JP6951366B2 - Azo compounds or salts thereof, and dye-based polarizing films and dye-based polarizing plates containing them. - Google Patents

Description

The present invention relates to a novel azo compound or a salt thereof, and a dye-based polarizing film containing them.

A polarizing plate having a light transmitting / shielding function is a basic component of a display device such as a liquid crystal display (LCD) together with a liquid crystal having a light switching function. The fields of application of this LCD include small devices such as calculators and clocks in the early days, notebook computers, word processors, liquid crystal projectors, liquid crystal televisions, car navigation systems, indoor and outdoor information display devices, measuring devices, and the like. It can also be applied to lenses having a polarizing function, and has been applied to sunglasses with improved visibility, and in recent years, polarized glasses compatible with 3D televisions and the like. It is also applied and put into practical use in familiar information terminals such as wearable terminals. Since the applications of the polarizing plate as described above are widespread, the polarizing plate is used under a wide range of conditions such as low temperature to high temperature, low humidity to high humidity, and low light amount to high light amount. Therefore, the polarization performance is high and durability is high. There is a demand for a polarizing plate having excellent properties.

Currently, the polarizing film is a polarizing film such as a stretch-oriented film of polyvinyl alcohol or a derivative thereof, or a polyene-based film in which polyene is generated and oriented by dehydroxication of a polyvinyl chloride film or dehydration of a polyvinyl alcohol-based film. It is produced by dyeing or containing iodine or a dichroic dye as a dichroic dye on a base material. Of these, iodine-based polarizing films using iodine as a dichroic dye have excellent polarization performance, but are vulnerable to water and heat, and are durable when used for a long time in high temperature and high humidity conditions. I have a problem with my sex. In order to improve the durability, a method of treating with formalin or an aqueous solution containing boric acid, or using a polymer film having low moisture permeability as a protective film has been considered, but the effect is not sufficient. On the other hand, a dye-based polarizing film using a dichroic dye as a dichroic dye is superior in moisture resistance and heat resistance to an iodine-based polarizing film, but generally has insufficient polarizing performance.

As the dye used for producing the dye-based polarizing film, for example, the water-soluble azo compounds described in Patent Documents 1 to 5 are known.

In a neutral color (hereinafter, also referred to as "neutral gray") polarizing film formed by adsorbing and orienting several kinds of dichroic dyes on a polymer film, the orientation directions of the two polarizing films are orthogonal to each other. If there is light leakage (color leakage) of a specific wavelength in the visible light region wavelength region in the superposed state (orthogonal position), the hue of the liquid crystal display changes in the dark state when the polarizing film is attached to the liquid crystal panel. It may end up. Therefore, when the polarizing film is attached to the liquid crystal display device, in order to prevent discoloration of the liquid crystal display due to color leakage of a specific wavelength in a dark state, several kinds of dichroic dyes are adsorbed and oriented on the polymer film. In the neutral gray polarizing film, the transmittance (orthogonal transmittance) at the orthogonal position in the wavelength region of the visible light region must be uniformly lowered.

Until recently, images were displayed with high brightness in order to improve the sharpness of images on liquid crystal displays. In hybrid cars and outdoor display devices (for example, industrial instruments and wearable terminals) equipped with such a display, there is a demand for a longer battery life. For this reason, a polarizing plate exhibiting a neutral gray hue with good polarization performance (hereinafter, "neutral gray polarizing plate") so that the sharpness of the image can be improved even if the brightness is lowered in order to reduce the power consumption of the liquid crystal display. Also called.) Has been sought. Further, in the in-vehicle liquid crystal display, there is a demand for a polarizing plate that does not change the degree of polarization even in a high temperature and high humidity environment in a car in summer. Previously, iodine-based polarizing plates having good polarization performance and exhibiting neutral gray were used for in-vehicle liquid crystal displays. However, the iodine-based polarizing plate has a problem that the light resistance, heat resistance, and moisture heat resistance are not sufficient because iodine is a dichroic dye as described above. In order to solve this problem, a neutral gray polarizing plate using a dye-based dichroic dye as a polarizer has come to be used. The neutral gray polarizing plate is usually used in combination with dyes of the three primary colors (red, green, and blue) in order to improve the transmittance and polarization performance in the entire visible light wavelength region on average. Therefore, it was necessary to develop a dichroic dye having good polarization performance for each of the three primary colors.

In addition, the emission line of the light source is different for each liquid crystal display. Therefore, in developing a dichroic dye having good polarization performance, it is particularly important to design the wavelength of the dye in accordance with the wavelength of the emission line. Therefore, it is necessary for each of the three primary color dyes to reliably control light in a limited wavelength range, suppress absorption in other wavelength ranges as much as possible, and provide excellent polarization performance.

Japanese Unexamined Patent Publication No. 3-012606 Japanese Unexamined Patent Publication No. 2001-33627 International Publication No. 2009/154855 Japanese Unexamined Patent Publication No. 2003-327858 Japanese Unexamined Patent Publication No. 3-12606 Japanese Unexamined Patent Publication No. 2005-171231

However, the blue dyes for polarizing plates so far have been dyes having a copper complex structure as described in Patent Document 6, and in this case, the absorption in the short wavelength region (400 to 500 nm) is increased due to the influence of the copper complex. When the dyes of the three primary colors are combined, there is a drawback that a neutral gray hue cannot be realized. Therefore, it has been desired to develop a blue dye capable of producing a neutral gray polarizing plate in which absorption on the short wavelength side is suppressed and transmittance and polarization performance are improved in the entire visible light wavelength region.

Therefore, an object of the present invention is to enable the production of high-performance dye-based polarizing films and dye-based polarizing plates having excellent polarization performance, particularly neutral gray high-performance dye-based films and dye-based polarizing plates, and their production. To provide an azo compound or a salt thereof.

As a result of diligent research to achieve this object, the present inventors have found that a polarizing film and a polarizing plate containing a specific azo compound or a salt thereof have excellent polarizing performance and have a neutral gray hue. The present invention has been completed.

（式中、Ａ_１及びＡ_２は各々独立に水素原子又は下記式（２）：

（式中、Ｒ_１及びスルホ基が置換している環は、破線で表される環が存在しない場合にはベンゾチアゾール環であり、破線で表される環が存在する場合にはナフトチアゾール環であり、Ｒ_１は塩素原子、スルホ基、ニトロ基、ヒドロキシ基、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、スルホ基を有する炭素数１〜４のアルキル基、ヒドロキシ基を有する炭素数１〜４のアルキル基、カルボキシ基を有する炭素数１〜４のアルキル基、スルホ基を有する炭素数１〜４のアルコキシ基、ヒドロキシ基を有する炭素数１〜４のアルコキシ基、及びカルボキシ基を有する炭素数１〜４のアルコキシ基からなる群より選択され、
Ｂは置換基を有してもよいフェニレン基またはナフチレン基であり、置換基は塩素原子、スルホ基、ニトロ基、ヒドロキシ基、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、スルホ基を有する炭素数１〜４のアルキル基、ヒドロキシ基を有する炭素数１〜４のアルキル基、カルボキシ基を有する炭素数１〜４のアルキル基、スルホ基を有する炭素数１〜４のアルコキシ基、ヒドロキシ基を有する炭素数１〜４のアルコキシ基、及びカルボキシ基を有する炭素数１〜４のアルコキシ基からなる群より（複数ある場合には各々独立して）選択され、
ｍは１〜３の整数である）
で表され、但し、Ａ_１及びＡ_２の両方が水素原子であるものは除き、
−ＮＨ−の２結合は各々独立してａ又はｂで示す置換位置に結合している）
で表されるアゾ化合物又はその塩。
［２］
式（２）が下記式（３）：

（式中、Ｒ_１ａが置換されている環、及びＲ_１ａは式（２）におけるＲ _１ が置換されている環及びＲ_１と同じものを表し、
Ｒ_２及びＲ_３は各々独立に水素原子、塩素原子、スルホ基、ニトロ基、ヒドロキシ基、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、スルホ基を有する炭素数１〜４のアルキル基、ヒドロキシ基を有する炭素数１〜４のアルキル基、カルボキシ基を有する炭素数１〜４のアルキル基、スルホ基を有する炭素数１〜４のアルコキシ基、ヒドロキシ基を有する炭素数１〜４のアルコキシ基、及びカルボキシ基を有する炭素数１〜４のアルコキシ基からなる群より選択され、
ｍ_１は、式（２）におけるｍと同じ意味を表す）、
又は、下記式（４）：

（式中のＲ_１ｂが置換されている環、及びＲ_１ｂは式（２）におけるＲ _１ が置換されている環及びＲ_１と同じものを表し、
Ｒ_４〜Ｒ_６は各々独立に水素原子、塩素原子、スルホ基、ニトロ基、ヒドロキシ基、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、スルホ基を有する炭素数１〜４のアルキル基、ヒドロキシ基を有する炭素数１〜４のアルキル基、カルボキシ基を有する炭素数１〜４のアルキル基、スルホ基を有する炭素数１〜４のアルコキシ基、ヒドロキシ基を有する炭素数１〜４のアルコキシ基、及びカルボキシ基を有する炭素数１〜４のアルコキシ基からなる群より選択され、
ｍ_２は、式（２）におけるｍと同じ意味を表す）
で表される［１］に記載のアゾ化合物又はその塩。
［３］
Ａ_１及びＡ_２が各々独立に式（３）又は式（４）で表される［２］に記載のアゾ化合物又はその塩。
［４］
Ａ_１が式（３）又は式（４）で表され、Ａ_２が水素原子である［２］に記載のアゾ化合物又はその塩。
［５］
式（４）中のＲ_１ｂが水素原子、塩素原子、炭素数１〜４のアルキル基、又は炭素数１〜４のアルコキシ基であり、Ｒ_４〜Ｒ_６が各々独立に水素原子、炭素数１〜４のアルキル基、又はスルホ基を有してもよい炭素数１〜４のアルコキシ基である［２］〜［４］のいずれかに記載のアゾ化合物又はその塩。
［６］
式（３）中のＲ_１ａは水素原子、塩素原子または炭素数１〜４のアルキル基であり、Ｒ_２及びＲ_３が各々独立に水素原子、炭素数１〜４のアルキル基、又はスルホ基を有してもよい炭素数１〜４のアルコキシ基である［２］〜［５］のいずれかに記載のアゾ化合物又はその塩。
［７］
式（１）中の−ＮＨ−置換位置がａである［１］〜［６］のいずれかに記載のアゾ化合物又はその塩。
［８］
［１］〜［７］のいずれかに記載のアゾ化合物又はその塩と、偏光膜基材とを含む、染料系偏光膜。
［９］
［１］〜［７］のいずれかに記載のアゾ化合物又はその塩及びこれ以外の有機染料を１種類以上と、偏光膜基材とを含む、染料系偏光膜。
［１０］
［１］〜［７］のいずれかに記載のアゾ化合物又はその塩を２種類以上及びこれら以外の有機染料を１種類以上と、偏光膜基材とを含む、染料系偏光膜。
［１１］
偏光膜基材がポリビニルアルコール樹脂又はその誘導体から形成されるフィルムである、［８］〜［１０］のいずれかに記載の染料系偏光膜。
［１２］
［８］〜［１１］のいずれかに記載の染料系偏光膜の少なくとも一方の面に透明保護層を貼合して得られる、染料系偏光板。
［１３］
［８］〜［１１］のいずれかに記載の染料系偏光膜又は［１２］に記載の染料系偏光板を備える液晶表示装置。
［１４］
ニュートラルグレーを呈する［８］〜［１１］のいずれかに記載の染料系偏光膜。
［１５］
［１４］に記載の染料系偏光膜、又は前記染料系偏光膜の少なくとも一方の面に透明保護層を貼合して得られる染料系偏光板を備える車載用表示装置又は屋外表示装置。 That is, the present invention relates to the following [1] to [15].
[1]
The following formula (1):

(In the formula, A ₁ and A ₂ are independently hydrogen atoms or the following formula (2):

(Wherein ring R ₁ and a sulfo group is substituted, if a ring represented by a broken line does not exist is a benzothiazole ring, naphthothiazole ring when there is a ring represented by a broken line R ₁ is a chlorine atom, a sulfo group, a nitro group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms having a sulfo group, and hydroxy. An alkyl group having 1 to 4 carbon atoms having a group, an alkyl group having 1 to 4 carbon atoms having a carboxy group, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, and an alkoxy group having 1 to 4 carbon atoms having a hydroxy group. , And selected from the group consisting of alkoxy groups having 1 to 4 carbon atoms having a carboxy group.
B is a phenylene group or a naphthylene group which may have a substituent, and the substituents are a chlorine atom, a sulfo group, a nitro group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms. , An alkyl group having 1 to 4 carbon atoms having a sulfo group, an alkyl group having 1 to 4 carbon atoms having a hydroxy group, an alkyl group having 1 to 4 carbon atoms having a carboxy group, and 1 to 4 carbon atoms having a sulfo group. It is selected from the group consisting of an alkoxy group, an alkoxy group having 1 to 4 carbon atoms having a hydroxy group, and an alkoxy group having 1 to 4 carbon atoms having a carboxy group (independently if there are a plurality of groups).
m is an integer from 1 to 3)
Represented by, except for those in which both _{A 1} and A _{2 are hydrogen atoms.}
The two -NH- bonds are independently bonded to the substitution positions indicated by a or b).
An azo compound represented by or a salt thereof.
[2]
Equation (2) is the following equation (3):

(Expressed in the _formula, the _{ring R 1a} is substituted, and _{R 1a} is the same as the ring and R ₁ wherein R ₁ is substituted in equation (2),
R ₂ and R ₃ independently have a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a sulfo group having 1 to 1 carbon atoms. An alkyl group of 4, an alkyl group having 1 to 4 carbon atoms having a hydroxy group, an alkyl group having 1 to 4 carbon atoms having a carboxy group, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, and a carbon number having a hydroxy group. Selected from the group consisting of 1 to 4 alkoxy groups and 1 to 4 carbon number alkoxy groups having a carboxy group.
m ₁ has the same meaning as m in equation (2)),
Alternatively, the following formula (4):

_{(Ring R 1b} in the formula is substituted, and _{R 1b} represent the same as the ring and R ₁ wherein R ₁ is substituted in equation (2),
R _{4 to} R ₆ independently have a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a sulfo group having 1 to 1 carbon atoms. Alkyl group of 4, alkyl group having 1 to 4 carbon atoms having a hydroxy group, alkyl group having 1 to 4 carbon atoms having a carboxy group, alkoxy group having 1 to 4 carbon atoms having a sulfo group, and carbon number having a hydroxy group. Selected from the group consisting of 1 to 4 alkoxy groups and 1 to 4 carbon number alkoxy groups having a carboxy group.
m ₂ has the same meaning as m in equation (2))
The azo compound according to [1] represented by (1) or a salt thereof.
[3]
The azo compound or salt thereof according to [2], wherein A ₁ and A ₂ are independently represented by the formula (3) or the formula (4).
[4]
The azo compound or salt thereof according to [2], wherein A ₁ is represented by the formula (3) or the formula (4), and A _{2 is a hydrogen atom.}
[5]
_{R 1b} in the formula (4) is a hydrogen atom, a chlorine atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and R _{4 to} R ₆ are independently hydrogen atoms and carbon atoms, respectively. The azo compound or a salt thereof according to any one of [2] to [4], which is an alkoxy group having 1 to 4 carbon atoms which may have an alkyl group of 1 to 4 or a sulfo group.
[6]
_{R 1a} in the formula (3) is a hydrogen atom, a chlorine atom or an alkyl group having 1 to 4 carbon atoms, and R ₂ and R ₃ are independently hydrogen atoms, an alkyl group having 1 to 4 carbon atoms, or a sulfo group, respectively. The azo compound or a salt thereof according to any one of [2] to [5], which is an alkoxy group having 1 to 4 carbon atoms which may have.
[7]
The azo compound or salt thereof according to any one of [1] to [6], wherein the -NH- substitution position in the formula (1) is a.
[8]
A dye-based polarizing film containing the azo compound according to any one of [1] to [7] or a salt thereof, and a polarizing film base material.
[9]
A dye-based polarizing film comprising one or more kinds of the azo compound according to any one of [1] to [7], a salt thereof, and other organic dyes, and a polarizing film base material.
[10]
A dye-based polarizing film containing two or more types of the azo compound or a salt thereof according to any one of [1] to [7], one or more types of organic dyes other than these, and a polarizing film base material.
[11]
The dye-based polarizing film according to any one of [8] to [10], wherein the polarizing film substrate is a film formed of a polyvinyl alcohol resin or a derivative thereof.
[12]
A dye-based polarizing plate obtained by laminating a transparent protective layer on at least one surface of the dye-based polarizing film according to any one of [8] to [11].
[13]
A liquid crystal display device including the dye-based polarizing film according to any one of [8] to [11] or the dye-based polarizing plate according to [12].
[14]
The dye-based polarizing film according to any one of [8] to [11], which exhibits neutral gray.
[15]
[14] dye-based polarizing film, or vehicle display device or outdoor display device comprising a dye-based polarizing plate obtained by pasting a transparent protective layer on at least one surface of the dye-based polarizing film according to.

The present invention relates to a high-performance dye-based polarizing film and dye-based polarizing plate having excellent polarization performance, particularly a neutral gray high-performance dye-based film and dye-based polarizing plate, and an azo compound capable of producing the same. The salt can be provided. In one aspect, the polarizing plate of the present invention has moisture resistance, heat resistance, and / or light resistance.

で表される。
式（１）において、−ＮＨ−の２結合は各々独立してａ又はｂで示す置換位置に結合している。<Azo compound or salt thereof>
The azo compound of the present invention has the following formula (1):

It is represented by.
In formula (1), the two -NH- bonds are independently bonded to the substitution positions represented by a or b.

で表される。但し、Ａ_１及びＡ_２の両方が水素原子である場合は除く。Ａ_１及びＡ_２の一方が水素原子であり、他方が式（２）で表されるか、又は、Ａ_１及びＡ_２の両方が式（２）で表される。好ましくは、Ａ_１及びＡ_２の両方が式（２）で表される。A ₁ and A ₂ are hydrogen atoms or the following formula (2):

It is represented by. However, this excludes cases where both _{A 1} and A _{2 are hydrogen atoms.} One of A ₁ and A ₂ is a hydrogen atom and the other is represented by the formula (2), or _{both A 1} and A ₂ are represented by the formula (2). Preferably, _{both A 1} and A ₂ are represented by the formula (2).

In the formula (2), the ring R ₁ and a sulfo group is substituted, if ring represented by a broken line is absent is a benzothiazole ring, naphtho if ring represented by a broken line is present It is a thiazole ring. When the ring represented by the broken line does not exist, that is, when the ring substituted by _{R 1 is a benzothiazole ring, the substitution positions of R 1} and the sulfo group are not particularly limited, but only the 4-position and the 6-position, The combination of the 4th and 6th positions and the combination of the 6th and 7th positions are preferable, and the combination of only the 6th position and the 4th and 6th positions is more preferable. When the ring represented by the broken line is present, that is, when the ring substituted by _{R 1 is a naphthoazole ring, the substitution position of the sulfo group and R 1} is not particularly limited, but the combination of the 6-position and the 8-position, A combination of 4th, 6th and 8th positions, and a combination of 4th, 7th and 9th positions are preferable, and a combination of 6th and 8th positions is more preferable.

R ₁ is a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms having a sulfo group, and a hydroxy group. An alkyl group having 1 to 4 carbon atoms having a group, an alkyl group having 1 to 4 carbon atoms having a carboxy group, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, and an alkoxy group having 1 to 4 carbon atoms having a hydroxy group. , And selected from the group consisting of alkoxy groups having 1 to 4 carbon atoms having a carboxy group. It is preferably a sulfo group or an alkoxy group having 1 to 4 carbon atoms. When R ₁ is a plurality, they are selected independently.

The lower alkoxy group having a hydroxy group is preferably a linear alkoxy group in which the terminal of the alkoxy group is substituted with a hydroxy group, and more preferably a 4-hydroxypropoxy group or a 4-hydroxybutoxy group. The lower alkoxy group having a carboxy group is preferably a linear alkoxy group in which the terminal of the alkoxy group is substituted with a carboxy group, and more preferably a 4-carboxypropoxy group or a 4-carboxybutoxy group. The lower alkoxy group having a sulfo group is preferably a linear alkoxy group in which the terminal of the alkoxy group is substituted with a sulfo group, and more preferably a 4-sulfopropoxy group or a 4-sulfobutoxy group.

B is a phenylene group or a naphthylene group which may have a substituent. The bonding position between B and the two azo groups is not limited. Substituents are hydrogen atom, chlorine atom, sulfo group, nitro group, hydroxy group, alkyl group having 1 to 4 carbon atoms, alkoxy group having 1 to 4 carbon atoms, alkyl group having 1 to 4 carbon atoms having sulfo group, hydroxy. An alkyl group having 1 to 4 carbon atoms having a group, an alkyl group having 1 to 4 carbon atoms having a carboxy group, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, and an alkoxy group having 1 to 4 carbon atoms having a hydroxy group. , And selected from the group consisting of alkoxy groups having 1 to 4 carbon atoms having a carboxy group. If there are multiple substituents, they are selected independently. When B is a phenylene group which may have a substituent, the substitution position is not particularly limited, but the combination of the 2-position and the 5-position and the combination of the 3-position and the 5-position are preferable, and the combination of the 2-position and the 5-position is preferable. Especially preferable. When B is a naphthylene group which may have a substituent, the substitution position is not particularly limited, but only the 2-position, the 6-position only, the 7-position only, the combination of the 2-position and the 6-position, and the 2-position and the 7-position. Is preferable, and only the 2-position and the combination of the 2-position and the 7-position are particularly preferable.

又は、式（４）：

で表される。The formula (2) is preferably the following formula (3):

Or, equation (4):

It is represented by.

In the formula (3), the _{rings in which R 1a} and R _1a are substituted have the same meaning as the rings in which _{R 1} and R _{1 are substituted in the formula (2).}
R ₂ and R ₃ have the same meaning as the substituent that B in the formula (2) may have. A hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms having a sulfo group are preferable.
m ₁ has the same meaning as m in the equation (2).

In formula (4), the _{rings in which R 1b} and R _1b are substituted have the same meaning as the rings in which _{R 1} and R _{1 are substituted in the formula (2).}
R _{4 to} R ₆ have the same meaning as the substituents that B in the formula (2) may have. It is preferably a hydrogen atom, a sulfo group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms.
m ₂ has the same meaning as m in the equation (2).

The azo compound represented by the formula (1) may be in the free form or in the salt form. The salt can 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.

Next, specific examples of the azo compound represented by the formula (1) will be given below. The sulfo group, carboxy group, and hydroxy group in the formula are represented in the form of a free acid.

The azo compound represented by the formula (1) or a salt thereof is prepared according to, for example, a conventional method for producing an azo dye as described in Patent Document 3 and Dye Chemistry (Yutaka Hosoda, 1957, p. 621). It can be produced by diazotization and coupling.

The following method can be mentioned as an example of a specific manufacturing method.
Aminothiazoles represented by the following formula (A) are diazotized and primaryly coupled with anilines represented by the following formula (B) or aminonaphthalene represented by the following formula (C), and the following formula (D) is used. ) Or a monoazoamino compound represented by the following formula (E).

The monoazoamino compound (D) or (E) is diazotized, and the azo compound of the formula (1) is obtained by secondary coupling with the naphthols of the following formula (F), respectively.

In the formulas (A) to (F), _{the replacement positions of R 1} and R ₁ have the same meaning as those in the formula (2), and R ₂ and R ₃ have the same meaning as those in the formula (3). _{4 to} R ₆ have the same meaning as those in the formula (4), and m has the same meaning as that in the formula (2).

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

The monoazo compound of the formula (D) or the formula (E) obtained by coupling can be filtered as it is, precipitated by acidification or salting out, filtered out, or taken out as a solution or a suspension in the next step. You can also proceed to. If the diazonium salt is sparingly soluble and is a suspension, it can be filtered and used as a press cake in the next coupling step.

The secondary coupling reaction between the diazodized monoazo compound of the formula (D) or the formula (E) and the naphthols represented by the formula (F) is neutral at pH 7 to 10 at a temperature of -10 to 40 ° C. It is preferable to carry out under alkaline conditions. After completion of the reaction, the obtained azo compound or salt of the formula (1) is preferably precipitated by salting out and filtered out. When purification is required, salting out may be repeated or precipitation may be performed from water using an organic solvent. Examples of the organic solvent used for purification include water-soluble organic solvents such as alcohols such as methanol and ethanol, and ketones such as acetone.

The aminothiazole compound represented by the formula (A) is represented as 2-aminobenzothiazoles in the absence of the ring represented by the broken line, and is represented by, for example, 2-amino-6-sulfobenzothiazole, 2-amino. Examples thereof include -7-methoxy-6-sulfobenzothiazole, 2-amino-4,6-disulfobenzothiazole, and 2-amino-7-methoxy-4,6-disulfobenzothiazole. The aminothiazole compound represented by the formula (A) is represented as 2-aminonaphthiazoles in the presence of a ring represented by a broken line, for example, 2-amino-6,8-disulfonaphthiazole, 2-Amino-4,6,8-trisulfonaphthiazole, 2-amino-4-chloro-6,8-disulfonaphthiazole, 2-amino-6-sulfopropoxy-4,8-disulfonaphthiazole, 2-Amino-6-sulfopropoxy-4,7,8-trisulfonaphthiazole, 2-amino-6-methoxy-4,7,8-trisulfonaphthiazole, 2-amino-7-sulfopropoxy-4, Examples thereof include 9-disulfonaphthiazole and 2-amino-4-sulfopropoxy-5,7,9-trisulfonaphthiazole, and examples thereof include 2-amino-6-sulfobenzothiazole and 2-amino-7-methoxy. -6-sulfobenzothiazole and 2-amino-6,8-disulfonaphthiazole are preferred.

Examples of the anilines of the formula (B) include anilines having a lower alkoxyl group having a sulfo group. Examples are 3- (2-amino-4-methylphenoxy) propan-1-sulfonic acid, 3- (2-aminophenoxy) propan-1-sulfonic acid, and 3- (2-amino-4-methylphenoxy). ) Butane-1-sulfonic acid and the like. Examples of other anilines include aniline, 2-methylaniline, 3-methylaniline, 2-ethylaniline, 3-ethylaniline, 2,5-dimethylaniline, 2,5-diethylaniline, and 2-methoxyaniline. Examples thereof include 3-methoxyaniline, 2-methoxy-5-methylaniline, 2,5-dimethoxyaniline, 3,5-dimethylaniline, 2,6-dimethylaniline, and 3,5-dimethoxyaniline. Preferred are 2-methoxy-5-methylaniline and 2,5-dimethoxyaniline. These anilines may have an amino group protected. Examples of the aminonaphthalene of the formula (C) include 1-aminonaphthalene, 1-aminonaphthalene-6-sulfonic acid, 1-aminonaphthalene-7-sulfonic acid, 1-amino-2-methoxynaphthalene-6-sulfon. Acids, 1-amino-2-methoxynaphthalene-7-sulfonic acid, 1-amino-2-ethoxynaphthalene-6-sulfonic acid, and 1-amino-2-ethoxynaphthalene-7-sulfonic acid are preferred. Examples thereof include 1-aminonaphthalene-7-sulfonic acid and 1-amino-2-methoxynaphthalene-7-sulfonic acid. These aminonaphthalene may have an amino group protected. Examples of the protecting group include the ω-methanesulfon group.

The azo compound or a salt thereof according to the present invention is useful as a dye for a polarizing film. The azo compound or a salt thereof according to the present invention is a blue dye and has a maximum absorption wavelength in the vicinity of, for example, 600 to 670 nm. According to the azo compound or a salt thereof according to the present invention, a high-performance dye-based polarizing plate having excellent polarization performance can be produced, and in particular, there is little color leakage at orthogonal positions in the wavelength region of the visible light region. It is possible to realize a high-performance dye-based polarizing plate of neutral gray. In one aspect, the azo compound or salt thereof according to the present invention can be suitably used for producing a neutral gray polarizing plate for automobiles or outdoor display used under high temperature and high humidity conditions.

<Dye-based polarizing film>
The dye-based polarizing film includes a dichroic dye containing at least an azo compound represented by the formula (1) or a salt thereof, and a polarizing film base material. The dye-based polarizing film can be either a color polarizing film or a neutral gray polarizing film, and is preferably a neutral gray polarizing film. Here, "neutral gray" means that there is little light leakage (color leakage) of a specific wavelength in the wavelength region of the visible light region in a state where two polarizing films are superposed so that their orientation directions are orthogonal to each other. means.

The dye-based polarizing film may contain one or more azo compounds represented by the formula (1) or salts thereof as dichroic dyes, and may further contain one or more other organic dyes as necessary. can. The other organic dyes used in combination are not particularly limited, but are dyes having absorption characteristics in a wavelength region different from the absorption wavelength region of the azo compound represented by the formula (1) or a salt thereof, and have high dichroism. It is preferable that it is a thing. Examples of the organic dye used in combination include C.I. I. direct. Yellow 12, C.I. I. direct. Yellow 28, C.I. I. direct. Yellow 44, C.I. I. direct. Orange 26, C.I. I. direct. Orange 39, C.I. I. direct. Orange 71, C.I. I. direct. Orange 107, C.I. I. direct. Red 2, C.I. I. direct. Red 31, C.I. I. direct. Red 79, C.I. I. direct. Red 81, C.I. I. direct. Red 247, C.I. I. direct. Green 80 and C.I. I. direct. Typical examples include Green 59 and the dyes described in Patent Documents 1 to 5. These dyes are contained in the dye-based polarizing film as free acids or as salts of alkali metal salts (for example, Na salt, K salt, Li salt), ammonium salts, or amines.

When other organic dyes are used in combination, depending on whether the target dye-based polarizing film is a neutral gray polarizing film, a color polarizing film for a liquid crystal projector, or another color polarizing film, the other organic dyes to be blended are used. The types are different. The blending ratio of the other organic dyes is not particularly limited, but the total of one or more organic dyes is 0.1 to 10 with respect to 100 parts by mass of the azo compound of the formula (1) or a salt thereof. It is preferably in the range of parts by mass.

In the case of a neutral gray polarizing film, the types of other organic dyes used in combination and their blending ratios are adjusted so that the obtained polarizing film has less color leakage in the wavelength region of the visible light region.

In the case of a color polarizing film, when the obtained polarizing film has a high single-plate average light transmittance in a specific wavelength range and two polarizing films are stacked so that the absorption axes are orthogonal to each other (orthogonal position). It is used in combination so as to have a low average light transmittance of, for example, a single plate average light transmittance of 39% or more in a specific wavelength range and an average light transmittance of 0.4 or less at an orthogonal position. The types of other organic dyes and their blending ratios are adjusted. Here, the average light transmittance of a single plate is the same as that of a single polarizing plate without a polarizing film or an AR (antireflection) layer and a support such as a transparent glass plate (hereinafter, simply referred to as a polarizing plate). It is the average value of the light transmittance in a specific wavelength region when natural light is incident on). The average light transmittance at the orthogonal position is the average value of the light transmittance in a specific wavelength region when natural light is incident on two polarizing films or polarizing plates arranged so that the orientation directions are orthogonal to each other.

The dye-based polarizing film of various colors or the neutral gray dye-based polarizing film contains at least an azo compound represented by the formula (1) or a salt thereof, and if necessary, a dichroic dye further containing another organic dye. Can be produced by being contained in a polarizing film base material (for example, a polymer film) by a known method and oriented, mixed with a liquid crystal, or oriented by a coating method.

The polarizing film base material is preferably a polymer film, and more preferably a film formed of a polyvinyl alcohol resin or a derivative thereof. Specific examples of the polarizing film base material include polyvinyl alcohol or a derivative thereof, and any of these modified with olefins such as ethylene and propylene, and unsaturated carboxylic acids such as crotonic acid, acrylic acid, methacrylic acid, and maleic acid. Things etc. can be mentioned. As the polarizing film base material, a film formed of polyvinyl alcohol or a derivative thereof is preferably used from the viewpoint of dye adsorptivity and orientation. The thickness of the polarizing film substrate is usually about 30 to 100 μm, preferably about 50 to 80 μm.

When the polarizing film base material is a polymer film, a method of dyeing the polymer film can usually be adopted when containing a dichroic dye containing at least the azo compound of the formula (1) or a salt thereof. .. The dyeing can be performed, for example, as follows. First, the azo compound of the present invention or a salt thereof, and if necessary, other organic dyes are dissolved in water to prepare a dyeing bath. The dye concentration in the dyeing bath is not particularly limited, but is usually selected from the range of about 0.001 to 10% by mass. Further, a dyeing aid may be used if necessary, and for example, it is preferable to use Glauber's salt at a concentration of about 0.1 to 10% by mass. The polymer film is immersed in the dyeing bath thus prepared for, for example, 1 to 10 minutes for dyeing. The dyeing temperature is preferably about 40 to 80 ° C.

The orientation of the dichroic dye containing the azo compound of the formula (1) or a salt thereof is performed by stretching the dyed polymer film. As the stretching method, any known method such as a wet method or a dry method can be used. In some cases, the polymer film may be stretched before dyeing. In this case, the orientation of the water-soluble dye is performed at the time of dyeing. The polymer film containing and oriented the water-soluble dye is subjected to post-treatment such as boric acid treatment by a known method, if necessary. Such post-treatment is performed for the purpose of improving the light transmittance and the degree of polarization of the dye-based polarizing film. The conditions for boric acid treatment differ depending on the type of polymer film used and the type of dye used, but in general, the boric acid concentration of the boric acid aqueous solution is 0.1 to 15% by mass, preferably 1 to 10% by mass. The treatment is carried out in a temperature range of, for example, 30 to 80 ° C., preferably 40 to 75 ° C., for example, by immersing for 0.5 to 10 minutes. Further, if necessary, the fixing treatment may be performed together with an aqueous solution containing a cationic polymer compound.

The obtained dye-based polarizing film can be used as a polarizing plate by attaching a protective film, and a protective layer or AR layer, a support, and the like can be further provided as needed. Applications of various color dye-based polarizing plates and neutral gray dye-based polarizing films include, for example, liquid crystal projectors, calculators, clocks, notebook computers, word processors, liquid crystal televisions, car navigation systems, indoor and outdoor measuring instruments, and displays for cars, etc. , And lenses, glasses, and the like. The dye-based polarizing film has high polarization performance comparable to that of a polarizing film using iodine, and is also excellent in durability. Therefore, it is particularly suitable for various liquid crystal displays, liquid crystal projectors, automobiles, and outdoor displays (for example, display applications and wearable applications of industrial instruments) that require high polarization performance and durability.

<Dye-based polarizing plate>
The dye-based polarizing plate can be obtained by laminating a transparent protective film on one side or both sides of the dye-based polarizing film. Since the dye-based polarizing plate includes the above-mentioned dye-based polarizing film, it has excellent polarization performance. As the material for forming the transparent protective film, a material having excellent optical transparency and mechanical strength is preferable. For example, in addition to a cellulose acetate film or an acrylic film, an ethylene tetrafluoride / propylene hexafluoride copolymer Fluorine-based films such as, polyester resin, polyolefin resin, polyamide-based resin, and the like are used. The transparent protective film is preferably a triacetyl cellulose (TAC) film or a cycloolefin-based film. The thickness of the protective film is usually preferably 40 to 200 μm.

Examples of the adhesive that can be used to bond the polarizing film and the protective film include polyvinyl alcohol-based adhesives, urethane emulsion-based adhesives, acrylic adhesives, polyester-isocyanate-based adhesives, and the like, and polyvinyl alcohol-based adhesives. The agent is suitable.

A more transparent protective layer may be provided on the surface of the dye-based polarizing plate. Further examples of the transparent protective layer include an acrylic or polysiloxane-based hard coat layer and a urethane-based protective layer. Further, in order to further improve the light transmittance of the veneer, it is preferable to provide an AR layer on the protective layer. The AR layer can be formed by depositing or sputtering a substance such as silicon dioxide or titanium oxide, or by applying a thin coating of a fluorine-based substance. The dye-based polarizing plate can also be used as an elliptical polarizing plate by further attaching a retardation plate to the surface.

The dye-based polarizing plate may be either a color polarizing plate or a neutral polarizing plate depending on the intended use.

The neutral gray polarizing plate has excellent polarization performance. In one aspect, the neutral gray polarizing plate has less color leakage at orthogonal positions in the wavelength region of the visible light region. Further, in one aspect, the neutral gray polarizing plate has a feature that discoloration and deterioration of polarization performance are prevented even in a high temperature and high humidity state, and light leakage at an orthogonal position in a visible light region is small, and is used for in-vehicle or outdoor display. Suitable for.

The neutral gray polarizing plate for in-vehicle or outdoor display is a polarizing plate composed of a polarizing film and a protective film, which is provided with an AR layer in order to further improve the light transmittance of a single plate to form a polarizing plate with an AR layer. More preferably, an AR layer provided with a support such as a transparent resin and a polarizing plate with the support are more preferable. The AR layer can be provided on one side or both sides of the polarizing plate. The support is preferably provided on one side of the polarizing plate, and may be provided on the polarizing plate via the AR layer or directly. The support preferably has a flat portion for attaching the polarizing plate, and is preferably a transparent substrate because it is used for optics. Transparent substrates are roughly divided into inorganic substrates and organic substrates. Inorganic substrates such as soda glass, borosilicate glass, crystal substrates, sapphire substrates, and spinel substrates, as well as acrylic, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, and Examples thereof include an organic substrate such as a cycloolefin polymer, but an organic substrate is preferable. The thickness and size of the transparent substrate may be a desired size.

The color polarizing plate has excellent polarization performance. In one aspect, the color polarizing plate is suitable for liquid crystal projectors, in-vehicle use, and outdoor display because it does not cause discoloration or deterioration of polarization performance even in a high temperature and high humidity state. The color polarizing plate can be manufactured by attaching a protective film to a dye-based polarizing film to form a polarizing plate, and if necessary, providing a protective layer, an AR layer, a support, or the like.

A color polarizing plate with a support for in-vehicle use or outdoor display is manufactured, for example, by applying a transparent adhesive (adhesive) agent to the flat surface portion of the support and then attaching a dye-based polarizing plate to the coated surface. Can be done. Alternatively, a transparent adhesive (adhesive) may be applied to the dye-based polarizing plate, and then a support may be attached to the coated surface. The adhesive (adhesive) used here is preferably an acrylic acid ester type, for example. When this dye-based polarizing plate is used as an elliptical polarizing plate, the retardation plate side is usually attached to the support side, but the polarizing plate side may be attached to the transparent substrate.

<Liquid crystal display>
The liquid crystal display device includes the above-mentioned dye-based polarizing film or dye-based polarizing plate. Liquid crystal displays are for, for example, calculators, watches, laptops, word processors, LCD TVs, car navigation systems, and displays for indoor and outdoor measuring instruments and displays, and in particular, require high polarization performance and durability. It is suitably used for various liquid crystal displays, for example, for in-vehicle and outdoor displays (for example, display applications and wearable applications of industrial instruments).

The dye-based polarizing film or dye-based polarizing plate provided in the liquid crystal display device is preferably neutral gray. By using a neutral gray dye-based polarizing film or dye-based polarizing plate, it is possible to prevent discoloration of the liquid crystal display due to color leakage of a specific wavelength in a dark state.

In a liquid crystal display device, a dye-based polarizing plate is arranged on either one or both of the incident side and the outgoing side of the liquid crystal cell. The dye-based polarizing plate may or may not be in contact with the liquid crystal cell, but it is preferable that the dye-based polarizing plate is not in contact with the liquid crystal cell from the viewpoint of durability. When the polarizing plate is in contact with the liquid crystal cell on the exit side of the liquid crystal cell, the liquid crystal cell can be used as a support for the dye-based polarizing plate. When the dye-based polarizing plate is not in contact with the liquid crystal cell, it is preferable to use a dye-based polarizing plate using a support other than the liquid crystal cell. Further, from the viewpoint of durability, it is preferable that the dye-based polarizing plate is arranged on both the incident side and the exit side of the liquid crystal cell, and further, the polarizing plate surface of the dye-based polarizing plate is on the liquid crystal cell side and the support surface is the light source. It is preferable to arrange it on the side. The incident side of the liquid crystal cell is the light source side, and the opposite side is called the exit side.

The liquid crystal cell provided in the liquid crystal display device for in-vehicle or outdoor display is, for example, an active matrix type, in which a liquid crystal is enclosed between a transparent substrate on which an electrode and a TFT are formed and a transparent substrate on which a counter electrode is formed. It is preferably formed. Light emitted from a light source such as a cold cathode fluorescent lamp or a white LED passes through a neutral gray polarizing plate, then passes through a liquid crystal cell, a color filter, and a neutral gray polarizing plate, and is projected onto a display screen.

In the in-vehicle or outdoor display display device configured as described above, the neutral gray polarizing plate has brightness and excellent polarization performance. Further, in one aspect, since the in-vehicle or outdoor display display device has durability and light resistance, it is unlikely to cause discoloration or deterioration of polarization performance even in a high temperature and high humidity state inside or outdoors, and is characterized by high reliability. Have.

Hereinafter, the present invention will be described in more detail with reference to Examples, but these are exemplary and do not limit the present invention in any way. The% and parts in the example are based on mass unless otherwise specified.

[Example 1]
Add 36.0 parts of 2-aminonaphthiazole-6,8-disulfonic acid to 100 parts of 98% sulfuric acid, dissolve at 50 ° C, add 12.6 parts of 60% nitric acid, and add 40% at 5-10 ° C. 50 parts of nitrosylsulfuric acid was added dropwise over about 10 minutes, and the reaction was carried out for 1 hour to obtain a diazo reaction solution. Next, 15.3 parts of 2,5-dimethoxyaniline was dissolved by adding 10.4 parts of 35% hydrochloric acid to an acidic aqueous solution diluted with 100 parts of water. The diazo reaction solution was added dropwise to this aqueous solution over 3 hours and stirred overnight to complete the coupling reaction. Then, filtration was performed to obtain 41.9 parts of a monoazoamino compound represented by the following formula (46).

41.9 parts of the obtained monoazoamino compound (46) was added to 200 parts of water, and 25% sodium hydroxide was added thereto to dissolve the monoazoamino compound. 13.8 parts of a 40% aqueous sodium nitrite solution was added thereto, then 25.0 parts of 35% hydrochloric acid was added at 20 to 30 ° C., and the mixture was stirred at 20 to 30 ° C. for 1 hour to obtain a diazodide. On the other hand, 36.9 parts of 6,6'-iminobis (1-hydroxynaphthalene-3-sulfonic acid) was added to 100 parts of water, and a 25% sodium hydroxide aqueous solution was added thereto to make it weakly alkaline, 6,6'-. Iminobis (1-hydroxynaphthalene-3-sulfonic acid) was dissolved. The previously obtained diazodide was added dropwise to this liquid at a pH of 8 to 10, and the mixture was stirred to complete the coupling reaction. Then, it was salted out with sodium chloride and then filtered to obtain 63.7 parts of the compound represented by the formula (5). The maximum absorption wavelength of the compound in the 20% aqueous pyridine solution was 675 nm.

[Example 2]
Example 1 except that 36.9 parts of 6,6'-iminobis (1-hydroxynaphthalene-3-sulfonic acid) is replaced with 36.9 parts of 7,7'-iminobis (1-hydroxynaphthalene-3-sulfonic acid). In the same manner as above, 63.7 parts of the compound represented by the formula (6) was obtained. The maximum absorption wavelength of the compound in the 20% aqueous pyridine solution was 678 nm.

[Example 3]
It is represented by the formula (11) in the same manner as in Example 1 except that 36.0 parts of 2-aminonaphthiazole-6,8-disulfonic acid is replaced with 23.0 parts of 2-aminobenzothiazole-6-sulfonic acid. 55.4 parts of the compound was obtained. The maximum absorption wavelength of the compound in the 20% aqueous pyridine solution was 647 nm.

[Example 4]
The formula (14) was the same as in Example 1 except that 36.0 parts of 2-aminonaphthiazole-6,8-disulfonic acid was replaced with 26.0 parts of 2-amino-7-methoxybenzothiazole-6-sulfonic acid. ) Was obtained in 57.3 parts. The maximum absorption wavelength in the 20% pyridine aqueous solution was 667 nm.

[Example 5]
A diazodide was obtained from 41.9 parts of the compound represented by the formula (46) in the same manner as in Example 1, and 79.6 parts of the compound represented by the formula (5) was added to 200 parts of water. The mixture was added dropwise to the dissolved aqueous solution at pH 9 to 11, and the mixture was stirred to complete the coupling reaction. Then, it was salted out with sodium chloride and then filtered to obtain 78.4 parts of the compound represented by the formula (16). The maximum absorption wavelength of the compound in the 20% pyridine aqueous solution was 700 nm.

[Example 6]
78.4 parts of the compound represented by the formula (17) was obtained in the same manner as in Example 5 except that the compound represented by the formula (5) was replaced with the compound represented by the formula (6). The maximum absorption wavelength of the compound in the 20% aqueous pyridine solution was 701 nm.

[Example 7]
In the same manner as in Examples 1 and 5, the formula ( 65.1 parts of the compound represented by 28) were obtained. The maximum absorption wavelength of the compound in the 20% aqueous pyridine solution was 665 nm.

[Example 8]
Same as in Examples 1 and 5 except that 23.0 parts of 2-aminonaphthiazole-6,8-disulfonic acid is replaced with 26.0 parts of 2-amino-7-methoxybenzothiazole-6-sulfonic acid. , 68.1 parts of the compound represented by the formula (31) were obtained. The maximum absorption wavelength of the compound in the 20% aqueous pyridine solution was 675 nm.

[Example 9]
40.6 parts of the monoazo compound represented by the formula (47) was obtained in the same manner as in Example 1 except that 15.3 parts of 2,5-dimethoxyaniline was replaced with 13.7 parts of 2-methoxy-5-methylaniline. rice field.

Represented by formula (32) in the same manner as in Example 5 except that 41.9 parts of the compound represented by the formula (46) are replaced with a compound represented by 40.6 parts of the compound represented by the formula (47). 77.6 parts of the disazo compound to be obtained was obtained. The maximum absorption wavelength of the compound in the 20% aqueous pyridine solution was 685 nm.

[Production Example 1: Polarizing film]
A 75 μm-thick polyvinyl alcohol was immersed in a staining solution consisting of an aqueous solution of the compound of the formula (5) obtained in Example 1 at a concentration of 0.03% and Glauber's salt at a concentration of 0.1% at 45 ° C. for 4 minutes. .. This film was stretched 5 times at 50 ° C. in a 3% aqueous boric acid solution, washed with water and dried while maintaining a tense state to obtain a polarizing film.

[Production Examples 2-9, Comparative Example 1: Polarizing Film]
Instead of the compound of formula (5), formulas (6), (11), (14), (16), (17), (28), (31), (32) obtained in Examples 2 to 9 A polarizing film was obtained in the same manner as in Production Example 1 except that the azo compound of) was used. Further, as a comparative example, a polarizing film was obtained in the same manner as in the production example of the present invention using the compound of the formula (III-1) described in Example 1 in Patent Document 6.

(Measurement of maximum absorption wavelength and polarization rate of polarizing film)
The maximum absorption wavelength and the polarization rate of the polarizing films obtained in Preparation Examples 1 to 9 and Comparative Example 1 of the polarizing film were measured. The maximum absorption wavelength of the polarizing film and the calculation of the polarization rate were calculated by measuring the parallel transmittance and the orthogonal transmittance at the time of polarization incident using a spectrophotometer (manufactured by Hitachi, Ltd .; U-4100). Here, the parallel transmittance (Ky) is the transmittance when the absorption axis of the absolute polarizer and the absorption axis of the polarizing film are parallel, and the orthogonal transmittance (Kz) is the absorption axis of the absolute polarizer and the polarizing film. Indicates the transmittance when the absorption axes of are orthogonal. The parallel transmittance and the orthogonal transmittance of each wavelength were measured at 380 to 900 nm at 1 nm intervals. The polarization rate of each wavelength was calculated from the following formula (i) using the measured values, and the maximum polarization rate at 380 to 900 nm and the absorption wavelength (nm) at that time were obtained. The results are shown in Table 1.

Polarization rate (%) = [(Ky-Kz) / (Ky + Kz)] x 100 (i)

As shown in Table 1, the polarizing films prepared by using these compounds had a maximum absorption wavelength on the long wavelength side in the visible light region of about 680 to 740 nm, and all of them had a high polarization rate.

(Polarizing film color measurement)
Using the compound of formula (III-1) described in Example 1 of Patent Document 6, a polarizing film having the same transmittance as that of the polarizing film of Production Example 3 using the compound of formula (11) is obtained. These polarizing films were prepared, and the chromaticity was measured at the time of parallel and at the time of orthogonality with the above spectrophotometer. The results are shown in Table 2.

b ^{* If the} value is positive, it will be yellow, and if it is negative, it will be blue. Originally, if the polarizing film has a maximum absorption wavelength of around 610 nm, the b ^* value will be a negative value both when parallel and when orthogonal, but for a polarizing film using the compound of formula (11), will have a negative value. It was shown and had the original blue color. On the other hand, the polarizing film using the compound of the comparative example had a positive value and was visually green. From this result, it is shown that the polarizing film using the compound of the formula (11) has less secondary absorption in the region other than the maximum absorption wavelength, particularly in the region of 500 nm or less, and it is possible that it is very useful as a blue component of the three primary colors. Shows sex.

[Production Example 10: Production Example of Neutral Gray Polarizing Plate]
As a staining solution, 0.2% of the compound of the formula (17) was added to C.I. I. direct. Orange 39 0.07%, C.I. I. direct. A polarizing film was prepared in the same manner as in Preparation Example 1 except that an aqueous solution at 45 ° C. in which Red 81 had a concentration of 0.02% and Glauber's salt had a concentration of 0.1% was used. The maximum absorption wavelength of the obtained polarizing film was 555 nm, the single plate average transmittance at 380 to 700 nm was 40%, and the average light transmittance at the orthogonal position was 0.02%, which had a high degree of polarization. .. Further, the transmittance in the visible light region was almost constant in both the parallel position and the orthogonal position, and the hue was neutral gray.
One triacetyl cellulose film (TAC film; manufactured by Fuji Photo Film Co., Ltd .; trade name TD-80U) was laminated on both sides of the polarizing film via an adhesive of an aqueous polyvinyl alcohol solution. Next, an AR support (manufactured by NOF CORPORATION; Realc X4010) was laminated on one of the TAC films using an adhesive to obtain a neutral gray dye-based polarizing plate with the AR support. The obtained polarizing plate exhibited a neutral gray hue and had a high polarization ratio, similar to the polarizing film.
Furthermore, although data are not shown, the obtained polarizing plate showed durability over a long period of time even in a high temperature and high humidity state, and was also excellent in light resistance to long-term exposure.

Claims (15)

The following formula (1):

(In the formula, A ₁ and A ₂ are independently hydrogen atoms or the following formula (2):

(Wherein ring R ₁ and a sulfo group is substituted, if a ring represented by a broken line does not exist is a benzothiazole ring, naphthothiazole ring when there is a ring represented by a broken line R ₁ is a chlorine atom, a sulfo group, a nitro group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms having a sulfo group, and hydroxy. An alkyl group having 1 to 4 carbon atoms having a group, an alkyl group having 1 to 4 carbon atoms having a carboxy group, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, and an alkoxy group having 1 to 4 carbon atoms having a hydroxy group. , And selected from the group consisting of alkoxy groups having 1 to 4 carbon atoms having a carboxy group.
B is a phenylene group or a naphthylene group which may have a substituent, and the substituents are a chlorine atom, a sulfo group, a nitro group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms. , An alkyl group having 1 to 4 carbon atoms having a sulfo group, an alkyl group having 1 to 4 carbon atoms having a hydroxy group, an alkyl group having 1 to 4 carbon atoms having a carboxy group, and 1 to 4 carbon atoms having a sulfo group. It is selected from the group consisting of an alkoxy group, an alkoxy group having 1 to 4 carbon atoms having a hydroxy group, and an alkoxy group having 1 to 4 carbon atoms having a carboxy group (independently if there are a plurality of groups).
m is an integer from 1 to 3)
Represented by, except for those in which both _{A 1} and A _{2 are hydrogen atoms.}
The two -NH- bonds are independently bonded to the substitution positions indicated by a or b).
An azo compound represented by or a salt thereof. Equation (2) is the following equation (3):

(Expressed in the _formula, the _{ring R 1a} is substituted, and _{R 1a} is the same as the ring and R ₁ wherein R ₁ is substituted in equation (2),
R ₂ and R ₃ independently have a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a sulfo group having 1 to 1 carbon atoms. An alkyl group of 4, an alkyl group having 1 to 4 carbon atoms having a hydroxy group, an alkyl group having 1 to 4 carbon atoms having a carboxy group, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, and a carbon number having a hydroxy group. Selected from the group consisting of 1 to 4 alkoxy groups and 1 to 4 carbon number alkoxy groups having a carboxy group.
m ₁ has the same meaning as m in equation (2)),
Alternatively, the following formula (4):

_{(Ring R 1b} in the formula is substituted, and _{R 1b} represent the same as the ring and R ₁ wherein R ₁ is substituted in equation (2),
R _{4 to} R ₆ independently have a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a sulfo group having 1 to 1 carbon atoms. Alkyl group of 4, alkyl group having 1 to 4 carbon atoms having a hydroxy group, alkyl group having 1 to 4 carbon atoms having a carboxy group, alkoxy group having 1 to 4 carbon atoms having a sulfo group, and carbon number having a hydroxy group. Selected from the group consisting of 1 to 4 alkoxy groups and 1 to 4 carbon number alkoxy groups having a carboxy group.
m ₂ has the same meaning as m in equation (2))
The azo compound according to claim 1 or a salt thereof. The azo compound or salt thereof according to claim 2, wherein A ₁ and A ₂ are independently represented by the formula (3) or the formula (4). The azo compound or salt thereof according to claim 2, wherein A ₁ is represented by the formula (3) or the formula (4), and A _{2 is a hydrogen atom. R 1b} in the formula (4) is a hydrogen atom, a chlorine atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and R _{4 to} R ₆ are independently hydrogen atoms and carbon atoms, respectively. The azo compound or a salt thereof according to any one of claims 2 to 4, which is an alkoxy group having 1 to 4 carbon atoms which may have an alkyl group of 1 to 4 or a sulfo group. _{R 1a} in the formula (3) is a hydrogen atom, a chlorine atom or an alkyl group having 1 to 4 carbon atoms, and R ₂ and R ₃ are independently hydrogen atoms, an alkyl group having 1 to 4 carbon atoms, or a sulfo group, respectively. The azo compound or a salt thereof according to any one of claims 2 to 5, which is an alkoxy group having 1 to 4 carbon atoms which may have. The azo compound or salt thereof according to any one of claims 1 to 6, wherein the -NH- substitution position in the formula (1) is a. A dye-based polarizing film comprising the azo compound according to any one of claims 1 to 7 or a salt thereof and a polarizing film substrate. A dye-based polarizing film comprising one or more kinds of the azo compound or a salt thereof according to any one of claims 1 to 7 and other organic dyes, and a polarizing film base material. A dye-based polarizing film comprising two or more kinds of the azo compound or a salt thereof according to any one of claims 1 to 7, one or more kinds of organic dyes other than these, and a polarizing film base material. The dye-based polarizing film according to any one of claims 8 to 10, wherein the polarizing film substrate is a film formed of a polyvinyl alcohol resin or a derivative thereof. A dye-based polarizing plate obtained by laminating a transparent protective layer on at least one surface of the dye-based polarizing film according to any one of claims 8 to 11. A liquid crystal display device comprising the dye-based polarizing film according to any one of claims 8 to 11 or the dye-based polarizing plate according to claim 12. The dye-based polarizing film according to any one of claims 8 to 11, which exhibits neutral gray. Dye-based polarizing film according to claim 14, or vehicle display device or outdoor display device comprising a dye-based polarizing plate obtained by pasting a transparent protective layer on at least one surface of the dye-based polarizing film.