JP2008077043A - Optical compensation sheet, polarizing plate, and liquid crystal display device - Google Patents

Abstract

The present invention has a sufficient Rth for optical compensation of a liquid crystal cell (for example, optical compensation at the time of black display of a VA mode liquid crystal cell), its wavelength dispersion exhibits forward dispersion, and stable production. An optical compensation sheet that functions as a C plate is provided.
An optical compensation sheet, which is a C plate, has a transparent support C1 and an optically anisotropic layer C2 satisfying the following formulas (1) to (3), and satisfies the following formula (4). (1) 0 ≦ Re ₆₃₀ (C1) ≦ 10 (2) 0 ≦ Re ₅₅₀ (C2) ≦ 10 (3) 100 ≦ Rth ₅₅₀ (C2) −Rth ₅₅₀ (C1) (4) | Rth ₄₀₀ (C2) / Rth ₇₀₀ (C2) −Rth ₄₀₀ (C) / Rth ₇₀₀ (C) | ≦ 0.1 [where Rthλ (C) is the film thickness direction of the optical compensation sheet (laminated body of C1 and C2) at the wavelength λnm. Of the retardation value (unit: nm)].
[Selection figure] None

Description

  The present invention relates to an optical compensation sheet and a polarizing plate that contribute to the improvement of viewing angle characteristics of a liquid crystal display device, particularly a VA mode liquid crystal display device. The present invention also relates to a liquid crystal display device with improved viewing angle characteristics, and more particularly to a VA mode liquid crystal display device.

  At present, the phase difference plate is widely used in a color TFT liquid crystal display device or the like in various display modes for the purpose of improving the contrast ratio at a wide viewing angle and reducing the color shift. A biaxial film prepared by stretching a polymer film as such a retardation plate is known. Examples of the material for the polymer film include cellulose acylates, polycarbonates, norbornene polymers, and the like. A retardation plate made of these polymer films may be incorporated into a liquid crystal display device in a state of being bonded to a polarizing film.

By the way, retardation of a retardation film made of a polymer film or the like does not become a uniform value for any wavelength, but changes depending on the wavelength of incident light (hereinafter, this property is referred to as “ Called wavelength dispersion). Some polymer films exhibit wavelength dispersion (hereinafter referred to as “forward dispersion”) in which retardation increases as the wavelength of incident light decreases, and wavelength decreases as the wavelength of incident light decreases. Some exhibit dispersibility (hereinafter referred to as “reverse dispersibility”). On the other hand, the birefringence of the liquid crystal cell also has wavelength dispersion. For more ideal optical compensation of the liquid crystal cell, it is necessary to adjust in consideration of the wavelength dispersion of retardation of the retardation plate. For example, it has been proposed to use a negative C plate for optical compensation of a VA mode liquid crystal cell (for example, Patent Document 1), but the wavelength dispersion of retardation (Rth) in the thickness direction of the negative C plate is proposed. If the inclination of the VA mode liquid crystal cell is small with respect to the wavelength dispersion, the color change or light leakage depending on the viewing angle during black display increases. However, the polymer film conventionally used as the retardation plate of the VA mode liquid crystal cell is difficult to control the wavelength dispersion of retardation, and is equivalent to the birefringence wavelength dispersion (usually forward dispersion) of the liquid crystal cell. Alternatively, it is difficult to produce a retardation plate that exhibits a steeper wavelength dispersion. In particular, a polymer film shows Rth of a certain size as an absolute value, and it is difficult to develop optical characteristics in which the wavelength dispersion of the Rth is forward dispersion. There is a problem that chromatic dispersion and Rth cannot be controlled simultaneously.
JP 2004-118185 A

  The present invention has a sufficient Rth for optically compensating a liquid crystal cell (for example, optical compensation during black display of a VA mode liquid crystal cell), its wavelength dispersion exhibits forward dispersion, and is stable. It is an object of the present invention to provide an optical compensation sheet that can be manufactured and functions as a C plate. It is another object of the present invention to provide an optical compensation sheet and a polarizing plate that are useful for optical compensation of a liquid crystal display device, particularly a VA mode liquid crystal display device, and are excellent in productivity. It is another object of the present invention to provide a liquid crystal display device, particularly a VA mode liquid crystal display device, in which viewing angle characteristics, in particular, color change depending on the viewing angle are reduced.

Means for solving the above-mentioned problems are as follows.
[1] An optical compensation sheet, which is a C plate, having a transparent support C1 and an optically anisotropic layer C2 and satisfying the following formulas (1) to (4):
(1) 0 ≦ Re ₆₃₀ (C1) ≦ 10
(2) 0 ≦ Re ₅₅₀ (C2) ≦ 10
(3) 100 ≦ Rth ₅₅₀ (C2) −Rth ₅₅₀ (C1)
(4) | Rth ₄₅₀ (C2) / Rth ₅₅₀ (C2) −Rth ₄₅₀ (C) / Rth ₅₅₀ (C) | ≦ 0.1
[In the formula, Reλ (C1) is the front retardation value (unit: nm) of the transparent support C1 at the wavelength λnm, and Rthλ (C1) is the retardation value of the transparent support C1 in the film thickness direction at the wavelength λnm (unit: nm). Reλ (C2) is the front retardation value (unit: nm) at the wavelength λnm of the optically anisotropic layer C2, and Rthλ (C2) is the letter in the film thickness direction of the optically anisotropic layer C2 at the wavelength λnm. Rthλ (C) is the retardation value (unit: nm) in the film thickness direction of the optical compensation sheet (laminated body of C1 and C2) at the wavelength λnm.
[2] The optical compensation sheet according to [1], wherein the transparent support C1 and the optically anisotropic layer C2 satisfy the following formulas (5) to (8):
(5) −25 ≦ Rth ₆₃₀ (C1) ≦ 25
(6) 100 ≦ Rth ₅₅₀ (C2) ≦ 300
(7) −35 ≦ Rth ₄₀₀ (C1) −Rth ₇₀₀ (C1) ≦ 50
(8) 1.04 ≦ Rth ₄₅₀ (C2) / Rth ₅₅₀ (C2) ≦ 1.30.

[3] The optical compensation sheet according to [1] or [2], wherein the transparent support C1 and / or the optically anisotropic layer C2 is a negative C plate.
[4] The transparent support C1 is made of a cellulose acylate film, a norbornene-based polymer film, a cycloolefin polymer film, a lactone ring-containing polymer resin film, or a polycarbonate film. 3] The optical compensation sheet according to any one of 3).
[5] The optically anisotropic layer C2 is a layer formed by fixing a polymerizable liquid crystal composition containing at least one polymerizable liquid crystal compound in a liquid crystal phase state [1] to [3] Any optical compensation sheet.
[6] The optical compensation sheet according to [5], wherein the optically anisotropic layer C2 is a layer formed by fixing a polymerizable liquid crystal composition containing a rod-like liquid crystal compound in a cholesteric phase state.
[7] The optically anisotropic layer C2 is formed by fixing a polymerizable liquid crystal composition containing a discotic liquid crystal compound in a nematic liquid crystal phase by homeotropically aligning the molecules of the discotic liquid crystal compound. The optical compensation sheet of [5], which is a layer.

[8] The optical compensation sheet according to any one of [5] to [7], wherein the optically anisotropic layer C2 further contains a compound having a fluorine-based polymer including the following general formula:

一般式（１）において、Ｒ¹、Ｒ²及びＲ³はそれぞれ独立に、水素原子又は置換基を表す。Ｑはフェニル基を少なくとも１つ含有したカルボキシル基（−ＣＯＯＨ）又はその塩、スルホ基（−ＳＯ₃Ｈ）又はその塩、ホスホノキシ基｛−ＯＰ（＝Ｏ）（ＯＨ）₂｝又はその塩、親水性基（−ＯＨ）、あるいはアクリルアミド（−ＮＲ⁴−（Ｒ⁴は水素原子、アルキル基、アリール基、又はアラルキル基を表す））を有する。Ｌは下記の連結基群から選ばれる任意の基、又はそれらの２つ以上を組み合わせて形成される２価の連結基を表す；
（連結基群）
単結合、−Ｏ−、−ＣＯ−、−Ｓ−、−ＳＯ₂−、−Ｐ（＝Ｏ）（ＯＲ⁵）−（Ｒ⁵はアルキル基、アリール基、又はアラルキル基を表す）、アルキレン基及びアリーレン基。 General formula (1)

In the general formula (1), R ¹ , R ² and R ³ each independently represent a hydrogen atom or a substituent. Q is a carboxyl group containing at least one phenyl group (—COOH) or a salt thereof, a sulfo group (—SO ₃ H) or a salt thereof, a phosphonoxy group {—OP (═O) (OH) ₂ } or a salt thereof, It has a hydrophilic group (—OH) or acrylamide (—NR ⁴ — (R ⁴ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group)). L represents an arbitrary group selected from the following linking group group, or a divalent linking group formed by combining two or more thereof;
(Linked group group)
Single bond, —O—, —CO—, —S—, —SO ₂ —, —P (═O) (OR ⁵ ) — (R ⁵ represents an alkyl group, an aryl group, or an aralkyl group), an alkylene group And an arylene group.

[9] Any of [5] to [8], wherein the optically anisotropic layer C2 is a layer formed from the polymerizable liquid crystal composition further containing a polyfunctional monomer having two or more functional groups. Optical compensation sheet.
[10] The optical compensation sheet according to any one of [1] to [3], wherein the optically anisotropic layer C2 is a polymer film layer.
[11] A polarizing plate comprising the optical compensation sheet according to any one of [1] to [10] and a polarizing film.
[12] A liquid crystal display device having the optical compensation sheet of any one of [1] to [10] and / or the polarizing plate of [11].
[13] Two polarizing films disposed with their absorption axes orthogonal to each other, and a pair of substrates between the two polarizing films, and liquid crystal molecules sandwiched between the pair of substrates with respect to the substrates A liquid crystal display device having a liquid crystal cell having a liquid crystal layer substantially vertically aligned in a non-driven state to which no external electric field is applied, wherein either one of the two polarizing films and the liquid crystal cell A liquid crystal display device having the optical compensation sheet according to any one of [1] to [10].
[14] The liquid crystal display device according to [12] or [13], further having an optically anisotropic layer A satisfying the following formulas (9) to (11):
(9) 70 ≦ Re ₅₅₀ (A) ≦ 180
(10) 30 ≦ Rth ₅₅₀ (A) ≦ 140
(11) 0.80 ≦ | Re ₄₅₀ (A) / Re ₅₅₀ (A) | ≦ 1.00
[In the formula, Reλ (A) is the front retardation value (unit: nm) of the optically anisotropic layer A at the wavelength λnm, and Rthλ (A) is the retardation in the film thickness direction of the optically anisotropic layer A at the wavelength λnm. Value (unit: nm)].
[15] The optically anisotropic layer A is disposed between any one of the two polarizing films and the liquid crystal cell, and the in-plane slow axis of the optically anisotropic layer A and the polarizing film [14] The liquid crystal display device according to [14].

  According to the present invention, the liquid crystal cell has Rth sufficient to optically compensate the liquid crystal cell (for example, optical compensation at the time of black display of the VA mode liquid crystal cell), and its wavelength dispersion exhibits forward dispersion and is stable. An optical compensation sheet functioning as a C plate can be provided. In addition, according to the present invention, it is possible to provide an optical compensation sheet and a polarizing plate that are useful for optical compensation of a liquid crystal display device, particularly a VA mode liquid crystal display device, and are excellent in productivity. Further, according to the present invention, it is possible to provide a liquid crystal display device, particularly a VA mode liquid crystal display device, in which viewing angle characteristics, in particular, color change depending on the viewing angle are reduced.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, embodiments of the optical compensation film, the polarizing plate, and the liquid crystal display device of the present invention will be sequentially described. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

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

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

  In this specification, Re (λ) and Rth (λ) respectively represent in-plane retardation and retardation in the thickness direction at a wavelength λ. The measurement wavelength λ nm may be any wavelength as long as it is in the visible light range, specifically 400 to 800 nm, but is preferably in the range of 400 to 750 nm, preferably in the range of 400 nm to 700 nm. More preferably it is. In this specification, unless otherwise specified, Re and Rth mean values measured at 530 to 600 nm (or values calculated based on these values). In-plane retardation (Re) is a value measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments). When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth is calculated by the following method.

Rth is defined as Re, with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis) (in the absence of the slow axis, any direction in the film plane is the rotation axis). )) At a step of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction, light of wavelength λ nm is incident from each inclined direction, and a total of 6 points are measured, and the measured retardation value KOBRA 21ADH or WR is calculated based on the assumed average refractive index and the input film thickness value.
In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative.
In addition, the retardation value is measured from the two inclined directions, with the slow axis as the tilt axis (rotation axis) (in the absence of the slow axis, the arbitrary direction in the film plane is the rotation axis), Based on the value, the assumed value of the average refractive index, and the input film thickness value (d), Rth can also be calculated from the following equations (1) and (2).

上記式中のＲｅ(θ)は法線方向から角度θ傾斜した方向におけるレターデーション値を表す。
上記式中のｎｘは面内における遅相軸方向の屈折率を表し、ｎｙは面内においてｎｘに直交する方向の屈折率を表し、ｎｚはｎｘ及びｎｙに直交する方向の屈折率を表し、ｄは膜厚（ｎｍ）である。

Re (θ) in the above formula represents a retardation value in a direction inclined by an angle θ from the normal direction.
In the above formula, nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, nz represents the refractive index in the direction perpendicular to nx and ny, d is the film thickness (nm).

In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no so-called optic axis, Rth is calculated by the following method. Rth is the Re in 10 degree steps from −50 degrees to +50 degrees with respect to the normal direction of the film, with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis). 11 points of light having a wavelength of λ nm are incident from the inclined direction, and KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed average refractive index, and the input film thickness value. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny and nz. In this specification, unless otherwise specified, the measurement wavelength is 590 nm, and the measurement value is 25 ° C. and 60% RH.

  In this specification, the in-plane retardation Re and the thickness direction retardation Rth of the predetermined member X at the wavelength λnm are expressed as “Reλ (X)” and “Rthλ (X)”.

[Optical compensation sheet]
The present invention relates to an optical compensation sheet C which is a C plate. The optical compensation sheet C of the present invention is preferably a negative C plate. Re ₅₅₀ (C) is preferably from 0 to 10 nm, more preferably from 0 to 5 nm, and further preferably from 0 to 3 nm. Rth ₅₅₀ (C) is preferably 100 nm or more, more preferably 120 to 280 nm, and further preferably 160 to 220 nm.

The optical compensation sheet C of the present invention has a transparent support C1 and an optically anisotropic layer C2 supported by the transparent support C1. The transparent support C1 and the optically anisotropic layer C2 satisfy the following formulas (1) to (3), respectively.
(1) 0 ≦ Re ₆₃₀ (C1) ≦ 10
(2) 0 ≦ Re ₅₅₀ (C2) ≦ 10
(3) 100 ≦ Rth ₅₅₀ (C2) −Rth ₅₅₀ (C1)
The transparent support C1 and the optically anisotropic layer C2 satisfy the above formulas (1) and (2), respectively, and therefore have substantially no optical axis in the plane. On the other hand, since the transparent support C1 and the optically anisotropic layer C2 satisfy the relational expression (3), at least one of the optically anisotropic layer C2 and the transparent support C1 has a positive axis having an optical axis in the thickness direction. Or a negative C plate. The optically anisotropic layer C2 and / or the transparent support C1 is preferably a negative C plate, and both the transparent support C1 and the optically anisotropic layer C2 are preferably negative C plates.

Furthermore, the optical compensation sheet C of the present invention satisfies the following formula (4).
(4) | Rth ₄₅₀ (c2) / Rth ₅₅₀ (c2) −Rth ₄₅₀ (c) / Rth ₅₅₀ (c) | ≦ 0.1
The ratio of Rth at wavelengths of 450 nm and 550 nm (Rth ₄₅₀ / Rth ₅₅₀ ) is an index of wavelength dispersion of the member. The forward dispersive member has Rth ₄₅₀ / Rth ₅₅₀ of more than 1, and the reverse dispersive member has Rth ₄₅₀ / Rth ₅₅₀ of less than 1. Here, since the optical compensation sheet C and the optically anisotropic layer C2 of the present invention satisfy the above formula (4), the wavelength dispersion of the optical compensation sheet C is almost equal to the wavelength dispersion of the optically anisotropic layer C2. equal.

In the embodiment of the C plate in which both the transparent support C1 and the optically anisotropic layer C2 have substantially only the retardation in the thickness direction, the Rth of the optical compensation sheet C that is the laminate is the sum of both Rth. Can be approximated. Similarly, the Rth wavelength dispersion (Rth ₄₅₀ / Rth ₅₅₀ ) of the optical compensation sheet C can also be approximated by the wavelength dispersion calculated by taking the sum of both Rths for each wavelength, and the wavelength dispersion of C1 and C2 ( Rth ₅₅₀ is equal to the load average value by Rth ₅₅₀ considering the sign of Rth ₄₅₀ / Rth ₅₅₀ ). That is, the contribution ratios of C1 and C2 are substantially determined by the respective Rth values.
When the absolute value of Rth of the transparent support C1 is sufficiently small, by using the optically anisotropic layer C2 that satisfies the above formula (3), the Rth value of the optical compensation sheet C can be set to Rth of the optically anisotropic layer C2. Almost equal to the value. Therefore, in this aspect, the wavelength dispersion of Rth of the optical compensation sheet C is substantially similar to the wavelength dispersion of the optically anisotropic layer C2 that occupies most of the contribution of Rth.
The negative C plate exhibiting a high Rth value can be produced, for example, by transferring the polymerizable liquid crystal composition to a predetermined liquid crystal phase and fixing it in that state. Moreover, it can produce by apply | coating and drying the coating liquid containing predetermined polymers, such as a polyimide. The optically anisotropic layer produced by these methods becomes a negative C plate showing a high Rth value, and the wavelength dispersion of Rth of these optically anisotropic layers shows forward dispersion. In the present invention, since the optically anisotropic layer C2 is much larger than the transparent support C1 in terms of the Rth of the optical compensation sheet and its degree of contribution to wavelength dispersion, the Rth exhibits a high Rth. By using a C plate having a forward dispersibility of C as the optically anisotropic layer C2, it is possible to easily obtain a C plate having a high Rth and a wavelength dispersibility of the Rth being forward dispersive. be able to.
As described above, in the present invention, it is difficult to produce a C plate having a high Rth value and a wavelength dispersibility of the Rth value exhibiting forward dispersion only with a polymer film used as a transparent support. In order to solve this problem, the optical compensation sheet is a laminated body of a transparent support C1 made of a polymer film and an optically anisotropic layer C2, and the Rth value is determined from the contribution of Rth of the transparent support C1. The contribution of Rth of the optically anisotropic layer C2 is high, and the wavelength dispersion of the Rth can obtain forward-dispersion optical characteristics. When the optical compensation sheet of the present invention is used for optical compensation of a liquid crystal display device, in particular, a VA mode liquid crystal display device, it is possible to reduce color change depending on the viewing angle and light leakage during black display. In the present invention, since the contribution of the Rth wavelength dispersibility of the transparent support C1 is small, for example, even when a cellulose acylate film or the like in which Rth tends to exhibit reverse dispersibility is used, the Rth wavelength dispersibility is high. An optical compensation sheet exhibiting forward dispersion can be provided.

Hereinafter, a more preferable range of the optical characteristics of each member and materials used for production will be described in detail.
[Optical characteristics of transparent support C1 and optically anisotropic layer C2]
The in-plane retardation Re of the transparent support C1 is preferably 0 to 10 nm, more preferably 0 to 5 nm, and further preferably 0 to 3 nm. Further, the retardation Rth in the thickness direction is preferably −25 to 100 nm, more preferably −25 to 50 nm, and further preferably −25 nm to 25 nm. The in-plane retardation Re of the optically anisotropic layer C2 is preferably 0 to 10 nm, more preferably 0 to 5 nm, and further preferably 0 to 3 nm. Furthermore, the retardation Rth in the thickness direction is preferably 100 to 300 nm, more preferably 120 to 240 nm, and still more preferably 150 nm to 210 nm. In the present invention, it is preferable that both the transparent support C1 and the optically anisotropic layer C2 are negative C plates.

Further, the wavelength dispersion of Rth of the transparent support C1 may be either forward dispersion or reverse dispersion, but in the case of reverse dispersion, the degree of wavelength dispersion is preferably small. Specifically, Rth ₄₀₀ (C1) -Rth ₇₀₀ (C1) is preferably −35 to 50, and more preferably −25 to 25. On the other hand, the wavelength dispersion of Rth of the optically anisotropic layer C2 is almost equal to the wavelength dispersion of the optical compensation sheet C, so that the application of the optical compensation sheet C (mode of the liquid crystal display device that is the target of the optical compensation sheet). Depending on the characteristics, the preferred properties differ, but in general, the forward dispersion is preferred. The mode used for optical compensation of the VA mode liquid crystal display device is Rth ₄₅₀ (C2) / Rth ₅₅₀ (C2). Is preferably 1.04 to 1.30, more preferably 1.10 to 1.25.

[Transparent support C1]
In the present invention, the transparent support C1 is preferably made of a polymer film. As long as the optical properties required for the transparent support C1 are satisfied, the material is not particularly limited. For example, when the polarizing plate is processed by laminating the optical compensation sheet of the present invention with a polarizing film, It is necessary to function as a protective film for protecting the film. In such an embodiment, it is preferable to use a cellulose acylate film, a cycloolefin polymer, a norbornene polymer, a lactone ring-containing polymer resin film, or a polycarbonate.

In the present invention, as described above, since it is difficult to obtain a transparent support having forward dispersion having a sufficient inclination, a polymer film having a small absolute value of Rth is selected as the transparent support C1, and the optical compensation sheet C It is preferable to keep the contribution to Rth as small as possible. As the C plate having a small Rth value, cellulose acylate films described in columns 0043 to 0250 of JP-A-2006-30937, polycarbonate-based films described in JP-A-2002-22594, and recently developed Are polymer films such as lactone ring-containing polymer resin films described in JP-A No. 2006-171464 and WO 2006-112207 pamphlets.
Among these, the cellulose acylate film is preferable from the viewpoint of suitability for polarizing plate processing, and the lactone ring-containing polymer resin film has a low photoelastic coefficient, particularly when used as the transparent support C1 of the C plate. Retardation hardly occurs and is preferable.

[Optically anisotropic layer C2]
The optically anisotropic layer C2 is preferably a negative C plate having a high Rth (at least an Rth value higher than that of the transparent support C1). As long as the optical properties required for the optically anisotropic layer C2 are satisfied, the material thereof is not particularly limited, and even an optically anisotropic layer made of a polymerizable liquid crystal composition is made of an optically different material made of a polymer. It may be an isotropic layer. An optically anisotropic layer that is a negative C plate having a high Rth and a forward dispersion of Rth wavelength dispersion can be easily formed using a polymerizable liquid crystal composition.
As a method of forming an optically anisotropic layer that becomes a negative C plate with a liquid crystal composition, a liquid crystal composition containing a rod-like liquid crystal compound is applied to the surface of a transparent support, and the molecules of the rod-like liquid crystal compound are directed to molecules. And a liquid crystal composition containing a discotic liquid crystal compound is applied to the surface of the transparent support. The molecules of the cholesteric liquid crystal compound are homeotropically aligned, that is, the direction of the director of the molecules is aligned substantially perpendicular to the layer surface to form a nematic phase, and the alignment state is fixed by polymerization or the like. The method of forming is preferable.

[Bar-shaped liquid crystalline compound]
Examples of rod-like liquid crystalline compounds that can be used for forming the optically anisotropic layer C2 include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoates, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes. Cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. Not only the above low-molecular liquid crystalline compounds but also high-molecular liquid crystalline compounds can be used. As the rod-like liquid crystalline compound, those having a partial structure capable of causing polymerization or a crosslinking reaction by actinic rays, electron beams, heat, etc. are preferably used so that the alignment can be fixed by polymerization. The number of the partial structures is preferably 1 to 6, more preferably 1 to 3. As the polymerizable rod-like liquid crystalline compound, Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. No. 4,683,327, US Pat. No. 5,622,648, US Pat. No. 5,770,107, International Publication WO95 / 22586. No. 95/24455, No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, No. 6-16616, and No. 7-110469. 11-80081, JP 2001-328773, JP 2004-240188, JP 2005-99236, JP 2005-99237, JP 2005-121827, JP It is possible to use the compounds described in 2002-30042 That.

  Among the rod-like liquid crystalline compounds, as described above, liquid crystalline compounds that can be transferred to the cholesteric phase are preferable. Specifically, polymerizable liquid crystals described in columns 0077 to 0081 of JP-A No. 2004-110003 are preferable. It is preferable to use a compound and a polymerizable chiral agent.

[Discotic liquid crystalline compounds]
Discotic liquid crystalline compounds that can be used for forming the optically anisotropic layer C2 include C.I. Benzene derivatives described in a research report of Destrade et al. (Mol. Cryst. 71, 111 (1981)), C.I. Destrode et al. (Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990)). The cyclohexane derivatives described in the research report of Kohne et al. (Angew. Chem. 96, 70 (1984)) and M.M. Lehn et al. (J. Chem. Commun., 1794 (1985)), J. Chem. Azacrown-type and phenylacetylene-type macrocycles described in the research report of Zhang et al. (J. Am. Chem. Soc. 116, 2655 (1994)) are included.

The discotic liquid crystalline compound also includes a compound having a structure in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation. Preferred examples of the discotic liquid crystalline compound are described in JP-A-8-50206. Moreover, about superposition | polymerization of a discotic liquid crystalline compound, Unexamined-Japanese-Patent No. 8-27284 has description.
The same applies to the rod-like liquid crystalline compound, but the optically anisotropic layer formed from the liquid crystalline composition containing the discotic liquid crystalline compound is finally composed of the compound contained in the optically anisotropic layer. It does not need to be a compound. For example, a low molecular weight discotic liquid crystalline molecule has a group that reacts with heat or light, and as a result, it is polymerized or cross-linked by reaction with heat or light to increase the molecular weight. You may have lost.

[Fluoropolymer]
In the process of producing the optically anisotropic layer C2, in order to make the direction of the director of the molecules of the rod-like liquid crystal compound substantially parallel to the layer surface (Re is substantially 0 nm), or the molecules of the discotic liquid crystal compound In order to make the orientation of the director of the discotic molecule substantially vertical (Re is substantially 0 nm) with respect to the layer surface, fluorine containing a repeating unit represented by the following general formula (1) It is preferable that a base polymer (hereinafter sometimes referred to as “polymer A”) is present, that is, the liquid crystal composition used to form the optically anisotropic layer C2 contains at least one polymer A It is preferable to do so.

General formula (1)

In the general formula (1), R ¹ , R ² and R ³ each independently represent a hydrogen atom or a substituent. Q is a carboxyl group containing at least one phenyl group (—COOH) or a salt thereof, a sulfo group (—SO ₃ H) or a salt thereof, a phosphonoxy group {—OP (═O) (OH) ₂ } or a salt thereof, It has a hydrophilic group (—OH) or acrylamide (—NR ⁴ — (R ⁴ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group)). L represents an arbitrary group selected from the following linking group group, or a divalent linking group formed by combining two or more thereof.
(Linked group group)
Single bond, —O—, —CO—, —S—, —SO ₂ —, —P (═O) (OR ⁵ ) — (R ⁵ represents an alkyl group, an aryl group, or an aralkyl group), an alkylene group And an arylene group.

In general formula (1), R ¹ , R ² and R ³ each independently represent a hydrogen atom or a substituent exemplified in columns 0017 to 0033 of JP-A-2004-46038. The substituent is preferably an alkyl group, a halogen atom, or a group represented by -LQ. R ¹ , R ² and R ³ are each independently preferably a hydrogen atom, an alkyl group, a halogen atom or a group represented by -LQ, preferably a hydrogen atom or an alkyl group. More preferred.

L represents a divalent linking group selected from the above linking group group, or a divalent linking group formed by combining two or more thereof. In the linking group group, R ^{4 in} —NR ⁴ — represents a hydrogen atom, an alkyl group, an aryl group or an aralkyl group, preferably a hydrogen atom or an alkyl group. R ⁵ in —PO (OR ⁵ ) — represents an alkyl group, an aryl group or an aralkyl group, and preferably an alkyl group. The carbon number when R ⁴ and R ⁵ represent an alkyl group, an aryl group or an aralkyl group is the same as that described in the “substituent group”. L preferably contains a single bond, —O—, —CO—, —NR ⁴ —, —S—, —SO ₂ —, an alkylene group or an arylene group, and is a single bond, —CO—, —O—. , —NR ⁴ —, an alkylene group or an arylene group is particularly preferable, and a single bond is most preferable. When L contains an alkylene group, the alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and particularly preferably 1 to 6 carbon atoms. Specific examples of particularly preferred alkylene groups include methylene, ethylene, trimethylene, tetrabutylene, hexamethylene groups and the like. When L contains an arylene group, the carbon number of the arylene group is preferably 6 to 24, more preferably 6 to 18, and particularly preferably 6 to 12. Specific examples of particularly preferred arylene groups include phenylene and naphthalene groups. When L contains a divalent linking group (that is, an aralkylene group) obtained by combining an alkylene group and an arylene group, the carbon number of the aralkylene group is preferably 7 to 34, more preferably 7 to 26, and particularly preferably. 7-16. Specific examples of particularly preferred aralkylene groups include a phenylenemethylene group, a phenyleneethylene group, and a methylenephenylene group. The group listed as L may have a suitable substituent. Examples of such a substituent include those similar to the substituents exemplified above as the substituents for R ^{1 to} R ³ .

  In the formula (1), Q is a carboxyl group, a salt of a carboxyl group (for example, lithium salt, sodium salt, potassium salt, ammonium salt (for example, ammonium, tetramethylammonium, trimethyl-2-hydroxyethylammonium, tetrabutylammonium, trimethyl). Benzylammonium, dimethylphenylammonium, etc.), pyridinium salts, etc.), sulfo groups, salts of sulfo groups (examples of cations forming salts are the same as those described above for carboxyl groups), phosphonoxy groups, salts of phosphonoxy groups Examples of the cation that forms are the same as those described above for the carboxyl group) and a hydrophilic group (hydroxyl group). A carboxyl group, a sulfo group, a phospho group, and a hydrophilic group are more preferable, and a carboxyl group or a hydrophilic group is particularly preferable.

  The polymer A may contain one type of repeating unit represented by the general formula (1), or may contain two or more types. The polymer A may have one or more repeating units derived from the fluoroaliphatic group-containing monomer. Preferably, it contains a repeating unit derived from a fluoroaliphatic group-containing monomer represented by the general formula [1] described in JP-A-2004-333861 shown below.

In the formula, R ¹ represents a hydrogen atom or a methyl group, X represents an oxygen atom, a sulfur atom or —N (R ¹² ) —, Hf represents a hydrogen atom or a fluorine atom, and m represents an integer of 1 to 6. , N represents an integer of 2-4. R ¹² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

  Furthermore, the polymer A may contain other repeating units. The other repeating units are not particularly limited, and preferred examples thereof include repeating units derived from ordinary radical polymerizable monomers. The polymer A may contain one type of repeating unit derived from a monomer selected from the monomer group described in paragraphs [0026] to [0033] in JP-A-2004-46038, You may contain 2 or more types.

  Further, the polymer A may contain a repeating unit derived from a monomer represented by the general formula [2] described in JP-A-2004-333861.

  The mass average molecular weight of the polymer A used in the present invention is preferably 1,000,000 or less, more preferably 500,000 or less, and further preferably 5,000 or more and 50,000 or less. The mass average molecular weight can be measured as a value in terms of polystyrene (PS) using gel permeation chromatography (GPC).

  The polymerization method employed in producing the polymer A is not particularly limited, but the method described in paragraphs [0035] to [0041] in the specification of JP-A-2004-46038 can be used. It is preferable to use it.

  The polymer A may have a polymerizable group as a substituent in order to fix the alignment state of the liquid crystal compound.

  Specific examples that are preferably used in the present invention as the polymer A are shown below, but the present invention is not limited to these specific examples. Here, the numerical values (numerical values such as a, b, c, and d) in the formula are mass percentages indicating the composition ratio of each monomer, and Mw is TSK Gel GMHxL, TSK Gel G4000 HxL, TSK Gel G2000 HxL (whichever Also, the mass average molecular weight is expressed in terms of polystyrene by solvent THF and differential refractometer detection using a GPC analyzer using a column of Tosoh Corporation's trade name).

  The polymer A used in the present invention can be produced by a known and commonly used method as described above. For example, it can be produced by adding a general-purpose radical polymerization initiator to an organic solvent containing the above-mentioned monomer having a fluoroaliphatic group, a monomer having a hydrogen bonding group, and the like, and polymerizing the mixture. Further, in some cases, other addition-polymerizable unsaturated compounds can be further added and produced by the same method as described above. Depending on the polymerizability of each monomer, a dropping polymerization method in which a monomer and an initiator are added dropwise to a reaction vessel is also effective for obtaining a polymer having a uniform composition.

[Polyfunctional monomer]
For the purpose of improving the adhesion between the optically anisotropic layer C2 and the transparent support C1, it is preferable to include a polyfunctional monomer in the liquid crystalline composition for forming the optically anisotropic layer C2. The film thickness of the optically anisotropic layer C2 varies depending on the intended retardation, but is preferably 0.5 μm or more in order to develop a certain Rth value. When a 0.5 μm or more layer is formed from the polymerizable liquid crystal composition, the adhesion with the transparent support C1 interface may be significantly reduced. It is preferable to include a polyfunctional monomer having two or more functional groups in the liquid crystalline composition because the adhesion between the transparent support C1 and the optically anisotropic layer C2 can be improved.

  Polyfunctional monomers having two or more functional groups include esters of polyhydric alcohol and (meth) acrylic acid [for example, ethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (meth) Acrylate, 1,4-cyclohexanediacrylate, pentaerythritol tetra (meth) acrylate], pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra ( (Meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pentaerythritol hexa (meth) acrylate, 1,2,3-cyclo Xanthan tetramethacrylate, polyurethane polyacrylate, polyester polyacrylate], modified ethylene oxide, vinylbenzene and derivatives thereof (for example, 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4- Divinylcyclohexanone), vinyl sulfone (eg divinyl sulfone), acrylamide (eg methylene bisacrylamide) and methacrylamide. Two or more of these monomers may be used in combination.

  The optically anisotropic layer C2 is prepared by preparing a polymerizable liquid crystalline composition as a coating liquid, coating the coating liquid on the surface of the transparent support C1, drying it, transferring it to a desired liquid crystal phase, and then aligning the liquid crystal composition. It can be formed by fixing to the state by polymerization. Solvents that can be used as a coating solution, polymerization initiators that can be added to the polymerizable liquid crystalline composition, conditions such as the intensity of UV light irradiated during polymerization, Methods, conditions and the like can be referred to (for example, the materials and conditions described in JP-A-2005-173567 and the like can be referred to). For the formation of the optically anisotropic layer C2, an alignment film may be used. As an alignment film that can be used for transition to a cholesteric phase and homotropic alignment of a discotic liquid crystalline compound, JP-A The alignment film described in the 0165th column of 2005-49866 gazette etc. can be mentioned.

[Polymer for optically anisotropic layer C2]
The optically anisotropic layer C2 to be a C plate can also be formed from the polymer composition. For example, when a polymer composition formed into a film exhibits predetermined optical characteristics required for the optically anisotropic layer C2, it can be used as it is as the optically anisotropic layer C2. In addition, in order to satisfy predetermined optical characteristics, a stretched film subjected to a stretching treatment or the like, or a film produced from an oriented film can be preferably used as the optical anisotropic layer C2. Furthermore, after laminating | stacking with the transparent support body C1, you may give an extending | stretching process.

  Polymers used for forming the optically anisotropic layer C2 include acetate resin, polyester resin, polyethersulfone resin, polysulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, acrylic resin, polynorbornene resin, and cellulose. Resin, polyarylate resin, polystyrene resin, polyvinyl alcohol resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyacrylic resin, mixed resin thereof, liquid crystal polymer, and heat having a substituted or unsubstituted imide group in the side chain It is preferably at least one polymer selected from the group consisting of a mixture of a thermoplastic resin and a thermoplastic resin having a substituted phenyl group or an unsubstituted phenyl group and a nitrile group in the side chain. Among them, a stretched film selected from polycarbonate, cycloolefin-based polymer, norbornene-based polymer, and cellulose acylate film, or at least one material selected from polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide is used. More preferred is an oriented film.

The optical compensation sheet of the present invention can be bonded to a linearly polarizing film (hereinafter simply referred to as “linearly polarizing film” when referred to simply as “polarizing film”) and used as a circularly polarizing plate or an elliptically polarizing plate. In such an embodiment, the transparent support C1 is preferably a support for the optically anisotropic layer C2 and can also function as a protective film for the polarizing film. From this viewpoint, a cellulose acylate film is preferable. .
Hereinafter, the polarizing plate of the present invention to which the optical compensation film of the present invention is added will be described in detail.
[Polarizer]
The polarizing plate of the present invention has at least the optical compensation sheet of the present invention and a polarizing film.
Examples of the polarizing film include an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film. The iodine polarizing film and the dye polarizing film are generally produced using a polyvinyl alcohol film. The absorption axis of the polarizing film corresponds to the stretching direction of the film. Accordingly, the polarizing film stretched in the longitudinal direction (transport direction) has an absorption axis parallel to the longitudinal direction, and the polarizing film stretched in the lateral direction (perpendicular to the transport direction) is perpendicular to the longitudinal direction. Has an absorption axis.

  As the polymer used for the base film of the polarizing film, a polyvinyl alcohol (hereinafter referred to as PVA) polymer is generally used. As the dichroic substance, iodine or a dichroic dye is used alone or in combination. PVA is usually a saponified polyvinyl acetate, but may contain components copolymerizable with vinyl acetate such as unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, and vinyl ethers. I do not care. In addition, modified PVA containing an acetoacetyl group, a sulfonic acid group, a carboxyl group, an oxyalkylene group, or the like can also be used. The degree of saponification of PVA is not particularly limited, but is preferably 80 to 100 mol%, particularly preferably 90 to 100 mol% from the viewpoints of solubility, polarization, heat resistance, moisture resistance, and the like. The degree of polymerization of PVA is not particularly limited, but is preferably from 1000 to 10,000, particularly preferably from 1500 to 5000, from the viewpoint of film strength, heat resistance, moisture resistance, stretchability, and the like. Moreover, it does not specifically limit about the syndiotacticity of PVA, It can also take arbitrary values according to the objective.

  In order to prepare a polarizing film by dyeing and stretching PVA, a method of stretching a PVA film as a raw fabric by dry or wet and then immersing it in a solution of iodine or dichroic dye, iodine or dichroic dye There are a method of stretching and orienting a PVA film in the above solution, a method of stretching and orienting a PVA film in iodine or a dichroic dye and then wet or dry. Moreover, when forming a PVA raw fabric by a solution casting method, a method of previously containing a dichroic substance in the PVA solution can be used.

  A manufacturing method by wet stretching of a typical polarizing plate will be described below. First, the raw fabric PVA film is pre-swelled with an aqueous solution. Subsequently, it is immersed in the solution of a dichroic substance, and a dichroic substance is adsorbed. Further, it is uniaxially stretched in the traveling direction in an aqueous solution of a boron compound such as boric acid. If necessary, a color adjustment bath, a curing bath or the like may be provided after this. When it is dried to some extent, a protective film is bonded using an adhesive such as PVA. Furthermore, it dries and a polarizing plate is obtained.

  Various organic solvents, inorganic salts, plasticizers, boric acids and the like may be added to the pre-swelled solution in the aqueous solution.

  As an example of the case where iodine is used as the dichroic substance, an iodine-potassium iodide aqueous solution is used as the staining liquid. Iodine is preferably 0.1 to 20 g / liter, potassium iodide is preferably 1 to 100 g / liter, and the weight ratio of iodine and potassium iodide is preferably 1 to 100. The dyeing time is preferably 30 to 5000 seconds, and the liquid temperature is preferably 5 to 50 ° C. It is also preferable to include a compound that crosslinks PVA such as a boron compound in the dyeing solution. The boron compound in the stretching bath is particularly preferably boric acid. The boric acid concentration is preferably 1 to 200 g / liter, more preferably 10 to 120 g / liter. In addition to the boron compound, the stretching bath can contain an inorganic salt such as potassium iodide, various organic solvents, or a dichroic dye. In addition to the dichroic dye, an inorganic salt such as potassium iodide, a boron compound, and the like are contained in the color adjustment bath and the curing bath as necessary.

  The stretching process of PVA is generally a method in which tension is applied in the traveling direction of the continuous film and the film is stretched and oriented in the traveling direction as exemplified above, but the film is stretched by stretching means such as a so-called tenter method. A method of applying tension in the width direction and orienting in the width direction is also applicable. The stretching is preferably performed 3 times or more in a uniaxial direction, and more preferably 4.5 times or more. Biaxial stretching may be performed depending on the purpose of use of the polarizing film. Although the film thickness after extending | stretching is not specifically limited, 5-100 micrometers is preferable from a viewpoint of a handleability, durability, and economical efficiency, and 10-40 micrometers is more preferable. The temperature during stretching varies depending on the stretching conditions, but is usually 10 to 250 ° C. When dry stretching at a temperature of 100 ° C. or higher, it is preferably performed in an inert gas atmosphere such as nitrogen. Moreover, it is preferable to perform a crystallization treatment at a temperature of 100 ° C. or higher before dyeing a previously stretched film.

  As the dyeing method, not only the immersion method exemplified above, but also any means such as application or spraying of iodine or a dye solution is possible. In addition to the liquid layer adsorption described above, adsorption by donation can be performed as necessary. It is also preferable to dye with a dichroic dye. Specific examples of the dichroic dye include dye compounds such as azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes and anthraquinone dyes. I can give you. A water-soluble one is preferred, but not limited thereto. Further, it is preferable that a hydrophilic substituent such as a sulfonic acid group, an amino group, or a hydroxyl group is introduced into these dichroic molecules.

  Typical examples of dichroic molecules include C.I. Ai. direct. Yellow 12, sea. Ai. direct. Orange 39, sea. Ai. direct. Orange 72, sea. Ai. direct. Red 28, Sea. Ai. direct. Red 39, Sea. Ai. direct. Red 79, Sea. Ai. direct. Red 81, Sea. Ai. direct. Red 83, Sea. Ai. direct. Red 89, Sea. Ai. direct. Violet 48, C.I. Ai. direct. Blue 67, Sea. Ai. direct. Blue 90, Sea. Ai. direct. Green 59, Sea. Ai. Acid. Red 37 and the like, and further, JP-A-1-161202, JP-A-1-172906, JP-A-1-172907, JP-A-1-183602, JP-A-2000-48105, JP-A-2000-65205, Examples thereof include the dyes described in JP-A-7-261024. In particular, Sea. Ai. direct. Red 28 (Congo Red) has long been known as preferred for this application. These dichroic molecules are used as free acids or alkali metal salts, ammonium salts, and salts of amines.

  By blending two or more of these dichroic molecules, it is possible to produce polarizers having various hues. As a polarizing element or polarizing plate, a compound (pigment) that exhibits black when the polarization axes are orthogonal to each other, or a compound in which various dichroic molecules are blended so as to exhibit black is excellent in terms of both the single plate transmittance and the polarization.

  From the viewpoint of increasing the heat resistance and moisture resistance of the polarizing film, it is preferable to include an additive that crosslinks PVA in the manufacturing process of the polarizing film. As the crosslinking agent, those described in US Reissue Patent No. 232897 can be used, but boric acid and borax are preferably used practically. In addition, it is known that the polarizing film contains a metal salt such as zinc, cobalt, zirconium, iron, nickel, manganese, etc., because it is known to improve durability. These crosslinking agents and metal salts may be contained in any of the above-described pre-swelling bath, dichroic material dyeing bath, stretching bath, curing bath, color adjusting bath, etc., and the order of the steps is particularly limited. Not. The adhesive that bonds the protective film and the polarizing film is not particularly limited, and any known adhesive such as PVA, modified PVA, urethane, or acrylic can be used. The thickness of the adhesive layer is preferably from 0.01 to 20 μm, more preferably from 0.1 to 10 μm.

  The polarizing film generally has a protective film. When the optical compensation sheet of the present invention has a polymer film excellent in the function of protecting a polarizing film such as a cellulose acylate film as the transparent support C1, the transparent support C1 is used as a protective film for the polarizing film. Also good. As a protective film for the polarizing film, it is preferable to use a cellulose ester film that has low birefringence, transparency, appropriate moisture permeability, dimensional stability and the like, and has high optical isotropy.

  The preferable manufacturing method of the polarizing plate of this invention includes the process of laminating | stacking a polarizing film and the optical compensation sheet | seat of this invention continuously in a respectively elongate state. The long polarizing plate is cut according to the screen size of the liquid crystal display device used.

  As described above, when the optical compensation sheet of the present invention functions as a protective film for a polarizing film, it is not necessary to separately bond a protective film to the surface of the polarizing film to be bonded to the surface of the optical compensation sheet. In the polarizing plate of the present invention, only an isotropic adhesive layer and / or a substantially isotropic transparent protective film is included between the polarizing film and the optical compensation sheet of the present invention. Is preferred. The substantially isotropic transparent protective film (protective film for polarizing film) specifically refers to a film having an in-plane retardation of 0 to 10 nm and a thickness direction retardation of -20 to 20 nm. A film containing cellulose acylate or cyclic polyolefin is preferred. Examples of the cellulose acylate or cyclic polyolefin that can be used for the transparent protective film are the same as those of the polymer film that can be used as the transparent support C1. Moreover, as an adhesive which can form an isotropic adhesive bond layer, the adhesive agent etc. which consist of a polyvinyl alcohol-type adhesive agent, polyester-type urethane, and an isocyanate type crosslinking agent are mentioned.

  The aspect of the polarizing plate of the present invention is a polarizing plate in which the optically anisotropic layer C2, the transparent support C1, and the polarizing film are laminated in this order. When the polarizing plate of the present invention is used in a VA mode liquid crystal display device, one mode of a pair of polarizing plates is a polarizing plate having an optically anisotropic layer A and a polarizing film described later.

[Liquid Crystal Display]
The optical compensation sheet which is a negative C plate of the present invention is preferably used for optical compensation of a VA mode liquid crystal display device. In a VA mode liquid crystal cell, rod-like liquid crystal molecules are aligned substantially vertically when no voltage is applied.
The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). 176625) (2) Liquid crystal cell (SID97, Digest of tech.Papers 28 (1997) 845 in which the VA mode is converted into a multi-domain (in MVA mode) for widening the viewing angle ), (3) A liquid crystal cell in a mode (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Preliminary collections 58-59 of the Japan Liquid Crystal Society) (1998)) and (4) SURVAVAL mode liquid crystal cells (announced at LCD International 98).

[Optically anisotropic layer A]
For the optical compensation of the VA mode liquid crystal display device, when the optical anisotropic layer A satisfying the following formulas (9) to (11) is further used together with the optical compensation sheet of the present invention, the viewing angle characteristics are further improved. Therefore, it is preferable.
(9) 70 ≦ Re ₅₅₀ (A) ≦ 180
(10) 30 ≦ Rth ₅₅₀ (A) ≦ 140
(11) 0.80 ≦ | Re ₄₅₀ (A) / Re ₅₅₀ (A) | ≦ 1.00
Re ₅₅₀ (A) of the optically anisotropic layer A is more preferably 90 to 160 nm, and further preferably 110 to 140 nm. Furthermore, Rth ₅₅₀ (A) of the optically anisotropic layer A is more preferably 50 to 120 nm, and further preferably 60 nm to 100 nm. Further, | Re ₄₅₀ (A) / Re ₅₅₀ (A) | is more preferably 0.85 to 0.95.

  As long as the optically anisotropic layer A satisfies the optical characteristics, there are no particular restrictions on the material thereof, but those that satisfy the optical characteristics can be easily produced, so polycarbonate, cycloolefin polymer, norbornene A film of polymer, cellulose acylate or the like (a stretched film subjected to a stretching treatment if necessary) is preferable.

  The present invention will be described more specifically with reference to the following examples. The materials, reagents, ratios, operations, and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

[Example 1]
(Preparation of transparent support C1)
(Preparation of cellulose acetate solution)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acetate solution A.
Composition of cellulose acetate solution A ――――――――――――――――――――――――――――――――――――
Cellulose acetate with an acetyl substitution degree of 2.94 100.0 parts by mass Methylene chloride (first solvent) 402.0 parts by mass Methanol (second solvent) 60.0 parts by mass ――――――――――――― ――――――――――――――――――――――

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

(Preparation of additive solution)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.
Additive solution composition ――――――――――――――――――――――――――――――
The following optical anisotropy reducing agent 49.3 parts by mass The following wavelength dispersion adjusting agent 4.9 parts by mass Methylene chloride (first solvent) 58.4 parts by mass Methanol (second solvent) 8.7 parts by mass Cellulose acetate Solution A 12.8 parts by mass ――――――――――――――――――――――――――――――

Optical anisotropy reducing agent

Chromatic dispersion modifier

(Production of cellulose acetate film)
94.6 parts by mass of the cellulose acetate solution A, 1.3 parts by mass of the matting agent solution, and 4.1 parts by mass of the additive solution were mixed after filtration, and cast using a band casting machine. The mass ratio of the compound that reduces optical anisotropy and the wavelength dispersion adjusting agent to cellulose acetate in the above composition was 12% and 1.2%, respectively. The film was peeled from the band with a residual solvent amount of 30% and dried at 140 ° C. for 40 minutes to produce a long cellulose acetate film T0 having a thickness of 80 μm. The in-plane retardation (Re) of the obtained film was 1 nm (the slow axis was a direction perpendicular to the film longitudinal direction), and the thickness direction retardation (Rth) was −1 nm. This was used as a transparent support C1.

After passing the dielectric heating roll of 60 degreeC on the transparent support body C1 produced above and heating up the film surface temperature to 40 degreeC, the alkali solution (S-1) of the composition shown below is made into a rod. Under a steam far-infrared heater manufactured by Noritake Company Limited, Co., Ltd., coated at a coating rate of 17.3 mL / m ² and a coating speed of 60 m / min using a coater and heated to 110 ° C. (saponification temperature) It was allowed to stay for 2 seconds (saponification time). Subsequently, 2.8 mL / m ^{2 of} pure water was applied using the same rod coater. The film temperature at this time was 40 degreeC. Next, washing with a fountain coater and draining with an air knife were repeated four times, and then the saponification treatment was performed by staying in a drying zone at 70 ° C. for 5 seconds and drying.

{Alkaline solution (S-1) composition}
Potassium hydroxide 4.7 parts by weight Water 15.8 parts by weight Isopropanol 63.7 parts by weight Surfactant 1.0 part by weight SF-1: C ₁₆ H ₃₃ O (CH ₂ CH ₂ O) ₁₀ H
14.8 parts by mass of propylene glycol

An alignment film coating solution having the following composition was applied to the saponified surface of the saponified transparent support C1 and dried to form an alignment film.
(Orientation film coating solution composition)
The following modified polyvinyl alcohol 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Glutaraldehyde (crosslinking agent) 0.5 parts by weight

(Preparation of coating solution for optically anisotropic layer C2)
The following composition was dissolved in 102 kg of methyl ethyl ketone to prepare a coating solution.
The following discotic liquid crystalline compound (1) 41.01 parts by mass Ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 4.06 parts by mass The following polymer A-1 0.13 parts by mass Part below photopolymerization initiator (1) 0.90 part by mass

Discotic liquid crystalline compounds (1)

Polymer A-1

Photopolymerization initiator (1)

  The composition of the optically anisotropic layer C2 is dissolved in 102 parts by mass of methyl ethyl ketone to form a coating solution, which is continuously applied to the surface of the alignment film with a # 4.2 wire bar at a temperature of 130 ° C. The state was heated for 1 minute to align the discotic liquid crystalline compound. Next, UV irradiation was performed using a 120 W / cm high-pressure mercury lamp at 100 ° C. to polymerize the discotic liquid crystalline compound. Then, it stood to cool to room temperature. Re of the obtained optically anisotropic layer measured at a wavelength of 550 nm was 0.5 nm, and Rth was 180 nm, which satisfied the optical characteristics required for the optically anisotropic layer C2.

(Evaluation of adhesion of optical compensation sheet)
The adhesion of the optical compensation sheet was evaluated by preparing a test piece in accordance with the JIS K 5400 8.5.2 base tape method. However, polyester adhesive tape NO31RH manufactured by Nitto Denko was used for evaluation. The results are shown in the table.

<Preparation of polarizing plate of optical compensation sheet>
A roll-shaped polyvinyl alcohol film having a thickness of 80 μm continuously dyed in an aqueous iodine solution was stretched 5 times in the transport direction and dried to obtain a long polarizing film. The optical compensation sheet (K-1) saponified on one surface of the polarizing film, and a commercially available cellulose acetate film (Fujitac TD80UL, manufactured by Fuji Film Co., Ltd.) saponified on the other surface, were polyvinyl alcohol. A polarizing plate (P-1) was produced by continuously bonding using a system adhesive.

(Preparation of optically anisotropic layer A)
An optically anisotropic layer A having Re of 120 nm and Rth of 78 nm was obtained by thermally relaxing a polycarbonate film “Pure Ace WR” manufactured by Teijin Chemicals Ltd. in the vicinity of Tg.

<Preparation of polarizing plate with optically anisotropic layer A>
A roll-shaped polyvinyl alcohol film having a thickness of 80 μm continuously dyed in an aqueous iodine solution was stretched 5 times in the transport direction and dried to obtain a long polarizing film. The optically anisotropic layer A is bonded to one surface of the polarizing film using a polyvinyl alcohol-based adhesive so that the transmission axis of the polarizing film and the slow axis of the optically anisotropic layer A are parallel, A commercially available cellulose acetate film (Fujitac TD80UL, manufactured by Fuji Film Co., Ltd.) saponified on the other surface was continuously bonded using a polyvinyl alcohol adhesive to prepare a polarizing plate (P-A1).

<Mounting on VA panel>
A pair of polarizing plates and a pair of optical compensation sheets provided in a liquid crystal display device [manufactured by Sharp (LC-37GE2)] using a vertical alignment type liquid crystal cell were peeled off, and the liquid crystal cell was taken out.
Instead of the pair of polarizing plates and the pair of optical compensation sheets provided in the liquid crystal display device using the vertical alignment type liquid crystal cell, the optically anisotropic layer C2 includes the polarizing plate P-1 produced above. It stuck on the liquid crystal cell of the backlight side through the adhesive so that it might become the liquid crystal cell side. Furthermore, the produced polarizing plate P-A1 was attached to the liquid crystal cell on the side opposite to the polarizing plate P-1 through an adhesive so that the optically anisotropic layer A was on the liquid crystal cell side. At this time, it was bonded to the liquid crystal cell so that the transmission axes of the polarizing plate P-1 and the polarizing plate P-A1 cross each other. A rectangular wave voltage of 55 Hz was applied to the liquid crystal cell. A normally black mode with 5 V white display and 0 V black display was set. The black display transmittance (%) at the azimuth angle of 0 ° and the polar angle of 60 ° and the color shift Δx between the azimuth angle of 0 ° polar angle of 60 ° and the azimuth angle of 180 ° and polar angle of 60 ° were obtained. . The results are shown in the table.
Color change (Δx)
◎: Less than 0.02 ○: 0.02-0.04
Δ: 0.04 to 0.06
×: 0.06 or more

[Example 2]
An optical compensation sheet and a polarizing plate were produced in the same manner as in Example 1 except that the optically anisotropic layer C2 was produced with a # 3.6 wire bar, Re was 0.4 nm, and Rth was 160 nm. A liquid crystal display device was produced in the same manner as in Example 1 except that this polarizing plate was used instead of the polarizing plate P-1, and the color viewing angle was measured in the same manner. The results are shown in the table, and the color change depending on the viewing angle was small and good as in Example 1.

[Example 3]
An optical compensation sheet and a polarizing plate were produced in the same manner as in Example 1 except that the optically anisotropic layer C2 was produced with a # 4.8 wire bar, Re was 0.4 nm, and Rth was 200 nm. A liquid crystal display device was produced in the same manner as in Example 1 except that this polarizing plate was used instead of the polarizing plate P-1, and the color viewing angle was measured in the same manner. The results are shown in the table, and the color change depending on the viewing angle was small and good as in Example 1.

[Examples 4 to 6]
Transparent support of a cellulose acylate film in which the value of Re, Rth, Rth ₄₀₀ (C1) -Rth ₇₀₀ (C1) is changed by changing the amount of addition of the wavelength dispersion adjusting agent used when producing the transparent support C1 An optical compensation sheet and a polarizing plate were respectively produced in the same manner as in Examples 1 to 3 except that the body C1 was used. A liquid crystal display device was produced in the same manner as in Example 1 except that each of the obtained polarizing plates was used instead of the polarizing plate P-1, and the color viewing angle was measured in the same manner. The results are shown in the table, and the color change depending on the viewing angle was small and good as in Example 1.

[Examples 7 to 9]
As the transparent support C1, a cyclic polyolefin (COC) film produced by the following method was produced.
(Preparation of transparent support C1)
The following composition was placed in a pressure-resistant sealed tank and stirred, and then heated to 80 ° C. with warm water to dissolve each component. After cooling, the mixture was filtered through a filter paper having an average pore diameter of 34 μm and a sintered metal filter having an average pore diameter of 10 μm.

―――――――――――――――――――――――――――――――――
Cyclic polyolefin solution D-2
―――――――――――――――――――――――――――――――――
Topas 5013 (Distributor Polyplastics Co., Ltd.) 150 parts by mass Cyclohexane 350 parts by mass ――――――――――――――――――――――――――――――― -

  Next, the following composition containing the cyclic polyolefin solution D-2 produced by the above method was charged into a disperser to prepare a matting agent dispersion.

――――――――――――――――――――――――――――――――――
Matting agent dispersion M-2
――――――――――――――――――――――――――――――――――
Silica particles having a primary average particle size of 16 nm (aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) 2 parts by mass cyclohexane 75 parts by mass cyclic polyolefin solution D-2 10 parts by mass -------- ―――――――――――――――――――

  100 parts by mass of the cyclic polyolefin solution D-2 and 1.1 parts by mass of the matting agent dispersion M-2 were mixed to prepare a dope for film formation. The above dope was cast using a band casting machine. A film peeled off from the band with a residual solvent amount of about 25% by mass was stretched in the width direction at a stretch rate of 2% using a tenter, and hot air was applied while holding the film so as not to cause wrinkles. Dried. Then, the tenter transport was shifted to the roll transport, and further dried at 100 ° C. to 120 ° C. and wound up. The produced COC film satisfied the optical characteristics as the transparent support C1 as shown in the table.

  The COC film produced by the above method was subjected to corona treatment. The optical compensation sheet and the polarizing plate were respectively used in the same manner as in Examples 1 to 3, except that the corona-treated COC film was used as the transparent support C1 instead of the saponified cellulose acetate film. Produced. A liquid crystal display device was produced in the same manner as in Example 1 except that each of the obtained polarizing plates was used instead of the polarizing plate P-1, and the color viewing angle was measured in the same manner. The results are shown in the table, and the color change depending on the viewing angle was small and good as in Example 1.

[Examples 10 to 12]
As the transparent support C1, a cyclic polyolefin (COP) film produced by the following method was produced.
(Preparation of transparent support C1)
A cyclic olefin resin COP film was obtained in the same manner as in Examples 7 to 9 except that the composition of the dope for film formation was as follows.
Arton G (manufactured by JSR Corporation) 100 parts by mass Dichloromethane 390 parts by mass Compound A-7 (manufactured by Tokyo Chemical Industry Co., Ltd.) 10.0 parts by mass

  The COP film produced by the above method was subjected to corona treatment. The optical compensation sheet and the polarizing plate were respectively used in the same manner as in Examples 1 to 3 except that the corona-treated COP film was used as the transparent support C1 instead of the saponified cellulose acetate film. Produced. A liquid crystal display device was produced in the same manner as in Example 1 except that each of the obtained polarizing plates was used instead of the polarizing plate P-1, and the color viewing angle was measured in the same manner. The results are shown in the table, and the color change depending on the viewing angle was small and good as in Example 1.

[Examples 13 to 15]
As the transparent support C1, a biaxially stretched lactone ring-containing polymer resin (LCA) film produced by the following method was used.
(Manufacture of lactone ring-containing polymer resin)
Into a 30 L reaction kettle equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction tube, 8000 g of methyl methacrylate (MMA), 2000 g of methyl 2- (hydroxymethyl) methyl acrylate (MHMA), and 10,000 g of toluene were charged. When the temperature was raised to 105 ° C. while refluxing nitrogen and the mixture was refluxed, 10.0 g tertiary aluminum peroxyisononanoate (manufactured by Atofina Yoshitomi, trade name: Lupazole 570) was added as an initiator, and at the same time 20.0 g While a solution consisting of an initiator and 100 g of toluene was added dropwise over 4 hours, solution polymerization was performed under reflux (about 105 to 110 ° C.), followed by further aging for 4 hours.
To the obtained polymer solution, 10 g of stearyl phosphate / distearyl phosphate mixture (manufactured by Sakai Chemicals, trade name: Phoslex A-18) was added and cyclized under reflux (about 90 to 110 ° C.) for 5 hours. A condensation reaction was performed. Subsequently, the polymer solution obtained by the cyclization condensation reaction was subjected to a vent with a parel temperature of 260 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 4 It is introduced into a type screw twin screw extruder (Φ = 29.75 mm, L / D = 30) at a treatment rate of 2.0 kg / hour in terms of resin amount, and cyclization condensation reaction and devolatilization are carried out in the extruder. By extrusion, a transparent lactone ring-containing polymer resin pellet (1A) was obtained.
The lactone ring-containing polymer resin pellet (1A) had a lactone ring ratio of 97.0%, a weight average molecular weight of 147700, a melt flow rate of 11.0 g / 10 minutes, and a Tg (glass transition temperature) of 130 ° C.

(Preparation of base film)
1 part of TINUVIN 1577 (manufactured by Ciba Specialty Chemicals), 1 part of ADK STAB LA-31 (manufactured by Asahi Denka Kogyo Co., Ltd.) 10 parts and 0.12 part of zinc acetate as a foaming inhibitor were mixed and extruded from a T die at a die temperature of 250 ° C. with a single screw extruder to obtain a 120 μm unstretched film. This unstretched film was stretched 1.5 times at 145 ° C. in the machine direction and then 1.8 times at 145 ° C. in the transverse direction to obtain a biaxially stretched film having a thickness of 60 μm.

  The LCA film produced by the above method was subjected to corona treatment. The optical compensation sheet and the polarizing plate were respectively used in the same manner as in Examples 1 to 3 except that this corona-treated LCA film was used as the transparent support C1 instead of the saponified cellulose acetate film. Produced. A liquid crystal display device was produced in the same manner as in Example 1 except that each of the obtained polarizing plates was used instead of the polarizing plate P-1, and the color viewing angle was measured in the same manner. The results are shown in the table, and the color change depending on the viewing angle was small and good as in Example 1.

[Examples 16 to 18]
When the optically anisotropic layer C2 was formed, the surface of the alignment film was rubbed, and the optically anisotropic layer C2 was formed using a coating liquid having the following composition. An optical compensation sheet and a polarizing plate were produced in the same manner as in Example 1 except that the film thickness was adjusted so that Rth was a value shown in the table. A liquid crystal display device was produced in the same manner as in Example 1 except that each of the obtained polarizing plates was used instead of the polarizing plate P-1, and the color viewing angle was measured in the same manner. Although the results are shown in the table, the color change depending on the viewing angle slightly increased as compared with Example 1, but was in a sufficiently good range.
(Composition of coating liquid containing rod-like liquid crystal compound)
――――――――――――――――――――――――――――――――――――
91 parts by mass of the following rod-like liquid crystalline compound Photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 3 parts by mass Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 1 part by mass The above polymer A-1 0. 4 parts by mass Ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 9 parts by mass Polymerizable chiral agent (LC756 manufactured by BASF) 3 parts by mass Methyl ethyl ketone 172 parts by mass ――――――――――――――――――――――――――――――

Rod-shaped liquid crystal compound

[Examples 19 to 21]
The LCA film produced by the above method was subjected to corona treatment. The optical compensation sheet and the polarizing plate were respectively used in the same manner as in Examples 16 to 18 except that the corona-treated LCA film was used as the transparent support C1 instead of the saponified cellulose acetate film. Produced. A liquid crystal display device was produced in the same manner as in Example 1 except that each of the obtained polarizing plates was used instead of the polarizing plate P-1, and the color viewing angle was measured in the same manner. Although the results are shown in the table, the color change depending on the viewing angle slightly increased as compared with Example 1, but was in a sufficiently good range.

[Examples 22 to 24]
The discotic liquid crystal compound (1) used for forming the optically anisotropic layer C2 is replaced with the following discotic liquid crystal compound (2), and the film is formed so that Re and Rth of the optically anisotropic layer C2 have the values shown in the table. An optical compensation sheet and a polarizing plate were prepared in the same manner as in Example 1 except that the thicknesses were adjusted. A liquid crystal display device was produced in the same manner as in Example 1 except that each of the obtained polarizing plates was used instead of the polarizing plate P-1, and the color viewing angle was measured in the same manner. The results are shown in the table, and the color change depending on the viewing angle was small and good as in Example 1.

Discotic liquid crystalline compounds (2)

[Examples 25 to 27]
The polymer A-1 which is a horizontal alignment agent used for forming the optically anisotropic layer C2 is replaced with the following polymer A-2, and the Re and Rth of the optically anisotropic layer C2 are as shown in the table. An optical compensation sheet and a polarizing plate were prepared in the same manner as in Example 1 except that the film thickness was adjusted. A liquid crystal display device was produced in the same manner as in Example 1 except that each of the obtained polarizing plates was used instead of the polarizing plate P-1, and the color viewing angle was measured in the same manner. The results are shown in the table, and the color change depending on the viewing angle was small and good as in Example 1.

Polymer A-2

[Example 28]
As the transparent support C1, a polymer film produced by the method described below was used.
(Production of polymer 1)
The following composition is put into a four-necked flask (installed with an inlet, a thermometer, a reflux condenser, a nitrogen inlet, and a stirrer), gradually heated to 80 ° C., and polymerized for 5 hours while stirring. After completion, the polymer solution was poured into a large amount of methanol to precipitate, further washed with methanol, purified and dried to obtain polymer 1 having a weight average molecular weight of 3,000 (measured by GPC).
Methyl acrylate 10 parts by mass 2-hydroxyethyl acrylate 1 part by mass Azobisisobutyronitrile (AIBN) 1 part by mass Toluene 30 parts by mass

(Preparation of transparent support C1)
The following dope composition was put into a pressure sealed container and heated to 70 ° C. to bring the pressure in the container to 1 atm or more, and the cellulose ester was completely dissolved while stirring. The dope temperature was lowered to 35 ° C. and allowed to stand overnight, and this dope was added to Azumi Filter Paper No. After filtration using 244, the mixture was further allowed to stand overnight for defoaming. Next, a filtration pressure of 1.0 using Finemet NM (absolute filtration accuracy 100 μm) and Finepore NF (absolute filtration accuracy 50 μm, 15 μm, 5 μm in order of absolute filtration accuracy) manufactured by Nippon Seisen Co., Ltd. It filtered by * 10 < ⁶ > Pa and used for film forming. The film thickness was 40 μm.
<Dope composition>
Cellulose triacetate (degree of substitution 2.83) 100 parts by mass Polymer 1 15 parts by mass The following UV agent (1) 0.8 parts by mass The following UV agent (2) 0.2 parts by mass Methylene chloride 475 parts by mass Ethanol 50 parts by mass Part

UV agent (1)

UV agent (2)

  The optical properties of the obtained polymer film satisfied the requirements as the transparent support C1 as shown in the table. An optically anisotropic sheet C2 was formed in the same manner as in Example 16 except that this polymer film was used as the transparent support C1, and an optical compensation sheet and a polarizing plate were produced. Further, using this polarizing plate, a liquid crystal display device was produced in the same manner, and the color viewing angle was measured in the same manner. The results are shown in the table. The color change depending on the viewing angle increased to some extent as compared with Example 1, but was sufficiently good.

[Example 29]
As the transparent support C1, a cellulose acylate film produced by the method described below was used.
(Preparation of transparent support C1)
The following dope composition was put into a pressure sealed container and heated to 70 ° C. to bring the pressure in the container to 1 atm or more, and the cellulose ester was completely dissolved while stirring. The dope temperature was lowered to 35 ° C. and allowed to stand overnight, and this dope was added to Azumi Filter Paper No. After filtration using 244, the mixture was further allowed to stand overnight for defoaming. Next, a filtration pressure of 1.0 using Finemet NM (absolute filtration accuracy 100 μm) and Finepore NF (absolute filtration accuracy 50 μm, 15 μm, 5 μm in order of absolute filtration accuracy) manufactured by Nippon Seisen Co., Ltd. It filtered by * 10 < ⁶ > Pa and used for film forming. The film thickness was 40 μm.
<Dope composition>
Cellulose triacetate (degree of substitution 2.83) 100 parts by mass Triphenyl phosphate 15 parts by mass UV agent (1) 0.8 parts by mass UV agent (2) 0.2 parts by mass Methylene chloride 475 parts by mass Ethanol 50 parts by mass

  The optical properties of the obtained cellulose acylate film satisfied the requirements as the transparent support C1 as shown in the table. An optically anisotropic layer C2 was formed in the same manner as in Example 16 except that this cellulose acylate film was used as the transparent support C1, and an optical compensation sheet and a polarizing plate were produced. Further, using this polarizing plate, a liquid crystal display device was produced in the same manner, and the color viewing angle was measured in the same manner. The results are shown in the table. The color change depending on the viewing angle increased to some extent as compared with Example 1, but was sufficiently good.

[Example 30]
In the production of the polymer film in Example 28, except that the transparent support C1 having a thickness of 80 μm and the Re and Rth adjusted to the values shown in the table was used, in the same manner as in Example 28, An optical compensation sheet and a polarizing plate were prepared. A liquid crystal display device was similarly produced using this polarizing plate, and the color viewing angle was similarly measured. The results are shown in the table. The color change depending on the viewing angle increased to some extent as compared with Example 1, but was sufficiently good.

[Example 31]
An optically anisotropic sheet C2 was formed in the same manner as in Example 1 except that the polymer film prepared in Example 30 was used as the transparent support C1, and an optical compensation sheet and a polarizing plate were prepared. A liquid crystal display device was produced in the same manner using this polarizing plate, and the color viewing angle was measured in the same manner. The results are shown in the table, and the color change depending on the viewing angle was small and good as in Example 1.

[Examples 32-34]
As the optically anisotropic layer C2, a polyimide layer formed by the following method and formed by adjusting the film thickness so that Re, Rth, and Rth450 / Rth550 have values shown in the table was used.
(Polyimide layer production)
Weight average molecular weight (Mw) 120 synthesized from 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane and 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl 1,000 polyimides were dissolved in cyclohexanone to prepare a 15 wt% polyimide solution. Then, the polyimide solution was applied to the transparent support C1 described in Example 1. As a result of drying this coating film at 100 ° C. for 10 minutes, it was an optical compensation sheet having a film thickness of 5 μm to 6 μm, and an optical compensation sheet having optical characteristics shown in the table was obtained. A polarizing plate was produced in the same manner as in Example 1 using each of these optical compensation sheets. Further, a liquid crystal display device was produced in the same manner, and the color viewing angle was measured. The results are shown in the table, and the color change depending on the viewing angle was small and good as in Example 1.

[Examples 35 to 37]
An optically anisotropic sheet C2 was formed in the same manner as in Examples 32-34 except that the polymer film prepared in Example 13 was used as the transparent support C1, and an optical compensation sheet and a polarizing plate were prepared. . A liquid crystal display device was produced in the same manner using this polarizing plate, and the color viewing angle was measured in the same manner. The results are shown in the table, and the color change depending on the viewing angle was small and good as in Example 1.

[Comparative Example 1]
In Example 1, an optically anisotropic layer was formed in the same manner as in Example 1 using a composition obtained by removing the polymer A-1 from the composition used for forming the optically anisotropic layer C2. The discotic liquid crystal compound was unoriented, and the optically anisotropic layer C2 having desired optical characteristics could not be formed.
[Comparative Example 2]
Instead of the transparent support C1 of Example 1, a polymer film having Re, Rth, and Rth400-Rth700 values shown in the table was used as the transparent support. Otherwise, a liquid crystal display device was produced in the same manner as in Example 1. Similarly, as a result of measuring the color viewing angle, it was found that the color change was worsened.
[Comparative Example 3]
Instead of the transparent support C1 of Example 1, a polymer film having Re as shown in the table was used, and the film thickness was adjusted so that Rth of the optically anisotropic layer C2 was as shown in the table. A liquid crystal display device was produced in the same manner as in Example 1. Similarly, as a result of measuring the color viewing angle, it was found that the color change was worsened.
[Comparative Example 4]
A liquid crystal display device was produced in the same manner as in Example 1 except that instead of the transparent support C1 of Example 1, a polymer film having Rth400 to Rth700 values shown in the table was used. Similarly, as a result of measuring the color viewing angle, it was found that the color change slightly worsened.

  In addition, a polyfunctional monomer (ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.)) was removed from the composition used for forming the optically anisotropic layer C2 of Example 1. An optical compensation sheet was produced in the same manner as in Example 1 except that the optically anisotropic layer was formed. The adhesion evaluation between the transparent support C1 and the optically anisotropic layer C2 of this optical compensation sheet was found to be 6 points.

Claims (15)

An optical compensation sheet, which is a C plate, having a transparent support C1 and an optically anisotropic layer C2 and satisfying the following formulas (1) to (4):
(1) 0 ≦ Re ₆₃₀ (C1) ≦ 10
(2) 0 ≦ Re ₅₅₀ (C2) ≦ 10
(3) 100 ≦ Rth ₅₅₀ (C2) −Rth ₅₅₀ (C1)
(4) | Rth ₄₅₀ (C2) / Rth ₅₅₀ (C2) −Rth ₄₅₀ (C) / Rth ₅₅₀ (C) | ≦ 0.1
[In the formula, Reλ (C1) is the front retardation value (unit: nm) of the transparent support C1 at the wavelength λnm, and Rthλ (C1) is the retardation value of the transparent support C1 in the film thickness direction at the wavelength λnm (unit: nm). Reλ (C2) is the front retardation value (unit: nm) at the wavelength λnm of the optically anisotropic layer C2, and Rthλ (C2) is the letter in the film thickness direction of the optically anisotropic layer C2 at the wavelength λnm. Rthλ (C) is the retardation value (unit: nm) in the film thickness direction of the optical compensation sheet (laminated body of C1 and C2) at the wavelength λnm. The optical compensation sheet according to claim 1, wherein the transparent support C1 and the optically anisotropic layer C2 satisfy the following formulas (5) to (8):
(5) −25 ≦ Rth ₆₃₀ (C1) ≦ 25
(6) 100 ≦ Rth ₅₅₀ (C2) ≦ 300
(7) −35 ≦ Rth ₄₀₀ (C1) −Rth ₇₀₀ (C1) ≦ 50
(8) 1.04 ≦ Rth ₄₅₀ (C2) / Rth ₅₅₀ (C2) ≦ 1.30. The optical compensation sheet according to claim 1 or 2, wherein the transparent support C1 and / or the optically anisotropic layer C2 is a negative C plate. The transparent support C1 is made of a film of cellulose acylate, a film of norbornene-based polymer, a film of cycloolefin polymer, a lactone ring-containing polymer resin film, or a film of polycarbonate. 2. The optical compensation sheet according to item 1. The optically anisotropic layer C2 is a layer formed by fixing a polymerizable liquid crystal composition containing at least one polymerizable liquid crystal compound in a liquid crystal phase. The optical compensation sheet as described. 6. The optical compensation sheet according to claim 5, wherein the optically anisotropic layer C2 is a layer formed by fixing a polymerizable liquid crystal composition containing a rod-like liquid crystal compound in a cholesteric phase. The optically anisotropic layer C2 is a layer formed by fixing a polymerizable liquid crystal composition containing a discotic liquid crystal compound with homeotropic alignment of molecules of the discotic liquid crystal compound and fixing it in a nematic liquid crystal phase. The optical compensation sheet according to claim 5. The optical compensation sheet according to any one of claims 5 to 7, wherein the optically anisotropic layer C2 further contains a compound having a fluorine polymer containing the following general formula:
General formula (1)

In the general formula (1), R ¹ , R ² and R ³ each independently represent a hydrogen atom or a substituent. Q is a carboxyl group containing at least one phenyl group (—COOH) or a salt thereof, a sulfo group (—SO ₃ H) or a salt thereof, a phosphonoxy group {—OP (═O) (OH) ₂ } or a salt thereof, It has a hydrophilic group (—OH) or acrylamide (—NR ⁴ — (R ⁴ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group)). L represents an arbitrary group selected from the following linking group group, or a divalent linking group formed by combining two or more thereof;
(Linked group group)
Single bond, —O—, —CO—, —S—, —SO ₂ —, —P (═O) (OR ⁵ ) — (R ⁵ represents an alkyl group, an aryl group, or an aralkyl group), an alkylene group And an arylene group. The optical according to any one of claims 5 to 8, wherein the optically anisotropic layer C2 is a layer formed from the polymerizable liquid crystal composition further containing a polyfunctional monomer having two or more functional groups. Compensation sheet. The optical compensation sheet according to any one of claims 1 to 3, wherein the optically anisotropic layer C2 is a polymer film layer. A polarizing plate comprising the optical compensation sheet according to claim 1 and a polarizing film. A liquid crystal display device comprising the optical compensation sheet according to claim 1 and / or the polarizing plate according to claim 11. Two polarizing films arranged with their absorption axes orthogonal to each other, and a pair of substrates between the two polarizing films, and liquid crystal molecules sandwiched between the pair of substrates are external to the substrate A liquid crystal display device having a liquid crystal cell having a liquid crystal layer aligned substantially vertically in a non-driven state where no electric field is applied,
A liquid crystal display device comprising the optical compensation sheet according to claim 1 between any one of the two polarizing films and the liquid crystal cell. Furthermore, the liquid crystal display device of Claim 12 or 13 which has the optically anisotropic layer A which satisfy | fills following formula (9)-(11):
(9) 70 ≦ Re ₅₅₀ (A) ≦ 180
(10) 30 ≦ Rth ₅₅₀ (A) ≦ 140
(11) 0.80 ≦ | Re ₄₅₀ (A) / Re ₅₅₀ (A) | ≦ 1.00
[In the formula, Reλ (A) is the front retardation value (unit: nm) of the optically anisotropic layer A at the wavelength λnm, and Rthλ (A) is the retardation in the film thickness direction of the optically anisotropic layer A at the wavelength λnm. Value (unit: nm)]. The optically anisotropic layer A is disposed between one of the two polarizing films and the liquid crystal cell, and an in-plane slow axis of the optically anisotropic layer A and an absorption axis of the polarizing film. The liquid crystal display device according to claim 14, wherein and are orthogonal to each other.