KR102581552B1 - Azo compounds, and dye-type polarizer film and polarizer plate including same - Google Patents

Abstract

The purpose of the present invention is to provide an azo compound useful as a dichroic dye used in a polarizing plate that has excellent polarization performance and durability and has low color leakage in the visible light region, and a neutral gray polarizing plate for vehicle use using the same. The following formula (1) (wherein A is A ₁ : a phenyl group having a substituent, or A ₂ : a hydrogen atom, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, and/or a naphthyl group having a sulfo group. and R ₁ to R ₄ each independently represent a hydrogen atom, an alkyl group with 1 to 4 carbon atoms, or an alkoxy group with 1 to 4 carbon atoms.) Azo compounds and salts thereof.

Description

Azo compounds and dye-based polarizing films and polarizers containing them {AZO COMPOUNDS, AND DYE-TYPE POLARIZER FILM AND POLARIZER PLATE INCLUDING SAME}

The present invention relates to novel azo compounds and dye-based polarizing films and polarizing plates containing them.

A polarizing plate, which has a function of transmitting and blocking light, is a basic component of a display device such as a liquid crystal display (LCD), along with a liquid crystal that has a light switching function. Fields of application for this LCD range from small devices such as early electronic desk calculators and watches to notebook PCs, word processors, liquid crystal projectors, liquid crystal televisions, car navigation systems, and indoor and outdoor measuring devices. In addition, it can be applied to lenses with a polarizing function, and has recently been applied to sunglasses with improved visibility and polarized glasses corresponding to 3D TVs, etc. Since the uses of the above polarizing plate are widespread, the usage conditions are also wide ranging from low temperature to high temperature, low humidity to high humidity, and low light intensity to high light intensity, so a polarizing plate with high polarization performance and high durability is required. there is.

Currently, a polarizing plate is a polarizing film substrate such as a stretched and oriented film of polyvinyl alcohol or its derivatives, or a polyene-based film oriented by generating polyene through dehydrochlorination of a polyvinyl chloride film or dehydration of a polyvinyl alcohol-based film, It is manufactured by dyeing or containing iodine or dichroic dyes. These are substances that greatly affect the polarization characteristics and durability of a polarizing plate. Iodine-based polarizing films using iodine are excellent in polarization performance, but are weak against water and heat, and have problems with their durability when used for a long time in high temperature and high humidity conditions. In order to improve durability, methods such as treatment with formalin or an aqueous solution containing boric acid, or using a polymer film with low moisture permeability as a protective film can be considered, but the effect cannot be said to be sufficient. On the other hand, dye-based polarizing films using dyes have superior moisture resistance and heat resistance compared to iodine-based polarizing films, but polarization performance is generally insufficient.

Until recently, images on liquid crystal displays were displayed at high brightness to improve image clarity. As hybrid cars and mobile devices equipped with such displays are demanding longer battery operating times, liquid crystal display manufacturers are developing polarizers that can maintain image brightness and color vividness even if the luminance is lowered to reduce power consumption. This has been demanded.

However, in a polarizing film made by adsorbing and aligning various types of dyes to a polymer film, if there is light leakage (color leakage) of a specific wavelength in the wavelength range of the visible light range, when the polarizing film is mounted on a liquid crystal panel, dark Depending on the condition, the color of the liquid crystal display may change. Therefore, when a polarizing film is mounted on a liquid crystal display device, in order to prevent discoloration of the liquid crystal display due to color leakage of a specific wavelength in a dark state, a neutral-colored polarizing film in which various types of dyes are dyed or contained in a polymer film is used. Therefore, the orthogonal transmittance (orthogonal transmittance) in the wavelength range of the visible light range must be uniformly low. In addition, for in-vehicle liquid crystal displays, polarizers that do not change polarization are also required because the high-temperature and high-humidity environment inside a car in the summer is present. Previously, an iodine-based polarizer with good polarization performance and neutral gray color was used. However, as described above, the iodine-based polarizing plate has the problem of insufficient light resistance, heat resistance, and heat and moisture resistance. To solve this problem, dye-based neutral gray polarizers dyed or containing various types of dichroic dyes came to be used. Dye-based neutral gray polarizers are generally used by combining dyes of red, blue, and yellow, which are the three primary colors of light. However, as described above, the polarization performance of the dye-based neutral gray polarizer is not sufficient. Therefore, it was necessary to develop dichroic dyes with good polarization performance for each of the three primary colors.

The characteristic of the dye system is that, as described above, in order to control the components of the three primary colors of light, they are dyed or contain independent dyes corresponding to them. Light sources used in recent liquid crystal display panels include a cold cathode tube type or an LED type, but the light source wavelength emitted from them differs depending on the type, and even for the same type, it often differs depending on each panel manufacturer. Therefore, in developing a dichroic dye with good polarization performance, it is especially important to design a dichroic dye with an absorption wavelength that matches the wavelength of the light source.

Examples of dyes used in the production of the dye-based polarizing film as described above include water-soluble azo compounds described in Patent Documents 1 to 5, etc.

Japanese Patent No. 2622748 Japanese Patent Publication No. 2001-33627 Japanese Patent Publication No. 2009-132794 Japanese Patent No. 4270486 Japanese Patent No. 4360100

dye chemistry; Written by Yutaka Hosoda, published by Kihodo (技報堂), 1957

One object of the present invention is to provide a high-performance polarizing plate having excellent polarization performance and moisture resistance, heat resistance, and light resistance. Another object of the present invention is a polarizing plate that exhibits a neutral gray color obtained by adsorbing and orienting two or more types of dichroic dyes on a polymer film, which has no orthogonal color leakage in the wavelength range of the visible light region and has excellent polarization performance and The object is to provide a high-performance polarizing plate having moisture resistance, heat resistance, and light resistance.

An additional purpose is to provide a dye-based neutral gray polarizer for in-vehicle liquid crystal displays, a high-performance polarizer with good brightness, polarization performance, durability, and light fastness.

The present inventors conducted intensive research to achieve this objective, and as a result found that polarizing films and polarizing plates containing specific azo compounds and their salts have excellent polarization performance, moisture resistance, heat resistance, and light resistance, and completed the present invention. did.

That is, the present invention is <1>

Equation (1)

[Formula 1]

(In the formula, A is A ₁ : a phenyl group having a substituent, or A ₂ : a hydrogen atom, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, and/or a naphthyl group having a sulfo group, and R ₁ to R ₄ each independently represent a hydrogen atom, an alkyl group with 1 to 4 carbon atoms, or an alkoxy group with 1 to 4 carbon atoms)

Azo compound or its salt represented by,

<2>

In the above formula (1), R ₁ to R ₄ are each independently a hydrogen atom, a methyl group or a methoxy group, an azo compound or a salt thereof according to <1>;

<3>

In the above formula (1), A is A ₁ : a phenyl group having a substituent, at least one of the substituents is a sulfo group or a carboxyl group, and the other substituents are a hydrogen atom, a sulfo group, a carboxyl group, or an alkyl group having 1 to 4 carbon atoms. , an alkoxy group having 1 to 4 carbon atoms, a halogen group, a nitro group, an amino group, an alkyl-substituted amino group having 1 to 4 carbon atoms, or an alkyl-substituted acylamino group having 1 to 4 carbon atoms, or the azo compound according to <1> or <2>. salt,

<4>

Equation (2)

[Formula 2]

(In the formula, at least one of R ₃ and R ₄ is a sulfo group, the others represent a hydrogen atom, a sulfo group, a carboxyl group, a methyl group, or a methoxy group, and R ₅ to R ₈ are each independently a hydrogen atom or a carbon number. (represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms)

Azo compound or its salt represented by,

<5>

In the above formula (2), R ₅ to R ₈ are each independently a hydrogen atom, a methyl group or a methoxy group, the azo compound or salt thereof according to <4>,

<6>

In the above formula (1), A is expressed in the following formula (3)

[Formula 3]

(In the formula, R ₅ represents a hydrogen atom, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a sulfo group, and m represents an integer of 1 to 3.)

The azo compound according to <1> or <2>, or a salt thereof,

<7>

Equation (4)

[Formula 4]

(Wherein, R ₆ represents a hydrogen atom, a hydroxyl group, or an alkoxy group having 1 to 4 carbon atoms, and R ₇ to R ₁₀ each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. represents an alkoxy group of 4, and n represents an integer of 1 to 3)

Azo compound or its salt represented by,

<8>

In the above formula (4), R ₆ is a hydrogen atom and n is 2, the azo compound or salt thereof described in <7>,

<9>

In the above formula (4), R ₇ to R ₁₀ are each independently a hydrogen atom, a methyl group or a methoxy group, the azo compound or salt thereof according to <7> or <8>,

<10>

In the formula (4), the azo compound or salt thereof according to any one of <7> to <9>, wherein one or both of R ₇ to R ₁₀ are methoxy groups;

<11>

A dye-based polarizing film comprising a polarizing film base material containing the azo compound or its salt according to any one of <1> to <10>,

<12>

A dye-based polarizing film comprising a polarizing film base material containing the azo compound or salt thereof according to any one of <1> to <10> and one or more organic dyes other than these;

<13>

The dye-based polarizing film according to <11> or <12>, wherein the polarizing film base is a film made of polyvinyl alcohol resin or a derivative thereof,

<14>

A dye-based polarizing plate that can be obtained by bonding a transparent protective layer to at least one side of the dye-based polarizing film according to any one of <11> to <13>,

<15>

A polarizing plate for a liquid crystal display using the dye-based polarizing film according to any one of <11> to <13> or the dye-based polarizing plate according to <14>,

<16>

A neutral gray polarizing plate for vehicle-mounted use, using the dye-based polarizing film according to any one of <11> to <13>, the dye-based polarizing plate according to <14>, or the polarizing plate for liquid crystal display according to <15>,

<17>

A liquid crystal display device using the dye-based polarizing plate according to <14>, the polarizing plate for liquid crystal display according to <15>, or the neutral gray polarizing plate for vehicle-mounted use according to <16>.

It's about.

The azo compound or its salt of the present invention is useful as a dye for a polarizing film. And polarizing films containing these compounds have high polarization performance comparable to polarizing films using iodine and are also excellent in durability. Therefore, it is suitable for use in various liquid crystal displays and liquid crystal projectors, in vehicle applications requiring high polarization performance and durability, and in display applications for industrial instruments used in various environments.

The azo compound of the present invention is represented by the above formula (1). A in the above formula (1) is A ₁ : a phenyl group having a substituent, or A ₂ : a hydrogen atom, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, or a naphthyl group having a sulfo group. , R ₁ to R ₄ each independently represent a hydrogen atom, an alkyl group with 1 to 4 carbon atoms, or an alkoxy group with 1 to 4 carbon atoms.

Hereinafter, the compound of the formula (1) will be described, but in the substituents below, those having 1 to 4 carbon atoms are referred to as “lower.”

In addition, in this application, the “substituent” contains a hydrogen atom, but is explained as a “substituent” for convenience.

A ₁ in the above formula (1) represents a phenyl group having a substituent, and the substituent may be a hydrogen atom, a sulfo group, a carboxyl group, a lower alkyl group, a lower alkoxy group, a halogen group, a nitro group, an amino group, a lower alkyl-substituted amino group, or A lower alkyl-substituted acylamino group is preferred, and when it has two or more substituents, at least one of the substituents is a sulfo group or a carboxyl group, and other substituents include a sulfo group, a hydrogen atom, a lower alkyl group, a lower alkoxy group, Carboxyl group, chloro group, bromo group, nitro group, amino group, lower alkyl substituted amino group, and lower alkyl substituted acylamino group are preferred. More preferably, they are a sulfo group, a hydrogen atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a carboxyl group, a chloro group, a nitro group, and an amino group, and particularly preferably a sulfo group, a carboxyl group, a hydrogen atom, a methyl group, and a methoxy group. There are no particular limitations on the substitution position, but a combination of the 2-position and the 4-position, or the 3-position and the 5-position is preferred.

A ₂ in the above formula (1) represents a naphthyl group having a substituent, and the substituent is preferably a hydrogen atom, a sulfo group, a hydroxyl group, a lower alkoxy group having a sulfo group, or a sulfo group. More preferably, A ₂ is a naphthyl group represented by the above formula (3), R ₅ represents a hydrogen atom, a hydroxyl group, an alkoxy group having 1 to 5 carbon atoms or a sulfo group, or a sulfo group, and m is 1. It is preferable that it is ~3. Additionally, the position of the sulfone group may be located at any benzene nucleus in the naphthalene ring. The lower alkoxy group having a sulfo group is preferably straight-chain alkoxy, the substitution position of the sulfo group is preferably at the end of the alkoxy group, and more preferably 3-sulfopropoxy group or 4-sulfobutoxy group. There is no particular limitation on the substitution position of the substituent of the naphthyl group, but as shown in the following formula (5), when there are two substituents, it is a combination of the 5-position and the 7-position, or the 6-position and the 8-position. is preferred, and when there are three substituents, the 3-position, 5-position, 7-position, 3-position, 6-position, and 8-position are preferred.

[Formula 5]

In the above formula (1), R ₁ to R ₄ may have a substituent, and the substituent is not particularly limited. Preferably, R ₁ to R ₄ each independently represent a hydrogen atom, a lower alkyl group, or a lower alkoxy group, and more preferably, a hydrogen atom, a methyl group, an ethyl group, and a lower alkoxy group such as a methoxy group or an ethoxy group, Particularly preferred are a hydrogen atom, a methyl group, an ethyl group, and a methoxy group. The substitution position is preferably described by the number shown in the formula (6) below: only the 2-position, only the 5-position, a combination of the 2-position and the 6-position, and a combination of the 2-position and the 5-position. , a combination of the 3-position and the 5-position is preferred, and more preferably, only the 2-position, only the 5-position, or a combination of the 2-position and the 5-position. In addition, in the above, only the 2-position and only the 5-position refer to having one substituent other than a hydrogen atom only at the 2- or 5-position.

[Formula 6]

Next, specific examples of the azo compound represented by the formula (1) used in the present invention are given below. In addition, the sulfo group, carboxyl group, and hydroxyl group in the formula are expressed in the form of free acid.

[Formula 7]

[Formula 8]

[Formula 9]

[Formula 10]

[Formula 11]

[Formula 12]

The azo compound and its salt represented by the above formula (1) are prepared by diazotization, coupling, and ureidation as described in patent document 3 according to a conventional azo dye production method as described in non-patent document 1. It can be easily manufactured by doing this.

As a specific production method, aminobenzene (aniline) or aminonaphthalene (naphthylamine) having a substituent as shown in the following formula (i) is diazotized by the same production method as in Non-Patent Document 1, and obtained by the following formula (ii) ) is coupled with anilines to obtain a monoazoamino compound represented by the following formula (iii).

[Formula 13]

(In the formula, A represents the same meaning as in the above formula (1))

[Formula 14]

(In the formula, R ₁ and R ₂ have the same meaning as in the above formula (1))

[Formula 15]

(In the formula, A, R ₁ , R ₂ have the same meaning as in the above formula (1))

Next, this monoazoamino compound (iii) is diazotized and subjected to secondary coupling with anilines of the following formula (iv) to obtain a disazoamino compound represented by the following formula (v).

[Formula 16]

(In the formula, R ₃ and R ₄ have the same meaning as in the above formula (1))

[Formula 17]

(In the formula, A, R ₁ to R ₄ have the same meaning as in the above formula (1))

By reacting this disazoamino compound (v) with phenyl chloroformate, an azo compound of the above formula (1) is obtained.

In the above reaction, the diazotization process follows the rule of mixing a nitrite such as sodium nitrite into an aqueous solution or suspension of a mineral acid such as hydrochloric acid or sulfuric acid of the diazo component, or mixing nitrite into a neutral or slightly alkaline aqueous solution of the diazo component. It is carried out by the inverse method of adding it and mixing it with the mineral acid. The appropriate temperature for diazotization is -10 to 40°C. In addition, the coupling process with anilines is performed by mixing an acidic aqueous solution such as hydrochloric acid or acetic acid with each of the above-mentioned diazo solutions, at a temperature of -10 to 40°C, and under acidic conditions of pH 2 to 7.

The monoazoamino compound and disazoamino compound obtained by coupling may be taken out as is, precipitated by acidification or salting out and filtered, or may proceed to the next step in a solution or suspension state. If the diazonium salt is poorly soluble and is in suspension, it can be filtered and used as a press cake in the next coupling process.

As a specific method of the ureidation reaction between a disazoamino compound and phenyl chloroformate, it is carried out by the production method shown in Patent Document 3, pp57, at a temperature of 10 to 90°C, and under neutral to alkaline conditions of pH 7 to 11. After completion of the reaction, it is precipitated by salting out and taken out by filtration. In addition, when purification is necessary, salting-out may be repeated or an organic solvent may be used to precipitate in water. Examples of organic solvents used for purification include water-soluble organic solvents such as alcohols such as methanol and ethanol, and ketones such as acetone.

In addition, in the present invention, the azo compound represented by the above formula (1) can be used not only as a free acid but also as a salt of the azo compound. Such salts include alkali metal salts such as lithium salts, sodium salts, and potassium salts, and organic salts such as ammonium salts and amine salts. Sodium salt is generally used.

The starting raw material for synthesizing a water-soluble dye in which A in the formula ( ₁ ) is A 1 is aromatic amines (A ₁ -NH ₂ ). The substituent may include a hydrogen atom, a sulfo group, a lower alkyl group, a lower alkoxy group, a carboxyl group, a nitro group, a halogen group, an amino group, a lower alkyl-substituted amino group, or a lower alkyl-substituted acylamino group. Preferred are a sulfo group, a hydrogen atom, methyl group, ethyl group, methoxy group, ethoxy group, carboxyl group, chloro group, bromo group, nitro group, amino group, dimethylamino group, and acetyl group, and particularly preferably a sulfo group, a hydrogen atom, and a methyl group. , methoxy group, carboxyl group, chloro group, and amino group. Moreover, it is more preferable that at least one of the substituents is a sulfo group or a carboxyl group, and, like aromatic amines having R ₃ to R ₄ represented by the above formula (2), it is even more preferable that the number of substituents is 2. When A is a phenyl group A ₁ having a substituent, examples of phenylamines (A ₁ -NH ₂ ) include 4-aminobenzenesulfonic acid, 3-aminobenzenesulfonic acid, 2-aminobenzenesulfonic acid, 4-aminobenzoic acid, and 2-aminobenzenesulfonic acid. Amino-5-methylbenzenesulfonic acid, 2-amino-5-ethylbenzenesulfonic acid, 2-amino-5-propylbenzenesulfonic acid, 2-amino-5-butylbenzenesulfonic acid, 4-amino-3-methylbenzenesulfonic acid, 4- Amino-3-ethylbenzenesulfonic acid, 4-amino-3-propylbenzenesulfonic acid, 4-amino-3-butylbenzenesulfonic acid, 2-amino-5-methoxybenzenesulfonic acid, 2-amino-5-ethoxybenzenesulfonic acid, 2-Amino-5-propoxybenzenesulfonic acid, 2-amino-5-butoxybenzenesulfonic acid, 4-amino-3-methoxybenzenesulfonic acid, 4-amino-3-ethoxybenzenesulfonic acid, 4-amino-3- Propoxybenzenesulfonic acid, 4-amino-3-butoxybenzenesulfonic acid, 2-amino-4-sulfobenzoic acid, 2-amino-5-sulfobenzoic acid, etc., 5-aminoisophthalic acid, 2-amino-5-chlorobenzenesulfonic acid , 2-Amino-5-bromobenzenesulfonic acid, 2-amino-5-nitrobenzenesulfonic acid, 2,5-diaminobenzenesulfonic acid, 2-amino-5-dimethylaminobenzenesulfonic acid, 2-amino-5-diethyl Aminobenzene sulfonic acid, 5-acetamide-2-aminobenzene sulfonic acid, 4-aminobenzene-1,3-disulfonic acid, 2-aminobenzene-1,4-disulfonic acid, etc. are mentioned. Particular preference is given to 4-aminobenzenesulfonic acid, 2-amino-5-methoxybenzenesulfonic acid, 4-amino-2-methylbenzenesulfonic acid and 4-aminobenzene-1,3-disulfonic acid.

The starting raw material for synthesizing the water-soluble dye in which A in the formula (1) is A ₂ is a hydrogen atom, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, and/or naphthylamines having a sulfo group ( A ₂ -NH ₂ ). Naphthylamines (A ₂ -NH ₂ ) having a hydrogen atom, a hydroxyl group, and a sulfo group include, for example, 4-aminonaphthalenesulfonic acid, 7-aminonaphthalene-3-sulfonic acid, 1-aminonaphthalene-6-sulfonic acid, 1-aminonaphthalene-7-sulfonic acid, 7-aminonaphthalene-1,3-disulfonic acid, 6-aminonaphthalene-1,3-disulfonic acid, 7-aminonaphthalene-1,5-disulfonic acid, 7-aminonaphthalene- 1,3,6-trisulfonic acid, etc. can be mentioned. Preferably 7-aminonaphthalene-3-sulfonic acid, 6-aminonaphthalene-1,3-disulfonic acid, 7-aminonaphthalene-1,4-disulfonic acid, 7-aminonaphthalene-1,5-disulfonic acid, 2- Amino-8-hydroxy-naphthalene-6-sulfonic acid, 3-amino-8-hydroxynaphthalene-6-sulfonic acid, 1-aminonaphthalene-3,6,8-trisulfonic acid, 2-amino-5-hydroxynaphthalene -1,7-disulfonic acid, 1-aminonaphthalene-3,8-disulfonic acid, etc. In the compound where A is represented by the above formula (3), examples of the hydrogen atom, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, and naphthylamines (A ₂ -NH ₂ ) having a sulfo group include, for example, 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, 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, 7-amino-3-(3-sulfopropoxy)naphthalene-1,5-disulfonic acid, etc.

In the above formula (1), the substituents of R ₁ to R ₄ in the primary and secondary coupling components are not particularly limited, but preferably each independently represents a hydrogen atom, a lower alkyl group, or a lower alkoxy group, and is more preferred. Preferably, it is a hydrogen atom, a methyl group, an ethyl group, a methoxy group, or an ethoxy group, and particularly preferably, it is a lower alkoxy group having a hydrogen atom, a methyl group, an ethyl group, a methoxy group, or a sulfo group.

The substitution position is preferably only the 2-position, only the 5-position, a combination of the 2-position and the 6-position, a combination of the 2-position and the 5-position, and a combination of the 3-position and the 5-position. And, especially preferably, only the 2-position, only the 5-position, or a combination of the 2-position and the 5-position.

Anilines that are primary and/or secondary couplers include aniline, 2-methylaniline, 2-ethylaniline, 2-propylaniline, 2-butylaniline, 3-methylaniline, 3-ethylaniline, and 3-propylaniline. , 3-butylaniline, 2,5-dimethylaniline, 2,5-diethylaniline, 2-methoxyaniline, 2-ethoxyaniline, 2-propoxyaniline, 2-butoxyaniline, 3-methoxyaniline , 3-ethoxyaniline, 3-propoxyaniline, 3-butoxyaniline, 2-methoxy-5-methylaniline, 2,5-dimethoxyaniline, 3,5-dimethylaniline, 2,6-dimethylaniline or 3,5-dimethoxyaniline, etc.

The amino group of these anilines may be protected. Examples of the protecting group include the ω-methane sulfone group.

In addition, in the dye-based polarizing film or dye-based polarizing plate of the present invention, in addition to the azo compound represented by the above formula (1) and its salts used alone or in combination, one or more types of other organic dyes may be used in combination as needed. do. There is no particular limitation on the organic dye to be incorporated, but a dye having absorption characteristics in a wavelength range different from that of the azo compound or its salt of the present invention and having high dichroism is preferable. For example, CI.I.Direct.Yellow 12, CI.I.Direct.Yellow 28, CI.I.Direct.Yellow 44, CI.I.Direct.Orange 26, CI.I.Direct.Orange 39, CI. I.I.Direct.Orange 71, CI.I.Direct.Orange 107, CI.I.Direct.Red 2, CI.I.Direct.Red 31, CI.I.Direct.Red 79, CI.I.Direct.Red 81, CI.I.Direct.Red 247, CI.I.Direct.Blue 237, CI.I.Direct.Blue 273, CI.I.Direct.Blue 274, CI.I.Direct.Green 80, CI.I. Representative examples include the dyes described in Direct.Green 59 and Patent Documents 1 to 5, but depending on the purpose, it is more preferable to use the dye developed for polarizing plates as described in Patent Documents 1 to 5. . These pigments are used as free acids or salts of alkali metals (e.g. Na salts, K salts, Li salts), ammonium salts, and amines.

When using other organic dyes together as needed, the types of dyes to be blended are different depending on whether the target polarizing film is a neutral-colored polarizing film, a color polarizing film for a liquid crystal projector, or another color polarizing film. The mixing ratio is not particularly limited, but generally, based on the mass of the azo compound of formula (1) and its salt, the total amount of at least one of the above organic dyes is in the range of 0.1 to 10 parts by mass. It is desirable to do so.

The azo compound and its salt represented by the above formula (1) are mixed with or applied to a polarizing film base material (e.g., polymer film), if necessary, along with other dyes, with liquid crystals that are aligned by a known method. By orienting by a method, a polarizing film having various colors or neutral colors can be manufactured. The obtained polarizer is attached with a protective film, and as a polarizer, a protective layer or an AR (anti-reflection) layer and a support are formed as needed, and is used in liquid crystal projectors, electronic desktop calculators, watches, note PCs, word processors, liquid crystal televisions, and cars. It is used in navigation, indoor and outdoor measuring instruments and indicators, as well as lenses and glasses.

The polarizing film base material (polymer film) used in the dye-based polarizing film of the present invention is preferably a film made of polyvinyl alcohol resin or a derivative thereof, and specific examples include polyvinyl alcohol or a derivative thereof, and any of these in ethylene. , those modified with olefins such as propylene, or unsaturated carboxylic acids such as crotonic acid, acrylic acid, methacrylic acid, and maleic acid. Among them, a film made of polyvinyl alcohol or a derivative thereof is preferably used in terms of dye adsorption and orientation properties. The thickness of the base material is usually about 30 to 100 μm, preferably about 50 to 80 μm.

When such a polarizing film base material (polymer film) is made to contain the azo compound of the above formula (1) and its salt, a method of dyeing the polymer film is usually adopted. Dyeing is carried out, for example, as follows. First, a dye bath is prepared by dissolving the azo compound of the present invention, its salt, and, if necessary, other dyes in water. The dye concentration in the dye bath is not particularly limited, but is usually selected in the range of about 0.001 to 10 mass%. Additionally, a dyeing auxiliary may be used as needed, and for example, it is preferable to use agarose at a concentration of about 0.1 to 10% by mass. The polymer film is immersed in the dye bath prepared in this way for 1 to 10 minutes to perform dyeing. The dyeing temperature is preferably about 40 to 80°C.

The orientation of the azo compound of the formula (1) and its salt is carried out by stretching the polymer film dyed as described above. As a stretching method, any known method, such as a wet method or a dry method, may be used. In some cases, stretching of the polymer film may be performed before dyeing. In this case, orientation of the water-soluble dye is carried out at the time of dyeing. The polymer film containing and orientating the water-soluble dye is, if necessary, subjected to post-treatment such as boric acid treatment by a known method. This post-processing is performed for the purpose of improving the light transmittance and polarization degree of the polarizing film. The conditions for boric acid treatment vary depending on the type of polymer film used or the type of dye used, but generally, the boric acid concentration of the aqueous boric acid solution is in the range of 0.1 to 15 mass%, preferably in the range of 1 to 10 mass%. , the treatment is carried out by immersing the material in a temperature range of 30 to 80°C, preferably 40 to 75°C, for 0.5 to 10 minutes. Additionally, if necessary, a fix treatment may also be performed with an aqueous solution containing a cationic polymer compound.

The dye-based polarizing film of the present invention obtained in this way can be used as a polarizing plate by bonding a transparent protective film excellent in optical transparency and mechanical strength to one or both sides of the dye-based polarizing film. Materials forming the protective film include, for example, cellulose acetate-based films and acrylic-based films, as well as fluorine-based films such as tetrafluoroethylene/hexafluoropropylene-based copolymers, polyester resins, polyolefin resins, or polyamide-based resins. etc. are used. Preferably, triacetylcellulose (TAC) film or cycloolefin-based film is used. The thickness of the protective film is typically 40 to 200 μm.

Adhesives that can be used to bond the polarizing film and the protective film include polyvinyl alcohol-based adhesives, urethane emulsion-based adhesives, acrylic adhesives, and polyester-isocyanate-based adhesives, with polyvinyl alcohol-based adhesives being preferred. .

A transparent protective layer may be further formed on the surface of the dye-based polarizing plate of the present invention. Examples of the protective layer include an acrylic or polysiloxane-based hard coat layer or a urethane-based protective layer. Additionally, in order to further improve the light transmittance of the single plate, it is preferable to form an AR layer on this protective layer. The AR layer can be formed, for example, by vapor deposition or sputtering of a material such as silicon dioxide or titanium oxide, or by thinly applying a fluorine-based material. Additionally, the dye-based polarizing plate of the present invention can also be used as an elliptically polarizing plate to which a retardation plate is attached.

The dye-based polarizing plate of the present invention constructed in this way has a neutral color, has no orthogonal color leakage in the wavelength range of the visible light region, has excellent polarization performance, and does not cause discoloration or deterioration of polarization performance even under high temperature and high humidity conditions. It has the characteristic of having little light leakage in the orthogonal phase in the visible light region.

The neutral gray polarizing plate for vehicle-mounted use in the present invention contains, as a dichroic dye, the azo compound represented by the above formula (1) and its salt, together with the other organic dyes mentioned above, if necessary. In addition, the polarizing film used in the color polarizing plate for a liquid crystal projector of the present invention is also manufactured by the above manufacturing method. These are used as a neutral gray polarizing plate for vehicle applications by additionally attaching a protective film to form a polarizing plate, and forming a protective layer, AR layer, and support as necessary.

As a color polarizer for a liquid crystal projector, the required wavelength range of the polarizer (A. When using an ultra-high pressure mercury lamp; 420 to 500 ㎚ for the blue channel, 500 to 580 ㎚ for the green channel, 600 to 680 ㎚ for the red channel, B. 3 primary colors Peak wavelength when using an LED lamp (430 to 450 nm for the blue channel, 520 to 535 nm for the green channel, and 620 to 635 nm for the red channel), the average light transmittance of a single panel is 39% or more, and the average light transmittance of the orthogonal position is This is 0.4% or less, more preferably, the average light transmittance of the single plate in the required wavelength range of the polarizing plate is 41% or more, and the average light transmittance of the orthogonal phase is 0.3% or less, and more preferably 0.2% or less. More preferably, the average light transmittance of the single plate in the required wavelength range of the polarizing plate is 42% or more, and the average light transmittance of the orthogonal phase is 0.1% or less. The color polarizer for a liquid crystal projector of the present invention has brightness and excellent polarization performance as described above.

In addition, the single plate average light transmittance is the ray in a specific wavelength range when natural light is incident on a single polarizing plate (hereinafter simply referred to as a polarizing plate, the same meaning is used) without forming a support such as an AR layer or a transparent glass plate. This is the average value of transmittance. The average light transmittance in orthogonal positions is the average value of the light transmittances in a specific wavelength range when natural light is incident on two polarizing plates arranged in orthogonal orientation directions.

The neutral gray polarizing plate for vehicle use of the present invention is preferably a polarizing plate in which the AR layer is formed on a polarizing plate composed of a polarizing film and a protective film, and the AR layer is attached, and the AR layer is attached to a support such as a transparent resin. And a polarizing plate with a support attached thereto is more preferable.

The neutral gray polarizing plate for vehicle-mounted use of the present invention is usually used as a polarizing plate with a support attached thereto. Since the support attaches a polarizing plate, it is preferable to have a flat portion, and since it is used for optical purposes, a transparent substrate is preferable. Transparent substrates are roughly divided into inorganic substrates and organic substrates, and include inorganic substrates such as soda glass, borosilicate glass, quartz substrate, sapphire substrate, and spinel substrate, as well as acrylic, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, and cycloolefin. Examples include organic substrates such as polymers, but organic substrates are preferred. The thickness and size of the transparent substrate can be any desired size. In addition, in order to further improve the single plate light transmittance of the polarizing plate with a transparent substrate, it is desirable to form an AR layer on one or both of the support surface or the polarizing plate surface.

In order to manufacture a color polarizing plate with a support for vehicle-mounted use, for example, a transparent adhesive (adhesive) agent may be applied to the flat surface of the support, and then the dye-based polarizing plate of the present invention may be attached to this applied surface. Alternatively, a transparent adhesive (adhesive) agent may be applied to the polarizing plate, and then a support may be attached to this applied surface. The adhesive (adhesive) agent used here is preferably of an acrylic acid ester type, for example. In addition, when using this polarizing plate as an elliptically polarizing plate, the retardation plate side is usually attached to the support side, but the polarizing plate side may be attached to the transparent substrate.

That is, in a liquid crystal display for vehicle-mounted use using the dye-based polarizing plate of the present invention, the dye-based polarizing plate of the present invention is disposed on one or both of the incident side and the exit side of the liquid crystal cell. The polarizing plate may or may not be in contact with the liquid crystal cell, but from the viewpoint of durability, it is preferable not to be in contact. On the emission side, when the polarizing plate is in contact with a liquid crystal cell, the dye-based polarizing plate of the present invention using the liquid crystal cell as a support can be used. When the polarizing plate is not in contact with the liquid crystal cell, it is preferable to use the dye-based polarizing plate of the present invention using a support other than the liquid crystal cell. Moreover, from the viewpoint of durability, it is preferable that the dye-based polarizing plate of the present invention is disposed on either the incident side or the exit side of the liquid crystal cell, and the polarizing plate side of the dye-based polarizing plate of the present invention is placed on the liquid crystal cell side, and the support side is placed on the liquid crystal cell side. It is desirable to place it on the light source side. In addition, the incident side of the liquid crystal cell refers to the light source side, and the opposite side is referred to as the emission side.

In the liquid crystal display for automotive use using the dye-based polarizing plate of the present invention, the liquid crystal cell used is, for example, an active matrix type, and the liquid crystal is enclosed between a transparent substrate on which electrodes and TFTs are formed and a transparent substrate on which a counter electrode is formed. ) is preferably formed. Light emitted from a light source such as a cold cathode lamp or a white LED passes through a neutral gray polarizer, and then passes through a liquid crystal cell, a color filter, and a neutral gray polarizer to be projected onto a display screen.

The neutral gray polarizer for vehicle use constructed in this way has excellent polarization performance and has the characteristic of not causing discoloration or deterioration of polarization performance even under high temperature and high humidity conditions inside the vehicle.

Example

Hereinafter, the present invention will be described in more detail through examples, but these are illustrative and do not limit the present invention at all. % and parts in examples are based on mass unless otherwise specified.

(Example 1)

Add 25.3 parts of 4-aminobenzene-1,3-disulfonic acid to 500 parts of water, cool, add 31.3 parts of 35% hydrochloric acid at 10°C or lower, then add 6.9 parts of sodium nitrite, and cool at 5 to 10°C. By stirring for a while, diazotization was achieved. 10.7 parts of 3-methylaniline were added thereto, and while stirring at 10 to 30°C, sodium carbonate was added to adjust the pH to 3, further stirred to complete the coupling reaction, and filtered to obtain monoazoyl azoate represented by the following formula (M1). 33.4 parts of amino compound were obtained.

[Formula 18]

33.4 parts of the obtained monoazoamino compound was added to 400 parts of water, dissolved in sodium hydroxide, 28.2 parts of 35% hydrochloric acid were added at 10 to 30°C, and then 6.2 parts of sodium nitrite were added, and stirred at 20 to 30°C for 1 hour. It was diaharmonized. 9.6 parts of 3-methylaniline were added thereto, and while stirring at 20 to 30°C, sodium carbonate was added to adjust the pH to 3, further stirred to complete the coupling reaction, and filtered to obtain disazo represented by the formula (M2) below. 46.1 parts of amino compound were obtained.

[Formula 19]

35.2 parts of the obtained disazoamino compound was added to 250 parts of water, dissolved in sodium hydroxide, and 5.6 parts of phenyl chloroformate were stirred at 30 to 70°C for 2 hours to ureide. It was salted out with sodium chloride and filtered to obtain 28.9 parts of the azo compound of the present invention (hereinafter also referred to as ureide compound) represented by the above formula (7). The maximum absorption wavelength of this compound in a 20% pyridine aqueous solution was 462 nm.

(Example 2)

In formula (7), the primary coupler is changed from 10.7 parts of 3-methylaniline to 12.1 parts of 2,5-dimethylaniline, and the secondary coupler is changed from 9.6 parts of 3-methylaniline to 12.3 parts of 2-methoxy-5-methylaniline. In the same manner as in Example 1 except for this, 31.5 parts of the ureide compound of the present invention represented by the above formula (8) was obtained. The maximum absorption wavelength of this compound in a 20% aqueous pyridine solution was 469 nm.

(Example 3)

Add 30.3 parts of 7-aminonaphthalene-1,3-disulfonic acid to 400 parts of water and dissolve with sodium hydroxide. Add 10.4 parts of 35% hydrochloric acid, then add 6.9 parts of sodium nitrite, and stir for 1 hour. 12.1 parts of 2,5-dimethylaniline was added thereto, and while stirring at 30 to 40°C, sodium carbonate was added to adjust the pH to 5, and further stirred to complete the coupling reaction to obtain a monoazoamino compound represented by the following formula (M3). got 39.2 copies.

[Formula 20]

After dispersing 50.4 parts of the monoazo compound of the above formula (65) in 600 parts of water, 9.4 parts of 35% hydrochloric acid are added, followed by 6.2 parts of sodium nitrite, and the mixture is stirred at 25 to 30°C for 2 hours to diazotize. 12.3 parts of 2-methoxy-5-methylaniline was added thereto, and while stirring at 30 to 40° C., sodium carbonate was added to adjust the pH to 3, and further stirred to complete the coupling reaction to obtain diss represented by the formula (M4) below. 46.6 parts of azoamino compound were obtained.

[Formula 21]

46.6 parts of the obtained disazoamino compound was added to 250 parts of water, dissolved in sodium hydroxide, and 6.2 parts of phenyl chloroformate were stirred at 30 to 70°C for 2 hours to ureide. It was salted out with sodium chloride and filtered to obtain 35.2 parts of the azo compound of the present invention represented by the above formula (31). The maximum absorption wavelength of this compound in a 20% aqueous pyridine solution was 455 nm.

(Example 4)

31.4 parts of the azo compound of the present invention represented by the above formula (32) was obtained in the same manner as in Example 3 except that 2,5-dimethylaniline was changed to 2,5-dimethoxyaniline. The maximum absorption wavelength of this compound in a 20% pyridine aqueous solution was 492 nm.

(Example 5)

The same procedure as in Example 3 was carried out except that 2,5-dimethylaniline was changed to 2,5-dimethoxyaniline and 2-methoxy-5-methylaniline was changed to 2,5-dimethylaniline. 30.6 parts of the azo compound of the present invention represented by formula (33) was obtained. The maximum absorption wavelength of this compound in a 20% aqueous pyridine solution was 491 nm.

(Example 6)

35.7 parts of the azo compound of the present invention represented by the above formula (34) was obtained in the same manner as in Example 3 except that 2,5-dimethylaniline was changed to 2-methoxy-5-methylaniline. The maximum absorption wavelength of this compound in a 20% aqueous pyridine solution was 483 nm.

(Example 7)

The procedure was the same as in Example 3 except that 2,5-dimethylaniline was replaced with 2-methoxy-5-methylaniline and 2-methoxy-5-methylaniline was replaced with 2,5-dimethylaniline. 35.3 parts of the azo compound of the present invention represented by the above formula (35) was obtained. The maximum absorption wavelength of this compound in a 20% pyridine aqueous solution was 463 nm.

(Example 8)

This product represented by the above formula (36) was carried out in the same manner as in Example 3 except that 7-aminonaphthalene-1,3-disulfonic acid in Example 3 was changed to 7-aminonaphthalene-1,3,6-trisulfonic acid. 33.8 parts of the inventive azo compound were obtained. The maximum absorption wavelength of this compound in a 20% pyridine aqueous solution was 453 nm.

(Example 9)

The above formula was obtained in the same manner as in Example 3 except that 7-aminonaphthalene-1,3-disulfonic acid was changed to 6-amino-4-(3-sulfopropoxy)naphthalene-2-sulfonic acid. 32.7 parts of the azo compound of the present invention represented by (37) was obtained. The maximum absorption wavelength of this compound in a 20% aqueous pyridine solution was 457 nm.

(Example 10)

29.0 parts of the azo compound of the present invention represented by the above formula (38) was obtained in the same manner as in Example 3 except that 2-methoxy-5-methylaniline was changed to 2,5-dimethylaniline. The maximum absorption wavelength of this compound in a 20% pyridine aqueous solution was 441 nm.

(Example 11)

The formula (39) was obtained in the same manner as in Example 3 except that 2,5-dimethylaniline was changed to 3-methylaniline and 2-methoxy-5-methylaniline was changed to 3,5-dimethylaniline. ) 29.0 parts of the azo compound of the present invention represented by was obtained. The maximum absorption wavelength of this compound in a 20% aqueous pyridine solution was 433 nm.

(Example 12)

The formula (63) was obtained in the same manner as in Example 3 except that 2,5-dimethylaniline was changed to 2-methylaniline and 2-methoxy-5-methylaniline was changed to 2,5-dimethylaniline. ) 34.0 parts of the azo compound of the present invention represented by was obtained. The maximum absorption wavelength of this compound in a 20% pyridine aqueous solution was 449 nm.

(Example 13)

A polyvinyl alcohol film with a thickness of 75 µm was immersed in a 45°C aqueous solution containing 0.03% of the compound of the formula (7) and 0.1% of citric acid obtained in Example 1 for 4 minutes. This film was stretched five times at 50°C in a 3% boric acid aqueous solution, washed with water and dried while maintaining the tension, to obtain a polarizing film of the present invention.

The maximum absorption wavelength of the obtained polarizing film was 482 nm, the polarization coefficient was 99.9%, and it had a high polarization coefficient.

(Example 14)

A polyvinyl alcohol film with a thickness of 75 µm was immersed in a 45°C aqueous solution containing 0.03% of the compound of the formula (31) and 0.1% of citric acid obtained in Example 4 for 4 minutes. This film was stretched five times at 50°C in a 3% boric acid aqueous solution, washed with water and dried while maintaining the tension, to obtain a polarizing film of the present invention.

The maximum absorption wavelength of the obtained polarizing film was 502 nm, the polarization rate was 99.9%, and it had a high polarization rate.

Additionally, the test method is described below.

In measuring the maximum absorption wavelength of the polarizing film and calculating the polarization coefficient, the parallel transmittance and orthogonal transmittance when polarized light was incident were measured and calculated using a spectrophotometer (U-4100 manufactured by Hitachi Ltd.).

Here, the parallel transmittance (Ky) refers to the transmittance when the absorption axis of the absolute polarizer and the absorption axis of the polarizing film are parallel, and the orthogonal transmittance (Kz) refers to the transmittance when the absorption axis of the absolute polarizer and the absorption axis of the polarizing film are orthogonal.

The parallel transmittance and orthogonal transmittance of each wavelength were measured at 1 nm intervals from 380 to 780 nm. Using each measured value, the polarization rate of each wavelength was calculated from the following formula (i), and the highest polarization rate in 380 to 780 nm and the maximum absorption wavelength (nm) were obtained.

Polarization ratio (%) = [(Ky - Kz)/(Ky + Kz)] × 100 (i)

(Example 15)

A polarizing film of the present invention was obtained in the same manner as in Example 13, using the compound of the formula (8) obtained in Example 2 instead of the compound of the formula (7). Table 1 shows the maximum absorption wavelength and change rate of the obtained polarizing film.

(Examples 16 to 19)

In addition, instead of the compound of the formula (31), the azo compound (of the formula (32), (34), (35), (63) described in Example 4, Example 6, Example 7, and Example 12 Compound) was used to obtain a polarizing film of the present invention in the same manner as in Example 14. Table 1 shows the maximum absorption wavelength and polarization coefficient of the obtained polarizing film.

As shown in Table 1, the polarizing films manufactured using these compounds all had high polarization coefficients.

(Test example)

As an indicator of image quality, there is contrast, which represents the difference in luminance between white and black displays, and the maximum absorption wavelength of the polarizing film obtained in Examples 12 and 14, and 13 and 15 to 17, and the contrast at that time. is shown in Table 2. Here, contrast refers to the ratio of parallel transmittance and orthogonal transmittance (contrast = parallel transmittance at the maximum absorption wavelength (Ky)/orthogonal transmittance at the maximum absorption wavelength (Kz)), and the larger this value, the better the polarization performance of the polarizer. indicates that In addition, in the evaluation of polarization performance, samples were prepared so that the parallel transmittance of the maximum absorption wavelength of the polarizing film was the same, and comparison was performed. As shown in Table 2, all polarizing films manufactured using these compounds had high contrast.

(Comparative Example 1)

Instead of the compound of the present invention, compound (II-5) synthesized in the same manner as described in Example 1 in Patent Document 5 was used, and a polarizing film was produced in the same manner as Example 12 of the present invention, and the contrast was calculated. . As shown in Table 2, the compounds of the present invention all showed high contrast and were excellent in polarization performance compared to Comparative Example 1.

(Comparative Example 2)

Instead of the compound of the present invention, compound (4) in Patent Document 4, synthesized in the same manner as the method described in Example 2 in Patent Document 4, was used to prepare a polarizing film in the same manner as Example 13 of the present invention, and contrast was adjusted. Calculated. As shown in Table 2, the compounds of the present invention all showed high contrast and were excellent in polarization performance compared to Comparative Example 2.

(Comparative Example 3)

Instead of the compound of the present invention, compound (I-3) synthesized in the same manner as described in [0077] in Patent Document 5 was used, and a polarizing film was produced in the same manner as Example 13 of the present invention, and the contrast was calculated. . As shown in Table 2, the compounds of the present invention all showed high contrast and were excellent in polarization performance compared to Comparative Example 3.

(Example 20)

The compound of the above formula (7) obtained in Example 1 was mixed at a concentration of 0.2% dye, 0.07% CI Direct Orange 39, 0.02% CI Direct Blue 274, and 0.1% red pepper at 45°C. A polarizing film was manufactured in the same manner as in Example 12 except for using an aqueous solution. The obtained polarizing film had a maximum absorption wavelength of 557 nm, a single plate average transmittance from 380 to 600 nm of 42%, an orthogonal average light transmittance of 0.02%, and a high degree of polarization.

A triacetylcellulose film (TAC film; manufactured by Fuji Photo Film Co., Ltd.; brand name TD-80U) is laminated on both sides of this polarizing film through an adhesive of polyvinyl alcohol aqueous solution, and the dye system of the present invention to which the AR support is attached using an adhesive is laminated. A polarizer (neutral gray polarizer) was obtained. The polarizing plate of the present invention has a high polarization coefficient and exhibits durability over a long period of time even in high temperature and high humidity conditions. In addition, light resistance to long-term exposure was excellent.

(Example 21)

The compound of formula (31) obtained in Example 4 was mixed at a concentration of 0.2% dye, 0.07% CI Direct Orange 39, 0.02% CI Direct Blue 274, and 0.1% red pepper at 45°C. A polarizing film was manufactured in the same manner as in Example 2 except for using an aqueous solution. The obtained polarizing film had a maximum absorption wavelength of 555 nm, a single plate average transmittance from 380 to 600 nm of 42%, an orthogonal average light transmittance of 0.02%, and a high degree of polarization.

A triacetylcellulose film (TAC film; manufactured by Fuji Photo Film Co., Ltd.; brand name TD-80U) is laminated on both sides of this polarizing film through an adhesive of polyvinyl alcohol aqueous solution, and the dye system of the present invention to which the AR support is attached using an adhesive is laminated. A polarizer (neutral gray polarizer) was obtained. The polarizing plate of the present invention has a high polarization coefficient and exhibits durability over a long period of time even in high temperature and high humidity conditions. In addition, light resistance to long-term exposure was excellent.

Claims (17)

Equation (1)
[Formula 1]

(In the formula, A is A ₁ : a phenyl group having a substituent, at least one of the substituents is a sulfo group or a carboxyl group, and the other substituents are a hydrogen atom, a sulfo group, a carboxyl group, an alkyl group with 1 to 4 carbon atoms, or a carbon number 1 It is an alkoxy group, a halogen group, a nitro group, an amino group, an alkyl-substituted amino group with 1-4 carbon atoms, or an alkyl-substituted acylamino group with 1-4 carbon atoms, or A ₂ : a carbon number having a hydrogen atom, a hydroxyl group, or a sulfo group. It is a naphthyl group having 1 to 4 alkoxy groups and/or sulfo groups, and R ₁ to R ₄ each independently represent a hydrogen atom, an alkyl group with 1 to 4 carbon atoms, or an alkoxy group with 1 to 4 carbon atoms)
An azo compound or a salt thereof represented by . According to claim 1,
In the formula (1), R ₁ to R ₄ are each independently a hydrogen atom, a methyl group, or a methoxy group. Equation (2)
[Formula 2]

(In the formula, at least one of R ₃ and R ₄ is a sulfo group, the others represent a hydrogen atom, a sulfo group, a carboxyl group, a methyl group, or a methoxy group, and R ₅ to R ₈ are each independently a hydrogen atom or a carbon number. Represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms)
An azo compound or a salt thereof represented by . According to claim 3,
In the formula (2), an azo compound or a salt thereof wherein R ₅ to R ₈ are each independently a hydrogen atom, a methyl group, or a methoxy group. A dye-based polarizing film comprising a polarizing film base material containing the azo compound or its salt according to any one of claims 1 to 4. A dye-based polarizing film comprising a polarizing film base material containing the azo compound or its salt according to any one of claims 1 to 4, and one or more organic dyes other than these. According to claim 5,
A dye-based polarizing film in which the polarizing film base material is a film made of polyvinyl alcohol resin or a derivative thereof. A dye-based polarizing plate that can be obtained by bonding a transparent protective layer to at least one side of the dye-based polarizing film according to claim 5. A polarizing plate for a liquid crystal display using the dye-based polarizing film according to claim 5. A neutral gray polarizing plate for automotive use, using the dye-based polarizing film according to claim 5. A liquid crystal display device using the dye-based polarizing plate according to claim 8. delete delete delete delete delete delete