JP2008145732A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device of an ECB (Electrically Controlled Birefringence) mode wherein gradation inversion and a tinge at the time when white display is performed are reduced with a simple configuration. <P>SOLUTION: In the liquid crystal display having: a liquid crystal layer (18) between first and second substrates which are disposed opposite to each other and at least one of which has a transparent electrode, wherein liquid crystal molecules are aligned to be nearly parallel to substrate surfaces at ≤45° twist angle between the substrates when no voltage is applied and the liquid crystal molecules are aligned in the normal direction of the substrate surfaces when voltage is applied; first and second polarizing layers (12a, 12b) disposed sandwiching the liquid crystal layer (18) and having polarization axes orthogonal to each other; and a first retardation layer (14a, 14b) between at least one of the first and the second polarizing layers (12a, 12b) and the liquid crystal layer (18), the first retardation layer satisfies the following formula (1), wherein Rth(λ) denotes a retardation value in a thickness direction to light having λ nm wavelength. -280 nm<Rth(550)<50 nm (1). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device of, for example, an ECB mode, which is aligned substantially parallel (homogeneous alignment) to a substrate surface when no voltage is applied and is aligned substantially perpendicular (homotropic alignment) to the substrate surface when a voltage is applied The present invention relates to an optical compensation method for improving viewing angle characteristics.

  The liquid crystal display device has a liquid crystal cell and a polarizing plate. A commonly used polarizing plate is composed of a protective film and a polarizing film. The polarizing film is generally produced by dyeing and stretching a polyvinyl alcohol film with iodine, and a protective film is formed on both sides of the polarizing film. Are bonded together to produce a polarizing plate. In the transmissive liquid crystal display device, the polarizing plate is attached to both sides of the liquid crystal cell, and one or more optical compensation films may be disposed. In a reflective liquid crystal display device, usually, a reflector, a liquid crystal cell, one or more optical compensation films, and a polarizing plate are arranged in this order. The liquid crystal cell has liquid crystal molecules, two substrates for encapsulating the liquid crystal molecules, and an electrode layer for applying a voltage to the liquid crystal molecules. The liquid crystal cell realizes optical switching by controlling the birefringence depending on the alignment state of liquid crystal molecules. Typical optical modes of the liquid crystal include TN (Twisted Nematic), IPS (In-Plane Switching), OCB (Optically Compensated Bend), VA (Vertically Aligned Bounded), and ECB (ElectricallyBlend Mode). ing.

  Optical compensation films are used in various liquid crystal display devices in order to eliminate image coloring and widen the viewing angle. As the optical compensation film, a stretched birefringent polymer film has been conventionally used. Further, it has been proposed to use an optical compensation film having an optical compensation film formed of a low-molecular or high-molecular liquid crystalline molecule on a transparent support, instead of the optical compensation film made of a stretched birefringent film. Since liquid crystalline molecules have various alignment forms, the use of liquid crystalline molecules can realize optical properties that cannot be obtained with conventional stretched birefringent polymer films. Furthermore, a structure that serves as both a protective film and an optical compensation film has been proposed by adding birefringence to the protective film of the polarizing plate.

The optical properties of the optical compensation film are determined according to the optical properties of the liquid crystal cell, specifically, the display mode difference as described above. When liquid crystalline molecules are used, optical compensation films having various optical properties corresponding to various display modes of the liquid crystal cell can be produced. As an optical compensation film manufactured using liquid crystal molecules, ones corresponding to various display modes have already been proposed. For example, in a TN mode liquid crystal cell, when a voltage is applied, the liquid crystalline molecules are in an alignment state inclined to the substrate surface while eliminating the twisted structure. Therefore, the optical compensation film for the TN mode liquid crystal cell performs optical compensation in this state, and black The contrast viewing angle characteristic is improved by preventing light leakage in an oblique direction during display (see Patent Document 1). However, for example, even if an optical compensation film in which a discotic liquid crystal compound is uniformly hybrid-aligned is used, it is very difficult to completely optically compensate the liquid crystal cell without any problem. For example, in a TN mode liquid crystal cell, a gradation reversal phenomenon occurs in which the transmittance at each gradation is reversed when observed from an oblique direction. A method of limiting the tilt angle range of the liquid crystal molecules in the liquid crystal cell is known but not sufficient in order not to cause gradation inversion (see Non-Patent Document 1).
On the other hand, a liquid crystal display device in ECB mode is a method in which the birefringence of a liquid crystal cell is controlled by an electric field. As an example, liquid crystal molecules are aligned substantially parallel to the substrate surface when no voltage is applied, that is, during white display. There is a method in which (homogeneous alignment) is performed, and liquid crystal molecules are aligned substantially perpendicularly to the substrate surface (homotropic alignment) when a voltage is applied, that is, in black display. In this method, it is desired to improve gradation inversion and color change (yellowing) that occur when viewing with a wide viewing angle during white display.

JP-A-6-214116 TECHNICAL REPORT OF IEICE. EID2001-108 P47-52

  The present invention has been made in view of the above-mentioned problems, and is a liquid crystal capable of displaying a high-quality image with a simple configuration and reduced gradation inversion and tinting (yellowing) that occur during white display. It is an object of the present invention to provide a display device, in particular, a parallel alignment type homogeneous ECB type liquid crystal display device in which a liquid crystal layer does not have a twisted structure.

Means for solving the above-mentioned problems are as follows.
[1] First and second substrates that are arranged to face each other and at least one of them has a transparent electrode; liquid crystal molecules are twisted between the first and second substrates without applying a voltage between the substrates. A liquid crystal layer having an angle of 45 ° or less and oriented substantially parallel to the substrate surface, and in which a liquid crystal molecule is oriented in a normal direction of the substrate surface when a voltage is applied; and polarized light that is disposed across the liquid crystal layer and orthogonal to each other A first and second polarizing layer having an axis; and a first retardation layer between at least one of the first and second polarizing layers and the liquid crystal layer, The first retardation layer satisfies the following formula (1):
−280 nm <Rth (550) <50 nm (1)
However, Rth (λ) is retardation in the thickness direction with respect to light having a wavelength of λ nm.
[2] The liquid crystal display device according to [1], wherein the first retardation layer satisfies the following formula (2):
−200 nm ≦ Rth (550) ≦ 0 nm (2).
[3] The first retardation layer is disposed between the first polarizing layer and the liquid crystal layer, and serves as a protective layer for the first polarizing layer. 2] Liquid crystal display device.
[4] A second retardation layer formed of a composition containing a compound having a discotic structural unit is further provided between at least one of the first and second polarizing layers and the liquid crystal layer. The liquid crystal display device according to any one of [1] to [3].
[5] The second retardation layer is disposed between the first retardation layer and the liquid crystal layer, and the first retardation layer satisfies the following formula (3): [4] Liquid crystal display device:
Re (550 nm) <200 nm (3)
However, Re (λ) is an in-plane retardation for light having a wavelength of λ nm.
[6] The liquid crystal display device according to [5], wherein the first retardation layer satisfies the following formula (4):
−50 nm ≦ Re (550) ≦ 150 nm (4).
[7] The first retardation layer contains cellulose acylate containing a substituent having a polarizability anisotropy Δα represented by the following formula (A) of 2.5 × 10 ⁻²⁴ cm ⁻³ or more. The liquid crystal display device according to any one of [1] to [6], comprising a film that performs:
Δα = αx− (αy + αz) / 2 (A)
In the formula, αx, αy, and αz are eigenvalues obtained after diagonalizing the polarizability tensor and satisfy αx ≧ αy ≧ αz.
[8] The liquid crystal display device according to any one of [1] to [6], wherein the first retardation layer is a layer formed of a composition containing a compound having a rod-like liquid crystal structural unit. .

  According to the present invention, a liquid crystal display device capable of displaying a high-quality image with a simple configuration and reduced gradation reversal and tinting (yellowing) that occurs during white display, particularly a twisted structure in a liquid crystal layer. It is possible to provide a parallel alignment type homogeneous ECB type liquid crystal display device which does not have.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the contents of 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.
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 Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis) (in the absence of the slow axis, any in-plane value) The light of wavelength λ nm is incident from each of the inclined directions in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction (with the direction of the rotation axis as the rotation axis). KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value.
In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative.
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).

−−−式（１）
Ｒｔｈ＝（（ｎｘ＋ｎｙ）／２ − ｎｚ） × ｄ −−−式（２）
注記：
上記のＲｅ（θ）は法線方向から角度θ傾斜した方向におけるレターデーション値をあらわす。
式中、ｎｘは面内における遅相軸方向の屈折率を表し、ｎｙは面内においてｎｘに直交する方向の屈折率を表し、ｎｚはｎｘ及びｎｙに直交する方向の屈折率を表す。

---- Formula (1)
Rth = ((nx + ny) / 2−nz) × d—the 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.

In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no 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.

Hereinafter, the liquid crystal display device of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of an example of the liquid crystal display device of the present invention. Note that FIG. 1 is a schematic diagram, and the relative relationship such as the thickness of the layers and the shape and size of the liquid crystalline molecules in each layer are not necessarily consistent with the actual ones. Absent. The same applies to FIG. 2 described later.
The liquid crystal display device shown in FIG. 1 includes an ECB mode liquid crystal cell 18 and a pair of an upper polarizing plate 20a and a lower polarizing plate 20b which are arranged with the liquid crystal cell interposed therebetween. The polarizing plates 20a and 20b include polarizing films 12a and 12b, protective films 14a and 14b having retardation, and retardation layers 16a and 16b, respectively.

  The liquid crystal cell 18 is a homogeneous ECB mode liquid crystal cell. Although the detailed structure is omitted in the figure, in general, it has a pair of transparent substrates and a liquid crystal layer sealed between them, and the alignment of the liquid crystals is controlled on the inner surface of the transparent substrate when no voltage is applied. And an electrode film capable of controlling the alignment of the liquid crystal. The liquid crystalline molecules in the homogeneous ECB liquid crystal cell 18 are aligned substantially parallel to the substrate surface when no voltage is applied, and the liquid crystal molecule twist angle between the substrates depends on the direction of rubbing treatment or the like applied to the alignment film. The direction of rubbing treatment applied to the alignment film is preferably 45 ° or less, and more preferably substantially parallel (± 10 ° or less). By setting it as such a range, the substantially parallel orientation (a twist angle is 45 degrees or less) which does not have a twist structure is realizable. The electrode film applies a voltage to the liquid crystal in the liquid crystal cell 18 to control its orientation. The electrode film is normally transparent and is made of, for example, indium tin oxide (ITO). The liquid crystal sealed between the upper and lower transparent substrates is not particularly limited. A material having a positive dielectric anisotropy Δε and generally a refractive index anisotropy Δn = 0.06 to 0.1 (589 nm, 20 ° C.) is used. The thickness d of the liquid crystal layer is about 2.5 to 5 μm. The brightness at the time of white display changes depending on the magnitude of the product Δn · d of the thickness d and the refractive index anisotropy Δn. Therefore, if the brightness is set to be in the range of 200 nm ≦ Δn · d ≦ 400 nm, good brightness is obtained. It is more preferable that Δnd that provides white display is 260 nm to 320 nm.

  The upper and lower polarizing plates 20a and 20b have a crossed Nicols arrangement in which the absorption axes of the polarizing films 12a and 12b are arranged to be orthogonal to each other. The absorption axes of the polarizing films 12a and 12b are the alignment directions of liquid crystalline molecules located in the vicinity of the transparent substrate located closer to the liquid crystal cell 18 (generally, the rubbing direction of the alignment film formed on the inner surface). In contrast, they are arranged so as to intersect at approximately 45 ° (35 to 55 °). The polarizing films 12a and 12b generally have a protective film made of a cellulose acylate film or the like that protects the polarizing film on both surfaces, but the protective film that protects the outer surface is omitted in FIG.

In this embodiment, the protective films 14a and 14b of the upper and lower polarizing films 12a and 12b are the first retardation layer and have optical characteristics that satisfy the following relational expression (1).
−280 nm <Rth (550) <50 nm (1)
Furthermore, it is preferable that the following relational expression (2) is satisfied.
−200 nm ≦ Rth (550) ≦ 0 nm (2)
In this embodiment, the in-plane retardation Re (550) of the protective films 14a and 14b preferably satisfies the following formula (3), and more preferably satisfies the following formula (4).
Re (550 nm) <200 nm (3)
−50 nm ≦ Re (550) ≦ 150 nm (4)
In this embodiment, the retardation film having the optical characteristics is used as a protective film on the liquid crystal cell side of the polarizing film, thereby reducing gradation inversion and color change (particularly yellowing) that occur during white display.

  The liquid crystal display device shown in FIG. 1 further includes second retardation layers 16a and 16b, which are optical compensation films containing a compound having a discotic structural unit, and 14a and 14b, which are first retardation layers, and a liquid crystal. Between the cell 18. By disposing the second retardation layers 16a and 16b, the transmittance during black display can be reduced, and as a result, a higher contrast image can be displayed with a wide viewing angle even during black display. be able to. In an ECB mode liquid crystal cell, in general, when a voltage is applied (black display), the liquid crystal molecules located in the vicinity of the cell substrate do not rise sufficiently, and retardation remains. The second retardation layer cancels this remaining retardation. Therefore, for example, in a mode in which the generation of residual retardation is suppressed by increasing the driving voltage, the second retardation layers 16a and 16b may not be provided, and the discotic structural unit may be used as long as it has a similar function. An optical compensation film made of a material other than the compound having an oriented polymer film or the like, or an alignment film of rod-like liquid crystalline molecules may be used. Further, when the second retardation layer for canceling the residual retardation is produced using the orientation of the compound having a discotic structural unit, the orientation control direction of the molecule of the compound having the discotic structural unit is It is preferable that the liquid crystal molecule orientation direction at the transparent substrate interface is substantially parallel. In general, the alignment control direction can be adjusted by the rubbing treatment direction of the alignment film used when producing an optical compensation film or the like.

  The optical properties of the second phase layers 16a and 16b are not particularly limited as long as they exhibit the above-described action, but Re (550) nm

  FIG. 1 shows a configuration in which the second retardation layers 16a and 16b are disposed between the pair of polarizing films 12a and 12b and the liquid crystal cell 18, but one of the pair of polarizing layers and the liquid crystal cell are shown. It may be arranged only between.

  In the embodiment of FIG. 1, the upper and lower polarizing plates 20 a and 20 b include a protective film (not shown), a polarizing film (12 a and 12 b), a first retardation layer (14 a and 14 b), and a second retardation layer (16 a and 16 b). 16b) in this order. In this embodiment, the first retardation layer (14a and 14b in FIG. 1) is used as a protective film for the polarizing film, and the second retardation layer (16a and 16b in FIG. 1) is formed from the liquid crystal composition. Since it is also used as a support at the time, the number of constituent members can be reduced and a thin liquid crystal display device is obtained.

FIG. 2 is a schematic sectional view of another example of the liquid crystal display device of the present invention. The same members as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
The liquid crystal display device shown in FIG. 2 includes an ECB-mode liquid crystal cell 18 and a pair of an upper polarizing plate 20a ′ and a lower polarizing plate 20b ′ arranged with the liquid crystal cell interposed therebetween. Between the polarizing plate 20 a ′ and the liquid crystal cell 18, and between the polarizing plate 20 b ′ and the liquid crystal cell 18, a support 14 a made of a polymer film or the like which is a first retardation layer (satisfies the above formula (1)). 14b and optical retardation films 21a and 21b having second retardation layers 16a and 16b formed thereon using a discotic liquid crystal composition are disposed.

In the aspect shown in FIG. 2, the arrangement relationship between the first retardation layer (14a, 14b) and the second retardation layer (16a, 16b) with respect to the liquid crystal cell 18 is reversed from the aspect shown in FIG. . In the embodiment shown in FIG. 2 as well, in the same manner as the embodiment shown in FIG. 1, the first phase difference layers 14a and 14b reduce gradation inversion and color change (particularly yellowing) that occur during white display. The viewing angle characteristics during black display are improved by the second retardation layers 16a and 16b.
In FIG. 2, the protective films 13a and 13b on the liquid crystal cell side of the polarizing plates 20a ′ and 20b ′ are preferably low retardation films. For example, the low retardation cellulose described in JP-A-2006-30937 An acylate film or the like is preferable.

  The aspect of FIG. 2 has the characteristic that the said outstanding effect is brought about irrespective of Re (550) of a 1st phase difference layer. As a result, there is an advantage that the range of selection of the retardation film used as the first retardation layer is widened.

  The driving voltage of the liquid crystal display device of the present invention is not particularly limited, and the liquid crystal display device can be driven within a general driving voltage range of the ECB mode liquid crystal display device. For example, the liquid crystal display device of the present invention can be driven in a normally white mode in which white display is performed when no voltage is applied, and black transmittance is displayed when a high voltage is applied. Black display is obtained when the Re value of the optical compensation film matches the retardation value of the liquid crystal layer in the voltage application state. This configuration is advantageous in that a wide range of high contrast is obtained and gradation inversion of halftone display does not occur. Furthermore, in the present invention, it is preferable to use an applied voltage condition showing a transmittance lower than the transmittance when no voltage is applied for maximum gradation (white display) because the viewing angle characteristics can be further expanded.

  In addition, it is preferable that the liquid crystal display device of the present invention has a structure called multi-domain in which one pixel is divided into a plurality of regions, since the viewing angle characteristics of luminance and color tone are further improved. Specifically, each pixel is composed of two or more (preferably 4 or 8) regions in which the initial alignment state of the liquid crystal molecules is different from each other, and averaging is performed. Can be reduced. Further, the same effect can be obtained even if each pixel is constituted by two or more different regions where the alignment direction of liquid crystal molecules continuously changes in a voltage application state.

  To form multiple regions with different alignment directions of liquid crystal molecules within one pixel, for example, use methods such as providing slits on electrodes, providing protrusions, changing the electric field direction, or biasing the electric field density. can do. In order to obtain a uniform viewing angle in all directions, the number of divisions may be increased. However, a substantially uniform viewing angle can be obtained by using four or more divisions. In particular, it is preferable that the polarizing plate absorption axis can be set at an arbitrary angle when dividing into eight.

  In the domain boundary of each domain, liquid crystal molecules tend to hardly respond. In the case of ECB, the white display state is maintained in the normally white mode, and thus the front contrast is lowered. Therefore, a light shielding layer such as a black matrix covering the region may be provided.

  The liquid crystal display device of the present invention is not limited to the configuration shown in FIGS. 1-2, and may include other members. For example, a color filter may be arranged between the liquid crystal cell and the polarizing film (may be inside or outside the liquid crystal cell). In addition, another optical compensation film may be separately disposed between the liquid crystal cell and the polarizing plate. In the case of use as a transmission type, a cold cathode or a hot cathode fluorescent tube, or a backlight having a light emitting diode, a field emission element, or an electroluminescent element as a light source can be disposed on the back surface. In addition, the liquid crystal display device of the present invention may be of a reflective type. In such a case, only one polarizing plate may be disposed on the observation side, and reflected on the back surface of the liquid crystal cell or the inner surface of the lower substrate of the liquid crystal cell. Install the membrane. Of course, it is also possible to provide a front light using the light source on the liquid crystal cell observation side.

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

In the liquid crystal display device of the present invention, the degree of yellowishness when observed from an oblique direction (angle horizontal polar angle 60 °) is b ^* coordinates of 28 or less in the L ^* a ^* b ^* color system. Is more preferable and 20 or less is more preferable. Further, the gradation inversion angle between black (0/7 gradation) and halftone (4/7) is preferably 35 or more, and more preferably 45 or more.

  Next, materials used for various members that can be used in the liquid crystal display device of the present invention, manufacturing methods thereof, and the like will be described in detail.

[First retardation layer]
The liquid crystal display device of the present invention has a first retardation layer that satisfies the following formula (1).
−280 nm <Rth (550) <50 nm (1)
The first retardation layer preferably satisfies the following formula (2).
−200 nm ≦ Rth (550) ≦ 0 nm (2).
Re (550) is not particularly limited, and can be determined according to the configuration of the liquid crystal display device (arrangement relationship between the first and second retardation layers), the optical characteristics of the liquid crystal cell, and the like. The preferred range is as described above.

(First cellulose acylate film for optically anisotropic layer)
The first retardation layer may be a cellulose acylate film. Hereinafter, the cellulose acylate film preferably used as the first retardation layer in the present invention will be described in detail.
In the present invention, the cellulose acylate film preferably used as the first retardation layer satisfies the above formula (1). The cellulose acylate film preferably has substantially no optical axis in the film plane, and preferably satisfies the above formula (3). The cellulose acylate film satisfying the above formula (1) has a polarizability anisotropy as a substituent in which the cellulose acylate used as a raw material is linked to three hydroxyl groups on the β-glucose ring as a constituent unit. It is preferable to have a large substituent. By introducing a substituent having a large polarizability anisotropy into the cellulose sylate and adjusting the other substituent and the degree of substitution, the refractive index is maximized in the film thickness direction, and the cellulose satisfies the above formula (1) An acylate film is obtained.

(Distance between substituent ends and polarizability anisotropy)
The polarizability anisotropy of cellulose acylate is defined by the following mathematical formula (1).
Formula (1): Δα = αx− (αy + αz) / 2
(In the formula, αx, αy, and αz are eigenvalues obtained after diagonalizing the polarizability tensor, and αx ≧ αy ≧ αz.) The polarizability anisotropy is in the direction perpendicular to the stretching direction during film stretching. This is related to refractive index expression. That is, when the polarizability anisotropy is small, a slow axis appears in the stretching direction, and when the polarizability anisotropy is large, a slow axis appears in the stretching orthogonal direction. In order to produce a cellulose acylate film satisfying the above formula (1), the higher the polarizability anisotropy of the cellulose acylate as a raw material, the more preferable, preferably 2.5 × 10 ⁻²⁴ cm ⁻³ or more. More preferably 3.5 × 10 ⁻²⁴ cm ⁻³ or more, and particularly preferably 4.5 × 10 ⁻²⁴ cm ⁻³ or more.
In addition, the distance between terminals and the polarizability anisotropy of the substituent of cellulose acylate are calculated using Gaussian 03 (Revision B.03, US Gaussian software). The end-to-end distance is calculated as the distance between the most distant atoms after structural optimization by calculation at the B3LYP / 6-31G * level. The polarizability anisotropy is calculated using the structure optimized at the B3LYP / 6-31G * level, after calculating the polarizability at the 3LYP / 6-311 + G ** level and diagonalizing the obtained polarizability tensor. Calculated from the diagonal component. In the calculation of the distance between the terminal ends of the substituent and the polarizability anisotropy, the substituent linked to the hydroxyl group on the β-glucose ring, which is the structural unit of cellulose acylate, is calculated with the partial structure containing the oxygen atom of the hydroxyl group. And ask.

  The cellulose acylate used for producing the cellulose acylate film is preferably a mixed acid ester having a fatty acid acyl group and a substituted or unsubstituted aromatic acyl group. Examples of the substituted or unsubstituted aromatic acyl group include groups represented by the following general formula (A).

Formula (A)

In the general formula (A), X is a substituent. Examples of the substituent include a halogen atom, cyano, alkyl group, alkoxy group, aryl group, aryloxy group, acyl group, carbonamido group, sulfonamido group, ureido. Group, aralkyl group, nitro, alkoxycarbonyl group, aryloxycarbonyl group, aralkyloxycarbonyl group, carbamoyl group, sulfamoyl group, acyloxy group, alkenyl group, alkynyl group, alkylsulfonyl group, arylsulfonyl group, alkyloxysulfonyl group, aryl Oxysulfonyl group, alkylsulfonyloxy group, and aryloxysulfonyl group, —S—R, —NH—CO—OR, —PH—R, —P (—R) ₂ , —PH—O—R, —P (— R) (- O-R) , - P (-O-R) 2, -PH (= O) -R-P _{= O) (- R) 2} , -PH (= O) -O-R, -P (= O) (- R) (- O-R), - P (= O) (- O-R) 2 , -O-PH (= O) -R, -OP (= O) (-R) _2- O-PH (= O) -O-R, -OP (= O) (-R) (—O—R), —O—P (═O) (— O—R) ₂ , —NH—PH (═O) —R, —NH—P (═O) (— R) (— O— R), —NH—P (═O) (— O—R) ₂ , —SiH ₂ —R, —SiH (—R) ₂ , —Si (—R) ₃ , —O—SiH ₂ —R, — O-SiH (-R) ₂ and -O-Si (-R) ₃ are included. R is an aliphatic group, an aromatic group or a heterocyclic group. The number of substituents is preferably from 1 to 5, more preferably from 1 to 4, more preferably from 1 to 3, and even more preferably 1 or 2. As the substituent, a halogen atom, cyano, alkyl group, alkoxy group, aryl group, aryloxy group, acyl group, carbonamido group, sulfonamido group and ureido group are preferable, halogen atom, cyano, alkyl group, alkoxy group, An aryloxy group, an acyl group and a carbonamido group are more preferred, a halogen atom, cyano, an alkyl group, an alkoxy group and an aryloxy group are more preferred, and a halogen atom, an alkyl group and an alkoxy group are still more preferred.

  The halogen atom includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. The alkyl group is most preferred. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, t-butyl, hexyl, cyclohexyl, octyl and 2-ethylhexyl. The alkoxy group may have a cyclic structure or a branch. The number of carbon atoms in the alkoxy group is preferably 1-20, more preferably 1-12, still more preferably 1-6, and even more preferably 1-4. The alkoxy group may be further substituted with another alkoxy group. Examples of the alkoxy group include methoxy, ethoxy, 2-methoxyethoxy, 2-methoxy-2-ethoxyethoxy, butyloxy, hexyloxy and octyloxy.

  The number of carbon atoms of the aryl group is preferably 6-20, and more preferably 6-12. Examples of the aryl group include phenyl and naphthyl. The aryloxy group preferably has 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms. Examples of the aryloxy group include phenoxy and naphthoxy. The number of carbon atoms in the acyl group is preferably 1-20, and more preferably 1-12. Examples of acyl groups include formyl, acetyl and benzoyl. The number of carbon atoms of the carbonamide group is preferably 1-20, and more preferably 1-12. Examples of the carbonamido group include acetamide and benzamide. The number of carbon atoms in the sulfonamide group is preferably 1-20, and more preferably 1-12. Examples of the sulfonamide group include methanesulfonamide, benzenesulfonamide, and p-toluenesulfonamide. The number of carbon atoms in the ureido group is preferably 1-20, and more preferably 1-12. Examples of ureido groups include (unsubstituted) ureido.

The alkyl group may have a cyclic structure or a branch. The number of carbon atoms of the alkyl group is preferably 1-20, more preferably 1-12, still more preferably 1-6, and 1-4.
The number of carbon atoms in the aralkyl group is preferably 7-20, and more preferably 7-12. Examples of aralkyl groups include benzyl, phenethyl and naphthylmethyl. The number of carbon atoms in the alkoxycarbonyl group is preferably 1-20, and more preferably 2-12. Examples of the alkoxycarbonyl group include methoxycarbonyl. The aryloxycarbonyl group preferably has 7 to 20 carbon atoms, and more preferably 7 to 12 carbon atoms. Examples of the aryloxycarbonyl group include phenoxycarbonyl. The number of carbon atoms in the aralkyloxycarbonyl group is preferably 8-20, and more preferably 8-12. Examples of the aralkyloxycarbonyl group include benzyloxycarbonyl. The number of carbon atoms of the carbamoyl group is preferably 1-20, and more preferably 1-12. Examples of the carbamoyl group include (unsubstituted) carbamoyl and N-methylcarbamoyl. The number of carbon atoms in the sulfamoyl group is preferably 20 or less, and more preferably 12 or less. Examples of sulfamoyl groups include (unsubstituted) sulfamoyl and N-methylsulfamoyl. The number of carbon atoms in the acyloxy group is preferably 1-20, and more preferably 2-12. Examples of the acyloxy group include acetoxy and benzoyloxy.

  The alkenyl group has preferably 2 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms. Examples of alkenyl groups include vinyl, allyl and isopropenyl. The number of carbon atoms in the alkynyl group is preferably 2-20, and more preferably 2-12. Examples of alkynyl groups include thienyl. The number of carbon atoms in the alkylsulfonyl group is preferably 1-20, and more preferably 1-12. The number of carbon atoms of the arylsulfonyl group is preferably 6-20, and more preferably 6-12. The alkyloxysulfonyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms. The number of carbon atoms of the aryloxysulfonyl group is preferably 6-20, and more preferably 6-12. The alkyloxysulfonyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms. The number of carbon atoms of the aryloxysulfonyl group is preferably 6-20, and more preferably 6-12.

  In the fatty acid ester residue in the cellulose mixed acid ester, the aliphatic acyl group preferably has 2 to 20 carbon atoms, specifically acetyl, propionyl, butyryl, isobutyryl, valeryl, pivaloyl, hexanoyl, octanoyl, Examples include lauroyl and stearoyl. Acetyl, propionyl and butyryl are preferred, and acetyl is particularly preferred. In addition, an aliphatic acyl group is meant to include those further having a substituent, and examples of the substituent include those exemplified as X in the general formula (A).

  In the general formula (A), the number (n) of the substituents X substituted on the aromatic ring is 0 or 1 to 5, preferably 1 to 3, particularly preferably 1 or 2. It is.

  Further, when the number of substituents substituted on the aromatic ring is 2 or more, they may be the same or different from each other, but they may be linked together to form a condensed polycyclic compound (for example, naphthalene, indene, indane, phenanthrene, quinoline). , Isoquinoline, chromene, chroman, phthalazine, acridine, indole, indoline, etc.). Specific examples of the aromatic acyl group represented by the general formula (A) are as shown below. 1, 3, 5, 6, 8, 13, 18, 28, more preferably 1, 3, 6, and 13.

  Examples of the method for substituting the hydroxyl group of cellulose with an aromatic acyl group generally include a method using a symmetric acid anhydride and a mixed acid anhydride derived from an aromatic carboxylic acid claloid or an aromatic carboxylic acid. . Particularly preferred is a method using an acid anhydride derived from an aromatic carboxylic acid (described in Journal of Applied Polymer Science, Vol. 29, 3981-3990 (1984)). As a method for producing the cellulose mixed acid ester compound of the present invention as the above-mentioned method, (1) once the cellulose fatty acid monoester or diester is produced, the remaining hydroxyl group is an aromatic acyl represented by the general formula (A) And (2) a method in which a mixed acid anhydride of an aliphatic carboxylic acid and an aromatic carboxylic acid is directly reacted with cellulose. In the former, the production method of the cellulose fatty acid ester or diester is a well-known method, but the subsequent reaction for introducing an aromatic acyl group into this further varies depending on the type of the aromatic acyl group, but preferably the reaction temperature. The reaction time is 0 to 100 ° C., more preferably 20 to 50 ° C., and the reaction time is preferably 30 minutes or more, more preferably 30 to 300 minutes. In the latter method using the mixed acid anhydride, the reaction conditions vary depending on the type of the mixed acid anhydride, but the reaction temperature is preferably 0 to 100 ° C., more preferably 20 to 50 ° C., and the reaction time is preferably 30 to 300. Minutes, more preferably 60 to 200 minutes. In any of the above reactions, the reaction may be performed in the absence of a solvent or in a solvent, but is preferably performed using a solvent. As the solvent, dichloromethane, chloroform, dioxane and the like can be used.

The degree of substitution in the present invention is 3.0 when the hydroxyl group of cellulose is substituted 100%. The degree of substitution can be determined from the peak intensity of the carbonyl carbon in the acyl group in C ¹³ -NMR.
In the case of a cellulose fatty acid monoester, the degree of substitution of the aromatic acyl group is 2.0 or less, preferably 0.1 to 2.0, more preferably 0.1 to 1.0 with respect to the remaining hydroxyl group. In the case of cellulose fatty acid diester (cellulose diacetate), it is 1.0 or less, preferably 0.1 to 1.0, based on the remaining hydroxyl group. Moreover, it is preferable that the total substitution degree PA of a cellulose acylate is 2.4-3.

  The cellulose acylate preferably has a mass average degree of polymerization of 350 to 800, and more preferably has a mass average degree of polymerization of 370 to 600. The cellulose acylate used in the present invention preferably has a number average molecular weight of 70000 to 230,000, more preferably 75000 to 230,000, and more preferably 78000 to 120,000. Further preferred.

  The cellulose acylate can be synthesized using an acid anhydride or acid chloride as an acylating agent. When the acylating agent is an acid anhydride, an organic acid (for example, acetic acid) or methylene chloride is used as a reaction solvent. As the catalyst, a protic catalyst such as sulfuric acid is used. When the acylating agent is an acid chloride, a basic compound is used as a catalyst. In the most common synthetic method in the industry, cellulose is an organic acid corresponding to acetyl group and other acyl groups (acetic acid, propionic acid, butyric acid) or their acid anhydrides (acetic anhydride, propionic anhydride, butyric anhydride). A cellulose ester is synthesized by esterification with a mixed organic acid component containing.

  In this method, cellulose such as cotton linter and wood pulp is activated with an organic acid such as acetic acid, and then esterified using a mixture of organic acid components as described above in the presence of a sulfuric acid catalyst. There are many cases to do. The organic acid anhydride component is generally used in an excess amount relative to the amount of hydroxyl groups present in the cellulose. In this esterification treatment, in addition to the esterification reaction, a hydrolysis reaction (depolymerization reaction) of the cellulose main chain β1 → 4-glycoside bond) proceeds. When the hydrolysis reaction of the main chain proceeds, the degree of polymerization of the cellulose ester is lowered, and the physical properties of the cellulose ester film to be produced are lowered. Therefore, the reaction conditions such as the reaction temperature are preferably determined in consideration of the degree of polymerization and molecular weight of the resulting cellulose ester.

  In order to obtain a cellulose ester having a high degree of polymerization (high molecular weight), it is important to adjust the maximum temperature in the esterification reaction step to 50 ° C. or lower. The maximum temperature is preferably adjusted to 35 to 50 ° C, more preferably 37 to 47 ° C. A reaction temperature of 35 ° C. or higher is preferable because the esterification reaction proceeds smoothly. A reaction temperature of 50 ° C. or lower is preferable because inconveniences such as a decrease in the degree of polymerization of the cellulose ester do not occur.

  After the esterification reaction, when the reaction is stopped while suppressing the temperature rise, a decrease in the polymerization degree can be further suppressed, and a cellulose ester having a high polymerization degree can be synthesized. That is, when a reaction terminator (for example, water or acetic acid) is added after completion of the reaction, the excess acid anhydride that did not participate in the esterification reaction is hydrolyzed to form a corresponding organic acid as a by-product. This hydrolysis reaction is accompanied by intense heat generation, and the temperature in the reactor rises. If the rate of addition of the reaction terminator is not too high, heat is rapidly generated exceeding the cooling capacity of the reactor, the hydrolysis reaction of the cellulose main chain proceeds significantly, and the degree of polymerization of the resulting cellulose ester decreases. Such a problem does not occur. In addition, a part of the catalyst is bonded to the cellulose during the esterification reaction, and most of the catalyst is dissociated from the cellulose during the addition of the reaction terminator. If the rate of addition of the reaction terminator is not too high at this time, a sufficient reaction time is secured for dissociating the catalyst, and problems such as part of the catalyst remaining in a state of being bound to cellulose are unlikely to occur. Cellulose esters to which a strong acid catalyst is partially bonded are very poor in stability, and are easily decomposed by heat during drying of the product to lower the degree of polymerization. For these reasons, after the esterification reaction, it is preferable to stop the reaction by adding a reaction terminator over a period of preferably 4 minutes or more, more preferably 4 to 30 minutes. In addition, it is preferable if the addition time of the reaction terminator is 30 minutes or less because problems such as a decrease in industrial productivity do not occur.

  As the reaction terminator, water or alcohol that decomposes an acid anhydride is generally used. However, in the present invention, a mixture of water and an organic acid is preferably used as a reaction terminator in order not to precipitate triesters having low solubility in various organic solvents. When the esterification reaction is carried out under the above conditions, a high molecular weight cellulose ester having a mass average polymerization degree of 500 or more can be easily synthesized.

  In the cellulose acylate film satisfying the general formula (1), a compound (also referred to as an Rth reducing agent) that lowers Rth may be used in order to achieve a desired retardation Rth in the thickness direction. The Rth-reducing compound is preferably contained in an amount of 0.01 to 30% by mass, more preferably 0.1 to 25% by mass, and still more preferably 0.1 to 20%, based on the cellulose acylate solid content. % By mass.

The compound that lowers Rth is sufficiently compatible with cellulose acylate, and it is advantageous that 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 the cellulose acylate film used in the present invention, among the compounds that reduce the optical anisotropy by inhibiting the cellulose acylate in the film from being oriented in the plane and in the film thickness direction as described above, Compounds having an octanol-water partition coefficient (log P value) of 0 to 7 are preferred. A compound having a log P value of 7 or less is excellent in compatibility with cellulose acylate, and hardly causes white turbidity or powder blowing of the film. A compound having a log P value of 0 or more is suitable for hydrophilicity and improves the water resistance of the cellulose acylate film. 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 the scope of the present invention by the Crippen's fragmentation method.

The compound that lowers Rth may or may not contain an aromatic group. The compound that reduces the optical anisotropy preferably has a molecular weight of 150 or more and 3000 or less, preferably 170 or more and 2000 or less, and particularly preferably 200 or more and 1000 or less. 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 lowers Rth is preferably a liquid at 25 ° C. or a solid having a melting point of 25 to 250 ° C., more preferably a liquid at 25 ° C. or a solid having a melting point of 25 to 200 ° C. is there. 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.
A compound that lowers Rth may be used alone, or two or more compounds may be mixed and used in an arbitrary ratio.
The timing of adding the compound that lowers Rth may be any time during the dope preparation process, or may be performed at the end of the dope preparation process.

  In the compound that reduces Rth, 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 80- of the average content of the compound in the central portion of the cellulose acylate film. 99%. The abundance of the compound of the present invention can be determined, for example, by measuring the amount of the compound at the surface and in the center by the method using an infrared absorption spectrum described in JP-A-8-57879.

  Although the specific example of the compound which reduces Rth used for preparation of the cellulose acylate film used preferably as said 1st phase difference layer below is shown, it is not limited to these compounds.

General formula (B)

In the general formula (B), 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.

  The above alkyl group and aryl group 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, and an alkyl group, an aryl group, an alkoxy group. Particularly preferred are groups, sulfone groups and sulfonamide groups.

  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, bicyclooctyl, nonyl, adamantyl, decyl, t-octyl, undecyl, dodecyl , Tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, didecyl, etc.) 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, biphenyl, terphenyl, naphthyl, binaphthyl, triphenylphenyl, etc.) are particularly preferable.
Although the preferable example of a compound represented by general formula (B) below is shown, it is not limited to these specific examples.

General formula (C)

In the general formula (C), R ³¹ represents an alkyl group or an aryl group, and R ³² and R ³³ each independently represent a hydrogen atom, an alkyl group, or an aryl group. Here, the alkyl group may be linear, branched or cyclic, and preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and 1 to 12 carbon atoms. Are even more preferred. As the cyclic alkyl group, a cyclohexyl group is particularly preferable. The aryl group preferably has 6 to 36 carbon atoms, and more preferably 6 to 24 carbon atoms.

  The above alkyl group and aryl group may have a substituent. Examples of the substituent include a halogen atom (for example, chlorine, bromine, fluorine and iodine), an alkyl group, an aryl group, an alkoxy group, an aryloxy group, An acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, a sulfonylamino group, a hydroxy group, a cyano group, an amino group, and an acylamino group are preferable, and a halogen atom, an alkyl group, an aryl group, an alkoxy group, and an aryloxy are more preferable. Group, sulfonylamino group and acylamino group, particularly preferably alkyl group, aryl group, sulfonylamino group and acylamino group.

  Preferred examples of the compound represented by the general formula (C) are shown below, but the present invention is not limited to these specific examples.

The cellulose acylate film may contain a wavelength dispersion adjusting agent in order to obtain a desired wavelength dispersion.
Specific examples of the wavelength dispersion adjusting agent include, for example, benzotriazole compounds, benzophenone compounds, cyano group-containing compounds, oxybenzophenone compounds, salicylic acid ester compounds, nickel complex compounds, and the like. It is not limited to.

As the benzotriazole-based compound, those represented by the general formula (101) are preferably used as the wavelength dispersion adjusting agent of the present invention.
Formula (101) Q ¹ -Q ² -OH
In the formula, Q ¹ represents a nitrogen-containing aromatic heterocycle, and Q ² represents an aromatic ring.

Q ¹ represents a nitrogen-containing aromatic heterocycle, preferably a 5- to 7-membered nitrogen-containing aromatic heterocycle, more preferably a 5- to 6-membered nitrogen-containing aromatic heterocycle, such as imidazole, Pyrazole, triazole, tetrazole, thiazole, oxazole, selenazole, benzotriazole, benzothiazole, benzoxazole, benzoselenazole, thiadiazole, oxadiazole, naphthothiazole, naphthoxazole, azabenzimidazole, purine, pyridine, pyrazine, pyrimidine, pyridazine , Triazine, triazaindene, tetrazaindene and the like, more preferably a 5-membered nitrogen-containing aromatic heterocycle, specifically, imidazole, pyrazole, triazole, tetrazole, thiazole, oxazol. , Benzotriazole, benzothiazole, benzoxazole, thiadiazole, oxadiazole preferably, particularly preferably benzotriazole.
The nitrogen-containing aromatic heterocycle represented by Q ¹ may further have a substituent, and the substituent T described below can be applied as the substituent. In addition, when there are a plurality of substituents, each may be condensed to further form a ring.

The aromatic ring represented by 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 is preferably (preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, benzene ring, naphthalene ring etc.), more preferably 6 carbon atoms. -20 aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms.) More preferred is 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, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, isoquinoline, Examples include phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, and tetrazaindene. Preferred examples of the aromatic heterocycle include pyridine, triazine, and quinoline.
The aromatic ring represented by Q ² is preferably an aromatic hydrocarbon ring, more preferably a naphthalene ring or a benzene ring, and particularly preferably a benzene ring. Q ² may further have a substituent, and the substituent T described later is preferable.

  The substituent T includes an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methyl, ethyl, iso-propyl, tert-butyl, and n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably carbon number). 2 to 8, for example, vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably carbon number). 2-8, for example, propargyl, 3-pentynyl, etc.), aryl groups (preferably 6-30 carbons, more preferred) Or having 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenyl, p-methylphenyl, naphthyl, etc.), a substituted or 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 amino, methylamino, dimethylamino, diethylamino, dibenzylamino, etc.), an alkoxy group (preferably having 1 carbon atom). To 20, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methoxy, ethoxy, butoxy, etc.), an aryloxy group (preferably 6 to 20 carbon atoms, more preferably). Has 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyloxy and 2-naphthyloxy. ), An acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include acetyl, benzoyl, formyl, pivaloyl, etc.), alkoxycarbonyl A group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, etc.), an aryloxycarbonyl group (preferably 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 10 carbon atoms, such as phenyloxycarbonyl, etc.), acyloxy group (preferably 2 to 20 carbon atoms, more preferably Has 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as acetoxy, benzoyl Examples include oxy. ), 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 acetylamino and benzoylamino), alkoxycarbonylamino group (Preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino), aryloxycarbonylamino group (preferably having carbon number) 7 to 20, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino, and the like, and sulfonylamino groups (preferably 1 to 20 carbon atoms, more preferably Has 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms. And 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 and methylsulfamoyl). , Dimethylsulfamoyl, phenylsulfamoyl, etc.), a carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as carbamoyl). , Methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl, etc.), an alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio, Ethylthio etc.), arylthio group (preferably Has 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio, and a sulfonyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as mesyl, tosyl, etc.), sulfinyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably Has 1 to 12 carbon atoms, such as methanesulfinyl, benzenesulfinyl, etc.), ureido group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms). For example, ureido, methylureido, phenylureido, etc.), phosphoric acid amide group (preferably having 1 to 20 carbon atoms) More preferably, it is C1-C16, Most preferably, it is C1-C12, for example, diethyl phosphoric acid amide, phenylphosphoric acid amide etc. are mentioned. ), 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, a sulfur atom, specifically, for example, imidazolyl, pyridyl, quinolyl, furyl, piperidyl , Morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, etc.), silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, and particularly preferably 3 to 24 carbon atoms). And examples thereof include trimethylsilyl and triphenylsilyl). 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.

  Preferred as the general formula (101) is a compound represented by the following general formula (101-A).

General formula (101-A)

In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ each independently represent a hydrogen atom or a substituent.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ each independently represent a hydrogen atom or a substituent, and the substituent T described above can be applied as the substituent. Further, 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 preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted amino groups, alkoxy groups, aryloxy groups, hydroxy groups, and halogen atoms, more preferably hydrogen atoms. An 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 4 to 12 carbon atoms).

R ² and R ⁴ are preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted amino groups, alkoxy groups, aryloxy groups, hydroxy groups, and halogen atoms, more preferably hydrogen atoms. An 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 It is a hydrogen atom.

R ⁵ and R ⁸ are preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted amino groups, alkoxy groups, aryloxy groups, hydroxy groups, and halogen atoms, more preferably hydrogen atoms. An 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 It is a hydrogen atom.

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

  More preferable as the general formula (101) is a compound represented by the following general formula (101-B).

General formula (101-B)

In the formula, R ¹ , R ³ , R ⁶ and R ⁷ have the same meanings as those in 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.

  Of the benzotriazole compounds exemplified above, compounds having a molecular weight of 320 or less are preferably used.

  As the wavelength dispersion adjusting agent, a benzophenone compound represented by the general formula (102) is also preferably used.

General formula (102)

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

In the general formula (102), the aromatic ring represented by Q ¹ and 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, 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, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, Examples include quinoline, isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzothiazole, benzotriazole, and tetrazaindene. Preferred examples of the aromatic heterocycle include pyridine, triazine, and quinoline.
The aromatic ring represented by Q ¹ and Q ² is preferably an aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 10 carbon atoms, still more preferably a substituted or unsubstituted benzene ring. is there.
Q ¹ and Q ² may further have a substituent, and are preferably selected from the aforementioned substituent T, 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. Substituent T described later can be applied as the substituent), an oxygen atom or a sulfur atom, and X is preferably NR (R is preferably an acyl group) , A sulfonyl group, and these substituents may be further substituted.), Or O, particularly preferably O.

  As the general formula (102), a compound represented by the following general formula (102-A) is preferable.

Formula (102-A)

In General Formula (102-A), 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.

In the general formula (102-A), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , and R ⁹ each independently represents a hydrogen atom or a substituent. The above-mentioned substituent T can be applied. Further, these substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ¹ , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁸ and R ⁹ are preferably hydrogen, alkyl, alkenyl, alkynyl, aryl, substituted or unsubstituted amino, alkoxy, aryl An oxy 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 ² is preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, a halogen atom, more preferably a hydrogen atom or one carbon atom. An alkyl group having -20 carbon atoms, an amino group having 0-20 carbon atoms, an alkoxy group having 1-12 carbon atoms, an aryloxy group having 6-12 carbon atoms, and a hydroxy group, and more preferably an alkoxy group having 1-20 carbon atoms. And particularly preferably an alkoxy group having 1 to 12 carbon atoms.

R ⁷ is preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, a halogen atom, more preferably a hydrogen atom or a carbon number of 1 An alkyl group having -20 carbon atoms, an amino group having 0-20 carbon atoms, an alkoxy group having 1-12 carbon atoms, an aryloxy group having 6-12 carbon atoms, and a hydroxy group, more preferably a hydrogen atom, having 1-20 carbon atoms. An alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, still more preferably a methyl group), particularly preferably a methyl group or a hydrogen atom.

  More preferable as the general formula (102) is a compound represented by the following general formula (102-B).

General formula (102-B)

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

R ¹⁰ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group. Applicable.
R ¹⁰ is preferably a substituted or unsubstituted alkyl group, more preferably a substituted or unsubstituted alkyl group having 5 to 20 carbon atoms, and still more preferably a substituted or unsubstituted alkyl group having 5 to 12 carbon atoms. (Including n-hexyl group, 2-ethylhexyl group, n-octyl group, n-decyl group, n-dodecyl group, benzyl group, etc.), particularly preferably a substitution of 6 to 12 carbon atoms or It is an unsubstituted alkyl group (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, it is also preferable to use the compound containing the cyano group represented by General formula (103) as said wavelength dispersion regulator.

General formula (103)

In general formula (103), Q ¹ and Q ² each independently represents an aromatic ring. X ¹ and X ² each represent a hydrogen atom or a substituent, at least one of which is a cyano group, and the other preferably represents a carbonyl group, a sulfonyl group or an aromatic heterocycle. ) The aromatic ring represented by Q ¹ and 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 is preferably (preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, benzene ring, naphthalene ring etc.), more preferably 6 carbon atoms. -20 aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms.) More preferred is 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, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, isoquinoline, Examples include phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, and tetrazaindene. Preferred examples of the aromatic heterocycle include pyridine, triazine, and quinoline.

The aromatic ring represented by Q ¹ and Q ² is preferably an aromatic hydrocarbon ring, and more preferably a benzene ring.
Q ¹ and Q ² may further have a substituent, and are preferably selected from the aforementioned substituent T.

X ¹ and X ² each represent a hydrogen atom or a substituent, at least one of which is a cyano group, and the other preferably represents a carbonyl group, a sulfonyl group, or an aromatic heterocycle. The substituent T described above can be applied to the substituents represented by X ¹ and X ² . In addition, the substituent represented by X ¹ and X ² may be further substituted with another substituent, and X ¹ and X ² may be condensed to form a ring structure.

X ¹ and X ² 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.

  As the general formula (103), a compound represented by the following general formula (103-A) is preferable.

General formula (103-A)

In general formula (103-A), R < ¹ >, R < ² >, R < ³ >, R < ⁴ >, R < ⁵ >, R < ⁶ >, R < ⁷ >, R <^8> , R < ⁹ > and R < ¹⁰ > each independently represents a hydrogen atom or a substituent. X ¹ and X ² have the same meanings as those in formula (103), and preferred ranges are also the same.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represents a hydrogen atom or a substituent. Is applicable. Further, these substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ¹ , R ² , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁹ , and R ¹⁰ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, An alkoxy group, an 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 carbon 1-12. An alkyl group, particularly preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.

R ³ and R ⁸ are preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted amino groups, alkoxy groups, aryloxy groups, hydroxy groups, halogen atoms, more preferably hydrogen atoms. , 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 a carbon number. It is a 1-12 alkyl group and a C1-C12 alkoxy group, Most preferably, it is a hydrogen atom.

  More preferable as the general formula (103) is a compound represented by the following general formula (103-B).

General formula (103-B)

In general formula (103-B), R ³ and R ⁸ have the same meanings as those in general formula (103-A), and preferred ranges are also the same. X ³ represents a hydrogen atom or a substituent.

X ³ 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 another substituent. X ³ 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 heterocyclic ring, more preferably a cyano group, a carbonyl group, a sulfonyl group or an aromatic heterocyclic ring. 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, an aryl having 6 to 12 carbon atoms). Group and a combination thereof).

  More preferable as the general formula (103) is a compound represented by the general formula (103-C).

General formula (103-C)

In General Formula (103-C), R ³ and R ⁸ have the same meanings as those in General Formula (103-A), and preferred ranges are also the same. R ²¹ represents an alkyl group having 1 to 20 carbon atoms.

R ²¹ is preferably an alkyl group having 2 to 12 carbon atoms, more preferably an alkyl group having 4 to 12 carbon atoms, and still more preferably 6 carbon atoms when both R ³ and R ⁸ are hydrogen. To 12 alkyl groups, particularly preferably n-octyl group, tert-octyl group, 2-ethylhexyl group, n-decyl group, n-dodecyl group, most preferably 2-ethylhexyl group. It is.

Preferably, when R ³ and R ⁸ are other than hydrogen as R ²¹ , the compound represented by the general formula (103-C) has a molecular weight of 300 or more and an alkyl group having 20 or less carbon atoms. preferable.

  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 invention is not limited to the following specific examples.

  The cellulose acylate film can be produced in a long shape using various methods such as an extrusion method and a solution casting method. In order to obtain predetermined optical characteristics after being formed into a film, it is desirable to further perform a stretching treatment. When the film is produced by using the solution casting method, a plasticizer (preferably added amount is 0.1 to 20% by mass with respect to the cellulose ester, the same applies hereinafter) and a modifier (0. 1 to 20% by mass), an ultraviolet absorber (0.001 to 10% by mass), a fine particle powder (0.001 to 5% by mass) having an average particle diameter of 5 to 3000 nm, and a fluorosurfactant (0. 001-2 mass%), release agent (0.0001-2 mass%), deterioration inhibitor (0.0001-2 mass%), optical anisotropy control agent (0.1-15 mass%), infrared absorption You may contain additives, such as an agent (0.1-5 mass%). In addition, about the production method of a film, the details are described in the public technique 2001-1745 (issued on March 15,2001, invention association) etc., and can be applied to this invention.

The obtained cellulose acylate film can be appropriately subjected to surface treatment to improve adhesion between the cellulose acylate layer and other layers. The surface treatment includes glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, saponification treatment (acid saponification treatment, alkali saponification treatment), and glow discharge treatment and alkali saponification treatment are particularly preferable.
As described above, the first retardation layer is required only for a film containing cellulose acylate containing a substituent having a polarizability anisotropy Δα of 2.5 × 10 ⁻²⁴ cm ⁻³ or more. Although the optical characteristics can be satisfied, the scope of the present invention includes an embodiment in which the first retardation layer includes another birefringent film or retardation film together with the cellulose acylate film.

(First retardation layer formed from a liquid crystal composition)
The first retardation layer may be a layer formed using a liquid crystal composition. For example, a layer formed by curing a polymerizable liquid crystal composition containing a polymerizable material by polymerization may be used. The liquid crystal material is preferably a rod-like liquid crystal. In order to satisfy the formula (1) and form a retardation layer having no in-plane optical axis, the rod-like liquid crystal is vertically aligned (homeotropic alignment) with respect to the layer surface and fixed in the alignment state. Is preferably formed. As rod-shaped liquid crystals, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyl Dioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. Not only the above low-molecular liquid crystalline compounds but also high-molecular liquid crystalline compounds can be used. It is more preferable to fix the alignment of the rod-like liquid crystal compound by polymerization. As the liquid crystal molecules, those having a partial structure capable of causing polymerization or crosslinking reaction by actinic rays, electron beams, heat, or the like are preferably used. The number of the partial structures is 1 to 6, preferably 1 to 3. As the polymerizable rod-like liquid crystalline compound, Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. No. 4,683,327, US Pat. No. 5,622,648, US Pat. No. 5,770,107, International Publication No. WO95 / 22586, No. 95/24455, No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, No. 6-16616, No. 7-110469, The compounds described in JP-A-11-80081 and JP-A-2001-328773 can be used.

Various agents such as a polymerization initiator, a polymerizable monomer, a vertical alignment agent, and a surfactant may be added to the liquid crystal composition.
When the first retardation layer is formed from a liquid crystal composition, it may be incorporated in a liquid crystal display device as an optical compensation film in which the layer is formed on the surface of a support such as a polymer film. However, in such a case, it is preferable that the support satisfies the optical characteristics as the second retardation layer that contributes to the improvement of the viewing angle characteristics during black display, or the smaller the retardation is.

[Second retardation layer]
The liquid crystal display device of the present invention preferably has a second retardation layer formed from a composition containing a compound having a discotic structural unit. As described above, the second retardation layer cancels out the residual retardation caused by insufficient rise of liquid crystalline molecules in the vicinity of the substrate when a voltage is applied. The optical characteristics of the second retardation layer are not particularly limited, and can be determined based on the relationship with the optical characteristics of the liquid crystal cell. For the production of the second retardation layer, a discotic liquid crystalline compound is used. The molecules of the discotic liquid crystalline compound are preferably fixed in a state in which the molecules are oriented substantially perpendicular to the layer surface (average inclination angle in the range of 50 to 90 degrees) in the layer. 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 employed. Regarding the polymerization of the discotic liquid crystalline compound, those described in JP-A-8-27284 can be employed.

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

  Preferred specific examples of the discotic core (D), the divalent linking group (L), and the polymerizable group (P) in the formula (X) 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.

  The molecules of the discotic liquid crystalline compound are preferably oriented substantially uniformly in the layer, more preferably fixed in a substantially uniformly oriented state. More preferably, the liquid crystal compound is fixed. In the case of a discotic liquid crystalline compound having a polymerizable group, it is preferable to substantially align vertically. Substantially perpendicular means that the average angle (average inclination angle) between the disc surface of the discotic liquid crystal compound molecule and the layer surface is in the range of 50 ° to 90 °. The molecules of the discotic liquid crystalline compound may be obliquely aligned, or the tilt angle may be gradually changed (hybrid alignment). Even in the case of oblique orientation or hybrid orientation, the average inclination angle is preferably 50 ° to 90 °.

  The second retardation layer may be formed by applying a coating liquid containing at least one discotic liquid crystalline compound and, if desired, the following polymerization initiator and other additives on the alignment film. preferable. 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)
The aligned liquid crystal compound molecules are preferably fixed 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 (for example, those described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ethers (for example, those described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin compounds (for example, those described in US Pat. No. 2,722,512), polynuclear quinone compounds (for example, those described in US Pat. Nos. 3,046,127 and 2,951,758), triarylimidazole dimers And a combination of p-aminophenylketone (for example, those described in US Pat. No. 3,549,367), acridine and phenazine compounds (for example, those described in JP-A-60-105667, described in US Pat. No. 4,239,850) And oxadiazole compounds (eg, rice) In Japanese Patent No. 4212970).

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 second retardation layer is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm.

(Alignment film)
In order to align the liquid crystalline compound when forming the second retardation layer, it is preferable to use an alignment film. The alignment film may be an organic compound (preferably polymer) rubbing treatment, oblique deposition of an inorganic compound, formation of a layer having a microgroup, or an organic compound (eg, ω-triconic acid) by the Langmuir-Blodgett method (LB film). , Dioctadecyldimethylammonium chloride, methyl stearylate, etc.). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known. An alignment film formed by a polymer rubbing treatment is particularly preferable. The rubbing process is carried out by rubbing the surface of the polymer layer several times in a certain direction with paper or cloth. The type of polymer used for the alignment film can be determined according to the alignment (particularly the average tilt angle) of the liquid crystal compound. For example, in order to align the liquid crystalline compound horizontally, a polymer (ordinary alignment polymer) that does not decrease the surface energy of the alignment film is used. Specific types of polymers are described in various documents about liquid crystal cells or optical compensation films. Any of the alignment films preferably has a polymerizable group for the purpose of improving the adhesion between the liquid crystal compound and the transparent support. 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 aligning a liquid crystalline compound using an alignment film, the liquid crystalline compound is fixed in the aligned state to form a retardation layer, and only the retardation layer is formed on the polymer film (or transparent support). You may transcribe.

  The support for supporting the second retardation layer is not particularly limited, and various polymer films and the like can be used. For example, a triacetyl cellulose, norbornene resin, etc. are mentioned. When the first retardation layer is made of a polymer film, the first retardation layer may be used as a support for the second retardation layer. Further, the support for the second retardation layer may also serve as a protective film for the polarizing plate. The specific example of the material of the support in this embodiment is the same as the specific example of the material of the protective film of the polarizing plate, and will be described later.

[Polarizer]
It does not restrict | limit especially about the polarizing plate used for the liquid crystal display device of this invention. In general, a polarizing plate includes a polarizing film and a pair of protective films that sandwich the polarizing film. For example, a polarizing film made of a polyvinyl alcohol film or the like is dyed with iodine, stretched, and both surfaces thereof are laminated with a protective film. As described above, one or both of the pair of protective films may also serve as the first retardation layer. In an embodiment having the second retardation, one or both of the pair of protective films is It may also serve as a support for the second retardation layer, and may be the first retardation layer and the support for the second retardation layer.

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

  A transparent polymer film is preferably used as the protective film of the polarizing plate. For example, cellulose esters such as cellulose acetate, cellulose acetate butyrate, and cellulose propionate, polycarbonate, polyolefin, polystyrene, polyester, and the like can be used. Commercially available polymers (for norbornene polymers, Arton (manufactured by JSR), Zeonore (manufactured by Nippon Zeon), etc.) may be used.

  The retardation value of the protective film of the polarizing plate is preferably low. In an embodiment in which the absorption axis of the polarizing film and the slow axis of the protective film are not parallel, the polarizing axis and the slow axis of the protective film are obliquely shifted, particularly when the in-plane retardation value Re of the protective film is a certain value or more. Therefore, linearly polarized light changes to elliptically polarized light, which is not preferable. Further, in the ECB mode liquid crystal display device, since the liquid crystalline molecules are inclined and aligned on the substrate surface during halftone display, it is preferable that gradation inversion occurs when the retardation value Rth in the thickness direction is a certain value or more. It is said that there is no. That is, for example, the retardation value of the protective film is preferably ± 10 nm or less, and more preferably ± 5 nm or less at 632.8 nm. As the polymer film having a low retardation value, polyolefins such as cellulose triacetate, ZEONEX, ZEONOR (both manufactured by Nippon Zeon Co., Ltd.) and ARTON (manufactured by JSR Co., Ltd.) are preferably used. Other examples include non-birefringent optical resin materials as described in JP-A-8-110402 or JP-A-11-293116.

[Example 1]
With respect to the liquid crystal display device having the same configuration as in FIG. 1, the gradation inversion and the yellow tint during white display were measured.
The liquid crystal cell 18 has a cell gap of 3.28 um, and Δn · d of the liquid crystal layer is 280 nm. The liquid crystal material is a liquid crystal having positive dielectric anisotropy, refractive index anisotropy, Δn = 0.0854 (589 nm, 20 ° C.), Δε = + 8.5 (for example, MLC-9100 manufactured by Merck). . The liquid crystal alignment is homogeneous alignment. The absorption axes of the upper and lower polarizing plates 20a and 20b are approximately 45 ° with respect to the alignment direction (rubbing direction) of the liquid crystal cell 18, and the crossing angle between the absorption axes of the upper and lower polarizing plates 20a and 20b is approximately 90 °. The first retardation layer and the protective films 14a and 14b are films formed by biaxially stretching a cellulose acetate film, and Re (550) ≈0 and Rth (550) of each film are Different. The second retardation layers 16a and 16b are layers (Re (550) is 28 nm) formed from a composition containing a compound having a discotic structure.

FIG. 3 is a graph plotting b ^* when observed from a grayscale inversion angle and an oblique direction (angle horizontal polar angle 60 °) at the time of white display with respect to Rth (550) of the first retardation layer. Indicates.
From the graph shown in FIG. 3, in the configuration of FIG. 1, when Rth (550) of the first retardation layer satisfies the above formula (1) −280 nm <Rth (550) <50 nm, b ^It can be understood that the liquid crystal display device is an ECB mode with a small ^* (28 or less) and a large gradation inversion angle (35 or more).

[Example 2]
With respect to the liquid crystal display device having the same configuration as in FIG. 2, the gradation inversion and the yellow tint during white display were measured.
The liquid crystal cell 18 has a cell gap of 3.28 μm, and Δn · d of the liquid crystal layer is 280 nm. The liquid crystal material is a liquid crystal having positive dielectric anisotropy, refractive index anisotropy, Δn = 0.0854 (589 nm, 20 ° C.), Δε = + 8.5 (for example, MLC-9100 manufactured by Merck). . The liquid crystal alignment is homogeneous alignment. The absorption axes of the upper and lower polarizing plates 20a ′ and 20b ′ are approximately 45 ° with the alignment direction (rubbing direction) of the liquid crystal cell 18, and the crossing angle of the absorption axes of the upper and lower polarizing plates 20a ′ and 20b ′ is approximately 90 °. Nicole. The protective films 13a and 13b are commercially available cellulose acetate films “Fujitac” (manufactured by Fuji Film). 14a and 14b, which are the first retardation layer and the support for the second retardation layer, are films formed by biaxially stretching a cellulose acetate film, and Re (550) ≈0, Rth (550) is different from each other. The second retardation layers 16a and 16b are layers (Re (550) is 28 nm) formed from a composition containing a compound having a discotic structure.

FIG. 4 is a graph plotting b ^* when observed from a grayscale inversion angle and an oblique direction (angle horizontal polar angle 60 °) during white display with respect to Rth (550) of the first retardation layer. Indicates.
From the graph shown in FIG. 4, in the configuration of FIG. 2, when Rth (550) of the first retardation layer satisfies the formula (1) −280 nm <Rth (550) <50 nm, b ^It can be understood that the ECB mode liquid crystal display device has a small ^* (28 or less) and a large gradation inversion angle (35 or more).

5, the liquid crystal display device in which the first retardation layers 14a and 14b are cellulose acylate films having Rth (550) of −100 nm and different Re (550) values in the configuration of FIG. Is a graph plotting b ^* when observing from the gradation inversion angle and the oblique direction (angle horizontal polar angle 60 °) at the time of white display with respect to Re (550) of the first retardation layer. .
From the graph shown in FIG. 5, with the configuration of FIG. 2, b ^* is small (28 or less) and the gradation inversion angle is large (35 or more) regardless of Re (550) of the first retardation layer. It can be understood that an ECB mode liquid crystal display device is obtained.

In addition, as an example of preparation of the cellulose acylate film used for the first retardation layer in Examples 1 and 2, there are the following examples.
Cellulose acylate 1 was obtained according to the following synthesis example by reaction with the corresponding acid chloride using Aldrich cellulose acetate (acetyl substitution degree 2.45) as a starting material. In addition, you may use the cellulose acetate (Acetyl substitution degree 2.41 (brand name: L-70), 2.14 (brand name: LM-80)) by Daicel Corporation as a starting material.

-Synthesis of Asalonic Acid Chloride Weigh 106.1 g of Asaronic acid (2,4,5-trimethoxybenzoic acid) and 400 ml of toluene into a 1 L three-necked flask equipped with a mechanical stirrer, thermometer, condenser, and dropping funnel, and 80 ° C. And stirred. 40.1 mL of thionyl chloride was slowly added dropwise thereto, and after addition, the mixture was further stirred at 80 ° C. for 2 hours. After the reaction, when the reaction solvent was distilled off using an aspirator, a white solid was obtained. To the obtained white solid, 300 ml of hexane was added, and the mixture was vigorously stirred and dispersed. The white solid was separated by suction filtration, and further washed with a large amount of hexane three times. The obtained white solid was vacuum-dried at 60 ° C. for 4 hours to obtain the target asaronic acid chloride as a white powder. (115.3 g, 99% yield)

-Synthesis of cellulose acylate 1 Into a 1 L three-necked flask equipped with a mechanical stirrer, thermometer, condenser, and dropping funnel, 40 g of cellulose acetate (acetyl substitution degree 2.45) made by Aldrich, 46.0 ml of pyridine, and 300 ml of methylene chloride. Weighed out and stirred at room temperature. Here, 84.0 g of the synthesized asaronic acid chloride was divided into several portions and added in powder form. After the addition, the mixture was further stirred at room temperature for 6 hours. After the reaction, when the reaction solution was added to 4 L of methanol with vigorous stirring, a white pink solid was precipitated. The white peach colored solid was separated by suction filtration and washed three times with a large amount of methanol. The obtained white pink solid was dried at 60 ° C. overnight and then vacuum dried at 90 ° C. for 6 hours to obtain the target compound as a white pink powder. For the obtained sample, cellulose acylate 1, the degree of substitution was determined from the peak intensity of the carbonyl carbon in the acyl group in C ¹³ -NMR. As a result, cellulose acylate 1 containing a substituent having a polarizability anisotropy Δα defined by the formula (A) Δα = αx− (αy + αz) / 2 was 8.6 × 10 ⁻²⁴ cm ⁻³ was obtained. It was confirmed that the total acyl group substitution degree (PA) of this cellulose acylate 1 was 2.91 and the substitution degree of the aromatic acyl group was 0.46.

After the cellulose acylate 1 produced above was dried at 120 ° C. for 2 hours, the composition described below was put into a mixing tank, stirred while heating to dissolve each component, and a cellulose acylate solution was prepared. Prepared.
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Methylene chloride 261 parts by mass Methanol 39 parts by mass Triphenyl phosphate 5.9 parts by mass Biphenyl diphenyl phosphate 5.9 parts by mass Cellulose acylate 1 100 parts by mass Silicon dioxide fine particles 0.25 parts by mass ======== ============================

The mixing tank used was a 400-liter stainless steel tank having stirring blades and circulating cooling water around the outer periphery. The solvent and additives other than cellulose acylate were added and stirred to disperse or dissolve, and then the cellulose acylate was gradually added. After completion of the addition, the mixture was stirred at room temperature for 2 hours, swollen for 3 hours, and then stirred again.
For stirring, a dissolver type eccentric stirring shaft that stirs at a peripheral speed of 15 m / sec (shear stress 5 × 10 ⁴ kgf / m / sec ² ) and an anchor blade on the central axis and a peripheral speed of 1 m / sec. A stirring shaft that stirs at a sec (shear stress of 1 × 10 ⁴ kgf / m / sec ² ) was used. Swelling was carried out with the high speed stirring shaft stopped and the peripheral speed of the stirring shaft having anchor blades set at 0.5 m / sec.
The cellulose acylate solution thus obtained was filtered with a filter paper having an absolute filtration accuracy of 0.01 mm (# 63, manufactured by Toyo Filter Paper Co., Ltd.), and further filtered with an absolute filtration accuracy of 2.5 μm (FH025, Paul Corporation). To obtain a cellulose acylate solution.

The cellulose acylate solution was heated to 30 ° C., and cast on a mirror-surface stainless steel support having a band length of 60 m through a casting Giesser (described in JP-A-11-314233). The casting point was set on a roll set at 18 ° C., and the temperature of the other roll supporting the band was set at 35 ° C. Moreover, the space temperature of the whole casting part was set to 80 degreeC. The casting speed was 40 m / min and the coating width was 140 cm.
The cellulose acylate film which had been cast and rotated 50 cm before the cast part was peeled off from the band, and both ends of the film were gripped with a tenter. The tenter part at 110 ° C. was conveyed while the film width was gradually narrowed, and was released from the tenter so as to be 98% of the width when the film was gripped. After the clip traces at both ends of the film were cut off, the film was dried through a film at 135 ° C. to 140 ° C. consisting of a plurality of pass rolls so that the residual solvent amount was 0.2% or less. Thus, a long cellulose acetate film having a thickness of 90 μm was obtained.
About the obtained cellulose acylate film, using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the light incident angle dependency of retardation was measured, and the optical characteristics were calculated. , Rth was −100 nm, and Re was −3 nm.
In the preparation of the cellulose acylate film, various cellulose acylate films were prepared by changing the stretching conditions and the type of cellulose acylate used, and incorporated in a liquid crystal display device. The evaluation results shown in FIGS. Got.

It is a schematic sectional drawing of an example of the liquid crystal display device of this invention. It is a schematic sectional drawing of the other example of the liquid crystal display device of this invention. FIG. 6 is a graph showing the results of Example 1, in which b ^* and gradation inversion angle are plotted against Rth (550) of the first retardation layer. 10 is a graph showing the results of Example 2, in which b ^* and the gradation inversion angle are plotted against Rth (550) of the first retardation layer. 6 is a graph showing the results of Example 2, in which b ^* and gradation inversion angle are plotted against Re (550) of the first retardation layer.

Explanation of symbols

12a, 12b Polarizing films 13a, 13b Polarizing film protective layers 14a, 14b First retardation layer 16a, 16b Second retardation layer 18 Liquid crystal cell 20a, 20b Polarizing plate 20a ', 20b' Polarizing plate

Claims (8)

First and second substrates disposed opposite to each other and at least one of which has a transparent electrode; a liquid crystal molecule between the first and second substrates without a voltage applied, and a twist angle of 45 ° between the substrates A liquid crystal layer that is aligned substantially parallel to the substrate surface and in which a liquid crystal molecule is aligned in a normal direction of the substrate surface when a voltage is applied; and a liquid crystal layer that is disposed across the liquid crystal layer and has orthogonal polarization axes A liquid crystal display device comprising: a first retardation layer; and a first retardation layer between at least one of the first and second polarization layers and the liquid crystal layer. The retardation layer satisfies the following formula (1):
−280 nm <Rth (550) <50 nm (1)
However, Rth (λ) is retardation in the thickness direction with respect to light having a wavelength of λ nm. The liquid crystal display device according to claim 1, wherein the first retardation layer satisfies the following formula (2):
−200 nm ≦ Rth (550) ≦ 0 nm (2). The said 1st phase difference layer is arrange | positioned between the said 1st polarizing layer and the said liquid-crystal layer, It is a protective layer of the said 1st polarizing layer, The Claim 1 or 2 characterized by the above-mentioned. Liquid crystal display device. The liquid crystal layer further includes a second retardation layer formed of a composition containing a compound having a discotic structural unit between at least one of the first and second polarizing layers and the liquid crystal layer. The liquid crystal display device according to claim 1. The second retardation layer is disposed between the first retardation layer and the liquid crystal layer, and the first retardation layer satisfies the following formula (3): Item 4. A liquid crystal display device according to item 4:
Re (550 nm) <200 nm (3)
However, Re (λ) is an in-plane retardation for light having a wavelength of λ nm. The liquid crystal display device according to claim 5, wherein the first retardation layer satisfies the following formula (4):
−50 nm ≦ Re (550) ≦ 150 nm (4). From the film in which the first retardation layer contains a cellulose acylate containing a substituent having a polarizability anisotropy Δα represented by the following formula (A) of 2.5 × 10 ⁻²⁴ cm ⁻³ or more. The liquid crystal display device according to any one of claims 1 to 6:
Δα = αx− (αy + αz) / 2 (A)
In the formula, αx, αy, and αz are eigenvalues obtained after diagonalizing the polarizability tensor and satisfy αx ≧ αy ≧ αz. The liquid crystal display device according to claim 1, wherein the first retardation layer is a layer formed of a composition containing a compound having a rod-like liquid crystal structural unit.

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