickness so as not to impair the adhesion with a water-soluble polymer such as polyvinyl alcohol. Is more preferable, 0.1 to 3.5% is more preferable, and 1 to 3% is particularly preferable. By setting the equilibrium moisture content to 4% or less, the dependency of retardation due to humidity change can be further reduced, which is preferable.
The moisture content was measured by a Karl Fischer method using a cellulose acylate film sample 7 mm × 35 mm with a moisture measuring device and a sample drying apparatus (CA-03, VA-05, both manufactured by Mitsubishi Chemical Corporation), and a moisture content (g) Is divided by the sample weight (g).

The moisture permeability of the cellulose acylate film is measured under the conditions of a temperature of 60 ° C. and a humidity of 95% RH based on JIS standard JISZ0208, and is 400 to 2000 g / m ² · 24 h in terms of a film thickness of 80 μm. Is preferred. More preferably 500~1800g / m ² · 24h, and particularly preferably 600~1600g / m ² · 24h. By setting it to 2000 g / m ² · 24 h or less, it becomes possible to easily maintain the absolute value of the humidity dependence of Re and Rth of the cellulose acylate film at 0.5 nm /% RH or less, and for the liquid crystal display device. A change in color and a decrease in viewing angle can be more effectively suppressed. In addition, by setting the moisture permeability of the cellulose acylate film to 400 g / m ² · 24 h or more, the adhesive of the cellulose acylate film can be easily dried and the adhesiveness is improved.
If the film thickness of the cellulose acylate film is thick, the moisture permeability becomes small, and if the film thickness is thin, the moisture permeability becomes large. Therefore, it is preferable to set the standard to 80 μm for any film thickness. In the present invention, the film thickness was obtained as 80 μm-converted moisture permeability = measured moisture permeability × measured film thickness μm / 80 μm.
The measurement method of moisture permeability is "Polymer Physical Properties II" (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294: Measurement of vapor permeation (mass method, thermometer method, vapor pressure method, adsorption amount method) The cellulose acylate film sample 70 mmφ that can be used in the present invention is conditioned at 25 ° C., 90% RH, 60 ° C., and 95% RH for 24 hours, respectively. (KK-709007, Toyo Seiki Co., Ltd.) calculates the amount of water per unit area (g / m ² ) according to JIS Z-0208, and obtains moisture permeability = weight after humidity adjustment−weight before humidity adjustment. It was.

The dimensional stability of the cellulose acylate film is such that the dimensional change rate when left standing for 24 hours under conditions of 60 ° C. and 90% RH (high humidity) and 24 hours under the conditions of 90 ° C. and 5% RH. It is preferable that the dimensional change rate when standing still (high temperature) is 0.5% or less. More preferably, it is 0.3% or less, More preferably, it is 0.15% or less.
The dimensional change rate is determined by the method described below. That is, two cellulose acylate film samples 30 mm × 120 mm were prepared, humidity-controlled at 25 ° C. and 60% RH for 24 hours, and an automatic pin gauge (Shinto Kagaku Co., Ltd.) with 6 mmφ holes at both ends. Opened at intervals, the original size (L ₀ ) of the punch interval was used. After measuring the punch interval dimension (L ₁ ) after one sample was treated at 60 ° C. and 90% RH for 24 hours, the other sample was treated at 90 ° C. and 5% RH for 24 hours. The dimension (L ₂ ) of the punch interval was measured. Measurement was made to a minimum scale of 1/1000 mm at all intervals. Dimensional change rate of 60 ° C. and 90% RH (high humidity) = {| L ₀ −L ₁ | / L ₀ } × 100, Dimensional change rate of 90 ° C. and 5% RH (high temperature) = {| L ₀ The dimensional change rate was determined as −L ₂ | / L ₀ } × 100.

Elastic modulus of the cellulose acylate film is preferably 200 to 500 kgf / mm ^2, more preferably 240~470kgf / mm ^2, more preferably from 270~440kgf / mm ^2. The elastic modulus is a value obtained by measuring a stress at 0.5% elongation in a 70% atmosphere at 23 ° C. in a 70% atmosphere using Toyo Baldwin's universal tensile tester STM T50BP.

The cellulose acylate film preferably has a photoelastic coefficient of 50 × 10 ⁻¹³ cm ² / dyne or less, more preferably 30 × 10 ⁻¹³ cm ² / dyne or less, and 20 × 10 ⁻¹³ cm. More preferably, it is ² / dyne or less. The photoelastic coefficient is determined by applying a tensile stress to the major axis direction of a 12 mm x 120 mm cellulose acylate film sample, and measuring the retardation with an ellipsometer (M150, JASCO Corporation). It can be calculated from the amount of change.

  A sample 100 × 100 mm was prepared, and stretched in the machine transport direction (MD direction) or the vertical direction (TD direction) using a fixed uniaxial stretching machine at a temperature of 140 ° C. The front retardation of each sample before and after stretching was measured using an automatic birefringence meter KOBRA21ADH. The detection of the slow axis was determined from the orientation angle obtained during the retardation measurement. The change in Re is preferably small by stretching, specifically, in-plane front retardation (nm) of a film obtained by stretching Re (n) by n (%), in-plane of a film not stretched by Re (0) It is preferable to have | Re (n) −Re (0) | /n≦1.0 when the front retardation (nm) is satisfied, and | Re (n) −Re (0) | / n ≦ 0. 3 or less is more preferable.

  Since the polarizing film of the cellulose acylate film has an absorption axis in the machine transport direction (MD direction), the cellulose acylate film preferably has a slow axis in the vicinity of the MD direction or in the vicinity of TD. Light leakage and color change can be reduced by making the slow axis parallel or orthogonal to the polarizing film. The vicinity means that, for example, the slow axis and the MD or TD direction are in the range of 0 to 10 °, preferably 0 to 5 °.

  When the cellulose acylate film is stretched in a direction having a slow axis in the film plane, the front retardation is increased, and when stretched in a direction perpendicular to the direction having the slow axis, the front retardation is decreased. This indicates that the intrinsic birefringence is positive, and it is effective to stretch in the direction perpendicular to the slow axis in order to cancel the retardation developed in the cellulose acylate film. As this method, for example, when the film has a slow axis in the machine conveyance direction (MD direction), the front retardation can be reduced by using tenter stretching in a direction perpendicular to MD (TD direction). Conceivable. As an opposite example, when the TD direction has a slow axis, it is conceivable to reduce the front retardation by increasing the tension of the machine transport roll in the MD direction and stretching.

  When the cellulose acylate film is stretched in a direction having a slow axis, the front retardation may be reduced, and when stretched in a direction perpendicular to the direction having a slow axis, the front retardation may be increased. This indicates that the intrinsic birefringence is negative, and it is effective to stretch in the same direction as the slow axis in order to cancel the retardation developed in the film. As this method, for example, when the cellulose acylate film has a slow axis in the machine conveyance direction (MD direction), the front retardation is reduced by increasing the tension of the machine conveyance roll in the MD direction and stretching. It is possible. As an opposite example, when the TD direction has a slow axis, it is conceivable to reduce the front retardation by using tenter stretching in a direction perpendicular to the MD (TD direction).

  It is preferable to dry on the conditions that the amount of residual solvents with respect to the said cellulose acylate film is the range of 0.01-1.5 mass%, More preferably, it is 0.01-1.0 mass%. Curling can be suppressed by setting the residual solvent amount of the polarizing film used in the present invention to 1.5% or less. More preferably, it is 1.0% or less. This is presumably because free deposition is reduced by reducing the amount of residual solvent during film formation by the above-described solvent casting method.

The cellulose acylate film preferably has a hygroscopic expansion coefficient of 30 × 10 ⁻⁵ /% RH or less. The hygroscopic expansion coefficient is preferably 15 × 10 ⁻⁵ /% RH or less, and more preferably 10 × 10 ⁻⁵ /% RH or less. Further, the hygroscopic expansion coefficient is preferably small, but usually a value of 1.0 × 10 ⁻⁵ /% RH or more. The hygroscopic expansion coefficient indicates the amount of change in the length of the sample when the relative humidity is changed at a constant temperature.

The cellulose acylate film can achieve improved adhesion to the cellulose acylate film by optionally performing a surface treatment. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs in a low-pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferable. A plasma-excitable gas is a gas that is plasma-excited under the above conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail in pages 30 to 32 in the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention), and are preferably used in the present invention. be able to.

  One effective means for surface treatment of the cellulose acylate film is alkali saponification treatment. In this case, the contact angle on the surface of the cellulose acylate film after the alkali saponification treatment is preferably 55 ° or less. More preferably, it is 50 ° or less, and further preferably 45 ° or less. The contact angle evaluation method can be used as an evaluation of hydrophilicity / hydrophobicity by an ordinary method in which a water droplet having a diameter of 3 mm is dropped on the surface of the film after the alkali saponification treatment and the angle formed by the surface of the cellulose acylate film and the water droplet is obtained.

As an index of light durability of the cellulose acylate film, the color difference ΔE * ab of the cellulose acylate film irradiated with super xenon light for 240 hours is preferably 20 or less. More preferably, it is 18 or less, and it is still more preferable that it is 15 or less. The color difference can be measured using, for example, UV3100 (manufactured by Shimadzu Corporation). The measurement is carried out by adjusting the cellulose acylate film to 25 ° C. and 60% RH for 2 hours and then measuring the color of the cellulose acylate film before irradiation with xenon light, and initial values (L0 ^* , a0 ^* , b0 ^* ). Ask for. The cellulose acylate film alone is irradiated with xenon light for 240 hours under the conditions of 150 W / m ² , 60 ° C. and 50% RH with a super xenon weather meter SX-75 (manufactured by Suga Test Instruments Co., Ltd.). After the elapse of a predetermined time, the cellulose acylate film is taken out from the thermostatic bath, adjusted to 25 ° C. and 60% RH for 2 hours, then subjected to color measurement again, and values after irradiation (L1 ^* , a1 ^* , b1 ^* ). Asked. From these, the color difference ΔE ^* ab = ((L0 ^* −L1 ^* ) ^ 2+ (a0 ^* −a1 ^* ) ^ 2+ (b0 ^* −b1 ^* ) ^ 2) ^ 0.5 can be measured.

  In the liquid crystal display device of the present invention, the cellulose acylate film may be used as a protective film for a polarizing plate. In the aspect in which the liquid crystal display device of the present invention has an optically anisotropic layer formed from a liquid crystalline composition, the cellulose acylate film may be used as a support for the optically anisotropic layer. Good.

[Polarizer]
In the present invention, a polarizing film (sometimes referred to as “polarizing film”) and a pair of protective films (also referred to as “protective film”) sandwiching the polarizing film, or a protective film provided on at least one side of the polarizing plate You may use the polarizing plate which has. For example, a polarizing film obtained by dyeing a polarizing film made of a polyvinyl alcohol film or the like with iodine, stretching, and laminating both surfaces with a protective film can be used. The polarizing plate is disposed outside the liquid crystal cell. It is preferable that a pair of polarizing plates each including a polarizing film and a pair of protective films sandwiching the polarizing film are disposed with the liquid crystal cell interposed therebetween.
In addition, as above-mentioned, it is preferable that the protective film arrange | positioned at the liquid crystal cell side among the protective films is the said cellulose acylate film.

[Polarized film]
Examples of the polarizing film include an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film. The iodine polarizing film and the dye polarizing film are generally produced using a polyvinyl alcohol film.

  Further, the moisture permeability of the protective film is important for improving the productivity of the polarizing plate. That is, the polarizing film and the protective film are bonded together with an aqueous adhesive, and the adhesive solvent is dried by diffusing in the protective film. The higher the moisture permeability of the protective film, the faster the drying and the higher the productivity. However, if the protective film is too high, moisture will enter the polarizing film depending on the usage environment (high humidity) of the liquid crystal display device. There is a tendency for the polarization ability to decrease.

  The polarizing film used in the present invention preferably has an absorption axis having a predetermined angle with respect to the longitudinal direction. When the absorption axis of the polarizing film has a predetermined angle with respect to the longitudinal direction, it can be easily pasted with a roll-to-roll when pasting with a protective film whose slow axis coincides with the longitudinal direction. it can. For example, as described in JP-A-2003-207628, a pair of protective films prepared in a long shape is bonded to both sides of a polarizing film prepared in a long shape, and a long laminate is obtained. Through a process of cutting (punching) into a desired size, a single plate polarizing plate can be obtained with high yield.

[adhesive]
The adhesive between the polarizing film and the protective film is not particularly limited, and examples thereof include PVA-based resins (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, and oxyalkylene group) and boron compound aqueous solution. PVA resin is preferable. The thickness of the adhesive layer is preferably 0.01 to 10 μm, particularly preferably 0.05 to 5 μm after drying.

[Integrated manufacturing process of polarizing film and protective film]
The polarizing plate used in the present invention usually has a drying step in which the polarizing film is stretched and then contracted to reduce the volatile content, but after drying or after a protective film is bonded to at least one side during drying, It is preferable to have a heating step. In an embodiment in which the protective film also serves as a support for the optically anisotropic layer, it is preferable to heat the protective film after bonding the protective film on one side and the transparent support having the optically anisotropic layer on the opposite side. As a specific application method, during the film drying process, a protective film is applied to the polarizing film with an adhesive while holding both ends, and then both ends are cut off, or after drying, polarized from the both ends holding part. There is a method of releasing a film for a film, cutting off both ends of the film, and then attaching a protective film. As a method for cutting off the ears, general techniques such as a method of cutting with a cutter such as a blade or a method of using a laser can be used. After bonding, it is preferable to heat in order to dry the adhesive and improve the polarization performance. The heating condition varies depending on the adhesive, but in the case of an aqueous system, it is preferably 30 ° C. or higher, more preferably 40 to 100 ° C., and further preferably 50 to 90 ° C. It is more preferable in terms of performance and production efficiency that these processes are manufactured in a consistent line.

[Performance of polarizing plate]
The optical properties and durability (short-term and long-term storage stability) of the polarizing plate in the present invention should be equivalent to or better than those of commercially available super high contrast products (for example, HLC2-5618 manufactured by Sanlitz Co., Ltd.). Is preferred. Specifically, the visible light transmittance is 42.5% or more, and the degree of polarization {(Tp−Tc) / (Tp + Tc)} ^1/2 ≧ 0.9995 (where Tp is parallel transmittance and Tc is orthogonal transmission) The rate of change in light transmittance before and after standing in an atmosphere of 60 ° C. and a humidity of 90% RH for 500 hours and 80 ° C. in a dry atmosphere for 500 hours is 3% or less based on the absolute value, Further, it is preferably 1% or less, and the rate of change in polarization degree is preferably 1% or less, more preferably 0.1% or less, based on the absolute value.

[Optically anisotropic layer]
The liquid crystal display device of the present invention may have an optically anisotropic layer. The optically anisotropic layer is used in a liquid crystal display device in order to eliminate image coloring or enlarge a viewing angle. In the present invention, as described above, it is essential to dispose cellulose acylate having predetermined optical characteristics in a predetermined axial relationship, and the optically anisotropic layer is not an essential member. Further, for example, in an aspect in which birefringence is added to one or both of the pair of protective films of the polarizing plate to function as an optically anisotropic layer, it is not necessary to provide a separate optically anisotropic layer.

  The material for the optically anisotropic layer is not particularly limited, and may be a stretched polymer film or a layer formed from a liquid crystalline composition. Moreover, the laminated body of 2 or more layers which has the optically anisotropic layer formed from the liquid crystalline composition on the support body of the optically anisotropic layer which consists of a stretched polymer film may be sufficient.

Examples of the liquid crystalline compound used for forming the optically anisotropic layer include rod-like liquid crystalline molecules and discotic liquid crystalline molecules. The rod-like liquid crystal molecule and the discotic liquid crystal molecule (discotic liquid crystal compound) may be a high-molecular liquid crystal or a low-molecular liquid crystal, and further include those in which the low-molecular liquid crystal is cross-linked and no longer exhibits liquid crystallinity.
When a rod-like liquid crystalline compound is used for the production of the optically anisotropic layer, the orientation direction of the major axis of the rod-like liquid crystalline molecule may be any of perpendicular, parallel, and hybrid orientation with respect to the layer surface. Will be decided accordingly. In the case of aligning vertically or in parallel, it is preferable that the average direction of the axis projected from the major axis on the layer surface is parallel to the alignment axis. The same applies to the case where a discotic liquid crystalline compound is used for the production of the optically anisotropic layer, and the orientation direction of the discotic surface of the discotic liquid crystalline molecules may be any of perpendicular, parallel and hybrid orientation to the layer surface. It is often determined according to the desired optical properties. As an example of the optically anisotropic layer, it is formed from a composition containing a discotic liquid crystalline compound, and the average direction of the axis of the discotic liquid crystalline molecules projected in the layer onto the support surface is the orientation axis. An optically anisotropic layer that is parallel to the rubbing axis (for example, the rubbing axis) and an angle (tilt angle) formed by the discotic liquid crystalline molecules between the disc plane and the layer plane in the layer. Is an optically anisotropic layer fixed in a hybrid alignment state in which changes in the depth direction.
The alignment of the liquid crystalline molecules is the properties of the alignment film used in the formation, the orientation of the rubbing axis applied to the surface of the alignment film, the properties of each material contained in the liquid crystalline composition used in the formation, etc. Can be adjusted by.

《Bar-shaped liquid crystalline molecules》
Examples of rod-like liquid crystalline molecules include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.
The rod-like liquid crystalline molecule includes a metal complex. A liquid crystal polymer containing rod-like liquid crystalline molecules in the repeating unit can also be used as the rod-like liquid crystalline molecules. In other words, the rod-like liquid crystal molecule may be bonded to a (liquid crystal) polymer.
For rod-like liquid crystalline molecules, see Chapter 4, Chapter 7 and Chapter 11 in the Chemistry of the Quarterly Chemical Review Vol. 22 Liquid Crystal Chemistry (1994) edited by the Chemical Society of Japan, and the 142nd Committee of the Japan Society for the Promotion of Science. Described in Chapter 3. The birefringence of the rod-like liquid crystal molecule is preferably in the range of 0.001 to 0.7.

  The rod-like liquid crystalline molecule preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably a radically polymerizable unsaturated group or a cationically polymerizable group. Specifically, for example, the polymerizable groups described in paragraphs [0064] to [0086] of JP-A-2002-62427 are described. Group and a polymerizable liquid crystal compound.

《Discotic liquid crystalline compound》
Discotic liquid crystalline compounds are disclosed in various documents (C. Destrade et al., Mol. Crysr. Liq. Cryst., Vol. 71, page 111 (1981); edited by The Chemical Society of Japan, Quarterly Chemical Review, No. 22, Liquid Crystal Chemistry, Chapter 5, Chapter 10 Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 (1985); J. Zhang et al., J Am. Chem. Soc., Vol. 116, page 2655 (1994)) can be widely used.

The discotic liquid crystalline compound preferably has a polymerizable group, for example, as described in JP-A-8-27284 so that it can be fixed by polymerization. For example, a structure in which a polymerizable group is bonded as a substituent to the discotic core of a discotic liquid crystalline compound can be considered, but if a polymerizable group is directly connected to the discotic core, the alignment state can be maintained in the polymerization reaction. It becomes difficult. Therefore, a structure having a linking group between the discotic core and the polymerizable group is preferable. That is, the discotic liquid crystalline compound having a polymerizable group is preferably a compound represented by the following formula (III).
Formula (III) D (-LP) _n
In formula (III), D is a discotic core, L is a divalent linking group, P is a polymerizable group, and n is an integer of 4 to 12.

  Preferred specific examples of the discotic core (D), the divalent linking group (L), and the polymerizable group (P) in the formula (III) are (D1) described in JP-A No. 2001-4837, respectively. To (D15), (L1) to (L25), and (P1) to (P18), and the contents described in the publication can be preferably used.

  These liquid crystalline compounds may be fixed in a state of being vertically aligned with respect to the layer surface in the optically anisotropic layer. The “layer surface” here refers to a surface parallel to the surface of the support on which the optically anisotropic layer is formed and a surface deviated by ± 5 degrees from the parallel surface. Further, it is preferably substantially uniformly aligned, more preferably fixed in a substantially uniformly aligned state, and further more preferably the liquid crystalline compound is fixed by a polymerization reaction. preferable. In the case of forming from a composition containing a discotic liquid crystalline compound having a polymerizable group, the disc surface of the discotic liquid crystalline molecules is preferably aligned substantially perpendicularly to the layer surface. Substantially perpendicular means that the average angle (average inclination angle) between the disc surface of the discotic liquid crystal molecules and the surface of the optically anisotropic layer is in the range of 70 to 90 degrees.

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

[Fixation of alignment state of liquid crystalline compounds]
It is preferable to fix the aligned liquid crystal compound molecules while maintaining the alignment state. The immobilization is preferably carried out by a polymerization reaction of a polymerizable group introduced into the liquid crystal compound. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator, and a photopolymerization reaction is more preferable. Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-carbonization. A hydrogen-substituted aromatic acyloin compound (described in US Pat. No. 2,722,512), a polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a triarylimidazole dimer and p-aminophenyl ketone Combinations (described in U.S. Pat. No. 3,549,367), acridine and phenazine compounds (described in JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,221,970). Included in the gazette).

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

[Vertical alignment film]
When forming an optically anisotropic layer by vertically aligning a liquid crystalline compound on the alignment film side, it is important to reduce the surface energy of the alignment film. Specifically, the surface energy of the alignment film is lowered by the functional group of the polymer, thereby bringing the liquid crystalline compound into a standing state. As the functional group for reducing the surface energy of the alignment film, a hydrocarbon group having 10 or more fluorine atoms and carbon atoms is effective. In order to make a fluorine atom or a hydrocarbon group exist on the surface of the alignment film, it is preferable to introduce a fluorine atom or a hydrocarbon group into the side chain rather than the main chain of the polymer. The fluorine-containing polymer preferably contains 0.05 to 80% by weight of fluorine atoms, more preferably 0.1 to 70% by weight, and 0.5 to 65% by weight. More preferably, it is most preferably contained in a proportion of 1 to 60% by weight. The hydrocarbon group is an aliphatic group, an aromatic group or a combination thereof. The aliphatic group may be cyclic, branched or linear. The aliphatic group is preferably an alkyl group (may be a cycloalkyl group) or an alkenyl group (may be a cycloalkenyl group). The hydrocarbon group may have a substituent that does not exhibit strong hydrophilicity, such as a halogen atom. The number of carbon atoms of the hydrocarbon group is preferably 10 to 100, more preferably 10 to 60, and most preferably 10 to 40. The main chain of the polymer preferably has a polyimide structure or a polyvinyl alcohol structure.

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

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

  For example, in order to uniformly vertically align the molecules of the discotic liquid crystal compound, it is preferable to control the alignment direction by rubbing the surface of the vertical alignment film. The rubbing treatment is performed by rubbing the surface of the polymer layer several times in a certain direction with paper or cloth. On the other hand, in order to vertically align the molecules of the rod-like liquid crystalline compound, the surface of the alignment film is preferably not rubbed. Further, in any alignment film, it is preferable to contain a molecule having a polymerizable group in the alignment film for the purpose of improving the adhesion between the optically anisotropic layer and the support made of a polymer film or the like. . The polymerizable group can be introduced by introducing a repeating unit having a polymerizable group in the side chain or as a substituent of a cyclic group. It is more preferable to use an alignment film that forms a chemical bond with the liquid crystal compound at the interface. Such an alignment film is described in JP-A-9-152509. The thickness of the alignment film is preferably 0.01 to 5 μm, and more preferably 0.05 to 1 μm. In addition, after applying a liquid crystalline composition on the surface of the alignment film and aligning the molecules of the liquid crystalline compound, the alignment state is maintained and the molecules of the liquid crystalline compound are fixed to form an optically anisotropic layer. Only the optically anisotropic layer may be transferred onto a support made of a polymer film or the like.

[Air interface alignment agent]
Since ordinary liquid crystalline compounds have the property of being tilted and aligned on the air interface side, it is necessary to control the alignment of the liquid crystal compound vertically also on the air interface side in order to obtain a uniformly vertically aligned state. . For this purpose, a compound that is unevenly distributed on the air interface side and has an action of vertically aligning the liquid crystalline compound by the excluded volume effect or the electrostatic effect is added to the liquid crystal coating liquid. The action of vertically aligning the liquid crystal compound corresponds to the action of reducing the tilt angle of the director, that is, the angle formed between the director and the coated liquid crystal air side surface in the discotic liquid crystal compound. Compounds that reduce the angle of inclination of the director of discotic liquid crystalline molecules include those with multiple F atoms bonded to the air interface as shown below, and those with a sulfonyl group or carboxyl group bonded. In addition, a compound in which a rigid structural unit that gives an excluded volume effect such that the liquid crystal molecules are aligned perpendicularly is bonded preferably.

  In addition to the exemplified compounds, compounds described in JP-A Nos. 2002-20363 and 2002-129162 can be used as the air interface alignment agent. Also, paragraph numbers [0072] to [0075] in the specification of Japanese Patent Application Laid-Open No. 2004-53981 (the specification of Japanese Patent Application No. 2002-212100), and paragraph numbers [0038] to [0040] of the specification of the Japanese Patent Application No. 2002-243600. ] And [0048] to [0049, paragraph numbers [0037] to [0039] of Japanese Patent Application No. 2002-262239, paragraphs of Japanese Patent Application Laid-Open No. 2004-4688 (Japanese Patent Application No. 2003-91752) The matters described in the numbers [0071] to [0078] can also be appropriately applied to the present invention.

  The amount of the air interface alignment agent used in the liquid crystal coating solution is preferably 0.05% by weight to 5% by weight. Moreover, when using a fluorine saturation type | system | group air interface aligning agent, it is preferable that it is 1 weight% or less.

The optically anisotropic layer used in the present invention may be composed of a stretched birefringent polymer film. The polymer film used as the optically anisotropic layer may be a stretched polymer film or a combination of a coating-type polymer layer and a polymer film. As a material for the polymer film, a synthetic polymer (eg, polycarbonate, polysulfone, polyethersulfone, polyacrylate, polymethacrylate, norbornene resin, triacetylcellulose) is generally used. These polymer films preferably have the same longitudinal direction (roll TO roll) in order to improve productivity and shape stability when temperature and humidity change.
In addition, as described above, the optically anisotropic layer may be a cellulose acylate film containing a component that develops or increases retardation in order to satisfy desired optical characteristics.

The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. However, Example 1 is a reference example.

[Example 1]
<Fabrication of FFS mode liquid crystal cell>
An FFS mode liquid crystal display device having the same configuration as that shown in FIG. 1 was produced.
Specifically, the common electrode ITO (18) was formed on the surface of the glass substrate (16), and an inorganic insulating film (20) such as SIN was formed thereon by vacuum film formation by sputtering or the like. A pixel electrode (22) (line width 5 μm, electrode gap 5 μm) provided with slits was formed thereon. Further, a polyimide film was provided thereon as an alignment film (not shown in FIG. 1), and a rubbing process was performed. A polyimide film (not shown in FIG. 1) was provided on one surface of a separately prepared glass substrate (26), and a rubbing treatment was performed to obtain an alignment film. Two glass substrates (16, 26) are stacked so that the alignment films face each other, the distance between the substrates (gap; d) is 4.1 μm, and the rubbing directions of the two glass substrates are parallel to each other. Then, a nematic liquid crystal composition having a refractive index anisotropy (Δn) of 0.098 and a dielectric anisotropy (Δε) of 4.5 was sealed, and a liquid crystal layer 24 was formed. The value of d · Δn of the liquid crystal layer 24 was 400 nm.

<Preparation of Cellulose Acylate Film R1>
(Preparation of cellulose acetate solution)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acetate solution D.
Cellulose acetate solution D composition Cellulose acetate having an acetylation degree of 2.86 100.0 parts by mass Methylene chloride (first solvent) 402.0 parts by mass Methanol (second solvent) 60.0 parts by mass

(Preparation of matting agent solution)
20 parts by mass of silica particles having an average particle size of 16 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) and 80 parts by mass of methanol were sufficiently stirred for 30 minutes to obtain a silica particle dispersion. This dispersion was put into a disperser together with the following composition, and further stirred for 30 minutes or more to dissolve each component to prepare a matting agent solution.
Matting agent solution composition Silica particle dispersion with an average particle size of 16 nm 10.0 parts by weight Methylene chloride (first solvent) 76.3 parts by weight Methanol (second solvent) 3.4 parts by weight Cellulose acetate solution D 10.3 parts by weight

(Preparation of additive solution)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution. The compound was used for the compound (optical anisotropy reducing agent) and the wavelength dispersion adjusting agent that reduce the optical anisotropy.
Additive solution composition Compound that lowers optical anisotropy 49.3 parts by weight Wavelength dispersion adjusting agent 7.6 parts by weight Methylene chloride (first solvent) 58.4 parts by weight Methanol (second solvent) 8.7 parts by weight Cellulose Acetate solution D 12.8 parts by mass

(Production of cellulose acetate film (low letter-day protection film R1))
94.6 parts by mass of the cellulose acetate solution D, 1.3 parts by mass of the matting agent solution, and 4.1 parts by mass of the additive solution were mixed after filtration, and cast using a band casting machine. The mass ratio of the compound for reducing optical anisotropy and the wavelength dispersion adjusting agent to cellulose acetate in the above composition was 12% and 1.8%, respectively. The film was peeled from the band with a residual solvent amount of 30% and dried at 140 ° C. for 40 minutes to produce a cellulose acetate film R1. The obtained cellulose acetate film had a residual solvent amount of 0.2% and a film thickness of 40 μm. Further, when the optical properties of the cellulose acylate film R1 were measured, Re was 0.5 nm and Rth was 0.2 nm at a wavelength of 550 nm, and the above formula (I) was satisfied.

<Preparation of polarizing plate>
The polarizing plate was prepared by using an acrylic adhesive so that the slow axis of the protective film and the absorption axis of the polarizing film were adhered to both sides of the polarizing film in parallel. Specifically, a Fuji TAC (TD80U) protective film (Re = 5 nm, Rth = 40 nm) is provided on the liquid crystal cell side on the surface that becomes the light source side (or display surface) of the polarizing film using an acrylic adhesive. The low retardation cellulose acylate film R1 (Re = 0.5 nm, Rth = 0.2 nm) prepared above was laminated on the surface.

<Fabrication of FFS mode liquid crystal display device>
As the polarizing plates P1 and P2 in FIG. The protective films 14 and 28 arranged on the liquid crystal cell LC side are the cellulose acylate film R1, and the polarizing plate protective films 10 and 32 outside the polarizing film are Fuji TAC (TD80U) protective films (Re = 5 nm, Rth = 40 nm). At this time, the absorption axis of the polarizing film 12 on the light source side and the orientation direction of the liquid crystal layer 24 (that is, the rubbing axis formed on the opposing surfaces of the substrates 16 and 26) are parallel to each other, and the polarizing film on the light source side The 12 absorption axes and the absorption axis of the polarizing film 30 on the display surface side were arranged in an orthogonal direction.

<Evaluation>
With respect to the manufactured liquid crystal display device, when the contrast ratio in the direction of 70 ° from the normal direction was measured at 45 ° in the azimuth direction with respect to the orthogonal absorption axes of the polarizing plates P1 and P2, the contrast ratio was 10. In addition, even if the viewing direction is changed from the normal direction to the tilt direction with respect to the display surface, the color change of the display surface is not recognized at all, the chromaticity does not depend on the viewing angle, and the color is not colored in any direction. It was found that no image was obtained.
For comparison, the polarizing plates P1 and P2 were evaluated in the same manner using commercially available polarizing plates. As a result, the same contrast characteristics as in Example 1 were obtained. It was found that the color change when changing the viewing direction was very large, the chromaticity was highly dependent on the viewing angle, and the display quality was poor.
From the above results, the liquid crystal display device of Example 1 has a negative dielectric anisotropy nematic liquid crystal in which the color change of the image depending on the viewing angle is reduced as compared with the conventional liquid crystal display device. Since the material is used, it was found that the liquid crystal display device can display images with high contrast and has excellent display quality.

[Example 2]
An FFS mode liquid crystal display device having the configuration of the first example shown in FIG. 5 was produced. Specifically, a liquid crystal display device having the same configuration as in Example 1 was produced except that the polarizing plate P2 used in Example 1 was replaced with a polarizing plate P2 ′. As the polarizing plate P2 ′, the protective film 28 disposed on the liquid crystal cell side of the polarizing plate P2 has a Re at a wavelength of 550 nm of 137 nm and an Rth at a wavelength of 550 nm of 70 nm from the polarizing film 30 side. Protective film 28 'made of a cellulose acylate film satisfying formula (III), Re at a wavelength of 550 nm is 1 nm, and Rth at a wavelength of 550 nm is -85 nm, that is, the following formula (II) is satisfied A polarizing plate having the same configuration as that of the polarizing plate P2 was used except that the laminated body of the optically anisotropic layer 27 made of a cellulose acylate film was used.
(II) −135 nm ≦ Rth ≦ −35 nm and 0 nm ≦ Re ≦ 10 nm
(III) 117 nm ≦ Re ≦ 157.5 nm and 58.5 nm ≦ Rth ≦ 78.8 nm
The slow axis of the protective film 28 'is an orientation orthogonal to the absorption axis of the polarizing film 30 and parallel to the orientation control direction (rubbing axis) formed on the opposing surfaces of the substrates 16 and 26, and is optically anisotropic. The slow axis of the conductive layer 27 was parallel to the orientation of the slow axis of the protective film 28 '.
The produced liquid crystal display device was evaluated in the same manner as in Example 1. Specifically, the contrast ratio was 500 when the contrast ratio in the direction of inclination of 70 ° from the normal direction was measured at 45 ° in the azimuth direction with respect to the orthogonal absorption axes of the polarizing plates P1 and P2 ′. Further, even when the viewing direction was changed from the normal direction to the tilt direction of the display surface, the color change of the display surface was not recognized at all, and black display was realized in all directions.
The cellulose acylate film used as the protective film 28 ′ of the polarizing plate P2 ′ and the optically anisotropic layer 27 is a stretched film prepared by uniaxially or biaxially stretching a cellulose acetate film to which a retardation-expressing component is added. It was.

[Example 3]
The FFS mode liquid crystal display device of the ninth example shown in FIG. 6 was produced. Specifically, a liquid crystal display device having the same configuration as in Example 1 and Example 1 was produced except that the polarizing plate P1 used in Example 1 was replaced with a polarizing plate P1 ′. As the polarizing plate P1 ′, the protective film 14 disposed on the liquid crystal cell side of the polarizing plate P1 has, from the polarizing film 12 side, Re at a wavelength of 550 nm is 0.5 nm and Rth at a wavelength of 550 nm is −85 nm. That is, the protective film 14 ′ made of a cellulose acylate film satisfying the above formula (II), Re at a wavelength of 550 nm is 138 nm, and Rth at a wavelength of 550 nm is 68 nm, that is, the above formula (III) is satisfied. A polarizing plate having the same configuration as that of the polarizing plate P1 was used except that the laminated body of the optically anisotropic layer 15 made of a cellulose acylate film was used. In addition, the alignment direction of the liquid crystal molecules in the liquid crystal layer 24 ′ (the liquid crystal molecule long axis coincides with the rubbing axis direction formed on the opposing surfaces of the substrates 16 and 26), the absorption axis of the light source side polarizing plate P1 ′, The slow axis of the optically anisotropic layer 15 and the slow axis of the protective film 14 ′ are arranged in an orthogonal direction.
When evaluated in the same manner as in Example 1, it was found that display characteristics similar to those of the liquid crystal display device of Example 2 were obtained.

[Example 4]
An FFS mode liquid crystal display device having the configuration of the second example shown in FIG. 5 was produced. Specifically, a liquid crystal display device having the same configuration as in Example 1 was produced except that the polarizing plate P2 used in Example 1 was replaced with a polarizing plate P2 ′. As the polarizing plate P2 ′, the protective film 28 disposed on the liquid crystal cell side of the polarizing plate P2 has, from the polarizing film 30 side, Re at a wavelength of 550 nm is 132 nm, and Rth at a wavelength of 550 nm is 70 nm. Protective film 28 'made of a cellulose acylate film satisfying (III), Re at wavelength 550nm is 2nm, and Rth at wavelength 550nm is -80nm, that is, cellulose satisfying the above formula (II) A polarizing plate having the same structure as the polarizing plate P2 was used except that the laminated body of the optically anisotropic layer 27 made of an acylate film was used.
The slow axis of the optically anisotropic layer 27 is oriented in the direction parallel to the absorption axis of the polarizing film 30 and perpendicular to the orientation control direction (rubbing axis) formed on the opposing surfaces of the substrates 16 and 26. The slow axis of the film 28 ′ was parallel to the orientation of the slow axis of the optically anisotropic layer 27.
When evaluated in the same manner as in Example 1, it was found that display characteristics similar to those of the liquid crystal display device of Example 2 were obtained.

[Example 5]
An FFS mode liquid crystal display device having the configuration of the tenth example shown in FIG. 6 was produced. Specifically, a liquid crystal display device having the same configuration as in Example 1 and Example 1 was produced except that the polarizing plate P1 used in Example 1 was replaced with a polarizing plate P1 ′. As the polarizing plate P1 ′, the protective film 14 disposed on the liquid crystal cell side of the polarizing plate P1 is, from the polarizing film 12 side, Re at a wavelength of 550 nm is 140 nm, and Rth at a wavelength of 550 nm is 67.
a protective film 14 ′ made of a cellulose acylate film that satisfies the above formula (III), and Re at a wavelength of 550 nm is 0.5 nm, and Rth at a wavelength of 550 nm is −85 nm. A polarizing plate having the same configuration as that of the polarizing plate P1 was used except that the laminated body of the optically anisotropic layer 15 made of a cellulose acylate film satisfying the formula (II) was used. In addition, the alignment direction of the liquid crystal molecules in the liquid crystal layer 24 ′ (the liquid crystal molecule long axis coincides with the rubbing axis direction formed on the opposing surfaces of the substrates 16 and 26) and the absorption axis of the light source side polarizing plate P1 ′. They were arranged in a direction orthogonal to each other and parallel to the slow axis of the optically anisotropic layer 15 and the slow axis of the protective film 14 '.
When evaluated in the same manner as in Example 1, it was found that display characteristics similar to those of the liquid crystal display device of Example 2 were obtained.

[Example 6]
An FFS mode liquid crystal display device having the configuration of the third example shown in FIG. 5 was produced. Specifically, a liquid crystal display device having the same configuration as in Example 1 was produced except that the polarizing plate P2 used in Example 1 was replaced with a polarizing plate P2 ′. As the polarizing plate P2 ′, the protective film 28 disposed on the liquid crystal cell side of the polarizing plate P2 has a Re at a wavelength of 550 nm of 135 nm and an Rth of −68 nm at a wavelength of 550 nm from the polarizing film 30 side. Protective film 28 'made of a cellulose acylate film satisfying formula (V), and Re at a wavelength of 550 nm is 5 nm and Rth at a wavelength of 550 nm is 80 nm, that is, cellulose satisfying the following formula (IV) A polarizing plate having the same structure as the polarizing plate P2 was used except that the laminated body of the optically anisotropic layer 27 made of an acylate film was used.
(IV) 35 nm ≦ Rth ≦ 135 nm and 0 nm ≦ Re ≦ 10 nm
(V) 117 nm ≦ Re ≦ 157.5 nm and −78.8 nm ≦ Rth ≦ −58.5 nm
The slow axis of the protective film 28 ′ is an orientation parallel to the absorption axis of the polarizing film 30 and perpendicular to the orientation control direction (rubbing axis) formed on the opposing surfaces of the substrates 16 and 26. The slow axis of the conductive layer 27 was parallel to the orientation of the slow axis of the protective film 28 '.
The manufactured liquid crystal display device was evaluated in the same manner as in Example 1. Specifically, the contrast ratio was 500 when the contrast ratio in the direction of inclination of 70 ° from the normal direction was measured at 45 ° in the azimuth direction with respect to the orthogonal absorption axes of the polarizing plates P1 and P2 ′. In addition, even when the viewing direction was changed from the normal direction of the display surface to the tilt direction, the color change of the display surface was not recognized at all, and black display was realized in all directions.
The cellulose acylate film used as the protective film 28 ′ of the polarizing plate P2 ′ and the optically anisotropic layer 27 is a stretched film prepared by uniaxially or biaxially stretching a cellulose acetate film to which a retardation-expressing component is added. It was.

[Example 7]
An FFS mode liquid crystal display device having the configuration of the eleventh example shown in FIG. 6 was produced. Specifically, a liquid crystal display device having the same configuration as in Example 1 and Example 1 was produced except that the polarizing plate P1 used in Example 1 was replaced with a polarizing plate P1 ′. As the polarizing plate P1 ′, the protective film 14 disposed on the liquid crystal cell side of the polarizing plate P1 has, from the polarizing film 12 side, Re at a wavelength of 550 nm is 0 nm and Rth at a wavelength of 550 nm is 90 nm. A protective film 14 ′ made of a cellulose acylate film satisfying (IV), and Re at a wavelength of 550 nm of 140 nm and Rth at a wavelength of 550 nm of 68 nm, that is, a cellulose acylate satisfying the above formula (V) A polarizing plate having the same configuration as that of the polarizing plate P1 was used except that the laminated body of the optically anisotropic layer 15 made of a rate film was used. Further, the alignment direction of the liquid crystal molecules in the liquid crystal layer 24 ′ (the liquid crystal molecule long axis coincides with the rubbing axis direction formed on the opposing surfaces of the substrates 16 and 26) and the slow axis of the optically anisotropic layer 15 are: It arrange | positioned in the direction orthogonal to the absorption axis of polarizing plate P1 'of the light source side.
When evaluated in the same manner as in Example 1, it was found that display characteristics similar to those of the liquid crystal display device of Example 6 were obtained.

[Example 8]
An FFS mode liquid crystal display device having the configuration of the fourth example shown in FIG. 5 was produced. Specifically, a liquid crystal display device having the same configuration as in Example 1 was produced except that the polarizing plate P2 used in Example 1 was replaced with a polarizing plate P2 ′. As the polarizing plate P2 ′, the protective film 28 disposed on the liquid crystal cell side of the polarizing plate P2 has a Re at a wavelength of 550 nm of 0.5 nm and an Rth at a wavelength of 550 nm of 87 nm from the polarizing film 30 side. Protective film 28 ′ made of a cellulose acylate film that satisfies the above formula (IV), Re at a wavelength of 550 nm is 134 nm, and Rth at a wavelength of 550 nm is −67 nm, that is, the above formula (V) is satisfied. A polarizing plate having the same configuration as that of the polarizing plate P2 was used except that the laminated body of the optically anisotropic layer 27 made of a cellulose acylate film was used.
The slow axis of the optically anisotropic layer 27 is oriented in the direction orthogonal to the absorption axis of the polarizing film 30 and parallel to the orientation control direction (rubbing axis) formed on the opposing surfaces of the substrates 16 and 26, and is protected. The slow axis of the film 28 ′ was parallel to the orientation of the slow axis of the optically anisotropic layer 27.
When evaluated in the same manner as in Example 1, it was found that display characteristics similar to those of the liquid crystal display device of Example 6 were obtained.

[Example 9]
The FFS mode liquid crystal display device of the twelfth example shown in FIG. 6 was produced. Specifically, a liquid crystal display device having the same configuration as in Example 1 and Example 1 was produced except that the polarizing plate P1 used in Example 1 was replaced with a polarizing plate P1 ′. As the polarizing plate P1 ′, the protective film 14 disposed on the liquid crystal cell side of the polarizing plate P1 has, from the polarizing film 12 side, Re at a wavelength of 550 nm is 133 nm, and Rth at a wavelength of 550 nm is −68 nm. Protective film 14 ′ made of a cellulose acylate film satisfying the formula (V), and Re at a wavelength of 550 nm is 5 nm and Rth at a wavelength of 550 nm is 80 nm, that is, cellulose satisfying the above formula (IV) A polarizing plate having the same configuration as that of the polarizing plate P1 was used except that the laminated body of the optically anisotropic layer 15 made of an acylate film was used. In addition, the alignment direction of the liquid crystal molecules in the liquid crystal layer 24 ′ (the liquid crystal molecule long axis coincides with the rubbing axis direction formed on the opposing surfaces of the substrates 16 and 26) and the slow axis of the optically anisotropic layer 15 are mutually They were arranged in parallel orientations, and they were placed in an orientation perpendicular to the slow axis of the protective film 14 'and the absorption axis of the polarizing plate P1' on the light source side.
When evaluated in the same manner as in Example 1, it was found that display characteristics similar to those of the liquid crystal display device of Example 6 were obtained.

[Example 10]
As the polarizing plate P2, instead of the cellulose acylate film R1, a cellulose acylate film in which Re at a wavelength of 550 nm is 270 nm and Rth at a wavelength of 550 nm is 0.5 nm, that is, the following formula (VI) is satisfied. An FFS mode liquid crystal display device having the same configuration as that of Example 1 shown in FIG. 1 was prepared except that the polarizing plate P2 disposed as the protective film 28 was used.
(VI) 252.5 nm ≦ Re ≦ 292.5 nm and | Rth | ≦ 25 nm
The absorption axis of the polarizing film 12 of the light source side polarizing plate P1 and the alignment direction of the liquid crystal in the liquid crystal layer 24 (corresponding to the alignment control direction (rubbing axis) formed on the opposing surfaces of the substrates 16 and 26) are made parallel. Arranged.
The produced liquid crystal display device was evaluated in the same manner as in Example 1. Specifically, when the contrast ratio in the direction of the inclination of 70 ° from the normal direction in the azimuth direction 45 ° with respect to the orthogonal absorption axes of the polarizing plates P1 and P2 was measured, the contrast ratio was 800. In addition, when the viewing direction was changed from the normal direction to the tilt direction on the display surface, the color change on the display surface was not recognized at all, and black display was realized in all directions.
The cellulose acylate film used as the protective film 28 of the polarizing plate P2 was a stretched film produced by uniaxially stretching or biaxially stretching a cellulose acetate film to which a retardation developing component was added.

[Example 11]
As the polarizing plate P1, in place of the cellulose acylate film R1, a cellulose acylate film having a Re of 277 nm at a wavelength of 550 nm and an Rth of 0 nm at a wavelength of 550 nm, ie, satisfying the above formula (VI) is protected. An FFS mode liquid crystal display device having the same configuration as that of Example 1 shown in FIG. However, the alignment direction of the absorption axis of the polarizing film 12 of the polarizing plate P1 and the long axis of the liquid crystal molecule in the liquid crystal layer (corresponds to the orientation of the alignment control direction (rubbing axis) formed on the opposing surfaces of the substrates 16 and 26). Were arranged in an orthogonal orientation. In addition, the slow axis of the protective film 14 was arranged to coincide with the direction of the absorption axis of the polarizing film 12 of the polarizing plate P1.
When the manufactured liquid crystal display device was evaluated in the same manner as in Example 1, it was found that the same display characteristics as those of the liquid crystal display device in Example 10 were obtained.

[Example 12]
An FFS mode liquid crystal display device having the configuration of the fifth example shown in FIG. 5 was produced. Specifically, a liquid crystal display device having the same configuration as in Example 1 was produced except that the polarizing plate P2 used in Example 1 was replaced with a polarizing plate P2 ′. As the polarizing plate P2 ′, the protective film 28 disposed on the liquid crystal cell side of the polarizing plate P2 has, from the polarizing film 30 side, Re at a wavelength of 550 nm is 278 nm and Rth at a wavelength of 550 nm is −68 nm. Protective film 28 ′ made of a cellulose acylate film satisfying formula (VII), and Re at a wavelength of 550 nm of 278 nm and Rth at a wavelength of 550 nm of 68 nm, that is, cellulose satisfying the following formula (VIII) A polarizing plate having the same structure as the polarizing plate P2 was used except that the laminated body of the optically anisotropic layer 27 made of an acylate film was used.
(VII) 252.5 nm ≦ Re ≦ 292.5 nm and −118.1 nm ≦ Rth ≦ −18.1 nm
(VIII) 252.5 nm ≦ Re ≦ 292.5 nm and 18.1 nm ≦ Rth ≦ 118.1 nm
The slow axis of the protective film 28 ′ and the slow axis of the optically anisotropic layer 27 are oriented in the direction perpendicular to the absorption axis of the polarizing film 30 and the orientation control direction (rubbing) formed on the opposing surfaces of the substrates 16 and 26. The slow axis of the optically anisotropic layer 27 is parallel to the slow axis direction of the protective film 28 '.
The produced liquid crystal display device was evaluated in the same manner as in Example 1. Specifically, when the contrast ratio in the direction of inclination of 70 ° from the normal direction in the azimuth direction 45 ° with respect to the orthogonal absorption axes of the polarizing plates P1 and P2 ′ was measured, the contrast ratio was 1000. In addition, when the viewing direction was changed from the normal direction to the tilt direction on the display surface, the color change on the display surface was not recognized at all, and black display was realized in all directions.
The cellulose acylate film used as the protective film 28 ′ of the polarizing plate P2 ′ and the optically anisotropic layer 27 is a stretched film prepared by uniaxially stretching or biaxially stretching a cellulose acetate film to which a retardation developing component is added. there were.

[Example 13]
An FFS mode liquid crystal display device having the configuration of the thirteenth example shown in FIG. 6 was produced. Specifically, a liquid crystal display device having the same configuration as in Example 1 and Example 1 was produced except that the polarizing plate P1 used in Example 1 was replaced with a polarizing plate P1 ′. As the polarizing plate P1 ′, the protective film 14 disposed on the liquid crystal cell side of the polarizing plate P1 has, from the polarizing film 12 side, Re at a wavelength of 550 nm is 275 nm and Rth at a wavelength of 550 nm is 70 nm. Protective film 14 'made of a cellulose acylate film satisfying (VIII), and Re at a wavelength of 550 nm is 278 nm and Rth at a wavelength of 550 nm is -70 nm, that is, cellulose satisfying the above formula (VII) A polarizing plate having the same configuration as that of the polarizing plate P1 was used except that the laminated body of the optically anisotropic layer 15 made of an acylate film was used. In addition, the orientation direction of the liquid crystal molecules in the liquid crystal layer 24 ′ (the liquid crystal molecule major axis coincides with the rubbing axis orientation formed on the opposing surfaces of the substrates 16 and 26) is the slow axis of the optically anisotropic layer 15, It arrange | positioned in the azimuth | direction orthogonal to the slow axis of protective film 14 ', and the absorption axis of polarizing plate P1' of the light source side.
When evaluated in the same manner as in Example 1, it was found that display characteristics similar to those of the liquid crystal display device of Example 12 were obtained.

[Example 14]
An FFS mode liquid crystal display device having the configuration of the sixth example shown in FIG. 5 was produced. Specifically, a liquid crystal display device having the same configuration as in Example 1 was produced except that the polarizing plate P2 used in Example 1 was replaced with a polarizing plate P2 ′. As the polarizing plate P2 ′, the protective film 28 disposed on the liquid crystal cell side of the polarizing plate P2 has, from the polarizing film 30 side, Re at a wavelength of 550 nm is 280 nm, and Rth at a wavelength of 550 nm is 68 nm. Protective film 28 'made of a cellulose acylate film satisfying (VIII), and Re at a wavelength of 550 nm is 275 nm and Rth at a wavelength of 550 nm is -70 nm, that is, cellulose satisfying the above formula (VII) A polarizing plate having the same structure as the polarizing plate P2 was used except that the laminated body of the optically anisotropic layer 27 made of an acylate film was used.
The slow axis of the optically anisotropic layer 27 and the slow axis of the protective film 28 ′ are oriented in parallel to the absorption axis of the polarizing film 30 and the orientation control direction (rubbing) formed on the opposing surfaces of the substrates 16 and 26. The direction was orthogonal to the axis.
When evaluated in the same manner as in Example 1, it was found that display characteristics similar to those of the liquid crystal display device of Example 12 were obtained.

[Example 15]
The FFS mode liquid crystal display device having the configuration of the fourteenth example shown in FIG. 6 was produced. Specifically, a liquid crystal display device having the same configuration as in Example 1 and Example 1 was produced except that the polarizing plate P1 used in Example 1 was replaced with a polarizing plate P1 ′. As the polarizing plate P1 ′, the protective film 14 disposed on the liquid crystal cell side of the polarizing plate P1 has, from the polarizing film 12 side, Re at a wavelength of 550 nm is 275 nm, and Rth at a wavelength of 550 nm is −68 nm. Protective film 14 'made of a cellulose acylate film that satisfies formula (VII), and Re at a wavelength of 550 nm is 275 nm and Rth at a wavelength of 550 nm is 70 nm, that is, cellulose that satisfies the above formula (VIII) A polarizing plate having the same configuration as that of the polarizing plate P1 was used except that the laminated body of the optically anisotropic layer 15 made of an acylate film was used. Further, the alignment direction of the liquid crystal molecules in the liquid crystal layer 24 ′ (the liquid crystal molecule long axis coincides with the rubbing axis direction formed on the opposing surfaces of the substrates 16 and 26) is the slow axis of the optically anisotropic layer 15 and The orientation was parallel to the slow axis of the protective film 14 'and the orientation was perpendicular to the absorption axis of the light source side polarizing plate P1'.
When evaluated in the same manner as in Example 1, it was found that display characteristics similar to those of the liquid crystal display device of Example 12 were obtained.

[Example 16]
The FFS mode liquid crystal display device having the configuration of the seventh example shown in FIG. 5 was produced. Specifically, a liquid crystal display device having the same configuration as in Example 1 was produced except that the polarizing plate P2 used in Example 1 was replaced with a polarizing plate P2 ′. As the polarizing plate P2 ′, the protective film 28 disposed on the liquid crystal cell side of the polarizing plate P2 has an Re of 278 nm at a wavelength of 550 nm and an Rth of 70 nm at a wavelength of 550 nm, that is, the above formula (VIII) is satisfied. A polarizing plate having the same configuration as that of the polarizing plate P2 was used except that the cellulose acylate film was replaced with two laminates (corresponding to the protective film 28 ′ and the optically anisotropic layer 27 in FIG. 5). .
The two cellulose acylate films were laminated with their slow axes orthogonal to each other. In addition, the slow axis of the cellulose acylate film disposed at the position of the protective film 28 ′ is an orientation parallel to the absorption axis of the polarizing film 30 and the orientation control direction formed on the opposing surfaces of the substrates 16 and 26 ( The orientation was orthogonal to the rubbing axis.
The produced liquid crystal display device was evaluated in the same manner as in Example 1. Specifically, when the contrast ratio in the direction of inclination of 70 ° from the normal direction in the azimuth direction 45 ° with respect to the orthogonal absorption axes of the polarizing plates P1 and P2 ′ was measured, the contrast ratio was 1000. In addition, when the viewing direction was changed from the normal direction to the tilt direction on the display surface, the color change on the display surface was not recognized at all, and black display was realized in all directions.

[Example 17]
An FFS mode liquid crystal display device having the configuration of the fifteenth example shown in FIG. 6 was produced. Specifically, a liquid crystal display device having the same configuration as in Example 1 and Example 1 was produced except that the polarizing plate P1 used in Example 1 was replaced with a polarizing plate P1 ′. As the polarizing plate P1 ′, the protective film 14 disposed on the liquid crystal cell side of the polarizing plate P1 has an Re Re of 280 at a wavelength of 550 nm.
2 and Rth at a wavelength of 550 nm of 65 nm, ie, satisfying the above formula (VIII), a laminate of two cellulose acylate films (in FIG. 6, protective film 14 ′ and optically anisotropic layer 15 A polarizing plate having the same configuration as that of the polarizing plate P1 was used except that the polarizing plate P1 was replaced.
The two cellulose acylate films were laminated with their slow axes orthogonal to each other. In addition, the slow axis of the cellulose acylate film disposed at the position of the protective film 14 ′ is an orientation parallel to the absorption axis of the polarizing film 12 and the orientation control direction formed on the opposing surfaces of the substrates 16 and 26 ( The orientation was orthogonal to the rubbing axis.
When evaluated in the same manner as in Example 1, it was found that display characteristics similar to those of the liquid crystal display device of Example 16 were obtained.

[Example 18]
An FFS mode liquid crystal display device having the configuration of the eighth example shown in FIG. 5 was produced. Specifically, a liquid crystal display device having the same configuration as in Example 1 was produced except that the polarizing plate P2 used in Example 1 was replaced with a polarizing plate P2 ′. As the polarizing plate P2 ′, the protective film 28 disposed on the liquid crystal cell side of the polarizing plate P2 has an Re of 275 nm at a wavelength of 550 nm and an Rth of 70 nm at a wavelength of 550 nm, that is, the above formula (VII) is satisfied. A polarizing plate having the same configuration as that of the polarizing plate P2 was used except that the cellulose acylate film was replaced with two laminates (corresponding to the protective film 28 ′ and the optically anisotropic layer 27 in FIG. 5). .
The two cellulose acylate films were laminated with their slow axes orthogonal to each other. In addition, the slow axis of the cellulose acylate film disposed at the position of the protective film 28 ′ is an orientation orthogonal to the absorption axis of the polarizing film 30 and an orientation control direction (which is formed on the opposing surfaces of the substrates 16 and 26). The orientation was parallel to the rubbing axis.
The produced liquid crystal display device was evaluated in the same manner as in Example 1. Specifically, when the contrast ratio in the direction with an inclination of 70 ° from the normal direction in the azimuth direction 45 ° with respect to the orthogonal absorption optical axes of the polarizing plates P1 and P2 ′ was measured, the contrast ratio was 1000. In addition, when the viewing direction was changed from the normal direction to the tilt direction on the display surface, the color change on the display surface was not recognized at all, and black display was realized in all directions.

[Example 19]
An FFS mode liquid crystal display device having the configuration of the sixteenth example shown in FIG. 6 was produced. Specifically, a liquid crystal display device having the same configuration as in Example 1 and Example 1 was produced except that the polarizing plate P1 used in Example 1 was replaced with a polarizing plate P1 ′. As the polarizing plate P1 ′, the protective film 14 disposed on the liquid crystal cell side of the polarizing plate P1 has an Re of 280 nm at a wavelength of 550 nm and an Rth of 65 nm at a wavelength of 550 nm, that is, the above formula (VII) is satisfied. A polarizing plate having the same configuration as that of the polarizing plate P1 was used except that the cellulose acylate film was replaced with two laminates (corresponding to the protective film 14 ′ and the optically anisotropic layer 15 in FIG. 6). .
The two cellulose acylate films were laminated with their slow axes orthogonal to each other. In addition, the slow axis of the cellulose acylate film disposed at the position of the protective film 14 ′ is an orientation perpendicular to the absorption axis of the polarizing film 12 and the orientation control direction (which is formed on the opposing surfaces of the substrates 16 and 26). The orientation was parallel to the rubbing axis.
When evaluated in the same manner as in Example 1, it was found that display characteristics similar to those of the liquid crystal display device of Example 18 were obtained.

  In Examples 1 to 18 described above, the effect of an example of a cellulose acylate film satisfying each formula was demonstrated. However, the protective film, the optically anisotropic layer, the orientation direction of the liquid crystalline molecules in the liquid crystal layer, and the polarization It was confirmed that the same effects as in the respective examples were obtained if the arrangement of axes such as the absorption axis of the film was the same as in the above examples, and Re and Rth satisfied the optical characteristics within the ranges of the respective formulas.

  According to the present invention, the viewing angle characteristics are improved by using cellulose acylate exhibiting predetermined optical characteristics (for example, as a protective film of a polarizing plate), and particularly the color change of an image depending on the viewing angle. It is possible to provide an FFS mode liquid crystal display device in which the above is reduced. Furthermore, according to the aspect having a liquid crystal layer made of a liquid crystal material having a negative dielectric anisotropy, the above-described effect, that is, the change in the color tone of the image depending on the viewing angle is reduced, and the contrast is higher than the conventional one. In addition, an improved FFS mode liquid crystal display device can be provided.

DESCRIPTION OF SYMBOLS 10 Protective film of light source side polarizing film 12 Light source side polarizing film 14 Protective film of light source side polarizing film (cellulose acylate film)
14 ′ Protective film for light source side polarizing film and fourth optical anisotropic layer 15 Third optical anisotropic layer 16, 16 ′ Liquid crystal cell substrate 18 Common electrode 20 Insulating layer 22 Pixel electrode 24, 24 ′ Liquid crystal layer 26, 26 'substrate for liquid crystal cell 27 first optically anisotropic layer 28 protective film for display surface side polarizing film (cellulose acylate film)
28 'protective film for the display surface side polarizing film and second optical anisotropic layer 30 display surface side polarizing film 32 protective film for the display surface side polarizing film P1, P1' light source side polarizing plate P2, P2 'display surface side polarizing plate LC, LC 'liquid crystal cell

Claims (3)

A pair of first and second substrates disposed opposite to each other; a pixel electrode and a common electrode formed on at least one of the pair of substrates via an insulating layer and capable of applying different potentials; A liquid crystal layer disposed between the pair of substrates, including a liquid crystal material having a negative dielectric anisotropy, and having liquid crystal molecules aligned substantially parallel to the substrate surface when no voltage is applied; and sandwiching the liquid crystal layer And a pair of first and second polarizing films disposed so that the absorption axes are orthogonal to each other, and an FFS that controls the orientation of the liquid crystal layer by an electric field formed on the pixel electrode and the common electrode. Fringe field switching) mode liquid crystal display device,
The pixel electrodes are formed in a plurality of lines, and the interval between the pixel electrodes is 2 to 10 μm.
Between the second polarizing film and the liquid crystal layer, a first optical anisotropic layer satisfying the following formula (VII) and a second optical anisotropic layer satisfying the following formula (VIII) are mutually connected: It is arranged with the in-plane slow axis orthogonal or parallel,
A cellulose acylate film satisfying the following formula (I) is provided between the first polarizing film and the first substrate disposed closer to the first polarizing film among the pair of substrates. FFS mode liquid crystal display:
(I) 0 nm ≦ Re ≦ 10 nm and | Rth | ≦ 25 nm
(VII) 252.5 nm ≦ Re ≦ 292.5 nm and −118.1 nm ≦ Rth ≦ −18.1 nm
(VIII) 252.5 nm ≦ Re ≦ 292.5 nm and 18.1 nm ≦ Rth ≦ 118.1 nm
In the above formula, Re represents the front retardation value (nm) at a wavelength of 550 nm, and Rth represents the retardation value (nm) in the film thickness direction at a wavelength of 550 nm. A pair of first and second substrates disposed opposite to each other; a pixel electrode and a common electrode formed on at least one of the pair of substrates via an insulating layer and capable of applying different potentials; A liquid crystal layer disposed between the pair of substrates, including a liquid crystal material having a negative dielectric anisotropy, and having liquid crystal molecules aligned substantially parallel to the substrate surface when no voltage is applied; and sandwiching the liquid crystal layer And a pair of first and second polarizing films disposed so that the absorption axes are orthogonal to each other, and an FFS that controls the orientation of the liquid crystal layer by an electric field formed on the pixel electrode and the common electrode. Fringe field switching) mode liquid crystal display device,
The pixel electrodes are formed in a plurality of lines, and the interval between the pixel electrodes is 2 to 10 μm.
Between the second polarizing film and the liquid crystal layer, two optically anisotropic layers satisfying the following formula (X) are arranged with their in-plane slow axes orthogonal to each other,
A cellulose acylate film satisfying the following formula (I) is provided between the first polarizing film and the first substrate disposed closer to the first polarizing film among the pair of substrates. FFS mode liquid crystal display:
(I) 0 nm ≦ Re ≦ 10 nm and | Rth | ≦ 25 nm
(X) 252.5 nm ≦ Re ≦ 292.5 nm and 18.1 nm ≦ Rth ≦ 118.1 nm
In the above formula, Re represents the front retardation value (nm) at a wavelength of 550 nm, and Rth represents the retardation value (nm) in the film thickness direction at a wavelength of 550 nm. Plane slow axis of the cellulose acylate film, the absorption axis of the first polarizing film, and the first claim intersects the at least one of the alignment control direction facing surface of the substrate has 1 or 2 A liquid crystal display device according to 1.