CN108603039B

CN108603039B - Azo compound, polarizing element and polarizing plate using the same, and display device

Info

Publication number: CN108603039B
Application number: CN201780009532.3A
Authority: CN
Inventors: 西口卓斗; 望月典明; 樋下田贵大
Original assignee: Nippon Kayaku Co Ltd; Polatechno Co Ltd
Current assignee: Nippon Kayaku Co Ltd; Polatechno Co Ltd
Priority date: 2016-02-04
Filing date: 2017-02-02
Publication date: 2020-09-01
Anticipated expiration: 2037-02-02
Also published as: HK1251789A1; TW201741402A; JPWO2017135392A1; TWI735527B; KR20180104650A; JP6862365B2; CN108603039A; WO2017135392A1

Abstract

The present invention provides a polarizing element and a polarizing plate having excellent polarizing performance and contrast, a display device having excellent contrast, and a novel azo compound useful in the polarizing element and the polarizing plate and the display device. The azo compound is represented by the following general formula (1) (wherein Ab₁Represents a substituted phenyl group or a substituted naphthyl group, Rb₁To Rb₅Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a sulfonic acid group, or an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group, Xb₁Represents an amino group which may have a substituent, a phenylamino group which may have a substituent, a benzoylamino group which may have a substituent, a phenylazo group which may have a substituent, or a naphthotriazole group which may have a substituent). The polarizing plate and the polarizing plate comprise a substrate and the azo compound. The display device is provided with the polarizing component or the polarizing plate.

Description

Azo compound, polarizing element and polarizing plate using the same, and display device

Technical Field

The present invention relates to a novel azo compound, and a polarizing element and a polarizing plate having a high degree of polarization using the azo compound, and a display device.

Background

The polarizing element is generally produced by causing iodine or a dichroic dye, which is a dichroic dye, to be adsorbed on a polyvinyl alcohol resin film in an aligned manner. A protective film made of triacetyl cellulose or the like may be bonded to at least one surface of the polarizing element with an adhesive layer interposed therebetween to form a polarizing plate. Polarizing plates, which can be used in display devices and the like. A polarizing plate using iodine as a dichroic dye is called an iodine-based polarizing plate, and a polarizing plate using a dichroic dye as a dichroic dye is called a dye-based polarizing plate. Among these, the dye-based polarizing plate is characterized by high heat resistance, high humidity and heat durability, and high stability, and by blending a dichroic dye, the color selectivity is high.

Patent documents 1 to 4 and non-patent documents 1 and 2 disclose dye-based polarizing elements containing an azo compound.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 11-218611

Patent document 2: japanese patent No. 4162334

Patent document 3: japanese patent No. 4360100

Patent document 4: japanese patent laid-open No. 2004-075719.

Non-patent document

Non-patent document 1: thin Tian Feng (dye chemistry, Tech-Prov. Purchase Ltd., 1957, 621 pages)

Non-patent document 2: "application of functional pigment" (1 st edition), CMC published by GmbH, 6 months in 2002, pages 98 to 104.

Disclosure of Invention

(problems to be solved by the invention)

However, the polarizing elements containing the conventional azo compounds described in patent documents 1 to 4 and non-patent documents 1 and 2 are not good in polarizing performance and contrast and cannot sufficiently respond to the recent demand for high-precision display alignment.

An object of the present invention is to provide a polarizing element and a polarizing plate having excellent polarizing performance and contrast, a display device having excellent contrast, and a novel azo compound which can be used in the polarizing element and the polarizing plate and the display device.

(means for solving the problems)

As a result of intensive studies to solve the above problems, the present inventors have found that a novel azo compound as a dichroic dye constituting a polarizing element and a polarizing plate can be used, and that a polarizing element and a polarizing plate having excellent polarizing performance and contrast and a display device having excellent contrast can be realized by using the azo compound, and have reached the present invention.

Namely, the present invention relates to the following:

(1) an azo compound represented by the following general formula (1) or a salt thereof.

(wherein Ab₁Represents a substituted phenyl group or a substituted naphthyl group, Rb₁To Rb₅Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a sulfonic acid group, or an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group, Xb₁Represents an amino group which may have a substituent, a phenylamino group which may have a substituent, a benzoylamino group which may have a substituent, a phenylazo group which may have a substituent, or a naphthotriazole group which may have a substituent);

(2) an azo compound represented by the following general formula (2) or a salt thereof, which is the azo compound of (1).

(wherein Ab₁Is represented by having a structure selected from the group consisting ofA phenyl group having 1 or 2 substituents selected from the group consisting of an acid group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms, or a naphthyl group having 2 or 3 substituents selected from the group consisting of a sulfonic acid group, a hydroxyl group and an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group; rb₁To Rb₅Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group; xb₁Represents a phenylamino group which may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfonic group, an amino group and an alkylamino group having 1 to 4 carbon atoms, a benzoylamino group which may have 1 substituent selected from the group consisting of a hydroxyl group, an amino group and a carboxyethylamino group, a phenylazo group which may have 1 to 3 substituents selected from the group consisting of a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an amino group and a carboxyethylamino group, or a naphthotriazolyl group substituted with 1 or 2 sulfonic groups);

(3) an azo compound of the formula (1) or (2), wherein Xb in the formula (1) or (2)₁Is a phenylamino group which may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfonic acid group, an amino group and an alkylamino group having 1 to 4 carbon atoms;

(4) a polarizing plate comprising a substrate and the azo compound described in any one of (1) to (3);

(5) a polarizing element comprising the polarizing element according to (4) and further containing an azo compound represented by the following general formula (3) or a salt thereof,

(wherein Ar is₁Represents a substituted phenyl group or a substituted naphthyl group, Rr₁To Rr₆Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group, Xr₁Represents an amino group which may have a substituent, a phenylamino group which may have a substituent, a benzoylamino group which may have a substituent, a phenylazo group which may have a substituentOr a substituted naphthotriazolyl group, m and n each independently represent 0 or 1);

(6) a polarizing element comprising the polarizing element according to (4) or (5) and further containing an azo compound represented by the following general formula (4) or a salt thereof,

(in the formula, Ay₁Represents a sulfonic acid group, a carboxyl group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, Ry₁To Ry₄Each independently represents a hydrogen atom, a sulfonic acid group, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and p represents an integer of 1 to 3);

(7) a polarizing element according to (5), wherein the azo compound represented by the general formula (3) or a salt thereof is an azo compound represented by the following general formula (5) or a salt thereof,

(wherein Ar is₁Represents a phenyl group having 1 or 2 substituents selected from the group consisting of a sulfonic acid group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms, or a naphthyl group having 2 or 3 substituents selected from the group consisting of a sulfonic acid group, a hydroxyl group and an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group; rr₁To Rr₆Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group; xr (x of X)₁Represents a phenylamino group which may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfonic group, an amino group, and an alkylamino group having 1 to 4 carbon atoms, a benzoylamino group which may have 1 substituent selected from the group consisting of a hydroxyl group, an amino group, and a carboxyethylamino group, a phenylazo group which may have 1 to 3 substituents selected from the group consisting of a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an amino group, and a carboxyethylamino group, or a naphthotriazole group substituted with 1 or 2 sulfonic acid groups; m and n are each independentlyImmediately represents 0 or 1);

(8) a polarizing plate according to (5) or (7), wherein Rr in the general formula (3) or (5)₅And Rr₆One is an alkoxy group having 1 to 4 carbon atoms, and the other is an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms;

(9) a polarizing plate according to (5) or (7), wherein Xr in the general formula (3) or (5)₁Is phenylamino which may have 1 or 2 substituents selected from the group consisting of methyl, methoxy, sulfonic acid, amino and alkylamino having 1 to 4 carbon atoms, or benzoylamino which may have 1 substituent selected from the group consisting of hydroxy, amino and carboxyethylamino;

(10) a polarizing plate comprising the polarizing plate of (6), wherein Ay in the general formula (4)₁Is carboxyl or sulfonic group;

(11) a polarizing plate assembly according to any one of (4) to (10), wherein the substrate is a film formed of polyvinyl alcohol or a derivative thereof;

(12) a polarizing plate comprising the polarizing element according to any one of (4) to (11), and a transparent protective layer provided on at least one surface of the polarizing element;

(13) a display device comprising the polarizing plate according to any one of (4) to (11) or the polarizing plate according to (12).

(Effect of the invention)

According to the present invention, a polarizing element and a polarizing plate having excellent polarizing performance and contrast, a display device having excellent contrast, and a novel azo compound useful for the polarizing element and the polarizing plate and the display device can be provided.

Detailed Description

The present invention will be described in detail below.

[ novel azo Compound ]

The azo compound of the present invention is an azo compound represented by the following general formula (1) or a salt thereof. The azo compound of the present invention is a water-soluble dye that functions as a dye, which is generally called a dichroic dye.

In the general formula (1), Ab₁Represents a substituted phenyl group or a substituted naphthyl group, Rb₁To Rb₅Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a sulfonic acid group or an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group, Xb₁Represents an amino group which may have a substituent (excluding a phenyl group and a benzoyl group), a phenylamino group which may have a substituent, a benzoylamino group which may have a substituent, a phenylazo group which may have a substituent, or a naphthotriazole group which may have a substituent.

The azo compound represented by the general formula (1) is preferably an azo compound represented by the following general formula (2). This can further improve the polarizing performance of the polarizing element using the azo compound represented by the general formula (1).

(wherein Ab₁、Rb₁To Rb₅And Xb₁Represents the same meaning as in the general formula (1)

Ab in the above general formula (1) or (2)₁The substituent-containing phenyl group or substituent-containing naphthyl group is preferably a phenyl group having 1 or 2 substituents selected from the group consisting of a sulfonic acid group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms, or a naphthyl group having 2 or 3 substituents selected from the group consisting of a sulfonic acid group, a hydroxyl group and an alkoxy group having 1 to 4 carbon atoms.

Ab in the above general formula (1) or (2)₁In the case of a substituted phenyl group, it is preferable that the substituted phenyl group has at least 1 sulfonic acid group or carboxyl group. Ab₁In the case of a phenyl group having 2 or more substituents, among these substituents, (some of) at least 1 substituent is a sulfonic acid group or a carboxyl group, and the other substituents are a sulfonic acid group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms, a substituted phenyl group, a substituted phenyl,An alkoxy group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms with a sulfonic acid group, a nitro group, an amino group, an acetylamino group, or an alkylamino group having 1 to 4 carbon atoms is preferable. The substituent on the phenyl group is more preferably a sulfonic acid group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a nitro group, an amino group or a carboxyl group, and particularly preferably a sulfonic acid group, a methyl group, a methoxy group, an ethoxy group or a carboxyl group. The number of substituents on the phenyl group is preferably 2. The substitution position of the substituent on the phenyl group is not particularly limited, but when the number of the substituents on the phenyl group is 2, a combination of the 2-position and the 4-position is preferable.

Ab in the above general formula (1) or (2)₁In the case of a substituted naphthyl group, it is preferable that the substituted naphthyl group has at least 1 sulfonic acid group. At Ab₁In the case of a naphthyl group having 2 or more substituents, among these substituents, at least 1 substituent (part of) is a sulfonic acid group, and the other substituents are a sulfonic acid group, a hydroxyl group, a carboxyl group or an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group. When the number of substituents on the naphthyl group is 2, the combination of the substitution positions of these substituents is preferably the combination of the 4-position and the 8-position or the combination of the 6-position and the 8-position, and particularly preferably the combination of the 6-position and the 8-position. When the number of substituents on the naphthyl group is 3, the combination of the substitution positions of these substituents is particularly preferable in combination of the 1-position and the 3-and 6-positions.

As Ab₁The alkoxy group having 1 to 4 carbon atoms of a sulfonic acid group as a substituent on the phenyl group or the naphthyl group in (1) is preferably a linear alkoxy group having 1 to 4 carbon atoms of a sulfonic acid group. Among the alkoxy groups having 1 to 4 carbon atoms of a sulfonic acid group, the substitution position of the sulfonic acid group is preferably an alkoxy terminal. The alkoxy group having a sulfonic acid group and having a carbon number of 1 to 4 is more preferably a 3-sulfopropoxy group or a 4-sulfobutoxy group, and particularly preferably a 3-sulfopropoxy group.

Xb in the general formula (1) or (2)₁Although it represents an amino group which may have a substituent (excluding a phenyl group and a benzoyl group), a phenylamino group which may have a substituent, a benzoylamino group which may have a substituent, a phenylazo group which may have a substituent, or a naphthotriazole group which may have a substituent; but preferably: may have a substituent selected from methylA phenylamino group having 1 or 2 substituents selected from the group consisting of a methoxy group, a sulfonic group, an amino group and an alkylamino group having 1 to 4 carbon atoms, a benzoylamino group which may have 1 substituent selected from the group consisting of a hydroxy group, an amino group and a carboxyethylamino group, a phenylazo group which may have 1 to 3 substituents selected from the group consisting of a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an amino group and a carboxyethylamino group, or a naphthotriazolyl group substituted with 1 or 2 sulfonic acid groups; more preferably: a phenylamino group which may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfonic acid group, an amino group and an alkylamino group having 1 to 4 carbon atoms, or a benzoylamino group which may have 1 substituent selected from the group consisting of a hydroxyl group, an amino group and a carboxyethylamino group; still more preferably: a phenylamino group which may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfonic acid group, an amino group and an alkylamino group having 1 to 4 carbon atoms. The substitution position of the substituent is not particularly limited, but Xb₁In the case of a phenylamino group having 1 substituent, a benzoylamino group having 1 substituent or a phenylazo group having 1 substituent, the para-position is particularly preferred.

Rb in the formula (1) or (2)₁To Rb₅Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group, and is preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and more preferably a hydrogen atom, a methyl group, or a methoxy group. And Rb is used for improving optical characteristics₁And Rb₂And Rb₃And Rb₄The combination of the substitution positions of (a) is preferably a combination of 2-position and 6-position, a combination of 2-position and 5-position or a combination of 3-position and 5-position, and more preferably a combination of 2-position and 5-position, respectively. Rb₅The substitution position(s) of (2) is preferably a 2-position or a 3-position, and more preferably a 2-position. Rb₁And Rb₂And Rb₃And Rb₄When the combination of the substitution positions (a) and (b) is independently at least one methoxy group, the combination of the 2-position and the 6-position, the combination of the 2-position and the 5-position or the combination of the 3-position and the 5-position is preferred, and the 2-position is usedThe combination with the 5-position is more preferred.

The following describes a method for producing the azo compound represented by the general formula (1). The azo compound represented by the above general formula (1) can be produced by the same production method as a known production method, and therefore the production method of the azo compound represented by the above general formula (1) is not limited to the production method described herein. For example, the azo compound represented by the above general formula (1) can be easily produced by a known method for producing an azo dye, such as that described in non-patent document 1, by diazotization and coupling.

The azo compound represented by the general formula (1) can be produced in the following manner. First, a monoazo amino compound represented by the following general formula (6) was obtained.

(wherein Ab₁、Rb₁And Rb₂Represents the same meaning as in the above general formulae (1) and (2)

Monoazo amino compound represented by the above general formula (6) as Ab₁In the case of a phenyl group having at least 1 sulfonic acid group, the aromatic amine represented by the following general formula (7) can be obtained by diazotizing a sulfonic acid alkoxyaniline obtained by sulfonic acid alkylation using a known method and coupling it 1 time with an aniline represented by the following general formula (8).

(in the formula, Rb₁₁And Rb₁₂One represents a sulfonic acid group or a carboxyl group, and the other represents a sulfonic acid group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a nitro group, an amino group, an acetylamino group, or an alkylamino group having 1 to 4 carbon atoms, or the compound represented by the general formula (7) may be 4-aminobenzenesulfonic acid, 3-aminobenzenesulfonic acid, 2-aminobenzenesulfonic acid, or 4-aminobenzoic acid)

(in the formula, Rb₁And Rb₂Represents the same meaning as in the above general formulae (1) and (2)

Monoazo amino compound represented by the above general formula (6) as Ab₁In the case of a naphthyl group having at least 1 sulfonic acid group, a sulfonic acid alkoxynaphthylamine sulfonic acid group obtained by sulfonic acid alkylation of a naphthylamine sulfonic acid group or an aminonaphthol sulfonic acid group represented by the following general formula (9) by a known method is diazotized and coupled 1 time with an aniline represented by the above general formula (8).

(in the formula, Rb₁₃Represents a hydrogen atom, a hydroxyl group, a carboxyl group, a sulfonic acid group, a tosylated hydroxyl group, an amino group, a substituted amino group, a nitro group, a substituted amide group, or an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group, q represents an integer of 1 to 3)

Next, the monoazo amino compound represented by the above general formula (6) is diazotized and coupled 2 times with the aniline represented by the following general formula (10), to obtain a disazo amino compound represented by the following general formula (11).

(in the formula, Rb₃And Rb₄Represents the same meaning as in the above general formula (1) and general formula (2)

(wherein Ab₁、Rb₁、Rb₂、Rb₃And Rb₄Represents the same meaning as in the above general formula (1) and general formula (2)

Then, the bisazo amino compound represented by the general formula (11) is diazotized and coupled with the aniline represented by the general formula (12) 3 times to obtain a trisazo amino compound represented by the general formula (13).

(wherein Ab₁And Rb₁To Rb₅Represents the same meaning as in the general formulae (1) and (2)

Next, the trisazo amino compound represented by the above general formula (13) is diazotized by a known method and coupled 4 times with the naphthol represented by the following general formula (14), whereby the tetrazo compound represented by the following general formula (15) can be obtained.

(in the formula, Xb₁Represents the same meaning as in the above general formulae (1) and (2)

(wherein Ab₁、Rb₁To Rb₅And Xb₁Represents the same meaning as in the above general formulae (1) and (2)

To the tetrazo compound represented by the general formula (15), a copper complex salt compound of copper sulfate and at least 1 selected from the group consisting of ammonia water, aminoalcohol and hexamethylenetetramine is added, and a cuprinization reaction is preferably carried out at 85 to 95 ℃, whereby a copper-complexed azo compound represented by the general formula (1) or the general formula (2) is obtained.

The diazotization step in the above synthesis may be carried out by a forward method of mixing a nitrite such as sodium nitrite in an aqueous solution or suspension of a mineral acid such as hydrochloric acid or sulfuric acid as a diazotization component, or by a reverse method of adding a nitrite to a neutral or weakly alkaline aqueous solution of a diazotization component in advance and mixing it with a mineral acid. The temperature of the diazotization is suitably from-10 to 40 ℃. The step of coupling the diazonium compound to the anilines is carried out by mixing an acidic aqueous solution such as hydrochloric acid or acetic acid with each of the diazonium solutions (aqueous solution or suspension of the diazonium compound) under acidic conditions of-10 to 40 ℃ and a pH of 2 to 7.

The monoazo amino compound, disazo amino compound and trisazo amino compound obtained by coupling may be separated out directly or by acid precipitation or salting out, and then filtered and taken out, or the solution or suspension may be maintained to be directly subjected to the next step. When the diazonium salt is sparingly soluble and forms a suspension, it may be filtered to form a presscake and used in the next coupling step.

The 4-time coupling reaction of the diazotized trisazo amino compound represented by the general formula (13) with the naphthol represented by the general formula (14) is carried out under neutral to basic conditions at a temperature of-10 to 40 ℃ and a pH of 7 to 10. After the reaction is completed, the salt is precipitated by salting out and is taken out by filtering. When purification is required, salting out may be repeated or precipitation from water may be carried out by using an organic solvent. Examples of the organic solvent used for purification include: alcohols such as methanol and ethanol; water-soluble organic solvents such as ketones, e.g., acetone.

The aromatic amine represented by the general formula (7) is Ab₁Starting materials (starting material compounds) for azo compounds represented by the above general formula (1) in the case of a substituted phenyl group, wherein Rb is an aromatic amine represented by the general formula (7)₁₁And Rb₁₂Examples thereof include a hydrogen atom, a sulfonic acid group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group, a naphthotriazolyl group substituted with a sulfonic acid group or the like, a nitro group, an amino group, an acetylamino group, and an alkylamino group having 1 to 4 carbon atoms. Rb₁₁And Rb₁₂Preferably a hydrogen atom, a sulfonic acid group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and Rb₁₁And Rb₁₂Is more preferably a sulfonic acid group, and Rb is₁₁And Rb₁₂The number of substituents of (2) (i.e., Rb)₁₁And Rb₁₂Both are not hydrogen atoms) are still more preferred. The alkoxy group having a sulfonic acid group and 1 to 4 carbon atoms is preferably a linear alkoxy group having a sulfonic acid group and 1 to 4 carbon atomsAnd (4) selecting. Among the alkoxy groups having 1 to 4 carbon atoms and having a sulfonic acid group, the substitution position of the sulfonic acid group is preferably an alkoxy terminal. The alkoxy group having a sulfonic acid group and having 1 to 4 carbon atoms is more preferably a 3-sulfopropoxy group or a 4-sulfobutoxy group.

Examples of the aromatic amines represented by the general formula (7) include: 4-aminobenzenesulfonic acid, 3-aminobenzenesulfonic acid, 2-aminobenzenesulfonic acid, 4-aminobenzoic acid, 2-amino-5-methylbenzenesulfonic acid, 2-amino-5-methoxybenzenesulfonic acid, 4-amino-2-methylbenzenesulfonic acid, 3-amino-4-methoxybenzenesulfonic acid, 2-amino-4-sulfobenzoic acid, 2-amino-5-sulfobenzoic acid and the like, 5-aminoisophthalic acid, 2-amino-5-nitrobenzenesulfonic acid, 5-acetamide-2-aminobenzenesulfonic acid, 2-amino-5- (3-sulfopropoxy) benzenesulfonic acid, 4-aminobenzene-1, 3-disulfonic acid, 2-aminobenzene-1, 4-disulfonic acid, etc., and 4-aminobenzenesulfonic acid, 2-amino-5-methoxybenzenesulfonic acid, 4-amino-2-methylbenzenesulfonic acid, 4-aminobenzene-1, 3-disulfonic acid are particularly preferred. The aromatic amines represented by the general formula (7) may have a naphthotriazolyl group as a substituent on the phenyl group. Examples of the naphthotriazole group include a 6, 8-disulfonic naphthotriazole group, a 7, 9-disulfonic naphthotriazole group, a 7-sulfonic naphthotriazole group, and a 5-sulfonic naphthotriazole group. In this case, the naphthotriazolyl group is particularly preferred in the para-position of the phenyl group.

The naphthylamine sulfonic acid represented by the general formula (9) is Ab₁A starting material (starting material compound) for an azo compound represented by the general formula (1) in the case of a substituted naphthyl group, wherein Rb of the naphthylamine sulfonic acid group represented by the general formula (9)₁₃The hydroxyl group is a hydrogen atom, a hydroxyl group, a carboxyl group, a sulfonic acid group, a tosylated hydroxyl group, an amino group, a substituted amino group, a nitro group, a substituted amide group, or an alkoxy group having a sulfonic acid group and having 1 to 4 carbon atoms, but a hydrogen atom, a sulfonic acid group, or an alkoxy group having a sulfonic acid group and having 1 to 4 carbon atoms is preferable. In addition, Rb₁₃Hydrogen atom, hydroxyl group, carboxyl group, or lower alkoxy group having a sulfonic acid group is preferable. The alkoxy group having a sulfonic acid group and having 1 to 4 carbon atoms is preferably a linear alkoxy group having a sulfonic acid group and having 1 to 4 carbon atoms. In the C1-4 alkoxy group having a sulfonic acid group, the substitution position of the sulfonic acid group is the alkoxy groupThe terminal group is preferred. The alkoxy group having a sulfonic acid group and having 1 to 4 carbon atoms is preferably a 3-sulfopropoxy group or a 4-sulfobutoxy group. In the naphthylamine sulfonic acids represented by the general formula (9), the substitution position of the sulfonic acid group may be on any benzene nucleus of the naphthalene ring. When the number q of sulfonic acid groups is 1, the substitution position of the sulfonic acid group is preferably any one of the 1-position, 3-position and 6-position, and when the number q of sulfonic acid groups is 2 or 3, the combination of the substitution positions of the sulfonic acid groups is preferably 2 or 3 selected from the group consisting of the 1-position, 3-position, 6-position and 7-position.

The naphthylamine sulfonic acids represented by the general formula (9) include, for example: 2-aminonaphthalene-1-sulfonic acid, 8-aminonaphthalene-1-sulfonic acid, 5-aminonaphthalene-2-sulfonic acid, 8-aminonaphthalene-2-sulfonic acid, 3-aminonaphthalene-1-sulfonic acid, 6-aminonaphthalene-2-sulfonic acid, 4-aminonaphthalene-1-sulfonic acid, 7-aminonaphthalene-1, 3-disulfonic acid, 6-aminonaphthalene-1, 3-disulfonic acid, 3-amino-7-nitronaphthalene-1, 5-disulfonic acid, 4-aminonaphthalene-1, 6-disulfonic acid, 4-aminonaphthalene-1, 5-disulfonic acid, 5-aminonaphthalene-1, 3-disulfonic acid, 3-aminonaphthalene-1, 5-disulfonic acid, 2-aminonaphthalene-1, 5-disulfonic acid, 7-aminonaphthalene-1, 3, 6-trisulfonic acid, 7-aminonaphthalene-1, 3, 5-trisulfonic acid, 8-aminonaphthalene-1, 3, 6-trisulfonic acid, 5-aminonaphthalene-1, 3, 6-trisulfonic acid, 7-amino-3- (3-sulfopropoxy) naphthalene-1-sulfonic acid, 7-amino-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, naphthalene-2-sulfonic acid, 6-amino-4- (3-sulfopropoxy) naphthalene-2-sulfonic acid, 6-amino-4- (4-sulfobutoxy) naphthalene-2-sulfonic acid, 2-amino-5- (3-sulfopropoxy) naphthalene-1, 7-disulfonic acid, 6-amino-4- (3-sulfopropoxy) naphthalene-2, 7-disulfonic acid, or 7-amino-3- (3-sulfopropoxy) naphthalene-1, 5-disulfonic acid, but 7-aminonaphthalene-1, 3-disulfonic acid, 6-aminonaphthalene-1, 3-disulfonic acid, 7-aminonaphthalene-1, 3, 6-trisulfonic acid, 7-amino-4- (3-sulfopropoxy) naphthalene-2-sulfonaphthalene The acid, 6-amino-4- (3-sulfopropoxy) naphthalene-2-sulfonic acid is preferred, and 7-aminonaphthalene-1, 3-disulfonic acid, 7-aminonaphthalene-1, 3, 6-trisulfonic acid, and 7-amino-4- (3-sulfopropoxy) naphthalene-2-sulfonic acid are particularly preferred.

Rb which is contained in the aniline represented by the general formula (8) which is a 1-fold coupling component₁And Rb₂And Rb which is contained in the aniline represented by the general formula (10) belonging to the 2-fold coupling component₃And Rb₄Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group, but a hydrogen atom, a methyl group, a methoxy group, a 3-sulfopropoxy group, a 4-sulfobutoxy group and a hydrogen atom, a methyl group or a methoxy group are preferable. Rb₁And Rb₂And Rb₃And Rb₄The combination of the substitution positions of (a) is preferably a combination of the 2-position and the 6-position, a combination of the 2-position and the 5-position, or a combination of the 3-position and the 5-position, and more preferably a combination of the 2-position and the 5-position, each independently and with respect to the amino group. The anilines having an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group which can be used as the anilines represented by the general formula (8) and the anilines represented by the general formula (10) include 3- (2-amino-4-methylphenoxy) propane-1-sulfonic acid, 3- (2-aminophenoxy) propane-1-sulfonic acid, and 3- (2-amino-4-methylphenoxy) butane-1-sulfonic acid. Examples of the aniline other than the aniline that can be used as the aniline represented by the general formula (8) and the aniline represented by the general formula (10) include: 2, 5-dimethylaniline, 2, 5-diethylaniline, 2-methoxy-5-methylaniline, 2, 5-dimethoxyaniline, 3, 5-dimethylaniline, 2, 6-dimethylaniline or 3, 5-dimethoxyaniline, etc. These anilines may be anilines in which an amino group is protected with a protecting group. Examples of the protecting group include: its omega-methanesulfonate group. The aniline represented by the general formula (8) used in the 1-time coupling and the aniline represented by the general formula (10) used in the 2-time coupling may be the same or different.

The aniline having a methoxy group represented by the general formula (12) which is a 3-fold coupling component may be any aniline having a methoxy group at the ortho-position to the amino group, but 2, 5-dimethoxyaniline, 2-methoxyaniline, and 2-methoxy-5-methylaniline are preferable.

A substituent Xb of the naphthol represented by the above general formula (14) which is a 4-degree coupling component₁The formula (I) represents an amino group which may have a substituent (excluding a phenyl group and a benzoyl group), a phenylamino group which may have a substituent, or a substituted amino groupA benzoylamino group, a phenylazo group which may have a substituent, or a naphthotriazole group which may have a substituent; but preferably: a phenylamino group which may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfonic group, an amino group and an alkylamino group having 1 to 4 carbon atoms, a benzoylamino group which may have 1 substituent selected from the group consisting of a hydroxyl group, an amino group and a carboxyethylamino group, a phenylazo group which may have 1 to 3 substituents selected from the group consisting of a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an amino group and a carboxyethylamino group, or a naphthotriazolyl group substituted with 1 or 2 sulfonic groups; more preferably: a phenylamino group which may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfonic acid group, an amino group and an alkylamino group having 1 to 4 carbon atoms, or a benzoylamino group which may have 1 substituent selected from the group consisting of a hydroxyl group, an amino group and a carboxyethylamino group; still more preferably: a phenylamino group which may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfonic acid group, an amino group and an alkylamino group having 1 to 4 carbon atoms. Xb₁When it is a phenylamino group having 1 substituent, a benzoylamino group having 1 substituent or a phenylazo group having 1 substituent, the substitution position of the substituent is not particularly limited, but Xb₁In the case of a phenylamino group having 1 substituent, a benzoylamino group having 1 substituent or a phenylazo group having 1 substituent, the para-position is particularly preferred.

The azo compound of the present invention may exist in the form of a free acid represented by the above general formula (1) or in the form of a salt thereof. Examples of the salt include: alkali metal salts, alkaline earth metal salts, alkylamine salts, alkanolamine salts, ammonium salts, and the like. The salt is preferably a sodium salt, a potassium salt or an ammonium salt when used for dyeing a base material for a polarizing element. The azo compound represented by the general formula (1) can be isolated as a free acid by adding mineral acid after the coupling reaction, and the isolated azo compound represented by the general formula (1) can be washed with water or acidified water to remove inorganic salts from the isolated azo compound represented by the general formula (1). Thus, an acid-type azo compound represented by the general formula (1) having a low salt content can be obtained. Then, the acid-form azo compound represented by the general formula (1) is neutralized with a desired inorganic or organic base in an aqueous solvent to obtain a solution of a corresponding salt. Or in the case of salting out after the coupling reaction, the azo compound represented by the general formula (1) may be used as a sodium salt using, for example, sodium chloride, or the azo compound represented by the general formula (1) may be used as a potassium salt using, for example, potassium chloride. Thus, the azo compound represented by the general formula (1) can be a desired salt.

Specific examples of the azo compound represented by the general formula (1) or (2) or a salt thereof in the present invention are shown below. In addition, examples of the compounds are shown in the form of free acids.

(Compound example 1)

(Compound example 2)

(Compound example 3)

(Compound example 4)

(Compound example 5)

(Compound example 6)

(Compound example 7)

(Compound example 8)

(Compound example 9)

(Compound example 10)

(Compound example 11)

(Compound example 12)

(Compound example 13)

(Compound example 14)

(Compound example 15)

(Compound example 16)

(Compound example 17)

(Compound example 18)

[ polarizing component ]

The polarizing element of the present invention comprises a substrate and the azo compound of the present invention. The azo compound of the present invention is preferably adsorbed on the substrate. The azo compound that can be used as a dye in the polarizing element of the present invention can be produced by diazotization and coupling, which are well known in the art, in accordance with the synthesis method of an azo dye known in the art (for example, page 626 of non-patent document 1). The base material is impregnated with the solution of the azo compound in the dyeing step, whereby the polarizing element can be produced.

The polarizing element of the present invention preferably further contains an azo compound represented by the following general formula (3) or a salt thereof, which is a dichroic dye, in addition to the azo compound of the present invention described above.

Therefore, the polarizing component with higher polarizing performance can be realized. The azo compound represented by the general formula (3) or a salt thereof is preferably adsorbed on the substrate.

In the general formula (3), Ar₁Represents a substituted phenyl group or a substituted naphthyl group, Rr₁To Rr₆Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group, Xr₁Represents an amino group which may have a substituent (excluding a phenyl group and a benzoyl group),A phenylamino group which may have a substituent, a benzoylamino group which may have a substituent, a phenylazo group which may have a substituent or a naphthotriazole group which may have a substituent, and m and n each independently represent 0 or 1.

The azo compound represented by the general formula (3) is preferably an azo compound represented by the following general formula (5).

(wherein Ar is₁、Rr₁To Rr₆、Xr₁Represents the same meaning as in the general formula (3)

In the above general formula (3) or (5), Ar₁Represents a substituted phenyl group or a substituted naphthyl group, Rr₁To Rr₆Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group, Xr₁Represents an amino group which may have a substituent (excluding a phenyl group and a benzoyl group), a phenylamino group which may have a substituent, a benzoylamino group which may have a substituent, a phenylazo group which may have a substituent, or a naphthotriazole group which may have a substituent, and m and n each independently represent 0 or 1.

Rr in the above general formula (3) or (5)₁To Rr₆Each of these groups is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and particularly preferably a hydrogen atom or a methyl group. Rr in the above general formula (3) or (5)₅And Rr₆Preferably, one is an alkoxy group having 1 to 4 carbon atoms, and the other is an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.

Xr in the aforementioned general formula (3) or (5)₁Preferably, the substituted amino group is a phenylamino group which may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfonic acid group, an amino group and an alkylamino group having 1 to 4 carbon atoms, the substituted amino group is a benzoylamino group which may have 1 substituent selected from the group consisting of a hydroxyl group, an amino group and a carboxyethylamino group, and the substituted amino group is a benzoylamino group which may have 1 to 3 substituents selected from the group consisting of a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an amino group and a carboxyethylamino groupPhenylazo radical of the group, or naphthotriazolyl substituted by 1 or 2 sulfonic acid groups; more preferably a phenylamino group which may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfonic group, an amino group and an alkylamino group having 1 to 4 carbon atoms, a benzoylamino group which may have 1 substituent selected from the group consisting of a hydroxyl group, an amino group and a carboxyethylamino group, or a naphthotriazolyl group substituted with 1 or 2 sulfonic groups; particularly preferred is a phenylamino group which may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfonic acid group, an amino group, or a benzoylamino group which may have 1 substituent selected from the group consisting of a hydroxyl group, an amino group and a carboxyethylamino group.

Ar in the above general formula (3) or (5)₁Although the phenyl group or the naphthyl group has a substituent, the phenyl group preferably has 1 or 2 substituents selected from the group consisting of a sulfonic acid group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms, or the naphthyl group preferably has 2 or 3 substituents selected from the group consisting of a sulfonic acid group, a hydroxyl group and an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group.

Ar in the above general formula (3) or (5)₁Among them, the substituent on the phenyl group is preferably a sulfonic acid group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms having a sulfonic acid group, a naphthotriazole group substituted with a sulfonic acid group, a nitro group, an amino group, an acetylamino group, or an alkylamino group having 1 to 4 carbon atoms. Ar in the above general formula (3) or (5)₁Among them, the substituent on the naphthyl group is preferably a sulfonic acid group, a hydroxyl group, or an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group. Ar in the above general formula (3) or (5)₁The phenyl group or naphthyl group having 1 or more sulfonic acid groups or carboxyl groups is preferable, and the phenyl group or naphthyl group having 2 or more sulfonic acid groups or carboxyl groups is more preferable for improving durability. Ar in the above general formula (3) or (5)₁In order to further improve the polarizing properties and to produce a neutral-color polarizing element, a phenyl group having a sulfonic acid group or a carboxyl group is more preferable.

In the general formula (3), m and n may be 0 or 1 independently, but in order to obtain good polarizing performance in the polarizing element of the present invention, at least one of m and n is preferably 1, and more preferably both m and n are 1. The substituted amino group is not particularly limited, and may contain, for example, an amino group substituted with an alkyl group or an acyl group having 1 to 4 carbon atoms. Further, the substituted amide group is not particularly limited, but may contain an amide group substituted with an alkyl group having 1 to 4 carbon atoms, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent.

The azo compound represented by the above general formula (3) or a salt thereof can be produced by, for example, the methods described in Japanese patent application laid-open No. 9-302250, Japanese patent No. 4662853, International publication No. 2012/108169, International publication No. 2012/108173, etc., but the method is not limited thereto.

Examples of the azo compound represented by the above general formula (3) or a salt thereof include, but are not limited to, C.I. direct Red 81, C.I. direct Red 117, C.I. direct Red 127, an azo compound described in International publication No. 2005/075572 (for example, the azo compound described in example 1 of International publication No. 2005/075572), a dye described in Japanese patent No. 4662853, a dye described in International publication No. 2013/008735, an azo compound described in Japanese examined patent publication No. 2-61988, an azo compound described in Japanese patent application laid-open No. 2013-57909, an azo compound described in International publication No. 2012/108169 (for example, the azo compound represented by the formula (8), (9), (10), (17), (21) of International publication No. 2012/108169), and the like.

The azo compound represented by the general formula (3) or a salt thereof may be contained in the polarizer in the form of a free acid represented by the general formula (3), or may be contained in the polarizer in the form of a salt of the azo compound represented by the general formula (3). The salt may be an alkali metal salt such as a lithium salt, a sodium salt, or a potassium salt, or an organic salt such as an ammonium salt or an alkylamine salt. The salt is preferably a lithium salt or a sodium salt, and more preferably a sodium salt.

Next, specific examples of the azo compound represented by the general formula (3) or a salt thereof which can be used in the polarizing element of the present invention are given below. In the following compound examples, substituents such as a sulfonic acid group, a carboxyl group, and a hydroxyl group are shown in the form of free acids, but these substituents may be in the form of salts. (Compound example 19)

(Compound example 20)

(Compound example 21)

(Compound example 22)

(Compound example 23)

(Compound example 24)

(Compound example 25)

(Compound example 26)

(Compound example 27)

(Compound example 28)

(Compound example 29)

(Compound example 30)

(Compound example 31)

(Compound example 32)

(Compound example 33)

(Compound example 34)

(Compound example 35)

(Compound example 36)

(Compound example 37)

(Compound example 38)

(Compound example 39)

(Compound example 40)

(Compound example 41)

(Compound example 42)

(Compound example 43)

(Compound example 44)

(Compound example 45)

(Compound example 46)

(Compound example 47)

(Compound example 48)

(Compound example 49)

(Compound example 50)

(Compound example 51)

(Compound example 52)

(Compound example 53)

(Compound example 54)

(Compound example 55)

(Compound example 56)

(Compound example 57)

(Compound example 58)

(Compound example 59)

(Compound example 60)

(Compound example 61)

(Compound example 62)

(Compound example 63)

(Compound example 64)

(Compound example 65)

(Compound example 66)

(Compound example 67)

(Compound example 68)

(Compound example 69)

(Compound example 70)

(Compound example 71)

(Compound example 72)

(Compound example 73)

(Compound example 74)

(Compound example 75)

(Compound example 76)

(Compound example 77)

(Compound example 78)

(Compound example 79)

(Compound example 80)

(Compound example 81)

(Compound example 82)

(Compound example 83)

(Compound example 84)

(Compound example 85)

(Compound example 86)

(Compound example 87)

(Compound example 88)

(Compound example 89)

(Compound example 90)

(Compound example 91)

(Compound example 92)

(Compound example 93)

(Compound example 94)

(Compound example 95)

(Compound example 96)

(Compound example 97)

(Compound example 98)

(Compound example 99)

(Compound example 100)

(Compound example 101)

(Compound example 102)

(Compound example 103)

(Compound example 104)

(Compound example 105)

(Compound example 106)

(Compound example 107)

In the polarizing element of the present invention, the content of the azo compound represented by the general formula (3) or a salt thereof is preferably in the range of 1 to 200 parts by weight, and more preferably in the range of 50 to 100 parts by weight, relative to 100 parts by weight of the content of the azo compound represented by the general formula (1) or a salt thereof of the present invention.

The polarizing element of the present invention preferably contains an azo compound represented by the following general formula (4) or a salt thereof in addition to the azo compound represented by the general formula (1) or a salt thereof in the present invention,

and two more preferable examples of the azo compound represented by the general formula (3) or a salt thereof and the azo compound represented by the general formula (4) or a salt thereof are further contained. Therefore, the polarizing component with higher polarization degree can be realized. The azo compound represented by the general formula (4) or a salt thereof is preferably adsorbed on the substrate.

In the above general formula (4), Ay₁Represents a sulfonic acid group, a carboxyl group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, Ry₁To Ry₄Each independently represents a hydrogen atom, a sulfonic acid group, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and p represents an integer of 1 to 3. Ay in the above general formula (4)₁The carboxyl group or the sulfonic acid group is preferable.

The method for synthesizing the azo compound represented by the general formula (4) or a salt thereof can be, for example, a method described in non-patent document 1 or a method described in international publication No. 2007/138980, but is not limited thereto.

As the azo compound represented by the above general formula (4) or a salt thereof, for example: C.I. direct yellow 12, C.I. direct yellow 72, C.I. direct orange 39(CAS number: 1325-54-8), azo compounds described in International publication No. 2007/138980 (for example, azo compounds of Compound example 111 described in example 1 of International publication No. 2007/138980), but are not limited thereto.

The azo compound represented by the general formula (4) or a salt thereof may be contained in the polarizer in the form of a free acid represented by the general formula (4), or may be contained in the polarizer in the form of a salt of the azo compound represented by the general formula (4). The salt may be an alkali metal salt such as a lithium salt, a sodium salt, or a potassium salt, or an organic salt such as an ammonium salt or an alkylamine salt. The salt is preferably a lithium salt or a sodium salt, and more preferably a sodium salt.

Next, specific examples of the azo compound represented by the general formula (4) or a salt thereof which can be used for the polarizing element of the present invention are given below. In the following compound examples, the sulfonic acid group and the carboxyl group are shown as free acids, but the sulfonic acid group and the carboxyl group may be in the form of salts.

(Compound example 108)

(Compound example 109)

(Compound example 110)

(Compound example 111)

In the polarizing element of the present invention, the content of the azo compound represented by the general formula (4) or a salt thereof is preferably in the range of 1 to 200 parts by weight, and more preferably in the range of 50 to 100 parts by weight, relative to 100 parts by weight of the content of the azo compound represented by the general formula (1) or a salt thereof of the present invention.

In the polarizing element of the present invention, 1 or more kinds of organic dyes other than the azo compounds represented by each of the general formulae (1), (3), and (4) or salts thereof (for example, the azo compounds described in non-patent document 2) and the azo compound represented by the general formula (1) or a salt thereof of the present invention may be used in combination with color adjustment or the like. The other organic dye to be used in combination is not particularly limited, but is preferably a dye which is obtained by dyeing a hydrophilic polymer and has absorption characteristics in a wavelength region different from the absorption wavelength region of the azo compound represented by the general formula (1) or a salt thereof of the present invention, and has high dichroism. Other organic dyes, for example: an azo compound described in non-patent document 2 (for example, c.i. direct yellow 28), or c.i. direct red 2, c.i. direct red 31, c.i. direct red 79, c.i. direct red 247, c.i. direct green 80, c.i. direct green 59, c.i. direct blue 202, c.i. direct violet 9, and the like. These azo compounds can be used in the form of a free acid or in the form of a salt such as an alkali metal salt (e.g., sodium salt, potassium salt, lithium salt), ammonium salt, or amine salt. When other organic dyes are used in combination as necessary, the types of the other organic dyes to be blended are different depending on which of a more neutral color polarizing element, a polarizing element having a characteristic color, a color polarizing element for a liquid crystal projector, and other color polarizing elements the target polarizing element belongs to. The amount of the other organic dye to be blended (in the case of two or more, the total amount of these organic dyes to be blended) is not particularly limited, but is generally preferably in the range of 0.1 to 10 parts by weight based on 100 parts by weight of the total amount of the azo compound represented by the general formula (1) or a salt thereof, the azo compound represented by the general formula (3) or a salt thereof, and the azo compound represented by the general formula (4) or a salt thereof in the present invention.

The substrate is preferably a hydrophilic polymer. The hydrophilic polymer is not particularly limited, but examples thereof include: polyvinyl alcohol or a derivative thereof, amylose (amylose) -based resin, starch-based resin, cellulose-based resin, polyacrylate-based resin, and the like. The base material containing the azo compound of the present invention is most preferably polyvinyl alcohol or a derivative thereof (hereinafter referred to as "polyvinyl alcohol resin") in terms of dyeing properties, crosslinking properties, and the like. The polarizing element of the present invention can be produced by forming a substrate into a film, adsorbing the azo compound of the present invention and other formulations on the film-shaped substrate, and applying orientation treatment such as stretching.

The method for producing the polyvinyl alcohol resin is not particularly limited, and a known production method can be used. The polyvinyl alcohol resin can be produced, for example, by saponifying a polyvinyl acetate resin (an homopolymer or copolymer of vinyl acetate). The polyvinyl acetate-based resin includes, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, a copolymer of vinyl acetate and another monomer copolymerizable with vinyl acetate. Other monomers copolymerizable with vinyl acetate include, for example: unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and the like. The polyvinyl alcohol or its derivative may be further modified, and may be, for example, an aldehyde-modified polyvinyl formal or polyvinyl acetal.

The saponification degree of the polyvinyl alcohol resin is usually preferably 85 mol% or more, more preferably 95 mol% or more, still more preferably 99 mol% or more, and particularly preferably 99.5 mol% or more. If the saponification degree is less than the lower limit, the polyvinyl alcohol resin is liable to be eluted, and there are problems such as in-plane unevenness of optical characteristics, reduction in dyeing property in the dyeing step, occurrence of cutting in the stretching step, and significant reduction in productivity.

In order to improve the optical characteristics of the polarizing element of the present invention, the polymerization degree of the polyvinyl alcohol resin is preferably 1,000 to 10,000, more preferably 2,000 to 10,000, still more preferably 3,500 to 10,000, and particularly preferably 5,000 to 10,000. If the polymerization degree exceeds 10,000, the polyvinyl alcohol resin becomes hard, the film-forming property or the elongation property is lowered, and the productivity is lowered, so that the polymerization degree is preferably 10,000 or less from the industrial viewpoint. The polymerization degree of the polyvinyl alcohol resin means viscosity average polymerization degree, and can be determined by a method well known in the art.

Hereinafter, a specific method for producing a polarizing element will be described by taking as an example a case where the substrate is a film made of a polyvinyl alcohol resin.

First, a raw film made of a polyvinyl alcohol resin is obtained by forming a film of the polyvinyl alcohol resin. As the method for forming a film of a polyvinyl alcohol resin, in addition to the method of melt-extruding a water-containing polyvinyl alcohol resin, a casting film-forming method, a wet film-forming method (a method of forming a film by discharging into a poor solvent), a gel film-forming method (a method of removing a solvent by extracting after an aqueous solution of a polyvinyl alcohol resin is once cooled and gelled), a casting film-forming method (a method of flowing and drying an aqueous solution of a polyvinyl alcohol resin on a substrate), a method of combining these methods, and the like can be used, but these methods are not limited thereto.

When a solvent is used for film formation, the solvent is not particularly limited, and examples thereof include: dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, glycerol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylolpropane, ethylenediamine, diethylenetriamine, water, and the like. The solvent may be used in 1 kind, or 2 or more kinds may be mixed and used. The amount of the solvent used for film formation is preferably 70 to 95% by weight based on the entire film formation stock solution (mixed solution containing the polyvinyl alcohol resin and the solvent used for film formation), but is not limited thereto. However, if the amount of the solvent is less than 70% by weight, the viscosity of the film-forming raw liquid becomes high, and filtration or deaeration during preparation becomes difficult, and it is difficult to obtain a raw film free from foreign matter or defects. If the amount of the solvent exceeds 95 wt%, the viscosity of the film-forming dope becomes too low to be easily controlled to a target thickness, and the influence of surface fluctuation due to wind during drying becomes large, and the drying time becomes long to deteriorate productivity.

Plasticizers may also be used when making raw films. Examples of the plasticizer include, but are not limited to, glycerin, diglycerin, ethylene glycol, propylene glycol, and low-molecular-weight polyethylene glycol. The amount of the plasticizer is not particularly limited, but is preferably in the range of usually 5 to 15 parts by weight based on 100 parts by weight of the polyvinyl alcohol resin.

Examples of the method for drying the raw film after film formation include: drying with hot air, contact drying with hot rolls, drying with infrared heaters, and the like, but is not limited thereto. One of these drying methods may be used alone in 1 kind, or 2 or more kinds may be used in combination. The drying temperature is not particularly limited, but is preferably in the range of 50 to 70 ℃.

The dried raw film is preferably heat-treated in order to control the degree of swelling to a predetermined range described later. Examples of the method of heat treatment of the raw film after film formation include: the method of treating the raw film with hot air or a method of contacting the raw film with a hot roll is not particularly limited as long as the treatment can be carried out by heat. One of these methods may be used alone in 1 kind, or 2 or more kinds may be used in combination. The heat treatment temperature is not particularly limited, but is preferably in the range of 110 to 140 ℃. The time of the heat treatment is usually about 1 to 10 minutes, but is not particularly limited.

The thickness of the raw film thus obtained is preferably from 20 to 100. mu.m, more preferably from 20 to 80 μm, and still more preferably from 20 to 60 μm. If the thickness is less than 20 μm, the film tends to be broken. If the thickness exceeds 100 μm, the stress to which the film is subjected during stretching becomes large, and the mechanical load in the stretching step becomes large, and a large-scale apparatus for withstanding the load is required.

The primary film made of the polyvinyl alcohol resin obtained as described above was subjected to the following swelling step.

The swelling step is carried out by immersing the raw film made of the polyvinyl alcohol resin in a solution at 20 to 50 ℃ for 30 seconds to 10 minutes. The solution is preferably an aqueous solution. Since swelling of the film also occurs during the dyeing treatment of the azo compound, the swelling step can be omitted when the time required for producing the polarizing element is to be shortened.

The degree of swelling F of the raw film is preferably 180 to 260%, more preferably 200 to 240%, and still more preferably 210 to 230%. If the degree of swelling F is less than 200%, the elongation at elongation becomes small, and the possibility of breakage at low magnification becomes high. If the amount is less than 180%, the elongation at elongation is remarkably reduced, the possibility of breakage is high, and sufficient elongation is difficult. If the degree of swelling F exceeds 240%, the film will swell excessively, wrinkles or slacks, and the film will be gradually cut during stretching. If the degree of swelling F exceeds 260%, it is not preferable because it is a cause of wrinkles or sagging. When the degree of swelling F is to be controlled, the degree of swelling F can be appropriately controlled by, for example, the temperature and time at the time of heat treatment of the formed raw film.

The degree of swelling F of the raw film can be measured by a method well known in the art, for example, the following method. First, the original film was cut into 5cm × 5cm, and immersed in 1L of distilled water at 30 ℃ for 4 hours. The immersed membrane was taken out from distilled water, and the filter paper was sandwiched between 2 sheets of filter paper to absorb water droplets on the surface of the membrane, and then the weight [ β (g) ] of the membrane once immersed in water was measured. Then, the film impregnated with and absorbed with the water droplets was dried for 20 hours using a drier at 105 ℃, cooled in a drier (drier) for 30 minutes, and then the weight [ γ (g) ] of the dried film was measured. Then, the degree of swelling F of the raw film was calculated by the following equation (v).

Swelling degree F ═ 100 × β/γ (%) … (v)

After the swelling step, a dyeing step is performed. In the dyeing step, the azo compound of the present invention (the azo compound represented by the general formula (1) or a salt thereof) may be adsorbed to the polyvinyl alcohol resin film together with other azo compounds (the azo compound represented by the general formula (3) or a salt thereof, the azo compound represented by the general formula (4) or a salt thereof, and the like) as needed.

The dyeing step is not particularly limited as long as the azo compound is adsorbed on the polyvinyl alcohol resin film, and may be performed, for example, by immersing the polyvinyl alcohol resin film in a solution containing the azo compound. The temperature of the solution in this dyeing step is preferably 5 to 60 ℃, more preferably 20 to 50 ℃, and particularly preferably 35 to 50 ℃. The time for immersion in the solution may be appropriately adjusted, but is preferably adjusted to 30 seconds to 20 minutes, and more preferably 1 to 10 minutes. The dyeing method is preferably a method of immersing the polyvinyl alcohol resin film in the solution, and may be a method of applying the solution to the polyvinyl alcohol resin film.

The solution containing the azo compound which is a dichroic dye may contain sodium carbonate, sodium bicarbonate, sodium chloride, sodium sulfate, anhydrous sodium sulfate, sodium tripolyphosphate, or the like as a dyeing assistant. The content of these dyeing assistants may be adjusted to any concentration depending on the time and temperature of dyeing by the dyeing property of the azo compound, but is preferably 0 to 5% by weight, and more preferably 0.1 to 2% by weight.

After the dyeing step, a washing step (hereinafter referred to as "washing step 1") may be performed before proceeding to the next step. The washing step 1 is a step of washing the dye solvent adhering to the surface of the polyvinyl alcohol resin film in the dyeing step with a washing liquid. By performing the washing step 1, the dye is inhibited from moving into the liquid to be treated next. In the washing step 1, water is usually used as the washing liquid. The cleaning method is preferably a method of immersing the resin film in a cleaning liquid, but a method of applying the cleaning liquid to the polyvinyl alcohol resin film may be used. The washing time is not particularly limited, but is preferably 1 to 300 seconds, and more preferably 1 to 60 seconds. The temperature of the cleaning liquid in the cleaning step 1 is required to be a temperature at which the hydrophilic polymer is not dissolved, and is usually 5 to 40 ℃.

After the dyeing step or after the washing step 1, a step of adding a crosslinking agent and/or a water-resistant agent to the polyvinyl alcohol resin film may be performed. As the aforementioned crosslinking agent, there can be used: for example, boric acid, boron compounds such as borax and ammonium borate, polyaldehydes such as glyoxal and glutaraldehyde, polyisocyanate-based compounds such as biuret type, isocyanurate type and block type, and titanium-based compounds such as titanyl sulfate can be used. Examples of the water-resistant agent include succinic peroxide, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerol diglycidyl ether, ammonium chloride, and magnesium chloride.

The step of containing the crosslinking agent and/or the water-resistant agent in the polyvinyl alcohol resin film is performed using at least 1 crosslinking agent and/or water-resistant agent described above. The crosslinking agent and/or the water-resistant agent are usually used in the form of a solution dissolved in a solvent. The solvent is preferably water, but is not limited thereto. In the step of containing the crosslinking agent and/or the water-resistant additive, the concentration of the crosslinking agent and/or the water-resistant additive in the solvent is preferably 0.1 to 6.0% by weight, more preferably 1.0 to 4.0% by weight, based on the solvent, in the case of boric acid as an example. The temperature of the solvent in this step is preferably 5 to 70 ℃ and more preferably 5 to 50 ℃. The method of containing the crosslinking agent and/or the water resistance agent in the polyvinyl alcohol resin film is preferably a method of immersing the polyvinyl alcohol resin film in a solution of the crosslinking agent and/or the water resistance agent, and may be a method of coating or applying the solution to the polyvinyl alcohol resin film. The treatment time of this step is preferably 30 seconds to 6 minutes, and more preferably 1 to 5 minutes. However, since it is not necessary to contain a crosslinking agent and/or a water-resistant agent in the polyvinyl alcohol resin film, this treatment step can be omitted when the time required for producing the polarizing plate is to be shortened or when the crosslinking treatment or the water-resistant treatment is not required.

After the dyeing step, after the washing step 1, or after the step of containing a crosslinking agent and/or a water-resistant agent, the elongation step is performed. The stretching step is a step of uniaxially stretching the polyvinyl alcohol resin film. The stretching method may be either a wet stretching method or a dry stretching method. The draw ratio is preferably 5 to 7 times, although 3 times or more the elongation ratio can be attained in the present invention.

In the dry stretching method, when the stretching heating medium is an air medium, the temperature of the air medium during stretching is preferably from room temperature to 180 ℃. In addition, it is preferable to perform the stretching treatment in an ambient atmosphere having a humidity of 20 to 95% RH. Examples of the stretching method include: the inter-roll stretching method, the roll heating stretching method, the rolling stretching method, the infrared heating stretching method, and the like, but are not limited to the stretching method. The extension step may be performed by 1-stage extension, or may be performed by multi-stage extension of 2 or more stages.

In the wet stretching method, the polyvinyl alcohol resin film is stretched in water, a water-soluble organic solvent, or a mixed solution thereof. And the stretching treatment is preferably performed while the polyvinyl alcohol resin film is immersed in a solution containing the crosslinking agent and/or the water-resistant agent. As the crosslinking agent, for example: boric acid, boron compounds such as borax and ammonium borate, polyaldehydes such as glyoxal and glutaraldehyde, polyisocyanate compounds such as biuret type, isocyanurate type and block type, titanium compounds such as titanyl sulfate, etc., and ethylene glycol glycidyl ether and polyamide epichlorohydrin may be used. Examples of the water-resistant agent include succinic peroxide, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerol diglycidyl ether, ammonium chloride, and magnesium chloride.

The step of incorporating the crosslinking agent and/or the water-resistant agent into the polyvinyl alcohol resin film is performed using at least 1 of the crosslinking agent and/or the water-resistant agent described above. The crosslinking agent and/or the water-resistant agent are usually used in the form of a solution dissolved in a solvent. The solvent is preferably water, but is not limited thereto.

The polyvinyl alcohol resin film is stretched in a solution containing at least 1 or more of the crosslinking agent and/or the water-resistant agent described above. The crosslinking agent is preferably boric acid. The concentration of the crosslinking agent and/or the water resistance agent in the foregoing extension step is, for example, preferably 0.5 to 15% by weight, and more preferably 2.0 to 8.0% by weight. The draw ratio is preferably 2 to 8 times, and more preferably 5 to 7 times. The elongation temperature is preferably 40 to 60 ℃ and more preferably 45 to 58 ℃. The extension time is usually 30 seconds to 20 minutes, but 2 to 5 minutes is more preferable. The wet stretching step may be performed by 1-stage stretching, or may be performed by multi-stage stretching in 2 or more stages.

After the stretching step, a washing step (hereinafter referred to as "washing step 2") of washing the surface of the film may be performed because a crosslinking agent and/or a water resistant agent may be precipitated on the surface of the film or foreign matter may be adsorbed thereon. The washing time is preferably 1 second to 5 minutes. The cleaning method is preferably a method of immersing in a cleaning liquid, but a method of coating or applying the cleaning liquid to a polyvinyl alcohol resin film may be used. The cleaning process may be performed in 1 stage, or may be performed in 2 or more stages. The temperature of the washing liquid in the washing step is not particularly limited, but is usually 5 to 50 ℃ and preferably 10 to 40 ℃.

The solvent used in the treatment steps so far includes, for example: water; dimethyl sulfoxide; n-methyl pyrrolidone; alcohols such as methanol, ethanol, propanol, isopropanol, glycerol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and trimethylolpropane; and amines such as ethylenediamine and diethylenetriamine, but not limited to these solvents. In addition, a mixture of 1 or more of these solvents may also be used. The most preferred solvent is water.

After the stretching step or the washing step 2, a drying step of the polyvinyl alcohol resin film is performed. The drying treatment may be performed by natural drying, but in order to further improve the drying efficiency, the moisture on the surface may be removed by compression with a roll, an air knife (air knife), a water suction roll, or the like, or may be performed by air drying together with or instead of such moisture removal. The temperature of the drying treatment is preferably 20 to 100 ℃ and more preferably 60 to 100 ℃. The time for the drying treatment may be in the range of 30 seconds to 20 minutes, but is preferably 5 to 10 minutes.

In the present invention, iodine may be contained in the polarizing element by adsorbing iodine to the substrate using, for example, a dyeing solution containing iodine within a range in which desired durability can be maintained even when the polarizing performance is further improved. The staining solution contains iodine and iodide. The iodide may be, for example, potassium iodide, ammonium iodide, cobalt iodide, zinc iodide, etc., but is not limited to the iodide shown here. The iodine concentration is preferably 0.0001 to 0.5% by weight, and more preferably 0.001 to 0.4% by weight. The iodide concentration is preferably 0.0001 to 8% by weight. In this case, any one of the dyeing step, the washing step 1, the stretching step and the washing step 2, or several of them may be used as the treatment step. The treatment temperature is preferably 5 to 60 ℃ and more preferably 5 to 50 ℃ and particularly preferably 10 to 40 ℃. The treatment time, although moderately adjustable, is preferably adjusted at 30 seconds to 20 minutes, and more preferably at 1 to 5 minutes.

As described above, the polarizing element of the present invention has excellent polarizing performance because the azo compound represented by the general formula (1) is used as the azo compound in the polarizing element comprising a base material and the azo compound.

[ polarizing plate ]

The polarizing plate of the present invention comprises the polarizing element of the present invention and a transparent protective layer provided on at least one surface of the polarizing element.

The transparent protective layer may be provided as a coating layer made of a transparent polymer or a laminated layer of transparent films. The transparent polymer or transparent film forming the transparent protective layer is preferably a transparent polymer or transparent film having high mechanical strength and good thermal stability. Examples of the transparent polymer or transparent film used for the transparent protective layer include: examples of the resin include cellulose acetate resins such as triacetylcellulose and diacetylcellulose and films thereof, acrylic resins and films thereof, polyvinyl chloride resins and films thereof, nylon resins and films thereof, polyester resins and films thereof, polyarylate resins and films thereof, cyclic polyolefin resins and films thereof using cyclic olefins such as norbornene as a monomer, polyethylene, polypropylene, polyolefins having a ring system or a norbornene skeleton or copolymers thereof, and polymers (or resins) or films thereof having imide and/or amide in a main chain or side chain. In addition, a resin having liquid crystallinity or a film thereof may be provided as the transparent protective layer. The thickness of the protective film is, for example, about 0.5 to 200 μm. The polarizing module may be provided with 1 layer of resin or film on one surface thereof, 2 or more layers of the same or different resins or films on one surface thereof, or 1 or more layers of the same or different resins or films on both surfaces thereof.

An adhesive may be used to attach the transparent protective layer to the polarizer. The binder is not particularly limited, but a polyvinyl alcohol binder is preferable. Examples of the polyvinyl alcohol binder include: GOHSENOL (registered trademark) NH-26 (manufactured by Nippon synthetic chemical industries, Ltd.), EXCEVAL (registered trademark) RS-2117 (manufactured by KURARARAY, Ltd.), and the like, but are not limited thereto. The binder may contain a crosslinking agent and/or a water resistant agent. The polyvinyl alcohol binder may be mixed with a maleic anhydride-isobutylene copolymer, and in this case, a crosslinking agent may be further mixed as required. The maleic anhydride-isobutylene copolymer includes, for example: ISOBAM (registered trademark) # 18 (manufactured by KURARAY Co., Ltd.), ISOBAM (registered trademark) #04 (manufactured by KURARAY Co., Ltd.), ammonia-modified ISOBAM (registered trademark) #104 (manufactured by KURAY Co., Ltd.), ammonia-modified ISOBAM (registered trademark) #110 (manufactured by KURAY Co., Ltd.), imidized ISOBAM (registered trademark) #304 (manufactured by KURAY Co., Ltd.), and imidized ISOBAM (registered trademark) #310 (manufactured by KURAY Co., Ltd.), and the like. As the crosslinking agent to be mixed in the maleic anhydride-isobutylene copolymer as required, a water-soluble polyepoxy compound can be used. Examples of the water-soluble polyepoxy compound include: DENACOL EX-521 (manufactured by Nagase ChemteX Co., Ltd.), TETRAD (registered trademark) -C (manufactured by Mitsubishi GAS chemical Co., Ltd.), and the like. The adhesive may be any known adhesive other than a polyvinyl alcohol adhesive such as a urethane (urethane) adhesive, an acrylic adhesive, and an epoxy adhesive. In addition, in order to improve the adhesive strength of the binder or to improve the water resistance, additives such as zinc compounds, chlorides, and iodides may be added to the binder at a concentration of about 0.1 to 10 wt%. The additive is not limited. The polarizing plate can be obtained by bonding a transparent protective layer to at least one surface of a polarizing element with an adhesive and then drying or heat-treating the resulting laminate at an appropriate temperature.

The polarizing plate may be bonded to a display device such as a liquid crystal display device or an organic electroluminescence display device, or may be provided with various functional layers, layers or films having luminance improving properties for improving a viewing angle and/or improving contrast on the surface of a transparent protective layer which is a non-exposed surface after bonding. When a polarizing plate is bonded to these layers or films or a display device, an adhesive is preferably used.

The polarizing plate may be one in which various known functional layers such as an antireflection layer, an antiglare layer, and a hard coat layer are provided on the other surface, i.e., the exposed surface, of the transparent protective layer. In the production of these various functional layers, a coating method is preferred, but a method of bonding films having such functions via an adhesive or an adhesive may be used. The functional layer may be a layer or a film for controlling retardation.

As described above, the polarizing plate of the present invention has excellent polarizing performance because the azo compound represented by the general formula (1) is used as the azo compound in the polarizing plate comprising a polarizing element comprising a base material and the azo compound, and a transparent protective layer provided on at least one surface of the polarizing element.

The polarizing component and the polarizing plate can be used for display equipment such as liquid crystal display equipment. A display device using the polarizing element or the polarizing plate of the present invention can be a display device having a high contrast ratio.

The polarizing element and the polarizing plate of the present invention are provided with a protective layer, a functional layer, a support, and the like as needed, and are used in a liquid crystal projector, an electronic calculator, a clock, a notebook computer, a word processor, a liquid crystal television, a polarizing lens, polarizing glasses, a car navigation system, an organic electroluminescence display, an indoor and outdoor measuring instrument, an indicator, and the like.

The polarizing plate of the present invention can be used as a polarizing plate with a support attached thereto by attaching the polarizing plate of the present invention to the support. The support preferably has a flat surface portion because a polarizing plate is attached. The support is preferably a glass molded product because it is used for optical purposes. Examples of the glass molded article include: glass plates, lenses, prisms (e.g., triangular prisms, cubic prisms, etc.), and the like. The lens with a polarizing plate attached thereto can be used as a condenser lens (condenser lens) with a polarizing plate in a liquid crystal projector. The prism-attached polarizing plate can be used as a polarizing beam splitter with a polarizing plate or a dichroic prism (dichroic prism) with a polarizing plate in a liquid crystal projector. In addition, a polarizing plate may be attached to the liquid crystal cell. The glass molded article may be made of, for example: inorganic glass such as soda glass, borosilicate glass, crystal, and sapphire, and organic plastic such as acrylic resin and polycarbonate. The thickness or size of the glass plate may be a desired size. In the polarizing plate with a support made of glass, when the single-plate light transmittance is to be further improved, an antireflection layer (AR layer) is preferably provided on one or both of the glass surface and the surface of the polarizing plate. A transparent adhesive is applied to the surface of the support, for example, the surface of the flat portion of the support, and then the polarizing plate of the present invention is attached to the applied surface. Alternatively, a transparent adhesive (pressure-sensitive adhesive) may be applied to the polarizing plate, and then the support may be attached to the applied surface. The adhesive (adhesive) used in this case is preferably an acrylate, for example. When the polarizing plate and the retardation plate are used in combination as an elliptically polarizing plate, the retardation plate side of the elliptically polarizing plate is usually attached to the support, but the polarizing plate side of the elliptically polarizing plate may be attached to the support.

[ display apparatus ]

The display device of the present invention includes the polarizing element of the present invention or the polarizing plate of the present invention. The display device of the present invention may be a reflection type, transmission type, or transmission/reflection type liquid crystal display device including, for example, a liquid crystal cell and the polarizing element of the present invention or the polarizing plate of the present invention disposed on one side or both sides of the liquid crystal cell. The liquid crystal cell may be any suitable liquid crystal cell, such as an active matrix drive type liquid crystal cell typified by a thin film transistor type, or a simple matrix drive type liquid crystal cell typified by a twisted nematic or super twisted nematic type.

In the display device of the present invention, 1 or 2 or more suitable other optical members such as a prism array sheet (prism sheet) or a lenticular array sheet, a light diffusion plate, or a backlight may be disposed at suitable positions. When the polarizing element of the present invention, the polarizing plate of the present invention, or other optical members are provided, these may be the same on both sides or may be different on both sides.

The display device of the present invention may be a display device having an adhesive layer for adhering to other members such as a liquid crystal cell on one side or both sides of the polarizing element of the present invention or the polarizing plate of the present invention. The adhesive layer can be formed using an appropriate adhesive material or adhesive, and is not particularly limited. Examples of the material constituting the pressure-sensitive adhesive layer include materials in which a suitable polymer such as acrylic resin, silicone resin, polyester, polyurethane, polyamide, polyether, fluororesin, or rubber is used as a matrix polymer.

The display device of the present invention can be used for liquid crystal display devices such as Twisted Nematic (TN) liquid crystal display devices, Super Twisted Nematic (STN) liquid crystal display devices, Thin Film Transistor (TFT) liquid crystal display devices, Vertical Alignment (VA) liquid crystal display devices, and in-plane switching (IPS) liquid crystal display devices as a whole, and other display devices.

[ examples ]

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the scope of these examples. The transmittance, the degree of polarization, and the contrast ratio of the polarizing element and the polarizing plate obtained in examples and comparative examples were measured in the following manner.

[ measuring method of transmittance and degree of polarization of polarizing element ]

The transmittance at each wavelength of the 1-piece polarizer is assumed to be a single transmittance Ts, the transmittance at each wavelength when the 2-piece polarizers are overlapped so that the absorption axis directions of the polarizers are the same is assumed to be a parallel-bit transmittance Tp, and the transmittance at each wavelength when the 2-piece polarizers are overlapped so that the absorption axes of the polarizers are perpendicular is assumed to be a perpendicular-bit transmittance Tc. The respective transmittances Ts, Tp and Tc were measured at 5nm intervals by a spectral luminance meter (U-4100 manufactured by Hitachi High-Technologies, Ltd.).

The polarization degree ρ (%) of the polarizer is calculated from the parallel transmittance Tp and the vertical transmittance Tc by the following equation.

ρ＝{(Tp-Tc)/(Tp+Tc)}^1/2×100

[ methods for measuring transmittance, polarization degree, and contrast value of polarizing plate ]

The transmittance corrected for the photosensitivity of the transmittance at each wavelength of 1 polarizing plate is the single transmittance Ys, the transmittance corrected for the photosensitivity of the transmittance at each wavelength when 2 polarizing plates are stacked so that the absorption axis directions of these polarizing plates are the same is the parallel bit transmittance Yp, and the transmittance corrected for the photosensitivity of the transmittance at each wavelength when 2 polarizing plates are stacked so that the absorption axes of these polarizing plates are perpendicular is the vertical bit transmittance Yc. The visibility correction is performed according to JIS Z8722: 2009 was performed with a C light source 2 ° field of view, chromaticity function. The respective transmittances Ys, Yp, and Yc are measured at respective wavelengths at intervals of 5nm by a spectrophotometer ("U-4100" manufactured by hitachi high-tech co.

The polarization degree Py (%) of the polarizing plate is calculated from the parallel bit transmittance Yp corrected for visibility and the vertical bit transmittance Yc corrected for visibility by the following formula (16).

Py＝{(Yp-Yc)/(Yp+Yc)}^1/2×100…(16)

The contrast value (CR) of the polarizing plate is calculated from the parallel bit transmittance Yp corrected for visibility and the perpendicular bit transmittance Yc corrected for visibility by the following formula (17).

CR＝Yp/Yc…(17)

[ example 1]

< Synthesis of azo Compound of Compound example 1 >

Adding 25.3 parts by weight of 4-aminobenzene-1, 3-disulfonic acid into 500 parts by weight of water, cooling and adding 31.3 parts by weight of 35 wt% aqueous hydrochloric acid solution at 10 ℃ or below, then adding 6.9 parts by weight of sodium nitrite, stirring for 1 hour at 5 to 10 ℃, and diazotizing the mixture. To this end, 10.7 parts by weight of 3-methylaniline dissolved in a dilute aqueous hydrochloric acid solution was added as a 1-time coupling agent (coupling component), sodium carbonate was added to adjust the pH to 3 while stirring at 10 to 30 ℃, the coupling reaction was completed by stirring, and 29.7 parts by weight of a monoazo amino compound represented by the following structural formula (18) was obtained by filtration.

The obtained monoazo amino compound of the structural formula (18) was added to 400 parts by weight of water, dissolved with sodium hydroxide, and 25.0 parts by weight of a 35% by weight aqueous hydrochloric acid solution was added at 10 to 30 ℃ followed by 5.5 parts by weight of sodium nitrite, and stirred at 20 to 30 ℃ for 1 hour to be diazotized. To this end, 8.6 parts by weight of 3-methylaniline dissolved in a dilute aqueous hydrochloric acid solution was added as a 2-fold coupling agent, sodium carbonate was added to adjust the pH to 3 while stirring at 20 to 30 ℃, the coupling reaction was further completed by stirring, and then, the mixture was filtered to obtain 31.3 parts by weight of a bisazo amino compound represented by the following structural formula (19).

The obtained bisazo amino compound of the structural formula (19) was added to 250 parts by weight of water, dissolved with sodium hydroxide, and 20.0 parts by weight of a 35% by weight aqueous hydrochloric acid solution was added at 20 to 30 ℃, followed by 4.4 parts by weight of sodium nitrite, stirred at 20 to 30 ℃ for 1 hour, and diazotized. To this end, 8.8 parts by weight of 2-methoxy-5-methylaniline dissolved in a dilute aqueous hydrochloric acid solution was added as a 3-time coupling agent, and while stirring at 20 to 30 ℃, sodium carbonate was added to adjust pH3.5, and further stirring was carried out to complete the coupling reaction, followed by filtration to obtain 32.6 parts by weight of a trisazo amino compound represented by the following structural formula.

The obtained trisazo amino compound of the structural formula (20) was added to 200 parts by weight of water, dissolved with sodium hydroxide, added with 16.0 parts by weight of a 35% by weight aqueous hydrochloric acid solution at 20 to 30 ℃ and then with 3.5 parts by weight of sodium nitrite, stirred at 20 to 30 ℃ for 1 hour, and diazotized to obtain a diazo compound of the trisazo amino compound. Further, as a 4-time coupling agent, 16.1 parts by weight of 6-phenylamino-1-naphthol-3-sulfonic acid was added to 50 parts by weight of water, and dissolved in sodium carbonate as weak alkali to obtain a solution of the 4-time coupling agent.

In this solution of the 4-time couplant, the diazotized substance of the trisazo amino compound obtained previously was kept at pH8 to 10 and injected, stirred, and the coupling reaction was completed. Then, monoethanolamine was added in an amount of 30.5 parts by weight to an aqueous solution of 25 parts by weight of copper sulfate, and the mixture was reacted at 95 ℃ for 10 hours to conduct a copper conversion reaction until no unreacted product was recognized by thin layer chromatography. After the reaction, salting out with sodium chloride and filtration were carried out to obtain 46.4 parts by weight of the azo compound (copper tetrazo compound) of compound example 1 as an example of the azo compound represented by general formula (1).

< manufacture of polarizing component >

A polyvinyl alcohol film (VF-PE #4000 manufactured by KURARAAY GmbH, Inc.; hereinafter simply referred to as "film") having a saponification degree of 99 mol% or more and a film thickness of 40 μm as a substrate was immersed in hot water at 35 ℃ for 3 minutes to perform swelling treatment. On the other hand, an aqueous solution at 40 ℃ was prepared by mixing 1.0 part by weight of the azo compound of compound example 1, which is an azo compound represented by general formula (1) or a salt thereof, 1.0 part by weight of anhydrous sodium sulfate as a dyeing assistant, and 2,000 parts by weight of water. The swollen membrane is immersed in the aqueous solution at 40 ℃ to adsorb the azo compound on the membrane.

After the film having adsorbed the azo compound was washed with water, boric acid treatment was performed for 1 minute with an aqueous solution of 40 ℃ containing 2% by weight of boric acid. While the film obtained by the boric acid treatment was stretched 5.0 times, the boric acid treatment was performed in an aqueous solution at 58 ℃ containing 3.0 wt% of boric acid for 5 minutes. The boric acid-treated film was kept in a taut state, and was washed with water at room temperature for 20 seconds. The film obtained by the washing treatment was immediately dried at 60 ℃ for 5 minutes to obtain a polarizing element in the form of a film having a thickness of 15 μm. A polarizing element containing the azo compound represented by the general formula (1) or a salt thereof, which is one example of the present invention, is produced by the above method.

[ example 2]

< Synthesis of azo Compound of Compound example 17 >

An azo compound of compound example 17 (a copper tetrazo compound) which is an azo compound represented by general formula (1) or a salt thereof was obtained in the same operation as the synthesis of the azo compound of compound example 1 in example 1 except that 28.2 parts by weight of (7, 8-disulfonic acid-2H-naphtho [1,2-d ] triazol-2-yl-) -1-naphthol-3-sulfonic acid was used as a 4-time coupling agent in place of 16.1 parts by weight of 6-phenylamino-1-naphthol-3-sulfonic acid.

< manufacture of polarizing component >

A polarizing module was produced in the same manner as in example 1, except that the azo compound of compound example 17 was used instead of the azo compound of compound example 1.

Comparative example 1

A polarizing module was produced in the same manner as in example 1, except that the cuprified azo compound described in example 38 of Japanese patent application laid-open No. Sho 60-156759 was used in place of the azo compound of Compound example 1.

Comparative example 2

A polarizing plate was produced in the same manner as in example 1 except that the cuprified azo compound described in example 1 of Japanese patent application publication No. 64-5623 was used in place of the azo compound of compound example 1.

Table 1 shows the measurement results of the monomer transmittance Ts, the parallel-bit transmittance Tp, the vertical-bit transmittance Tc, and the polarization degree ρ at the wavelength at which the polarization degree is highest in the polarizers of examples 1 and 2 and the polarizers of comparative examples 1 and 2.

[ Table 1]

	Ts(％)	Tp(％)	Tc(％)	ρ(％)
					Example 1	44.05	38.33	0.482	98.75
Example 2	43.91	37.98	0.582	98.48
					Comparative example 1	44.02	37.44	1.315	96.55
Comparative example 2	43.96	35.78	2.872	92.27

As is clear from table 1, the polarization module using the cupped azo compound of examples 1 and 2 of the present invention dramatically improved the polarization degree with the same degree of transmittance as compared with the hitherto known cupped azo compound.

[ example 3]

First, a polyvinyl alcohol film (VF-PE #4000 manufactured by KURARAAY GmbH, Inc.; hereinafter simply referred to as "film") having a saponification degree of 99 mol% or more and a film thickness of 40 μm as a substrate was immersed in hot water at 35 ℃ for 3 minutes to perform swelling treatment. An aqueous solution at 40 ℃ was prepared from 2.0 parts by weight of the azo compound of example 1, which is the azo compound represented by the general formula (1) or a salt thereof, 0.5 parts by weight of the azo compound (c.i. direct red 117) of example 20, which is the azo compound represented by the general formula (3) or a salt thereof, 0.5 parts by weight of the azo compound of example 111, which is the azo compound represented by the general formula (4) or a salt thereof (the azo compound described in example 1 of international publication No. 2007/138980), 1.0 parts by weight of sodium tripolyphosphate and 1.0 part by weight of anhydrous sodium sulfate as dyeing auxiliaries, and 2,000 parts by weight of water. The swollen membrane is immersed in the aqueous solution at 40 ℃ to adsorb the azo compound on the membrane.

After the film having adsorbed the azo compound was washed with water, boric acid treatment was performed for 1 minute with an aqueous solution of 30 ℃ containing 2% by weight of boric acid. While the film obtained by the boric acid treatment was stretched 5.0 times, the boric acid treatment was performed in an aqueous solution at 58 ℃ containing 3.0 wt% of boric acid for 5 minutes. The boric acid-treated film was kept in a taut state, and was washed with water at room temperature for 20 seconds. The film obtained by the washing treatment was immediately dried at 60 ℃ for 5 minutes to obtain a polarizing element in the form of a film having a thickness of 15 μm. The polarizing element comprising the film containing the azo compound represented by the general formula (1) or a salt thereof, the azo compound represented by the general formula (3) or a salt thereof, and the azo compound represented by the general formula (4) or a salt thereof is produced by the above method.

Both sides of the obtained polarizing element were laminated (laminated) with a TAC/adhesive layer/polarizing element/adhesive layer/TAC composition by bonding alkali-treated triacetyl cellulose films (TD-80U manufactured by Fuji film Co., Ltd.; hereinafter, abbreviated as "TAC") having a film thickness of 80 μm with a polyvinyl alcohol adhesive. Thereby, a polarizing plate was obtained. The obtained polarizing plate was used as a measurement sample.

[ example 4]

A polarizing plate was produced in the same manner as in example 3 except that 3.0 parts by weight of the azo compound of compound example 17 used in example 2 was used instead of 2.0 parts by weight of the azo compound of compound example 1 as the azo compound represented by general formula (1) or a salt thereof, and a polarizing module comprising the azo compound represented by general formula (1) or a salt thereof, the azo compound represented by general formula (3) or a salt thereof, and the azo compound represented by general formula (4) or a salt thereof in a film was produced, and the produced polarizing plate was used as a measurement sample.

[ example 5]

A polarizing plate was produced in the same manner as in example 3 except that 1.0 part by weight of the sodium salt of the azo compound of compound example 41 (the azo compound described in example 1 of international publication No. 2005/075572) was used instead of 0.5 part by weight of the azo compound of compound example 20 as the azo compound represented by general formula (3) or a salt thereof, and a polarizing module containing the azo compound represented by general formula (1) or a salt thereof, the azo compound represented by general formula (3) or a salt thereof, and the azo compound represented by general formula (4) or a salt thereof in a film was produced, and the polarizing plate thus produced was used as a measurement sample.

[ example 6]

A polarizing plate was produced in the same manner as in example 3 except that 1.6 parts by weight of the azo compound of compound example 54 (the azo compound represented by formula (21) described in example 3 of international publication No. 2012/108169) was used instead of 0.5 parts by weight of the azo compound of compound example 20 as the azo compound represented by general formula (3) or a salt thereof, and a polarizing plate was produced in the same manner as in example 3, the film containing the azo compound represented by general formula (1) or a salt thereof, the azo compound represented by general formula (3) or a salt thereof, and the produced polarizing plate was used as a measurement sample.

[ example 7]

A polarizing plate was produced in the same manner as in example 3 except that 0.58 parts by weight of c.i. direct orange 39(CAS No. 1325-54-8) having the structure of the general formula (4) was used instead of 0.5 parts by weight of the azo compound of compound example 111 as the azo compound represented by the general formula (4) or a salt thereof, and a polarizing plate containing the azo compound represented by the general formula (1) or a salt thereof, the azo compound represented by the general formula (3) or a salt thereof, and the azo compound represented by the general formula (4) or a salt thereof in a film was produced, and the produced polarizing plate was used as a measurement sample.

[ example 8]

A polarizing plate comprising a film containing an azo compound represented by the general formula (1) or a salt thereof, an azo compound represented by the general formula (3) or a salt thereof, and an azo compound represented by the general formula (4) or a salt thereof, was produced in the same manner as in example 3, except that 0.12 parts by weight of the azo compound of compound example 20 and 0.5 parts by weight of the azo compound of compound example 20 were replaced with 1.2 parts by weight of the azo compound of compound example 99 (the azo compound represented by the formula (17) described in example 1 of International publication No. 2012/108169), and 0.39 parts by weight of C.I. direct orange 39(CAS No. 1325-54-8) having the structure of the general formula (4) was used as the azo compound represented by the general formula (4) or a salt thereof, and 0.5 parts by weight of the azo compound example 111 was replaced with the azo compound of compound example 4, at the same time, a polarizing plate was produced, and the produced polarizing plate was used as a measurement sample.

[ example 9]

A polarizing plate was produced in the same manner as in example 3 except that c.i. direct yellow 28(0.80 parts by weight) represented by the following structural formula was used as another organic dye instead of 0.5 parts by weight of the azo compound of compound example 111 which is the azo compound represented by general formula (4) or a salt thereof, and a polarizing component containing the azo compound represented by general formula (1) or a salt thereof, the azo compound represented by general formula (3) or a salt thereof, and the azo compound represented by general formula (4) or a salt thereof having a polarizing function at almost the same wavelength in the film was produced, and the produced polarizing plate was used as a measurement sample.

Comparative example 3

A polarizing plate was produced in the same manner as in example 3 except that the composition of the azo compound in example 3 was changed to the composition of the azo compound described in example 2 of jp-a 11-218611, and a polarizing plate was produced to obtain a measurement sample.

Comparative example 4

A polarizing plate was prepared in the same manner as in example 3 except that the composition of the azo compound in example 3 was changed to the composition of the azo compound described in example 3 of japanese patent No. 4162334, and the thus-prepared polarizing plate was used as a measurement sample.

Comparative example 5

A polarizing plate was prepared in the same manner as in example 3 except that the composition of the azo compound in example 3 was changed to the composition of the azo compound described in example 1 of japanese patent No. 4360100, and the thus-prepared polarizing plate was used as a measurement sample.

Comparative example 6

A polarizing plate was produced in the same manner as in example 3 except that the azo compound belonging to compound example 1, which is an azo compound represented by general formula (1), was not used, and a polarizing plate was produced.

Comparative example 7

A polarizing plate was produced in the same manner as in example 3 except that 1.8 parts by weight of an azo compound represented by formula (17) which is the same as the azo compound of compound example 1 and belongs to the tetrazo compound international publication No. 2012/108169 was used instead of the azo compound of compound example 1 represented by general formula (1), and the produced polarizing plate was used as a measurement sample.

Table 2 shows the single transmittance Ys corrected for visibility, the parallel bit transmittance Yp corrected for visibility, the vertical bit transmittance Tc corrected for visibility, the polarization degree Py, and the contrast value CR at the wavelength at which the polarization degree is highest in the polarizing plates of examples 3 to 9 and comparative examples 3 to 7.

[ Table 2]

	Ys(％)	Yp(％)	Yc(％)	Py(％)	CR
						Example 3	40.23	32.33	0.0371	99.89	871
Example 4	40.36	32.54	0.0423	99.87	769
						Example 5	40.71	33.11	0.0313	99.91	1058
Example 6	40.44	32.68	0.0236	99.93	1385
						Example 7	40.41	32.54	0.1201	99.63	271
Example 8	40.43	32.67	0.0256	99.92	1276
						Example 9	40.45	32.56	0.1621	99.50	201
Comparative example 3	40.38	31.94	0.6756	97.91	47
						Comparative example 4	40.69	32.60	0.5123	98.44	64
Comparative example 5	40.61	32.09	0.8914	97.26	36
						Comparative example 6	40.53	22.61	10.242	61.36	2
Comparative example 7	40.45	31.91	0.818	97.47	39

As can be seen from table 2, the polarizing plates of examples 3 to 9 of the present invention have improved polarizing performance and contrast when compared with the polarizing plates of comparative examples 3 to 7. In addition, even when the polarizing plates of examples 3 to 9 were exposed to an environment of 85 ℃ and 85% relative humidity for 500 hours, the transmittance and the degree of polarization were not changed.

As is apparent from the above, the results of examples 1 to 9 and comparative examples 1 to 7 clearly show that the polarizing plate and the polarizing element of the present invention have improved optical characteristics as compared with the conventional polarizing plate and polarizing element. Further, as is apparent from the results of examples 3 to 9 above, the polarizing plate and the polarizing element of the present invention are a polarizing element and a polarizing plate having high durability. Further, products such as display devices and polarizing lenses using the polarizing element or polarizing plate of the present invention have good polarizing properties and durability, and thus high reliability can be obtained.

Claims

1. An azo compound represented by the following general formula (1):

in the formula, Ab₁Represents a phenyl group having 1 or 2 substituents selected from the group consisting of a sulfonic acid group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms, or a naphthyl group having 2 or 3 substituents selected from the group consisting of a sulfonic acid group, a hydroxyl group and an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group,

Rb₁to Rb₅Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a sulfonic acid group, or an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group,

Xb₁represents a phenylamino group which may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfonic group, an amino group and an alkylamino group having 1 to 4 carbon atoms, a benzoylamino group which may have 1 substituent selected from the group consisting of a hydroxyl group, an amino group and a carboxyethylamino group, a phenylazo group which may have 1 to 3 substituents selected from the group consisting of a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an amino group and a carboxyethylamino group, or a naphthotriazole group substituted with 1 or 2 sulfonic acid groups.

2. The azo compound according to claim 1, which is an azo compound represented by the following general formula (2) or a salt thereof:

in the formula, Ab₁Represents a phenyl group having 1 or 2 substituents selected from the group consisting of a sulfonic acid group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms, or a naphthyl group having 2 or 3 substituents selected from the group consisting of a sulfonic acid group, a hydroxyl group and an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group; rb₁To Rb₅Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group; xb₁May have a structure selected from methyl,A phenylamino group having 1 or 2 substituents selected from the group consisting of a methoxy group, a sulfonic acid group, an amino group and an alkylamino group having 1 to 4 carbon atoms, a benzoylamino group having 1 substituent selected from the group consisting of a hydroxy group, an amino group and a carboxyethylamino group, a phenylazo group having 1 to 3 substituents selected from the group consisting of a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an amino group and a carboxyethylamino group, or a naphthotriazolyl group substituted with 1 or 2 sulfonic acid groups.

3. The azo compound of claim 1, wherein Xb in the general formula (1)₁Is a phenylamino group which may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfonic acid group, an amino group and an alkylamino group having 1 to 4 carbon atoms.

4. The azo compound of claim 2, wherein Xb in the general formula (2)₁Is a phenylamino group which may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfonic acid group, an amino group and an alkylamino group having 1 to 4 carbon atoms.

5. A polarizing plate comprising a substrate and the azo compound of any one of claims 1 to 4.

6. The polarizing assembly according to claim 5, further comprising an azo compound represented by the following general formula (3) or a salt thereof:

in the formula, Ar₁Represents a phenyl group having 1 or 2 substituents selected from the group consisting of a sulfonic acid group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms, or a naphthyl group having 2 or 3 substituents selected from the group consisting of a sulfonic acid group, a hydroxyl group and an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group,

Rr₁to Rr₆Each independently represents a hydrogen atom or an alkane having 1 to 4 carbon atomsA C1 to C4 alkoxy group or a C1 to C4 alkoxy group having a sulfonic acid group,

Xr₁represents a phenylamino group which may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfonic group, an amino group and an alkylamino group having 1 to 4 carbon atoms, a benzoylamino group which may have 1 substituent selected from the group consisting of a hydroxyl group, an amino group and a carboxyethylamino group, a phenylazo group which may have 1 to 3 substituents selected from the group consisting of a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an amino group and a carboxyethylamino group, or a naphthotriazole group substituted with 1 or 2 sulfonic acid groups,

m and n each independently represent 0 or 1.

7. The polarizing assembly according to claim 5, further comprising an azo compound represented by the following general formula (4) or a salt thereof:

in the formula, Ay₁Represents a sulfonic acid group, a carboxyl group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, Ry₁To Ry₄Each independently represents a hydrogen atom, a sulfonic acid group, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and p represents an integer of 1 to 3.

8. The polarizing assembly according to claim 6, further comprising an azo compound represented by the following general formula (4) or a salt thereof:

9. The light polarizing assembly according to claim 6,

the azo compound represented by the general formula (3) or a salt thereof is an azo compound represented by the following general formula (5) or a salt thereof:

in the formula, Ar₁Represents a phenyl group having 1 or 2 substituents selected from the group consisting of a sulfonic acid group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms, or a naphthyl group having 2 or 3 substituents selected from the group consisting of a sulfonic acid group, a hydroxyl group and an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group; rr₁To Rr₆Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms and having a sulfonic acid group; xr (x of X)₁Represents a phenylamino group which may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfonic group, an amino group and an alkylamino group having 1 to 4 carbon atoms, a benzoylamino group which may have 1 substituent selected from the group consisting of a hydroxyl group, an amino group and a carboxyethylamino group, a phenylazo group which may have 1 to 3 substituents selected from the group consisting of a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an amino group and a carboxyethylamino group, or a naphthotriazole group substituted with 1 or 2 sulfonic acid groups; m and n each independently represent 0 or 1.

10. The light polarizing assembly according to claim 6 or 9, wherein Rr in the general formula (3) or (5)₅And Rr₆One is an alkoxy group having 1 to 4 carbon atoms, and the other is an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.

11. The light polarizing assembly according to claim 6 or 9, wherein Xr in the general formula (3) or (5)₁Is phenylamino which may have 1 or 2 substituents selected from the group consisting of methyl, methoxy, sulfonic acid, amino and alkylamino having 1 to 4 carbon atoms, or may have a substituent selected from the group consisting of hydroxy, amino and carboxyethylaminoBenzoylamino of 1 substituent in the group.

12. The light polarizing assembly according to claim 7 or 8, wherein Ay in the general formula (4)₁Is a carboxyl group or a sulfonic acid group.

13. The light polarizing assembly according to any one of claims 5 to 9, wherein the substrate is a film formed of polyvinyl alcohol or a derivative thereof.

14. A polarizing plate comprising the polarizing element according to any one of claims 5 to 13 and a transparent protective layer provided on at least one surface of the polarizing element.

15. A display device provided with the polarizing plate according to any one of claims 5 to 13 or the polarizing plate according to claim 14.