JPH09302249A - Azo compound and dye-based polarizing film containing the same - Google Patents

Abstract

(57) Abstract: An azo compound useful as a dye, particularly a dye for a polarizing film, and a dye-based polarizing film containing the compound and having excellent polarization performance and durability. SOLUTION: General formula (I) [In the formula, X is substituted with one or more sulfo or carboxy and may be further substituted with phenyl, or is substituted with one or more sulfo and is further substituted with another substituent. Naphthyl which may be R ₁ and R ₂
Represents hydrogen, methyl, etc., R ₃ represents hydrogen, amino, etc., R ₄ represents hydrogen, amino, etc., Y represents hydrogen, sulfo, etc. And a dye-based polarizing film containing the azo compound in a polarizing film substrate.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dye, particularly an azo compound useful as a dye for a polarizing film, and a dye-based polarizing film containing the azo compound.

[0002]

2. Description of the Related Art A polarizing film is made of a stretched and oriented film of polyvinyl alcohol or a derivative thereof, or a polyene-based film in which polyene is produced and oriented by dehydrochlorination of a polyvinyl chloride film or dehydration of a polyvinyl alcohol-based film. It is manufactured by adding iodine or a dichroic dye as a polarizing element to a polarizing film substrate. Among these, the iodine-based polarizing film has excellent initial polarization performance, but has poor durability against heat and water, and therefore has a problem that its performance deteriorates in a high temperature and high humidity state. In order to improve durability against heat and durability against water, a method of treating with an aqueous solution containing formalin or boric acid or a method of using a polymer film having low moisture permeability as a protective film has been considered. Not enough. On the other hand, as a dye-based polarizing film using a dichroic dye, the following formula

[0003]

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The production of a polarizing film using a water-soluble disazo dye represented by, for example, JP-A-59-1452.
No. 55 is described.

[0005]

However, the dye-based polarizing film containing the water-soluble dye is not always satisfactory from the viewpoint of polarization performance and durability.

[0006]

Means for Solving the Problems The present inventors provide a polarizing film having excellent polarization performance and durability under high temperature and high humidity conditions, especially when used for a dye-based polarizing film. As a result of intensive studies to provide a compound having excellent dyeability during production, the present invention has been completed by finding that an azo compound having a specific structure is effective. That is, the present invention, when expressed in the form of the free acid, has the general formula (I)

[0007]

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[In the formula, X is substituted with one or more sulfo groups or carboxy groups, and may be further substituted with a phenyl group, or is substituted with one or more sulfo groups, and Represents a naphthyl group optionally substituted with a substituent, R ₁ and R ₂ are the same or different and represent a hydrogen atom, a methyl group or a methoxy group, and R ₃ represents a hydrogen atom, an amino group or a sulfo group. , R ₄ represents a hydrogen atom, an amino group or an acetylamino group, Y is a hydrogen atom, a sulfo group, or the following formula (a) —NH—A (a) (wherein A is substituted with an amino group or a hydroxy group). Optionally a benzoyl group, a methyl group, an ethyl group, an acetyl group or a phenyl group), or a group represented by the following formula (b) -N = N-B (b) (wherein B is substituted Optionally substituted phenyl group or optionally substituted phenyl group It represents a group represented by represents a methyl group.). ] The azo compound represented by, a dye-based polarizing film containing the azo compound in a polarizing film substrate, and a dye-based polarizing film containing the azo compound and other organic dyes in a polarizing film substrate It is provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the general formula (I), X is substituted with one or more sulfo groups or carboxy groups,
A phenyl group which may be substituted with another substituent,
Alternatively, it is a naphthyl group which may be substituted with one or a plurality of sulfo groups and which may be further substituted with another substituent, wherein the phenyl group and the naphthyl group may have a plurality of different substituents. Good. Examples of the substituted phenyl group represented by X include the following formula (c)

[0010]

[Chemical 6]

(In the formula, one of R ₅ and R ₆ is a sulfo group or a carboxy group, and the other is a hydrogen atom, a hydroxy group, an alkyl group having 4 or less carbon atoms, an alkoxy group having 4 or less carbon atoms, a sulfo group or A substituted phenyl group represented by), which represents a carboxy group, is preferred. Among the substituted phenyl groups represented by the formula (c), a phenyl group substituted with one sulfo group or carboxy group is particularly preferable. Similarly, as the substituted naphthyl group represented by X, for example, the following formula (d)

[0012]

[Chemical 7]

(In the formula, R ₇ , R ₈ and R ₉ are the same or different and each represent a hydrogen atom, a hydroxy group or a sulfo group, and at least one of R ₇ , R ₈ and R ₉ is a sulfo group. A substituted naphthyl group represented by Among the substituted naphthyl groups represented by the formula (d), 1
Particularly preferred are naphthyl groups substituted with ~ 2 sulfo groups.

R ₁ and R ₂ are the same or different and each represent a hydrogen atom, a methyl group or a methoxy group, and preferred R
₁ and R ₂ are hydrogen atoms.

As Y, a group represented by the above formula (a) or (b) is preferable.

As the group represented by the formula (b), in particular, the following formula (e) -N = NB '(e) (wherein B'is an unsubstituted phenyl group or an alkyl group having 4 or less carbon atoms). Group, alkoxy group having 4 or less carbon atoms, hydroxy group, nitro group, chlorine atom, carboxyl group, amino group,
It represents a phenyl group substituted with a substituent selected from the group consisting of a sulfo group and a substituted amino group. Or a group represented by the following formula (f) -N = N-B "(f) (wherein B" is substituted with at least one sulfo group,
Further, it represents a naphthyl group which may be substituted with a substituent selected from the group consisting of an amino group, a substituted amino group and a hydroxy group. The group shown by these is preferable. Where B '
When is a phenyl group substituted with a substituted amino group, preferred substituents of the substituted amino group are methyl group, ethyl group,
Examples thereof include a hydroxyethyl group, a cyanoethyl group, an acetyl group, a sulfomethyl group and a carbamoyl group. or,
In the case where B ″ is a naphthyl group substituted with a substituted amino group, a preferable substituent of the substituted amino group includes a methyl group, an ethyl group or an acetyl group. As a preferable substituent of the substituted phenyl group represented by B ′ Is methyl, ethyl,
Examples include methoxy, ethoxy, amino, acetylamino, hydroxy, nitro, chlorine, carboxy and sulfo.

The azo compound represented by the general formula (I) can be produced, for example, by the method (i) or (ii) described below. That is, (i) general formula (II)

[0018]

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The compound represented by the formula (wherein R ₁ and R ₂ have the above-mentioned meanings) is converted into an acid chloride by a known method to give a compound represented by the general formula (III):

[0020]

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A compound represented by the formula (wherein R ₁ and R ₂ have the above-mentioned meanings) is obtained. Then, the compound is reacted with a compound represented by the general formula (IV) X—NH ₂ (IV) (wherein X represents the above meaning), and then reduced by a known method to give a compound represented by the general formula ( V)

[0022]

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A compound represented by the formula (wherein R ₁ , R ₂ and X have the above-mentioned meanings) is obtained. Then, the compound is diazotized to obtain a diazotized product.

Further, the diazo compound is represented by the general formula (VI)

[0025]

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(Wherein R ₃ and R ₄ have the above-mentioned meanings and Y ′ represents a hydrogen atom, a sulfo group or a group represented by the formula (a)). , Y is a hydrogen atom, a sulfo group or a group represented by the formula (a) can be produced.

The azo compound (ii) in which Y is a group represented by the formula (b) can be produced by the following two methods. First, the formula (VII) obtained by reacting 3-amino-8-naphthol-6-sulfonic acid with p-toluenesulfonic acid chloride

[0028]

[Chemical 12]

The compound represented by the formula (9) is diazotized, and this diazotized compound is represented by the compound represented by the general formula (VIII) H-B (VIII) (wherein B represents the above-mentioned meaning) or ω-of the compound. Coupling reaction with methane sulfonate. Then, the coupling product is hydrolyzed to obtain the general formula (IX)

[0030]

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(Wherein R ₄ and B have the above-mentioned meanings,
R ₃ ^' represents a hydrogen atom or a sulfo group. ), A monoazo compound represented by the general formula (V)
The desired azo compound can be obtained by coupling the diazotized product of the reduction product of the compound represented by 4-amino-8-naphthol-6-sulfonic acid and p-
Formula (X) obtained by reacting toluenesulfonic acid chloride

[0032]

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(Wherein R ₄ has the above meaning) and a compound of the general formula (XI) NH ₂ -B (XI) (wherein B has the above meaning). The compound is reacted with a diazo compound to undergo a coupling reaction. Then, the coupling product is hydrolyzed to obtain the general formula (XII)

[0034]

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A monoazo compound represented by the formula (wherein B and R ₄ have the same meanings as described above) is further produced by the method (i) to give a reduction product of the compound represented by the general formula (V). The desired azo compound can be obtained by coupling with the diazo compound of.

Examples of the compound represented by the general formula (II) include 4-nitrobenzoic acid, 4-nitro-3-hydroxybenzoic acid, 4-nitro-3-methylbenzoic acid and 4-nitro-3-methoxy. Examples thereof include benzoic acid and 4-nitro-2,5-dimethylbenzoic acid.

Examples of the compound represented by the general formula (IV) include 1-aminobenzene-2-, 3- or 4-sulfonic acid, 1-aminobenzene-2,4-disulfonic acid, 1
-Aminobenzene-2,5-disulfonic acid, 1-amino-2-, 3- or 4-benzoic acid, 5-aminoisophthalic acid, 4-aminoisophthalic acid, 2-amino-4-sulfobenzoic acid, 2- Amino-5-sulfobenzoic acid, 4-aminosalicylic acid, 5-aminosalicylic acid, 1-aminobenzene-2-methyl-4-sulfonic acid, 1-aminobenzene-2-methoxy-4-sulfonic acid, 1-aminobenzene -2-Methoxy-5-sulfonic acid, 1-aminobenzene-4-methoxy-5-sulfonic acid, 1-aminobenzene-2-methoxy-5-methyl-4-sulfonic acid, 1-
Aminonaphthalene-4-, 5-, 6-, 7- or 8-sulfonic acid, 2-aminonaphthalene-1-, 8-, 7-,
6- or 5-sulfonic acid, 1-aminonaphthalene-4,
7-, 4,6-, 3,7-, 3,8- or 3,6-disulfonic acid, 2-aminonaphthalene-4,8-, 6,8
-, 3,6-, 1,5- or 5,7-disulfonic acid, 1
-Aminonaphthalene-3,6,8-trisulfonic acid, 2
-Aminonaphthalene-3,6,8- or 4,6,8-trisulfonic acid, 2-aminonaphthalene-5-hydroxy-7-sulfonic acid, 2-aminonaphthalene-8-hydroxy-6-sulfonic acid, etc. Can be mentioned.

Examples of the compound represented by the formula (VI) include 1-hydroxynaphthalene-6-amino-3-sulfonic acid and 1-hydroxynaphthalene-7-amino-3-.
Sulfonic acid, 1-hydroxynaphthalene-5-amino-
3-sulfonic acid, 1-hydroxynaphthalene-7-amino-3,6-disulfonic acid, 1-hydroxynaphthalene-6-amino-3,5-disulfonic acid, 1-hydroxynaphthalene-8-amino-3,5- Disulfonic acid, 1-
Hydroxynaphthalene-8-amino-3,6-disulfonic acid, 1-hydroxynaphthalene-8-acetylamino-3,5-disulfonic acid, 1-hydroxynaphthalene-
8-Acetylamino-3,6-disulfonic acid, 1-hydroxynaphthalene-6-methylamino-3-sulfonic acid, 1-hydroxynaphthalene-6-ethylamino-3
-Sulfonic acid, 1-hydroxynaphthalene-6-dimethylamino-3-sulfonic acid, 1-hydroxynaphthalene-6-diethylamino-3-sulfonic acid, 1-hydroxynaphthalene-6-acetylamino-3-sulfonic acid,
1-hydroxynaphthalene-6-phenylamino-3-
Sulfonic acid, 1-hydroxynaphthalene-6-benzoylamino-3-sulfonic acid, 1-hydroxynaphthalene-6- (4-, 3- or 2-hydroxybenzoyl) amino-3-sulfonic acid, 1-hydroxynaphthalene-6
-(4-, 3- or 2-aminobenzoyl) amino-3
-Sulfonic acid and the like.

Examples of the compound represented by the formula (VIII) include 1-aminobenzene, 1,3-diaminobenzene,
1,3-diamino-4-methylbenzene, 1-amino-
2- or 3-methylbenzene, 1-amino-2- or 3
-Ethylbenzene, 1-amino-2- or 3-methoxybenzene, 1-amino-2- or 3-ethoxybenzene, 1-amino-3-acetylaminobenzene, 1-amino-3-carbamoylaminobenzene, 1-amino −
2-methoxy-5-methylbenzene, 1-amino-2,
5-dimethoxybenzene, 1-amino-2,5-diethoxybenzene, 1-amino-3-methylsulfonylaminobenzene, 1-amino-2-methoxy-5-acetylaminobenzene, 1-hydroxybenzene, 1,3 -Dihydroxybenzene, 1,3,5-trihydroxybenzene, 1-hydroxy-2-, 3- or 4-methylbenzene, 2-hydroxybenzoic acid, 1-amino-2- or 3-hydroxybenzene, 1-diethylamino Examples include aniline and its derivatives such as -3-hydroxybenzene, phenol and its derivatives, aminophenol and its derivatives, and also the compounds exemplified by the formula (VI).

Examples of the compound represented by the formula (XI) include 1-aminobenzene, 1-amino-2-, 3- or 4-sulfamoylbenzene, 1-amino-2-, 3-
Or 4-chlorobenzene, 1-amino-2,5-dichlorobenzene, 1-amino-2-, 3- or 4-bromobenzene, 1-amino-2-, 3- or 4-methylbenzene, 1-amino- 2-, 3- or 4-ethylbenzene,
1-amino-2-, 3- or 4-methoxybenzene, 1
-Amino-2-, 3- or 4-ethoxybenzene, 1-
Amino-4-di (β-hydroxyethyl) aminobenzene, 1-amino-4-nitrobenzene, 1-amino-4
-Acetylaminobenzene, the compounds exemplified by the formula (IV), and the like.

The azo compound represented by the formula (I) thus obtained may be used in the form of free acid, but it is usually preferable to use it in the form of sodium salt, such as lithium salt, potassium salt and ammonium salt. It can also be used in the form of a salt, an ethanolamine salt, an alkylamine salt or the like. Also, the formula
The azo compound represented by (I) can be used in combination with other organic dyes to correct the hue and improve the polarization performance. The organic dye used in this case may be any dye as long as it has high dichroism, and examples thereof include the followings described in the color index. C-I Direct Yellow 12, C-I Direct Yellow 28, C-I Direct
Yellow 44, Sea Eye Direct Orange 26, Sea Eye Direct Orange 39, Sea Eye Direct Orange 107, Sea Eye Direct Red 2, Sea Eye Direct Red 31, Sea Eye Direct Red 79, Sea Eye Direct Red 81, and Sea Eye Direct Red 247

The dye-based polarizing film of the present invention comprises a dichroic dye comprising a compound represented by the formula (I) or further containing another organic dye, which is a polymer film as a polarizing film substrate. It can be manufactured by incorporating it in a known method. When another organic dye is used in addition to the azo compound represented by the formula (I), the respective compounding ratios thereof are not particularly limited, but generally, the formula (I) is used.
It is preferable to use other organic dyes in a total amount of 0.1 to 5 times by weight based on the weight of the azo compound represented by. As the polymer film, for example, polyvinyl alcohol or a derivative thereof, any of which is modified with an olefin such as ethylene or propylene, or an unsaturated carboxylic acid such as crotonic acid, acrylic acid, methacrylic acid, or maleic acid And EVA (ethylene / vinyl acetate) resin, saponified EVA resin, nylon resin, polyester resin and the like. Among them, a film made of polyvinyl alcohol or a derivative thereof is preferably used from the viewpoint of the dye adsorbability and orientation. In incorporating a dichroic dye into such a polymer film, a method of dyeing the polymer film is usually employed. Staining can be performed, for example, as follows. First, a dichroic dye is dissolved in water to prepare a dye bath. The dye concentration in the dye bath is not particularly limited, but is usually selected from the range of 0.0001 to 10% by weight.
If necessary, a dyeing aid may be used. For example, it is preferable to use 1 to 10% by weight of Glauber's salt. The polymer film is immersed in the dyeing bath prepared in this way to perform dyeing. The dyeing temperature is preferably 40 to 80 ° C. The dichroic dye is oriented by stretching the polymer film. As a stretching method, any known method such as a wet method and a dry method may be employed. The stretching of the polymer film may be performed before dyeing. The polymer film containing and orienting the dichroic dye is optionally subjected to post-treatment such as boric acid treatment by a known method. Such a post-treatment is performed for the purpose of improving the light transmittance, the degree of polarization, and the durability of the polarizing film. The conditions of the boric acid treatment differ depending on the type of polymer film used and the type of dye used, but generally the boric acid concentration of the aqueous boric acid solution is set to 1 to 15% by weight, preferably 5 to 10% by weight. , The treatment is 30 to 80 ° C., preferably 50 to 75 ° C.
The temperature range is as follows. Further, if necessary, the fix treatment may be performed together with an aqueous solution containing a cationic polymer compound.

The dye-based polarizing film thus obtained is
A polarizing plate can be obtained by laminating a protective film having excellent optical transparency and mechanical strength on one or both surfaces thereof. The material for forming the protective film may be a conventionally used material, for example, a cellulose acetate film or an acrylic film, or a fluorine film such as an ethylene tetrafluoride / propylene hexafluoride copolymer. Alternatively, a film-processed resin made of a polyester resin, a polyolefin resin, or a polyamide resin is used.

In this way, a polarizing film having high polarization performance and excellent durability against water and heat can be obtained. Further, by using the azo compound represented by the formula (I) in combination with other organic dyes, it is possible to obtain a neutral color polarizing film having excellent durability against water and heat.

[0045]

EFFECT OF THE INVENTION The azo compound of the present invention has a good affinity for a polarizing film substrate and is excellent in dyeability. Therefore, it is useful as a dye, especially as a dye for a polarizing film. And since the dye-based polarizing film containing this compound has high polarization performance and excellent durability, various liquid crystal displays,
Among them, it is suitable for outdoor applications that require high polarization performance and durability (particularly when mounted on automobiles), and display applications for industrial instruments used in various environments.

[0046]

The present invention will be described in more detail with reference to the following examples, which are illustrative only and do not limit the present invention in any way. The percentages and parts in the examples are by weight unless otherwise indicated.

Example 1 34.6 parts of sulfanilic acid were dispersed in 1000 parts of water,
A 28% aqueous sodium hydroxide solution is added to adjust the pH to 7 and dissolve. Then, 37.1 parts of 4-nitrobenzoyl chloride is added little by little, and a pH of about 7 is maintained by appropriately adding a 28% sodium hydroxide aqueous solution during this period. 1 more
Incubate for 2 hours. Next, sodium chloride is added for salting out, and the precipitated crystals are filtered.

30 parts of iron powder and 5 parts of ferrous sulfate (7 hydrate) were added to 1400 parts of water, dispersed and heated to 85 ° C.
Next, the crystals obtained above are added little by little and reacted at 85 ° C. for 7 hours. Then, after cooling to 60 ° C., a 28% aqueous sodium hydroxide solution is added to adjust the pH to 10, and the insoluble matter is removed by filtration. 35% hydrochloric acid was added to the obtained filtrate and p
H7 was added, sodium chloride was added for salting out, and the precipitated crystals were filtered to obtain an intermediate (1) having the following structure.

[0049]

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The above intermediate (1) 15.7 was added to 150 parts of water.
And 7 parts of a 28% aqueous sodium hydroxide solution were added and dissolved, and a 35% aqueous sodium nitrite solution 10.9 was added to the solution.
20 parts by weight, and then 26 parts of 35% hydrochloric acid to add 20 to 30 parts.
Diazotize at ℃. Excess sodium nitrite is eliminated by adding sulfamic acid to obtain a diazo solution. On the other hand, 1-
Hydroxynaphthalene-6-benzoylamino-3-sulfonic acid (17.2 parts) was added to water (200 parts), and the temperature was adjusted to 10 to 15 ° C.
Sodium carbonate is added to adjust the pH to 8.5, and while maintaining this pH with sodium carbonate, the diazo solution obtained above is injected and stirred to complete the coupling reaction. Salting out was performed with sodium chloride, and the precipitated crystals were filtered to obtain an azo compound having the following structure.

[0051]

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This compound has a λmax of 491 in an aqueous medium.
nm is shown.

Example 2 12.0 parts of 1-hydroxynaphthalene-5-amino-3-sulfonic acid was dispersed in 200 parts of water, 6 parts of caustic soda was added, and then 9.6 parts of tosyl chloride was added at 35-40 ° C. Stir for 1 hour to obtain a reaction solution. On the other hand, 7.5 parts of 4-acetylaminoaniline is dispersed in 100 parts of water. After adding 5.2 parts of 35% hydrochloric acid and then adding ice to bring the temperature of the contents to 5 ° C, 11 parts of 35% hydrochloric acid and 3.5 parts of sodium nitrite are added to diazotize. After removing excess sodium nitrite by adding sulfamic acid, the diazotized solution after removing excess sodium nitrite was injected into the previously obtained reaction solution at 10 to 15 ° C. After the injection, 100 parts of ethanol was added, and then 15% sodium carbonate solution was added to adjust the pH to 3, and the coupling reaction was completed by appropriately adding 15% sodium carbonate solution while maintaining this pH. Then, 16 parts of caustic soda was added, and the mixture was heated and stirred at 80 to 90 ° C. for hydrolysis. After cooling to room temperature, 35% hydrochloric acid was added to make it weakly alkaline, sodium chloride was added to salt out, and the precipitated crystals were filtered to obtain an intermediate compound (2) represented by the following structure.

[0054]

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26 parts of the above-mentioned intermediate compound (2) was added to 100 parts of water, and 28% caustic soda solution was further added to adjust the pH to 9 to obtain a monoazo solution. On the other hand, the intermediate (1) 1 obtained in Example 1
5.7 parts was added to 150 parts of water, 7 parts of 28% caustic soda was added and dissolved, and then 10.9 parts of 35% sodium nitrite was added, and then
Add 26 parts of 35% hydrochloric acid and diazotize at 20-30 ° C. Excess sodium nitrite was removed with sulfamic acid to obtain a diazo solution. This diazo solution was poured into the above monoazo solution at 10 to 15 ° C, and during this period, a coupling reaction was carried out while appropriately adding 28% caustic soda to maintain this pH. Then, sodium chloride was added for salting out, and the precipitated crystals were filtered to obtain an azo compound represented by the following structure.

[0056]

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This compound showed a λmax of 597 nm in an aqueous medium.

Example 3 27.5 parts of 4-aminobenzoic acid was dispersed in 1000 parts of water to give 28%.
The pH was adjusted to 9 by adding caustic soda. Then, 37.1 parts of 4-nitrobenzoyl chloride was added little by little, and 28% caustic soda was added appropriately during this period to maintain pH around 8. In addition, 12
After reacting for a period of time, salting out and then filtration were performed to obtain crystals.

30 parts of iron powder and 5 parts of ferrous sulfate (7 hydrate) were added to 1400 parts of water, dispersed and heated to 85 ° C.
Next, the crystals obtained above are added little by little and reacted at 85 ° C. for 7 hours. Then, after cooling to 60 ° C., a 28% aqueous sodium hydroxide solution is added to adjust the pH to 10, and the insoluble matter is removed by filtration. 35% hydrochloric acid was added to the obtained filtrate and p
H7 was added, sodium chloride was added for salting out, and the precipitated crystals were filtered to obtain an intermediate (3) having the following structure.

[0060]

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The intermediate (3) 13.9 was added to 150 parts of water.
And 7 parts of a 28% aqueous sodium hydroxide solution were added and dissolved, and a 35% aqueous sodium nitrite solution 10.9 was added to the solution.
20 parts by weight, and then 26 parts of 35% hydrochloric acid to add 20 to 30 parts.
Diazotize at ℃. Excess sodium nitrite is eliminated by adding sulfamic acid to obtain a diazo solution. On the other hand, 26 parts of the intermediate compound (2) obtained above is added to 100 parts of water, and a 28% aqueous sodium hydroxide solution is further added to adjust the pH to 9. The previously obtained diazo solution was injected into this at 10 to 15 ° C., 28% sodium hydroxide aqueous solution was appropriately added during this period, and the coupling reaction was carried out by stirring while maintaining this pH. Salting out was performed with sodium chloride, and the precipitated crystals were filtered to obtain an azo compound having the following structure.

[0062]

[Chemical 21]

This compound showed a λmax of 597 nm in an aqueous medium.

Example 4 12.0 parts of 1-hydroxynaphthalene-6-amino-3-sulfonic acid was dispersed in 150 parts of water, 6 parts of caustic soda was added, and then 9.6 parts of tosyl chloride was added thereto at 35-40 ° C. Stir for 1 hour. Next, after adding ice to 5 ° C., 21 parts of 35% hydrochloric acid and 3.5 parts of sodium nitrite are added to diazotize. Next, after adding 4.7 parts of phenol, caustic soda is added to adjust the pH to 9, and the mixture is stirred at 5 to 10 ° C to complete the coupling reaction. Next, add 3 parts of caustic soda, and add 3 parts at 80 ° C.
It was hydrolyzed by stirring for a time. After cooling to room temperature, add 35% hydrochloric acid to pH 7, add sodium chloride and salt out,
The precipitated crystals were filtered and the intermediate shown by the following structure (4)
I got

[0065]

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On the other hand, 15.7 parts of the intermediate (1) obtained in Example 1 was added to 150 parts of water, 7 parts of 28% caustic soda was added and dissolved, and then 10.9 parts of 35% sodium nitrite was added, followed by 35 parts. Add 26 parts of hydrochloric acid to diazotize at 20 to 30 ° C. Excess sodium nitrite was removed with sulfamic acid to obtain a diazo solution. 18.3 parts of the above intermediate (4) is added to 100 parts of water, and 28% caustic soda is further added to adjust the pH to 8. Add 10 parts of the above diazo solution.
Pour at ~ 15 ° C, while adding 28% caustic soda as needed.
The coupling reaction was carried out while maintaining the pH around 7. Then, sodium chloride was added for salting out, and the precipitated crystals were filtered to obtain an azo compound represented by the following structure.

[0067]

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Polyvinyl alcohol film having a thickness of 75 μm (Kuraray vinylon # 7500, Kuraray Co., Ltd.)
Was longitudinally uniaxially stretched 5 times to obtain a polarizing film substrate. While keeping this polyvinyl alcohol film in a tensioned state, it was immersed in a 65 ° C. aqueous solution in which the concentration of the azo compound obtained above was 0.025% and that of Glauber's salt, a dyeing aid, was 2.0%. Further, after immersing in a 65 ° C. aqueous solution having a boric acid concentration of 7.5% for 5 minutes, it was taken out, washed with water at 20 ° C. for 20 seconds, and dried at 50 ° C. to obtain a polarizing film. Λmax of the obtained polarizing film was 520 nm, and this polarizing film had a high degree of polarization, and exhibited durability for a long time even in a high temperature and high humidity condition.

Example 5 Instead of the azo compound used in Example 4, Examples 1 to 3 were used.
A polarizing film was obtained in the same manner as in Example 4 by using the azo compound obtained in the above. The λmax of the obtained polarizing film is shown in the table below.

[0070]

[Table 1]

Example 6 Instead of the azo compound used in Example 5, Examples 1 to 4 were used.
A polarizing film was obtained in the same manner as in Example 4 by using the azo compounds shown in the second column of the following table obtained in the same manner as in. The hues in the table are the hues of the polarizing film. Each of the obtained polarizing films was excellent in durability under the conditions of high temperature and high humidity.

[0072]

[Table 2]

Claims (9)

[Claims] 1. When represented in the form of a free acid, it has the general formula (I): [In the formula, X is a phenyl group which is substituted with one or more sulfo groups or carboxy groups, and may be further substituted with another substituent group, or is substituted with one or more sulfo groups, and another substituent group is further substituted. Represents a naphthyl group which may be substituted with, R ₁ and R ₂ are the same or different and represent a hydrogen atom, a methyl group or a methoxy group, R ₃ represents a hydrogen atom, an amino group or a sulfo group, and R ₄ Represents a hydrogen atom, an amino group or an acetylamino group, Y represents a hydrogen atom, a sulfo group, the following formula (a) -NH-A (a) (In the formula, A may be substituted with an amino group or a hydroxy group. A good benzoyl group, a methyl group, an ethyl group, an acetyl group or a phenyl group), or a group represented by the following formula (b) -N = N-B (b) (in the formula, B may be substituted) Represents a good phenyl group or an optionally substituted naphthyl group. . A group represented by). ] The azo compound shown by these. 2. X is the following formula (c): (In the formula, one of R ₅ and R ₆ is a sulfo group or a carboxy group, and the other is a hydrogen atom, a hydroxy group, an alkyl group having 4 or less carbon atoms, an alkoxy group having 4 or less carbon atoms, a sulfo group or a carboxy group. The azo compound according to claim 1, which is a substituted phenyl group represented by 3. X is the following formula (d): (Wherein, R _7, R ₈ and R ₉ are the same or different and each a hydrogen atom, represents a hydroxy group or a sulfo group, R _7,
At least one of R ₈ and R ₉ represents a sulfo group. The azo compound according to claim 1, which is a substituted naphthyl group represented by the formula (1). 4. Y is a compound represented by the following formula (e) -N = N-B '(e) (wherein B'is an unsubstituted phenyl group, an alkyl group having 4 or less carbon atoms, or an alkoxy group having 4 or less carbon atoms). Group, a hydroxy group, a nitro group, a chlorine atom, a carboxy group, an amino group, a sulfo group, and a substituted amino group, and a phenyl group substituted with a substituent selected from the group). The azo compound according to any one of to 3. 5. Y is represented by the following formula (f) -N = NB "(f) (wherein B" is substituted with at least one sulfo group,
Further, it represents a naphthyl group which may be substituted with a substituent selected from the group consisting of an amino group, a substituted amino group and a hydroxy group. ] The azo compound in any one of Claims 1-3 which is a group shown by these. 6. R ₁ and R ₂ are hydrogen atoms.
The azo compound according to any one of to 5. 7. A dye-based polarizing film, which comprises a polarizing film substrate containing the azo compound according to any one of claims 1 to 6. 8. A dye-based polarizing film comprising a polarizing film substrate containing at least one azo compound according to any one of claims 1 to 6 and at least one other organic dye. 9. The dye-based polarizing film according to claim 7, wherein the polarizing film substrate is a film made of polyvinyl alcohol or a derivative thereof.