TW202106814A - Achromatic polarizing element, and achromatic polarizing plate and display using the same - Google Patents

Abstract

A polarizing element contains an azo compound represented by formula (1) or a salt thereof and an azo compound represented by formula (2) or a salt thereof.

In the formula (2), Ag₁ represents a phenyl group having a substituent or a naphthyl group having a substituent, Bg and Cg are each independently represented by the formula (3) or the formula (4), and any one of them is represented by the formula (3).

Description

Achromatic polarizing element, and achromatic polarizing plate and display device using the polarizing element

The present invention relates to an achromatic dye-based polarizing element, and an achromatic polarizing plate and a display device using the polarizing element.

Polarizing elements are generally manufactured by adsorbing aligned iodine or dichroic dyes on a substrate such as a polyene film. The polyene film will dehydrochloride the film or polyvinyl chloride film on which polyvinyl alcohol or its derivatives are stretched and aligned. , Or the polyvinyl alcohol-based film is dehydrated to generate polyene and align it. A protective film composed of cellulose triacetate or the like is bonded to the polarizing element through the adhesive layer to obtain a polarizing plate, which is used in a liquid crystal display device and the like. Polarizers that use iodine as a dichroic pigment are called iodine-based polarizers. On the other hand, a polarizer that uses dichroic dyes, such as a polarizer that uses a dichroic azo compound as a dichroic pigment, is called a dye-based polarizer. Polarizing plate. These dye-based polarizers have high heat resistance, high humidity and heat durability, and high stability. In addition, they have higher color selectivity due to the blending of pigments. On the other hand, they have the same degree of polarization compared to The iodine-based polarizer has penetrating The problem of low rate and contrast. Therefore, there is a need for a polarizing element that can maintain high durability and diverse color selectivity, but also has high polarization characteristics through higher transmittance.

In addition, even for dye-based polarizers with various color selectivity, the polarizing elements so far are superimposed in such a way that the absorption axis directions of the two polarizing elements become parallel to each other (hereinafter, also referred to as "parallel position"). When it is arranged and displayed in white (hereinafter, also referred to as "white display" or "bright display"), there is a problem of white with a slight yellowish sensation. Even if a polarizing element that suppresses the yellowish feeling is produced in order to alleviate the problem of the white and yellowish feeling, the polarizing plate so far has made two polarizing elements perpendicular to each other in the direction of the absorption axis (hereinafter, also referred to as When the "orthogonal bit" is arranged in an overlapping manner and displays black (hereinafter, also referred to as "dark display" or "dark display"), there is a problem of blue color. Accordingly, a polarizing plate that displays achromatic white in white display and black in black display is required. In particular, it is difficult to obtain a high-quality white polarizing plate for white display. Such a polarizing plate is generally called a paper white polarizing plate.

In order to make the polarizing plate achromatic, the transmittance of each wavelength in the parallel position or the orthogonal position must be almost constant regardless of the wavelength. So far, such a polarizing plate has not been available.

The reason for the difference in hue between the white display and the black display is that the wavelength dependence of the transmittance of the parallel position and the orthogonal position is different, and in particular, the transmittance is not constant in the visible light range. In addition, the fact that the dichroism is not fixed in the visible light field is also one of the main reasons why it is difficult to realize an achromatic polarizer.

Taking the iodine-based polarizer as an example, an iodine-based polarizer that uses polyvinyl alcohol (hereinafter, also referred to as "PVA") as a base material and uses iodine as a dichroic dye, usually has 480nm and 600nm as the center The absorption. The absorption at 480 nm is believed to be due to the _{complex of polyiodine I 3} ^- and PVA, and the absorption at 600 nm is believed to be due to the _{complex of polyiodine I 5} ^- and PVA. The degree of polarization (dichroism) at each wavelength is _{higher based on the complex of polyiodide I 5} ^- and PVA than that based on the complex of polyiodide I ₃ ^- and PVA. That is, if the transmittance of the orthogonal position is fixed in each wavelength, the transmittance of the parallel position of 600nm is higher than the transmittance of the parallel position of 480nm, which causes the phenomenon of white coloring and yellowing during white display. On the contrary, if the parallel bit penetration rate is fixed, the cross bit penetration rate of 600 nm is lower than the cross bit penetration rate of 480 nm, which causes the black to be colored with blue in black display. When the white display is yellow, generally speaking, it gives the impression that it is deteriorating, so it is hardly better. In addition, when it appears blue during black display, it cannot become a clear black, giving an impression of no sense of luxury. In addition, in the iodine-based polarizing plate, there is no complex compound based on the wavelength near 550 nm where the main visual sensitivity is high, and it is difficult to control the hue.

As mentioned above, the degree of polarization (dichroism) of each wavelength is not fixed, which leads to the wavelength dependence of the degree of polarization. In addition, the complex formed by iodine and PVA has only two absorptions at 480nm and 600nm, so the iodine-based polarizer composed of iodine and PVA cannot adjust the hue.

The method of improving the hue of the iodine-based polarizing plate is described in Patent Document 1 or Patent Document 2. Patent Document 1 describes a polarizing plate whose neutral coefficient is calculated and whose absolute value is 0 to 3. Patent Document 2 describes a polarizing film whose transmittance from 410nm to 750nm is within ±30% of its average value. In addition to iodine, direct dyes, reactive dyes, or acid dyes are added to adjust the color to make. In addition, the technology of achromatic coloring-based polarizing plate like Patent Document 3 is also disclosed.

[Prior Technical Literature]

[Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2002-169024

Patent Document 2: Japanese Patent Laid-Open No. 10-133016

Patent Document 3: WO2014/162635 Publication

Patent Document 4: Japanese Patent Application Laid-Open No. 8-291259

Patent Document 5: Japanese Patent Laid-Open No. 2002-275381

Patent Document 6: WO2015/152026 Publication

Patent Document 7: Japanese Patent Laid-Open No. 1-161202

Patent Document 8: Japanese Patent Application Laid-Open No. 1-172907

Patent Document 9: Japanese Patent Laid-Open No. 1-183602

Patent Document 10: Japanese Patent Laid-Open No. 1-248105

Patent Document 11: Japanese Patent Application Laid-Open No. 1-265205.

Patent Document 12: Japanese Patent Publication No. 7-92531

Patent Document 13: Japanese Patent Laid-Open No. 2009-132794

Patent Document 14: Japanese Patent Application Laid-Open No. 2008-065222

Patent Document 15: Japanese Patent Laid-Open No. 2003-215338

Patent Document 16: Japanese Patent Laid-Open No. 11-218611.

Patent Document 17: Japanese Patent Application Publication No. 2001-033627

Patent Document 18: Japanese Patent Laid-Open No. 2004-251962

Patent Document 19: Japanese Patent Application Laid-Open No. 8-291259

[Non-Patent Literature]

Non-Patent Document 1: Application of Functional Pigments (published by CMC Co., Ltd., the first edition, supervised by Masahiro Irie, pages 98 to 100)

Non-Patent Document 2: Dye Chemistry; by Hosoda Toyoda, published by Jihodo, 1957, page 621

However, for the polarizing plate of Patent Document 1, for example, it is known from Example 1 that even if the neutral coefficient (Np) is low, the parallel hue obtained from JIS Z 8729 has a* value of -1.67 and b* value of 3.51, so When white is displayed, it is yellow-green. In addition, although the a* value of the orthogonal hue is 0.69 but the b* value is -3.40, it is blue when displayed in black. In addition, the polarizing film of Patent Document 2 is obtained by using only one polarizing film and setting the a value and b value in the measured UCS color space to an absolute value of 2 or less. When two polarizing films are superimposed, the white display is When displaying in black and black, achromatic color cannot be expressed in both hues at the same time. In addition, the average monomer transmittance of the polarizing film of Patent Document 2 is 31.95% in Example 1 and 31.41% in Example 2, which shows a low value. As mentioned above, the polarizing film of Patent Document 2 has a low transmittance, and therefore does not have sufficient performance in fields requiring high transmittance and high contrast, especially in the fields of liquid crystal display devices and organic electroluminescence. In addition, the polarizing film of Patent Document 2 mainly uses iodine as a dichroic dye. Therefore, after a durability test, especially after a damp heat durability test (e.g., an environment of 85°C and a relative humidity of 85%), the color changes greatly. The durability is poor.

On the other hand, although the dye-based polarizing plate is excellent in durability, the wavelength dependence is different between the parallel position and the orthogonal position, and this system is the same as the iodine-based polarizing plate. There is almost no azo compound exhibiting the dichroism of the same hue in the parallel position and the orthogonal position, and even if it exists, its dichroism (polarization characteristic) is low. Depending on the type of the dichroic azo compound, there are also azo compounds that are yellow in white display and blue in black display, and have completely different wavelength dependences in the orthogonal position and the parallel position. Also, according to the brightness of light, people’s sensibility to color is different, even if The color correction of the dye-based polarizer still needs to control the polarization from the orthogonal position to the parallel position to correct the brightness and darkness of the various generated light. Unless the transmittance in the parallel position and the orthogonal position is almost a fixed value at each wavelength and there is no wavelength dependency, an achromatic polarizing plate cannot be achieved. Furthermore, in order to obtain a polarizing element with high transmittance and high contrast, in addition to satisfying a fixed transmittance in parallel and orthogonal positions at the same time, the polarization degree (dichroic ratio) of each wavelength must be high and fixed. Although when one type of azo compound is applied to the polarizing element, the wavelength dependence of the transmittance of each wavelength in the orthogonal position and the parallel position is different, in order to mix two or more azo compounds and achieve a fixed transmission in each wavelength It is necessary to consider the penetration rate of each parallel position and orthogonal position, and precisely control the two-color ratio relationship of more than two kinds.

On the other hand, even if the relationship between the transmittance of each wavelength and the dichroic ratio of the parallel position and the orthogonal position is precisely controlled, and the transmittance can be fixed at each wavelength, high transmittance and high contrast cannot be achieved. . That is, the higher the transmittance or the higher the degree of polarization, the more difficult it is to become achromatic, and an achromatic polarizer with high transmittance or high degree of polarization cannot be achieved. It is very difficult to obtain an achromatic polarizer with high transmittance and/or high contrast, and it is not suitable for those that can only be achieved by using dichroic pigments of the three primary colors. In particular, it is extremely difficult to simultaneously achieve a fixed transmittance and high dichroism in each wavelength in a parallel position. High-quality white cannot be displayed with white coloring only slightly. In addition, the white color in the bright state is particularly important because of its high brightness and high sensitivity. Therefore, as far as the polarizing element is concerned, it is required to display an achromatic white like high-quality paper when displaying in white, and displaying achromatic black when displaying in black, and the monomer transmittance after correction of visual sensitivity is over 35% and has Polarizing element with high degree of polarization. Although Patent Document 3 describes an achromatic polarizer during white display and black display, further performance improvement can be expected.

Therefore, the object of the present invention is to provide a high-performance achromatic polarizing element that has high transmittance and high degree of polarization, and is achromatic in both white display and black display, and an achromatic polarizing element using the polarizing element. Color polarizer and display device. Another issue is to provide a high-quality white polarizing element for white display.

In order to solve the above-mentioned problems, the inventors of the present inventors have found a polarizing element, which can be manufactured by doping the azo compound of formula (1) and formula (2), which has no wavelength dependence on dichroism and parallel Each of the position and the orthogonal position is achromatic, and has a higher degree of polarization than before. The inventors discovered for the first time that the wavelength-independence in the visible light field can be achieved even with high transmittance, and developed a polarizing element with a higher degree of polarization, which can achieve a white quality like high-quality paper, commonly known as paper white.

That is, the present invention relates to the following, but is not limited to this.

[1] A polarizing element comprising the azo compound represented by formula (1) or its salt, and the azo compound represented by formula (2) or its salt,

In formula (1), Ar ₁ represents a substituted phenyl group or a substituted naphthyl group, Rr ₁ and Rr ₂ each independently represent a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, A sulfo group, a halogen atom, or a C1 to 4 alkoxy group having a sulfo group, and _{at least one of Rr 1} and Rr ₂ represents a group other than the above-mentioned hydrogen atom, and Rr ₃ to Rr ₆ each independently represents a hydrogen atom, C1 to 4 alkyl group, C1 to 4 alkoxy group, or C1 to 4 alkoxy group having a sulfo group, j represents 0 or 1, Xr ₁ represents an amine group that may have a substituent, and an alkoxy group that may have a substituent A phenylamino group, a phenylazo group which may have a substituent, a benzylamino group which may have a substituent, or a benzylamino group which may have a substituent;

In the formula (2), Ag ₁ represents a substituted phenyl group or a substituted naphthyl group, and Bg and Cg are each independently represented by the following formula (3) or formula (4), and either of them is represented by the formula ( 3) As shown, Xg ₁ represents an amino group that may have a substituent, a phenylamino group that may have a substituent, a phenylazo group that may have a substituent, a benzyl group that may have a substituent, or A benzylamino group with substituents;

In formula (3), Rg ₁ represents a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, or a C1 to 4 alkoxy group having a sulfo group, and p ₁ represents an integer of 0 to 2;

In formula (4), Rg ₂ and Rg ₃ each independently represent a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, or a C1 to 4 alkoxy group having a sulfo group.

[2] The polarizing element described in [1] above, wherein Cg in the above formula (2) is represented by the above formula (3).

[3] The polarizing element described in [1] or [2], wherein the azo compound represented by the above formula (2) or a salt thereof is an azo compound represented by the following formula (5) or a salt thereof,

In formula (5), Ag ₂ represents a substituted phenyl group or a substituted naphthyl group, and Rg ₄ and Rg ₅ each independently represent a hydrogen atom, a C1 to 4 alkyl group, an alkoxy group, or a sulfo group The C1 to 4 alkoxy group, Xg ₂ represents an amino group which may have a substituent, a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, and a benzyl group which may have a substituent , Or a benzylamino group which may have a substituent, p ₂ and p ₃ each independently represent an integer of 0 to 2.

[4] The polarizing element as described in [3] above, wherein p ₂ and p ₃ described in the above formula (5) are 1 or 2, respectively.

[5] The polarizing element according to any one of [1] to [4] above, wherein Xr ₁ of the above formula (1) is a phenylamino group which may have a substituent.

[6] The polarizing element according to any one of [1] to [5] above, wherein Xg ₁ described in the above formula (2) is an optionally substituted phenylamino group.

[7] The polarizing element described in any one of [1] to [6] above, which further contains an azo compound represented by the following formula (6) or formula (7) or a salt thereof,

In formula (6), Ay ₆₁ represents a sulfo group, a carboxyl group, a hydroxyl group, a C1 to 4 alkyl group, or a C1 to 4 alkoxy group, and Ry ₆₁ to Ry ₆₄ each independently represents a hydrogen atom, a C1 to 4 alkyl group , C1 to 4 alkoxy group, or C1 to 4 alkoxy group having a sulfo group, k represents an integer of 1 to 3;

In formula (7), Ay ₇₁ and Ay ₇₂ are each independently an optionally substituted naphthyl group or an optionally substituted phenyl group, s and t are each independently an integer of 0 or 1, Ry ₇₁ , Ry ₇₂ , Ry ₇₇ and Ry ₇₈ are each independently a hydrogen atom, a C1 to 4 alkyl group, and a C1 to 4 alkoxy group, Ry ₇₃ to Ry ₇₆ are each independently a hydrogen atom, a C1 to 4 alkyl group, and C1 to 4 The alkoxy group, the C1 to 4 alkoxy group having a sulfo group.

[8] The polarizing element as described in [7] above, which contains the azo compound represented by the formula (7) or a salt thereof, wherein at least any one _{of Ay 71} and Ay _{72 in the above formula (7)} Those include those shown in the following formula (8),

In formula (8), _{any one of Ry 81} and Ry ₈₂ is a sulfo group, a carboxy group, or a C1 to 4 alkoxy group having a sulfo group, and the other is a hydrogen atom, a sulfo group, a carboxy group, or a sulfo group C1 to 4 alkoxy group, C1 to 4 alkyl group, C1 to 4 alkoxy group, halogen atom, nitro group, amino group, amino group substituted by C1 to 4 alkyl group, or C1 to 4 Alkyl-substituted amide group, * in the formula represents the bonding position to the NH site of the terminal amide group of the above formula (7).

[9] The polarizing element as described in [8] above, wherein _{any one of Ry 81} and Ry _{82 in} the above formula (8) is a sulfo group or a carboxyl group, and the other is a hydrogen atom, a sulfo group, a carboxyl group, Methyl, or methoxy.

[10] The polarizing element according to any one of [7] to [9] above, wherein _{at least one of Ay 71} and Ay _{72 in} the above formula (7) is a naphthyl group which may have a substituent .

[11] The polarizing element according to any one of [7] to [10] above, wherein Ay ₇₁ and Ay ₇₂ in the above formula (7) are each independently capable of having a hydroxyl group and a sulfo group. C1 to 4 alkoxy group and naphthyl group as a substituent selected by the group of sulfo groups.

[12] The polarizing element described in any one of [7] to [11] above, wherein Ay ₇₁ and Ay ₇₂ in the above formula (7) are each independently represented by the following formula (9),

In the formula (9), Ry ₉₁ is a hydrogen atom, a hydroxyl group, a C1 to 4 alkoxy group having a sulfo group, or a sulfo group, f is an integer from 1 to 3, and * represents the same as the terminal amide of the above formula (7) The bonding position of the NH site of the base.

[13] The polarizing element as described in [12] above, wherein, in the above formula (9), Ry ₉₁ is a hydrogen atom and f is 2.

[14] The polarizing element as described in any one of [1] to [13] above, wherein the two polarizing elements are superimposed and measured so that the absorption axis directions are parallel to each other, and the wavelengths obtained through measurement pass In the transmittance, the average transmittance from 420nm to 480nm and the average transmittance from 520nm to 590nm The absolute value of the difference in rate is 2.5% or less, and the absolute value of the difference in the average transmittance from 520 nm to 590 nm and the average transmittance from 600 nm to 640 nm is 3.0% or less.

[15] The polarizing element described in any one of [1] to [14] above, wherein a* value and b are obtained when natural light is used to measure transmittance in accordance with JIS Z 8781-4:2013 *The absolute value of the value is:

In the above-mentioned polarizing element alone, it is 1.0 or less (-1.0≦a*-s≦1.0, -1.0≦b-s*≦1.0),

In the state where the above two polarizing elements are arranged so that their respective absorption axis directions are parallel to each other, they are all 2.0 or less (-2.0≦a*-p≦2.0, -2.0≦b*-p≦2.0),

(a*-s represents the a* value of the monomer, b*-s represents the b* value of the monomer, a*-p represents the a* value of the parallel position, and b*-p represents the b* value of the parallel position).

[16] The polarizing element as described in any one of the preceding [1] to [15], wherein the monomer transmittance of the polarizing element after correction of the visual sensitivity is 35% to 45%,

The average transmittance of each wavelength from 520nm to 590nm is 28% to 45% when the two polarizing elements are overlapped and arranged in such a way that their respective absorption axis directions are parallel to each other.

[17] The polarizing element as described in any one of [1] to [16] above, in which the wavelengths obtained when the two polarizing elements are arranged so that the absorption axis directions thereof are orthogonal to each other are superimposed. In the transmittance,

The absolute value of the difference between the average transmittance from 420nm to 480nm and the average transmittance from 520nm to 590nm is 1.0% or less, and the absolute value of the difference between the average transmittance from 520nm to 590nm and the average transmittance from 600nm to 640nm The value is 1.0% or less.

[18] The polarizing element as described in any one of [1] to [17] above, wherein the wavelength bands of 420nm to 480nm, 520nm to 590nm, and 600nm to 640nm are transmitted through orthogonal positions The rate is 1% or less, or the degree of polarization is 97% or more.

[19] The polarizing element described in any one of [1] to [18] above, wherein, in a state where two pieces of polarizing elements are superimposed and arranged such that their respective absorption axis directions are orthogonal to each other, it is based on JIS Z 8781 -4: 2013, when using natural light to measure the transmittance, the absolute values of a* value and b* value are both below 2.0 (-2.0≦a*-c≦2.0, -2.0≦b*-c≦2.0) (a*-c represents the a* value of the orthogonal bit, and b*-c represents the b* of the orthogonal bit).

[20] The polarizing element as described in any one of [1] to [19] above, which further contains a polyvinyl alcohol-based resin film as a base material.

[21] A polarizing plate comprising the polarizing element described in any one of [1] to [20], and a transparent protective layer provided on one or both sides of the polarizing element.

[22] A display device comprising the polarizing element described in any one of [1] to [20] or the polarizing plate described in [21].

The present invention can provide a high-performance achromatic polarizing element that has high transmittance and high degree of polarization, and is achromatic in both white display and black display, and an achromatic polarizing plate and display using the polarizing element Device. In one aspect, the polarizing element and the like of the present invention present high-quality white during white display.

In this specification and the scope of the patent application, the "azo compound or its salt" may be abbreviated as the "azo compound" in some cases, except for cases where the free form is clearly indicated.

In this specification and the scope of the patent application, the "substituent" includes a hydrogen atom for convenience of description. "May have a substituent" also includes the case where it does not have a substituent. For example, "phenyl which may have substituents" includes unsubstituted simple phenyl groups and substituted phenyl groups.

The above-mentioned "C1 to 4 (carbon number 1 to 4) alkyl group" includes, for example, straight-chain alkyl groups such as methyl, ethyl, n-propyl, n-butyl; sec-butyl, tertiary butyl, etc. Branched alkyl groups; unsaturated hydrocarbon groups such as vinyl groups, etc.

Examples of the "C1 to 4 alkoxy group" include methoxy, ethoxy, propoxy, n-butoxy, second butoxy, and tertiary butoxy.

<Polarizing element>

The polarizing element of the present invention includes the azo compound represented by the above formula (1) or the salt thereof, and the azo compound represented by the above formula (2) or the salt thereof. The polarizing element of the present invention may further optionally contain at least one organic dye having a structure other than the aforementioned azo compound. For example, it may further contain the azo compound represented by the above formula (6) or formula (7), preferably containing formula (1), formula (2) and formula (6), or formula (1), formula (2) ) And formula (7).

The above-mentioned polarizing element is preferably used as a base material such as a film obtained by forming a film of a hydrophilic polymer capable of adsorbing a dichroic dye, especially an azo compound. The hydrophilic polymer is not particularly limited, and examples thereof include polyvinyl alcohol-based resins, amylose-based resins, starch-based resins, cellulose-based resins, and polyacrylate-based resins. From the viewpoints of the dyeability, processability, and crosslinkability of the dichroic dye, the hydrophilic polymer is most preferably a polyvinyl alcohol-based resin and its derivatives. A polarizing element can be produced by adsorbing an azo compound or its salt on a substrate and applying alignment treatment such as extension.

The azo compound represented by the above formula (1) will be described.

In formula (1), Ar ₁ represents a substituted phenyl group or a substituted naphthyl group, Rr ₁ and Rr ₂ each independently represent a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, A sulfo group, a halogen atom, or a C1 to 4 alkoxy group having a sulfo group, and _{at least one of Rr 1} and Rr ₂ represents a group other than the aforementioned hydrogen atom. Rr ₃ to Rr ₆ each independently represent a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, or a C1 to 4 alkoxy group having a sulfo group, j represents 0 or 1, and Xr ₁ represents Substituent amino group, optionally substituted phenylamino group, optionally substituted phenylazo group, optionally substituted benzylamino group, or optionally substituted benzylamino group .

The substituted phenyl group or the substituted naphthyl group in _{Ar 1} of the above formula (1) will be described. When Ar ₁ is a substituted phenyl group, it preferably has at least one sulfo group or carboxyl group as its substituent. When the phenyl group has more than two substituents, at least one of the substituents is a sulfo group or a carboxyl group, and the other substituents are preferably a sulfo group, a carboxyl group, a C1 to 4 alkyl group, and a C1 to 4 alkoxy group. , C1 to 4 alkoxy, nitro, benzyl, amine, acetamido, or amine substituted with C1 to 4 alkylamino groups with sulfo groups, other substituents are more preferred Sulfo, methyl, ethyl, methoxy, ethoxy, carboxy, nitro, benzyl, or amino group, particularly preferably sulfo, methyl, methoxy, ethoxy, benzyl An acyl group, or a carboxy group. The above-mentioned C1 to 4 alkoxy group having a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably at the end of the alkoxy group, more preferably 3-sulfopropoxy and 4-sulfobutyl The oxy group is particularly preferably 3-sulfopropoxy. The number of sulfo groups possessed by the phenyl group is preferably 1 or 2, and the substitution position is not particularly limited. When the substitution position of the amide group is the 1-position, it is preferably only the 4-position, the combination of the 2-position and the 4-position, and A combination of 3 and 5 digits.

When Ar ₁ is a naphthyl group having a substituent, the substituent is preferably a C1 to 4 alkoxy group having at least one sulfo group, a hydroxyl group, or a sulfo group, and when it has two or more substituents, these substituents At least one of them is a sulfo group, and other substituents are preferably a sulfo group, a hydroxyl group, a carboxyl group, or a C1 to 4 alkoxy group having a sulfo group. The C1 to 4 alkoxy group having a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably at the end of the alkoxy group, more preferably 3-sulfopropoxy and 4-sulfobutoxy Group, particularly preferably 3-sulfopropoxy. When the number of sulfo groups is 2, and the substitution position of the amido group is 2, the position of the sulfo group on the naphthyl group is preferably a combination of the 4-position and the 8-position, and a combination of the 6-position and the 8-position, and more preferably the 6-position Combination with 8 bits. When the number of sulfo groups of the naphthyl group is 3, the substitution position of the sulfo group is particularly preferably a combination of the 3-position, the 6-position and the 8-position.

The above Rr ₁ and Rr ₂ each independently represent a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, a sulfo group, a halogen atom, or a C1 to 4 alkoxy group having a sulfo group, and Rr _1. At least any one of Rr ₂ represents a group other than the above-mentioned hydrogen atom. Rr ₁ and Rr _{2 are} preferably each independently selected from the group consisting of a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, a sulfo group, and a chlorine atom, and more preferably are selected from a hydrogen atom, A group of methyl and methoxy groups. The above-mentioned C1 to 4 alkoxy group having a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably at the end of the alkoxy group, more preferably 3-sulfopropoxy and 4-sulfobutyl The oxy group is particularly preferably 3-sulfopropoxy. Rr ₁ and Rr ₂ are the above-mentioned groups other than the hydrogen atom, and when the substitution position of the amide group is the 1, the substitution position of Rr ₁ and Rr ₂ can include only the 2-position, only the 3-position, the 2-position and the 5. The combination of position, position 2 and position 6, position 3 and position 5, preferably only 2 position, only 3 position, and particularly preferably substituted at position 2.

The above-mentioned Rr ₃ to Rr ₆ each independently represent a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, or a C1 to 4 alkoxy group having a sulfo group. Rr ₃ to Rr ₆ are each independently preferably a hydrogen atom, a C1 to 4 alkyl group, or a C1 to 4 alkoxy group, and more preferably a hydrogen atom, a methyl group, or a methoxy group. The C1 to 4 alkoxy group having a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably at the end of the alkoxy group, more preferably 3-sulfopropoxy and 4-sulfobutoxy Group, particularly preferably 3-sulfopropoxy. When the substitution position of the azo group on the side of the amide group is the 1, the substitution position can include only the 2 position, only the 3 position, the 2 position and the 5 position, the 2 position and the 6 position, the 3 position and the 5 position, and the 3 position. The combination with 6 digits is preferably a combination of only 2 digits, only 3 digits, 2 digits and 5 digits, 3 digits and 6 digits.

The above j represents 0 or 1. When j is 0, it is easy to control the color. When two polarizing elements are arranged so that their respective absorption axis directions are parallel to each other, when measuring the transmittance using natural light according to JIS Z 8781-4:2013, the a* value and The absolute value of the b* value can be easily adjusted to below 2.0, so it is one of the better ways to adjust the color. When j is 1, it shows a high degree of polarization, so it is one of the better forms for high performance.

The above Xr ₁ represents an amino group which may have a substituent, a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a benzyl group which may have a substituent, or a benzene which may have a substituent Formamide. The amino group which may have a substituent preferably has a group selected from a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, a sulfo group, an amino group, and a C1 to 4 alkylamino group One or two of the substituents of the amino group are more preferably selected from the group consisting of hydrogen atom, methyl, ethyl, methoxy, ethoxy, amino, and C1 to 4 alkylamino groups. An amine group with one or two substituents in the group. The phenylamino group which may have a substituent is preferably composed of a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, a sulfo group, an amino group, and a C1 to 4 alkylamino group The phenylamino group of one or two substituents in the group, more preferably has one or two selected from the group consisting of a hydrogen atom, a methyl group, a methoxy group, a sulfo group, and an amino group One of the substituents is the phenylamino group. The benzyl group which may have a substituent preferably has a benzyl group selected from the group consisting of a hydrogen atom, a hydroxyl group, a sulfo group, an amino group, and a carboxyethylamino group. The benzylamino group which may have a substituent is preferably a benzylamino group having one selected from the group consisting of a hydrogen atom, a hydroxyl group, an amino group, and a carboxyethylamino group. The phenylazo group which may have a substituent preferably has 1 selected from the group consisting of a hydrogen atom, a hydroxyl group, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, an amino group and a carboxyethylamino group To 3 phenylazo groups. Xr _{1 is} preferably an amino group which may have a substituent, a benzylamino group which may have a substituent, and a phenylamino group which may have a substituent, more preferably an amino group which may have a substituent, which may be substituted The phenylamino group of the group. The position of the substituent is not particularly limited. When Xr ₁ is a group having a phenyl group, one of the substituents is particularly preferably carried out at the p-position relative to the bonding position indirectly bonded to the naphthalene skeleton represented by formula (1) When the specific example of substitution is a phenylamino group, it is preferable to have a substituent at the p-position with respect to the amino group.

The method for obtaining the azo compound represented by the above formula (1) includes the methods described in Patent Documents 4 to 6, etc., but it is not limited to these methods.

Further specific examples of the azo compound represented by the above formula (1) and its free acid form are shown below.

Next, the compound represented by the above formula (2) will be explained.

In the above formula (2), Ag ₁ represents a substituted phenyl group or a substituted naphthyl group. When Ag ₁ is a substituted phenyl group, it preferably has at least one sulfo group or carboxyl group as a substituent. When the phenyl group has two or more substituents, it is preferred that at least one of the substituents is a sulfo group or a carboxyl group, and the other substituents are preferably a sulfo group, a carboxyl group, a C1 to 4 alkyl group, and a C1 to 4 group. An alkoxy group, a C1 to 4 alkoxy group having a sulfo group, a nitro group, an amino group, an acetamido group, or an amine group substituted with a C1 to 4 alkylamino group. Other substituents are more preferably sulfo, methyl, ethyl, methoxy, ethoxy, carboxy, nitro, or amino, and particularly preferably sulfo, methyl, methoxy, ethoxy, or carboxyl. The C1 to 4 alkoxy group having a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably at the end of the alkoxy group, more preferably 3-sulfopropoxy and 4-sulfobutoxy Group, particularly preferably 3-sulfopropoxy. The number of substituents of the phenyl group is preferably 1 or 2. The substitution position is not particularly limited. When the position of the azo group is the 1-position, it is preferably only the 4-position, the combination of the 2-position and the 4-position, and the 3. Combination of bit and 5 bit. When Ag ₁ is a naphthyl group having a substituent, it preferably has at least one sulfo group as its substituent. When the naphthyl group has two or more substituents, it is preferable that at least one of the substituents is a sulfo group, a hydroxyl group, a C1 to 4 alkoxy group having a sulfo group, and the other substituents are a sulfo group, a hydroxyl group, and a carboxyl group. , Or a C1 to 4 alkoxy group having a sulfo group. The naphthyl group preferably has two or more sulfo groups as a substituent. The C1 to 4 alkoxy group having a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably at the end of the alkoxy group, more preferably 3-sulfopropoxy and 4-sulfobutoxy Group, particularly preferably 3-sulfopropoxy. When the number of sulfo groups possessed by the naphthyl group is 2, and the position of the azo group is 2, the substitution position of the sulfo group is preferably a combination of the 4-position and the 8-position, and a combination of the 6-position and the 8-position, more preferably It is a combination of 6 and 8 bits. When the number of sulfo groups possessed by the naphthyl group is 3, when the substitution position of the azo group is the 2-position, the substitution position of the sulfo group is preferably a combination of the 3-position, the 6-position and the 8-position.

Bg and Cg in the above-mentioned formula (2) are each independently represented by the above-mentioned formula (3) or the above-mentioned formula (4), but any one of Bg and Cg is represented by the above-mentioned formula (3).

In the above formula (3), Rg ₁ represents a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, or a C1 to 4 alkoxy group having a sulfo group, preferably a hydrogen atom, C1 to 4 The alkyl group or C1 to 4 alkoxy group is more preferably a hydrogen atom, a methyl group, or a methoxy group. It is particularly _{preferable that Rg 1} is a hydrogen atom or a methoxy group. The C1 to 4 alkoxy group having a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably at the end of the alkoxy group, more preferably 3-sulfopropoxy and 4-sulfobutoxy Group, particularly preferably 3-sulfopropoxy. In formula (3), when _{the azo group substituted on the Ag 1} side is the 1-position, _{the substitution position of Rg 1} is preferably the 2-position or the 3-position, and more preferably the 3-position. p ₁ represents an integer from 0 to 2. When there is a sulfo group (p ₁ is 1 or 2), the substitution position of the sulfo group is preferably 6-position or 7-position, more preferably 6-position.

In the above formula (4), Rg ₂ and Rg ₃ each independently represent a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, or a C1 to 4 alkoxy group having a sulfo group, preferably Hydrogen atom, C1 to 4 alkyl group, C1 to 4 alkoxy group, or C1 to 4 alkoxy group having sulfo group, more preferably hydrogen atom, methyl group, methoxy group, 3-sulfopropoxy group Group, or 4-sulfopropoxy. _{When the azo group substituted on the Ag 1} side in the above formula (2) is the 1 position, _{the substitution position of Rg 2} or Rg ₃ applies only to 2 positions, only 5 positions, 2 and 5 positions, 3 and 5 positions, A combination of 2 and 6 digits, or 3 and 6 digits, preferably only 2 digits, only 5 digits, 2 digits and 5 digits. In addition, only the 2nd position and only the 5th position means that only the 2 or 5 position has a substituent other than one hydrogen atom.

_{Xg 1} in the above formula (2) represents an amino group which may have a substituent, a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a benzyl group which may have a substituent, or It may have a substituted benzylamino group. Xg _{1 is} preferably an amino group which may have a substituent or a phenylamino group which may have a substituent, and more preferably a phenylamino group which may have a substituent. The amino group which may have a substituent preferably has one or two selected from the group consisting of a hydrogen atom, a methyl group, a methoxy group, a sulfo group, an amino group, and a C1 to 4 alkylamino group The amino group is more preferably an amino group having one or two hydrogen atoms, a methyl group, or a sulfo group. The phenylamino group which may have a substituent is preferably composed of a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, a sulfo group, an amino group, and a C1 to 4 alkylamino group The phenylamino group of one or two substituents in the group, more preferably has one or two selected from the group consisting of a hydrogen atom, a methyl group, a methoxy group, a sulfo group, and an amino group The substituent is the phenylamino group. The phenylazo group preferably has 1 to 3 selected from the group consisting of a hydrogen atom, a hydroxyl group, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, an amino group, a hydroxyl group, and a carboxyethylamino group The phenylazo group. The benzyl group which may have a substituent is preferably a benzyl group having one substituent selected from the group consisting of a hydrogen atom, a hydroxyl group, an amino group, and a carboxyethylamino group. The benzylamino group which may have a substituent is preferably a benzylamino group having one substituent selected from the group consisting of a hydrogen atom, a hydroxyl group, an amino group, and a carboxyethylamino group. The position of the substituent is not particularly limited. When Xg ₁ is a group having a phenyl group, it is particularly preferred that one of the substituents is located at the p-position relative to the bonding position indirectly bonded to the naphthalene skeleton represented by formula (2) In the case of a phenylamino group, it is preferable that the substituent is located at the p-position relative to the amino group.

When the azo compound represented by the above formula (2) or the salt thereof is the azo compound represented by the above formula (5) or the salt thereof, the performance can be particularly improved, so it is preferred.

In the above formula (5), Ag ₂ represents the same as _{Ag 1} in the formula (2). Rg ₄ and Rg ₅ each independently represent the same as _{Rg 1} in formula (3). Xg ₂ represents the same as _{Xg 1} in formula (2). p ₂ and p ₃ each independently represent the same as _{p 1} in formula (2). In particular _{, it is preferable that p 2} and p ₃ are independently 1 or 2 to improve the polarization characteristics.

In the above-mentioned polarizing element, the content of the azo compound represented by the above formula (2) or its salt is preferably 0.01 to 5000 parts by mass relative to 100 parts by mass of the content of the azo compound of the above formula (1) Parts, more preferably 0.1 to 3000 parts by mass, still more preferably 10 to 1000 parts by mass, and still more preferably 40 to 400 parts by mass.

The azo compound represented by the above formula (2) or a salt thereof can be synthesized by methods described in Patent Document 7 to Patent Document 12, etc., but is not limited to these.

Specific examples of the azo compound represented by the above formula (2) include, for example: CIDirect Blue 34, CIDirect Blue 69, CIDirect Blue 70, CIDirect Blue 71, CIDirect Blue 72, CIDirect Blue 75, CIDirect Blue 78, CIDirect Blue 81, CIDirect Blue 82, CIDirect Blue 83, CIDirect Blue 186, CIDirect Blue 258, Benzo Fast Chrome BlueFG (CI34225), BenzoFastBlueBN (CI34120), CIDirectGreen51 and other azo compounds.

Hereinafter, specific examples of the azo compound represented by the above formula (2) are shown in free acid form.

The above-mentioned polarizing element is combined and contains the azo compound represented by the above-mentioned formula (1) and the above-mentioned formula (2), thereby having higher contrast, high transmittance and high degree of polarization than conventional achromatic polarizers, and , Achromatic color can be realized in both white display and black display. In one aspect, the white display can display the white color of high-quality paper, commonly known as paper white. In one aspect, an achromatic black can be realized when black is displayed, especially a clear black with a high sense of quality.

In order to further improve performance, the above-mentioned polarizing element preferably further contains an azo compound represented by formula (6) or formula (7) in addition to the azo compound represented by formula (1) and formula (2).

The azo compound represented by the above formula (6) or formula (7) particularly affects the transmittance of 400 to 500 nm. In the polarizing element, the transmittance and polarization (contrast) at the short wavelength side of 400 to 500 nm will affect the blueness of black during black display, or the yellowing of white during white display. The azo compound represented by formula (6) or formula (7) can suppress the short in the parallel position of the polarizing element The transmittance of the wavelength side is reduced, and the polarization characteristic (dichroism) of 400 to 500 nm is improved, which can further reduce the yellowness of white display and the blueness of black display. That is, the polarizing element further contains the azo compound represented by formula (6) or formula (7), so that the monomer transmittance after correction of the visual sensitivity is in the range of 35 to 66%. It means achromaticity. It displays white like high-quality paper when displaying in white, and further improves the degree of polarization, and displaying achromatic black when displaying in black, so it is better.

The above formula (6) is explained. In the above formula (6), Ay ₆₁ is a sulfo group, a carboxyl group, a hydroxyl group, a C1 to 4 alkyl group, or a C1 to 4 alkoxy group, preferably a sulfo group or a carboxyl group. Ry ₆₁ to Ry ₆₄ are each independently a hydrogen atom, a sulfo group, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, a C1 to 4 alkoxy group having a sulfo group, preferably a hydrogen atom, a sulfo group , C1 to 4 alkyl group, C1 to 4 alkoxy group, more preferably hydrogen atom, methyl group, methoxy group. k represents an integer from 1 to 3.

In the above-mentioned polarizing element, the content of the azo compound represented by the above formula (6) or its salt is preferably 0.01 to 300 parts by mass, more preferably 0.1 to 200 parts by mass relative to 100 parts by mass of the azo compound content of formula (1) Parts by mass, more preferably 30 to 200 parts by mass.

The azo compound represented by the formula (6) or a salt thereof can be synthesized, for example, by the method described in WO2007/138980, etc., or commercially available products can also be obtained. Specific examples of the azo compound represented by formula (6) include CIDirect Yellow 4, CIDirect Yellow 12, CIDirect Yellow 72, and CIDirect Orange 39, and the azo having a stilbene structure described in WO2007/138980. Compounds, etc., but are not limited to them.

Further specific examples of the azo compound represented by formula (6) include the following. In addition, compound examples are shown in free acid form.

Next, the azo compound represented by formula (7) will be explained.

In formula (7), Ay ₇₁ and Ay ₇₂ are each independently an optionally substituted naphthyl group or an optionally substituted phenyl group, s and t are each independently 0 or 1, Ry ₇₁ , Ry ₇₂ , Ry ₇₇ and Ry ₇₈ are each independently a hydrogen atom, a C1 to 4 alkyl group, and a C1 to 4 alkoxy group, and Ry ₇₃ to Ry ₇₆ are each independently a hydrogen atom, a C1 to 4 alkyl group, and a C1 to 4 alkyl group. An oxy group, a C1 to 4 alkoxy group having a sulfo group. In order to improve the polarization characteristics, either s or t is preferably 1.

The phenyl group which may have a substituent preferably has a C1 to 4 alkoxy group selected from a sulfo group, a carboxy group, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, a halo group, and a nitro group having a sulfo group. A phenyl group of one or more substituents in the group consisting of an amine group, an amine group substituted with a C1 to 4 alkyl group, and an acylamino group substituted with a C1 to 4 alkyl group. When the phenyl group has two or more substituents, it is preferred that at least one of the substituents is a sulfo group, or a carboxyl group, or a C1-4 alkoxy group having a sulfo group, and the other substituents are a sulfo group, a hydrogen atom, C1 to 4 alkyl group, C1 to 4 alkoxy group, C1 to 4 alkoxy group with sulfo group, carboxyl group, chlorine group, bromine group, nitro group, amino group, substituted by C1 to 4 alkyl group An amino group or an acylamino group substituted with a C1 to 4 alkyl group. Other substituents are more preferably sulfo group, hydrogen atom, methyl, ethyl, methoxy, ethoxy, carboxy, sulfoethoxy, sulfopropoxy, sulfobutoxy, chloro, nitro The group or the amino group is particularly preferably a sulfo group, a carboxyl 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 it is preferably only 2-position, only 4-position, combination of 2-position and 6-position, combination of 2-position and 4-position, combination of 3-position and 5-position, Particularly preferred are only 2-position, only 4-position, a combination of 2-position and 4-position, or a combination of 3-position and 5-position. Also, only the 2-position and only the 4-position means that there is only a substituent other than one hydrogen atom at the 2-position or the 4-position

Among Ay ₇₁ or Ay ₇₂ , the optionally substituted phenyl group is preferably represented by the following formula (8). The * in the following formula (8) represents the bonding position to the NH site of the terminal amine group of the above formula (7).

In formula (8), one of Ry ₈₁ and Ry ₈₂ is a sulfo group, a carboxy group, or a C1 to 4 alkoxy group having a sulfo group, and the other is a hydrogen atom, a sulfo group, a carboxy group, or a C1 having a sulfo group Alkoxy group to 4, C1 to 4 alkyl group, C1 to 4 alkoxy group, halo, nitro group, amino group, amino group substituted by C1 to 4 alkyl group, or C1 to 4 alkyl group A substituted acylamino group. Preferably, one of Ry ₈₁ and Ry ₈₂ is a sulfo group or a carboxyl group, and the other is a hydrogen atom, a sulfo group, a carboxyl group, a methyl group, or a methoxy group.

In Ay ₇₁ or Ay ₇₂ , the naphthyl group which may have a substituent is preferably naphthalene which may have one or more substituents selected from the group consisting of a hydroxyl group, a C1 to 4 alkoxy group having a sulfo group, and a sulfo group base.

In Ay ₇₁ or Ay ₇₂ , the naphthyl group which may have a substituent is preferably a naphthyl group represented by the following formula (9). The * in the following formula (9) represents the bonding position to the NH site of the terminal amine group of the above formula (7).

In the formula (9), Ry ₉₁ is a hydrogen atom, a hydroxyl group, a C1 to 4 alkoxy group having a sulfo group, or a sulfo group. f is an integer from 1 to 3. The position of the sulfo group may exist in any benzene nucleus of the naphthalene ring. Preferably, Ry ₉₁ is a hydrogen atom and f is 2. The C1 to 4 alkoxy group having a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably the alkoxy terminal. The C1 to 4 alkoxy group having a sulfo group is more preferably 3-sulfopropoxy and 4-sulfobutoxy. The position of the substituent of the naphthyl group is not particularly limited. When the substitution position of the azo group is set to 2 and the number of substituents is 2, it is preferably 4-position and 8-position, 5-position and 7-position, Or a combination of 6-position and 8-position. When there are 3 substituents, 3-position, 5-position and 7-position; 3-position, 6-position and 8-position are preferred.

In formula (7), Ry ₇₁ , Ry ₇₂ , Ry ₇₇ , and Ry ₇₈ are each independently a hydrogen atom, a C1 to 4 alkoxy group, and a C1 to 4 alkyl group. Preferably, it is a hydrogen atom, a methyl group, an ethyl group, a methoxy group, and an ethoxy group.

In formula (7), Ry ₇₃ to Ry ₇₆ are each independently a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, and a C1 to 4 alkoxy group having a sulfo group. Ry ₇₃ to Ry ₇₆ are each independently preferably a hydrogen atom, methyl, ethyl, methoxy, ethoxy, 3-sulfopropoxy, or 4-sulfobutoxy, and more preferably hydrogen Atom, methyl, ethyl, methoxy, or 3-sulfopropoxy. The positions of Ry ₇₃ to Ry ₇₆ are preferably only 2-position, only 5-position, combination of 2-position and 6-position, combination of 2-position and 5-position, combination of 3-position and 5-position, More preferably, it is a combination of only 2-position, only 5-position, 2-position and 5-position. In addition, only the 2-position and only the 5-position means that only the 2-position or the 5-position has a substituent other than one hydrogen atom.

The azo compound represented by formula (7) is preferably represented by the following formula (10). In addition, Ay ₇₁ , Ay ₇₂ , Ry ₇₁ to Ry ₇₈ , s, and t represent the same as those described in formula (7).

Next, specific examples of the azo compound represented by formula (7) are given below. In addition, the sulfo group, carboxyl group and hydroxyl group in the formula are expressed in free acid form.

The azo compound represented by the above formula (7) or its salt can be diazotized and coupled according to the general azo dye preparation method described in Non-Patent Document 2, or can be diazotized and coupled as described in Patent Document 13 by combining with The urea-based agent is produced by reaction.

An example of a specific manufacturing method can be performed by the same method as in Patent Document 13 by reacting an aromatic amine represented by the following formula (A), which may have a substituent, with a chlorine represented by the following formula (B), and then performing a reduction reaction , And the aminobenzylanilines represented by the following formula (C) are obtained.

In the formula (A), Ay ₇₁ represents the same as in the above formula (7). In the formula (B), Ry ₇₁ and Ry ₇₂ represent the same as those in the above formula (7). In the formula (C), Ay ₇₁ , Ry ₇₁ and Ry ₇₂ represent the same as those in the above formula (7).

Next, in the same manner as in Non-Patent Document 2, the substituted aminobenzylanilines represented by the above formula (C) are diazotized and coupled with the anilines of the following formula (D) to obtain the following The monoazoamino compound represented by formula (E).

In the formula (D), Ry ₇₃ and Ry ₇₄ represent the same as those in the above formula (7). In the formula (E), Ay ₇₁ and Ry ₇₁ to Ry ₇₄ represent the same as those in the above formula (7).

Next, in the same manner as in Patent Document 1, the aromatic amines represented by the following formula (F), which may have a substituent, are reacted with the chlorine represented by the following formula (G), and then the reduction reaction is performed to obtain the following formula (H) The aminobenzylanilines shown in (H).

In the formula (F), Ay ₇₂ represents the same as in the above formula (7). In the formula (G), Ry ₇₇ and Ry ₇₈ represent the same as those in the above formula (7). In the formula (H), Ay ₇₂ , Ry ₇₇ and Ry ₇₈ represent the same as those in the above formula (7).

Next, in the same manner as in Non-Patent Document 2, the substituted aminobenzylanilines represented by the above formula (H) are diazotized and coupled with the anilines of the following formula (I) to obtain the following The monoazoamino compound represented by formula (J).

In the above formula (I), Ry ₇₅ and Ry ₇₆ represent the same as those in the above formula (7). In the formula (J), Ay ₇₂ and Ry ₇₅ to Ry ₇₈ represent the same as those in the above formula (7).

In order to obtain the azo compound of the above formula (7) in which both s and t are 1, the above monoazoamine compound (E) and the above monoazoamine compound (J) are combined with chloroformic acid which is a urea-based agent The phenyl ester is reacted, thereby obtaining the azo compound of the above formula (7). In order to obtain the azo compound of the above formula (7) in which s is 1 and t is 0, the aromatic amines represented by the following formula (K), which may have substituents, are diazotized in the same manner as in Non-Patent Document 2. , Coupled with the aniline of the above formula (I), to obtain the monoazoamino compound represented by the following formula (L).

In the formula (K), Ay ₇₂ represents the same as in the above formula (7). In the formula (L), Ay ₇₂ , Ry ₇₅ and Ry ₇₆ represent the same as those in the above formula (7).

Next, the monoazoamine compound (E) and the monoazoamine compound (L) are reacted with phenyl chloroformate of the ureidolating agent, thereby obtaining the azo compound of formula (7).

In order to obtain the azo compound of the above formula (7) in which s is 0 and t is 1, in the same way as in Non-Patent Document 2, the aromatic amines represented by the following formula (M) which may have substituents are diazotized , Coupled with the aniline of the above formula (D), to obtain the monoazoamine compound represented by the following formula (N).

In the formula, Ay ₇₁ represents the same as in the above formula (7). In the formula (N), Ay ₇₁ , Ry ₇₃ , and Ry ₇₄ represent the same as those in the above formula (7).

Next, the monoazoamine compound (J) and the monoazoamine compound (N) are reacted with phenyl chloroformate of the ureidolation agent, thereby obtaining the azo compound of formula (7).

The diazotization step is based on the positive method of mixing diazonium components in hydrochloric acid, sulfuric acid and other mineral acid aqueous solutions or suspensions, mixed with sodium nitrite and other nitrites, or in neutral or weakly alkaline aqueous solutions of diazonium components In the reverse method of adding nitrite first and then mixing with mineral acid. The diazotization temperature is more appropriately -10 to 40°C. In addition, the step of coupling with anilines is preferably to mix acidic aqueous solutions such as hydrochloric acid, acetic acid, and the above-mentioned diazonium liquids, and perform the acidic conditions at a temperature of -10 to 40° C. and a pH of 2 to 7.

The monoazoamine compound (E), the monoazoamine compound (J), the monoazoamine compound (L), and the monoazoamine compound (N) obtained by coupling are obtained by acid precipitation Or it can be precipitated by salting out and taken out by filtration, or it can be directly used as a solution or suspension for the subsequent steps. When the diazonium salt is poorly soluble and becomes a suspension, it can also be filtered and made into a pressed cake for subsequent coupling steps.

The specific conditions of the ureidolation reaction using phenyl chloroformate are based on the preparation method shown on page 57 of Patent Document 13. The temperature is preferably 10 to 90°C, pH 3 to 11, and more preferably 20 to 80°C. , PH 4 to 10, particularly preferably 20 to 70 ℃, pH 6 to 9. In addition to phenyl chloroformate, urea-based agents can use phosgene, triphosgene, ethyl chloroformate, butyl chloroformate, isobutyl chloroformate, 4-nitrophenyl chloroformate, 4-fluorophenyl chloroformate , 4-chlorophenyl chloroformate, 4-bromophenyl chloroformate, diphenyl carbonate, bis(2-methoxyphenyl) carbonate, bis(pentafluorophenyl) carbonate, bis(4- Nitrophenyl) ester and 1,1'-carbonyldiimidazole, but are not limited to these. The urea-based agent is preferably phenyl chloroformate, 4-nitrophenyl chloroformate, 4-chlorophenyl chloroformate, diphenyl carbonate, bis(4-nitrophenyl) carbonate, more preferably chlorine Phenyl formate, 4-nitrophenyl chloroformate.

After the urea reaction is completed, the resulting azo compound of formula (7) is precipitated by salting out and filtered out. When refining is necessary, the salting-out can be repeated or the organic solvent can be used to precipitate from the water. Examples of the organic solvent used in the purification include water-soluble organic solvents such as alcohols such as methanol and ethanol, and ketones such as acetone.

_{The aromatic amines represented by Ay 71} -NH ₂ and Ay ₇₂ -NH ₂ used to synthesize the azo compound represented by formula (7) are naphthyl amines or anilines.

As the naphthylamines, it is preferable to use one or more naphthylamines selected from the group consisting of a hydrogen atom, a hydroxyl group, a C1 to 4 alkoxy group having a sulfo group, and a sulfo group. Examples of naphthylamines include: 4-aminonaphthalenesulfonic acid, 7-aminonaphthalene-3-sulfonic acid, 1-aminonaphthalene-6-sulfonic acid, 1-aminonaphthalene-7-sulfonic acid Acid, 7-aminonaphthalene-1,3-disulfonic acid, 6-aminonaphthalene-1,3-disulfonic acid, 7-aminonaphthalene-1,5-disulfonic acid, 7-aminonaphthalene- 1,3,6-trisulfonic acid and so on. Preferably they are 7-aminonaphthalene-3-sulfonic acid, 6-aminonaphthalene-1,3-disulfonic acid, 7-aminonaphthalene-1,4-disulfonic acid, 7-aminonaphthalene-1, 5-disulfonic acid, 2-amino-8-hydroxy-naphthalene-6-sulfonic acid, 3-amino-8-hydroxynaphthalene-6-sulfonic acid, 1-aminonaphthalene-3,6,8-tris Sulfonic acid, 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid, 1-aminonaphthalene-3,8-disulfonic acid, etc.

Examples of naphthylamines with sulfo groups and C1 to 4 alkoxy groups containing sulfo groups include: 7-amino-3-(3-sulfopropoxy)naphthalene-1-sulfonic acid, 7-amine 3-(4-sulfobutoxy)naphthalene-1-sulfonic acid, 7-amino-4-(3-sulfopropoxy)naphthalene-2-sulfonic acid, 7-amino-4- (4-Sulfobutoxy)naphthalene-2-sulfonic acid, 6-amino-4-(3-sulfopropoxy)naphthalene-2-sulfonic acid, 6-amino-4-(4-sulfonic acid Butoxy) naphthalene-2-sulfonic acid, 2-amino-5-(3-sulfopropoxy) naphthalene-1,7-disulfonic acid, 6-amino-4-(3-sulfo Propoxy)naphthalene-2,7-disulfonic acid, 7-amino-3-(3-sulfopropoxy)naphthalene-1,5-disulfonic acid, etc.

Anilines include: 4-aminobenzenesulfonic acid, 3-aminobenzenesulfonic acid, 2-aminobenzenesulfonic acid, 4-aminobenzoic acid, 2-amino-5-methylbenzenesulfonic acid, 2-Amino-5-ethylbenzenesulfonic acid, 2-amino-5-propylbenzenesulfonic acid, 2-amino-5-butylbenzenesulfonic acid, 4-amino-3-methylbenzenesulfonic acid Acid, 4-amino-3-ethylbenzenesulfonic acid, 4-amino-3-propylbenzenesulfonic acid, 4-amino-3-butylbenzenesulfonic acid, 2-amino-5-methoxy Benzenesulfonic acid, 2-amino-5-ethoxybenzenesulfonic acid, 2-amino-5-propoxybenzenesulfonic acid, 2-amino-5-butoxybenzenesulfonic acid, 4-amine 3-methoxybenzenesulfonic acid, 4-amino-3-ethoxybenzenesulfonic acid, 4-amino-3-propoxybenzenesulfonic acid, 4-amino-3-butoxybenzene Sulfonic acid, 2-amino-4-sulfobenzoic acid, 2-amino-5-sulfobenzoic acid, 4-amino-3-sulfobenzoic acid, 5-amino-2-chlorobenzoic acid, 5-aminoisophthalic acid, 2-amino-5-chlorobenzenesulfonic acid, 2-amino-5-bromobenzenesulfonic acid, 2-amino-5-nitrobenzenesulfonic acid, 2,5- Diaminobenzenesulfonic acid, 2-amino-5-dimethylaminobenzenesulfonic acid, 2-amino-5-diethylaminobenzenesulfonic acid, 5-acetamide-2-aminobenzenesulfonic acid , 4-aminobenzene-1,3-disulfonic acid, 2-aminobenzene-1,4-disulfonic acid Acid, 4-amino-2-methylbenzenesulfonic acid, 2-(4-aminophenoxy)ethane-1-sulfonic acid, 3-(4-aminophenoxy)propane-1-sulfonic acid Acid, 4-(4-aminophenoxy)butane-1-sulfonic acid, 2-(3-aminophenoxy)ethane-1-sulfonic acid, 3-(3-aminophenoxy) ) Propane-1-sulfonic acid, 4-(3-aminophenoxy)butane-1-sulfonic acid, 2-amino-5-(2-sulfoethoxy)benzenesulfonic acid, 2-amine 5-(3-sulfopropoxy)benzenesulfonic acid, 2-amino-5-(4-sulfobutoxy)benzenesulfonic acid, 2-amino-5-(2-sulfoethyl Oxy)benzoic acid, 2-amino-5-(3-sulfopropoxy)benzoic acid, 2-amino-5-(4-sulfobutoxy)benzoic acid, 4-amino-3 -(2-sulfoethoxy)benzenesulfonic acid, 4-amino-3-(3-sulfopropoxy)benzenesulfonic acid, 4-amino-3-(4-sulfobutoxy) Benzenesulfonic acid, 4-amino-3-(2-sulfoethoxy)benzoic acid, 4-amino-3-(3-sulfopropoxy)benzoic acid, 4-amino-3-( 4-sulfobutoxy) benzoic acid, 2-(4-amino-3-methylphenoxy)ethane-1-sulfonic acid, 3-(4-amino-3-methylphenoxy) ) Propane-1-sulfonic acid, 4-(4-amino-3-methylphenoxy)butane-1-sulfonic acid, 2-(4-amino-3-ethylphenoxy)ethane -1-sulfonic acid, 3-(4-amino-3-ethylphenoxy)propane-1-sulfonic acid, 4-(4-amino-3-ethylphenoxy)butane-1- Sulfonic acid, 2-(4-amino-3-propylphenoxy)ethane-1-sulfonic acid, 3-(4-amino-3-propylphenoxy)propane-1-sulfonic acid, 4-(4-amino-3-propylphenoxy)butane-1-sulfonic acid, 2-(4-amino-3-butylphenoxy)ethane-1-sulfonic acid, 3- (4-Amino-3-butylphenoxy)propane-1-sulfonic acid, 4-(4-amino-3-butylphenoxy)butane-1-sulfonic acid, 2-(4- Amino-3-methoxyphenoxy)ethane-1-sulfonic acid, 3-(4-amino-3-methoxyphenoxy)propane-1-sulfonic acid, 4-(4-amine 3-methoxyphenoxy)butane-1-sulfonic acid, 2-(4-amino-3-ethoxyphenoxy)ethane-1-sulfonic acid, 3-(4-amine 3-ethoxyphenoxy) propane-1-sulfonic acid, 4-(4-amino-3-ethoxyphenoxy)butane-1-sulfonic acid, 2-(4-amino -3-Propoxyphenoxy)ethane-1-sulfonic acid, 3-(4-amino-3-propoxyphenoxy)propane-1-sulfonic acid, 4-(4-amino- 3-propoxyphenoxy)butane-1-sulfonic acid, 2-(4-amino-3-butoxyphenoxy)ethane-1-sulfonic acid, 3-(4-amino- 3-butoxyphenoxy) Propan-1-sulfonic acid, 4-(4-amino-3-butoxyphenoxy)butane-1-sulfonic acid, etc. The amine groups of these aromatic amines may be protected. The protecting group can be exemplified by ω-methylsulfonyl.

Aromatic amines (D) and (I) belonging to primary coupling agents include aniline, 2-methylaniline, 2-ethylaniline, 2-propylaniline, 2-butylaniline, and 3-methylaniline. Aniline, 3-ethylaniline, 3-propylaniline, 3-butylaniline, 2,5-dimethylaniline, 2,5-diethylaniline, 2-methoxyaniline, 2-ethoxy Aniline, 2-propoxyaniline, 2-butoxyaniline, 3-methoxyaniline, 3-ethoxyaniline, 3-propoxyaniline, 3-butoxyaniline, 2-methoxyaniline -5-methylaniline, 2,5-dimethoxyaniline, 3,5-dimethylaniline, 2,6-dimethylaniline, 3,5-dimethoxyaniline, 3-(2- Amino-4-methylphenoxy)propane-1-sulfonic acid, 3-(2-aminophenoxy)propane-1-sulfonic acid, 4-(2-amino-4-methylphenoxy) Yl)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)propane-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-sulfonic 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)propane-1-sulfonic acid, 4-(3- Amino-4-ethoxyphenoxy)butane-1-sulfonic acid, 2-(3-amino-4-ethoxyphenoxy)ethane-1-sulfonic acid, etc. The amine groups of these aromatic amines may be protected. The protecting group can be exemplified by ω-methylsulfonyl.

The chlorine (B) and (G) include: 4-nitrobenzyl chloride, 3-methyl-4-nitrobenzyl chloride, 2-methyl-4-nitrobenzyl chloride, 3-ethyl-4-nitrobenzyl chloride, 2-ethyl-4-nitrobenzyl chloride, 3-propyl-4-nitrobenzyl chloride, 2-propyl-4-nitro Benzyl chloride, 3-butyl-4-nitro benzyl chloride, 2-butyl-4-nitro benzyl chloride, 3-methoxy-4-nitro benzyl chloride, 3 -Ethoxy-4-nitrobenzyl chloride, 3-propoxy-4-nitrobenzyl chloride, 3-butoxy-4-nitrobenzyl chloride, 2-methoxy- 4-nitrobenzyl chloride, 2-ethoxy-4-nitrobenzyl chloride, 2-propoxy-4-nitrobenzyl chloride, 2-butoxy-4-nitrobenzene Formaldehyde chloride and so on.

In the above-mentioned polarizing element, the content of the azo compound represented by the above formula (7) or its salt is preferably 0.01 to 300 parts by mass, more preferably 0.1 to 200 parts by mass relative to 100 parts by mass of the azo compound content of formula (1) Parts by mass, more preferably 30 to 200 parts by mass.

The azo compound represented by the above formula (1), formula (2), formula (6), or formula (7) may be in a free form or in a salt form, respectively. The salt may be, for example, an alkali metal salt such as a lithium salt, a sodium salt, and a potassium salt; or an organic salt such as an ammonium salt or an alkylamine salt. The salt is preferably a sodium salt.

The above-mentioned polarizing element contains the azo compound represented by the formula (1) and the formula (2), and may further contain any one or more organic dyes having a structure other than the aforementioned azo compound. For example, it may further contain an azo compound represented by formula (6) or formula (7). The above-mentioned polarizing element may have properties such as the a* value and b* value of the chromaticity in the preferred range described later, the monomer transmittance after the visual sensitivity correction, and the average transmittance in a specific wavelength band. For example, the transmittance of a single polarizing element may be fixed in the transmittance of each wavelength. In addition, the transmittance can be fixed in the parallel position of each wavelength, that is, in the parallel position hue when the absorption axes of the two polarizing elements are parallel, achromatic color can be provided. In addition, the transmittance of each wavelength can be fixed in the orthogonal position at the same time, that is, in the hue of the orthogonal position when the absorption axes of the two polarizing elements are orthogonal, an achromatic hue can be provided. In this regard, the polarizing element in this case is based on Organic dyes containing formula (1) and formula (2), and any other structure, such as the azo compound represented by formula (6) or (7), can not only provide high transmittance and high contrast, that is, , Polarizing elements with high polarization degree, and polarizing elements with achromatic hue are also provided.

The blending ratio of the azo compound in the polarizing element is preferably adjusted in the content of each azo compound so that the transmittance and chromaticity fall into the preferable range described later. The performance of the polarizing element is not only changed by the blending ratio of the azo compounds in the polarizing element, but also due to the swelling or extension ratio of the substrate that adsorbs the azo compound, dyeing time, dyeing temperature, pH, salt during dyeing The influence of various factors such as the change. Therefore, the blending ratio of each azo compound can be determined according to the swelling degree of the substrate, the temperature, time, pH, salt type, salt concentration, and extension ratio of the substrate.

(Permeability after correction of visual sensitivity)

The above-mentioned transmittance after correction of visual sensitivity is obtained according to JIS Z 8722:2009, which is corrected to the transmittance of human visual sensitivity. The measurement system of the transmittance of each wavelength used for correction can be obtained by the following method: For the measurement sample (for example, a polarizing element or a polarizing plate), use a C light source (2 degree field of view) and be in the range of 400 to 700 nm For each wavelength, the spectral transmittance is measured at every 5nm or 10nm and corrected to visual sensitivity according to JIS Z 8722:2009. The transmittance after the correction of the visual sensitivity includes: the transmittance of the monomer after the correction of the visual sensitivity of the polarizing element or the polarizing plate when the monomer is measured; when using 2 pieces of the polarizing element or the polarizing plate and making the absorption axes parallel Transmittance, corrected to the visual sensitivity when the visual sensitivity is corrected, and the parallel bit transmittance after correction; and, when two polarizing elements or polarizing plates are used and the transmittance when the absorption axes are orthogonal to each other, the transmittance is corrected to the visual sensitivity of the visual sensitivity. Orthogonal bit penetration rate after correction.

(H-1) The difference of the average transmittance of the 2 wavelength bands

The above-mentioned polarizing element preferably has a difference in average transmittance between specific wavelength bands that is equal to or less than a specific value. The average transmittance is the average value of the transmittance of each wavelength in a specific wavelength band.

The wavelength bands of 420nm to 480nm, 520nm to 590nm, and 600nm to 640nm are the main wavelength bands of the isochromatic function used in the calculation when displaying colors in accordance with JIS Z 8781-4:2013. Specifically, among the color functions such as XYZ of JIS Z 8701, which is the basis of JIS Z 8781-4:2013, x(λ) with 600nm as the maximum value, y(λ) with 550nm as the maximum value, and 455nm When the respective maximum value of z(λ), which is the maximum value, is set to 100, the respective wavelength bands of 420nm to 480nm, 520nm to 590nm, and 600nm to 640nm that are values above 20 are displayed.

Regarding the state where the two polarizing elements are stacked so that the absorption axis directions become parallel (during bright display or white display), the transmittance measured at each wavelength is also called the "parallel transmittance of each wavelength"". In addition, the average transmittance of each wavelength from ○nm to △nm is also referred to as "AT _○-△ ". About parallel bits of each of the wavelength of the polarizing element of the present invention, the transmittance, the absolute value of the difference between the AT _420-480 and preferred _AT 520-590 2.5% or less, more preferably 1.8% or less, and more preferably 1.5% Below, 1.0% or less is particularly preferred. Further, on the parallel position transmittance of each wavelength, an absolute value of the difference between the _AT 520-590 and preferred AT _600-640 3.0% or less, more preferably 2.0% or less, and more preferably 1.5% or less, particularly preferably It is 1.0% or less. Such a polarizing element can display the white color of high-quality paper in parallel position.

Regarding the superimposed arrangement of two polarizing elements such that the absorption axis directions are orthogonal (during black display or dark display), the transmittance measured at each wavelength is also called the "orthogonal position of each wavelength". Penetration rate". On Orthogonal transmittance of each wavelength position of the polarizing element of the present invention, preferably the absolute value of the difference between the AT _{420-480 AT} 520-590 1.0% or less, and _AT 520-590 of the AT _600-640 The absolute value of the difference is 1.0% or less. Such a polarizing element can display achromatic black at orthogonal positions. And, an orthogonal position on the transmittance of each wavelength, an absolute value of the difference between the AT _420-480 and preferred _AT 520-590 0.6% or less, more preferably 0.3% or less, and more preferably 0.1% or less. On Orthogonal transmittance bits, the absolute value of the difference between the _AT 520-590 and preferred AT _600-640 1.0% or less, more preferably 0.6% or less, and more preferably 0.3% or less, particularly preferably 0.1%.

In addition, the average transmittance of the monomer transmittance, the parallel position transmittance, and the orthogonal position transmittance in the wavelength bands of 380nm to 420nm, 480nm to 520nm, and 640nm to 780nm are used to make When the average transmittance in the above-mentioned wavelength bands of 420 nm to 480 nm, 520 nm to 590 nm, and 600 nm to 640 nm is adjusted as described above, although it has little effect on the hue of the polarizing element, it is preferably adjusted to a certain degree. Monomer on the transmittance of each wavelength, AT _380-420 and preferably _420-480 difference AT is 15% or less, AT _480-520 and preferably _420-480 difference AT is 15% or less, AT _480-520 and AT is the difference between _520-590 preferably 15% or _less, AT 640-780 and _600-640 difference AT is preferably 20% or less.

(H-2) The value of single penetration rate after correction of visual sensitivity

The above-mentioned polarizing element preferably has a monomer transmittance of 35% to 66% after the visual sensitivity is corrected. The single transmittance after the correction of the visual sensitivity is the transmittance of the visual sensitivity based on JIS Z 8722:2009 for one measurement sample (for example, a polarizing element or a polarizing plate). As far as the performance of the polarizing plate is concerned, higher transmittance is required. If the single transmittance rate after the correction of the visual sensitivity is 35% to 60%, even if it is used in a display device, it can show a sense of brightness without violation. The higher the transmittance, the lower the polarization. Therefore, from the viewpoint of the balance of polarization, the monomer transmittance after correction of visual sensitivity is preferably 37% to 50%, and more preferably 35% to 35%. 45%. If the single penetration rate after correction of visual sensitivity exceeds 65%, there will be When the degree of polarization is reduced, but the bright transmittance of the polarizing element, or the specific polarization performance or contrast is required, the monomer transmittance after the correction of the visual sensitivity can exceed 65%.

(H-3) Average transmittance in a specific wavelength band

The polarizing element is preferably 25% to 50% _{of AT 520-590 measured at the parallel position.} When such a polarizing element is installed in a display device, it can become a bright, high-brightness and clear display device. The transmittance of the wavelength band from 520nm to 590nm is based on one of the main wavelength bands of the isochromatic function used in the calculation of color display in JIS Z 8781-4:2013. In particular, the wavelength bands from 520 nm to 590 nm are the wavelength bands with the highest visual sensitivity based on the isochromatic function, and the transmittance in this range is close to the transmittance that can be confirmed visually. Therefore, it is very important to adjust the transmittance of the wavelength band from 520nm to 590nm. _{The AT 520-590} measured in the parallel position is more preferably 28% to 45%, and more preferably 30% to 40%. Moreover, the degree of polarization of the polarizing element at this time can be 80% to 100%, preferably 90% to 100%, more preferably 97% to 100%, still more preferably 99% or more, particularly preferably 99.5% or more . The degree of polarization is preferably the higher one, but in the relationship between the degree of polarization and the transmittance, the transmittance and the degree of polarization can be adjusted according to the importance of lightness or the degree of polarization (or contrast).

(Chromaticity a* value and b* value)

The chromaticity a* value and b* value are the values obtained by JIS Z 8781-4:2013 during the measurement of natural light transmittance. The object color display method specified in JIS Z 8781-4:2013 is equivalent to the object color display method specified by the International Commission on Illumination (abbreviation: CIE). The measurement of the chromaticity a* value and b* value is performed by irradiating a measurement sample (for example, a polarizing element or a polarizing plate) with natural light. In addition, in the following, the a* value and b* value obtained for one measurement sample are expressed as a*-s and b*-s, and the two measurement samples are arranged in such a state that their absorption axis directions are parallel to each other ( In white display) the obtained chromaticity a* value and b* value are expressed as a*-p and b*-p, so that the two measurement samples are squared by their absorption axis The chromaticity a* value and b* value obtained in the state of being arranged orthogonally to each other (during black display) are expressed as a*-c and b*-c.

In the above-mentioned polarizing element, the absolute values of a*-s and b*-s are each preferably 1.0 or less, and the absolute values of a*-p and b*-p are each preferably 2.0 or less. Such a polarizing element is a neutral color alone, and can display high-quality white in white display. The absolute value of a*-p and b*-p of the polarizing element is more preferably 1.5 or less, and still more preferably 1.0 or less. In addition, in the polarizing element, the absolute values of a*-c and b*-c are each preferably 2.0 or less, and more preferably 1.0 or less. Such a polarizing element can display achromatic black when displaying black. Even if the difference between the absolute value of the chromaticity a* value and b* value is only 0.5, people can feel the color difference, and people may feel the color difference. Therefore, it is very important to control the same value in the polarizing element. In particular, when the absolute values of a*-p, b*-p, a*-c, and b*-c are each less than 1.0, it is possible to obtain white during white display and almost no black during black display. Good polarizers of other colors. It can be realized that the parallel position is achromatic, that is, the white of high-quality paper, and the orthogonal position has the achromatic, high-quality and clear black. However, the effect of the black hue imparted to the display device is not limited to this. Originally in a non-light (dark) state, even if it has a hue, it will be regarded as black. Therefore, when the degree of polarization is high, that is, when the cross bit transmittance is low, the polarizing element can impart black color even if the absolute values of a*-c and b*-c are not 2.0 or less, respectively. As a result of the inventor’s review, it was found that when the orthogonal position transmittance in the wavelength bands of 420nm to 480nm, 520nm to 590nm, and 600nm to 640nm is 1% or less or the polarization degree is about 97% or more, there is no Regarding the absolute values of a*-c and b*-c, it can give a visual black, so it is better. In the wavelength bands of 420nm to 480nm, 520nm to 590nm, and 600nm to 640nm, the orthogonal transmittance of each wavelength is 0.6% or less, or the polarization degree is 98% or more, which can give a sense of sight The upper black is better, and the orthogonal transmittance of each wavelength is less than 0.3% or the polarization degree is more than 99%.

From the above, it can be seen that when two polarizing elements are arranged in such a way that the absorption axis directions are perpendicular to each other, a better way to impart a black hue can be achieved by satisfying any one of the following 1) to 3).

1) Regarding the transmittance of each wavelength measured when the two polarizing elements are superimposed so that the absorption axis directions are orthogonal to each other (during black display or dark display) (hereinafter, also referred to as the "orthogonal" of each wavelength bit transmittance "), absolute value of difference AT AT _420-480 and _520-590 of 1.0% or less, and the difference AT AT _520-590 and _600-640 of the absolute value of 1.0% or less;

2) The absolute values of a*-c and b*-c are respectively below 2.0;

3) In the wavelength bands of 420 nm to 480 nm, 520 nm to 590 nm, and 600 nm to 640 nm, the orthogonal transmittance is 1% or less or the polarization degree is about 97% or more.

The polarizing element of the present invention has high contrast and high transmittance, and has achromaticity and high degree of polarization in a single unit. Moreover, in one aspect, the polarizing element of the present invention can be expressed as white (paper white) of high-quality paper in white display, and can express achromatic black in black display, especially clear black with high-grade sense. So far, there has not been such a polarizing element with both high transmittance and achromaticity. Furthermore, the polarizing element of the present invention has high durability, especially durability against high temperature and high humidity.

In addition, compared to commonly used iodine-based polarizers or Patent Document 3, the polarizing element of the present invention absorbs less light with a wavelength of 700 nm or more, so it has the advantage of less heat generation even if it is irradiated with light such as sunlight. For example, when a liquid crystal display is used outdoors, solar light is irradiated on the liquid crystal display, and as a result, the polarizing element is also irradiated. Sunlight also has wavelengths above 700nm Light, including near-infrared rays with heating effect. For example, a polarizing element using the azo compound described in Example 3 of Japanese Patent Publication No. 02-061988, which absorbs near-infrared light with a wavelength around 700 nm, generates heat slightly. However, the polarizing element of the present invention Near-infrared absorption is very small, so even when exposed to sunlight outdoors, it generates less heat. The polarizing element of the present invention is excellent in terms of less heat generation and therefore less deterioration.

<Making method of polarizing element>

Hereinafter, a case where an azo compound is adsorbed on a polyvinyl alcohol-based resin base material and manufactured is taken as an example to describe a specific manufacturing method of a polarizing element. In addition, the manufacturing method of the polarizing element of the present invention is not limited to the following manufacturing method.

(Preparation of raw film)

The raw material film can be produced by film-forming a polyvinyl alcohol-based resin. The polyvinyl alcohol-based resin is not particularly limited, and a commercially available product 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 a polyvinyl acetate-based resin. In addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, polyvinyl acetate resins may also include copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. The degree of saponification of the polyvinyl alcohol-based resin is generally preferably about 85 to 100 mol%, and more preferably 95 mol% or more. The polyvinyl alcohol-based resin may be further modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may also be used. In addition, the degree of polymerization of the polyvinyl alcohol-based resin is the average degree of polymerization of the viscosity, which can be obtained by a method known in the technical field, and is usually preferably about 1,000 to 10,000, and more preferably about 1,500 to 6,000.

The film forming method of the said polyvinyl alcohol-type resin is not specifically limited, A well-known method can be used for film forming. In this case, the polyvinyl alcohol-based resin film may contain glycerin, ethylene glycol, propylene glycol, low molecular weight polyethylene glycol, etc. as a plasticizer. The amount of the plasticizer is preferably 5 to 20% by mass in the total amount of the film, more preferably 8 to 15% by mass. The film thickness of the raw material film is not particularly limited. For example, it is about 5 μm to 150 μm, preferably about 10 μm to 100 μm.

(Swelling step)

The swelling treatment is performed on the raw film obtained by the above. The swelling treatment is preferably performed by immersing the raw material film in a swelling solution at 0 to 50°C for 30 seconds to 10 minutes. The swelling liquid is preferably water. The stretching magnification is preferably adjusted to 1.00 to 1.50 times, and more preferably adjusted to 1.10 to 1.35 times. In the case of shortening the time for manufacturing the polarizing element, the swelling treatment for swelling the raw material film may be omitted during the dyeing treatment described later.

(Dyeing step)

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 simultaneously in the dyeing step. The treatment of adsorption and impregnation with azo compound is a step of coloring the resin film, so it is regarded as a dyeing step.

The azo compound used in the dyeing step is a mixture of the azo compound represented by formula (1) and formula (2) or its salt. The azo compound represented by formula (6) or formula (7) or a salt thereof can be further used arbitrarily. Furthermore, the azo compound of the dichroic dye exemplified in Non-Patent Document 1 and the like can be arbitrarily used to adjust the color without impairing the performance of the polarizing element of the present application. In addition to using these azo compounds in the form of free acids, the salts of the compounds can also be used. Examples of such salts include alkali metal salts such as lithium salt, sodium salt, and potassium salt, or organic salts such as ammonium salt or alkylamine salt, and sodium salt is preferred.

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

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

In addition to azo compounds, the dyeing solution can also contain dyeing auxiliary agents as needed. Examples of dyeing auxiliary agents include sodium carbonate, sodium bicarbonate, sodium chloride, sodium sulfate, anhydrous sodium sulfate, and sodium tripolyphosphate. The content of the dyeing auxiliary agent can be adjusted in any concentration according to the time and temperature of the dyeability of the dye, but the respective content in the dyeing solution is preferably 0.01 to 5% by mass, more preferably 0.1 to 2% by mass.

(Washing step 1)

After the dyeing step, a washing step (hereinafter, also referred to as "washing step 1") can be performed before proceeding to the subsequent steps. Dyeing step 1 is a step of washing the dyeing solution attached to the surface of the resin film in the dyeing step. By performing the washing step 1, it is possible to prevent the dye from being transferred to the liquid for subsequent treatment. In washing step 1, water is generally used as a washing liquid. The washing method is preferably immersed in a washing liquid, but it may be washed by applying the washing liquid to the 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 solution in the cleaning step 1 must be a temperature that does not dissolve the material constituting the resin film (for example, a hydrophilic polymer, here is a polyvinyl alcohol-based resin). The washing treatment is generally carried out at 5 to 40°C. However, even if there is no cleaning step 1, there will be no problem in performance, so the cleaning step can be omitted.

(Steps containing crosslinking agent and/or water resistant agent)

The dyeing step or the washing step 1 may be followed by a step containing a crosslinking agent and/or a water resistance agent. The method for making the resin film contain a crosslinking agent and/or a water-resistant agent is preferably immersing in a treatment solution, and the treatment solution may be applied or applied to the resin film. The treatment solution contains at least one crosslinking agent and/or water resistance 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 processing time of this step is preferably 30 seconds to 6 minutes, more preferably 1 to 5 minutes.

As the crosslinking agent, for example, boron compounds such as boric acid, borax, or ammonium borate; polyaldehydes such as glyoxal or glutaraldehyde; polyisocyanate compounds such as biuret type, isocyanurate type, or block type; Titanium-based compounds such as titanyl sulfate, etc., and other ethylene glycol glycidyl ether, polyamide epichlorohydrin, etc. can be used. Water resistance agents include: peroxysuccinic acid, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerol diglycidyl ether, ammonium chloride, or magnesium chloride, etc. , It is preferable to use boric acid. The solvent for the crosslinking agent and/or water resistance agent is preferably water, but it is not limited thereto. The concentration of the crosslinking agent and/or water resistance agent can be appropriately determined by those skilled in the art according to the type. However, taking boric acid as an example, the concentration in the treatment solution is preferably 0.1 to 6.0% by mass. More preferably, it is 1.0 to 4.0% by mass. However, it is not necessary to contain a cross-linking agent and/or a water-resistant agent, and this treatment step can be omitted when it is desired to recover for a short time or when the cross-linking treatment or water-resistant treatment is not required.

(Extension step)

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

In 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 perform the stretching treatment while being immersed in a solution containing at least one kind of crosslinking agent and/or water resistance agent. The cross-linking agent and the water-resistant agent can be the same as those described in the step of containing the cross-linking agent and/or the water-resistant agent. The concentration in the solution of the crosslinking agent and/or water resistance agent in the extension step is, for example, preferably 0.5 to 15% by mass, more preferably 2.0 to 8.0% by mass. The extension temperature is preferably 40 to 60°C, more preferably 45 to 58°C. The extension time is usually 30 seconds to 20 minutes, more preferably 2 to 5 minutes. The wet stretching step may be performed in one stage, or may be performed by multiple stages of stretching in two or more stages.

In 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 preferably in an environment with a humidity of 20 to 95% RH. The heating method includes, for example, an inter-roll zone stretching method, a roll heating stretching method, a pressure stretching method, and an infrared heating stretching method, and the stretching method is not limited. The extension step may be performed in one stage, or may be performed in a multi-stage extension of more than two stages.

(Washing step 2)

After the stretching step, the crosslinking agent and/or water-resistant agent are deposited on the surface of the resin film, or foreign matter is attached, so the cleaning step of cleaning the surface of the resin film can be performed (hereinafter, also referred to as "cleaning step 2" ). The washing time is preferably 1 second to 5 minutes. The cleaning method is preferably to immerse the resin film in a cleaning solution, but it can also be cleaned by coating the resin film or a coating solution. The washing liquid is preferably water. The washing treatment can be carried out in one stage, or in a multi-stage treatment of two or more stages. The temperature of the solution in the washing step is not particularly limited, and is usually 5 to 50°C, preferably 10 to 40°C.

In addition to water, the treatment liquid or its solvent used in the treatment steps so far may include, for example, dimethyl sulfoxide, N-methylpyrrolidone, methanol, ethanol, propanol, isopropanol, glycerin, Alcohols such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol or trimethylolpropane; amines such as ethylenediamine and diethylenetriamine, but not limited to these Wait. The treatment liquid or its solvent is preferably water. In addition, these treatment liquids or their solvents may be used singly, or a mixture of two or more kinds may be used.

(Drying step)

After the stretching step or the washing step 2, a drying step of the resin film is performed. Drying treatment can be carried out by natural drying, but in order to further improve drying efficiency, it can be carried out by roller compression, air knife or suction roller, etc. to remove surface moisture, etc., and/or air drying. get on. The drying treatment temperature is preferably 20 to 100°C for drying treatment, more preferably 60 to 100°C for drying treatment. The drying treatment time is, for example, 30 seconds to 20 minutes, preferably 5 to 10 minutes.

In the manufacturing method of the polarizing element, it is preferable to adjust the swelling degree of the substrate in the swelling step and the swelling degree of the substrate in the dyeing step so that the polarizing element satisfies at least one of the following conditions (i) to (v) The mixing ratio of the nitrogen compound, the temperature and pH of the dyeing solution, the type or concentration of salts such as sodium chloride or mirabilite, sodium tripolyphosphate, and the dyeing time, and the extension ratio in the extension step are more preferable to further satisfy The conditions of (vi) and (vii) shall be adjusted.

(i) bits on parallel transmittance, and the absolute value of difference AT _{420-480 AT} 520-590 becomes 2.5 or less, the absolute value of difference _AT 520-590 AT _600-640 becomes 2.0 or less.

(ii) about orthogonal bit penetration, and the absolute value of difference AT _{420-480 AT} 520-590 becomes 1.0 or less, the absolute value of difference _AT 520-590 AT _600-640 becomes 1.0 or less.

(iii) The monomer penetration rate after correction of visual sensitivity becomes 28% to 45%.

(iv) The absolute values of the a* value and the b* value are 1.0 or less for the polarizing element alone, and 2.0 or less for the parallel position.

(v) The absolute values of the a* value and the b* value measured by the quadrature position each become 2 or less.

(vi) Regarding the parallel bit transmittance of each wavelength, AT _520-590 becomes 25 to 35%.

bit orthogonal transmittance (vii) a monomer or transmittance of each wavelength of each wavelength, the difference between the AT _420-480 AT _380-420 becomes 15% or less, and the difference AT _480-520 of the AT _420-480 becomes 15% or less, a difference AT AT _480-520 and _520-590 to become 15% or less, and / or be a difference AT and AT _{600-640 640-780} 20% or less.

By the above method, a polarizing element containing at least a combination of azo compounds represented by formula (1) and formula (2), or any combination of azo compounds represented by formula (6) or formula (7) can be manufactured . The polarizing element has higher transmittance and high degree of polarization than the conventional polarizing element, and the monomer has a neutral color (neutral gray) hue. In one aspect, when two polarizing elements are arranged so that the absorption axis directions are parallel, the white color can be displayed as high-quality paper. Furthermore, in one aspect, when two polarizing elements are stacked so that the absorption axis directions are orthogonal to each other, the polarizing element displays high-quality achromatic black. In addition, the polarizing element has high durability against high temperature and high humidity.

<Polarizer>

The polarizing plate of the present invention is provided with a polarizing element and a transparent protective layer arranged on one or both sides of the polarizing element. The transparent protective layer is provided for the purpose of improving the water resistance or handling properties of the polarizing element.

The above-mentioned transparent protective layer is a protective film formed using a transparent material. The protective film is a film having a layer shape that can maintain the shape of the polarizing element, and is preferably a plastic with excellent transparency, mechanical strength, thermal stability, and moisture shielding properties. The same layer can be set by forming the same layer And other functions. As an example of the plastic constituting the protective film, there are polyester resins, acetate resins, polyether resins, polycarbonate resins, polyamide resins, polyimide resins, and polyolefins. Thermoplastic resins such as acrylic resins and acrylic resins; films made of thermosetting resins such as acrylic, urethane, urethane acrylate, epoxy, and silicone, or ultraviolet curable resins, etc. Among others, the polyolefin-based resin can be exemplified by an amorphous polyolefin-based resin and a resin having a norbornene-based monomer or a cyclic polyolefin polymerized unit such as a polycyclic norbornene-based monomer. Generally speaking, it is better to choose a protective film that does not hinder the performance of the polarizing element after the protective film is laminated. Such a protective film is particularly preferably cellulose triacetate (TAC) and norbornene formed from a cellulose acetate resin. . In addition, the protective film may be subjected to hard coating treatment, anti-reflection treatment, treatment for the purpose of preventing adhesion or diffusion, anti-glare, etc., within a range that does not impair the effects of the present invention. The thickness of the transparent protective layer is generally preferably 10 to 200 μm.

The above-mentioned polarizing plate preferably further includes an adhesive layer for bonding the transparent protective layer and the polarizing element between the transparent protective layer and the polarizing element. The adhesive constituting the adhesive layer is not particularly limited. Examples include polyvinyl alcohol-based adhesives, urethane emulsion-based adhesives, acrylic-based adhesives, and polyester isocyanate-based adhesives, and polyvinyl alcohol-based adhesives are preferred. Examples of polyvinyl alcohol-based adhesives include GOHSENOL NH-26 (manufactured by Nippon Gosei Co., Ltd.) and EXCEVAL RS-2117 (manufactured by Kuraray Co., Ltd.), but are not limited to these. A crosslinking agent and/or a water resistance agent can be added to the adhesive. The polyvinyl alcohol-based adhesive is preferably a maleic anhydride/isobutylene copolymer, and an adhesive mixed with a crosslinking agent can be used as required. Examples of the maleic anhydride/isobutylene copolymer include ISOBAM #18 (manufactured by Kuraray), ISOBAM #04 (manufactured by Kuraray), ammonia-modified ISOBAM #104 (manufactured by Kuraray), and ammonia-modified ISOBAM #110 ( Kuraray Corporation), imidization ISOBAM #304 (Kuraray Corporation Manufactured by Kuraray), and imidized ISOBAM #310 (manufactured by Kuraray). In this case, the crosslinking agent can be a water-soluble multi-epoxy compound. Examples of the water-soluble polyvalent epoxy compound include Denacol EX-521 (manufactured by Nagasechemtex) and TETRAD-C (manufactured by Mitsui Gas Chemical Co., Ltd.). In addition, known adhesives such as urethane-based, acrylic-based, and epoxy-based adhesives can be used as adhesives other than polyvinyl alcohol-based resins. Particularly preferred is the use of polyvinyl alcohol modified with an acetyl acetone group, and as the crosslinking agent, it is preferred to use polyhydric aldehydes. In addition, for the purpose of enhancing the adhesive strength of the adhesive or enhancing the water resistance, additives such as zinc compounds, chlorides, and iodides can be contained individually or at a concentration of about 0.1 to 10% by mass. The additives of the adhering agent are not particularly limited, and can be appropriately selected by those having ordinary knowledge in the relevant technical field. After bonding the transparent protective layer and the polarizing element with the adhesive, the polarizing plate can be obtained by drying or heat treatment at an appropriate temperature.

Polarizing elements or polarizing plates are based on the situation. For example, when they are attached to display devices such as liquid crystal or organic electroluminescence (commonly known as OLED or OEL), they can also be used as a non-exposed protective layer or film surface to improve Various functional layers for viewing angle and/or contrast improvement, and layers or films with brightness enhancement properties. Various functional layers are, for example, layers or films that control phase difference. The polarizing plate is preferably attached to the films or the display device by a pressure-sensitive adhesive.

The polarizing element or the polarizing plate may be provided with various known functional layers such as an AR layer (anti-reflection layer), an anti-glare layer, and a hard coat layer on the exposed surface of the transparent protective layer or film. The coating method is preferably used to prepare the layer with various functions, but it is also possible to bond a film with the function through an adhesive or an adhesive.

The above-mentioned hard coat layer may be, for example, an acrylic or polysiloxane-based hard coat layer or a urethane-based protective layer. In addition, the above-mentioned AR layer can be expected to further improve the light penetration of the veneer. Transmittance. The AR layer can be formed by, for example, silicon dioxide, titanium oxide, or the like by evaporation or sputtering, or can be formed by thinly coating a fluorine-based substance.

The polarizing element or the polarizing plate is based on the situation, for example, when it is attached to a display device such as liquid crystal, organic electroluminescence (commonly known as OLED or OEL), it can later become a non-exposed transparent protective layer or film surface to improve the viewing angle And/or various functional layers to improve contrast, and layers or films with brightness enhancement properties. Various functional layers are, for example, a layer or film that controls phase difference (hereinafter, also referred to as "phase difference plate"). The polarizing plate of the present invention can be used as an elliptical polarizing plate by bonding the retardation plate. The polarizing plate is preferably attached to the films or the display device by an adhesive.

The polarizing plate of the present invention can have high transmittance and high degree of polarization, and can realize achromaticity. In one aspect, the white display can display white as high-quality paper, and the black display can display neutral black. In one aspect, the polarizing plate of the present invention has high durability.

<Display device>

The polarizing element or polarizing plate of the present invention can be provided with a protective layer or a functional layer and a transparent support such as glass, crystal, sapphire, etc. according to needs, and is suitable for LCD projectors, computers, watches, notebook computers, word processors, and LCD TVs. , Polarized lenses, polarized glasses, car navigation, and indoor and outdoor measuring instruments or displays, etc.

In particular, the polarizing element or polarizing plate of the present invention is not only suitable for liquid crystal display devices, such as reflective liquid crystal display devices, semi-transmissive liquid crystal display devices, and liquid crystal display devices, but also suitable for organic electroluminescence. In one aspect, the liquid crystal display device using the polarizing element or polarizing plate of the present invention can display white and neutral black such as high-quality paper. In one aspect, the liquid crystal display device is a liquid crystal display device with high durability, high reliability, high contrast for a long time, and high color reproducibility.

(Example)

Hereinafter, the present invention will be described in further detail with examples, but the present invention is not limited to these. The% in the examples is a quality standard unless otherwise specified.

[Example 1]

A polyvinyl alcohol film (VF-PS#7500 manufactured by Kuraray Corporation) having a saponification degree of 99% or more and an average degree of polymerization of 2400 was immersed in warm water at 45°C for 2 minutes, and subjected to swelling treatment, and the extension ratio was 1.30 times. At 45°C containing 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous Glauber's salt, compound example 1-5 0.16 parts by mass, compound example 2-12 0.30 parts by mass, and compound example 6-1 0.27 parts by mass The dyeing solution is immersed for 6 minutes and 00 seconds so that the film contains an azo compound. The obtained film was immersed in a 40°C aqueous solution containing 20 g/l of boric acid (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) for 1 minute. The film after the immersion was stretched to 5.0 times while being stretched for 5 minutes in a 50°C aqueous solution containing 30.0 g/l of boric acid. The resulting film was immersed in water at 25°C for 20 seconds while maintaining its tension, thereby performing a washing treatment. The cleaned film was dried at 70°C for 9 minutes to obtain a polarizing element. For this polarizing element, 4% polyvinyl alcohol (NH-26 manufactured by JAPAN VAM & POVAL) is used as an adhesive, and an alkali-treated cellulose triacetate film (ZRD-60 manufactured by FUJIFILM) is laminated, and Obtain a polarizing plate. The obtained polarizing plate maintains the optical properties of the above-mentioned polarizing element, in particular, the monomer transmittance of each wavelength, the parallel transmittance of each wavelength, the orthogonal transmittance of each wavelength, the hue, and the degree of polarization. Wait. This polarizing plate was used as the measurement sample of Example 1.

[Example 2]

Except that the swollen film contains 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous Glauber's salt, 0.16 parts by mass of compound example 1-4, and 0.30 part by mass of compound example 2-12. Part, Compound Example 6-1 0.27 parts by mass of the 45°C dyeing solution was treated for 6 minutes to contain an azo compound, and the rest was performed in the same manner as in Example 1 to produce a polarizing plate.

[Example 3]

Except that the swollen film contains 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous Glauber's salt, 0.21 parts by mass of compound example 1-24, 0.29 parts by mass of compound example 2-12, and compound example 6-1 A 0.26 part by mass of the 45°C dyeing solution was treated for 6 minutes to contain an azo compound, and the rest was applied in the same manner as in Example 1 to produce a polarizing plate.

[Example 4]

Except that the swollen film contains 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous Glauber's salt, 0.13 parts by mass of compound examples 1-4, 0.35 parts by mass of compound examples 2-22, and compound example 6 -1 0.24 parts by mass of the 45°C dyeing solution was treated for 6 minutes and 45 seconds to contain an azo compound, and the rest was performed in the same manner as in Example 1 to produce a polarizing plate.

[Example 5]

Except that the swollen film contains 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous Glauber's salt, 0.15 parts by mass of compound example 1-4, 0.42 parts by mass of compound example 2-3, and compound example 6-1 0.25 parts by mass of the 45°C dyeing solution was treated for 6 minutes and 45 seconds to contain the azo compound, and the rest was performed in the same manner as in Example 1 to produce a polarizing plate.

[Example 6]

Except that the swollen film contains 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous Glauber's salt, 0.16 parts by mass of compound example 1-4, 0.37 parts by mass of compound example 2-4, and compound example 6-1 0.27 parts by mass of the 45°C dyeing solution was treated for 6 minutes and 30 seconds to contain an azo compound, and the rest was performed in the same manner as in Example 1 to produce a polarizing plate.

[Example 7]

Except that the swollen film contains 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous Glauber's salt, 0.17 parts by mass of compound example 1-4, 0.33 parts by mass of compound example 2-12, and compound example 7-84 0.28 parts by mass of the 45°C dyeing solution was treated for 6 minutes and 30 seconds to contain an azo compound, and the rest was performed in the same manner as in Example 1 to produce a polarizing plate.

[Example 8]

Except that the swollen film contains 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous Glauber's salt, 0.17 parts by mass of compound example 1-24, 0.33 parts by mass of compound example 2-12, and compound example 7-84. 0.26 parts by mass of the 45°C dyeing solution was treated for 6 minutes and 30 seconds to contain an azo compound, and the rest was performed in the same manner as in Example 1 to produce a polarizing plate.

[Example 9]

Except that the swollen film contains 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous Glauber's salt, 0.15 parts by mass of compound example 1-9, 0.31 parts by mass of compound example 2-9, and compound example 7-84. 0.30 parts by mass of the 45°C dyeing solution was treated for 6 minutes and 30 seconds to contain an azo compound, and the rest was performed in the same manner as in Example 1 to produce a polarizing plate.

[Example 10]

Except that the swollen film contains 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous Glauber's salt, the following compound examples 1-25, 0.17 parts by mass, and compound example 2- as the compound of formula (1) 12 0.32 parts by mass and 0.26 parts by mass of compound example 7-84 were treated with a 45°C dyeing solution for 6 minutes and 30 seconds to contain an azo compound. The rest was performed in the same manner as in Example 1 to produce a polarizing plate.

[Example 11]

Except that the swollen film contains 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous Glauber's salt, 0.16 parts by mass of compound example 1-8, 0.35 parts by mass of compound example 2-15, and compound example 6-2 0.30 parts by mass of the 45°C dyeing solution was treated for 6 minutes and 30 seconds to contain an azo compound, and the rest was performed in the same manner as in Example 1 to produce a polarizing plate.

[Comparative Example 1]

The high-transmittance dye-based polarizing plate SHC-115 made by Polatechno, which has a neutral gray color, was used as a general dye-based polarizing plate and used as a measurement sample.

[Comparative Example 2]

The dye-based polarizer SHC-128 manufactured by Polatechno, which is a neutral gray with high contrast, is used as a general dye-based polarizer and used as a measurement sample.

[Comparative Examples 3 to 8]

According to the preparation method of Comparative Example 1 in Patent Document 14, the iodine content time is 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 it was 3 minutes and 30 seconds, in Comparative Example 7 it was 4 minutes and 00 seconds, and in Comparative Example 8 it was 5 minutes and 15 seconds, and an iodine-based polarizing plate was produced, that is, a polarized light that does not contain an azo compound. Plate, and used as a measurement sample.

[Comparative Example 9]

Start with the iodine-based polarizer SKW-18245P made by Polatechno, which displays paper white in the parallel position, and use it as a measurement sample.

[Comparative Examples 10 and 11]

Except that the aqueous solution (dyeing solution) containing only the azo compound in Example 1 has the same composition as Example 1 of Patent Document 3, and the respective dyeing times are 6 minutes (Comparative Example 10) and 5 minutes (Comparative Example 11) Other than that, the rest was performed in the same manner as in Example 1 of the present case, and the time for the swollen film to be immersed in the aqueous solution was adjusted so that the penetration rate was almost the same as that of Example 1, and the azo compound was contained in the film. Polarizing plates of Comparative Examples 10 and 11.

[Comparative Example 12]

Except that in Example 1, instead of Compound Examples 1-5, the dyeing solution contains the azo compound described in Synthesis Example 1 of Patent Document 15 in the same amount, and the azo compound is included, and the rest is the same as in Example 1. Make a polarizing plate by applying it.

[Comparative Example 13]

Except that in Example 1, instead of Compound Examples 1-5, C.I. Direct Red 4BH was contained in the same amount in the dyeing solution, and the azo compound was contained, the procedure was carried out in the same manner as in Example 1 to produce a polarizing plate.

[Comparative Example 14]

Except that in Example 5, instead of Compound Example 1-4, the dyeing solution contained formula (11) in the same amount to contain an azo compound, the same procedure was carried out as in Example 5 to produce a polarizing plate.

[Comparative Example 15]

The polarizing plate was produced as in Example 1 of Patent Document 16 on the dye-based polarizing plate.

[Comparative Example 16]

The polarizing plate was produced as in Example 3 of Patent Document 17 on the dye-based polarizing plate.

[Comparative Example 17]

The polarizing plate was produced as in Example 1 of Patent Document 18 on the dye-based polarizing plate.

[Comparative Example 18]

The polarizing plate was produced as in Example 15 No. 1 of Patent Document 19 on the dye-based polarizing plate.

[Comparative Example 19]

In addition to substituting compound examples 1-5 in Example 1, 0.98 parts by mass of CIDirect Red 80, which is an azo compound of the same color and has a urea-based skeleton, is used. The transmittance of each wavelength at the orthogonal position is almost constant and its Except for adjusting the color to be black, it was performed in the same manner as in Example 1 to produce a polarizing plate.

[Comparative Example 20]

In addition to substituting compound examples 2-3 in Example 5, 0.45 parts by mass of CIDirect Blue 6, which is an azo compound of the same color and having a skeleton of dichroic dianisidine, is used to penetrate at each wavelength in the orthogonal position. Except for the point that the rate was almost constant and the color was designed to be black, it was performed in the same manner as in Example 1 to produce a polarizing plate.

[assessment method]

The evaluation of the measurement samples obtained in Examples 1 to 11 and Comparative Examples 1 to 20 was performed as follows.

(a) The monomer transmittance Ts of each wavelength, the parallel transmittance Tp of each wavelength, and the orthogonal transmittance Tc of each wavelength

A spectrophotometer ("U-4100" manufactured by Hitachi, Ltd.) was used to measure the monomer transmittance Ts, parallel position transmittance Tp, and orthogonal position transmittance Tc of each wavelength of each measurement sample. Here, the monomer transmittance Ts of each wavelength is the transmittance of each wavelength when one measurement sample is measured. The parallel transmittance Tp of each wavelength is the spectral transmittance of each wavelength measured by superimposing two measurement samples so that the absorption axis directions are parallel. The orthogonal transmittance Tc of each wavelength is the spectral transmittance measured by superimposing two polarizers so that their absorption axes are orthogonal. The measurement is performed at a wavelength of 400 to 700 nm. The parallel position transmittance Tp and the orthogonal position transmittance Tc obtained from the measurement results are the average value of each wavelength in the range of 420 to 480nm, the average value of each wavelength in the range of 520 to 590nm, and the average value of each wavelength in the range of 600 The average value of each wavelength up to 640 nm is shown in Table 1.

(b) 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

Obtain the individual penetration rate Ys (%) after the correction of the visual sensitivity, the parallel position penetration rate Yp (%) after the correction of the visual sensitivity, and the orthogonal position penetration rate Yc after the correction of the visual sensitivity of each measurement sample. (%). The single penetration rate Ys(%) after the visual sensitivity correction, the parallel position penetration rate Yp(%) after the visual sensitivity correction, and the orthogonal position penetration rate Yc(%) after the visual sensitivity correction are respectively for the The wavelength range of 400 to 700nm, each predetermined wavelength interval dλ (here, 5nm) is calculated for the above monomer transmittance Ts of each wavelength, the parallel transmittance Tp of each wavelength, and the orthogonality of each wavelength The bit transmittance Tc is corrected to the transmittance of visual sensitivity according to JIS Z 8722:2009. Specifically, the monomer transmittance Ts of each wavelength, the parallel transmittance Tp of each wavelength, and the orthogonal transmittance Tc of each wavelength are divided into Do not substitute into the following formulas (V to VII) and calculate. In addition, in the following formulas (V to VII), Pλ represents the spectral distribution of standard light (C light source), and yλ represents a color function such as a 2-degree field of view. The results are shown in Table 1.

(c) Comparison

Calculate the ratio (Yp/Yc) of the parallel transmission rate after correction of the visual sensitivity measured by using 2 pieces of the same measurement sample (Yp/Yc) to obtain the comparison (CR) . The results are shown in Table 1.

(d) The absolute value of the difference between the average transmittance of each wavelength in the 2 wavelength bands

In Table 2, the parallel position transmittance Tp of each wavelength and the orthogonal position transmittance Tc of each wavelength of each measurement sample are respectively the average value of each wavelength in the range of 520 to 590 nm and the average value of each wavelength in the range of 420 to 480 nm. The absolute value of the difference and the absolute value of the difference between the average value of each wavelength in 520 to 590 nm and the average value of each wavelength in 600 to 640 nm are displayed.

As shown in Table 1 and Table 2, the parallel position transmittance Tp of each wavelength of the measurement samples of Examples 1 to 11 has an average value of 30% or more in the range of 520 to 590 nm, which has a high transmittance. In addition, the parallel transmittance Tp of each wavelength is 2.5% or less in absolute value of the difference between the average value of each wavelength in 420 to 480 nm and the average value of each wavelength in 520 to 590 nm, and the absolute value of the difference between 520 to 590 nm The absolute value of the difference between the average value of each wavelength and the average value of each wavelength from 600 to 640 nm is 3.0% or less, and both are very low values. In addition, the orthogonal transmittance Tc of each wavelength is 1.0% or less of the absolute value of the difference between the average value of each wavelength from 420 to 480 nm and the average value of each wavelength from 520 to 590 nm, and each of 520 to 590 nm The absolute value of the difference between the average value of the wavelength and the average value of each wavelength in the range of 600 to 640 nm is 1.0% or less, and both are very low values. Therefore, the measurement samples obtained in Examples 1 to 8 show that the average transmittance of each wavelength is almost constant in the parallel position and the orthogonal position, respectively. On the other hand, the measurement samples of Comparative Examples 1 to 9 and Comparative Examples 15 to 20 are the absolute value of the difference in the average value of the parallel transmission Tp of each wavelength shown in Table 2 between the above-mentioned wavelength bands, And the orthogonal bit transmittance Tc of each wavelength shows that at least any one of the absolute values of the difference between the average values between the above-mentioned wavelength bands is a higher value.

In addition, comparing Examples 1 to 11 and Comparative Examples 10 to 14 in which the monomer transmittance after correction of the visual sensitivity is 40 to 42%, the comparison with Comparative Examples 10 to 14 is 27 to 189, and Examples 1 to 11 The comparison shows that it is 220 or more. In particular, if Example 5 is compared with Comparative Example 14, Example 5 has a contrast that is about 20% higher. As can be seen from the above, the polarizing plate of this case has high performance. In addition, when observing the difference between the average value of each wavelength of 520 to 590 nm and the average value of each wavelength of 420 to 480 nm, compared with Example 5, it is 0.83% higher in 420 to 480 nm, and Comparative Example 14 is only 0.13% higher. Therefore, it can be seen that the polarizing element or its polarizing plate of this case can achieve high transmittance in the range of 420 to 480 nm.

(e) Polarization ρy after correction of visual sensitivity

Substitute the corrected visual sensitivity of the parallel transmission rate Yp and the corrected visual sensitivity of the orthogonal transmission rate Yc into the following formula (VIII), and obtain the corrected polarization ρy of the visual sensitivity of each measurement sample. The results are shown in Table 3.

ρy={(Yp-Yc)/(Yp+Yc)} ^1/2 ×100 Formula (VIII)

(f) Chromaticity a* value and b* value

For each measurement sample, according to JIS Z 8781-4:2013, measure the respective chromaticity a* value and b* value at the following moments: The monomer transmittance of each wavelength Ts is measured, and the parallel position penetration of each wavelength When measuring the transmission rate Tp, and when measuring the orthogonal bit transmittance Tc of each wavelength. The measurement system uses the above-mentioned spectrophotometer, and measures the transmitted color and the reflected color from the outdoor side. The light source is C light source. The results are shown in Table 3. Here, a*-s and b*-s, a*-p and b*-p, and a*-c and b*-c correspond to the monomer transmittance Ts, parallel position transmittance Tp and orthogonal respectively Chromaticity a* value and b* value when measuring bit transmittance Tc.

(g) Observation of color

For each measurement sample, the same measurement sample was superimposed on the white light source in parallel and orthogonal positions, and the colors observed at this time were investigated. The observation system was performed by 10 observers visually, and the most observed colors are shown in Table 3. In addition, in Table 3, the color of the parallel position means the color of the state (white) when two pieces of the same sample are overlapped with their absorption axis directions parallel to each other, and the color of the orthogonal position means that the two pieces of the same sample are aligned with their absorption axis. Arrange the colors in the overlapping state (during black display) so that the directions are orthogonal to each other. Basically, the color of the polarized light in the parallel position is "white", and the color in the orthogonal position is "black". However, in the embodiment, for example, the yellowish white is expressed as "yellow", and the bluish-purple Black is represented as "blue-purple".

As shown in Table 3, the measured samples of Examples 1 to 11 have a monomer transmittance of 35% or more after the visual sensitivity correction. The measurement samples of Examples 1 to 11 have high transmittance and show a high degree of polarization of 99.5% or more, and it can be seen that white and black can be sufficiently displayed. In addition, in the measurement samples of Examples 1 to 11, the absolute value of a*-s, b*-s, and a*-p is 1.0 or less, and the absolute value of b*-p is 2.0 or less, showing very low values. . When the measurement samples of Examples 1 to 11 are visually observed, they also behave as white as high-quality paper in the parallel position. In addition, in the wavelength bands of 420 nm to 480 nm, 520 nm to 590 nm, and 600 nm to 640 nm, the orthogonal bit transmittance is 1% or less or the polarization degree is about 97%, so it displays black. On the other hand, Comparative Examples 1 to 9 and Comparative Examples 15 to 20 are at least any one of a*-s, b*-s, a*-p, b*-p, a*-c, and b*-c It shows a higher value, or, as in Comparative Example 9, when the orthogonal position transmittance is 1% or more, it is not achromatic in the parallel position or the orthogonal position when visually observed.

It can be seen from the above that the polarizing element of the present invention maintains high monomer transmittance and parallel position transmittance, and can display white as high-quality paper in parallel position. Moreover, the monomer is of high quality without coloring. The hue of neutral color (achromatic neutral gray). In addition, it can be seen that the polarizing element of the present invention maintains the single transmittance after high-sensitivity correction, and exhibits achromaticity in the parallel position, and also has a high degree of polarization. In addition, the polarizing element of the present invention can obtain a polarizing element that displays high-quality achromatic black at the orthogonal position.

(h) Durability test

The measurement samples of Examples 1 to 11 and Comparative Examples 3 to 9 were applied in an environment of 85° C. and a relative humidity of 85% RH for 240 hours. As a result, no change in transmittance or hue was observed in the measurement samples of Examples 1 to 8. In contrast to this, the degree of polarization of Comparative Examples 3 to 9 is reduced by more than 10%, b*-c If it is lower than -10, the appearance color will obviously change to blue. Especially, when two measurement samples are arranged in orthogonal position (during black display), it will appear blue greatly. Therefore, it can be seen that Examples 1 to 8 have high durability.

[Industrial availability]

The polarizing element of the present invention has high transmittance and high degree of polarization, and is achromatic in both white display and black display. By using the polarizing element of the present invention, an extremely useful achromatic polarizing plate and Display device. In one aspect, by using the polarizing element of the present invention, an achromatic polarizer and a display device that exhibit high-quality white in white display can be provided.

Claims (22)

A polarizing element containing the azo compound represented by formula (1) or its salt, and the azo compound represented by formula (2) or its salt,

In formula (1), Ar ₁ represents a substituted phenyl group or a substituted naphthyl group, Rr ₁ and Rr ₂ each independently represent a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, A sulfo group, a halogen atom, or a C1 to 4 alkoxy group having a sulfo group, and _{at least one of Rr 1} and Rr ₂ represents a group other than the above-mentioned hydrogen atom, and Rr ₃ to Rr ₆ each independently represents a hydrogen atom, C1 to 4 alkyl group, C1 to 4 alkoxy group, or C1 to 4 alkoxy group having a sulfo group, j represents 0 or 1, Xr ₁ represents an amine group that may have a substituent, and an alkoxy group that may have a substituent A phenylamino group, a phenylazo group which may have a substituent, a benzylamino group which may have a substituent, or a benzylamino group which may have a substituent;

In the formula (2), Ag ₁ represents a substituted phenyl group or a substituted naphthyl group, and Bg and Cg are each independently represented by the following formula (3) or formula (4), and either of them is represented by the formula ( 3) As shown, Xg ₁ represents an amino group that may have a substituent, a phenylamino group that may have a substituent, a phenylazo group that may have a substituent, a benzyl group that may have a substituent, or A benzylamino group with substituents;

In formula (3), Rg ₁ represents a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, or a C1 to 4 alkoxy group having a sulfo group, and p1 represents an integer of 0 to 2;

In formula (4), Rg ₂ and Rg ₃ each independently represent a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, or a C1 to 4 alkoxy group having a sulfo group. The polarizing element according to claim 1, wherein Cg in the above formula (2) is represented by the above formula (3). The polarizing element according to claim 1 or 2, wherein the azo compound or salt thereof represented by the above formula (2) is an azo compound or salt thereof represented by the following formula (5),

In formula (2), Ag ₂ represents a substituted phenyl group or a substituted naphthyl group, and Rg ₄ and Rg ₅ each independently represent a hydrogen atom, a C1 to 4 alkyl group, an alkoxy group, or a sulfo group The C1 to 4 alkoxy group, Xg ₂ represents an amino group which may have a substituent, a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, and a benzyl group which may have a substituent , Or a benzylamino group which may have a substituent, p ₂ and p ₃ each independently represent an integer of 0 to 2. The polarizing element according to claim 3, wherein p ₂ and p _{3 in the} above formula (5) are 1 or 2, respectively. The polarizing element according to any one of claims 1 to 4, wherein Xr ₁ of the above formula (1) is a phenylamino group which may have a substituent. The polarizing element according to any one of claims 1 to 5, wherein Xg ₁ described in the above formula (2) is a phenylamino group which may have a substituent. The polarizing element according to any one of claims 1 to 6, which further contains an azo compound represented by the following formula (6) or formula (7) or a salt thereof,

In formula (6), Ay ₆₁ represents a sulfo group, a carboxyl group, a hydroxyl group, a C1 to 4 alkyl group, or a C1 to 4 alkoxy group, and Ry ₆₁ to Ry ₆₄ each independently represents a hydrogen atom, a C1 to 4 alkyl group , C1 to 4 alkoxy group, or C1 to 4 alkoxy group having a sulfo group, k represents an integer of 1 to 3; In formula (7), Ay ₇₁ and Ay ₇₂ are each independently an optionally substituted naphthyl group or an optionally substituted phenyl group, s and t are each independently an integer of 0 or 1, Ry ₇₁ , Ry ₇₂ , Ry ₇₇ and Ry ₇₈ are each independently a hydrogen atom, a C1 to 4 alkyl group, and a C1 to 4 alkoxy group, Ry ₇₃ to Ry ₇₆ are each independently a hydrogen atom, a C1 to 4 alkyl group, and C1 to 4 The alkoxy group, the C1 to 4 alkoxy group having a sulfo group. The polarizing element according to claim 7, which contains the azo compound represented by the formula (7) or a salt thereof, and at least any one _{of Ay 71} and Ay _{72 in the above formula (7) is the following formula (8)} As shown,

In formula (8), _{any one of Ry 81} and Ry ₈₂ is a sulfo group, a carboxy group, or a C1 to 4 alkoxy group having a sulfo group, and the other is a hydrogen atom, a sulfo group, a carboxy group, or a sulfo group C1 to 4 alkoxy group, C1 to 4 alkyl group, C1 to 4 alkoxy group, halogen atom, nitro group, amino group, amino group substituted by C1 to 4 alkyl group, or C1 to 4 Alkyl-substituted amide group, * in the formula represents the bonding position with the NH site of the terminal amide group of the above formula (7). The polarizing element according to claim 8, wherein _{any one of Ry 81} and Ry _{82 in} the above formula (8) is a sulfo group or a carboxyl group, and the other is a hydrogen atom, a sulfo group, a carboxyl group, a methyl group, or Methoxy. The polarizing element according to any one of claims 7 to 9, wherein _{at least one of Ay 71} and Ay _{72 in} the above formula (7) is a naphthyl group which may have a substituent. The polarizing element according to any one of claims 7 to 10, wherein Ay ₇₁ and Ay ₇₂ in the above formula (7) are each independently an alkoxy group having C1 to 4 selected from a hydroxyl group and a sulfo group. The naphthyl group of the substituent in the group formed by the sulfo group The polarizing element according to any one of claims 7 to 11, wherein Ay ₇₁ and Ay ₇₂ in the above formula (7) are independently represented by the following formula (9),

In the formula (9), Ry ₉₁ is a hydrogen atom, a hydroxyl group, a C1 to 4 alkoxy group having a sulfo group, or a sulfo group, f is an integer from 1 to 3, and * represents the same as the terminal amide of the above formula (7) The bonding position of the NH site of the base. The polarizing element according to claim 12, wherein, in the above formula (9), Ry ₉₁ is a hydrogen atom and f is 2. The polarizing element according to any one of claims 1 to 13, wherein the transmittance of each wavelength obtained by superposing two polarizing elements so that the respective absorption axis directions are parallel to each other and measuring the transmittance of each wavelength is from 420 nm to The absolute value of the difference between the average transmittance at 480nm and the average transmittance from 520nm to 590nm is 2.5% or less, and the absolute value of the difference between the average transmittance from 520nm to 590nm and the average transmittance from 600nm to 640nm is 3.0 %the following. The polarizing element according to any one of claims 1 to 14, wherein the absolute value of a* value and b* value obtained when measuring transmittance using natural light according to JIS Z 8781-4:2013 is: In the above-mentioned polarizing element monomer, it is less than 1.0, that is, -1.0≦a*-s≦1.0, -1.0≦b-s*≦1.0, When the above two polarizing elements are overlapped and arranged in such a way that their respective absorption axis directions are parallel to each other, they are both below 2.0, that is, -2.0≦a*-p≦2.0, -2.0≦b*-p≦2.0, where, a*-s represents the a* value of the monomer, b*-s represents the b* value of the monomer, a*-p represents the a* value of the parallel position, and b*-p represents the b* of the parallel position. The polarizing element according to any one of claims 1 to 15, wherein the monomer transmittance of the polarizing element after the correction of the visual sensitivity is 35% to 45%, and the two polarizing elements are each The average transmittance of each wavelength from 520nm to 590nm is 28% to 45% when the absorption axis directions are parallel to each other. The polarizing element according to any one of claims 1 to 16, wherein, in each wavelength transmittance obtained by superimposing two polarizing elements so that the respective absorption axis directions are orthogonal to each other, The absolute value of the difference between the average transmittance from 420nm to 480nm and the average transmittance from 520nm to 590nm is 1.0% or less, and the absolute value of the difference between the average transmittance from 520nm to 590nm and the average transmittance from 600nm to 640nm It is 1.0% or less. The polarizing element according to any one of claims 1 to 17, wherein the orthogonal position transmittance of each wavelength in the wavelength bands of 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 more than 97%. The polarizing element according to any one of claims 1 to 18, wherein the two polarizing elements are arranged so that their respective absorption axis directions are orthogonal to each other in a state where they are superimposed and measured by natural light in accordance with JIS Z 8781-4:2013 The absolute values of the a* value and b* value obtained in the transmittance are both below 2.0, that is, -2.0≦a*-c≦2.0, -2.0≦b*-c≦2.0, where, a*-c represents the a* value of the orthogonal bit, and b*-c represents the b* of the orthogonal bit. The polarizing element according to any one of claims 1 to 19, which further contains a polyvinyl alcohol-based resin film as a base material. A polarizing plate is provided with the polarizing element according to any one of claims 1 to 20, and a transparent protective layer provided on one or both sides of the polarizing element. A display device is provided with the polarizing element according to any one of claims 1 to 20 or the polarizing plate according to claim 21.