KR101767854B1 - Phase Difference Plate, Elliptically Polarizing Plate and Display Device Using the Same - Google Patents

Abstract

There is provided a phase difference plate comprising a single-layer film having an extraordinary ray refraction index ne or a birefringence? N of "negative dispersion" while suppressing a decrease in transmittance to a minimum. A retardation film according to the present invention is a retardation film comprising a film comprising an organic polymer and at least one kind of dichroic dye, wherein the retardation of the retardation film is DELTA na da, Wherein the retardation film satisfies the following formula (1) when? Nb · db is the retardation of the retardation film made of a film.
(580) /? N? Da (550) - ?? nb 占 db (580) /? Nb 占 db (550)
(Where retardation is represented by the product of the birefringence Δn of the retarder and the film thickness d of the retarder, and Δna da (580) and Δnb · db (580) are the retardation of each retarder at a wavelength of 580 nm , And? Na da (550) and? Nb 占 db (550) are the retardations of the respective retardation plates at a wavelength of 550 nm).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a phase difference plate, an elliptically polarizing plate,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retarder used for a liquid crystal display device, an organic electroluminescence display device, and the like, and an image display device such as a liquid crystal display device and an organic electroluminescence display device using the same.

The retardation plate is an optical element used for obtaining polarized light (linearly polarized light, circularly polarized elliptically polarized light). The retardation plate can be used for color compensation of a liquid crystal display device, for use in a viewing angle improving film, use of an antireflection film for an organic EL display device in which a polarizing plate and a 1/4 wave plate are combined or a cholesteric liquid crystal, Or a reflection type polarizing plate for reflecting only one of the circularly polarized light in the direction of the light. As the retardation plate, a plate in which an inorganic material (calcite, mica, crystal) is sliced, a stretched film made of a polymer material having a high intrinsic birefringence, or a film in which rod or disk liquid crystal material is aligned and fixed in a liquid crystal state is used.

As a typical retardation plate, a 1/4 wavelength plate having a retardation corresponding to 1/4 of a wavelength or a 1/2 wavelength plate having a retardation corresponding to 1/2 of a wavelength is known. The quarter wave plate has an optical function of converting linearly polarized light into circularly polarized light. The 1/2 wave plate has a function of converting the polarization plane of linearly polarized light to 90 degrees.

The phase difference plate is usually designed to give necessary optical function to light (monochromatic light) of a specific wavelength. In a 1/4 wavelength plate used in a color compensation film for a liquid crystal display device or an antireflection film for an organic EL display device, in a wavelength range of 400 to 700 nm, preferably 400 to 780 nm, It is necessary to have a function of converting linearly polarized light into circularly polarized light and converting circularly polarized light into linearly polarized light. (Ideal) of the retardation plate when the phase difference is 1/4 wavelength of the measurement wavelength, that is,? / 4 (nm) at a measurement wavelength of 400 to 700 nm, preferably 400 to 780 nm, to be.

Generally, the above-described retardation plate material or the like is used as a 1/4 wavelength plate, but these materials have a wavelength dispersion (wavelength dependence) in retardation. Here, a dispersion characteristic in which a phase difference is larger and a phase difference is smaller in a shorter wavelength is defined as a "positive dispersion ", a dispersion characteristic in which a phase difference is smaller in a shorter wavelength and a phase difference is larger in a longer wavelength, " 1 shows the wavelength dispersion characteristics of the birefringence (? N (?)) Of each wavelength in the visible light region normalized by setting the birefringence value? N (550 nm) at a measurement wavelength of 550 nm to be 1. Generally, as shown by the solid line in Fig. 1, the birefringence of the polymer film becomes larger as the measurement wavelength becomes shorter, and becomes smaller as the longer wavelength becomes longer. That is, "positive dispersion ". On the other hand, the ideal 1/4 wavelength plate has a "negative dispersion" characteristic in which the birefringence becomes larger as the measurement wavelength becomes longer, as shown by the dotted line in FIG. 1, since the birefringence is proportional to the measurement wavelength. Therefore, it is difficult to obtain an ideal "negative dispersion" characteristic at a measurement wavelength? Of 400 to 700 nm with only one polymer film. When such a retardation film made of a general polymer film having a "positive dispersion" property is applied to a white light in which light in a visible light region is mixed, a distribution of polarization states occurs at each wavelength and a colored polarized light is generated .

JP-A-10-68816 (Patent Document 1) and JP-A-10-90521 (Patent Document 2) disclose a retardation plate in which two polymer films having optical anisotropy are laminated have. The retardation plate described in Patent Document 1 is a retardation plate having a 1/4 wavelength plate in which the retardation of birefringent light is 1/4 wavelength and a 1/2 wavelength plate in which the phase difference is 1/2 wavelength of birefringence light, will be. The retardation plate described in Patent Document 2 is formed by laminating at least two retardation plates having optical retardation values of 160 to 320 nm so that their slow axes are not parallel and orthogonal to each other.

In addition, the relationship of Japanese Patent Publication Laid-Open Patent Publication No. 11-52131 (Patent Document 3), the birefringence wavelength dispersion values of Δn α (α = Δn (450nm ) / Δn (650nm)) is α _A <α _B A birefringent medium comprising two birefringent media laminated in a direction orthogonal to each of the slow axes, the birefringent medium being made of a liquid crystal compound having at least one of the birefringent media in a molecular alignment state in a parallel alignment (homogeneous orientation) And the retardation R is R _A &gt; R _B , and the wavelength dispersion value? Is smaller than 1.

The retardation plates disclosed in the above-mentioned Patent Documents 1 to 3 are all formed by laminating two birefringent media. By using such a laminate retardation plate, a 1/4 wavelength plate can be achieved in a wide wavelength region. However, in order to produce the retarder described in Patent Document 1 and Patent Document 2, a complicated process of adjusting the optical direction (optical axis or slow axis) of the two polymer films is required. The optical direction of the polymer film generally corresponds to the longitudinal direction or the transverse direction of the sheet-like or roll-shaped film. A polymer film having an optical axis or a slow axis in the diagonal direction of a sheet or a roll is difficult to produce industrially. Therefore, in the above-mentioned process of preparing the optical direction, in adjusting the optical direction of the two polymer films to an angle that is neither parallel nor orthogonal, it is necessary to stick chips that can be obtained by cutting two kinds of polymer films at a predetermined angle . If a retarder is manufactured by sticking chips, the process becomes complicated, quality deterioration due to shaft misalignment tends to easily occur, and the yield is lowered, which not only increases manufacturing cost but also causes deterioration due to contamination easy to do. Further, in the polymer film, it is also difficult to strictly control the optical retardation value.

The reason for the birefringence wavelength dispersion of the rod-like molecules having anisotropy is that the two refractive indexes ne and no of the anisotropic molecule are changed more rapidly than the no, toward the short wavelength side of the visible wavelength spectrum as shown in Fig. 2 . Where ne is the "extraordinary ray refraction index" in the direction parallel to the long molecular axis and no is the "normal ray refraction index" in the direction perpendicular to the long molecular axis. Fig. 3 shows the relationship of the refractive index of the rod-like molecules 1 in the polymer film 2. Fig. This is because, in the case of rod-shaped molecules having anisotropy, a functional group having a conjugated double bond in the long axis direction of the molecule is oriented, so that the refractive index (abnormal ray refraction index ne) in the long axis direction is absorbed in the ultraviolet region close to the visible light region And the refractive index (the normal ray refraction index) in the minor axis direction has a relatively gentle curve, while the refractive index changes rapidly toward the short wavelength side of the visible wavelength spectrum.

One way to further refine the "positive dispersion" characteristic of birefringence is to design the molecule to increase the positive dispersion of ne and reduce the positive dispersion of no, as shown in FIG. For example, a rod-like molecular structure having absorption in an ultraviolet region closer to the visible light region may be designed, or a method in which a dye having absorption in an ultraviolet region is mixed with a polymer may be considered. Japanese Patent Application Laid-Open No. 2000-314885 (Patent Document 4) discloses a retarder capable of arbitrarily controlling the wavelength dispersion characteristics by mixing an additive that affects the wavelength dispersion characteristics of retardation in a polymer. The retardation plate described in Patent Document 4 is designed so that the dye is oriented in the major axis direction of the rod-like molecules by adding a dye absorbed in the ultraviolet region so that the short wavelength region changes more sharply than the original extraordinary ray refractive index. Document 4 also specifies that the "positive dispersion" However, as a method of imparting the "negative dispersion" characteristic, only a method of overlapping two polymer films to which a dye is added orthogonally is disclosed.

On the other hand, as a method of obtaining the "negative dispersion" characteristic in which the birefringence becomes as large as the long wavelength, it is conceivable to design the molecule so as to increase the positive dispersion of no and decrease the positive dispersion of ne Currently, no such materials have been found.

As another method of obtaining the "negative dispersion " characteristic in which the birefringence becomes as long as the long wavelength, it has been proposed in the prior art to mix a birefringent material having a positive birefringence wavelength dispersion property and a compound made of a negative birefringent material. , A phase difference plate having "negative dispersion &quot; property can be obtained as a single film.

For example, Japanese Patent Application Laid-Open No. 2002-48919 (Patent Document 5) discloses an optical film comprising a mixture or copolymer film of at least two kinds of organic polymers composed of an organic polymer having positive birefringence and an organic polymer having negative birefringence Discloses that a retardation film having a "negative dispersion " property can be realized by using a single film as a retardation film formed by uniaxially stretching the retardation film described in Patent Document 5. The retardation film described in Patent Document 5 is a schematic view shown in Fig. (1) of the organic polymer having the "positive birefringence" (the rod-shaped molecule 1 in FIG. 5), the birefringence Of the organic polymer having the "negative birefringence" (the discotic molecule 3 in Fig. 5) has an extraordinary ray refractive index ne2 and an ordinary ray refractive index no2 Here, when the birefringence DELTA n1 of the organic polymer having the "positive birefringence" is larger than the birefringence DELTA n2 of the organic polymer having the "negative birefringence " (I.e., in the case of? N1>? N2), the total birefringence? N =? N1 +? N2> 0 is obtained, and the mixture becomes "positive birefringence".

The wavelength dispersion characteristics D1 of the birefringence? N1 of the organic polymer having the "positive birefringence" is represented by D1 =? N1 (450) /? N1 650 where? N1 (450) and? N1 (650) D2 =? N2 (450) /? N2 (650) where? N2 (450) represents the birefringence of the polymer film at 650 nm, and D2 represents the wavelength dispersion characteristic D2 of birefringence? N2 of the organic polymer having "negative birefringence" And? N2 (650) are defined as the birefringence of the polymer film at the measurement wavelength of 450 nm and 650 nm, respectively), the wavelength dispersion characteristics D2 of the organic polymer having the "negative birefringence" (Positive birefringence) and a negative birefringence (birefringence), the birefringence of the positive birefringence and the negative birefringence are set to be larger than the wavelength dispersion characteristics D1 of the organic polymer having the positive birefringence Can be obtained.

However, since the retardation film obtained by uniaxially stretching the copolymer film has a very small birefringence? N, it is necessary to increase the thickness to 50 to 200 占 퐉 in order to impart a 1/4 wavelength plate characteristic. In recent years, a retardation plate used for a liquid crystal display or an organic EL display has been required to be thin, and a polymer elongation film having a small birefringence? N has been required to be improved in terms of film thickness.

Japanese Patent Application Laid-Open No. 2002-267838 (Patent Document 6) discloses a liquid crystal film composed of a rod-shaped liquid crystal compound as a thin film and a retardation plate having a birefringence that increases as the measurement wavelength becomes longer. The retardation film described in Patent Document 6 is obtained by aligning a compound having two or more kinds of mesogen groups and a liquid crystal compound containing rod-shaped liquid crystal molecules in parallel and arranging at least one kind of mesogen group in the direction of the optical axis of the rod- And is oriented in an orthogonal direction. The rod-shaped liquid crystal compound has a thickness of several micrometers, which is advantageous from the viewpoint of thinning of the retarder, because the birefringence Δn of the rod-like liquid crystal compound is comparatively large as compared with the copolymer resin.

Patent Document 1: JP-A-10-68816 Patent Document 2: JP-A-10-90521 Patent Document 3: Japanese Patent Application Laid-Open No. 11-52131 Patent Document 4: JP-A-2000-314885 Patent Document 5: JP-A-2002-48919 Patent Document 6: JP-A-2002-267838

However, with the methods proposed in Patent Documents 5 and 6, it is difficult to obtain a characteristic in which the retardation becomes a quarter wavelength of the measurement wavelength in a region of a wide band of 400 to 700 nm in wavelength, which is a visible light region, , As shown in Fig. 7, the long wavelength side tends to deviate from the ideal straight line in particular. This is due to the fact that the slope of the curve on the longer wavelength side is different from the curve on the shorter wavelength side than the central wavelength of visible light of 550 nm, as can be seen from the birefringence wavelength dispersion curve shown in Fig. Therefore, in order to obtain an ideal wavelength dispersion characteristic in a wide band region of a wavelength of 400 to 700 nm, which is a visible light region, a wavelength of 400 to 700 nm, a curve on the short wavelength side is made close to an ideal straight line It is necessary to make an attempt.

The inventors of the present invention have found that by mixing at least one kind of dichroic dye into an organic polymer, it is possible to obtain a liquid crystal display device having a "negative dispersion" characteristic in which the extraordinary ray refraction index ne becomes larger as the measurement wavelength becomes longer in at least a part of the wavelength region of the visible light region A new retardation plate can be realized. In addition, by optimizing the birefringence wavelength dispersion characteristics of the polymerizable liquid crystal compound and the maximum absorption wavelength and mixing amount of the dichroic dye, and optimizing the film forming conditions, it is possible to obtain the birefringence Δn in the wavelength region of at least a part of the visible light region, It was found that a novel phase difference plate having "negative dispersion" characteristics can be obtained which becomes larger as the measurement wavelength becomes longer. The present invention is based on this finding.

Accordingly, it is an object of the present invention to provide a retarder comprising a single-layer film having an extraordinary ray refraction index ne or a birefringence? N of "negative dispersion" characteristics while suppressing a decrease in transmittance to a minimum.

Another object of the present invention is to provide an image display apparatus such as a liquid crystal display device and an organic electroluminescence display device having an elliptically polarizing plate having the retardation plate and an elliptically polarizing plate.

A retardation film according to the present invention is a retardation film comprising a film comprising an organic polymer and at least one dichroic dye,

The retardation of the retarder is represented by? Na da,

The retardation of the retardation film made of the film excluding the dichroic dye from the film was defined as? Nb · db

The retardation plate satisfies the following formula (1).

   ? Na da (580) /? Na da (550) -

? Nb · db (580) /? Nb · db (550)> 0 (1)

(Where retardation is represented by the product of the birefringence Δn of the retarder and the film thickness d of the retarder, and Δna da (580) and Δnb · db (580) are the retardation of each retarder at a wavelength of 580 nm , And? Na da (550) and? Nb 占 db (550) are the retardations of the respective retardation plates at a wavelength of 550 nm).

In the retarder according to the present invention, the extraordinary ray refraction index ne or the birefringence index n may have a "negative dispersion" property in which at least a part of the wavelength region of the visible light region has a larger measurement wavelength.

In the retarder according to the present invention, both of the extraordinary ray refraction index ne and the birefringence? N may have a "negative dispersion" characteristic in which the longer the measurement wavelength becomes, the longer the wavelength range of at least a part of the visible light region.

In the retarder according to the present invention, the retardation ratio of the retarder at a specific wavelength may satisfy the following expressions (2) and (3).

   0.70 <? N d (450) /? N d 550 <1.00 (2)

   1.00 <? N d (650) /? N? D 550 <1.30 (3)

(650) is retardation of each retardation plate at wavelengths of 450 nm, 550 nm, and 650 nm, respectively). Here, Δn · d (450), Δn · d (550)

In the retarder according to the present invention, the retardation ratio of the retarder at a specific wavelength may satisfy the following expressions (4) and (5).

   0.80 <? N d (500) /? N? D 550 <1.10 (4)

   1.00 <? N d (580) /? N? D (550) <1.15 (5)

(500),? N d (550) and? N d (580) are the retardations of the retarder at wavelengths of 500 nm, 550 nm and 580 nm, respectively.

In the retarder according to the present invention, the birefringence of the organic polymer may have a "negative dispersion" property.

In the retarder according to the present invention, the organic polymer may be obtained by polymerizing the polymerizable liquid crystal compound in a predetermined liquid crystal alignment state, and the liquid crystal alignment may be parallel alignment.

In the retarder according to the present invention, the organic polymer may be a mixture or copolymer of at least two kinds of organic polymers composed of an organic polymer having a positive birefringence and an organic polymer having a negative birefringence.

In the retarder according to the present invention, the film may be stretched.

In the retarder according to the present invention, the absorption maximum wavelength of the dichroic dye may be in the range of 380 to 780 nm of the measurement wavelength.

In the retarder according to the present invention, the absorption maximum wavelength of the dichroic dye may be different from the absorption maximum wavelength of the emission spectrum of the image display apparatus.

As another aspect of the present invention, there is provided an elliptically polarizing plate having a retarder and a polarizing plate, and an image display apparatus having the elliptically polarizing plate.

The image display apparatus according to another aspect of the present invention may be a liquid crystal display apparatus or an organic electroluminescence display apparatus.

According to the present invention, by mixing at least one kind of dichroic dye into the organic polymer so as to satisfy the formula (1), the extraordinary ray refraction index ne is increased in at least a part of the wavelength region of the visible light region, Negative retardation "property can be realized.

Further, according to the present invention, by optimizing the birefringence wavelength dispersion property, the dichroic dye absorption maximum wavelength, and the mixing amount of the polymerizable liquid crystal composition and optimizing the film forming conditions, the birefringence? It is possible to realize a phase difference plate having "negative dispersion"

According to the present invention, the retardation plate having the above-described birefringent wavelength dispersion property and having a retardation of 1/4 wavelength at a measurement wavelength of 550 nm is characterized in that circularly polarized light is linearly polarized in a wide wavelength region, It is possible to improve the brightness, contrast ratio, and the like when used in a liquid crystal display device, and to provide an organic electroluminescent display device that exhibits a high anti-reflection performance against mirror-surface reflection The contrast is greatly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a comparison between the wavelength dispersion of the ordinary birefringence Δn and a general polymer film.
Fig. 2 is a graph showing comparison of wavelength dispersion of an extraordinary ray refraction index ne and an ordinary ray refraction index no of an anisotropic rod-shaped molecule. Fig.
3 is a view showing a polymer film 2 comprising an organic polymer (rod-like molecule) 1 having positive birefringence.
Fig. 4 is a graph showing a comparison between the wavelength dispersion of the extraordinary ray refraction index ne of the rod-like molecule and the refractive index no of the phase ray index for explaining a method of further polymerizing the "positive dispersion" characteristic of birefringence.
5 is a view showing a polymer film 2 comprising an organic polymer (rod-shaped molecule) 1 having positive birefringence and an organic polymer (disc-shaped molecule) 3 having negative birefringence.
FIG. 6 is a view for explaining that a birefringence "negative dispersion" characteristic is expressed by a polymer film comprising an organic polymer having a positive birefringence and an organic polymer having a negative birefringence.
7 is a diagram showing a comparison between a birefringence wavelength dispersion and a retardation plate having a "negative dispersion" characteristic.
Fig. 8 is a graph showing wavelength dispersion characteristics of refractive index and absorption coefficient of organic molecules. Fig.
FIG. 9 is an enlarged view of the ideal dispersion region of FIG. 8;
10 is a view showing a comparison of wavelength dispersion of the extraordinary ray refraction index ne and the phase ray index of ref before and after adding the dichroic dye to the organic polymer having anisotropy.
11 is a diagram showing a comparison between the absorption spectrum in the major axis direction (ne direction) and the minor axis direction (no direction) of the dye molecules of the dichroic dye.
12 is a view showing a comparison with the wavelength dispersion of birefringence Δn before and after the addition of a dichroic dye to an organic polymer having anisotropy.
[Fig. 13] Fig. 13 is a diagram of the luminescence spectrum when the organic electroluminescence display device is illuminated simultaneously with the emission spectrum of the red, green and blue colors of three colors.
14 is a diagram showing the wavelength dispersion characteristics of the extraordinary ray refraction index ne and the phase ray index of refinity no of the liquid crystal film produced in Example 1. Fig.
15 is a diagram showing the wavelength dispersion characteristics of the birefringence? N of the liquid crystal film produced in Example 1. FIG.
16 is a graph showing the wavelength dispersion characteristics of the extraordinary ray refraction index ne and the phase ray index of refinity no of the liquid crystal film produced in Example 2. Fig.
17 is a view showing the wavelength dispersion characteristics of the birefringence? N of the liquid crystal film produced in Example 2. FIG.
18 is a diagram showing the wavelength dispersion characteristics of the extraordinary ray refraction index ne and the phase ray index of refinity no of the liquid crystal film produced in Example 3. Fig.
19 is a diagram showing the wavelength dispersion characteristics of the birefringence? N of the liquid crystal film produced in Example 3. Fig.
20 shows the wavelength dispersion characteristics of the birefringence? N of the liquid crystal film produced in Example 4. FIG.
21 shows the wavelength dispersion characteristics of the birefringence? N of the liquid crystal film produced in Example 5. FIG.
22 is a diagram showing the wavelength dispersion characteristics of the birefringence? N of the liquid crystal film produced in Example 6. Fig.
23 is a diagram showing the wavelength dispersion characteristics of the extraordinary ray refraction index ne and the phase ray index of refinity no of the liquid crystal film produced in Comparative Example 1. FIG.
24 is a diagram showing the wavelength dispersion characteristics of the birefringence? N of the liquid crystal film produced in Comparative Example 1. FIG.
25 is a diagram showing the wavelength dispersion characteristics of the extraordinary ray refraction index ne and the phase ray index of refinity no of the liquid crystal film produced in Comparative Example 2. FIG.
26 is a diagram showing the wavelength dispersion characteristics of the birefringence? N of the liquid crystal film produced in Comparative Example 2. FIG.
27 is a graph showing the wavelength dispersion characteristics of the extraordinary ray refraction index ne and the phase ray index of refinity no of the liquid crystal film produced in Comparative Example 3. FIG.
28 is a view showing the wavelength dispersion characteristics of the birefringence? N of the liquid crystal film produced in Comparative Example 3. Fig.

A retardation film according to the present invention is a retardation film comprising a film comprising an organic polymer and at least one dichroic dye,

The retardation of the retarder is represented by? Na da,

The retardation of the retardation film made of the film excluding the dichroic dye from the film was defined as? Nb · db

, The following formula (1) is satisfied.

? Na da (580) /? Na da (550) -

? Nb · db (580) /? Nb · db (550)> 0 (1)

(Where retardation is represented by the product of the birefringence Δn of the retarder and the film thickness d of the retarder, and Δna da (580) and Δnb · db (580) are the retardation of each retarder at a wavelength of 580 nm , And? Na da (550) and? Nb 占 db (550) are the retardations of the respective retardation plates at a wavelength of 550 nm).

Before describing the retarder of the present invention, the difference between the conventional retarder and the retarder of the present invention will be described.

[Comparison with Conventional Phase Difference Plate]

First, the refractive index wavelength dispersion characteristics of the organic polymer will be described with reference to FIG.

Hereinafter, the refractive index is expressed by a complex number N = n-ik (where n is a real number of N and is usually called a "refractive index. &Quot;) k (imaginary part of N) ) Is represented by k =? / (4?) As a function of wavelength? (?) And is related to an absorption coefficient).

In general, the refractive index n of the organic polymer in a region (regions a1, a2, a3 in Fig. 8) deviated from the intrinsic absorption wavelength is monotonically decreased at the same time as the wavelength increases. This dispersion is called "normal dispersion ", where k = 0 in this dispersion region. On the other hand, the refractive index n in the wavelength range including the intrinsic absorption (regions b1, b2 and b3 in FIG. 8) increases rapidly as the wavelength increases. Such dispersion is referred to as "ideal dispersion ". In the present specification, "normal dispersion" is referred to as "positive dispersion" and "ideal dispersion" as "negative dispersion".

Since the conventional retardation plate does not have absorption in the visible light region, the curve of the extraordinary ray refraction index ne and the index of the phase ray refraction index no both have a "positive dispersion" property in the visible light region. Therefore, in the prior art proposed as a method of obtaining the "negative dispersion" characteristic in which the birefringence becomes longer, the copolymer or mixture of the organic polymer having the "positive birefringence" and the organic polymer having the "negative birefringence" Has an extraordinary ray refractive index ne and an ordinary ray refractive index no having "positive dispersion"

On the other hand, in the present invention, by adding a dichroic dye having absorption in the visible light region to an organic polymer having a refractive index of "positive dispersion", it is possible to prevent the dichroic dye from being added in at least a part of the wavelength region of the visible light region The design concept is fundamentally different from the prior art in that the extraordinary ray refraction index ne is a retardation plate having "negative dispersion"

[Phase difference plate of the present invention]

A retardation film according to the present invention is a retardation film made of a film comprising an organic polymer and at least one kind of dichroic dye, and is a novel retardation film having retardation characteristics satisfying the above formula (1). In the present invention, the retardation ratio at a predetermined wavelength of a retardation film made of a film containing a dichroic dye is made larger than a retardation ratio at a predetermined wavelength of a retardation film made of a film not containing a dichroic dye, It is possible to realize a retarder in which the extraordinary ray refraction index ne or the birefringence? N has a "negative dispersion" property even in the case of a retardation film made of a film. When the retardation plate does not satisfy the above formula (1), the birefringence wavelength dispersion property becomes insufficient, and display characteristics (contrast, color) when mounted on a liquid crystal display device and antireflection performance There is a possibility that trouble may occur.

The retarder according to the present invention is a retardation plate having an extraordinary ray refraction index ne or a birefringence index? N in the wavelength region of at least part of the visible light region having the "negative dispersion" property. A method of designing the extraordinary ray refraction index ne or the birefringence index DELTA n having the "negative dispersion" characteristic which is a characteristic of the retarder according to the present invention will be described.

A film obtained by uniaxially stretching a mixture or copolymer film of an organic polymer having a birefringence amount and an organic polymer having negative birefringence as exemplified in the above Patent Document 5, In the liquid crystal film comprising the compound having two or more kinds of mesogen groups and the liquid crystal compound including the rod-like liquid crystal molecules, the retardation plate having the "positive birefringence" or "negative dispersion" characteristics as shown in FIG. However, generally, as shown in Fig. 7, the longer wavelength side tends to deviate from the ideal straight line due to the difference in the slope of the curve on the longer wavelength side from the curve on the shorter wavelength side than the central wavelength of visible light of 550 nm. Therefore, in order to approximate ideal wavelength dispersion characteristics in a wide band region of a measurement wavelength of 400 to 700 nm, which is a visible light region, a curve on the long wavelength side is shifted to an ideal straight line while keeping the curve on the short wavelength side close to the ideal straight line. You need an attempt to get closer. In the present invention, in view of the above situation, attention has been paid to the "negative dispersion" characteristic attributable to the ideal dispersion region of the organic polymer.

Fig. 9 shows an enlarged view of the curve of the "ideal dispersion area" in Fig. Assuming a symmetric absorption band, in the "ideal dispersion region ", the contribution of the ideal dispersion is approximately zero at the maximum absorption value, and the local maximum value of the refractive index is the half wave height value of the absorption band on the long wavelength side. And a local minimum value of the refractive index appears immediately after the half wave cantilever on the short wavelength side. These positions are shown in Fig. 9 as? Max,? +,? -. Namely, there is a so-called "negative dispersion" characteristic in which the refractive index becomes larger as the wavelength becomes longer in the range from? - to? +.

Next, the design concept of the present invention will be described with reference to Figs. 10 and 11. Fig.

Generally, in the case of an organic polymer having anisotropy, since the kind of the dipole differs depending on the axial direction, as indicated by the thin line (ne line, no dotted line) in Fig. 10, the extraordinary ray refractive index ne and the phase ray refractive index no Represents a different "positive dispersion" curve. When a dye exhibiting a high dichroism having an absorption spectrum having an absorption maximum wavelength at 580 nm as shown in Fig. 11 is added to this organic polymer, the extraordinary ray refraction index ne in the wavelength range of 550 to 650 nm near the absorption wavelength It is possible to obtain a phase difference plate having the "negative dispersion" property. Here, the high dichroism means that the difference between the dichroic dye absorption characteristics in the ne direction and the no direction of the organic polymer is large. Fig. 12 shows birefringence wavelength dispersion characteristics of a retardation plate made of an organic polymer before and after the addition of a dichroic dye. It can be seen that by adding a dichroic dye, a retarder having birefringence of "negative dispersion" can be obtained in the wavelength range of 550 to 650 nm.

From the above, it can be seen that, by adding a dichroic dye having an ideal dispersion region to a material (organic polymer) having a birefringence characteristic of "negative dispersion", the birefringence in the propagation region of visible light, Negative retardation "property can be obtained.

Fig. 12 shows data obtained by adding a dichroic dye to an organic polymer having birefringence of "positive dispersion ". By adding a dichroic dye to a retarder having birefringence of "negative dispersion" characteristics as described in the above Patent Documents 5 and 6, it is possible to obtain a retarder having a "negative dispersion" property in a wide visible light region Can be obtained.

For example, the retarder having the "negative dispersion" characteristic shown in Fig. 7 has a state near relatively ideal straight line on the shorter wavelength side than the central wavelength of visible light of 550 nm, but on the longer wavelength side than 550 nm, There is a tendency to deviate greatly. By adding a high dichroic dye having an absorption maximum in the visible light region to such a retardation plate and orienting it, it becomes possible to have a dispersion characteristic close to an abnormal straight line on the long wavelength side while maintaining the wavelength dispersion property on the short wavelength side .

In the above-described Patent Document 4, as an additive, a dye having absorption in the ultraviolet region, a dye having absorption in the infrared region, and a dye having absorption in the visible region are taken as examples. Designing with a dye having absorption in the ultraviolet region is explained However, there is no mention in the patent document 4 regarding the design concept of the present invention that the extraordinary ray refraction index ne having the "negative dispersion" property is designed. Further, adding a coloring material causes coloration of the retardation plate, which is a problem for a retardation plate material which is required to be transparent in visible light, but Patent Document 4 does not mention any method for avoiding these problems.

The retardation plate according to the present invention has a "negative dispersion" property in which the extraordinary ray refraction index ne or the birefringence index n becomes larger in a wavelength region of at least a part of the visible light region as the measurement wavelength becomes longer. Here, the visible light region generally indicates a wavelength range of 380 nm to 780 nm, but a region having a refractive index ne in the vicinity of 550 nm of the center wavelength of the visible light is preferable as the region exhibiting the "negative dispersion" property. This is because the vicinity of 555 nm is considered to be the maximum in the light where the human eye senses the brightness per wavelength (hereinafter, referred to as the invisibility sensitivity) and 507 nm in the dark.

In general, it is preferable that the refractive index ne of the extraordinary ray is larger at longer wavelengths over the visible light propagation field, but it is not preferable from the standpoint of coloration of the retardation plate because it is necessary to increase the addition amount of the coloring material as described later. Further, in consideration of human non-viscous sensitivity characteristics, it is possible to obtain sufficiently desired characteristics if it can have a "negative dispersion" property within a wavelength range of 550 to 650 nm, preferably a wavelength of 550 to 600 nm.

The retardation plate according to the present invention is characterized in that the birefringence Δn has a "negative dispersion" characteristic in which the longer the measurement wavelength is, the larger the wavelength dispersion is in at least a part of the wavelength region of the visible light region. More specifically, the retardation (the product of the birefringence Δn and the film thickness d of the retardation plate) of the retardation plate at wavelengths of 450 nm, 550 nm and 650 nm is expressed as Δn · d (450), Δn · d (550) d (650), it is preferable that the following formulas (2) and (3) are satisfied.

  0.70 <? N d (450) /? N d 550 <1.00 (2)

  1.00 <? N d (650) /? N? D 550 <1.30 (3)

More preferably, the following formulas (1-1) and (2-1) are satisfied.

  0.80 <? N d (450) /? N? D (550) <O.95 (2-1)

  1.02 <? N d (650) /? N? D 550 <1.20 (3-1)

Considering the non-sensitivity characteristics, the retardation (the product of the birefringence? N and the thickness d of the retardation film) of the retardation plate at wavelengths of 500 nm, 550 nm and 580 nm at a more preferable measurement wavelength of 550 nm to 580 nm is? (4) and (5) in the case where d (500),? N d (550) and? N d (580) are satisfied.

  0.80 <? N d (500) /? N? D 550 <1.10 (4)

  1.00 <? N d (580) /? N? D (550) <1.15 (5)

More preferably, the following formulas (3-1) and (4-1) are satisfied.

  0.85 <? N d (500) /? N? D 550 <1.05 (4-1)

  1.02 <? N d (580) /? N d 550 <1.12 (5-1)

When the retardation of the retardation plate is out of the above range, for example, when it is used as a quarter-wave plate, when the linearly polarized light of 400 to 700 nm enters the film, , There is a case where the circularly polarized light is deviated greatly from the circularly polarized light at other wavelengths.

The retardation plate may be required not only to have a thickness but also to have a specific retardation value depending on its use and the like. Here, the retardation value? N · d of the retardation plate is preferably 20 nm to 450 nm (more preferably 50 nm to 300 nm). In the present specification, the "retardation value (n d)" is a retardation value for light having a wavelength of 550 nm. The retardation value can be measured by a conventionally known method. For example, a device capable of measuring birefringence (e.g., Axoscan manufactured by Axometrix, KOBRA-21ADH manufactured by Oji Keiko Co., Ltd.) Etc.).

The retardation film according to the present invention comprises a film comprising an organic polymer and at least one dichroic dye. For example, the retardation film may be formed by forming a mixture of a polymer and a dichroic dye in a film, A mixture containing a liquid crystal compound and a dichroic dye may be applied to an alignment film or the like to form a film by fixing the alignment of the liquid crystal compound in a predetermined liquid crystal alignment state. Hereinafter, the dichroic dye and the organic polymer used in the retarder according to the present invention will be described.

[Dichromatic dye]

First, the dichroic dye used in the present invention will be described. The dichroic dye referred to here refers to a dye having a property that the absorbance in the major axis direction of the molecule is different from the absorbance in the minor axis direction. The dichroic dye is not particularly limited as long as it has such properties, and it may be a dye or a pigment. A plurality of dyes may be used, a plurality of dyes may be used, or a combination of dyes and pigments may be used. Such a dichroic dye may have a polymerizable functional group or may have liquid crystallinity. As the polymerizable functional group, an acrylic group, a methacrylic group, a vinyl group, a vinyloxy group, an epoxy group, and an oxetanyl group are preferable, and an acrylic group, an epoxy group and an oxetanyl group are particularly preferable from the viewpoint of reactivity. Regarding liquid crystallinity, it is preferable to have a nematic phase and a smectic phase.

The dichroic dye preferably has a maximum absorption wavelength (? Max) in a range of 400 to 800 nm, and more preferably 450 to 700 nm. When the retarder of the present invention is applied to an image display apparatus, It is preferable to select the absorption maximum wavelength which is different from the absorption maximum wavelength of the emission spectrum of the image display apparatus.

Fig. 13 shows the luminescence spectra of the organic electroluminescence display device when white display is performed by simultaneously lighting the three red emission colors of three red colors. As shown in Fig. 13, the blue color has an emission spectrum showing a maximum value at about 460 nm, a green color at 530 nm, and a red color at 630 nm. When the retarder of the present invention is applied to an organic electroluminescence display device, absorption by a dichroic dye is inevitable, but in order to suppress the decrease in transmittance due to the absorption to a minimum, It is preferable to select a dichroic dye having the maximum absorption at a wavelength deviated from the wavelength. For example, it is preferable to apply a dichroic dye having a maximum absorption wavelength in the vicinity of 580 nm as shown in FIG. 11 shows the emission spectrum of the organic electroluminescence display device, but the same applies to other image display devices. For example, in the case of using an LED as a light source, in a liquid crystal display device, the transmittance decrease can be reduced by setting the wavelength to be out of the maximum value of the emission spectrum of the LED using the maximum absorption wavelength of the dichroic dye. The difference between the maximum wavelength of the dichroic dye absorption maximum wavelength and the maximum wavelength of the emission spectrum of the image display device is 5 nm or more, preferably 10 nm or more, and more preferably 20 nm or more. When the thickness is less than 5 nm, suppression of decrease in transmittance due to an out-of-wavelength becomes insufficient.

The dichroic ratio of the dichroic dye is defined as the ratio of the absorbance at the maximum absorption wavelength to the absorbance at the single axis in the major axis direction of the dye molecule. The dichroic ratio can be obtained by measuring the absorbance in the alignment direction of the dye and the absorbance in the direction perpendicular to the alignment direction. The dichroic dye which can be used in the present invention has a dichroic ratio of preferably 2 or more and 50 or less, more preferably 5 or more and 30 or less.

The dichroic dye is not particularly limited, and examples thereof include an azo dye, an azine dye, an azomethine dye, an oxazine dye, a cyanine dye, a melocyanine dye, a squarylium dye, a naphthalene dye, And at least one of an anthraquinone dye, a benzotriazole dye, a benzophenone dye, a pyrazoline dye, a diphenylpolyene dye, a binaphthylpolyene dye, a stilbene dye, a benzothiazole dye, a thienothiazole dye, Coumarin dyes, nitrophenylamine dyes, polymethine dyes, naphthoquinone dyes, perylene dyes, quinophthalone dyes, stilbene dyes and indigo dyes. Among them, the dichroic dye is preferably an anthraquinone dye or an azo dye. Examples of the azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes and stilbenazo dyes, and preferred examples thereof include bisazo dyes, trisazo dyes and derivatives of these dyes can do. Any dye satisfying the above conditions can be used in the present invention. An example of a coloring matter which can be used in the present invention is referred to as a coloring matter described in a dye hand book (Makoto Ogawara, Kitaotejiro, Hirashima Tsuneyaki, Matsuoka Masaru (ed.), Kodansha Scientific Corporation: 1986 first edition) Lt; / RTI &gt;

The dichroic dye is particularly preferably a dye represented by the following formula (1) (hereinafter sometimes referred to as "azo dye (1)").

In the formula (1), n is an integer of 1 to 4, and Ar ₁ and Ar ₃ each independently represent a group selected from the following group.

In the formula (1), Ar ₂ represents a group selected from the following group, and when n is 2 or more, Ar ₂ may be the same or different from each other.

In the above group, A ₁ and A ₂ each independently represent a group selected from the following group.

(Wherein m is an integer of 0 to 10, and when two m are present in the same group, these two m may be the same or different.)

It is preferable that the azobenzene moiety of the azo dye (1) is trans-isomer. Examples of the azo dye (1) include compounds represented by the formulas (1-1) to (1-58), respectively.

Among the specific examples of the azo dye (1), the azo dye represented by the formula (1-2), the formula (1-5), the formula (1-6), the formula (1-8), the formula (1-10) (1-12), (1-13), (1-15), (1-16), (1-19), (1-20) (1-22), (1-22), (1-24), (1-26), (1-27), (1-28) ) Equation 1-31, Equation 1-32, Equation 1-33, Equation 1-34, Equation 1-35, Equation 1-36, Equation 1-49, Expression (1-50), Expression (1-51), Expression (1-52), Expression (1-53), Expression (1-54) Expression (1-55) (1-5), (1-8), (1-10) and (1-58) 1-12), Expression (1-28), Expression (1-29), Expression (1-30), Expression (1) (1-36), (1-36), (1-33), (1-34), (1-35) ), The expression (1-51), the expression (1-52), the expression (1-53), the expression (1-54) and the expression (1-55), respectively.

The anthraquinone dye is preferably a compound represented by the formula (1-59).

Wherein R ¹ to R ⁸ independently represent a hydrogen atom, -Rx, -NH ₂ , -NHRx, -NRx ₂ , -SRx or a halogen atom, Rx represents an alkyl group having 1 to 4 carbon atoms, An aryl group having 6 to 12 carbon atoms.

As the acridine dye, a compound represented by the formula (1-60) is preferable.

(Wherein R ⁹ to R ¹⁵ independently represent a hydrogen atom, -R x, -NH ₂ , -NHR x, -NR x ₂ , -SR x, or a halogen atom, R x represents an alkyl group having 1 to 4 carbon atoms, An aryl group having 6 to 12 carbon atoms.

As the oxazole dye, a compound represented by the formula (1-61) is preferable.

(Wherein R ¹⁶ to R ²³ independently represent a hydrogen atom, -R x, -NH ₂ , -NHR x, -NR x ₂ , -SR x, or a halogen atom, R x represents an alkyl group having 1 to 4 carbon atoms, An aryl group having 6 to 12 carbon atoms.

In the above formulas (1-59), (1-60) and (1-61), the alkyl group having 1 to 6 carbon atoms represented by Rx is a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, , And the aryl group having 6 to 12 carbon atoms includes a phenyl group, a toluyl group, a xylyl group and a naphthyl group.

As the cyanine dye, a compound represented by the formula (1-62) and a compound represented by the formula (1-63) are preferable.

(Wherein D ¹ and D ² are independently of each other and represent a group represented by any one of the following formulas (1-62a) to (1-62d), and n5 represents an integer of 1 to 3.)

(In the formula (1-63), D ³ and D ⁴ independently represent a group represented by any one of the following formulas (1-63a) to (1-63h), and n6 is an integer of 1 to 3 .

The azo dye (1) is preferably a dichroic dye, and the azo dye (1) having different maximum absorption wavelengths is preferably used as the dichroic dye, Or at least two kinds thereof.

The content of the dichroic dye in the retarder can be appropriately adjusted depending on the kind of the dichroic dye or the like. For example, the content of the dichroic dye in the retarder is preferably 0.001 part by mass or more and 50 parts by mass or less based on 100 parts by mass of the total amount of the organic polymer compound More preferably 0.01 parts by mass or more and 10 parts by mass or less, and still more preferably 0.03 parts by mass or more and 1 part by mass or less. When the content of the dichroic dye is within this range, the organic polymer can be formed and polymerized without disturbing the orientation of the organic polymer. If the content of the dichroic dye is too large, the orientation of the organic polymer may be inhibited or the transmittance of the film may be lowered due to the absorption of the dye. Therefore, the content of the dichroic dye may be determined within a range in which the organic polymer can maintain alignment. The content of the dichroic dye referred to herein means the total amount of two or more dichroic dyes.

[Phase difference plate of the present invention made of stretched film]

As the polymer used as the stretched film, from the viewpoint of maintaining optical properties as an optical film, from the viewpoints of high optical isotropy and a light transmittance of 80% or more, and in view of cost and continuous productivity, polyvinyl alcohol , Polyester-based polymers such as polyimide, polyphenylene oxide, polyphenylenesulfide, polysulfone, polyetherketone, polyether sulfone, polyetheretherketone, polyarylate, polyethylene terephthalate and polyethylene naphthalate; Cellulosic polymers such as diacetylcellulose and triacetylcellulose; Polycarbonate-based polymers; Transparent polymers such as (meth) acryl-based polymers such as polymethyl (meth) acrylate; Styrene-based polymers such as polystyrene, acrylonitrile and styrene copolymer; Olefin-based polymers such as polyethylene, polypropylene, and ethylene-propylene copolymer; Cyclic olefin polymers (polycycloolefins) such as norbornene derivatives; Vinyl chloride-based polymers; Amide polymers such as nylon and aromatic polyamides; , And blends of these materials. The &quot; cyclic olefin polymer &quot; is a general term for resins obtained from cyclic olefins such as norbornene, dicyclopentadiene, tetracyclododecene and their derivatives. The organic polymer material as the material of such a base material can be selected from the group consisting of a cellulose-based polymer, a polycarbonate-based polymer, a cyclic olefin polymer (a cycloolefin polymer : COP) is more preferable.

As such a cellulosic polymer, a lower fatty acid ester of cellulose is more preferable. As such a lower fatty acid, a fatty acid having 6 or less carbon atoms is preferable. The number of carbon atoms of such lower fatty acids is more preferably 2 to 4. Examples of such a cellulosic polymer include cellulose acetate, cellulose propionate, and cellulose butyrate. Among such cellulose-based polymers, cellulose triacetate is particularly preferable. As the cellulose-based polymer, a mixed fatty acid ester such as cellulose acetate propionate or cellulose acetate butyrate may be used.

Examples of the cyclic olefin polymer (COP) include ring-opening polymers of cyclic olefins, addition polymers of cyclic olefins, random copolymers of cyclic olefins and? -Olefins such as ethylene and propylene, unsaturated carboxylic acids and derivatives thereof And the like, hydrides thereof, and the like. As such cyclic olefins, norbornene and its derivatives and dicyclopentadiene are preferable.

In the case where the birefringence is aimed at a retardation film having a "negative dispersion" property, at least two types of organic polymers including a positive birefringent organic polymer as described in Patent Document 5 and an organic polymer having negative birefringence It is preferable to use an organic polymer composed of a mixture or copolymer of polymers.

As the mixing method of the organic polymer and the dichroic dye, it is preferable to mix them in a solution state for uniform mixing. Specifically, a method of suspending or dissolving the polymer in a solvent, and suspending or dissolving the additive in the polymer are mixed. The solvent used in the present invention preferably has a high solubility in a polymer. With respect to the film formation method of a film composed of an organic polymer and a dichroic dye, there are a solvent casting method in which a dichroic dye or an organic polymer is melted and cast in a solvent, an extrusion molding method in which the mixture is kneaded in a solid state, A calender method in which a mixture is kneaded in a calender roll, a press molding method in which a film is formed by a press or the like, and the like. Among these, a solvent casting method having an excellent film thickness (accuracy) is preferable. The thickness of the film after the film formation is not particularly limited, but if it is too thin, it adversely affects the mechanical strength. If it is too thick, the evaporation rate of the solvent at the time of film formation by the solvent casting method becomes slow, Thickness range. The thickness of the film after film formation is preferably 20 to 500 mu m, more preferably 50 to 300 mu m.

Examples of the stretching method for stretching while heating the film after film formation include a tenter stretching method, an inter-roll stretching method, and an inter-roll compression stretching method. From the viewpoint of the uniformity of the film surface and the like, the tenter stretching method and the inter-roll stretching method are preferable. The method of heating the film is not particularly limited. The heating temperature at the time of stretching the film by these stretching methods is appropriately selected according to the softening temperature of the polymer to be used and the transition temperature of the dichroic dye. With respect to the draw ratio, if the magnification is low, the orientation becomes insufficient. If the magnification is too high, the film thickness becomes too thin, which makes handling difficult. Specifically, it is preferably 1.1 to 20 times, more preferably 1.2 to 15 times. The drawing speed and the cooling speed after drawing are not particularly limited.

[Phase difference plate of the present invention comprising a liquid crystal film]

The liquid crystal film is a film in which a liquid crystal compound is aligned and immobilized in a liquid crystal state. The orientation of the liquid crystal film referred to here indicates a state in which the molecular chains of the liquid crystal compound are aligned in a specific direction and this state can be measured by measuring the retardation (? N d) of the film. , It indicates that? N d is 20 nm or more at a measurement wavelength of 550 nm. DELTA n · d is the product of the birefringence Δn of the liquid crystal film and the film thickness d. The liquid crystal compound may be either low molecular weight or high molecular weight or it may be polymerized by polymerization or crosslinking reaction. Examples of the method of immobilizing the orientation of the compound include a method in which a polymerizable functional group is added to a liquid crystal compound to form a polymerizable liquid crystal compound and the alignment state is fixed by polymerization or a method in which the alignment state of the liquid crystal compound is controlled to be below the glass transition temperature Followed by immobilization in a glass state. It is preferable to use a polymerizable liquid crystal compound in that the liquid crystal compound can be aligned at a relatively low temperature and the molecular design of the liquid crystal compound is easy.

[Polymerizable liquid crystal compound]

In the case where the retarder according to the present invention is formed of a liquid crystal film, the polymerizable liquid crystal material constituting the liquid crystal film will be described. The polymerizable liquid crystal compound is not particularly limited as far as it is a liquid crystal compound capable of fixing the alignment state by polymerization, and a known polymerizable liquid crystal compound can be suitably used. As such a polymerizable liquid crystal compound, it is preferable to use a polymerizable liquid crystal compound capable of aligning parallelly on a substrate and fixing the alignment state thereof. Examples of such a polymerizable liquid crystal compound include a polymerizable liquid crystal compound having a low molecular weight (a liquid crystalline monomer having a polymerizable group), a polymerizable liquid crystal compound (a liquid crystalline polymer having a polymerizable group) And the like.

In addition, as such a polymerizable liquid crystal compound, a liquid crystal compound having a polymerizable group which reacts by light and / or heat is preferable from the viewpoint that the alignment state can be more efficiently fixed. Such a liquid crystal compound having a polymerizable group which reacts with light or heat may be any one capable of polymerizing with a component (liquid crystal compound or the like) existing around the polymerizable group by light and / or heat to fix the alignment, Is not particularly limited, and a liquid crystal compound having a known polymerizable group can be appropriately used. The polymerizable group is preferably a vinyl group, a (meth) acryloyl group, a vinyloxy group, an oxiranyl group, an oxetanyl group or an aziridinyl group. With respect to such a polymerizable group, other polymerization groups such as an isocyanato group, a hydroxyl group, an amino group, an acid anhydride group, and a carboxyl group may be used depending on the reaction conditions and the like.

Such a polymerizable liquid crystal compound is preferably a liquid crystal compound having a (meth) acryloyl group as a polymerizable group from the viewpoint of availability, heat resistance and ease of handling, and a (meth) acrylate- A liquid crystal compound having an acrylate group) is more preferably used. In the present invention, "methacryloyl" and "acryloyl" are collectively referred to as "(meth) acryloyl" in some cases, and "methacrylate" and " Methacrylate "and" acrylate "are generically referred to as" (meth) acrylate " The term "(meth) acrylate group" refers to a residue in which hydrogen is removed from the carboxyl group of (meth) acrylic acid ((meth) acryloyloxy group).

As such (meth) acrylate-based liquid crystal compounds, compounds represented by the following general formulas (10) to (12) are preferable.

In the general formulas (10) to (12), W independently represents any one of H and CH ₃ . Depending on the type of W, the group represented by CH ₂ = CWCOO is any one of an acrylate group and a methacrylate group. Further, n is an integer of 1 to 20 (more preferably 2 to 12, still more preferably 3 to 6). When the value of n is less than the lower limit, the temperature range in which the compound exhibits liquid crystallinity tends to decrease. On the other hand, when the upper limit is exceeded, the liquidity-derived fluidity of the compound required for realizing a favorable parallel alignment As a result, it becomes difficult to realize a good parallel alignment.

In the general formula (10), R ^a represents any one group selected from an alkyl group having 1 to 20 carbon atoms and an alkoxy group having 1 to 20 carbon atoms. The alkyl group having 1 to 20 carbon atoms, which may be selected as such R ^a , more preferably has 1 to 12 carbon atoms, and more preferably 3 to 6 carbon atoms. When the number of carbon atoms exceeds the upper limit, the liquidity derived from the liquid crystal of the compound necessary for realizing a favorable parallel alignment tends to be small, and as a result, it tends to be difficult to realize a good parallel alignment. If the carbon number is lower than the lower limit, the temperature range at which the compound exhibits liquid crystallinity tends to be small. Such an alkyl group is not particularly limited as long as it is straight chain, branched chain or cyclic. It is more preferable that the alkyl group is a linear chain from the viewpoint of realizing good parallel alignment.

The alkoxy group having 1 to 20 carbon atoms which may be selected as R &^lt; ^a &gt; is more preferably 1 to 12 carbon atoms, and further preferably 3 to 6 carbon atoms. When the number of carbon atoms exceeds the upper limit, the liquidity derived from the liquid crystal of the compound necessary for realizing a favorable parallel alignment tends to be small, and as a result, it tends to be difficult to realize a good parallel alignment. If the carbon number is lower than the lower limit, the temperature range at which the compound exhibits liquid crystallinity tends to be small. The alkoxy group has a structure in which an alkyl group is bonded to an oxygen atom, but the structure of the alkyl group portion is not particularly limited as long as it is a straight chain, branched chain, or cyclic structure. However, From the viewpoint of realization, it is more preferable to be a straight line.

In the general formula (12), Z ¹ and Z ² are each independently any one of -COO- and -OCO-. As such Z ¹ and Z ² , From the standpoint of easiness of preparation of the compound and the like, Z ¹ and Z ² Is a group represented by -COO-, and the other group is preferably a group represented by -OCO-.

In the general formula (12), X ¹ and X ² each independently represent any one of H and an alkyl group having 1 to 7 carbon atoms. The alkyl group having 1 to 7 carbon atoms which may be selected as X ¹ and X ² is more preferably 1 to 3 carbon atoms, and more preferably 1 (the alkyl group is CH ₃ ). If the number of carbon atoms exceeds the upper limit, it tends to be difficult to achieve good orientation. Thus, X ¹ and X ² are each independently H and CH ₃ Is particularly preferable.

Examples of the (meth) acrylate-based liquid crystal compound represented by the general formulas (10) to (12) include compounds described in the following general formulas (110) to (113). These (meth) acrylate-based liquid crystal compounds may be used singly or in combination of two or more.

As the polymerizable liquid crystal compound, it is preferable to use the compounds represented by the above-mentioned general formulas (10) to (12) in combination, and the use of the compounds represented by the above general formulas (110) More preferable.

As described above, when the polymerizable liquid crystal compound is used in combination with the compounds represented by the general formulas (10) to (12), the content of the compound represented by the general formula (10) ) To (12), more preferably 20 to 60% by mass, and more preferably 30 to 45% by mass. When the content of the compound represented by the general formula (10) is less than the lower limit described above, alignment defects tend to occur in the parallel alignment property, and when exceeding the upper limit, orientation defects tend to occur in the parallel alignment property .

When the compounds represented by the above general formulas (10) to (12) are used in combination, the content of the compound represented by the general formula (11) is preferably represented by the general formulas (10) Is preferably from 10 to 50 mass%, more preferably from 20 to 30 mass%, based on the total amount of the compound. When the content of the compound represented by the general formula (11) is less than the lower limit described above, alignment defects tend to occur in the parallel alignment property, and when exceeding the upper limit, alignment defects tend to occur in the parallel alignment property .

When the compounds represented by the general formulas (10) to (12) are used in combination, the content of the compound represented by the general formula (12) is preferably represented by the general formulas (10) Is preferably 10 to 70% by mass, more preferably 25 to 45% by mass with respect to the total amount of the compound to be added. When the content of the compound represented by the general formula (12) is less than the lower limit described above, alignment defects tend to occur in the parallel alignment property, while in the case of exceeding the upper limit, alignment defects tend to occur in the parallel alignment property .

When the compounds represented by the above general formulas (110) to (113) are used in combination as the polymerizable liquid crystal compound, from the viewpoint of realizing a favorable parallel alignment, ): [The compound represented by the above general formula (111)]: [the compound represented by the general formula (112)]: [the compound represented by the general formula (113) : 15: 0 to 35: 5: 30: 30, and more preferably 35: 23: 23: 19 to 38: 25: 25: 12.

The method of producing the polymerizable liquid crystal compound is not particularly limited, and a known method can be appropriately used. For example, in the case of producing the compound represented by the above general formula (110), for example, the method described in British Patent Application Publication No. 2,280,445 may be employed, and the compound represented by the general formula (111) The method described on page 3201 to page 3215 of "Makromol.Chem. (Vol.190, published 1989)" of DJ Broer et al. May be employed, ) To (113), for example, the method described in WO 93/22397 may be employed. Thus, the polymerizable liquid crystal compound can be produced by appropriately using a known method depending on the kind of the compound used. As such a polymerizable liquid crystal compound, a commercially available product may be used. These polymerizable liquid crystal compounds may be used singly or in combination of two or more.

In the retarder according to the present invention, it is preferable that the retardation? N 占 d (the product of the birefringence? N and the film thickness d of the retardation film) satisfies the following formulas (1) and (2).

0.70 <? N d (450) /? N d (550) <1.00 (1)

1.00 <? N d (650) /? N? D (550) <1.30 (2)

Considering the non-bias sensitivity characteristic, the retardation plate according to the present invention has retardation? N d (product of birefringence? N and film thickness d of the retardation plate) at a more preferable measurement wavelength of 550 nm to 580 nm, (3) and (4).

0.80 <? N d (500) /? N d 550 <1.10 (3)

1.00 <? N d (580) /? N? D (550) <1.15 (4)

Particularly, as a method of satisfying the requirement of the formula (1), it is preferable that the polymerizable polymer compound is a compound having two or more kinds of mesogen groups, and at least one mesogen group among them is arranged in a direction substantially orthogonal to the slow axis of the parallel alignment of the liquid crystal layer , It is described in JP-A-2002-267838 and JP-A-2010-31223 that the phase difference becomes larger as the wavelength becomes longer. Here, the mesogen in the meso gene group is also called a mesophase (liquid crystal phase) forming molecule ("liquid crystal dictionary ", Japan Academic Promotion Association, Organic Materials for Information Science Committee 142, , Which has almost the same meaning as liquid crystalline molecular structure. In the present invention, it is preferable to employ a mesogen group (a molecular structure relating to the liquid crystallinity of rod-like liquid crystal) of rod-like liquid crystal. Mesogenic groups in rod-shaped liquid crystals are described in various documents (for example, Flussige Kristalle in Tabellen, VEB Deutscher Verlag furGrundstoffindustrie, Leipzig (1984), Vol. 2).

Examples of mesogens include biphenyl, phenylcyclohexyl, cyclohexylphenyl, phenyloxycarbonylphenyl, phenylcarbonyloxyphenyl, phenyloxycarbonylcyclohexyl, cyclohexylcarbonyloxyphenyl, phenylcarbonyloxyphenyloxycarbo Phenylcarbonyloxyphenyloxycarbonylphenyl, phenylcarbonyloxycyclohexyloxycarbonylphenyl, phenyloxycarbonylcyclohexylcarbonyloxyphenyl, phenylcarbonyloxyphenylaminocarbonylphenyl, phenylethenylene phenyl , Phenylethynylenephenyl, phenylethynylenephenylethynylenephenyl, phenylethenylenecarbonyloxybiphenyl, and phenylethenyleneoxyphenylethynylenephenyl. The term &quot; arylalkenyl &quot;

The mesogen group (a benzene ring or a cyclohexane ring constituting the mesogen group) may have a substituent. As the substituent, the above-mentioned polymerizable group or derivative thereof is preferable. As a combination of two kinds of mesogen groups, one mesogen group is selected from biphenyl, phenylcyclohexyl, cyclohexylphenyl, phenyloxycarbonylphenyl, phenylcarbonyloxyphenyl, phenyloxycarbonylcyclohexyl, cyclohexylcarbonyloxy Phenylcarbonyloxyphenyloxycarbonylphenyl, phenylcarbonyloxyphenyloxycarbonylphenyl, phenylcarbonyloxyphenyloxycarbonylphenyl, phenylcarbonyloxycyclohexyloxycarbonylphenyl, phenyloxycarbonylcyclohexylcarbonyloxyphenyl, and phenylcarbonyloxyphenylamino Carbonylphenyl, and the other mesogen group is selected from the group consisting of phenylethenylenephenyl, phenylethynylenephenyl, phenylethynylenephenylethynylenephenyl, phenylethenylenecarbonyloxybiphenyl, and phenyl Phenylenediamine, phenylenediamine, phenylenediamine, phenylenediamine, phenylenediamine, phenylenediamine and phenylenediamine.

The compound having two or more kinds of mesogen groups can be synthesized by applying a general synthesis method. For example, 1) sequential introduction method in which one of two or more mesogen groups is first introduced by functional group conversion of the starting material and then another mesogen group is subsequently introduced by the same functional group conversion, 2) A simultaneous introduction method in which two or more kinds of mesogen groups are simultaneously introduced at the same time, or 3) a combination method of a sequential introduction method and a simultaneous introduction method can be adopted. The method for producing the compound having two or more kinds of mesogen groups is not particularly limited and a known method can be appropriately used. For example, the method described in Japanese Patent Application Laid-Open No. 2002-267838 may be employed do. As described above, the polymerizable liquid crystal compound can be produced by suitably using a known method depending on the kind of the compound used. Other methods are disclosed in Japanese Patent Publication No. 2010-522892, Japanese Patent Publication No. 2010-522893, Japanese Patent Publication No. 2010-537954, Japanese Patent Publication No. 2010-537955, Japanese Patent Application Laid-Open No. 2010-540472, Japanese Patent Publication No. 2012-532155, Japanese Patent Publication No. 2013-509458, Japanese Patent Application Laid-Open No. 2007-2208, Japanese Patent Application Laid-open No. 2007 -2209, Japanese Patent Application Laid-Open No. 2007-2210, Japanese Patent Application Laid-Open No. 2009-173893, Japanese Patent Application Laid-Open No. 2010-30979, Japanese Laid-Open Patent Application No. 2011-6360, Japanese Patent Application Laid- Japanese Patent Application Laid-Open No. 2011-6361, Japanese Patent Application Laid-Open No. 2011-42606, Japanese Laid-Open Patent Application No. 2011-162678, Japanese Laid-Open Patent Publication No. 2011-207765, Japanese Laid- 71956, Japanese Patent Application Laid-Open No. 2005-289980 JP-A-2006-243470, JP-A-2008-273925, JP-A-2009-62508, JP-A-2009-179563, JP-A- JP-A-2010-84032, JP-A-2005-208415, JP-A-2005-208416, WO02012 / 169424, etc.

As the polymerizable liquid crystal compound, a commercially available product may be used. Such a polymerizable liquid crystal compound may be used singly or as a mixture of two or more kinds. When two or more liquid crystal compounds are mixed, it is not necessary that all the liquid crystal compounds exhibit liquid crystallinity, and the mixture may exhibit liquid crystallinity. For example, a compound having two or more kinds of mesogen groups may exhibit liquid crystallinity even if the compound itself does not exhibit liquid crystallinity but the other liquid crystal compound. Furthermore, when used as a mixture of two or more polymerizable liquid crystal compounds, not all liquid crystal compounds need to have a polymerizable functional group, and at least one liquid crystal compound may contain a polymerizable functional group.

Such a polymerizable liquid crystal compound may be a mixture of a liquid crystal compound having a polymerizable group and another polymerizable monomer that does not exhibit liquid crystallinity. Such other polymerizable monomer is not particularly limited as long as it has compatibility with a liquid crystal compound having a polymerizable group and is not capable of causing orientation inhibition remarkably when the liquid crystalline compound is oriented, May be suitably used. Depending on the design of the intended liquid crystal composition, suitable monomers may be selected and used from known polymerizable monomers. Examples of such other polymerizable monomers include compounds having polymerizable functional groups such as ethylenic unsaturated groups (e.g., vinyl group, vinyloxy group, (meth) acryloyl group). The amount of such another polymerizable monomer to be added is preferably 0.5 to 50% by mass, more preferably 1 to 30% by mass, based on the total amount of the liquid crystal compound having the polymerizable group and the other polymerizable monomer not exhibiting liquid crystallinity. . The number of polymerizable functional groups of such a polymerizable monomer is preferably 2 or more from the viewpoint of sufficiently high polymerization rate and from the viewpoint of imparting sufficient heat resistance to the obtained liquid crystal film. The method for producing such a polymerizable monomer is not particularly limited, and a known method can be appropriately used. As such a polymerizable monomer, a commercially available product may be used.

The polymerization initiator for polymerizing the above-mentioned polymerizable liquid crystal compound is not particularly limited, and a known polymerization initiator can be suitably used. Among the known polymerization initiators, the polymerization initiator can be more efficiently And those capable of initiating polymerization of the polymerizable liquid crystal compound may suitably be selected and used.

The polymerization initiator may be a thermal polymerization initiator (an initiator when a thermal polymerization reaction is used) or a photopolymerization initiator (an initiator when light or electron beam irradiation is used). As such a polymerization initiator, it is more preferable to use a photopolymerization initiator from the viewpoint of preventing the substrate or the like from being deformed or altered by heat when a plastic film or the like is used as a base material in the production of a liquid crystal film. Examples of such a photopolymerization initiator include a combination of an? -Carbonyl compound, an acyloin ether, an? -Hydrocarbon substituted aromatic acyloin compound, a polynuclear quinone compound, a triarylimidazole dimer and p-aminophenyl ketone Acridine, and phenazine compounds, and oxadiazole compounds. Examples of such an? -Carbonyl compound include? -Carbonyl compounds described in USP 2367661 and USP 2367670, and examples of the acyloin ether include, for example, And those described in U.S. Patent No. 2448828. Examples of the? -Hydrocarbon substituted aromatic acyloin compounds include those described in U.S. Patent No. 2722512, and examples of the polynuclear quinone compounds include U.S. Patent No. 3046127 and U.S. Patent No. 2951758 And those described in the specification of the present invention. Examples of the combination of triarylimidazole dimer and p-aminophenyl ketone include those described in US Pat. No. 3,549,367, and examples of the acridine and phenazine compounds include, For example, those described in Japanese Patent Application Laid-Open Nos. 60-105667 and 4239850, and the oxadiazole compounds described in United States Patent No. 4212970 .

As a photopolymerization initiator, a commercially available product may be used. For example, a photopolymerization initiator (trade name "Irugacure 907 ", trade name" Irugacure 651 ", trade name "Irugacure 184" (Trade name "UVI6974"), and the like may be appropriately used. Such a photopolymerization initiator may generate free radicals or generate ions by irradiation with light or electron beams. Depending on the kind of the polymerizable liquid crystal compound in the composition or the polymerization reaction conditions, (For example, trade name "Irgacure 651 ", trade name; manufactured by BASF) or a photopolymerization initiator (for example, a photopolymerization initiator (trade name" UVI6974 " The appropriate one may be appropriately selected and used.

The content of the polymerization initiator is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass based on 100 parts by mass of the polymerizable liquid crystal compound to which a dichroic dye is added. If the content of the polymerization initiator is too low, the curability of the resulting retardation plate tends to be insufficient. On the other hand, if the content of the polymerization initiator is too large, defects tend to occur in the alignment of the liquid crystal.

Next, a method of manufacturing the retarder of the present invention will be described. The method for producing the retarder is not limited to these, but it is also possible to use a method in which a composition containing a polymerizable liquid crystal compound, a dichroic dye and various kinds of compounds to be added as needed is melted or a solution of the composition is applied onto an alignment substrate Or by applying heat treatment (orientation of liquid crystal), or if necessary, by a means for fixing the above-mentioned orientation such as light irradiation and / or heat treatment (polymerization / crosslinking) The liquid crystal and the optically anisotropic layer in which the alignment of the dichroic dye is immobilized are formed.

The state that the "orientation state is immobilized in the parallel alignment state" is a state in which the alignment direction of the liquid crystal molecules in the optically anisotropic layer obtained after polymerization of the polymerizable liquid crystal compound is fixed, (The orientation in alignment) is confirmed, and the component derived from the polymerizable liquid crystal compound or the like (preferably, the component derived from the polymerizable liquid crystal compound: the polymerizable liquid crystal compound itself, the constituent Or a polymerizable liquid crystal compound, etc.) may be fixed in a state of parallel alignment.

The solvent used for the preparation of the solution is not particularly limited as long as it is a solvent capable of dissolving the polymerizable liquid crystal compound and the dichroic dye and allowing it to be distilled off under appropriate conditions and generally includes acetone, Ketones such as isophorone, cyclohexanone and cyclopentanone, alcohols such as isopropyl alcohol and n-butanol, ether alcohols such as butoxyethyl alcohol, hexyloxyethyl alcohol and methoxy-2-propanol, ethylene glycol dimethyl Glycol ethers such as diethylene glycol dimethyl ether, 2-methoxyethyl acetate and propylene glycol 1-monomethyl ether 2-acetal, esters such as ethyl acetate and ethyl lactate, phenols such as phenol and chlorophenol, N , Amides such as N-dimethylformamide, N, N-dimethylacetoamide and N-methylpyrrolidone, chloroform, dichloromethane, trichlorethylene, tetrachloroethane, Halogenated hydrocarbons such as benzene, toluene, xylene, methoxybenzene, 1,2-dimethoxybenzene, and the like; And cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve, or a mixture thereof can be used.

From such viewpoints of drying speed, ease of handling (hazard to the environment), and solubility in a polymerizable liquid crystal compound and a dichroic dye, it is preferable to use a solvent such as propylene glycol 1-mono Methyl ether 2-acetate, 2-methoxyethyl acetate, toluene, xylene, methoxybenzene, 1,2-methoxybenzene, cyclohexanone, cyclopentanone, methyl cellosolve, ethyl cellosolve, butyl cell Propanol, 1-propanol, 1-propanol, 1-propanol, 1-propanol, 1-butanol and 1-propanol. These solvents may be used alone or in combination of two or more. In addition, depending on the kind of the substrate, it is preferable to appropriately select and use a suitable solvent in accordance with the kind of the substrate since corrosion may occur depending on the kind of the solvent.

The content of the solvent used in the present invention is not particularly limited depending on the method of using the composition (for example, when the composition is used to form an optically anisotropic layer, a method of using the composition including the thickness, a coating method, etc.) But it is preferably from 30 to 98% by mass, more preferably from 50 to 95% by mass, still more preferably from 70 to 90% by mass. When the content of such a solvent is too small, the amount of the solvent to the mixture of the polymerizable liquid crystal compound and the dichroic dye is decreased, so that the liquid crystal precipitates during storage, the viscosity of the mixture increases, , There is a tendency that coating becomes difficult during production of the retarder. On the other hand, if the content of the solvent is too large, the removal time (drying time) of the solvent is long when the solvent is removed. In addition, when the film is produced, the working efficiency is lowered. Since the flow of the surface is aggravated, it tends to be difficult to use the composition to produce a uniform retardation plate. Thus, in the mixture of the polymerizable liquid crystal compound and the dichroic dye of the present invention, the amount of the mixture of components other than the solvent is preferably 2 to 70 mass%, more preferably 5 to 50 mass% More preferably 10 to 30% by mass. The mixture of the polymerizable liquid crystal compound and the dichroic dye may contain not only the solvent but also a reaction activator, a sensitizer, a surfactant, a defoaming agent, a leveling agent and the like in order to form a uniform coating film on the alignment substrate do.

Next, an alignment substrate for orienting the polymerizable liquid crystal compound will be described. As the alignment substrate, it is preferable to first have a flat plane, and examples thereof include a film or sheet made of an organic polymer material, a glass plate, a metal plate, and the like. From the viewpoint of cost and continuous productivity, it is preferable to use a material made of an organic polymer. Examples of the organic polymer material include polyvinyl alcohol, polyimide, polyamide, polyamideimide, polyphenylsulfone, polyethersulfone, polyphenylene oxide, polyetherketone, polyetheretherketone, polyethylene terephthalate, polyethylene naphthalate , Polyester polymers such as polysulfone and polyallylate, cellulosic polymers such as diacetylcellulose and triacetylcellulose, polycarbonate polymers, acrylic polymers such as polymethylmethacrylate, epoxy resins, phenol resins and the like Of a transparent polymer. Examples of the polymer include styrene polymers such as polystyrene and acrylonitrile-styrene copolymer, olefin polymers such as polyethylene, polypropylene and ethylene-propylene copolymer, cyclopolyolefins having a cyclic to norbornene structure, vinyl chloride polymers, Amide-based polymers such as polyamides, and the like. Examples of the polymer include imide polymers, sulfonic polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylsulfone polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, A film composed of a transparent polymer such as a polyoxymethylene polymer, an epoxy polymer, or a blend of the above polymers.

As the cellulose-based polymer, a lower fatty acid ester of cellulose is more preferable. As such a lower fatty acid, a fatty acid having 6 or less carbon atoms is preferable. Further, the number of carbon atoms of such lower fatty acids is more preferably 2 to 4. Examples of such a cellulosic polymer include cellulose acetate, cellulose propionate, and cellulose butyrate. Among such cellulose-based polymers, cellulose triacetate is particularly preferable. As the cellulose-based polymer, a mixed fatty acid ester such as cellulose acetate propionate or cellulose acetate butyrate may be used.

Examples of the cyclic olefin polymer (COP) include ring-opening polymers of cyclic olefins, addition polymers of cyclic olefins, random copolymers of cyclic olefins and? -Olefins such as ethylene and propylene, unsaturated carboxylic acids and their derivatives And the like, and hydrides thereof, and the like. As such cyclic olefins, norbornene and its derivatives and dicyclopentadiene are preferable. As the cyclic olefin polymer film, a commercially available product can be used. Examples thereof include commercially available products such as Zeonoa (trade name, manufactured by Nippon Zeon Co., Ltd.), Zeonex (trade name, manufactured by Nippon Zeon Co., ) Can be used.

Of the films made of the organic polymer materials described above, plastic films such as triacetyl cellulose, polycarbonate, norbornene polyolefin, and polyethylene terephthalate, which are used as optical films, can be preferably used. Examples of the metal film include a corresponding film formed of aluminum or the like.

Such a base material is not particularly limited, but it may be provided with a retardation function in accordance with its use, for example, when a layered product of the formed optically anisotropic layer and a base material is directly used as an optical film or the like. Such a substrate may be uniaxially stretched (so-called monoaxially stretched film) or biaxially stretched (so-called biaxially stretched film). Such a base material may be used as a film having optical anisotropy by emitting biaxial optical anisotropy by stretching it in the longitudinal direction and the transverse direction.

As such a substrate, a substrate subjected to a Z-axis alignment treatment may be used. In order to control the adhesiveness of the substrate, surface treatment such as corona treatment, plasma treatment, UV-ozone treatment, and saponification treatment may be appropriately performed on one surface or both surfaces. The conditions for such a surface treatment may be suitably set according to the substrate to be used, and there is no particular limitation, and known conditions may be suitably employed.

Some of these films exhibit sufficient aligning ability to the polymerizable liquid crystal compound even if no treatment for expressing the aligning ability is performed again depending on the production method. However, when the alignment ability is insufficient or the alignment ability is not exhibited, If necessary, these films may be stretched under appropriate heating, or the so-called rubbing treatment may be performed in which the film surface is rubbed with a rayon cloth or the like in one direction, or a film of a known alignment agent such as polyimide, polyvinyl alcohol, An orientation film is formed and subjected to a rubbing treatment, a photo alignment film is applied on a film and heated to a suitable temperature, and then an alignment film is formed by irradiating linearly polarized ultraviolet rays, or an oblique deposition process such as silicon oxide is performed, Alternatively, a film exhibiting an orientation ability such as a combination of these means may be used.

It is also possible to use a metal plate such as aluminum, iron, copper, nickel, or stainless which has regular fine grooves formed on its surface, various glass plates, or the like as a circular mold, Or a regular fine groove is transferred to the surface of the film by using an ultraviolet curable resin or the like can also be used as an alignment substrate. Among them, in the field of liquid crystal, it is general to perform rubbing treatment to wipe the substrate with cloth or the like. An important set value for defining the rubbing condition is the peripheral speed ratio. This shows the ratio of the movement speed of the cloth to the movement speed of the substrate when the substrate is rubbed while rotating the rubbing cloth around the roll. In the present invention, the peripheral velocity ratio is usually 50 or less, more preferably 25 or less, particularly preferably 10 or less. When the peripheral velocity ratio is larger than 50, the effect of rubbing is too strong, the liquid crystal material can not be completely oriented, and the orientation becomes insufficient, which may lead to property deterioration.

Next, a method of applying a mixture (composition) containing a polymerizable liquid crystal compound and a dichroic dye to the alignment substrate described above will be described. Regarding the application method, a known method can be employed without particular limitation as long as the method can ensure uniformity of the coating film. For example, spin coating method, die coating method, curtain coating method, dip coating method, roll coating method and the like can be given. Such a coating film is also different depending on the content of the solvent in the mixture of the polymerizable liquid crystal compound and the dichroic dye, and it is not always uniform. It is preferable that the thickness of the coating film before drying (wet film thickness) is 3 to 50 mu m More preferably 5 to 20 占 퐉. If such a thickness (wet film thickness) is too small, it becomes necessary to increase the concentration of the solid component (liquid crystal compound or the like) in the liquid crystal composition in order to obtain desired optical characteristics, so that precipitation of solid content in the composition tends to occur, Not only it becomes difficult to obtain a uniform liquid crystal film, but also uniform coating becomes difficult, and the smoothness of the liquid crystal film tends to decrease. On the other hand, if the thickness (wet film thickness) is too large, the concentration of the solid content in the liquid crystal composition tends to be lowered to achieve the desired optical properties, so that the drying time after coating tends to be long.

In the method of applying the liquid crystal material solution, it is preferable that a drying step for removing the solvent after the application is included. The drying conditions are different depending on the kind of the polymerizable liquid crystal compound, the dichroic dye, the solvent, etc., and are not particularly limited and are not particularly limited. For example, depending on the kind of the solvent, it is possible to dry-remove the solvent from the coating film even at room temperature (25 캜). As described above, it is also possible to produce a liquid crystal film having a parallel alignment, without subjecting it to heat treatment, depending on the kind of the solvent and the like. The temperature condition in the solvent removal step is preferably 15 to 110 ° C, more preferably 20 to 80 ° C. In order to dry at a temperature below 15 ° C, separate cooling facilities may be required. On the other hand, when dried at a high temperature, the base material may be distorted by heat to change the optical characteristics and the like, so that desired optical characteristics may not be obtained.

The pressure condition in this drying step is not particularly limited, but is preferably 650 to 1400 hPa, more preferably 900 to 1100 hPa. When the pressure is less than the above lower limit, the drying of the solvent tends to be rapid and drying unevenness tends to occur. On the other hand, when the upper limit is exceeded, the drying of the solvent tends to take time. The time (drying time) of the solvent removal step is not particularly limited, but is preferably 10 seconds to 60 minutes, and more preferably 30 seconds to 30 minutes. When the drying time is less than the lower limit described above, the solvent tends to be dried rapidly and the smoothness of the liquid crystal film tends to decrease (drying unevenness occurs). On the other hand, when the upper limit is exceeded, the production speed is lowered, There is a tendency. In the case of using a drying device in such a solvent removing step, it is preferable to control the relative moving speed of the coating film and the drying device such that the relative wind speed is from 60 m / min to 1200 m / min. As long as the uniformity of the coating film is maintained, a known method can be adopted without particular limitation. For example, a method of heating (furnace), hot air blowing, or the like.

The film thickness of the applied film in the dry state is preferably 0.1 to 50 mu m, more preferably 0.2 to 20 mu m. Outside this range, the optical properties of the obtained optically anisotropic layer may be insufficient, or the alignment of the polymerizable liquid crystal compound and the dichroic dye may become insufficient.

Next, a method of immobilizing the orientation will be described. As a method of fixing the alignment state by polymerization of the polymerizable liquid crystal compound, a known method capable of polymerization can be appropriately adopted depending on the kind of the polymerization initiator and the polymerizable liquid crystal compound to be used. As such a method for immobilization (polymerization and immobilization) in the aligned state, for example, the polymerizable group (reactive functional group) is reacted with light irradiation and / or heat treatment according to the kind of the polymerization initiator, A method of fixing the orientation in the state of

In the case where the polymerization initiator is one that exhibits an initiator function by irradiation of light (for example, in the case of a so-called photo (radical) initiator or a photo (cationic) cation generator), the orientation It is desirable to fix the state. Such a light irradiation method is not particularly limited. For example, a light source having a spectrum in the absorption wavelength region of the polymerization initiator used (for example, a metal halide lamp having a luminance of at least 10 mW / cm ² , a medium pressure or high pressure mercury lamp A high pressure mercury lamp, a low pressure mercury lamp, a xenon lamp, an arc lamp, an LED, a laser, etc.) for irradiating light from the light source. In addition, by irradiation of such light, it becomes possible to activate the polymerization initiator, and it becomes possible to efficiently react the reactive functional group.

Further, as such a method of light according to the accumulated dose of irradiation, as the accumulated amount of exposure at a wavelength of 365nm, and 10 ~ 2000mJ / cm ² is preferable, and more preferably 100 ~ 150OmJ / cm ^2. However, the case where the absorption region of the polymerization initiator differs markedly from the spectrum of the light source, or the case where the polymerizable liquid crystal compound itself has the ability to absorb light of the light source wavelength is not limited thereto. In this case, from the viewpoint of immobilizing (curing) the coating film while keeping the alignment state more efficiently, it is also possible to employ a method of mixing a suitable photosensitizer or two or more kinds of polymerization initiators having different absorption wavelengths . Such a temperature condition at the time of light irradiation is not particularly limited as long as it is within a temperature range in which the polymerizable liquid crystal compound can maintain the alignment state of parallel alignment. Further, a cold mirror or other cooling device may be provided between the base material and the light source (ultraviolet lamp or the like) so that the surface temperature of the coating film can maintain the liquid crystal temperature range at the time of light irradiation.

The atmospheric condition at the time of light irradiation is not particularly limited and may be an atmospheric atmosphere or a nitrogen atmosphere in which oxygen is shut off to increase the reaction efficiency. In addition, since the oxygen concentration in the atmosphere is involved in the degree of polymerization, when the desired degree of polymerization is not reached in the air, it is preferable to conduct light irradiation in an atmosphere in which the oxygen concentration is lowered by a method such as nitrogen substitution. The oxygen concentration in the atmosphere gas in such a case is preferably 10% by volume or less, more preferably 7% by volume or less, and most preferably 3% by volume or less.

In the case where the polymerization initiator exhibits the function of an initiator by heat (for example, in the case of a so-called thermal radical initiator or a thermal cation generator), it is preferable that the orientation is fixed in the alignment state of parallel alignment by heat treatment desirable. The conditions for such heat treatment are not particularly limited, and depending on the kind of the polymerization initiator, temperature conditions may be selected so that the orientation state is sufficiently maintained, and known conditions can be suitably employed. When a low heat resistance material is used as the alignment base material, it is preferable that the orientation state of the parallel alignment is fixed by light irradiation by using the polymerization initiator which exhibits the function of the initiator by irradiation with light.

The liquid crystal film produced by the above process is a sufficiently firm film. Specifically, the mesogen is three-dimensionally bonded by the curing reaction, and the heat resistance (the upper limit temperature of the liquid crystal orientation holding) is improved as compared with that before the curing, and the mechanical strength such as scratch resistance, abrasion resistance and crack resistance Is greatly improved.

After the mixture containing the polymerizable liquid crystal compound and the dichroic dye is coated on the alignment substrate as described above, the solvent is removed from the coating film to orient the polymerizable liquid crystal compound and the dichroic dye, By immobilizing the liquid crystal film, a liquid crystal film immobilized in a state in which the alignment state is parallel can be formed on the alignment substrate.

In addition, it is also possible to use an optically isotropic (isotropic) substrate or an obtained retardation plate as opposed to opaque in the intended use wavelength range, or the thickness of the alignment substrate is excessively thick, If there is a problem, a form formed on the alignment substrate, a substrate optically isotropic, a stretched film having a phase difference function, or a form directly transferred to a polarizing plate may be used. As a transfer method, a known method can be employed. For example, as described in JP-A-4-57017 and JP-A-5-333313, a liquid crystal film is laminated on a substrate different from an alignment substrate through an adhesive or an adhesive, A method of transferring only the liquid crystal film by peeling the alignment substrate from the liquid crystal film by applying a curing treatment to the surface using an adhesive or an adhesive as necessary, and the like.

The pressure-sensitive adhesive or adhesive used for transferring is not particularly limited as far as it is an optical grade, and acrylic, epoxy, urethane or the like which is generally used can be used. In addition, although the liquid crystal film alone can be used as the device, the retardation plate may be formed by coating one side or both sides of the liquid crystal film with a transparent protective layer in order to improve the strength and resistance of the liquid crystal film. Examples of the transparent protective layer include a transparent plastic film such as polyester and triacetylcellulose laminated directly or via a point adhesive, a resin coating layer, and a photo-curable resin layer such as acrylic or epoxy resin. When these transparent protective layers are coated on both sides of the liquid crystal film, a different protective layer may be formed on both sides. As the optically anisotropic element, a liquid crystal film may be formed directly on the polarizing plate and directly used as the elliptically polarizing plate of the present invention. For example, a liquid crystal film is laminated on a transparent plastic film such as polyester or triacetylcellulose used for producing the polarizing film, and then the polarizing film is integrated with the polarizing film to form a polarizing film / transparent plastic film / retardation plate (liquid crystal film) It can be an elliptically polarizing plate of a polarizing film / retardation film (liquid crystal film) / transparent plastic film.

As a method of confirming the parallel alignment in the liquid crystal film obtained as described above, the following method may be employed. As a method for confirming the parallel alignment, a known method can be suitably employed, and there is no particular limitation, but a pair of orthogonal polarizers (a pair of polarizers in which the direction in which one polarizing plate is deflected and the direction in which the other alignment plate is deflected are perpendicular (A polarizing plate of a polarizing plate) in which a liquid crystal film (which may be in the form of a substrate and a laminate) is placed, a method of visually checking the transmitted light or a method of observing the retarder by a polarizing microscope do. In the case of employing any one of the above methods, when the liquid crystal film is a parallel alignment liquid crystal film, when light is incident in a direction perpendicular to the surface of the liquid crystal film in the sample, it appears bright due to the phase difference of light, The amount of light transmitted when the incident angle of the incident light with respect to the sample is tilted is almost the same in the direction in which the light is incident in the direction perpendicular to the sample. Therefore, it is possible to confirm the presence or absence of parallel alignment by measuring the contrast of such a sample through visual observation or a polarization microscope while changing the incident angle of light. As a method for confirming the parallel alignment, for example, a parallel alignment liquid crystal film is preferably used in a direction perpendicular to the surface of the liquid crystal film (vertical incidence angle), since the parallel alignment liquid crystal film has different retardation characteristics in accordance with the incident angle of light, (For example, trade name "Axoscan" manufactured by Axo-metrix, trade name "KOBRA-21ADH" manufactured by Oji Keiki Co., Ltd.) capable of measuring the phase difference when the angle of incidence of light is inclined at a specific angle in the vertical angle of incidence, , The phase difference is measured while appropriately changing the angle in a direction in which the viewing angle becomes larger in a viewing angle of 0 ° (a direction perpendicular to the liquid crystal film) to obtain the phase differences of the sample at a plurality of viewing angles, A phase difference is confirmed in a direction perpendicular to the surface of the film, and in a direction in which the viewing angle becomes larger with respect to the surface of the liquid crystal film A method of confirming the presence or absence of the parallel alignment may be employed based on confirming that the retardation in the direction of the viewing angle exhibits symmetry with respect to the values in the minus direction and the minus direction.

The thickness of the liquid crystal film (thickness of the cured film) is preferably 0.1 to 10 mu m, more preferably 0.2 to 5 mu m, though it may vary depending on applications and required characteristics. If the thickness of the liquid crystal film is too small, a desired retardation tends to be unable to be developed. On the other hand, if it is too thick, the alignment property of the liquid crystal of the liquid crystal decreases, but the transmission due to the dye tends to decrease.

<Elliptically polarizing plate>

According to the present invention, there is provided an elliptically polarizing plate comprising the retardation plate and the polarizing plate. As the linearly polarizing plate used in combination with the retarder, usually, one having a protective film on one or both sides of the polarizer is used. The polarizer is not particularly limited, and various kinds of polarizers can be used. For example, a polarizer can be used as the polarizer, such as a polyvinyl alcohol film, a partially porous polyvinyl alcohol film, a partially saponified ethylene- Those obtained by uniaxially stretching by adsorbing dichroic substances such as iodine and dichroic dyes, polyene oriented films such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride films. Among them, those obtained by stretching a polyvinyl alcohol film to adsorb and orient a dichroic material (iodine, dye) are suitably used. The thickness of the polarizer is not particularly limited, but is generally about 5 to 80 탆.

A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching can be produced by, for example, dying polyvinyl alcohol in an aqueous solution of iodine and stretching it to 3 to 7 times the original length. And may be immersed in an aqueous solution such as boric acid or potassium iodide, if necessary. If necessary, the polyvinyl alcohol film may be dipped in water and washed with water before dyeing. The polyvinyl alcohol film is washed with water to clean the surface of the polyvinyl alcohol film and to prevent unevenness such as uneven dyeing by swelling the polyvinyl alcohol film. The stretching may be carried out after the dyeing with iodine, the stretching while dyeing, or the stretching followed by the dyeing with iodine. It can be stretched either in an aqueous solution such as boric acid or potassium iodide or in a water bath.

The protective film formed on one or both sides of the polarizer is preferably excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like. Examples of the material of the protective film include polyester-based polymers such as polyethylene terephthalate and polyethylene naphthalate; cellulose-based polymers such as diacetylcellulose and triacetylcellulose; acrylic polymers such as polymethylmethacrylate; Styrene-based polymers such as rhenitrile-styrene copolymer (AS resin), and polycarbonate-based polymers. Examples of the polymer include polyolefin polymers such as polyethylene, polypropylene and ethylene / propylene copolymer, polyolefins having cycloolefin or norbornene structure, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, Based polymer, a polyether sulfone-based polymer, a polyether sulfone-based polymer, a polyether sulfone-based polymer, a polyether sulfone-based polymer, a polyether sulfone-based polymer, a polyether sulfone-based polymer, Based polymer, a blend of the polymer, and the like are examples of the polymer forming the protective film. In addition, examples thereof include those obtained by filming thermosetting or ultraviolet-curable resins such as acryl-based or urethane-based, acrylic urethane-based, epoxy-based or silicone-based resins. The thickness of the protective film is generally 500 탆 or less, preferably 1 to 300 탆. Particularly preferably 5 to 200 탆.

As the protective film, an optically isotropic substrate is preferable. For example, a triacetyl cellulose (TAC) film such as Fujitack (manufactured by Fuji Photo Film Co., Ltd.) or Konica Kagaku (manufactured by Konica Minolta Toso Co., Ltd.) ), An acrylic film, a TPX film (manufactured by Mitsui Chemicals), and an acrylic film (manufactured by Mitsubishi Rayon Co., Ltd.), which are commercially available from Nippon Zeon Co., Triacetyl cellulose, a cycloolefin-based polymer, and an acrylic polymer are preferable in terms of planarity, heat resistance and moisture resistance in the case of an elliptically polarizing plate.

When a protective film is formed on both sides of the polarizer, a protective film made of the same polymer material may be used for the front and back sides, or a protective film made of a different polymer material or the like may be used. The polarizer and the protective film are normally in close contact with each other through an aqueous pressure-sensitive adhesive, an ultraviolet curable adhesive, or the like. Examples of the water-based adhesive include polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based, water-based polyurethane and water-based polyesters. From the viewpoint of thinness, the substrate used for the retarder made of the liquid crystal film may also serve as a protective film for the polarizer.

As the protective film, there can be used a hard coat layer, an anti-reflection treatment, a prevention of sticking, and a treatment for diffusion or anti-glare treatment.

The hard coat treatment is carried out for the purpose of preventing the surface of the polarizing plate from being damaged or the like. For example, a method of adding a cured film excellent in hardness and sliding property by a suitable ultraviolet ray hardening type resin such as acrylic or silicone to the surface of the protective film . The antireflection treatment is carried out for the purpose of preventing reflection of external light (external light) on the surface of the polarizing plate, and can be achieved by forming a conventional antireflection film or the like. The anti-sticking treatment is carried out for the purpose of preventing adhesion to the adjacent layer.

In addition, the anti-glare treatment is carried out for the purpose of preventing external light from being reflected on the surface of the polarizing plate to prevent the visibility of the light transmitted through the polarizing plate from being deteriorated. For example, the anti-glare treatment may be performed by sandblasting or embossing Surface-finishing) method or a method of blending transparent fine particles or the like to give a fine concavo-convex structure to the surface of the protective film. Examples of the fine particles contained in the surface micro concavo-convex structure include conductive particles made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide or the like having an average particle diameter of 0.5 to 50 μm Transparent fine particles such as inorganic fine particles, organic fine particles made of crosslinked or uncrosslinked polymers and the like are used. When forming the surface micro concavo-convex structure, the amount of the fine particles to be used is generally about 2 to 50 parts by weight, preferably 5 to 25 parts by weight based on 100 parts by weight of the transparent resin forming the surface micro concavo-convex structure. The anti-glare layer may also serve as a diffusion layer (time magnification function or the like) for diffusing the polarized-plate transmitted light to enlarge the viewing angle or the like.

The antireflection layer, the anti-sticking layer, the diffusion layer, the antiglare layer, and the like may be formed on the protective film itself, or may be formed as a separate optical layer as a separate optical layer from the transparent protective layer.

The retardation plate and the polarizing plate can be manufactured by attaching the retardation plate and the polarizing plate together through a pressure-sensitive adhesive layer. However, in the case of a retardation plate made of a liquid crystal film, a mixture of a polymerizable liquid crystal compound and a dichroic dye is directly or indirectly polarized And then fixation and orientation. The pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer is not particularly limited. For example, a pressure-sensitive adhesive containing a base polymer such as an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, . Particularly, it is preferable to use those having excellent optical transparency such as an acrylic pressure-sensitive adhesive, exhibiting suitable wettability, cohesiveness and adhesive property, and excellent weather resistance and heat resistance.

The formation of the pressure-sensitive adhesive layer can be carried out in an appropriate manner. As an example thereof, a pressure-sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a single substance or a mixture of a suitable solvent such as toluene or ethyl acetate is prepared, A method of directly laying on the liquid crystal layer by an appropriate developing method such as a casting method or a coating method or a method of forming a pressure-sensitive adhesive layer on a separator and attaching it on the liquid crystal layer in accordance with the above- . The pressure-sensitive adhesive layer is preferably provided with a pressure-sensitive adhesive layer such as a natural or synthetic resin, particularly a pressure-sensitive adhesive resin, a filler comprising a glass fiber, a glass bead, a metal powder and other inorganic powders, Or may be added to the layer. Or a pressure-sensitive adhesive layer containing fine particles and exhibiting light diffusibility.

In addition, when the optically anisotropic layers are stuck together through the pressure-sensitive adhesive layer, the film surface can be surface-treated to improve the adhesion with the pressure-sensitive adhesive layer. The surface treatment means is not particularly limited, but surface treatment methods such as corona discharge treatment, sputtering treatment, low-pressure UV irradiation, and plasma treatment, which can maintain the transparency of each optically anisotropic layer described above, can be suitably employed. Among these surface treatment methods, the corona discharge treatment is preferable.

<Image Display Device>

The image display apparatus according to the present invention is provided with an elliptic (circular) polarizer plate including the retardation plate and the polarizing plate. The kind of the image display device is not particularly limited, and a known image display device such as a liquid crystal display device, an organic EL display device, a plasma display or the like can be suitably used. A method of arranging an elliptic (circular) polarizing plate on an image display device is also not particularly limited, and a known method can be suitably used.

<Liquid Crystal Display Device>

A liquid crystal display device to which a retarder according to the present invention is applied will be described. The liquid crystal display device generally comprises a polarizing plate, a liquid crystal cell, and members such as a retardation plate, a reflective layer, a light diffusion layer, a backlight, a front light, a light control film, a light guide plate, a prism sheet, etc. In the present invention, But there is no particular limitation. Further, the position of use of the retarder is not particularly limited and may be one position or a plurality of positions. It is also possible to use it in combination with another retardation plate.

The liquid crystal cell is not particularly limited and a common liquid crystal cell such as a liquid crystal layer sandwiched between a pair of transparent substrates provided with electrodes can be used. The transparent substrate constituting the liquid crystal cell is not particularly limited as long as the material exhibiting liquid crystallinity constituting the liquid crystal layer is oriented in a specific alignment direction. Specifically, a transparent substrate having a property that the substrate itself has a property of aligning liquid crystals, and a transparent substrate having an alignment film having a property of aligning liquid crystals, although the substrate itself has no aligning ability can be used. As the electrode of the liquid crystal cell, a known electrode can be used. Normally, the liquid crystal layer can be provided on the surface of the transparent substrate on which the liquid crystal layer is in contact. When the substrate having the alignment film is used, it can be provided between the substrate and the alignment film.

The material exhibiting liquid crystallinity for forming the liquid crystal layer is not particularly limited and includes various kinds of low-molecular liquid crystal materials, polymer liquid crystal materials, and mixtures thereof that can form various liquid crystal cells. In addition, pigments, chiral agents, non-liquid crystalline substances and the like can be added to these to the extent that liquid crystallinity is not impaired. The liquid crystal cell may have various components necessary for forming liquid crystal cells of various types described later in addition to the electrode substrate and the liquid crystal layer.

As the liquid crystal cell method, a twisted nematic (TN) method, a super twisted nematic (STN) method, an ECB (Electrically Controlled Birefringence) method, an IPS (In-Plane Switching) method, a VA ), A HAL (Hybrid Aligned Nematic) method, an ASM (Axially Symmetric Aligned Microcell) method, a halftone gray scale method, a domain division method, or a display method using a ferroelectric liquid crystal or a counter ferroelectric liquid crystal .

The driving method of the liquid crystal cell is not particularly limited. The liquid crystal cell may be driven by a passive matrix method used in an STN-LCD or the like, an active matrix using active electrodes such as a thin film transistor (TFT) electrode and a thin film diode (TFD) Or the like. The liquid crystal display device provided with the retardation plate of the present invention has advantages in that the retardation plate has desired birefringence wavelength dispersion characteristics, and therefore, depending on the characteristics thereof, for example, the viewing angle of the liquid crystal display device is sufficiently widened, Or the like. This makes it possible to sufficiently improve the viewing angle and the image quality.

<Organic Electroluminescence Device>

An organic electroluminescence device (organic EL display device) to which a retarder according to the present invention is applied will be described. In general, an organic EL display device forms a light emitting body (organic electroluminescence light emitting body) by sequentially laminating a transparent electrode, an organic light emitting layer and a metal electrode on a transparent substrate. Here, the organic luminescent layer is a laminate of various organic thin films, for example, a laminate of a hole injecting layer made of a triphenylamine derivative or the like, and a luminescent layer made of a fluorescent organic solid such as anthracene, or a laminate of such luminescent layer and perylene A multilayer structure of an electron injection layer made of a derivative or the like, or a multilayer body of a hole injection layer, a light emission layer, and an electron injection layer of these layers.

In the organic EL display, when a voltage is applied to the transparent electrode and the metal electrode, positive holes and electrons are injected into the organic light emitting layer, and energy generated by the recombination of the holes and electrons causes the fluorescent material to be excited ), And emits light on the principle that the excited fluorescent material emits light when it returns to the ground state. The mechanism of recombination in the middle is the same as that of a general diode. As can be expected from this point, the current and the light emission intensity exhibit strong nonlinearity accompanied by rectification with respect to the applied voltage.

In the organic EL display device, at least one of the electrodes must be transparent in order to realize light emission in the organic light emitting layer, and a transparent electrode formed of a transparent conductor such as indium tin oxide (ITO) is usually used as the anode. On the other hand, in order to facilitate the injection of electrons to raise the luminous efficiency, it is important to use a material having a small work function for the cathode, and metal electrodes such as Mg-Ag and Al-Li are generally used.

In the organic EL display device having such a structure, the organic luminescent layer is formed of an extremely thin film with a thickness of about 10 nm. Therefore, the organic luminescent layer almost completely transmits the light, like the transparent electrode. As a result, since the light incident on the surface of the transparent substrate at the time of non-emission and transmitted through the transparent electrode and the organic luminescent layer and reflected by the metal electrode again comes out to the surface side of the transparent substrate, The display surface looks like a mirror surface (mirror surface).

In an organic EL display device including an organic electroluminescent light emitting body having a transparent electrode on a surface side of an organic light emitting layer that emits light when a voltage is applied and a metal electrode on a back side of the organic light emitting layer, And a phase difference plate may be provided between the transparent electrode and the polarizing plate.

The retardation plate and the polarizing plate have the effect of preventing the mirror surface of the metal electrode from being viewed (viewed) from the outside due to the polarizing action since the polarizing plate has the function of polarizing the light reflected from the metal electrode when incident from the outside. In particular, the mirror surface of the metal electrode can be completely shielded by forming the retardation plate as a 1/4 wave plate and by forming a circularly polarizing plate in which the linear polarizer and the retarder are combined.

That is, only the linearly polarized light component transmits the external light incident on the organic EL display device by the polarizing plate. This linearly polarized light is generally elliptically polarized by the retardation plate, but becomes circularly polarized light when the angle of the retardation plate reaches 1/4 wavelength and the polarization direction of the polarizing plate and the retardation plate reaches? / 4.

The circularly polarized light is transmitted through the transparent substrate, the transparent electrode and the organic thin film, reflected by the metal electrode, again transmitted through the organic thin film, the transparent electrode and the transparent substrate, and becomes linearly polarized again in the retarder. The linearly polarized light is orthogonal to the polarization direction of the polarizing plate, and thus can not transmit through the polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded. When the angle formed by the absorption axis of the polarizing plate and the slow axis of the 1/4 wave plate is p, it is usually 40 ° to 50 °, and more preferably 40 ° to 50 °, in order to form a circularly polarizing plate in which a 1/4 wave plate is combined with the linearly polarizing plate. Preferably in the range of 42 to 48 degrees, more preferably in the range of about 45 degrees. In a range other than the above range, image quality may deteriorate due to deterioration of the antireflection effect.

Example

EXAMPLES Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

The analytical methods used in the examples are as follows.

(1) Microscopic observation

The alignment state of the liquid crystal was observed with a BH2 polarizing microscope manufactured by Olympus Kogaku Co., Ltd.

(2) Refractive index

The refractive indexes no and ne were measured at a wavelength of 440 to 1000 nm under the conditions of a temperature of 20 DEG C +/- 2 DEG C and a relative humidity of 60 +/- 5% using a spectroscopic ellipsometry (product name: "AUTO-SE" manufactured by Horiba Seisakusho Co., Was measured.

(3) Birefringence measurement

We used an automatic refractometer Axoscan manufactured by Axometrics.

(5) Polarization absorption spectrum of dichroic dye, measurement of transmittance

(V-570) manufactured by Nihon Bunko Co., Ltd.

(Example 1)

&Lt; Preparation of a mixed solution of a polymerizable liquid crystal compound (A) and a dichroic dye [

First, polymerizable liquid crystal compounds (acrylate-based polymerizable liquid crystal compounds) represented by the following formulas (110) to (113) were prepared, respectively.

Each of the polymerizable liquid crystal compounds represented by the above general formulas (110) to (113) was produced by a known method. Specifically, the compound represented by the formula (110) (hereinafter, simply referred to as " liquid crystal compound (I) ") is prepared by the method described in British Patent Application Publication No. 2,280,445, The compound represented by the above general formula (111) (hereinafter, simply referred to as &quot; liquid crystal compound (II) &quot;, hereinafter) can be prepared according to a method described in 1989 (DJ Broer et al., "Makromol. Chem. (112) (hereinafter, simply referred to as &quot; liquid crystal compound (III) &quot;, as occasion demands), and the compound represented by formula (Hereinafter, simply referred to as &quot; liquid crystal compound (IV) &quot;) were prepared by the method described in International Publication No. 93/22397. The polymerizable liquid crystal compounds represented by the general formulas (110) to (113) were all solid at room temperature (25 캜).

Next, the liquid crystal compounds (I) to (IV) were obtained in the same manner as in Example 1 except that the liquid crystal compounds (I) were changed to 35 mass%, the liquid crystal compounds (II): 23 mass%, the liquid crystal compounds (III) IV): 19% by mass, to obtain a first mixture (referred to as a polymerizable liquid crystal compound (A)). Then, the first mixture was added with a dichroic dye (YM-2711, manufactured by YAMADA KAGAKU Co., Ltd., merocyanine system, absorption maximum wavelength: 550 nm) in a proportion of 0.3 parts by weight based on 100 parts by weight of the total amount, (Solid) under a condition of room temperature (25 占 폚) was added in an amount of 4.0 parts by mass per 100 parts by mass of the total amount of the liquid crystal compounds (I) to (IV) and the dichroic dye To obtain a second mixture (solid) of the liquid crystal compounds (I) to (IV) and a mixture of the dichroic dye and the polymerization initiator. Subsequently, the second mixture was dissolved in dichlorobenzene (solvent), and insoluble matter was filtered with a polytetrafluoroethylene filter having a pore diameter of 0.45 mu m to obtain the liquid crystal compound (I) To (IV), a mixed solution (third mixture) containing a dichroic dye, a polymerization initiator and a solvent was obtained. In the production of such a third mixture, the content of the solvent in the third mixture is 80% by mass, and the total amount of the liquid crystal compounds (I) to (IV), the total amount of the dichroic dye and the polymerization initiator By mass to 20% by mass.

&Lt; Production of liquid crystal film &

The alignment substrate was prepared as follows. A polyethylene naphthalate film (manufactured by Teijin Co., Ltd.) having a thickness of 38 탆 was cut out at a 15 cm square and a 5 wt% solution of an alkyl-modified polyvinyl alcohol (PVA: Kuraray Co., MP-203) The solvent was a mixed solvent of water and isopropyl alcohol in a weight ratio of 1: 1) by a spin coat method, dried on a hot plate at 50 占 폚 for 30 minutes, and then heated in an oven at 120 占 폚 for 10 minutes. Then, it was rubbed with rayon cloth of rayon. The film thickness of the obtained PVA layer was 1.2 탆. The rubbing ratio (rubbing cloth moving speed / substrate film moving speed) at the time of rubbing was set to 4.

The liquid crystal compounds (I) to (IV) obtained as described above and a mixed solution (third mixture) containing a dichroic dye, a polymerization initiator and a solvent were applied to the thus obtained alignment substrate by spin coating (Wet film thickness: 5 占 퐉) to obtain a laminate of the coating film and the alignment substrate.

Next, the layered product of the coating film and the alignment substrate was allowed to stand for 2 minutes under the conditions of a pressure of 1013 hPa and a temperature of room temperature (25 캜), thereby removing the solvent from the coating film by drying (solvent removal step). Further, after 2 minutes had elapsed from completion of coating on the alignment substrate, the solvent was removed from the entire surface of the coating film.

Then, with respect to the coating film after dried by a solvent removal process, the illuminance: 15mW / cm ² using a high pressure mercury lamp, and and so that the accumulated irradiation dose is 200mJ / cm ^2, the ultraviolet light (紫外光) (However, the 365nm wavelength (Curing) the liquid crystal compound and fixing the alignment state by irradiating the liquid crystal compound on the liquid crystal cell and irradiating the liquid crystal compound on the alignment substrate, Sieve).

Since the polyethylene naphthalate film used as the substrate has a large birefringence and is not preferable as an optical film, the optically anisotropic layer on the obtained alignment substrate is transferred to a triacetylcellulose (TAC) film through an ultraviolet curable adhesive. That is, an adhesive was applied on the cured liquid crystal film layer on the polyethylene naphthalate film so as to have a thickness of 5 mu m, laminated with a TAC film, irradiated with ultraviolet rays from the TAC film side to cure the adhesive, and the alignment substrate was peeled off .

Observation of the resulting optical film (liquid crystal film / adhesive layer / TAC film) under a polarizing microscope revealed that the mono-domains were uniformly oriented without any desclination.

Further, the extraordinary ray refraction index ne and the phase ray index of refraction no of the liquid crystal film layer of the obtained optical film were measured by spectroscopic erisphometry. The wavelength dispersion characteristics of the refractive index of the liquid crystal film layer are shown in Fig. 14, and the optical characteristic results are summarized in Table 2. [ It was confirmed that, in the range of the measurement wavelength of 540 to 570 nm, the longer the wavelength of the measurement, the larger the extraordinary ray refractive index.

The wavelength dispersion characteristics of the laminate of the TAC film and the liquid crystal film and the retardation (? Nd) in the in-plane direction of the TAC film unit were measured using the product name "Axoscan" manufactured by Axometrix, The wavelength dispersion characteristics of the birefringence of the layer were measured. Fig. 15 shows the wavelength dispersion characteristics of the birefringence of the liquid crystal film layer, and Table 2 summarizes the optical property results. Also,? N d at 550 nm was 138 nm, and? N d (500) /? N d (550) = 0.964 and? N d (580) /? N d (550) = 1.011. Also,? N d (450) /? N d (550) = 1.030 and? N d (650) /? N d (550) = 0.958. In particular, it was confirmed that the retardation increases with the longer wavelength of the measurement wavelength in the range of the measurement wavelength of 540 to 560 nm.

(Example 2)

&Lt; Preparation of a mixed solution of a polymerizable liquid crystal compound (B) and a dichroic dye [

A compound (22) having two or more mesogen groups represented by the following formulas and a rod-like liquid crystal compound (21) were prepared. The compound (22) and the rod-shaped liquid crystal compound (21) were produced by the method described in Japanese Patent Application Laid-Open No. 2002-267838.

Next, a fourth mixture (referred to as a polymerizable liquid crystal compound (B)) was obtained by mixing 2% by weight of the compound (22) and 17.6% by weight of the rod-shaped liquid crystal compound (21). Next, to the fourth mixture, a dichroic dye (M-137 manufactured by Mitsui Chemicals, Inc., anthraquinone system, maximum absorption wavelength: 594 nm, 639 nm) was added in a ratio of 2.0 parts by mass based on 100 parts by mass of the total amount, Further, 0.2 parts by mass of a polymerization initiator (trade name &quot; Irugacure 651 &quot;, manufactured by BASF, solid at room temperature (25 ° C)) was added in an amount of 0.2 parts by mass based on 100 parts by mass of the total amount of the polymerizable liquid crystal compound To obtain a fifth mixture (solid) comprising the polymerizable liquid crystal compound (B) and a mixture of the dichroic dye and the polymerization initiator.

Then, the fifth mixture thus obtained was dissolved in methyl ethyl ketone (solvent), and the insoluble matter was filtered with a polytetrafluoroethylene filter having a pore diameter of 0.45 mu m to obtain the polymerizable liquid crystal compound (B) , A mixed solution (sixth mixture) containing a dichroic dye, a polymerization initiator and a solvent was obtained. Further, in the production of the sixth mixture, the content of the solvent in the sixth mixture is 80% by mass, the total amount of the polymerizable liquid crystal compound (B), the dichroic dye and the polymerization initiator is 20 % By mass.

&Lt; Production of liquid crystal film &

An optical film (optically anisotropic layer / adhesive layer / TAC film) was obtained in the same manner as in Example 1, except that the mixed solution was used. Observation of the resulting optical film (liquid crystal film / adhesive layer / TAC film) under a polarizing microscope revealed that the mono-domains were uniformly oriented without any desclination. FIG. 16 shows the wavelength dispersion characteristics of the refractive index of the liquid crystal film layer, FIG. 17 shows the birefringence wavelength dispersion characteristics of the liquid crystal film layer, and Table 2 lists the optical property results. It was confirmed that, in the range of the measurement wavelength of 570 to 620 nm, the longer the wavelength of the measurement, the larger the extraordinary ray refraction index. ? N d (500) /? N d (550) = 1.018,? N d (580) / n d 550 = 1.030. Also,? N d at 550 nm was 138 nm, and? N d (450) /? N d (550) = 0.962 and? N d (650) /? N d (550) = 1.273. Particularly, it was confirmed that the retardation increases with the longer wavelength of the measurement wavelength in the measurement wavelength range of 400 nm to 510 nm and 560 to 660 nm.

(Example 3)

&Lt; Preparation of a mixed solution of a polymerizable liquid crystal compound (C) and a dichroic dye [

Were mixed at a mass ratio of 23 mass% of the first mixture (polymerizable liquid crystal compound (A)) prepared in Example 1 and 77 mass% of the fourth mixture (polymerizable liquid crystal compound (B)) prepared in Example 2 , And a seventh mixture (referred to as polymerizable liquid crystal compound (C)). Next, the seventh mixture was added with the same dichroic dye as in Example 1 at a ratio of 0.3 parts by weight based on 100 parts by weight of the total amount, and a polymerization initiator (trade name &quot; Irugacure 651 &quot;, trade name, (C) at a ratio of 0.2 parts by mass based on 100 parts by mass of the total amount of the polymerizable liquid crystal compound (C) and the dichroic dye, to obtain the polymerizable liquid crystal compound (C) To obtain an eighth mixture (solid) obtained by mixing the dye and the polymerization initiator.

Subsequently, the eighth mixture was dissolved in methyl ethyl ketone (solvent), and the insoluble matter was filtered with a polytetrafluoroethylene filter having a pore diameter of 0.45 mu m to obtain a polymerizable liquid crystal compound (C), a dichroic dye To obtain a mixed solution (ninth mixture) containing a polymerization initiator and a solvent. Further, in the production of the ninth mixture, the content of the solvent in the ninth mixture is 80% by mass, the total amount of the polymerizable liquid crystal compound (C), the dichroic dye and the polymerization initiator is 20 mass% %. &Lt; / RTI &gt;

&Lt; Production of liquid crystal film &

An optical film (optically anisotropic layer / adhesive layer / TAC film) was obtained in the same manner as in Example 1, except that the mixed solution was used. FIG. 18 shows the wavelength dispersion characteristics of the refractive index of the liquid crystal film layer, FIG. 19 shows the birefringence wavelength dispersion characteristics of the liquid crystal film layer, and Table 2 lists the optical property results.

It was confirmed that, in the range of the measurement wavelength of 540 to 560 nm, the longer the measurement wavelength becomes, the larger the extraordinary ray refractive index becomes. Further,? N d at 550 nm was 138 nm,? N d (500) /? N d (550) = 0.926, and? N d (580) /? N d (550) = 1.024. Also,? N d (450) /? N d (550) = 0.961 and? N d (650) /? N d (550) = 0.971. In particular, it was confirmed that the retardation increases as the measurement wavelength is longer in the range of the measurement wavelength of 500 nm to 530 nm and 540 to 560 nm.

(Example 4)

The dichroic dye (G-241, trisazo dye, absorption maximum wavelength: 560 nm) was added to the total amount of 100 parts by weight of the fourth mixture (polymerizable liquid crystal compound (B)) prepared in Example 2 0.2 parts by mass was added at a ratio of 0.2 part by mass to the total amount of the optical film (optically anisotropic layer / adhesive layer / TAC film). 20 shows the wavelength dispersion characteristics of the birefringence of the liquid crystal film layer, and Table 2 lists the optical characteristic results. Also,? N d at 550 nm was 138 nm,? N d (500) /? N d (550) = 0.963, and? N d (580) /? N d (550) = 1.016. Also,? N d (450) /? N d (550) = 0.897 and? N d (650) /? N d (550) = 1.038. In particular, it was confirmed that the retardation increases as the measurement wavelength becomes longer in the range of the measurement wavelength of 500 nm to 600 nm.

(Example 5)

The dichroic dye (G-241, trisazo dye, absorption maximum wavelength: 560 nm) was added to the total amount of 100 parts by weight of the fourth mixture (polymerizable liquid crystal compound (B)) prepared in Example 2 (Optical anisotropic layer / adhesive layer / TAC film) was obtained in the same manner as in Example 2, except that the optical anisotropic layer / adhesive layer / TAC film was added in a ratio of 0.08 parts by mass. FIG. 21 shows the wavelength dispersion characteristics of the birefringence of the liquid crystal film layer, and Table 2 lists the optical characteristic results. Also,? N d at 550 nm was 138 nm,? N d (500) /? N d (550) = 0.973, and? N d (580) /? N d (550) = 1.014. Also,? N d (450) /? N d (550) = 0.910 and? N d (650) /? N d (550) = 1.029. In particular, it was confirmed that the retardation increases as the measurement wavelength becomes longer in the range of the measurement wavelength of 500 nm to 600 nm.

(Example 6)

(KDR-902, diazo dye, maximum absorption wavelength: 570 nm) was added to the total of the first mixture (polymerizable liquid crystal compound (B)) prepared in Example 2 (Optically anisotropic layer / adhesive layer / TAC film) was obtained in the same manner as in Example 2, except that the addition amount was 0.2 parts by mass based on the total amount of the components. 22 shows the wavelength dispersion characteristics of the birefringence of the liquid crystal film layer, and Table 2 shows the optical characteristics results. Also,? N d at 550 nm was 138 nm,? N d (500) /? N d (550) = 0.966 and? N d (580) /? N d (550) = 1.024. Also,? N d (450) /? N d (550) = 0.894 and? N d (650) /? N d (550) = 1.042.

(Comparative Example 1)

An optical film (optically anisotropic layer / adhesive layer / TAC film) was obtained in the same manner as in Example 1 except that the dichroic dye was not mixed. Fig. 23 shows the wavelength dispersion characteristics of the refractive index of the liquid crystal film layer, Fig. 24 shows the birefringence wavelength dispersion characteristics of the liquid crystal film layer, and Table 2 lists the optical property results.

It was confirmed that the longer the wavelength of the measurement wavelength is, the smaller the extraordinary ray refractive index becomes in the wavelength range of 450 to 700 nm. Also,? N d at 550 nm was 138 nm, and? N d (500) /? N d (550) = 1.033 and? N d (580) /? N d (550) = 0.985. Also,? N d (450) /? N d (550) = 1.080 and? N d (650) /? N d (550) = 0.957. In particular, it was confirmed that the phase difference becomes smaller as the wavelength of the measurement becomes longer in the range of the measurement wavelength of 400 to 700 nm.

(Comparative Example 2)

An optical film (optically anisotropic layer / adhesive layer / TAC film) was obtained in the same manner as in Example 2 except that the dichroic dye was not mixed. FIG. 25 shows the wavelength dispersion characteristics of the refractive index of the liquid crystal film layer, FIG. 26 shows the birefringence wavelength dispersion characteristics of the liquid crystal film layer, and Table 2 lists the optical property results. Further,? N d at 550 nm was 138 nm, and? N d (500) /? N d (550) = 0.981 and? N d (580) /? N d (550) = 1.000. Also,? N d (450) /? N d (550) = 0.907 and? N d (650) /? N d (550) = 1.000. It has been confirmed that the retardation increases as the measurement wavelength becomes longer in the range of the measurement wavelength of 400 to 550 nm, but it is confirmed that the retardation value is substantially constant regardless of the measurement wavelength at 550 nm or more. In addition, it was confirmed that the longer the wavelength of the measurement wavelength is, the smaller the extraordinary ray refractive index becomes in the range of the measurement wavelength of 450 to 700 nm. In particular, it was confirmed that the phase difference becomes smaller as the wavelength of the measurement becomes longer in the range of the measurement wavelength of 400 to 700 nm.

(Comparative Example 3)

An optical film (optically anisotropic layer / adhesive layer / TAC film) was obtained in the same manner as in Example 3, except that the dichroic dye was not mixed. Fig. 27 shows the wavelength dispersion characteristics of the refractive index of the liquid crystal film layer, Fig. 28 shows the birefringence wavelength dispersion characteristics of the liquid crystal film layer, and Table 2 lists the optical property results.

It was confirmed that the longer the wavelength of the measurement wavelength is, the smaller the extraordinary ray refractive index becomes in the wavelength range of 450 to 700 nm. Also,? N d at 550 nm was 138 nm,? N d (500) /? N d (550) = 1.013, and? N d (580) /? N d (550) = 0.990. Also,? N d (450) /? N d (550) = 1.016 and? N d (650) /? N d (550) = 0.973. In particular, it was confirmed that the phase difference becomes smaller as the wavelength of the measurement becomes longer in the range of the measurement wavelength of 400 to 700 nm.

Until now, a system which is not mixed with a system containing a mixture of dichroic dyes was compared in Example 1 and Comparative Example 1, in Examples 2, 4 to 6 and Comparative Example 2, and in Example 3 and Comparative Example 3 , The transmittance of the film (Examples 1 to 3) in which the dichroic dye was mixed was about 0.9 to 0.96 when the transmittance of the film not mixing the dichroic dye (Comparative Examples 1 to 3) was 1, and the transmittance Can be suppressed within 10%.

Based on the above results, the difference in the ratio of the retardation in the system (Examples 1 to 6) in which the dichroic dye was mixed with the system in which the dichroic dye was not mixed (Comparative Examples 1 to 3) That is,

   ? Na da (580) /? Na da (550) -

? Nb · db (580) /? Nb · db (550)

Are as shown in the following Table 3, and all of them are larger than 0, and it is found that the above formula (5) is satisfied.

(Example 7)

The liquid crystal film produced in Example 2 was incorporated into a single polarizing plate reflective liquid crystal display device and evaluated. The composition of the liquid crystal film / glass substrate / ITO transparent electrode / orientation film / twisted nematic liquid crystal / orientation film / metal electrode / reflection film / glass substrate produced in Example 2 from the polarizing plate / The adhesive layer between the layers is omitted. And coloring was evaluated visually by using an angle of fitting such that the white display was obtained when the voltage was turned off. Particularly, it was confirmed that the coloration in the black display at the time of the voltage on was small, whereby the contrast was high and the visibility was excellent.

(Example 8)

The optical film produced in Example 2 was laminated with a commercially available polarizing plate (SRW062 manufactured by Sumitomo Chemical Co., Ltd.), and the optical axis of the polarizing plate and the optical axis of the polarizing plate were brought to 45 degrees through an acrylic adhesive, (Adhered) onto a transparent glass substrate of an organic EL element of an EL display through an acrylic pressure-sensitive adhesive, thereby producing an organic EL display device. As a result, it was found that an organic EL display device exhibiting a remarkable effect of preventing external light reflection and having excellent visibility can be obtained as compared with the case where the circularly polarizing plate is not disposed. The emission spectrum of this organic EL display device is the graph shown in Fig. 13, and it can be seen that even when the optical film produced in Example 2 is laminated, the transmittance reduction is suppressed to about 5% I could confirm.

1: rod-shaped molecule
2: polymer film
3: Discoidal molecules

Claims (15)

1. A retardation film comprising an organic polymer obtained by polymerizing a polymerizable liquid crystal compound in a predetermined liquid crystal alignment state and a film comprising at least one dichroic dye,
Wherein the liquid crystal alignment is in a parallel orientation,
The maximum absorption wavelength of the dichroic dye is in a range of 450 to 700 nm,
Wherein the retardation ratio of the retardation plate at a specific wavelength satisfies the following expressions (4) and (5).
0.80 <? N d (500) /? N? D 550 <1.10 (4)
1.00 <? N d (580) /? N? D (550) <1.15 (5)
(500),? N? D (550) and? N? D (580) when the birefringence of the retarder is denoted by? N and the film thickness of the retarder is denoted by d are wavelengths of 500 nm, 550 nm, Is the retardation of the retardation plate in the liquid crystal cell.) The method according to claim 1,
Wherein the extraordinary ray refraction index ne or the birefringence index n has a "negative dispersion" property in which at least a part of the wavelength region of the visible light region has a larger measurement wavelength. The method according to claim 1,
Wherein the extraordinary ray refraction index ne and birefringence index n have a "negative dispersion" property in which at least a part of the wavelength region of the visible light region has a larger measurement wavelength. 4. The method according to any one of claims 1 to 3,
Wherein the retardation ratio of the retardation plate at a specific wavelength satisfies the following expressions (2) and (3).
0.70 <? N d (450) /? N d 550 <1.00 (2)
1.00 <? N d (650) /? N? D 550 <1.30 (3)
(650) is retardation of each retardation plate at wavelengths of 450 nm, 550 nm, and 650 nm, respectively). Here, Δn · d (450), Δn · d (550) 4. The method according to any one of claims 1 to 3,
Satisfies the following formula (1) when the retardation of the retarder is represented by? Na da, and the retardation of the retardation film comprising the film excluding the dichroic dye is denoted by? Nb · db from the film.
? Na da (580) /? Na da (550) -
? Nb · db (580) /? Nb · db (550)> 0 (1)
(Where retardation is represented by the product of the birefringence Δn of the retarder and the film thickness d of the retarder, and Δna da (580) and Δnb · db (580) are the retardation of each retarder at a wavelength of 580 nm , And? Na da (550) and? Nb 占 db (550) are the retardations of the respective retardation plates at a wavelength of 550 nm). 4. The method according to any one of claims 1 to 3,
Wherein the birefringence of the organic polymer has a "negative dispersion" property. delete delete delete delete 4. The method according to any one of claims 1 to 3,
Wherein the dichroic dye is contained in an amount of 0.03 to 2 parts by mass based on 100 parts by mass of the organic polymer. 4. The method according to any one of claims 1 to 3,
Wherein an absorption maximum wavelength of the dichroic dye is different from an absorption maximum wavelength of an emission spectrum of an image display apparatus. An elliptically polarizing plate comprising the retardation plate according to any one of claims 1 to 3 and a polarizing plate. An image display apparatus comprising the elliptically polarizing plate according to claim 13. 15. The method of claim 14,
Wherein the image display device is a liquid crystal display device or an organic electroluminescence display device.

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