JP2006071963A - Polarizing plate integrated optical compensation film and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an IPS (In-Plane Switching) type liquid crystal display device which is improved not only in display quality but also in a viewing angle characteristic with a simple constitution. <P>SOLUTION: The liquid crystal display device comprises at least a first polarizing film, a first retardation region, a second retardation region, a liquid crystal cell which holds a liquid crystal layer between a pair of substrates and a second polarizing film, wherein liquid crystal molecules align substantially in parallel with respect to the surface of a pair of the substrates upon black display. Retardation Re in the plane of the first retardation region is 20 nm to 150 nm, the value Nz of the first retardation region is 1.5 to 7, retardation Rth in the thickness direction of the second retardation region is -80 nm to -400 nm, at least one side of the first retardation region and the second retardation region is a film including cellulose acetate propionate or cellulose propionate and the transmission axis of the first polarizing film is parallel to the direction of the slow axis of liquid crystal molecules upon black display. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and more particularly to an in-plane switching mode liquid crystal display device that performs display by applying a horizontal electric field to liquid crystal molecules aligned in a horizontal direction. The present invention also relates to a polarizing plate integrated optical compensation film that contributes to optical compensation of a liquid crystal display device, particularly an in-plane switching mode liquid crystal display device.

  As a liquid crystal display device, a so-called TN mode is widely used in which a liquid crystal layer in which nematic liquid crystal is twisted is sandwiched between two orthogonal polarizing plates and an electric field is applied in a direction perpendicular to the substrate. 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 such a 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 in the panel. A vertical alignment (VA) mode in which alignment is divided by 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, slight light leakage in the diagonally oblique incidence direction during black display, which has not been considered as a problem in these operation modes, has become apparent as a cause of deterioration 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 an optical axis orthogonal to each other to compensate for the increase / decrease in retardation of the liquid crystal layer during tilting, a white display or a halftone display is diagonally arranged between the substrate and the polarizing plate. It is disclosed that coloring can be improved when viewing directly from (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 crystalline compound (see Patent Documents 2, 3, and 4), or an optical axis having a positive birefringence as an optical compensation film. A film in which the film is in the plane of the film and 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 half 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.

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

  However, many of the proposed methods are methods that improve the viewing angle by canceling the birefringence anisotropy of the liquid crystal in the liquid crystal cell, so the polarization axis crossing angle when the orthogonal polarizing plate is viewed from an oblique direction. There is a problem that the light leakage based on the deviation from orthogonality cannot be solved sufficiently. Even in a system that can compensate for this light leakage, it is very difficult to completely optically compensate the liquid crystal cell without any problem. Furthermore, in the optical compensation sheet for an IPS 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. In addition, since an adhesive layer is used for laminating stretched films, the adhesive layer contracts due to changes in temperature and humidity, and defects such as peeling and warping between films may occur.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an IPS liquid crystal display device with a simple structure and not only display quality but also significantly improved viewing angle characteristics. Another object of the present invention is to provide a polarizing plate integrated optical compensation film that contributes to the improvement of viewing angle characteristics of a liquid crystal display device, particularly an IPS liquid crystal display device.

Means for solving the above-mentioned problems are as follows.
[1] A polarizing plate-integrated optical compensation film having at least a polarizing film, a first retardation region, and a second retardation region, having an in-plane refractive index nx, ny (nx> ny), and thickness The retardation Re of the first retardation region defined by Re = (nx−ny) × d using the refractive index nz in the vertical direction and the thickness d is 20 nm to 150 nm, and Nz = (nx−nz) The value Nz of the first retardation region defined by / (nx−ny) is 1.5 to 7, the in-plane refractive indexes nx and ny are substantially equal, and nx <nz Rth = {(nx + ny) / 2−nz} × d. The retardation Rth in the thickness direction of the second retardation region defined by Rth = {(nx + ny) / 2−nz} × d is −80 nm to −400 nm, and the first retardation region and the first retardation region At least one of the two retardation regions is cellulose acetate Pioneto or polarizing plate-integrated optical compensation film is a film comprising a cellulose propionate.
[2] The cellulose acetate propionate or the film containing cellulose propionate is a cellulose acylate film in which the acyl substitution degree to the hydroxyl group of cellulose satisfies all of the following formulas (I) to (III) [1] ] A polarizing plate integrated optical compensation film.
(I) 2.82 ≦ SA + SP ≦ 3
(II) 0 ≦ SA ≦ 1.7
(III) 1.3 ≦ SP ≦ 2.9
(In the formula, SA and SP represent the substitution degree of the acyl group substituted with the hydroxyl group of cellulose, SA is the substitution degree of the acetyl group, and SP is the substitution degree of the propionyl group.)
[3] The polarizing film, the first retardation region, and the second retardation region are arranged in this order, and the slow axis of the first retardation region is the transmission axis of the polarizing film. The polarizing compensation integrated optical compensation film of [1] or [2], which is substantially parallel.
[4] The polarizing film, the second retardation region, and the first retardation region are arranged in this order, and the slow axis of the first retardation region is substantially the transmission axis of the polarizing film. The polarizing compensation integrated optical compensation film of [1] or [2] which is orthogonal.

[5] At least a first polarizing film, a first retardation region, a second retardation region, a liquid crystal cell having a liquid crystal layer sandwiched between a pair of substrates, and a second polarizing film, wherein liquid crystal molecules are displayed during black display. A liquid crystal display device that is aligned substantially parallel to the surfaces of the pair of substrates, wherein an in-plane refractive index nx and ny (nx> ny), a refractive index nz in the thickness direction, and a thickness d The retardation Re of the first retardation region defined by Re = (nx−ny) × d is 20 nm to 150 nm, and the first defined by Nz = (nx−nz) / (nx−ny). The phase difference region value Nz is 1.5 to 7, the in-plane refractive indexes nx and ny of the second phase difference region are substantially equal, nx <nz, and Rth = {(nx + ny) / 2− retardation Rth in the thickness direction of the second retardation region defined by nz} × d is −80. m to −400 nm, at least one of the first retardation region and the second retardation region is cellulose acetate propionate or a film containing cellulose propionate, and the transmission axis of the first polarizing film is A liquid crystal display device parallel to the slow axis direction of liquid crystal molecules during black display.
[6] The first polarizing film, the first retardation region, the second retardation region, and the liquid crystal cell are arranged in this order, and the slow axis of the first retardation region is the first retardation layer. The liquid crystal display device according to [5], which is substantially parallel to the transmission axis of the polarizing film.
[7] The first polarizing film, the second retardation region, the first retardation region, and the liquid crystal cell are arranged in this order, and the slow axis of the first retardation region is the first polarizing film. [5] The liquid crystal display device of [5], which is substantially perpendicular to the transmission axis.
[8] It has a pair of protective films arranged with at least one of the first polarizing film and the second polarizing film interposed therebetween, and at least the position in the thickness direction of the protective film on the side close to the liquid crystal layer among the pair of protective films The liquid crystal display device according to any one of [5] to [7], wherein the phase difference Rth is 40 nm to −40 nm.
[9] It has a pair of protective films arranged with at least one of the first polarizing film and the second polarizing film interposed therebetween, and at least the position in the thickness direction of the protective film on the side close to the liquid crystal layer among the pair of protective films The liquid crystal display device according to any one of [5] to [8], wherein the phase difference Rth is 20 nm to -20 nm.
[10] It has a pair of protective films arranged with at least one of the first polarizing film and the second polarizing film interposed therebetween, and the thickness of the protective film on the side close to the liquid crystal layer of the pair of protective films is 60 μm or less. The liquid crystal display device according to any one of [5] to [9].
[11] A pair of protective films disposed between the first polarizing film and / or the second polarizing film, wherein the protective film on the side close to the liquid crystal layer is a cellulose acylate film or The liquid crystal display device according to any one of [5] to [10], which is a norbornene-based film.
[12] The liquid crystal display device according to any one of [5] to [11], wherein the first retardation region and / or the second retardation region is adjacent to the first polarizing film and / or the second polarizing film. .
[13] Any of [5] to [12], wherein the first retardation region or the second retardation region is disposed at a position closer to the substrate on the opposite side to the viewing side of the pair of substrates of the liquid crystal cell. Liquid crystal display device.
[14] The cellulose acetate propionate or the film containing cellulose propionate is a cellulose acylate film in which the acyl substitution degree of the hydroxyl group of cellulose satisfies all of the following formulas (I) to (III) [5] ]-[13] Liquid crystal display device.
(I) 2.82 ≦ SA + SP ≦ 3
(II) 0 ≦ SA ≦ 1.7
(III) 1.3 ≦ SP ≦ 2.9
(In the formula, SA and SP represent the substitution degree of the acyl group substituted with the hydroxyl group of cellulose, SA is the substitution degree of the acetyl group, and SP is the substitution degree of the propionyl group.)

  The present invention includes at least a first polarizing film, a first retardation region, a second retardation region, and a liquid crystal cell in which a liquid crystal layer made of a liquid crystal material is sandwiched between a pair of substrates. In the liquid crystal display device in which the liquid crystal molecules of the liquid crystal material are aligned substantially parallel to the surfaces of the pair of substrates, the in-plane refractive indexes nx and ny (nx> ny), the refractive index nz in the thickness direction, and The retardation Re of the first retardation region defined by Re = (nx−ny) × d using the thickness d is 20 nm to 150 nm, and is defined by Nz = (nx−nz) / (nx−ny). The first retardation region value Nz1 is 1.5 to 7, the in-plane refractive indices nx and ny are substantially equal, nx <nz, and Rth = {(nx + ny ) / 2−nz} × d thickness of second retardation region defined by The direction retardation Rth is -80 nm to -400 nm, and the transmission axis of the first polarizing film is parallel to the slow axis direction of the liquid crystal molecules at the time of black display, thereby changing the characteristics in the front direction. In contrast, when viewed from an oblique azimuth direction, the contrast decrease caused by the shift of the absorption axes of the two polarizing plates from 90 degrees, particularly the contrast decrease from the oblique direction of 45 degrees, is improved. Further, the contrast can be further improved by setting the Rth of the protective film of the polarizing film to 40 nm or less. In the present invention, cellulose acetate propionate or a film containing cellulose propionate is used in at least one of the two retardation regions. The film has optical properties required for the first retardation region or the second retardation region by adjusting the degree of acyl substitution to the hydroxyl group of cellulose acetate propionate or cellulose propionate and adjusting the production conditions. It can be filled with only one layer. Therefore, by using the film, a liquid crystal display device having a simple structure and improved viewing angle characteristics can be manufactured. In addition, since the film has the performance required as a protective film for the polarizing film, it can be made to function as a protective film by forming it on the surface of the polarizing film, and the viewing angle characteristics can be improved with a simpler configuration. The manufactured liquid crystal display device can be manufactured.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, an embodiment of the liquid crystal display device of the present invention and its constituent members will be described in order. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

  In the present specification, “parallel” and “orthogonal” mean that the angle is within a range of strictly less than ± 10 °. In this range, an error from a strict angle is preferably less than ± 5 °, and more preferably less than ± 2 °. Further, “substantially vertical” means within a range of less than ± 20 ° from a strict vertical angle. In this range, an error from a strict angle is preferably less than ± 15 °, and more preferably less than ± 10 °. Further, the “slow axis” means a direction in which the refractive index is maximized. Further, the measurement wavelength of the refractive index is a value at λ = 550 nm in the visible light region unless otherwise specified.

  In this specification, “polarizing plate” is cut into a size to be incorporated into a long polarizing plate and a liquid crystal device unless otherwise specified (in this specification, “cutting” includes “punching” and “cutting out”. It is used in the meaning including both of the polarizing plates. In this specification, “polarizing film” and “polarizing plate” are distinguished from each other. “Polarizing plate” means a laminate having a transparent protective film for protecting the polarizing film on at least one side of the “polarizing film”. It shall be.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an example of a pixel region of the liquid crystal display device of the present invention. 2 and 3 are schematic views of an embodiment of the liquid crystal display device of the present invention.
[Liquid Crystal Display]
The liquid crystal display device shown in FIG. 2 includes polarizing films 8 and 20, a first retardation region 10, a second retardation region 12, substrates 13 and 17, and a liquid crystal layer 15 sandwiched between the substrates. . The polarizing films 8 and 20 are sandwiched between protective films 7a and 7b and 19a and 19b, respectively.

  In the liquid crystal display device of FIG. 2, the liquid crystal cell includes substrates 13 and 17 and a liquid crystal layer 15 sandwiched between them. The product Δn · d of the thickness d (μm) of the liquid crystal layer and the refractive index anisotropy Δn is optimal in the range of 0.2 to 0.4 μm for the IPS type having no twisted structure in the transmission mode. In this range, the white display luminance is high and the black display luminance is small, so that a bright and high-contrast display device can be obtained. An alignment film (not shown) is formed on the surfaces of the substrates 13 and 17 that are in contact with the liquid crystal layer 15 to align liquid crystal molecules substantially parallel to the surface of the substrate and to be rubbed on the alignment film. The liquid crystal molecule alignment direction in the voltage non-application state or the low application state is controlled by the processing directions 14 and 18 and the like. Further, an electrode (not shown in FIG. 2) capable of applying a voltage to the liquid crystal molecules is formed on the inner surface of the substrate 13 or 17.

  FIG. 1 schematically shows the orientation of liquid crystal molecules in one pixel region of the liquid crystal layer 14. FIG. 1 shows the alignment of liquid crystal molecules in a very small area corresponding to one pixel of the liquid crystal layer 14 in the rubbing direction 4 of the alignment film formed on the inner surfaces of the substrates 13 and 17 and the substrates 13 and 17. It is the schematic diagram shown with the electrodes 2 and 3 which can apply a voltage to the liquid crystal molecule formed in the inner surface. When active driving is performed using a nematic liquid crystal having positive dielectric anisotropy as a field effect liquid crystal, the liquid crystal molecule alignment directions in a no voltage application state or a low application state are 5a and 5b. A display is obtained. When applied between the electrodes 2 and 3, the liquid crystal molecules change their alignment direction in the directions of 6 a and 6 b in accordance with the voltage. Usually, bright display is performed in this state.

In FIG. 2 again, the transmission axis 9 of the polarizing film 8 and the transmission axis 21 of the polarizing film 20 are arranged orthogonally. The slow axis 11 of the first retardation region 10 is parallel to the transmission axis 9 of the polarizing film 8 and the slow axis direction 16 of the liquid crystal molecules in the liquid crystal layer 15 during black display.
In the liquid crystal display device shown in FIG. 2, the configuration in which the polarizing film 8 is sandwiched between the two protective films 7a and 7b is shown, but the protective film 7b may be omitted. Further, although the polarizing film 20 is also sandwiched between the two protective films 19a and 19b, the protective film 19a on the side close to the liquid crystal layer 15 may be omitted. In the aspect of FIG. 2, the first retardation region and the second retardation region may be disposed between the liquid crystal cell and the viewing-side polarizing film with reference to the position of the liquid crystal cell. You may arrange | position between the liquid crystal cell and the polarizing film of the back side. In this embodiment, in any configuration, the second retardation region is disposed closer to the liquid crystal cell.

  Another embodiment of the present invention is shown in FIG. In the liquid crystal display device of FIG. 3, the second retardation region 12 is disposed between the polarizing film 8 and the first retardation region 10. In the liquid crystal display device of FIG. 3, the protective film 7b or the protective film 19a may be omitted. In the embodiment shown in FIG. 3, the first retardation region 10 has a slow axis 11 orthogonal to the transmission axis 9 of the polarizing film 8 and the slow axis direction 16 of the liquid crystal molecules in the liquid crystal layer 15 during black display. It is arranged to become. In the aspect of FIG. 3, the first retardation region and the second retardation region may be disposed between the liquid crystal cell and the viewing-side polarizing film with reference to the position of the liquid crystal cell. You may arrange | position between the liquid crystal cell and the polarizing film of the back side. In the present embodiment, in any configuration, the first retardation region is disposed closer to the liquid crystal cell.

  2 and 3, the first retardation region 10 has an in-plane retardation Re defined by Re = (nx−ny) × d of 20 nm to 150 nm, and Nz = (nx−nz). A value Nz of the first phase difference region defined by / (nx−ny) is 1.5 to 7. On the other hand, in the second retardation region 12, the in-plane refractive indexes nx and ny are substantially equal, nx <nz, and the thickness direction defined by Rth = {(nx + ny) / 2−nz} × d. Retardation Rth is -80 nm to -400 nm. At least one of the first retardation region 10 and the second retardation region 12 is a film containing cellulose acetate propionate or cellulose propionate. Such a film has the optical characteristics required as the first retardation region or the second retardation region by adjusting the acyl substitution degree of the hydroxyl group of cellulose or by adjusting the production conditions. Only one layer can be shown. In addition, since such a film can satisfy the performance required as a protective film for the polarizing film, in the embodiment of FIG. 2, when the first retardation region 10 is made of the film, the protective film 7b is not provided. If the polarizing film 8 and the first retardation region 10 are integrally manufactured, and the second retardation region 12 is made of the film, the polarizing film 8 and the first layer can be formed even without the protective film 7b. By integrally producing the phase difference region 10 and the second phase difference region 12 in this order, the polarizing film 8 deteriorates even when placed in a harsh environment such as high temperature and humidity. It is possible to reduce the deterioration of the characteristics. 3, when the second retardation region 12 is made of the film, the polarizing film 8, the polarizing film 8, and the second retardation region 12 are integrally manufactured, When the retardation region 10 is made of the film, the polarizing film 8, the second retardation region 12, and the first retardation region 10 are integrally manufactured in this order, so that the protective film 7b is not provided. Even when placed in a harsh environment such as high temperature and humidity, it is possible to reduce the deterioration of the polarizing film 8 and display characteristics.

  2 and 3 show a mode of a transmissive mode display device including an upper polarizing plate and a lower polarizing plate, the present invention is a mode of a reflection mode including only one polarizing plate. In such a case, since the optical path in the liquid crystal cell is doubled, the optimum value of Δn · d is about the above half value. The liquid crystal cell used in the present invention is not limited to the IPS mode, and any liquid crystal display device in which liquid crystal molecules are aligned substantially parallel to the surfaces of the pair of substrates during black display can be used. It can be used suitably. Examples thereof include a ferroelectric liquid crystal display device, an antiferroelectric liquid crystal display device, and an ECB type liquid crystal display device.

  The liquid crystal display device of the present invention is not limited to the configuration shown in FIGS. 1 to 3 and may include other members. For example, a color filter may be disposed between the liquid crystal layer and the polarizing film. Further, an antireflection treatment or a hard coat may be applied to the surface of the protective film of the polarizing film. Moreover, you may use what gave electroconductivity to the structural member. In the case of use as a transmission type, a cold cathode or a hot cathode fluorescent tube, or a backlight using a light emitting diode, a field emission element, or an electroluminescent element as a light source can be disposed on the back surface. In this case, the arrangement of the backlight may be on the upper side or the lower side in FIGS. In addition, a reflective polarizing plate, a diffusion plate, a prism sheet, or a light guide plate can be disposed between the liquid crystal layer and the backlight. In addition, as described above, the liquid crystal display device of the present invention may be of a reflective type. In such a case, only one polarizing plate may be disposed on the observation side, and the back side of the liquid crystal cell or the lower side of the liquid crystal cell. A reflective film is disposed on the inner surface of the substrate. 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, a mode applied to a passive matrix liquid crystal display device called time-division driving is also effective.

  Hereinafter, preferred optical characteristics of various members usable in the liquid crystal display device of the present invention, materials used for the members, manufacturing methods thereof, and the like will be described in detail.

In the present invention, at least one of the first retardation region and the second retardation region is made of cellulose acetate propionate or a film containing cellulose propionate. Cellulose acetate propionate is a cellulose acylate in which some of the hydroxyl groups of cellulose are substituted by acetyl groups and propionyl groups. Cellulose propionate is a cellulose acylate in which some of the hydroxyl groups of cellulose are substituted by propionyl groups. Rate. By using cellulose acetate propionate or cellulose propionate having different acyl group substitution degrees, films having desired optical properties can be produced. In order to satisfy the optical characteristics required for the second retardation region, it is preferable to use cellulose acetate propionate or cellulose propionate whose acyl substitution degree satisfies all of the following formulas (I) to (III). Preferably
(I) 2.82 ≦ SA + SP ≦ 3
(II) 0 ≦ SA ≦ 1.7
(III) 1.3 ≦ SP ≦ 2.9
(In the formula, SA and SP represent the substitution degree of the acyl group substituted with the hydroxyl group of cellulose, SA is the substitution degree of the acetyl group, and SP is the substitution degree of the propionyl group.)
More preferably,
(I) 2.83 ≦ SA + SP ≦ 2.99
(II) 0 ≦ SA ≦ 1.59
(III) 1.4 ≦ SP ≦ 2.85
And more preferably
(I) 2.85 ≦ SA + SP ≦ 2.98
(II) 0 ≦ SA ≦ 1.48
(III) 1.5 ≦ SP ≦ 2.8
It is.
Among these, when SA + SP is increased, the value of Rth can be decreased, and when SP is increased, the humidity dependency of retardation can be decreased.

  Cellulose acylate such as cellulose acetate propionate or cellulose propionate that can be used in the present invention can be obtained by introducing a functional group biologically or chemically from cellulose ester compound and cellulose as a raw material. The basic principle of is described in Nobuhiko Ueda et al., Wood Chemistry pages 180-190 (Kyoritsu Shuppan, 1968). A typical synthesis method of cellulose acylate is a liquid phase acylation method using a carboxylic acid anhydride-carboxylic acid-sulfuric acid catalyst. Specifically, cellulose raw materials such as cotton linter and wood pulp are pretreated with an appropriate amount of carboxylic acid such as acetic acid, and then put into a precooled acylated mixture for esterification, and complete cellulose acylate (2nd, The total degree of acyl substitution at the 3rd and 6th positions is approximately 3.00). The acylated mixed solution generally contains a carboxylic acid as a solvent, a carboxylic anhydride as an esterifying agent, and sulfuric acid as a catalyst. The carboxylic anhydride is generally used in a stoichiometric excess over the sum of the cellulose that reacts with it and the water present in the system.

  After completion of the acylation reaction, water or hydrous acetic acid is added in order to hydrolyze the excess carboxylic anhydride remaining in the system. In order to partially neutralize the esterification catalyst, an aqueous solution of a neutralizing agent (for example, calcium, magnesium, iron, aluminum or zinc carbonate, acetate, hydroxide or oxide) may be added. Next, the obtained complete cellulose acylate is saponified and aged by maintaining it at 20 to 90 ° C. in the presence of a small amount of an acylation reaction catalyst (generally, remaining sulfuric acid) to obtain a desired degree of acyl substitution and polymerization. The cellulose acylate having a degree is changed. When the desired cellulose acylate is obtained, the catalyst remaining in the system is completely neutralized with a neutralizing agent as described above, or in water or dilute acetic acid without neutralization. The cellulose acylate solution is added (or water or dilute acetic acid is added into the cellulose acylate solution) to separate the cellulose acylate, and the cellulose acylate is obtained by washing and stabilizing treatment.

  The degree of polymerization of the cellulose acylate is preferably from 150 to 500, more preferably from 200 to 400, and even more preferably from 220 to 350 in terms of viscosity average degree of polymerization. The viscosity average degree of polymerization can be measured according to Uda et al.'S limiting viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Science, Vol. 18, No. 1, pages 105-120, 1962). A method for measuring the viscosity average degree of polymerization is also described in JP-A-9-95538.

Cellulose acetate propionate or a film containing cellulose propionate can be produced by utilizing various methods such as an extrusion method and a solution casting method. In order to obtain predetermined optical characteristics after the film is formed, a stretching process can be further performed. In the case of producing the film by using a solution casting method, a plasticizer (preferably added amount is 0.1 to 20% by mass with respect to the cellulose ester, the same applies hereinafter) and a modifier (0. 1 to 20% by mass), an ultraviolet absorber (0.001 to 5% by mass), a fine particle powder (0.001 to 5% by mass) having an average particle diameter of 5 to 3000 nm, and a fluorosurfactant (0. 001-2 mass%), release agent (0.0001-2 mass%), deterioration inhibitor (0.0001-2 mass%), optical anisotropy control agent (0.1-15 mass%), infrared absorption You may contain additives, such as an agent (0.1-5 mass%). In addition, about the production method of a film, the details are described in the public technique 2001-1745 (issued on March 15, 2001, invention association) etc., and can be applied to this invention.
By subjecting the obtained unstretched and stretched cellulose acylate film to an appropriate surface treatment, adhesion between the cellulose acylate layer and other layers can be improved. The surface treatment includes glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, saponification treatment (acid saponification treatment, alkali saponification treatment), and glow discharge treatment and alkali saponification treatment are particularly preferable.
In addition, as described above, only the film containing cellulose acetate propionate or cellulose propionate can satisfy the optical characteristics required for the first retardation region or the second retardation region. The aspect in which the first retardation region or the second retardation region includes other birefringent film or retardation film together with cellulose acetate propionate film or cellulose propionate film is also included.

[First phase difference region]
In the present invention, the first retardation region is defined as Re = (nx−ny) × d using in-plane refractive indexes nx and ny (nx> ny), a refractive index nz in the thickness direction, and a thickness d. The in-plane retardation Re is 20 nm to 150 nm. In order to effectively reduce the light leakage in the oblique direction, Re of the first phase difference region is more preferably 40 nm to 115 nm, and further preferably 60 nm to 95 nm. Further, Nz defined by Nz = (nx−nz) / (nx−ny) is 1.5 to 7. Thus, in order to effectively reduce the light leakage in the oblique direction, the Nz of the first phase difference region is more preferably 2.0 to 5.5, and 2.5 to 4.5. Is more preferable.

  The material and form of the first retardation region are not particularly limited as long as it has the optical characteristics. As described above, it may be composed of cellulose acetate propionate or a film containing cellulose propionate, or it may be composed of a birefringent polymer film made of other materials. A retardation film having a retardation layer formed by applying or transferring a polymer liquid crystalline compound may be used. Moreover, each can also be laminated | stacked and used.

  As the birefringent polymer film, those having excellent controllability of birefringence characteristics, transparency and heat resistance are preferable. In this case, the polymer material to be used is not particularly limited as long as it is a polymer capable of achieving uniform biaxial orientation, but is preferably a conventionally known material that can be formed by a solution casting method or an extrusion method, and is preferably a norbornene-based material. Polymers, polycarbonate polymers, polyarylate polymers, polyester polymers, aromatic polymers such as polysulfone, cellulose acylate, or polymers obtained by mixing two or more of these polymers It is done.

The biaxial orientation of the film is a film made of the thermoplastic resin produced by an appropriate method such as an extrusion molding method or a casting film forming method, for example, a longitudinal stretching method using a roll, a transverse stretching method using a tenter, or a biaxial stretching method. For example, it can be achieved by performing a stretching treatment. In the longitudinal stretching method using the roll, an appropriate heating method such as a method using a heating roll, a method of heating an atmosphere, or a method of using them together can be adopted. In the biaxial stretching method using a tenter, an appropriate method such as a simultaneous biaxial stretching method using an all tenter method or a sequential biaxial stretching method using a roll tenter method can be employed.
Moreover, a thing with little orientation nonuniformity and phase difference nonuniformity is preferable. Although the thickness can be appropriately determined depending on the phase difference or the like, it is generally preferably 1 to 300 μm, more preferably 10 to 200 μm, and further preferably 20 to 150 μm from the viewpoint of thinning. .

  As the norbornene-based polymer, norbornene and its derivatives, tetracyclododecene and its derivatives, dicyclopentadiene and its derivatives, methanotetrahydrofluorene and its monomers as a main component of a monomer polymer, Ring-opening polymer of norbornene monomer, ring-opening copolymer of norbornene monomer and other monomer capable of ring-opening copolymerization, addition polymer of norbornene monomer, copolymerizable with norbornene monomer Examples include addition copolymers with other monomers and hydrogenated products thereof. Among these, from the viewpoints of heat resistance, mechanical strength, and the like, a ring-opening polymer hydride of a norbornene monomer is most preferable. The molecular weight of the norbornene-based polymer, the polymer of the monocyclic olefin or the polymer of the cyclic conjugated diene is appropriately selected according to the purpose of use, but the cyclohexane solution (toluene solution if the polymer resin does not dissolve) The polyisoprene or polystyrene-converted weight average molecular weight measured by gel permeation chromatography is usually 5,000 to 500,000, preferably 8,000 to 200,000, more preferably 10,000 to 100,000. When the thickness is within the range, the mechanical strength of the film (A) and the moldability are highly balanced and suitable.

  The acyl group of cellulose acylate may be an aliphatic group or an allyl group, and is not particularly limited. They are, for example, alkyl carbonyl esters, alkenyl carbonyl esters, aromatic carbonyl esters, aromatic alkyl carbonyl esters, etc. of cellulose, each of which may further have a substituted group, and an ester having a total carbon number of 22 or less. Groups are preferred. These preferred cellulose acylates include acyl groups having a total carbon number of 22 or less in the ester moiety (for example, acetyl, propionyl, butyroyl, barrel, heptanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, hexadecanoyl, octadecanoyl, etc. ), Arylcarbonyl groups (acrylic, methacrylic, etc.), allylcarbonylkis (benzoyl, naphthaloyl etc.) and cinnamoyl groups. Among these, cellulose acetate, cellulose acetate propionate, cellulose propionate, cellulose acetate butyrate, cellulose acetate stearate, cellulose acetate benzoate, etc., in the case of mixed esters, the ratio is not particularly limited, preferably It is preferable that acetate is 30 mol% or more of the total ester. Especially, it is preferable that a 1st phase difference area | region is a film containing the above-mentioned cellulose acetate propionate or a cellulose propionate.

  A cellulose acylate film is also preferable, and a photographic grade is particularly preferable, and a commercially available photographic grade can be obtained with satisfactory quality such as viscosity average polymerization degree and substitution degree. As manufacturers of photographic grade cellulose triacetate, Daicel Chemical Industries, Ltd. (for example, LT-20, 30, 40, 50, 70, 35, 55, 105, etc.), Eastman Kodak Company (for example, CAB-551) 0.01, CAB-551-0.02, CAB-500-5, CAB-381-0.5, CAB-381-02, CAB-381-20, CAB-321-0.2, CAP-504 0.2, CAP-482-20, CA-398-3, etc.), Coatles, Hoechst, etc., any of which can use photographic grade cellulose acylate. In addition, plasticizers, surfactants, retardation modifiers, UV absorbers, and the like can be used in the future for the purpose of controlling the mechanical and optical properties of the film (reference material: Japanese Patent Application Laid-Open No. 2002-277632). Gazette, JP-A-2002-182215)

As a method of forming the transparent resin into a sheet or film, for example, either a hot melt molding method or a solution casting method can be used. The heat-melt molding method can be further classified into an extrusion molding method, a press molding method, an inflation molding method, an injection molding method, a blow molding method, a stretch molding method, etc. Among these methods, mechanical strength, surface In order to obtain a film excellent in accuracy and the like, the extrusion molding method, the inflation molding method, and the press molding method are preferable, and the extrusion molding method is most preferable. The molding conditions are appropriately selected depending on the purpose of use and the molding method. In the case of the heat-melt molding method, the cylinder temperature is preferably set in the range of preferably 100 to 400 ° C, more preferably 150 to 350 ° C. The thickness of the sheet or film is preferably 10 to 300 μm, more preferably 30 to 200 μm.
When the glass transition temperature of the transparent resin is defined as Tg, the stretching of the sheet or film is preferably in a temperature range of Tg-30 ° C to Tg + 60 ° C, more preferably in a temperature range of Tg-10 ° C to Tg + 50 ° C. In at least one direction, the stretching ratio is preferably 1.01 to 2 times. The stretching direction may be at least one direction, but when the sheet is obtained by extrusion, the direction is preferably the mechanical flow direction (extrusion direction) of the resin. A free shrink uniaxial stretching method, a fixed width uniaxial stretching method, a biaxial stretching method, and the like are preferable. The optical characteristics can be controlled by controlling the draw ratio and the heating temperature.

[Second phase difference region]
In the present invention, in the second retardation region, the in-plane refractive indexes nx and ny are substantially equal, and the refractive index nz in the thickness direction satisfies nx <nz. The retardation Rth in the thickness direction of the second retardation region defined by Rth = {(nx + ny) / 2−nz} × d using the refractive index nz in the thickness direction and the thickness d is −80 nm to − 400 nm. The more preferable range of Rth of the second retardation region varies depending on the optical characteristics of other optical members, and in particular, the Rth of the protective film (for example, triacetylcellulose film) of the polarizing film located closer to the second retardation region. Depending on the situation, it varies greatly. In order to effectively reduce the light leakage in the oblique direction, Rth of the second retardation region is more preferably −100 nm to −340 nm, and further preferably −120 nm to −270 nm. On the other hand, nx and ny in the second phase difference region are substantially the same as described above, and Re has a value in the vicinity of 0. Specifically, the in-plane retardation Re is preferably 0 to 50 nm, and more preferably 0 to 20 nm.

  As long as the second retardation region has the optical characteristics, the material and form thereof are not particularly limited. As described above, it may be composed of cellulose acetate propionate or a film containing cellulose propionate, a retardation film composed of a birefringent polymer film composed of another material, and a low molecular weight on a transparent support. Alternatively, any of retardation films having a retardation layer formed by applying or transferring a polymer liquid crystalline compound can be used. Moreover, each can also be laminated | stacked and used.

  The retardation film composed of a birefringent polymer film having the above optical characteristics can be obtained by stretching a polymer film in the thickness direction of the film or by applying a vinylcarbazole polymer and drying it (Japanese Patent Laid-Open No. 2001-091746). Publication). In addition, as a retardation layer formed from a liquid crystalline compound having the above optical characteristics, a cholesteric discotic liquid crystal compound or composition containing a chiral structural unit is fixed after its helical axis is aligned substantially perpendicular to the substrate. Examples thereof include a layer formed by forming a rod-like liquid crystal compound or composition having a positive refractive index anisotropy and a composition formed by orienting the substrate substantially perpendicularly to the substrate and then immobilizing it (for example, JP-A-6-6 331826 and Japanese Patent No. 2853064). The rod-like liquid crystal compound may be a low molecular compound or a high molecular compound. Furthermore, not only one retardation layer but also a plurality of retardation layers can be laminated to form the second retardation region exhibiting the above optical characteristics. Further, the second retardation region may be configured so that the entire laminated body of the support and the retardation layer satisfies the optical characteristics. As the rod-like liquid crystal compound to be used, those that take a nematic liquid crystal phase, a smectic liquid crystal phase, and a lyotropic liquid crystal phase in a temperature range in which the orientation is fixed are preferably used. A liquid crystal exhibiting a smectic A phase and a B phase capable of obtaining uniform vertical alignment without fluctuation is preferable. In particular, in the presence of an additive, a rod-like liquid crystalline compound that becomes a liquid crystal state in an appropriate orientation temperature range is formed by using a composition containing the additive and the rod-like liquid crystalline compound. Is also preferable.

《Bar-shaped liquid crystalline compound》
The second retardation region of the present invention may be formed from a composition containing a rod-like liquid crystal compound. Examples of the rod-like liquid crystalline compound 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. In addition to the above low-molecular liquid crystalline molecules, high-molecular liquid crystalline molecules can also be used. As the liquid crystal molecules, those having a partial structure capable of causing polymerization or crosslinking reaction by actinic rays, electron beams, heat, or the like are preferably used. The number of the partial structures is 1 to 6, preferably 1 to 3.

  When the second retardation region includes a retardation layer formed by fixing the rod-like liquid crystalline compound in the aligned state, the rod-like liquid crystalline compound is substantially vertically aligned and fixed in that state. It is preferable to use a retardation layer. Substantially perpendicular means that the angle formed by the film surface and the director of the rod-like liquid crystal compound is in the range of 70 ° to 90 °. These liquid crystalline compounds may be aligned obliquely or may be changed so that the inclination angle gradually changes (hybrid alignment). Even in the case of oblique orientation or hybrid orientation, the average inclination angle is preferably 70 ° to 90 °, more preferably 80 ° to 90 °, and most preferably 85 ° to 90 °.

  The retardation layer formed from the rod-like liquid crystalline compound is formed on the support with a coating liquid containing the rod-like liquid crystalline compound and, if desired, the following polymerizable initiator, air interface vertical alignment agent and other additives. It can be formed by coating on the vertical alignment film formed, vertically aligning, and fixing the alignment state. When it is formed on a temporary support, it can also be produced by transferring the retardation layer onto the support. Furthermore, not only a single retardation layer but also a plurality of retardation layers can be laminated to form a second retardation region exhibiting the above optical characteristics. Further, the second retardation region may be configured so that the entire laminated body of the support and the retardation layer satisfies the optical characteristics.

  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).

  The vertically aligned liquid crystal compound is preferably fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction of the polymerizable group (P) 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. A photopolymerization reaction is preferred. Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Description), acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970).

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. The light irradiation for polymerizing the rod-like liquid crystalline molecules preferably uses 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 first retardation region including the optically illegal layer is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm, and most preferably 1 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 allow a fluorine atom or a hydrocarbon group to 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 mass, more preferably in a proportion of 0.1 to 70% by mass, and in a proportion of 0.5 to 65% by mass. More preferably, it is most preferable to contain in the ratio of 1-60 mass%. 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 hydrocarbon group has preferably 10 to 100 carbon atoms, more preferably 10 to 60, and most preferably 10 to 40 carbon atoms. 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.

  Further, as a means for vertically aligning the liquid crystalline compound, a method of mixing an organic acid with a polymer of polyvinyl alcohol, modified 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. Moreover, quaternary ammonium salts can also be used suitably. The mixing amount is preferably 0.1% by mass to 20% by mass and more preferably 0.5% by mass to 10% by mass with respect to the polymer.

  The saponification degree of the polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. The polymerization degree of polyvinyl alcohol is preferably 100 to 5000.

  When aligning a rod-like liquid crystalline compound, the alignment film is preferably made of a polymer having a hydrophobic group as a functional group in the side chain. The specific type of functional group is determined according to the type of liquid crystal molecule and the required alignment state. For example, the modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, fluorine atoms Substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy, dialkoxy, monoalkoxy) and the like can be mentioned. Specific examples of these modified polyvinyl alcohol compounds include, for example, paragraph numbers [0022] to [0145] in JP-A No. 2000-155216 and paragraph numbers [0018] to [0018] in JP-A No. 2002-62426. And the like described in [0022].

  The alignment film is formed by using a polymer having a side chain having a crosslinkable functional group bonded to the main chain or a polymer having a crosslinkable functional group on a side chain having a function of aligning liquid crystal molecules. When the retardation film is formed using a composition containing a polyfunctional monomer, the polymer in the alignment film and the polyfunctional monomer in the retardation film formed thereon can be copolymerized. As a result, a covalent bond is formed not only between the polyfunctional monomers but also between the alignment film polymers and between the polyfunctional monomer and the alignment film polymer, and the alignment film and the retardation film are firmly bonded. Therefore, the strength of the optical compensation sheet can be remarkably improved by forming the alignment film using a polymer having a crosslinkable functional group. The crosslinkable functional group of the alignment film polymer preferably contains a polymerizable group in the same manner as the polyfunctional monomer. Specific examples include those described in paragraphs [0080] to [0100] in JP-A-2000-155216.

  Apart from the crosslinkable functional group, the alignment film polymer can also be crosslinked using a crosslinking agent. Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraphs [0023] to [024] in JP-A-2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.

  0.1-20 mass% is preferable with respect to a polymer, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is more preferable. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By adjusting in this way, even if the alignment film is used for a long time in a liquid crystal display device or left in a high-temperature and high-humidity atmosphere for a long time, sufficient durability without occurrence of reticulation can be obtained.

  The alignment film can be basically formed by applying a composition containing the polymer and the crosslinking agent, which are alignment film forming materials, onto a transparent support, followed by drying by heating (crosslinking) and rubbing treatment. it can. As described above, the crosslinking reaction may be performed at an arbitrary time after coating on the transparent support. When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the coating solution is preferably a mixed solvent of an organic solvent (eg, methanol) having a defoaming action and water. The ratio of water: methanol is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the alignment film and also the phase difference layer surface reduces remarkably.

  The alignment film is preferably applied by spin coating, dip coating, curtain coating, extrusion coating, rod coating, or roll coating. A rod coating method is particularly preferable. The film thickness after drying is preferably 0.1 to 10 μm. Heating and drying can be performed at 20 ° C to 110 ° C. In order to form sufficient cross-linking, 60 ° C to 100 ° C is preferable, and 80 ° C to 100 ° C is particularly preferable. The drying time can be 1 minute to 36 hours, preferably 1 minute to 30 minutes. The pH is preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, the pH is 4.5 to 5.5, and 5 is particularly preferable.

  The alignment film is preferably provided on the transparent support. The alignment film is used by crosslinking the polymer layer as described above. The rubbing treatment is preferably not performed for the vertical alignment of the rod-like liquid crystalline compound. In addition, after aligning a liquid crystalline compound using an alignment film, the liquid crystalline compound is fixed in the alignment 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 vertical alignment agent》
Usually, since the liquid crystalline compound has a property of being inclined and aligned on the air interface side, it is necessary to control the alignment of the liquid crystalline compound vertically on the air interface side in order to obtain a uniformly vertically aligned state. . For this purpose, a phase difference film is formed by adding a compound that is unevenly distributed on the air interface side and that has the effect of vertically aligning the liquid crystalline compound by its excluded volume effect or electrostatic effect to the liquid crystal coating liquid. It is preferable to do this.

  As the air interface alignment agent, compounds described in JP-A Nos. 2002-20363 and 2002-129162 can be used. Also, paragraph numbers [0072] to [0075] of Japanese Patent Application No. 2002-212100, paragraph numbers [0037] to [0039] of Japanese Patent Application No. 2002-262239, paragraphs of Japanese Patent Application No. 2003-91752 Nos. [0071] to [0078], paragraph numbers [0052] to [0054], [0065] to [0066], [0092] to [0094] of Japanese Patent Application No. 2003-119959, Japanese Patent Application No. 2003-330303 The matters described in paragraph numbers [0028] to [0030] of the specification and paragraph numbers [0087] to [0090] of Japanese Patent Application No. 2004-003804 can also be appropriately applied to the present invention. Moreover, by mix | blending these compounds, applicability | paintability is improved and generation | occurrence | production of a nonuniformity or a repellency is suppressed.

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

<Other materials in retardation layer>
Along with the liquid crystal compound, a plasticizer, a surfactant, a polymerizable monomer, and the like can be used in combination to improve the uniformity of the coating film, the strength of the film, the orientation of the liquid crystal compound, and the like. These materials are preferably compatible with the liquid crystal compound and do not inhibit the alignment.

  Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer and is preferably copolymerizable with the above-described polymerizable group-containing liquid crystal compound. Examples thereof include those described in paragraph numbers [0018] to [0020] in JP-A No. 2002-296423. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the discotic liquid crystalline molecules.

  Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specifically, for example, compounds described in JP-A-2001-330725, paragraphs [0028] to [0056], and paragraphs [0069] to [0126] in Japanese Patent Application No. 2003-295212. And the compounds described.

  The polymer used together with the liquid crystal compound is preferably capable of thickening the coating solution. A cellulose ester can be mentioned as an example of a polymer. Preferable examples of the cellulose ester include those described in paragraph [0178] of JP-A No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass, and in the range of 0.1 to 8% by mass with respect to the liquid crystal molecules so as not to inhibit the alignment of the liquid crystal compound. It is more preferable.

[Support]
In the present invention, a retardation layer formed from a liquid crystal compound may be formed on a support. The support is preferably transparent, and specifically, the light transmittance is preferably 80% or more. The support preferably has a small wavelength dispersion. Specifically, the Re400 / Re700 ratio is preferably less than 1.2. Among these, a polymer film is preferable. The transparent support can also serve as the first retardation region, the second retardation region, or the polarizing plate protective film. The transparent support and the whole retardation layer may constitute the first retardation region or the second retardation region. In addition, for example, when the second retardation region is a retardation film made of liquid crystalline molecules, the support contains cellulose propionate or cellulose propionate having optical characteristics required for the first retardation region. As a film, or when the first retardation region is a retardation film made of liquid crystalline molecules, the support contains cellulose propionate or cellulose propionate having optical properties required for the second retardation region. As the film, the first phase difference region and the first phase difference region can be integrally manufactured.

  The optical anisotropy of the support is preferably small, and the in-plane retardation (Re) is preferably 20 nm or less, more preferably 10 nm or less, and most preferably 5 nm or less. Moreover, when it serves also as a 1st phase difference area | region, retardation Re is 20 nm-150 nm, It is more preferable that it is 40 nm-115 nm, It is more preferable that it is 60 nm-95 nm. Moreover, Nz is 1.5-7, it is more preferable that it is 2.0-5.5, and it is further more preferable that it is 2.5-4.5.

  Examples of the polymer film as the support include cellulose ester, polycarbonate, polysulfone, polyethersulfone, polyacrylate and polymethacrylate films. A cellulose ester film is preferred, an acetylcellulose film is more preferred, and a triacetylcellulose film is most preferred. The polymer film is preferably formed by a solvent cast method. The thickness of the transparent support is preferably 20 to 500 μm, and more preferably 40 to 200 μm. In order to improve adhesion between the transparent support and the layer (adhesive layer, vertical alignment film or retardation layer) provided thereon, surface treatment (eg, glow discharge treatment, corona discharge treatment, ultraviolet light (UV) ) Treatment, flame treatment). An adhesive layer (undercoat layer) may be provided on the transparent support. Moreover, the average particle diameter is 10 to 100 nm in order to provide the transparent support or the long transparent support with slipperiness in the conveying process or to prevent the back surface and the surface from sticking after winding. It is preferable to use what formed the polymer layer which mixed the inorganic particle of about 5%-40% by solid content weight ratio by the application | coating or co-casting with the support body on the one side of the support body.

[Protective film for polarizing film]
As the protective film for the polarizing film, a protective film having no absorption in the visible light region, a light transmittance of 80% or more, and a retardation based on birefringence is preferable. Specifically, the in-plane Re is preferably 0 to 30 nm, more preferably 0 to 15 nm, and most preferably 0 to 5 nm. Furthermore, the retardation Rth in the thickness direction is preferably 0 to 40 nm, more preferably 0 to 20 nm, and most preferably 0 to 10 nm. Any film having this characteristic can be preferably used, but from the viewpoint of durability of the polarizing film, cellulose acylate or norbornene-based film is more preferable. Examples of the method for reducing the Rth of the cellulose acylate film include methods described in JP-A Nos. 11-246704, 2001-247717, and Japanese Patent Application No. 2003-379975. Rth can also be reduced by reducing the thickness of the cellulose acylate film. The thickness of the cellulose sylate film as the protective film for the first and second polarizing films is preferably 10 to 100 μm, more preferably 10 to 60 μm, and still more preferably 20 to 45 μm.

[Optical compensation film integrated with polarizing plate]
The present invention relates to a polarizing plate integrated compensation film manufactured by integrating a polarizing film and first and second retardation regions having an optical compensation function. By using the polarizing plate integrated optical compensation film of the present invention, the viewing angle characteristics of the liquid crystal display device can be improved with a simpler configuration. In addition, the polarizing plate integrated optical compensation film of the present invention can be produced in a long shape by roll-to-roll, and then cut into a desired size, so that it can be produced by a simple process, It also contributes to improving the productivity of liquid crystal display devices.

  One embodiment of the polarizing plate-integrated optical compensation film of the present invention includes a polarizing film, a first retardation region having an in-plane retardation Re of 20 nm to 150 nm, and Nz of 1.5 to 7, and an in-plane The first retardation region is arranged in this order with the second retardation region in which the refractive indexes nx and ny are substantially equal, nx <nz, and the retardation Rth in the thickness direction is -80 nm to -400 nm. And at least one of the second retardation regions is cellulose acetate propionate or a film containing cellulose propionate, and the slow axis of the first retardation region is substantially parallel to the transmission axis of the polarizing film. This is a polarizing plate integrated optical compensation film. The polarizing plate integrated optical compensation film of this embodiment has not only a function as a polarizing film but also a retardation layer that satisfies optical characteristics as the first retardation region and the second retardation region. The polarizing plate-integrated optical compensation film of the present embodiment is produced, for example, in a long shape by roll-to-roll, and after being cut into a predetermined size, a liquid crystal display device (for example, a liquid crystal display device having the configuration of FIG. 2). Used for.

  In another embodiment of the polarizing plate-integrated optical compensation film of the present invention, the in-plane refractive indices nx and ny are substantially equal to each other, nx <nz, and the retardation Rth in the thickness direction is −80 nm to A second retardation region of −400 nm and an in-plane retardation Re of 20 nm to 150 nm and a first retardation region of Nz of 1.5 to 7 are arranged in this order, and the first retardation At least one of the region and the second retardation region is cellulose acetate propionate or a film containing cellulose propionate, and the slow axis of the first retardation region is substantially the transmission axis of the polarizing film It is a polarizing plate-integrated optical compensation film that is orthogonal. The polarizing plate integrated optical compensation film of this embodiment has not only a function as a polarizing film but also a retardation layer that satisfies optical characteristics as the first retardation region and the second retardation region. The polarizing plate-integrated optical compensation film of the present embodiment is produced, for example, in a long shape by roll-to-roll, cut into a predetermined size, and then a liquid crystal display device (for example, a liquid crystal display device having the configuration of FIG. 3). Used for.

  Note that the polarizing plate-integrated optical compensation film of the present invention may have a polarizing film protective film on the surface of the polarizing film opposite to the side where the retardation layer is formed. Further, a protective film for the polarizing film polarizing film may be provided between the polarizing film and the retardation layer. In such a case, the retardation based on the birefringence of the protective film is small. The in-plane retardation Re and the thickness direction retardation Rth are both preferably closer to 0 nm.

The present invention will be described more specifically with reference to the following examples. The materials, reagents, amounts and ratios of substances, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.
<Production of IPS mode liquid crystal cell>
As shown in FIG. 1, electrodes (2 and 3 in FIG. 1) are arranged on one glass substrate so that the distance between adjacent electrodes is 20 μm, and a polyimide film is used as an alignment film on it. A rubbing process was performed. The rubbing process was performed in the direction 4 shown in FIG. 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 3.9 μm, and the rubbing directions of the two glass substrates are parallel. A nematic liquid crystal composition having a refractive index anisotropy (Δn) of 0.0769 and a dielectric anisotropy (Δε) of 4.5 was enclosed. The value of d · Δn of the liquid crystal layer was 300 nm.

<Fabrication of ferroelectric liquid crystal cell>
A polyimide film on an ITO electrode glass substrate was provided as an alignment film, and a rubbing treatment was performed. Two substrates are manufactured, the alignment films are made to face each other, the distance between the substrates (gap; d) is set to 1.9 μm, and the rubbing directions of the two glass substrates are parallel to each other and bonded together. Next, a ferroelectric liquid crystal composition having a refractive index anisotropy (Δn) of 0.15 and a spontaneous polarization (Ps) of 12 nCcm ⁻² was sealed. The value of d · Δn of the liquid crystal layer was 280 nm.

<Preparation of first retardation region 1 and first retardation region 2>
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution. The solution was filtered using a filter paper (No. 63, manufactured by Advantech) having a retained particle diameter of 4 μm and a drainage time of 35 seconds at 5 kg / cm ² or less.

────────────────────────────────────
Cellulose acetate solution composition ────────────────────────────────────
Cellulose acetate having an acetylation degree of 60.9% (degree of polymerization: 300, Mn / Mw = 1.5) 100 parts by weight Triphenyl phosphate (plasticizer) 7.8 parts by weight Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by weight Methylene chloride (first solvent) 300 parts by weight Methanol (second solvent) 54 parts by weight 1-butanol (third solvent) 11 parts by weight ──────────────────── ────────────────

  In another mixing tank, 8 parts by mass of the following retardation increasing agent A, 10 parts by mass of retardation increasing agent B, 0.28 parts by mass of silicon dioxide fine particles (average particle size: 0.1 μm), 80 parts by mass of methylene chloride And 20 parts by mass of methanol were added and stirred while heating to prepare a retardation increasing agent solution (and a fine particle dispersion). The dope was prepared by mixing 474 parts by mass of the cellulose acetate solution with 40 parts by mass of the retardation increasing agent solution and stirring sufficiently.

  The obtained dope was cast using a band casting machine. A film having a residual solvent amount of 15% by mass was stretched laterally at a stretch ratio of 20% using a tenter under the condition of 130 ° C., held at 50 ° C. for 30 seconds with the stretched width, and then clipped to remove cellulose. An acetate film was prepared. The residual solvent amount at the end of stretching was 5% by mass, and further dried to prepare a film with the residual solvent amount being less than 0.1% by mass.

  The film thus obtained (first retardation region 1) had a thickness of 80 μm. About the produced 1st phase difference area | region 1, Re is 70 nm by measuring the light incident angle dependence of Re using an automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments Co., Ltd. product). It was found that Rth was 175 nm and Nz was 3.0.

  In another mixing tank, 16 parts by mass of the above-mentioned retardation increasing agent A, 8 parts by mass of retardation increasing agent B, 0.28 parts by mass of silicon dioxide fine particles (average particle size: 0.1 μm), 80 parts by mass of methylene chloride And 20 parts by mass of methanol were added and stirred while heating to prepare a retardation increasing agent solution (and a fine particle dispersion). 45 parts by mass of the retardation increasing agent solution was mixed with 474 parts by mass of the cellulose acetate solution, and the dope was prepared by sufficiently stirring, as in the first retardation region 1 except that the draw ratio was 23%. A film was formed. The film thus obtained (first retardation region 2) had a thickness of 77 μm. About the produced 1st phase difference area | region 2, Re is 70 nm by measuring the light incident angle dependence of Re using an automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments Co., Ltd. product). It was found that Rth was 210 nm and Nz was 3.5.

<< Production of Second Phase Difference Region 1, Second Phase Difference Region 2, and Second Phase Difference Region 3 >>
The roll-shaped cellulose acylate film of Table 1 was produced according to the following.
(Preparation of cellulose acylate)
Cellulose acylates having different acyl group types and substitution degrees as shown in Table 1 were prepared. That is, a mixture of sulfuric acid as a catalyst (7.8 parts by mass with respect to 100 parts by mass of cellulose) and carboxylic anhydride is added to cellulose derived from pulp after cooling to -20 ° C, and acylation is performed at 40 ° C. went. At this time, the kind of acyl group and its substitution ratio were adjusted by adjusting the kind and amount of carboxylic anhydride. After acylation, aging was performed at 40 ° C. to adjust the total substitution degree.

(Preparation of cellulose acylate solution)
1) Cellulose acylate The cellulose acylate prepared was heated to 120 ° C. and dried to adjust the water content to 0.5% by mass or less, and then 30 parts by mass was mixed with a solvent.
2) Solvent Dichloromethane / methanol / butanol (81/15/4 parts by mass) was used as a solvent. The water content of these solvents was 0.2% by mass or less.
3) Additives 0.9 parts by weight of trimethylolpropane triacetate were added in preparing all the solutions. In addition, 0.25 part by mass of silicon dioxide fine particles (particle diameter 20 nm, Mohs hardness about 7) was added in preparing all solutions.
4) The cellulose acylate was gradually added to the 400 liter stainless steel dissolution tank having swelling and dissolution stirring blades and circulating cooling water around the outer periphery, while stirring and dispersing the solvent and additives. . After completion of the addition, the mixture was stirred at room temperature for 2 hours, swollen for 3 hours, and then stirred again to obtain a cellulose acylate solution.
For stirring, a dissolver type eccentric stirring shaft that stirs at a peripheral speed of 15 m / sec (shear stress 5 × 10 ⁴ kgf / m / sec ² ) and an anchor blade on the central axis and a peripheral speed of 1 m / sec. A stirring shaft that stirs at a sec (shear stress of 1 × 10 ⁴ kgf / m / sec ² ) was used. Swelling was carried out with the high speed stirring shaft stopped and the peripheral speed of the stirring shaft having anchor blades set at 0.5 m / sec.
5) Filtration The cellulose acylate solution obtained above was filtered with a filter paper (# 63, manufactured by Toyo Filter Paper Co., Ltd.) having an absolute filtration accuracy of 0.01 mm, and further a filter paper (FH025, Poll) having an absolute filtration accuracy of 2.5 μm. To obtain a cellulose acylate solution.

(Preparation of cellulose acylate film)
The cellulose acylate solution was heated to 30 ° C., and cast on a mirror surface stainless steel support having a band length of 60 m set at 15 ° C. through a casting Giesser (described in JP-A-11-314233). The space temperature of the entire casting part was set to 15 ° C. And the cellulose acylate film which had been cast and rotated 50 cm before the casting part was peeled off from the band, and 45 ° C. dry air was blown. Next, it was dried at 110 ° C. for 5 minutes and further at 140 ° C. for 10 minutes to obtain a cellulose acylate film shown in Table 1 having a length of 500 m.

<Production of polarizing plate integrated optical compensation film 1>
A roll-like polyvinyl alcohol film having a thickness of 80 μm continuously dyed in an aqueous iodine solution was stretched 5 times in the transport direction and dried to obtain a polarizing film. A saponified cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) is applied to one surface of the polarizing film, and a saponified first retardation region 1 is applied to the other surface of the polarizing film. Were bonded using a polyvinyl alcohol-based adhesive so as to be orthogonal to the absorption axis of the polarizing film (that is, parallel to the transmission axis of the polarizing film). Subsequently, the above-described second retardation region 2 was bonded to the first retardation region 1 side using an adhesive to produce a polarizing plate integrated optical compensation film 1.

<Preparation of polarizing plate integrated optical compensation film 2>
A saponified cellulose triacetate film is applied to one side of the polarizing film formed in the same manner as described above, and the saponified first retardation region 1 is applied to the other side of the polarizing film as the slow axis of the polarizing film. Bonding was performed using a polyvinyl alcohol-based adhesive at right angles (that is, parallel to the transmission axis of the polarizing film). Subsequently, the above-described second retardation region 1 was bonded to the first retardation region 1 side using an adhesive to produce a polarizing plate integrated optical compensation film 2.
<Preparation of polarizing plate integrated optical compensation film 3>
A saponified cellulose triacetate film is applied to one surface of the polarizing film formed in the same manner as described above, and the first retardation region 2 is saponified to the other surface, the slow axis of which is the absorption axis of the polarizing film. Bonding was performed using a polyvinyl alcohol-based adhesive at right angles (that is, parallel to the transmission axis of the polarizing film). Subsequently, the above-described second retardation region 3 was bonded to the first retardation region 2 side using an adhesive to produce a polarizing plate integrated optical compensation film 3.

<Preparation of polarizing plate integrated optical compensation film 4>
A saponified cellulose triacetate film was bonded to one surface of the polarizing film formed in the same manner as described above, and the second retardation region 2 saponified to the other surface was bonded using a polyvinyl alcohol-based adhesive. . Subsequently, the first retardation region 1 is disposed on the second retardation region 2 side so that the slow axis thereof is parallel to the absorption axis of the polarizing film (that is, orthogonal to the transmission axis of the polarizing film). Were bonded together to produce a polarizing plate integrated optical compensation film 4.
<Preparation of polarizing plate integrated optical compensation film 5>
A saponified cellulose triacetate film was bonded to one surface of the polarizing film formed in the same manner as described above, and the saponified second retardation region 3 was bonded to the other surface using a polyvinyl alcohol-based adhesive. . Subsequently, the first retardation region 2 is disposed on the second retardation region 3 side so that its slow axis is parallel to the absorption axis of the polarizing film (that is, orthogonal to the transmission axis of the polarizing film). Were bonded together to produce a polarizing plate integrated optical compensation film 5.

<Preparation of polarizing plate A>
A polarizing film was produced in the same manner, and a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was saponified and attached to one side of the polarizing film using a polyvinyl alcohol-based adhesive. . In the same manner, the protective film 1 having a thickness of 60 μm manufactured as described above was attached to the other surface of the polarizing film to form a polarizing plate A.
<Preparation of polarizing plate B>
A polarizing film was produced in the same manner, and a commercially available cellulose acetate film (Fujitac T40UZ, manufactured by Fuji Photo Film Co., Ltd., Re = 1 nm, Rth = 35 nm, thickness 40 μm) was subjected to saponification treatment, and a polyvinyl alcohol adhesive Was attached to both surfaces of the polarizing film to form a polarizing plate B.

Next, various liquid crystal display devices were manufactured using the polarizing plate-integrated optical compensation film prepared above, and light leakage was evaluated. In addition, the polarizing plate-integrated optical compensation film produced in a long shape was cut into a predetermined size and then incorporated into a liquid crystal display device [Example 1]
The produced polarizing plate-integrated optical compensation film 1 is placed on one of the produced IPS mode liquid crystal cells so that the slow axis of the first retardation region 1 is parallel to the rubbing direction of the liquid crystal cell (that is, the first Paste so that the slow axis of one phase difference region 1 is parallel to the slow axis of the liquid crystal molecules of the liquid crystal cell during black display) and the second phase difference region 2 side is on the liquid crystal cell side It was. Subsequently, the polarizing plate A is pasted on the other side of the IPS mode liquid crystal cell so that the protective film 1 side is on the liquid crystal cell side and the polarizing plate integrated optical compensation film 1 is in a crossed Nicols arrangement. A liquid crystal display device was produced. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 60 ° was 0.07%.

[Example 2]
The produced polarizing plate-integrated optical compensation film 2 is placed on one of the produced IPS mode liquid crystal cells so that the slow axis of the first retardation region 1 is parallel to the rubbing direction of the liquid crystal cell (that is, the first Paste so that the slow axis of one retardation region 1 is parallel to the slow axis of the liquid crystal molecules of the liquid crystal cell during black display) and the second retardation region 1 surface side is the liquid crystal cell side It was. Subsequently, a polarizing plate B was attached to the other side of the IPS mode liquid crystal cell so as to be in a crossed Nicols arrangement with respect to the polarizing plate integrated optical compensation film 2 to produce a liquid crystal display device. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 60 ° was 0.11%.

[Example 3]
The produced polarizing plate-integrated optical compensation film 3 is placed on one of the produced IPS mode liquid crystal cells so that the slow axis of the first retardation region 2 is parallel to the rubbing direction of the liquid crystal cell (that is, the first Paste so that the slow axis of one retardation region 2 is parallel to the slow axis of the liquid crystal molecules of the liquid crystal cell during black display), and the second retardation region 3 surface side is the liquid crystal cell side. It was. Subsequently, a polarizing plate B was attached to the other side of the IPS mode liquid crystal cell so as to be in a crossed Nicols arrangement with the polarizing plate integrated optical compensation film 3 to produce a liquid crystal display device. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 60 ° was 0.13%.

[Example 4]
The produced polarizing plate-integrated optical compensation film 4 is placed on one of the IPS mode liquid crystal cells produced above so that the slow axis of the first retardation region 1 is perpendicular to the rubbing direction of the liquid crystal cell (ie, the first Paste so that the slow axis of one retardation region 1 is perpendicular to the slow axis of the liquid crystal molecules of the liquid crystal cell during black display) and the first retardation region 1 surface side is the liquid crystal cell side It was. Subsequently, the polarizing plate A is pasted on the other side of the IPS mode liquid crystal cell so that the protective film 1 side is on the liquid crystal cell side and the polarizing plate integrated optical compensation film 4 is in a crossed Nicols arrangement. A liquid crystal display device was produced. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 60 ° was 0.07%.

[Example 5]
The produced polarizing plate-integrated optical compensation film 5 is placed on one of the IPS mode liquid crystal cells produced above so that the slow axis of the first retardation region 2 is orthogonal to the rubbing direction of the liquid crystal cell (that is, the first Paste so that the slow axis of one retardation region 2 is perpendicular to the slow axis of the liquid crystal molecules of the liquid crystal cell during black display) and the first retardation region 2 surface side is the liquid crystal cell side It was. Subsequently, a polarizing plate B was attached to the other side of the IPS mode liquid crystal cell so as to be in a crossed Nicols arrangement with respect to the polarizing plate integrated optical compensation film 5 to produce a liquid crystal display device. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 60 ° was 0.12%.

[Example 6]
Orientation of liquid crystal molecules when the polarizing plate-integrated optical compensation film 5 is applied to one of the ferroelectric liquid crystal cells produced above and the slow axis of the first retardation region 2 is applied with a DC voltage to the liquid crystal cell. So as to be perpendicular to the direction (that is, the slow axis of the first retardation region 2 is perpendicular to the slow axis of the liquid crystal molecules of the liquid crystal cell during black display) and the first retardation region 2 It was pasted so that the surface side was the liquid crystal cell side. Subsequently, a polarizing plate B was attached to the other side of the ferroelectric liquid crystal cell so as to be in a crossed Nicols arrangement with respect to the polarizing plate integrated optical compensation film 5 to produce a liquid crystal display device. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 60 ° was 0.12%.

[Comparative Example 1]
A commercially available polarizing plate (HLC2-5618, manufactured by Sanlitz Co., Ltd.) was attached to both sides of the produced IPS mode liquid crystal cell in a crossed Nicol arrangement to produce a liquid crystal display device. An optical compensation film was not used. In the liquid crystal display device, as in Example 1, the polarizing plate was attached so that the transmission axis of the polarizing plate on one side was parallel to the rubbing direction of the liquid crystal cell. The leakage light of the liquid crystal display device thus manufactured was measured. Light leakage when observed from the left oblique direction of 60 ° was 0.55%.

[Comparative Example 2]
Similarly to Example 5, the manufactured polarizing plate-integrated optical compensation film 5 is placed on one of the IPS mode liquid crystal cells manufactured as described above, except that the slow axis of the first retardation region 2 is parallel to the rubbing direction of the liquid crystal cell. (That is, the slow axis of the first retardation region 2 is parallel to the slow axis of the liquid crystal molecules of the liquid crystal cell during black display), and the first retardation region 2 surface side is liquid crystal Affixed to the cell side. Subsequently, a polarizing plate B was attached to the other side of the IPS mode liquid crystal cell so as to be in a crossed Nicols arrangement with respect to the polarizing plate integrated optical compensation film 5 to produce a liquid crystal display device. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 60 ° was extremely large as 2.36%.

It is the schematic which shows the pixel area example of the liquid crystal display device of this invention. It is the schematic which shows an example of the liquid crystal display device of this invention. It is the schematic which shows the other example of the liquid crystal display device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal element pixel area 2 Pixel electrode 3 Display electrode 4 Rubbing direction 5a, 5b Director of liquid crystal compound at the time of black display 6a, 6b Director of liquid crystal compound at the time of white display 7a, 7b, 19a, 19b Protective film for polarizing film 8, 20 Polarizing film 9, 21 Polarizing transmission axis 10 of polarizing film First retardation region 11 Slow axis 12 of first retardation region Second retardation region 13, 17 Cell substrate 14, 18 Cell substrate rubbing direction 15 Liquid crystal Layer 16 Slow axis direction of liquid crystal layer

Claims (14)

A polarizing plate integrated optical compensation film having at least a polarizing film, a first retardation region, and a second retardation region,
Retardation of the first retardation region defined by Re = (nx−ny) × d using the in-plane refractive indexes nx and ny (nx> ny), the refractive index nz in the thickness direction, and the thickness d. Re is 20 nm to 150 nm, the value Nz of the first retardation region defined by Nz = (nx−nz) / (nx−ny) is 1.5 to 7, and the in-plane of the second retardation region Of the second retardation region defined by Rth = {(nx + ny) / 2−nz} × d is -80 nm. The refractive index nx is substantially equal to ny, nx <nz, and Rth = {(nx + ny) / 2−nz} × d. A polarizing plate integrated optical compensation film having a thickness of ˜−400 nm and at least one of the first retardation region and the second retardation region is cellulose acetate propionate or a film containing cellulose propionate. 2. The cellulose acylate film according to claim 1, wherein the cellulose acetate propionate or the film containing cellulose propionate is a cellulose acylate film in which the degree of acyl substitution with a hydroxyl group of cellulose satisfies all of the following formulas (I) to (III): Polarizing plate integrated optical compensation film.
(I) 2.82 ≦ SA + SP ≦ 3
(II) 0 ≦ SA ≦ 1.7
(III) 1.3 ≦ SP ≦ 2.9
(In the formula, SA and SP represent the substitution degree of the acyl group substituted with the hydroxyl group of cellulose, SA is the substitution degree of the acetyl group, and SP is the substitution degree of the propionyl group.) The polarizing film, the first retardation region, and the second retardation region are arranged in this order, and the slow axis of the first retardation region is substantially the transmission axis of the polarizing film. 3. The polarizing plate-integrated optical compensation film according to claim 1 or 2, which is parallel. The polarizing film, the second retardation region, and the first retardation region are arranged in this order, and the slow axis of the first retardation region is substantially perpendicular to the transmission axis of the polarizing film. The polarizing plate-integrated optical compensation film according to claim 1 or 2. At least a first polarizing film, a first retardation region, a second retardation region, a liquid crystal cell having a liquid crystal layer sandwiched between a pair of substrates, and a second polarizing film, wherein the liquid crystal molecules at the time of black display A liquid crystal display device oriented substantially parallel to the surface of the substrate,
Retardation of the first retardation region defined by Re = (nx−ny) × d using the in-plane refractive indexes nx and ny (nx> ny), the refractive index nz in the thickness direction, and the thickness d. Re is 20 nm to 150 nm, the value Nz of the first retardation region defined by Nz = (nx−nz) / (nx−ny) is 1.5 to 7, and the in-plane of the second retardation region Of the second retardation region defined by Rth = {(nx + ny) / 2−nz} × d is -80 nm. The refractive index nx is substantially equal to ny, nx <nz, and Rth = {(nx + ny) / 2−nz} × d. ~ -400nm,
At least one of the first retardation region and the second retardation region is cellulose acetate propionate or a film containing cellulose propionate, and the transmission axis of the first polarizing film is a liquid crystal molecule of black display A liquid crystal display device parallel to the slow axis direction. The first polarizing film, the first retardation region, the second retardation region, and the liquid crystal cell are arranged in this order, and the slow axis of the first retardation region is that of the first polarizing film. The liquid crystal display device according to claim 5, wherein the liquid crystal display device is substantially parallel to the transmission axis. The first polarizing film, the second retardation region, the first retardation region, and the liquid crystal cell are arranged in this order, and the slow axis of the first retardation region is the transmission axis of the first polarizing film. The liquid crystal display device according to claim 5, wherein the liquid crystal display device is substantially orthogonal to. A pair of protective films disposed between at least one of the first polarizing film and the second polarizing film, and a thickness direction retardation Rth of the protective film on the side close to the liquid crystal layer of the pair of protective films. The liquid crystal display device according to claim 5, wherein the liquid crystal display device is 40 nm to −40 nm. A pair of protective films disposed between at least one of the first polarizing film and the second polarizing film, and a thickness direction retardation Rth of the protective film on the side close to the liquid crystal layer of the pair of protective films. The liquid crystal display device according to claim 5, which is 20 nm to −20 nm. A pair of protective films disposed between at least one of the first polarizing film and the second polarizing film, and a thickness of the protective film on the side close to the liquid crystal layer of the pair of protective films is 60 μm or less. Item 10. The liquid crystal display device according to any one of Items 5 to 9. A pair of protective films disposed between the first polarizing film and / or the second polarizing film, wherein the protective film on the side close to the liquid crystal layer is a cellulose acylate film or a norbornene-based film The liquid crystal display device according to any one of claims 5 to 10. The liquid crystal display device according to claim 5, wherein the first retardation region and / or the second retardation region is adjacent to the first polarizing film and / or the second polarizing film. The said 1st phase difference area | region or the said 2nd phase difference area | region is arrange | positioned in the position nearer to the board | substrate on the opposite side to the visual recognition side among a pair of board | substrates of a liquid crystal cell. Liquid crystal display device. The cellulose acylate film in which the cellulose acetate propionate or the film containing cellulose propionate satisfies all of the following formulas (I) to (III) in terms of acyl substitution with hydroxyl groups of cellulose: The liquid crystal display device according to any one of the above.
(I) 2.82 ≦ SA + SP ≦ 3
(II) 0 ≦ SA ≦ 1.7
(III) 1.3 ≦ SP ≦ 2.9
(In the formula, SA and SP represent the substitution degree of the acyl group substituted with the hydroxyl group of cellulose, SA is the substitution degree of the acetyl group, and SP is the substitution degree of the propionyl group.)

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