JP2006267333A - Optical compensating film and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical compensation film contributing to improvement of view angle characteristics of a liquid crystal display device during black display and reduction of color slurring from an oblique direction. <P>SOLUTION: The optical compensation film has a transparent film such that the ratio Re/Rth (450 nm) of Re and Rth at a wavelength of 450 nm is 0.39 to 0.95 time as large as the Re/Rth (550 nm) at a wavelength of 550 nm, the ratio Re/Rth (650 nm) at a wavelength of 650 nm is 1.04 to 2.20 times as large as the Re/Rth (550 nm), and the retardation Rth along the thickness at the wavelength of 550 nm is 70 to 400 nm, and an optical anisotropic layer formed of a composition containing a liquid crystal compound, wherein the angle of intersection of the alignment mean direction of the axis of molecule symmetry of the liquid crystal compound at least on the interface on the side of the transparent film and the slow axis in a surface of the transparent film is nearly 0 or 90°. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical compensation film and a liquid crystal display device using the same.

  The liquid crystal display device has a liquid crystal cell and a polarizing plate. The polarizing plate generally has a protective film and a polarizing film. For example, a polarizing film made of a polyvinyl alcohol film is dyed with iodine, stretched, and both surfaces thereof are laminated with a protective film. In the transmissive liquid crystal display device, polarizing plates are attached to both sides of the liquid crystal cell, and one or more optical compensation films may be disposed. In a reflective liquid crystal display device, the reflector, liquid crystal cell, one or more optical compensation films, and a polarizing plate are usually arranged in this order. The liquid crystal cell includes a liquid crystal molecule, two substrates for encapsulating the liquid crystal molecule, and an electrode layer for applying a voltage to the liquid crystal molecule. The liquid crystal cell performs ON / OFF display depending on the alignment state of liquid crystal molecules, and can be applied to both transmission and reflection types. TN (Twisted Nematic), IPS (In-Plane Switching), OCB (Optically Compensatory Bend). ), VA (Vertically Aligned), and ECB (Electrically Controlled Birefringence) have been proposed.

  Among such LCDs, for applications that require high display quality, a 90 degree twisted nematic liquid crystal display device (hereinafter referred to as a TN mode) that uses nematic liquid crystal molecules having positive dielectric anisotropy and is driven by a thin film transistor. Is mainly used. However, although the TN mode has excellent display characteristics when viewed from the front, the contrast is reduced when viewed from an oblique direction, or gradation inversion that reverses the brightness in gradation display occurs. There is a viewing angle characteristic that the display characteristic is deteriorated, and this improvement is strongly demanded. In particular, the market demand for contrast is strong, and in particular, there is a strong demand for further improvement in the vertical and horizontal viewing angle contrast.

As an optical compensation film that expands the viewing angle of a TN mode liquid crystal layer liquid crystal display cell, a compensation film in which a discotic compound is fixed in a hybrid alignment state has been put into practical use (for example, Patent Document 1). In this method, since the nematic liquid crystal cell composed of rod-shaped liquid crystals is compensated by the discotic compound, it is possible to compensate for incident light from an oblique direction, and the display viewing angle can be greatly expanded. is there. However, in this method, compensation for the deviation from 90 degrees of the polarization angle in the oblique direction of the polarizing plate is not sufficiently taken into account, so that it cannot be said that a sufficient viewing angle contrast is obtained. Also proposed is a method of improving the viewing angle characteristics by controlling the chromatic dispersion of the optical compensation film. It has been difficult to obtain a good viewing angle characteristic only by controlling a conventionally known optical parameter of chromatic dispersion by the method described in this document.

Japanese Patent No. 2587398 JP2003-202572

  An object of the present invention is to provide a liquid crystal display device in which a liquid crystal cell is accurately optically compensated and has a high viewing angle contrast, particularly a TN mode liquid crystal display device. The present invention also provides an optical compensation film that optically compensates for a liquid crystal cell, particularly a TN mode liquid crystal cell, and contributes to improvement in viewing angle contrast and reduction in black luminance floating in the visible light wavelength region during black display. Is an issue.

Means for solving the problems of the present invention are as follows.
[1] An optical compensation film having at least two layers of a transparent film and an optically anisotropic layer having in-plane optical anisotropy,
When the in-plane retardation of the transparent film is Re and the retardation in the thickness direction is Rth, the ratio Re / Rth (450 nm) of Re to Rth at a wavelength of 450 nm is Re / Rth (550 nm) at a wavelength of 550 nm. 0.39 to 0.95 times, Re / Rth (650 nm) at a wavelength of 650 nm is 1.04 to 2.20 times Re / Rth (550 nm), and Rth at a wavelength of 550 nm is 70 nm to 400 nm. Yes,
The optically anisotropic layer is formed from a composition containing a liquid crystalline compound, and in the optically anisotropic layer, the molecules of the liquid crystalline compound are fixed in an aligned state, and the molecular symmetry axis of the liquid crystalline compound is An optical system in which the crossing angle between the direction in which the orientation average direction at the interface on the transparent film side is orthogonally projected into the transparent film plane and the slow axis in the plane of the transparent film is approximately 0 degrees or approximately 90 degrees Compensation film.
[2] The optical compensation film according to [1], wherein the liquid crystalline compound is a discotic liquid crystalline compound.

[3] A pair of oppositely arranged substrates having electrodes on at least one side, and a nematic liquid crystal material sandwiched between the pair of substrates, and the liquid crystal molecules of the nematic liquid crystal material are surfaces of the pair of substrates when not driven And a liquid crystal cell having a liquid crystal layer having a product Δn · d of thickness d (micron) and refractive index anisotropy Δn of 0.2 to 1.5 microns, and the liquid crystal A first and second polarizing film disposed with a cell sandwiched therebetween, and a transparent film between at least one of the first and second polarizing films and the liquid crystal cell,
When the in-plane retardation of the transparent film is Re and the retardation in the thickness direction is Rth, the Re / Rth ratio Re / Rth (450 nm) at a wavelength of 450 nm is Re / Rth (550 nm) at a wavelength of 550 nm. The Re / Rth (650 nm) at a wavelength of 650 nm is 1.04 to 2.20 times the Re / Rth (550 nm), and the transparent film has an Rth at a wavelength of 550 nm. Is 70 nm to 400 nm, and has at least one optically anisotropic layer between the transparent film and the liquid crystal cell, and the optically anisotropic layer is formed from a composition containing a liquid crystalline compound. In the optically anisotropic layer, the molecules of the liquid crystalline compound are fixed in an aligned state, and the molecular symmetry axis of the liquid crystalline compound is at least Also, the crossing angle between the direction in which the orientation average direction at the interface on the transparent film side is orthogonally projected in the plane of the transparent film and the slow axis in the plane of the transparent film is approximately 0 degree or 90 degrees [3. ] Liquid crystal display device.
[4] The liquid crystal display device according to [4], wherein the liquid crystalline compound is a discotic liquid crystalline compound.
[5] The liquid crystal display device according to [3] or [4], wherein the liquid crystal cell is a TN mode liquid crystal cell.

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

  In 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, and “polarizing plate” is a laminate having a transparent protective film for protecting the polarizing film on at least one side of the “polarizing film”. Means.

In the present specification, the “molecular symmetry axis” means a symmetry axis when the molecule has a rotational symmetry axis, but does not require that the molecule is rotationally symmetric in a strict sense. In general, the molecular symmetry axis of the discotic liquid crystalline compound coincides with the axis perpendicular to the disc surface passing through the center of the disc surface, and the rod-like liquid crystalline compound coincides with the long axis of the molecule. In the present specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. In the present invention, Re (λ) is a value measured using KOBRA 21ADH (manufactured by Oji Scientific Instruments) with light having a wavelength of λ nm incident in the normal direction of the film. Rth (λ) is a light having a wavelength of λ nm from the direction inclined by + 40 ° with respect to the normal direction of the film, with Re (λ) and the slow axis (determined by KOBRA 21ADH) as the tilt axis (rotation axis). And the retardation value measured by making light of wavelength λ nm incident from a direction inclined −40 ° with respect to the film normal direction with the slow axis as the tilt axis (rotation axis). A value calculated by KOBRA 21ADH based on retardation values measured in three directions in total. Here, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59).
The KOBRA 21ADH calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness.

  The present invention has been completed based on the knowledge obtained as a result of intensive studies by the present inventors. In-plane retardation and retardation in the thickness direction are selected by appropriately selecting materials and manufacturing methods. By using an optical compensation film having a transparent film with an optically optimal value by independently controlling the chromatic dispersion of the liquid crystal, it is possible to compensate for the viewing angle of the black state of a liquid crystal cell, particularly an OCB mode liquid crystal cell, at almost all wavelengths It is to make. As a result, in the liquid crystal display device of the present invention, light leakage in an oblique direction during black display is reduced, and the viewing angle contrast is remarkably improved. In addition, the liquid crystal display device of the present invention can suppress light leakage in an oblique direction during black display in almost all visible light wavelength regions. Can also be improved.

BEST MODE FOR CARRYING OUT THE INVENTION

The operation of the present invention will be described below with reference to the drawings.
FIG. 1 shows a schematic diagram of a configuration example of a liquid crystal display device of the present invention. The TN mode liquid crystal display device shown in FIG. 1 has a liquid crystal cell composed of a liquid crystal layer 7 in which the liquid crystal bends with respect to the substrate surface when a voltage is applied, that is, black display, and substrates 6 and 8 sandwiching the liquid crystal layer 7. The substrates 6 and 8 have a liquid crystal surface subjected to alignment treatment, and the rubbing direction is indicated by an arrow RD. In the case of the back surface, it is indicated by a broken line arrow. Polarizing films 1 and 101 are disposed with the liquid crystal cell interposed therebetween. The transmission axes 2 and 102 of the polarizing films 1 and 101 are arranged orthogonal to each other and at an angle of 0 degree or 90 degrees with the RD direction of the liquid crystal layer 7 of the liquid crystal cell. Transparent films 13a and 113a and optically anisotropic layers 5 and 9 are disposed between the polarizing films 1 and 101 and the liquid crystal cell, respectively. The transparent films 13a and 113a are arranged such that their slow axes 14a and 114a are parallel to the directions of the transmission axes 2 and 102 of the polarizing films 1 and 101 adjacent thereto, respectively. The optically anisotropic layers 5 and 9 have optical anisotropy expressed by the orientation of the liquid crystalline compound.

  The liquid crystal cell in FIG. 1 includes a liquid crystal layer formed of an upper substrate 6 and a lower substrate 8 and liquid crystal molecules 7 sandwiched therebetween. An alignment film (not shown) is formed on the surface of the substrates 6 and 8 that contacts the liquid crystal molecules 7 (hereinafter sometimes referred to as “inner surface”). Is controlled in a parallel direction with a pretilt angle. Further, on the inner surfaces of the substrates 6 and 8, a transparent electrode (not shown) capable of applying a voltage to the liquid crystal layer made of the liquid crystal molecules 7 is formed. In the present invention, the product Δn · d of the thickness d (micron) of the liquid crystal layer and the refractive index anisotropy Δn is preferably 0.1 to 1.5 microns, and further 0.2 to 1. It is more preferably 5 microns, more preferably 0.2 to 1.2 microns, and even more preferably 0.6 to 0.9 microns. In these ranges, since the white display luminance when white voltage is applied is high, a bright and high-contrast display device can be obtained. The liquid crystal material to be used is not particularly limited, but in an aspect in which an electric field is applied between the upper and lower substrates 6 and 8, a liquid crystal material having a positive dielectric anisotropy such that the liquid crystal molecules 7 respond in parallel to the electric field direction is used. use.

  For example, when the liquid crystal cell is a TN mode liquid crystal cell, a nematic liquid crystal material having a positive dielectric anisotropy between Δn = 0.08 and Δε = 5 is used between the upper and lower substrates 6 and 8. it can. The thickness d of the liquid crystal layer is not particularly limited, but can be set to about 6 microns when a liquid crystal having the above characteristics is used. In order to obtain sufficient brightness when white voltage is applied, the brightness during white display changes depending on the thickness Δ and the product Δn · d of refractive index anisotropy Δn when white voltage is applied. The Δn · d of the liquid crystal layer in the non-application state is preferably set to be in the range of 0.6 to 1.5 microns.

  Note that in a TN mode liquid crystal display device, a chiral material may be added to reduce alignment defects. In addition, a multi-domain structure may be used in the TN mode. A multi-domain structure refers to a structure in which one pixel of a liquid crystal display device is divided into a plurality of regions. For example, in the TN mode, a multi-domain structure is preferable because the viewing angle characteristics of luminance and color tone are improved. Specifically, each pixel is composed of two or more (preferably 4 or 8) regions in which the initial alignment state of the liquid crystal molecules is different from each other, and averaging is performed. Can be reduced. Further, the same effect can be obtained even if each pixel is constituted by two or more different regions where the alignment direction of liquid crystal molecules continuously changes in a voltage application state.

  In the transparent films 13a and 113a, the ratio Re / Rth (450 nm) of Re and Rth at a wavelength of 450 nm is 0.39 to 0.95 times Re / Rth (550 nm) at a wavelength of 550 nm, and Re / Rth at a wavelength of 650 nm. (650 nm) satisfies the relationship of 1.04 to 2.20 times Re / Rth (550 nm), and Rth is 70 to 400 nm. The transparent films 13a and 113a may function as a support for the optically anisotropic layers 5 and 9, or may function as a protective film for the polarizing film 1 and the polarizing film 101, or both of them. It may have a function. That is, the polarizing film 1, the transparent film 13a and the optically anisotropic layer 5, or the polarizing film 101, the transparent film 113a and the optically anisotropic layer 9 are incorporated into the liquid crystal display device as an integrated laminate. Alternatively, they may be incorporated as individual members. In addition, a protective film for a polarizing film may be separately disposed between the transparent film 13a and the polarizing film 1 or between the transparent film 113a and the polarizing film 101. Preferably they are not arranged. The slow axis 14a of the transparent film 13a and the slow axis 114a of the transparent film 113a are preferably substantially parallel or orthogonal to each other. If the slow axes 14a and 114a of the transparent films 13a and 113a are orthogonal to each other, the birefringence of the respective transparent films cancel each other, thereby reducing the deterioration of the optical characteristics of light perpendicularly incident on the liquid crystal display device. can do. Further, in the aspect in which the slow axes 14a and 114a are parallel to each other, when there is a residual phase difference in the liquid crystal layer, the phase difference can be compensated by birefringence of the protective film.

  Regarding the transmission axes 2 and 102 of the polarizing films 1 and 101, the slow axis directions 14a and 114a of the transparent films 13a and 113a, and the alignment direction of the liquid crystal molecules 7, the materials used for each member, the display mode, and the laminated structure of the members Adjust to the optimal range according to the above. That is, the transmission axis 2 of the polarizing film 1 and the transmission axis 102 of the polarizing film 101 are arranged so as to be substantially orthogonal to each other. However, the liquid crystal display device of the present invention is not limited to this configuration.

  The optically anisotropic layers 5 and 9 are disposed between the transparent films 13a and 113a and the liquid crystal cell. The optically anisotropic layers 5 and 9 are layers formed from a composition containing a liquid crystal compound, for example, a rod-like compound or a discotic compound. In the optically anisotropic layer, the molecules of the liquid crystalline compound are fixed in a predetermined alignment state. The molecular symmetry axes of the liquid crystalline compounds in the optically anisotropic layers 5 and 9 and the orientation average directions 5a and 9a at least at the interface on the transparent films 13a and 113a side, and the slow axis 14a in the plane of the transparent films 13a and 113a And 114a intersect at approximately 0 degrees or approximately 90 degrees (in FIG. 1, an example of intersecting at 90 degrees is shown). When arranged in such a relationship, the optically anisotropic layer 5 or 9 causes retardation with respect to the incident light from the normal direction, does not cause light leakage, and is incident on the incident light from the oblique direction. In contrast, the effects of the present invention can be sufficiently achieved. Even at the interface on the liquid crystal cell side, the orientation average direction of the molecular symmetry axes of the optically anisotropic layers 5 and 9 is about 0 degrees or about 90 degrees with respect to the slow axes 14a and 114a in the plane of the transparent films 13a and 113a. Preferably there is. Further, the orientation average direction 5a on the polarizing film side (transparent film interface side) of the molecular symmetry axis of the liquid crystalline compound of the optically anisotropic layer 5 is substantially 0 degree with the transmission axis 2 of the polarizing film 1 located closer to the optically anisotropic layer 5. It is preferable to arrange at approximately 90 degrees (in FIG. 1, an arrangement of 0 degrees is shown). Similarly, the orientation average direction 9a on the polarizing film side (transparent film interface side) of the molecular symmetry axis of the liquid crystalline compound of the optically anisotropic layer 9 is substantially 0 degree with the transmission axis 102 of the polarizing film 101 located closer to the optically anisotropic layer 9. Or it is preferable to arrange at approximately 90 degrees (in FIG. 1, the arrangement of 0 degrees is shown). When arranged in such a relationship, optical switching can be performed according to the sum of the retardation generated in the optically anisotropic layer 5 or 9 and the retardation generated in the liquid crystal layer, and incident light from an oblique direction can be obtained. Thus, the effects of the present invention can be sufficiently achieved.

Next, the principle of image display of the liquid crystal display device of FIG. 1 will be described.
In a driving state in which a driving voltage corresponding to black is applied to the respective transparent electrodes (not shown) of the liquid crystal cell substrates 6 and 8, the liquid crystal molecules 7 in the liquid crystal layer are in a state where the liquid crystal molecules stand more from the initial twist alignment. The polarization state of the incident light hardly changes in the front direction. Since the transmission axes 2 and 102 of the polarizing films 1 and 101 are orthogonal to each other, the light incident from the lower side (for example, the back electrode) is polarized by the polarizing film 101 and passes through the liquid crystal cells 5 to 8 while maintaining the polarization state. Passes and is blocked by the polarizing film 1. That is, the liquid crystal display device of FIG. 1 realizes black display in the driving state. On the other hand, in a driving state in which a driving voltage corresponding to white is applied to a transparent electrode (not shown), the liquid crystal molecules 7 in the liquid crystal layer are deformed close to a twist alignment state, and the polarization plane of incident light is liquid crystal By passing through the cell, it rotates about 90 degrees and passes through the polarizing film 1. That is, a white display is obtained.

  Conventionally, in the TN mode, there has been a problem that even if the front contrast is high, the contrast decreases in an oblique direction. In Patent Document 1, in order to increase the viewing angle contrast in the oblique direction, high contrast can be obtained by compensation of the liquid crystal cell and the optically anisotropic layer, but the transmission axes 2 of the upper and lower polarizing films 1 and 101 and The crossing angle of 102 is 90 ° perpendicular to the front, but it is not sufficiently considered that it is not 90 ° when viewed obliquely. Due to this factor, leakage light occurs in the oblique direction, and the contrast is low. There is a problem of lowering. In the liquid crystal display device of the present invention having the configuration shown in FIG. 1, paying attention to this point of view, Re / Rth in R, G, and B does not match each other and the transparent film 13a (or 113a) having optical characteristics satisfying a specific condition is satisfied. ) Is used to reduce light leakage in an oblique direction during black display and improve contrast.

More specifically, in the present invention, by using the transparent film having the optical characteristics, the light of each wavelength of R, G, and B incident in an oblique direction is optical with different slow axis and retardation for each wavelength. It is possible to compensate. Further, the optically anisotropic layer (5 and 9 in FIG. 1) in which the orientation of the liquid crystalline compound is fixed is compared with the orientation average direction at the transparent film side interface of the symmetry axis of the molecules of the liquid crystalline compound and the slow phase of the transparent film. Arranging so that the axis intersects at 0 degree or 90 degrees makes it possible to perform a unique compensation method of TN alignment at all wavelengths. As a result, the viewing angle contrast of black display is greatly improved, and the coloring in the viewing angle direction of black display is further reduced.
Here, in this specification, as wavelengths of R, G, and B, R has a wavelength of 650 nm, G has a wavelength of 550 nm, and B has a wavelength of 450 nm. The wavelengths of R, G, and B are not necessarily represented by these wavelengths, but are considered to be suitable wavelengths for defining the optical characteristics that exhibit the effects of the present invention.

  In particular, the present invention focuses on Re / Rth, which is the ratio of Re and Rth of the transparent film. This is because the value of Re / Rth determines the two intrinsic polarization axes in the propagation of light traveling obliquely through the birefringent medium. The axes of the two intrinsic polarizations in the propagation of light traveling obliquely through the birefringent medium correspond to the major axis and minor axis directions of the cross section formed when the refractive index ellipsoid is cut in the normal direction of the light traveling direction. To do. FIG. 2 shows the relationship between Re / Rth and the direction of one axis of two intrinsic polarizations, that is, the angle of the slow axis in this case, when light traveling in an oblique direction is incident on the transparent film used in the present invention. An example of the calculation result is shown. In FIG. 2, the propagation direction of light is assumed to be azimuth = 45 degrees and polar angle = 34 degrees. As shown in FIG. 2, the angle of the slow axis does not depend on the wavelength of incident light, but is uniquely determined by Re / Rth. How the polarization state of incident light changes by passing through the transparent film is mainly determined by the slow axis orientation of the transparent film and the retardation of the transparent film. Regardless of the G and B wavelengths, the Re / Rth values are almost the same, that is, the slow axis angles are also almost the same. On the other hand, in the present invention, by specifying the Re / Rth relationship separately for each of the R, G, and B wavelengths, both the slow axis and the retardation, which are factors that mainly determine the change in the polarization state, can be obtained. Optimization is performed for each wavelength of R, G, and B. Then, when the light in the oblique direction passing through the transparent film passes through the optically anisotropic layer in which the orientation of the liquid crystalline compound is fixed and further passes through the liquid crystal layer in the bend orientation, the retardation and the upper and lower polarizing films at any wavelength. The value of Re / Rth of the transparent film is adjusted according to the wavelength so that the two factors that the apparent transmission axis deviates from the front can be compensated simultaneously. Specifically, by increasing the Re / Rth of the transparent film as the wavelength increases, the difference in polarization state in R, G, and B caused by wavelength dispersion of the optically anisotropic layer and the liquid crystal cell layer is eliminated. Became possible. As a result, complete compensation is possible and reduction in contrast is reduced. If the parameters of the film are determined with R, G, and B representing the entire visible light region, almost complete compensation can be achieved in the entire visible light region.

  Here, polar angle and azimuth angle are defined. The polar angle is the normal direction of the film surface, that is, the inclination angle from the z-axis in FIG. 1. For example, the normal direction of the film surface is the direction of polar angle = 0 degrees. The azimuth angle represents an azimuth rotated counterclockwise with respect to the positive direction of the x-axis. For example, the positive direction of the x-axis is the direction of the azimuth angle = 0 degrees, and the positive direction of the y-axis is Azimuth angle = 90 degrees. The oblique direction in which black display is most problematic is that the polarization axis of the polarizing layer is ± 45, so that the polar angle is not 0 degrees and the azimuth angle = 0 degrees, 90 degrees, 180 degrees. It mainly refers to the case of 270 degrees.

  In order to explain the effect of the present invention in more detail, the polarization state of the light incident on the liquid crystal display device is shown on the Poincare sphere in FIGS. In FIG. 3, the S2 axis is an axis that penetrates vertically from the top to the bottom of the drawing, and FIG. 3 is a view of the Poincare sphere viewed from the positive direction of the S2 axis. Further, since FIG. 3 is shown in a plan view, the displacement of the point before and after the change of the polarization state is indicated by a straight arrow in the figure, but actually it passes through the liquid crystal layer or the transparent film. The change in the polarization state due to this is expressed by rotating a specific angle around a specific axis determined according to each optical characteristic on the Poincare sphere.

  In the configuration of the conventional TN mode liquid crystal display device as shown in FIG. 5, the transparent films 113a and 13a whose Re / Rth exhibits the above-described wavelength dependence are not arranged. Instead, for example, optical anisotropic Transparent supports 103a and 3a of the conductive layers 5 and 9 are arranged. The transparent supports 103a and 3a are used for the purpose of supporting the optically anisotropic layers 5 and 9, and are made of a general polymer film. Accordingly, there is no wavelength dependency on Re / Rth as shown by the transparent films 113a and 13a, and the same Re and Rth are shown at any of the R, G, and B wavelengths. As a result, in the conventional OCB mode liquid crystal display device, when voltage is applied, that is, when black is displayed, the front retardation of the liquid crystal cell and the optically anisotropic layer is canceled in the front, and black is obtained. In the direction, there was a problem that light leakage of black display could not be completely suppressed. As a result, a sufficient viewing angle contrast cannot be obtained, and compensation cannot be made at all wavelengths, so that there is a problem of coloring.

  In FIG. 3, the polarization state of the R incident light is indicated by IR, the polarization state of the G incident light is indicated by IG, and the polarization state of the B incident light is indicated by IB. Further, as a configuration of a conventional TN mode liquid crystal display device, it is assumed that the transparent supports 3 and 103 in FIG. 3 have Re = 96 nm and Rth = 58 nm at any wavelength of R, G, and B. The optical anisotropic layers 5 and 9 were calculated assuming that Re = 30 nm. First, in FIG. 3, the polarization states after passing through the polarizing film 101, IR1, IG1, and IB1 are equal. Paying attention to the change in the polarization state of the B light, the B light incident from the left 60 ° shifts for each wavelength as the polarization state IB2 after passing through the transparent support 103 passes through the optically anisotropic layer 9. I can understand that. As a result, the positions of the final transition states IR6, IG6, and IB6 of the incident light of R, G, and B do not match. For this reason, the left and right black light is not completely lost, and a sufficient viewing angle contrast cannot be obtained. At the same time, light of all wavelengths cannot be blocked at the same time.

  In the present invention, the viewing angle contrast of the TN mode liquid crystal display device is improved by arranging a transparent film exhibiting specific optical characteristics. In order to explain in more detail, the result of calculating the polarization state of the R, G, B light passing through the TN mode liquid crystal display device having the configuration of the present invention shown in FIG. 1 is shown on the Poincare sphere in FIG. It was. FIG. 4 is a diagram showing changes in the polarization state of light incident from below 60 ° for R, G, and B, respectively. In the drawing, the polarization state of R incident light is indicated by IR, the polarization state of G incident light is indicated by IG, and the polarization state of B incident light is indicated by IB. The transparent films 113 and 13 have a Re / Rth (450 nm) at a wavelength of 450 nm of 0.17, a Re / Rth (550 nm) at a wavelength of 550 nm of 0.28, and a Re / Rth (650 nm) at a wavelength of 650 nm of 0.39. And Rth at a wavelength of 550 nm is assumed to be 160 nm. Re of the optically anisotropic layers 5 and 9 was assumed to be the same value as the Poincare sphere shown in FIG.

  As shown in FIG. 4, the incident R light, G light, and B light are all in the vicinity of S1 = 0 after passing through the transparent films 113a and 13a, and the Re / Rth wavelength of the transparent film 113a. Reflecting the dependency, the polarization state changes to a shifted position. This shift makes it possible to cancel the shift in the polarization state that the R light, G light, and B light receive due to the wavelength dispersion of the optically anisotropic layers 9, 5 and the liquid crystal layer 7. As a result, the light that has entered from either the left or right direction can have the same final transition point regardless of the wavelength. As a result, black light omission at the lower viewing angle can be reduced, and the contrast viewing angle can be greatly improved.

  The feature of the present invention is not only to improve the viewing angle contrast in an oblique direction, for example, an azimuth angle of 270 degrees and a polar angle of 60 degrees by using the so-called biaxiality of the transparent film adjacent to the optically anisotropic layer. By actively utilizing the relationship between the Re and Rth wavelength dispersion of the retardation of the film, the black light loss in the viewing angle direction is improved. In particular, in the TN mode, the use of a film composed of an optically anisotropic layer and a transparent film can improve the viewing angle contrast in all directions. The effect of this method is not limited by the display mode of the liquid crystal layer, and can be used for a liquid crystal display device having a liquid crystal layer of any display mode such as a TN mode, a VA mode, an IPS mode, an ECB mode, and an OCB mode.

  Further, the liquid crystal display device of the present invention is not limited to the configuration shown in FIG. 1 and may include other members. For example, a color filter may be disposed between the liquid crystal cell and the polarizing film. In the case of use as a transmission type, a cold cathode or a hot cathode fluorescent tube, or a backlight using a light emitting diode, a field emission element, or an electroluminescent element as a light source can be disposed on the back surface.

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

Next, regarding the members used in the liquid crystal display device of the present invention, the characteristics, raw materials, production methods and the like will be described in more detail, particularly focusing on the optical compensation film of the present invention.
[Optical compensation film]
The optical compensation film of the present invention contributes to an increase in the viewing angle contrast of a liquid crystal display device, particularly a TN mode liquid crystal display device, and a reduction in color shift depending on the viewing angle. The optical compensation film of the present invention may be disposed between the observer-side polarizing plate and the liquid crystal cell, or may be disposed between the rear-side polarizing plate and the liquid crystal cell, or may be disposed on both. Also good. For example, it can be incorporated into the liquid crystal display device as an independent member, or a protective film that protects the polarizing film can be provided with optical characteristics and function as a transparent film. It can also be incorporated inside the display device. The optical compensation film of the present invention has at least two layers of a transparent film and an optically anisotropic layer having optical anisotropy in the plane. You may have the orientation film which controls the orientation of the liquid crystalline compound in an optically anisotropic layer between a transparent film and an optically anisotropic layer. Moreover, as long as the optical characteristic mentioned later is satisfy | filled, the transparent film and the optically anisotropic layer may each consist of two or more layers. First, each component of the optical compensation film of the present invention will be described in detail.

[Transparent film]
In the transparent film constituting the optical compensation film of the present invention, the Re / Rth ratio Re / Rth (450 nm) at a wavelength of 450 nm in the visible light region is 0.39 to 0.95 of Re / Rth (550 nm) at a wavelength of 550 nm. Times, preferably 0.39 to 0.9 times, more preferably 0.6 to 0.8 times, and Re / Rth (650 nm) at a wavelength of 650 nm is equal to Re / Rth (550 nm). 1.04 to 2.20 times, preferably 1.1 to 1.9 times, and more preferably 1.2 to 1.7 times. Note that Re / Rth in each of R, G, and B is preferably in the range of 0.1 to 0.8.

Further, the retardation in the thickness direction (Rth) of the entire transparent film also has a function for canceling the retardation of the liquid crystal layer in the thickness direction during black display. In general, it is generally preferable that Rth at a wavelength of 550 nm is 70 nm to 400 nm. More specifically, for example, a TN mode liquid crystal cell (for example, a liquid crystal layer having a product Δn · d of a thickness d (micron) and a refractive index anisotropy Δn of 0.2 to 1.5 microns is provided. When used for optical compensation of a TN mode liquid crystal cell), it is preferably 10 to 200 nm, more preferably 20 nm to 150 nm, and even more preferably 40 to 120 nm. The Re retardation is generally 20 to 200 nm, preferably 30 to 170 nm, and more preferably 80 to 130 nm.
The thickness of the transparent film is not particularly limited, but is 110 microns or less, preferably 40 to 110 microns, and more preferably 80 to 110 microns.

  A transparent film satisfying the optical properties of Re and Rth can be produced by selecting the raw materials, the blending amount, production conditions, and the like, and adjusting these values to a desired range. Specifically, a method of mixing two or more types of polymers having different wavelength dispersions, a method of controlling the wavelength dispersion of visible light by adding an additive having absorption in the ultraviolet region or infrared region, Absorbing additive that is structurally oriented in the film thickness direction, stretching direction or non-stretching direction, method of adjusting wavelength dispersion by applying or pasting polymers having different wavelength dispersion There is a method of controlling wavelength dispersion by adjusting orientation or material uniformity by giving a non-uniform temperature distribution or ultraviolet intensity distribution in the thickness direction in the film manufacturing process.

  In the present invention, the material for the transparent film is not particularly limited. For example, it may be a stretched birefringent polymer film or an optically anisotropic layer formed by fixing a liquid crystalline compound in a specific orientation. Moreover, the transparent film is not limited to a single layer structure, and may have a laminated structure in which a plurality of layers are laminated. In the aspect of the laminated structure, the material of each layer may not be the same, and may be a laminated body of a polymer film and an optically anisotropic layer made of a liquid crystalline compound, for example. In the aspect of the laminated structure, in consideration of the thickness, a coating type laminated body including a layer formed by coating is preferable to a laminated body of stretched polymer films.

  When a liquid crystal compound is used for the production of the transparent film, since the liquid crystal compound has various alignment forms, an optically anisotropic layer prepared by fixing the liquid crystal compound in a specific alignment state is a single layer. Desired optical properties are exhibited by a layer or a laminate of a plurality of layers. That is, the transparent film may be composed of a support and one or more optically anisotropic layers formed on the support. The retardation of the whole transparent film of this aspect can be adjusted by the optical anisotropy of the optical anisotropic layer. Liquid crystal compounds can be classified into rod-like liquid crystal compounds and discotic liquid crystal compounds based on their molecular shapes. Furthermore, there are low molecular weight and high molecular weight types, respectively, and both can be used. When using a liquid crystalline compound for the production of the transparent film, it is preferable to use a rod-like liquid crystalline compound or a discotic liquid crystalline compound, and a rod-like liquid crystalline compound having a polymerizable group or a discotic liquid crystalline compound having a polymerizable group. More preferably, the compound is used.

  Moreover, the transparent film may consist of a polymer film. The polymer film may be a stretched polymer film or a combination of a coating-type polymer layer and a polymer film. As a material for the polymer film, a synthetic polymer (eg, polycarbonate, polysulfone, polyethersulfone, polyacrylate, polymethacrylate, norbornene resin, triacetylcellulose) is generally used. In addition, a cellulose acylate film using a composition in which a rod-like compound having an aromatic ring (specifically, an aromatic compound having two aromatic rings) is added to cellulose acylate is also preferable. A polymer film having desired optical properties can be produced by adjusting the type of aromatic compound, the amount added, and the stretching conditions of the film.

<Cellulose acylate film>
The cellulose acylate film that can be used as a transparent film in the present invention will be described in more detail.
By adjusting the kind and amount of a rod-shaped compound having an aromatic ring to be added (specifically, an aromatic compound having two aromatic rings), or production conditions (for example, film stretching conditions), the present invention. A cellulose acylate setate film satisfying the optical properties of the transparent film can be produced. In addition, the protective film of a polarizing plate generally consists of a cellulose acylate film. When the cellulose acylate film is used as one protective film of the polarizing plate, an optical compensation function can be added to the polarizing plate without increasing the number of components of the polarizing plate.

  In addition, when two or more rod-shaped compounds having a maximum absorption wavelength (λmax) shorter than 250 nm in the ultraviolet absorption spectrum are used in combination, Re / Rth ratios different depending on the wavelength can be obtained.

  As the raw material cotton of cellulose acylate, a known raw material can be used (for example, refer to the Japanese Society for Invention and Innovation 2001-1745). Cellulose acylate can also be synthesized by a known method (for example, see Mita et al., Wood Chemistry pages 180-190 (Kyoritsu Shuppan, 1968)). The viscosity average polymerization degree of cellulose acylate is preferably 200 to 700, more preferably 250 to 500, and most preferably 250 to 350. The cellulose ester used in the present invention preferably has a narrow molecular weight distribution of Mw / Mn (Mw is a mass average molecular weight, Mn is a number average molecular weight) by gel permeation chromatography. The specific value of Mw / Mn is preferably 1.5 to 5.0, more preferably 2.0 to 4.5, and most preferably 3.0 to 4.0. preferable.

  The acyl group of the cellulose acylate film is not particularly limited, but an acetyl group or a propionyl group is preferably used, and an acetyl group is particularly preferable. The degree of substitution of all acyl groups is preferably 2.7 to 3.0, more preferably 2.8 to 2.95. In this specification, the substitution degree of an acyl group is a value calculated according to ASTM D817. The acyl group is most preferably an acetyl group. When cellulose acetate having an acyl group as the acetyl group is used, the acetylation degree is preferably 59.0 to 62.5%, and 59.0 to 61.5. % Is more preferable. When the acetylation degree is within this range, Re does not become larger than the desired value due to the conveying tension during casting, there is little in-plane variation, and there is little change in the retardation value due to temperature and humidity. In addition, the substitution degree of the acyl group at the 6-position is preferably 0.9 or more from the viewpoint of suppressing variations in Re and Rth.

  Further, when two kinds of cellulose acetates having different acetylation degrees are mixed within a certain range, the wavelength dispersion characteristic can be adjusted by utilizing the fact that the wavelength dispersion characteristic of the retardation can be adjusted. About this method, as described in detail in JP-A-2001-253971, the difference in acetylation degree between cellulose acetate having the maximum degree of acetylation (Ac1) and cellulose acetate having the minimum degree of acetylation (Ac2). (Ac1-Ac2) is preferably 2.0 to 6.0% (2.0% ≦ Ac1-Ac2 ≦ 6.0%). The average degree of acetylation of the whole cellulose acetate mixture is preferably 55.0 to 61.5%. The non- (P1 / P2) viscosity average polymerization degree of the cellulose acetate having the maximum viscosity average polymerization degree (P1) and the cellulose acetate having the minimum viscosity average polymerization degree (P2) is 1 or more and less than 2 (1 ≦ P1 / P2 <2) is preferable. The viscosity average polymerization degree of the whole cellulose acetate mixture is preferably 250 to 500, and more preferably 250 to 400.

<Retardation control agent>
The cellulose acylate film preferably contains a rod-shaped compound having at least two aromatic rings as a retardation control agent. The rod-like compound preferably has a linear molecular structure. The linear molecular structure means that the molecular structure of the rod-shaped compound is linear in the thermodynamically most stable structure. The most thermodynamically stable structure can be obtained by crystal structure analysis or molecular orbital calculation. For example, molecular orbital calculation is performed using molecular orbital calculation software (eg, WinMOPAC2000, manufactured by Fujitsu Limited), and a molecular structure that minimizes the heat of formation of a compound can be obtained. The molecular structure being linear means that in the thermodynamically most stable structure obtained by calculation as described above, the angle of the main chain constituting the molecular structure is 140 degrees or more.

As the rod-shaped compound having at least two aromatic rings, a compound represented by the following general formula (1) is preferable.
Formula (1): Ar ¹ -L ¹ -Ar ²
In the general formula (1), Ar ¹ and Ar ² are each independently an aromatic group, and L ¹ is an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO— or a combination thereof. A divalent linking group selected from the following groups.

In the present specification, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group, and a substituted aromatic heterocyclic group.
An aryl group and a substituted aryl group are more preferable than an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The heterocycle of the aromatic heterocyclic group is generally unsaturated. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As a hetero atom, a nitrogen atom, an oxygen atom or a sulfur atom is preferable, and a nitrogen atom or a sulfur atom is more preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine Rings, pyridazine rings, pyrimidine rings, pyrazine rings, and 1,3,5-triazine rings are included.
As the aromatic ring of the aromatic group, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable. .

  Examples of substituents for substituted aryl groups and substituted aromatic heterocyclic groups include halogen atoms (F, Cl, Br, I), hydroxyl, carboxyl, cyano, amino, alkylamino groups (eg, methylamino, ethylamino) , Butylamino, dimethylamino), nitro, sulfo, carbamoyl, alkylcarbamoyl groups (eg, N-methylcarbamoyl, N-ethylcarbamoyl, N, N-dimethylcarbamoyl), sulfamoyl, alkylsulfamoyl groups (eg, N- Methylsulfamoyl, N-ethylsulfamoyl, N, N-dimethylsulfamoyl), ureido, alkylureido groups (eg, N-methylureido, N, N-dimethylureido, N, N, N′-trimethyl) Ureido), alkyl groups (eg, methyl, ethyl, propyl, butyl, pentyl, Butyl, octyl, isopropyl, s-butyl, t-amyl, cyclohexyl, cyclopentyl), alkenyl groups (eg, vinyl, allyl, hexenyl), alkynyl groups (eg, ethynyl, butynyl), acyl groups (eg, formyl, acetyl, Butyryl, hexanoyl, lauryl), acyloxy groups (eg, acetoxy, butyryloxy, hexanoyloxy, lauryloxy), alkoxy groups (eg, methoxy, ethoxy, propoxy, butoxy, pentyloxy, heptyloxy, octyloxy), aryloxy groups (Eg, phenoxy), alkoxycarbonyl group (eg, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentyloxycarbonyl, heptyloxycarbonyl), aryloxycarbo Group (eg, phenoxycarbonyl), alkoxycarbonylamino group (eg, butoxycarbonylamino, hexyloxycarbonylamino), alkylthio group (eg, methylthio, ethylthio, propylthio, butylthio, pentylthio, heptylthio, octylthio), arylthio group (eg, , Phenylthio), alkylsulfonyl groups (eg, methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, pentylsulfonyl, heptylsulfonyl, octylsulfonyl), amide groups (eg, acetamide, butylamide group, hexylamide, laurylamide) and non- Aromatic heterocyclic groups (eg, morpholyl, pyrazinyl) are included.

Substituents for substituted aryl groups and substituted aromatic heterocyclic groups include halogen atoms, cyano, carboxyl, hydroxyl, amino, alkyl-substituted amino groups, acyl groups, acyloxy groups, amide groups, alkoxycarbonyl groups, alkoxy groups, alkylthios. And groups and alkyl groups are preferred.
The alkyl moiety of the alkylamino group, alkoxycarbonyl group, alkoxy group, and alkylthio group and the alkyl group may further have a substituent. Examples of alkyl moieties and substituents of alkyl groups include halogen atom, hydroxyl, carboxyl, cyano, amino, alkylamino group, nitro, sulfo, carbamoyl, alkylcarbamoyl group, sulfamoyl, alkylsulfamoyl group, ureido, alkylureido Group, alkenyl group, alkynyl group, acyl group, acyloxy group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group, alkylsulfonyl group, amide group and non-aromatic An aromatic heterocyclic group is included. As the substituent for the alkyl moiety and the alkyl group, a halogen atom, hydroxyl, amino, alkylamino group, acyl group, acyloxy group, acylamino group, alkoxycarbonyl group and alkoxy group are preferable.

L ¹ is a divalent linking group selected from an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO— and a combination thereof.
The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group.
The number of carbon atoms of the alkylene group is preferably 1-20, more preferably 1-15, still more preferably 1-10, still more preferably 1-8, and most preferably 1-6. It is.

  The alkenylene group and the alkynylene group preferably have a chain structure rather than a cyclic structure, and more preferably have a linear structure rather than a branched chain structure. The alkenylene group and the alkynylene group preferably have 2 to 10 carbon atoms, more preferably 2 to 8, more preferably 2 to 6, still more preferably 2 to 4, and most preferably 2. (Vinylene or ethynylene). The arylene group preferably has 6 to 20 carbon atoms, more preferably 6 to 16, and still more preferably 6 to 12.

The example of the bivalent coupling group which consists of a combination is shown.
L-1: —O—CO-alkylene group —CO—O—
L-2: -CO-O-alkylene group -O-CO-
L-3: —O—CO—alkenylene group —CO—O—
L-4: -CO-O-alkenylene group -O-CO-
L-5: -O-CO-alkynylene group -CO-O-
L-6: -CO-O-alkynylene group -O-CO-
L-7: -O-CO-arylene group -CO-O-
L-8: -CO-O-arylene group -O-CO-
L-9: -O-CO-arylene group -CO-O-
L-10: -CO-O-arylene group -O-CO-

In the molecular structure of the general formula (1), the angle formed by Ar ¹ and Ar ² across L ¹ is preferably 140 degrees or more. As the rod-like compound, a compound represented by the following formula (2) is more preferable.
Formula ^{(2): Ar 1 -L 2} -X-L 3 -Ar 2
In the general formula (2), Ar ¹ and Ar ² are each independently an aromatic group. The definition and examples of the aromatic group are the same as those of Ar ¹ and Ar ^{2 in} the general formula (1).

In the general formula (2), L ² and L ³ are each independently a divalent linking group selected from an alkylene group, —O—, —CO—, and a group consisting of a combination thereof. The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a linear structure rather than a branched chain structure.
The number of carbon atoms of the alkylene group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, still more preferably 1 to 4, and 1 or 2 (methylene or Most preferred is ethylene). L ² and L ³ are particularly preferably —O—CO— or CO—O—.

  In the general formula (2), X is 1,4-cyclohexylene, vinylene or ethynylene.

  Specific examples of the compound represented by the general formula (1) are shown below.

  Specific examples (1) to (34), (41), and (42) have two asymmetric carbon atoms at the 1-position and the 4-position of the cyclohexane ring. However, since the specific examples (1), (4) to (34), (41), and (42) have a symmetrical meso type molecular structure, there are no optical isomers (optical activity), and geometric isomers (trans Type and cis type). The trans type (1-trans) and cis type (1-cis) of specific example (1) are shown below.

  As described above, the rod-like compound preferably has a linear molecular structure. Therefore, the trans type is preferable to the cis type. Specific examples (2) and (3) have optical isomers (a total of four isomers) in addition to geometric isomers. As for geometric isomers, the trans type is similarly preferable to the cis type. The optical isomer is not particularly superior or inferior, and may be D, L, or a racemate. In specific examples (43) to (45), the central vinylene bond includes a trans type and a cis type. For the same reason as above, the trans type is preferable to the cis type.

  Other preferred compounds that can be used as retardation control agents are shown below.

As the retardation control agent, it is preferable to use two or more kinds of rod-like compounds having a maximum absorption wavelength (λmax) shorter than 250 nm in the ultraviolet absorption spectrum of the solution. The rod-like compound can be synthesized with reference to methods described in literature. As literature, Mol. Cryst. Liq. Cryst. 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170, 43 (1989), J. Am. Am. Chem. Soc. 113, p. 1349 (1991), p. 118, p. 5346 (1996), p. 92, p. 1582 (1970). Org. Chem. 40, 420 pages (1975), Tetrahedron, Vol. 48, No. 16, page 3437 (1992).
The addition amount of the retardation control agent is preferably from 0.1 to 30% by mass, more preferably from 0.5 to 20% by mass, based on the amount of the polymer.

  An aromatic compound is used in 0.01-20 mass parts with respect to 100 mass parts of cellulose acylates. The aromatic compound is preferably used in a range of 0.05 to 15 parts by mass, and more preferably in a range of 0.1 to 10 parts by mass with respect to 100 parts by mass of cellulose acylate. Two or more kinds of compounds may be used in combination.

[Wavelength dispersion adjusting agent]
The compound that adjusts the wavelength dispersion of the cellulose acylate film will be described. The wavelength dispersibility of the cellulose acylate film can be adjusted by various methods. For example, it can be adjusted by including a compound having absorption in the ultraviolet region of 200 to 400 nm in the film. The preferable addition amount of the compound is 0.01 to 30% by mass depending on the type of compound used and the degree of adjustment. A cellulose acylate film having the optical properties required for the transparent film of the present invention can be produced.

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

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

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

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

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

(Compound addition amount)
As described above, the addition amount of the wavelength dispersion adjusting agent preferably used in the present invention is preferably 0.01 to 30% by mass, more preferably 0.1 to 20% by mass of the cellulose acylate. 0.2 to 10% by mass is particularly preferable.

(Method of compound addition)
These wavelength dispersion adjusting agents may be used alone or in combination of two or more compounds at an arbitrary ratio.
Further, the timing of adding these wavelength dispersion adjusting agents may be any time during the dope preparation process, or may be performed at the end of the dope preparation process.

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

As the benzotriazole-based compound, those represented by the general formula (3) are preferably used as a wavelength dispersion adjusting agent.
General formula (3)
Q ¹ -Q ² -OH
(In the formula, Q ¹ represents a nitrogen-containing aromatic heterocycle, and Q ² represents an aromatic ring.)

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

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

  Among the compounds represented by the general formula (3), a compound represented by the following general formula (3-A) is preferable.

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

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

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

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

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

  More preferred as the general formula (3) is a compound represented by the following general formula (3-B).

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

  Although the specific example of a compound represented by General formula (3) below is given, this invention is not limited to the following specific example at all.

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

  As the benzophenone compound that is one of the wavelength dispersion adjusting agents used in the present invention, those represented by the general formula (4) are preferably used.

In the formula, Q ^1a and Q ^2a each independently represent an aromatic ring. X represents NR (R represents a water element or a substituent), an oxygen atom or a sulfur atom.

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

  X represents NR (R represents a hydrogen atom or a substituent. Substituent T described later can be applied as a substituent), an oxygen atom or a sulfur atom, and X is preferably NR (R is preferably an acyl group). , A sulfonyl group, and these substituents may be further substituted.) Or O, particularly preferably O.

  Examples of the substituent T include an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably 1 to 8 carbon atoms such as methyl, ethyl, iso-propyl, tert-butyl, and n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably carbon number). 2 to 8, for example, vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably carbon number). 2-8, for example, propargyl, 3-pentynyl, etc.), aryl groups (preferably having 6-30 carbon atoms) More preferably, it has 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyl, p-methylphenyl, naphthyl and the like, and a substituted or unsubstituted amino group (preferably having 0 to 0 carbon atoms). 20, more preferably 0 to 10 carbon atoms, particularly preferably 0 to 6 carbon atoms, such as amino, methylamino, dimethylamino, diethylamino, dibenzylamino, etc.), an alkoxy group (preferably having a carbon number) 1 to 20, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methoxy, ethoxy, butoxy, etc.), an aryloxy group (preferably 6 to 20 carbon atoms, more Preferably it has 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenyloxy, 2-naphthyloxy and the like. An acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include acetyl, benzoyl, formyl, and pivaloyl). An alkoxycarbonyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, etc.), an aryloxycarbonyl group ( Preferably it has 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 10 carbon atoms, and examples include phenyloxycarbonyl, etc.), an acyloxy group (preferably 2 to 20 carbon atoms, More preferably, it has 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms. Nzoyloxy and the like. ), An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include acetylamino and benzoylamino), alkoxycarbonylamino group (Preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino), aryloxycarbonylamino group (preferably having carbon number) 7 to 20, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino, and the like, and sulfonylamino groups (preferably 1 to 20 carbon atoms, more preferably Has 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms. And sulfamoyl group (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, and particularly preferably 0 to 12 carbon atoms, such as sulfamoyl and methylsulfamoyl). , Dimethylsulfamoyl, phenylsulfamoyl, etc.), a carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as carbamoyl). , Methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl, etc.), an alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio, Ethylthio etc.), arylthio group (preferably Has 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio, and a sulfonyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as mesyl, tosyl, etc.), sulfinyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably Has 1 to 12 carbon atoms, such as methanesulfinyl, benzenesulfinyl, etc.), ureido group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms). For example, ureido, methylureido, phenylureido, etc.), phosphoric acid amide group (preferably having 1 to 20 carbon atoms) More preferably, it is C1-C16, Most preferably, it is C1-C12, for example, diethyl phosphoric acid amide, phenylphosphoric acid amide etc. are mentioned. ), Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, Heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom, a sulfur atom, specifically, for example, imidazolyl, pyridyl, quinolyl, furyl, piperidyl , Morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, etc.), silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, and particularly preferably 3 to 24 carbon atoms). For example, trimethylsilyl, triphenylsilyl, etc.) . These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

  As the general formula (4), a compound represented by the following general formula (4-A) is preferable.

In the formula, R ^1b , R ^2b , R ^3b , R ^4b , R ^5b , R ^6b , R ^7b , R ^8b , and R ^9b each independently represent a hydrogen atom or a substituent.

R ^1b , R ^2b , R ^3b , R ^4b , R ^5b , R ^6b , R ^7b , R ^8b , and R ^9b each independently represent a hydrogen atom or a substituent, and the substituent T described above applies as the substituent it can. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ^1b , R ^3b , R ^4b , R ^5b , R ^6b , R ^8b and R ^9b are preferably a hydrogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, substituted or unsubstituted amino group, alkoxy group, aryl An oxy group, a hydroxy group and a halogen atom, more preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, still more preferably a hydrogen atom and a carbon 1-12 alkyl group. Particularly preferred are a hydrogen atom and a methyl group, and most preferred is a hydrogen atom.

R ^2b is preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, a halogen atom, more preferably a hydrogen atom or a carbon number of 1 An alkyl group having -20 carbon atoms, an amino group having 0-20 carbon atoms, an alkoxy group having 1-12 carbon atoms, an aryloxy group having 6-12 carbon atoms, and a hydroxy group, more preferably an alkoxy group having 1-20 carbon atoms. And particularly preferably an alkoxy group having 1 to 12 carbon atoms.

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

  More preferred as the general formula (4) is a compound represented by the following general formula (4-B).

In the formula, R ^10b represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group.

R ^10b represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group, and the substituent is the substituent T described above. Applicable.
R ^10b is preferably a substituted or unsubstituted alkyl group, more preferably a substituted or unsubstituted alkyl group having 5 to 20 carbon atoms, and still more preferably a substituted or unsubstituted alkyl group having 5 to 12 carbon atoms. (Including n-hexyl group, 2-ethylhexyl group, n-octyl group, n-decyl group, n-dodecyl group, benzyl group, etc.), particularly preferably a substitution of 6 to 12 carbon atoms or An unsubstituted alkyl group (2-ethylhexyl group, n-octyl group, n-decyl group, n-dodecyl group, benzyl group).

The compound represented by the general formula (4) can be synthesized by a known method described in JP-A-11-12219.
Although the specific example of a compound represented by General formula (4) below is given, this invention is not limited to the following specific example at all.

  As the compound containing a cyano group, which is one of the wavelength dispersion adjusting agents used in the present invention, those represented by the general formula (5) are preferably used.

In the formula, Q ^1c and Q ^2c each independently represent an aromatic ring. X ^1c and X ^2c represent a hydrogen atom or a substituent, and at least one of them represents a cyano group, a carbonyl group, a sulfonyl group, or an aromatic heterocycle. The aromatic ring represented by Q ^1c and Q ^2c may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.

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

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

The aromatic ring represented by Q ^1c and Q ^2c is preferably an aromatic hydrocarbon ring, and more preferably a benzene ring. Q ^1c and Q ^2c may further have a substituent, and the substituent T described later is preferable. Examples of the substituent T include an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably 1 to 8 carbon atoms such as methyl, ethyl, iso-propyl, tert-butyl, and n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably carbon number). 2 to 8, for example, vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably carbon number). 2-8, for example, propargyl, 3-pentynyl, etc.), aryl groups (preferably having 6-30 carbon atoms) More preferably, it has 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyl, p-methylphenyl, naphthyl and the like, and a substituted or unsubstituted amino group (preferably having 0 to 0 carbon atoms). 20, more preferably 0 to 10 carbon atoms, particularly preferably 0 to 6 carbon atoms, such as amino, methylamino, dimethylamino, diethylamino, dibenzylamino, etc.), an alkoxy group (preferably having a carbon number) 1 to 20, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methoxy, ethoxy, butoxy, etc.), an aryloxy group (preferably 6 to 20 carbon atoms, more Preferably it has 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenyloxy, 2-naphthyloxy and the like. An acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include acetyl, benzoyl, formyl, and pivaloyl). An alkoxycarbonyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, etc.), an aryloxycarbonyl group ( Preferably it has 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 10 carbon atoms, and examples thereof include phenyloxycarbonyl, etc.), an acyloxy group (preferably 2 to 20 carbon atoms, More preferably, it has 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms. Nzoyloxy and the like. ), An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include acetylamino and benzoylamino), alkoxycarbonylamino group (Preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino), aryloxycarbonylamino group (preferably having carbon number) 7 to 20, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino, and the like, and sulfonylamino groups (preferably 1 to 20 carbon atoms, more preferably Has 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms. And sulfamoyl group (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms, such as sulfamoyl and methylsulfamoyl). , Dimethylsulfamoyl, phenylsulfamoyl, etc.), a carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as carbamoyl). , Methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl, etc.), an alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio, Ethylthio etc.), arylthio group (preferably Has 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio, and a sulfonyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as mesyl, tosyl, etc.), sulfinyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably Has 1 to 12 carbon atoms, such as methanesulfinyl, benzenesulfinyl, etc.), ureido group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms). For example, ureido, methylureido, phenylureido, etc.), phosphoric acid amide group (preferably having 1 to 20 carbon atoms) More preferably, it is C1-C16, Most preferably, it is C1-C12, for example, diethyl phosphoric acid amide, phenylphosphoric acid amide etc. are mentioned. ), Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, Heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom, a sulfur atom, specifically, for example, imidazolyl, pyridyl, quinolyl, furyl, piperidyl , Morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, etc.), silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, and particularly preferably 3 to 24 carbon atoms). For example, trimethylsilyl, triphenylsilyl, etc.) . These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

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

X ^1c and X ^2c are preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group, or an aromatic heterocycle, and more preferably a cyano group, a carbonyl group, a sulfonyl group, An aromatic heterocycle, more preferably a cyano group or a carbonyl group, and particularly preferably a cyano group or an alkoxycarbonyl group (—C (═O) OR (R is an alkyl group having 1 to 20 carbon atoms, 6 carbon atoms). ~ 12 aryl groups and combinations thereof.

  Preferred as the general formula (5) is a compound represented by the following general formula (5-A).

In the formula, R ^1c , R ^2c , R ^3c , R ^4c , R ^5c , R ^6c , R ^7c , R ^8c , R ^9c and R ^10c each independently represent a hydrogen atom or a substituent. X ^1c and X ^2c have the same ^{meanings as} those in formula (5), and preferred ranges are also the same.

R ^1c , R ^2c , R ^3c , R ^4c , R ^5c , R ^6c , R ^7c , R ^8c , R ^9c and R ^10c each independently represent a hydrogen atom or a substituent, and the substituent is the above-described substituent T Is applicable. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ^1c , R ^2c , R ^3c , R ^4c , R ^5c , R ^6c , R ^7c , R ^8c , R ^9c and R ^10c are preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted Substituted amino group, alkoxy group, aryloxy group, hydroxy group and halogen atom, more preferably hydrogen atom, alkyl group, aryl group, alkyloxy group, aryloxy group and halogen atom, more preferably hydrogen atom. , A carbon 1-12 alkyl group, particularly preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.

R ^3c and R ^8c are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, a halogen atom, more preferably a hydrogen atom, An alkyl group having 1 to 20 carbon atoms, an amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and a hydroxy group, more preferably a hydrogen atom and 1 carbon atom. An alkyl group having 12 to 12 carbon atoms and an alkoxy group having 1 to 12 carbon atoms, particularly preferably a hydrogen atom.

  More preferred as the general formula (5) is a compound represented by the following general formula (5-B).

In the formula, R ^3c and R ^8c have the same ^{meanings as} those in formula (5-A), and preferred ranges are also the same. X ^3c represents a hydrogen atom or a substituent.

X ^3c represents a hydrogen atom or a substituent. As the substituent, the above-described substituent T can be applied, and if possible, the substituent may be further substituted with another substituent. X ^3c is preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group, or an aromatic heterocyclic ring, more preferably a cyano group, a carbonyl group, a sulfonyl group, or an aromatic heterocyclic ring. More preferably a cyano group or a carbonyl group, and particularly preferably a cyano group or an alkoxycarbonyl group (—C (═O) OR (R is an alkyl group having 1 to 20 carbon atoms, an aryl having 6 to 12 carbon atoms). Group and a combination thereof).

  More preferred as the general formula (5) is a compound represented by the general formula (5-C).

In the formula, R ^3c and R ^8c have the same ^{meanings as} those in formula (5-A), and preferred ranges are also the same. R ^21c represents an alkyl group having 1 to 20 carbon atoms.

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

Preferably, when R ^3c and R ^8c are other than hydrogen as R ^21c , the compound represented by formula (5-C) has a molecular weight of 300 or more and an alkyl group having 20 or less carbon atoms. preferable.

  The compound represented by the general formula (5) of the present invention can be synthesized by the method described in Journal of American Chemical Society 63, 3452 (1941).

  Although the specific example of a compound represented by General formula (5) below is given, this invention is not limited to the following specific example at all.

<< Manufacture of cellulose acylate film >>
It is preferable to produce a cellulose acylate film by a solvent cast method. In the solvent cast method, a film is produced using a solution (dope) in which cellulose acylate is dissolved in an organic solvent. The organic solvent is a solvent selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to contain. The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone, and ester (that is, —O—, —CO—, and COO—) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

  Examples of the ether having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone. Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol. The number of carbon atoms of the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of halogen atoms substituted by halogen in the halogenated hydrocarbon is preferably 25 to 75 mol%, more preferably 30 to 70 mol%, and more preferably 35 to 65 mol%. More preferably, it is most preferable that it is 40-60 mol%. Methylene chloride is a representative halogenated hydrocarbon. Two or more organic solvents may be mixed and used.

A cellulose acylate solution can be prepared by a general method. The general method means that the treatment is performed at a temperature of 0 ° C. or higher (room temperature or high temperature). The solution can be prepared by using a dope preparation method and apparatus in a normal solvent cast method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly methylene chloride) as the organic solvent.
The amount of cellulose acylate is adjusted so as to be contained in the obtained solution in an amount of 10 to 40% by mass. The amount of cellulose acylate is more preferably 10 to 30% by mass. Arbitrary additives described later may be added to the organic solvent (main solvent). The solution can be prepared by stirring cellulose acylate and an organic solvent at room temperature (0 to 40 ° C.). The high concentration solution may be stirred under pressure and heating conditions. Specifically, cellulose acylate and an organic solvent are placed in a pressure vessel and sealed, and stirred while being heated to a temperature equal to or higher than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil. The heating temperature is usually 40 ° C. or higher, preferably 60 to 200 ° C., and more preferably 80 to 110 ° C.

  Each component may be coarsely mixed in advance and then placed in a container. Moreover, you may put into a container sequentially. The container needs to be configured so that it can be stirred. The container can be pressurized by injecting an inert gas such as nitrogen gas. Moreover, you may utilize the raise of the vapor pressure of the solvent by heating. Or after sealing a container, you may add each component under pressure. When heating, it is preferable to heat from the outside of the container. For example, a jacket type heating device can be used. The entire container can also be heated by providing a plate heater outside the container and piping to circulate the liquid. It is preferable to provide a stirring blade inside the container and stir using this. The stirring blade preferably has a length that reaches the vicinity of the wall of the container. A scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the vessel wall. Instruments such as a pressure gauge and a thermometer may be installed in the container. Each component is dissolved in a solvent in the container. The prepared dope is taken out of the container after cooling, or taken out and then cooled using a heat exchanger or the like.

  A solution can also be prepared by a cooling dissolution method. In the cooling dissolution method, cellulose acylate can be dissolved in an organic solvent that is difficult to dissolve by a normal dissolution method. In addition, even if it is a solvent which can melt | dissolve a cellulose acylate with a normal melt | dissolution method, there exists an effect that a uniform solution can be obtained rapidly according to a cooling melt | dissolution method. In the cooling dissolution method, first, cellulose acylate is gradually added to an organic solvent at room temperature while stirring. The amount of cellulose acylate is preferably adjusted so as to be contained in the mixture in an amount of 10 to 40% by mass. The amount of cellulose acylate is more preferably 10 to 30% by mass. Furthermore, you may add the arbitrary additive mentioned later in a mixture.

The mixture is then cooled to -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50 to -20 ° C, most preferably -50 to -30 ° C). The cooling can be performed, for example, in a dry ice / methanol bath (−75 ° C.) or a cooled diethylene glycol solution (−30 to −20 ° C.). When cooled in this way, the mixture of cellulose acylate and organic solvent solidifies.
The cooling rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and most preferably 12 ° C./min or more. The faster the cooling rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. The cooling rate is a value obtained by dividing the difference between the temperature at the start of cooling and the final cooling temperature by the time from the start of cooling until the final cooling temperature is reached.

Furthermore, when this is heated to 0 to 200 ° C. (preferably 0 to 150 ° C., more preferably 0 to 120 ° C., most preferably 0 to 50 ° C.), cellulose acylate dissolves in the organic solvent. The temperature can be raised by simply leaving it at room temperature or in a warm bath.
The heating rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and most preferably 12 ° C./min or more. The higher the heating rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. The heating rate is the value obtained by dividing the difference between the temperature at the start of heating and the final heating temperature by the time from the start of heating until the final heating temperature is reached. is there.
A uniform solution is obtained as described above. If the dissolution is insufficient, the cooling and heating operations may be repeated. Whether or not the dissolution is sufficient can be determined by merely observing the appearance of the solution with the naked eye.

In the cooling dissolution method, it is desirable to use a sealed container in order to avoid moisture mixing due to condensation during cooling. In the cooling and heating operation, when the pressure is applied during cooling and the pressure is reduced during heating, the dissolution time can be shortened. In order to perform pressurization and decompression, it is desirable to use a pressure-resistant container.
In addition, according to differential scanning calorimetry (DSC), a 20% by mass solution of cellulose acylate (degree of acetylation: 60.9%, viscosity average degree of polymerization: 299) dissolved in methyl acetate by the cooling dissolution method is There exists a quasi-phase transition point between a sol state and a gel state in the vicinity of 33 ° C., and a uniform gel state is obtained below this temperature. Therefore, this solution needs to be stored at a temperature equal to or higher than the pseudo phase transition temperature, preferably about the gel phase transition temperature plus about 10 ° C. However, this pseudo phase transition temperature varies depending on the degree of acetylation of cellulose acylate, the degree of viscosity average polymerization, the concentration of the solution, and the organic solvent used.

From the prepared cellulose acylate solution (dope), a cellulose acylate film is produced by a solvent cast method.
The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 18 to 35%. The surface of the drum or band is preferably finished in a mirror state. For casting and drying methods in the solvent casting method, U.S. Pat. No. 736892, JP-B Nos. 45-4554, 49-5614, JP-A-60-176834, No. 60-203430, and No. 62-1115035.
The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less. After casting, it is preferable to dry it by applying air for 2 seconds or more. The obtained film can be peeled off from the drum or band, and further dried by high-temperature air whose temperature is successively changed from 100 to 160 ° C. to evaporate the residual solvent. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting.

A plasticizer can be added to the cellulose acylate film in order to improve mechanical properties or increase the drying rate. As the plasticizer, phosphoric acid ester or carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP). Representative examples of the carboxylic acid ester include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethylhexyl phthalate (DEHP). Examples of citrate esters include triethyl O-acetylcitrate (OACTE) and tributyl O-acetylcitrate (OACTB). Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalate plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred.
The addition amount of the plasticizer is preferably 0.1 to 25% by mass of the amount of cellulose ester, more preferably 1 to 20% by mass, and most preferably 3 to 15% by mass.

  A degradation inhibitor (eg, antioxidant, peroxide decomposer, radical inhibitor, metal deactivator, acid scavenger, amine) may be added to the cellulose acylate film. The deterioration preventing agents are described in JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, and JP-A-6-107854. The amount of the deterioration inhibitor added is 0.01 to 1 of the solution (dope) to be prepared from the viewpoint that the effect of addition of the deterioration inhibitor is manifested and that the deterioration inhibitor is prevented from bleeding out on the film surface. It is preferable that it is mass%, and it is further more preferable that it is 0.01-0.2 mass%. Examples of particularly preferred deterioration inhibitors include butylated hydroxytoluene (BHT) and tribenzylamine (TBA).

<Stretching treatment of cellulose acylate film>
The retardation of the cellulose acylate film can be adjusted by stretching. The draw ratio is preferably 3 to 100%.
There is no restriction | limiting in particular about the extending | stretching method, A well-known method can be utilized. Tenter stretching is particularly preferably used from the viewpoint of in-plane uniformity. The cellulose acylate film used in the present invention preferably has a width of at least 100 cm, the variation in the Re value over the entire width is preferably ± 5 nm, and more preferably ± 3 nm. Further, the variation of the Rth value is preferably ± 10 nm, and more preferably ± 5 nm. Further, it is preferable that the variation in the Re value and the Rth value in the length direction is also within the range of the variation in the width direction.
In addition, the stretching process may be performed in the middle of the film forming process, or the raw film that has been formed and wound may be stretched. In the former case, the stretching may be performed in a state including the residual solvent amount, and the stretching can be preferably performed with the residual solvent amount of 2 to 30%. At this time, it is preferable to stretch the film in the direction perpendicular to the longitudinal direction while conveying the film in the longitudinal direction so that the slow axis of the film is orthogonal to the longitudinal direction of the film.
The stretching temperature can be selected appropriately depending on the amount of residual solvent and the film thickness during stretching. When stretching in a state containing a residual solvent, it is preferable to dry after stretching. The drying method can be performed according to the method described in the film production.
The cellulose acylate film after stretching has a thickness of 110 microns or less, preferably 40 to 110 microns, more preferably 60 to 110 microns, and preferably 80 to 110 microns.

<< Surface treatment of cellulose acylate film >>
When using the transparent film which consists of a cellulose acylate film as a transparent protective film of a polarizing plate, it is preferable to surface-treat a cellulose acylate film. As the surface treatment, corona discharge treatment, glow discharge treatment, flame treatment, acid treatment, alkali treatment or ultraviolet irradiation treatment is performed. It is particularly preferable to perform acid treatment or alkali treatment, that is, saponification treatment on cellulose acylate.

  The rod-shaped compound having a linear structure having at least two aromatic rings as described above is stretched to satisfy the desired retardation values Re, Rth, and Re / Rth ratio, and the film thickness is 40 microns to 110 microns. The cellulose acylate film satisfies the optical characteristics of the transparent film of the present invention, and can be used as a transparent film in various liquid crystal display devices.

[Optically anisotropic layer]
The optical compensation film of the present invention has at least one optically anisotropic layer formed from a liquid crystalline compound. The optically anisotropic layer may be formed directly on the surface of the transparent film, or may be formed on the alignment film by forming an alignment film on the transparent film. Moreover, it is also possible to produce the optical compensation film of the present invention by transferring a liquid crystalline compound layer formed on another substrate onto a transparent film using an adhesive, an adhesive, or the like.
Examples of the liquid crystalline compound used for forming the optically anisotropic layer include a rod-like liquid crystalline compound and a discotic liquid crystalline compound (hereinafter, the discotic liquid crystalline compound may be referred to as a “discotic liquid crystalline compound”). The rod-like liquid crystal compound and the discotic liquid crystal compound may be a high-molecular liquid crystal or a low-molecular liquid crystal. Further, the compound finally contained in the optically anisotropic layer no longer needs to exhibit liquid crystallinity. For example, when a low-molecular liquid crystalline compound is used for the production of the optically anisotropic layer, the optically anisotropic layer In the process of forming, the compound may be cross-linked and no longer exhibits liquid crystallinity.

(Bar-shaped liquid crystalline compound)
Examples of the rod-like liquid crystalline compound that can be used in the present invention include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, and cyano-substituted phenylpyrimidines. Alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. The rod-like liquid crystalline compound includes a metal complex. A liquid crystal polymer containing a rod-like liquid crystal compound in a repeating unit can also be used. In other words, the rod-like liquid crystalline compound may be bonded to a (liquid crystal) polymer.
For rod-like liquid crystalline compounds, see Chapter 4, Chapter 7 and Chapter 11 of the Chemistry of the Quarterly Chemical Review Vol. Described in Chapter 3.

The birefringence of the rod-like liquid crystalline compound used in the present invention is preferably in the range of 0.001 to 0.7.
The rod-like liquid crystalline compound preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably an unsaturated polymerizable group or an epoxy group, more preferably an unsaturated polymerizable group, and most preferably an ethylenically unsaturated polymerizable group.

(Discotic liquid crystalline compounds)
Examples of discotic liquid crystalline compounds include C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, page 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), azacrown type and phenylacetylene type macrocycles are included.

  The discotic liquid crystalline compound exhibits liquid crystallinity with a structure in which a linear alkyl group, an alkoxy group or a substituted benzoyloxy group is radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule. Also included are compounds. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation.

  As described above, when an optically anisotropic layer is formed from a liquid crystalline compound, the compound finally contained in the optically anisotropic layer no longer needs to exhibit liquid crystallinity. For example, a low-molecular discotic liquid crystalline compound has a group that reacts with heat or light, and the group reacts with heat or light to polymerize or crosslink to increase the molecular weight. When a layer is formed, the compound contained in the optically anisotropic layer may no longer have liquid crystallinity. Preferred examples of the discotic liquid crystalline compound are described in JP-A-8-50206. Moreover, about superposition | polymerization of a discotic liquid crystalline compound, Unexamined-Japanese-Patent No. 8-27284 has description.

  In order to fix the discotic liquid crystalline compound by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline compound. However, when the polymerizable group is directly connected to the disc-shaped core, it becomes difficult to maintain the orientation state in the polymerization reaction. Therefore, a linking group is introduced between the discotic core and the polymerizable group. Therefore, the discotic liquid crystalline compound having a polymerizable group is preferably a compound represented by the following formula (III).

Formula (III)
D (-LQ) _n
In the formula, D is a discotic core, L is a divalent linking group, Q is a polymerizable group, and n is an integer of 4 to 12.

  An example of the disk-shaped core (D) is shown below. In each of the following examples, LQ (or QL) means a combination of a divalent linking group (L) and a polymerizable group (Q).

  In the formula (III), the divalent linking group (L) is selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, —CO—, —NH—, —O—, —S—, and combinations thereof. A divalent linking group selected is preferable. The divalent linking group (L) is a divalent combination of at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, -CO-, -NH-, -O-, and S-. The linking group is more preferable. The divalent linking group (L) is most preferably a divalent linking group in which at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, -CO- and O- are combined. preferable. The alkylene group preferably has 1 to 12 carbon atoms. The alkenylene group preferably has 2 to 12 carbon atoms. The arylene group preferably has 6 to 10 carbon atoms.

Examples of the divalent linking group (L) are shown below. The left side is bonded to the discotic core (D), and the right side is bonded to the polymerizable group (Q). AL represents an alkylene group or an alkenylene group, and AR represents an arylene group. The alkylene group, alkenylene group and arylene group may have a substituent (eg, alkyl group).
L1: -AL-CO-O-AL-
L2: -AL-CO-O-AL-O-
L3: -AL-CO-O-AL-O-AL-
L4: -AL-CO-O-AL-O-CO-
L5: -CO-AR-O-AL-
L6: -CO-AR-O-AL-O-
L7: -CO-AR-O-AL-O-CO-
L8: -CO-NH-AL-
L9: -NH-AL-O-
L10: -NH-AL-O-CO-

L11: -O-AL-
L12: -O-AL-O-
L13: -O-AL-O-CO-
L14: -O-AL-O-CO-NH-AL-
L15: -O-AL-S-AL-
L16: -O-CO-AR-O-AL-CO-
L17: -O-CO-AR-O-AL-O-CO-
L18: -O-CO-AR-O-AL-O-AL-O-CO-
L19: -O-CO-AR-O-AL-O-AL-O-AL-O-CO-
L20: -S-AL-
L21: -S-AL-O-
L22: -S-AL-O-CO-
L23: -S-AL-S-AL-
L24: -S-AR-AL-

The polymerizable group (Q) of the formula (III) is determined according to the type of polymerization reaction. The polymerizable group (Q) is preferably an unsaturated polymerizable group or an epoxy group, more preferably an unsaturated polymerizable group, and most preferably an ethylenically unsaturated polymerizable group.
In formula (III), n is an integer of 4-12. A specific number is determined according to the type of the disk-shaped core (D). In addition, although the combination of several L and Q may differ, it is preferable that it is the same.

  In the present invention, in the optically anisotropic layer, the molecules of the rod-like compound or the discotic compound are fixed in an oriented state. The orientation average direction of the molecular symmetry axis of the liquid crystalline compound at the interface on the transparent film side has an intersection angle with the slow axis in the plane of the transparent film of approximately 0 degrees or approximately 90 degrees. In the present specification, “substantially 0 degrees or 90 degrees” refers to an angle in a range of 0 ° ± 5 ° or 90 ° ± 5 °, preferably 42 to 48 °, and more preferably 43 to 48 °. It is 47 °. The average direction of the molecular symmetry axis of the liquid crystalline compound in the optically anisotropic layer is preferably 43 ° to 47 ° with respect to the longitudinal direction of the transparent film (that is, the fast axis direction of the transparent film). .

  The orientation average direction of the molecular symmetry axis of the liquid crystal compound can be generally adjusted by selecting a material of the liquid crystal compound or the alignment film or by selecting a rubbing treatment method. In the present invention, for example, when an alignment film for forming an optically anisotropic layer is produced by rubbing, the molecular symmetry of the liquid crystalline compound is obtained by rubbing in the direction of 45 ° with respect to the slow axis of the transparent film. It is possible to form an optically anisotropic layer in which the orientation average direction of the axis at least at the transparent film interface is 45 ° with respect to the slow axis of the transparent film. For example, the optical compensation film of the present invention can be continuously produced by using a long transparent film whose slow axis is parallel to the longitudinal direction. Specifically, a coating liquid for forming an alignment film is continuously applied to the surface of a long transparent film to prepare a film, and then the surface of the film is continuously oriented in the direction of 45 ° in the longitudinal direction. An alignment film is prepared by rubbing, and then a coating liquid for forming an optically anisotropic layer containing a liquid crystalline compound is continuously applied on the prepared alignment film to align the molecules of the liquid crystalline compound. By fixing in this state, an optically anisotropic layer can be produced, and a long optical compensation film can be produced continuously. The optical compensation film produced in a long shape is cut into a desired shape before being incorporated into the liquid crystal display device.

  Further, with respect to the orientation average direction of the molecular symmetry axis on the surface side (air side) of the liquid crystalline compound, the orientation average direction of the molecular symmetry axis of the liquid crystalline compound on the air interface side is substantially 0 with respect to the slow axis of the transparent film. The angle is preferably 90 ° or 90 °, more preferably 42 to 48 °, and still more preferably 43 to 47 °. In general, the orientation average direction of the molecular symmetry axis of the liquid crystal compound on the air interface side can be adjusted by selecting the type of the liquid crystal compound or the additive used together with the liquid crystal compound. Examples of the additive used together with the liquid crystal compound include a plasticizer, a surfactant, a polymerizable monomer and a polymer. Similarly to the above, the degree of change in the orientation direction of the molecular symmetry axis can be adjusted by selecting the liquid crystal compound and the additive. In particular, regarding the surfactant, it is preferable that the surface tension control of the coating solution is compatible.

  The plasticizer, surfactant and polymerizable monomer used together with the liquid crystal compound are compatible with the discotic liquid crystal compound and can change the tilt angle of the liquid crystal compound or do not inhibit the alignment. Is preferred. Polymerizable monomers (eg, compounds having a vinyl group, a vinyloxy group, an acryloyl group and a methacryloyl group) are preferred. 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 liquid crystal compound. In addition, when a monomer having 4 or more polymerizable reactive functional groups is mixed and used, adhesion between the alignment film and the optically anisotropic layer can be improved.

When a discotic liquid crystalline compound is used as the liquid crystalline compound, it is preferable to use a polymer that has a certain degree of compatibility with the discotic liquid crystalline compound and can change the tilt angle of the discotic liquid crystalline compound.
A cellulose ester can be mentioned as an example of a polymer. Preferred examples of the cellulose ester include cellulose acetate, cellulose acetate propionate, hydroxypropyl cellulose, and cellulose acetate butyrate. In order not to inhibit the orientation of the discotic liquid crystalline compound, the amount of the polymer added is preferably in the range of 0.1 to 10% by mass, preferably 0.1 to 8% by mass with respect to the discotic liquid crystalline compound. More preferably, it is in the range of 0.1 to 5% by mass.
The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline compound is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

  In the present invention, the optically anisotropic layer preferably has at least in-plane optical anisotropy. The optical characteristics of the optically anisotropic layer are determined according to the optical characteristics and mode of the liquid crystal cell to be optically compensated. When used in a TN mode liquid crystal display device, the in-plane retardation Re of the optically anisotropic layer is preferably 3 to 300 nm, more preferably 5 to 200 nm, and more preferably 10 to 100 nm. Is more preferable. The retardation Rth in the thickness direction of the optically anisotropic layer is preferably 20 to 400 nm, and more preferably 50 to 200 nm. The thickness of the optically anisotropic layer is preferably 0.1 to 20 microns, more preferably 0.5 to 15 microns, and most preferably 1 to 10 microns.

[Alignment film]
The optical compensation film of the present invention may have an alignment film between the transparent film and the optically anisotropic layer. Alternatively, an alignment film may be used only when an optically anisotropic layer is produced, and after the optically anisotropic layer is produced on the oriented film, only the optically anisotropic layer may be transferred onto the transparent film. .
In the present invention, the alignment film is preferably a layer made of a crosslinked polymer. The polymer used for the alignment film may be either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent. The alignment film is formed by reacting a polymer having a functional group or a polymer having a functional group introduced therein with light, heat, pH change, or the like; or a cross-linking agent that is a highly reactive compound Can be formed by introducing a linking group derived from a cross-linking agent between polymers to cross-link between the polymers.

The alignment film composed of a crosslinked polymer can be usually formed by applying a coating solution containing the polymer or a mixture of a polymer and a crosslinking agent on a support, followed by heating.
In the rubbing process described later, it is preferable to increase the degree of crosslinking in order to suppress the dust generation of the alignment film. A value (1- (Ma / Mb)) obtained by subtracting 1 from the ratio (Ma / Mb) of the amount (Ma) of the crosslinking agent remaining after crosslinking to the amount (Mb) of the crosslinking agent added to the coating solution. When Mb)) is defined as the degree of crosslinking, the degree of crosslinking is preferably 50% to 100%, more preferably 65% to 100%, and most preferably 75% to 100%.

  In the present invention, the polymer used for the alignment film may be either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent. Of course, a polymer having both functions can also be used. Examples of the polymer include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleimide copolymer, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylol acrylamide). ), Styrene / vinyl toluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, carboxymethylcellulose -Polymers such as silica, gelatin, polyethylene, polypropylene and polycarbonate and compounds such as silane coupling agents. Examples of preferred polymers are water-soluble polymers such as poly (N-methylacrylamide), carboxymethyl cellulose, gelatin, polyvir alcohol and modified polyvinyl alcohol, and gelatin, polyvir alcohol and modified polyvinyl alcohol. Are preferable, and in particular, polyvinyl alcohol and modified polyvinyl alcohol can be mentioned.

Among the above polymers, polyvinyl alcohol or modified polyvinyl alcohol is preferable.
Examples of the polyvinyl alcohol include those having a saponification degree of 70 to 100%, generally those having a saponification degree of 80 to 100%, and more preferably those having a saponification degree of 82 to 98%. The degree of polymerization is preferably in the range of 100 to 3000.
Examples of the modified polyvinyl alcohol include those modified by copolymerization (for example, COONa, Si (OX) ₃ , N (CH ₃ ) ₃ .Cl, C ₉ H ₁₉ COO, SO ₃ Na, C ₁₂ H ₂₅ etc. Modified by chain transfer (for example, COONa, SH, SC ₁₂ H ₂₅ etc. are introduced as modifying groups), modified by block polymerization (modified groups such as COOH, for example) , CONH ₂ , COOR, C ₆ H _5, etc. are introduced). As a polymerization degree, the range of 100-3000 is preferable. Among these, unmodified or modified polyvinyl alcohol having a saponification degree of 80 to 100% is preferable, and unmodified or alkylthio-modified polyvinyl alcohol having a saponification degree of 85 to 95% is more preferable.

As the modified polyvinyl alcohol used for the alignment film, a reaction product of a compound represented by the following general formula (6) and polyvinyl alcohol is preferable.
General formula (6):

In the formula, R ^1d represents an unsubstituted alkyl group, or an alkyl group substituted with an acrylolyl group, a methacryloyl group or an epoxy group, W represents a halogen atom, an alkyl group or an alkoxy group, X ^1d represents an active ester, an acid This represents a group of atoms necessary for forming an anhydride or acid halide, l represents 0 or 1, and n represents an integer of 0 to 4.

Moreover, as the modified polyvinyl alcohol used for the alignment film, a reaction product of a compound represented by the following general formula (7) and polyvinyl alcohol is also preferable.
General formula (7):

In the formula, X ^2d represents an atomic group necessary for forming an active ester, acid anhydride or acid halide, and m represents an integer of 2 to 24.

The polyvinyl alcohol used for reacting with the compounds represented by the general formula (6) and the general formula (7) includes the unmodified polyvinyl alcohol and the copolymer-modified one, that is, chain transfer. Examples include modified products of polyvinyl alcohol such as modified products and modified products by block polymerization. Preferred examples of the specific modified polyvinyl alcohol are described in detail in JP-A-8-338913.
When using a hydrophilic polymer such as polyvinyl alcohol for the alignment film, it is preferable to control the moisture content from the viewpoint of the degree of hardening, preferably 0.4% to 2.5%, 0.6% More preferably, it is -1.6%. The water content can be measured with a commercially available Karl Fischer moisture content measuring device.
The alignment film preferably has a thickness of 10 microns or less.

[Polarizer]
In the present invention, a polarizing plate comprising a polarizing film and a pair of protective films sandwiching the polarizing film can be used. For example, a polarizing film obtained by dyeing a polarizing film made of a polyvinyl alcohol film or the like with iodine, stretching, and laminating both surfaces with a protective film can be used. The polarizing plate is disposed outside the liquid crystal cell. It is preferable that a pair of polarizing plates each including a polarizing film and a pair of protective films sandwiching the polarizing film are disposed with the liquid crystal cell interposed therebetween. As described above, the protective film disposed on the liquid crystal cell side may be the optical compensation film (transparent film) of the present invention.

(Protective film)
The polarizing plate that can be used in the present invention may be one in which a pair of protective films (also referred to as protective films) are laminated on both sides of the polarizing film. The kind of protective film is not particularly limited, and cellulose esters such as cellulose acetate, cellulose acetate butyrate, and cellulose propionate, polycarbonate, polyolefin, polystyrene, polyester, and the like can be used. As described above, a cellulose acylate film that satisfies the optical properties of the transparent film of the present invention can also be used as a protective film.

  The protective film is usually supplied in a roll form, and it is preferable that the protective film is continuously bonded to the long polarizing film so that the longitudinal directions thereof coincide. Here, the orientation axis (slow axis) of the protective film may be any direction, and the orientation axis of the protective film is preferably parallel to the longitudinal direction for ease of operation.

  In the case of providing the protective film with optical compensation capability, Re / Rth (450 nm), which is the ratio of Re and Rth at a wavelength of 450 nm in the visible light region, is 0.39 to 0.003 of Re / Rth (550 nm) at a wavelength of 550 nm. 95 times, and Re / Rth (650 nm) at a wavelength of 650 nm is 1.04 to 2.20 times Re / Rth (550 nm) at a wavelength of 550 nm, and the thickness of the transparent film in the visible light region at a wavelength of 550 nm The retardation Rth in the direction is preferably 70 nm to 400 nm.

  On the other hand, in an embodiment where the protective film does not function as a transparent film, the retardation of the transparent protective film is preferably low. In an embodiment where the transmission axis of the polarizing film and the orientation axis of the transparent protective film are not parallel, the retardation of the transparent protective film is particularly preferable. If the value is greater than a certain value, the polarization axis and the orientation axis (slow axis) of the transparent protective film are obliquely shifted, so that linearly polarized light changes to elliptically polarized light, which is not preferable. As the polymer film having low retardation, polyolefins such as cellulose triacetate, ZEONEX, ZEONOR (both manufactured by Nippon Zeon Co., Ltd.) and ARTON (manufactured by JSR Co., Ltd.) are preferably used. Other examples include non-birefringent optical resin materials as described in JP-A-8-110402 or JP-A-11-293116. In this embodiment, when a laminate comprising a support and an optically anisotropic layer made of a liquid crystalline compound is used as a light compensation layer, the protective film is a support having an optically anisotropic layer. You may also serve.

  When laminating the protective film and the polarizing film, at least one protective film (protective film disposed on the side close to the liquid crystal cell when incorporated in a liquid crystal display device), the slow axis (alignment axis), The protective film and the polarizing film are preferably laminated so that the absorption axis (stretching axis) of the polarizing film intersects. Specifically, the angle between the absorption axis of the polarizing film and the slow axis of the protective film is preferably 10 ° to 90 °, more preferably 20 ° to 70 °, still more preferably 40 ° to 50 °, particularly Preferably it is 43-47 degrees. The angle between the slow axis of the other protective film and the absorption axis of the polarizing film is not particularly limited, and can be appropriately set according to the purpose of the polarizing plate, but is preferably in the above range, and the retardation of the pair of protective films The phase axes are preferably coincident.

  Note that when the slow axis of the protective film and the absorption axis of the polarizing film are parallel to each other, the mechanical stability of the polarizing plate such as dimensional change of the polarizing plate and prevention of curling can be improved. At least two axes of a total of three films of the polarizing film and the pair of protective films, the slow axis of one protective film and the absorption axis of the polarizing film, or the slow axes of the two protective films should be substantially parallel. The same effect can be obtained.

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

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

<Performance of polarizing plate>
Optical properties and durability (short-term and long-term storage stability) of a polarizing plate comprising a transparent protective film, a polarizer and a transparent support related to the present invention are commercially available super high contrast products (for example, Sanritz Corporation). Manufactured by HLC2-5618 and the like) and preferably have equivalent or better performance. Specifically, the visible light transmittance is 42.5% or more, and the degree of polarization {(Tp−Tc) / (Tp + Tc)} 1/2 ≧ 0.9995 (where Tp is parallel transmittance, and Tc is orthogonal transmission) The change rate of the light transmittance before and after being left in an atmosphere of 60 ° C. and a humidity of 90% RH for 500 hours and 80 ° C. in a dry atmosphere for 500 hours is 3% or less based on the absolute value, Further, it is preferably 1% or less, and the rate of change of the polarization degree is preferably 1% or less, more preferably 0.1% or less based on the absolute value.

  The present invention will be described more specifically with reference to the following examples. These examples show specific examples of the contents of the present invention, and the present invention is not limited to these examples.

[Example 1]
An optical simulation was performed on the liquid crystal display device having the configuration shown in FIG. 1 to confirm the effect. For the optical calculation, LCD Master Ver 6.08 manufactured by Shintech Co., Ltd. was used. As the liquid crystal cell, electrode, substrate, polarizing plate, etc., those conventionally used for liquid crystal displays can be used as they are. As the liquid crystal material, ZLI-4792 attached to the LCD Master was used. The alignment of the liquid crystal cell is a horizontal alignment with a pretilt angle of 4 degrees, a parallel alignment, a cell gap of the substrate of 4 microns, and a liquid crystal material having a positive dielectric anisotropy (that is, the thickness of the liquid crystal layer). The product Δn · d) of the thickness d (micron) and the refractive index anisotropy Δn was 395 nm. G1220DU attached to LCD Master was used for the polarizing film. For the transparent film, the values of Re and Rth at the wavelength were set to the values shown in the column of Example 1 in Table 1. The front Re retardation value of the optically anisotropic layer was set to 30 nm. A Backlight light source attached to the LCD Master was used as the light source. Thus, the liquid crystal display device of Example 1 was configured as shown in FIG. However, the crossing angle between the transmission axis 2 of the polarizing film 1 and the in-plane slow axis 14a of the transparent film 13a and the crossing angle between the transmission axis 102 of the polarizing film 101 and the in-plane slow axis 114a of the transparent film 113a are: Each was 0 °.
<Leakage and chromaticity of liquid crystal display devices>
The voltage with the lowest front transmittance, that is, the black voltage, is applied to the liquid crystal display device of Example 1, and the black display transmittance (%) at the azimuth angle 270 ° and polar angle 60 ° viewing angle is obtained. It was. The results are shown in Table 1.

[Examples 2 to 4]
In the same manner as in Example 1, Re and Rth of the transparent film were set so that the optical characteristics shown in Table 1 were obtained. Other than that, the optical characteristics of the liquid crystal display device were calculated by the LCD Master in exactly the same manner as in Example 1.
<Measurement of leakage light and chromaticity of liquid crystal display device>
A voltage at which the transmissivity at the front surface is minimized, that is, a black voltage was applied to these liquid crystal display devices, and the black display transmissivity (%) at the azimuth angle of 270 ° and the polar angle of 60 ° was determined. The results are shown in Table 1.

[Comparative Example 1]
In the same manner as in Example 1, Re and Rth of the transparent film were set so that the optical characteristics shown in Table 1 were obtained. Otherwise, the optical characteristics of the liquid crystal display device were calculated by LCD Master in exactly the same manner as in Example 1. In Comparative Example 1, for comparison with the effect of the present invention, Re / Rth, which is the ratio of Re and Rth, was made almost constant at any wavelength of 450, 550, and 650 nm.
<Measurement of leakage light and chromaticity of liquid crystal display device>
A voltage at which the transmissivity at the front surface is minimized, that is, a black voltage was applied to these liquid crystal display devices, and the black display transmissivity (%) at the azimuth angle of 270 ° and the polar angle of 60 ° was determined. The results are shown in Table 1.

  From the results shown in Table 1, Re / Rth (450 nm) is 0.39 to 0.95 times Re / Rth (550 nm), and Re / Rth (650 nm) is 1 of Re / Rth (550 nm). The liquid crystal display device Examples 1 to 4 of the embodiment of the present invention having a magnification of 04 to 2.20 times each have lower transmittance at the time of black display at a polar angle of 60 ° as compared with Comparative Example 1. I understand. Further, from the results of Table 1, when Re / Rth (450 nm) is 0.56 times Re / Rth (550 nm) and Re / Rth (650 nm) is 1.69 times Re / Rth (550 nm). It can be understood that both transmittance and color shift are minimized.

It is a schematic diagram explaining the structural example of the liquid crystal display device of this invention. It is a graph which shows the optical characteristic about an example of the transparent film used for this invention. It is the schematic of the Poincare sphere used in order to demonstrate the change of the polarization state of the incident light in an example of the conventional liquid crystal display device. It is the schematic of the Poincare sphere used in order to demonstrate the change of the polarization state of the incident light in the liquid crystal display device of this invention. It is a schematic diagram explaining the structural example of the liquid crystal display device of the conventional TN mode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polarizing film 2 Transmission axis 3a Transparent support 13a Transparent film 14a In-plane slow axis 5 Optical anisotropic layer 5a Orientation average direction 6 on the polarizing film side (transparent film interface side) of the molecular symmetry axis of the liquid crystalline compound 6 Substrate 7 Liquid crystalline molecule 8 Substrate 9 Optically anisotropic layer 9a Orientation average direction 103a on the polarizing film side (transparent film interface side) of the molecular symmetry axis of the liquid crystalline compound Transparent support 113a Transparent film 114a In-plane slow axis 101 Polarizing film 102 Transmission axis

Claims (5)

An optical compensation film having at least two layers of a transparent film and an optically anisotropic layer having optical anisotropy in the plane,
When the in-plane retardation of the transparent film is Re and the retardation in the thickness direction is Rth, the ratio Re / Rth (450 nm) of Re to Rth at a wavelength of 450 nm is Re / Rth (550 nm) at a wavelength of 550 nm. 0.39 to 0.95 times, Re / Rth (650 nm) at a wavelength of 650 nm is 1.04 to 2.20 times Re / Rth (550 nm), and Rth at a wavelength of 550 nm is 70 nm to 400 nm. And
The optically anisotropic layer is formed from a composition containing a liquid crystalline compound, and in the optically anisotropic layer, the molecules of the liquid crystalline compound are fixed in an aligned state, and the molecular symmetry axis of the liquid crystalline compound is An optical system in which the crossing angle between the direction in which the orientation average direction at the interface on the transparent film side is orthogonally projected into the transparent film plane and the slow axis in the plane of the transparent film is approximately 0 degrees or approximately 90 degrees Compensation film. The optical compensation film according to claim 1, wherein the liquid crystal compound is a discotic liquid crystal compound. A pair of opposed substrates having electrodes on at least one of the substrates, and a nematic liquid crystal material sandwiched between the pair of substrates, and liquid crystal molecules of the nematic liquid crystal material with respect to the surfaces of the pair of substrates when not driven A liquid crystal cell having a liquid crystal layer oriented substantially in parallel and having a product Δn · d of a thickness d (micron) and a refractive index anisotropy Δn of 0.1 to 1.5 microns,
A first and second polarizing film disposed with the liquid crystal cell sandwiched therebetween, and a transparent film between at least one of the first and second polarizing films and the liquid crystal cell;
When the in-plane retardation of the transparent film is Re and the retardation in the thickness direction is Rth, the ratio Re / Rth (450 nm) of Re to Rth at a wavelength of 450 nm is Re / Rth (550 nm) at a wavelength of 550 nm. 0.39 to 0.95 times, Re / Rth (650 nm) at a wavelength of 650 nm is 1.04 to 2.20 times Re / Rth (550 nm), and Rth of the transparent film at a wavelength of 550 nm is , 70 nm to 400 nm,
Between the transparent film and the liquid crystal cell, it has at least one optically anisotropic layer, and the optically anisotropic layer is formed from a composition containing a liquid crystalline compound, and the optical anisotropy In the layer, the molecules of the liquid crystal compound are fixed in an alignment state, and the direction of the molecular symmetry axis of the liquid crystal compound is orthogonally projected into the transparent film plane at least at the interface on the transparent film side, and A liquid crystal display device in which the crossing angle with the slow axis in the plane of the transparent film is approximately 0 degrees or approximately 90 degrees. The liquid crystal display device according to claim 3, wherein the liquid crystal compound is a discotic liquid crystal compound. 5. The liquid crystal display device according to claim 3, wherein the liquid crystal cell is a TN mode liquid crystal cell.

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