JP2006182846A - Azo compound or its salt and polarizing film containing the compound or its salt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing film while having durability under a high temperature and a high humidity condition and a high light fastness against a long time exposure, which are general characteristics of a dye-based polarizing film, also having a high polarization performance equal to that of an iodine-based film, and also a polarizing material of a dyestuff suitable for the polarizing film. <P>SOLUTION: This azo compound expressed by formula (I) [wherein, A is phenyl having 1-2 sulfonyl and/or carboxyl or naphthyl having 1-3 sulfonyl; R<SP>1</SP>to R<SP>6</SP>are each the same or different and are each H, a 1-4C alkyl or 1-4C alkoxy; X is N=N or NHCO; Y is H, a 1-4C alkyl, 1-4C alkoxy, amino, hydroxy, carboxyl or sulfonyl; and Z is carboxyl or sulfonyl] or its salt, and the polarizing film containing the compound or its salt are provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dye-based polarizing film used for a liquid crystal display device (LCD) such as a liquid crystal projector and a flat panel display device (FPD) such as a projection television.

Liquid crystal display devices (LCD) such as liquid crystal projectors, and flat panel display devices (FPD) such as projection televisions have recently required not only high light resistance but also high degree of polarization so that they can be used outdoors. It has been. A polarizing plate is used in the apparatus, and the polarizing plate is produced by adding iodine or a dichroic dye as a polarizing material to a polarizing film substrate such as a stretched and oriented film of polyvinyl alcohol or a derivative thereof. And a polarizing film in which polyene is produced and oriented by dehydrochlorination of a polyvinyl chloride film or dehydration of a polyvinyl alcohol film, and the like are used.
And in patent document 1, the dye-type polarizing film which uses a dichroic dye as a polarizing material has a comparatively high degree of polarization, and also the durability in high temperature and high humidity conditions, and the light resistance with respect to long-time exposure. It is disclosed that it is excellent. However, in general, dye-based polarizing films have higher durability against heat and water than iodine-based polarizing films, but their polarization performance tends to be inferior, and have a polarization performance that is comparable to iodine-based polarizing films. There is a need for a polarizing film.

JP 2001-240762 A (page 7, formula (Ib))

  The present invention is a general characteristic of a dye-based polarizing film, having a high polarization performance comparable to that of an iodine-based film while having durability under high temperature and high humidity conditions and high light resistance against long-term exposure. And a polarizing material of a dye suitable for the polarizing film.

（式中、Ａは、スルホ及び／若しくはカルボキシルを１〜２個有するフェニル、又は１〜３個のスルホを有するナフチルを表す。Ｒ¹ 、Ｒ² 、Ｒ³ 、Ｒ⁴ 、Ｒ⁵ 及びＲ⁶ は、互いに同一又は相異なり、水素原子、炭素数１〜４のアルキル又は炭素数１〜４のアルコキシを表す。Ｘは、−Ｎ＝Ｎ−又は−ＮＨＣＯ−を表し、Ｙは、水素原子、炭素数１〜４のアルキル、炭素数１〜４のアルコキシ、アミノ基、水酸基、カルボキシル又はスルホを表し、Ｚは、カルボキシル又はスルホを表す。） The present invention is an azo compound represented by the formula (I) or a salt thereof, and a polarizing film having the compound or a salt thereof.

(In the formula, A represents phenyl having 1 to 2 sulfos and / or carboxyls, or naphthyl having 1 to 3 sulfos. R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ^6. Are the same as or different from each other and each represents a hydrogen atom, alkyl having 1 to 4 carbon atoms or alkoxy having 1 to 4 carbon atoms, X represents —N═N— or —NHCO—, Y represents a hydrogen atom, (C1-C4 alkyl, C1-C4 alkoxy, an amino group, a hydroxyl group, carboxyl, or sulfo are represented, and Z represents carboxyl or sulfo.)

  The polarizing film containing the compound of the present invention or a salt thereof has a particularly high degree of polarization among the same type of dye-based polarizing film, and has a high degree of polarization comparable to that of iodine. The polarizing film of the present invention is excellent in durability and light resistance against long-time exposure.

Hereinafter, the present invention will be described in detail.
A in Formula (I) is phenyl having 1 to 2 sulfos and / or carboxyls, or naphthyl having 1 to 3 sulfos.
Examples of phenyl include 2-, 3- or 4-sulfophenyl, 2-, 3- or 4-carboxyphenyl, 2,4- or 2,5-disulfophenyl, 3,5-dicarboxyphenyl, and , 2-carboxy-4- or -5-sulfophenyl, and the like. Among them, monosulfophenyl is preferable because it is easily available.
Examples of naphthyl include 5-, 6-, 7- or 8-sulfo-2-naphthyl, 4-, 5-, 6- or 7-sulfo-1-naphthyl, 6,8-, 4,8. -, 5,7- or 3,6-disulfo-2-naphthyl, 3,6- or 4,6-disulfo-1-naphthyl and 3,6,8- or 4,6,8-trisulfo-2 -Naphthyl and the like can be mentioned. Among them, disulfonaphthyl is preferable because it is easily available, and disulfo-2-naphthyl is particularly preferable.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are the same or different from each other, and represent a hydrogen atom, alkyl having 1 to 4 carbon atoms or alkoxy having 1 to 4 carbon atoms. The alkyl and alkoxy may be linear or branched. Specific examples of alkyl include methyl, ethyl and propyl, and specific examples of alkoxy include methoxy, ethoxy and propoxy.
R ^{1 to} R ⁶ are particularly preferably a hydrogen atom, methyl or methoxy from the viewpoint of the degree of polarization.

  X in the formula (I) represents -N = N- or -NHCO-, and Y represents a hydrogen atom, alkyl having 1 to 4 carbon atoms, alkoxy having 1 to 4 carbon atoms, amino group, hydroxyl group, carboxyl or sulfo. Z represents carboxyl or sulfo.

（式中、Ｙ、Ｚは前記と同じ意味を表す。）
で示される芳香族アミン化合物を、水性溶媒中、クロロ炭酸フェニルと反応させて、 Examples of the method for producing the azo compound represented by the formula (I) or a salt thereof include the following methods. First, formula (II)

(In the formula, Y and Z have the same meaning as described above.)
Is reacted with phenyl chlorocarbonate in an aqueous solvent,

（式中、Ｙ、Ｚは前記と同じ意味を表す。）
で示されるカルバメート化合物を得る。 (III)

(In the formula, Y and Z have the same meaning as described above.)
Is obtained.

（式中、Ａ、Ｘ、Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴、Ｒ⁵及びＲ⁶は、前記と同じ意味を表す。）
で示されるアゾ中間化合物とを、水性溶媒中、２０〜６０℃で反応させることにより、アゾ化合物（I）を得ることができる。 This carbamate 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.)
The azo compound (I) can be obtained by reacting with an azo intermediate compound represented by the formula (2) in an aqueous solvent at 20 to 60 ° C.

Examples of the salt of the azo compound (I) include compounds of the formulas (I-1) to (I-12).

  When the azo compound (I) is present in the form of a salt, the salt includes alkali metal salts such as lithium salt, sodium salt and potassium salt, ammonium salts, and organic materials such as ethanolamine salts and alkylamine salts. Examples include amine salts. When the azo compound (I) is contained in the polarizing film substrate, it is preferably used in the form of a sodium salt.

The polarizing film of the present invention comprises the azo compound or a salt thereof in a polarizing film substrate.
In addition to the azo compound or a salt thereof, the polarizing film may contain 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, but a polarizing film suitable for liquid crystal projector applications can be obtained by selecting a dye that is particularly excellent in light resistance. .

Examples of the dye having a maximum absorption wavelength in the range of 500 to 570 nm include azo compounds represented by the following formula (V) or salts thereof.

Here, D in the formula (V) represents phenyl having 1 to 2 sulfos and / or carboxyls, or naphthyl having 1 to 3 sulfos. The phenyl or naphthyl of D may be bonded with 1 to 2 alkyls having 1 to 4 carbon atoms and / or alkoxy having 1 to 4 carbon atoms.
Examples of phenyl of D 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, 2- or 3-methyl-4-sulfophenyl, 2- or 3-methyl-4-carboxyphenyl, 2,5-dimethyl-4-sulfophenyl, 2, 5-dimethyl-4-carboxyphenyl, 2- or 3-methoxy-4-sulfophenyl, 2- or 3-methoxy-4-carboxyphenyl, 2,5-dimethoxy-4-sulfophenyl, and 2,5-dimethoxy-4- Carboxyphenyl etc. are mentioned.
Among them, monosulfophenyl is preferable because it is easily available.
Examples of the naphthyl of D include, for example, 5-, 6-, 7- or 8-sulfo-2-naphthyl, 4-, 5-, 6- or 7-sulfo-1-naphthyl, 6,8-, 4 , 8-, 5,7- or 3,6-disulfo-2-naphthyl, 3,6- or 4,6-disulfo-1-naphthyl and 3,6,8- or 4,6,8-trisulfo -2-naphthyl and the like.
As naphthyl, disulfonaphthyl is preferable because it is easily available, and disulfo-2-naphthyl is particularly preferable.

R < ⁷ >, R <^8> , R < ⁹ > and R < ¹⁰ > in the formula (V) are the same or different from each other, and represent a hydrogen atom, alkyl having 1 to 4 carbon atoms or alkoxy having 1 to 4 carbon atoms. The alkyl and alkoxy may be linear or branched. Specific examples of alkyl include methyl, ethyl and propyl, and specific examples of alkoxy include methoxy, ethoxy and propoxy.
R ^{7 to} R ¹⁰ are particularly preferably a hydrogen atom, methyl or methoxy from the viewpoint of the degree of polarization.

E represents -NH-, -N = N- or -NHCO-.
F represents phenyl, and 1 to 2 groups selected from the group consisting of hydroxy, amino, alkyl having 1 to 4 carbons, alkoxy having 1 to 4 carbons and sulfo are bonded to phenyl of F. Also good. Here, examples of the alkyl and alkoxy include groups exemplified as R ^{7 to} R ¹⁰ . As F, phenyl, 4-aminophenyl and hydroxyphenyl are preferable because of easy production.
n represents 0 or 1, and 0 is particularly preferable because it is easy to produce.

Examples of the compound of formula (V) include formulas (V-1) to (V-7).

  When the compound of the formula (V) is present in the form of a salt, the salt includes alkali metal salts such as lithium salt, sodium salt and potassium salt, ammonium salt, and ethanolamine salt and alkylamine salt. Examples thereof include organic amine salts. When the compound of formula (V) is contained in the polarizing film substrate, it is preferably used in the form of a sodium salt.

  The compound represented by the formula (V) can be produced by a method according to the azo compound (I).

The polarizing film of the present invention contains a dye having a maximum absorption wavelength in the range of 500 to 570 nm, such as azo compound (I) or a salt thereof, preferably a compound of formula (V), and if necessary, Furthermore, it can be produced by adding a dichroic dye containing another organic dye to a polarizing film substrate in the form of a polymer film by a known method.
As the polarizing film substrate used in the polarizing film of the present invention, for example, a material 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 here includes polyvinyl alcohol itself, which is a part of polyvinyl acetate or a completely saponified product, as well as other copolymerizable monomers such as saponified EVA resin, for example, Saponified copolymers of olefins such as ethylene and propylene, unsaturated carboxylic acids such as crotonic acid, acrylic acid, methacrylic acid and maleic acid, unsaturated sulfonic acids and vinyl ethers, and also polyvinyl alcohol Also included are polyvinyl formal and polyvinyl acetal modified with aldehyde.
As the polarizing film substrate, a polyvinyl alcohol film, particularly a polyvinyl alcohol film, is preferably used from the viewpoint of the adsorptivity and orientation of the dye.

  As a method for incorporating a dichroic dye into the polarizing film substrate, a method of dyeing a 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. Further, if necessary, a dyeing assistant may be used. For example, it is preferable to use 1 to 10% by weight of sodium sulfate in the dyeing bath. Dyeing is performed by immersing the polymer film in the dye bath thus prepared. 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, 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 conditions for boric acid treatment vary depending on the type of polymer film used and the type of dye used, but generally the boric acid concentration in the boric acid aqueous solution is in the range of 1 to 15% by weight, preferably in the range of 5 to 10% by weight. And the treatment is 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 thereof. 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, a fluororesin film such as a tetrafluoroethylene / hexafluoropropylene copolymer Polyester film, polyolefin film, polyamide film and the like are used.

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-time exposure.
The polarizing film of the present invention can be suitably used for a large amount of liquid crystal display device such as a car navigation system, a liquid crystal projector, and a projection television because of its excellent characteristics.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples. In the examples, “%” and “parts” are by weight and parts by weight unless otherwise specified.

(Example: Production Example of Azo Compound (I))
After 8 parts of sodium metanylate was dissolved in 100 parts of water, 8 parts of phenyl chlorocarbonate were added dropwise over 30 minutes while adjusting the pH to 7-8 with a 15% aqueous sodium carbonate solution at a temperature of 20-25 ° C. After completion of the dropwise addition, the mixture was stirred at the same temperature and the same pH for 1 hour, and then the precipitated crystals were filtered to obtain an intermediate represented by the following formula (1).

Subsequently, the total amount of the intermediate (1) obtained and the formula (2)

7 parts of a disazo intermediate compound represented by formula (1) is added to a mixed solution of 100 parts of water and 100 parts of N-methylpyrrolidone, and stirred for 3 hours at a temperature of 40 to 45 ° C. while adjusting the pH to 8 to 9 with a 15% aqueous sodium carbonate solution. did. After removing insolubles by filtration, 300 parts of ethanol was added to the filtrate to precipitate crystals. After filtering the precipitated crystals, 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 solution, and the precipitated crystals were filtered to obtain a salt of the disazo compound represented by (I-1), which showed λmax 404 nm in an aqueous medium.

(Production example of polarizing film)
A polyvinyl alcohol film [Kuraray Vinylon # 7500, Kuraray Co., Ltd.] having a thickness of 75 μm was stretched 5 times along a longitudinal axis to obtain a polarizing film substrate. While maintaining this polyvinyl alcohol film in a tensioned state, 0.025% of the salt of the disazo compound represented by the formula (I-1) obtained in Example 1 and 2.0% of mirabilite as a dyeing assistant It was immersed in the 70 degreeC aqueous solution made into the density | concentration. Next, the film was immersed in a 7.5% boric acid aqueous 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. Λmax of the obtained polarizing film was 440 nm. As a result of measuring the degree of polarization of this polarizing film at 440 nm, the degree of polarization at a single transmittance of 43% was 99.25%, indicating a high degree of polarization. It also showed long-term durability even under high temperature and high humidity conditions, and excellent light resistance against long-term exposure.

(Comparative example)
Instead of the azo compound (I-1), a polarizing film was obtained in the same manner as in Example, using the compound represented by the formula (1b) on page 7 of Patent Document 1. Λmax of the obtained polarizing film was 440 nm. As a result of measuring the degree of polarization of this polarizing film at 440 nm, the degree of polarization at a single transmittance of 43% was only 98.75%.

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

Claims (12)

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

(In the formula, A represents phenyl having 1 to 2 sulfos and / or carboxyls, or naphthyl having 1 to 3 sulfos. R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ^6. Are the same or different and each represents a hydrogen atom, alkyl having 1 to 4 carbon atoms or alkoxy having 1 to 4 carbon atoms, X represents —N═N— or —NHCO—, Y represents a hydrogen atom, carbon (C 1 -C 4 alkyl, C 1 -C 4 alkoxy, amino group, hydroxyl group, carboxyl or sulfo are represented, and Z represents carboxyl or sulfo.)   The azo compound or a salt thereof according to claim 1, wherein A is monosulfophenyl or disulfonaphthyl. The azo compound or a salt thereof according to claim 1 or 2, wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are the same or different from each other and are a hydrogen atom, methyl or methoxy.   The azo compound or salt thereof according to any one of claims 1 to 3, wherein Y is a hydrogen atom.   The polarizing film formed by containing the azo compound in any one of Claims 1-4, or its salt in a polarizing film base material.   A polarizing film comprising a polarizing film substrate containing a dye having a maximum absorption wavelength in the range of 500 to 570 nm in the azo compound according to any one of claims 1 to 5 or a salt thereof. The polarizing film according to claim 6, wherein the dye having a maximum absorption wavelength in the range of 500 to 570 nm is an azo compound represented by the following formula (V) or a salt thereof.

(In the formula, D represents phenyl having 1 to 2 sulfos and / or carboxyls, or naphthyl having 1 to 3 sulfos. In the phenyl or naphthyl of D, the alkyl having 1 to 4 carbon atoms and / or Alternatively, one or two alkoxy groups having 1 to 4 carbon atoms may be bonded to each other, and R ⁷ , R ⁸ , R ^9, and R ¹⁰ may be the same or different from each other, and may be a hydrogen atom, C represents an alkoxy having 1 to 4 carbon atoms, E represents —NH—, —N═N— or —NHCO—, F represents phenyl, F phenyl represents hydroxy, amino, and carbon atoms 1 to 4 1 to 2 groups selected from the group consisting of alkyl, alkoxy having 1 to 4 carbon atoms and sulfo may be bonded. N represents 0 or 1.) The polarizing film according to claim 7, wherein R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are the same or different from each other and are a hydrogen atom, methyl or methoxy.   The polarizing film according to claim 7 or 8, wherein F is phenyl to which hydroxy or amino may be bonded.   The polarizing film according to any one of claims 7 to 9, wherein D is monosulfophenyl or disulfonaphthyl.   The polarizing film substrate according to any one of claims 5 to 10, wherein the polarizing film substrate is polyvinyl alcohol. The liquid crystal display device which has a polarizing film in any one of Claims 5-11.