JP2007079561A - Optical film, optical compensating film using the same, polarizer, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film which has a high contrast ratio over a wide range and can suppress a color shift, an optical compensating film using the same, a polarizer, and a liquid crystal display device. <P>SOLUTION: Disclosed are the optical film which satisfies retardations represented by inequalities (1) to (4) and contains a specified kind of polycarbonate copolymer with a specified copolymerization ratio and/or a blend body containing the polycarbonate copolymer, the optical compensating film using the same, the polarizer, and the liquid crystal display device, wherein (1) 0.1<Re(450)/Re(550)<0.95, (2) 1.03<Re(650)/Re(550)<1.93, (3) 0.4<(Re(450)/Rth(450))/(Re(550)/Rth(550))<0.95, and (4) 1.05<(Re(650)/Rth(650))/(Re(550)/Rth(550))<1.90. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

Liquid crystal display devices are widely used in monitors for personal computers and portable devices, and for television applications because of their various advantages, such as low voltage and low power consumption, enabling miniaturization and thinning. Various modes have been proposed for such a liquid crystal display device depending on the alignment state of the liquid crystal molecules in the liquid crystal cell. Conventionally, the liquid crystal display device is in an alignment state twisted by about 90 ° from the lower substrate to the upper substrate of the liquid crystal cell. The TN mode was mainstream.
In general, a liquid crystal display device includes a liquid crystal cell, an optical compensation sheet, and a polarizer. The optical compensation sheet is used for eliminating image coloring or expanding the viewing angle, and a stretched birefringent film or a film obtained by applying a liquid crystal to a transparent film is used. For example, Patent Document 1 discloses a technique for applying an optical compensation sheet in which a discotic liquid crystal is applied on a triacetyl cellulose film, aligned, and fixed to a TN mode liquid crystal cell to widen the viewing angle. However, a liquid crystal display device for television that is expected to be viewed from various angles on a large screen has a strict requirement for viewing angle dependency, and even with the above-described method, the requirement cannot be satisfied. Therefore, liquid crystal display devices different from the TN mode, such as an IPS (In-Plane Switching) mode, an OCB (Optically Compensatory Bend) mode, and a VA (Vertically Aligned) mode, have been studied. In particular, the VA mode is attracting attention as a liquid crystal display device for TV because of its high contrast and relatively high production yield.

  However, in the VA mode, almost complete black display is possible in the normal direction of the panel, but when the panel is observed from an oblique direction, light leakage occurs and the viewing angle becomes narrow. In order to solve this problem, a retardation plate having a refractive index anisotropy having a sufficiently small refractive index in the film thickness direction relative to the in-plane refractive index is disposed on at least one of the liquid crystal layer and the polarizing plate. It has been proposed to reduce leakage (for example, Patent Document 2). Further, the first retardation plate having positive uniaxial refractive index anisotropy and the second retardation plate having negative refractive index anisotropy having a sufficiently small refractive index in the film thickness direction with respect to the refractive index in the film plane. There has been proposed a method of reducing light leakage by using together with the above retardation plate (for example, Patent Document 3). Furthermore, it has been proposed to improve the viewing angle characteristics of a VA mode liquid crystal display device by using an optically biaxial retardation plate having different refractive indexes in the three-dimensional direction of the film (for example, Patent Documents). 4).

  However, these methods only reduce light leakage for a certain wavelength range (for example, green light near 550 nm), and light for other wavelength ranges (for example, blue light near 450 nm, red light near 650 nm). Leakage is not considered. For this reason, for example, when black is displayed and observed from an oblique direction, the so-called color shift problem of coloring blue or red has not been solved.

Japanese Patent No. 2587398 JP-A-62-210423 Japanese Patent No. 3027805 Japanese Patent No. 3330574

  The present invention has been made in view of such circumstances, and an object thereof is to provide an optical film having a high contrast ratio over a wide range and capable of suppressing color shift, an optical compensation film using the same, a polarizing plate, and a liquid crystal display device. And

These objects have been achieved by the following means.
1. The repeating unit represented by the above formula (A), which satisfies the retardation of the following formulas (1) to (4), consists of a repeating unit represented by the following formula (A) and a repeating unit represented by the following formula (B). An optical film containing a polycarbonate copolymer comprising 80 to 30 mol% of the total and / or a blend containing the polycarbonate copolymer.
(1) 0.1 <Re (450) / Re (550) <0.95
(2) 1.03 <Re (650) / Re (550) <1.93
(3) 0.4 <(Re (450) / Rth (450)) / (Re (550) / Rth (550)) <0.95
(4) 1.05 <(Re (650) / Rth (650)) / (Re (550) / Rth (550)) <1.90
(In the formula, Re (λ) is an in-plane retardation value of the film with respect to light of wavelength λ nm, and Rth (λ) is a retardation value of the film in the thickness direction with respect to light of wavelength λ nm (unit: : Nm).)

(In the above formula (A), R _{1 to} R ₈ are each independently at least one group selected from a hydrogen atom, a halogen atom and a hydrocarbon group having 1 to 6 carbon atoms, and X is the following formula (X):

R ₉ and R ₁₀ are each independently a hydrogen atom, a halogen atom or an alkyl group having 1 to 3 carbon atoms. )

(In the above formula (B), R _{11 to} R ₁₈ are each independently at least one group selected from a hydrogen atom, a halogen atom, and a hydrocarbon group having 1 to 22 carbon atoms, and Y represents the following group of formulas:

Is selected from, wherein _R 19 _{~R 21, R 23} and _{R 24} is at least one group each independently a hydrogen atom, selected from a halogen atom and a hydrocarbon group having 1 to 22 carbon _{atoms, R 22} and R ₂₅ is each independently at least one group selected from hydrocarbon groups having 1 to 20 carbon atoms, and Ar _{1 to} Ar ₃ are each independently at least one group selected from aryl groups having 6 to 10 carbon atoms. It is a group. )
2. The optical film is a polycarbonate copolymer in which the repeating unit represented by the following formula (C) accounts for 30 to 60 mol% of the whole and the repeating unit represented by the following formula (D) accounts for 70 to 40 mol% of the whole and / or 2. The optical film as described in 1 above, which contains a blend containing a polycarbonate copolymer.

(In the formula (C), R _{26 to} R ₂₇ are each independently selected from a hydrogen atom or a methyl group.)

(In the formula (D), R _{28 to} R ₂₉ are each independently selected from a hydrogen atom or a methyl group.)
3. 3. The optical film as described in 1 or 2 above, further comprising at least one retardation developer comprising a rod-like compound or a discotic compound.
4). 4. The optical film according to any one of 1 to 3 above, wherein the optical film is formed by solution casting and wet-stretched in a range of 5 to 50% by mass of the residual solvent. Optical film.
5. 5. The optical film as described in any one of 1 to 4 above, which satisfies the following formulas (5) and (6).
(5) 5 <Re (550) <200
(6) 10 <Rth (550) <400
6). An optical compensation film comprising the optical film according to any one of 1 to 5 and an optically anisotropic layer having Re (550) of 0 to 200 nm and Rth (550) of −400 to 400 nm.
7). 7. The optical compensation film according to 6, wherein the optically anisotropic layer includes a layer formed from discotic liquid crystalline molecules.
8). 7. The optical compensation film as described in 6 above, wherein the optically anisotropic layer includes a layer formed from rod-like liquid crystalline molecules.
9. 7. The optical compensation film as described in 6 above, wherein the optically anisotropic layer comprises a polymer film.
10. 10. The optical compensation film as described in 9 above, wherein the polymer film contains at least one polymer material selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide polyesterimide and polyaryletherketone.
11. A polarizing plate produced by laminating the optical film according to any one of 1 to 5 or the optical compensation film according to any one of 6 to 10 and a polarizer.
12 A liquid crystal display device comprising the optical film according to any one of 1 to 5, the optical compensation film according to any one of 6 to 10, or the polarizing plate according to 11.
13. The optical film according to any one of 1 to 5, the optical compensation film according to any one of 6 to 10 or the polarizing plate according to 11 is disposed on one side of a liquid crystal cell, and the following formula (7 A liquid crystal display device comprising a film satisfying () to (11).
(7) 0 <Re (550) <10
(8) 30 <Rth (550) <400
(9) 10 <Rth (550) / Re (550)
(10) 1.0 <Rth (450) / Rth (550) <2.0
(11) 0.5 <Rth (650) / Rth (550) <1.0
(In the formula, Re (λ) is an in-plane retardation value of the film with respect to light of wavelength λ nm, and Rth (λ) is a retardation value of the film in the thickness direction with respect to light of wavelength λ nm (unit: : Nm).)
14 The optical film according to any one of 1 to 5, the optical compensation film according to any one of 6 to 10 or the polarizing plate according to 11 described above is used one by one above and below a liquid crystal cell. Liquid crystal display device.
15. 15. The liquid crystal display device according to any one of 12 to 14, which has a structure in which a major axis of liquid crystal molecules in a liquid crystal cell is oriented in a direction substantially perpendicular to a panel surface in a state in which no voltage is applied.

The present invention has been completed based on the knowledge obtained as a result of diligent studies by the present inventors, and the in-plane retardation and thickness of the optical compensation film can be selected by appropriately selecting materials and manufacturing methods. The wavelength dispersion of the directional retardation is independently controlled to obtain an optical optimum value, and the viewing angle compensation of the black state of a liquid crystal cell, particularly a VA mode liquid crystal cell, is enabled at almost all wavelengths. 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. Has been greatly improved. According to the present invention, an optical film having a high contrast ratio over a wide range and capable of suppressing a color shift, an optical compensation film using the same, a polarizing plate, and a liquid crystal display device can be provided.

The operation of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of a general VA mode liquid crystal display device. The VA mode liquid crystal display device includes a liquid crystal cell 3 having a liquid crystal layer in which liquid crystal is vertically aligned with respect to a substrate surface when no voltage is applied, that is, black display,
The polarizing plate 1 and the polarizing plate 2 are disposed so that the transmission axis directions (shown by stripes in FIG. 1) are orthogonal to each other. In FIG. 1, light enters from the polarizing plate 1 side. When light traveling in the normal direction, that is, the z-axis direction is incident when no voltage is applied, the light that has passed through the polarizing plate 1 passes through the liquid crystal cell 3 while maintaining the linearly polarized state. Completely shaded. As a result, an image with high contrast can be displayed.

  However, as shown in FIG. 2, the situation is different in the case of oblique light incidence. When light is incident from an oblique direction that is not the z-axis direction, that is, an oblique direction with respect to the polarization direction of the polarizing plates 1 and 2 (so-called OFF AXIS), the incident light passes through the vertically aligned liquid crystal layer of the liquid crystal cell 3. When passing, the polarization state changes due to the influence of the oblique retardation. Furthermore, the apparent transmission axes of the polarizing plate 1 and the polarizing plate 2 deviate from the orthogonal arrangement. Due to these two factors, the incident light from the oblique direction in OFF AXIS is not completely shielded by the polarizing plate 2, and light leakage occurs during black display, resulting in a decrease in contrast.

  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 FIGS. 1 and 2. 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 diagonal direction in OFF AXIS described above mainly refers to the case where the polar angle is not 0 degree and the azimuth angle is 45 degrees, 135 degrees, 225 degrees, and 315 degrees.

In FIG. 3, the schematic diagram about the structural example for demonstrating the effect | action of this invention is shown. The configuration of FIG. 3 is a configuration in which an optical film 4 is disposed between the liquid crystal cell 3 and the polarizing plate 1 in the configuration of FIG.
The optical film 4 is as described above.
(1) 0.1 <Re (450) / Re (550) <0.95
(2) 1.03 <Re (650) / Re (550) <1.93
(3) 0.4 <(Re (450) / Rth (450)) / (Re (550) / Rth (550)) <0.95
(4) 1.05 <(Re (650) / Rth (650)) / (Re (550) / Rth (550)) <1.90
Meet the relationship. In the present invention, by using the optical film having the optical characteristics, optical compensation is performed with respect to light of R, G, and B wavelengths incident in an oblique direction with different slow axes and retardations for the respective wavelengths. It is possible. As a result, as compared with the conventional liquid crystal display device, the viewing angle contrast of the black display is remarkably improved, and the coloring in the viewing angle direction of the 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. This is because the value of Re / Rth determines the axes of two intrinsic polarizations in the propagation of light traveling obliquely through a biaxial birefringent medium. FIG. 4 shows an example of a calculation result of the relationship between Re / Rth and the direction of one axis of two intrinsic polarizations when light traveling in an oblique direction is incident on the optical film used in the present invention. The light propagation direction was assumed to be azimuth = 45 degrees and polar angle = 34 degrees. From the results shown in FIG. 4, it can be seen that if Re / Rth is determined, one axis of intrinsic polarization is determined. How the polarization state of incident light changes by passing through the optical film is mainly determined by the in-plane slow axis orientation of the optical film and the retardation of the optical film. In the present invention, by defining the Re / Rth relationship for each of the R, G, and B wavelengths, both the in-plane slow axis and the retardation, which are factors that mainly determine the change in the polarization state, are R, Optimized for G and B wavelengths. As a result, light is incident from an oblique direction, affected by the retardation in the oblique direction of the liquid crystal layer, and there are two factors, that is, the apparent transmission axes of the polarizing plate 1 and the polarizing plate 2 are deviated. However, complete compensation with one optical compensation film 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.

  In the VA mode, since the liquid crystal is vertically aligned when no voltage is applied, that is, when displaying black, the polarization state of light incident from the normal direction is not affected by the retardation of the optical film 4 when displaying black. Further, it is preferable that the in-plane slow axis of the optical film 4 is perpendicular or parallel to the polarizing plate 1 or the polarizing plate 2. An optical film may be disposed between the polarizing plate 2 and the liquid crystal cell 3, and in this case, the in-plane slow axis of the optical film may be perpendicular or parallel to the polarizing plate 1 or the polarizing plate 2. preferable.

  FIG. 5 is a diagram illustrating the compensation mechanism in the configuration of FIG. 3 using a Poincare sphere. Here, the propagation directions of light are azimuth = 45 degrees and polar angle = 34 degrees. In FIG. 5, the S2 axis is an axis that penetrates vertically from the top to the bottom of the page, and FIG. 5 is a view of the Poincare sphere viewed from the positive direction of the S2 axis. In addition, since FIG. 5 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 optical 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.

  The polarization state of the incident light that has passed through the polarizing plate 1 in FIG. 3 corresponds to the point (i) in FIG. 5, and the polarization state shielded by the absorption axis of the polarizing plate 2 in FIG. It corresponds to (ii). Conventionally, in the VA mode liquid crystal display device, the light leakage of OFF AXIS in the oblique direction is caused by the deviation of the point (i) and the point (ii). The optical film is generally used for changing the polarization state of incident light from the point (i) to the point (ii) including the change of the polarization state in the liquid crystal layer. Since the liquid crystal layer of the liquid crystal cell 3 exhibits positive refractive index anisotropy and is vertically aligned, the change in the polarization state of incident light due to passing through the liquid crystal layer is the top in FIG. 5 on the Poincare sphere. Indicated by a downward arrow from, and expressed as rotation about the S1 axis. Therefore, in order for the visible light after passing through the liquid crystal layer to be completely shielded by the polarizing plate 2, the starting point before rotation is the point (ii) rotated about the S1 axis for each of R, G, and B. It must be on the line. Further, the rotation angle is proportional to the value Δn′d ′ / λ obtained by dividing the effective retardation Δn′d ′ from the oblique direction of the liquid crystal layer by the wavelength, so that each of R, G, and B having different wavelengths is obtained. At the wavelength, the rotation angles do not match. Therefore, in order for all the polarization states of R, G, and B to be point (ii) after rotation, as shown in FIG. 5, the polarization states of R, G, and B before rotation are the points (ii). ) On the line rotated around the S1 axis, and at a point corresponding to each rotation angle. In the present invention, after passing through the optical film 4 and before passing through the liquid crystal cell 3, the respective R, G, and B polarization states are set to the above-described polarization states. An optical film satisfying a certain relationship is arranged to perform optical compensation.

  On the other hand, an example of the prior art is similarly shown in FIG. The example shown in FIG. 6 is an example when an optical compensation film having a constant Re / Rth with respect to the wavelength is used. In this case, for example, even if the optical characteristics of the optical compensation film are adjusted so that the starting point before rotation by the liquid crystal layer is positioned on the line rotated about the S1 axis with respect to the G light, R Light and B light cannot be positioned on such a line. Therefore, the R and B lights that have passed through the liquid crystal layer do not change to the polarization state at the point (ii) and cannot be completely shielded by the absorption axis of the polarizing plate. As a result, light loss of R light and B light occurs, and color misregistration occurs in black display. The same applies when using an optical compensation film optimized for only R light and B light.

  In the present invention, the film has optical characteristics in which the wavelength dispersion of the retardation is different between the normal direction and an oblique direction inclined with respect to the normal direction, for example, the polar angle direction of 60 degrees, and it is actively used for optical compensation. It is characterized by being used for. The scope of the present invention 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 VA mode, IPS mode, ECB mode, TN mode, and OCB mode. .

Next, with respect to the optical film of the present invention, optical characteristics, raw materials, production methods and the like will be described in more detail.
The optical film of the present invention can be effectively used as an optical compensation film for a liquid crystal display device, and particularly contributes to an increase in the viewing angle contrast of a VA mode liquid crystal display device and a reduction in color shift depending on the viewing angle. The optical film of the present invention may be disposed between the observer-side polarizing plate and the liquid crystal cell, may be disposed between the back-side polarizing plate and the liquid crystal cell, or may be disposed on both. Good. For example, it can be incorporated into the liquid crystal display device as an independent member, or it can function as an optical compensation film by imparting the above optical characteristics to a protective film for protecting the polarizing film, and as a member of a polarizing plate. It can also be incorporated in the liquid crystal display device.

The optical film of the present invention, as described above,
(1) 0.1 <Re (450) / Re (550) <0.95
(2) 1.03 <Re (650) / Re (550) <1.93
(3) 0.4 <(Re (450) / Rth (450)) / (Re (550) / Rth (550)) <0.95
(4) 1.05 <(Re (650) / Rth (650)) / (Re (550) / Rth (550)) <1.90
Meet the relationship.
Preferably,
(1) 0.2 <Re (450) / Re (550) <0.9,
(2) 1.05 <Re (650) / Re (550) <1.9,
(3) 0.5 <(Re (450) / Rth (450)) / (Re (550) / Rth (550)) <0.9
(4) 1.1 <(Re (650) / Rth (650)) / (Re (550) / Rth (550)) <1.8
It is.

Moreover, it is preferable that the optical film of this invention satisfy | fills following formula (5) and (6).
(5) 5 ≦ Re (550) ≦ 200
(6) 10 ≦ Rth (550) ≦ 400
Preferably, (5) 20 ≦ Re (550) ≦ 150,
(6) 50 ≦ Rth (550) ≦ 300,
It is.

(Retardation and its wavelength dispersion characteristics)
In this specification, Re (λ) and Rth (λ) respectively represent in-plane retardation and retardation in the thickness direction at a wavelength λ (under an environment of 25 ° C. and 60% RH). Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH (manufactured by Oji Scientific Instruments). Rth (λ) is 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 in-plane slow axis (determined by KOBRA 21ADH) as the tilt axis (rotation axis). And a retardation value measured by injecting light having a wavelength of λ nm from a direction tilted by −40 ° with respect to the normal direction of the film with the in-plane slow axis as the tilt axis (rotation axis). KOBRA 21ADH is calculated based on the 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 the 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. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

  Moreover, since the retardation (Rth) in the thickness direction of the entire optical film of the present invention preferably corresponds to canceling retardation of the liquid crystal layer, the preferable range varies depending on the mode of each liquid crystal layer. For example, a VA mode liquid crystal cell (for example, a VA mode liquid crystal cell having a liquid crystal layer having a product Δn · d of thickness d (μm) and refractive index anisotropy Δn of 0.2 to 1.0 μm). When used for optical compensation, it is preferably 10 to 400 nm, more preferably 50 nm to 350 nm, and even more preferably 100 to 300 nm. The Re retardation value is not particularly limited, but is generally 5 to 200 nm, preferably 20 to 150 nm, and more preferably 50 to 100 nm.

  Moreover, there is no restriction | limiting in particular regarding the thickness of an optical film, However, It is 300 micrometers or less, Preferably it is 40-250 micrometers, More preferably, it is 60-250 micrometers, It is preferable that it is 80-200 micrometers.

  The optical film of the present invention is to produce an optical compensation film satisfying the above optical characteristics by selecting a polymer raw material, its blending amount, additives, production conditions, etc., and adjusting these values to a desired range. Can do.

The polycarbonate copolymer used for the optical film of the present invention will be described.
The polycarbonate copolymer comprises a repeating unit represented by the following formula (A) and a repeating unit represented by the following formula (B), and the repeating unit represented by the above formula (A) comprises 80 to 30 mol% of the whole. Polycarbonate copolymer occupied.

In the above formula (A), R _{1 to} R ₈ are each independently selected from a hydrogen atom, a halogen atom, and a hydrocarbon group having 1 to 6 carbon atoms. Examples of the hydrocarbon group having 1 to 6 carbon atoms include alkyl groups such as methyl group, ethyl group, isopropyl group, and cyclohexyl group, and aryl groups such as phenyl group. Among these, a hydrogen atom and a methyl group are preferable.

X is the following formula (X), and R ₉ and R ₁₀ are each independently a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms. Examples of the halogen atom and the alkyl group having 1 to 3 carbon atoms include the same ones as described above.

In the above formula (B), R _{11 to} R ₁₈ are each independently selected from a hydrogen atom, a halon atom, and a hydrocarbon group having 1 to 22 carbon atoms. Examples of the hydrocarbon group having 1 to 22 carbon atoms include alkyl groups having 1 to 9 carbon atoms such as a methyl group, an ethyl group, an isopropyl group, and a cyclohexyl group, and aryl groups such as a phenyl group, a biphenyl group, and a terphenyl group. It is done. Among these, a hydrogen atom and a methyl group are preferable.

Y is the following group of formulas, R _{19 to} R ₂₁ , R ₂₃ and R ₂₄ are each independently a hydrogen atom,
It is at least one group selected from a halogen atom and a hydrocarbon group having 1 to 22 carbon atoms.
Examples of the hydrocarbon group are the same as those described above. R ₂₂ and R ₂₅ are each independently selected from hydrocarbon groups having 1 to 20 carbon atoms, such hydrocarbon groups include methylene, ethylene, propylene, butylene, cyclohexylene, phenylene, naphthylene, A terphenylene group is mentioned. Examples of Ar _{1 to} Ar ₃ include aryl groups having 6 to 10 carbon atoms such as a phenyl group and a naphthyl group.

  As said polycarbonate copolymer, the polycarbonate copolymer which consists of 30-60 mol% of repeating units shown by the following formula (C), and 70-40 mol% of repeating units shown by the following formula (D) is preferable.

  More preferably, it is a polycarbonate copolymer composed of 45 to 55 mol% of the repeating unit represented by the above formula (C) and 55 to 45 mol% of the repeating unit represented by the above formula (D).

In the above formula (C), R _{26 to} R ₂₇ are each independently a hydrogen atom or a methyl group, and preferably a methyl group from the viewpoint of handleability.

In the above formula (D), R _{28 to} R ₂₉ are each independently a hydrogen atom or a methyl group, and a hydrogen atom is preferred from the viewpoint of economy, film characteristics, and the like.

  The optical film in the present invention is preferably one using the above-described polycarbonate copolymer having a fluorene skeleton. As the polycarbonate copolymer having a fluorene skeleton, for example, a blend of polycarbonate copolymers having different composition ratios composed of the repeating unit represented by the above formula (A) and the repeating unit represented by the above formula (B) is often used. The content of the above formula (A) is preferably 80 to 30 mol%, more preferably 75 to 35 mol%, still more preferably 70 to 40 mol% of the entire polycarbonate copolymer.

  The copolymer may be a combination of two or more repeating units represented by the above formulas (A) and (B).

  Here, the molar ratio can be determined by, for example, a nuclear magnetic resonance (NMR) apparatus over the entire polycarbonate bulk constituting the optical film.

  The above polycarbonate copolymer can be produced by a known method. As the polycarbonate, a method by polycondensation of a dihydroxy compound and phosgene, a melt polycondensation method or the like is preferably used.

  The intrinsic viscosity of the polycarbonate copolymer is preferably 0.3 to 2.0 dl / g. If it is less than 0.3, there is a problem that it becomes brittle and the mechanical strength cannot be maintained. There is a problem of becoming.

The optical film of the present invention may be a composition (blend) of the polycarbonate copolymer and other polymer compounds. In this case, since the polymer compound needs to be optically transparent, it is preferable that the polymer compound is compatible with the polycarbonate copolymer, or the refractive index of each polymer is substantially equal. Specific examples of other polymers include poly (styrene-co-maleic anhydride), and the composition ratio of the polycarbonate copolymer to the polymer compound is 80 to 30% by mass of the polycarbonate copolymer, The polymer compound body is 20 to 70 mass%, preferably the polycarbonate copolymer is 80 to 40 mass%, and the polymer compound body is 20 to 60 mass%. Also in the case of a blend, two or more kinds of repeating units of the polycarbonate copolymer may be combined. In the case of a blend, a compatible blend is preferable, but even if the blend is not completely compatible, the light scattering between the components can be suppressed and the transparency can be improved by adjusting the refractive index between the components. In addition, a blend body may combine 3 or more types of materials, and can combine multiple types of polycarbonate copolymer and another high molecular compound.
The weight average molecular weight of the polycarbonate copolymer is 1,000 to 1,000,000, preferably 5,000 to 500,000. The mass average molecular weight of the other polymer compound is 500 to 100,000, preferably 1,000 to 50,000.

(Retardation expression agent)
The optical film of the present invention preferably further contains one or more retardation enhancers composed of a discotic compound or a rod-shaped compound. In-plane retardation Re and thickness-direction retardation Rth are brought close to desired values by the retardation enhancer, and further, wavelength dispersion characteristics in which Re and Rth at each wavelength satisfy formulas (1) to (4). It becomes possible. In particular, in the present invention, it is possible to bring the wavelength dispersion of Re into a desired range by the polycarbonate structure described above, so that the retardation developer can bring the wavelength dispersion of Rth mainly close to the desired range. To. To bring the Rth wavelength dispersion closer to the desired range, the Rth in the short wave region is relatively higher than that on the long wave side because the discotic compound or rod-like compound having absorption in the short wave region is oriented substantially horizontally in the film. Can be considered.

  In order to raise the Rth of the short wave region relatively higher than the long wave side, both a discotic compound and a rod-like compound can be used, but from the viewpoint of the ability to orient substantially horizontally in the film, It is more desirable to use a compound.

The retardation enhancer is an agent that increases the value of Re and Rth by 0.11 or more per micron of film thickness by adding 1 part by mass with respect to 100 parts by mass of the polymer component of the optical film of the present invention. More preferably, the retardation is increased by 0.2 or more per micron of film thickness, and more preferably by 0.3 or more per micron of film thickness.
As the disk-like or rod-like compound, a compound having at least two aromatic rings can be used.
Since the discotic compound is superior to the rod-like compound in Rth retardation expression, it is preferably used when a particularly large Rth retardation is required.
Two or more retardation developing agents may be used in combination.
The retardation developer composed of a rod-like or discotic compound preferably has maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.

(Discotic compound)
Specific examples of the retardation developing agent comprising a discotic compound preferably used in the present invention are shown below, but are not limited thereto.
In the present invention, it can be preferably used as a retardation developer composed of a discotic compound represented by the following general formula (I). The compound represented by the general formula (I) is preferable because the molecular structure is rotationally symmetric with a triazine ring as the center, and thus has high retardation expression and can be produced at low cost.
Formula (I)

In the above general formula (I):
Each R ¹ independently represents an aromatic ring or a heterocyclic ring having a substituent in at least one of the ortho, meta and para positions.
X ¹ each independently represents a single bond or —NR ³ —. Here, each R ³ independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an aryl group, or a heterocyclic group.

The aromatic ring represented by R ¹ is preferably phenyl or naphthyl, and particularly preferably phenyl. The aromatic ring represented by R ¹ may have at least one substituent at any substitution position. Examples of the substituent include a halogen atom, hydroxyl, cyano, nitro, carboxyl, alkyl group, alkenyl group, aryl group, alkoxy group, alkenyloxy group, aryloxy group, acyloxy group, alkoxycarbonyl group, alkenyloxycarbonyl group. , Aryloxycarbonyl group, sulfamoyl group, alkyl-substituted sulfamoyl group, alkenyl-substituted sulfamoyl group, aryl-substituted sulfamoyl group, sulfonamide group, carbamoyl, alkyl-substituted carbamoyl group, alkenyl-substituted carbamoyl group, aryl-substituted carbamoyl group, amide group, alkylthio group , An alkenylthio group, an arylthio group, and an acyl group.

The heterocyclic group represented by R ¹ preferably has aromaticity. The heterocycle having aromaticity is generally an unsaturated heterocycle, preferably a heterocycle having the largest number of double bonds. The heterocyclic ring is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and most preferably a 6-membered ring. The hetero atom of the heterocyclic ring is preferably a nitrogen atom, a sulfur atom or an oxygen atom, and particularly preferably a nitrogen atom. As the heterocyclic ring having aromaticity, a pyridine ring (2-pyridyl or 4-pyridyl as the heterocyclic group) is particularly preferable. The heterocyclic group may have a substituent. Examples of the substituent of the heterocyclic group are the same as the examples of the substituent of the aryl moiety.
When X ¹ is a single bond, the heterocyclic group is preferably a heterocyclic group having a free valence on the nitrogen atom. The heterocyclic group having a free valence on the nitrogen atom is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and a 5-membered ring. Is most preferred. The heterocyclic group may have a plurality of nitrogen atoms. In addition, the heterocyclic group may have a hetero atom other than the nitrogen atom (eg, O, S). Examples of heterocyclic groups having free valences on nitrogen atoms are shown below.

As described above, in the general formula (I), X ¹ represents a single bond or —NR ³ —. R ³ independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an aryl group, or a heterocyclic group. The alkyl group represented by R ³ may be a cyclic alkyl group or a chain alkyl group, but a chain alkyl group is preferable, and a linear alkyl group is more preferable than a branched chain alkyl group. preferable. The number of carbon atoms in the alkyl group is preferably 1-30, more preferably 1-20, further preferably 1-10, still more preferably 1-8, and 1-6. Most preferred. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, an alkoxy group (for example, methoxy, ethoxy) and an acyloxy group (for example, acryloyloxy, methacryloyloxy).

The alkenyl group represented by R ³ may be a cyclic alkenyl group or a chain alkenyl group, but preferably represents a chain alkenyl group, and is a straight chain alkenyl group rather than a branched chain alkenyl group. More preferably it represents a group. The number of carbon atoms in the alkenyl group is preferably 2 to 30, more preferably 2 to 20, still more preferably 2 to 10, still more preferably 2 to 8, 6 is most preferred. The alkenyl group may have a substituent. Examples of the substituent are the same as those of the alkyl group described above.
The aromatic ring group and heterocyclic group represented by R ³ are the same as the aromatic ring and heterocyclic ring represented by R ¹ , and the preferred range is also the same. The aromatic ring group and heterocyclic group may further have a substituent, and examples of the substituent are the same as those of the aromatic ring and heterocyclic ring of R ¹ .

The molecular weight of the retardation developer composed of the discotic compound represented by the general formula (I) is preferably 300 to 800.
In addition, a UV absorber may be used in combination with a retardation developer composed of a discotic compound represented by the general formula (I). The amount of the UV absorber used is preferably 10% or less, more preferably 3% or less, in terms of a mass ratio with respect to the retardation developer composed of the discotic compound represented by the general formula (I).

  Specific examples of the retardation enhancer comprising the discotic compound represented by the general formula (I) used in the present invention are shown below. Several R shown in each example means the same group. The definition of R is shown after the formula together with the specific example number.

(1) phenyl (2) 3-ethoxycarbonylphenyl (3) 3-butoxyphenyl (4) m-biphenylyl (5) 3-phenylthiophenyl (6) 3-chlorophenyl (7) 3-benzoylphenyl (8) 3 Acetoxyphenyl (9) 3-benzoyloxyphenyl (10) 3-phenoxycarbonylphenyl (11) 3-methoxyphenyl (12) 3-anilinophenyl (13) 3-isobutyrylaminophenyl (14) 3-phenoxy Carbonylaminophenyl (15) 3- (3-ethylureido) phenyl (16) 3- (3,3-diethylureido) phenyl (17) 3-methylphenyl (18) 3-phenoxyphenyl (19) 3-hydroxyphenyl

(20) 4-ethoxycarbonylphenyl (21) 4-butoxyphenyl (22) p-biphenylyl (23) 4-phenylthiophenyl (24) 4-chlorophenyl (25) 4-benzoylphenyl (26) 4-acetoxyphenyl ( 27) 4-Benzoyloxyphenyl (28) 4-phenoxycarbonylphenyl (29) 4-methoxyphenyl (30) 4-anilinophenyl (31) 4-isobutyrylaminophenyl (32) 4-phenoxycarbonylaminophenyl ( 33) 4- (3-Ethylureido) phenyl (34) 4- (3,3-diethylureido) phenyl (35) 4-methylphenyl (36) 4-phenoxyphenyl (37) 4-hydroxyphenyl

(38) 3,4-diethoxycarbonylphenyl (39) 3,4-dibutoxyphenyl (40) 3,4-diphenylphenyl (41) 3,4-diphenylthiophenyl (42) 3,4-dichlorophenyl (43 ) 3,4-dibenzoylphenyl (44) 3,4-diacetoxyphenyl (45) 3,4-dibenzoyloxyphenyl (46) 3,4-diphenoxycarbonylphenyl (47) 3,4-dimethoxyphenyl ( 48) 3,4-dianilinophenyl (49) 3,4-dimethylphenyl (50) 3,4-diphenoxyphenyl (51) 3,4-dihydroxyphenyl (52) 2-naphthyl

(53) 3,4,5-triethoxycarbonylphenyl (54) 3,4,5-tributoxyphenyl (55) 3,4,5-triphenylphenyl (56) 3,4,5-triphenylthiophenyl (57) 3,4,5-trichlorophenyl (58) 3,4,5-tribenzoylphenyl (59) 3,4,5-triacetoxyphenyl (60) 3,4,5-tribenzoyloxyphenyl (61 ) 3,4,5-triphenoxycarbonylphenyl (62) 3,4,5-trimethoxyphenyl (63) 3,4,5-trianilinophenyl (64) 3,4,5-trimethylphenyl (65) 3,4,5-triphenoxyphenyl (66) 3,4,5-trihydroxyphenyl

(67) Phenyl (68) 3-ethoxycarbonylphenyl (69) 3-butoxyphenyl (70) m-biphenylyl (71) 3-phenylthiophenyl (72) 3-chlorophenyl (73) 3-benzoylphenyl (74) 3 Acetoxyphenyl (75) 3-benzoyloxyphenyl (76) 3-phenoxycarbonylphenyl (77) 3-methoxyphenyl (78) 3-anilinophenyl (79) 3-isobutyrylaminophenyl (80) 3-phenoxy Carbonylaminophenyl (81) 3- (3-ethylureido) phenyl (82) 3- (3,3-diethylureido) phenyl (83) 3-methylphenyl (84) 3-phenoxyphenyl (85) 3-hydroxyphenyl

(86) 4-Ethoxycarbonylphenyl (87) 4-butoxyphenyl (88) p-biphenylyl (89) 4-phenylthiophenyl (90) 4-chlorophenyl (91) 4-benzoylphenyl (92) 4-acetoxyphenyl ( 93) 4-Benzoyloxyphenyl (94) 4-phenoxycarbonylphenyl (95) 4-methoxyphenyl (96) 4-anilinophenyl (97) 4-isobutyrylaminophenyl (98) 4-phenoxycarbonylaminophenyl ( 99) 4- (3-Ethylureido) phenyl (100) 4- (3,3-diethylureido) phenyl (101) 4-methylphenyl (102) 4-phenoxyphenyl (103) 4-hydroxyphenyl

(104) 3,4-diethoxycarbonylphenyl (105) 3,4-dibutoxyphenyl (106) 3,4-diphenylphenyl (107) 3,4-diphenylthiophenyl (108) 3,4-dichlorophenyl (109) ) 3,4-Dibenzoylphenyl (110) 3,4-diacetoxyphenyl (111) 3,4-dibenzoyloxyphenyl (112) 3,4-diphenoxycarbonylphenyl (113) 3,4-dimethoxyphenyl ( 114) 3,4-dianilinophenyl (115) 3,4-dimethylphenyl (116) 3,4-diphenoxyphenyl (117) 3,4-dihydroxyphenyl (118) 2-naphthyl

(119) 3,4,5-triethoxycarbonylphenyl (120) 3,4,5-tributoxyphenyl (121) 3,4,5-triphenylphenyl (122) 3,4,5-triphenylthiophenyl (123) 3,4,5-trichlorophenyl (124) 3,4,5-tribenzoylphenyl (125) 3,4,5-triacetoxyphenyl (126) 3,4,5-tribenzoyloxyphenyl (127 ) 3,4,5-triphenoxycarbonylphenyl (128) 3,4,5-trimethoxyphenyl (129) 3,4,5-trianilinophenyl (130) 3,4,5-trimethylphenyl (131) 3,4,5-triphenoxyphenyl (132) 3,4,5-trihydroxyphenyl

(133) phenyl (134) 4-butylphenyl (135) 4- (2-methoxy-2-ethoxyethyl) phenyl (136) 4- (5-nonenyl) phenyl (137) p-biphenylyl (138) 4-ethoxy Carbonylphenyl (139) 4-butoxyphenyl (140) 4-methylphenyl (141) 4-chlorophenyl (142) 4-phenylthiophenyl (143) 4-benzoylphenyl (144) 4-acetoxyphenyl (145) 4-benzoyl Oxyphenyl (146) 4-phenoxycarbonylphenyl (147) 4-methoxyphenyl (148) 4-anilinophenyl (149) 4-isobutyrylaminophenyl (150) 4-phenoxycarbonylaminophenyl (151) 4- ( 3-ethylureido) phenyl ( 52) 4- (3,3-diethyl-ureido) phenyl (153) 4-phenoxyphenyl (154) 4-hydroxyphenyl

(155) 3-Butylphenyl (156) 3- (2-methoxy-2-ethoxyethyl) phenyl (157) 3- (5-nonenyl) phenyl (158) m-biphenylyl (159) 3-ethoxycarbonylphenyl (160 ) 3-butoxyphenyl (161) 3-methylphenyl (162) 3-chlorophenyl (163) 3-phenylthiophenyl (164) 3-benzoylphenyl (165) 3-acetoxyphenyl (166) 3-benzoyloxyphenyl (167) ) 3-phenoxycarbonylphenyl (168) 3-methoxyphenyl (169) 3-anilinophenyl (170) 3-isobutyrylaminophenyl (171) 3-phenoxycarbonylaminophenyl (172) 3- (3-ethylureido) ) Phenyl (173) 3- (3 - diethyl ureido) phenyl (174) 3-phenoxyphenyl 175 3-hydroxyphenyl

(176) 2-Butylphenyl (177) 2- (2-methoxy-2-ethoxyethyl) phenyl (178) 2- (5-nonenyl) phenyl (179) o-biphenylyl (180) 2-ethoxycarbonylphenyl (181) ) 2-butoxyphenyl (182) 2-methylphenyl (183) 2-chlorophenyl (184) 2-phenylthiophenyl (185) 2-benzoylphenyl (186) 2-acetoxyphenyl (187) 2-benzoyloxyphenyl (188) ) 2-phenoxycarbonylphenyl (189) 2-methoxyphenyl (190) 2-anilinophenyl (191) 2-isobutyrylaminophenyl (192) 2-phenoxycarbonylaminophenyl (193) 2- (3-ethylureido ) Phenyl (194) 2- (3 - diethyl ureido) phenyl (195) 2-phenoxyphenyl (196) 2-hydroxyphenyl

(197) 3,4-dibutylphenyl (198) 3,4-di (2-methoxy-2-ethoxyethyl) phenyl (199) 3,4-diphenylphenyl (200) 3,4-diethoxycarbonylphenyl (201 ) 3,4-didodecyloxyphenyl (202) 3,4-dimethylphenyl (203) 3,4-dichlorophenyl (204) 3,4-dibenzoylphenyl (205) 3,4-diacetoxyphenyl (206) 3 , 4-Dimethoxyphenyl (207) 3,4-di-N-methylaminophenyl (208) 3,4-diisobutyrylaminophenyl (209) 3,4-diphenoxyphenyl (210) 3,4-dihydroxyphenyl

(211) 3,5-dibutylphenyl (212) 3,5-di (2-methoxy-2-ethoxyethyl) phenyl (213) 3,5-diphenylphenyl (214) 3,5-diethoxycarbonylphenyl (215 ) 3,5-didodecyloxyphenyl (216) 3,5-dimethylphenyl (217) 3,5-dichlorophenyl (218) 3,5-dibenzoylphenyl (219) 3,5-diacetoxyphenyl (220) 3 , 5-Dimethoxyphenyl (221) 3,5-di-N-methylaminophenyl (222) 3,5-diisobutyrylaminophenyl (223) 3,5-diphenoxyphenyl (224) 3,5-dihydroxyphenyl

(225) 2,4-dibutylphenyl (226) 2,4-di (2-methoxy-2-ethoxyethyl) phenyl (227) 2,4-diphenylphenyl (228) 2,4-diethoxycarbonylphenyl (229) ) 2,4-didodecyloxyphenyl (230) 2,4-dimethylphenyl (231) 2,4-dichlorophenyl (232) 2,4-dibenzoylphenyl (233) 2,4-diacetoxyphenyl (234) 2 , 4-Dimethoxyphenyl (235) 2,4-di-N-methylaminophenyl (236) 2,4-diisobutyrylaminophenyl (237) 2,4-diphenoxyphenyl (238) 2,4-dihydroxyphenyl

(239) 2,3-dibutylphenyl (240) 2,3-di (2-methoxy-2-ethoxyethyl) phenyl (241) 2,3-diphenylphenyl (242) 2,3-diethoxycarbonylphenyl (243 ) 2,3-didodecyloxyphenyl (244) 2,3-dimethylphenyl (245) 2,3-dichlorophenyl (246) 2,3-dibenzoylphenyl (247) 2,3-diacetoxyphenyl (248) 2 , 3-Dimethoxyphenyl (249) 2,3-di-N-methylaminophenyl (250) 2,3-diisobutyrylaminophenyl (251) 2,3-diphenoxyphenyl (252) 2,3-dihydroxyphenyl

(253) 2,6-dibutylphenyl (254) 2,6-di (2-methoxy-2-ethoxyethyl) phenyl (255) 2,6-diphenylphenyl (256) 2,6-diethoxycarbonylphenyl (257 ) 2,6-didodecyloxyphenyl (258) 2,6-dimethylphenyl (259) 2,6-dichlorophenyl (260) 2,6-dibenzoylphenyl (261) 2,6-diacetoxyphenyl (262) 2 , 6-Dimethoxyphenyl (263) 2,6-di-N-methylaminophenyl (264) 2,6-diisobutyrylaminophenyl (265) 2,6-diphenoxyphenyl (266) 2,6-dihydroxyphenyl

(267) 3,4,5-tributylphenyl (268) 3,4,5-tri (2-methoxy-2-ethoxyethyl) phenyl (269) 3,4,5-triphenylphenyl (270) 3,4 , 5-triethoxycarbonylphenyl (271) 3,4,5-tridodecyloxyphenyl (272) 3,4,5-trimethylphenyl (273) 3,4,5-trichlorophenyl (274) 3,4,5 -Tribenzoylphenyl (275) 3,4,5-triacetoxyphenyl (276) 3,4,5-trimethoxyphenyl (277) 3,4,5-tri-N-methylaminophenyl (278) 3,4 , 5-Triisobutyrylaminophenyl (279) 3,4,5-triphenoxyphenyl (280) 3,4,5-trihydroxyphenyl

(281) 2,4,6-tributylphenyl (282) 2,4,6-tri (2-methoxy-2-ethoxyethyl) phenyl (283) 2,4,6-triphenylphenyl (284) 2,4 , 6-triethoxycarbonylphenyl (285) 2,4,6-tridodecyloxyphenyl (286) 2,4,6-trimethylphenyl (287) 2,4,6-trichlorophenyl (288) 2,4,6 -Tribenzoylphenyl (289) 2,4,6-triacetoxyphenyl (290) 2,4,6-trimethoxyphenyl (291) 2,4,6-tri-N-methylaminophenyl (292) 2,4 , 6-Triisobutyrylaminophenyl (293) 2,4,6-triphenoxyphenyl (294) 2,4,6-trihydroxyphenyl

(295) pentafluorophenyl (296) pentachlorophenyl (297) pentamethoxyphenyl (298) 6-N-methylsulfamoyl-8-methoxy-2-naphthyl (299) 5-N-methylsulfamoyl-2- Naphthyl (300) 6-N-phenylsulfamoyl-2-naphthyl (301) 5-ethoxy-7-N-methylsulfamoyl-2-naphthyl (302) 3-methoxy-2-naphthyl (303) 1- Ethoxy-2-naphthyl (304) 6-N-phenylsulfamoyl-8-methoxy-2-naphthyl (305) 5-methoxy-7-N-phenylsulfamoyl-2-naphthyl (306) 1- (4 -Methylphenyl) -2-naphthyl (307) 6,8-di-N-methylsulfamoyl-2-naphthyl (308) 6-N 2-acetoxyethyl sulfamoyl-8-methoxy-2-naphthyl (309) 5-acetoxy -7-N-phenyl-sulfamoyl-2-naphthyl (310) 3-benzoyloxy-2-naphthyl

(311) 5-acetylamino-1-naphthyl (312) 2-methoxy-1-naphthyl (313) 4-phenoxy-1-naphthyl (314) 5-N-methylsulfamoyl-1-naphthyl (315) 3 -N-methylcarbamoyl-4-hydroxy-1-naphthyl (316) 5-methoxy-6-N-ethylsulfamoyl-1-naphthyl (317) 7-tetradecyloxy-1-naphthyl (318) 4- ( 4-methylphenoxy) -1-naphthyl (319) 6-N-methylsulfamoyl-1-naphthyl (320) 3-N, N-dimethylcarbamoyl-4-methoxy-1-naphthyl (321) 5-methoxy- 6-N-Benzylsulfamoyl-1-naphthyl (322) 3,6-di-N-phenylsulfamoyl-1-naphthyl

(323) methyl (324) ethyl (325) butyl (326) octyl (327) dodecyl (328) 2-butoxy-2-ethoxyethyl (329) benzyl (330) 4-methoxybenzyl

(331) Methyl (332) phenyl (333) butyl

  In the present invention, a retardation developer comprising a discotic compound represented by the following general formula (II) can also be preferably used.

The compound represented by general formula (II) is demonstrated below.
Formula (II)

In the formula, R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁹ each independently represent a hydrogen atom or a substituent.
As the substituents represented by R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁹ , an alkyl group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably carbon number). 1-20 alkyl groups, such as methyl, ethyl, isopropyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc. ), An alkenyl group (preferably an alkenyl group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, and particularly preferably 2 to 20 carbon atoms, such as a vinyl group, an allyl group, and 2-butenyl. Group, 3-pentenyl group and the like), alkynyl group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms). A quinyl group, for example, a propargyl group, a 3-pentynyl group, and the like; an aryl group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms). Group, for example, a phenyl group, a p-methylphenyl group, a naphthyl group and the like, a substituted or unsubstituted amino group (preferably having 0 to 40 carbon atoms, more preferably 0 to 30 carbon atoms, and particularly preferably Is an amino group having 0 to 20 carbon atoms, and examples thereof include an unsubstituted amino group, a methylamino group, a dimethylamino group, a diethylamino group, and an anilino group).

An alkoxy group (preferably an alkoxy group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, and a butoxy group). Aryloxy group (preferably an aryloxy group having 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms, particularly preferably 6 to 20 carbon atoms, and examples thereof include a phenyloxy group and a 2-naphthyloxy group. An acyl group (preferably an acyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably 1 to 20 carbon atoms, such as an acetyl group, a benzoyl group, a formyl group, and a pivaloyl group. Etc.), an alkoxycarbonyl group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, and particularly preferably carbon number) To 20 alkoxy groups such as methoxycarbonyl group and ethoxycarbonyl group), aryloxycarbonyl groups (preferably having 7 to 40 carbon atoms, more preferably having 7 to 30 carbon atoms, and particularly preferably carbon atoms). An aryloxycarbonyl group having 7 to 20 carbon atoms, such as a phenyloxycarbonyl group, and an acyloxy group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, and particularly preferably 2 carbon atoms). ˜20 acyloxy groups such as an acetoxy group and a benzoyloxy group)

An acylamino group (preferably an acylamino group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, such as an acetylamino group and a benzoylamino group), alkoxycarbonyl An amino group (preferably an alkoxycarbonylamino group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, such as a methoxycarbonylamino group), aryloxy Carbonylamino group (preferably an aryloxycarbonylamino group having 7 to 40 carbon atoms, more preferably 7 to 30 carbon atoms, particularly preferably 7 to 20 carbon atoms, such as a phenyloxycarbonylamino group) Sulfonylamino group (preferably having 1 to 40 carbon atoms, more preferred Or a sulfonylamino group having 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, such as a methanesulfonylamino group and a benzenesulfonylamino group, and a sulfamoyl group (preferably having a carbon number of 0 to 40). More preferably, it is a sulfamoyl group having 0 to 30 carbon atoms, particularly preferably 0 to 20 carbon atoms, and examples thereof include a sulfamoyl group, a methylsulfamoyl group, a dimethylsulfamoyl group, and a phenylsulfamoyl group. ), A carbamoyl group (preferably a carbamoyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, such as an unsubstituted carbamoyl group, a methylcarbamoyl group, diethylcarbamoyl group Group, phenylcarbamoyl group, etc.),

An alkylthio group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, such as a phenylthio group), a sulfonyl group (preferably having 1 to 1 carbon atoms). 40, more preferably a sulfonyl group having 1 to 30 carbon atoms, particularly preferably a sulfonyl group having 1 to 20 carbon atoms, such as a mesyl group and a tosyl group, and a sulfinyl group (preferably having a carbon number of 1 to 40, more Preferably it is C1-C30, Most preferably, it is C1-C20 sulfinyl group, for example, a methane sulfinyl group, a benzene sulfinyl group, etc., a ureido group (preferably C1-C40, more preferable) Is a ureido group having 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, such as an unsubstituted ureido group or methylurea. And phosphoric acid amide groups (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably 1 to 20 carbon atoms), For example, diethyl phosphoric acid amide group, phenylphosphoric acid amide group etc. are mentioned), hydroxy group, mercapto group, halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group , A nitro group, a hydroxamic acid group, a sulfino group, a hydrazino group, an imino group, a heterocyclic group (preferably a heterocyclic group having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms such as a nitrogen atom, an oxygen atom, A heterocyclic group having a heteroatom such as a sulfur atom, for example, an imidazolyl group, a pyridyl group, a quinolyl group, a furyl group, a piperidyl group Morpholino group, benzoxazolyl group, benzimidazolyl group, benzthiazolyl group, 1,3,5-triazyl group and the like, silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms). Particularly preferred is a silyl group having 3 to 24 carbon atoms, and examples thereof include a trimethylsilyl group and a triphenylsilyl group. These substituents may be further substituted with these substituents. Further, when two or more substituents are present, they may be the same or different. If possible, they may be bonded to each other to form a ring.

The substituent represented by each of R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁹ is preferably an alkyl group, aryl group, substituted or unsubstituted amino group, alkoxy group, alkylthio group or halogen. Is an atom.

  Although the specific example of a compound represented by general formula (II) below is given, it is not limited to this.

  The retardation developing agent represented by the general formulas (I) and (II) is used in an amount of 0.01 to 20 parts by mass, preferably 0.5 to 10 parts by mass, with respect to 100 parts by mass of the raw material polymer. By using a retardation developer within this range, the retardation of the film can be appropriately controlled.

(Bar compound)
In the present invention, a rod-like compound can be preferably used in addition to the above-mentioned discotic compound.
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 can be performed using molecular orbital calculation software (eg, WinMOPAC2000, manufactured by Fujitsu Limited) to determine the molecular structure that minimizes the heat of formation of the compound. The molecular structure being linear means that the angle of the molecular structure is 140 degrees or more in the thermodynamically most stable structure obtained by calculation as described above.

As the rod-like compound, a compound represented by the following formula (I ′) is preferable.
(I ′) Ar ¹ -L ¹ -Ar ²
In the formula (I ′), Ar ¹ and Ar ² are each independently an aromatic group. 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 the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include halogen atom (F, Cl, Br, I), hydroxyl, carboxyl, cyano, amino, alkylamino group (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, Heptyl, 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, acetamido, butyramide, hexylamide, laurylamide) and non- Aromatic heterocyclic groups (eg, morpholyl, pyrazinyl) are included.

  Substituents of 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. Groups and alkyl groups are preferred. The alkyl part and alkyl group of the alkylamino group, alkoxycarbonyl group, alkoxy group and alkylthio 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 Family heterocyclic groups are 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.

In the formula (I ′), L ¹ is a divalent linking group selected from the group consisting of an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO—, and combinations 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 alkylene group preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, still more preferably 1 to 10 carbon atoms, still more preferably 1 to 8 carbon atoms. 6 is most preferred.

  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. Most preferred is 2 (vinylene or ethynylene).

The example of the bivalent coupling group which consists of combinations 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-

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

In Formula (II), L ² and L ³ are each independently a divalent linking group selected from the group consisting of an alkylene group, —O—, —CO—, and combinations 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 in 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 Most preferred is 2 (methylene or ethylene). L ² and L ³ are particularly preferably —O—CO— or —CO—O—.

  In the formula (II), X is 1,4-cyclohexylene, vinylene or ethynylene. Specific examples of the rod-like compound represented by the formula (I ′) 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 are shown below.

  The addition amount of the retardation enhancer composed of the rod-shaped compound is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer component.

  Two or more rod-shaped compounds whose maximum absorption wavelength (λmax) is shorter than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination. The rod-like compound can be synthesized with reference to methods described in literature. References include Mol. Cryst. Liq. Cryst., 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170, 43 Page (1989), J. Am. Chem. Soc., 113, 1349 (1991), 118, 5346 (1996), 92, 1582 (1970), J. Org Chem., 40, 420 (1975), Tetrahedron, 48, 16, 3437 (1992).

(Spectrum measurement of a specific example)
The ultraviolet-visible region (UV-vis) spectrum of the retardation control agent (10-trans) was measured. The retardation control agent (10-trans) was dissolved in tetrahydrofuran (without stabilizer (BHT)) and adjusted to a concentration of 10 ⁻⁵ mol / dm ³ . The solution thus prepared was measured with a measuring instrument (manufactured by Hitachi, Ltd.). As a result, the wavelength (λmax) giving the absorption maximum was 220 nm, and the extinction coefficient (ε) at that time was 15000. Similarly, in the retardation control agent (29-trans), the wavelength (λmax) giving the absorption maximum was 240 nm, and the extinction coefficient (ε) at that time was 20000. Similarly, in the retardation control agent (41-trans), the wavelength (λmax) giving the absorption maximum was 230 nm, and the extinction coefficient (ε) at that time was 16000.

  Two or more rod-shaped compounds whose maximum absorption wavelength (λmax) is shorter than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination.

(Other retardation agents)
In addition to the above, in-plane retardation Re and thickness direction retardation Rth are brought close to desired values, and Re and Rth at each wavelength have wavelength dispersion characteristics satisfying equations (1) to (4). Can be added to the optical film of the present invention without limitation.

[Other additives]
The optical film of the present invention may further contain an ultraviolet absorber such as phenyl salicylic acid, 2-hydroxybenzophenone, triphenyl phosphate, a bluing agent for changing the color, an antioxidant, and the like. Good.

  In the optical film of the present invention, a known plasticizer such as phthalic acid esters such as dimethyl phthalate, diethyl phthalate and dibutyl phthalate, tributyl phosphate is used for the purpose of improving the stretchability when the film described later is stretched. May contain phosphate ester, aliphatic dibasic ester, glycerin derivative, glycol derivative and the like.

[Film forming method]
As a method for producing the optical film of the present invention, a known film forming method can be used. The raw material may be heated to form a melt, or the raw material may be dissolved in a solvent to form a solution.

[Melting film formation]
The method for producing the optical film of the present invention may be melt film formation. A raw material such as a polymer or an additive as a raw material may be heated and melted, and may be extruded and formed into a film by injection molding. Alternatively, the raw material may be sandwiched between two heated plates and pressed to form a film.

  The temperature for heating and melting is not particularly limited as long as the polycarbonate copolymer or blend as a raw material is melted uniformly. Specifically, it is heated to a temperature equal to or higher than the melting point or softening point. In order to obtain a uniform film, it is melted by heating to a temperature higher than the melting point of the polycarbonate copolymer, preferably 5 to 40 ° C higher than the melting point, particularly preferably 8 to 30 ° C higher than the melting point. It is preferable.

[Solution casting]
In the production method of the optical film of the present invention, it is also particularly preferable to dissolve the polycarbonate copolymer, blend, additive and the like in a solvent to form a solution. In particular, solution film formation can be used as an excellent film formation method from the viewpoint of improving the surface shape of the film. As a specific method for solution casting, there is no particular limitation as long as it is a method of casting on a support substrate having a smooth surface such as a metal plate, the dope solution is directly developed on the support substrate to form a film. Alternatively, a casting method using Giesa or various coating methods using a blade can be used as appropriate. The solvent can be dried by room temperature or heat drying depending on the boiling point of the solvent used. Heating and drying can be performed in a temperature range of 30 to 200 ° C., for about 5 minutes to 2 hours, in a stationary or blasted manner according to a predetermined drying state.

  When the optical film of the present invention is formed into a solution, the film can be produced using a solution (dope) in which a polycarbonate copolymer, a blend, an additive and the like are uniformly dissolved in an organic solvent. The organic solvent preferably used as the main solvent of the optical film of the present invention is preferably a solvent selected from esters, ketones, ethers having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 7 carbon atoms. Esters, ketones and ethers may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a main solvent, such as alcoholic hydroxyl groups. It may have a functional group of In the case of the main solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

[Dissolution process]
Preparation of the solution (dope) of the optical film of the present invention is not particularly limited, and it may be performed at room temperature, further by a cooling dissolution method or a high temperature dissolution method, or a combination thereof. In the present invention, preparation of the optical film solution, and further steps such as solution concentration and filtration accompanying the dissolving step can be performed in accordance with a known film dissolving method.

[Casting]
Next, a method for producing a film by solution casting of the optical film of the present invention will be described. As the method and equipment for producing the optical film of the present invention, a solution casting film forming method and a solution casting film forming apparatus conventionally used for cellulose triacetate film production are preferably used. The dope (solution containing polycarbonate and additives) prepared from the dissolving machine (kettle) is temporarily stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is sent from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of rotations, and the dope is run endlessly from the die (slit) of the pressure die. The dry-dried dope film (also referred to as web) is peeled off from the metal support at a peeling point that is uniformly cast on the metal support and substantially rounds the metal support.

[Drying and winding]
The both ends of the obtained web are sandwiched between clips, transported by a tenter while keeping the width, dried, then transported by a roll group of a drying device, dried, and wound up to a predetermined length by a winder. The combination of the tenter and the roll group dryer varies depending on the purpose.

[Stretching]
The optical film of the present invention can be a polymer oriented film obtained by stretching an unstretched film such as polycarbonate and orienting polymer chains.

  The stretching method includes, for example, a simultaneous biaxial stretching method in which the film is spread in the width direction with a clip having a speed difference in the film flow direction, the film width direction is grasped by a pin or a clip, and the film flow direction speed of the grasped portion is There is a longitudinal uniaxial stretching method that uses the difference, a horizontal uniaxial stretching method that widens the part gripped with a tenter, etc., and a sequential combination of these stretching methods and a roll uniaxial stretching method that utilizes the difference in roll speed. Examples of the stretching method include the biaxial stretching method, and the stretching method is not particularly limited in producing the optical film of the present invention. Further, although some examples of the continuous stretching method have been given, the stretching method of the optical film of the present invention is not limited to these, and continuous stretching is preferable from the viewpoint of productivity, but it is not necessary to be continuous stretching. .

  However, in the optical film of the present invention, it is preferable to use an appropriate stretching method in order to make the desired optical performance of Re and Rth and their wavelength dependency ideal.

  In order to obtain Re and Rth wavelength dispersion in the desired state of the optical film of the present invention, it is most preferable that the film is stretched freely in the machine direction (film machine conveyance direction) and the transverse direction is necked in. Further, the same effect can be obtained by performing an operation of relaxing (shrinking) in the longitudinal direction while performing widening stretching while being held by a tenter or the like in the lateral direction. According to such a method, desired optical performance can be achieved by increasing the refractive index in the film thickness direction while orienting the polymer chain to the side with a high draw ratio. The preferred draw ratio in this method is 1.1 to 4.0 times in the machine direction, more preferably 1.2 to 3.5 times, and even more preferably 1.5 to 3.0 times.

  The next preferred stretching method for the optical film of the present invention is fixed biaxial stretching in which both the longitudinal and lateral directions are maintained, and a method in which the stretching ratio in the longitudinal direction is higher than in the transverse direction can be mentioned. The actual stretching ratio in the machine direction is 1.2 to 3.0 times, more preferably 1.3 to 2.5 times, and more preferably 1.4 to 2.0 times. The draw ratio is preferably 1.1 to 3.0 times larger than the transverse draw ratio, more preferably 1.2 to 2.5 times larger, and 1.3 to 2. It is even better to be 0 times larger. If the stretching ratio in the transverse direction is made larger than that in the longitudinal direction, it is not desirable for expressing desired Re. In addition, when both the longitudinal and lateral stretching ratios are larger than the above, the refractive index in the in-plane direction is increased and the refractive index in the thickness direction is decreased. This is especially true for the Rth value and the Rth wavelength dispersion. It ’s not good.

  At the time of stretching, the organic solvent used at the time of film formation described above may be stretched while remaining in the film. The amount of the organic solvent affects not only easiness of stretching but also Re and Rth of the finished optical film, and thus wavelength dispersion. The amount of the residual organic solvent at the time of stretching is preferably 5 to 50% by mass relative to the polymer solid content, more preferably 7 to 45% by mass, and further preferably 10 to 40% by mass.

[Residual solvent amount of film]
When the optical film of the present invention is obtained by solution casting, it is preferable to dry under conditions where the final residual solvent amount is in the range of 0.01 to 1.5% by mass. More preferably, it is 0.01-1.0 mass%. The residual solvent amount can be expressed by the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass of the web at any point, and N is the mass when M is dried at 110 ° C. for 3 hours.

[Haze]
The optical film is preferably transparent, and preferably has a haze value of 3% or less and a total light transmittance of 85% or more. The haze can be measured according to JIS K-6714 with a haze meter (HGM-2DP, Suga Test Machine).

[Laminated optical compensation film]
In the present invention, the optical 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, for example, an optically anisotropic layer using a rod-like liquid crystal or an optically anisotropic layer using a discotic liquid crystal may be used alone or in combination. . Moreover, the laminated body of the polymer film and the optically anisotropic layer which consists of a liquid crystalline compound may be sufficient. 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.

(Optical compensation film made of liquid crystalline compound)
When a liquid crystal compound is used for the production of the optical compensation film, since the liquid crystal compound has various alignment forms, the optical anisotropic layer prepared by fixing the liquid crystal compound in a specific alignment state is Desired optical properties are exhibited by a single layer or a laminate of a plurality of layers. That is, the optical compensation film may be an embodiment comprising a support and one or more optically anisotropic layers formed on the support. The retardation of the entire optical compensation 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 a liquid crystal compound is used for producing the optical compensation film, it is preferable to use a rod-like liquid crystal compound or a discotic liquid crystal compound, and a rod-like liquid crystal compound having a polymerizable group or a discotic liquid crystal compound having a polymerizable group Is more preferable.

(Optically anisotropic layer made of polymer film)
As described above, the optically anisotropic layer may be formed from a polymer film. The polymer film is formed from a polymer that can exhibit optical anisotropy. Examples of such polymers include polyolefins (eg, polyethylene, polypropylene, norbornene-based polymers), polycarbonate, polyarylate, polysulfone, polyvinyl alcohol, polymethacrylic acid ester, polyacrylic acid ester and cellulose ester (eg, cellulose triacetate). Tate, cellulose diacetate). Further, a copolymer or a polymer mixture of these polymers may be used.

  The optical anisotropy of the polymer film is preferably obtained by stretching. The stretching is preferably uniaxial stretching or biaxial stretching. Specifically, longitudinal uniaxial stretching using a difference in peripheral speed between two or more rolls, tenter stretching for grasping both sides of the polymer film and stretching in the width direction, or biaxial stretching in combination of these is preferable. In addition, using two or more polymer films, the optical properties of the entire two or more films may satisfy the above conditions. The polymer film is preferably produced by a solvent cast method in order to reduce unevenness in birefringence. The thickness of the polymer film is preferably 20 to 500 μm, and most preferably 40 to 100 μm.

  Further, as the polymer film forming the optically anisotropic layer, at least one polymer material selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide polyesterimide, and polyaryletherketone is used. A method in which a solution in which is dissolved in a solvent is applied to a substrate and the solvent is dried to form a film can also be preferably used. At this time, a method of stretching the polymer film and the base material to develop optical anisotropy and using it as an optical anisotropic layer can be preferably used, and the optical film of the present invention is preferably used as the base material. Can do. Alternatively, the polymer film may be prepared on another substrate, and the polymer film may be peeled off from the substrate and then bonded to the optical film of the present invention, and used as an optically anisotropic layer. preferable. In this method, the thickness of the polymer film can be reduced, and is preferably 50 μm or less, and more preferably 1 to 20 μm. The optically anisotropic layer preferably has Re (550) of 0 to 200 nm and Rth (550) of −400 to 400 nm. More preferably, Re (550) = 0 to 150 (nm) and Rth (550) = − 300 to 300 (nm).

[Polarizer]
When the optical film of the present invention is used as an optical compensation film, the optical compensation film may be bonded via a pressure-sensitive adhesive to a polarizing plate already prepared by bonding both sides of a polarizer with a protective film. The optical film of the present invention may be directly bonded to a polarizer as a protective film for a polarizing plate. In this case, for example, a method for producing a polyvinyl alcohol-based polarizing plate is not particularly limited, and can be produced by a general method. For example, there is a method in which the surface of an optical film is modified by alkali saponification treatment, plasma treatment, corona discharge treatment, and the like, and a polyvinyl alcohol film (PVA) is dipped in an iodine solution and bonded to both sides of a polarizer. .

In a liquid crystal display device, a substrate containing liquid crystal is usually disposed between two polarizing plates. However, a polarizing plate to which the optical film of the present invention is applied may be disposed in any part.
FIG. 7 is a diagram schematically showing a cross-sectional structure of an example of the polarizing plate of the present invention (for the sake of explanation, liquid crystal cell glass is also shown). In FIG. 7, protective films 72 and 73 are provided on both surfaces of a polarizer 71, and at least one of them has the optical film of the present invention. The polarizing plate 70 is pasted on the liquid crystal cell glass 75 through the adhesive layer 74. FIG. 8 is a diagram schematically showing a cross-sectional structure of another example of the polarizing plate of the present invention. In the embodiment of FIG. 8, the functional layer 81 as described above is provided on the polarizing plate of FIG.

[Functional layer]
When the optical film of the present invention is used as a protective film for a polarizing plate and used in a liquid crystal display device, various functional layers may be provided on the surface. These are, for example, a cured resin layer (transparent hard coat layer), an antiglare layer, an antireflection layer, an easy adhesion layer, an optical compensation layer, an alignment layer, a liquid crystal layer antistatic layer, and the like. These functional layers and materials for which the hybrid film of the present invention can be used include surfactants, slip agents, matting agents, antistatic layers, hard coat layers, and the like. No. 2001-1745, issued on March 15, 2001, Invention Association), and are described in detail on pages 32 to 45, and can be preferably used in the present invention.

[Liquid Crystal Display]
The liquid crystal display device of the present invention uses an optical film (optical compensation film), a liquid crystal cell, and a polarizing plate in combination. The optical film (optical compensation film), the liquid crystal cell, and the polarizing plate are preferably in close contact with each other, and a known pressure-sensitive adhesive or adhesive can be used for the close contact.

  The optical film of the present invention, and the optical compensation film and polarizing plate using the optical film can be applied to liquid crystal display devices in various display modes. Typical display modes include VA (Vertically Aligned), IPS (In-Plane Switching), TN (Twisted Nematic Fend), OCB (Optically Compensated Bend), STN (Super Twisted Bend), STN (Super Twisted Bend). Various display modes have been proposed such as Ferroelectric Liquid Crystal (AFLC), Anti-Ferroelectric Liquid Crystal (AFLC), and Hybrid Aligned Nematic (HAN). In addition, a display mode in which the above display mode is oriented and divided has been proposed. The effect of using the film having improved physical properties of the present invention is particularly remarkable in a large-screen liquid crystal display device, and is particularly preferably used in a VA mode liquid crystal display device used for a large TV.

9 and 10 show configuration examples of the liquid crystal display device of the present invention.
In FIG. 9, protective films 72 and 73 are provided on both surfaces of a polarizer 71, and at least one of them has the optical film of the present invention. The optical film of the present invention is preferably provided on the liquid crystal cell side. A functional layer 81 is provided on the protective film 72 (observer side). The polarizing plate 70 is pasted on the liquid crystal cell glass 92 through the adhesive layer 74. The liquid crystal cell 90 is formed by sandwiching a liquid crystal layer 91 between liquid crystal cell glasses 92 and 93, and a polarizing plate 70 ′ is bonded to the light source side liquid crystal cell glass 93 via an adhesive layer 74 ′. Yes. The polarizing plate 70 ′ is formed by providing protective films 72 ′ and 73 ′ on both surfaces of the polarizer 71 ′. In this invention, what is necessary is just to have the optical film of this invention in either the polarizing plate 70 or polarizing plate 70 ', or both.
FIG. 10 illustrates the liquid crystal display device of the present invention more specifically. In FIG. 10, the liquid crystal display device includes a liquid crystal cell including a liquid crystal layer 107 and an upper substrate 106 and a lower substrate 108 sandwiching the liquid crystal layer 107. The upper substrate 106 and the lower substrate 108 are subjected to alignment treatment on the liquid crystal surface. Polarizing films 101 and 201 are disposed so as to sandwich the liquid crystal cell. The transmission axes 102 and 202 of the polarizing films 101 and 201 are arranged orthogonal to each other and at an angle of 45 degrees with the direction in which the liquid crystal layer 107 of the liquid crystal cell is tilted in a voltage application state. Between the polarizing films 101 and 201 and the liquid crystal cell, the optical films 103a and 203a and the optically anisotropic layers 105 and 109 of the present invention are disposed, respectively.
The optical films 103a and 203a have in-plane slow axes 104a and 204a arranged in parallel with the directions of the transmission axes 102 and 202 of the polarizing films 101 and 201 adjacent thereto, respectively.
The liquid crystal layer 107 has a structure in which the major axis of liquid crystal molecules is aligned in a direction substantially perpendicular to the panel surface when no voltage is applied.

In addition, when the said optical film is arrange | positioned to one side of a liquid crystal cell, you may arrange | position films other than the optical film of this invention to the other side of a liquid crystal cell. However, it is preferable that the other film satisfy | fills following formula (7)-(11).
(7) 0 <Re (550) <10, preferably 0 <Re (550) <5,
(8) 30 <Rth (550) <400, preferably 40 <Rth (550) <300,
(9) 10 <Rth (550) / Re (550), preferably 15 <Rth (550) /
Re (550),
(10) 1.0 <(Rth (450) / Rth (550)) <2.0, preferably 1.0
5 <(Rth (450) / Rth (550)) <1.9,
(11) 0.5 <(Rth (650) / Rth (550)) <1.0, preferably 0.5
5 <(Rth (650) / Rth (550)) <0.95.

  Moreover, you may use various optical films, such as a prism sheet and a diffusion film, between members, such as said optical film, a liquid crystal cell, and a polarizing plate, in the liquid crystal display device of this invention.

  The preferred values for the in-plane retardation and the thickness direction retardation of the optical film vary slightly depending on the retardation value in the thickness direction of the liquid crystal and the average refractive index n of the liquid crystal and the optical film, but are optimized according to the purpose. I want to do it.

  Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

  The monomer structures of the polycarbonates used in the following examples and comparative examples are shown below. The polymer copolymerization ratio was measured by proton NMR of “JNM-alpha600” (manufactured by JEOL Ltd.). In particular, in the case of a copolymer of bisphenol A (BPA) and biscresol fluorene (BCF), heavy benzene was used as a solvent, and calculation was performed from the proton intensity ratio of each methyl group.

[Example 1]
A reaction vessel equipped with a stirrer, a thermometer and a reflux condenser was charged with an aqueous sodium hydroxide solution and ion-exchanged water, and the monomers (E) and (F) having the above structure were dissolved in a molar ratio of 47:53 in this, A small amount of hydrosulfite was added. Next, methylene chloride was added thereto, and phosgene was blown in at about 20 ° C. over about 60 minutes. Further, p-tert-butyphenol was added to emulsify, and then triethylamine was added and stirred at 30 ° C. for about 3 hours to complete the reaction. After completion of the reaction, the organic phase was separated and methylene chloride was evaporated to obtain a polycarbonate copolymer. The composition ratio of the obtained copolymer was almost equal to the monomer charge ratio.

  The following discotic compound was dissolved in methylene chloride at a ratio of 3 parts by mass with respect to 100 parts by mass of the copolymer to prepare a dope solution having a solid content concentration of 18% by mass. This dope solution is continuously cast from a die to a stainless steel band, peeled off from the band with a residual solvent amount of 20% by mass, and then 1.8 times in the longitudinal direction between rolls with a speed difference in a 200 ° C. drying zone. Free uniaxial stretching. Furthermore, an optical film having the characteristics shown in Table 1 was obtained through a zone for drying the residual solvent amount to less than 1% by mass.

[Comparative Example 1]
A film having the characteristics shown in Table 1 was obtained in the same manner as in Example 1 without adding a discotic compound to the polycarbonate copolymer of Example 1.

[Comparative Example 2]
A dope solution having a solid content concentration of 18% by mass was prepared without adding a discotic compound to the polycarbonate copolymer of Example 1. This dope solution is continuously cast from a die to a stainless steel band, peeled off from the band with a residual solvent amount of 20% by mass, and then 1.8 times in the longitudinal direction between rolls with a speed difference in a 200 ° C. drying zone. Thereafter, the film was uniaxially stretched 2.0 times in the transverse direction in the tenter zone. Further, an optical film having the characteristics shown in Table 1 was obtained through a zone for drying the residual solvent amount to less than 1%.

[Example 2]
Using the same dope solution as used in Example 1, this dope solution was continuously cast from a die to a stainless steel band, peeled off from the band with a residual solvent amount of 20% by mass, and then placed in a 200 ° C. drying zone. The rolls were subjected to free uniaxial stretching of 1.4 times in the machine direction between rolls with different speeds. Furthermore, an optical film having the characteristics shown in Table 1 was obtained through a zone for drying the residual solvent amount to less than 1% by mass.

[Comparative Example 3]
A film having the characteristics shown in Table 1 was obtained in the same manner as in Example 2 without adding a discotic compound to the polycarbonate copolymer of Example 1.

[Example 3]
Instead of adding the discotic compound to the polycarbonate copolymer of Example 1, the following rod-shaped compound was dissolved in methylene chloride at a ratio of 3 parts by mass to prepare a dope solution having a solid content concentration of 18% by mass. This dope solution is continuously cast from a die to a stainless steel band, peeled off from the band with a residual solvent amount of 20% by mass, and then 1.6 times in the longitudinal direction between rolls with a speed difference in a 200 ° C. drying zone. Free uniaxial stretching. Furthermore, an optical film having the characteristics shown in Table 1 was obtained through a zone for drying the residual solvent amount to less than 1% by mass.

[Comparative Example 4]
A film having the characteristics shown in Table 1 was obtained in the same manner as in Example 3 except that no rod-shaped compound was added in the operation of Example 3.

  Table 1 shows the composition of the optical film of the present invention, the film forming method, the optical characteristics, and the performance when mounted on a liquid crystal display device.

(Polarizing plate processing)
The optical film sample of the present invention obtained in the above examples and the sample obtained in the comparative example were bonded together using a commercially available polarizing plate (HLC2-5618, manufactured by Sanlitz Co., Ltd.) and an adhesive, and an optical compensation film It was processed into an integrated polarizing plate.

[Example 4]
(Mounting on VA panel)
The polarizing plate on the front and back of the VA mode liquid crystal TV (LC-20C5, manufactured by Sharp Corporation) and the retardation plate are peeled off, and the optical film integrated polarizing plate obtained by processing the optical film produced in Example 1 on the back is used. A commercially available polarizing plate (HLC2-5618, manufactured by Sanlitz Co., Ltd.) was attached using a laminator roll to prepare a liquid crystal panel having the layer structure of FIG. In the figure, the protective tack means a protective film. Similarly, the samples obtained in Comparative Example 1 and Comparative Example 2 were attached in the same manner.

  Next, two sets of optical film-integrated polarizing plates obtained by processing the optical film prepared in Example 2 were prepared and pasted on both the upper and lower sides of the liquid crystal cell, thereby producing a liquid crystal panel having the layer configuration of FIG. Similarly, the sample obtained in Comparative Example 3 was attached in the same manner.

  Furthermore, the optical film integrated polarizing plate obtained by processing the optical film produced in Example 3 was attached to the front side, and a film coated with a discotic liquid crystal layer having the performance shown in Table 2 was attached from the back side of the liquid crystal cell. A liquid crystal panel with the layer structure was prepared. Similarly, the sample obtained in Comparative Example 4 was attached in the same manner.

In addition, the film which apply | coated the discotic liquid crystal layer was produced as follows.
10 cc of a 1.0 N potassium hydroxide solution (solvent: water / isopropyl alcohol / propylene glycol = 69.2 mass parts / 15 mass parts / 15.8 mass parts) on one side of Fuji Photo Film Co., Ltd., Fujitac TD80UL / M ^{2 was} applied and held at about 40 ° C. for 30 seconds, and then the alkaline solution was scraped off, washed with pure water, and water droplets were removed with an air knife. Then, it dried at 100 degreeC for 15 second.

(Preparation of alignment film)
On this tack film, an alignment film coating solution having the following composition was applied at 28 ml / m ² with a # 16 wire bar coater. The film was dried with warm air of 60 ° C. for 60 seconds and further with warm air of 90 ° C. for 150 seconds to produce an alignment film.

──────────────────────────────────────
Alignment film coating solution composition ──────────────────────────────────────
Denatured polyvinyl alcohol 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Glutaraldehyde (crosslinking agent) 0.5 parts by weight Citrate ester (AS3 manufactured by Sankyo Chemical) 0.35 parts by weight ──────── ──────────────────────────────

  Drying was performed at 25 ° C. for 60 seconds, 60 ° C. warm air for 60 seconds, and 90 ° C. warm air for 150 seconds. The alignment film thickness after drying was 1.1 μm. Further, the surface roughness of the alignment film was measured with an atomic force microscope (AFM: Atomic Force Microscope, SPI3800N, manufactured by Seiko Instruments Inc.), and found to be 1.147 nm.

(Formation of optically anisotropic layer)
The coating liquid containing the discotic liquid crystal having the following composition on the alignment film is conveyed at 20 m / min by rotating the wire bar # 4.2 in the same direction as the film conveying direction at 380 rotations. It apply | coated continuously on the alignment film surface of the produced tack film with an alignment film.

─────────────────────────────────────
Application composition of discotic liquid crystal layer ─────────────────────────────────────
The following discotic liquid crystalline compound 32.6% by mass
The following compound (additive for orienting the disk surface within 5 degrees) 0.1% by mass
Ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 3.2% by mass
Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.4% by mass
Photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 1.1% by mass
Methyl ethyl ketone 62.6% by mass
─────────────────────────────────────

  In the step of continuously heating from room temperature to 100 ° C., the solvent is dried, and thereafter, the film surface wind speed of the discotic liquid crystal compound layer is about 90 m so as to be 2.5 m / sec in the 130 ° C. drying zone. The discotic liquid crystal compound was aligned by heating for 2 seconds. Next, with the surface temperature of the film being about 130 ° C., an ultraviolet irradiation device (ultraviolet lamp: output 120 W / cm) is irradiated with ultraviolet rays for 4 seconds to advance the crosslinking reaction, and the discotic liquid crystal compound is aligned. Fixed to. Then, it was allowed to cool to room temperature and wound into a cylindrical shape to form a roll. In this way, a roll-shaped optical film was produced. The angle between the disc surface of the discotic liquid crystal compound and the tack film surface was 0 degree.

  The surface of the film coated with the discotic liquid crystal layer produced as described above on the side not coated with liquid crystal was saponified. On the other hand, one side of a commercially available Fujitac TD80UL (Fuji Photo Film Co., Ltd.) was also saponified. Further, the polarizer is made by stretching and adsorbing iodine to the polyvinyl alcohol film, and the optical film and the Fujitac coated with the saponified discotic liquid crystal prepared above are used with the polyvinyl alcohol adhesive. Pasted on both sides. In this way, a polarizing plate in which both sides of the polarizing film were protected was produced.

(Panel color viewing angle evaluation)
For each sample mounted on the liquid crystal display device with the layer configuration shown in FIGS. 11 to 13, the color change in the oblique direction from the azimuth angle of 45 degrees and the polar angle of 60 degrees when the screen is displayed in black is evaluated. did. In the color evaluation, ○ indicates no change in color (yellowish or red), Δ indicates a change in color at a polar angle of 60 degrees, but returns the polar angle from 60 degrees to 30 degrees The change in color disappears, and x indicates that there was a clear change in color at any polar angle.
None of the samples using the optical film of the present invention produced in the Examples had any coloration (change in color) even when viewed obliquely, and no light leakage was observed. On the other hand, when the sample of the comparative example was viewed from an oblique direction, light leakage was significant, and coloring of the leaking light (slightly red) was confirmed. Further, the measurement was performed when the screen was displayed in white, and the contrast ratio with the black display was determined. As a result, it was found that all of the optical films of the present invention had an excellent contrast ratio.

  As described above, the optical film having the desired properties of Re and Rth according to the present invention has an excellent high contrast ratio over a wide range and can produce an optical compensation film capable of suppressing color change. It was possible to provide a polarizing plate and a liquid crystal display device.

[Example 5]
(Optical compensation film including discotic liquid crystal layer)
In the configuration shown in FIG. 13 of Example 4, a discotic liquid crystal was applied on Fujitac TD80UL, but an optical compensation film combined with the discotic liquid crystal was produced using the optical film obtained in Example 3 instead of TD80UL. At this time, the same operation was performed except that the corona treatment was performed instead of the alkali saponification treatment performed in TD80UL, and the wire bar count was changed from # 4.2 to # 2.7. The obtained optical compensation film had Re (550) = 150 nm and Rth (550) = 175 nm.

(Evaluation of mounting on VA liquid crystal display)
Two sets of the optical compensation films prepared above were prepared and mounted with the layer configuration shown in FIG. At this time, the surface on which the discotic liquid crystal was applied was placed on the protective tack side, and the optical film was placed on the liquid crystal cell side, and each was bonded using an adhesive.

(Comparative example)
By the same operation as described above, an optical compensation film combined with a discotic liquid crystal was produced using the optical film obtained in Comparative Example 4. The obtained optical compensation film had Re (550) = 150 nm and Rth (550) = 175 nm. This was mounted in the same layer configuration as above.

  When the color viewing angle characteristics of the liquid crystal display device obtained as described above were measured, the optical compensation film using the optical film obtained in Example 3 of the present invention used the film of Comparative Example 4. The amount of change in color on the left, right, top and bottom was significantly smaller than that of the optical compensation film, and the viewing angle was excellent.

[Example 6]
(Optical compensation film including polyimide layer)
Using the optical film sample of Example 2 of the present invention, an optical compensation film sample was produced according to the method described in Example 1 of JP-A-2003-315541. Synthesis from 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl (TFMB) A solution prepared by preparing a polyimide having a weight average molecular weight (Mw) of 70,000 and Δn of about 0.04 to 25 wt% using cyclohexanone as a solvent was applied to the optical film of the present invention produced in Example 2. . Thereafter, after heat treatment at 100 ° C. for 10 minutes, 15% longitudinal uniaxial stretching was performed at 160 ° C. to obtain an optical compensation film in which a 6 μm-thick polyimide film was applied to the optical film of the present invention. The optical properties of this optical compensation film are as follows: Re (550) = 72 nm, Rth (550) = 220 nm, the misalignment angle of the orientation axis is within ± 0.3 degrees, and the optical compensation film has a birefringent layer of nx>ny> nz. It was a film.

(Evaluation of mounting on VA liquid crystal display)
The side of the optical compensation film obtained as described above where the polyimide film was not applied was bonded to the protective tack of the polarizing plate via an adhesive, and mounted in the layer configuration of FIG. At this time, the optical compensation film was bonded so that the slow axis direction of the optical compensation film and the absorption axis of the polarizing plate were orthogonal to each other. Note that only the polarizing plate was bonded to the VA liquid crystal cell via an adhesive so that the absorption axes of the polarizing plate were orthogonal to each other on the opposite side of the liquid crystal cell.

(Comparative example)
An optical compensation film coated with a 6 μm-thick polyimide film was obtained in the same manner except that the film was applied to the film obtained in Comparative Example 3 instead of the optical film. The optical properties of this optical compensation film were Re (5550) = 73 nm and Rth (550) = 221 nm. This was mounted in the same layer configuration as above.

  When the color viewing angle characteristics of the liquid crystal display device obtained as described above were measured, the optical compensation film using the optical film obtained in Example 2 of the present invention used the film of Comparative Example 3. The amount of change in color on the left, right, top and bottom was significantly smaller than that of the optical compensation film, and the viewing angle was excellent.

It is a schematic diagram explaining the structural example of the liquid crystal display device of the conventional VA mode. It is a schematic diagram explaining the structural example of the liquid crystal display device of the conventional VA mode. 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 optical compensation 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 the liquid crystal display device of 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 a figure which shows typically the cross-sectional structure of an example of the polarizing plate of this invention. It is a figure which shows typically the cross-sectional structure of another example of the polarizing plate of this invention. It is a figure which shows the structural example of the liquid crystal display device of this invention. It is a figure which shows the structural example of the liquid crystal display device of this invention. It is a figure for demonstrating the layer structure of the liquid crystal panel employ | adopted in the Example. It is a figure for demonstrating the layer structure of the liquid crystal panel employ | adopted in the Example. It is a figure for demonstrating the layer structure of the liquid crystal panel employ | adopted in the Example. It is a figure for demonstrating the layer structure of the liquid crystal panel employ | adopted in the Example. It is a figure for demonstrating the layer structure of the liquid crystal panel employ | adopted in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Polarizing plate 3 Liquid crystal cell 4 Optical film 70 Polarizing plate 71, 101 Polarizer 72, 73, 103a Protective film 81 Functional layer 102 Absorption axis 104a In-plane slow axis 105 Optical compensation film 105a In-plane slow axis 106 Upper side Substrate 107 Liquid crystal layer 108 Lower substrate 109 Optical compensation film 109a In-plane slow axis 203a Protective film 204a In-plane slow axis

Claims (15)

The repeating unit represented by the above formula (A), which satisfies the retardation of the following formulas (1) to (4), consists of a repeating unit represented by the following formula (A) and a repeating unit represented by the following formula (B). An optical film containing a polycarbonate copolymer comprising 80 to 30 mol% of the total and / or a blend containing the polycarbonate copolymer.
(1) 0.1 <Re (450) / Re (550) <0.95
(2) 1.03 <Re (650) / Re (550) <1.93
(3) 0.4 <(Re (450) / Rth (450)) / (Re (550) / Rth (5
50)) <0.95
(4) 1.05 <(Re (650) / Rth (650)) / (Re (550) / Rth (550)) <1.90
(In the formula, Re (λ) is an in-plane retardation value of the film with respect to light of wavelength λ nm, and Rth (λ) is a retardation value of the film in the thickness direction with respect to light of wavelength λ nm (unit: : Nm).)

(In the above formula (A), R _{1 to} R ₈ are each independently at least one group selected from a hydrogen atom, a halogen atom and a hydrocarbon group having 1 to 6 carbon atoms, and X is the following formula (X):

R ₉ and R ₁₀ are each independently a hydrogen atom, a halogen atom or a carbon number of 1 to
3 alkyl groups. )

(In the above formula (B), R _{11 to} R ₁₈ are each independently at least one group selected from a hydrogen atom, a halogen atom, and a hydrocarbon group having 1 to 22 carbon atoms, and Y represents the following group of formulas:

Wherein R _{19 to} R ₂₁ , R ₂₃ and R ₂₄ are each independently at least one group selected from a hydrogen atom, a halogen atom and a hydrocarbon group having 1 to 22 carbon atoms;
₂₂ and R ₂₅ are each independently at least 1 selected from hydrocarbon groups having 1 to 20 carbon atoms.
Ar _{1 to} Ar ₃ each represent at least one group independently selected from aryl groups having 6 to 10 carbon atoms. ) The optical film contains 30 to 60 mol% of the repeating unit represented by the following formula (C).
The optical film of Claim 1 containing the blend body containing the polycarbonate copolymer in which the repeating unit shown by following formula (D) occupies 70-40 mol% of the whole, and / or this polycarbonate copolymer.

(In the formula (C), R _{26 to} R ₂₇ are each independently selected from a hydrogen atom or a methyl group.)

(In the formula (D), R _{28 to} R ₂₉ are each independently selected from a hydrogen atom or a methyl group.) The optical film according to claim 1, further comprising at least one retardation developer comprising a rod-like compound or a discotic compound. 4. The optical film according to any one of claims 1 to 3, wherein the optical film is formed by solution casting and wet-stretched in a range of 5 to 50% by mass of the residual solvent. Optical film. The optical film according to claim 1, wherein the following expressions (5) and (6) are satisfied.
(5) 5 <Re (550) <200
(6) 10 <Rth (550) <400 An optical compensation film comprising: the optical film according to claim 1; and an optically anisotropic layer having Re (550) of 0 to 200 nm and Rth (550) of −400 to 400 nm. The optical compensation film according to claim 6, wherein the optically anisotropic layer includes a layer formed from discotic liquid crystalline molecules. The optical compensation film according to claim 6, wherein the optically anisotropic layer includes a layer formed of rod-like liquid crystalline molecules.   The optical compensation film according to claim 6, wherein the optically anisotropic layer includes a polymer film. The optical compensation film according to claim 9, wherein the polymer film contains at least one polymer material selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide polyesterimide, and polyaryletherketone. A polarizing plate produced by laminating the optical film according to any one of claims 1 to 5 or the optical compensation film according to any one of claims 6 to 10 and a polarizer. A liquid crystal display device comprising the optical film according to claim 1, the optical compensation film according to claim 6, or the polarizing plate according to claim 11. The optical film according to any one of claims 1 to 5, the optical compensation film according to any one of claims 6 to 10, or the polarizing plate according to claim 11 is disposed on one side of the liquid crystal cell, and the following is performed on the other side. A liquid crystal display device comprising a film satisfying the formulas (7) to (11).
(7) 0 <Re (550) <10
(8) 30 <Rth (550) <400
(9) 10 <Rth (550) / Re (550)
(10) 1.0 <Rth (450) / Rth (550) <2.0
(11) 0.5 <Rth (650) / Rth (550) <1.0
(In the formula, Re (λ) is an in-plane retardation value of the film with respect to light of wavelength λ nm, and Rth (λ) is a retardation value of the film in the thickness direction with respect to light of wavelength λ nm (unit: : Nm).) The optical film according to any one of claims 1 to 5, the optical compensation film according to any one of claims 6 to 10, or the polarizing plate according to claim 11 is used one by one above and below the liquid crystal cell. A liquid crystal display device. The liquid crystal display device according to any one of claims 12 to 14, having a structure in which the major axis of liquid crystal molecules in the liquid crystal cell is aligned in a direction substantially perpendicular to the panel surface when no voltage is applied.

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