WO2022071204A1

WO2022071204A1 - Polarizing element, polarizing plate and display device provided with same

Info

Publication number: WO2022071204A1
Application number: PCT/JP2021/035317
Authority: WO
Inventors: 典明望月; 陵太郎森田; 由侑服部; 悠衣横山
Original assignee: 日本化薬株式会社
Priority date: 2020-09-29
Filing date: 2021-09-27
Publication date: 2022-04-07
Also published as: CN116097135A; JPWO2022071204A1; TW202231792A

Abstract

A polarizing element which contains, in the form of a free acid: an azo compound represented by formula (1) or a salt thereof, or an azo compound represented by formula (2) or a salt thereof; and an azo compound represented by formula (3) or a salt thereof.

Description

A polarizing element, a polarizing plate, and a display device including the polarizing element.

The present invention relates to a dye-based polarizing element, a polarizing plate, and a display device (display) including the same.

The polarizing element is generally manufactured by adsorbing and orienting iodine or a dichroic dye, which is a dichroic dye, on a polyvinyl alcohol-based resin film. A polarizing plate obtained by laminating a protective film made of triacetyl cellulose or the like on this polarizing element via an adhesive layer is used in a liquid crystal display device or the like. Polarizing plates made with iodine as a dichroic dye are called iodine-based polarizing plates, while polarized light made with a dichroic dye, for example, a dichroic azo compound, as a dichroic dye. The plate is called a dye-based polarizing plate. Dye-based polarizing plates have high heat resistance, high humidity and heat durability, and high stability, and are characterized by high color selectivity due to the blending of dyes, while iodine-based polarizing plates having the same degree of polarization. There was a problem that the transmittance and the contrast were low as compared with the plate. Therefore, a polarizing element having high transmittance, high transmittance, and high polarization characteristics in addition to maintaining high durability and various color selectivity is desired.

Further, even in the case of dye-based polarizing plates having various color selectivity, the conventional polarizing elements have a positional relationship in which the absorption axis directions of the two polarizing elements are parallel to each other (hereinafter, also referred to as "parallel position"). There was a problem that the white color became yellowish white when it was arranged so as to be ()) to show white color (hereinafter, also referred to as "white display time" or "bright display time"). .. Further, even in the case of a polarizing element manufactured by suppressing this yellowness, the conventional polarizing plates have a positional relationship in which the absorption axis directions of the two polarizing elements are orthogonal to each other (hereinafter, also referred to as “orthogonal position”). ), There is a problem that the black color is colored blue when the black color is shown (hereinafter, also referred to as “black display” or “dark display”). Therefore, there has been a demand for a polarizing plate that exhibits achromatic white color when displayed in white and black color when displayed in black. In particular, it has been difficult to obtain a polarizing plate having high-quality white when displayed in white, commonly known as a paper-white polarizing plate. Further, in order for the polarizing plate to be achromatic, it is necessary that the transmittance of each wavelength at the parallel position and the orthogonal position is a substantially constant value regardless of the wavelength, and it is possible to obtain such a polarizing plate. It wasn't possible until now.

The reason why the hues in white display and black display are different is that the wavelength dependence of the transmittance is not the same in the parallel position and the orthogonal position, and in particular, the transmittance is not constant over the visible light region. Further, the fact that the dichroism is not constant over the visible light region is one of the factors that make it difficult to realize an achromatic polarizing plate.

Taking an iodine-based polarizing plate as an example, an iodine-based polarizing plate manufactured by using polyvinyl alcohol (hereinafter, also referred to as “PVA”) as a base material and iodine as a dichroic dye is generally used. It has absorption in the region centered on 480 nm and 600 nm. It is said that the absorption at 480 nm is due to the complex of polyiodide I _3- ^and PVA, and the absorption at 600 nm is due to the complex of polyiodide I _5- ^and PVA. Regarding the degree of polarization (dichroism) at each wavelength, the degree of polarization based on the complex of polyiodide I _5- ^and PVA (dichroism) is the degree of polarization based on the complex of polyiodide I _3- ^and PVA (dichroism). Higher than dichroism). That is, when trying to make the transmittance at the orthogonal position constant at each wavelength, the transmittance at the parallel position is higher at 600 nm than at 480 nm, and a phenomenon that white is colored yellow when displayed in white has occurred. On the contrary, when trying to make the transmittance at the parallel position constant, the transmittance at the orthogonal position is lower at 600 nm than at 480 nm, so that black is colored blue when displayed in black. When the white color is yellow when the white color is displayed, it is not preferable because it generally gives the impression that the deterioration has progressed. Also, if the blue color disappears when displaying black, it gives the impression that there is no sense of luxury because it is not clear black. Further, in the iodine-based polarizing plate, it is difficult to control the hue mainly in the vicinity of 550 nm, which has high visual sensitivity, because there is no complex based on the wavelength. As described above, since the degree of polarization (dichroism) of each wavelength is not constant, the wavelength dependence of the degree of polarization (dichroism) has occurred. Further, since there are only two dichroic dyes of 480 nm and 600 nm, which are absorbed by the complex of iodine and PVA, the hue cannot be adjusted by the iodine-based polarizing plate composed of iodine and PVA.

A method for improving the hue of an iodine-based polarizing plate is described in Patent Document 1 and Patent Document 2. Patent Document 1 describes a polarizing plate having a neutral coefficient calculated and an absolute value of 0 to 3. Patent Document 2 describes a polarizing element in which the transmittance at 410 nm to 750 nm is within ± 30% of the average value, and the color is adjusted by directly adding a dye, a reactive dye, or an acid dye in addition to iodine. Has been done. Further, as in Patent Document 3, a technique of an achromatic dye-based polarizing plate is also disclosed.

However, as can be seen from Example 1 of the polarizing plate of Patent Document 1, even if the neutral coefficient (Np) is low, the parallel hue obtained from JIS Z 8729 has an a * value of −1.67. Moreover, since the b * value is 3.51, it can be seen that the color is yellowish green when displayed in white. Further, the hue at the orthogonal position has an a * value of 0.69, but since the b * value is -3.40, the black display is a polarizing plate exhibiting blue. The polarizing element of Patent Document 2 is obtained by setting the a * value and b * value in the UCS color space measured using only one polarizing element to an absolute value of 2 or less, and two polarizing elements are stacked. It was not possible to express achromatic colors at the same time in both the hues of white display and black display. Further, the average value of the single transmittance of the polarizing element of Patent Document 2 was 31.95% in Example 1 and 31.41% in Example 2, showing low values. As described above, since the polarizing element of Patent Document 2 has a low transmittance, it does not have sufficient performance in fields where high transmittance and high contrast are required, particularly in fields such as liquid crystal displays and organic electroluminescence. .. Further, since the polarizing element of Patent Document 2 is manufactured by using iodine as a main dichroic dye, after the durability test, in particular, a moist heat durability test (for example, an environment of 85 ° C. and a relative humidity of 85%). ) Later, the color change was large and the durability was inferior.

On the other hand, the dye-based polarizing plate has excellent durability, but the wavelength dependence differs between the parallel position and the orthogonal position, which is the same as the iodine-based polarizing plate. There are almost no dichroic azo compounds showing the same hue at the parallel and orthogonal positions, and even if they exist, the dichroism (polarization characteristics) is low. Depending on the type of azo compound having bichromaticity, there are azo compounds having completely different wavelength dependence in orthogonal and parallel positions, such as white in white display showing yellow and black in black display showing blue. .. In addition, since the sensitivity of human color differs depending on the brightness of the light, even if the color of the dye-based polarizing plate is corrected, the brightness of the light generated by controlling the polarization in both the orthogonal and parallel positions is different. Color correction suitable for each is required. The achromatic polarizing plate cannot be achieved unless the transmittance is a substantially constant value at each wavelength in each of the parallel position and the orthogonal position and there is no wavelength dependence. Further, in order to obtain a polarizing element having high transmittance and high contrast, in addition to simultaneously satisfying a constant transmittance at the parallel position and the orthogonal position, the degree of polarization (two-color ratio) of each wavelength is high and the degree of polarization (two-color ratio) is high. , Must be constant. Even when one type of azo compound is used for manufacturing a polarizing element, even though the wavelength dependence of the transmittance of each wavelength differs between the orthogonal position and the parallel position, two or more types of azo compounds are blended to each wavelength. In order to achieve a certain transmittance, it is necessary to precisely control the relationship between two or more types of two-color ratios in consideration of the transmittance of each type of parallel position and orthogonal position.

On the other hand, even if the relationship between the transmittance and the two-color ratio of each wavelength in the parallel position and the orthogonal position can be precisely controlled and the transmittance can be made constant at each wavelength, the transmittance is high and high. Achieving contrast has not yet been achieved. That is, the higher the transmittance or the higher the degree of polarization, the more difficult it is to make the color achromatic, and it has not been possible to achieve an achromatic polarizing plate having a high transmittance or a high degree of polarization. It is very difficult to obtain an achromatic polarizing plate with high transmittance and / or high contrast, and it cannot be achieved by simply applying a dichroic dye of the three primary colors. In particular, it is extremely difficult to simultaneously achieve constant transmittance and high dichroism at each wavelength in the parallel position. White cannot express high-quality white even with a slight amount of color. In addition, white in the bright state is particularly important because it has high luminance and high sensitivity. Therefore, as a polarizing element, it exhibits an achromatic white color like high-quality paper when displayed in white, an achromatic black color when displayed in black, and has a single transmittance of 35% or more and a high degree of polarization after correction of luminosity factor. There is a demand for a polarizing element to have. Patent Document 3 also describes an achromatic polarizing plate when displaying white and displaying black, but further improvement in performance is desired.

Japanese Unexamined Patent Publication No. 2002-169024 Japanese Unexamined Patent Publication No. 10-13301 WO2014 / 162635 Gazette Japanese Unexamined Patent Publication No. 2006-182846 JP-A-2007-084033 WO2016 / 186194 WO2016 / 186195 Japanese Unexamined Patent Publication No. 11-218611 Japanese Unexamined Patent Publication No. 2001-0332627 Japanese Unexamined Patent Publication No. 2004-251962 Japanese Unexamined Patent Publication No. 8-291259

Therefore, an object of the present invention is to provide a polarizing element having high transmittance and high degree of polarization as one form, or a polarizing plate thereof. Further, one form provides a high-performance polarizing element or polarizing plate and a display device that are achromatic in white display or both in white display and black display, and exhibit high-quality white color particularly in white display. That is.

As a result of diligent studies to solve the above problems, the present inventors have made an azo compound represented by the formula (1) or an azo compound represented by the formula (2) and an azo compound represented by the formula (3). The present invention has been completed by using it for producing a polarizing element or a polarizing plate containing at least.

That is, the present invention relates to the following [Invention 1] to [Invention 17], but is not limited thereto.
[Invention 1]
In the form of free acid, an azo compound represented by the following formula (1) or a salt thereof or an azo compound represented by the following formula (2) or a salt thereof and an azo compound represented by the following formula (3) or a salt thereof. A polarizing element containing a salt.

(In the formula (1), Ac ₁ independently represents a phenyl group or a naphthyl group having at least one substituent selected from a sulfo group and a carboxy group, and Rc ₁₁ to Rc ₁₄ are independent of each other. Represents a hydrogen atom, an alkyl group of C1 to 4, an alkoxy group of C1 to 4, or an alkoxy group of C1 to 4 having a sulfo group.)

(In the formula (2), Ac ₂ represents a phenyl group or a naphthyl group having at least one substituent selected from a sulfo group and a carboxy group, and Rc ₂₁ to Rc ₂₈ are independent hydrogen atoms, respectively. Represents an alkoxy group of C1 to 4 having an alkyl group of C1 to 4, an alkoxy group of C1 to 4 or a sulfo group, and Xc ₂ is an amino group or a substituent which may have at _least one substituent S2. Represents a phenylamino group which may have a phenylamino group, a phenylazo group which may have a substituent, a _{naphthotriazole} group which may have a substituent or a benzoylamino group which may have a substituent, and a substituent S2. (Independently if there are more than one), an alkyl group of C1-4 which may further have a substituent, an alkoxy group of C1-4, a sulfo group, an alkylamino group of C1-4, a hydroxy group, It is selected from an amino group, a substituted amino group, a carboxy group, and a carboxyethyl amino group, and r, p, and q each independently indicate 0 or 1, except when r, p, and q are all 1. Further, when either p or q is 1 and Ac ₂ is a naphthyl group, it does not contain a hydroxy group as a substituent.)

(In formula (3), Ra ₁ , Ra ₂ , Ab ₁ or Ab ₂ is substituted with either ring a or ring b, and either one of Ra ₁ or Ra ₂ is a hydroxy group and the other. Represents a hydrogen atom, a hydroxy group, an alkoxy group of C1 to 4 or an alkoxy group of C1 to 4 having a sulfo group, and either Ab ₁ or Ab ₂ may have a sulfo group, a carboxy group or a substituent. Representing an amino group, the other is a substituent selected from a hydrogen atom, a sulfo group, a carboxy group, or an amino group which may have a substituent, and Rb ₁ to Rb ₆ are independently hydrogen atoms. , C1-4 alkyl group, C1-4 alkoxy group, sulfo group, C1-4 alkoxy group having sulfo group, or amino group which may have a substituent, h represents 0 or 1. , Xb ₁ may have an amino group which may have at least one substituent S ₃ , a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, or a substituent. A good naphthotriazole group or a benzoylamino group which may have a substituent is shown, and the substituent S3 ₍ independently if there is more than one) is an alkyl group of C1-4 which may further have a substituent. , C1-4 alkoxy group, sulfo group, amino group, C1-4 alkylamino group, hydroxy group, carboxy group and carboxyethylamino group).
[Invention 2]
The polarizing element according to Invention 1, further comprising an azo compound represented by the following formula (4) or a salt thereof, or an azo compound represented by the formula (5) or a salt thereof.

(In the formula (4), Ay ₁₁ independently represents a sulfo group, a carboxy group, a hydroxy group, an alkyl group of C1 to 4 or an alkoxy group of C1 to 4, and Ry ₁₁ to Ry ₁₄ independently represent hydrogen atoms. , C1-4 alkyl group, C1-4 alkoxy group or C1-4 alkoxy group having sulfo group, f indicates an integer of 1-3)

(In the formula (5), Ay ₂₁ and Ay ₂₂ are independently naphthyl groups which may have a substituent or a phenyl group which may have a substituent, and are Ry ₂₁ , Ry ₂₂ , Ry ₂₇ , and Ry 27. And Ry ₂₈ are independently hydrogen atoms, C1 to 4 alkyl groups, and C1 to 4 alkoxy groups, and Ry ₂₃ to Ry ₂₆ are independently hydrogen atoms, C1 to 4 alkyl groups, and C1 to C1 to Ry 26, respectively. It is an alkoxy group of C1 to 4 having an alkoxy group of 4 and a sulfo group, and s and t independently indicate 0 or 1 respectively.)
[Invention 3]
The polarizing element according to Invention 1 or 2, wherein the azo compound represented by the formula (3) or a salt thereof is an azo compound represented by the following formula (6) or a salt thereof.

(In the formula (6), Ra ₁ , Ra ₂ , Ab ₁ , Ab ₂ , Rb ₁ to Rb ₆ , h, and Xb ₁ have the same meanings as those in the formula (3).)
[Invention 4]
The polarizing element according to any one of Inventions 1 to 3, wherein the azo compound represented by the formula (3) or a salt thereof is an azo compound represented by the following formula (7) or a salt thereof.

(In the formula (7), Ra ₁ , Ra ₂ , Ab ₁ , Ab ₂ , Rb ₁ to Rb ₆ , h, and Xb ₁ have the same meanings as those in the formula (3).)
[Invention 5]
The polarizing element according to any one of 1 to 4, wherein the azo compound represented by the formula (3) or a salt thereof is an azo compound represented by the following formula (8) or a salt thereof.

(In the formula (8), Ra ₁ , Ab ₁ , Rb ₁ to Rb ₆ , h, and Xb ₁ have the same meanings as in the formula (3), and Ra ₃ represents a hydrogen atom or a hydroxy group.)
[Invention 6]
The polarizing element according to any one of Inventions 1 to 5, wherein the azo compound represented by the formula (3) or a salt thereof is an azo compound represented by the following formula (9) or a salt thereof.

(In the above formula (9), Ra ₁ , Ab ₁ , Rb ₁ to Rb ₆ , h, and Xb ₁ have the same meanings as those in the formula (2).)
[Invention 7]
The average transmittance of 420 nm to 480 nm and the average transmittance of 520 nm to 590 nm are obtained in the transmittance of each wavelength obtained by stacking two polarizing elements so that their absorption axis directions are parallel to each other. Inventions 1 to 6 in which the difference is 2.5% or less as an absolute value, and the difference between the average transmittance of 520 nm to 590 nm and the average transmittance of 600 nm to 640 nm is 3.0% or less as an absolute value. The polarizing element according to any one of the above items.
[Invention 8]
Any of the inventions 1 to 7, wherein the absolute values of the a * value and the b * value in the polarizing element alone, which are obtained when the transmittance is measured using natural light according to JIS Z 8781-4: 2013, are both 1.0 or less. The polarizing element according to item 1.
[Invention 9]
According to JIS Z 8781-4: 2013 in a state where two polarizing elements are stacked so that their absorption axis directions are parallel to each other, the a * value obtained at the time of transmittance measurement using natural light is -2. The polarizing element according to any one of the inventions 1 to 8, which is 0.0 to 2.0 and has an absolute value of b * of −2.0 to 3.0.
[Invention 10]
The single transmittance of the polarizing element after correction of the visual sensitivity is 35% to 65%, and the wavelength band is 520 nm to 590 nm in a state where two polarizing elements are stacked so as to be parallel to each other in the absorption axis direction. The polarizing element according to any one of the inventions 1 to 9, wherein the average transmittance of the above is 25% to 50%.
[Invention 11]
The difference between the average transmittance of 420 nm to 480 nm and the average transmittance of 520 nm to 590 nm is 1.0% as an absolute value when two polarizing elements are stacked so that their absorption axis directions are orthogonal to each other. The polarizing element according to any one of the inventions 1 to 10, wherein the difference between the average transmittance of 520 nm to 590 nm and the average transmittance of 600 nm to 640 nm is 1.0% or less as an absolute value.
[Invention 12]
In a state where two polarizing elements are stacked so that their absorption axis directions are orthogonal to each other, the orthogonal position transmittance of each wavelength in the wavelength band of 420 nm to 480 nm, 520 nm to 590 nm and 600 nm to 640 nm is 1%. The polarizing element according to any one of Inventions 1 to 11, wherein the degree of polarization is as follows, or the degree of polarization after correction of visual sensitivity is 97% or more.
[Invention 13]
In a state where two polarizing elements are stacked so that their absorption axis directions are orthogonal to each other, the a * value and b * value at the time of transmittance measurement using natural light are determined according to JIS Z 8781-4: 2013. The polarizing element according to any one of Inventions 1 to 12, wherein the absolute value is 2.0 or less.
[Invention 14]
The polarizing element according to any one of inventions 1 to 13, which comprises a base material.
[Invention 15]
The polarizing element according to invention 14, which comprises a polyvinyl alcohol-based resin film as a base material.
[Invention 16]
A polarizing plate provided with a transparent protective layer provided on one side or both sides of the polarizing element according to any one of the inventions 1 to 15.
[Invention 17]
A display device including the polarizing element according to any one of the inventions 1 to 15 or the polarizing plate according to the invention 16.

The polarizing element of the present invention or its polarizing plate has high transmittance and high degree of polarization. As another aspect, the polarizing element of the present invention further has a characteristic that the dichroism is not wavelength-dependent and the transmittance is constant at each of the parallel position or the parallel position and the orthogonal position. In another aspect, the polarizing element of the present invention has an achromatic hue in both white and black display. In another aspect, the polarizing element of the present invention or its polarizing plate has high durability.

In the present specification and claims, "azo compound or salt thereof" may be simply referred to as "azo compound" unless it clearly represents a free form.

In the claims and the specification of the present application, since the "substituent" may contain a hydrogen atom, the hydrogen atom may be described as a "substituent" for convenience. "May have a substituent" means that a case without a substituent is also included. For example, a "phenyl group which may have a substituent" includes an unsubstituted mere phenyl group and a phenyl group having a substituent. Further, unless otherwise specified, the "lower" such as the lower alkyl group and the lower alkoxy group of the present application has a carbon atom number of 1 to 4 (C1 to 4), preferably 1 to 3 (C1 to 3). Is shown.

Examples of the above-mentioned "C1-4 aliphatic hydrocarbon group" include linear alkyl groups such as methyl group, ethyl group, n-propyl group and n-butyl group, sec-butyl group and tert-butyl group. Examples thereof include unsaturated hydrocarbon groups such as a branched alkyl group and a vinyl group.

Examples of the above-mentioned "alkoxy group of C1 to 4" include a methoxy group, an ethoxy group, a propoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group and the like.

The polarizing element of the present invention is an azo compound represented by the above formula (1) or a salt thereof, or an azo compound represented by the formula (2) or a salt thereof, and an azo compound represented by the formula (3) or a salt thereof. Contains its salt. The polarizing element according to the present invention may further contain an azo compound represented by the above formula (4) or an azo compound represented by the formula (5).

The polarizing element of the present invention preferably includes a base material, and the azo compound is contained in the base material. The base material is preferably a film obtained by forming a film of a hydrophilic polymer capable of adsorbing a dichroic dye, particularly an azo compound. The hydrophilic polymer is not particularly limited, and is, for example, a polyvinyl alcohol-based resin, an amylose-based resin, a starch-based resin, a cellulosic-based resin, a polyacrylic acid salt-based resin, and the like. The hydrophilic polymer is most preferably a polyvinyl alcohol-based resin or a derivative thereof from the viewpoint of dyeability, processability, crosslinkability and the like of the dichroic dye. A polarizing element can be manufactured by adsorbing an azo compound on a substrate and applying an orientation treatment such as stretching.

First, the azo compound represented by the following formula (1) will be described.

In the above formula (1), when Ac ₁ is a phenyl group, the substituents thereof include a sulfo group, a carboxy group, a lower alkyl group, a lower alkoxy group, a lower alkoxy group having a sulfo group, a nitro group and an amino group. Examples thereof include an acetylamino group and a lower alkylamino group substituted amino group, and it is preferable to have at least one sulfo group or a carboxy group. When the phenyl group has two or more substituents, at least one of the substituents is a sulfo group or a carboxy group, and the other substituent is preferably a sulfo group, a carboxy group, a lower alkyl group or a lower alkoxy. It is selected from a group, a lower alkoxy group having a sulfo group, a nitro group, an amino group, an acetylamino group and a lower alkylamino group substituted amino group, and more preferably a sulfo group, a methyl group, an ethyl group, a methoxy group and an ethoxy group. It is selected from a carboxy group, a nitro group and an amino group, and particularly preferably selected from a sulfo group, a methyl group, a methoxy group, an ethoxy group and a carboxy group. As the lower alkoxy group having a sulfo group, a linear alkoxy group is preferable, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. The lower alkoxy group having such a sulfo group is more preferably a 3-sulfopropoxy group or a 4-sulfobutoxy group, and particularly preferably a 3-sulfopropoxy group. When the phenyl group has a sulfo group as a substituent, the number of sulfo groups is preferably 1 or 2. The substitution position of the sulfo group is not particularly limited, but when there is one sulfo group, the position of the azo group is set to the 1st position, the 4-position of the phenyl group is preferable, and two sulfo groups are used. In some cases, a combination of the 2- and 4-positions of the phenyl group or a combination of the 3- and 5-positions of the phenyl group is preferred.

In the above formula (1), when Ac ₁ is a naphthyl group, examples thereof include a sulfo group, a hydroxy group, a carboxy group and a lower alkoxy group having a sulfo group, and having at least one sulfo group. Is preferable. When the naphthyl group has two or more substituents, at least one of the substituents is a sulfo group, and the other substituent is preferably a lower alkoxy having a sulfo group, a hydroxy group, a carboxy group and a sulfo group. Selected from the group. As the lower alkoxy group having a sulfo group, a linear alkoxy group is preferable, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. The lower alkoxy group having such a sulfo group is more preferably a 3-sulfopropoxy group or a 4-sulfobutoxy group, and particularly preferably a 3-sulfopropoxy group. When the number of sulfo groups substituted with naphthyl groups is 2, the position of the azo group is the 2-position, and the substitution position of the sulfo group is the combination of the 4-position and the 8-position of the naphthyl group or the combination of the 6-position and the 8-position. Is preferable, and the combination of the 6-position and the 8-position is more preferable. When the number of sulfo groups substituted with naphthyl groups is 3, the substitution position of the sulfo group is preferably a combination of 1-position, 3-position and 6-position, and a combination of 3-position, 6-position and 8-position. ..

In the above formula (1), Rc ₁₁ to Rc ₁₄ each independently represent a lower alkoxy group having a hydrogen atom, a lower alkyl group, a lower alkoxy group or a sulfo group. As the lower alkoxy group having a sulfo group, a linear alkoxy group is preferable, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. Rc ₁₁ to Rc ₁₄ are preferably hydrogen atoms, methyl groups, ethyl groups, methoxy groups, ethoxy groups, 3-sulfopropoxy groups or 4-sulfobutoxy groups, respectively, and particularly preferably hydrogen atoms. It is a methyl group, a methoxy group or a 3-sulfopropoxy group. As the substitution position of the phenyl group in which Rc ₁₁ to Rc ₁₄ are substituted, when the substitution position of the azo group on the ureido skeleton side is set to the 1st position, preferably only the 2nd position of the phenyl group, only the 5th position, the 2nd position and the 6th position are used. It is a combination of positions, a combination of 2nd and 5th positions, a combination of 3rd and 5th positions, and particularly preferably a combination of 2nd and 5th positions and 2nd and 5th positions. In addition, only the 2nd place and the 5th place are related to Rc ₁₁ and Rc ₁₂ , and Rc ₁₃ and Rc ₁₄ , and either Rc ₁₁ and Rc ₁₂ or Rc ₁₃ and Rc ₁₄ are in 2nd place or 5th place. It means that it has one substituent other than a hydrogen atom only at the position and the other is a hydrogen atom.

Among the azo compounds represented by the above formula (1), the azo compound represented by the following formula (1b) is particularly preferable. By using such an azo compound, the polarization performance of the polarizing element can be further improved.

(In the formula, Ac ₁ and Rc ₁₁ to Rc ₁₄ have the same meanings as in the formula (1), respectively.)

The azo compound represented by the above formula (1) or the azo compound represented by the formula (1b) shall be produced by, for example, known diazotization and uraido formation as described in Patent Documents 4 to 7. However, it is not limited to these.

Specific examples of the azo compound represented by the formula (1) include the following azo compounds in the form of free acid.

Next, the azo compound represented by the formula (2) will be described.

In the formula (2), Ac ₂ represents a phenyl group or a naphthyl group having at least one substituent selected from a sulfo group and a carboxy group, and Rc ₂₁ to Rc ₂₈ are independent hydrogen atoms and C1 respectively. Represents an alkoxy group of C1 to 4 having an alkyl group of to 4, an alkoxy group of C1 to 4, or a sulfo group, and Xc ₂ is an amino group or a substituent which may have at _least one substituent S2. Represents a phenylamino group which may have a phenylamino group, a phenylazo group which may have a substituent, a _{naphthotriazole} group which may have a substituent or a benzoylamino group which may have a substituent, and a substituent S2. (Independently if there are multiple groups), C1-4 alkyl group, C1-4 alkoxy group, sulfo group, C1-4 alkylamino group, hydroxy group, amino group, substituted amino group, carboxy group , And carboxyethylamino groups, where r, p, q each independently represent 0 or 1, except that r, p, q are all 1, and only one of p or q. When 1 is and Ac ₂ is a naphthyl group, it does not contain a hydroxy group as a substituent.

In the above formula (2), when Ac ₂ is a phenyl group having a substituent, the phenyl group is a sulfo group, a carboxy group, an alkyl group of C1 to 4 and an alkoxy group of C1 to 4 as a substituent, and a sulfo group. C1-4 alkoxy group, hydroxy group, nitro group, amino group, or substituted amino group (particularly, acetylamino group or C1-4 alkylamino group) having at least one sulfo group or carboxy group. It is preferable to have. When the phenyl group has two or more substituents, at least one of those substituents is a sulfo group or a carboxy group, and the other substituents are a sulfo group, a carboxy group, an alkyl group of C1-4, C1. It is preferably an alkoxy group of 4 to 4, an alkoxy group of C1 to 4 having a sulfo group, a hydroxy group, a nitro group, an amino group, or a substituted amino group (particularly, an acetylamino group or an alkylamino group of C1 to 4). , The other substituent is more preferably a sulfo group, a carboxy group, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a hydroxy group, a nitro group, or an amino group, and a sulfo group, a carboxy group, a methyl group, It is particularly preferably a methoxy group or an ethoxy group. Further, as the alkoxy group of C1 to C4 having a sulfo group, a linear alkoxy group is preferable, and the substitution position of the sulfo group is preferably the end of the alkoxy group. As the alkoxy group of C1 to 4 having a sulfo group, a 3-sulfopropoxy group or a 4-sulfobutoxy group is more preferable, and a 3-sulfopropoxy group is particularly preferable. The number of substituents on the phenyl group is preferably 1 or 2, and the position of the substituent on the phenyl group is not particularly limited, but is only at the 4-position, a combination of the 2-position and the 4-position, or 3 It is preferable to use a combination of the 5th place and the 5th place.

In the above formula (2), when Ac ₂ is a naphthyl group having a substituent, the naphthyl group is selected from a sulfo group, a hydroxy group, a carboxy group, or an alkoxy group of C1 to 4 having a sulfo group as the substituent. It is preferable to have at least one sulfo group. When a naphthyl group has two or more substituents, at least one of those substituents is a sulfo group and the other substituents are C1-4 having a sulfo group, a hydroxy group, a carboxy group, or a sulfo group. It is preferably an alkoxy group of. Further, as the alkoxy group of C1 to C4 having a sulfo group, a linear alkoxy group is preferable, and the substitution position of the sulfo group is preferably the end of the alkoxy group. As the alkoxy group of C1 to 4 having a sulfo group, a 3-sulfopropoxy group or a 4-sulfobutoxy group is more preferable, and a 3-sulfopropoxy group is particularly preferable. When the number of sulfo groups on the naphthyl group is 2, the substitution position of the azo group is preferably the 2-position, and the substitution position of the sulfo group is preferably a combination of the 4-position and the 8-position or a combination of the 6-position and the 8-position. , A combination of 6th and 8th positions is particularly preferable. When the number of sulfo groups on the naphthyl group is 3, the substitution positions of the sulfo groups are the combination of the 1-position, the 3-position and the 6-position with the substitution position of the azo group as the 2-position, and the 3-position, the 6-position and the 8-position. It is particularly preferable to use a combination of.

In the above formula (2), Xc ₂ has an amino group which may have at least one substituent S ₂ , a phenylamino group which may have at least one substituent, and at least one substituent. A phenylazo group which may have a phenylazo group, a naphthotriazole group which may have at least one substituent, a benzoyl group which may have at least one substituent, or a benzoylamino group which may have at least one substituent. , Preferably a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a naphthotriazole group which may have a substituent, and a benzoyl which may have a substituent. Examples thereof include a benzoylamino group which may have a group or a substituent, and particularly preferable Xc ₂ is a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, and a substituent. Examples thereof include a benzoylamino group which may have. The substituent is selected from a lower alkyl group, a lower alkoxy group, a sulfo group, a lower alkylamino group, a hydroxy group, an amino group, a substituted amino group, a carboxy group, and a carboxyethylamino group.

When Xc ₂ is an amino group which may have at least one substituent S ₂ , the amino group may be unsubstituted, but preferably a lower alkyl group, a lower alkoxy group, a sulfo group and a carboxy group. , Amino group, substituted amino group, and substituent selected from lower alkylamino group, more preferably methyl group, methoxy group, sulfo group, carboxy group, amino group and lower alkylamino. It has one or two substituents selected from the groups.

When Xc ₂ is a phenylamino group which may have at least one substituent, the phenylamino group is unsubstituted or preferably a lower alkyl group, a lower alkoxy group, a sulfo group, and the like. It has one or two substituents selected from an amino group and a lower alkylamino group, more preferably one or two substituents selected from a methyl group, a methoxy group, a sulfo group and an amino group. ..

When Xc ₂ is a phenylazo group which may have at least one substituent, the phenylazo group is unsubstituted or preferably an hydroxy group, a lower alkyl group, a lower alkoxy group or an amino group. And 1 to 3 substituents selected from the carboxyethylamino group, more preferably 1 to 3 substituents selected from the methyl group, methosiki group, carboxyethylamino group, amino group and hydroxy group. Have.

When Xc ₂ is a naphthotriazole group which may have at least one substituent, the naphthotriazole group is unsubstituted or preferably selected from a sulfo group, an amino group and a carboxy group. It has one or two substituents, more preferably one or two sulfo groups as substituents.

When Xc ₂ is a benzoylamino group which may have at least one of the above substituents, the benzoylamino group is unsubstituted or preferably an hydroxy group, an amino group and a carboxyethylamino group. It has one substituent selected from, more preferably one or two hydroxy or amino groups as substituents.

When Xc ₂ is a benzoylamino group which may have at least one substituent, the benzoyl moiety is unsubstituted or preferably selected from hydroxy, amino and carboxyethylamino groups. It has one substituent, more preferably one or two hydroxy or amino groups as the substituent.

The substitution position of the substituent which the phenylamino group, the phenylazo group and the benzoylamino group may have is not particularly limited, but one of the substituents is for each of the amino group, the azo group or the amide group. It is preferably at the p-position. The substitution position of Xc ₂ is preferably 6-position or 7-position, and more preferably 6-position, when the position of the hydroxy group of the substituted naphthyl group is 1-position.

In the above formula (2), Rc ₂₁ to Rc ₂₈ each independently represent a lower alkoxy group having a hydrogen atom, a lower alkyl group, a lower alkoxy group or a sulfo group. Rc ₂₁ to Rc ₂₈ are each independently preferably a hydrogen atom, an alkyl group of C1 to 4, an alkoxy group of C1 to 4, or a linear alkoxy group having a sulfo group at the terminal, preferably a hydrogen atom and a methyl. A group, an ethyl group, a methoxy group, an ethoxy group, a 3-sulfopropoxy group, or a 4-sulfobutoxy group is more preferable, and a hydrogen atom, a methyl group, a methoxy group, or a 3-sulfopropoxy group is particularly preferable. preferable.

In the above formula (2), in particular, Rc ₂₇ and Rc ₂₈ are independent and preferably a lower alkoxy group having a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a sulfo group, so that the permeability is high. It is possible to reach a high degree of polarization, more preferably a hydrogen atom, an alkyl group of C1 to 3, an alkoxy group of C1 to 3, and preferably a hydrogen atom, a methyl group, an ethyl group, a methoxy group, or an ethoxy group. More preferably, it is a hydrogen atom, a methyl group, and a methoxy group, and it is particularly preferable.

In the above equation (2), r, p or q are independently 0 or 1, respectively. In order to obtain good polarization performance in the polarizing element of the present invention, when one of p and q is 0, the other is preferably 1, and it is more preferable that both p and q are 1. Further, in order to obtain even better polarization characteristics, it is preferable that r is 1 and either p or q or both are 0. When r, p and q are all 1, the content in the substrate, for example, the dyeability on a polyvinyl alcohol film may decrease.

Among the azo compounds represented by the above formula (2), the azo compound represented by the following formula (2b) is preferable. By using such an azo compound, the polarization performance of the polarizing element can be further improved.

(In the formula (2b), Ac ₂ , Rc ₂₁ to Rc ₂₈ , Xc ₂ , r, p, and q each have the same meaning as the formula (2).)

Next, specific examples of the azo compound represented by the formula (2) are given below. The following compound examples are expressed in the form of free acid.

Examples of the azo compound whose free acid form is represented by the formula (2) and the azo compound represented by the formula (2b) include C.I. I. Direct Red 117, C.I. I. Direct Red 127, JP-A-3-12606, JP-A-8-291259, JP-A-9-302250, JP-A-2002-2753811, International Publication No. 2005/075572, International Publication No. 2012 / Examples thereof include azo compounds described in JP-A-108169 and JP-A-2012 / 108173.

Examples of the method for synthesizing the azo compound represented by the formula (2) and the azo compound represented by the formula (2b) include JP-A-3-12606, JP-A-8-291259, and JP-A-9-302250. Examples thereof include the methods described in Japanese Patent Laid-Open No. 2002-275381, International Publication No. 2005/075572, International Publication No. 2012/108169, International Publication No. 2012/108173, and the like. Not limited to.

Next, the azo compound represented by the following formula (3) will be described.

(In formula (3), Ra ₁ , Ra ₂ , Ab ₁ , and Ab ₂ are substituted with either ring a or ring b, and either one of Ra ₁ or Ra ₂ is a hydroxy group and the other. Represents a hydrogen atom, a hydroxy group, a C1-4 alkoxy group having a C1-4 alkoxy group or a sulfo group, and Ab ₁ and Ab ₂ may have a hydrogen atom, a sulfo group, a carboxy group, or a substituent. A substituent selected from good amino groups, wherein either Ab ₁ or Ab ₂ represents an amino group which may have a sulfo group, a carboxy group, or a substituent, and Rb ₁ to Rb ₆ are. Each independently represents a hydrogen atom, an alkyl group of C1-4, an alkoxy group of C1-4, a sulfo group, an alkoxy group of C1-4 having a sulfo group, or an amino group which may have a substituent. h represents 0 or 1, and Xb ₁ is an amino group which may have at least one substituent S ₃ , a phenylamino group which may have a substituent, and a phenylazo group which may have a substituent. , A naphthotriazole group which may have a substituent or a benzoylamino group which may have a substituent, and the substituent S3 ₍ independently if there is more than one) further has a substituent. It may be selected from the group consisting of an alkyl group of C1 to 4, an alkoxy group of C1 to 4, a sulfo group, an amino group, an alkylamino group of C1 to 4, a hydroxy group, a carboxy group, and a carboxyethylamino group.)

The "amino group which may have a substituent" which Rb ₁ to Rb ₆ may have is preferably an unsubstituted amino group or a substituent (C1-4 alkyl group, acetyl group) of 1 or 2 It is an amino group having one.

The amino group which may have the substituent S ₃ preferably has an unsubstituted amino group and a substituent (hydroxy group, methoxy group, ethoxy group, amino group, carboxy group, sulfo group, phenyl group). It is also a good amino group having one or two alkyl groups of C1 to C4, more preferably an amino group having one or two hydrogen atoms and a methyl group. The phenylamino group which may have a substituent is preferably one selected from the group consisting of a hydrogen atom, a lower alkyl group, a lower alkoxy group, a sulfo group, a carboxy group, an amino group, and a lower alkylamino group. Or a phenylamino group having two substituents, more preferably one or two substituents selected from the group consisting of a hydrogen atom, a methyl group, a methoxy group, a sulfo group, a carboxy group and an amino group. It is a phenylamino group that has. The phenylazo group which may have a substituent is preferably selected from the group consisting of a hydrogen atom, a hydroxy group, an alkyl group of C1 to 4, an alkoxy group of C1 to 4, an amino group, a hydroxy group and a carboxyethylamino group. It is a phenylazo group having 1 to 3 to be treated. The benzoylamino group which may have a substituent is preferably a benzoylamino group having one substituent selected from the group consisting of a hydrogen atom, a hydroxy group, an amino group and a carboxyethylamino group. The naphthotriazole group which may have a substituent is unsubstituted or preferably has one or two substituents selected from the group consisting of a sulfo group, an amino group and a carboxy group. More preferably, it has one or two sulfo groups as substituents.

The substitution position of the substituent which the phenylamino group, the phenylazo group and the benzoylamino group may have is not particularly limited, but one of the substituents is for each of the amino group, the azo group or the amide group. It is preferably at the p-position. The substitution position of Xb ₁ is preferably 6-position or 7-position, and more preferably 6-position, when the position of the hydroxy group of the substituted naphthyl group is 1-position.

When the azo compound represented by the above formula (3) is an azo compound represented by the following formula (6), a polarizing element having a high degree of polarization can be further improved in transmittance at a parallel position of 550 nm to 700 nm. Can be provided. It is more preferably an azo compound represented by the formula (7), further preferably an azo compound represented by the formula (8), still more preferably an azo compound represented by the formula (9), and particularly. It is preferably an azo compound represented by the formula (10). In the formulas (3) and (6) to (10), when Xb ₁ is an amino group which may have at least one substituent S ₃ , the Ra ₁ , Ra ₂ , Ab ₁ or Ab ₂ is described above. It is more preferable that the amino group may have at least one substituent different from the above.

(In the above formula (6), Ra ₁ , Ra ₂ , Ab ₁ , Ab ₂ , Rb ₁ to Rb ₆ , h, and Xb ₁ have the same meanings as those in the formula (3).)

(In the formula (7), Ra ₁ , Ra ₂ , Ab ₁ , Ab ₂ , Rb ₁ to Rb ₆ , h, and Xb ₁ have the same meanings as those in the formula (3).)

(In the formula (8), Ra ₁ , Ab ₁ , Rb ₁ to Rb ₆ , h, and Xb ₁ have the same meanings as those in the formula (3).)

(In the formula (9), Ra ₁ , Ab ₁ , Rb ₁ to Rb ₆ , h, and Xb ₁ have the same meanings as those in the formula (3).)

(In the formula (10), Ab ₁ , Rb ₁ to Rb ₆ , h, and Xb ₁ have the same meanings as those in the formula (3).)

The azo compound represented by the above formula (3) can be easily produced by performing known diazotization and coupling according to the usual method for producing an azo dye as described in Non-Patent Document 1. The synthesis method will be illustrated by taking the case of the azo compound represented by the formula (6) and h = 0 as an example.

First, the amines represented by the formula (A) are diazotized by a known method as described in Non-Patent Document 1, primaryly coupled with the anilines of the following formula (B), and represented by the following formula (C). To obtain a monoazoamino compound.

(In formulas (A) to (C), Ra ₁ , Ra ₂ , Ab ₁ , Ab ₂ , Rb ₁ , and Rb ₂ have the same meanings as those in formula (3), respectively.)

Next, this monoazoamino compound (C) is diazotized by a known method as described in Non-Patent Document 1, secondaryly coupled with the anilines of the following formula (D), and represented by the following formula (E). Obtain a disazoamino compound.

(In the formula (D) and the formula (E), Ra ₁ , Ra ₂ , Ab ₁ , Ab ₂ , Rb ₁ to Rb ₄ have the same meanings as those in the formula (3), respectively.)

The azo compound of the formula (3) can be obtained by diazotizing the formula (E) by a known method as described in Non-Patent Document 1 and coupling it with the naphthols represented by the following formula (F).

(In the formula (F), Xb ₁ has the same meaning as in the formula (3), respectively.)

In the above reaction, the diazotization step is carried out by the normal method of mixing a mineral acid aqueous solution such as hydrochloric acid or sulfuric acid of the diazo component or a nitrite such as sodium nitrite with a turbid solution, or a neutral or weak alkaline diazo component. This is done by the reverse method of adding nitrite to the aqueous solution and mixing it with mineral acid. The temperature of diazotization is preferably −10 to 40 ° C. The coupling step with anilines is carried out by mixing an acidic aqueous solution such as hydrochloric acid or acetic acid with each of the above diazo solutions at a temperature of −10 to 40 ° C. and acidic conditions of pH 2 to 7.

The monoazo compound and disazo compound obtained by coupling can be taken out as they are, or they can be precipitated by acidation or salting out and filtered out, or they can proceed to the next step as a solution or a turbid solution. If the monoazo compound or disazo compound obtained by coupling is a sparingly soluble and turbid liquid, it can be filtered and used as a press cake in the next coupling step.

The coupling reaction between the diazodized diazo compound and the naphthols represented by the formula (F) is carried out at a temperature of -10 to 40 ° C. under neutral to alkaline conditions of pH 7 to 10. After completion of the reaction, it is precipitated by salting out, filtered and taken out. If purification is required, salting out may be repeated or precipitated from water using an organic solvent. Examples of the organic solvent used for purification include water-soluble organic solvents such as alcohols such as methanol and ethanol, and ketones such as acetone.

The starting material for synthesizing the azo compound represented by the formula (3) is a naphthylamine compound corresponding to the substituted naphthyl group represented by the formula (A). Examples of the naphthylamines of the formula (A) include 2-amino-1-hydroxy-naphthalene-6-sulfonic acid, 3-amino-1-hydroxy-naphthalen-6-sulfonic acid, and 2-amino-1-hydroxy-naphthalene-. 3,6-disulfonic acid, 2-amino-8-hydroxy-naphthalen-6-sulfonic acid, 3-amino-8-hydroxy-naphthalen-6-sulfonic acid, 2-amino-8-hydroxy-naphthalene-3,6 -Disulfonic acid, 2-amino-1,8-dihydroxy-naphthalen-6-sulfonic acid, 3-amino-1,8-dihydroxy-naphthalen-6-sulfonic acid, 2-amino-1,8-dihydroxy-naphthalen- 2,6-disulfonic acid 2-amino-1,8-dihydroxy-naphthalene-3-sulfonic acid, 2-amino-1,8-dihydroxy-naphthalene-3,6-disulfonic acid, 2-amino-1-methoxy- 8-Hydroxy-naphthalen-6-sulfonic acid, 3-amino-1-methoxy-8-hydroxy-naphthalene-6-sulfonic acid, 2-amino-1-methoxy-8-hydroxy-naphthalene-3-sulfonic acid, 2 -Amino-1-methoxy-8-hydroxy-naphthalene-3,6-disulfonic acid,
2-Amino-1-hydroxy-8-methoxy-naphthalen-6-sulfonic acid, 3-amino-1-hydroxy-8-methoxy-naphthalen-6-sulfonic acid, 2-amino-1-hydroxy-8-methoxy- Naphthalene-3-sulfonic acid, 3-amino-1-hydroxy-8-methoxy-naphthalen-6-sulfonic acid, 2-amino-1-hydroxy-8-methoxy-naphthalene-3,6-disulfonic acid, 2-amino -1-Hydroxy-8- (3-sulfopropoxy) -naphthalen-3-sulfonic acid, 2-amino-1-hydroxy-8- (4-sulfobutoxy) -naphthalen-3-sulfonic acid, 2-amino-1 -(3-Sulfopropoxy) -8-hydroxy-naphthalen-3-sulfonic acid, 2-amino-1- (4-sulfobutoxy) -8-hydroxy-naphthalene-3-sulfonic acid, 2-amino-1-hydroxy -8- (3-sulfopropoxy) -naphthalen-6-sulfonic acid, 2-amino-1-hydroxy-8- (4-sulfobutoxy) -naphthalen-6-sulfonic acid, 2-amino-1- (3-amino-1-) Sulfopropoxy) -8-hydroxy-naphthalen-3,6-disulfonic acid, 2-amino-1- (4-sulfobutoxy) -8-hydroxy-naphthalene-3,6-disulfonic acid, 2-amino-1,8 -Dihydroxy-naphthalene-6-aminomethyl-3-disulfonic acid and the like are mentioned as preferable, and more preferably 2-amino-1,8-dihydroxy-naphthalene-6-sulfonic acid, 2-amino-1,8- Dihydroxy-naphthalen-3-sulfonic acid, 2-amino-1,8-dihydroxy-naphthalen-3,6-disulfonic acid, 2-amino-1-methoxy-8-hydroxy-naphthalen-6-sulfonic acid, 2-amino -1-methoxy-8-hydroxy-naphthalene-3,6-disulfonic acid, 2-amino-1-hydroxy-8-methoxy-naphthalen-6-sulfonic acid, 2-amino-1-hydroxy-8-methoxy-naphthalene -3-Sulfonic acid, 2-amino-1-hydroxy-8-methoxy-naphthalene-3,6-disulfonic acid, 2-amino-1-hydroxy-8- (3-sulfopropoxy) -naphthalene-3-sulfonic acid , 2-Amino-1- (3-sulfopropoxy) -8-hydroxy-naphthalene-3,6-disulfonic acid, but is not limited thereto.

Anilines having a substituent (Rb ₁ to Rb ₆ ) which is a primary / secondary coupling component when h is 0 or a primary to tertiary coupling component when h is 1 include aniline and 2 -Methylaniline, 2-ethylaniline, 2-propylaniline, 2-butylaniline, 3-methylaniline, 3-ethylaniline, 3-propylaniline, 3-butylaniline, 2,5-dimethylaniline, 2,5- Diethylaniline, 2-methoxyaniline, 2-ethoxyaniline, 2-propoxyaniline, 2-butoxyaniline, 3-methoxyaniline, 3-ethoxyaniline, 3-propoxyaniline, 3-butoxyaniline, 2-methoxy-5-methyl Aniline, 2,5-dimethoxyaniline, 3,5-dimethylaniline, 2,6-dimethylaniline, 3,5-dimethoxyaniline, 3- (2-amino-4-methylphenoxy) propan-1-sulfonic acid, 3 -(2-Aminophenoxy) Propane-1-sulfonic acid, 4- (2-amino-4-methylphenoxy) butane-1-sulfonic acid, 4- (2-Aminophenoxy) butane-1-sulfonic acid, 2- (2-Amino-4-methylphenoxy) ethane-1-sulfonic acid, 2- (2-aminophenoxy) ethane-1-sulfonic acid, 3- (3-amino-4-methylphenoxy) propan-1-sulfonic acid , 3- (3-Aminophenoxy) Propane-1-sulfonic acid, 4- (3-Amino-4-methylphenoxy) butane-1-sulfonic acid, 4- (3-Aminophenoxy) butane-1-sulfonic acid, 2- (3-Amino-4-methylphenoxy) ethane-1-sulfonic acid, 2- (3-aminophenoxy) ethane-1-sulfonic acid, 3- (2-amino-4-methoxyphenoxy) propane-1- Sulphonic acid, 4- (2-amino-4-methoxyphenoxy) butane-1-sulfonic acid, 2- (2-amino-4-methoxyphenoxy) ethane-1-sulfonic acid, 3- (3-amino-4-) Methoxyphenoxy) Propane-1-sulfonic acid, 4- (3-amino-4-methoxyphenoxy) butane-1-sulfonic acid, 2- (3-amino-4-methoxyphenoxy) ethane-1-sulfonic acid, 3- (2-Amino-4-ethoxyphenoxy) Propane-1-sulfonic acid, 4- (2-amino-4-ethoxyphenoxy) butane-1-sulfonic acid, 2- (2-amino-4-ethoxyphenoxy) ethane- 1-sulfonic acid , 3- (3-Amino-4-ethoxyphenoxy) propan-1-sulfonic acid, 4- (3-amino-4-ethoxyphenoxy) butane-1-sulfonic acid, 2- (3-amino-4-ethoxyphenoxy) ) Etan-1-sulfonic acid and the like can be mentioned, but the present invention is not limited thereto. These aromatic amines may have an amino group protected. Examples of the protecting group include an ω-methanesulfon group.

Examples of naphthols having Xb ₁ which is a tertiary coupling component when h is 0 or a quaternary coupling component when h is 1 include 6-amino-3-sulfonic acid-1-naphthol. 6-Methylamino-3-sulfonic acid-1-naphthol, 6-phenylamino-3-sulfonic acid-1-naphthol, 6- (4-methoxy-phenylamino) -3-sulfonic acid-1-naphthol, 6- Examples thereof include, but are not limited to, benzoylamino-3-sulfonic acid-1-naphthol and 6- (4'-aminobenzoyl) amino-3-sulfonic acid-1-naphthol.

Specific examples of the azo compound represented by the formula (3) are given below. The azo compound is represented in the form of a free acid.

The polarizing element of the present invention is a conventional dye-based polarizing element by combining an azo compound represented by the formula (1) or an azo compound represented by the formula (2) with an azo compound represented by the formula (3). Provided by a polarizing element or a polarizing plate having a higher transmittance than a plate and a high degree of polarization. In addition, while having higher transmittance and higher degree of polarization than conventional polarizing plates, it achieves high-quality paper-like white, commonly known as paper white, when displayed in white, and achromatic black, especially when displayed in black. It is possible to realize a high-quality clear black color and to have a higher contrast than a conventional dye-based polarizing element or dye-based polarizing plate.

The polarizing element of the present invention is further represented by the formula (4) with respect to the azo compound represented by the formula (1) or the azo compound represented by the formula (2) and the azo compound represented by the formula (3). By containing the azo compound or the azo compound represented by the formula (5), a polarizing element or a polarizing plate having a higher transmission rate and a higher degree of polarization can be obtained. In particular, by containing the azo compound represented by the formula (4) or the formula (5) or a salt thereof, the transmittance can be further improved at 400 to 500 nm in the polarizing element, and a high degree of polarization can be obtained, which is preferable.

Next, the azo compound represented by the formula (4) will be described.

(In the above formula (4), Ay ₁₁ is an independent hydrogen atom, a sulfo group, a carboxy group, a hydroxy group, a lower alkyl group, or a lower alkoxy group, and Ry ₁₁ to Ry ₁₄ are independently hydrogen. It is a lower alkoxy group having an atom, a sulfo group, a lower alkyl group, a lower alkoxy group, and a sulfo group, and f represents an integer of 1 to 3).

In the above formula (4), Ay11 is preferably a sulfo group or a carboxy group. Ry11 to Ry14 are preferably a hydrogen atom, a sulfo group, a lower alkyl group and a lower alkoxy group, and more preferably a hydrogen atom, a methyl group and a methoxy group.

Specific examples of the azo compound represented by the formula (4) include, for example, C.I. I. Direct Yellow 4, C.I. I. Direct Yellow 12, C.I. I. Direct Yellow 72, and C.I. I. There are, but are not limited to, Direct Orange 39 and azo compounds having a stilbene structure described in International Publication No. 2007/138980 and the like.

The azo compound represented by the formula (4) or a salt thereof can be synthesized by, for example, the method described in International Publication No. 2007/138980.

Further specific examples of the azo compound represented by the formula (4) are given below. Examples of compounds are expressed in the form of free acid.

Next, the azo compound represented by the formula (5) will be described.

(In the formula (5), Ay ₂₁ and Ay ₂₂ are naphthyl groups which may have a substituent or a phenyl group which may have a substituent, respectively, and are Ry ₂₁ , Ry ₂₂ and Ry ₂₇ . , Ry ₂₈ are independently hydrogen atoms, C1 to 4 alkyl groups, and C1 to 4 alkoxy groups, and Ry ₂₃ to Ry ₂₆ are independently hydrogen atoms, C1 to 4 alkyl groups, and C1. It is an alkoxy group of C1 to 4 having an alkoxy group of 4 and a sulfo group, and s and t independently indicate 0 or 1 respectively.)

The phenyl group having a substituent is preferably a sulfo group, a carboxy group, a lower alkoxy group having a sulfo group, a lower alkyl group, a lower alkoxy group, a halogen group, a nitro group, an amino group, a lower alkyl substituted amino group, and a lower group. Alkyl Substituted Acylamino Group A phenyl group having one or more substituents selected from phenyl groups. When the phenyl group has two or more substituents, at least one of the substituents is a sulfo group, a carboxy group, or a lower alkoxy group having a sulfo group, and the other substituents are a sulfo group, a hydrogen atom, and the like. It is preferably a lower alkyl group, a lower alkoxy group, a lower alkoxy group having a sulfo group, a carboxy group, a chloro group, a bromo group, a nitro group, an amino group, a lower alkyl substituted amino group, or a lower alkyl substituted acylamino group. A sulfo group, a hydrogen atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a carboxy group, a sulfoethoxy group, a sulfopropoxy group, a sulfobutoxy group, a chloro group, a nitro group, or an amino group is more preferable. Particularly preferably, it is a group, a carboxy group, a hydrogen atom, a methyl group, a methoxy group, a sulfoethoxy group, a sulfopropoxy group, or a sulfobutoxy group. The substitution position is not particularly limited, but preferably only the 2-position, only the 4-position, the combination of the 2-position and the 6-position, the combination of the 2-position and the 4-position, and the combination of the 3-position and the 5-position are particularly preferable, and the 2-position is particularly preferable. Only the place, only the 4th place, the combination of the 2nd place and the 4th place, or the combination of the 3rd place and the 5th place. Note that only the 2-position and the 4-position indicate that only the 2-position or the 4-position has one substituent other than a hydrogen atom.

The phenyl group having a substituent is preferably represented by the following formula (11).

In formula (11), at least one of Ry _2a and Ry _2b is a lower alkoxy group having a sulfo group, a carboxyl group, or a sulfo group, and the other is a lower alkoxy group having a hydrogen atom, a sulfo group, a carboxy group, or a sulfo group. A group, a lower alkyl group, a lower alkoxy group, a halogen group, a nitro group, an amino group, a lower alkyl substituted amino group, or a lower alkyl substituted acylamino group. Preferably, one of Ry _2a and Ry _2b is a sulfo group or a carboxy group, and the other is a hydrogen atom, a sulfo group, a carboxy group, a methyl group or a methoxy group.

The naphthyl group which may have a substituent is preferably a naphthyl group which may have one or more substituents selected from a hydroxy group, a lower alkoxy group having a sulfo group and a sulfo group.

The naphthyl group which may have a substituent is preferably a naphthyl group represented by the following formula (12).

In formula (12), Ry _2c is a lower alkoxy group having a hydrogen atom, a hydroxy group, a sulfo group, or a sulfo group. u is an integer of 1 to 3. The position of the sulfo group may be present in any benzene nucleus of the naphthalene ring. Preferably, Ry _2c is a hydrogen atom and u is 2. As the lower alkoxy group having a sulfo group, a linear alkoxy group is preferable, and the substituent of the sulfo group is preferably an alkoxy group terminal. The lower alkoxy group having a sulfo group is more preferably a 3-sulfopropoxy group and a 4-sulfobutoxy group. The position of the substituent of the naphthyl group is not particularly limited, but when described by the number shown in the formula (12), the substitution position of the azo group is the 2-position in the formula (5), and the 5-position when there are two substituents. The 7-position and the 4-position and the 8-position, or the combination of the 6-position and the 8-position are preferable, and when the number of substituents is 3, the 3-position, the 5-position and the 7-position, and the 3-position, the 6-position and the 8-position are preferable.

Ry ₂₁ , Ry ₂₂ , Ry ₂₇ , and Ry ₂₈ are independently hydrogen atoms, lower alkoxy groups, and lower alkyl groups, but are preferably hydrogen atoms, methyl groups, ethyl groups, methoxy groups, and ethoxy groups, respectively.

Ry ₂₃ to Ry ₂₆ are lower alkoxy groups each independently having a hydrogen atom, a lower alkyl group, a lower alkoxy group, and a sulfo group, whereas Ry ₂₃ to Ry ₂₆ are independent, preferably hydrogen atom, a methyl group, respectively. It is an ethyl group, a methoxy group, an ethoxy group, a 3-sulfopropoxy group, or a 4-sulfobutoxy group, and more preferably a hydrogen atom, a methyl group, an ethyl group, a methoxy group, or a 3-sulfopropoxy group. As the positions of Ry ₃ to Ry ₆ , preferably, only the 2nd position, only the 5th position, the combination of the 2nd and 6th positions, the combination of the 2nd and 5th positions, and the combination of the 3rd and 5th positions are preferable, and more preferably. Only the 2nd place, only the 5th place, and the combination of the 2nd place and the 5th place. It should be noted that only the 2-position and the 5-position indicate that only the 2-position or the 5-position has one substituent other than the hydrogen atom.

The azo compound represented by the formula (5) is preferably represented by the following formula (5b).

(In the formula (5b), Ay ₂₁ , Ay ₂₂ , Ry ₂₁ to Ry ₂₈ , s or t have the same meanings as those in the formula (5), respectively.)

The azo compound represented by the above formula (5) or the azo compound represented by the formula (5b) or a salt thereof is diazotized and coupled according to a conventional method for producing an azo dye as described in Non-Patent Document 1. It can be produced by reacting with a uraido agent as described in Patent Documents 4 to 7.

Next, specific examples of the azo compound represented by the formula (5) or the azo compound represented by the formula (5b) are given below. The sulfo group, carboxy group and hydroxy group in the formula are represented in the form of free acid.

The azo compounds represented by the above formulas (1) to (5) may be in the form of a free acid or a salt, but may be a salt of a metal ion or an ammonium ion. Examples of the metal ion include alkali metal ions such as lithium ion, sodium and potassium ion, and alkaline earth metal ions such as calcium ion and magnesium ion. Examples of the ammonium ion include ammonium ion, methylammonium ion, dimethylammonium ion, triethylammonium ion, tetraethylammonium ion, tetra-n-propylammonium ion, tetra-n-butylammonium ion, triethanolammonium ion and the like. .. More specifically, for example, in the case of free acid, sulfonic acid (-SO ₃ H), in the case of sodium ion, sodium sulfonate (-SO ₃ Na), in the case of ammonium ion, ammonium sulfonate (-SO). ₃ NH ₄ ) is represented.

The polarizing element of the present invention includes an azo compound represented by the formula (1), an azo compound represented by the formula (2), and an azo compound represented by the formula (3). It is possible to provide a polarizing element having high transmittance, high contrast, that is, high degree of polarization. Further, by further incorporating the azo compound represented by the formula (4) or the azo compound represented by the formula (5), it is possible to provide a polarizing element having higher transmittance, higher contrast, that is, a higher degree of polarization.

The polarizing element of the present invention has excellent polarization performance such as chromaticity a * value and b * value in a preferable range described later, single transmittance after correction of visual sensitivity, and average transmittance in a specific wavelength band. For example, the transmittance of a single polarizing element at each wavelength can be made constant. Further, it is possible to have a constant transmittance, that is, an achromatic hue even at each wavelength in the parallel position when the absorption axes of the two polarizing elements are parallel. Further, it is possible to have a constant transmittance, that is, an achromatic hue even at each wavelength at the orthogonal position when the absorption axes of the two polarizing elements are orthogonal to each other. From this, the polarizing element of the present invention can not only have high transmittance and high contrast, that is, high degree of polarization, but also have an achromatic hue.

By changing the amount of each of the above azo compounds contained in the substrate in the polarizing element of the present invention, the transmittance and chromaticity can be adjusted to be within the preferable ranges described later. The performance of the polarizing element includes not only the compounding ratio of each azo compound in the polarizing element, but also various factors such as the degree of swelling and stretching ratio of the substrate that adsorbs the azo compound, the dyeing time, the dyeing temperature, the pH at the time of dyeing, and the influence of the salt. It changes depending on various factors. Therefore, the blending ratio of each azo compound can be determined according to the degree of swelling of the substrate, the temperature at the time of dyeing, the time, the pH, the type of salt, the concentration of salt, and the draw ratio.

(Transmittance after luminosity factor correction)
The transmittance after the luminosity factor correction refers to the transmittance corrected to the luminosity factor of the human eye, and can be obtained according to JIS Z 8722: 2009. For the measurement sample (for example, a polarizing element or a polarizing plate), the spectral transmittance of each wavelength is measured every 5 nm or 10 nm in the wavelength range of 380 to 780 nm using a C light source (2 degree field), and JIS Z 8722. : It can be obtained by correcting the visual sensitivity according to 2009. The transmittance after the visual sensitivity correction is the single transmittance (Ys) after the visual sensitivity correction when the measurement sample is measured by itself, and the visual sensitivity when each absorption axis is parallel to each other using two measurement samples. There are the corrected parallel position transmittance (Yp) and the corrected orthogonal position transmittance (Yc) when the absorption axes are orthogonal to each other using two measurement samples.

(Difference in average transmittance between two wavelength bands)
In the polarizing element of the present invention, it is preferable that the difference in average transmittance between specific wavelength bands is a predetermined value or less. The average transmittance means the average value of the transmittance of each wavelength in a specific wavelength band.

The wavelength bands 420 nm to 480 nm, 520 nm to 590 nm, and 600 nm to 640 nm are the main wavelength bands based on the color matching function used in the calculation when showing colors in JIS Z 8781-4: 2013. Specifically, in the XYZ color matching function of JIS Z 8701, which is the basis of JIS Z 8781-4: 2013, x (λ) having a maximum value of 600 nm and y (λ) having a maximum value of 550 nm are set to 455 nm. When the maximum value of z (λ) as the maximum value is 100, each wavelength showing a value of 20 or more is each wavelength band of 420 nm to 480 nm, 520 nm to 590 nm, and 600 nm to 640 nm. Hereinafter, the average transmittance of each wavelength from ○ nm to △ nm is also referred to as “AT _{○ － △} ”.

(Parallel transmittance)
The transmittance obtained by measuring at each wavelength in a state where two polarizing elements are stacked so as to be parallel to each other in the absorption axis direction (when displayed in bright light or when displayed in white) is the "parallel transmission" of each wavelength. Also referred to as "rate (Tp)". Regarding the parallel transmittance of each wavelength of the polarizing element of the present invention, the difference in average transmittance between the two wavelength bands is preferably 2.5% as the absolute value of the difference between AT _420-480 and AT _520-590 . It is less than or equal to, more preferably 1.8% or less, still more preferably 1.5% or less, and particularly preferably 1.0% or less. Further, the difference between AT _520-590 and AT _600-640 is preferably 3.0% or less, more preferably 2.0% or less, still more preferably 1.5% or less as an absolute value. Particularly preferably, it is 1.0% or less. Such a polarizing element can display a high-quality paper-like white color in a parallel position.

(Orthogonal transmittance)
The transmittance obtained by measuring at each wavelength in a state where two polarizing elements are stacked so that the absorption axis directions are orthogonal to each other (when displayed in black or when displayed in dark) is the "orthogonal transmission" of each wavelength. It is called "rate (Tc)". Regarding the orthogonal transmittance of each wavelength of the polarizing element of the present invention, the difference in average transmittance between the two wavelength bands is such that the difference between AT _420-480 and AT _520-590 is 1.0% or less as an absolute value. It is preferable that the difference between AT _520-590 and AT _600-640 is 1.0% or less as an absolute value. Such a polarizing element can display an achromatic black color at an orthogonal position. Further, the difference between AT _420-480 and AT _520-590 as an absolute value is preferably 0.6% or less, more preferably 0.3% or less, still more preferably 0.1% or less. .. The difference between AT _520-590 and AT _600-640 is preferably 1.0% or less, more preferably 0.6% or less, and further preferably 0.3% or less as an absolute value. , Particularly preferably 0.1%.

Further, the average transmittance of each wavelength in the wavelength band of 380 nm to 420 nm, 480 nm to 520 nm, and 640 nm to 780 nm, which is different from the above wavelength band, the parallel position transmittance, and the orthogonal position transmittance is also to some extent. It is preferable that it is adjusted. Regarding the single transmittance of each wavelength of the polarizing element of the present invention, the difference in average transmittance between the two wavelength bands is preferably that the difference between AT _{380-420 and AT 420-480} _is 15% or less, and AT. The difference between _{480-520 and AT 420-480} _is more preferably 15% or less, and the difference between AT _{480-520 and AT 520-590} _is preferably 15% or less, with AT _640-780 . It is more preferable that the difference from AT _600-640 is 20% or less.

(Value of single transmittance after correction of visual sensitivity)
The polarizing element of the present invention preferably has a simple substance transmittance (Ys) of 35% to 65% after correction of visual sensitivity. The single transmittance after the visual sensitivity correction is the transmittance corrected to the visual sensitivity according to JIS Z 8722: 2009 for one measurement sample (for example, a polarizing element or a polarizing plate). As for the performance of the polarizing plate, if the single transmittance after the visual sensitivity correction is 35% to 65%, the brightness can be expressed without discomfort even when used in a display device. The higher the transmittance, the lower the degree of polarization. Therefore, from the viewpoint of the balance with the degree of polarization, the single transmittance after the visual sensitivity correction is preferably 36% to 55%, more preferably 37% to 37%. It is 50%, more preferably 38% to 48%, and particularly preferably 39% to 45%. If the single transmittance after luminosity factor correction exceeds 65%, the degree of polarization may decrease, but if the bright transmittance of the polarizing element or specific polarization performance or contrast is required, the single transmittance after luminosity factor correction is required. The rate may exceed 65%.

(Average transmittance in a specific wavelength band)
In the polarizing element of the present invention, AT _520-590 is preferably 25% to 50% with respect to the average transmittance of the parallel transmittance (Tp) of each wavelength. When such a polarizing element is provided in a display device, it can be a bright and clear display device with high brightness. The transmittance of the wavelength band from 520 nm to 590 nm is one of the main wavelength bands based on the color matching function used in the calculation when showing a color in JIS Z 8781-4: 2013. In particular, each wavelength band from 520 nm to 590 nm is the wavelength band having the highest visual sensitivity based on the color matching function, and it is said that the transmittance in this range is close to the transmittance that can be visually confirmed. Therefore, it is very important to adjust the transmittance in the wavelength band of 520 nm to 590 nm. The average transmittance AT _520-590 of the parallel transmittance of each wavelength is more preferably 28% to 45%, still more preferably 30% to 40%. Further, the degree of polarization of the polarizing element at this time is preferably 80% to 100%, more preferably 90% to 100%, still more preferably 97% to 100%, still more preferably 99% or more. It is particularly preferably 99.5% or more. The higher the degree of polarization is preferable, but in the relationship between the degree of polarization and the transmittance, the transmittance and the degree of polarization should be adjusted to be suitable depending on whether the brightness is emphasized or the degree of polarization (or contrast) is emphasized. Can be done.

(Saturation a * value and b * value)
The chromaticity a * value and b * value are values obtained at the time of measuring the transmittance of natural light according to JIS Z 8781-4: 2013. The object color display method defined in JIS Z 8781-4: 2013 corresponds to the object color display method defined by the International Commission on Illumination (abbreviation: CIE). The measurement of the chromaticity a * value and the b * value is performed by irradiating the measurement sample (for example, a polarizing element or a polarizing plate) with natural light. In the following, the chromaticity a * value and b * value required for one measurement sample are shown as a * -s and b * -s so that the absorption axis directions of the two measurement samples are parallel to each other. The chromaticity a * value and b * value obtained for the arranged state (when displayed in white) are shown as a * -p and b * -p, and the two measurement samples are arranged so that their absorption axis directions are orthogonal to each other. The chromaticity a * value and b * value obtained for the state (when displayed in black) are shown as a * -c and b * -c.

In the polarizing element of the present invention, the absolute values of chromaticity a * -s and b * -s required for one measurement sample are 1.0 or less (-1.0 ≤ a * -s ≤ 1.0,-, respectively. 1.0 ≦ b * −s ≦ 1.0) is preferable. Further, a * -p is preferably -2.0 to 2.0 (-2.0 ≤ a * -p ≤ 2.0), and b * -p is -2.0 to 3.0 (-2.0 ≤ a * -p ≤ 2.0). -2.0≤b * -p≤3.0) is preferable. Such a polarizing element is a neutral color by itself, and can display high-quality white when displayed in white. More preferably, the absolute values of a * -p and b * -p in a state where two measurement samples are arranged so as to be parallel to each other in the absorption axis direction (when displayed in white) are independently 2.0 or less. It is good, more preferably 1.5 or less independently, and particularly preferably 1.0 or less independently. Further, the absolute values of the chromaticities a * -c and b * -c in the state where the two measurement samples are arranged so that their absorption axis directions are orthogonal to each other (when displayed in black) are 2.0 or less (-2. 0 ≤ a * -c ≤ 2.0, -2.0 ≤ b * -c ≤ 2.0), each of which is 1.0 or less (-1.0 ≤ a * -c ≤ 1.0). , -1.0 ≦ b * -c ≦ 1.0) is more preferable. Such a polarizing element can display achromatic black when displaying black. Even if there is a difference of 0.5 between the absolute values of the chromaticity a * value and the b * value, humans can perceive the difference in color, and the difference in color may be felt greatly depending on the person. Therefore, it is very important to control these values in the polarizing element. In particular, when the absolute values of a * -p, b * -p, a * -c, and b * -c are 1.0 or less, the white color when displayed in white and the black color when displayed in black are used. , A good polarizing plate with almost no other colors can be obtained. It is possible to realize achromatic color in the parallel position, that is, white color like high-quality paper, and to realize a clear black color with a high-quality achromatic color in the orthogonal position. However, the influence of the hue giving the black color of the display device is not limited to this, and in the absence of light (dark) in the first place, the display device looks black even if it has a hue. Therefore, when the degree of polarization is high, that is, when the orthogonal position transmittance is low, the polarizing element can give black even if the absolute values of a * -c and b * -c are not 2.0 or less. As a result of our examination, when the orthogonal transmittance at each wavelength of the wavelength band 420 nm to 480 nm, 520 nm to 590 nm, and 600 nm to 640 nm is 1% or less, or the degree of polarization is about 97% or more, a * -c. And it was found that black can be given visually regardless of the absolute value of b * -c. When the orthogonal transmittance of each wavelength in the wavelength band of 420 nm to 480 nm, 520 nm to 590 nm, and 600 nm to 640 nm is 0.6% or less, or the degree of polarization is 98% or more, more black is visually imparted. It is more preferable, and it is particularly preferable when the orthogonal position transmittance of each wavelength is 0.3% or less or the degree of polarization is 99% or more.

From the above, in order to give an achromatic black color in a state where two polarizing elements are overlapped and arranged so that the absorption axis directions are orthogonal to each other (when displaying black or when displaying dark). It is preferable to satisfy any of the following conditions 1) to 3).
1) Regarding the orthogonal transmittance (Tc) of each wavelength, the difference between AT _420-480 and AT _520-590 is 1.0% or less as an absolute value, and AT _520-590 and AT _600-640. When the difference from the absolute value is 1.0% or less 2) When the absolute values of chromaticity a * -c and b * -c are 2.0 or less, respectively 3) Wavelength band 420 nm to 480 nm, 520 nm to When the orthogonal transmittance (Tc) of each wavelength at 590 nm and 600 nm to 640 nm is 1% or less, or the degree of polarization is about 97% or more.

The polarizing element of the present invention has high contrast and high transmittance, while having achromaticity and high degree of polarization by itself. Further, the polarizing element of the present invention can express high-quality paper-like white (paper white) when displayed in white, and express achromatic black, particularly high-quality clear black when displayed in black. Can be done. The polarizing element of the present invention is also highly durable, particularly resistant to high temperatures and high humidity.

The polarizing element of the present invention absorbs less light having a wavelength of 700 nm or more than the iodine-based polarizing plate and the polarizing element described in Patent Document 3, and therefore generates less heat even when irradiated with light such as sunlight. There are advantages. For example, when the liquid crystal display is used outdoors, sunlight is applied to the liquid crystal display, and as a result, the polarizing element is also irradiated. Sunlight also includes light having a wavelength of 700 nm or more, and light in the near infrared region has a heat generation effect. Since the polarizing element of the present invention absorbs very little near-infrared rays, it is excellent in that it generates less heat even when exposed to sunlight outdoors and therefore has less deterioration.

<Method of manufacturing a polarizing element>
Hereinafter, a specific method for producing a polarizing element will be described by taking as an example a case where an azo compound is adsorbed on a base material made of a polyvinyl alcohol-based resin. The method for manufacturing the polarizing element of the present invention is not limited to the following manufacturing method.

(Preparation of original film)
The raw film can be produced by forming a polyvinyl alcohol-based resin. The polyvinyl alcohol-based resin is not particularly limited, and a commercially available one may be used, or one synthesized by a known method may be used. The polyvinyl alcohol-based resin can be obtained, for example, by saponifying the polyvinyl acetate-based resin. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and a copolymer of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids and the like. The degree of saponification of the polyvinyl alcohol-based resin is usually preferably about 85 to 100 mol%, more preferably 95 mol% or more. The polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can also be used. The degree of polymerization of the polyvinyl alcohol-based resin means the viscosity average degree of polymerization, and can be obtained by a method well known in the art, and is usually preferably about 1,000 to 10,000, and the degree of polymerization is 1,500 to 1,500. About 6,000 is more preferable.

The method for forming the film of the polyvinyl alcohol-based resin is not particularly limited, and the film can be formed by a known method. In this case, the polyvinyl alcohol-based resin film may contain glycerin, ethylene glycol, propylene glycol, low molecular weight polyethylene glycol, or the like as a plasticizer. The amount of the plasticizer is preferably 5 to 20% by mass, more preferably 8 to 15% by mass in the total amount of the film. The film thickness of the raw film is not particularly limited, but is preferably about 5 μm to 150 μm, more preferably about 10 μm to 100 μm, for example.

(Swelling process)
The raw film obtained as described above is subjected to a swelling treatment. The swelling treatment is preferably carried out by immersing the raw film in a solution at 20 to 50 ° C. for 30 seconds to 10 minutes. The solution is preferably water. The draw ratio is preferably adjusted to 1.00 to 1.50 times, more preferably 1.10 to 1.35 times. When the time for manufacturing the polarizing element is shortened, the swelling treatment can be omitted because the raw film swells even during the dyeing treatment described later.

(Dyeing process)
In the dyeing step, the resin film obtained by swelling the raw film is adsorbed and impregnated with the azo compound. When the swelling step is omitted, the swelling treatment of the raw film can be performed at the same time in the dyeing step. Since the process of adsorbing and impregnating the azo compound is a step of coloring the resin film, it is a dyeing step.

As the azo compound used in the dyeing step, an azo compound represented by the formula (1) or a mixture of the azo compound represented by the formula (2) and the azo compound represented by the formula (3) is used. Arbitrarily, the azo compound represented by the formula (4) or the azo compound represented by the formula (5) can be further used. Further, an azo compound which is a dichroic dye exemplified in Non-Patent Document 2 and the like can be optionally used to the extent that the performance of the polarizing element of the present invention is not impaired. In addition to using these azo compounds in the form of free acids, salts of the compounds may be used. Such salts are alkali metal salts such as, for example, lithium salts, sodium salts, and potassium salts, or organic salts such as ammonium salts and alkylamine salts, preferably sodium salts.

The dyeing step is not particularly limited as long as it is a method of adsorbing and impregnating the dye on the resin film, but is preferably performed by immersing the resin film in the dyeing solution, and is performed by applying the dyeing solution to the resin film. You can also do it. Each azo compound in the dyeing solution can be adjusted, for example, in the range of 0.001 to 10% by mass.

The solution temperature in this step is preferably 5 to 60 ° C, more preferably 20 to 50 ° C, and particularly preferably 35 to 50 ° C. The time of immersion in the solution can be appropriately adjusted, but is preferably adjusted to 30 seconds to 20 minutes, more preferably 1 to 10 minutes.

The dyeing solution may further contain a dyeing aid, if necessary, in addition to the azo compound. Examples of the dyeing aid include sodium carbonate, sodium hydrogencarbonate, sodium chloride, sodium sulfate, anhydrous sodium sulfate, sodium tripolyphosphate and the like. The content of the dyeing aid can be adjusted at an arbitrary concentration depending on the time and temperature depending on the dyeability of the dye, but the content of each is preferably 0.001 to 5% by mass, preferably 0.01 to 0.01 in the dyeing solution. 2% by mass is more preferable.

(Washing step 1)
After the dyeing step and before entering the next step, a washing step (hereinafter, also referred to as “cleaning step 1”) can be performed. The dyeing and cleaning step 1 is a step of cleaning the dyeing solution adhering to the surface of the resin film in the dyeing step. By performing the washing step 1, it is possible to suppress the transfer of the dye into the liquid to be treated next. In the cleaning step 1, water is generally used as the cleaning liquid. The cleaning method is preferably immersed in a cleaning liquid, but cleaning can also be performed by applying the cleaning liquid to a resin film. The washing time is not particularly limited, but is preferably 1 to 300 seconds, more preferably 1 to 60 seconds. The temperature of the cleaning liquid in the cleaning step 1 needs to be a temperature at which the material constituting the resin film (for example, a hydrophilic polymer, here, a polyvinyl alcohol-based resin) does not dissolve. Generally, it is washed at 5 to 40 ° C. However, even if there is no cleaning step 1, there is no problem in performance, so the cleaning step can be omitted.

(Step of containing a cross-linking agent and / or a water resistant agent)
After the dyeing step or the washing step 1, a step of containing a cross-linking agent and / or a water resistant agent can be performed. As a method of incorporating a cross-linking agent and / or a water resistant agent in the resin film, it is preferable to immerse the resin film in the treatment solution, but the treatment solution may be applied or coated on the resin film. The treatment solution contains at least one cross-linking agent and / or water resistant agent and a solvent. The temperature of the treatment solution in this step is preferably 5 to 70 ° C, more preferably 5 to 50 ° C. The treatment time in this step is preferably 30 seconds to 6 minutes, more preferably 1 to 5 minutes.

Examples of the cross-linking agent include a boron compound such as boric acid, boric acid or ammonium borate, a polyvalent aldehyde such as glyoxal or glutaraldehyde, a polyvalent isocyanate compound such as biuret type, isocyanurate type or block type, and titanium oxy. Titanium-based compounds such as sulfate can be used, but ethylene glycol glycidyl ether, polyamide epichlorohydrin and the like can also be used. Examples of the water resistant agent include succinic acid peroxide, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, ammonium chloride, magnesium chloride and the like, but boric acid is preferable. Used. The solvent for the cross-linking agent and / or the water resistant agent is preferably, but not limited to, water. The concentration of the cross-linking agent and / or the water-resistant agent can be appropriately determined by those skilled in the art depending on the type thereof, but when boric acid is taken as an example, the concentration in the treatment solution is 0.1 to 6.0 mass by mass. % Is preferable, and 1.0 to 4.0% by mass is more preferable. However, it is not essential to contain a crosslinking agent and / or a water resistant agent, and if the time is to be shortened and the crosslinking treatment or the water resistance treatment is unnecessary, this treatment step may be omitted. ..

(Stretching process)
After performing the dyeing step, the washing step 1, or the step of containing the cross-linking agent and / or the water resistant agent, the stretching step is performed. The stretching step is performed by stretching the resin film uniaxially. The stretching method may be either a wet stretching method or a dry stretching method. The draw ratio is preferably 3 times or more, more preferably 4 to 8 times, and particularly preferably 5 to 7 times.

In the case of the wet stretching method, it is preferable to stretch the resin film in water, a water-soluble organic solvent, or a mixed solution thereof. It is preferable to carry out the stretching treatment while immersing in a solution containing at least one cross-linking agent and / or a water resistant agent. As the cross-linking agent and the water-resistant agent, the same ones as described above can be used for the step of containing the cross-linking agent and / or the water-resistant agent. The concentration of the cross-linking agent and / or the water resistant agent in the solution in the stretching step is preferably, for example, 0.5 to 15% by mass, more preferably 2.0 to 8.0% by mass. The stretching temperature is preferably 40 to 60 ° C, more preferably 45 to 58 ° C. The stretching time is usually 30 seconds to 20 minutes, but more preferably 2 to 5 minutes. The wet stretching step can be performed in one step, but it can also be performed by multi-step stretching in two or more steps.

In the case of the dry stretching method, when the stretching heating medium is an air medium, it is preferable to stretch the resin film at a temperature of the air medium from room temperature to 180 ° C. Moreover, it is preferable that the humidity is in an atmosphere of 20 to 95% RH. Examples of the heating method include an inter-roll zone stretching method, a roll heating stretching method, a pressure stretching method, an infrared heating stretching method, and the like, but the stretching method is not limited. The stretching step can be carried out in one step, but can also be carried out by multi-step stretching in two or more steps.

(Washing step 2)
After the stretching step, the cross-linking agent and / or the water resistant agent may precipitate on the surface of the resin film, or foreign matter may adhere to the surface of the resin film. Can be referred to). The washing time is preferably 1 second to 5 minutes. As a cleaning method, it is preferable to immerse the resin film in the cleaning liquid, but the solution can also be applied to the resin film or washed by coating. Water is preferable as the cleaning liquid. The cleaning treatment can be performed in one stage, or the multi-stage treatment in two or more stages can be performed. The solution temperature in the washing step is not particularly limited, but is usually 5 to 50 ° C, preferably 10 to 40 ° C.

The treatment liquid or its solvent used in the treatment steps up to this point includes water, for example, dimethylsulfoxide, N-methylpyrrolidone, methanol, ethanol, propanol, isopropyl alcohol, glycerin, ethylene glycol, propylene glycol, diethylene glycol, and triethylene. Examples thereof include alcohols such as glycol, tetraethylene glycol or trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine, but the present invention is not limited thereto. The treatment liquid or its solvent is most preferably water. Moreover, these treatment liquids or the solvent thereof may be used individually by 1 type, but a mixture of 2 or more types may also be used.

(Drying process)
After the stretching step or the washing step 2, a drying step of the resin film is performed. The drying treatment can be carried out by natural drying, but in order to further improve the drying efficiency, it can be carried out by compression with a roll, air knife, removal of moisture on the surface by a water absorbing roll, etc., and / or by blowing air drying. You can also do it. The drying treatment temperature is preferably 20 to 100 ° C, more preferably 60 to 100 ° C. The drying treatment time is usually 30 seconds to 20 minutes, but is preferably 5 to 10 minutes.

In the method for producing a polarizing element, the degree of swelling of the base material in the swelling step, the compounding ratio of each azo compound in the dyeing step, the temperature of the dyeing solution, pH, the type and concentration of salts such as sodium chloride, glazed glass, sodium tripolyphosphate, etc. And the dyeing time and the stretching ratio in the stretching step are preferably adjusted so that the polarizing element of the present invention satisfies at least one of the following conditions (i) to (vi), (vii) and (viii). It is more preferable to make adjustments so as to further satisfy the above conditions.
(I) Regarding the parallel transmittance (Tp), the difference between AT _420-480 and AT _520-590 is 2.5 or less as an absolute value, and the difference between AT _520-590 and AT _600-640 is an absolute value. As 3.0.
(Ii) Regarding the orthogonal position transmittance (Tc), the difference between AT _420-480 and AT _520-590 is 1.0 or less as an absolute value, and the difference between AT _520-590 and AT _600-640 is an absolute value. Is 1.0 or less.
(Iii) The simple substance transmittance (Ys) after the visual sensitivity correction is 35 to 65%.
(Iv) The absolute values of the chromaticity a * value and the b * value of the polarizing element alone are both 1.0 or less.
(V) In the chromaticity a * value and b * value in the parallel position, the a * value is −2.0 to 2.0 and the b * value is −2.0 to 3.0.
(Vi) The absolute values of the chromaticity a * value and the b * value at the orthogonal position are both 2.0 or less.
(Vii) AT _520-590 is 25 to 35% with respect to the parallel transmittance (Tp).
(Viii) The difference between AT _380-420 and AT _420-480 is 15% or less in the simple substance transmittance (Ts) or the orthogonal position transmittance (Tc), and the difference between AT _480-520 and AT _420-480 . Is 15% or less, the difference between AT _{480-520 and AT 520-590} _is 15% or less, and / or the difference between AT _640-780 and AT _600-640 is 20% or less.

By the above method, the azo compound represented by the formula (1) or the combination of the azo compound represented by the formula (2) and the azo compound represented by the formula (3), or optionally represented by the formula (4). It is possible to manufacture a polarizing element containing the azo compound to be used or a combination of the azo compounds represented by the formula (5).

<Polarizer>
The polarizing plate of the present invention includes a polarizing element and a transparent protective layer provided on one side or both sides of the polarizing element. The transparent protective layer is provided for the purpose of improving the water resistance and handleability of the polarizing element.

The transparent protective layer is a protective film formed by using a transparent substance. The protective film is a film having a layered shape capable of maintaining the shape of the polarizing element, and plastic or the like having excellent transparency, mechanical strength, thermal stability, moisture shielding property, etc. is preferable. Equivalent functions may be provided by forming a layer equivalent to this. Examples of plastics constituting the protective film include thermoplastic resins such as polyester resins, acetate resins, polyether sulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins and acrylic resins. Examples thereof include a film obtained from a thermosetting resin such as acrylic, urethane, acrylic urethane, epoxy and silicone, or an ultraviolet curable resin. Among these, examples of the polyolefin-based resin include an amorphous polyolefin-based resin having a polymerization unit of a cyclic polyolefin such as a norbornene-based monomer or a polycyclic norbornene-based monomer. In general, it is preferable to select a protective film that does not impair the performance of the polarizing element after laminating the protective film, and as such a protective film, triacetyl cellulose (TAC) made of a cellulose acetate resin and norbornene are particularly preferable. .. Further, the protective film may be subjected to a hard coat treatment, an antireflection treatment, a sticking prevention / diffusion treatment, an antiglare treatment, or the like, as long as the effect of the present invention is not impaired. The thickness of the transparent protective layer is preferably 10 to 200 μm.

It is preferable that the polarizing plate of the present invention further includes an adhesive layer for adhering the transparent protective layer to the polarizing element between the transparent protective layer and the polarizing element. The adhesive constituting the adhesive layer is not particularly limited. For example, a polyvinyl alcohol-based adhesive, a urethane emulsion-based adhesive, an acrylic-based adhesive, a polyester-isocyanate-based adhesive, and the like can be mentioned, and a polyvinyl alcohol-based adhesive is preferable. Examples of the polyvinyl alcohol-based adhesive include, but are not limited to, Gosenol NH-26 (manufactured by Nippon Synthetic Co., Ltd.) and Exevar RS-2117 (manufactured by Kuraray Co., Ltd.). A cross-linking agent and / or a water resistant agent can be added to the adhesive. As the polyvinyl alcohol-based adhesive, it is preferable to use a maleic anhydride-isobutylene copolymer, and if necessary, an adhesive mixed with a cross-linking agent can be used. Examples of the maleic anhydride-isobutylene copolymer include Isovan # 18 (manufactured by Kuraray), Isoban # 04 (manufactured by Kuraray), Ammonia-modified Isovan # 104 (manufactured by Kuraray), and Ammonia-modified Isovan # 110 (manufactured by Kuraray). ), Imidized Isovan # 304 (manufactured by Kuraray Co., Ltd.), Imidized Isovan # 310 (manufactured by Kuraray Co., Ltd.) and the like. A water-soluble polyvalent epoxy compound can be used as the cross-linking agent at that time. Examples of the water-soluble polyvalent epoxy compound include Denacol EX-521 (manufactured by Nagase Chemtech) and Tetrat-C (manufactured by Mitsui Gas Chemicals Co., Ltd.). Further, as an adhesive other than the polyvinyl alcohol-based resin, known adhesives such as urethane-based, acrylic-based, and epoxy-based adhesives can also be used. In particular, it is preferable to use polyvinyl alcohol modified with an acetoacetyl group, and it is more preferable to use a polyhydric aldehyde as a cross-linking agent thereof. In addition, for the purpose of improving the adhesive strength or water resistance of the adhesive, additives such as zinc compounds, chlorides, and iodides should be contained alone or simultaneously at a concentration of about 0.1 to 10% by mass. You can also. Additives to the adhesive are not particularly limited and can be appropriately selected by those skilled in the art. A polarizing plate can be obtained by bonding the transparent protective layer and the polarizing element with an adhesive and then drying or heat-treating at an appropriate temperature.

When the polarizing element or polarizing plate of the present invention is attached to a display device such as a liquid crystal display or an organic electroluminescence (commonly known as OLED or OEL), the viewing angle is improved and / on the surface of a protective layer or film which will later become an unexposed surface. Alternatively, various functional layers for improving contrast, and a layer or film having brightness improving property may be provided. The various functional layers are, for example, a layer or a film for controlling the phase difference. The polarizing plate is preferably attached to these films or display devices with an adhesive. By attaching a retardation plate, the polarizing plate of the present invention can also be used as an elliptical polarizing plate. The polarizing plate is preferably attached to these films or display devices with an adhesive.

The polarizing element or polarizing plate of the present invention may be provided with various known functional layers such as an AR layer (antireflection layer), an antiglare layer, and a hard coat layer on the transparent protective layer or the exposed surface of the film. good. A coating method is preferable for producing layers having various functions, but a film having the functions can also be bonded via an adhesive or an adhesive.

Examples of the hard coat layer include a protective layer such as an acrylic-based, polysiloxane-based, or urethane-based hard coat layer. Further, the AR layer can be expected to further improve the light transmittance of the single plate. The AR layer can be formed by coating, vapor deposition, or sputtering a substance such as silicon dioxide or titanium oxide, or by applying a thin coat of a fluorine-based substance.

The polarizing plate of the present invention has high transmittance and high degree of polarization, and can realize achromaticity while having high transmittance and high degree of polarization, and is particularly high quality when displayed in white. It is a highly durable polarizing plate that can express white color like paper and can express neutral black color when displayed in black.

<Display device>
The polarizing element or polarizing plate of the present invention is provided with a protective layer or a functional layer and a transparent support such as glass, crystal, or sapphire, if necessary, and is provided with a liquid crystal projector, a calculator, a clock, a notebook computer, a word processor, a liquid crystal television, or the like. It is applied to polarized lenses, polarized glasses, car navigation systems, and indoor and outdoor measuring instruments and displays.

In particular, the polarizing element or the polarizing plate of the present invention is suitably used for a liquid crystal display device, for example, a reflective liquid crystal display device, a transflective liquid crystal display device, and an organic electroluminescence other than the liquid crystal display device. The liquid crystal display device provided with the polarizing element or the polarizing plate of the present invention can express high-quality paper-like white and neutral black. Further, the liquid crystal display device is a liquid crystal display device having high durability, high reliability, high contrast in the long term, and high color reproducibility.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto. The% in the example is based on mass unless otherwise specified.

[Synthesis Example 1]
(Step 1)
After adding 15.0 parts of commercially available N-acetyl-1,4-phenylenediamine to 200 parts of water and stirring, 42 parts of 35% hydrochloric acid and 17.3 parts of 40% sodium nitrite were added for 1 hour. Diazotization was performed by stirring. Next, 32.0 parts of 1,8-dihydroxynaphthalene-3,6-disulfonic acid was added to 200 parts of water and dissolved in a 25% aqueous sodium hydroxide solution as weakly alkaline. The previously obtained diazo solution was added dropwise to this solution at a pH of 6.5 to 8.0, and the mixture was stirred to complete the coupling reaction. Subsequently, the obtained reaction solution was stirred at pH 0.0 to 0.5 at 90 ° C. to 99 ° C. for 5 hours to carry out a hydrolysis reaction, and then the precipitated solid was filtered off to be represented by the formula (13). We obtained 150 parts of a wet cake of the monoazo compound.

(Step 2)
150 parts of the obtained wet cake of the monoazo compound represented by the formula (13) was added to 300 parts of water, stirred and suspended, and the pH was adjusted to 9.0 using 25% sodium hydroxide, and 40% sodium nitrite was added thereto. 17.3 parts of aqueous solution was added. The obtained aqueous solution was added dropwise to a mixed solution of 200 parts of water and 42 parts of 35% hydrochloric acid to prepare a diazo solution. 15.3 parts of 2,5-dimethoxyaniline was added to the obtained diazo solution, and the mixture was stirred with 15% sodium carbonate aqueous solution at pH 1.5 to 4.0 for 8 hours to complete the coupling reaction. Then, it was salted out with sodium chloride and then filtered to obtain 200 parts of a wet cake of the disuazo compound represented by the formula (14).

(Step 3)
200 parts of the obtained wet cake of the disuazo compound represented by the formula (14) was added to 500 parts of water, stirred and suspended, and the pH was adjusted to 9.0 using 25% sodium hydroxide, and 40% sodium nitrite was added thereto. 17.3 parts of aqueous solution was added. The obtained suspension was added dropwise to a mixed solution of 100 parts of water and 42 parts of 35% hydrochloric acid to prepare a diazo solution. On the other hand, 31.5 parts of 1-hydroxy-6-anilino-3-naphthalene sulfonic acid was added to 300 parts of water and dissolved in a 25% aqueous sodium hydroxide solution as weakly alkaline. The previously obtained diazo solution was added dropwise to this solution at a pH of 6.5 to 8.0, and the mixture was stirred to complete the coupling reaction. Then, it was salted out with sodium chloride, filtered and dried to obtain 8.0 parts of the azo compound shown in Compound Example 3-8.

[Example 1]
A polyvinyl alcohol film (VF-PS # 7500 manufactured by Kuraray Co., Ltd.) having a saponification degree of 99% or more and an average degree of polymerization of 2400 was immersed in warm water at 40 ° C. for 3 minutes, and a swelling treatment was applied to increase the stretching ratio by 1.30 times. Was stretched. The obtained film is obtained from 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous brazing glass, and the azo compound of the formula (2), which is the azo compound of JP-A-2002-275381 (7). Immerse the compound in a staining solution containing 0.36 parts by mass and 0.22 parts by mass of Compound Example 3-8, which is the azo compound of the formula (3) obtained in Synthesis Example 1, and adjusted to 45 ° C. for 8 minutes. Then, the azo compound was contained in the film. The obtained film was immersed in an aqueous solution at 40 ° C. containing 20 g / l of boric acid (manufactured by Wako Pure Chemical Industries, Ltd.) for 1 minute. The film after immersion was stretched 5.0 times in an aqueous solution at 50 ° C. containing 30.0 g / l of boric acid for 5 minutes. The obtained film was washed by immersing it in water at 25 ° C. for 20 seconds while maintaining its tension. The washed film was dried at 70 ° C. for 9 minutes to obtain a polarizing element. An alkali-treated triacetyl cellulose film (ZRD-60 manufactured by Fujifilm Co., Ltd.) using polyvinyl alcohol (NH-26 manufactured by Japan Vam & Poval Co., Ltd.) dissolved in water at 4% of this polarizing element as an adhesive. ) Was laminated to obtain a polarizing plate. The obtained polarizing plate maintains the optical performance of the above-mentioned polarizing element, particularly the single transmittance of each wavelength, the parallel position transmittance of each wavelength, the orthogonal position transmittance of each wavelength, the hue, the degree of polarization and the like. rice field. This polarizing plate was used as the measurement sample of Example 1.

[Synthesis Example 2]
Changed 31.5 parts of 1-hydroxy-6-anilino-3-naphthalene sulfonic acid in step 3 of Synthesis Example 1 to 34.5 parts of 1-hydroxy-6- (4-methoxyphenylamino) -3-naphthalene sulfonic acid. In the same manner as in Synthesis Example 1, 8.0 parts of the azo compound shown in Compound Example 3-10 was obtained.

[Example 2]
The film obtained by applying the swelling treatment was prepared by a method according to the production method of Non-Patent Document 1 with 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous brazing glass, and the formula (2). Compound Example 2-102, which is an azo compound of the above, by 0.37 parts by mass, Compound Example 3-10, which is an azo compound of the formula (3) obtained in Synthesis Example 2, by 0.26 parts by mass, WO2007 / 138980. Compound Example 4-1 which is an azo compound of the formula (4) obtained by the method according to the above was treated with a staining solution at 45 ° C. containing 0.27 parts by mass for 8 minutes, except that the azo compound was contained. A polarizing plate was produced in the same manner as in Example 1.

[Synthesis Example 3]
Changed 31.5 parts of 1-hydroxy-6-anilino-3-naphthalene sulfonic acid in step 3 of Synthesis Example 1 to 35.8 parts of 1-hydroxy-6- (4-aminobenzoylamino) -3-naphthalene sulfonic acid. 11.0 parts of the azo compound shown in Compound Example 3-31 was obtained in the same manner as in Synthesis Example 1.

[Example 3]
Compound Example 1-13 (WO2016 / WO2016 / 186194 (28) Azo compound) 0.21 part by mass, compound example 3-31 which is the azo compound of the formula (3) obtained in Synthesis Example 3 is 0.26 part by mass, according to the production method of WO2007 / 138980. Compound Example 4-1 which is an azo compound of the formula (4) obtained by the same method was treated with a staining solution at 45 ° C. containing 0.25 parts by mass for 8 minutes, except that the azo compound was contained. A polarizing plate was produced in the same manner as in Example 1.

[Synthesis Example 4]
Synthetic Example by changing 32.0 parts of 1,8-dihydroxynaphthalene-3,6-disulfonic acid in step 1 of Synthesis Example 1 to 33.4 parts of 1-hydroxy-8-methoxynaphthalene-3,6-disulfonic acid. Changed 31.5 parts of 1-hydroxy-6-anilino-3-naphthalene sulfonic acid in step 3 of 1 to 37.5 parts of 1-hydroxy-6- (2,4-dimethoxyphenylamino) -3-naphthalene sulfonic acid. 12.0 parts of the azo compound shown in Compound Example 3-15 was obtained in the same manner as in Synthesis Example 1.

[Example 4]
The film obtained by applying the swelling treatment was prepared by a method according to the production method of Non-Patent Document 1 with 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous brazing glass, and the formula (2). 0.21 parts by mass of Compound Example 2-29, which is the azo compound described in the above, 0.28 parts by mass of Compound Example 3-15, which is the azo compound of the formula (3) obtained in Synthesis Example 4, WO2007 / 138980. Compound Example 4-1 which is an azo compound of the formula (4) obtained by a method according to the above-mentioned production method was treated with a dyeing solution at 45 ° C. containing 0.25 parts by mass for 8 minutes to contain the azo compound. A polarizing plate was produced in the same manner as in Example 1 except for the above.

[Synthesis Example 5]
The compound was prepared in the same manner as in Synthesis Example 1 except that 31.5 parts of 1-hydroxy-6-anilino-3-naphthalenesulfonic acid in step 3 of Synthesis Example 1 was changed to 34.4 parts of the compound represented by the following formula (15). 11.3 parts of the azo compound shown in Example 3-32 was obtained.

[Example 5]
The film obtained by applying the swelling treatment was obtained by adding 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous sodium sulfate, and C.I. I. Direct Red 117 (Compound Example 2-6) 0.18 parts by mass, Compound Example 3-32, which is the azo compound of the formula (3) obtained in Synthesis Example 5, was added to 0.30 parts by mass in the production method of WO2007 / 138980. Compound Example 4-1 which is an azo compound of the formula (4) obtained by the same method was treated with a staining solution at 45 ° C. containing 0.25 parts by mass for 8 minutes, except that the azo compound was contained. A polarizing plate was produced in the same manner as in Example 1.

[Example 6]
The film obtained by applying the swelling treatment was prepared by a method according to the production method of JP-A-8-291259, which was 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous brazing glass. 0.27 parts by mass of Compound Example 2-77, which is the azo compound of (2), 0.28 parts by mass of Compound Example 3-10, which is the azo compound of the formula (3) obtained in Synthesis Example 2. 4) The azo compound was treated with a staining solution at 45 ° C. containing 0.22 parts by mass of Compound Example 4-2 (azo compound described in Synthesis Example 1 of WO2007 / 138980) for 8 minutes to contain the azo compound. A polarizing plate was produced in the same manner as in Example 1 except for the above.

[Synthesis Example 6]
Same as Synthesis Example 1 except that 32.0 parts of 1,8-dihydroxynaphthalene-3,6-disulfonic acid in step 1 of Synthesis Example 1 was changed to 30.4 parts of 1-hydroxynaphthalene-3,6-disulfonic acid. Then, 13.5 parts of the azo compound shown in Compound Example 3-7 was obtained.

[Example 7]
The film obtained by applying the swelling treatment was prepared by a method according to the production method of JP-A-8-291259, which was 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous brazing glass. 0.23 parts by mass of Compound Example 2-70, which is the azo compound of (2), 0.29 parts by mass of Compound Example 3-7, which is the azo compound of the formula (3) obtained in Synthesis Example 6. 4) The azo compound was treated with a staining solution at 45 ° C. containing 0.24 parts by mass of Compound Example 4-2 (azo compound described in Synthesis Example 1 of WO2007 / 138980) for 8 minutes to contain the azo compound. A polarizing plate was produced in the same manner as in Example 1 except for the above.

[Synthesis Example 7]
(Step 1)
150 parts of the wet cake of the monoazo compound represented by the formula (13) in step 1 of Synthesis Example 1 was added to 300 parts of water, stirred and suspended, and the pH was adjusted to 9.0 using 25% sodium hydroxide, and 40% thereof. 17.3 parts of an aqueous sodium nitrite solution was added. The obtained aqueous solution was added dropwise to a mixed solution of 200 parts of water and 42 parts of 35% hydrochloric acid to prepare a diazo solution. 12.1 parts of 2,5-dimethylaniline was added to the obtained diazo solution, and the mixture was stirred with 15% sodium carbonate aqueous solution at pH 1.5 to 4.0 for 8 hours to complete the coupling reaction. Then, it was salted out with sodium chloride and then filtered to obtain 200 parts of a wet cake of the disuazo compound represented by the formula (16).

(Step 2)
150 parts of the obtained wet cake of the monoazo compound represented by the formula (16) was added to 300 parts of water, stirred and suspended, and the pH was adjusted to 9.0 using 25% sodium hydroxide, and a 40% sodium nitrite aqueous solution was added thereto. 17.3 parts were added. The obtained aqueous solution was added dropwise to a mixed solution of 200 parts of water and 42 parts of 35% hydrochloric acid to prepare a diazo solution. 15.3 parts of 2,5-dimethoxyaniline was added to the obtained diazo solution, and the mixture was stirred with 15% sodium carbonate aqueous solution at pH 1.5 to 4.0 for 8 hours to complete the coupling reaction. Then, it was salted out with sodium chloride and then filtered to obtain 200 parts of a wet cake of the trisazo compound represented by the formula (17).

(Step 3)
200 parts of the obtained wet cake of the trisazo compound represented by the formula (17) was added to 500 parts of water, stirred and suspended, and the pH was adjusted to 9.0 using 25% sodium hydroxide, and 40% sodium nitrite was added thereto. 17.3 parts of aqueous solution was added. The obtained suspension was added dropwise to a mixed solution of 100 parts of water and 42 parts of 35% hydrochloric acid to prepare a diazo solution. On the other hand, 31.5 parts of 1-hydroxy-6-anilino-3-naphthalene sulfonic acid was added to 300 parts of water and dissolved in a 25% aqueous sodium hydroxide solution as weakly alkaline. The previously obtained diazo solution was added dropwise to this solution at a pH of 6.5 to 8.0, and the mixture was stirred to complete the coupling reaction. Then, it was salted out with sodium chloride, filtered and dried to obtain 11.0 part of the azo compound shown in Compound Example 3-42.

[Example 8]
Compound Example 1-23 (WO2016 / WO2016 / No. 186194 (Azo compound of formula (54)) 0.21 parts by mass, compound example 3-42 obtained in Synthesis Example 7 which is an azo compound of formula (3) is 0.35 parts by mass, of formula (4). It was treated with a dyeing solution at 45 ° C. containing 0.26 parts by mass of Compound Example 4-2 (the azo compound described in Synthesis Example 1 of WO2007 / 138980), which is an azo compound, for 8 minutes, except that the azo compound was contained. A polarizing plate was produced in the same manner as in Example 1.

[Synthesis Example 8]
The compound was prepared in the same manner as in Synthesis Example 1 except that 31.5 parts of 1-hydroxy-6-anilino-3-naphthalene sulfonic acid in step 3 of Synthesis Example 1 was changed to 55.1 parts of the compound represented by the following formula (18). 6.2 parts of the azo compound shown in Example 3-35 were obtained.

[Example 9]
The film obtained by applying the swelling treatment was prepared by a method according to the production method of JP-A-8-291259, which was 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous brazing glass. 0.26 parts by mass of Compound Example 2-95 which is the azo compound of (2), 0.37 parts by mass of Compound Example 3-35 obtained in Synthesis Example 8 which is the azo compound of the formula (3). The azo compound was treated with a dyeing solution at 45 ° C. containing 0.25 parts by mass of Compound Example 5-88 (the azo compound described in WO2019 / 124161 Compound Example 1-B83), which is the azo compound of 5), for 8 minutes. A polarizing plate was produced in the same manner as in Example 1 except that it was contained.

[Example 10]
The film obtained by applying the swelling treatment was prepared by a method according to the production method of JP-A-8-291259, which was 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous brazing glass. 0.23 parts by mass of Compound Example 2-70, which is the azo compound of (2), 0.26 parts by mass of Compound Example 3-8, which is the azo compound of the formula (3) obtained in Synthesis Example 1. The azo compound was treated with a dyeing solution at 45 ° C. containing 0.25 parts by mass of Compound Example 5-88 (the azo compound described in WO2019 / 124161 Compound Example 1-B83), which is the azo compound of 5), for 8 minutes. A polarizing plate was produced in the same manner as in Example 1 except that it was contained.

[Synthesis Example 9]
Synthesis Example except that 31.5 parts of 1-hydroxy-6-anilino-3-naphthalene sulfonic acid in step 3 of Synthesis Example 1 was changed to 25.3 parts of 1-hydroxy-6-methylamino-3-naphthalene sulfonic acid. In the same manner as in No. 1, 9.2 parts of the azo compound shown in Compound Example 3-36 was obtained.

[Example 11]
Compound Example 1-13 (WO2016 / WO2016 / 186194 parts by mass of the azo compound of the formula (28), 0.24 parts by mass of the compound example 3-36 which is the azo compound of the formula (3) obtained in Synthesis Example 9 and the formula (5). The compound was treated with a staining solution at 45 ° C. containing 0.22 parts by mass of Compound Example 5-3 (the azo compound according to WO2019 / 124161 Compound Example 1-A4), which is an azo compound, for 8 minutes to contain the azo compound. A polarizing plate was produced in the same manner as in Example 1 except for the above.

[Synthesis Example 10]
31.5 parts of 1-hydroxy-6-anilino-3-naphthalene sulfonic acid in step 3 of Synthesis Example 1 and 37.5 parts of 1-hydroxy-6- (2,4-dimethoxyphenylamino) -3-naphthalene sulfonic acid 8.9 parts of the azo compound shown in Compound Example 3-14 was obtained in the same manner as in Synthesis Example 1 except that the mixture was changed to.

[Example 12]
The film obtained by applying the swelling treatment was prepared by a production method according to 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous brazing glass, and the manufacturing method of JP-A-2002-275381. Compound Example 2-103, which is the azo compound of (2), is 0.30 parts by mass, and Compound Example 3-14, which is the azo compound of the formula (3) obtained in Synthesis Example 10, is 0.29 parts by mass. The azo compound was treated with a staining solution at 45 ° C. containing 0.21 parts by mass of Compound Example 5-84 (the azo compound according to WO2019 / 124161 Compound Example 1-B64) which is the azo compound of 5) for 8 minutes. A polarizing plate was produced in the same manner as in Example 1 except that it was contained.

[Example 13]
The film obtained by applying the swelling treatment was compounded with 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous brazing glass, and Compound Example 2-59 (WO2012 / Publication No. 108169 Compound Example (17) 0.29 parts by mass, Compound Example 3-10, which is the azo compound of the formula (3) obtained in Synthesis Example 2, 0.29 parts by mass, azo of the formula (5) Treatment with a staining solution at 45 ° C. containing 0.21 parts by mass of Compound Example 5-84 (the azo compound according to WO2019 / 124161 Compound Example 1-B64), which is a compound, for 8 minutes, except that the azo compound was contained. Made a polarizing plate in the same manner as in Example 1.

[Example 14]
The film obtained by applying the swelling treatment was prepared by a production method according to 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous brazing glass, and the production method of JP-A-2002-275381. Compound Example 2-103, which is the azo compound of (2), is 0.30 parts by mass, and Compound Example 3-14, which is the azo compound of the formula (3) obtained in Synthesis Example 10, is 0.29 parts by mass. 5) The C.I. I. The Direct Orange 72 was treated with a staining solution containing 0.20 parts by mass at 45 ° C. for 8 minutes to prepare a polarizing plate in the same manner as in Example 1 except that it contained an azo compound.

[Example 15]
The film obtained by applying the swelling treatment was compounded with 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous brazing glass, and compound example 2-26 (WO2005 / WO2005 /) which is an azo compound of the formula (2). 075572 The azo compound of the formula (4)) 0.22 parts by mass, the compound example 3-7 which is the azo compound of the formula (3) obtained in Synthesis Example 6 was 0.29 parts by mass, C.I. I. The Direct Yellow 12 was treated with a staining solution containing 0.30 parts by mass at 45 ° C. for 8 minutes to prepare a polarizing plate in the same manner as in Example 1 except that the azo compound was contained.

[Comparative Example 1]
As a general dye-based polarizing plate, a high-transmittance dye-based polarizing plate SHC-115 manufactured by Polatechno Co., Ltd., which has a neutral gray color, was obtained and used as a measurement sample.

[Comparative Example 2]
As a general dye-based polarizing plate, a neutral gray-colored, high-contrast dye-based polarizing plate SHC-128 manufactured by Polatechno Co., Ltd. was obtained and used as a measurement sample.

[Comparative Examples 3 to 8]
According to the production method described in Comparative Example 1 of Patent Document 9, the iodine content time was set to 5 minutes and 30 seconds in Comparative Example 3, 4 minutes and 45 seconds in Comparative Example 4, 4 minutes and 15 seconds in Comparative Example 5, and in Comparative Example 6. An iodine-based polarizing plate containing no azo compound was prepared by the same method except that the changes were made for 3 minutes and 30 seconds, in Comparative Example 7 for 4 minutes and 00 seconds, and in Comparative Example 8 for 5 minutes and 15 seconds. bottom.

[Comparative Example 9]
An iodine-based polarizing plate SKW-18245P manufactured by Polatechno Co., Ltd., which shows a paper white color in a parallel position, was obtained and used as a measurement sample.

[Comparative Examples 10 to 11]
In Example 1, the aqueous solution (staining solution) containing the azo compound has the composition described in Example 1 of Patent Document 3, and the same applies to the following except that the respective staining times are changed to 6 minutes and 5 minutes, which will be described later. The polarizing plates of Comparative Example 10 and Comparative Example 11 were prepared by adjusting the time for immersing the swollen film in the aqueous solution so that the simple substance transmittance was about 41% and containing the azo compound, respectively.

[Comparative Example 12]
The polarizing plate described in Example 1 of Patent Document 8 relating to a dye-based polarizing plate was produced.

[Comparative Example 13]
The polarizing plate described in Example 3 of Patent Document 9 relating to a dye-based polarizing plate was produced.

[Comparative Example 14]
The polarizing plate described in Example 1 of Patent Document 10 relating to a dye-based polarizing plate was produced.

[Comparative Example 15]
The polarizing plate described in Example 15 (No. 1) of Patent Document 11 relating to a dye-based polarizing plate was produced.

[Comparative Example 16]
In Example 10, instead of the azo compound of Compound Example 2-70, C.I. I. Using Direct Red 80, a staining solution was prepared so that the obtained polarizing element had the same simple substance transmittance, and a polarizing plate was prepared in the same manner as in Example 10 except that the polarizing element contained an azo compound. ..

[Comparative Example 17]
In Example 10, instead of the azo compound of Compound Example 3-8, C.I. I. Using Direct Blue 67, a staining solution was prepared so that the obtained polarizing element had the same simple substance transmittance, and a polarizing plate was prepared in the same manner as in Example 10 except that the azo compound was contained in the polarizing element. ..

[Evaluation methods]
The measurement samples obtained in Examples 1 to 15 and Comparative Examples 1 to 17 were evaluated as follows.
(A) Single transmittance Ts, parallel position transmittance Tp and orthogonal position transmittance Tc of each wavelength
The single transmittance Ts, parallel position transmittance Tp and orthogonal position transmittance Tc of each wavelength of each measurement sample were measured using a spectrophotometer (“U-4100” manufactured by Hitachi High-Tech Science Co., Ltd.). Here, the simple substance transmittance Ts (%) of each wavelength is the transmittance of each wavelength when the measurement sample is measured by one sheet. The parallel transmittance Tp (%) of each wavelength is the spectral transmittance of each wavelength measured by superimposing two measurement samples so that their absorption axis directions are parallel to each other. The orthogonal transmittance Tc (%) of each wavelength is the spectral transmittance measured by superimposing two measurement samples so that their absorption axes are orthogonal to each other. Measurements were made over the wavelength range of 380-780 nm.
(B) Single transmittance Ys after luminosity factor correction, parallel transmittance Yp after luminosity factor correction, and orthogonal transmittance Yc after luminosity factor correction.
The single transmittance Ys (%) after the luminosity factor correction, the parallel transmittance Yp (%) after the luminosity factor correction, and the orthogonal transmittance Yc (%) after the luminosity factor correction were obtained for each measurement sample. The single transmittance Ys (%) after the visual sensitivity correction, the parallel position transmittance Yp (%) after the visual sensitivity correction, and the orthogonal position transmittance Yc (%) after the visual sensitivity correction are in the wavelength region of 380 to 780 nm. The single transmittance Ts of each wavelength, the parallel position transmittance Tp of each wavelength, and the orthogonal position transmittance Tc of each wavelength obtained at predetermined wavelength intervals dλ (here, 5 nm) are viewed according to JIS Z 8722: 2009. It is the transmittance corrected to the sensitivity. Specifically, the simple substance transmittance Ts of each wavelength, the parallel-position transmittance Tp of each wavelength, and the orthogonal-position transmittance Tc of each wavelength were calculated by substituting them into the following equations (I to III). In the following equations (I to III), Pλ represents the spectral distribution of standard light (C light source), and yτλ represents the two-degree visual field color matching function. The results are shown in Table 1.

(C) Contrast By calculating the ratio (Yp / Yc) of the parallel transmittance Yp after luminosity factor correction and the orthogonal luminosity factor Yc after luminosity factor correction, which are measured using two identical measurement samples. , Contrast (CR) was determined. The results are shown in Table 1.

(D) Degree of polarization ρy after correction of visual sensitivity
The degree of polarization ρy after correction of luminosity factor of each measurement sample was obtained by substituting the parallel transmittance Yp after correction of luminosity factor and the orthogonal position transmittance Yc after correction of luminosity factor into the following equation (IV). The results are shown in Tables 1 and 2.

Comparing Examples 1 to 15 with Comparative Examples 1 and 10 to 17, the polarizing plate of the present invention has a high degree of polarization and contrast, and the degree of polarization and contrast are almost the same as those of Comparative Example 2. It can be seen that the single transmittance is about 1 to 2% lower than that of the value. Therefore, it can be seen that the polarizing plate of the present invention improves the performance of the dye-based polarizing plate. In Comparative Examples 3 to 9, as will be described later, although a polarizing plate having high contrast and high degree of polarization has been obtained, the durability is low.

Next, the average transmittance (AT 420-480) at 420 to 480 nm and the average transmittance (AT _520-590 ) at 520 to 590 nm of the parallel position transmittance Tp and the orthogonal position transmittance Tc obtained by the above-mentioned measurements, respectively _. ), And the average transmittance (AT _600-640 ) at 600 to 640 nm are shown in Tables 3 and 4.

(E) Absolute value of the difference between the average transmittances of the two wavelength bands The average transmittance (AT ₅₂₀ ) of each of the parallel position transmittance Tp of each wavelength and the orthogonal position transmittance Tc of each wavelength at 520 to 590 nm of each measurement sample. It shows the absolute value of the difference between _{-590) and the average transmittance (AT 420-480} ₎ at 420 to 480 nm, and the average transmittance at 520 to 590 nm (AT _520-590 ) and the average transmittance at 600 to 640 nm (AT). The absolute value of the difference from _600-640 ) was measured. The results are shown in Tables 5 and 6.

From Table 3, it can be seen that the measurement samples of Examples 1 to 15 have a high average transmittance (AT _520-590 ) of the parallel transmittance Tp of each wavelength at 520 to 590 nm, which is 32.15% or more.
Further, from Tables 3 to 6, the difference between the average transmittance (AT _520-590 ) and the average transmittance (AT _420-480 ) in the parallel transmittance Tp of Examples 3 and 5 to 15 is smaller than 3.0. Moreover, it can be seen that the difference between the average transmittance (AT _520-590 ) and the average transmittance (AT _600-640 ) is smaller than 2.5. Further, in the measurement samples of Examples 6, 7, 12, and 14, the difference between the average transmittance (AT _520-590 ) and the average transmittance (AT _420-480 ) at the parallel transmittance Tp. Further, the difference between the average transmittance (AT _520-590 ) and the average transmittance (AT _600-640 ) at the parallel transmittance Tp is within 2%, and it can be seen that the difference between each wavelength band is extremely small. Further, the difference between the average transmittance (AT _520-590 ) and the average transmittance (AT _420-480 ) in the orthogonal position transmittance Tc of Examples 6, 12, and 14, as well as the orthogonal position transmittance Tc. The difference between the average transmittance (AT _520-590 ) and the average transmittance (AT _600-640 ) in the above is within 1%, and the polarizing plate of the present invention is compared with Comparative Examples 1 to 9 and Comparative Examples 12 to 17. It can be seen that there is no difference between each wavelength band even in Tc of each wavelength. On the other hand, in the measurement samples of Comparative Examples 10 to 11, the difference between the average transmittance (AT _520-590 ) and the average transmittance (AT _420-480 ) at Tp is within 2.5%, and at Tp. The difference between the average transmittance (AT _520-590 ) and the average transmittance (AT _600-640 ) is within 3.0%, and the difference in the average transmittance in Tc is 1%, which are shown in Table 2. As you can see, the contrast and the degree of polarization are low. From the above, it can be seen that the polarizing element of the present application can realize a polarizing element having no wavelength dependence at Tp and Tc of each wavelength, or a polarizing plate thereof, while having high transmittance and high degree of polarization.

(F) Chromaticity a * value and b * value For each measurement sample, according to JIS Z 8781-4: 2013, when measuring the single transmittance Ts of each wavelength, when measuring the parallel transmittance Tp of each wavelength, and of each wavelength. The chromaticity a * value and b * value at the time of measuring the orthogonal position transmittance Tc were measured. The above spectrophotometer was used for the measurement. A C light source was used as the light source. The results are shown in Tables 7 and 8. Here, a * -s and b * -s, a * -p and b * -p, and a * -c and b * -c have a single transmittance Ts, a parallel transmittance Tp, and an orthogonal transmittance, respectively. It corresponds to the chromaticity a * value and b * value at the time of Tc measurement, respectively.

(G) Observation of color For each measurement sample, two identical measurement samples were placed on a mirror commercially available as a reflector in parallel and orthogonal positions, and the color observed at that time was observed. investigated. The observations were made visually by 10 observers, and the most observed colors are shown in Tables 7 and 8. In the table, the colors in the parallel position mean the colors in which two identical samples are stacked so that their absorption axis directions are parallel to each other (when displayed in white), and the colors in the orthogonal position are the same samples. It means the color in a state where two sheets are overlapped so that their absorption axis directions are orthogonal to each other (when displayed in black). Basically, the polarized color is "white" for the parallel position and "black" for the orthogonal position, but in the examples or comparative examples, for example, yellowish white is "yellow". , Blue-purple black is referred to as "blue-purple".

As shown in Tables 7 and 8, the measurement samples of Examples 1 to 15 have a single transmittance Ys of 40% or more after the visual sensitivity correction, and further, Examples 2, Example 7, and Example 12 have a single transmittance of 40% or more. In the measurement samples of Examples 14 and 15, the absolute values of the chromaticities a * -s and b * -s are both 1.0 or less, and the absolute values of the chromaticities a * -p and b * -p are Shows a small value of 2.0 or less. In addition, since it has a high transmittance and a high degree of polarization of 97% or more, it was found that white and black can be sufficiently expressed. On the other hand, in Comparative Examples 1 to 9 and Comparative Examples 12 to 17, the absolute values of the chromaticities a * -s and b * -s are both higher than 1, and the absolute values of the chromaticities a * -p and b * -p are high. Is higher than 3 or any of chromaticity a * -c and b * -c is higher than 1 when the degree of polarization is 97% or less. It turned out that I could not fully express. Further, although white and black can be sufficiently expressed in the measurement samples of Comparative Examples 10 to 11, the contrast and the degree of polarization are low as shown in Table 2.
From the above, the polarizing element of the present invention can be designed so that it can sufficiently express achromatic colors in both parallel and orthogonal positions, that is, white and black, while having high transmittance and high degree of polarization, or It was shown that the polarizing plate can be realized.

From the above, the polarizing element of the present invention can express high-quality paper-like white color in parallel position while maintaining high single-unit transmittance and parallel-position transmittance, and is high-quality without coloring by itself. It was shown to be a hue with a neutral color (achromatic neutral gray). Further, it can be seen that the polarizing element of the present invention maintains a single transmittance after high luminosity factor correction, exhibits achromaticity at parallel positions, and also has a high degree of polarization. Further, it can be seen that the polarizing element of the present invention makes it possible to obtain a polarizing element showing a high-quality achromatic black at an orthogonal position.

(H) Durability test The measurement samples of Examples 1 to 17 and Comparative Examples 3 to 9 were placed in an environment of 85 ° C. with a relative humidity of 85% RH for 240 hours to perform a durability test. As a result, no change in transmittance or hue was observed in the measurement samples of Examples 1 to 17. On the other hand, in the measurement samples of Comparative Examples 3 to 9, the degree of polarization was reduced by 10% or more, the chromaticity b * -c was lower than -10, and the apparent color changed significantly to blue. When the samples were arranged in the orthogonal position (when displayed in black), the color was greatly blue. Therefore, it was found that the polarizing element of the present invention has high durability.

The polarizing element or polarizing plate of the present invention is used for a liquid crystal display device, for example, a reflective liquid crystal display device, a transflective liquid crystal display device, and an organic electroluminescence other than the liquid crystal display device. The liquid crystal display device provided with the polarizing element or the polarizing plate of the present invention can express high-quality paper-like white and neutral black. Further, the liquid crystal display device can be used for a liquid crystal display device having high durability, high reliability, long-term high contrast, and high color reproducibility.

Claims

In the form of free acid, an azo compound represented by the following formula (1) or a salt thereof or an azo compound represented by the following formula (2) or a salt thereof and an azo compound represented by the following formula (3) or a salt thereof. A polarizing element containing a salt.

(In the formula (1), Ac 1 independently represents a phenyl group or a naphthyl group having at least one substituent selected from a sulfo group and a carboxy group, and Rc 11 to Rc 14 are independent of each other. Represents a hydrogen atom, an alkyl group of C1 to 4, an alkoxy group of C1 to 4, or an alkoxy group of C1 to 4 having a sulfo group.)

(In the formula (2), Ac 2 represents a phenyl group or a naphthyl group having at least one substituent selected from a sulfo group and a carboxy group, and Rc 21 to Rc 28 are independent hydrogen atoms, respectively. Represents an alkoxy group of C1 to 4 having an alkyl group of C1 to 4, an alkoxy group of C1 to 4 or a sulfo group, and Xc 2 has an amino group and a substituent which may have at least one substituent S. It represents a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a naphthotriazole group which may have a substituent or a benzoylamino group which may have a substituent, and the substituent S 2 is represented. (Independently if there are multiple groups), C1-4 alkyl groups that may further have substituents, C1-4 alkoxy groups, sulfo groups, C1-4 alkylamino groups, hydroxy groups, aminos. It is selected from a group, a substituted amino group, a carboxy group, and a carboxyethylamino group, and r, p, and q each independently indicate 0 or 1, except that r, p, and q are all 1. When either p or q is 1 and Ac 2 is a naphthyl group, it does not contain a hydroxy group as a substituent.)

(In formula (3), Ra 1 , Ra 2 , Ab 1 or Ab 2 is substituted with either ring a or ring b, and either one of Ra 1 or Ra 2 is a hydroxy group and the other. Represents a hydrogen atom, a hydroxy group, an alkoxy group of C1 to 4 or an alkoxy group of C1 to 4 having a sulfo group, and either Ab 1 or Ab 2 may have a sulfo group, a carboxy group or a substituent. Representing an amino group, the other is a substituent selected from a hydrogen atom, a sulfo group, a carboxy group, or an amino group which may have a substituent, and Rb 1 to Rb 6 are independently hydrogen atoms. , C1-4 alkyl group, C1-4 alkoxy group, sulfo group, C1-4 alkoxy group having sulfo group, or amino group which may have a substituent, h represents 0 or 1. , Xb 1 may have an amino group which may have at least one substituent S 3 , a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, or a substituent. A good naphthotriazole group or a benzoylamino group which may have a substituent is shown, and the substituent S3 ( independently if there is more than one) is an alkyl group of C1-4 which may further have a substituent. , C1-4 alkoxy group, sulfo group, amino group, C1-4 alkylamino group, hydroxy group, carboxy group and carboxyethylamino group).
The polarizing element according to claim 1, further comprising an azo compound represented by the following formula (4) or a salt thereof, or an azo compound represented by the formula (5) or a salt thereof.

(In the formula (4), Ay 11 independently represents a sulfo group, a carboxy group, a hydroxy group, an alkyl group of C1 to 4 or an alkoxy group of C1 to 4, and Ry 11 to Ry 14 independently represent hydrogen atoms. , C1-4 alkyl group, C1-4 alkoxy group or C1-4 alkoxy group having sulfo group, f indicates an integer of 1-3)

(In the formula (5), Ay 21 and Ay 22 are independently naphthyl groups which may have a substituent or a phenyl group which may have a substituent, and are Ry 21 , Ry 22 , Ry 27 , and Ry 27. And Ry 28 are independently hydrogen atoms, C1 to 4 alkyl groups, and C1 to 4 alkoxy groups, and Ry 23 to Ry 26 are independently hydrogen atoms, C1 to 4 alkyl groups, and C1 to C1 to Ry 26, respectively. It is an alkoxy group of C1 to 4 having an alkoxy group of 4 and a sulfo group, and s and t independently indicate 0 or 1 respectively.)
The polarizing element according to claim 1 or 2, wherein the azo compound represented by the formula (3) or a salt thereof is an azo compound represented by the following formula (6) or a salt thereof.

(In the formula (6), Ra 1 , Ra 2 , Ab 1 , Ab 2 , Rb 1 to Rb 6 , h, and Xb 1 have the same meanings as those in the formula (3).)
The polarizing element according to any one of claims 1 to 3, wherein the azo compound represented by the formula (3) or a salt thereof is an azo compound represented by the following formula (7) or a salt thereof.

(In the formula (7), Ra 1 , Ra 2 , Ab 1 , Ab 2 , Rb 1 to Rb 6 , h, and Xb 1 have the same meanings as those in the formula (3).)
The polarizing element according to any one of 1 to 4, wherein the azo compound represented by the formula (3) or a salt thereof is an azo compound represented by the following formula (8) or a salt thereof.

(In the formula (8), Ra 1 , Ab 1 , Rb 1 to Rb 6 , h, and Xb 1 have the same meanings as in the formula (3), and Ra 3 represents a hydrogen atom or a hydroxy group.)
The polarizing element according to any one of claims 1 to 5, wherein the azo compound represented by the formula (3) or a salt thereof is an azo compound represented by the following formula (9) or a salt thereof.

(In the above formula (9), Ra 1 , Ab 1 , Rb 1 to Rb 6 , h, and Xb 1 have the same meanings as those in the formula (2).)
The average transmittance of 420 nm to 480 nm and the average transmittance of 520 nm to 590 nm are obtained in the transmittance of each wavelength obtained by stacking two polarizing elements so that their absorption axis directions are parallel to each other. Claim 1 to claim 1, wherein the difference is 2.5% or less as an absolute value, and the difference between the average transmittance of 520 nm to 590 nm and the average transmittance of 600 nm to 640 nm is 3.0% or less as an absolute value. 6. The polarizing element according to any one of 6.
Any of claims 1 to 7, wherein the absolute values of the a * value and the b * value in the polarizing element alone obtained at the time of transmittance measurement using natural light according to JIS Z8781-4: 2013 are both 1.0 or less. The polarizing element according to one item.
According to JIS Z8781-4: 2013 in a state where two polarizing elements are stacked so that their absorption axis directions are parallel to each other, the a * value obtained at the time of transmittance measurement using natural light is -2. The polarizing element according to any one of claims 1 to 8, which is 0.0 to 2.0 and has an absolute value of b * of −2.0 to 3.0.
The single transmittance of the polarizing element after correction of the visual sensitivity is 35% to 65%, and the wavelength band is 520 nm to 590 nm in a state where two polarizing elements are stacked so as to be parallel to each other in the absorption axis direction. The polarizing element according to any one of claims 1 to 9, wherein the average transmittance of the above is 25% to 50%.
The difference between the average transmittance of 420 nm to 480 nm and the average transmittance of 520 nm to 590 nm is 1.0% as an absolute value when two polarizing elements are stacked so that their absorption axis directions are orthogonal to each other. The polarizing element according to any one of claims 1 to 10, wherein the difference between the average transmittance of 520 nm to 590 nm and the average transmittance of 600 nm to 640 nm is 1.0% or less as an absolute value.
In a state where two polarizing elements are stacked so that their absorption axis directions are orthogonal to each other, the orthogonal position transmittance of each wavelength in the wavelength band of 420 nm to 480 nm, 520 nm to 590 nm and 600 nm to 640 nm is 1%. The polarizing element according to any one of claims 1 to 11, wherein the degree of polarization is as follows, or the degree of polarization after correction of visual sensitivity is 97% or more.
In a state where two polarizing elements are stacked so that their absorption axis directions are orthogonal to each other, the a * value and b * value at the time of transmittance measurement using natural light according to JIS Z8781-4: 2013. The polarizing element according to any one of claims 1 to 12, wherein the absolute value is 2.0 or less.
The polarizing element according to any one of claims 1 to 13, which comprises a base material.
The polarizing element according to claim 14, which comprises a polyvinyl alcohol-based resin film as a base material.
A polarizing plate provided with a transparent protective layer provided on one side or both sides of the polarizing element according to any one of claims 1 to 15.
A display device including the polarizing element according to any one of claims 1 to 15 or the polarizing plate according to claim 16.