JP2009053684A - Retardation film, polarizing plate, and liquid crystal display device comprising it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide novel retardation films and polarizing plates, contributing towards reduction in the color shift occurring in oblique directions and to provide VA-mode liquid crystal display devices in which the color shift depending on the viewing direction in the black state is reduced. <P>SOLUTION: The retardation film has a polymer film, and an optically anisotropic layer which is disposed on the polymer film and has ≤5 μm thickness, and is characterized in that the in-plane retardation Re(550) at 550 nm wavelength is 0-10 nm, the thickness-direction retardation Rth(550) at the same wavelength is 200-400 nm, and 1.04≤Rth(450)/Rth(550)≤1.09 is satisfied. The polarizing plate and the liquid crystal display device each have the retardation film. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a novel retardation film, a polarizing plate and a liquid crystal display device using the same.

Conventionally, wide viewing angle liquid crystal systems such as an IPS (In-Plane Switching) system, an OCB (Optically Compensatory Bend) system, and a VA (Vertically Aligned) system have been proposed. It is expanding. In each method, the display quality is improved, but the problem of color misregistration that occurs when observed obliquely has not yet been solved.
To solve such a problem, for example, by using two types of retardation films having different optical characteristics, a method for providing a clear and achromatic VA mode liquid crystal display device even when observed from an oblique direction during black display. Is disclosed (for example, see Patent Document 1).
However, when the two types of retardation films are actually incorporated into a liquid crystal display device, they are often integrated with a polarizing plate and incorporated into a liquid crystal display device. A step of bonding two retardation films exhibiting optical characteristics is necessary. For this reason, there are problems that the manufacturing process becomes complicated, the productivity is low, and the manufacturing cost is high, and the improvement has been demanded.

  On the other hand, for example, Patent Document 2 discloses an optical compensation sheet having a transparent support and an optically anisotropic layer formed of discotic liquid crystalline molecules as an optical compensation sheet for a VA mode liquid crystal display device. Proposed. By using a cellulose acylate film as the transparent support, the cellulose acylate film can be used as a protective film for a polarizing plate, and the above-mentioned productivity problems can be solved. However, in order to obtain the optical characteristics necessary for optical compensation of the VA mode liquid crystal display device, the retardation (Rth) in the thickness direction needs to be about 300 nm. It is necessary to increase the thickness of the isotropic layer. When the optically anisotropic layer is formed by coating, a problem of coating unevenness may occur.

By the way, the retardation of a retardation film made of a polymer film or the like does not become a uniform value for any wavelength, but changes to some extent depending on the wavelength of incident light (hereinafter, this property is changed). "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 the wavelength dispersion of retardation of the retardation plate to be similar to that. May occur.
For example, it has been proposed to use a negative C plate for optical compensation at the time of black display of a VA mode liquid crystal cell, but the wavelength dispersion of retardation (Rth) in the thickness direction of the negative C plate is VA. If the wavelength dispersion of the liquid crystal cell in the mode is not similar, a color change depending on the viewing angle (sometimes referred to as “color shift”) occurs.
However, the polymer film conventionally used as a retardation plate of a VA mode liquid crystal cell is difficult to control the wavelength dispersion of retardation, and exhibits an ideal wavelength dispersion similar to the birefringence of a liquid crystal cell. It is difficult to produce a retardation plate. 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.
As described above, the optical compensation of the VA mode liquid crystal display device requires that the thickness direction retardation (Rth) be about 300 nm, and in order to realize this, the optical anisotropic layer has a thickness of 200 nm or more. Directional retardation (Rth) is required. In such a system, the wavelength dispersion of the optically anisotropic layer is dominant, and when the anisotropic layer is formed of a discotic liquid crystal compound, the wavelength dispersion is high and it is difficult to obtain the desired wavelength dispersion as a whole. Met. Under such circumstances, it is required to provide an optical compensation film having an excellent optical compensation ability for various modes, particularly VA mode liquid crystal cells.

  Patent Document 3 discloses a discotic liquid crystal compound having low wavelength dispersion and large refractive index anisotropy. However, wavelength dispersion Rth (450) / Rth (550) is 1.1 or more. As it is, a retardation film exhibiting the wavelength dispersion necessary for optical compensation of a VA mode liquid crystal display device cannot be obtained.

In summary, a retardation film that can be used as a polarizing plate protective film for optical compensation of a VA mode liquid crystal display device, has the same wavelength dispersion as a VA mode liquid crystal cell, and has no unevenness. It is required to provide.
International Publication No. 2003/032060 Pamphlet JP 2000-304931 A JP 2006-076992 A

The present invention provides a novel retardation film and polarizing plate useful for optical compensation of a liquid crystal display device, particularly a VA mode liquid crystal display device, and particularly capable of contributing to reduction of color misregistration occurring in an oblique direction. Is an issue.
Another object of the present invention is to provide a liquid crystal display device, particularly a VA mode liquid crystal display device, which has improved contrast and improved color shift depending on the viewing angle direction during black display.

Means for solving the above-mentioned problems are as follows.
[1] A retardation film having a polymer film and an optically anisotropic layer having a thickness of 5 μm or less thereon, wherein an in-plane retardation Re (550) at a wavelength of 550 nm is 0 to 10 nm, and a wavelength of 550 nm A retardation film characterized in that the retardation Rth (550) in the thickness direction is from 200 to 400 nm and satisfies the following formula (1).
(1) 1.04 ≦ Rth (450) / Rth (550) ≦ 1.09
[2] The in-plane retardation Re (550) of the optically anisotropic layer having a wavelength of 550 nm is 0 to 10 nm, the retardation Rth (550) in the thickness direction of the same wavelength is 200 to 400 nm, and The retardation film of [1], which satisfies the formula (2).
(2) 1.05 ≦ Rth (450) / Rth (550) ≦ 1.15
[3] Thickness direction retardation Rth (550) of wavelength 550 nm of optical anisotropic layer divided by film thickness d of optical anisotropic layer, Rth (550) / d is 0.080 or more The retardation film of [1] or [2], wherein
[4] The retardation film according to any one of [1] to [3], wherein the optically anisotropic layer is formed from a polymerizable composition.
[5] The polymerizable composition is a composition containing a discotic liquid crystalline compound having a polymerizable group, and in the optically anisotropic layer, the discotic structural unit of the discotic liquid crystalline compound is relative to the layer surface. The retardation film according to any one of [1] to [4], which is horizontally oriented.

［式中、Ｙ¹¹、Ｙ¹²、及びＹ¹³は、それぞれ独立にメチン又は窒素原子を表し；
Ｌ¹、Ｌ²、及びＬ³は、それぞれ独立に単結合、又は二価の連結基を表し；
Ｈ¹、Ｈ²、及びＨ³は、それぞれ独立に、下記一般式（ＤＩ−Ａ）、又は下記一般式（ＤＩ−Ｂ）を表し；

［一般式（ＤＩ−Ａ）中、ＹＡ¹及びＹＡ²は、それぞれ独立にメチン又は窒素原子を表し；「＊」は上記一般式（ＤＩ）におけるＬ¹〜Ｌ³側と結合する位置を表し；
「＊＊」は上記一般式（ＤＩ）におけるＲ¹〜Ｒ³側と結合する位置を表す。］

［一般式（ＤＩ−Ｂ）中、ＹＢ¹及びＹＢ²は、それぞれ独立にメチン又は窒素原子を表し；「＊」は、上記一般式（ＤＩ）におけるＬ¹〜Ｌ³側と結合する位置を表し；
「＊＊」は、上記一般式（ＤＩ）におけるＲ¹〜Ｒ³側と結合する位置を表す。］
Ｒ¹、Ｒ²、及びＲ³は、それぞれ独立に下記一般式（ＤＩ−Ｒ）を表す。

［上記一般式（ＤＩ−Ｒ）中、「＊」は、一般式（ＤＩ）におけるＨ¹〜Ｈ³側と結合する位置を表し；
Ｌ²¹は、単結合、又は二価の連結基を表し；
Ｑ²は少なくとも１種類の環状構造を有する二価の基（環状基）を表し；
ｎ１は、０〜４の整数を表し；
Ｌ²²は、＊＊−Ｏ−、＊＊−Ｏ−ＣＯ−、＊＊−ＣＯ−Ｏ−、＊＊−Ｏ−ＣＯ−Ｏ−、＊＊−Ｓ−、＊−Ｎ（Ｒ）−、＊＊−ＣＨ₂−、＊＊−ＣＨ＝ＣＨ−、又は＊＊−Ｃ≡Ｃ−を表し、「＊＊」は、Ｑ²側と結合する位置を表し；
Ｌ²³は、−Ｏ−、−Ｓ−、−Ｃ（＝Ｏ）−、−ＮＨ−、−ＣＨ₂−、−ＣＨ＝ＣＨ−及びＣ≡Ｃ−、並びに、これらの組み合わせからなる群より選ばれる二価の連結基を表し；
Ｑ¹は、重合性基又は水素原子を表す。] [6] The retardation film of [5], wherein the discotic liquid crystalline compound is a compound represented by the following formula (DI).

[Wherein Y ¹¹ , Y ¹² and Y ¹³ each independently represent a methine group or a nitrogen atom;
L ¹ , L ² , and L ³ each independently represent a single bond or a divalent linking group;
H ¹ , H ² , and H ³ each independently represent the following general formula (DI-A) or the following general formula (DI-B);

[In General Formula (DI-A), YA ¹ and YA ² each independently represent methine or a nitrogen atom; “*” represents a position bonded to the L ^{1 to} L ³ side in General Formula (DI). ;
“**” represents a position bonded to the R ^{1 to} R ³ side in the general formula (DI). ]

[In General Formula (DI-B), YB ¹ and YB ² each independently represent a methine or nitrogen atom; “*” represents a position bonded to the L ^{1 to} L ³ side in General Formula (DI). Representation;
“**” represents a position bonded to the R ^{1 to} R ³ side in the general formula (DI). ]
R ¹ , R ² , and R ³ each independently represent the following general formula (DI-R).

[In the general formula (DI-R), “*” represents a position bonded to the H ^{1 to} H ³ side in the general formula (DI);
L ²¹ represents a single bond or a divalent linking group;
Q ² represents a divalent group (cyclic group) having at least one kind of cyclic structure;
n1 represents an integer of 0 to 4;
L ²² is **-O-, **-O-CO-, **-CO-O-, **-O-CO-O-, **-S-, **-N (R)-, ** — CH ₂ —, ** — CH═CH—, or ** — C≡C—, and “**” represents the position to be bonded to the Q ² side;
L ²³ is selected from the group consisting of —O—, —S—, —C (═O) —, —NH—, —CH ₂ —, —CH═CH— and C≡C—, and combinations thereof. Represents a divalent linking group;
Q ¹ represents a polymerizable group or a hydrogen atom. ]

[7] The retardation film according to any one of [1] to [6], wherein the optically anisotropic layer contains a fluoroaliphatic group-containing polymer.
[8] The retardation film according to any one of [1] to [7], wherein the retardation Rth (550) in the thickness direction at a wavelength of 550 nm of the polymer film is 30 nm or more.
[9] The retardation film according to any one of [1] to [8], wherein the polymer film is a cellulose acylate film.
[10] A polarizing plate comprising at least a polarizing film and the retardation film of any one of [1] to [9].
[11] A liquid crystal display device comprising the retardation film of any one of [1] to [10].
[12] A liquid crystal layer comprising a pair of polarizing films whose absorption axes are orthogonal to each other, a pair of substrates disposed between the polarizing films, and a liquid crystal molecule sandwiched between the substrates, and the liquid crystal [11] The liquid crystal display device according to [11], wherein the sex molecules are aligned in a direction substantially perpendicular to the substrate in a non-driven state where no external electric field is applied.
[13] The liquid crystal display device according to [11] or [12], further comprising a second retardation film, wherein the second retardation film comprises a polymer stretched film.
[14] The in-plane retardation Re (550) of the second retardation film having a wavelength of 550 nm and the Nz value (Nz = Rth (550) / Re (550) +0.5) of the same wavelength are represented by the following formula (3): And [13] the liquid crystal display device satisfying the following formula (4).
(3) 200 nm ≦ Re (550) ≦ 300 nm
(4) 0.3 <Nz <0.7
[15] The in-plane retardation Re (550) of wavelength 550 of the second retardation film and the Nz value (Nz = Rth (550) / Re (550) +0.5) of the same wavelength are expressed by the following formula (5). And [13] the liquid crystal display device satisfying the following formula (6).
(5) 240 nm ≦ Re (550) ≦ 290 nm
(6) 0.4 ≦ Nz ≦ 0.6
[16] The liquid crystal display device according to any one of [13] to [15], wherein the second retardation film satisfies the following formula (7).
(7) 0.7 ≦ Re (450) / Re (550) ≦ 1.1
[17] In the above [13] to [16], the second retardation film is any one of a cellulose acylate film, a norbornene film, a polycarbonate film, a polyester film, and a polysulfone film. Any liquid crystal display device.
[18] The second retardation film is directly laminated on one of the pair of polarizing films with an in-plane slow axis perpendicular to the absorption axis of the polarizing film. [15] to [17] Any one of the liquid crystal display devices.

According to the present invention, there are provided a novel retardation film and polarizing plate useful for optical compensation of a liquid crystal display device, particularly a VA mode liquid crystal display device, and particularly capable of contributing to reduction of color shift occurring in an oblique direction. can do.
In addition, according to the present invention, it is possible to provide a liquid crystal display device, particularly a VA mode liquid crystal display device, which has improved contrast and improved color shift depending on the viewing angle direction during black display.

  Hereinafter, the present invention will be described in detail. 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, numerical values and numerical ranges indicating optical characteristics and the like are to be interpreted as numerical values or numerical ranges including generally allowable errors for liquid crystal display devices and members used therefor. . Regarding the angle, in this specification, “45 °”, “parallel” or “orthogonal” means that the angle is within a range of strictly less than ± 5 °. The error from the exact angle is preferably less than 4 °, more preferably less than 3 °. Regarding the angle, “+” means the clockwise direction, and “−” means the counterclockwise direction. Further, the “slow axis” means a direction in which the refractive index is maximized. The “visible light region” means 380 to 780 nm. Further, the measurement wavelength of the refractive index is a value at λ = 550 nm in the visible light region unless otherwise specified.

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

In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).
In selecting the measurement wavelength λnm, the wavelength selection filter can be exchanged manually, or the measurement value can be converted by a program or the like.
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) is Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis) (if there is no slow axis, any in-plane film The light of wavelength λ nm is incident from each of the inclined directions in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction (with the direction of the rotation axis as the rotation axis). KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value.

In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative.
The retardation value is measured from two inclined directions with the slow axis as the tilt axis (rotation axis) (if there is no slow axis, the arbitrary direction in the film plane is the rotation axis). Based on the value, the assumed value of the average refractive index, and the input film thickness value, Rth can also be calculated from the following formulas (I) and (II).

数式（ＩＩ）
Ｒｔｈ＝｛（ｎｘ＋ｎｙ）／２−ｎｚ｝×ｄ
式中、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あらわす。
また、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は膜厚を表す。

Formula (II)
Rth = {(nx + ny) / 2−nz} × d
In the formula, Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction.
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, and d Represents the film thickness.

When the film to be measured is a film that cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optical axis, Rth (λ) is calculated by the following method.
Rth (λ) is the above-mentioned Re (λ), and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotary axis), and −50 degrees to +50 degrees with respect to the film normal direction. Measured at 11 points by making light of wavelength λ nm incident from each tilted direction in 10 degree steps, and based on the measured retardation value, assumed value of average refractive index, and input film thickness value KOBRA 21ADH or WR is calculated.
In the above measurement, as the assumed value of the average refractive index, the values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical compensation films can be used.
Moreover, about the thing whose average refractive index value is not known, it can measure with an Abbe refractometer. Examples of the average refractive index values of main optical compensation films are as follows:
Cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).
The KOBRA 21ADH or WR calculates nx, ny, and nz by inputting the assumed average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

[Phase difference film]
The retardation film of the present invention is a retardation film having at least one optically anisotropic layer on a polymer film. The in-plane retardation Re of the retardation film of the present invention is 0 to 10 nm, preferably 0 to 5 nm, and particularly preferably 0 to 3 nm. The retardation Rth in the thickness direction is 200 to 400 nm, more preferably 230 to 370 nm, and particularly preferably 250 to 350 nm. In the aspect of the retardation film for a liquid crystal display device in the VA mode, the wavelength dispersion Rth (450) / Rth (550) of the retardation film is preferably 1.04 to 1.09, and 1.05 to 1. It is more preferable that it is 08, and it is still more preferable that it is 1.06-1.08. Here, Rth (450) represents an Rth value for light having a wavelength of 450 nm, and Rth (550) represents an Rth value for light having a wavelength of 550 nm. When the above wavelength dispersion condition is satisfied, the VA mode liquid crystal display element can be compensated over the entire visible light range.

  Hereinafter, the polymer film and the optically anisotropic layer, which are elements of the retardation film of the present invention, will be described in detail.

[Polymer film]
The polymer film of the retardation film of the present invention preferably satisfies the following formulas (11) to (13).
30 nm ≦ Rth (550) ≦ 250 nm Formula (11)
Rth (450) / Rth (550) ≦ 1.08 (12)
0 ≦ Re (550) ≦ 10 nm Formula (13)
In Formula (11), Rth (550) is preferably 30 nm or more, more preferably 60 nm or more, and particularly preferably 80 nm or more. If the retardation in the thickness direction of the polymer film is large, the film thickness of the optically anisotropic layer can be reduced, and the problem of coating unevenness hardly occurs. Although there is no restriction | limiting in particular about the upper limit of Rth (550), Generally, the upper limit of Rth of a polymer film is about 250 nm.

  In the formula (12), [Rth (450) / Rth (550)] is preferably 1.05 or less, more preferably 1.03 or less, and particularly preferably 1.00 or less. [Rth (450) / Rth (550)] is preferably 0.70 or more.

  In the formula (13), Re (590) is preferably 0 to 5 nm.

  The thickness of the base material of the polymer film can be appropriately determined depending on the retardation or the like, but is preferably 10 to 150 μm, more preferably 20 to 130 μm, and more preferably 30 to 100 μm from the viewpoint of thinning and handling properties of the polarizing plate. Particularly preferred.

  The material of the polymer film is not particularly limited, and polymer films made of various materials that satisfy the optical characteristics can be used. Among these, a cellulose acylate film is preferable from the viewpoint of inexpensive raw materials and suitability for polarizing plate processing. In the present specification, the “cellulose acylate film” is a main component of the polymer composition constituting the film, specifically, cellulose acylate is, for example, 70% with respect to the total mass of the film. It shows that it is contained by mass% or more, preferably 80 mass% or more. In the present specification, the terms “mainly” and “main component” mean the same meaning.

  Cellulose acylate is one in which part or all of the hydroxyl groups of cellulose are substituted with acyl groups. The degree of substitution of cellulose acylate means the ratio of acylation of three hydroxyl groups present in the structural unit of cellulose (glucose having a (β) 1,4-glycoside bond). The degree of substitution (acylation degree) can be calculated by measuring the amount of bound fatty acid per unit mass of cellulose. The measuring method is carried out according to “ASTM D817-91”.

  The cellulose acylate used as a raw material for the polymer film is preferably a cellulose acylate having an acyl substitution degree of 2.90 to 3.00. The acyl substitution degree is more preferably 2.93 to 2.97.

  Another preferred cellulose acylate used as a raw material for the polymer film is a mixed fatty acid ester having a total acyl substitution degree of 2.70 to 3.00. More preferred is a mixed fatty acid ester having an acyl group with a total acyl substitution degree of 2.80 to 3.00 and having 3 to 4 carbon atoms. The acyl substitution degree of the mixed fatty acid ester is more preferably 2.85 to 2.97. The degree of substitution of the acyl group having 3 to 4 carbon atoms is preferably 0.1 to 2.0, and more preferably 0.3 to 1.5.

  The cellulose acylate used in the present invention preferably has a mass average polymerization degree of 350 to 800, more preferably 370 to 600. The cellulose acylate used in the present invention preferably has a number average molecular weight of 70,000 to 230,000, more preferably 75,000 to 230,000, and more preferably 78,000 to 27,000. Most preferably, it has a number average molecular weight of 120,000.

  The cellulose acylate used in the present invention can be synthesized using an acid anhydride or acid chloride as an acylating agent. When the acylating agent is an acid anhydride, an organic acid (for example, acetic acid) or methylene chloride is used as a reaction solvent. Further, a protic catalyst such as sulfuric acid can be used as the catalyst. When the acylating agent is an acid chloride, a basic compound can be used as a catalyst. In the most general synthetic method in industry, cellulose is an organic acid corresponding to acetyl group and other acyl groups (acetic acid, propionic acid, butyric acid) or acid anhydrides thereof (acetic anhydride, propionic anhydride, butyric anhydride). A cellulose ester is synthesized by esterification with a mixed organic acid component containing.

  In this method, cellulose such as cotton linter or wood pulp is activated with an organic acid such as acetic acid and then esterified using a mixture of organic acid components as described above in the presence of a sulfuric acid catalyst. In many cases. The organic acid anhydride component is generally used in an excess amount relative to the amount of hydroxyl groups present in the cellulose. In this esterification treatment, a hydrolysis reaction (depolymerization reaction) of the cellulose main chain ((β) 1,4-glycoside bond) proceeds in addition to the esterification reaction. When the hydrolysis reaction of the main chain proceeds, the degree of polymerization of the cellulose ester is lowered, and the physical properties of the cellulose ester film to be produced are lowered. Therefore, the reaction conditions such as the reaction temperature are preferably determined in consideration of the degree of polymerization and molecular weight of the resulting cellulose ester.

  A commercially available cellulose acylate film (for example, TD80UF manufactured by FUJIFILM Corporation) itself or by heating and stretching it can produce a cellulose acylate film satisfying the above formulas (11) to (13). In addition, a dope prepared by adding a retardation increasing agent such as 1,3,5-triazine ring compound to a solution of cellulose acylate having an acetylation degree of about 55.0 to 62.5% is put on a drum or the like. The cellulose acylate film which is cast and satisfies the above formulas (11) to (13) can also be produced. Various conditions of the solution casting method that can be used in the method described later, the retardation increasing agent, and the cellulose acylate raw material are described in detail in JP-A No. 2001-166144, and used for the production of the polymer film. be able to.

[Optically anisotropic layer]
Rth (450) / Rth (550) indicating the wavelength dispersibility of the optically anisotropic layer of the retardation film of the present invention is preferably 1.05 to 1.15, and 1.06 to 1.14. It is preferable that it is and it is especially preferable that it is 1.07-1.13. When having such wavelength dispersion, it is possible to obtain wavelength dispersion preferable as a retardation film in combination with the wavelength dispersion of the polymer film, and it is possible to compensate the liquid crystal display element over the entire visible light region. The in-plane retardation Re of the optically anisotropic layer is preferably 0 to 10 nm, more preferably 0 to 5 nm.

  In addition, a value obtained by dividing retardation Rth in the thickness direction of the optically anisotropic layer by the film thickness d of the optically anisotropic layer, Rth / d is preferably 0.080 or more, and 0.090 or more. It is still more preferable, and it is more preferable that it is 0.10 or more. Such an optically anisotropic layer has an advantage that unevenness hardly occurs when continuously applied to a long support. By using a liquid crystal compound excellent in Rth expression, particularly a liquid crystal compound represented by the general formula (DI) described later, an optically anisotropic layer having an Rth / d of 0.080 or more can be easily formed. The upper limit of Rth / d is not particularly limited, but is generally 0.20 or less.

[Optically anisotropic layer made of liquid crystalline compound]
The optically anisotropic layer is preferably formed from a polymerizable composition, and in particular, formed from a composition having a liquid crystalline compound having an optically negative refractive index anisotropy and having a polymerizable group. It is preferable. As such an optically anisotropic layer, a layer formed from a polymerizable composition containing a chiral nematic (cholesteric) liquid crystalline compound, a composition containing a discotic liquid crystalline compound, and derived from the discotic liquid crystalline compound A layer in which the discotic structural units are horizontally oriented with respect to the layer surface.

The chiral nematic (cholesteric) liquid crystal compound means a compound that forms a chiral nematic (cholesteric) liquid crystal phase when a composition containing the compound is applied onto a polymer substrate. Or a liquid crystalline compound.
In order to align the rod-like liquid crystalline compound with chiral nematic (cholesteric) orientation, an optically active rod-like liquid crystalline compound is used, or a mixture of the rod-like liquid crystalline compound and the optically active compound is used. The rod-like liquid crystalline compounds are azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano substituted phenylpyrimidines, alkoxy substituted phenylpyrimidines, Phenyl dioxanes, tolanes and alkenyl cyclohexyl benzonitriles are preferred.
The composition containing the compound can be applied on a polymer film substrate, and can be fixed while maintaining the alignment state in the same manner as in the method for producing an optically anisotropic layer comprising a discotic liquid crystalline compound described later.

  The optically anisotropic layer can also be formed using a polymer material having negative refractive index anisotropy when coated and having an optical axis in the normal direction of the film surface. As such a polymer material, a film-forming material having at least one kind of aromatic ring (polyamide, polyimide, polyamic acid, polyester, polyesteramide, etc.) as proposed in JP-A-2000-190385 Or a low molecular weight compound capable of giving these polymers) has a negative refractive index anisotropy when coated, an optical axis in the normal direction of the surface, and is usually positive. Has retardation of wavelength dispersion.

[Optically anisotropic layer made of discotic liquid crystalline compound]
In the present invention, the optically anisotropic layer is preferably formed from a composition containing a discotic liquid crystalline compound.
Discotic liquid crystalline compounds are disclosed in various literatures (C. Destrade et al., Mol. Crysr. Liq. Cryst., Vol. 71, page 111 (1981); edited by the Chemical Society of Japan, Quarterly Chemical Review, No. 22, Liquid Crystal Chemistry, Chapter 5, Chapter 10 Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 (1985); J. Zhang et al., J Am. Chem. Soc., Vol. 116, page 2655 (1994)) can be widely used. For the polymerization of the discotic liquid crystalline compound, for example, the method described in JP-A-8-27284 can be employed.

The discotic liquid crystalline compound preferably has a polymerizable group so that it can be fixed by polymerization. For example, a structure in which a polymerizable group is bonded as a substituent to a discotic core of a discotic liquid crystalline compound can be considered. A structure having a linking group between the discotic core and the polymerizable group is more preferable. When a structure having a linking group is employed, it becomes easier to maintain the alignment state in the polymerization reaction. The discotic liquid crystalline compound having a polymerizable group is preferably a compound represented by the following general formula (VI).
Formula (VI) D (-LP) _n
(In General Formula (VI), D is a discotic core, L is a divalent linking group, P is a polymerizable group, and n is an integer of 2 to 12.)

  The discotic core (D), divalent linking group (L) and polymerizable group (P) in the formula (VI) are, for example, (D1) to (D15) described in JP-A No. 2001-4837. , (L1) to (L25) and (P1) to (P18) can be used.

  In the case of a discotic liquid crystalline compound having a polymerizable group, it is substantially horizontally aligned as described above. Preferable examples of the discotic liquid crystalline compound in this case also include those described in International Publication WO 01 / 88574A1, page 58, line 6 to page 65, line 8.

In the present invention, the discotic liquid crystalline compound is preferably a compound represented by the following general formula (DI).

In the above general formula (DI), Y ¹¹ , Y ¹² , and Y ¹³ each independently represent a methine or a nitrogen atom.

When Y ¹¹ , Y ¹² , and Y ¹³ are methine, the hydrogen atom of methine may be substituted with a substituent. Here, methine refers to an atomic group obtained by removing three hydrogen atoms from methane.
Examples of the substituent that the carbon atom of methine may have include an alkyl group, an alkoxy group, an aryloxy group, an acyl group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, an alkoxycarbonylamino group, an alkylthio group, an arylthio group, Preferred examples include halogen atoms and cyano groups.
Among these substituents, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an acyloxy group, a halogen atom and a cyano group are more preferable, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, and a carbon number A 2-12 alkoxycarbonyl group, a C2-C12 acyloxy group, a halogen atom, and a cyano group are still more preferable.
Y ¹¹ , Y ¹² and Y ¹³ are more preferably methine, and methine is more preferably unsubstituted.

In the general formula (DI), L ¹ , L ² , and L ³ each independently represent a single bond or a divalent linking group. When L ¹ , L ² , and L ³ are divalent linking groups, each independently represents —O—, —S—, —C (═O) —, —NR ⁷ —, —CH═CH—, It is preferably a divalent linking group selected from the group consisting of —C≡C—, a divalent cyclic group, and combinations thereof.
R ⁷ is an alkyl group having 1 to ⁷ carbon atoms or a hydrogen atom, preferably an alkyl group having 1 to 4 carbon atoms or a hydrogen atom, and preferably a methyl group, an ethyl group, or a hydrogen atom. More preferably, it is particularly preferably a hydrogen atom.

The divalent cyclic group in L ¹ , L ² , and L ³ is a divalent linking group having at least one cyclic structure (hereinafter sometimes referred to as a cyclic group). The cyclic group preferably has a 5-membered ring, a 6-membered ring, or a 7-membered ring, more preferably has a 5-membered ring or a 6-membered ring, and still more preferably has a 6-membered ring. The ring contained in the cyclic group may be a condensed ring. However, it is preferably a monocycle rather than a condensed ring.
Further, the ring contained in the cyclic group may be any of an aromatic ring, an aliphatic ring, and a heterocyclic ring. Preferred examples of the aromatic ring include a benzene ring and a naphthalene ring.
A preferable example of the aliphatic ring is a cyclohexane ring.
Preferred examples of the heterocyclic ring include a pyridine ring and a pyrimidine ring.
The cyclic group is more preferably an aromatic ring or a heterocyclic ring. The cyclic group is more preferably a divalent linking group consisting of only a cyclic structure (including a substituent).

Of the divalent cyclic groups represented by L ¹ , L ² and L ³ , the cyclic group having a benzene ring is preferably a 1,4-phenylene group.
As the cyclic group having a naphthalene ring, a naphthalene-1,5-diyl group and a naphthalene-2,6-diyl group are preferable.
The cyclic group having a cyclohexane ring is preferably a 1,4-cyclohexylene group.
As the cyclic group having a pyridine ring, a pyridine-2,5-diyl group is preferable.
The cyclic group having a pyrimidine ring is preferably a pyrimidine-2,5-diyl group.

The divalent cyclic group represented by L ¹ , L ² and L ³ may have a substituent. Examples of the substituent include a halogen atom, a cyano group, a nitro group, an alkyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, an alkynyl group having 2 to 16 carbon atoms, and 1 to 1 carbon atoms. 16 halogen-substituted alkyl groups, alkoxy groups having 1 to 16 carbon atoms, acyl groups having 2 to 16 carbon atoms, alkylthio groups having 1 to 16 carbon atoms, acyloxy groups having 2 to 16 carbon atoms, carbon atoms Examples include an alkoxycarbonyl group having 2 to 16 carbon atoms, a carbamoyl group, a carbamoyl group substituted with an alkyl group having 2 to 16 carbon atoms, and an acylamino group having 2 to 16 carbon atoms.

L ¹ , L ² , and L ³ include a single bond, * —O—CO—, * —CO—O—, * —CH═CH—, * —C≡C—, * —divalent cyclic group. -, * -O-CO-divalent cyclic group-, * -CO-O-divalent cyclic group-, * -CH = CH-divalent cyclic group-, * -C≡C-divalent Cyclic group-, * -divalent cyclic group-O-CO-, * -divalent cyclic group-CO-O-, * -divalent cyclic group-CH = CH-, and * -divalent cyclic group. The group -C≡C- is preferred.
Among these, a single bond, * —CH═CH—, * —C≡C—, * —divalent cyclic group —O—CO—, * —CH═CH—divalent cyclic group—, and * —C. ≡C-divalent cyclic group- is more preferable, and a single bond is still more preferable.
Here, the above “*” represents a position bonded to the 6-membered ring side including Y ¹¹ , Y ¹² , and Y ¹³ in the general formula (DI).

H ¹ , H ² , and H ³ each independently represent the following general formula (DI-A) or the following general formula (DI-B).

In General Formula (DI-A), YA ¹ and YA ² each independently represent a methine or a nitrogen atom. It is preferable that at least one of YA ¹ and YA ² is a nitrogen atom, and it is more preferable that both are nitrogen atoms. XA represents an oxygen atom, a sulfur atom, methylene, or imino, and preferably an oxygen atom.
Here, in the above general formula (DI-A), "*" represents the position at which the group bonds to L ¹ ~L ³ side in formula (DI), "**" is R in formula (DI) ^{1 to} R ³ represents the position of binding. The imino is represented by -NH- (including those in which H is substituted with a substituent).

In the general formula (DI-B), YB ¹ and YB ² each independently represent a methine or a nitrogen atom. It is preferable that at least one of YB ¹ and YB ² is a nitrogen atom, and it is more preferable that both are nitrogen atoms.
XB represents an oxygen atom, a sulfur atom, methylene or imino, preferably an oxygen atom.
Here, in the above general formula (DI-B), "*" represents the position at which the group bonds to L ¹ ~L ³ side in formula (DI), "**" is the general formula (DI) It represents a position bonded with R ¹ to R ³ side in.

R ¹ , R ² , and R ³ each independently represent the following general formula (DI-R).

In the above general formula (DI-R), “*” represents a position bonded to the H ^{1 to} H ³ side in the general formula (DI).

In the general formula (DI-R), L ²¹ is a single bond or a divalent linking group. When L ²¹ is a divalent linking group, it consists of —O—, —S—, —C (═O) —, —NR ⁷ —, —CH═CH—, C≡C—, and combinations thereof. A divalent linking group selected from the group is preferred. R ⁷ is an alkyl group having 1 to ⁷ carbon atoms or a hydrogen atom, preferably an alkyl group having 1 to 4 carbon atoms or a hydrogen atom, and more preferably a methyl group, an ethyl group or a hydrogen atom. A hydrogen atom is preferable, and a hydrogen atom is particularly preferable.

In the general formula (DI-R), L ²¹ represents a single bond, ***-O-CO-, ***-CO-O-, ***-CH = CH-, and *. Any one of **-C≡C- (where “***” represents the “*” side in the general formula (DI-R)) is preferable, and a single bond is more preferable.

In the general formula (DI-R), Q ² represents a divalent group (cyclic group) having at least one kind of cyclic structure. As such a cyclic group, a cyclic group having a 5-membered ring, a 6-membered ring, or a 7-membered ring is preferable, a cyclic group having a 5-membered ring or a 6-membered ring is more preferable, and a cyclic group having a 6-membered ring is Particularly preferred. The cyclic structure contained in the cyclic group may be a condensed ring. However, it is more preferably a monocycle than a condensed ring.
Further, the ring contained in the cyclic group may be any of an aromatic ring, an aliphatic ring, and a heterocyclic ring. Preferred examples of the aromatic ring include a benzene ring and a naphthalene ring.
A preferable example of the aliphatic ring is a cyclohexane ring.
Preferred examples of the heterocyclic ring include a pyridine ring and a pyrimidine ring.
The cyclic group is more preferably an aromatic ring or a heterocyclic ring. The cyclic group is more preferably a divalent linking group consisting of only a cyclic structure (including a substituent).

In the general formula (DI-R), among Q ² , the cyclic group having a benzene ring is preferably a 1,4-phenylene group.
Moreover, as a cyclic group having a naphthalene ring, a naphthalene-1,5-diyl group and a naphthalene-2,6-diyl group are preferable.
Further, the cyclic group having a cyclohexane ring is preferably a 1,4-cyclohexylene group.
The cyclic group having a pyridine ring is preferably a pyridine-2,5-diyl group.
The cyclic group having a pyrimidine ring is preferably a pyrimidine-2,5-diyl group. Among these, a 1,4-phenylene group and a 1,4-cyclohexylene group are particularly preferable.

In the general formula (DI-R), Q ² may have a substituent. Examples of the substituent include a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, nitro group, alkyl group having 1 to 16 carbon atoms, alkenyl group having 2 to 16 carbon atoms, carbon An alkynyl group having 2 to 16 atoms, an alkyl group substituted with a halogen having 1 to 16 carbon atoms, an alkoxy group having 1 to 16 carbon atoms, an acyl group having 2 to 16 carbon atoms, and 1 to 16 carbon atoms An alkylthio group having 2 to 16 carbon atoms, an alkoxycarbonyl group having 2 to 16 carbon atoms, a carbamoyl group, an alkyl-substituted carbamoyl group having 2 to 16 carbon atoms, and an acylamino group having 2 to 16 carbon atoms Is included.
Among these, a halogen atom, a cyano group, an alkyl group having 1 to 6 carbon atoms, and an alkyl group substituted with a halogen having 1 to 6 carbon atoms are preferable, a halogen atom, an alkyl group having 1 to 4 carbon atoms, An alkyl group substituted with a halogen having 1 to 4 carbon atoms is more preferable, and a halogen atom, an alkyl group having 1 to 3 carbon atoms, and a trifluoromethyl group are particularly preferable.

  n1 represents the integer of 0-4. As n1, the integer of 1-3 is preferable and 1 or 2 is still more preferable.

L ²² is **-O-, **-O-CO-, **-CO-O-, **-O-CO-O-, **-S-, **-N (R)-, ** — CH ₂ —, ** — CH═CH—, or ** — C≡C— is represented, and “**” represents a position bonded to the Q ² side.
L ²² is preferably ** — O—, ** — O—CO—, ** — CO—O—, ** — O—CO—O—, ** — CH ₂ —, ** — CH. ═CH—, ** — C≡C—, more preferably ** — O—, ** — O—CO—, ** — O—CO—O—, ** — CH ₂ —. .

L ²³ is selected from the group consisting of —O—, —S—, —C (═O) —, —NH—, —CH ₂ —, —CH═CH— and C≡C—, and combinations thereof. Represents a divalent linking group.
Here, the hydrogen atoms of —NH—, —CH ₂ —, and —CH═CH— may be substituted with a substituent.
Examples of such a substituent include a halogen atom, a cyano group, a nitro group, an alkyl group having 1 to 6 carbon atoms, an alkyl group substituted with a halogen having 1 to 6 carbon atoms, and an alkoxy having 1 to 6 carbon atoms. Group, an acyl group having 2 to 6 carbon atoms, an alkylthio group having 1 to 6 carbon atoms, an acyloxy group having 2 to 6 carbon atoms, an alkoxycarbonyl group having 2 to 6 carbon atoms, a carbamoyl group, and 2 carbon atoms Preferred examples include a carbamoyl group substituted with -6 alkyl and an acylamino group having 2 to 6 carbon atoms, and a halogen atom and an alkyl group having 1 to 6 carbon atoms are more preferred.

L ²³ is preferably selected from the group consisting of —O—, —C (═O) —, —CH ₂ —, —CH═CH—, C≡C—, and combinations thereof.
L ²³ preferably contains 1 to 20 carbon atoms, more preferably 2 to 14 carbon atoms. Furthermore, L ²³ preferably contains 1 to 16 —CH ₂ —, and more preferably ₂ to 12 —CH ₂ —.

Q ¹ represents a polymerizable group or a hydrogen atom. When the liquid crystal compound used in the present invention is used for an optical compensation film in which the retardation does not change by heat, Q ¹ is preferably a polymerizable group.
The polymerization reaction is preferably addition polymerization (including ring-opening polymerization) or condensation polymerization. That is, the polymerizable group is preferably a functional group capable of addition polymerization reaction or condensation polymerization reaction. Examples of the polymerizable group are shown below.

  Furthermore, the polymerizable group is particularly preferably a functional group capable of addition polymerization reaction. As such a polymerizable group, a polymerizable ethylenically unsaturated group or a ring-opening polymerizable group is preferable.

  Examples of the polymerizable ethylenically unsaturated group include the following formulas (M-1) to (M-6).

In formulas (M-3) and (M-4), R represents a hydrogen atom or an alkyl group, and among them, a hydrogen atom or a methyl group is preferable.
Among the above formulas (M-1) to (M-6), the polymerizable ethylenically unsaturated group of the present invention is preferably (M-1) or (M-2), and (M-1) is More preferred.

  The ring-opening polymerizable group is preferably a cyclic ether group, more preferably an epoxy group or oxetanyl group, and particularly preferably an epoxy group.

  As the liquid crystalline compound used in the present invention, a liquid crystalline compound represented by the following general formula (DII) is particularly preferable.

In General Formula (DII), Y ³¹ , Y ³² , and Y ³³ each independently represent a methine or nitrogen atom, and have the same meaning as Y ¹¹ , Y ¹² , and Y ¹³ in General Formula (DI), The preferred range is also synonymous.

In the general formula (DII), R ³¹ , R ³² , and R ³³ each independently represent the following general formula (DII-R).

In the general formula (DII-R), A ³¹ and A ³² each independently represent a methine or nitrogen atom, preferably at least one is a nitrogen atom, and more preferably both are nitrogen atoms. X ³ represents an oxygen atom, a sulfur atom, methylene, or imino, and among them, an oxygen atom is preferable.

Q ³¹ represents a divalent linking group having a 6-membered cyclic structure (hereinafter sometimes referred to as a 6-membered cyclic group).
The 6-membered ring may be a condensed ring. However, it is more preferably a monocycle than a condensed ring.
The ring contained in the 6-membered cyclic group may be any of an aromatic ring, an aliphatic ring, and a heterocyclic ring. Preferred examples of the aromatic ring include a benzene ring and a naphthalene ring.
A preferable example of the aliphatic ring is a cyclohexane ring.
Preferred examples of the heterocyclic ring include a pyridine ring and a pyrimidine ring.
Q ³¹ is preferably a divalent linking group consisting of only a 6-membered cyclic structure (which may have a substituent).

Of Q ^31, the 6-membered cyclic group having a benzene ring is preferably a 1,4-phenylene group or a 1,3-phenylene group.
As the cyclic structure having a naphthalene ring, a naphthalene-1,5-diyl group and a naphthalene-2,6-diyl group are preferable.
The cyclic structure having a cyclohexane ring is preferably a 1,4-cyclohexylene group.
The cyclic structure having a pyridine ring is preferably a pyridine-2,5-diyl group.
The cyclic structure having a pyrimidine ring is preferably a pyrimidine-2,5-diyl group. Among these, a 1,4-phenylene group and a 1,3-phenylene group are particularly preferable.

The cyclic structure of Q ³¹ may have a substituent. Examples of the substituent include a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, nitro group, alkyl group having 1 to 16 carbon atoms, alkenyl group having 2 to 16 carbon atoms, carbon An alkynyl group having 2 to 16 atoms, an alkyl group substituted with a halogen atom having 1 to 16 carbon atoms, an alkoxy group having 1 to 16 carbon atoms, an acyl group having 2 to 16 carbon atoms, and 1 to 1 carbon atoms 16 alkylthio groups, acyloxy groups having 2 to 16 carbon atoms, alkoxycarbonyl groups having 2 to 16 carbon atoms, carbamoyl groups, alkyl-substituted carbamoyl groups having 2 to 16 carbon atoms, and acylamino having 2 to 16 carbon atoms A group is included.
The substituent of the 6-membered cyclic group is preferably a halogen atom, a cyano group, an alkyl group having 1 to 6 carbon atoms, or an alkyl group substituted with a halogen atom having 1 to 6 carbon atoms. An alkyl group substituted with a C 1-4 alkyl group or a C 1-4 halogen atom is more preferred, and a halogen atom, a C 1-3 alkyl group, or a trifluoromethyl group is more preferred.

  n3 represents an integer of 1 to 3, and preferably 1 or 2.

L ³¹ is * -O-, * -O-CO-, * -CO-O-, * -O-CO-O-, * -S-, * -N (R)-, * -CH _2-. , * —CH═CH—, or * —C≡C—.
In addition, “*” represents a position bonded to the Q ³¹ side, specifically, is synonymous with L ²² in the general formula (DI-R), and a preferred range is also synonymous.

L ³² is selected from the group consisting of —O—, —S—, —C (═O) —, —NH—, —CH ₂ —, —CH═CH—, C≡C—, and combinations thereof. It represents a divalent linking group, specifically, the general formula has the same meanings as (DI-R) in L ^23, and the preferred range is also the same.

Q ³² in the general formula (DII-R) represents a polymerizable group or a hydrogen atom, and specifically has the same meaning as Q ¹ in the general formula (DI-R), and the preferred range is also the same. It is.

  Specific examples of the liquid crystal compound represented by the general formula (DI) are shown below, but the present invention is not limited thereto.

  The liquid crystal compound used in the present invention desirably exhibits a liquid crystal phase exhibiting good monodomain properties. By making the monodomain property favorable, it is possible to effectively prevent the resulting structure from becoming a polydomain, causing an alignment defect at the boundary between domains, and scattering light. Furthermore, it is preferable to exhibit good monodomain properties because the retardation plate has a higher light transmittance.

  Examples of the liquid crystal phase exhibited by the liquid crystalline compound used in the present invention include a columnar phase and a discotic nematic phase (ND phase). Among these liquid crystal phases, a discotic nematic phase (ND phase) that exhibits good monodomain properties and can be hybrid-aligned is particularly preferable.

  The liquid crystalline compound used in the present invention is better as the anisotropic wavelength dispersion is smaller. Specifically, Re (450) / Re (650) is 1.25, where Re (λ) is the retardation (in-plane retardation value (nm) of the liquid crystal layer at wavelength λ) that the liquid crystalline compound develops. Is preferably less than 1.20, more preferably 1.20 or less, and particularly preferably 1.15 or less. The thickness of the optically anisotropic layer is 5 μm or less. In order to further reduce unevenness and make a layer having higher planar smoothness, the thickness is preferably 0.5 to 4.0 μm. The liquid crystalline compound represented by the formula (DI) is a compound particularly excellent in Rth expression, and exhibits a sufficiently high Rth even when the optically anisotropic layer is formed with the above thin film thickness. preferable.

In order to align the liquid crystal compound used in the present invention on a polymer film (or an alignment film provided thereon), the isotropic transition temperature T _iso is preferably 100 to 180 ° C., and 100 to 165 More preferably, it is 100 degreeC, and it is especially preferable that it is 100-150 degreeC.

  The optically anisotropic layer is formed by applying a curable liquid crystal composition containing the liquid crystalline compound on the surface of a polymer film or an alignment film made of a polyvinyl alcohol derivative or the like formed on the polymer film. It is preferable to form by fixing the alignment state by irradiating with ultraviolet rays or the like after the alignment. Various additives can be added to the curable composition for the purpose of improving the coatability and / or for promoting the alignment of the liquid crystal compound. Among them, it is preferable to add a fluoroaliphatic group-containing polymer because both effects can be obtained. Examples of the fluoroaliphatic group-containing polymer that can be used include polymers described in JP-A-2006-267183.

[Polarizer]
The present invention also relates to a polarizing plate having a polarizing film and the retardation film of the present invention.
In the polarizing plate of the present invention, the retardation film is preferably bonded to the surface of the polarizing film via an adhesive. More specifically, it is preferable that the back surface of the polymer film of the retardation film (the surface on which the optically anisotropic layer is not provided) is bonded to the surface of the polarizing film via an adhesive. In the case where another polymer film or the like is disposed between the polarizing film and the retardation film, the film is preferably optically isotropic.

Bonding is preferably performed using an adhesive. The adhesive is not particularly limited, but PVA resin (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) and boron compound aqueous solution can be used. preferable.
The thickness of the adhesive layer is preferably 0.01 to 10 μm after drying, and more preferably 0.05 to 5 μm.

  Bonding may be performed in a state where both ends of the retardation film of the present invention are held during the drying step, or may be performed after being released from both end holding portions after drying. It is preferable to wear the ears after bonding, and in the former case, both ends are bonded after being bonded to the polarizing film, and in the latter case, both ends are preferably set before being bonded to the polarizing film. As a method for cutting off the ears, general techniques such as a method of cutting with a cutter such as a blade or a method of using a laser can be used.

  After bonding, it is preferable to heat in order to dry the adhesive and improve the polarization performance. The heating conditions vary depending on the adhesive, but in the case of an aqueous system, 30 ° C or higher is preferable, 40 to 100 ° C is more preferable, and 50 to 90 ° C is still more preferable. It is more preferable in terms of performance and production efficiency that these processes are manufactured in a consistent line.

The retardation film may be subjected to a surface treatment to improve adhesion.
As the surface treatment, for example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used.
The glow discharge treatment here may be low-temperature plasma that occurs under a low pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferred.
Plasma-excitable gas refers to a gas that is plasma-excited under the above conditions, such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, chlorofluorocarbons such as tetrafluoromethane, and mixtures thereof. Can be mentioned.
As for these, the Japan Institute of Invention Disclosure Technical Bulletin No. 2001-1745 (issued March 15, 2001, Invention Association) p. 30-32.
Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, for example, irradiation energy of 20 to 500 kGy is used under 10 to 1,000 keV, and more preferably irradiation energy of 20 to 300 kGy is used under 30 to 500 keV. .

  As the polarizing film, for example, a polarizing film made of a polyvinyl alcohol film or the like can be dyed with iodine and stretched. You may implement the drying process which reduces a volatile matter rate after extending | stretching. It is also preferable that the drying is performed by laminating a retardation film or other protective film and then performing a heating step.

When another polymer film is present as a polarizing film protective film between the polarizing film and the retardation film of the present invention, the film is preferably substantially isotropic, specifically, The in-plane retardation Re is preferably 0 to 10 nm, more preferably 0 to 7 nm, and further preferably 0 to 5 nm. The retardation Rth in the thickness direction is preferably −25 to 25 nm, more preferably −15 to 15 nm, and particularly preferably −10 to 10 nm.
Moreover, when laminating | stacking the said retardation film on an isotropic film, it is preferable to use an isotropic adhesive. The isotropic film is preferably a cellulose acylate film.

  The polarizing plate of the present invention preferably has the retardation film of the present invention on one surface of the polarizing film and also has a protective film on the other surface. The protective film is preferably a cellulose acylate film.

  One aspect of the polarizing plate of the present invention is a polarizing film, a retardation film of the present invention (also serving as a protective film for a polarizing film), and a biaxial film having a predetermined optical property, which is a second retardation film described later, in this order. It is the aspect which has.

The optical properties and durability (short-term and long-term storage stability) of the polarizing plate of the present invention should be equal to or better than those of a commercially available super high contrast product (for example, HLC2-5618 manufactured by Sanlitz Co., Ltd.). Is preferred.
Specifically, the visible light transmittance is 42.5% or more, and the degree of polarization {(Tp−Tc) / (Tp + Tc)} ^1/2 ≧ 0.9995 (where Tp is parallel transmittance and Tc is orthogonal transmission) The rate of change in light transmittance before and after leaving in an atmosphere of 60 ° C. and humidity 90% RH for 500 hours and 80 ° C. in a dry atmosphere for 3 hours or less is 3% or less based on the absolute value. Is preferable, and 1% or less is more preferable. The rate of change in the degree of polarization is preferably 1% or less, more preferably 0.1% or less, based on the absolute value.

In the polarizing plate of the present invention, at least one layer of a hard coat layer, an antiglare layer or an antireflection layer is provided on the surface of the protective film (the surface on the viewing side) on at least one side of the polarizing plate. Is preferred.
That is, when the polarizing plate is used for a liquid crystal display device, it is preferable to provide a functional film such as an antireflection layer on the protective film disposed on the side opposite to the liquid crystal cell. It is preferable to provide at least one layer of a coat layer, an antiglare layer or an antireflection layer.
In addition, it is not necessary to provide each layer as a separate layer, for example, by providing an antireflection layer and a hard coat layer with an antiglare function, instead of providing two layers of an antireflection layer and an antiglare layer, You may make it function as an anti-glare antireflection layer.

-Antireflection layer In the present invention, an antireflection layer in which at least a light scattering layer and a low refractive index layer are laminated in this order on the protective film of the polarizing plate, or a medium refractive index layer and a high refractive index on the protective film. An antireflection layer in which a layer and a low refractive index layer are laminated in this order is suitably provided. Preferred examples thereof are described below. In the former configuration, the specular reflectance is generally 1% or more, which is referred to as a low reflection (LR) film. In the latter configuration, it is possible to realize a mirror reflectivity of 0.5% or less, and this is called an Anti Reflection (AR) film.

-LR film A preferred example of an antireflection layer (LR film) in which a light scattering layer and a low refractive index layer are provided on a protective film of a polarizing plate will be described.
In the light scattering layer, mat particles are preferably dispersed. The refractive index of the material other than the mat particles in the light scattering layer is preferably in the range of 1.50 to 2.00, and the low refractive index The refractive index of the refractive index layer is preferably in the range of 1.20 to 1.49.
In the present invention, the light scattering layer has both antiglare properties and hard coat properties, and may be a single layer or a plurality of layers, for example, two to four layers.

  The antireflection layer has an uneven surface shape, centerline average roughness Ra is 0.08 to 0.40 μm, 10-point average roughness Rz is 10 times or less Ra, average unevenness distance Sm is 1 to 100 μm, unevenness The standard deviation of the height of the convex part from the deepest part is 0.5 μm or less, the standard deviation of the average unevenness distance Sm with respect to the center line is 20 μm or less, and the surface with the inclination angle of 0 to 5 ° is 10% or more. It is preferable that it is designed so that sufficient anti-glare property and visual uniform matte feeling can be achieved.

Further, the ratio of the minimum value to the maximum value of the reflectance when the color of the reflected light under the C light source is in the range of a * value −2 to 2, b * value −3 to 3, and 380 to 780 nm is 0. It is preferable that the color is 5 to 0.99 because the color of the reflected light becomes neutral.
Furthermore, it is preferable that the b * value of the transmitted light under the C light source is 0 to 3 because the yellow color of white display when applied to a display device is reduced.
Furthermore, if a 120 μm × 40 μm grid is inserted between the surface light source and the antireflection layer and the luminance distribution is measured on the film, the standard deviation of the luminance distribution is 20 or less. Since glare when the polarizing plate of the invention is applied is reduced, it is preferable.

The antireflection layer that can be used in the present invention suppresses reflection of external light by setting its optical properties to a specular reflectance of 2.5% or less, a transmittance of 90% or more, and a 60 ° glossiness of 70% or less. This is preferable because visibility is improved. In particular, the specular reflectance is more preferably 1% or less, and further preferably 0.5% or less.
Moreover, haze 20-50%, ratio of internal haze / total haze value is 0.3-1, haze value after forming low refractive index layer from haze value to light scattering layer is within 15%, comb width Prevents glare on a high-definition LCD panel by setting the transmission image clarity at 0.5 mm to 20 to 50% and the transmittance ratio of vertical transmitted light / inclination 2 ° from the vertical to 1.5 to 5.0. This is preferable because blurring of characters and the like is reduced.

-Low refractive index layer 1.20-1.49 are preferable and, as for the refractive index of the low refractive index layer which can be used by this invention, 1.30-1.44 are more preferable. Furthermore, the low refractive index layer preferably satisfies the following formula (C) from the viewpoint of reducing the reflectance.
( _M / 4) λ × 0.7 <n _L d _L <(m / 4) λ × 1.3... (C)
In the above formula (C), m is a positive odd number, n _L is the refractive index of the low refractive index layer, and d _L is the film thickness (nm) of the low refractive index layer. Further, λ is a wavelength, which is a value in the range of 500 to 550 nm.

  The retardation film of the present invention is more preferably used for optical compensation of a VA mode liquid crystal display device in combination with a biaxial film having an Nz value of about 0.5 (hereinafter referred to as “second retardation film”). .

[Second retardation film]
A biaxial film having an Nz value of about 0.5 that can be preferably used in combination with the retardation film of the present invention will be described.
The second retardation film has a relationship of nx>nz> ny and satisfies the following formulas (3) and (4).
(3) 200 nm ≦ Re (550) ≦ 300 nm
(4) 0.3 <Nz <0.7
More preferably, the retardation film satisfies the following formulas (5) and (6).
(5) 240 nm ≦ Re (550) ≦ 290 nm
(6) 0.4 ≦ Nz ≦ 0.6

More specifically, the in-plane retardation of the second retardation film is preferably 240 nm or more, and more preferably 260 nm or more from the viewpoint of enhancing the compensation function. Moreover, it is preferable that it is 290 nm or less, and it is still more preferable that it is 280 nm or less.
The Nz value is preferably 0.4 or more, more preferably 0.45 or more from the viewpoint of enhancing the compensation function. Moreover, it is preferable that it is 0.6 or less, and it is still more preferable that it is 0.55 or less.

  Examples of the retardation film having such optical properties include a birefringent film of a polymer film and an alignment film of a liquid crystal polymer.

  Examples of the polymer include polyolefins such as polystyrene, polycarbonate, and polypropylene, polyesters such as polyethylene terephthalate and polyethylene naphthalate, alicyclic polyolefins such as polynorbornene, polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, and polyhydroxyethyl acrylate. , Hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polyarylate, polysulfone, polyether sulfone, polyphenylene sulfide, polyphenylene oxide, polyallyl sulfone, polyamide, polyimide, polyvinyl chloride, cellulosic polymer, or a binary system thereof, Examples include ternary various copolymers, graft copolymers, blends, and the like. The retardation film controls the refractive index in the thickness direction by a method of stretching a polymer film biaxially in the plane direction, a method of stretching uniaxially or biaxially in the plane direction, and stretching in the thickness direction, etc. Can be obtained. Further, it can be obtained by, for example, a method in which a heat-shrinkable film is adhered to a polymer film and the polymer film is stretched or / and contracted by tilting under the action of the shrinkage force by heating.

  Examples of the liquid crystalline polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. It is done. Specific examples of the main chain type liquid crystalline polymer include, for example, a nematic alignment polyester liquid crystalline polymer, a discotic polymer, and a cholesteric polymer having a structure in which a mesogen group is bonded to a spacer portion that imparts flexibility. . Specific examples of the side chain type liquid crystalline polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment imparting paraffin through a spacer portion composed of a conjugated atomic group as a side chain. Examples thereof include those having a mesogen moiety composed of a substituted cyclic compound unit. The alignment film of these liquid crystalline polymers is, for example, a liquid crystalline polymer on an alignment-treated surface such as a surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or an oblique deposition of silicon oxide. A solution in which the liquid crystal polymer is oriented by developing and heat-treating the above solution, and particularly in a tilted orientation, is preferred.

  Among these, the second retardation film is preferably any of a cellulose acylate film, a norbornene film, a polycarbonate film, a polyester film, and a polysulfone film.

  The lamination of the retardation film and the polarizing plate, and further the lamination to the liquid crystal panel may be simply arranged, and can be performed by an adhesive layer or the like. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is appropriately selected. Can be used. In particular, those having excellent optical transparency such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and being excellent in weather resistance, heat resistance and the like can be preferably used.

  For each layer such as an optical film or an adhesive layer, for example, a method of treating with an ultraviolet absorber such as a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex compound Those having an ultraviolet absorbing ability may be used.

[Liquid Crystal Display]
The present invention also relates to a liquid crystal display device having the retardation film of the present invention and / or the polarizing plate of the present invention.
The liquid crystal display device of the present invention may be any of a reflection type, a semi-transmission type, a transmission type liquid crystal display device and the like. A liquid crystal display device generally includes a polarizing plate, a liquid crystal cell, and, if necessary, a retardation film, a reflective layer, a light diffusion layer, a backlight, a front light, a light control film, a light guide plate, a prism sheet, a color filter, etc. Although comprised from a member, in this invention, there is no restriction | limiting in particular except the point which makes it essential to use the polarizing plate of this invention. The liquid crystal cell is not particularly limited, and a general liquid crystal cell such as a liquid crystal layer sandwiched between a pair of transparent substrates provided with electrodes can be used. The transparent substrate constituting the liquid crystal cell is not particularly limited as long as the liquid crystal material constituting the liquid crystal layer is aligned in a specific alignment direction. Specifically, a transparent substrate in which the substrate itself has a property of orienting liquid crystals, a transparent substrate in which an alignment film having the property of orienting liquid crystals is provided, but the substrate itself lacks the alignment ability. Either can be used. Moreover, a well-known thing can be used for the electrode of a liquid crystal cell. Usually, it can be provided on the surface of the transparent substrate in contact with the liquid crystal layer, and when a substrate having an alignment film is used, it can be provided between the substrate and the alignment film. The material exhibiting liquid crystallinity for forming the liquid crystal layer is not particularly limited, and examples thereof include various ordinary low-molecular liquid crystalline compounds, high-molecular liquid crystalline compounds, and mixtures thereof that can constitute various liquid crystal cells. Moreover, a pigment | dye, a chiral agent, a non-liquid crystalline compound, etc. can also be added to these in the range which does not impair liquid crystallinity.

  In addition to the electrode substrate and the liquid crystal layer, the liquid crystal cell may include various components necessary for forming various types of liquid crystal cells described later. As the liquid crystal cell system, a TN (Twisted Nematic) system, a STN (Super Twisted Nematic) system, an ECB (Electrically Controlled Birefringence) system, an IPS (In-Plane Switching) system, a VA (In-Plane Switching) system, a VA (In-Plane Switching) system, a VA (In-Plane Switching) system, a VA (In-Plane Switching) system, Alignment), PVA (Patterned Vertical Alignment), OCB (Optically Compensated Birefringence), HAN (Hybrid Aligned Nematic), ASM crocell) method, halftone gray scale method, domain division method, or display method using ferroelectric liquid crystal or antiferroelectric liquid crystal. The driving method of the liquid crystal cell is not particularly limited, and a passive matrix method used for STN-LCD and the like, and an active matrix method using an active electrode such as a TFT (Thin Film Transistor) electrode and a TFD (Thin Film Diode) electrode, Any driving method such as a plasma addressing method may be used. A field sequential method that does not use a color filter may be used.

  The mode of the liquid crystal cell is not particularly limited, but the VA mode is preferable.

  Next, preferred embodiments of the liquid crystal display device of the present invention will be described with reference to the drawings. In addition, the same number was attached | subjected to the same member in FIGS.

FIG. 1 is a schematic diagram showing a configuration of an embodiment of a VA mode liquid crystal display device.
The liquid crystal display device of FIG. 1 includes a pair of first polarizing film 3 and second polarizing film 8 arranged with the absorption axes 9 and 2 orthogonal to each other, and the pair of polarizing films 3 and 8. The liquid crystal cell 6 is disposed. Although omitted in the drawing, the liquid crystal cell 6 has a pair of substrates and a liquid crystal layer disposed between the pair of substrates, and the liquid crystal molecules in the liquid crystal layer are substantially relative to the substrate during black display. It is a so-called vertical alignment mode liquid crystal cell that is aligned orthogonally. A protective film is disposed on the outer surfaces of the first and second polarizing films 3 and 8, respectively.

  The liquid crystal display device of FIG. 1 further includes a first retardation film (retardation film of the present invention) 11 disposed between the first polarizing film 3 and the liquid crystal cell 6. The first retardation film 11 also functions as a protective film on the liquid crystal cell side of the first polarizing film 3.

  In the configuration of FIG. 1, the first retardation film, which is the retardation film of the present invention, has a thickness direction retardation (Rth) of 200 to 400 nm, preferably 230 to 370 nm, and preferably 250 to 400 nm. More preferably, it is particularly preferably 270 to 330 nm.

Rth (450) / Rth (550) is 1.04 to 1.09, more preferably 1.05 to 1.09, and particularly preferably 1.06 to 1.08.
In this configuration, it is preferable that the wavelength dispersion Rth (450) / Rth (550) of the first retardation film and the Rth (450) / Rth (550) of the liquid crystal cell are substantially equal. The absolute value of the difference is preferably 0.03 or less, more preferably 0.02 or less, and particularly preferably 0.01 or less.

  In FIG. 1, any of the first and second polarizing films 3 and 8 may be a backlight-side polarizing film or a viewing-side polarizing film, but the first polarizing film 3 is on the backlight side. It is preferable that

  The VA mode liquid crystal cell 6 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 horizontally when a voltage is applied. (2) Liquid crystal cell (SID97, Digest of tech. Papers (Proceedings) 28 (1997) 845 in which the VA mode is made into a multi-domain (MVA mode) in order to expand 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 Collection 58- 59 (1998)) and (4) SURVAVAL mode liquid crystal cells (announced at LCD International 98).

2 and 3 are schematic views showing the configuration of an embodiment of the VA mode liquid crystal display device of the present invention in which the second retardation film is mounted together with the retardation film of the present invention.
2 and 3 differ only in the axial arrangement (the direction of the slow axis) of the second retardation film.

  The liquid crystal display device of FIG. 2 includes a pair of first polarizing film 3 and second polarizing film 8 arranged with the absorption axes 9 and 2 orthogonal to each other, and the pair of polarizing films 3 and 8. The liquid crystal cell 6 is disposed. Although omitted in the drawing, the liquid crystal cell 6 has a pair of substrates and a liquid crystal layer disposed between the pair of substrates, and the liquid crystal molecules in the liquid crystal layer are substantially relative to the substrate during black display. It is a so-called vertical alignment mode liquid crystal cell that is aligned orthogonally. A protective film is disposed on the outer surfaces of the first and second polarizing films 3 and 8, respectively.

  2 further includes a first retardation film (retardation film of the present invention) 11 and a second polarizing film disposed between the first polarizing film 3 and the liquid crystal cell 6. The second retardation film 12 is disposed between the liquid crystal cell 6 and the liquid crystal cell 6. The first and second retardation films 11 and 12 also function as protective films on the liquid crystal cell side of the first and second polarizing films 3 and 8, respectively.

  2 or 3, the first retardation film, which is the retardation film of the present invention, has a thickness direction retardation (Rth) of 200 to 400 nm, preferably 230 to 370 nm, 250 More preferably, it is -400 nm, and it is especially preferable that it is 270-350 nm.

  Rth (450) / Rth (550) is 1.04 to 1.09, preferably 1.05 to 1.09, more preferably 1.06 to 1.09, and 1 It is especially preferable that it is 0.06-1.08.

  In FIG. 2, the second retardation film 12 has an in-plane slow axis perpendicular to the absorption axis of the second polarizing film 8 and satisfies the above formulas (3) and (4). Have The second retardation film 12 is a biaxial film, and the in-plane retardation Re (550) is 200 to 300 nm, preferably 240 to 290 nm, and more preferably 260 to 280 nm. Further, the Nz value is about 0.5, specifically 0.3 <Nz <0.7, preferably 0.4 to 0.6.

In FIG. 2, any of the first and second polarizing films 3 and 8 may be a backlight-side polarizing film or a viewing-side polarizing film, but the first polarizing film 3 is on the backlight side. It is preferable.
In addition, the laminated body which consists of the 1st phase difference film 11, the 1st polarizing film 3, and the protective film 1 in FIG. 2 is a polarizing plate of this invention, and it is preferable to use it for a backlight side polarizing plate.

  FIG. 4 and FIG. 5 are schematic views showing the configuration of another embodiment of the VA mode liquid crystal display device of the present invention in which the second retardation film is mounted together with the retardation film of the present invention. The configuration shown in FIG. 4 is different from the configuration shown in FIG. 2 in that a second polarizing plate protective film (cell side) is inserted between the second retardation film and the second polarizing film. Similarly, the configuration shown in FIG. 5 is different from the configuration shown in FIG. 3 in that a second polarizing plate protective film (cell side) is inserted between the second retardation film and the second polarizing film. The configurations shown in FIGS. 4 and 5 are different in the axial arrangement (the direction of the slow axis) of the second retardation film.

  4 and 5, the second polarizing plate protective film is preferably an optically substantially isotropic film.

  As a substantially isotropic film, the in-plane retardation (Re) is preferably 0 to 20 nm, more preferably 0 to 10 nm, and most preferably 0 to 5 nm. The retardation in the thickness direction (Rth) is preferably -60 nm to 60 nm, preferably -40 nm to 40 nm, and most preferably -20 nm to 20 nm. The wavelength dispersion is preferably such that the ratio of Re400 / Re700 is less than 1.2.

  The material for the polarizing plate protective film is not particularly limited as long as it satisfies the above-mentioned optical characteristics, but is preferably a cellulose ester film from the viewpoint of ease of polarizing plate processing.

  In the configuration of FIG. 4 or FIG. 5, the preferred range of the optical characteristics of the first retardation film and the second retardation film is the same as that of the liquid crystal display device having the configuration shown in FIG.

  In the embodiment of the VA mode of the present invention in which the second retardation film and the retardation film of the present invention are mounted, any of the configurations of FIGS. 2 to 5 may be used, but optical compensation can be performed more accurately. The configuration of FIG. 2 or 4 is more preferable, and the configuration of FIG. 2 is particularly preferable in that the liquid crystal panel can be thinned.

  FIG. 6 shows an example of the optical compensation mechanism of the VA mode liquid crystal display device having the configuration shown in FIG. 4 on the Poincare sphere. 6 shows that the polarization state I of light incident from the first polarizing film 3 in FIG. 4 is the first retardation film (retardation film of the present invention) 11, the liquid crystal cell 6, and the second retardation film. It is the figure which showed the locus | trajectory which passes 12 and reaches | attains the quenching point II of a diagonal direction (45 degrees) on the Poincare sphere. Since the retardation film of the present invention is used as the first retardation film 11, the wavelength dependence of the birefringence of the liquid crystal cell 6 is canceled by passing through the first retardation film 11, and thereafter The second retardation film 12 can bring the polarization state close to the extinction point II for any of R, G, and B light. As a result, there is no light leakage in the oblique direction, and color misregistration can be reduced.

Examples of the present invention will be described below, but the present invention is not limited to the following examples.
First, the retardation film of the present invention and a polarizing plate using the retardation film will be described, and subsequently, a VA mode liquid crystal display device equipped with the retardation film of the present invention and a second retardation film will be described.

[Example 1]
<Preparation of retardation film (F1)>
A commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Film Co., Ltd., film thickness 80 μm) was passed through a dielectric heating roll at a temperature of 60 ° C., and the film surface temperature was raised to 40 ° C. Solution A was applied with a bar coater at 14 ml / m ² and allowed to stay for 10 seconds under a steam far-infrared heater (manufactured by Noritake Co., Ltd.) heated to 110 ° C., and then purified water using the same bar coater. 3 ml / m ^{2 was} applied. The film temperature at this time was 40 degreeC. Next, washing with a fountain coater and draining with an air knife were repeated three times, and then the film was retained in a drying zone at 70 ° C. for 2 seconds and dried.

――――――――――――――――――――――――――――――――――
<Alkaline solution A composition>
――――――――――――――――――――――――――――――――――
Potassium hydroxide 4.7 parts by weight Water 15.7 parts by weight Isopropanol 64.8 parts by weight Propylene glycol 14.9 parts by weight C ₁₆ H ₃₃ O (CH ₂ CH ₂ O) ₁₀ H (surfactant) 1.0 mass Department ――――――――――――――――――――――――――――――――――

An alignment film coating solution having the following composition was continuously applied with a # 14 wire bar on the saponified surface of the produced long cellulose acetate film. The alignment film was formed by drying with warm air of 60 ° C. for 60 seconds and further with warm air of 100 ° C. for 120 seconds.
――――――――――――――――――――――――――
Composition of alignment film coating solution ――――――――――――――――――――――――――
The following modified polyvinyl alcohol 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Glutaraldehyde 0.5 parts by weight ――――――――――――――――――――――――――――

A coating liquid (S1) containing a discotic liquid crystalline compound having the following composition was prepared, and continuously coated on the prepared alignment film with a wire bar. The conveyance speed of the film was 20 m / min. The solvent was dried in a step of continuously heating from room temperature to 80 ° C., and then heated in a drying zone at 120 ° C. for 90 seconds to align the discotic liquid crystalline compound. Subsequently, while maintaining the temperature of the film at 90 ° C., UV light is irradiated at 500 mJ / cm ² using a high-pressure mercury lamp, the orientation of the liquid crystal compound is fixed, an optically anisotropic layer is formed, and a retardation film ( F1) was produced.

Composition of coating solution (S1) ――――――――――――――――――――――――――――――――――――
Composition of coating liquid (S1) containing discotic liquid crystal compound ――――――――――――――――――――――――――――――――――――
The following discotic liquid crystalline compound (I) 91 parts by mass Ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 9 parts by mass 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 following fluoropolymer A 0.4 parts by mass Methyl ethyl ketone 212 parts by mass ――――――――――――― ――――――――――――――――――――――

  The produced retardation film (F1) was measured for optical characteristics using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). Re measured at a wavelength of 550 nm was 2 nm, and Rth was 300 nm.

<Preparation of retardation film (F2)>
(Production of cellulose acetate film (CAF1))
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.

  The obtained inner layer dope and outer layer dope were cast on a drum cooled to 0 ° C. using a three-layer co-casting die. The film having a residual solvent amount of 70% by mass is peeled off from the drum, both ends are fixed with a pin tenter and dried at 80 ° C. while transporting at a draw ratio of 110% in the transport direction, and the residual solvent amount is 10%. Then, it was dried at 110 ° C. Thereafter, it was dried at a temperature of 140 ° C. for 30 minutes to produce cellulose acetate (CAF1) (outer layer: 3 μm, inner layer: 74 μm, outer layer: 3 μm) having a residual solvent of 0.3 mass%. Optical characteristics of the produced cellulose acetate film were measured.

  The obtained cellulose acetate film (CAF1) had a width of 1340 mm and a thickness of 80 μm. When the retardation value (Re) at a wavelength of 550 nm was measured using KOBRA 21ADH, it was 2 nm. Moreover, it was 80 nm when the retardation value (Rth) in wavelength 550nm was measured.

  The commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Film Co., Ltd.) used for the production of the retardation film (F1) was changed to the cellulose acetate film (CAF1) produced above, and the retardation values were as shown in Table 3. A retardation film (F2) was produced in the same manner as the retardation film (F1) except that the thickness of the optically anisotropic layer was changed so as to be a value.

  The produced retardation film (F2) was measured for optical properties using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). Re measured at a wavelength of 550 nm was 2 nm, and Rth was 300 nm.

<Preparation of retardation film (F3)>
An alignment film was formed on a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Film Co., Ltd.) in the same manner as the production of the retardation film (F1) produced above.

A coating liquid (S2) containing a discotic liquid crystalline compound having the following composition was prepared, and continuously coated on the prepared alignment film with a wire bar. The conveyance speed of the film was 20 m / min. The solvent was dried in a step of continuously heating from room temperature to 80 ° C., and then heated in a drying zone at 110 ° C. for 90 seconds to align the discotic liquid crystalline compound. Subsequently, the temperature of the film is maintained at 70 ° C., UV light is irradiated at 500 mJ / cm ² using a high-pressure mercury lamp, the orientation of the liquid crystal compound is fixed, an optically anisotropic layer is formed, and a retardation film ( F3) was prepared.

Composition of coating solution (S2) ――――――――――――――――――――――――――――――――――――
Composition of coating liquid (S2) containing discotic liquid crystal compound ――――――――――――――――――――――――――――――――――――
91 parts by mass of the discotic liquid crystalline compound D-524 Ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 9 parts by mass 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 fluoropolymer A 0.4 parts by mass Methyl ethyl ketone 212 parts by mass ――――――――――――――― ―――――――――――――――――――――

  Optical properties of the produced retardation film (F3) were measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). Re measured at a wavelength of 550 nm was 2 nm, and Rth was 300 nm.

<Preparation of retardation film (F4)>
The commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Film Co., Ltd.) used for the production of the retardation film (F3) was changed to the cellulose acetate film (CAF1) produced above, and the retardation value was as shown in Table 3. A retardation film (F4) was produced in the same manner as the retardation film (F3) except that the thickness of the optically anisotropic layer was changed so as to be a value.

<Production of Retardation Films (F5) to (F6)>
The discotic compound was changed from D-524 to D-521 with respect to the coating solution (S2) used in the retardation film (F3) produced above, to prepare a coating solution (S3).

  Retardation films (F5) and (F6) were produced in the same manner as the above produced retardation films (F3) and (F4) except that the coating solution (S3) was changed.

<Production of Retardation Films (F7) to (F8)>
With respect to the coating liquid (S2) used with the retardation film (F3) produced above, the discotic compound was changed from D-524 to D-10 to prepare a coating liquid (S4).

  Retardation films (F7) and (F8) were produced in the same manner except that the retardation films (F3) and (F4) produced above were changed to the coating solution (S4).

<Preparation of retardation film (F9)>
2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropanoic acid dianhydride in a reaction vessel (500 mL) equipped with a mechanical stirrer, Dean-Stark device, nitrogen inlet tube, thermometer and condenser tube [Clariant Japan Co., Ltd.] 17.77 g (40 mmol) and 2,2-bis (trifluoromethyl) -4,4′-diaminobiphenyl [Wakayama Seika Kogyo Co., Ltd.] 12.81 g (40 mmol) added. Subsequently, a solution in which 2.58 g (20 mmol) of isoquinoline was dissolved in 275.21 g of m-cresol was added, and the mixture was stirred at 23 ° C. for 1 hour (600 rpm) to obtain a uniform solution. Next, the reaction vessel was heated using an oil bath so that the temperature in the reaction vessel became 180 ± 3 ° C., and stirred for 5 hours while maintaining the temperature to obtain a yellow solution. After further stirring for 3 hours, the heating and stirring were stopped, and the mixture was allowed to cool to room temperature.

  Acetone was added to the yellow solution in the reaction vessel to completely dissolve the gel to prepare a diluted solution (7% by mass). When this diluted solution was gradually added to 2 L of isopropyl alcohol while stirring, a white powder was precipitated. This powder was collected by filtration and poured into 1.5 L of isopropyl alcohol for washing. Further, the same operation was repeated once again for washing, and then the powder was collected again by filtration. This was dried for 48 hours in an air circulation type constant temperature oven at 60 ° C. and then dried at 150 ° C. for 7 hours to obtain a polyimide powder (yield 85%). The weight average molecular weight (Mw) of the polyimide was 124,000, and the imidization ratio was 99.9%.

  The polyimide powder was dissolved in methyl isobutyl ketone to prepare a 15% by mass polyimide solution (coating solution S5). This polyimide solution was applied to the surface of a polymer film containing triacetyl cellulose [trade name “ZRF80S” (Re [550] = 0.5 nm, Rth [550] = 1.0 nm) manufactured by Fuji Film Co., Ltd.) Coating was performed in one direction with a rod coater. Next, the solvent is evaporated by drying in a 135 ± 1 ° C. air circulating constant temperature oven for 5 minutes, then in a 150 ± 1 ° C. air circulating constant temperature oven for 10 minutes, and a polyimide layer (thickness 7.5 μm) The retardation film (F9) provided with was produced. The characteristics are shown in Table 4.

The results of the retardation films (F1) to (F9) produced above are summarized in Table 2.
In Table 2, unevenness of the retardation film was evaluated by the following method.

(Evaluation of unevenness)
On the Schaukasten set in the dark room, two polarizing plates occur so that their absorption axes are orthogonal to each other. The retardation film prepared above is placed between the two polarizing plates, and the direction is 60 degrees from the normal direction. The unevenness was evaluated according to the following criteria when viewed from a distance of 1 m.
A: Unevenness is not observed.
○: Slight unevenness occurs.
Δ: Unevenness is visible in part.
X: Unevenness is visible on the entire surface.

(Preparation of polarizing plate (P1))
The retardation film (F1) is saponified, iodine is adsorbed to the stretched polyvinyl alcohol film to produce a polarizing film, and one surface of the polarizing film is saponified using a polyvinyl alcohol adhesive. Further, the retardation film (F1) was attached by roll-to-roll.
In addition, a commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Film Co., Ltd.) is saponified, and is attached to the other surface of the polarizing film with a roll-to-roll using a polyvinyl alcohol-based adhesive. And dried for 10 minutes or more to produce a polarizing plate (P1).

(Preparation of polarizing plates (P2) to (P9))
The polarizing plate (P2) to the polarizing plate (P1) was prepared in the same manner as the polarizing plate (P1) except that the retardation film (F1) was replaced with the retardation films (F2) to (F9). (P9) was produced.

<Production of cellulose acetate film (T0)>
(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 well for 30 minutes to obtain a silica particle dispersion. This dispersion was put into a disperser together with the following composition, and further stirred for 30 minutes or more to dissolve each component to prepare a matting agent solution.
Matting agent solution composition ――――――――――――――――――――――――――――――――――
Silica particle dispersion 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 ――――――――――――――――――――――――――――――

(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.

(Preparation of polarizing plate (P0))
The retardation film (F1) was changed to the cellulose acetate film (T0) with respect to the polarizing plate (P1) produced above, and the polarizing plate (P0) was produced.

(Preparation of polarizing plate (P10))
With respect to the polarizing plate (P1) produced above, the retardation film (F1) was changed to a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Film Co., Ltd.) to produce a polarizing plate (P10).

(Production of liquid crystal display device)
<< Production of vertical alignment liquid crystal cell >>
1% by mass of octadecyldimethylammonium chloride (coupling agent) was added to a 3% by mass aqueous polyvinyl alcohol solution. This was spin-coated on a glass substrate with an ITO electrode, heat-treated at 160 ° C., and then rubbed to form a vertical alignment film. The rubbing treatment was performed so that the two glass substrates were in opposite directions. Two glass substrates were faced to each other so that the cell gap (d) was about 5.0 μm. A vertical alignment liquid crystal cell A was produced by injecting a liquid crystal compound (Δn: 0.06) mainly composed of ester and ethane into the cell gap. The product of Δn and d was 300 nm.
Further, the wavelength dispersion Rth (450) / Rth (550) of retardation Rth in the thickness direction in the absence of an electric field of the liquid crystal cell was 1.07. Here, Rth (450) and Rth (550) are retardation Rth in the thickness direction of the liquid crystal cell at 450 nm and 550 nm, respectively, in the absence of an electric field.

The polarizing plate (P1) and the polarizing plate (P0) produced above were bonded to the upper and lower glass substrates of the vertical alignment liquid crystal cell using an adhesive. At this time, the polarizing plate (P1) is disposed as the polarizing plate on the backlight side, the polarizing plate (P0) is disposed as the viewing-side polarizing plate, and the retardation film (F1) included in the polarizing plate (P1) is provided. The cellulose acetate film (T0) contained in the polarizing plate (P0) was bonded to the backlight side so that the glass substrate was in contact with the glass substrate on the viewing side.
Moreover, it arrange | positioned so that the absorption axis of a polarizing plate (P1) and the absorption axis of a polarizing plate (P0) may orthogonally cross.

  The liquid crystal display device (L1) has the configuration shown in FIG. 1, the first polarizing film 3 is a backlight-side polarizing plate, the first retardation film 11 is a retardation film (F1), and the first It also serves as a protective film for the polarizing film 3.

  With respect to the liquid crystal display device (L1), the backlight side polarizing plate was changed as shown in Table 4, and liquid crystal display devices (L0) and (L2) to (L5) were produced.

  The liquid crystal display devices (L0) to (L5) prepared above were evaluated for front and oblique light leakage, color shift and unevenness when viewed from the front and oblique directions, and are summarized in Table 3.

(1) Light leakage (front)
A liquid crystal cell is placed on a Schaukasten set in a dark room without attaching a polarizing plate, and a luminance meter (spectral radiance meter CS-1000: Minolta Co., Ltd.) placed 1 m away in the normal direction. Brightness 1 was measured.
Next, each liquid crystal display device having a polarizing plate bonded on the same Schaukasten as described above was placed, and the luminance 2 was measured in the same manner as described above.

(2) Leakage light (oblique)
A liquid crystal cell is placed on a Schaukasten set in a dark room with no polarizing plate attached, and is oriented 45 degrees to the left with respect to the rubbing direction of the liquid crystal cell and 60 degrees from the normal direction of the liquid crystal cell. The luminance 1 was measured with a luminance meter (spectral radiance meter CS-1000: manufactured by Minolta Co., Ltd.) installed at a distance of 1 m in the direction of.
Then, each liquid crystal display device having a polarizing plate bonded on the same Schaukasten as described above was placed, and the luminance 2 was measured in the same manner as described above.

(3) Color shift during black display (front)
Place the liquid crystal cell with the polarizing plate pasted on the Schaukasten set in the dark room, and observe the liquid crystal cell from the place 1m away in the normal direction. It was evaluated as follows. The intensity of the color shift was in accordance with the following criteria.
○: Specific color is not visible ○ △: Specific color is slightly visible
Δ: A specific color can be seen a little.
X: A specific color can be clearly seen.

(4) Color shift during black display (diagonal)
A liquid crystal cell is placed on a Schaukasten set in a dark room with a polarizing plate attached, and is oriented 45 degrees leftward with respect to the rubbing direction of the liquid crystal cell and 60 degrees from the normal direction of the liquid crystal cell. The color shift at the time of black display was evaluated based on the same criteria as the above (3) from a distance of 1 m in the direction of.

(5) Unevenness Place the liquid crystal cell on the Schaukasten set in the dark room without placing the polarizing plate so that the substrate on which the electrode is placed is on the Schaukasten side, and turn left with respect to the rubbing direction of the liquid crystal cell. In addition, the unevenness was evaluated according to the following criteria when viewed from a position 1 m away from the normal direction of the liquid crystal cell at a direction of 45 degrees and 60 degrees from the normal line direction.
A: Unevenness is not observed.
○: Slight unevenness occurs.
Δ: Unevenness is visible in part.
X: Unevenness is visible on the entire surface.

From the results in Table 3, the following is clear.
A retardation film having a retardation Rth in the thickness direction is protected between the liquid crystal cell and the polarizer so that the retardation of the liquid crystal cell is canceled against a film using a normal cellulose acetate film as the polarizing plate protective film. By inserting it as a film, oblique leakage light and its color shift can be improved. However, in the VA mode using the retardation film of 1.04 ≦ Rth (450) / Rth (550) ≦ 1.09 of the present invention. The liquid crystal display device had no unevenness, and both light leakage and color shift were good.

  In particular, a VA mode liquid crystal display equipped with the retardation film of the present invention having an optically anisotropic layer formed using a coating liquid S2 containing a discotic compound D-524 (liquid crystal compound of general formula (DI)). The apparatus was particularly excellent with no unevenness, little light leakage in the oblique direction, and little color shift in the oblique direction.

  Next, a VA mode liquid crystal display device in which a biaxial film (retardation film B) and the retardation film (retardation film) of the present invention are mounted as a second retardation film will be described.

(Production of biaxial film (retardation film B))
A heat-shrinkable film was adhered to both sides of the polycarbonate film via an adhesive layer, and then uniaxially stretched 1.3 times at 152 ° C. to obtain a stretched film. The obtained stretched film had an in-plane retardation (Re) of 270 nm and an Nz value = 0.50.

A vertically aligned liquid crystal cell is prepared by the same method as described above, and the polarizing plate (P3) prepared above and the retardation film B prepared above are applied to the upper and lower glass substrates of the vertically aligned liquid crystal cell using an adhesive. Pasted together. At this time, a polarizing plate (P3) was disposed as a polarizing plate on the backlight side, and the retardation film (F3) contained in the polarizing plate (P3) was bonded so as to be in contact with the glass substrate on the backlight side. Furthermore, the polarizing plate (P0) produced above was bonded onto the retardation film B so that the cellulose acetate film (T0) was in contact therewith to produce a liquid crystal display device (L8).
The liquid crystal display device (L8) has the configuration shown in FIG. 4, and the absorption axis of the polarizing plate (P3) is set so that the absorption axis of the polarizing plate (P0) is orthogonal to the in-plane slow axis of the retardation film B. It arrange | positioned so that an axis | shaft and the absorption axis of a polarizing plate (P0) may orthogonally cross.

  The liquid crystal display device (L8) produced above was evaluated in the same manner as the liquid crystal display (L1) and summarized in the following table.

The following can be understood from the results shown in Table 4.
By using the retardation film (first retardation film) of the present invention in combination with a biaxial retardation film having an Nz value of 0.5, a liquid crystal display device with little oblique light leakage and little color shift can be obtained. can get.

It is a schematic diagram which shows the structure of embodiment of the liquid crystal display device of this invention. It is a schematic diagram which shows the structure of other embodiment of the liquid crystal display device of this invention. It is a schematic diagram which shows the structure of other embodiment of the liquid crystal display device of this invention. It is a schematic diagram which shows the structure of other embodiment of the liquid crystal display device of this invention. It is a schematic diagram which shows the structure of other embodiment of the liquid crystal display device of this invention. It is the figure which showed on the Poincare sphere an example of the locus | trajectory of the polarization state of the light which injected into the liquid crystal display device of embodiment shown in FIG.

Explanation of symbols

1 First polarizing film protective film (outside)
2 First polarizing film absorption axis direction 3 First polarizing film 6 Liquid crystal cell 7 Second polarizing film protective film (cell side)
8 Second polarizing film 9 Second polarizing film absorption axis direction 10 Second polarizing film protective film (outside)
11 First retardation film (retardation film of the present invention)
12 Second retardation film 13 Slow axis direction of second retardation film

Claims (18)

A retardation film having a polymer film and an optically anisotropic layer having a thickness of 5 μm or less thereon, an in-plane retardation Re (550) at a wavelength of 550 nm of 0 to 10 nm, and a thickness of a wavelength of 550 nm A retardation film having a retardation Rth (550) in a direction of 200 to 400 nm and satisfying the following formula (1).
(1) 1.04 ≦ Rth (450) / Rth (550) ≦ 1.09 The in-plane retardation Re (550) at a wavelength of 550 nm of the optically anisotropic layer is 0 to 10 nm, the retardation Rth (550) in the thickness direction of the same wavelength is 200 to 400 nm, and the following formula (2 The retardation film according to claim 1, wherein:
(2) 1.05 ≦ Rth (450) / Rth (550) ≦ 1.15 A value obtained by dividing retardation Rth (550) in the thickness direction of the optically anisotropic layer at a wavelength of 550 nm by the film thickness d of the optically anisotropic layer, and Rth (550) / d is 0.080 or more. The retardation film according to claim 1, wherein: The retardation film according to claim 1, wherein the optically anisotropic layer is formed from a polymerizable composition. The polymerizable composition is a composition containing a discotic liquid crystal compound having a polymerizable group, and in the optically anisotropic layer, the discotic structural unit of the discotic liquid crystal compound is aligned horizontally with respect to the layer surface. The retardation film according to any one of claims 1 to 4. The retardation film according to claim 5, wherein the discotic liquid crystalline compound is a compound represented by the following formula (DI).

[Wherein Y ¹¹ , Y ¹² and Y ¹³ each independently represent a methine group or a nitrogen atom;
L ¹ , L ² , and L ³ each independently represent a single bond or a divalent linking group;
H ¹ , H ² , and H ³ each independently represent the following general formula (DI-A) or the following general formula (DI-B);

[In General Formula (DI-A), YA ¹ and YA ² each independently represent methine or a nitrogen atom; “*” represents a position bonded to the L ^{1 to} L ³ side in General Formula (DI). ;
“**” represents a position bonded to the R ^{1 to} R ³ side in the general formula (DI). ]

[In General Formula (DI-B), YB ¹ and YB ² each independently represent a methine or nitrogen atom; “*” represents a position bonded to the L ^{1 to} L ³ side in General Formula (DI). Representation;
“**” represents a position bonded to the R ^{1 to} R ³ side in the general formula (DI). ]
R ¹ , R ² , and R ³ each independently represent the following general formula (DI-R).

[In the general formula (DI-R), “*” represents a position bonded to the H ^{1 to} H ³ side in the general formula (DI);
L ²¹ represents a single bond or a divalent linking group;
Q ² represents a divalent group (cyclic group) having at least one kind of cyclic structure;
n1 represents an integer of 0 to 4;
L ²² is **-O-, **-O-CO-, **-CO-O-, **-O-CO-O-, **-S-, **-N (R)-, ** — CH ₂ —, ** — CH═CH—, or ** — C≡C—, and “**” represents the position to be bonded to the Q ² side;
L ²³ is selected from the group consisting of —O—, —S—, —C (═O) —, —NH—, —CH ₂ —, —CH═CH— and C≡C—, and combinations thereof. Represents a divalent linking group;
Q ¹ represents a polymerizable group or a hydrogen atom. ] The retardation film according to claim 1, wherein the optically anisotropic layer contains a fluoroaliphatic group-containing polymer. The retardation film according to any one of claims 1 to 7, wherein the retardation Rth (550) in the thickness direction of a wavelength of 550 nm of the polymer film is 30 nm or more. The retardation film according to claim 1, wherein the polymer film is a cellulose acylate film. A polarizing plate comprising at least a polarizing film and the retardation film according to claim 1. A liquid crystal display device comprising the retardation film according to claim 1. A pair of polarizing films whose absorption axes are orthogonal to each other, a pair of substrates disposed between the polarizing films, and a liquid crystal layer composed of liquid crystalline molecules sandwiched between the substrates, 12. The liquid crystal display device according to claim 11, wherein the liquid crystal display device is aligned in a direction substantially perpendicular to the substrate in a non-driving state where no external electric field is applied. The liquid crystal display device according to claim 11, further comprising a second retardation film, wherein the second retardation film is formed of a polymer stretched film. The in-plane retardation Re (550) of the second retardation film having a wavelength of 550 nm and the Nz value (Nz = Rth (550) / Re (550) +0.5) of the same wavelength are represented by the following formula (3) and the following formula: The liquid crystal display device according to claim 13, wherein (4) is satisfied.
(3) 200 nm ≦ Re (550) ≦ 300 nm
(4) 0.3 <Nz <0.7 In-plane retardation Re (550) of wavelength 550 of the second retardation film and Nz value (Nz = Rth (550) / Re (550) +0.5) of the same wavelength are represented by the following formula (5) and the following formula: The liquid crystal display device according to claim 13, wherein (6) is satisfied.
(5) 240 nm ≦ Re (550) ≦ 290 nm
(6) 0.4 ≦ Nz ≦ 0.6 The liquid crystal display device according to claim 13, wherein the second retardation film satisfies the following formula (7).
(7) 0.7 ≦ Re (450) / Re (550) ≦ 1.1 The second retardation film is any one of a cellulose acylate film, a norbornene film, a polycarbonate film, a polyester film, and a polysulfone film, according to any one of claims 13 to 16. The liquid crystal display device described. The second retardation film is directly laminated on one of the pair of polarizing films in an arrangement in which the in-plane slow axis and the absorption axis of the polarizing film are orthogonal to each other. A liquid crystal display device according to 1.

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