JP2009199070A - Polarizing plate and liquid crystal display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate which contributes to broadening of a viewing angle and improvement of display characteristics during black display and white display to intermediate tone display without reducing front face contrast of a liquid crystal display apparatus when compared with conventional technique. <P>SOLUTION: The polarizing plate has a polarizing layer 10, a first optical anisotropic layer 14, a second optical anisotropic layer 12 and a light diffusion layer 18. The first optical anisotropic layer 14 is a layer formed of a liquid crystal composition and a ratio (Re/Re) of retardation at 450 nm wavelength to retardation at 550 nm wavelength is 0.9 to 1.1. The second optical anisotropic layer 12 has retardation of 40 to 120 nm and retardation Rth in a thickness direction at 550 nm wavelength is 40 to 100 nm. Further scattered light intensity of the light diffusion layer 18 in a pole angle 30° direction is 0.01 to 0.2%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polarizing plate that contributes to an increase in the viewing angle of a liquid crystal display device, and a liquid crystal display device using the same.

Conventionally, various optical compensation films having an optically anisotropic layer formed of a liquid crystal composition on a transparent support have been proposed as optical compensation films for TN mode liquid crystal display devices. In the optical compensation film having this configuration, generally, the optical anisotropic layer formed from the liquid crystal composition has a retardation necessary for the optical compensation of the TN mode liquid crystal cell, and the liquid crystal cell is compensated to thereby adjust the viewing angle. Is expanding. On the other hand, as an optical compensation sheet having a predetermined range of optical characteristics of a transparent support made of a polymer film or the like that supports an optically anisotropic layer formed from a liquid crystal composition, for example, described in Patent Documents 1 and 2 Examples include an optical compensation sheet.
In addition, in order to further expand the viewing angle of the TN mode liquid crystal display device, a technique using a predetermined light diffusion film has been proposed (Patent Document 3).

JP 2002-169023 A Japanese Patent Laid-Open No. 2003-21718 JP 2003-43218 A

However, in a television (TV) or a personal computer with a TV function (PC), a plurality of observers often observe the display screen from various positions, and the viewing angle characteristics that a conventional PC display monitor satisfies are as follows: TV (or display monitor for PC with TV function) is not enough. Further, wide viewing angle characteristics are required not only when displaying black but also when displaying white to halftone.
Further, as one means for widening the viewing angle, the use of a light diffusing film can be mentioned as described above. As a result of various studies by the present inventors, the viewing angle of the conventional TN mode liquid crystal display device is set to TV. It has been found that the use of a light diffusing film in order to expand to a sufficient extent for the purpose of use significantly reduces the front contrast.

The present invention provides a polarizing plate that contributes to widening the viewing angle and improving display characteristics during black display and white display to halftone display, as compared with the prior art, without reducing the front contrast of the liquid crystal display device. The task is to do.
Another object of the present invention is to provide a liquid crystal display device that achieves high contrast not only in the front but also in a wide viewing angle range, and has good display characteristics during black display and white to halftone display. .

Means for solving the above-mentioned problems are as follows.
[1] A polarizing plate having a polarizing layer, first and second optically anisotropic layers, and a light diffusing layer, wherein the first optically anisotropic layer is a layer formed from a liquid crystal composition. The ratio Re (450) / Re (550) of Re (450) at a wavelength of 450 nm to Re (550) at a wavelength of 550 nm is 0.9 to 1.1, and the Re ( 550) is 40 to 120 nm, and the retardation Rth (550) in the thickness direction at a wavelength of 550 nm is 40 to 100 nm. Polarized light characterized in that the scattered light intensity in the direction of polar angle 30 ° is 0.01 to 0.2% at the azimuth angle at which the scattering intensity is maximum with respect to the light intensity in the direction normal to the layer surface) Board.
[2] The polarizing plate according to [1], wherein the first optically anisotropic layer is a layer formed from a liquid crystal composition containing at least one discotic liquid crystal compound.

［式中、
Ｙ¹¹、Ｙ¹²及びＹ¹³は、それぞれ独立に置換されていてもよい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、それぞれ独立に一般式（ＤＩ−Ａ）： [3] The polarizing plate according to [1] or [2], wherein the at least one discotic liquid crystal compound is a liquid crystal compound represented by the following general formula (DI):

[Where:
Y ¹¹ , Y ¹² and Y ¹³ each independently represent an optionally substituted methine or nitrogen atom;
L ¹ , L ² and L ³ each independently represents a single bond or a divalent linking group;
H ¹ , H ² and H ³ are each independently represented by the general formula (DI-A):

（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；
ＸＡは、酸素原子、硫黄原子、メチレン又はイミノを表し；
＊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。）
又は一般式（ＤＩ−Ｂ）：

（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；
ＸＢは、酸素原子、硫黄原子、メチレン又はイミノを表し；
＊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。）を表し；
Ｒ¹、Ｒ²及びＲ³は、それぞれ独立に下記一般式（ＤＩ−Ｒ）：

(In the general formula (DI-A),
YA ¹ and YA ² each independently represents a methine or nitrogen atom;
XA represents an oxygen atom, a sulfur atom, methylene or imino;
* Represents the position of bonding to the L ^{1 to} L ³ side in the above general formula (DI);
** represents a position to be bonded to the R ^{1 to} R ³ side in the general formula (DI). )
Or general formula (DI-B):

(In the general formula (DI-B),
YB ¹ and YB ² each independently represent a methine or nitrogen atom;
XB represents an oxygen atom, a sulfur atom, methylene or imino;
* Represents the position of bonding to the L ^{1 to} L ³ side in the above general formula (DI);
** represents a position to be bonded to the R ^{1 to} R ³ side in the general formula (DI). );
R ¹ , R ² and R ³ each independently represents the following general formula (DI-R):

General formula (DI-R)
-(-L ²¹ -Q ² ) _n1 -L ²² -L ²³ -Q ¹
(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 having at least one cyclic structure;
n ¹ represents an integer of 0 to 4, and L ²² represents ** — O—, ** — O—CO—, ** — CO—O—, ** — O—CO—O—, **. -S -, * - N (R ) -, ** - CH 2 -, ** - CH = CH- or ** - C≡C- represent, where ** is a position to bind to Q ² side Represents;
L ²² is **-O-, **-O-CO-, **-CO-O-, **-O-CO-O-, **-S-, **-N (R ¹⁰¹ )-. , ** — CH ₂ —, ** — CH═CH— or ** — C≡C—, R ¹⁰¹ represents an alkyl group having 1 to 5 carbon atoms, and ** binds to the Q ² side. Represents the position;
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 valent linking group;
Q ¹ represents a polymerizable group or a hydrogen atom)
Represents. ]

式中、Ｌ¹及びＬ²は各々独立に単結合又は二価の連結基を表し；Ａ¹及びＡ²は各々独立に、−Ｏ−、−ＮＲ−（Ｒは水素原子又は置換基を表す）、−Ｓ−及び−ＣＯ−からなる群から選ばれる基を表し；Ｒ¹、Ｒ²、及びＲ³は各々独立に置換基を表し；Ｘは第１４〜１６族の非金属原子を表し、ただし、Ｘには水素原子又は置換基が結合してもよく；ｎは０〜２の整数を表し；

式中、ＭＧ¹及びＭＧ²はそれぞれ独立に、２〜８個の環状基から構成される液晶相の発現を誘起する液晶コア部であり、液晶コア部を構成する環状基としては、芳香族環、脂肪族環、及び複素環のいずれでもよく；ＭＧ¹及びＭＧ²を構成する環状基の１つは、Ｌ¹¹及びＬ¹²で置換され；Ｒ¹¹、Ｒ¹²、Ｒ¹³、及びＲ¹⁴はそれぞれ液晶コア部の分子長軸方向に置換している液晶相の発現を誘起する柔軟性のある置換基、双極子作用基及び水素結合性基であり；Ｌ¹¹及びＬ¹²はそれぞれ独立に、液晶コア部ＭＧ¹及びＭＧ²に置換する連結基であり、下記式（ＩＩ）−ＬＡ又は式（ＩＩ）−ＬＢで表され；

式中、＊はＭＧ¹を構成する環状基に置換する位置を表し；＃はＰ¹と連結する位置を表し；Ａ¹¹、Ａ¹³及びＡ¹⁴はそれぞれ独立に、―Ｏ−、−ＮＨ−、−Ｓ−、−ＣＨ₂−、−ＣＯ−、−ＳＯ−、又は−ＳＯ₂−を表し；Ａ¹²は−ＣＨ＝又は−Ｎ＝を表し；Ｌ¹¹及びＬ¹²の双方が式（ＩＩ）−ＬＡで表される基の場合、置換基Ｐ¹は単結合、又は−ＣＨ＝ＣＨ−、−Ｃ≡Ｃ−、１，４−フェニレン及びそ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；Ｌ¹¹及びＬ¹²の一方が、式（ＩＩ）−ＬＢで表される基で、他方が式（ＩＩ）−ＬＡで表される基の場合、置換基Ｐ¹は、＊＝ＣＨ−Ｐ¹¹−＃、又は＊＝Ｎ−Ｐ¹¹−＃で表され（＊は式（ＩＩ）−ＬＢで表される基との連結位置を表し、＃は式（ＩＩ）−ＬＡで表される基との連結位置を表す）；Ｐ¹¹は単結合、又は−ＣＨ＝ＣＨ−、−Ｃ≡Ｃ−、１，４−フェニレン及びこの組み合わせから選ばれる二価の連結基を表し；Ｌ¹¹及びＬ¹²の双方が式（ＩＩ）−ＬＢで表される基の場合、置換基Ｐ¹は、二重結合、＝ＣＨ−Ｐ¹¹−ＣＨ＝、＝Ｎ−Ｐ¹¹−ＣＨ＝、＝Ｎ−Ｐ¹¹−Ｎ＝を表し；Ｐ¹¹は上記Ｐ¹¹と同義である。 [4] The first optically anisotropic layer contains a compound represented by the following general formula (I) or general formula (II), or is represented by the following general formula (I) or (II) A polarizing plate according to [1] or [2], comprising a polymer containing a repeating unit derived from a compound:

In the formula, L ¹ and L ² each independently represent a single bond or a divalent linking group; A ¹ and A ² each independently represent —O— or —NR— (R represents a hydrogen atom or a substituent). ), -S- and -CO-; R ¹ , R ² and R ³ each independently represents a substituent; X represents a non-metallic atom of Groups 14-16 Provided that a hydrogen atom or a substituent may be bonded to X; n represents an integer of 0 to 2;

In the formula, MG ¹ and MG ² are each independently a liquid crystal core part that induces the expression of a liquid crystal phase composed of 2 to 8 cyclic groups, and the cyclic group constituting the liquid crystal core part is an aromatic group Any of a ring, an aliphatic ring, and a heterocyclic ring; ^one of the cyclic groups constituting MG ¹ and MG ² is substituted with L ¹¹ and L ¹² ; R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ Are flexible substituents, dipole action groups, and hydrogen bonding groups that induce the expression of the liquid crystal phase substituted in the molecular long axis direction of the liquid crystal core; L ¹¹ and L ¹² are each independently , A linking group substituted for the liquid crystal core parts MG ¹ and MG ² , represented by the following formula (II) -LA or formula (II) -LB;

In the formula, * represents a position substituted with the cyclic group constituting MG ¹ ; # represents a position linked to P ¹ ; A ¹¹ , A ¹³ and A ¹⁴ are each independently —O—, —NH—. , -S-, -CH _2- , -CO-, -SO-, or -SO _2- ; A ¹² represents -CH = or -N =; both L ¹¹ and L ¹² are represented by the formula (II ) In the case of a group represented by -LA, the substituent P ¹ is a single bond or a divalent group selected from the group consisting of -CH = CH-, -C≡C-, 1,4-phenylene and combinations thereof. In the case where one of L ¹¹ and L ¹² is a group represented by the formula (II) -LB and the other is a group represented by the formula (II) -LA, the substituent P ¹ is represented by * = CH-P ¹¹ - #, or * = N-P ¹¹ - represented by # (* represents a linking position between the groups of the formula (II) -LB, # in formula (II) -LA Group represented Represents the coupling position); P ¹¹ is a single bond, or a -CH = CH -, - C≡C-, represents a 1,4-phenylene and a divalent linking group selected from the combination; L ¹¹ and L ¹² Are both groups represented by the formula (II) -LB, the substituent P ¹ is a double bond, ═CH—P ¹¹ —CH═, ═N—P ¹¹ —CH═, ═N—P ^11. -N =; P ¹¹ has the same meaning as P ¹¹ above.

[5] The polarizing plate according to any one of [1] to [4], wherein the second optically anisotropic layer is a cellulose acylate film.
[6] The polarizing plate according to any one of [1] to [4], wherein the second optically anisotropic layer is a cycloolefin-based polymer film or a polycarbonate film.
[7] The crossing angle between the in-plane slow axis of the second optically anisotropic layer and the in-plane transmission axis of the polarizing layer is approximately 0 degrees [1] to [6] ] The polarizing plate in any one of.
[8] A pair of oppositely arranged substrates having electrodes on at least one side and a nematic liquid crystal material sandwiched between the pair of substrates, and the liquid crystal molecules of the nematic liquid crystal material on the surface of the pair of substrates during black display And a liquid crystal cell having a liquid crystal layer having a product Δn · d of thickness d (micron) and refractive index anisotropy Δn of 0.1 to 1.5 μm, [1] A liquid crystal display device comprising the polarizing plate according to any one of [7] to [7].
[9] The liquid crystal display device according to [8], wherein the polarizing plate is a polarizing plate disposed on a display surface side with respect to the liquid crystal cell.

According to the present invention, a polarizing plate contributes to an increase in viewing angle and improvement in display characteristics during black display and white display to halftone display, as compared with the prior art, without reducing the front contrast of the liquid crystal display device. Can be provided.
In addition, the present invention can provide a liquid crystal display device that achieves high contrast not only in the front but also in a wide viewing angle range and has good display characteristics during black display and white to halftone display.

It is a cross-sectional schematic diagram of an example of the polarizing plate of this invention. It is a cross-sectional schematic diagram of an example of the liquid crystal display device of this invention.

Hereinafter, the present invention will be described in detail. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.
First, details of Re (λ), Rth (λ), tilt angle, and average tilt angle in this specification will be described below.
(Measurement of Re and Rth)
In the present specification, Re (λ) and Rth (λ) respectively represent in-plane retardation and thickness direction retardation at a wavelength λ. 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).
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, when the film has 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, the retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative.
In addition, the retardation value is measured from the two inclined directions, with the slow axis as the tilt axis (rotation axis) (in the absence of the slow axis, the arbitrary direction in the film plane is the rotation axis), Based on the value, the assumed value of the average refractive index, and the input film thickness value, Rth can also be calculated from the following equations (1) and (2).

注記：
上記式中、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表す。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。

Note:
In the above 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. Represents.

In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no so-called optical axis, Rth (λ) is calculated by the following method.
Rth (λ) is from −50 degrees to +50 degrees with respect to the normal direction of the film, with Re (λ) being the in-plane slow axis (determined by KOBRA 21ADH or WR) and the tilt axis (rotating axis). In each of the 10 degree steps, light of wavelength λ nm is incident from the inclined direction and measured at 11 points. Based on the measured retardation value, the assumed average refractive index, and the 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 films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. Examples of the average refractive index values of main optical films are given below:
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 value of the average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

(Measurement of tilt angle)
In an optically anisotropic layer in which a discotic liquid crystalline compound or a rod-like liquid crystalline compound is aligned, the tilt angle θ1 on one side of the optically anisotropic layer and the tilt angle θ2 on the other side are directly and accurately determined. It is difficult to measure. Therefore, in this specification, θ1 and θ2 are calculated by the following method. Although this method does not accurately represent the actual orientation state of the present invention, it is effective as a means for expressing the relative relationship of some optical properties of the optical film.
In this method, in order to facilitate calculation, the following two points are assumed and the tilt angle at the two interfaces of the optically anisotropic layer is used.
1. The optically anisotropic layer is assumed to be a multilayer body composed of layers containing a discotic liquid crystalline compound or a rod-like liquid crystalline compound. Further, it is assumed that the minimum unit layer (the tilt angle of the discotic liquid crystal compound or the rod-like liquid crystal compound is uniform in the layer) constituting it is optically uniaxial.
2. It is assumed that the tilt angle of each layer changes monotonically with a linear function along the thickness direction of the optically anisotropic layer.
The specific calculation method is as follows.
(1) In a plane in which the tilt angle of each layer changes monotonically with a linear function along the thickness direction of the optically anisotropic layer, the incident angle of the measurement light to the optically anisotropic layer is changed, and three or more The retardation value is measured at the measurement angle. In order to simplify the measurement and calculation, it is preferable to measure the retardation value at three measurement angles of −40 °, 0 °, and + 40 °, with the normal direction to the optically anisotropic layer being 0 °. Such measurements include KOBRA-21ADH and KOBRA-WR (manufactured by Oji Scientific Instruments), transmission ellipsometer AEP-100 (manufactured by Shimadzu Corporation), M150 and M520 (manufactured by JASCO Corporation). ), ABR10A (manufactured by UNIOPT Co., Ltd.).
(2) In the above model, the refractive index of ordinary light in each layer is no, the refractive index of extraordinary light is ne (ne is the same value in all layers, and no is the same), and the thickness of the entire multilayer body is d. And Further, based on the assumption that the tilt direction of each layer and the uniaxial optical axis direction of the layer coincide with each other, the calculation of the angular dependence of the retardation value of the optically anisotropic layer agrees with the measured value. Fitting is performed using the tilt angle θ1 on one surface of the isotropic layer and the tilt angle θ2 on the other surface as variables, and θ1 and θ2 are calculated.
Here, known values such as literature values and catalog values can be used for no and ne. If the value is unknown, it can also be measured using an Abbe refractometer. The thickness of the optically anisotropic layer can be measured by an optical interference film thickness meter, a cross-sectional photograph of a scanning electron microscope, or the like.

  Further, in this specification, unless a measurement wavelength is particularly added, it is assumed that Re and Rth are at a wavelength of 550 nm. Further, in this 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 optical axis (such as the transmission axis of the polarizer and the slow axis of the optically anisotropic layer (such as “parallel” and “orthogonal”) and the angle between the axes (eg, “0 degree”)) It is the same.

[Polarizer]
The present invention is a polarizing plate having a polarizing layer, first and second optically anisotropic layers, and a light diffusing layer, wherein the first optically anisotropic layer is a layer formed from a liquid crystal composition. Yes, Re (450) / Re (550) is 0.9 to 1.1, Re (550) of the second optical anisotropic layer is 40 to 120 nm, and Rth (550) is 40. And the scattered light profile of the goniophotometer of the light diffusing layer is poles at an azimuth angle at which the scattering intensity is maximum with respect to the light intensity at an emission angle of 0 ° (normal direction to the layer surface). The present invention relates to a polarizing plate having a scattered light intensity in the direction of 30 ° angle of 0.01 to 0.2%. In the present invention, by combining the first and second optically anisotropic layers satisfying the optical characteristics and the light diffusion layer satisfying the predetermined characteristics, the front contrast of the liquid crystal display device is increased by the light diffusion layer. There is provided a polarizing plate that contributes to an increase in viewing angle without loss and contributes to an improvement in display characteristics not only during black display but also during white to halftone display.

  In FIG. 1, the cross-sectional schematic diagram of an example of the polarizing plate of this invention is shown. The polarizing plate P in FIG. 1 has a second optically anisotropic layer 12 made of a polymer film and a first optically anisotropic layer 14 made of a liquid crystal composition on one surface of the polarizing layer 10. And having the protective layer 16 of the polarizing layer 10 and the light diffusion layer 18 on the other surface. The first and second optically anisotropic layers 14 and 12 satisfy the above-mentioned predetermined optical characteristics, compensate for birefringence generated in an oblique direction of the liquid crystal cell of the liquid crystal display device used, and widen the viewing angle. This contributes to the improvement of display characteristics during black display. The light diffusing layer 18 satisfies the above-mentioned predetermined characteristics, and contributes to wide viewing angle by light diffusing incident light, and also contributes to improving display characteristics of white to halftone display.

  The polarizing plate P in FIG. 1 is preferably used in a liquid crystal display device as a polarizing plate disposed on the display surface side. In addition, when used in a liquid crystal display device, the light diffusing layer is arranged on the outermost surface of the polarizing plate. However, the light diffusing layer has an optical anisotropy between the polarizing layer 10 and the protective layer 16. It may be disposed between the layer 12 and the polarizing layer 10, between the optically anisotropic layer 14 and the optically anisotropic layer 12, and between the liquid crystal cell and the optically anisotropic layer 14. Each layer may also serve as a light diffusion layer. Moreover, in FIG. 1, although the aspect which has arrange | positioned the protective layer for protecting a polarizing layer between a light-diffusion layer and a polarizing layer was shown, when a light-diffusion layer consists of a self-supporting polymer film etc. The light diffusion layer may be bonded to the surface of the polarizing layer as a protective layer for the polarizing layer. In addition, when the protective layer (the protective layer 16 in FIG. 1) is made of a polymer film, the light scattering layer may be a layer formed by coating on the surface of the polymer film.

  In addition, in the polarizing plate P of FIG. 1, the second optically anisotropic layer is bonded to the surface of the polarizing layer and functions as a protective layer for protecting the polarizing layer. Of course, a protective layer made of a low moisture-permeable polymer film may be disposed between the two optically anisotropic layers. However, in that aspect, the protective layer disposed between the polarizing layer and the second optical anisotropic layer does not affect the optical compensation ability of the first and second optical anisotropic layers. It is preferable to use an optically isotropic polymer film.

Hereinafter, each member of the polarizing plate of the present invention will be described in detail.
(Light diffusion layer)
The light diffusing layer used in the present invention has a polar angle at an azimuth angle at which the scattering intensity of the goniophotometer has a maximum scattering intensity with respect to the light intensity I with an emission angle of 0 ° (normal direction with respect to the layer surface). The ratio of scattered light intensity I _{30 in} the 30 ° direction, that is, I ₃₀ / I is 0.01 to 0.2%. By setting the scattered light intensity I ₃₀ in the polar angle 30 ° direction within the above range, the front contrast is not lowered, and specifically, the front contrast is maintained at 90% or more as compared with the form not using the light diffusion layer. On the other hand, it contributes to the improvement of display characteristics of wide viewing angle and white to halftone display. From the same viewpoint, I ₃₀ / I is preferably 0.02 to 0.18%, more preferably 0.03 to 0.16%, and still more preferably 0.04 to 0.14%. When I ₃₀ / I is smaller than 0.02%, the desired display characteristic improvement effect cannot be obtained because the scattered light intensity is weak. On the other hand, when I ₃₀ / I is greater than 0.18%, the front contrast cannot be maintained at 90% or more as compared with the mode in which the light diffusion layer is not used because the scattered light intensity is too strong.
The liquid crystal display device using the polarizing plate of the present invention can achieve a front contrast of 90% or more, preferably 95% or more, as compared with a mode in which a light diffusion layer is not used.

  In the present invention, it is preferable to use a light diffusion layer having an internal haze of 45% or more, preferably 50% to 90%, particularly preferably 55% to 80%. Use of a light diffusion layer having an internal haze in the above range is preferable because the scattering intensity in the direction of 30 ° polar angle can be efficiently increased while maintaining blackening in the presence of external light.

  The light diffusing layer may be a layer including a translucent resin and translucent particles having a refractive index different from the refractive index of the translucent resin. The scattered light profile and the haze value can be adjusted by the refractive index difference between the translucent particles and the translucent resin, the particle diameter of the translucent particles, and the content of the translucent particles. As the translucent particles, only translucent particles having the same particle diameter and the same material may be used, or plural kinds of translucent particles having different particle diameters and / or materials may be used. The latter is preferable in that the scattered light profile and the haze value can be adjusted.

  The refractive index of the light-transmitting particles and the refractive index of the light-transmitting resin that is the main component of the light diffusing layer (described later, when inorganic fine particles or the like are added to the light-transmitting resin for adjusting the refractive index of the layer, The difference from the optical average refractive index is preferably 0.03 to 0.30. If the difference in refractive index is less than 0.03, the difference in refractive index between the two is too small to obtain a light diffusion effect, and if the difference in refractive index is greater than 0.30, the light diffusibility is too large. The whole film turns white. The refractive index difference is more preferably 0.06 to 0.25, and even more preferably 0.09 to 0.20.

  In the present invention, the particle diameter of the translucent particles (first translucent particles) is preferably 0.5 to 3.5 μm in order to obtain an appropriate scattering property for improving the viewing angle characteristics. More preferably, it is -2.0 micrometers, and it is still more preferable that it is 0.6-1.8 micrometers. The greater the diffusion effect, the better the viewing angle characteristics. However, in order to maintain the front brightness in terms of display quality, it is also necessary to increase the transmittance as much as possible. When the particle diameter is less than 0.5 μm, the effect of diffusion is large and the viewing angle characteristics are improved, but the backscattering is large and the brightness is greatly reduced. On the other hand, when it exceeds 3.5 μm, the diffusion effect is reduced, and the improvement in viewing angle characteristics is reduced.

  Further, it is also preferable to further add translucent particles (second translucent particles) that do not have the main purpose of imparting a diffusion effect. It is used for providing irregularities on the surface of the diffusion layer to provide a reflection preventing function. The particle diameter of the second light-transmitting particles is preferably larger than the particle diameter of the first light-transmitting particles, and more preferably 2.5 μm to 10.0 μm. Thereby, suitable surface scattering can be provided. In order to achieve good display quality, it is also important to prevent reflection of external light. The lower the haze value on the surface, the less white-brown feeling is caused by external light and a clear display can be obtained.However, if the surface haze value is too low, the reflection increases, so the outermost layer has a light diffusing layer. It is also preferable to provide a low refractive index layer having a refractive index lower than the refractive index to reduce the reflectance. In order to control the surface haze value, it is preferable to provide appropriate irregularities on the surface of the resin layer with the second light-transmitting particles, but this is not restrictive. When the particle diameter is 2.5 μm or less, the thickness of the layer has to be reduced when providing desired surface irregularities, which is not preferable in terms of film hardness. On the other hand, when the particle diameter is 10 μm or more, one particle Since the weight of one is large, it is not always preferable from the viewpoint of particle sedimentation stability in the coating solution. Therefore, the particle diameter of the second light transmissive particles is preferably 2.7 to 9.0 μm, and more preferably 3.0 to 8.0 μm.

  The refractive index of the second light-transmitting particles is preferably different from the refractive index of the light-transmitting resin that is the main component of the light diffusing layer than the first light-transmitting particles.

  The surface unevenness of the light diffusing layer preferably has a surface roughness Ra of 0.5 μm or less, more preferably 0.3 μm or less, and even more preferably 0.2 μm or less. The surface roughness Ra (center line average roughness) can be measured according to JIS-B0601.

  The haze value of the light diffusion layer, particularly the internal scattering haze (internal haze) that greatly contributes to the diffusion of transmitted light has a strong correlation with the effect of improving the viewing angle characteristics. The light emitted from the backlight is diffused by the light diffusion layer provided on the surface of the polarizing plate on the viewing side, whereby the viewing angle characteristics are improved. However, since the front luminance is reduced if it is excessively diffused, the internal haze of the light diffusion layer is preferably 45% or more, more preferably 50% to 90%, and particularly preferably 55% to 80%. As a method of increasing the noise to internal scattering, increase the coating amount of translucent particles for the purpose of imparting diffusivity, if the coating amount is the same, decrease the particle diameter, increase the film thickness, and particles and resin There is a method such as increasing the difference in refractive index.

  The haze caused by surface scattering of the light diffusion layer (surface haze) is preferably 0.1 to 30%, preferably 10% or less, and particularly preferably 5% or less, from the viewpoint of achieving both reduction in reflection and reduction in white-brown feeling. preferable. If importance is attached to the reduction of white-brown feeling due to external light, it is preferably 4% or less, and more preferably 2% or less. Since reflection increases when surface haze is reduced, a low refractive index layer is provided, and it is preferable that the average value in the wavelength region from 450 nm to 650 nm of the integrated reflectance at 5 ° incidence be 3.0% or less, 2.0% or less is more preferable, and 1.0% or less is more preferable. In order to improve the display quality (improve viewing angle characteristics) in the present invention, it is necessary to adjust the internal scattering property as described above. At the same time, by setting the surface haze and / or reflectivity within a suitable range, In contrast, the contrast can be improved, and a more preferable effect can be exhibited.

  The translucent particles may be monodispersed organic fine particles or inorganic fine particles. As the particle size is not varied, the scattering property is less varied and the design of haze is facilitated. As the translucent particles, plastic beads are suitable, and those having particularly high transparency and a difference in refractive index from the translucent resin are preferable. As organic fine particles, polymethyl methacrylate beads (refractive index 1.49), acrylic-styrene copolymer beads (refractive index 1.52-1.57), melamine beads (refractive index 1.57-1.65), Polycarbonate beads (refractive index 1.57), styrene beads (refractive index 1.60), crosslinked polystyrene beads (refractive index 1.61), polyvinyl chloride beads (refractive index 1.60), benzoguanamine-melamine formaldehyde beads (refractive A rate of 1.68) is used. As the inorganic fine particles, silica beads (refractive index 1.44 to 1.46), alumina beads (refractive index 1.63), and the like are used. It is preferable to contain 5-30 mass parts of translucent particles with respect to 100 mass parts of translucent resin.

  Some translucent particles are likely to settle in the resin composition (translucent resin), and therefore an inorganic filler such as silica may be added to prevent sedimentation. As the amount of the inorganic filler added increases, it is more effective in preventing the translucent particles from settling, but adversely affects the transparency of the coating film. Therefore, preferably, an inorganic filler having a particle size of 0.5 μm or less is contained in an amount of less than about 0.1% by mass so as not to impair the transparency of the coating film with respect to the translucent resin.

  As the translucent resin, there are three types of resins that are mainly cured by ultraviolet rays and electron beams, that is, an ionizing radiation curable resin, a mixture of an ionizing radiation curable resin and a thermoplastic resin and a solvent, and a thermosetting resin. Is done. In order to impart hard coat properties, an ionizing radiation curable resin is preferably the main component. The thickness of the light diffusion layer is usually 1.5 to 30 μm, preferably 3 to 20 μm. In general, the light diffusing layer also functions as a hard coat layer. However, when the thickness of the light diffusing layer becomes thinner than 1.5 μm, the hard coat property is not sufficient, whereas from 30 μm If the thickness is too thick, this is an undesirable direction in terms of curling and brittleness. When providing the low refractive index layer, the refractive index of the translucent resin is preferably 1.46 to 2.00, more preferably 1.48 to 1.90, and further preferably 1.50. 1.80. In addition, the refractive index of translucent resin is an average value of the light-diffusion layer measured without including translucent particle | grains. When the refractive index of the light diffusing layer is too small, the antireflection property is lowered. If it is too large, the color of the reflected light becomes strong, which is not preferable. From this point, the above range is preferable. The refractive index of the light diffusing layer can be set to a desired value in terms of antireflection properties and reflected light color.

  The binder used for the translucent resin is preferably a polymer having a saturated hydrocarbon or polyether as the main chain, and more preferably a polymer having a saturated hydrocarbon as the main chain. The binder is preferably crosslinked. The polymer having a saturated hydrocarbon as the main chain is preferably obtained by a polymerization reaction of an ethylenically unsaturated monomer. In order to obtain a crosslinked binder, it is preferable to use a monomer having two or more ethylenically unsaturated groups in the molecule.

  Examples of monomers having two or more ethylenically unsaturated groups include esters of polyhydric alcohols and (meth) acrylic acid (eg, ethylene glycol di (meth) acrylate, 1,4-dichlorohexane diacrylate, penta Erythritol tetra (meth) acrylate), pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) Acrylate, dipentaerythritol hexa (meth) acrylate, 1,3,5-cyclohexanetriol trimethacrylate, polyurethane polyacrylate, polyester polyacrylate), vinylbenzene derivatives Examples are 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinyl sulfone (eg, divinyl sulfone), acrylamide (eg, methylenebisacrylamide) and methacrylamide. included. Among these, an acrylate or methacrylate monomer having at least three functional groups, and further an acrylate monomer having at least five functional groups are preferable from the viewpoint of film hardness, that is, scratch resistance. A mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate is commercially available and is particularly preferably used.

  These monomers having an ethylenically unsaturated group are prepared by applying a coating solution prepared by dissolving in a solvent together with various polymerization initiators and other additives to the surface, and then allowing the polymerization reaction to proceed by ionizing radiation or heat after coating and drying. Can be cured.

  Instead of or in addition to the monomer having two or more ethylenically unsaturated groups, a crosslinked structure may be introduced into the binder by the reaction of a crosslinkable group. Examples of the crosslinkable functional group include an isocyanate group, an epoxy group, an aziridine group, an oxazoline group, an aldehyde group, a carbonyl group, a hydrazine group, a carboxyl group, a methylol group, and an active methylene group. Vinylsulfonic acid, acid anhydride, cyanoacrylate derivative, melamine, etherified methylol, ester and urethane, and metal alkoxide such as tetramethoxysilane can also be used as a monomer for introducing a crosslinked structure. A functional group that exhibits crosslinkability as a result of the decomposition reaction, such as a block isocyanate group, may be used. That is, in the present invention, the crosslinkable functional group may not react immediately but may exhibit reactivity as a result of decomposition. The binder having these crosslinkable functional groups can form a crosslinked structure by heating after coating.

The light-transmitting resin is preferably formed from a monomer having a high refractive index and / or metal oxide ultrafine particles having a high refractive index in addition to the binder polymer. Examples of the high refractive index monomer include bis (4-methacryloylthiophenyl) sulfide, vinyl naphthalene, vinyl phenyl sulfide, 4-methacryloxyphenyl-4′-methoxyphenyl thioether and the like. Examples of the metal oxide ultrafine particles having a high refractive index include a particle diameter of 100 nm or less, preferably 50 nm or less, made of at least one oxide selected from zirconium, titanium, aluminum, indium, zinc, tin, and antimony. It is preferable to contain fine particles. The metal oxide ultrafine particles having a high refractive index are preferably oxide ultrafine particles of at least one metal selected from Al, Zr, Zn, Ti, In and Sn. Specific examples include ZrO ₂ , TiO ₂ , _{al 2 O 3, In 2 O} 3, ZnO, SnO 2, Sb 2 O 3, ITO , and the like. Among these, ZrO ₂ is particularly preferably used. The addition amount of the high refractive index monomer and the metal oxide ultrafine particles is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, based on the total mass of the translucent resin.

  Examples of the curing method of the ionizing radiation curable resin composition as described above include a normal curing method of the ionizing radiation curable resin composition, that is, a method of curing by irradiation with electron beams or ultraviolet rays.

  Examples of the photo radical polymerization initiator include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides (JP-A No. 2001-139663, etc.), 2 , 3-dialkyldione compounds, disulfide compounds, fluoroamine compounds, aromatic sulfoniums, lophine dimers, onium salts, borate salts, active esters, active halogens, inorganic complexes, coumarins and the like. These initiators may be used alone or in combination. In addition, “Latest UV Curing Technology”, Technical Information Association, 1991, p. 159, and “UV curing system” written by Kayo Kiyomi, 1989, General Technology Center, p. Various examples are also described in 65-148 and are useful in the present invention. Commercially available radical photopolymerization initiators include KAYACURE (DETX-S, BP-100, BDKM, CTX, BMS, 2-EAQ, ABQ, CPTX, EPD, ITX, QTX, manufactured by Nippon Kayaku Co., Ltd. BTC, MCA, etc.), Irgacure (127,184,500,651,819,907,369,1173,1870,2959,4265,4263, etc.) manufactured by Ciba Specialty Chemicals Co., Ltd., and Esacure (available from Sartomer) Preferred examples include KIP100F, KB1, EB3, BP, X33, KT046, KT37, KIP150, TZT) and combinations thereof.

  It is preferable to use a photoinitiator in the range of 0.1-15 mass parts with respect to 100 mass parts of polyfunctional monomers, More preferably, it is the range of 1-10 mass parts.

(Low refractive index layer)
The polarizing plate of the present invention may have a low refractive index layer having a refractive index lower than that of the light diffusion layer together with the light diffusion layer. The low refractive index layer is preferably arranged on the outer side of the light diffusion layer and adjacent to the light diffusion layer. By forming the low refractive index layer, antireflection performance is obtained, reflection of external light is suppressed, and contrast in a bright room environment can be further improved.

  The refractive index of the low refractive index layer is preferably 1.20 to 1.50, more preferably 1.25 to 1.45, and still more preferably 1.30 to 1.40. . There are no particular restrictions on the material used to form the low refractive index layer. For example, it is formed by curing a curable composition containing a fluorine-containing compound as a main component or a curable composition containing a monomer having a plurality of binding groups in the molecule and particles having a low refractive index. Can do. More specifically, examples of preferable cured product compositions include (1) a composition containing a fluorine-containing polymer having a crosslinkable or polymerizable functional group, and (2) hydrolytic condensation of a fluorine-containing organosilane material. And (3) a composition containing a monomer having two or more ethylenically unsaturated groups and inorganic fine particles having a hollow structure.

(Transparent substrate)
The polarizing plate of the present invention may have a transparent substrate that supports the light diffusion layer. For example, the light diffusion layer can be formed by applying a light diffusion layer forming coating solution on the surface of the transparent substrate. A transparent polymer film, a transparent glass plate, etc. can be used for a transparent substrate. As the transparent polymer film, a cellulose ester film (eg, triacetyl cellulose film, diacetyl cellulose film, typically TAC-TD80U, TD80UF, etc. manufactured by Fuji Film), polyamide film, polycarbonate film, polyester film (eg, polyethylene terephthalate) Film, polyethylene naphthalate film), polystyrene film, polyolefin film, norbornene resin film (Arton: trade name, manufactured by JSR), amorphous polyolefin film (ZEONEX: trade name, manufactured by Nippon Zeon), and the like. . Among these, a triacetyl cellulose film, a polyethylene terephthalate film, and a polyethylene naphthalate film are preferable, and a triacetyl cellulose film is particularly preferable. The thickness of the transparent substrate is preferably 20 to 200 μm, more preferably 30 to 100 μm, still more preferably 35 to 90 μm, and even more preferably 40 to 80 μm, from the viewpoint of thinning needs and handling properties (conveyability).
In addition, when a transparent substrate consists of a polymer film, in this invention, a transparent substrate can also be utilized as a protective film of the linearly polarizing film which is a polarizing layer. Specifically, a light diffusion film having a polymer film and a light diffusion layer thereon is bonded to the back surface of the polymer film (the surface on which the light diffusion layer is not formed) and the surface of the linear polarizing film. The polymer film may be used as a protective film. Moreover, depending on arrangement | positioning of the said transparent substrate, the polymer film which satisfies the predetermined optical characteristic which is a 2nd optically anisotropic layer may be sufficient.

  Moreover, in this invention, you may utilize an anisotropic light-scattering film as a light-diffusion layer. Anisotropic light scattering film has a different diffusion angle depending on the azimuth angle, and by using this, it is possible to suppress black floating in perspective and improve contrast, and it is easy to cause insufficient compensation in the downward direction, etc. The angle that does not cause gradation inversion in the direction can be enlarged. Moreover, coloring based on a birefringent layer can also be reduced. The scattering anisotropic film can be obtained, for example, as a speckle gram composed of a film on which rusty (trade name, manufactured by Sumitomo Chemical Co., Ltd.) or speckle is recorded, and also contains a transparent region containing minute regions having different birefringence characteristics. It can be obtained as a film made of a light-sensitive resin.

Hereinafter, embodiments of typical anisotropic light scattering films will be described. Particularly preferred is the first embodiment.
(First embodiment of anisotropic light scattering film)
In the present invention, the first aspect of the anisotropic light scattering film that can be used as a light diffusion layer is a film in which portions having different refractive indexes are distributed in an irregular shape and thickness inside the film. For example, a film having a portion where the refractive index is formed in a light and shade pattern (a portion having a different refractive index) and the portion is distributed in a layered manner inclined with respect to the thickness direction of the film is suitable. Used for. The anisotropic light scattering film of this example causes light scattering for light incident at an angle along the tilt direction, and is merely a transparent film for light incident at an angle perpendicular to the tilt direction. Therefore, the light scattering property has an incident angle selectivity. The refractive index distribution may be uniform in the direction in which the portions having different refractive indexes are inclined in a layered manner, and the refractive index distribution is not uniform in the direction in which the refractive index is inclined in a layered manner. It may be a rule. In addition, the portions having different refractive indexes are irregular in size, and the respective shapes are vertically long (or horizontally long), and the light scattering characteristics by the respective portions are horizontally long (or vertically long). Thus, it is preferable that the light scattering characteristics have anisotropy. Such an anisotropic light scattering film is disclosed in JP-A No. 2000-171619.

  As described above, the light incident on the anisotropic light scattering film of the first aspect is transmitted as scattered light depending on the incident angle. The incident light to the anisotropic light scattering film is emitted as scattered light, and the maximum scattering angle θ between the transmitted light indicating the maximum scattering direction of the scattered light and the normal direction of the anisotropic light scattering film is 20 ° to A range of 50 ° is preferable.

  The material used for the anisotropic light scattering film of the first aspect is appropriately selected in the range of refractive index difference of 0.001 to 0.2, and the film thickness is also in the range of 1000 μm to 1 μm depending on the refractive index difference. Will be selected accordingly. The sizes of the portions having different refractive indexes are random and not regular in order to cause light scattering, but in order to have the necessary scattering properties, the average size is in the range of 0.1 μm to 300 μm in diameter. Is appropriately selected.

  The anisotropic light scattering film of the first aspect can be produced using, for example, a random mask pattern. Specifically, ultraviolet light emitted from the UV light source is converted into parallel light by a collimating optical system, and the mask original is irradiated. The mask original plate is composed of a glass substrate and a random chromium pattern. A photosensitive material is placed in close contact with the surface opposite to the UV irradiation side of the mask original, and the pattern of the mask original is exposed to the photosensitive material. At this time, since the UV parallel light and the mask original are inclined by a predetermined angle α, the pattern exposure is performed at a predetermined angle in the photosensitive material. This angle corresponds to the inclination angle of the portion having a different refractive index in the light scattering film (that is, the maximum scattering angle θ depending on the incident angle). The photosensitive material used is a photosensitive material that can be recorded in a form in which the refractive index changes between the exposed and unexposed portions of UV light, and has a higher resolving power than the shading pattern to be recorded, in the direction of its thickness. Is a material capable of recording a pattern. As such a recording material, a volume hologram photosensitive material can be used, such as a silver salt photosensitive material 8E56 dry plate manufactured by Agfa, hologram photosensitive material HRF film or dichromated gelatin manufactured by DuPont, and DMP- manufactured by Polaroid. 128 recording materials. As the mask master having a random pattern, a black and white pattern data produced by random number calculation using a computer and etched as a metal chromium pattern on a glass substrate by a so-called photolithography technique can be used. Of course, the method for producing the mask original plate is not limited to the above-described method, and a similar mask can be produced even if produced by a photographic technique using a squirrel plate.

  The anisotropic light scattering film of the first aspect can be produced using a speckle pattern. Specifically, the ground glass is irradiated with laser light emitted from a laser light source. A photosensitive material is disposed on a surface opposite to the laser irradiation side of the frosted glass, and a speckle pattern, which is a complicated interference pattern generated by laser light transmitted and scattered by the frosted glass, is exposed to the photosensitive material. At this time, since the ground glass and the photosensitive material are inclined at a predetermined angle α, the speckle pattern is exposed at a predetermined angle in the photosensitive material. This angle corresponds to the inclination of the portion having a different refractive index in the light scattering film (that is, the maximum scattering angle θ depending on the incident angle). The laser light source used for recording can be appropriately selected and used according to the sensitivity of the photosensitive material among the wavelengths of 514.5 nm, 488 nm, and 457.9 nm of an argon ion laser. Other than argon ion lasers, any laser light source having good coherency can be used. For example, a helium neon laser or a krypton ion laser can be used.

(Second embodiment of anisotropic light scattering film)
In the present invention, the second aspect of the anisotropic light-scattering film that can be used as the light diffusion layer is that one or more of the light-transmitting polymers and the light-transmitting polymer for forming the microregions are not the same. Mix one or more materials with different refractive characteristics, for example, suitable materials with excellent transparency such as polymers and liquid crystals, and disperse the materials in a light-transmitting polymer in a minute region. After forming the film to contain, it is a film produced by forming the area | region from which birefringence differs by the appropriate orientation process by an extending | stretching process etc. as needed. In the anisotropic light-scattering film of the second aspect, the above condition is satisfied by adjusting the refractive index difference between the light-transmitting polymer and the microregion dispersed therein, and the birefringence distribution formed by the alignment treatment. An anisotropic light scattering film exhibiting a satisfactory scattering profile can be produced.

  Any translucent polymer can be used as long as it is transparent. For example, polyesters; polystyrenes such as polystyrene and acrylonitrile / styrene copolymers (AS polymers); polyolefins such as polyethylene, polypropylene, ethylene / propylene copolymers, polyolefins having a cyclo or norbornene structure; polycarbonates; Poly (meth) acryls; Polyvinyl chlorides; Cellulose acylates; Polyamides; Polyimides; Polysulfones; Polyether sulfones; Polyether ether ketones; Polyphenylene sulfides; Polyvinyl alcohols; Polyvinylidene chlorides; Butyrals; polyarylates; polyoxymethylenes; silicone resins; polyurethanes; blends of two or more of them; Le-based or urethane-based, polymers of thermosetting or UV-curable urethane acrylic or epoxy or silicone, and the like.

  The translucent polymer may be a material that hardly causes orientation birefringence due to molding distortion or the like (isotropic polymer), or may be a material that is easily generated (anisotropic polymer). It is preferable to use a polymer having excellent transparency in the visible light region.

(First optical anisotropic layer)
The polarizing plate of the present invention has a first optical anisotropy in which a ratio Re (450) / Re (550) of Re (450) at a wavelength of 450 nm to Re (550) at a wavelength of 550 nm is 0.9 to 1.1. It has a sex layer. The Re (450) / Re (550) of the first optically anisotropic layer is more preferably 1 to 1.1.
The preferred range of Re (550) of the first optically anisotropic layer varies depending on the mode of the liquid crystal display device used, but in the mode of the polarizing plate used in the TN mode liquid crystal display device, Re (550) of the first optically anisotropic layer is preferably 20 to 55 nm, and more preferably 22 to 45 nm.

  The first optically anisotropic layer is a layer formed from a liquid crystal composition. The liquid crystal composition used for forming the first optically anisotropic layer is preferably a liquid crystal composition capable of forming a nematic phase and a smectic phase. Liquid crystal compounds are generally classified into rod-like and disc-like liquid crystal compounds based on their molecular shapes, but any shape of liquid crystal compounds may be used in the present invention. In order to satisfy the characteristics required for the first optically anisotropic layer, the liquid crystal compound to be used is a compound having a low birefringence wavelength dispersion when the birefringence is expressed by the orientation of the molecule. Is preferred.

  When a rod-like liquid crystal compound is used, it is preferable to use two or more rod-like liquid crystal compounds in order to satisfy the characteristics required for the first optically anisotropic layer. Preferable combinations include a combination of at least one rod-like liquid crystal represented by the following formula (I) and at least one rod-like liquid crystal represented by the following formula (II).

In the formula, A and B each represent an aromatic or aliphatic hydrocarbon ring or a heterocyclic group; R ^{1 to} R ⁴ are each substituted or unsubstituted C ^{1 to} 12 (preferably C 3 to 7). Or an alkoxy group, an acyloxy group, an alkoxycarbonyl group or an alkoxycarbonyloxy group containing a C1-12 (preferably C3-7) alkylene chain; R ^a , R ^b and R ^c each represent ^a substituent. X; y and z each represents an integer of 1 to 4;

In the above formula, the alkyl chain contained in R ^{1 to} R ⁴ may be either linear or branched. More preferably, it is linear. In order to cure the composition, R ^{1 to} R ⁴ preferably have a polymerizable group at the end, and examples of the polymerizable group include an acryloyl group, a methacryloyl group, and an epoxy group. included.

In the above formula (I), x and z are preferably 0 and y is preferably 1, and one R ^b is a substituent at the meta position or the ortho position with respect to the oxycarbonyl group or acyloxy group. Is preferred. R ^b is preferably a C1-12 alkyl group (for example, a methyl group), a halogen atom (for example, a fluorine atom), or the like.

  In the formula (II), each of A and B is preferably a phenylene group or a cyclohexylene group, and both A and B are phenylene groups, or one is a cyclohexylene group and the other is phenylene. A group is preferred.

  Specific examples of the compound represented by the general formula (I) and specific examples of the compound represented by the general formula (II) are shown below, but are not limited to the following specific examples.

  There is no restriction | limiting in particular about the ratio of the compound of the said general formula (I) and (II). In order to satisfy the above characteristics, an equal amount may be used, or one of them may be used as a main component and the other as a subcomponent.

  As the discotic liquid crystal compound, in order to satisfy the characteristics required for the first optically anisotropic layer, it is preferable to use a compound represented by the following general formula (DI). These are preferable because they exhibit high birefringence. Among the compounds represented by the following general formula (DI), compounds showing discotic liquid crystallinity are preferable, and compounds showing a discotic nematic phase are particularly preferable.

In the general formula (DI), Y ¹¹ , Y ¹² and Y ¹³ each independently represent a methine or nitrogen atom. L ¹ , L ² and L ³ each independently represents a single bond or a divalent linking group. H ^1, the H ^2, H ³ are each independently, represent the general formula (DI-A) or the following formula (DI-B). R ¹ , R ² and R ³ each independently represents the following general formula (DI-R).

In the general formula (DI), Y ¹¹ , Y ¹² and Y ¹³ each independently represent a methine or nitrogen atom. When Y ¹¹ , Y ¹² and Y ¹³ are each methine, the hydrogen atom of methine may be substituted with a substituent. Examples of the substituent that methine may have include, for example, alkyl group, alkoxy group, aryloxy group, acyl group, alkoxycarbonyl group, acyloxy group, acylamino group, alkoxycarbonylamino group, alkylthio group, arylthio group, halogen Mention may be made of atoms and cyano groups. Among these, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an acyloxy group, a halogen atom, and a cyano group are more preferable, and the number of carbon atoms (referred to as the number of carbon atoms that the substituent has, hereinafter referred to as a discotic liquid crystal compound). The same for the substituents which may be present) 1-12 alkyl groups, C1-12 alkoxy groups, C2-12 alkoxycarbonyl groups, C2-12 acyloxy groups, halogen atoms and cyano groups Is more preferable.

Y ¹¹ , Y ¹² and Y ¹³ are preferably all methine, and methine is preferably unsubstituted.

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

The divalent cyclic group represented by L ¹ , L ² and L ³ is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, More preferably, it is a 6-membered ring. The ring 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. Examples of the aromatic ring include a benzene ring and a naphthalene ring. Examples of the aliphatic ring include a cyclohexane ring. Examples of the heterocyclic ring include a pyridine ring and a pyrimidine ring. The cyclic group preferably contains an aromatic ring and a heterocyclic ring.

  Of the divalent cyclic group, 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. 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.

The divalent cyclic group represented by L ¹ , L ² or 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 carbon atom. An alkyl group substituted with -16 halogen atoms, an alkoxy group having 1 to 16 carbon atoms, an acyl group having 2 to 16 carbon atoms, an alkylthio group having 1 to 16 carbon atoms, and 2 carbon atoms -16 acyloxy groups, alkoxycarbonyl groups having 2 to 16 carbon atoms, carbamoyl groups, carbamoyl groups substituted with alkyl groups having 2 to 16 carbon atoms, and acylamino groups having 2 to 16 carbon atoms It is.

L ¹ , L ² and L ³ include a single bond, * —O—CO—, * —CO—O—, * —CH═CH—, * —C≡C—, * -2 valent cyclic group— * -O-CO-2 valent cyclic group-, * -CO-O-2 valent cyclic group-, * -CH = CH-2 valent cyclic group-, * -C≡C-2 valent cyclic. Group-, * -2 valent cyclic group-O-CO-, * -2 valent cyclic group-CO-O-, * -2 valent cyclic group-CH = CH-, or * -2 valent cyclic group- C≡C— is preferred. In particular, a single bond, * -CH = CH-, * -C≡C-, * -CH = CH-2 valent cyclic group- or * -C≡C-2 valent cyclic group- is more preferable, Is more preferable. Here, * represents a position bonded to a 6-membered ring including Y ¹¹ , Y ¹² and Y ¹³ in the general formula (I).

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 formula (DI-A), YA ¹ and YA ² each independently represent a methine group or a nitrogen atom. At least one of YA ¹ and YA ² is preferably a nitrogen atom, and more preferably both are nitrogen atoms. XA represents an oxygen atom, a sulfur atom, methylene or imino. XA is preferably an oxygen atom. * Represents a position where L ^{1 to} L ³ are bonded, and ** represents a position where R ^{1 to} R ³ are bonded.

In the general formula (DI-B), YB ¹ and YB ² each independently represent a methine or a nitrogen atom. At least one of YB ¹ and YB ² is preferably a nitrogen atom, and more preferably both are nitrogen atoms. XB represents an oxygen atom, a sulfur atom, methylene or imino. XB is preferably an oxygen atom. * Represents a position where L ^{1 to} L ³ are bonded, and ** represents a position where R ^{1 to} R ³ are bonded.

R ¹ , R ² and R ³ each independently represents the following general formula (DI-R).
General formula (DI-R)
*-(-L ²¹ -F ¹ ) _n1 -L ²² -L ²³ -Q ¹

In the general formula (DI-R), * represents a position bonded to H ¹ , H ² or H ³ in the general formula (DI). F ¹ represents a divalent linking group having at least one cyclic structure. L ²¹ represents 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 preferable. R ⁷ is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom, more preferably an alkyl group having 1 to 4 carbon atoms or a hydrogen atom, and a methyl group, ethyl group or hydrogen atom. Is more preferable, and a hydrogen atom is particularly preferable.

L ²¹ represents a single bond, ** — O—CO—, ** — CO—O—, ** — CH═CH— or ** — C≡C— (where ** represents a general formula (DI-R Represents the left side of L ^{21 in} the formula (A). A single bond is particularly preferable.

F ¹ in the general formula (DI-R) represents a divalent cyclic linking group having at least one cyclic structure. The cyclic structure is preferably a 5-membered ring, a 6-membered ring or a 7-membered ring, more preferably a 5-membered ring or a 6-membered ring, and even more preferably a 6-membered ring. The cyclic structure 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. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring. Examples of the aliphatic ring include a cyclohexane ring. Examples of the heterocyclic ring include a pyridine ring and a pyrimidine ring.

Of F ¹ , those having a benzene ring are preferably a 1,4-phenylene group or a 1,3-phenylene group. Those having a naphthalene ring include naphthalene-1,4-diyl group, naphthalene-1,5-diyl group, naphthalene-1,6-diyl group, naphthalene-2,5-diyl group, naphthalene-2,6- A diylnaphthalene-2,7-diyl group is preferred. Those having a cyclohexane ring are preferably 1,4-cyclohexylene groups. Pyridine-2,5-diyl groups are preferred as those having a pyridine ring. As a compound having a pyrimidine ring, a pyrimidine-2,5-diyl group is preferable. F ¹ is particularly preferably a 1,4-phenylene group, a 1,3-phenylenenaphthalene-2,6-diyl group, and a 1,4-cyclohexylene group.

F ¹ 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 1 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, carbamoyl groups substituted with alkyl groups having 2 to 16 carbon atoms, and 2 to 2 carbon atoms 16 acylamino groups are included. The substituent 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, and a halogen atom or an alkyl having 1 to 4 carbon atoms. Group, an alkyl group substituted with a halogen atom 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 an integer of 0 to 4. As n1, the integer of 1-3 is preferable and 1 or 2 is preferable. When n1 is 0, L ²² in the formula (DI-R) is directly bonded to H ^{1 to} H ³ in the general formula (D1). When n1 is 2 or more, each -L ²¹ -F ¹ may be the same or different.

L ²² represents —O—, —O—CO—, —CO—O—, —O—CO—O—, —S—, —NH—, —SO ₂ —, —CH ₂ —, —CH═CH. -Or -C≡C- is represented. Preferred is —O—, —O—CO—, —CO—O—, —O—CO—O—, —CH ₂ —, —CH═CH— or —C≡C—, and more preferred. —O—, —O—CO—, —CO—O—, —O—CO—O— or —CH ₂ —.
Here, when it is a group containing a hydrogen atom among the above, the hydrogen atom may be replaced by a substituent. Examples of other substituents 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 atom having 1 to 6 carbon atoms, and 1 to 6 carbon atoms. Alkoxy group having 2 to 6 carbon atoms, alkylthio group having 1 to 6 carbon atoms, acyloxy group having 2 to 6 carbon atoms, alkoxycarbonyl group having 2 to 6 carbon atoms, carbamoyl group, carbon atom A carbamoyl group substituted with an alkyl group having 2 to 6 carbon atoms and an acylamino group having 2 to 6 carbon atoms are included. In particular, a halogen atom and an alkyl group having 1 to 6 carbon atoms are preferable.

L ²³ represents —O—, —S—, —C (═O) —, —SO ₂ —, —NH—, —CH ₂ —, —CH═CH—, —C≡C—, and two of these. A divalent linking group selected from the groups formed by linking the above. Here, the hydrogen atoms of —NH—, —CH ₂ —, and —CH═CH— may be replaced with other substituents. Examples of other substituents 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 atom having 1 to 6 carbon atoms, and 1 to 6 carbon atoms. Alkoxy group having 2 to 6 carbon atoms, alkylthio group having 1 to 6 carbon atoms, acyloxy group having 2 to 6 carbon atoms, alkoxycarbonyl group having 2 to 6 carbon atoms, carbamoyl group, carbon atom A carbamoyl group substituted with an alkyl group having 2 to 6 carbon atoms and an acylamino group having 2 to 6 carbon atoms are included. In particular, a halogen atom and an alkyl group having 1 to 6 carbon atoms are preferable. By being substituted with these substituents, the solubility of the compound represented by the general formula (DI) in the solvent can be improved, and the composition of the present invention can be easily prepared as a coating solution. .

L ²³ is preferably a linking group 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 is -CH ₂ - preferably contains 1 to 16 a, -CH ₂ - and more preferably a containing 2-12.

Q ¹ is a polymerizable group or a hydrogen atom. When the compound represented by the general formula (DI) is used for production of an optical film or the like that requires that the phase difference does not change due to heat like an optical compensation film, Q ¹ represents a polymerizable group. It is preferable that The polymerization reaction is preferably addition polymerization (including ring-opening polymerization) or condensation polymerization. In other words, the polymerizable group is preferably a functional group capable of addition polymerization reaction or condensation polymerization reaction. Examples of polymerizable groups are shown below.

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

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

  In formula (M-3) and formula (M-4), R represents a hydrogen atom or an alkyl group. R is preferably a hydrogen atom or a methyl group. Among the above (M-1) to (M-6), (M-1) or (M-2) is preferable, and (M-1) is more preferable.

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

  In the present invention, it is also preferable to use a compound represented by the following general formula (DII) or a compound represented by the following general formula (DIII) as the discotic liquid crystal compound.

（一般式（ＤＩＩ）中、Ｙ³¹、Ｙ³²、Ｙ³³はそれぞれ独立にメチン又は窒素原子を表す。Ｒ³¹、Ｒ³²、Ｒ³³はそれぞれ独立に下記一般式（ＤＩＩ−Ｒ）で表される。）

(In the general formula (DII), Y ³¹ , Y ³² and Y ³³ each independently represent a methine or nitrogen atom. R ³¹ , R ³² and R ³³ are each independently represented by the following general formula (DII-R). )

In the general formula (DII), Y ³¹ , Y ³² and Y ³³ each independently represent a methine or a nitrogen atom. Y ³¹ , Y ³² and Y ³³ are respectively the same as the definitions of Y ¹¹ , Y ¹² and Y ^{13 in} the general formula (DI), and preferred ranges are also synonymous.

R ³¹ , R ³² and R ³³ are each independently represented by the general formula (DII-R).

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

In General Formula (DII-R), F ² represents a divalent cyclic linking group having a 6-membered cyclic structure. The 6-membered ring contained in F ² may be a condensed ring. However, it is more preferably a monocycle than a condensed ring. The 6-membered ring contained in F ² may be any of an aromatic ring, an aliphatic ring, and a heterocyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring. Examples of the aliphatic ring include a cyclohexane ring. Examples of the heterocyclic ring include a pyridine ring and a pyrimidine ring.

  Among the divalent cyclic groups, the cyclic group having a benzene ring is preferably a 1,4-phenylene group or a 1,3-phenylene group. As a cyclic group having a naphthalene ring, naphthalene-1,4-diyl group, naphthalene-1,5-diyl group, naphthalene-1,6-diyl group, naphthalene-2,5-diyl group, naphthalene-2,6 -Diyl groups and naphthalene-2,7-diyl groups are preferred. 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. As the divalent cyclic group, 1,4-phenylene group, 1,3-phenylene group, naphthalene-2,6-diyl group and 1,4-cyclohexylene group are particularly preferable.

F 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 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, carbamoyl groups substituted with alkyl groups having 2 to 16 carbon atoms, and 2 to 2 carbon atoms 16 acylamino groups are included. As the substituent of the divalent cyclic group, a halogen atom, a cyano group, an alkyl group having 1 to 6 carbon atoms, and an alkyl group substituted with a halogen atom having 1 to 6 carbon atoms are preferable. An alkyl group having 1 to 4 carbon atoms and an alkyl group substituted with a halogen atom having 1 to 4 carbon atoms are preferable, and a halogen atom, an alkyl group having 1 to 3 carbon atoms, and a trifluoromethyl group are more preferable.

n3 represents an integer of 1 to 3. n3 is preferably 1 or 2. When n3 is 2 or more, each F ² may be the same or different.

L ³¹ is —O—, —O—CO—, —CO—O—, —O—CO—O—, —S—, —NH—, —SO ₂ —, —CH ₂ —, —CH═CH—. , -C≡C-, and when the above group is a group containing a hydrogen atom, the hydrogen atom may be replaced by a substituent. A preferred range for L ³¹ is the same as L ^{22 in} formula (DI-R).

L ³² represents —O—, —S—, —C (═O) —, —SO ₂ —, —NH—, —CH ₂ —, —CH═CH—, —C≡C—, or two or more thereof. Represents a divalent linking group selected from the group formed by linking and when the above group is a group containing a hydrogen atom, the hydrogen atom may be replaced by a substituent. A preferred range for L ³² is the same as L ^{23 in} formula (DI-R).

Q ³ represents a polymerizable group or a hydrogen atom, and a preferred range is the same as Q ¹ in the general formula (DI-R).

  Next, the detail of the compound represented by general formula (DIII) is described.

In the general formula (DIII), Y ⁴¹ , Y ⁴² and Y ⁴³ each independently represents a methine or nitrogen atom. When Y ⁴¹ , Y ⁴² and Y ⁴³ are each methine, the hydrogen atom of the methine is a substituent. May be substituted. Examples of the substituent that 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, a halogen atom, and A cyano group can be mentioned as a preferred example. 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, Particularly preferred are an alkoxycarbonyl group having 2 to 12 carbon atoms, an acyloxy group having 2 to 12 carbon atoms, a halogen atom and a cyano group.
Y ⁴¹ , Y ⁴² and Y ⁴³ are all preferably methine, and methine is more preferably unsubstituted.

R ⁴¹ , R ⁴² and R ⁴³ each independently represent the following general formula (DIII-A), the following general formula (DIII-B), or the following general formula (DIII-C).
In the case of producing a retardation plate or the like having a small wavelength dispersion, R ⁴¹ , R ⁴² and R ⁴³ are each preferably represented by general formula (DIII-A) or general formula (DIII-C), What is represented by general formula (DIII-A) is more preferable.

In the general formula (DIII-A), A ⁴¹ , A ⁴² , A ⁴³ , A ⁴⁴ , A ⁴⁵ and A ⁴⁶ each independently represents a methine or nitrogen atom. At least one of A ⁴¹ and A ⁴² is preferably a nitrogen atom, and more preferably both are nitrogen atoms. At least three of A ⁴³ , A ⁴⁴ , A ⁴⁵ and A ⁴⁶ are preferably methine, more preferably methine. When A ⁴³ , A ⁴⁴ , A ⁴⁵ and A ⁴⁶ are each methine, the hydrogen atom of methine may be substituted with a substituent. Examples of substituents possessed by methine include halogen atoms (fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, nitro group, alkyl group having 1 to 16 carbon atoms, and alkenyl group having 2 to 16 carbon atoms. Group, an alkynyl group having 2 to 16 carbon 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, a carbon atom An alkylthio group having 1 to 16 carbon atoms, an acyloxy group having 2 to 16 carbon atoms, an alkoxycarbonyl group having 2 to 16 carbon atoms, a carbamoyl group, a carbamoyl group and a carbon atom substituted with an alkyl group having 2 to 16 carbon atoms The acylamino group of several 2-16 is contained. 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 more preferable.
X ⁴¹ represents an oxygen atom, a sulfur atom, methylene or imino, and preferably an oxygen atom.

In the general formula (DIII-B), A ⁵¹ , A ⁵² , A ⁵³ , A ⁵⁴ , A ⁵⁵ and A ⁵⁶ each independently represents a methine or nitrogen atom. At least one of A ⁵¹ and A ⁵² is preferably a nitrogen atom, and more preferably both are nitrogen atoms. At least three of A ⁵³ , A ⁵⁴ , A ⁵⁵ and A ⁵⁶ are preferably methine, more preferably methine. When A ⁵³ , A ⁵⁴ , A ⁵⁵ and A ⁵⁶ are each methine, the hydrogen atom of methine may be substituted with a substituent. Examples of the substituent that methine may have include a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, nitro group, alkyl group having 1 to 16 carbon atoms, and 2 to 2 carbon atoms. 16 alkenyl groups, alkynyl groups having 2 to 16 carbon atoms, alkyl groups substituted with halogen having 1 to 16 carbon atoms, alkoxy groups having 1 to 16 carbon atoms, acyl groups having 2 to 16 carbon atoms, An alkylthio group having 1 to 16 carbon atoms, an acyloxy group having 2 to 16 carbon atoms, 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 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 atom having 1 to 6 carbon atoms are preferable, and a halogen atom and an alkyl group having 1 to 4 carbon atoms. An alkyl group substituted with a halogen atom having 1 to 4 carbon atoms is more preferable, and a halogen atom, an alkyl group having 1 to 3 carbon atoms, or a trifluoromethyl group is more preferable.
X ⁵² represents an oxygen atom, a sulfur atom, methylene or imino, and preferably an oxygen atom.

In the general formula (DIII-C), A ⁶¹ , A ⁶² , A ⁶³ , A ⁶⁴ , A ⁶⁵ and A ⁶⁶ each independently represents a methine or nitrogen atom. At least one of A ⁶¹ and A ⁶² is preferably a nitrogen atom, and more preferably both are nitrogen atoms. At least three of A ⁶³ , A ⁶⁴ , A ⁶⁵ and A ⁶⁶ are preferably methine, more preferably methine. When A ⁶³ , A ⁶⁴ , A ⁶⁵ and A ³⁶ are each methine, the hydrogen atom of the methine may be substituted with a substituent. Examples of the substituent that methine may have include a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, nitro group, alkyl group having 1 to 16 carbon atoms, carbon atom number An alkenyl group having 2 to 16 carbon atoms, an alkynyl group having 2 to 16 carbon atoms, an alkyl group substituted with a halogen having 1 to 16 carbon atoms, an alkoxy group having 1 to 16 carbon atoms, and an acyl having 2 to 16 carbon atoms Group, an alkylthio group having 1 to 16 carbon atoms, an acyloxy group having 2 to 16 carbon atoms, an alkoxycarbonyl group having 2 to 16 carbon atoms, a carbamoyl group, and a carbamoyl substituted with an alkyl group having 2 to 16 carbon atoms Groups and acylamino groups of 2 to 16 carbon atoms are 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 more preferable.
X ⁶³ represents an oxygen atom, a sulfur atom, methylene or imino, preferably an oxygen atom.

L ^{41 in} the general formula (DIII-A), L ^{51 in} the general formula (DIII-B), and L ⁶¹ in the general formula (DIII-C) are each independently —O— or —O—CO—. , —CO—O—, —O—CO—O—, —S—, —NH—, —SO ₂ —, —CH ₂ —, —CH═CH— or —C≡C—. Preferably, -O -, - O-CO -, - CO-O -, - O-CO-O -, - CH 2 -, - CH = CH -, - it is C≡C-, more preferably, —O—, —O—CO—, —CO—O—, —O—CO—O— or —CH ₂ —. When the above group is a group containing a hydrogen atom, the hydrogen atom may be replaced 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 atom 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 ^{42 in} the general formula (DIII-A), L ^{52 in} the general formula (DIII-B), and L ⁶² in the general formula (DIII-C) are each independently —O—, —S—, — Selected from C (═O) —, —SO ₂ —, —NH—, —CH ₂ —, —CH═CH— and —C≡C— and groups formed by linking two or more 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 atom 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 ⁴² , L ⁵² and L ⁶² each independently connect —O—, —C (═O) —, —CH ₂ —, —CH═CH— and —C≡C— and two or more thereof. It is preferable that it is a bivalent coupling group selected from the group formed in this way. L ⁴² , L ⁵² and L ⁶² each independently preferably contain 1 to 20 carbon atoms, more preferably 2 to 14 carbon atoms. Furthermore, L ⁴² , L ⁵² and L ⁶² each independently preferably contain 1 to 16 —CH ₂ —, and more preferably ₂ to 12 —CH ₂ —.

Formula (DIII-A) in Q ^4, the general formula (DIII-B) Q ⁵ and formula in (DIII-C) Q ⁶ in each independently represents a polymerizable group or a hydrogen atom . These preferable ranges are the same as Q < ¹ > in general formula (DI-R).

  Although the specific example of a compound represented by general formula (DI), general formula (DII), and general formula (DIII) below is shown, this invention is not limited to these.

  The compounds represented by formula (DIII) are shown below.

  The compounds represented by the above general formula (DI), general formula (DII) and general formula (DIII) can be synthesized by applying known methods.

  In the present invention, as the discotic liquid crystal compound, only one of the compounds represented by the above general formula (DI), general formula (DII) and general formula (DIII) may be used, or two or more kinds thereof may be used. May be.

  In addition, preferable examples of the discotic liquid crystal compound include compounds described in JP-A-2005-301206.

  In order for the first optical anisotropic layer to satisfy 0.9 ≦ Re (450) / Re (550) ≦ 1.1, the refractive index of extraordinary light is included in the first optical anisotropic layer. The absorption transition that mainly contributes to the refractive index of ordinary light has a longer wavelength than the absorption transition that mainly contributes to the normal light, and the absorption transition direction that mainly contributes to ordinary light is the major axis direction of the molecule (light It is preferable that a molecule inclined by 70 to 90 ° with respect to the axial direction) is present. In order for the transition direction of absorption mainly contributing to ordinary light to tilt 70 to 90 ° with respect to the long axis direction (optical axis direction) of the molecule, a 6-membered ring and an odd-membered ring (3-membered ring, 5-membered ring, It preferably has a partial structure in which a 7-membered ring, 9-membered ring, etc.) are condensed. Specifically, a liquid crystal compound represented by the following general formula (I) or a general formula (II) described later can be given. These liquid crystalline compounds may be contained in the optically anisotropic layer as additives as a monomolecular structure, and when these liquid crystalline compounds have a polymerizable group, from these liquid crystalline compounds You may contain in the said optically anisotropic layer in the state of the polymer | macromolecule which has a repeating unit induced | guided | derived.

In the formula, L ¹ and L ² each independently represent a single bond or a divalent linking group. A ¹ and A ² each independently represent a group selected from the group consisting of —O—, —NR— (R represents a hydrogen atom or a substituent), —S—, and —CO—. R ¹ , R ² , and R ³ each independently represent a substituent. X is 14th
Represents a non-metallic atom of Group -16 (however, a hydrogen atom or a substituent may be bonded to X). n represents an integer of 0 to 2.

  In particular, a liquid crystal compound represented by the following general formula (I ′) is preferable.

In general formula (I ′), L ¹ and L ² each independently represents a single bond or a divalent linking group. A ¹ and A ² each independently represent a group selected from the group consisting of —O—, —NR— (R represents a hydrogen atom or a substituent), —S—, and —CO—. R ¹ , R ² , R ³ , R ⁴ and R ⁵ each independently represents a substituent. n represents an integer of 0 to 2.

In the general formula (I) or (I ′), the divalent linking group represented by L ¹ and L ² preferably includes the following examples.

  More preferred are -O-, -COO-, and -OCO-.

In general formula (I) or (I ′), R ¹ is a substituent, and when a plurality of R ¹ are present, they may be the same or different and may form a ring. The following can be applied as examples of the substituent.

  A halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), an alkyl group (preferably an alkyl group having 1 to 30 carbon atoms, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a tert- Butyl group, n-octyl group, 2-ethylhexyl group), cycloalkyl group (preferably a substituted or unsubstituted cycloalkyl group having 3 to 30 carbon atoms, such as cyclohexyl group, cyclopentyl group, 4-n-dodecylcyclohexyl) Group), a bicycloalkyl group (preferably a substituted or unsubstituted bicycloalkyl group having 5 to 30 carbon atoms, that is, a monovalent group obtained by removing one hydrogen atom from a bicycloalkane having 5 to 30 carbon atoms. Bicyclo [1,2,2] heptan-2-yl group, bicyclo [2,2,2] octan-3-yl group),

An alkenyl group (preferably a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, such as a vinyl group or an allyl group), a cycloalkenyl group (preferably a substituted or unsubstituted cycloalkenyl group having 3 to 30 carbon atoms, That is, it is a monovalent group in which one hydrogen atom of a cycloalkene having 3 to 30 carbon atoms is removed, for example, a 2-cyclopenten-1-yl, 2-cyclohexen-1-yl group), a bicycloalkenyl group (substituted or substituted). An unsubstituted bicycloalkenyl group, preferably a substituted or unsubstituted bicycloalkenyl group having 5 to 30 carbon atoms, that is, a monovalent group in which one hydrogen atom of a bicycloalkene having one double bond is removed. Bicyclo [2,2,1] hept-2-en-1-yl group, bicyclo [2,2,2] oct-2-en-4-yl group), alkini Group (preferably a substituted or unsubstituted alkynyl group having 2 to 30 carbon atoms, such as ethynyl group, propargyl group),

An aryl group (preferably a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, such as a phenyl group, a p-tolyl group, a naphthyl group), a heterocyclic group (preferably a 5- or 6-membered substituted or unsubstituted, aromatic A monovalent group obtained by removing one hydrogen atom from an aromatic or non-aromatic heterocyclic compound, and more preferably a 5- or 6-membered aromatic heterocyclic group having 3 to 30 carbon atoms. 2-furyl group, 2-thienyl group, 2-pyrimidinyl group, 2-benzothiazolyl group), cyano group, hydroxyl group, nitro group, carboxyl group, alkoxy group (preferably substituted or unsubstituted having 1 to 30 carbon atoms) Alkoxy groups such as methoxy group, ethoxy group, isopropoxy group, tert-butoxy group, n-octyloxy group, 2-methoxyethoxy group), aryloxy group (preferably Or a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, such as phenoxy group, 2-methylphenoxy group, 4-tert-butylphenoxy group, 3-nitrophenoxy group, 2-tetradecanoylaminophenoxy. Group),

A silyloxy group (preferably a silyloxy group having 3 to 20 carbon atoms, such as trimethylsilyloxy group or tert-butyldimethylsilyloxy group), a heterocyclic oxy group (preferably a substituted or unsubstituted heterocycle having 2 to 30 carbon atoms) Ring oxy group, 1-phenyltetrazole-5-oxy group, 2-tetrahydropyranyloxy group), acyloxy group (preferably formyloxy group, substituted or unsubstituted alkylcarbonyloxy group having 2 to 30 carbon atoms, carbon number 6-30 substituted or unsubstituted arylcarbonyloxy groups such as formyloxy group, acetyloxy group, pivaloyloxy group, stearoyloxy group, benzoyloxy group, p-methoxyphenylcarbonyloxy group), carbamoyloxy group (preferably , C1-C30 substitution or non-placement Carbamoyloxy group, for example, N, N-dimethylcarbamoyloxy group, N, N-diethylcarbamoyloxy group, morpholinocarbonyloxy group, N, N-di-n-octylaminocarbonyloxy group, Nn-octylcarbamoyl An oxy group), an alkoxycarbonyloxy group (preferably a substituted or unsubstituted alkoxycarbonyloxy group having 2 to 30 carbon atoms, such as a methoxycarbonyloxy group, an ethoxycarbonyloxy group, a tert-butoxycarbonyloxy group, and an n-octylcarbonyloxy group. Group), an aryloxycarbonyloxy group (preferably a substituted or unsubstituted aryloxycarbonyloxy group having 7 to 30 carbon atoms, such as phenoxycarbonyloxy group, p-methoxyphenoxycarbonyloxy group, pn- Hexadecyl oxy phenoxycarbonyl group),

An amino group (preferably an amino group, a substituted or unsubstituted alkylamino group having 1 to 30 carbon atoms, a substituted or unsubstituted anilino group having 6 to 30 carbon atoms, such as an amino group, a methylamino group, a dimethylamino group; , Anilino group, N-methyl-anilino group, diphenylamino group), acylamino group (preferably formylamino group, substituted or unsubstituted alkylcarbonylamino group having 1 to 30 carbon atoms, substituted or unsubstituted 6 to 30 carbon atoms, or Unsubstituted arylcarbonylamino group, for example, formylamino group, acetylamino group, pivaloylamino group, lauroylamino group, benzoylamino group), aminocarbonylamino group (preferably substituted or unsubstituted amino having 1 to 30 carbon atoms) Carbonylamino group, for example, carbamoylamino group, N, N-dimethylaminocarbonyl Mino group, N, N-diethylaminocarbonylamino group, morpholinocarbonylamino group), alkoxycarbonylamino group (preferably a substituted or unsubstituted alkoxycarbonylamino group having 2 to 30 carbon atoms, such as methoxycarbonylamino group, ethoxycarbonylamino Group, tert-butoxycarbonylamino group, n-octadecyloxycarbonylamino group, N-methyl-methoxycarbonylamino group), aryloxycarbonylamino group (preferably substituted or unsubstituted aryloxycarbonyl having 7 to 30 carbon atoms) Amino groups such as phenoxycarbonylamino group, p-chlorophenoxycarbonylamino group, mn-octyloxyphenoxycarbonylamino group),

Sulfamoylamino group (preferably a substituted or unsubstituted sulfamoylamino group having 0 to 30 carbon atoms, such as sulfamoylamino group, N, N-dimethylaminosulfonylamino group, Nn-octylamino Sulfonylamino groups), alkyl and arylsulfonylamino groups (preferably substituted or unsubstituted alkylsulfonylamino groups having 1 to 30 carbon atoms, substituted or unsubstituted arylsulfonylamino groups having 6 to 30 carbon atoms, such as methylsulfonyl An amino group, a butylsulfonylamino group, a phenylsulfonylamino group, a 2,3,5-trichlorophenylsulfonylamino group, a p-methylphenylsulfonylamino group, a mercapto group, and an alkylthio group (preferably a substituent having 1 to 30 carbon atoms) Or an unsubstituted alkylthio group such as a methylthio group Ethylthio group, n-hexadecylthio group), arylthio group (preferably a substituted or unsubstituted arylthio group having 6 to 30 carbon atoms, for example, phenylthio group, p-chlorophenylthio group, m-methoxyphenylthio group), heterocyclic thio A group (preferably a substituted or unsubstituted heterocyclic thio group having 2 to 30 carbon atoms, such as 2-benzothiazolylthio group, 1-phenyltetrazol-5-ylthio group),

Sulfamoyl group (preferably a substituted or unsubstituted sulfamoyl group having 0 to 30 carbon atoms such as N-ethylsulfamoyl group, N- (3-dodecyloxypropyl) sulfamoyl group, N, N-dimethylsulfamoyl group N-acetylsulfamoyl group, N-benzoylsulfamoyl group, N- (N′-phenylcarbamoyl) sulfamoyl group), sulfo group, alkyl and arylsulfinyl group (preferably having 1 to 30 carbon atoms substituted or An unsubstituted alkylsulfinyl group, a substituted or unsubstituted arylsulfinyl group having 6 to 30 carbon atoms, such as a methylsulfinyl group, an ethylsulfinyl group, a phenylsulfinyl group, a p-methylphenylsulfinyl group), an alkyl and an arylsulfonyl group ( Preferably, the substitution having 1 to 30 carbon atoms or An unsubstituted alkylsulfonyl group, a substituted or unsubstituted arylsulfonyl group having 6 to 30 carbon atoms, such as a methylsulfonyl group, an ethylsulfonyl group, a phenylsulfonyl group, a p-methylphenylsulfonyl group),

An acyl group (preferably a formyl group, a substituted or unsubstituted alkylcarbonyl group having 2 to 30 carbon atoms, a substituted or unsubstituted arylcarbonyl group having 7 to 30 carbon atoms, such as an acetyl group or a pivaloylbenzoyl group), Aryloxycarbonyl group (preferably a substituted or unsubstituted aryloxycarbonyl group having 7 to 30 carbon atoms, such as phenoxycarbonyl group, o-chlorophenoxycarbonyl group, m-nitrophenoxycarbonyl group, p-tert-butylphenoxy Carbonyl group), alkoxycarbonyl group (preferably a substituted or unsubstituted alkoxycarbonyl group having 2 to 30 carbon atoms, such as methoxycarbonyl group, ethoxycarbonyl group, tert-butoxycarbonyl group, n-octadecyloxycarbonyl group), carbamoyl Group (preferred Is a substituted or unsubstituted carbamoyl group having 1 to 30 carbon atoms, such as a carbamoyl group, N-methylcarbamoyl group, N, N-dimethylcarbamoyl group, N, N-di-n-octylcarbamoyl group, N- ( Methylsulfonyl) carbamoyl group),

Aryl and heterocyclic azo groups (preferably substituted or unsubstituted arylazo groups having 6 to 30 carbon atoms, substituted or unsubstituted heterocyclic azo groups having 3 to 30 carbon atoms, such as phenylazo group, p-chlorophenylazo group, 5-ethylthio-1,3,4-thiadiazol-2-ylazo group), imide group (preferably N-succinimide group, N-phthalimide group), phosphino group (preferably substituted or non-substituted having 2 to 30 carbon atoms) Substituted phosphino groups such as dimethylphosphino group, diphenylphosphino group, methylphenoxyphosphino group), phosphinyl groups (preferably substituted or unsubstituted phosphinyl groups having 2 to 30 carbon atoms such as phosphinyl group, dioctyl Oxyphosphinyl group, diethoxyphosphinyl group), phosphinyloxy group (preferably carbon A substituted or unsubstituted phosphinyloxy group having 2 to 30 carbon atoms, such as a diphenoxyphosphinyloxy group or a dioctyloxyphosphinyloxy group, or a phosphinylamino group (preferably having 2 to 30 carbon atoms) A substituted or unsubstituted phosphinylamino group such as a dimethoxyphosphinylamino group or a dimethylaminophosphinylamino group, a silyl group (preferably a substituted or unsubstituted silyl group having 3 to 30 carbon atoms, such as , Trimethylsilyl group, tert-butyldimethylsilyl group, phenyldimethylsilyl group).

  Among the above substituents, those having a hydrogen atom may be substituted with the above groups after removing this. Examples of such functional groups include an alkylcarbonylaminosulfonyl group, an arylcarbonylaminosulfonyl group, an alkylsulfonylaminocarbonyl group, and an arylsulfonylaminocarbonyl group. Examples thereof include a methylsulfonylaminocarbonyl group, a p-methylphenylsulfonylaminocarbonyl group, an acetylaminosulfonyl group, and a benzoylaminosulfonyl group.

R ¹ is preferably a halogen atom, alkyl group, alkenyl group, aryl group, heterocyclic group, hydroxyl group, carboxyl group, alkoxy group, aryloxy group, acyloxy group, cyano group, amino group, more preferably A halogen atom, an alkyl group, a cyano group, and an alkoxy group;

R ² and R ³ each independently represents a substituent. An example of R ¹ is given as an example. Preferred are a substituted or unsubstituted benzene ring and a substituted or unsubstituted cyclohexane ring. More preferred are a benzene ring having a substituent and a cyclohexane ring having a substituent, and more preferred are a benzene ring having a substituent at the 4-position and a cyclohexane ring having a substituent at the 4-position.

R ⁴ and R ⁵ each independently represents a substituent. An example of R ¹ is given as an example. Preferably, the Hammett substituent constant σp value is preferably an electron-withdrawing substituent greater than 0, and more preferably has an electron-withdrawing substituent having a σp value of 0 to 1.5. . Examples of such a substituent include a trifluoromethyl group, a cyano group, a carbonyl group, and a nitro group. R ⁴ and R ⁵ may be bonded to form a ring.
As for Hammett's substituent constants σp and σm, for example, Naoki Inamoto's “Hammett's Rule-Structure and Reactivity” (Maruzen), edited by the Chemical Society of Japan, “New Experimental Chemistry Course 14 Synthesis and Reaction of Organic Compounds V” 2605 (Maruzen), Tadao Nakatani “Theoretical Organic Chemistry” 217 (Tokyo Kagaku Dojin), Chemical Review, 91, 165-195 (1991).

A ¹ and A ² each independently represent a group selected from the group consisting of —O—, —NR— (wherein R is a hydrogen atom or a substituent), —S—, and —CO—. Preferably -O -, - NR- (. R represents a substituent, examples Examples of the R ¹ and the like) or -S-.
Preferred examples of R ⁵ and R ⁶ include a cyano group (CN), an acyl group (—COR: R represents a substituted or unsubstituted alkyl group or aryl group), a substituted or unsubstituted alkoxycarbonyl group or aryl. Oxycarbonyl group (C (═O) OR: R represents a substituted or unsubstituted alkyl group or aryl group), or a substituted or unsubstituted carbamoyl group (C (═O) NR ¹¹ R ¹² : R ¹¹ and R ¹² represents a hydrogen atom, or a substituted or unsubstituted alkyl group or aryl group, which may be bonded to each other to form a ring. The substituted or unsubstituted alkyl group represented by R, R ¹¹ and R ¹² is preferably a C _{1 to} C ₁₀ substituted or unsubstituted alkyl group, and a C _{2 to} C ₈ substituted or unsubstituted alkyl group. and more preferably at, a still more preferably a substituted or unsubstituted alkyl group of C ₂ -C _6. Moreover, one of the carbon atoms not adjacent to each other in the alkyl group may be substituted with an oxygen atom or a sulfur atom. Examples of the substituted or unsubstituted aryl group represented by R, R ¹¹ and R ¹² include the specific examples of the aryl group exemplified as R ¹ . Examples of the substituent for the alkyl group and aryl group are the same as the examples of the substituent represented by R ¹ . It is also preferable to have a polymerizable group described later as a substituent. Examples of the ring formed by combining R ¹¹ and R ¹² with each other include a piperazine ring.
Among these, it is preferable that one of R ⁵ and R ⁶ is a cyano group and the other is a substituted or unsubstituted alkoxycarbonyl group.
n represents an integer of 0 to 2, preferably 0 or 1.

When the compound represented by the general formula (I) or (I ′) has a polymerizable group, it is preferable because the optical properties of the optically anisotropic layer are not changed by heat or the like. As a polymeric group, it is the same as that of illustration of the substituent Q which the compound represented with general formula (III) mentioned later has. The compound represented by the general formula (I) or (I ') may, for example, may have a polymerizable group as a substituent for R ² and / or R ^3.

  Specific examples of the compound represented by the general formula (I) or (I ′) are shown below, but the present invention is not limited to the following specific examples. Regarding the following compounds, unless otherwise specified, the number in parentheses () indicates the exemplified compound (X).

  The synthesis of the compound represented by the general formula (I) or (I ′) can be performed with reference to known methods. For example, exemplary compound (1) can be synthesized according to the following scheme.

In the scheme, the synthesis from the compound (1-A) to the compound (1-D) is described in “Journal of Chemical Crystallography” (1997); 27 (9); p. 515-526. It can be performed with reference to the method described in 1.
Further, as shown in the above scheme, methanesulfonic acid chloride was added to a tetrahydrofuran solution of the compound (1-E), N, N-diisopropylethylamine was added dropwise and stirred, and then N, N-diisopropylethylamine was added. Exemplary solution (1) can be obtained by adding dropwise a tetrahydrofuran solution of compound (1-D) and then adding a tetrahydrofuran solution of N, N-dimethylaminopyridine (DMAP).

  For the formation of the optically anisotropic layer, it is also preferable to use a compound represented by the following general formula (II).

式中、ＭＧ¹及びＭＧ²はそれぞれ独立に、２〜８個の環状基から構成される液晶相の発現を誘起する液晶コア部であり、液晶コア部を構成する環状基としては、芳香族環、脂肪族環、及び複素環のいずれでもよく；ＭＧ¹及びＭＧ²を構成する環状基の１つは、Ｌ¹¹及びＬ¹²で置換され；Ｒ¹¹、Ｒ¹²、Ｒ¹³、及びＲ¹⁴はそれぞれ液晶コア部の分子長軸方向に置換している液晶相の発現を誘起する柔軟性のある置換基、双極子作用基及び水素結合性基であり；Ｌ¹¹及びＬ¹²はそれぞれ独立に、液晶コア部ＭＧ¹及びＭＧ²に置換する連結基であり、下記式（ＩＩ）−ＬＡ又は式（ＩＩ）−ＬＢで表され；

In the formula, MG ¹ and MG ² are each independently a liquid crystal core part that induces the expression of a liquid crystal phase composed of 2 to 8 cyclic groups, and the cyclic group constituting the liquid crystal core part is an aromatic group Any of a ring, an aliphatic ring, and a heterocyclic ring; ^one of the cyclic groups constituting MG ¹ and MG ² is substituted with L ¹¹ and L ¹² ; R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ Are flexible substituents, dipole action groups, and hydrogen bonding groups that induce the expression of the liquid crystal phase substituted in the molecular long axis direction of the liquid crystal core; L ¹¹ and L ¹² are each independently , A linking group substituted for the liquid crystal core parts MG ¹ and MG ² , represented by the following formula (II) -LA or formula (II) -LB;

式中、＊はＭＧ¹を構成する環状基に置換する位置を表し；＃はＰ¹と連結する位置を表し；Ａ¹¹、Ａ¹³及びＡ¹⁴はそれぞれ独立に、―Ｏ−、−ＮＨ−、−Ｓ−、−ＣＨ₂−、−ＣＯ−、−ＳＯ−、又は−ＳＯ₂−を表し；Ａ¹²は−ＣＨ＝又は−Ｎ＝を表し；Ｌ¹¹及びＬ¹²の双方が式（ＩＩ）−ＬＡで表される基の場合、置換基Ｐ¹は単結合、又は−ＣＨ＝ＣＨ−、−Ｃ≡Ｃ−、１，４−フェニレン及びそ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；Ｌ¹¹及びＬ¹²の一方が、式（ＩＩ）−ＬＢで表される基で、他方が式（ＩＩ）−ＬＡで表される基の場合、置換基Ｐ¹は、＊＝ＣＨ−Ｐ¹¹−＃、又は＊＝Ｎ−Ｐ¹¹−＃で表され（＊は式（ＩＩ）−ＬＢで表される基との連結位置を表し、＃は式（ＩＩ）−ＬＡで表される基との連結位置を表す）；Ｐ¹¹は単結合、又は−ＣＨ＝ＣＨ−、−Ｃ≡Ｃ−、１，４−フェニレン及びこの組み合わせから選ばれる二価の連結基を表し；Ｌ¹¹及びＬ¹²の双方が式（ＩＩ）−ＬＢで表される基の場合、置換基Ｐ¹は、二重結合、＝ＣＨ−Ｐ¹¹−ＣＨ＝、＝Ｎ−Ｐ¹¹−ＣＨ＝、＝Ｎ−Ｐ¹¹−Ｎ＝を表し；Ｐ¹¹は上記Ｐ¹¹と同義である。

In the formula, * represents a position substituted with the cyclic group constituting MG ¹ ; # represents a position linked to P ¹ ; A ¹¹ , A ¹³ and A ¹⁴ are each independently —O—, —NH—. , -S-, -CH _2- , -CO-, -SO-, or -SO _2- ; A ¹² represents -CH = or -N =; both L ¹¹ and L ¹² are represented by the formula (II ) In the case of a group represented by -LA, the substituent P ¹ is a single bond or a divalent group selected from the group consisting of -CH = CH-, -C≡C-, 1,4-phenylene and combinations thereof. In the case where one of L ¹¹ and L ¹² is a group represented by the formula (II) -LB and the other is a group represented by the formula (II) -LA, the substituent P ¹ is represented by * = CH-P ¹¹ - #, or * = N-P ¹¹ - represented by # (* represents a linking position between the groups of the formula (II) -LB, # in formula (II) -LA Group represented Represents the coupling position); P ¹¹ is a single bond, or a -CH = CH -, - C≡C-, represents a 1,4-phenylene and a divalent linking group selected from the combination; L ¹¹ and L ¹² Are both groups represented by the formula (II) -LB, the substituent P ¹ is a double bond, ═CH—P ¹¹ —CH═, ═N—P ¹¹ —CH═, ═N—P ^11. -N =; P ¹¹ has the same meaning as P ¹¹ above.

  The compounds represented by the general formula (I) are described in detail in [2005] to [0083] of JP-A-2005-289980, and the exemplified compounds are also described in [0085] to [0098] of the same publication. Can be used.

The first optically anisotropic layer comprises a liquid crystal compound (preferably a discotic liquid crystal compound of the formula (DI)) and optionally at least one additive represented by the above formula (I) or (II). The composition contained is placed on the surface of a polymer film used as the second optically anisotropic layer (for example, the alignment film surface), the molecules of the liquid crystal compound are brought into a desired alignment state, cured by polymerization, and the alignment Preferably, the state is fixed. It is preferable to fix the molecules of the liquid crystal compound (including both rod-like and disk-like molecules) in a hybrid alignment state.
The hybrid alignment refers to an alignment state in which the director direction of liquid crystal molecules continuously changes in the layer thickness direction. In the case of a rod-like molecule, the director is in the major axis direction, and in the case of a disc-like molecule, the director is in the normal direction of the disc surface.

Further, the composition may contain one or more additives in order to bring the molecules of the liquid crystal compound into a desired alignment state and to improve the applicability or curability of the composition.
In order to hybrid-align the molecules of the liquid crystal compound (particularly rod-shaped liquid crystal compound), an additive capable of controlling the orientation of the layer on the air interface side (hereinafter referred to as “air interface orientation control agent”) may be added. Examples of the additive include low molecular weight or high molecular weight compounds having hydrophilic groups such as fluorinated alkyl groups and sulfonyl groups. Specific examples of usable air interface orientation control agents include compounds described in JP-A 2006-267171.

  Moreover, when the said composition is prepared as a coating liquid and the said 1st optically anisotropic layer is formed by application | coating, you may add surfactant for the improvement of applicability | paintability. As the surfactant, a fluorine-based compound is preferable, and specific examples include compounds described in paragraph numbers [0028] to [0056] in JP-A-2001-330725. Commercially available “Megafac F780” (manufactured by Dainippon Ink) may be used.

Moreover, it is preferable that the said composition contains the polymerization initiator. The polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator, but a photopolymerization initiator is preferable from the viewpoint of easy control. Examples of photopolymerization initiators that generate radicals by the action of light include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670) and acyloin ethers (described in US Pat. No. 2,448,828). ), Α-hydrocarbon-substituted aromatic acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), triarylimidazole dimers and p-amino Combination with phenyl ketone (described in US Pat. No. 3,549,367), acridine and phenazine compounds (described in JP-A-60-105667, US Pat. No. 4,239,850) and oxadiazole compounds (US Pat. No. 4,221,970) Description), acetophenone series Compounds, benzoin ether compounds, benzyl compounds, benzophenone compounds, thioxanthone compounds and the like are preferable. Examples of the acetophenone compound include 2,2-diethoxyacetophenone, 2-hydroxymethyl-1-phenylpropan-1-one, 4′-isopropyl-2-hydroxy-2-methyl-propiophenone, 2-hydroxy -2-methyl-propiophenone, p-dimethylaminoacetone, p-tert-butyldichloroacetophenone, p-tert-butyltrichloroacetophenone, p-azidobenzalacetophenone and the like. Examples of the benzyl compound include benzyl, benzyl dimethyl ketal, benzyl-β-methoxyethyl acetal, 1-hydroxycyclohexyl phenyl ketone and the like. Examples of benzoin ether compounds include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin-n-propyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, and benzoin isobutyl ether. Examples of the benzophenone compound include benzophenone, methyl o-benzoylbenzoate, Michler's ketone, 4,4′-bisdiethylaminobenzophenone, 4,4′-dichlorobenzophenone, and the like. Examples of the thioxanthone compound include thioxanthone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, and the like. Among such photosensitive radical polymerization initiators composed of aromatic ketones, acetophenone compounds and benzyl compounds are particularly preferable in terms of curing characteristics, storage stability, odor, and the like. The photosensitive radical polymerization initiators composed of these aromatic ketones can be used alone or in combination of two or more according to the desired performance.
In addition to a polymerization initiator, a sensitizer may be used for the purpose of increasing sensitivity. Examples of the sensitizer include n-butylamine, triethylamine, tri-n-butylphosphine, thioxanthone and the like.

  Multiple photopolymerization initiators may be combined, and the amount used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the solid content of the coating solution. The light irradiation for the polymerization of the liquid crystal compound preferably uses ultraviolet rays.

Apart from the polymerizable liquid crystal compound, the composition may contain a non-liquid crystalline polymerizable monomer. As the polymerizable monomer, a compound having a vinyl group, a vinyloxy group, an acryloyl group or a methacryloyl group is preferable. Note that it is preferable to use a polyfunctional monomer having two or more polymerizable reactive functional groups, for example, ethylene oxide-modified trimethylolpropane acrylate because durability is improved.
Since the non-liquid crystalline polymerizable monomer is a non-liquid crystalline component, the addition amount thereof does not exceed 15% by mass with respect to the liquid crystal compound, and is preferably about 0 to 10% by mass.

The first optically anisotropic layer is prepared by using the composition as a coating solution, and the coating solution is applied to, for example, the surface of an alignment film formed on a support and dried to remove the solvent. At the same time, the molecules of the liquid crystal compound can be aligned and then cured by polymerization to form.
Application methods include curtain coating, dip coating, spin coating, print coating, spray coating, slot coating, roll coating, slide coating, blade coating, gravure coating, wire bar method, etc. A well-known coating method is mentioned.
You may heat when drying a coating film. The coating film is dried to remove the solvent, and at the same time, the molecules of the liquid crystal compound in the coating film are aligned to obtain a desired alignment state.

Next, polymerization is advanced by ultraviolet irradiation or the like to fix the alignment state and form the first optical anisotropic layer. It is preferable to use ultraviolet rays for light irradiation for polymerization. The irradiation energy is preferably 20 mJ / cm ^{2 to} 50 J / cm ² , and more preferably 100 mJ / cm ^{2 to} 800 mJ / cm ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.

  Although there is no restriction | limiting in particular about the thickness of a 1st optically anisotropic layer, It is preferable that it is 0.1-10 micrometers, and it is more preferable that it is 0.5-5 micrometers.

  The first optically anisotropic layer is preferably formed using an alignment film. Examples of the alignment film that can be used include a polyvinyl alcohol film and a polyimide film.

(Second optically anisotropic layer)
The polarizing plate of the present invention has a second optically anisotropic layer having Re (550) of 40 to 110 nm and retardation Rth (550) in the thickness direction at a wavelength of 550 nm of 40 to 100 nm. That is, the second optically anisotropic layer is optically biaxial. Re (550) is preferably 50 to 100 nm, and Rth (550) is preferably 50 to 80 nm.

  The second optically anisotropic layer is preferably a polymer film having optical transparency, specifically, a transmittance of 80% or more for visible light. When the second optically anisotropic layer is a polymer film, it can be bonded to the surface of the polarizer. The polymer film material is preferably a polymer excellent in optical performance, transparency, mechanical strength, thermal stability, moisture shielding property, isotropy, etc., but any material is acceptable as long as it satisfies the above conditions. May be used. For example, a modified polycarbonate, a modified cycloolefin polymer, a cellulose polymer having an acetyl group in the side chain (hereinafter referred to as cellulose acylate), or the like is preferably used as a material that expresses Re by stretching or the like.

Even if the acyl substituent of the cellulose acylate used as the material of the cellulose acylate film for the second optically anisotropic layer is, for example, a cellulose acylate composed of an acetyl group alone, a cellulose having a plurality of acyl substituents A composition containing acylate may be used. Preferable examples of cellulose acylate have a total acylation degree of 2.3 to 3.0, and more preferably 2.4 to 2.95.
Moreover, the mixed fatty acid ester which has another fatty acid ester residue with an acetyl group is also preferable. The number of carbon atoms in the aliphatic acyl group of the fatty acid ester residue is preferably 2 to 20, and specific examples include acetyl, propionyl, butyryl, isobutyryl, valeryl, pivaloyl, hexanoyl, octanoyl, lauroyl, stearoyl and the like. . Among them, it is preferable to use cellulose acylate having an acyl group selected from propionyl group, butyryl group, pentanoyl group and hexanoyl group together with acetyl group, and the degree of substitution satisfies the following formulas (1) to (3). More preferably, cellulose acylate is used.
(1) 2.0 ≦ X + Y ≦ 3.0
(2) 0 ≦ X ≦ 2.0
(3) 1.2 ≦ Y ≦ 2.9
In the formulas (1) to (3), X represents the substitution degree of the acetyl group in cellulose acylate, and Y is an acyl group selected from propionyl group, butyryl group, pentanoyl group, and hexanoyl group in cellulose acylate. Indicates the sum of the degree of substitution.

  The cellulose acylate preferably has a mass average degree of polymerization of 350 to 800, and more preferably has a mass average degree of polymerization of 370 to 600. The cellulose acylate used in the present invention preferably has a number average molecular weight of 70000 to 230,000, more preferably 75000 to 230,000, and more preferably 78000 to 120,000. Further preferred.

  The cellulose acylate film is preferably produced by a solution casting method or a melt casting method. Examples of producing cellulose acylate films using the solution casting method are described in US Pat. Nos. 2,336,310, 2,367,603, 2,492,078, and 2,492,977. 2,492,978, 2,607,704, 2,739,069 and 2,739,070, British Patent Nos. 640731 and 736892 And JP-B Nos. 45-4554, 49-5614, JP-A-60-176834, JP-A-60-203430, JP-A-62-115035, and the like. The cellulose acylate film exhibits Re and Re reverse wavelength dispersibility by being subjected to stretching treatment. For the stretching method and conditions, see, for example, the examples described in JP-A-62-115035, JP-A-4-152125, JP-A-2842211, JP-A-298310, JP-A-11-48271, etc. Can be.

In the second optically anisotropic layer, Re may exhibit reverse dispersion wavelength dependence in a visible light region. In order to produce a polymer film having such properties, it is preferable to perform a stretching treatment after forming a composition containing cellulose acetate propionate and cellulose acetate by a melt film forming method.
In addition, it is preferable that a composition containing cellulose acylate (preferably cellulose acetate) and a Re enhancer is formed by a solution casting method and stretched as desired. Here, the “Re developing agent” is a compound having the property of developing birefringence within the film plane. As the Re enhancer, the compound represented by the above formula (I) mentioned as an example that can be used for preparing the first optically anisotropic layer is preferable.

In addition, for the production of the second optically anisotropic layer, a compound represented by the following formula (V) is used as a Re enhancer instead of or together with the compound represented by the above formula (I). May be.
(V) Ar ¹ -L ¹ -Ar ²
In the formula (V), Ar ¹ and Ar ² are each independently an aromatic group.
In the present specification, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group, and a substituted aromatic heterocyclic group.
An aryl group and a substituted aryl group are more preferable than an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The heterocycle of the aromatic heterocyclic group is generally unsaturated. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As a hetero atom, a nitrogen atom, an oxygen atom or a sulfur atom is preferable, and a nitrogen atom or a sulfur atom is more preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine Rings, pyridazine rings, pyrimidine rings, pyrazine rings, and 1,3,5-triazine rings are included.
As the aromatic ring of the aromatic group, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable. .

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

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

In the formula (V), L ¹ is a divalent linking group selected from the group consisting of an alkylene group, an alkenylene group, an alkynylene group, a divalent saturated heterocyclic group, —O—, —CO—, and combinations thereof. is there.
The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group.
The number of carbon atoms of the alkylene group is preferably 1-20, more preferably 1-15, still more preferably 1-10, still more preferably 1-8, 6 is most preferred.

The alkenylene group and the alkynylene group preferably have a chain structure rather than a cyclic structure, and more preferably have a linear structure rather than a branched chain structure.
The number of carbon atoms of the alkenylene group and the alkynylene group is preferably 2 to 10, more preferably 2 to 8, still more preferably 2 to 6, and still more preferably 2 to 4. Most preferred is 2 (vinylene or ethynylene).
The divalent saturated heterocyclic group preferably has a 3- to 9-membered heterocyclic ring. The hetero atom of the hetero ring is preferably an oxygen atom, a nitrogen atom, a boron atom, a sulfur atom, a silicon atom, a phosphorus atom or a germanium atom. Examples of saturated heterocycles include piperidine ring, piperazine ring, morpholine ring, pyrrolidine ring, imidazolidine ring, tetrahydrofuran ring, tetrahydropyran ring, 1,3-dioxane ring, 1,4-dioxane ring, tetrahydrothiophene ring, 1 , 3-thiazolidine ring, 1,3-oxazolidine ring, 1,3-dioxolane ring, 1,3-dithiolane ring and 1,3,2-dioxaborolane. Particularly preferred divalent saturated heterocyclic groups are piperazine-1,4-diylene, 1,3-dioxane-2,5-diylene and 1,3,2-dioxaborolane-2,5-diylene.

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

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

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

In the formula (VI), X is 1,4-cyclohexylene, vinylene or ethynylene.
Specific examples of the compound represented by formula (V) are shown below.

  Specific examples (1) to (34), (41), (42), (46), (47), (52), (53) are two asymmetric carbons at the 1st and 4th positions of the cyclohexane ring. Has atoms. However, the specific examples (1), (4) to (34), (41), (42), (46), (47), (52), (53) have a symmetric meso type molecular structure. Therefore, there is no optical isomer (optical activity) and only geometric isomers (trans and cis forms) exist. The trans type (1-trans) and cis type (1-cis) of specific example (1) are shown below.

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

Moreover, you may use the rod-shaped aromatic compound of pages 11-14 of Unexamined-Japanese-Patent No. 2004-50516 as said Re expression agent.
Further, as the Re enhancer, one kind of compound can be used alone, or two or more kinds of compounds can be mixed and used. It is preferable to use two or more compounds different from each other as the Re enhancer because the retardation adjustment range is widened and can be easily adjusted to a desired range.
The addition amount of the Re enhancer is preferably 0.1 to 20% by mass, and more preferably 0.5 to 10% by mass with respect to 100 parts by mass of cellulose acylate. When the cellulose acylate film is produced by a solvent cast method, the Re enhancer may be added to the dope. The addition may be performed at any timing. For example, the Re developing agent may be dissolved in an organic solvent such as alcohol, methylene chloride, dioxolane, etc., and then added to the cellulose acylate solution (dope) or directly. You may add during dope composition.

  In order to produce a cellulose acylate film that satisfies the conditions for the second optically anisotropic layer, it is preferable to add an Rth enhancer to the cellulose acylate film. Here, the “Rth enhancer” is a compound having the property of developing birefringence in the thickness direction of the film.

  As the Rth enhancer, a compound having a large polarizability anisotropy having an absorption maximum in a wavelength range of 250 nm to 380 nm is preferable. As the Rth enhancer, a compound represented by the following general formula (VII) can be particularly preferably used.

In the formula, X ¹ is a single bond, —NR ⁴ —, —O— or S—; X ² is a single bond, —NR ⁵ —, —O— or S—; X ³ is a single bond A bond, —NR ⁶ —, —O— or S—. R ¹ , R ² , and R ³ are each independently an alkyl group, an alkenyl group, an aromatic ring group, or a heterocyclic group; R ⁴ , R ^5, and R ⁶ are each independently a hydrogen atom , An alkyl group, an alkenyl group, an aryl group or a heterocyclic group.

  Preferred examples of the compound represented by the general formula (VII) are shown below, but the present invention is not limited to these specific examples.

  The cellulose acylate film used as the second optically anisotropic layer may contain an ultraviolet absorber. In particular, a cellulose acylate film formed from a composition containing cellulose acylate (more preferably, cellulose acetate propionate (CAP)) satisfying the formulas (1) to (3) and an ultraviolet absorber is provided. The film is preferably stretched in a direction perpendicular to the film longitudinal direction because a film satisfying the second optical characteristics can be easily produced. The ultraviolet absorber can also function as an Rth enhancer. Examples of the ultraviolet absorbers include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. System compounds are preferred. Further, ultraviolet absorbers described in JP-A-10-182621 and JP-A-8-337574 and polymer ultraviolet absorbers described in JP-A-6-148430 are also preferably used. The cellulose acylate film used as the second optically anisotropic layer has an excellent ability to absorb ultraviolet rays having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of a polarizer and liquid crystal as an ultraviolet absorber, and From the viewpoint of liquid crystal display properties, those that absorb less visible light having a wavelength of 400 nm or more are preferred.

You may produce the polymer film which satisfies the optical characteristic requested | required of a said 2nd optically anisotropic layer by extending | stretching with respect to various polymer films.
In particular, a CAP film produced by melt extrusion of cellulose acylate (more preferably, cellulose acetate propionate (CAP)) satisfying the above formulas (1) to (3) at a temperature of 100 to 120 ° C. A CAP film satisfying the above optical properties can be produced by subjecting the film in the longitudinal direction to a stretching treatment at a stretching ratio of 50 to 70%.
In addition, a composition containing the Re enhancer represented by the above formula (I) and TAC having a total acylation degree of 2.3 to 3.0 is formed by a solution casting method, A TAC film satisfying the above optical properties can be produced by subjecting the film to a direction orthogonal to the direction at a temperature of 140 to 190 ° C. and a stretch ratio of 15 to 35%.

  Although the thickness of the polymer film used as the second optically anisotropic layer is not particularly limited, it is generally preferably 30 to 120 μm, and more preferably 30 to 100 μm.

(Polarizing layer)
The polarizing plate of the present invention has a polarizing layer. The polarizing layer is made of a linear polarizing film. The linear polarizing film includes an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film, and any of them may be used in the present invention. The iodine polarizing film and the dye polarizing film are generally produced using a polyvinyl alcohol film.

(Protective layer)
The protective layer bonded to the surface of the polarizing layer opposite to the side on which the first and second optically anisotropic layers are disposed is light transmissive, specifically visible. A polymer film having a light transmittance of 80% or more for light is preferably used. As the protective film, a cellulose acylate film and a polyolefin film containing polyolefin are preferable. Among the cellulose acylate films, a cellulose triacetate film is preferable. Of the polyolefin films, a polynorbornene film containing a cyclic polyolefin is preferable.
The thickness of the polymer film used as the protective layer is preferably 20 to 500 μm, and more preferably 50 to 200 μm.

(Preparation of polarizing plate)
The polarizing plate of the present invention can be produced by a roll-to-roll method. For example, it can be produced by the following method.
First, a coating solution for forming an alignment film is continuously applied to the surface of a polymer film such as a long cellulose acylate film (a polymer film that satisfies the optical properties required for the second optically anisotropic layer). The alignment film is continuously formed by performing a rubbing treatment in a predetermined crossing angle with respect to the longitudinal direction, preferably 0.2 to 4.0 °, more preferably 0.3 to 2.0 °. Form. A coating liquid of a curable liquid crystal composition containing a polymerizable discotic liquid crystal is continuously applied to the rubbing treated surface and dried to bring the discotic liquid crystal into a desired alignment state, and polymerization proceeds in that state. Then, an optically anisotropic film (an optically anisotropic layer satisfying optical characteristics required for the first optically anisotropic layer) is continuously formed, and an optical compensation film (first and second optical films) is formed. A laminate of anisotropic layers) is continuously produced. The produced long optical compensation film is temporarily wound into a roll. A coating solution for forming a light diffusion layer is continuously applied to the surface of a long polymer film (protective layer), dried and cured to form a light diffusion layer (a light diffusion layer that satisfies the above specified characteristics). Then, a long light diffusion film is produced. It is wound up into a roll form. A roll of a long optical compensation film, a roll of a long linear polarizing film (polarizing layer), and a roll of a long light diffusion film (protective layer) are bonded together in a roll-to-roll system. The polarizing plate of the present invention can be produced. In the case where the light diffusion layer is a self-supporting light diffusion film, after the optical compensation film, the linearly polarizing film and the protective layer polymer film are laminated by roll-to-roll, a laminate is produced. Further, it may be formed by a light diffusion film roll-to-roll. In addition, once the optical compensation film, the linearly polarizing film, and the protective layer polymer film were laminated by roll-to-roll to produce a laminate, the light diffusion layer coating solution was continuously applied to obtain a light A diffusion layer may be formed.
The polarizing plate produced in a long shape is conveyed and stored in a state of being wound in a roll form, and is cut into a predetermined size when actually used in a liquid crystal display device. Of course, the polarizing plate may be prepared by cutting and pasting each member into a predetermined size.

[Liquid Crystal Display]
Since the TN mode liquid crystal display device of the present invention satisfies the wide viewing angle characteristic without reducing the front contrast, it can be used particularly for a display monitor for a TV or a PC with a TV function.
The TN mode liquid crystal display device of the present invention has a front contrast of 800 or more. Preferably it is 1000 or more, More preferably, it is 1500 or more. The upper limit value is not limited, but the upper limit value of the front contrast of the TN mode liquid crystal display device is generally said to be about 800. Further, in a liquid crystal display device for TV or the like, a viewing angle with a contrast ratio of 10 or more for monochrome display exceeds 320 degrees, and in a TV for color display or the like, the screen normal direction is further set to 0 °, U ′ at a point farthest from the front u′v ′ value from the locus on ΔCu′v ′ (u′v ′ (color coordinates in CIELAB space) space at a viewing angle of 0 to 60 °. (meaning the distance to v ′) is 0.06 or less. Further, it is required that a region where gradation inversion does not occur in the downward direction is a polar angle of 50 ° or more. The liquid crystal display device of the present invention exhibits excellent viewing angle characteristics that can satisfy any of the characteristics.

  FIG. 2 shows a schematic diagram of one embodiment of the liquid crystal display device of the present invention. The liquid crystal display device shown in FIG. 1 includes a protective film (16a), a polarizing layer (10a), a second optical anisotropic layer (12a), and a first optical anisotropic layer in order from the backlight (BL) side. (14a), lower substrate (22a) of liquid crystal cell, nematic liquid crystal layer (20), upper substrate (22b) of liquid crystal cell, first optical anisotropic layer (14b), second optical anisotropic layer ( 12b), a polarizing layer (10b), a protective film (16b), and a light diffusion layer (18) on the outside thereof. The polarizing plate P of the present invention is arranged as a display surface side polarizing plate, and the polarizing plate P ′ having the same configuration as the polarizing plate P of the present invention is the backlight side except that the light diffusion layer 18 is removed. It is arranged as a polarizing plate. The pair of polarizing layers (10a and 10b) are arranged with their transmission axes orthogonal to each other, and the optically anisotropic layers (14a and 14b) are each formed of a liquid crystalline composition, and Re (450) / Re ( 550) is 0.9 to 1.1, and the second optically anisotropic layer (12a and 12b) has Re (550) of 40 to 120 nm and Rth (550) of 40 to 100 nm, respectively. And has a function of protecting the polarizing layers (10a and 10b) and supporting the first optical anisotropic layers (14a and 14b). The first and second optically anisotropic layers have a function of compensating for birefringence remaining in the nematic liquid crystal layer (20) during black display and voltage application.

  The TN mode liquid crystal layer 20 is made of a nematic liquid crystal material, and nematic liquid crystal molecules are aligned substantially perpendicular to the surfaces of the substrates 22a and 22b during black display. The product Δn · d of the thickness d (micron) of the liquid crystal layer 20 and the refractive index anisotropy Δn is not particularly limited, but is generally about 0.1 to 1.5 μm.

The light diffusion layer 18 of the display surface side polarizing plate P scatters the light that has passed through the polarizing layer 10b. The scattered light intensity of the scattered light from the light diffusion layer 18 is in the polar angle 30 ° direction at the azimuth angle where the scattering intensity is maximum with respect to the light intensity I with an emission angle of 0 ° (in the film normal direction). I ₃₀ , that is, I ₃₀ / I, is 0.01 to 0.2%. In the liquid crystal display device of FIG. 1, in the display surface side polarizing plate P, the first and second optical anisotropic layers (12b and 14b) and the light diffusion layer 18 satisfying predetermined characteristics are combined, While diffusing light, the viewing angle is expanded without impairing the front contrast, and the viewing angle display characteristics are improved not only when displaying black but also when displaying white to halftone. In the liquid crystal display device of FIG. 2, since the backlight side polarizing plate P ′ also includes the first and second optically anisotropic layers (14a and 12a), the display characteristics are further improved.

  Although the mode of the TN mode liquid crystal display device has been described with reference to FIG. 2, the present invention is not limited to the TN mode, and the present invention can be applied to any mode in which nematic liquid crystal is vertically aligned during black display, for example, OCB mode or ECB mode. The effect is obtained.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below. Hereinafter, for convenience, “part by mass” may be simply referred to as “part”, and “liter” may be simply referred to as “L”.

[Second optically anisotropic layer]
(Preparation of film 1 for second optically anisotropic layer)
Each component described in the following table was mixed to prepare a cellulose acylate solution. This cellulose acylate solution was cast on a metal support, the obtained web was peeled from the support, and then stretched 20% at 185 ° C. in the TD direction to produce a film 1. In addition, TD direction means the direction orthogonal to the conveyance direction of a film. The film thickness after stretching was 80 μm.

  In the production of the film 1, films 2 to 15 were produced by appropriately changing the addition amount of the retardation control agent (1) and the retardation control agent (2) and the stretch ratio of the obtained web. The amount of each retardation control agent added, the web stretch ratio, and the optical properties of each film obtained are summarized in the following table.

[First optically anisotropic layer]
(Formation of alignment film)
On the film 1 produced above, an alignment film coating solution having the following composition was coated at 24 mL / m ² with a # 14 wire bar coater. It was dried for 120 seconds with 100 ° C. warm air. Next, the longitudinal direction (transport direction) of the optically anisotropic layer 2 was set to 0 °, and the formed film was rubbed in the 0 ° direction.

───────────────────────────────────
Composition of alignment film coating solution ────────────────────────────────────
The following modified polyvinyl alcohol 40 parts by weight water 728 parts by weight Methanol 228 parts by weight glutaraldehyde (crosslinking agent) 2 parts by weight citrate ester (AS3, Sankyo Chemical Co., Ltd.) 0.69 parts by weight ──────── ────────────────────────────

(Formation of optically anisotropic layer 1 (first optically anisotropic layer))
On the alignment film, the coating liquid for optical anisotropic layer having the following composition is conveyed at 20 m / min by rotating the wire bar of # 3.4 at 781 rpm in the same direction as the film conveying direction. The roll film was continuously applied to the alignment film surface. In the step of continuously heating from room temperature to 100 ° C., the solvent was evaporated and dried, and then heated in a drying zone at 135 ° C. for about 120 seconds to align the discotic liquid crystal compound. Next, it is transported to a drying zone at 100 ° C., and irradiated with ultraviolet rays having an illuminance of 600 mW for 4 seconds by an ultraviolet irradiation device (ultraviolet lamp: output 160 W / cm, emission length 1.6 m), and the crosslinking reaction proceeds, so that the discotic The liquid crystal compound was fixed in that orientation. Then, it stood to cool to room temperature and obtained the optically anisotropic layer 1. The roll-shaped optical film 1 was obtained by winding up into a cylindrical shape.

───────────────────────────────────
Optically anisotropic layer coating composition ───────────────────────────────────
Discotic liquid crystal compound (1) 38 parts by mass The following wavelength dispersion control agent (2) 3 parts by mass Ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 4 parts by mass cellulose acetate butyrate (CAB551-0.2, manufactured by Eastman Chemical Co., Ltd.) 0.14 parts by mass cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemicals Co., Ltd.) 0.22 parts by mass of fluoroaliphatic group-containing polymer (Megafac F780, large 0.45 parts by mass photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 1.35 parts by mass sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.45 parts by mass methyl ethyl ketone 200 mass ─────────────────────────── ───────

(Formation of optically anisotropic layers 2 to 15)
In the production method of the optically anisotropic layer 1, by appropriately changing the addition amount of the wavelength dispersion controlling agent (2), cellulose acetate butyrate (CAB551-0.2), cellulose acetate butyrate (CAB531-1), Optical anisotropic layers 2 to 15 were formed on the films 2 to 15, respectively, and optical films 1 to 15 were produced. For forming the optically anisotropic layer 10, the following discotic liquid crystal compound (3) was used instead of the discotic liquid crystal compound (1). The amount of each additive added and the optical properties of the obtained optically anisotropic layer are summarized in the following table.

<Preparation of optical film 16>
(Preparation of ring-opening polymerized cyclic polyolefin dope)
The following composition was put into a mixing tank, stirred to dissolve each component, and then filtered through a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm.

―――――――――――――――――――――――――――――――――
Cyclic polyolefin solution A
―――――――――――――――――――――――――――――――――
Arton G (manufactured by JSR Corporation) 150 parts by mass Methylene chloride 550 parts by mass Ethanol 50 parts by mass ――――――――――――――――――――――――――――― ―――

  Next, the following composition containing the ring-opening polymerization cyclic polyolefin solution prepared by the above method was put into a disperser to prepare a mat agent dispersion.

――――――――――――――――――――――――――――――――――
Matting agent dispersion ――――――――――――――――――――――――――――――――――
Silica particles having an average particle diameter of 16 nm (aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) 2 parts by mass Methylene chloride 75 parts by mass Ethanol 5 parts by mass Cyclic polyolefin solution A 10 parts by mass ――――――――――――― ――――――――――――――――――――

  100 parts by mass of the cyclic polyolefin solution and 1.1 parts by mass of the matting agent dispersion were mixed to prepare a dope for film formation.

The above dope was cast using a band casting machine. The film peeled off from the band with a residual solvent amount of about 22% by mass was stretched in the width direction at a stretch rate of 50% using a tenter. Then, the tenter transport was shifted to the roll transport, and further dried at 120 to 140 ° C. and wound up. The produced cyclic polyolefin film 16 had a thickness of 80 μm, Re (550) of 70 nm and Rth (550) of 80 nm in a 25 ° C., 60% RH environment. That is, this film 16 satisfied the conditions as the second optically anisotropic layer. This film 16 was subjected to glow discharge treatment (frequency 3000 Hz, 4200 V high frequency voltage applied between the upper and lower electrodes, treatment for 20 seconds) between brass upper and lower electrodes (argon gas atmosphere).
An optically anisotropic layer 16 was formed on the treated surface in the same manner as the optically anisotropic layer 1 to produce an optical film 16.

(Measurement of optical properties)
The optically anisotropic layer 16 was peeled from the produced optical film 16 and transferred onto a glass plate via an adhesive. The glass plate / adhesive used was optically isotropic.
The optically anisotropic layer 16 was measured for in-plane retardation Re (550) at a wavelength of 550 nm using KOBRA 21ADH, and Re (550) was 34 nm. Further, in the optically anisotropic layer 16, the discotic compound molecules are fixed in a hybrid alignment state, there is no direction in which Re (550) becomes 0 nm, and the absolute value of Re (550) is the smallest. That the direction to be is neither in the normal direction of the layer nor in the plane, the light having the wavelength λ nm from the inclined direction in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction. A total of 6 points were measured after incidence, and the values were confirmed from KOBRA 21ADH or WR based on the measured retardation value, the assumed average refractive index, and the input film thickness value.
Similarly, when Re (450) at a wavelength of 450 nm was measured, Re (450) / Re (550) was 1.09.

[Light diffusion film (high internal scattering film)]
(Preparation of coating solution 1 for light diffusion layer)
The following coating solution 1 was filtered through a polypropylene filter having a pore size of 30 μm to prepare a coating solution for a light diffusion layer.

Coating solution for light diffusion layer 1
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DPHA 15g
PETA 73g
Irgacure 184 1g
Irgacure 127 1g
Average particle size 5.0μm Styrene particles 8g
Average particle size 1.5μm benzoguanamine particles 2g
MEK 50g
MIBK 50g
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The compounds used are shown below.
DPHA: Mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate [manufactured by Nippon Kayaku Co., Ltd.]
PET-30: Pentaerythritol triacrylate [manufactured by Nippon Kayaku Co., Ltd.]
・ Irgacure 127: Polymerization initiator [Ciba Specialty Chemicals Co., Ltd.]
・ Irgacure 184: Polymerization initiator [Ciba Specialty Chemicals Co., Ltd.]

[Light diffusion film (high internal scattering film)]
(Preparation of coating solution 2 for light diffusion layer)
The following coating solution 2 was filtered through a polypropylene filter having a pore diameter of 30 μm to prepare a coating solution for a light diffusion layer.
Light diffusion layer coating solution 2
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DPHA 80g
Irgacure 184 1g
Irgacure 127 1g
Melamine particles with an average particle size of 1.5μm 18g
MEK 30g
MIBK 70g
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The compounds used are shown below.
DPHA: Mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate [manufactured by Nippon Kayaku Co., Ltd.]
・ Irgacure 127: Polymerization initiator [Ciba Specialty Chemicals Co., Ltd.]
・ Irgacure 184: Polymerization initiator [Ciba Specialty Chemicals Co., Ltd.]
-1.5 μm particle size melamine particles: Opto beads [manufactured by Nissan Chemical Co., Ltd.]

(Preparation of coating solution for low refractive index layer)
-Preparation of sol solution Stirrer, reactor equipped with reflux condenser, methyl ethyl ketone 120 parts, acryloyloxypropyltrimethoxysilane (KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts, diisopropoxy aluminum ethyl acetoacetate 3 After adding a part and mixing, 30 parts of ion-exchange water was added, and it was made to react at 60 degreeC for 4 hours, Then, it cooled to room temperature and obtained the sol liquid. The mass average molecular weight was 1600, and among the components higher than the oligomer component, the component having a molecular weight of 1000 to 20000 was 100%. Further, from the gas chromatography analysis, the raw material acryloyloxypropyltrimethoxysilane did not remain at all.

-Preparation of dispersion hollow silica fine particle sol (isopropyl alcohol silica sol, average particle size 60 nm, shell thickness 10 nm, silica concentration 20% by mass, silica particle refractive index 1.31, in Preparation Example 4 of JP-A-2002-79616) According to changes made in size, 500 g is mixed with 30 g of acryloyloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 1.5 g of diisopropoxyaluminum ethyl acetate, and then 9 g of ion-exchanged water is added. It was. After reacting at 60 ° C. for 8 hours, the mixture was cooled to room temperature, and 1.8 g of acetylacetone was added. While adding cyclohexanone to 500 g of this dispersion so that the content of silica was almost constant, solvent substitution by vacuum distillation was performed. There was no generation of foreign matter in the dispersion, and the viscosity when the solid content concentration was adjusted to 20% by mass with cyclohexanone was 5 mPa · s at 25 ° C. When the residual amount of isopropyl alcohol in the obtained dispersion A was analyzed by gas chromatography, it was 1.5%.

-Preparation of coating solution for low refractive index layer Ethylenically unsaturated group-containing fluoropolymer (Fluoropolymer (A-1) described in Production Example 3 of JP-A-2005-89536) 41.0 g of methyl isobutyl as a solid content Dissolve in 500 g of ketone, and further, Dispersion A 260 parts by mass (silica + surface treatment agent solid content 52.0 parts by mass), DPHA 5.0 parts by mass, Irgacure 127 (photopolymerization initiator, Ciba Specialty Chemicals) (Made) 2.0 mass parts was added. A coating solution for a low refractive index layer was prepared by diluting with methyl ethyl ketone so that the solid content concentration of the entire coating solution was 6% by mass. The refractive index of the layer formed by this coating solution was 1.36.

(Formation of light diffusion layer)
A triacetyl cellulose film (TAC-TD80UL, manufactured by Fuji Film Co., Ltd.) was unwound in a roll form, and using a coater having a throttle die, the light diffusion layer coating solution was directly extruded and applied. After coating at a transfer speed of 30 m / min and drying at 30 ° C. for 15 seconds and 90 ° C. for 20 seconds, an air-cooled metal halide lamp with an oxygen concentration of 0.2% under nitrogen purge (Igraphics Corporation) )), The coating layer was cured by irradiating with an ultraviolet ray with an irradiation amount of 90 mJ / cm ² to form a light diffusion layer, and then wound up. Here, the light-diffusion layers 11-13 and 21-23 were each produced by changing suitably the coating liquid for light-diffusion layers and the thickness of a coating layer.
The coating liquid used and the thickness and optical properties of the obtained light diffusion layer are summarized in the following table.
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Light diffusion layer 11 Coating liquid 1 Thickness 8.0 μm I ₃₀ / I 0.10%
Light diffusion layer 12 Coating solution 1 Thickness 5.0 μm I ₃₀ / I 0.05%
Light diffusion layer 13 Coating solution 1 Thickness 20.0 μm I ₃₀ / I 0.27%
Light diffusion layer 21 Coating liquid 2 Thickness 7.0 μm I ₃₀ / I 0.05%
Light diffusion layer 22 Coating liquid 2 Thickness 1.5 μm I ₃₀ / I 0.007%
Light diffusion layer 23 Coating solution 2 Thickness 20.0 μm I ₃₀ / I 0.22%
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(Formation of a low refractive index layer)
Using a coater having a throttle die on the light diffusion layer formed as described above, the low refractive index layer coating liquid is directly extruded onto the surface on which the hard coat layer on the backup roll is coated. Then, a low refractive index layer having a thickness of 100 nm was formed and then wound up. In this way, light diffusion films 11 to 13 and 21 to 23 were produced. The drying / curing conditions are shown below.
Drying: Drying at 90 ° C. for 60 seconds.
Curing: Irradiation with an irradiation dose of 400 mJ / cm ² was performed using an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) in an atmosphere with an oxygen concentration of 0.1% by nitrogen purge.

[Examples 1 to 10 and Comparative Examples 1 to 6]
(Preparation of polarizing plate)
A polyvinyl alcohol (PVA) film having a thickness of 80 μm is dyed by immersing it in an aqueous iodine solution having an iodine concentration of 0.05% by mass at 30 ° C. for 60 seconds, and then in an aqueous boric acid solution having a boric acid concentration of 4% by mass. The film was vertically stretched to 5 times the original length while being immersed for 2 seconds, and then dried at 50 ° C. for 4 minutes to obtain a polarizing film having a thickness of 20 μm.
The back surface of each optical film produced (the surface on the side where the optically anisotropic layers 1 to 16 of the films 1 to 16 as the support are not formed) is 1.5 mol / L in an aqueous sodium hydroxide solution at 55 ° C. Then, the sodium hydroxide was thoroughly washed away with water. Then, after being immersed in a diluted sulfuric acid aqueous solution at 35 ° C. for 1 minute at 0.005 mol / L, the diluted sulfuric acid aqueous solution was sufficiently washed away by immersion in water. Finally, the sample was thoroughly dried at 120 ° C.
Each optical film subjected to the saponification treatment as described above is combined with the light diffusion film 11 also subjected to the saponification treatment, and the saponification treatment surface is bonded using a polyvinyl alcohol-based adhesive so as to sandwich the polarizing film, An observer side polarizing plate was obtained.
Moreover, as a polarizing plate on the backlight side of the liquid crystal display device, a polarizing plate was obtained in the same manner using Fujitac TF80UL (manufactured by Fuji Film Co., Ltd.) as a commercially available cellulose acetate film instead of the light diffusion film. At this time, since the polarizing film and the protective films on both sides of the polarizing film are produced in a roll form, the longitudinal directions of the roll films are parallel to each other and are continuously bonded. Therefore, each optical film roll longitudinal direction (film casting direction) was parallel to the polarizer absorption axis.

(Production and evaluation of TN liquid crystal display device)
A TN mode liquid crystal display device having the same configuration as that of FIG. 1 was produced. Specifically, a pair of polarizing plates provided in a liquid crystal display device (AL2216W, manufactured by Nippon Acer Co., Ltd.) using a TN type liquid crystal cell is peeled off, and the observer side and the backlight side prepared above are used instead. The polarizing plates were attached to the viewer side and the backlight side one by one through an adhesive so that each optical film was on the liquid crystal cell side. At this time, the transmission axis of the polarizing plate on the observer side and the transmission axis of the polarizing plate on the backlight side were arranged so as to be orthogonal to each other. In this way, a TN liquid crystal display device was produced. In addition, as a liquid crystal display device that does not use a light diffusion layer, a polarizing plate prepared for use on the backlight side was arranged on both the viewer side and the backlight side to prepare a TN liquid crystal display device.

(Viewing angle measurement method)
About the liquid crystal display device produced in Examples 1-10 and Comparative Examples 1-6, it is a visual field from black display (L0) to white display (L7) using measuring machine "EZ-Contrast160D" (made by ELDIM). The corner was measured. The contrast ratio (white transmittance / black transmittance) at a polar angle of 80 degrees was determined in the vertical and horizontal directions.

From the results shown in the above table, in Examples 1 to 10, the front contrast of the liquid crystal display device using the light diffusing layer 11 is 90% or more with respect to the front contrast of the form in which the light diffusing layer is not used. I knew it would be maintained. On the other hand, in the liquid crystal display devices of Comparative Examples 1 to 6, it was found that the front contrast was less than 90% and the contrast was low.
That is, in the liquid crystal display devices of Examples 1 to 10 of the present invention, it can be understood that a wide viewing angle can be achieved by the light diffusion layer without excessively reducing the front contrast.

[Examples 12 and 21 and Comparative Examples 13, 22, and 23]
Examples 12 and 21 and Comparative Example 13, except that light diffusing films 12 to 13 and 21 to 23 were used in place of the light diffusing film 11 as the observer-side polarizing plate, respectively. 22 and 23 were obtained.

(Production and evaluation of TN liquid crystal display device)
A TN mode liquid crystal display device having the same configuration as that of FIG. 1 was produced. Evaluation was performed similarly to Examples 1-10 and Comparative Examples 1-6.
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Upper CR Lower CR Horizontal CR Front unused Front usage Example 1 Light diffusing film 11 53 104 142 1004 954
Example 12 Light Diffusing Film 12 47 93 132 1004 979
Comparative Example 13 Light Diffusing Film 13 68 129 175 1004 833
Example 21 Light Diffusing Film 21 56 107 149 1004 946
Comparative Example 22 Light Diffusing Film 22 39 70 103 1004 991
Comparative Example 23 Light Diffusing Film 23 62 121 171 1004 784
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From the results shown in the above table, in Examples 1, 12 and 21, the front contrast of the liquid crystal display device using the light diffusing layer is 90% or more with respect to the front contrast of the form in which the light diffusing layer is not used. It was found to maintain. On the other hand, in the liquid crystal display device of Comparative Example 22, although the front contrast is 90% or more, the vertical and horizontal contrasts are low, and a wide viewing angle cannot be achieved. In addition, it was found that the liquid crystal display devices of Comparative Examples 13 and 23 had a low front contrast because the front contrast was less than 90% with respect to the front contrast in the form not using the light diffusion layer.
That is, in the liquid crystal display devices of Examples 12 and 2111 to 23 of the present invention using the light diffusing film whose I ₃₀ / I is 0.01 to 0.2%, the light intensity is reduced without excessively reducing the front contrast. It can be understood that a wide viewing angle can be achieved by the diffusion layer.

(Examples 1-a to 1-g)
In the preparation of the coating liquid used for forming the first optically anisotropic layer of Example 1, 34 parts by mass of discotic liquid crystal compound A shown in the following table and disco instead of 38 parts by mass of discotic liquid crystal compound (1) A first optically anisotropic layer was formed using each coating solution prepared in the same manner except that 4 parts by mass of tick liquid crystal compound B was used. In Table 5, for example, the description “D-112 (Japanese Unexamined Patent Publication No. 2006-76992)” represents Exemplified Compound D-112 described in Japanese Unexamined Patent Publication No. 2006-76992.

Any of the formed first optically anisotropic layers had Re (450) / Re (550) in the range of 0.9 to 1.1, and Re (550) in the range of 20 to 55 nm. It was.
Other than that, each polarizing plate was produced similarly to Example 1, and also each liquid crystal display device was produced and evaluated like Example 1 using the said polarizing plate.
Similarly to the liquid crystal display device of Example 1, the liquid crystal display devices of Examples 1-a to 1-g have a high front contrast with a front contrast of 90% or more with respect to the front contrast of the form not using the light diffusion layer. I knew it would be maintained. More specifically, it was found that in the liquid crystal display devices of Examples 1-a to 1-g of the present invention, wide viewing angle by the light diffusion layer can be achieved without excessively reducing the front contrast.

10, 10a, 10b Polarizing layers 12, 12a, 12b Second optical anisotropic layers 14, 14a, 14b First optical anisotropic layers 16, 16a, 16b Protective film 18 Light diffusing layer P, P ′ Polarizing plate

Claims (9)

A polarizing plate having a polarizing layer, first and second optically anisotropic layers, and a light diffusing layer, wherein the first optically anisotropic layer is a layer formed from a liquid crystal composition, and has a wavelength of 450 nm. The ratio Re (450) / Re (550) of Re (450) at a wavelength of 550 nm to Re (550) is 0.9 to 1.1, and Re (550) of the second optical anisotropic layer is The retardation Rth (550) in the thickness direction at a wavelength of 550 nm is 40 to 100 nm, and the goniophotometer scattered light profile of the light diffusion layer has an emission angle of 0 ° (with respect to the layer surface). The polarizing plate is characterized in that the scattered light intensity in the polar angle 30 ° direction is 0.01 to 0.2% at the azimuth angle at which the scattering intensity is maximum with respect to the light intensity in the normal direction). The polarizing plate according to claim 1, wherein the first optically anisotropic layer is a layer formed from a liquid crystal composition containing at least one discotic liquid crystal compound. The polarizing plate according to claim 1, wherein the at least one discotic liquid crystal compound is a liquid crystal compound represented by the following general formula (DI):

[Where:
Y ¹¹ , Y ¹² and Y ¹³ each independently represent an optionally substituted methine or nitrogen atom;
L ¹ , L ² and L ³ each independently represents a single bond or a divalent linking group;
H ¹ , H ² and H ³ are each independently represented by the general formula (DI-A):

(In the general formula (DI-A),
YA ¹ and YA ² each independently represents a methine or nitrogen atom;
XA represents an oxygen atom, a sulfur atom, methylene or imino;
* Represents the position of bonding to the L ^{1 to} L ³ side in the above general formula (DI);
** represents a position to be bonded to the R ^{1 to} R ³ side in the general formula (DI). )
Or general formula (DI-B):

(In the general formula (DI-B),
YB ¹ and YB ² each independently represent a methine or nitrogen atom;
XB represents an oxygen atom, a sulfur atom, methylene or imino;
* Represents the position of bonding to the L ^{1 to} L ³ side in the above general formula (DI);
** represents a position to be bonded to the R ^{1 to} R ³ side in the general formula (DI). );
R ¹ , R ² and R ³ each independently represents the following general formula (DI-R):
General formula (DI-R)
-(-L ²¹ -Q ² ) _n1 -L ²² -L ²³ -Q ¹
(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 having at least one cyclic structure;
n ¹ represents an integer of 0 to 4, and L ²² represents ** — O—, ** — O—CO—, ** — CO—O—, ** — O—CO—O—, **. -S -, * - N (R ) -, ** - CH 2 -, ** - CH = CH- or ** - C≡C- represent, where ** is a position to bind to Q ² side Represents;
L ²² is **-O-, **-O-CO-, **-CO-O-, **-O-CO-O-, **-S-, **-N (R ¹⁰¹ )-. , ** — CH ₂ —, ** — CH═CH— or ** — C≡C—, R ¹⁰¹ represents an alkyl group having 1 to 5 carbon atoms, and ** binds to the Q ² side. Represents the position;
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 valent linking group;
Q ¹ represents a polymerizable group or a hydrogen atom)
Represents. ] The first optically anisotropic layer contains a compound represented by the following general formula (I) or general formula (II) or derived from a compound represented by the following general formula (I) or (II) The polarizing plate according to claim 1, comprising a polymer containing a repeating unit.

In the formula, L ¹ and L ² each independently represent a single bond or a divalent linking group; A ¹ and A ² each independently represent —O— or —NR— (R represents a hydrogen atom or a substituent). ), -S- and -CO-; R ¹ , R ² and R ³ each independently represents a substituent; X represents a non-metallic atom of Groups 14-16 Provided that a hydrogen atom or a substituent may be bonded to X; n represents an integer of 0 to 2;

In the formula, MG ¹ and MG ² are each independently a liquid crystal core part that induces the expression of a liquid crystal phase composed of 2 to 8 cyclic groups, and the cyclic group constituting the liquid crystal core part is an aromatic group Any of a ring, an aliphatic ring, and a heterocyclic ring; ^one of the cyclic groups constituting MG ¹ and MG ² is substituted with L ¹¹ and L ¹² ; R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ Are flexible substituents, dipole action groups, and hydrogen bonding groups that induce the expression of the liquid crystal phase substituted in the molecular long axis direction of the liquid crystal core; L ¹¹ and L ¹² are each independently , A linking group substituted for the liquid crystal core parts MG ¹ and MG ² , represented by the following formula (II) -LA or formula (II) -LB;

In the formula, * represents a position substituted with the cyclic group constituting MG ¹ ; # represents a position linked to P ¹ ; A ¹¹ , A ¹³ and A ¹⁴ are each independently —O—, —NH—. , -S-, -CH _2- , -CO-, -SO-, or -SO _2- ; A ¹² represents -CH = or -N =; both L ¹¹ and L ¹² are represented by the formula (II ) In the case of a group represented by -LA, the substituent P ¹ is a single bond or a divalent group selected from the group consisting of -CH = CH-, -C≡C-, 1,4-phenylene and combinations thereof. In the case where one of L ¹¹ and L ¹² is a group represented by the formula (II) -LB and the other is a group represented by the formula (II) -LA, the substituent P ¹ is represented by * = CH-P ¹¹ - #, or * = N-P ¹¹ - represented by # (* represents a linking position between the groups of the formula (II) -LB, # in formula (II) -LA Group represented Represents the coupling position); P ¹¹ is a single bond, or a -CH = CH -, - C≡C-, represents a 1,4-phenylene and a divalent linking group selected from the combination; L ¹¹ and L ¹² Are both groups represented by the formula (II) -LB, the substituent P ¹ is a double bond, ═CH—P ¹¹ —CH═, ═N—P ¹¹ —CH═, ═N—P ^11. -N =; P ¹¹ has the same meaning as P ¹¹ above. The polarizing plate according to any one of claims 1 to 4, wherein the second optically anisotropic layer is a cellulose acylate film. The polarizing plate according to claim 1, wherein the second optically anisotropic layer is a cycloolefin polymer film or a polycarbonate film. The crossing angle between the slow axis in the plane of the second optically anisotropic layer and the transmission axis in the plane of the polarizing layer is 0 degree. The polarizing plate as described in. A pair of opposed substrates having electrodes on at least one of the substrates, and a nematic liquid crystal material sandwiched between the pair of substrates, and the liquid crystal molecules of the nematic liquid crystal material with respect to the surfaces of the pair of substrates during black display A liquid crystal cell having a liquid crystal layer oriented substantially vertically and having a product Δn · d of a thickness d (micron) and a refractive index anisotropy Δn of 0.1 to 1.5 μm, and A liquid crystal display device comprising the polarizing plate according to claim 1. The liquid crystal display device according to claim 8, wherein the polarizing plate is a polarizing plate disposed on a display surface side with respect to the liquid crystal cell.

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