WO2007023733A1

WO2007023733A1 - Azo compound and polarizing film containing the compound

Info

Publication number: WO2007023733A1
Application number: PCT/JP2006/316194
Authority: WO
Inventors: Toru Ashida
Original assignee: Sumitomo Chemical Company, Limited
Priority date: 2005-08-22
Filing date: 2006-08-11
Publication date: 2007-03-01
Also published as: TW200718755A

Abstract

An azo compound represented by the following formula (I) or a salt thereof; a polarizing film which comprises a polarizing film base containing the azo compound or salt; and a liquid-crystal display employing the polarizing film. (The symbols in the formula are the same as defined in the description.)

Description

LIGHT COMPOSITION AND POLARIZING FILM CONTAINING THE COMPOUND TECHNICAL FIELD

The present invention relates to an azo compound. Background art

Polarizing films used in flat panel display devices (FPD) such as in-car navigation systems and liquid crystal projectors (LCDs) and projection televisions have high degree of polarization. Therefore, light resistance is required such that the transmittance does not decrease even when light is irradiated for a long time.

JP-A-2001-240762 (page 7, formula (lb)) discloses a dye-based polarizing film using an azo compound represented by the following formula or a salt thereof as a dichroic dye. However, with the recent increase in the use of LCD and FPD, there has been a demand for further improvements in the light resistance of polarizing films.

Disclosure of the invention

An object of the present invention is to provide an azo compound having a polarizing film having high polarization performance and further improved light resistance.

That is, the present invention provides the following [1] to [12].

[1] An azo compound represented by the formula (I) or a salt thereof.

(In the formula, A is a phenyl group having 1 to 2 at least one water-soluble group selected from the group consisting of a sulfo group and a carboxyl group, or a naphthyl group having 1 to 3 such water-soluble groups. R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ may be the same or different, and are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or 1 to 4 represents an alkoxy group, X represents —N═N— or —NHCO—, and Y ¹ and Y ² may be the same or different, and each represents a strong lpoxyl group, a sulfo group and a hydroxyl group. Represents a hydrocarbon group or a hydrogen atom having at least one functional group selected from the group consisting of a group, at least one of Y ¹ and Y ² is the hydrocarbon group, and Z is a strong lpoxyl group or a sulfo group Represents)

[2] The azo compound according to [1], wherein A is a monosulfophenyl group or a disulfonaphthyl group.

[3] The azo compound according to [1] or [2], wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are a hydrogen atom, a methyl group or a methoxy group. [4] The azo compound according to any one of [1] to [3], wherein either ^one of Y ¹ and Y ² is a hydrogen atom.

[5] A polarizing film comprising the polarizing film substrate containing the azo compound according to any one of [1:] to [4].

[6]. A polarizing film base material containing the azo compound according to any one of [1] to [4] and a dye having a maximum absorption wavelength in the range of 500 to 5700 nm. Polarizing film

[7] The polarizing film according to [6], wherein the dye having a maximum absorption wavelength in the range of 50 to 570 nm is a compound represented by the following formula (V).

(In the formula, D represents a phenyl group having at least 1 or 2 water-soluble groups selected from the group consisting of a sulfo group and a strong lpoxyl group, or a naphthyl group having 1 to 3 water-soluble groups. The phenyl group or naphthyl group of D may have 1 to 2 alkyl groups having 1 to 4 carbon atoms and / or 1 to 2 alkoxy groups having 1 to 4 carbon atoms, R ⁷ , R ⁸ , R ⁹ and R ^{1 ()} may be the same or different from each other, and each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms; NH—, — N = N— or one NHCO—, F represents a phenyl group, F phenyl group is a hydroxy group, an amino group, an alkyl group having 1 to 4 carbon atoms, a carbon number of 1 1 to 2 groups selected from the group consisting of -4 alkoxy groups and sulfo groups may be bonded, and n represents 0 or 1.)

[8] The polarizing film according to [7], wherein R ⁷ , RR ⁹ and R ^{1 () in the} compound (V) are a hydrogen atom, a methyl group, or a methoxy group.

[9] The polarizing film according to [7] or [8], wherein F in the compound (V) is a phenol group having a hydroxyl group or an amino group.

[10] The polarizing film according to any one of [7] to [9], wherein D is a monosulfophenyl group or a disulfonaphthyl group.

[11] The polarizing film according to any one of [7] to [10], wherein the polarizing film substrate is polypinyl alcohol.

[123. A liquid crystal display device comprising the polarizing film according to any one of [5] to [11]. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail.

A in the formula (I) is a phenyl group having 1 to 2 at least one water-soluble group selected from the group consisting of a sulfo group and a strong lpoxyl group, or a naphthyl group having 1 to 3 such water-soluble groups. Represents. That is, A is a phenyl group to which 1 to 2 sulfo groups and Z or carboxy groups are bonded, or a naphthyl group to which 1 to 3 sulfo groups and / or carboxy groups are bonded.

Examples of the phenyl group include monosulfophenyl groups such as 2-sulfophenyl, 3-sulfophenyl and 4-sulfophenyl, and 2-carboxyphenyl. , Mono-carbonoxy phenyl groups such as 3-force lpoxyphenyl, 4-carboxyphenyl, disulfophenyl groups such as 2,4-disulfophenyl, 2,5-disulfophenyl, 3,5-dicarboxenyl, 2- For example, strong lpoxy 4-sulfophenyl, 2-strong lpoxy 5-sulfophenyl group, and the like. Of these, a monosulfophenyl group is preferred because it is easily available. Examples of the naphthyl group include 5-sulfo-2-naphthyl, 6-sulfo-2-naphthyl, 7-sulfo-2-naphthyl, 8-sulfo-2-naphthyl, 4-sulfo1-1mononaphthyl, 5-sulfo-1 —Naphtyl, 6-sulfo-1-1 mononaphthyl, 7-sulfo 1-naphthyl and other monosulfonaphthyl groups, 6,8-disulfo-2-naphthyl, 4,8-disulfo-2-naphthyl, 5,7-disulfo 2- Disulfonaphthyl groups such as naphthyl, 3,6-disulfo-2-naphthyl, 3,6-disulfo-1 mononaphthyl, 4,6-disulfo-1 mononaphthyl, 3,6,8-trisulfo-2-naphthyl, 4, Examples include 6,8-trisulfo-2-naphthyl group. Among them, a disulfonaphthyl group is preferable because it is easily available, and a disulfo-2-naphthyl group is particularly preferable. R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ in formula (I) may be the same as or different from each other, and may be a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or carbon. Represents an alkoxy group having a prime number of 1 to 4; The alkyl group and alkoxy group may be either linear or branched. Specific examples of the alkyl group include a methyl group, an ethyl group, and a propyl group. Specific examples of the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group.

R ′ to R ⁶ are particularly preferably a hydrogen atom, a methyl group, or a methoxy group from the viewpoint of the degree of polarization. X in the formula (I) represents —N = N— or —NHCO—. Z represents a strong lupoxyl group or a sulfo group. Y ¹ and Y ² may be the same or different, and a hydrocarbon group to which at least one functional group selected from the group consisting of a strong lpoxyl group, a sulfo group and a hydroxyl group is bonded, or Represents a hydrogen atom, and at least one of Y ¹ and Y ² is the hydrocarbon group.

One NY'Y ² , for example, one NHCH ₂ COOH, one NHC ₂ H ₄ CO '

-NHC 3 H ₆ COOH, -NHC ₄ H ₈ CO 0 H, 1 NHC ₂ H ₄ OH, -NHC ₂ H ₄ S 0 ₃ H, 1 NHCH (CH ₃ ) C 0 OH,

-NH (COOH) CH ₂ OH, -NHCH (COOH) CH (CH ₃ ) ₂ , -NHCH (COOH) CH ₂ CH (CH ₃ ) ₂ , -NH (COOH) CH ₂ COOH,

-NH (COOH) C 2 H ₄ COOH, NH (COOH) CH (OH) CH CH _{3 and the} like. The azo compound (I) or a salt thereof can be produced, for example, by the method described below.

That is, first, the following formula (II 1 υ

(Wherein γ represents a halogen atom such as a chlorine atom or a bromine atom, and ζ represents the same meaning as described above.) In an aqueous solvent, an aromatic nitro compound represented by the following formula (II-2) Amine compounds represented by

(Wherein Υ ¹ and Υ ² represent the same meaning as described above), and the following formula (II-3)

(In the formula, Υ ¹ , Υ ² , and Ζ represent the same meaning as described above.)

An intermediate represented by is obtained. Next, the intermediate obtained in (II-3) above is subjected to reduction of the nitro group in an aqueous solvent to obtain the following formula (11_4)

Is obtained. Next, the aromatic amine compound obtained in the above (II-14) is reacted with chlorocarbonate fuel in an aqueous solvent to obtain the following formula (III)

(In the formula, Y ¹ , Y ² , and ζ have the same meaning as described above.)

A force rubamate compound represented by is obtained. This force rubamate compound is then combined with the formula (IV)

(In the formula, A, X, R ¹ R ² , R ³ , R ⁴ , R ⁵ and R ⁶ represent the same meaning as described above, and an azo intermediate compound represented by The azo compound (I) can be obtained by reacting at ° C. Here, the aqueous solvent is an organic compound that can be mixed with water at an arbitrary ratio, or a mixture of the organic compound and water. Examples of organic compounds that can be mixed with water in any proportion include usually alcohols with 1 to 3 carbon atoms such as methanol, ethanol, propanol, etc. Examples of the salt include compounds of the formulas (1-1) to (1-10)

The sulfo group and the force lpoxyl group contained in the azo compound (I) may exist as anions together with cations such as alkali metal ions such as lithium ion, sodium ion and potassium ion, and ammonium ion, and ethanolamine. It may be present as a sulfonic acid group or a carboxyl group together with an organic amine such as alkylamine. When the azo compound (I) is contained in the polarizing film substrate, it is used in the form of an anion with sodium ions. Preferably, the polarizing film of the present invention contains the azo compound in a polarizing film substrate. The polarizing film contains another organic dye in addition to the azo compound. As a result, the hue can be corrected and the polarization performance can be improved. The organic dye used in this case may be any dye having high dichroism, but it should be a polarizing film suitable for liquid crystal projector applications by selecting a dye that is particularly excellent in light resistance. Can do.

In particular, when a dye having a maximum absorption wavelength in the range of 500 to 570 nm is used, the hue can be corrected and the polarization performance can be improved. Examples of the dye having a maximum absorption wavelength in the range of 500 to 570 nm include compounds represented by the following formula (V).

Here, D in the formula (V) represents a phenyl group having 1 to 2 sulfo groups and Z or a strong lpoxyl group, or a naphthyl group having 1 to 3 sulfo groups. One or two alkyl groups having 1 to 4 carbon atoms and / or alkoxy groups having 1 to 4 carbon atoms may be bonded to the phenyl group or naphthyl group of D.

Examples of the phenyl group of D include monosulfophenyl groups such as 2-sulfophenyl, 3-sulfophenyl, and 4-sulfophenyl; 2-carboxyphenyl, 3-stroxyphenyl, 4-carboxyphenyl, and the like. 2,4-disulfophenyl, 2,5-disulfophenyl groups such as disulfophenyl; 3,5-dicarboxenyl; 2-force l-poxy-4-sulfurphenyl, 2--r-oxyloxy-5— Carpoxysulfophenyl groups such as sulfophenyl; alkylsulfophenyl groups such as 2-methyl-4-sulfophenyl, 3-methyl-4-sulfophenyl, 2-methyl-4 monosulfophenyl, 2,5-dimethyl-4 monosulfophenyl; 3 Such as methyl-4-carboxyphenyl, 2,5-dimethyl-1,4-carboxyphenyl Kilcarpoxyphenyl groups; 2-methoxy-4-sulfophenyl, 3-methoxy-4-sulfophenyl, 2,5-dimethoxy-1-sulfophenyl and other alkoxysulfophenyl groups; 2-methoxy-4-carboxenyl Alkoxycarbonyl groups such as 3-methoxy-4-force l-oxyphenyl, 2,5-dimethoxy-4-l-oxyloxyphenyl, and the like.

As the phenyl group, a monosulfophenyl group is preferable because it is easily available. Examples of the naphthyl group of D include, for example, 5-sulfo-2-naphthyl, 6-sulfo-2-naphthyl, 7-sulfo-2-naphthyl, and 8-sulfo-2-naphthyl. 4-sulfo-1 mononaphthyl, 5-sulfo-1-naphthyl, 6-sulfo-1-naphthyl, 7-sulfo-1-naphthyl and other monosulfonaphthyl groups; 6, 8 monodisulfo-2-naphthyl, 4, 8 —Disulfo-2-naphthyl, 5,7-disulfo 2-naphthyl, 3,6-disulfo-2-naphthyl, 3,6-disulfo-1-1 naphthyl, 4,6-disulfo- 1_naphthyl, etc. Groups; trisulfonaphthyl groups such as 3, 6, 8-trisulfo-2-naphthyl, 4, 6, 8_trisulfo-2-naphthyl, and the like;

As the naphthyl group, a disulfonaphthyl group is preferable because it is easily available, and a disulfo-2-naphthyl group is particularly preferable. R ⁷ , R ⁸ , R ⁹ and R ^{1 Q} in the formula (V) may be the same as or different from each other, and are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or 1 to 4 carbon atoms. Represents an alkoxy group. The alkyl group and alkoxy group may be linear or branched. Specific examples of the alkyl group include a methyl group, an ethyl group, and a propyl group. Specific examples of the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group.

R ⁷ to R ^{1 D} are particularly preferably a hydrogen atom, a methyl group or a methoxy group from the viewpoint of the degree of polarization. E represents —NH—, 1 N═N— or —NHCO—.

F represents a phenyl group, and the phenyl group of F is a group selected from the group consisting of a hydroxyl group, an amino group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a sulfo group. 1 or 2 may be bonded. Here, examples of the alkyl group and the alkoxy group include groups exemplified as R ^{7 to} R ^{1 ()} . As F, a phenyl group, a 4-aminophenyl group, and a hydroxyphenyl group are preferable because of easy production. .

n represents 0 or 1, and when n is 0, it is preferable because production is easy. Examples of the compound of formula (V) include formulas (V-1) to (V-7).

The sulfo group and force lupoxyl group contained in the compound (V) may exist as anions together with cations such as alkali metal ions such as lithium ion, sodium ion and potassium ion, and ammonium ion, and ethanol. Amine with organic amines such as alkylamine, It may be present as a phonic acid group or a force loxyl group. When compound (V) is contained in the polarizing film substrate, it is preferably used in the form of an anion together with sodium ions. The compound represented by the formula (V) can be produced by a method according to the azo compound (I).

Specifically, after reacting an azo compound represented by the following formula with sodium nitrite at 0 to 40 ° C. in an acidic aqueous solvent,

(In the formula, n, D and have the same meaning as described above.) By reacting a compound represented by the following formula in an aqueous solvent at 0 to 40 ° C. and pH 6 to 11, the compound (V) can be obtained.

(In the formula, E and F have the same meaning as described above.) The polarizing film of the present invention has a maximum absorption wavelength of 500 to 570 nm, such as the azo compound (I), preferably the compound of the formula (V). It can be produced by adding a dichroic dye containing another organic dye, if necessary, to the polarizing film substrate in the form of a polymer film by a known method. '

Examples of the polarizing film substrate used in the polarizing film of the present invention include those made of polyvinyl alcohol resin, poly (vinyl acetate) resin, ethylene Z vinyl acetate (EVA) resin, nylon resin, polyester resin and the like. . The polypinyl alcohol-based resin mentioned here includes polyvinyl alcohol itself, which is a partially saponified product of poly (vinyl acetate) or other copolymerizable monomers such as saponified EVA resin and other copolymerizable monomers. For example, olefins such as ethylene and propylene; unsaturated carboxylic acids such as crotonic acid, acrylic acid, methacrylic acid and maleic acid; unsaturated sulfonic acids; And polyvinyl formal and polyvinyl acetal in which polypinyl alcohol is modified with aldehyde.

As a polarizing film substrate, a polyvinyl alcohol-based film, particularly a polypinyl alcohol film, is preferably used from the viewpoint of the adsorptivity and orientation of the dye. As a method of incorporating a dichroic dye into the polarizing film substrate, Usually polymer film Is used. For example, staining can be performed as follows. First, a dye bath is prepared by dissolving dichroic dye in water. The dye concentration in the dye bath is not particularly limited, but is usually selected from the range of 0.001 to 10% by weight. If necessary, a dyeing assistant may be used. For example, it is preferable to use 1 to 10% by weight of sodium sulfate in a dyeing bath. Dye by immersing the polymer film in the dye bath prepared in this way. The dyeing temperature is preferably 40 to 80 ° C. The orientation of the dichroic dye is performed by stretching a polymer film. As a stretching method, for example, any known method such as a wet method or a dry method may be employed. The polymer film may be stretched before dyeing or after dyeing. The polymer film containing the dichroic dye and oriented is subjected to post-treatment such as boric acid treatment by a known method, if necessary. Such post-processing is performed for the purpose of improving the light transmittance, polarization degree, and durability of the polarizing film. The boric acid treatment conditions vary depending on the type of polymer film used and the type of dye used, but in general, the boric acid concentration of the boric acid aqueous solution is 1 to 15% by weight, preferably 5 to 10% by weight. The treatment is usually carried out in a temperature range of 30 to 80 ° C, preferably 50 to 80 ° C. Further, if necessary, the fixing treatment may be performed together with an aqueous solution containing a cationic polymer compound. The polarizing film thus obtained can be made into a polarizing plate by bonding a protective film excellent in optical transparency and mechanical strength on one or both surfaces. The material for forming the protective film may be those conventionally used. For example, in addition to a cellulose acetate film and an acrylic film, fluorine such as a tetrafluoroethylene / hexafluoropropylene copolymer may be used. Resin film, polyester film, polyolefin film, polyamide film, etc. are used. The polarizing film containing the azo compound of the present invention has a high degree of polarization, little deterioration even when irradiated for a long time, and is excellent in light resistance. The polarizing film containing the polyazo compound of the present invention or a salt thereof exhibits a high degree of polarization comparable to that of an iodine-based polarizing film, and further exhibits durability and light resistance against long-term exposure. Due to its excellent characteristics, the polarizing film of the present invention can be suitably used for liquid crystal display devices (LCD) such as force navigation and liquid crystal projectors, and flat panel display devices (FPD) such as projection televisions. Example

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, it cannot be overemphasized that this invention is not what is limited by these Examples. In the examples, “%” and “parts” are by weight unless otherwise specified. Example 1

Formula (1 1 1)

After adding 23.8 parts of the aromatic nitro compound represented by the following formula to 100 parts of water, add 5 parts of sodium hydroxide, then add 178 parts of / 3-alanine, and incubate at 90 for 5 hours. After confirming the disappearance of the aromatic nitro compound represented by 1-11), the mixture was cooled and the analyzed crystals were filtered to obtain an intermediate represented by the formula (1-2).

After that, the total amount of the intermediate intermediate body ((11 __ 22)) obtained in the above-mentioned above was replaced with the total amount of iron powder-reduction source in water. The intermediate intermediate body represented by the formula ((11-33)) was obtained. .

Next, 13 parts of the intermediate represented by the formula (11-3) was dissolved in 100 parts of water, and then adjusted to pH 7-8 with a 15% aqueous sodium carbonate solution at a temperature of 20-25 ° C. Then, 8 parts of black carbon dioxide was added dropwise over 30 minutes. After completion of the dropwise addition, the mixture was stirred for 1 hour at the same temperature and pH, and the precipitated crystals were filtered to obtain an intermediate represented by the formula (1-4).

S0 ₃ H

-OCO-NH -NHC ₂ HACOOH (1-4) The total amount of the intermediate (1-4) obtained above and the formula (2) (2)

Add 7 parts of the disazo intermediate compound represented by the following formula to a mixture of 100 parts of water and 100 parts of N-methylpyrrolidone, and adjust the pH to 8-9 with 15% aqueous sodium carbonate solution at a temperature of 40-45 ° C. The mixture was stirred for 3 hours. After removing insolubles by filtration, 300 parts of ethanol was added to the filtrate to precipitate crystals. After the precipitated crystals were filtered, the obtained cake was dissolved again in a mixed solution of 220 parts of water and 80 parts of N-methylpyrrolidone. 30 parts of sodium chloride was added to this liquid, and the precipitated crystals were filtered to obtain a salt of the disazo compound represented by (1-1), which showed λ max 406 nm in an aqueous medium.

(Production example of polarizing film)

7 5 rn thick polyvinyl alcohol film [Kuraray Vinylon # 7 500 , Kuraray Co., Ltd.] was stretched 5 times along a longitudinal axis to obtain a polarizing film substrate. While maintaining this polyvinyl alcohol film in a tensioned state, 0.0 25% of the salt of the disazo compound represented by the formula (1-1) obtained in Example 1 was used, and 2. It was immersed in a 70 ° C. aqueous solution having a concentration of 0%. Next, it is immersed in 7.5% boric acid solution at 78 ° C for 5 minutes, then taken out, washed with 20 ° C water for 20 seconds, and dried at 50 ° C to obtain a polarizing film. Got. The obtained polarizing film had a λ max (wavelength at which the transmittance in the direction of stretching of the film was minimized) of 44 Onm.

When the obtained polarizing film was irradiated with a high-pressure mercury lamp with an illuminance of 520 mW / cm ² (red light) for 48 hours under the condition of 100, the value of ΔΑ (%) was 89 (%) Light resistance to long-term exposure at high temperatures was also excellent. ΔΑ (%) is the value of absorbance at 0 hour as A (0) and the absorbance value after 48 hours as A (48).

ΔΑ (%) = (A (48) Z A (0)) X100

Is defined. The larger the ΔΑ value, the better the light resistance. Example 2

Prepared in the same manner as in Example 1, with a concentration of 0.08% for the azo compound (1-1) and 0.005% for the compound (V-4), and 2.0% for mirabilite as a dyeing assistant. Soaked in an aqueous solution. Next, after immersing it in 7.5% boric acid aqueous solution at 78 ° C for 5 minutes, it is taken out, washed with 20 ° C water for 20 seconds, and dried at 50 ° C to obtain a polarizing film. The Amax of the obtained polarizing film was 44 Onm.

When the obtained polarizing film was irradiated with a high-pressure mercury lamp with an illuminance of 520 mW / cm ² (red light) for 48 hours under the condition of 100 ° C, the value of ΔΑ (%) was 86 (%) Excellent light resistance under high temperature and long exposure. Example 3

Prepared in the same manner as in Example 1 at a concentration of 0.08% for the azo compound (1-1) and 0.005% for the compound (V-2), and 2.0% for mirabilite as a staining aid. Soaked in an aqueous solution. Next, after immersing it in a 7.5% boric acid aqueous solution at 78 ° C for 5 minutes, it is taken out, washed with 20 ° C water for 20 seconds, and dried at 50 ° C. Obtained . Amax of the obtained polarizing film was 44 Onm.

When the obtained polarizing film was irradiated with a high-pressure mercury lamp with an illuminance of 520 mW / cm ² (red light) for 48 hours under the condition of 100, the value of ΔΑ (%) was 84 (%) Light resistance to long-term exposure at high temperatures was also excellent. Comparative Example 1

A polarizing film is obtained in the same manner as in Example 2, using a compound represented by the formula (lb) on page 7, Patent Document 1 instead of a polarizing film dye containing an azo compound (1-1). It was. Λ max of the obtained polarizing film was 440 nm. When the value of light resistance ΔΑ was determined in the same manner as in Example 1, the value of ΔΑ (%) was only 76 (%), and the light resistance was inferior to the polarizing film of the present invention. Industrial applicability

Since the polarizing film of the present invention is excellent in light resistance in addition to high polarization performance, it is suitably used in liquid crystal display devices such as carna pigeons, liquid crystal projectors, and projection televisions.

Claims

The scope of the claims

(In the formula, A is a phenyl group having 1 to 2 at least one water-soluble group selected from the group consisting of a sulfo group and a strong loxyl group, or a naphthyl having 1 to 3 such water-soluble groups. R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ may be the same or different, and are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or 1 carbon atom. Represents an alkoxy group of ˜4, X represents one N═N— or one NHCO—, Y ¹ and Y ² may be the same or different, and each represents a strong lpoxyl group, a sulfo group, and Represents a hydrocarbon group or a hydrogen atom having at least one functional group selected from the group consisting of a hydroxyl group, at least one of Y ¹ and Y ² is the hydrocarbon group, and z is a strong lpoxyl group or a sulfo group. Represents a group)

2. The azo compound according to claim 1, wherein A is a monosulfophenyl group or a disulfonaphthyl group.

3. The azo compound according to claim 1 or 2, wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are a hydrogen atom, a methyl group, or a methoxy group.

4. The azo compound according to any one of claims 1 to 3, wherein any ^one of Y ¹ and Y ² is a hydrogen atom.

5. A polarizing film comprising the polarizing film substrate containing the azo compound according to any one of claims 1 to 4.

6. A polarizing film comprising the polarizing film substrate containing the azo compound according to any one of claims 1 to 4 and a dye having a maximum absorption wavelength in the range of 500 to 570 nm.

7. The polarizing film according to claim 6, wherein the dye having a maximum absorption wavelength in the range of 500 to 570 nm is a compound represented by the following formula (V).

(In the formula, D has a phenyl group having 1 to 2 at least one water-soluble group or 1 to 3 water-soluble groups selected from the group consisting of a sulfo group and a force lpoxyl group. The phenyl group or naphthyl group of D may have 1 to 2 alkyl groups having 1 to 4 carbon atoms and / or 1 to 2 alkoxy groups having 1 to 4 carbon atoms, R ⁷ , R ⁸ , R ⁹ and R ^{1 ()} may be the same as or different from each other, and each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; Represents one NH—, _N = N— or one NHCQ—, F represents a phenyl group, the phenyl group of F is a hydroxy group, an amino group, an alkyl group having 1 to 4 carbon atoms, or a carbon number One to two groups selected from the group consisting of 1-4 alkoxy groups and sulfo groups may be bonded, and n represents 0 or 1. )

8. The polarizing film according to claim 7, wherein R ⁷ , R ⁸ , R ⁹ and R ^{1 (1} is a hydrogen atom, a methyl group, or a methoxy group in the compound (V).

9. The polarizing film according to claim 7 or 8, wherein F in the compound (V) is a phenyl group having a hydroxyl group or an amino group.

10. The polarizing film according to any one of claims 7 to 9, wherein D is a monosulfophenyl group or a disulfonaphthyl group.

1 1. The polarizing film according to any one of claims 7 to 10, wherein the polarizing film substrate is polyvinyl alcohol.

12. A liquid crystal display device comprising the polarizing film according to any one of claims 5 to 11.