JP2003064276A - Azo compound or its salt and dye-based polarizing film containing them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a salt of an azo compound useful as a dye in a dye-based polarizing film. SOLUTION: The salt or the like of the azo compound expressed by formula (1) is provided. (wherein A denotes naphthyl having 1-3 sulfo or phenyl which has 1-2 groups selected from sulfo and carboxyl and may have alkyl or alkoxy. R<1> -R<4> denotes hydrogen or lower alkyl; R<5> denotes hydrogen or sulfo; D denotes -NHCO-, -N=N- or -NH-; and E denotes phenyl which may have 1-3 groups selected from hydroxy, amino, nitro, sulfo, carboxyl, alkyl and alkoxy).

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A polarizing film is a stretched and oriented polyvinyl alcohol-based film, 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 including iodine or a dichroic dye as a polarizing element in a base material. 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 at high temperature and high humidity. In order to improve such durability, a method of treating with an aqueous solution containing formaldehyde or boric acid, a method of using a polymer film having a low water vapor transmission rate as a protective film, etc. have been considered, but they are still sufficient. Absent.

On the other hand, a dye-based polarizing film using a dichroic dye as a polarizing element is superior in durability against heat and water as compared with an iodine-based polarizing film, but generally tends to be inferior in initial polarizing performance, particularly in the initial stage. There is a demand for a dye for polarizing film, which has excellent polarization performance.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have found that the dyeing property during the production of a polarizing film is good, the polarizing performance is excellent, and the durability and light resistance under high temperature and high humidity conditions are excellent, and the polymer film is As a result of searching for a dye covering a region of 500 to 580 nm in a polarizing film for use in a liquid crystal projector or the like in which a dichroic dye is adsorbed and oriented, it was found that a specific azo compound or a salt thereof achieves the above object. Headline,
The present invention has been completed.

[0005]

That is, the present invention provides (a)
The following formula (I)

[0006]

[Chemical 2]

(In the formula, A represents naphthyl having 1 to 3 sulfo, or has 1 to 2 water-soluble groups selected from sulfo and carboxyl, and has lower alkyl or lower alkoxy. R ^{1 to} R ⁴ are the same or different and represent hydrogen or lower alkyl, R ⁵ represents hydrogen or sulfo, and D
Represents -NHCO-, -N = N- or -NH-,
E is 1 to 1 selected from hydroxy, amino, nitro, sulfo, carboxyl, lower alkyl and lower alkoxy.
Represents phenyl which may have 3 groups. ) Or an azo compound represented by the above), and (ii) above (ii)
The present invention provides a dye-based polarizing film comprising a polarizing film substrate containing the azo compound or salt thereof. Hereinafter, the present invention will be described in detail.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A in the above formula (I) is 1 to 3.
Is naphthyl having 1 sulfo, or phenyl having 1 to 2 water-soluble groups selected from sulfo and carboxyl and optionally having lower alkyl or lower alkoxy. As the lower alkyl and lower alkoxy, a linear or branched group having 1 to 4 carbon atoms is preferable. Specific examples of lower alkyl include methyl, ethyl and propyl. Specific examples of lower alkoxy include methoxy, ethoxy and propoxy. Examples of the phenyl represented by A above include 2-, 3- or 4-sulfophenyl, 2-, 3- or 4
-Carboxyphenyl, 2,4- or 2,5-disulfophenyl, 3,5-dicarboxyphenyl, 2-carboxy-4- or -5-sulfophenyl, and 2- or 3-methyl-4-sulfo Examples include phenyl and the like.

Examples of the naphthyl represented by A include 5-, 6-, 7- or 8-sulfo-2-naphthyl,
4-, 5-, 6- or 7-sulfo-1-naphthyl, 1,
5-, 6,8-, 4,8-, 5,7- or 3,6-disulfo-2-naphthyl, 3,6- or 4,6-disulfo-
1-naphthyl, 1,5,7-, 3,6,8- or 4,6,8-trisulfo-2-naphthyl and the like can be mentioned. As A, 4-sulfophenyl and 1,5
Disulfo-naphthyl such as-, 6,8-, 4,8-, 5,7- or 3,6-disulfo-2-naphthyl is preferred,
Especially, 4-sulfophenyl and disulfo-2-naphthyl are preferable.

R ^{1 to} R ⁴ are the same or different and are hydrogen or lower alkyl. Examples of the lower alkyl include the groups exemplified above as the substituent of phenyl represented by A. R ^{1 to} R ⁴ are the same or different and are preferably hydrogen or methyl. R ⁵ represents hydrogen or sulfo, with hydrogen being more preferred. D is -NHCO-, -N = N
Represents -or -NH-, but -NHCO- or -N = N-
Is preferred. E represents phenyl which may have 1 to 3 groups selected from hydroxy, amino, nitro, sulfo, carboxyl, lower alkyl and lower alkoxy, and the lower alkyl and the lower alkoxy are as follows. The groups exemplified as the substituent of the phenyl represented by A can be mentioned. As E, 4-hydroxyphenyl or 4-aminophenyl is preferable.

The azo compound (I) or its salt is, for example,
It can be manufactured by the method described below. That is, first, the following formula (II)

[0012]

[Chemical 3]

The amide compound represented by the formula (A, R ¹ and R ² have the above-mentioned meanings) is added to an acidic aqueous medium,
It is diazotized by reacting with sodium nitrite under the condition of 5 to 40 ° C. The obtained diazo compound is represented by the following formula (III)

[0014]

[Chemical 4]

An aniline compound represented by the formula (wherein R ³ and R ⁴ have the above-mentioned meanings) and 5 to 5 in an aqueous medium.
A monoazo compound is obtained by reacting under conditions of 40 ° C. and pH 6-11. The obtained monoazo compound is reacted with sodium nitrite in an acidic aqueous medium at a temperature of 5 to 40 ° C to diazotize. The obtained second diazo compound is represented by the following formula (IV)

[0016]

[Chemical 5]

By reacting a hydroxynaphthalene compound represented by the formula (wherein R ⁵ , D and E have the above-mentioned meanings) in an aqueous medium under the conditions of 5 to 40 ° C. and pH 6 to 11, The azo compound (I) can be obtained.

Examples of the azo compound represented by the formula (I) are:
For example,

[0019]

[Chemical 6]

[0020]

[Chemical 7]

[0021]

[Chemical 8]

[0022]

[Chemical 9]

And the like.

When the azo compound (I) is present in the form of a salt, the salt includes lithium salts, alkali metal salts such as sodium salts and potassium salts, ammonium salts, and ethanolamine salts and alkylamine salts. Such organic amine salts and the like can be mentioned. When the polarizing film substrate contains the azo compound (I), it is preferably used in the form of a sodium salt.

When the polarizing film base material contains the azo compound (I) or a salt thereof to form a polarizing film, the hue can be corrected and the polarizing performance can be improved by using it together with another organic dye. . The organic dye used in this case may be any dye as long as it has high dichroism, but by selecting a dye having particularly excellent light resistance, a polarizing film suitable for liquid crystal projector applications can be obtained. .

The organic dye used in combination with the azo compound (I) is a color index generic name (Color In
dex Generic Name), the following are illustrated.

[CI Direct Yellow 12] Sea I Direct Yellow 28 Sea I Direct Yellow 44 C-I Direct Orange 26 Sea I Direct Orange 39 C-I Direct Orange 107 Sea I Direct Red 2 C-I Direct Red 31 Sea I Direct Red 79 Sea I Direct Red 81 Sea I Direct Red 247

The dye-based polarizing film of the present invention comprises a dichroic dye comprising an azo compound (I) or a salt thereof, or a dichroic dye comprising an azo compound (I) or a salt thereof and another organic dye. It can be produced by incorporating the polymer film, which is the polarizing film substrate, by a known method. As the polymer film, for example, a film made of polyvinyl alcohol resin, polyvinyl acetate resin, ethylene / vinyl acetate (EVA) resin, nylon resin, polyester resin, or the like is used. The polyvinyl alcohol-based resin as used herein includes saponified E in addition to polyvinyl alcohol itself which is a partially or completely saponified product of polyvinyl acetate.
Vinyl acetate and other copolymerizable monomers such as VA resin, for example, olefins such as ethylene and propylene, unsaturated carboxylic acids such as crotonic acid, acrylic acid, methacrylic acid and maleic acid, Saturated sulfonic acids,
Also included are saponification products of copolymers with vinyl ethers and the like, and polyvinyl formal and polyvinyl acetal obtained by modifying polyvinyl alcohol with an aldehyde. As the polarizing film substrate, a polyvinyl alcohol-based film, particularly a polyvinyl alcohol film, is preferably used from the viewpoint of dye adsorption and orientation.

In order to incorporate a dichroic dye into such a polymer film, a method of dyeing the polymer film is usually adopted. Dyeing can be performed as follows, for example. 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 0.1 to 10% by weight of Glauber's salt in the dyeing bath. The polymer film is immersed in the dyeing bath thus prepared for dyeing. The dyeing temperature is preferably 40 to
It is 80 ° C. The orientation of the dichroic dye is performed by stretching the polymer film. Examples of the stretching method of the polymer film include known methods such as a wet method and a dry method. The stretching of the polymer film may be performed before dyeing or after dyeing.

The oriented polymer film containing a dichroic dye is subjected to post-treatment such as boric acid treatment by a known method, if necessary. Such post-treatment is carried out 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 boric acid aqueous solution is in the range of 1 to 15% by weight, preferably 5 to 10% by weight. The treatment is carried out in the temperature range of 30 to 80 ° C, preferably 50 to 80 ° C. Further, if necessary, a fixing treatment may be additionally performed with an aqueous solution containing a cationic polymer compound.

The dye-based polarizing film thus obtained is
A protective film having excellent optical transparency and mechanical strength can be attached to one surface or both surfaces of the same to form a polarizing plate. The material for forming the protective film may be one that has been conventionally used. For example, in addition to cellulose acetate film and acrylic film, fluororesin film such as tetrafluoroethylene / hexafluoropropylene copolymer. Polyester films, polyolefin films, polyamide films, etc. are used.

[0032]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" and "parts" in the examples represent% by weight and parts by weight.

Example 1 160 parts of sodium 4- (4-aminobenzoylamino) benzenesulfonate and 75 parts of sodium nitrite were added to 1 part of water.
In addition to 600 parts, 100 parts of 35% hydrochloric acid was added at room temperature and stirred for 2 hours to obtain a diazo compound a. Separately, 120 parts of N-sulfomethyl-2,5-xylidine and 140 parts of sodium bicarbonate were added to 500 parts of water and stirred at room temperature. The resulting solution was charged with the solution of diazo compound a over 1 hour, and the mixture was stirred for 1 hour to carry out the coupling reaction, and then the sulfomethyl group was hydrolyzed under the condition of being alkaline with sodium hydroxide to give a monoazo compound. The compound was obtained. 280 parts of this monoazo compound and 83 parts of sodium nitrite are added to 2800 parts of water.
220 parts of 35% hydrochloric acid was added at room temperature and stirred for 2 hours to obtain a reaction solution of diazo compound b. Separately, formula (5)

[0034]

[Chemical 10]

270 parts of the compound represented by and 150 parts of sodium bicarbonate were added to a mixed solution of 1400 parts of water and 1400 parts of N-methyl-2-pyrrolidinone and stirred at room temperature. The reaction liquid of the diazo compound b obtained above was added to this stirring mixture over 1 hour. After the addition was completed, a coupling reaction was further carried out for 1 hour to obtain a salt of the disazo compound represented by the formula (1). The λmax of this salt was 535 nm in an aqueous medium.

Example 2 In the same manner as in Example 1, a reaction solution of diazo compound b was obtained.
Next, instead of the compound (5), the following formula (6)

[0037]

[Chemical 11]

Example 1 except that the compound represented by
A stirred mixture of sodium bicarbonate, water and N-methyl-2-pyrrolidinone was obtained according to. A reaction solution of the diazo compound b obtained in the same manner as in Example 1 was added to this mixture, and after the addition was completed, a coupling reaction was further performed to obtain a salt of the trisazo compound represented by the above formula (2). . The λmax of this salt was 560 nm in an aqueous medium.

Example 3 A polyvinyl alcohol film [Kuraray Vinylon # 7500, Kuraray Products Co., Ltd.] having a thickness of 75 μm was vertically uniaxially set to 5
The film was stretched twice to obtain a polarizing film substrate. While keeping the polyvinyl alcohol film in a tensioned state, 0.025 of the salt of the disazo compound represented by the formula (1) obtained in Example 1 was used.
%, And Glauber's salt, a dyeing aid, at a concentration of 0.2% at 70 ° C.
It was immersed in an aqueous solution of. Next, after immersing in a 7.5% aqueous boric acid solution at 78 ° C. 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. Λ of this polarizing film
max (wavelength at which the transmittance in the stretching direction of the film is minimum) is 55
0 nm, this polarizing film has a high degree of polarization,
It showed long-term durability even in high humidity. It was also excellent in light resistance to long-term exposure.

Example 4 The same treatment as in Example 3 was carried out except that the salt (2) of the trisazo compound obtained in Example 2 was used in place of the salt (1) of the disazo compound obtained in Example 1, and polarized light was obtained. A film was obtained. Λmax of the obtained polarizing film was 550 nm. This polarizing film had a high degree of polarization and showed durability for a long time even in a high temperature and high humidity state. It was also excellent in light resistance to long-term exposure.

[0041]

EFFECT OF THE INVENTION The dye-based polarizing film containing the azo compound or salt thereof of the present invention exhibits high polarization performance and is excellent in durability and light resistance to long-term exposure. Suitable for body use.

Claims (6)

[Claims] 1. The following formula (I): (In the formula, A represents naphthyl having 1 to 3 sulfo, or 1 to 1 selected from sulfo and carboxyl.
It represents phenyl which has two water-soluble groups and may have lower alkyl or lower alkoxy. R ¹ ~ R
⁴ are the same or different and represent hydrogen or lower alkyl, R ⁵ represents hydrogen or sulfo, and D is —NHC.
Represents O-, -N = N- or -NH-, and E represents phenyl which may have 1 to 3 groups selected from hydroxy, amino, nitro, sulfo, carboxyl, lower alkyl and lower alkoxy. Represent ) The azo compound or its salt shown by these. 2. The azo compound according to claim 1, wherein A is 2-naphthyl having 2-3 sulfo, or phenyl having 1-2 water-soluble groups selected from sulfo and carboxyl. Its salt. 3. The azo compound or a salt thereof according to claim 1, wherein R ^{1 to} R ⁴ are the same or different and are hydrogen or methyl. 4. E is p-hydroxyphenyl or p
-Aminophenyl, the azo compound or a salt thereof according to claim 1. 5. A dye-based polarizing film comprising a polarizing film substrate containing the azo compound or salt thereof according to any one of claims 1 to 4. 6. The dye-based polarizing film according to claim 5, wherein the polarizing film substrate is a film made of a polyvinyl alcohol-based resin.