JP4860333B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device, and in particular, an in-plane switching mode for performing display by applying a horizontal electric field to a horizontally aligned nematic liquid crystal, particularly a liquid crystal in a horizontal electric field switching mode called FFS (fringe field switching). The present invention relates to improvement of display device characteristics.

  Conventionally, as a liquid crystal display device, a so-called TN mode, in which a liquid crystal layer in which nematic liquid crystal is twisted and arranged between two orthogonal polarizing plates and an electric field is applied in a direction perpendicular to the substrate, has been widely used. ing. In this system, since the liquid crystal rises with respect to the substrate during black display, birefringence occurs due to liquid crystal molecules when viewed from an oblique direction, and light leakage occurs. To solve this problem, a system for optically compensating the liquid crystal cell and preventing this light leakage by using a film in which liquid crystal molecules are hybrid-aligned has been put into practical use. However, even if liquid crystal molecules are used, it is very difficult to completely optically compensate the liquid crystal cell without any problem, resulting in a problem that gradation reversal in the lower direction of the screen cannot be suppressed.

  In order to solve this problem, a liquid crystal display device using a so-called in-plane switching (IPS) mode in which a lateral electric field is applied to the liquid crystal, or a liquid crystal having a negative dielectric anisotropy is vertically aligned and formed in the panel. A vertical alignment (VA) mode in which the alignment is divided by the projected protrusions and slit electrodes has been proposed and put into practical use. In recent years, these panels have been developed not only for monitor applications but also for TV applications, and screen brightness has been greatly improved accordingly. For this reason, a slight light leakage in the diagonally oblique incident direction during black display, which has not been considered as a problem in these operation modes, has become apparent as a cause of a decrease in display quality.

As one means for improving the color tone and the viewing angle of black display, the arrangement of an optical compensation material having birefringence characteristics between the liquid crystal layer and the polarizing plate is also studied in the IPS mode. For example, by arranging a birefringent medium having optical axes orthogonal to each other to compensate for increase / decrease in liquid crystal layer retardation at the time of tilting, the white display or halftone display is obliquely viewed from the diagonal direction. It has been disclosed that coloring in direct viewing can be improved (see Patent Document 1).
In addition, a method using an optical compensation film made of a styrenic polymer having a negative intrinsic birefringence or a discotic liquid crystal compound (see Patent Documents 2, 3, and 4), or an optical axis as an optical compensation film with positive birefringence. Is a method of combining a film in the plane of the film with a film having a positive birefringence and an optical axis in the normal direction of the film (see Patent Document 5), biaxial optical compensation with a retardation of 1/2 wavelength A method using a sheet (see Patent Document 6), a method using a film having a negative retardation as a protective film of a polarizing plate, and providing an optical compensation layer having a positive retardation on this surface (see Patent Document 7) Proposed.
However, the fundamental problem of IPS is that the transmittance is low compared to other modes, and as a method for improving this, a conventional method using a metal electrode is changed to a transparent electrode (ITO). A method has been proposed (Patent Document 8). Further, fringe field switching (FFS) (Patent Documents 9 to 11) has been newly proposed as a method for improving the transmittance. However, even in this method, the display quality is not perfect, and improvements in viewing angle characteristics, gradation γ viewing angle characteristics, and the like are desired.

Japanese Patent Laid-Open No. 9-80424 Japanese Patent Laid-Open No. 10-54982 JP-A-11-202323 Japanese Patent Laid-Open No. 9-292522 JP 11-133408 A JP-A-11-305217 JP-A-10-307291 Japanese Patent No. 3465835 Japanese Patent No. 3114065 USP 6,388,726B Japanese Patent No. 3465835

Many of the proposed methods described above are methods that improve the viewing angle by canceling the birefringence anisotropy of the liquid crystal in the liquid crystal cell. There is a problem that light leakage based on a deviation from orthogonality cannot be solved sufficiently. In addition, even in a system that can compensate for this light leakage, it is very difficult to completely optically compensate the liquid crystal cell. Furthermore, in the optical compensation sheet for FFS mode liquid crystal cell that performs optical compensation with a stretched birefringent polymer film, it is necessary to use a plurality of films. As a result, the thickness of the optical compensation sheet is increased and the display device is made thinner. It is disadvantageous. Moreover, since an adhesive layer is used for lamination | stacking of a stretched film, the adhesive layer contracted by the temperature / humidity change, and defects, such as peeling and a curvature between films, may generate | occur | produce.
In addition, the FFS mode has a narrower electrode gap than the IPS mode, so the lateral electric field is non-uniform, and the switching is efficient because of the oblique switching without in-plane switching (IPS) due to the oblique electric field in the vicinity of the electrode. There is a problem of being bad. Furthermore, the IPS mode is excellent in γ viewing angle characteristics (color reproducibility in the tilt direction) because the liquid crystal molecules are switched substantially in-plane. However, the FFS is γ because the liquid crystal molecules are switched in the oblique and oblique directions. There was a problem of poor viewing angle characteristics.

  The present invention has been made in view of the above problems, and has an FFS mode liquid crystal display device with a simple configuration and improved not only in display quality but also in CR viewing angle characteristics, γ viewing angle characteristics, and display uniformity. It is an issue to provide.

Means for solving the above problems are as follows.
[1] A pair of first and second substrates disposed opposite to each other, and a pixel electrode formed on at least one of the pair of substrates via an insulating layer and capable of applying different potentials And a common electrode, a liquid crystal layer in which liquid crystal molecules are aligned substantially parallel to the substrate surface in a state in which no voltage is applied between the pair of substrates, and a pair of polarizing plates arranged with the liquid crystal layer interposed therebetween. , An FFS (fringe field switching) mode liquid crystal display device that controls the orientation of the liquid crystal layer by an electric field formed by the pixel electrode and the common electrode,
A liquid crystal display device, wherein the thickness of the insulating layer is different within one pixel or between sub-pixels.
[2] A pair of first and second substrates disposed opposite to each other, and a pixel electrode formed on at least one of the pair of substrates via an insulating layer and capable of applying different potentials And a common electrode, a liquid crystal layer in which liquid crystal molecules are aligned substantially parallel to the substrate surface in a state in which no voltage is applied between the pair of substrates, and a pair of polarizing plates arranged with the liquid crystal layer interposed therebetween. , An FFS (fringe field switching) mode liquid crystal display device that controls the orientation of the liquid crystal layer by an electric field formed by the pixel electrode and the common electrode,
2. A liquid crystal display device, wherein the dielectric constant of the insulating layer is different within one pixel or between sub-pixels.
[3] The polarizing plate has a polarizing film and a protective film provided on at least one surface of the polarizing film, and a slow axis of the protective film is an absorption axis of the polarizing film or an average of the liquid crystal layer The liquid crystal display device according to [1] or [2], wherein the protective film is a cellulose acylate film that intersects at least one of the orientation control directions and satisfies the following formulas (I) and (II):
(I) 0 ≦ Re (630) ≦ 10 and | Rth (630) | ≦ 25
(II) | Re (400) −Re (700) | ≦ 10 and | Rth (400) −Rth (700) | ≦ 35
In the above formulas (I) and (II), Re (λ) represents the front retardation value (nm) at the wavelength λnm, and Rth (λ) represents the retardation value (nm) in the film thickness direction at the wavelength λnm. To express.
[4] The polarizing plate has a polarizing film and a protective film provided on at least one surface of the polarizing film, and a slow axis of the protective film is an absorption axis of the polarizing film or an average of the liquid crystal layer Cellulose containing a compound that crosses at least one of the orientation control directions and the protective film reduces Rth such that Rth in the film thickness direction of the protective film satisfies the following formulas (III) and (IV): [1] or [2] liquid crystal display device which is an acylate film:
(III) (Rth (A) −Rth (0)) / A ≦ −1.0
(IV) 0.01 ≦ A ≦ 30
In formulas (III) and (IV), Rth (A) represents Rth (nm) of a protective film containing a compound that lowers Rth, and Rth (0) is the protective film, which lowers Rth. Rth (nm) of a film not containing the compound to be expressed is represented, and A represents the mass (%) of the compound that decreases Rht relative to the weight of the film raw material polymer.
[5] The liquid crystal display device according to any one of [1] to [4], wherein at least one optically anisotropic layer is disposed between the polarizing plate and the liquid crystal layer.
[6] The liquid crystal display device according to [5], wherein the optically anisotropic layer is made of a composition containing a rod-like liquid crystalline compound.
[7] The liquid crystal display device according to any one of [1] to [6], wherein the insulating layer also has a function as a selective wavelength filter.
[8] The liquid crystal display device according to any one of [1] to [7], wherein the insulating layer has a phase difference.
[9] The liquid crystal display device according to any one of [1] to [8], wherein the liquid crystal layer has negative dielectric anisotropy.

In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at a wavelength λ, respectively. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) is an arbitrary value within the film plane when Re (λ) is an in-plane slow axis (determined by KOBRA 21ADH or WR) and an inclined axis (rotation axis). The direction of the rotation axis is the rotation axis), and the light of wavelength λ nm is incident from each inclined direction in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction, and a total of 6 points are measured. KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed 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).

Ｒｔｈ＝（（ｎｘ＋ｎｙ）／２ − ｎｚ） ｘ 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表す。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。

Rth = ((nx + ny) / 2−nz) x d −−−- formula (2)
Note:
The above Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. In the formula, nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, and nz represents the refractive index in the direction perpendicular to nx and ny.

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

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

  In the present invention, a liquid crystal display device is formed by forming a plurality of domains showing different applied voltage-transmittance (VT) characteristics in one pixel or by making VT characteristics different for each RGB sub-pixel. An FFS mode liquid crystal display device having improved display quality, high luminance, wide viewing angle, and excellent gamma gradation viewing angle characteristics is provided.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.
Hereinafter, the configuration of 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 FFS mode liquid crystal display device of the present invention, showing an ON state in which a voltage equal to or higher than a threshold is applied. The FFS mode liquid crystal display device shown in FIG. 1 includes a pair of transparent substrates 12 and a liquid crystal layer including rod-like liquid crystalline molecules 14 disposed therebetween. A common electrode 16 and a plurality of pixel electrodes 18 are disposed on the opposing surface of one transparent substrate 12, and are disposed via insulating layers 20a and 20b therebetween. In the liquid crystal display device, insulating layers 20a and 20b having different thicknesses are formed in one pixel, and a low threshold domain a in which an insulating layer 20a having a relatively large thickness is disposed in one pixel. And a high threshold domain b in which an insulating layer 20b having a relatively small thickness is disposed. A pair of polarizing plates 22 are arranged outside the pair of substrates 12 with their absorption axes orthogonal to each other.

  The common electrode 16 may be an unpatterned electrode or a linear electrode. An electrode layer made of a transparent material is preferable, and an ITO electrode or the like is preferable. The pixel electrode 18 disposed in the upper layer is preferably linear, but may be any shape such as a mesh shape, a spiral shape, or a dot shape as long as the electric field from the common electrode 16 disposed in the lower layer can pass therethrough. A floating electrode having a neutral potential may be further added. 2A and 2B show a configuration example of the pixel electrode 18. The pixel electrode 18 may have a configuration in which a plurality of linear electrode layers are arranged in parallel as shown in FIG. 2A, or domains having different orientation directions are formed as shown in FIG. As possible, a configuration in which a plurality of linear electrode layers are arranged at ± θ (for example, θ is about 10 °) with respect to the rubbing direction may be employed. In order to rotate and switch rod-like liquid crystalline molecules in an inclined state, the interval between the linear electrode layers is preferably about 1 to 30 μm, more preferably 2 to 10 μm.

The insulating layers 20a and 20b may be made of an inorganic material such as an oxide such as SiO ₂ or a nitride such as SiN, or may be an organic material such as acrylic or epoxy. In order to form a plurality of domains having different threshold characteristics in one pixel, the difference in layer thickness between the insulating layers 20a and 20b is preferably about 0.1 to 4 μm, and preferably about 0.1 to 1.5 μm. It is more preferable that However, the preferred range of the layer thickness difference varies depending on the material of the insulating layer, and is not limited to this. Further, the method for forming insulating layers having different thicknesses is not particularly limited. For example, once an insulating layer having a uniform thickness is formed, an insulating layer having a different thickness can be formed in one pixel by performing processes such as photolithography and an etching process (dry, wet). . In addition, by using a technique of locally etching the gate insulating film (generally SiN) of the TFT forming the TFT, it differs from each other by changing the insulating film thickness between the counter electrode and the pixel electrode in the present invention. An insulating layer having a thickness may be formed.

  In the OFF state in which no voltage is applied, the rod-like liquid crystalline molecules 14 (assumed to have positive dielectric anisotropy here) in the liquid crystal layer are aligned films (not shown) formed on the opposing surface of the substrate 12. The molecules are aligned horizontally with the long axis direction of the molecules coincided with the rubbing direction. In the ON state (FIG. 1) in which a voltage equal to or higher than the threshold is applied, an electric field in the horizontal direction is formed with respect to the substrate 12 by the pixel electrode 18 composed of a plurality of linear electrode layers. The axial direction is aligned with the direction of the electric field. However, the alignment of the liquid crystalline molecules 14 located in the vicinity of the pixel electrode layer 16 is disturbed by the pixel electrode layer 16 and is aligned at a predetermined inclination angle with respect to the substrate plane. This has been a cause of deterioration in the γ viewing angle characteristics of the conventional FFS mode. Since the liquid crystal display device of FIG. 1 includes domains a and b having different threshold characteristics in one pixel, the tilt angle of the orientation of the rod-like liquid crystalline molecules 14 and the disturbance of the orientation direction of the long axis with respect to the electric field Is different for each domain. As a result, the change in the optical characteristics of the liquid crystal layer depending on the viewing direction is averaged, and the γ viewing angle characteristics are remarkably improved as compared with the conventional FFS mode liquid crystal display device.

  FIG. 3 is a schematic cross-sectional view of another example of the FFS mode liquid crystal display device of the present invention. 3 also shows an ON state in which a voltage equal to or higher than the threshold is applied, as in FIG. Moreover, the same number is attached | subjected about the same member as in FIG. 1, and although detailed description is abbreviate | omitted, the polarizing plate 22 was abbreviate | omitted in the figure. The same applies to FIGS. 4 to 7. The FFS mode liquid crystal display device shown in FIG. 3 is an example in which threshold characteristics between RGB pixels are different from each other. Specifically, in FIG. 3, since the R pixel 10R, the G pixel 10G, and the B pixel 10B include insulating layers 20r, 20g, and 20b having different thicknesses, respectively, the threshold characteristics are different from each other. Accordingly, in the same manner as described above, the inclination angle of the alignment of the rod-like liquid crystal molecules 14 in the ON state and the disturbance of the alignment direction of the major axis with respect to the electric field are different between the RGB pixels, and as a result, the liquid crystal layer depending on the observation direction The change in the optical characteristics is averaged, and the γ viewing angle characteristics are improved.

  FIG. 4 shows an example in which the insulating layer itself is used as the RGB layer of the color filter in the configuration of FIG. Specifically, the R pixel 10R ′, the G pixel 10G ′, and the B pixel 10B ′ each include insulating layers 20r ′, 20g ′, and 20b ′ having different thicknesses. The insulating layers 20r ', 20g', and 20b 'are colored layers colored R, G, and B, respectively, and constitute a color filter. According to the liquid crystal display device shown in FIG. 4, the same effects as in FIG. 3 can be obtained, and the formation of the color filter and the formation of the insulating layer can be performed simultaneously, which is advantageous in terms of productivity. The insulating layers 20r ', 20g', and 20b 'can be formed from a composition in which a coloring material such as a dye or a pigment is mixed with a polymer or the like.

  FIG. 5 is a schematic cross-sectional view of another example of the FFS mode liquid crystal display device of the present invention. FIG. 5 shows an example of a liquid crystal display device in which a plurality of domains having different threshold characteristics are formed in one pixel by changing the dielectric constant of the insulating layer. Specifically, in the liquid crystal display device shown in FIG. 4, insulating layers 20a ′ and 20b ′ having different dielectric constants are formed in one pixel, and an insulating layer having a relatively low dielectric constant is formed in one pixel. It includes a low threshold domain a ′ in which 20a ′ is disposed and a high threshold domain b ′ in which an insulating layer 20b ′ having a relatively high dielectric constant is disposed. Since one pixel includes the domain a ′ and the domain b ′ having different threshold characteristics, the tilt angle of the orientation of the rod-like liquid crystal molecules 14 in the ON state and the orientation direction of the major axis with respect to the electric field are the same as described above. The disturbance is different in each domain. As a result, the change in the optical characteristics of the liquid crystal layer depending on the viewing direction is averaged, and the γ viewing angle characteristics are improved.

  In addition, although there is no restriction | limiting in particular about the difference of the dielectric constant of the insulating layer contained in each domain, In order to set it as the domain from which a threshold value characteristic differs, the difference of the dielectric constant of the insulating layer contained in each domain is 2-2. It is preferably about 7. For example, examples of the high dielectric constant material include silicon nitride, silicon oxide, and titanium oxide, and examples of the low dielectric constant material include acrylic resin, methacrylic resin, and epoxy resin. It is not limited.

  FIG. 6 shows a schematic cross-sectional view of another example of the FFS mode liquid crystal display device of the present invention. This is an example in which threshold characteristics between RGB pixels are different from each other. Specifically, in FIG. 6, the R pixel 10R ″, the G pixel 10G ″, and the B pixel 10B ″ each include insulating layers 20r ″, 20g ″, and 20b ″ that have different dielectric constants. Are different from each other. Accordingly, in the same manner as described above, the inclination angle of the alignment of the rod-like liquid crystal molecules 14 in the ON state and the disturbance of the alignment direction of the major axis with respect to the electric field are different between the RGB pixels, and as a result, the liquid crystal layer depending on the observation direction The change in the optical characteristics is averaged, and the γ viewing angle characteristics are improved.

  FIG. 7 shows an example in which the insulating layer itself is used as the RGB layer of the color filter in the configuration of FIG. Specifically, the R pixel 10R ′ ″, the G pixel 10G ′ ″, and the B pixel 10B ′ ″ have different insulating layers 20r ′ ″, 20g ′ ″, and 20b ′ ″, respectively. Contains. The insulating layers 20r "", 20g "" and 20b "" are colored layers colored R, G and B, respectively, and constitute a color filter. According to the liquid crystal display device shown in FIG. 4, the same effects as in FIG. 6 can be obtained, and the formation of the color filter and the formation of the insulating layer can be performed simultaneously, which is advantageous in terms of productivity. The insulating layers 20r "", 20g "" and 20b "" can be formed, for example, from a composition in which color materials such as dyes and pigments are mixed with polymers having different dielectric constants.

  1 and 3 to 7 show the simplest configuration, but in any configuration, the same effect can be obtained even in a configuration including more domains having different threshold characteristics. . Further, the sub-pixel is not limited to the RGB sub-pixel, and the same effect can be obtained even in other forms such as the RGBW sub-pixel.

  The liquid crystal display device of the present invention is not limited to the configuration shown in FIGS. 1 to 7, and for example, a color filter may be disposed between the liquid crystal cell and the polarizing film. Further, as will be described later, another optical compensation film can be further 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 of the present invention may be disposed on the observation side, and the liquid crystal cell back surface or the lower substrate of the liquid crystal cell may be disposed. Install a reflective film on the inner surface. Of course, it is also possible to provide a front light using the light source on the liquid crystal cell observation side.

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

Hereinafter, materials and manufacturing methods used for various members of the liquid crystal display device of the present invention will be described.
[Liquid crystal layer]
The liquid crystal material used for the liquid crystal layer is not particularly limited as long as it is a nematic liquid crystal. As the value of the dielectric anisotropy Δε is larger, the driving voltage can be reduced, and as the refractive index anisotropy Δn is smaller, the thickness (gap) of the liquid crystal layer can be increased, and the liquid crystal sealing time is shortened. In addition, gap variation can be reduced. In the FFS mode, nematic liquid crystal having a positive dielectric anisotropy Δε is generally used. However, in the present invention, a negative nematic liquid crystal material may be used and is not particularly limited.

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

  In the liquid crystal display device of the present invention, the viewing angle of the liquid crystal display device is further improved by having a predetermined relationship between the slow axis of the protective film of the polarizing plate and the absorption axis of the polarizing film. Furthermore, the viewing angle is further improved by disposing an optical compensation film between the polarizing plate and the liquid crystal cell. The optical compensation film is not particularly limited and may have any configuration as long as it has optical compensation capability. Examples thereof include a birefringent polymer film and a laminate of an optical compensation film made of a transparent support and liquid crystal molecules formed on the transparent support. In the latter embodiment, the protective film on the side close to the liquid crystal layer of the polarizing plate may also serve as the support for the optical compensation film.

[Polarizer]
In the present invention, a polarizing plate having a polarizing film and a pair of protective films sandwiching the polarizing film or a protective film provided on at least one surface of the polarizing plate may be used. For example, a polarizing film obtained by dyeing a polarizing film made of a polyvinyl alcohol film or the like with iodine, stretching, and laminating both surfaces with a protective film can be used. The polarizing plate is disposed outside the liquid crystal cell. It is preferable that a pair of polarizing plates each including a polarizing film and a pair of protective films sandwiching the polarizing film are disposed with the liquid crystal cell interposed therebetween.

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

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

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

The polarizing plate used for the liquid crystal display device of the present invention has a polarizing film and a protective film provided on at least one surface of the polarizing film, and the protective film is either (1) or (2) below. It is preferable that the above condition is satisfied.
(1) Cellulose acylate film satisfying the following formulas (I) and (II) (I) 0 ≦ Re (630) ≦ 10 and | Rth (630) | ≦ 25
(II) | Re (400) −Re (700) | ≦ 10 and | Rth (400) −Rth (700) | ≦ 35.
(In the above formulas (I) and (II), Re (λ) represents the front retardation value (nm) at the wavelength λnm, and Rth (λ) is the retardation value in the film thickness direction at the wavelength λnm (nm). Represents.)
(2) Cellulose acylate film containing a compound that lowers Rth such that Rth in the film thickness direction of the protective film satisfies the following formulas (III) and (IV): (III) (Rth (A) -Rth (0 )) / A ≦ −1.0
(IV) 0.01 ≦ A ≦ 30.
(In the formulas (III) and (IV), Rth (A) represents Rth (nm) of a protective film containing a compound that reduces Rth, and Rth (0) is the protective film, and Rth is Rth (nm) of a film not containing the compound to be reduced is represented, and the weight (%) of the compound to reduce Rht relative to the weight of the film raw polymer is represented.
Here, the polymer of the film raw material refers to the raw material polymer of the main component constituting the film, and examples thereof include cellulose acylate.

Hereinafter, in the present invention, a cellulose acylate film preferable as a protective film for a polarizing plate will be described in detail.
Examples of cellulose as a cellulose acylate raw material include cotton linter and wood pulp (hardwood pulp, conifer pulp). Cellulose acylate obtained from any raw material cellulose can be used, and in some cases, a mixture may be used. . Detailed descriptions of these raw material celluloses can be found in, for example, Plastic Materials Course (17) Fibrous Resin (Maruzawa, Uda, Nikkan Kogyo Shimbun, published in 1970) and Invention Association Open Technical Report 2001-1745 (page 7). To page 8) can be used.

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

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

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

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

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

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

  When producing a cellulose acylate film to be used as the protective film, one kind or two or more different kinds are selected from the cellulose acylate in the above-mentioned range such as a substituent, a substitution degree, a polymerization degree, and a molecular weight distribution. It is preferable to do this.

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

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

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

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

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

  Although the specific example of the compound which reduces the optical anisotropy of the cellulose acylate film preferably used by this invention below is shown, it is not limited to these.

The 1st example of the compound which reduces optical anisotropy is a compound represented by following General formula (13).

上記一般式（１３）中、Ｒ¹¹はアルキル基又はアリール基を表し、Ｒ¹²及びＲ¹³は、それぞれ独立に、水素原子、アルキル基又はアリール基を表す。また、Ｒ¹¹、Ｒ¹²及びＲ¹³の炭素原子数の総和が１０以上であることが特に好ましい。Ｒ¹¹、Ｒ¹²及びＲ¹³は置換基を有していてもよく、置換基としてはフッ素原子、アルキル基、アリール基、アルコキシ基、スルホン基及びスルホンアミド基が好ましく、アルキル基、アリール基、アルコキシ基、スルホン基及びスルホンアミド基が特に好ましい。また、アルキル基は直鎖であっても、分岐であっても、環状であってもよく、炭素原子数１〜２５のものが好ましく、６〜２５のものがより好ましく、６〜２０のもの（例えば、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、ｔ−ブチル基、アミル基、イソアミル基、ｔ−アミル基、ヘキシル基、シクロヘキシル基、ヘプチル基、オクチル基、ビシクロオクチル基、ノニル基、アダマンチル基、デシル基、ｔ−オクチル基、ウンデシル基、ドデシル基、トリデシル基、テトラデシル基、ペンタデシル基、ヘキサデシル基、ヘプタデシル基、オクタデシル基、ノナデシル基、ジデシル基）が特に好ましい。アリール基としては炭素原子数が６〜３０のものが好ましく、６〜２４のもの（例えば、フェニル基、ビフェニル基、テルフェニル基、ナフチル基、ビナフチル基、トリフェニルフェニル基）が特に好ましい。
以下に、一般式（１３）で表される化合物の好ましい例を下記に示すが、これらの具体例に限定されるものではない。尚、化合物中、Ｐｒⁱはイソプロピル基を意味する（以下、同じ）。

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

一般式（１８）中、Ｒ¹⁴はアルキル基又はアリール基を表し、Ｒ¹⁵及びＲ¹⁶はそれぞれ独立に水素原子、アルキル基又はアリール基を表す。
Ｒ¹⁴は、フェニル基又は、環状アルキル基が好ましい。Ｒ¹⁵及びＲ¹⁶は、それぞれ、フェニル基又はアルキル基が好ましい。アルキル基としては、環状アルキル基及び直鎖のアルキル基のいずれも好ましい。
これらの基は、置換基を有していてもよく、置換基としてはフッ素原子、アルキル基、アリール基、アルコキシ基、スルホン基及びスルホンアミド基が好ましく、アルキル基、アリール基、アルコキシ基、スルホン基及びスルホンアミド基が特に好ましい。
一般式（１８）で表される化合物は、より好ましくは一般式（１９）で表される化合物である。

In General Formula (18), R ¹⁴ represents an alkyl group or an aryl group, and R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom, an alkyl group, or an aryl group.
R ¹⁴ is preferably a phenyl group or a cyclic alkyl group. R ¹⁵ and R ¹⁶ are each preferably a phenyl group or an alkyl group. As the alkyl group, both a cyclic alkyl group and a linear alkyl group are preferable.
These groups may have a substituent, and the substituent is preferably a fluorine atom, an alkyl group, an aryl group, an alkoxy group, a sulfone group, or a sulfonamide group, and an alkyl group, an aryl group, an alkoxy group, a sulfone group. Groups and sulfonamido groups are particularly preferred.
The compound represented by the general formula (18) is more preferably a compound represented by the general formula (19).

一般式（１９）中、Ｒ¹¹⁴、Ｒ¹¹⁵及びＲ¹¹⁶はそれぞれ独立にアルキル基又はアリール基を表す。アルキル基は、環状アルキル基及び直鎖のアルキル基のいずれも好ましいく、アリール基はフェニル基が好ましい。
以下に、一般式（１８）（及び一般式（１９））で表される化合物の好ましい例を下記に示すが、これらの具体例に限定されるものではない。尚、化合物中、Ｂｕⁱはイソブチル基を意味する。

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

A compound for reducing the wavelength dispersion of the cellulose acylate film (hereinafter also referred to as a wavelength dispersion adjusting agent) will be described. In order to improve the Rth wavelength dispersion of the cellulose acylate film, a compound that reduces the Rth wavelength dispersion ΔRth = | Rth (400) −Rth (700) | represented by the following formula (VII): It is preferable to contain at least one kind within a range satisfying the following formulas (V) and (VI).
(VII) ΔRth = | Rth (400) −Rth (700) |
(V) (ΔRth (B) −ΔRth (0)) / B ≦ −2.0
(VI) 0.01 ≦ B ≦ 30
The above formulas (V) and (VI) are: (V−I) (ΔRth (B) −ΔRth (0)) / B ≦ −3.0
(VI-I) 0.05 ≦ B ≦ 25
More preferably,
(V-II) (ΔRth (B) −ΔRth (0)) / B ≦ −4.0
(VI-II) 0.1 ≦ B ≦ 20
More preferably.
The above-mentioned wavelength dispersion adjusting agent has at least a compound having absorption in the ultraviolet region of 200 to 400 nm and reducing | Re (400) -Re (700) | and | Rth (400) -Rth (700) | The wavelength dispersion of Re and Rth of the cellulose acylate film was adjusted by including 0.01 to 30% by weight of one type of cellulose acylate solids. By adding 0.1 to 30% by weight as the addition amount, wavelength dispersion of Re and Rth of the cellulose acylate film was adjusted.

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

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

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

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

  It is preferable that the wavelength dispersion adjusting agent does not volatilize during the dope casting and drying process for producing the cellulose acylate film.

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

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

  As the benzotriazole-based compound, those represented by the following general formula (101) are preferably used as a wavelength dispersion adjusting agent.

Formula (101)
Q ¹¹ -Q ¹² -OH
(In the general formula (101), Q ¹¹ represents a nitrogen-containing aromatic heterocycle, and Q ¹² represents an aromatic ring.)

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

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

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

General formula (101-A)

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

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

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

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

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

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

一般式（１０１−Ｂ）中、Ｒ¹、Ｒ³、Ｒ⁶及びＲ⁷は一般式（１０１−Ａ）におけるそれらと同義であり、また好ましい範囲も同様である。 General formula (101-B)

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

  Specific examples of the compound represented by the general formula (101) are shown below, but are not limited to the following specific examples.

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

  In addition, as the benzophenone compound which is one of the wavelength dispersion adjusting agents used in the present invention, those represented by the general formula (102) are preferably used.

（一般式（１０２）中、Ｑ¹及びＱ²は、それぞれ、芳香族環を表す。ＸはＮＲ（Ｒは水素原子又は置換基を表す。）、酸素原子又は硫黄原子を表す。） General formula (102)

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

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

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

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

Formula (102-A)

(In the general formula (102-A), R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ each independently represent a hydrogen atom or a substituent.)

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

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

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

Preferably a hydrogen atom R ^27, an alkyl group, an alkenyl group, an alkynyl group, an aryl groups, an amino group, an alkoxy group, an aryloxy group, hydroxy group, halogen atom, more preferably a hydrogen atom, an alkyl group having 1 to 20 carbon atoms , An amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and a hydroxy group, more preferably a hydrogen atom and an alkyl group having 1 to 20 carbon atoms (preferably A carbon number of 1 to 12, more preferably a carbon number of 1 to 8, and still more preferably a methyl group, and 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 the general formula (102-B), R ¹⁰ represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, or an aryl group.)

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

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

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

（一般式（１０３）中、Ｑ³¹及びＱ³²はそれぞれ独立に芳香族環を表す。Ｘ³¹及びＸ³²はそれぞれ、水素原子又は置換基を表し、少なくともどちらか１つはシアノ基、カルボニル基、スルホニル基、芳香族ヘテロ環を表す。）
Ｑ³¹及びＱ³²で表される芳香族環は芳香族炭化水素環でも芳香族ヘテロ環でもよい。また、これらは単環であってもよいし、さらに他の環と縮合環を形成してもよい。 General formula (103)

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

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

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

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

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

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

  Preferred as the general formula (103) is a compound represented by the following general formula (103-A).

（一般式（１０３−Ａ）中、Ｒ³¹、Ｒ³²、Ｒ³³、Ｒ³⁴、Ｒ³⁵、Ｒ³⁶、Ｒ³⁷、Ｒ³⁸、Ｒ³⁹及びＲ³⁰はそれぞれ独立に水素原子又は置換基を表す。Ｘ³¹及びＸ³²は一般式（１０３）におけるそれらと同義であり、また好ましい範囲も同様である。） General formula (103-A)

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

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

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

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

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

General formula (103-B)

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

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

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

General formula (103-C)

(In the general formula (103-C), R ³³ and R ³⁸ have the same meanings as those in the general formula (103-A), and the preferred range is also the same. R ³⁰² is an alkyl having 1 to 20 carbon atoms. Represents a group.)

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

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

  The compound represented by the general formula (103) 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 shown below, but are not limited to the following specific examples.

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

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

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

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

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

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

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

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

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

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

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

  The dissolution method used when preparing the cellulose acylate solution (dope) is not particularly limited, and it may be room temperature, or a cooling dissolution method or a high temperature dissolution method, or a combination thereof. Regarding the preparation of the cellulose acylate solution in the present invention, and further the steps of solution concentration and filtration associated with the dissolution step, the Technical Report of the Japan Society of Invention (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention) The manufacturing process described in detail on pages 22 to 25 is preferably used.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[Optical compensation film]
The optical compensation film is used in a liquid crystal display device to eliminate image coloring or to expand a viewing angle. In the present invention, as described above, the optical compensation film is not an essential member. For example, in an aspect in which birefringence is added to one or both of the pair of protective films of the polarizing plate to function as the optical compensation film. It is not necessary to provide a separate optical compensation film.

Examples of liquid crystalline compounds that form the optical compensation film include rod-like liquid crystalline molecules and discotic liquid crystalline molecules. The rod-like liquid crystal molecule and the discotic liquid crystal molecule (discotic liquid crystal compound) may be a high-molecular liquid crystal or a low-molecular liquid crystal, and further include those in which the low-molecular liquid crystal is cross-linked and no longer exhibits liquid crystallinity.
When a rod-like liquid crystalline compound is used to produce the optically anisotropic layer, the orientation direction of the rod-like liquid crystalline molecules may be perpendicular, parallel, or hybrid orientation to the protective film surface. In the case of vertical and parallel, it is preferable that the average direction of the axis projected from the major axis on the support surface is parallel to the orientation axis. Further, when a discotic liquid crystalline compound is used for the production of the optically anisotropic layer, the average direction of the axis of the discotic liquid crystalline molecule projected on the support surface is parallel to the alignment axis. Is preferred. Further, the hybrid orientation described later in which the angle (inclination angle) formed by the disk surface and the layer plane changes in the depth direction may be used.
《Bar-shaped liquid crystalline molecules》
Examples of rod-like liquid crystalline molecules include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.
The rod-like liquid crystalline molecule includes a metal complex. In addition, a liquid crystal polymer containing a rod-like liquid crystalline molecule in a repeating unit can also be used as the rod-like liquid crystalline molecule. In other words, the rod-like liquid crystal molecule may be bonded to a (liquid crystal) polymer.
For rod-like liquid crystalline molecules, see Chapter 4, Chapter 7 and Chapter 11 in the Chemistry of the Quarterly Chemical Review Vol. 22 Liquid Crystal Chemistry (1994) edited by the Chemical Society of Japan, and the 142nd Committee of the Japan Society for the Promotion of Science. Described in Chapter 3. The birefringence of the rod-like liquid crystal molecule is preferably in the range of 0.001 to 0.7.

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

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

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

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

  These liquid crystalline compounds are substantially vertically aligned with the substrate surface in the optical compensation film. Here, “substantially on the substrate surface” means, for example, being parallel to the substrate surface or shifted by ± 5 degrees. Further, it is preferably substantially uniformly oriented, more preferably fixed in a substantially uniformly oriented state, and most preferably the liquid crystalline compound is fixed by a polymerization reaction. . 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 tilt angle) between the disc surface of the discotic liquid crystal compound and the surface of the optical compensation film is in the range of 70 to 90 degrees.

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

[Fixation of alignment state of liquid crystalline compounds]
The aligned liquid crystalline compound is 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 photopolymerization initiators include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substitution. Aromatic acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenyl ketone (US Patent No. 3549367), acridine and phenazine compounds (JP-A-60-105667, US Pat. No. 4,239,850) and oxadiazole compounds (US Pat. No. 4,221,970) Is included.

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 optical compensation film is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm.

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

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

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

  For uniform alignment of the discotic liquid crystalline compound, the vertical alignment film is rubbed to control the alignment direction. The rubbing treatment is performed by rubbing the surface of the polymer layer several times in a certain direction with paper or cloth. On the other hand, it is preferable not to perform rubbing treatment for the alignment of the rod-like liquid crystalline compound. In any alignment film, the alignment film 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.

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

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

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

The in-plane retardation (Re) of the entire optical compensation film is preferably 20 to 200 nm. The thickness direction retardation (Rth) of the entire optical compensation film is preferably 50 to 500 nm. The in-plane retardation (Re) and the thickness direction retardation (Rth) of the optical compensation film are defined by the following equations, respectively. Where d _2a is the thickness (μm) of the optical compensation film.
Re = (nx−ny) × d _2a
Rth = ((nx + ny) / 2−nz) × d _2a
(Where d _2a (nm) is the thickness of the entire optical compensation film, nx and ny (where ny <nx) is the in-plane main average refractive index, and nx is the main average refractive index in the thickness direction) Nx, ny and nz are orthogonal to each other.)

  Examples of the optical compensation film other than the discotic compound include an optical compensation film made of a stretched birefringent polymer film, and an optical compensation film having an optical compensation film formed from a low-molecular or high-molecular liquid crystalline compound on a transparent support. However, any of them can be used in the present invention. In addition, an optical compensation film having a laminated structure can be used, including the case of a laminate of two optical compensation films. Regarding the optical compensation film having a laminated structure, in consideration of the thickness, an optical compensation film made of a coating-type laminate is preferable to an optical compensation film made of a laminate of stretched polymer films.

  The polymer film used as the optical compensation film may be a stretched polymer film or a combination of a coating type polymer layer and a polymer film. As a material for the polymer film, a synthetic polymer (eg, polycarbonate, polysulfone, polyethersulfone, polyacrylate, polymethacrylate, norbornene resin, triacetylcellulose) is generally used. These polymer films preferably have the same longitudinal direction (roll TO roll) in order to improve productivity and shape stability when temperature and humidity change.

  Since the liquid crystalline compound has various alignment forms, the optical compensation film made of the liquid crystalline compound exhibits a desired optical property by a single layer or a laminate of a plurality of layers. That is, the optical compensation film may be an embodiment comprising a support and one or more optical compensation films formed on the support. The retardation of the optical compensation film as a whole can be adjusted by the optical anisotropy of the optical compensation film. Liquid crystal compounds can be classified into rod-like liquid crystal compounds and discotic liquid crystal compounds based on their shapes. Furthermore, there are low molecular weight and high molecular weight types, respectively, and both can be used. The optical compensation film produced using the liquid crystal compound preferably uses a rod-like liquid crystal compound or a discotic liquid crystal compound as the liquid crystal compound, and more preferably uses a discotic liquid crystal compound having a polymerizable group. preferable.

  The liquid crystal display device of the present invention is an aspect in which the liquid crystal material is aligned substantially parallel during black display, and displays black by aligning liquid crystal molecules in parallel with the substrate surface in the absence of applied voltage. In these embodiments, by using the above-described cellulose acylate film as a protective film, it contributes to improvement in color tone, expansion of viewing angle, and improvement in contrast. In this aspect, among the protective films for the polarizing plates above and below the liquid crystal cell, the cellulose acylate that can be used in the present invention for the protective film (the protective film on the cell side) disposed between the liquid crystal cell and the polarizing plate. A polarizing plate using a rate film is preferably used on at least one side. In the FFS method, a single protective film made of the cellulose acylate film is disposed between the protective film of the lower polarizing film and the liquid crystal layer, and between the upper polarizing film and the liquid crystal layer, thereby leaking light during black display. This is preferable because the reduction in color and the coloring in the viewing angle direction are eliminated.

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

[Example 1]
<Fabrication of FFS mode liquid crystal cell>
An FFS mode liquid crystal display device having the same configuration as that shown in FIG. 1 was produced.
Specifically, a common electrode ITO was formed on a glass substrate having a single color filter, and an acrylic organic insulating film (or an inorganic film such as SIN) was formed thereon. Insulating film
Low threshold domain and high threshold domain having insulating films with different thicknesses of about 0.5μm in one pixel by etching using photolithography (may be done at the same time as active device manufacturing process such as TFT) Formed. A pixel electrode (line width 5 μm, electrode gap 5 μm) provided with slits was formed thereon. Further, a polyimide film was provided thereon as an alignment film, and a rubbing process was performed. A polyimide film was provided on one surface of a separately prepared glass substrate, and a rubbing treatment was performed to obtain an alignment film. The two glass substrates are stacked and bonded so that the alignment films face each other, the distance between the substrates (gap; d) is 4.1 μm, and the rubbing directions of the two glass substrates are parallel. A nematic liquid crystal composition having a refractive index anisotropy (Δn) of 0.098 and a dielectric anisotropy (Δε) of 4.5 was enclosed. The value of d · Δn of the liquid crystal layer was 400 nm.

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

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

(Preparation of additive solution)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution. As the compound (optical anisotropy reducing agent) for reducing optical anisotropy and the wavelength dispersion adjusting agent, those shown in Table 1 below were used.
Additive solution composition Compound that lowers optical anisotropy 49.3 parts by weight Wavelength dispersion adjusting agent 7.6 parts by weight Methylene chloride (first solvent) 58.4 parts by weight Methanol (second solvent) 8.7 parts by weight Cellulose Acetate solution D 12.8 parts by mass

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

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

<Fabrication of FFS mode liquid crystal display device>
The optically anisotropic film R1 was laminated with an adhesive so as to be on the viewing side surface of the FFS mode liquid crystal cell produced above. On the other hand, a polarizing plate was laminated with an adhesive on the opposite surface of the liquid crystal cell to produce a liquid crystal display device. The polarizing plate on the viewing side was laminated so that the extraordinary refractive index direction of the liquid crystal composition in the liquid crystal cell and the absorption axis of the polarizing plate were orthogonal when no voltage was applied. Further, the absorption axis of the polarizing plate and the slow axis of the optically anisotropic film R1 were arranged to be orthogonal to each other.

<Evaluation>
With respect to the manufactured liquid crystal display device, the contrast ratio in a direction with an inclination of 70 ° from the normal direction in an azimuth direction of 45 ° with respect to the optical axis of the orthogonal polarizing plate was measured. Moreover, when the in-plane unevenness at the time of black display of this liquid crystal display device was confirmed visually, the unevenness by the dispersion | variation in retardation of protective films, such as a linear form, was hardly observed. In addition, almost no deterioration in polarization performance was observed. Further, the change in transmittance depending on the observation direction was examined, but the same transmittance as that in frontal observation was obtained in any direction.
The same effect can be obtained by forming the domain shown in FIG. 5, that is, by forming domains having different dielectric constants of the insulating layers.

  Moreover, when it evaluated similarly using a commercially available polarizing plate as a polarizing plate, the same gamma viewing angle characteristic as Example 1 was shown. However, Example 1 using the polarizing plate having the low retardation protective film was superior in that it had less coloring depending on the viewing direction. In addition, when both liquid crystal display devices were placed in a condition of 0 ° C. and 95% RH for 200 hours and then in-plane unevenness of black display was visually confirmed, the liquid crystal display device of Example 1 was found to be a protective film, The unevenness presumed to be caused by the liquid crystal panel was hardly observed, and the polarization performance was hardly deteriorated.

[Example 2]
An FFS mode liquid crystal display device having a configuration similar to that shown in FIG. 3 was manufactured. Specifically, the insulating film thickness is changed between the RGB sub-pixels (the film thickness of the insulating layer in the R pixel is 4.8 μm, the film thickness of the insulating layer in the G pixel is 4.1 μm, the insulating layer in the B pixel) The threshold characteristics were made different for each RGB subpixel unit. Other than that was carried out similarly to Example 1, and produced the liquid crystal display device.
When this liquid crystal display device was evaluated in the same manner as described above, it exhibited excellent γ viewing angle characteristics as in Example 1. Furthermore, when a liquid crystal display device using a commercially available polarizing plate was prepared and the performance thereof was compared in the same manner as described above, the liquid crystal display device of Example 2 using a polarizing plate having a low retardation protective film was better. The coloration depending on the viewing direction was less and excellent. Further, after both of the liquid crystal display devices were placed in a condition of 0 ° C. and 95% RH for 200 hours, the in-plane unevenness of black display was visually confirmed. The unevenness presumed to be caused by the liquid crystal panel was hardly observed, and the polarization performance was hardly deteriorated.
Note that the same effect can be obtained with the configuration shown in FIG.

[Example 3]
An FFS mode liquid crystal display device having a configuration similar to that shown in FIG. 4 was manufactured. Specifically, in Example 2 described above, the insulating films in the RGB pixels were colored in R, G, and B colors to function as color filters, respectively, and the color filter manufacturing process was omitted. Other than that was carried out similarly to Example 2, and produced the liquid crystal display device.
When this liquid crystal display device was evaluated in the same manner as described above, it exhibited excellent γ viewing angle characteristics as in Examples 1 and 2. Furthermore, when a liquid crystal display device using a commercially available polarizing plate was prepared and the performance was compared in the same manner as described above, the liquid crystal display device of Example 3 using a polarizing plate having a low retardation protective film was better. The coloration depending on the viewing direction was less and excellent. In addition, both of the liquid crystal display devices were placed in a condition of 0 ° C. and 95% RH for 200 hours, and then the in-plane unevenness of black display was visually confirmed. The unevenness presumed to be caused by the liquid crystal panel was hardly observed, and the polarization performance was hardly deteriorated.
Note that the same effect can be obtained with the configuration shown in FIG. 7, that is, the configuration in which the dielectric constant of the insulating layer differs between the pixels.

[Example 4]
About Examples 1-3, the liquid crystal display device of the same structure was respectively produced except having used the negative nematic liquid crystal material instead of the nematic liquid crystal material with positive dielectric anisotropy.
When evaluated in the same manner, it was possible to display an image with a high transmittance during white display as compared with a liquid crystal display device using a nematic liquid crystal material having a positive dielectric anisotropy.

  According to the present invention, it is possible to provide an FFS mode liquid crystal display device with a simple configuration and improved not only in display quality but also in CR viewing angle characteristics, γ viewing angle characteristics, and display uniformity.

It is a cross-sectional schematic diagram which shows a structure of an example of the liquid crystal display device of the FFS mode of this invention. It is a plane schematic diagram which shows the electrode structure which can be used for the liquid crystal display device of the FFS mode of this invention of this invention. It is a cross-sectional schematic diagram which shows a structure of an example of the liquid crystal display device of the FFS mode of this invention. It is a cross-sectional schematic diagram which shows a structure of an example of the liquid crystal display device of the FFS mode of this invention. It is a cross-sectional schematic diagram which shows a structure of an example of the liquid crystal display device of the FFS mode of this invention. It is a cross-sectional schematic diagram which shows a structure of an example of the liquid crystal display device of the FFS mode of this invention. It is a cross-sectional schematic diagram which shows a structure of an example of the liquid crystal display device of the FFS mode of this invention.

Explanation of symbols

12 Transparent substrate 14 Liquid crystalline molecule 16 Common electrode 18 Pixel electrode 20a, 20b Insulating layer 20a ′, 20b ′ Insulating layer 20r, 20g, 20b Insulating layer 20r ′, 20g ′, 20b ′ Insulating layer 20r ″, 20g ″, 20b ″ insulating layer 20r ′ ″, 20g ′ ″, 20b ′ ″ insulating layer 22 polarizing plate 10R, 10R ′, 10R ″, 10R ′ ″ R pixel 10G, 10G ′, 10G ″, 10G ′ '' G pixel 10B, 10B ', 10B ", 10B''' B pixel

Claims (8)

A pair of first and second substrates disposed opposite to each other, a pixel electrode and a common electrode formed on at least one of the pair of substrates via an insulating layer and capable of applying different potentials A liquid crystal layer in which liquid crystal molecules are aligned substantially parallel to the substrate surface in a state in which no voltage is applied between the pair of substrates, and a pair of polarizing plates arranged with the liquid crystal layer interposed therebetween, An FFS (fringe field switching) mode transmissive liquid crystal display device that controls the orientation of a liquid crystal layer by an electric field formed by an electrode and a common electrode,
A liquid crystal display device, wherein the thickness of the insulating layer is different within one pixel or between sub-pixels. A pair of first and second substrates disposed opposite to each other, a pixel electrode and a common electrode formed on at least one of the pair of substrates via an insulating layer and capable of applying different potentials A liquid crystal layer in which liquid crystal molecules are aligned substantially parallel to the substrate surface in a state in which no voltage is applied between the pair of substrates, and a pair of polarizing plates arranged with the liquid crystal layer interposed therebetween, An FFS (fringe field switching) mode transmissive liquid crystal display device that controls the orientation of a liquid crystal layer by an electric field formed by an electrode and a common electrode,
2. A liquid crystal display device, wherein the dielectric constant of the insulating layer is different within one pixel or between sub-pixels. The polarizing plate, and a protective film provided on at least one surface of the polarizing film and the polarizing film, before Symbol protective film is a cellulose acylate film satisfying the following formulas (I) and (II) according to Item 3. The liquid crystal display device according to item 1 or 2:
(I) 0 ≦ | Re (630) | ≦ 10 and 0 ≦ | Rth (630) | ≦ 25
(II) | Re (400) −Re (700) | ≦ 10 and | Rth (400) −Rth (700) | ≦ 35
In the above formulas (I) and (II), Re (λ) represents the front retardation value (nm) at the wavelength λnm, and Rth (λ) represents the retardation value (nm) in the film thickness direction at the wavelength λnm. To express. The polarizing plate, and a protective film provided on at least one surface of the polarizing film and the polarizing film, before Symbol protective film, Rth in the film thickness direction of the protective film satisfies the following formula (III) and ( The liquid crystal display device according to claim 1 or 2, which is a cellulose acylate film containing a compound that reduces Rth so as to satisfy IV).
(III) (Rth (A) −Rth (0)) / A ≦ −1.0
(IV) 0.01 ≦ A ≦ 30
In formulas (III) and (IV), Rth (A) represents Rth (nm) of a protective film containing a compound that lowers Rth, and Rth (0) is the protective film, which lowers Rth. is to represent the Rth of the film not containing the compound (nm), a represents the mass of the compound that reduces the R th for the weight of the film raw material polymer (%). The liquid crystal display device according to claim 1, wherein at least one optically anisotropic layer is disposed between the polarizing plate and the liquid crystal layer. The liquid crystal display device according to claim 5, wherein the optically anisotropic layer is made of a composition containing a rod-like liquid crystalline compound. The liquid crystal display device according to claim 1, wherein the insulating layer is a selective wavelength filter having different thicknesses between regions having different selective wavelengths. The liquid crystal display device according to claim 1, wherein the insulating layer has a phase difference.

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