WO2013008735A1 - Polarizing element and polarizing plate - Google Patents

Abstract

[Problem] To provide a polarizing element exhibiting high polarization performance in relation to a light source having a maximum light emission intensity at a wavelength of 520-545 nm, and a polarizing plate. [Solution] A polarizing element is characterized by including a dichroic dye represented by formula (1) and formula (2), and comprising a stretched polyvinyl alcohol film. (In formula (1), n is an integer of 1-4.) (In compound (2), X is a phenyl group or a naphthyl group having at least one sulfo group, R1-R6 each independently represent a hydrogen atom, a lower alkyl group having 1-4 carbon atoms, an alkoxyl group having 1-4 carbon atoms, or an acetylamino group, Y represents a hydrogen atom or an amino group, and m represents 0 or 1.)

Description

Polarizing element and polarizing plate

The present invention relates to a polarizing element and a polarizing plate using the polarizing element.

A polarizing element is generally produced by adsorbing and orienting iodine or dichroic dye, which is a dichroic dye, on a polyvinyl alcohol resin film. A protective film made of triacetyl cellulose or the like is bonded to at least one surface of the polarizing element via an adhesive layer to form a polarizing plate, which is used for a liquid crystal display device or the like. A polarizing plate using iodine as a dichroic dye is called an iodine polarizing plate, while a polarizing plate using a dichroic dye is called a dye polarizing plate. Among these, the dye-based polarizing plate has a problem that the transmittance is lower than that of the polarizing plate having the same degree of polarization as that of the iodine-based polarizing plate, that is, the contrast is low. It is used in color liquid crystal projectors and the like.
In the case of a color liquid crystal projector, a polarizing plate is used for the liquid crystal image forming portion. However, light is greatly absorbed by the polarizing plate, and an image that is projected from several tens of inches to hundreds of tens of inches is reduced to 0.5. In order to collect light on a polarizing plate having a small area of ˜6 inches, deterioration due to light and the influence of heat upon irradiation with light are inevitable due to the size of the light density.

Patent No. 3769140 Japanese Patent No. 3585097 Japanese Patent No. 3591220 JP-A-64-72007 Japanese Patent No. 4162334 Japanese Patent No. 4662853 International Publication Number WO2007 / 138980 JP 2004-075719 A

Conventional light sources have used CCFLs or high-pressure mercury lamps, and Patent Document 1 describes a polarizing plate for a liquid crystal projector that uses a liquid crystal cell corresponding to blue in consideration of the light source. By selecting an appropriate dye, a technique for a polarizing plate having good polarization characteristics at a specific wavelength is disclosed. In recent years, new light sources have been developed along with the market trend. In recent years, light sources using light emitting diodes (hereinafter abbreviated as LEDs) as in Patent Document 2 and Patent Document 3, and Laser light sources as in Patent Document 4 have been developed. Has been reported, and polarizing plates corresponding to these new light sources have begun to be desired. In general, an LED that emits white light uses a general iodine-based polarizing plate. However, the light emission intensity of the LED has been remarkably improved, and light resistance and heat resistance have become issues as the light emission intensity increases. A light-resistant and high heat-resistant polarizing plate is being desired. Among them, the light resistance and heat resistance of the dye-based polarizing plate are higher than those of the iodine-based polarizing plate, and a dye-based polarizing plate corresponding to each light source is desired. However, the polarizing property is lower than that of iodine-based polarizing plates, and a dye-based polarizing plate having higher polarizing properties is desired.

Among them, LEDs that are becoming mainstream as new light sources and emitted light using Laser as a light source are different from the emission colors separated by a dichroic mirror using a conventional high-pressure mercury lamp. The light emission of a green light source using a conventional high-pressure mercury lamp as the light source has a wavelength with the highest emission intensity in the vicinity of 555 nm, but the green emission light source of LED or Laser has the highest emission intensity at 520 nm to 545 nm. Thus, in contrast to a new light source having a wavelength of the maximum light emission intensity different from that of the conventional light source, the polarizing plate corresponding to the conventional light source has a low degree of polarization in the band of the emitted light, and the actual display contrast is low.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have combined a specific compound as a specific dichroic dye, and a polarizing element adsorbed on a polyvinyl alcohol film has excellent polarization characteristics with respect to a new light source. The present invention has been completed. That is, the present invention
(1) A polarizing element comprising a film of a polyvinyl alcohol resin or a derivative thereof containing a dichroic dye represented by the following formula (1) and the following formula (2) or a salt thereof, and stretched:

(In formula (1), n is an integer of 1 to 4.)

(In Formula (2), X represents a phenyl group or a naphthyl group having at least one sulfo group, R _{1 to} R ₆ are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or 1 carbon atom. To an alkoxyl group or an acetylamino group which is 3 to 3, Y represents a hydrogen atom or an amino group, and m represents 0 or 1, respectively.
(2) The polarizing element according to the above (1), wherein Y in formula (2) is an amino group,
(3) The polarizing element according to (1) or (2), wherein when m = 0 in formula (2), X is a phenyl group having at least one sulfo group,
(4) The polarizing element according to (3), wherein X is a structure represented by the following formula (3):

(In formula (3), Z ₁ represents a sulfo group, a methoxy group or a carboxyl group, and Z ₂ represents a sulfo group.)
(5) When m = 1 in formula (2), X is a naphthyl group having at least two substituents, at least one of the substituents is a sulfo group, and the other substituents are hydroxy groups, Or the polarizing element according to the above (1) or (2), which is an alkoxy group having a sulfo group,
(6) When m = 1 in the formula (2), X is a phenyl group having at least two substituents, at least one of the substituents is a sulfo group, and the other substituents are hydrogen atoms, The polarizing element according to the above (1) or (2), which is a sulfo group, an alkyl group, an alkoxy group, an alkoxy group having a sulfo group, a carboxy group, a nitro group, an amino group, or an acetylamino group,
(7) In the dichroic dye of formula (1), any of the above (1) to (6), wherein the adsorption ratio of n = 2 with respect to the total adsorption amount of n = 1 to n = 4 is 55% or more The polarizing element according to item 1,
(8) A polarizing plate comprising a support film on at least one surface of the polarizing element according to any one of (1) to (6) above,
(9) A polarizing plate with an inorganic substrate, wherein the polarizing element according to any one of (1) to (7) above or the polarizing plate according to (8) above is laminated on an inorganic substrate,
(10) The present invention relates to a projector including the polarizing element or polarizing plate according to any one of (1) to (9).

The polarizing element of the present invention and the polarizing plate thereof have high polarization performance with respect to a light source having the highest light emission intensity at 520 nm to 545 nm.

Issuance intensity for each wavelength of the green light source of a Samsung projector (SP-F10M) with a 3-wavelength LED light source

Hereinafter, the present invention will be described in detail.
The polarizing element of the present invention is characterized by containing a dichroic dye which is a free acid represented by the following formulas (1) and (2) or a salt thereof, and a stretched polyvinyl alcohol resin or a derivative film thereof It consists of Hereinafter, unless otherwise specified, the free acid of formula (1), its salt or its copper compound is simplified with compound (1), and the free acid of formula (2), its salt is simplified with compound (2), respectively. Represent.

(In formula (1), n represents an integer of 1 to 4)

(In the formula (2), X represents a phenyl group having at least one sulfo group or a naphthyl group, and R _{1 to} R ₆ are each independently a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, carbon An alkoxyl group or an acetylamino group represented by formulas 1 to 4; Y represents a hydrogen atom or an amino group; and m represents 0 or 1, respectively.

The polyvinyl alcohol resin film used in the present invention will be described. The manufacturing method of the polyvinyl alcohol-type resin which comprises a polarizing element is not specifically limited, A well-known method may be sufficient. For example, the polyvinyl alcohol resin can be obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. The saponification degree of the polyvinyl alcohol-based resin is usually preferably from 85 to 100 mol%, more preferably 95 mol% or more. This polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol resin is usually preferably from 1,000 to 10,000, and more preferably from 1,500 to 5,000.
Examples of the derivative of the polyvinyl alcohol resin that can be used in the present invention include the resin subjected to the modification treatment.

Such a polyvinyl alcohol resin or a derivative thereof (hereinafter, both are collectively referred to as a polyvinyl alcohol resin) is used as a raw film. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. In this case, the polyvinyl alcohol resin can contain glycerin, ethylene glycol, propylene glycol, or low molecular weight polyethylene glycol as a plasticizer. The amount of plasticizer is preferably 5 to 20% by weight, more preferably 8 to 15% by weight. The thickness of the raw film made of polyvinyl alcohol resin is not particularly limited, but is preferably 5 to 150 μm, and more preferably 10 to 100 μm.

The polyvinyl alcohol film is first subjected to a swelling process. The swelling step is performed by immersing the polyvinyl alcohol film in a solution at 20 to 50 ° C. for 30 seconds to 10 minutes. The solution is preferably water. When the time for manufacturing the polarizing element is shortened, the swelling step can be omitted because the swelling occurs even during the dyeing process.

The dyeing process is performed after the swelling process. In this invention, the pigment | dye of a compound (1) and a compound (2) can be made to adsorb | suck to a polyvinyl alcohol film at a dyeing process. The dyeing process is not particularly limited as long as it is a method for adsorbing the pigment to the polyvinyl alcohol film. For example, the dyeing process is performed by immersing the polyvinyl alcohol film in a solution containing a dichroic dye. The solution temperature in this step is preferably 5 to 60 ° C, more preferably 20 to 50 ° C, and particularly preferably 35 to 50 ° C. The time for dipping in the solution can be adjusted moderately, but is preferably adjusted from 30 seconds to 20 minutes, more preferably from 1 to 10 minutes. The dyeing method is preferably immersed in the solution, but can also be performed by applying the solution to a polyvinyl alcohol film.

The solution containing the dichroic dye can contain sodium chloride, sodium sulfate, anhydrous sodium sulfate, sodium tripolyphosphate and the like as a dyeing assistant. Their content can be adjusted at any concentration depending on the time and temperature depending on the dyeability of the dye, but the respective content is preferably 0 to 5% by weight, more preferably 0.1 to 2% by weight.

The polarizing element of the present invention adsorbs the compound (1) and the compound (2) on the polyvinyl alcohol film. The compound (2) is represented by the formula (2), and when m = 0 in the formula (2), X is preferably a phenyl group having at least one sulfo group in order to exhibit good polarization characteristics. . The phenyl group having a sulfo group has good adsorption to PVA and becomes a polarizing dye for having a high degree of polarization in the polarizing element.

When m = 0, it is more preferable that X of the compound (2) has a structure represented by the following formula (3), and at least one of Z1 and Z2 is a sulfo group. A polarizing element having excellent polarization characteristics can be obtained. In order to obtain a better polarizing element, Z2 is a sulfo group, and Z1 is either a methoxy group or a carboxyl group, in order to have a high degree of polarization and high durability, More preferred.

In order to obtain a polarizing element having better polarization characteristics than the compound of m = 0 in formula (2), a tetrakisazo dye with m = 1 is preferable.

In the formula (2), when m = 1, X in the formula (2) is a structure represented by the formula (3), and in the formula (3), at least one of Z1 and Z2 is a sulfo group Thus, a polarizing element having better polarization characteristics can be obtained. In order to obtain a better polarizing element, it is preferable that Z2 is a sulfo group and Z1 is any one of a sulfo group, a methoxy group, and a carboxyl group.

In order to improve the polarization characteristics, Y in compound (2) is an amino group, so that a polarizing element having good polarization characteristics can be obtained by combining with the dye shown in compound (1). It reaches.

When X in the compound (2) is a phenyl group having at least one sulfo group, sulfoalkoxyanilic acids obtained by sulfoalkylating aromatic amines or phenols by the production method shown in Patent Document 8, pp35 Is diazotized and subjected to primary coupling with anilines of the following formula (A) to obtain a monoazoamino compound represented by the following formula (B).

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

In the compound (2), when X is a naphthyl group having at least one sulfo group, sulfoalkoxynaphthylamine obtained by sulfoalkylating naphthylamine sulfonic acid or aminonaphthol sulfonic acid by the production method shown in Patent Document 8, pp35 The sulfonic acids are diazotized and primary-coupled with the anilines of the formula (A) to obtain a monoazoamino compound represented by the following formula (B).

(In the formula, X, R ₁ and R ₂ represent the same meaning as in the above formula (2).)

Next, the monoazoamino compound (B) is diazotized and secondarily coupled with anilines of the following formula (C) to obtain a disazoamino compound represented by the following formula (D).

(In formula (C), R ₃ and R ₄ represent the same meaning as in formula (2) above.)

(In the formula (D), X, R ₁ , R ₂ , R ₃ and R ₄ represent the same meaning as in the above formula (2).)

In the case of producing a compound of m = 1 in the formula (2), the disazoamino compound represented by the formula (D) is diazotized and thirdarily coupled with anilines of the following formula (E), and the following formula (F) The trisazoamino compound shown is obtained.

(In the formula, R ₅ and R ₆ have the same meaning as in the above formula (2).)

(In the formula, X, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ represent the same meaning as in the above formula (2).)

In the formula (2), in the case of a compound of m = 0, the compound of formula (D), and in the case of a compound of m = 1, this trisazoamino compound is diazotized with the compound of formula (F). By coupling with naphthols represented by the formula (G), an azo compound of the formula (2) is obtained.

(In formula (G), Y represents the same meaning as in formula (2) above.)

In the above reaction, the diazotization step is performed by a conventional method of mixing a nitrite such as sodium nitrite in a mineral acid aqueous solution or suspension of diazo component such as hydrochloric acid or sulfuric acid, or a neutral or weak alkaline solution of diazo component. Nitrite is added to the aqueous solution and mixed with mineral acid. The diazotization temperature is suitably -10 to 40 ° C. The coupling step with anilines is carried out by mixing an acidic aqueous solution such as hydrochloric acid or acetic acid with each of the above diazo solutions, and at a temperature of −10 to 40 ° C. and acidic conditions of pH 2 to 7.

The monoazo compound, disazo compound, and trisazo compound obtained by the coupling can be taken out as they are or by acid precipitation or salting out and filtered, or the solution or suspension can be used for the next step. If the diazonium salt is insoluble and in suspension, it can be filtered and used as a press cake in the next coupling step.

In the anilines having substituents R ₁ to R ₆ used in primary, secondary, and tertiary couplings, phenols are disclosed in Patent Documents as a specific method for producing anilines having an alkoxy group having a sulfo group. 8, sulfoalkoxyanilines can be obtained by sulfoalkylation and reduction by the production method shown by pp35, and can be used in the coupling step.

The quaternary coupling reaction between the diazotized trisazoamino compound and the naphthols represented by the formula (G) is carried out under neutral to alkaline conditions at a temperature of −10 to 40 ° C. and a pH of 7 to 10. After completion of the reaction, it is precipitated by salting out and filtered out. If purification is required, salting out may be repeated or precipitated from water using an organic solvent. Examples of the organic solvent used for purification include water-soluble organic solvents such as alcohols such as methanol and ethanol, and ketones such as acetone.

The substituent of the aromatic amine represented by A, which is a starting material for synthesizing the water-soluble dye represented by the above formula (2), is a hydrogen atom, a sulfo group, a lower alkyl group, a lower alkoxy group, a sulfo group. A naphthotriazole group, a nitro group, an amino group, or an acetylamino group substituted by a lower alkoxy group having a carboxy group, a carboxy group, a sulfo group, etc., preferably a hydrogen atom, a sulfo group, a lower alkyl group, a lower alkoxy group More preferably, at least one of the substituents is a sulfo group, and the number of substituents is more preferably 2.
The lower alkoxy group having a sulfo group is preferably linear alkoxy, and the sulfo group is preferably substituted at the end of the alkoxy group. Here, the lower alkoxy group is preferably an alkoxyl group having 1 to 5 carbon atoms, and the lower alkoxy group having a sulfo group may be either a 3-sulfopropoxy group or a 4-sulfobutoxy group. preferable. When A is a phenyl group having a substituent, for example, 4-aminobenzenesulfonic acid, 3-aminobenzenesulfonic acid, 2-aminobenzenesulfonic acid, 4-aminobenzoic acid, 2-amino-5-methylbenzenesulfonic acid, 2-amino-5-methoxybenzenesulfonic acid, 4-amino-2-methylbenzenesulfonic acid, 3-amino-4-methoxybenzenesulfonic acid, 2-amino-4-sulfobenzoic acid, 2-amino-5-sulfo Benzoic acid, 5-aminoisophthalic acid, 2-amino-5-nitrobenzenesulfonic acid, 5-acetamido-2-aminobenzenesulfonic acid, 2-amino-5- (3-sulfopropoxy) benzenesulfonic acid, 4-amino Examples include benzene-1,3-disulfonic acid and 2-aminobenzene-1,4-disulfonic acid. Aminobenzenesulfonic acid, 2-amino-5-methoxy-benzenesulfonic acid, 4-amino-2-methyl-benzenesulfonic acid, 4-amino-1,3-disulfonic acid are particularly preferred. Further, it may have a naphthotriazole group as a substituent of the phenyl group, and may be 6,8-disulfonaphthotriazole group, 7,9-disulfonaphthotriazole group, 7-sulfonaphthotriazole group, 5-sulfonaphthotriazole group. In this case, it is particularly preferred to be in the p-position of the phenylazo group. Specific examples of the substituent of naphthylamine sulfonic acids include a hydrogen atom, a sulfo group, a hydroxy group, a tosylated hydroxy group, an amino group, a substituted amino group, a nitro group, a substituted amide group, or a lower alkoxy group having a sulfo group. The lower alkoxy group having a hydrogen atom, a sulfo group or a sulfo group is preferred. The lower alkoxy group having a sulfo group is preferably linear alkoxy, and the sulfo group is preferably substituted at the end of the alkoxy group. Here, the lower alkoxy group preferably represents an alkoxyl group having 1 to 4 carbon atoms, and the lower alkoxy group having a sulfo group may be either a 3-sulfopropoxy group or a 4-sulfobutoxy group. preferable. The number of the sulfo group as a substituent is preferably 1 to 3, and the position of the sulfo group may be in any benzene nucleus of the naphthalene ring, but preferably the position of substitution of the sulfo group is 1-, 3-, Any of the 6-positions, or a combination of any of the 1-, 3-, 6-, and 7-positions when a plurality of sulfo groups are present. Examples of the compound group represented by A include 2-aminonaphthalene-1-sulfonic acid, 8-aminonaphthalene-1-sulfonic acid, 5-aminonaphthalene-1-sulfonic acid, and 5-aminonaphthalene-2-sulfonic acid. 8-aminonaphthalene-2-sulfonic acid, 3-aminonaphthalene-1-sulfonic acid, 6-aminonaphthalene-2-sulfonic acid, 4-aminonaphthalene-1-sulfonic acid, 7-aminonaphthalene-1,3- Disulfonic acid, 6-aminonaphthalene-1,3-disulfonic acid, 3-amino-7-nitronaphthalene-1,5-disulfonic acid, 4-aminonaphthalene-1,6-disulfonic acid, 4-aminonaphthalene-1, 5-disulfonic acid, 5-aminonaphthalene-1,3-disulfonic acid, 3-aminonaphthalene-1,5-disulfonic acid, 2-aminonaphth Talen-1,5-disulfonic acid, 4-aminonaphthalene-1,6-disulfonic acid, 7-aminonaphthalene-1,3,6-trisulfonic acid, 7-aminonaphthalene-1,3,5-trisulfonic acid 8-aminonaphthalene-1,3,6-trisulfonic acid, 5-aminonaphthalene-1,3,6-trisulfonic acid, 7-amino-3- (3-sulfopropoxy) naphthalene-1-sulfonic acid, 7-amino-3- (4-sulfobutoxy) naphthalene-1-sulfonic acid, 7-amino-4- (3-sulfopropoxy) naphthalene-2-sulfonic acid, 7-amino-4- (4-sulfobutoxy) Naphthalene-2-sulfonic acid, 6-amino-4- (3-sulfopropoxy) naphthalene-2-sulfonic acid, 6-amino-4- (4-sulfobutoxy) naphthalene-2-sulfonic acid, 2- Amino-5- (3-sulfopropoxy) naphthalene-1,7-disulfonic acid, 6-amino-4- (3-sulfopropoxy) naphthalene-2,7-disulfonic acid, or 7-amino-3- (3- Sulfopropoxy) naphthalene-1,5-disulfonic acid and the like, and preferably 7-aminonaphthalene-1,3-disulfonic acid, 6-aminonaphthalene-1,3-disulfonic acid, 7-aminonaphthalene-1, 3,6-trisulfonic acid, 7-amino-4- (3-sulfopropoxy) naphthalene-2-sulfonic acid, and 6-amino-4- (3-sulfopropoxy) naphthalene-2-sulfonic acid, particularly preferred 7-aminonaphthalene-1,3-disulfonic acid, 7-aminonaphthalene-1,3,6-trisulfonic acid, 7-amino-4- (3-sulfopropoxy ) Naphthalene-2-sulfonic acid.

The substituents in the anilines having substituents (R1 to R6), which are primary, secondary, and tertiary coupling components, include a hydrogen atom, a lower alkyl group, a lower alkoxyl group, or a lower alkoxy group having a sulfo group. Preferably a hydrogen atom, a methyl group, a methoxy group, or a 3-sulfopropoxy group or a 4-sulfobutoxy group, more preferably a hydrogen atom, a methyl group, a methoxy group, or a 3-sulfopropoxy group. is there. One or two of these substituents may be bonded. The bonding position is 2-position, 3-position, 2-position and 5-position, 3-position and 5-position, or 2-position and 6-position with respect to the amino group. The-and 2- and 5-positions are preferred. Examples of anilines having a lower alkoxyl group having a sulfo group include 3- (2-amino-4-methylphenoxy) propane-1-sulfonic acid, 3- (2-aminophenoxy) propane-1-sulfonic acid, 3- (2-amino-4-methylphenoxy) butane-1-sulfonic acid and the like. Examples of other anilines include aniline, 2-methylaniline, 3-methylaniline, 2-ethylaniline, 3-ethylaniline, 2,5-dimethylaniline, 2,5-diethylaniline, 2-methoxyaniline, Examples include 3-methoxyaniline, 2-methoxy-5-methylaniline, 2,5-dimethoxyaniline, 3,5-dimethylaniline, 2,6-dimethylaniline, and 3,5-dimethoxyaniline. These anilines may have an amino group protected. Examples of the protecting group include the ω-methanesulfo group. The anilines used for the primary coupling and the anilines used for the secondary coupling may be the same or different.

Examples of the naphthols in the naphthols having Y which is a tertiary coupling component in the case of synthesizing a compound with m = 0 in the formula (2) and a quaternary coupling component in the case of synthesizing a compound with m = 1 include 6-benzoylamino-3-sulfonic acid-1-naphthol, 6- (4′-aminobenzoyl) amino-3-sulfonic acid-1-naphthol, and the like.

The compound represented by the formula (2) used in the present invention may exist in a free acid form or a salt form thereof. Examples of the salt include alkali metal salts, alkaline earth metal salts, alkylamine salts, alkanolamine salts, and ammonium salts. When dyeing | staining to the base material for polarizing films, it is preferable that it is a salt of sodium, potassium, or ammonium. After the coupling reaction, the salt of the compound represented by the formula (2) can be isolated in the form of a free acid by adding a mineral acid, and then the inorganic salt can be removed by washing with water or acidified water. I can do it. Next, the acid type dye having a low salt content thus obtained can be neutralized with a desired inorganic or organic base in an aqueous medium to obtain a solution of the corresponding salt. Alternatively, at the time of salting out after the coupling reaction, for example, sodium chloride can be used to form a sodium salt, for example, potassium chloride can be used to form a potassium salt, and thus a desired salt can be obtained. it can.

Preferred specific examples of the dye represented by the compound (2) of the present invention are listed below. The sulfo group, carboxyl group, and hydroxyl group of the following formulas are represented in the form of free acid.

(Compound Example 1)

(Compound Example 2)

(Compound Example 3)

(Compound Example 4)

(Compound Example 5)

(Composite example 6)

(Compound Example 7)

(Compound Example 8)

(Compound Example 9)

(Compound Example 10)

(Compound Example 11)

(Compound Example 12)

(Compound Example 13)

(Compound Example 14)

(Compound Example 15)

(Compound Example 16)

(Compound Example 17)

(Compound Example 18)

(Compound Example 19)

(Compound Example 20)

(Compound Example 21)

(Compound Example 22)

(Compound Example 23)

(Compound Example 24)

(Compound Example 25)

(Compound Example 26)

The dye shown in Compound (1) is also a dye disclosed in Patent Document 7. The polarizing element of this invention is obtained by mix | blending combining a compound (1) and a compound (2), and making it adsorb | suck to a polyvinyl alcohol film. In order to obtain even better polarization characteristics, the adsorption ratio of compound (1) is such that the adsorption ratio of n = 2 with respect to the total adsorption amount of compounds of n = 1 to 4 in formula (1) is 55% or more. It is preferable to make it. In the above, the adsorption ratio of the compound with n = 2 may be 55% or more, more preferably 65% or more, still more preferably 75% or more, and most preferably 85% or more. In addition, in the compound (1), when the total adsorption ratio of the compound of n = 1 and the compound of n = 3 is 45% or more, a polarizing plate having sufficiently good polarization characteristics at 520 nm to 545 nm cannot be obtained. There is.

The adsorption ratio of the dye in this case is the purity measured by the area ratio by high performance liquid chromatography (hereinafter abbreviated as HPLC), and 0.5 g of a polyvinyl alcohol resin film containing a dichroic dye or a derivative thereof is used. After being immersed in 50% by weight of pyridine water for 24 hours and extracting the pigment from the film into pyridine water, the pyridine water is measured by HPLC, and the ratio is represented by the peak area ratio expressed as a result.

In the formula (1), a method for producing a polarizing element in which the adsorption ratio of the compound n = 2 to the total adsorption amount of the compounds n = 1 to n = 4 is 55% or more includes the compound containing n = 2 A method for producing a polarizing element by producing a dyeing solution using the compound (1) having a ratio of 55% or more, and a dyeing step using the dyeing solution, or a dyeing step for adsorbing the dye to the polyvinyl alcohol film The method of adjusting the temperature and time of the is mentioned.

The azo compound represented by the formula (1) in the form of a free acid is easily produced by performing known diazotization and coupling in accordance with a conventional azo dye production method as described in Non-Patent Document 1. it can. As a specific production method, 4-aminobenzoic acid is diazotized and coupled with aniline represented by compound (4) to obtain compound (5) which is a monoazoamino compound.

Next, the monoazoamino compound and 4,4′-dinitrostilbene-2,2′-sulfonic acid are reacted under an alkaline condition and then subjected to glucose reduction to obtain an azo compound represented by compound (1). .

In the above reaction, the diazotization step may be performed by a conventional method in which a diacid component such as hydrochloric acid or sulfuric acid or a mineral acid aqueous solution or suspension is mixed with a nitrite such as sodium nitrite. Or you may carry out by the reverse method of adding a nitrite to neutral or weakly alkaline aqueous solution of a diazo component, and mixing this and a mineral acid. The diazotization temperature is suitably -10 to 40 ° C. The coupling step with the compound of the formula (1) is carried out by mixing an acidic aqueous solution such as hydrochloric acid or acetic acid with each of the diazo liquids at a temperature of −10 to 40 ° C. and acidic conditions of pH 2 to 7.

In the reaction of the compound of formula (5) with 4,4'-dinitrostilbene-2,2'-sulfonic acid, the condensation step under alkaline conditions is performed under strong alkaline conditions such as sodium hydroxide and lithium hydroxide. The alkali concentration is suitably 2 to 10% by weight, and the temperature is suitably 70 to 100 ° C. N in the formula (1) can be adjusted by changing the molar ratio of the compound of the formula (5) and 4,4'-dinitrostilbene-2,2'-sulfonic acid. In addition, it can be adjusted by the time for the condensation reaction of 4,4′-dinitrostilbene-2,2′-sulfonic acid and the compound of formula (5). As the condensation reaction is faster, n tends to increase. The slower it is, the smaller n tends to be. In the glucose reduction step, the glucose concentration is generally 0.5 to 1.2 equivalents under alkaline conditions.

In the present invention, the azo compound represented by the formula (1) can be used as a free acid or a salt of an azo compound. Examples of such salts include organic salts such as alkali metal salts such as lithium salts, sodium salts, and potassium salts, ammonium salts, and amine salts. In general, a sodium salt is used. After the salting out of the organic salt, n in the formula (1) can be adjusted even at the filtration temperature. The lower the filtration temperature, the smaller the value of n. The higher the filtration temperature, the larger n is. Tend to show. The filtration temperature for obtaining a pigment having a high content ratio of n = 2 is 50 ° C. to 95 ° C., preferably 60 ° C. to 95 ° C.

In the present invention, the content ratio of compounds in which n is 1 to 4 in the compound of formula (1) is not necessarily limited. That is, the adsorption ratio of the compound with n = 2 varies depending on the conditions of the manufacturing process of the polarizing element. Specifically, the composition of the dye to be dyed and the composition of the dye composition adsorbed in the film vary depending on the degree of swelling in the swelling process, the adsorption ratio in the dyeing process, and the elution of the dye in the water washing process and the stretching process. However, in order to make the adsorption ratio of the compound of n = 2 in the film 55% or more, the composition of the compound of the formula (1) is such that the content ratio of the compound n = 2 is 55% or more. Use is preferable because the present invention can be easily achieved.

In the dyeing step, when the adsorption ratio of the compound with n = 2 to 55% or more with respect to the total adsorption amount of the compounds with n = 1 to 4 in the compound (1), the ratio that the compound with smaller n is adsorbed as the dyeing temperature is lower The higher the dyeing temperature, the higher the rate of adsorption of compounds with a large n. However, even if the dyeing temperature is too low, the adsorption of the dye itself is remarkably reduced, and if it is too high, problems such as uneven dyeing and dissolution of the polyvinyl alcohol film in the dyeing solution occur. The dyeing temperature is not particularly limited because it depends on the degree of polymerization of the polyvinyl alcohol film, the water content, and the influence of the swelling process. However, a preferable temperature range in the present invention is typically 30 to 60. ° C, preferably 35-50 ° C. In addition, the time of immersion in the dyeing solution at that time may be appropriately adjusted and is not limited. However, the lower the time of immersion, the higher the adsorption ratio of the compound having a smaller n, and the higher the dyeing temperature. As the value of n increases, the adsorption ratio of the compound increases. Generally, the staining time is adjusted from 30 seconds to 20 minutes, but in the present invention, it is more preferably 2 to 10 minutes, more preferably 3 to 9 minutes. The dyeing method is preferably immersed in the solution, but can also be performed by applying the solution to a polyvinyl alcohol-based resin film, bringing it into contact, and controlling the temperature at an appropriate temperature.

Further, other dyes may be used in combination as long as the polarization characteristics of the dye of the present invention are not impaired. Examples of such pigments are C.I. Eye. direct. Yellow 12, sea. Ai. direct. Yellow 28, Sea. Ai. direct. Yellow 44, Sea. Eye. direct. Orange 26, Sea. Eye. direct. Orange 39, sea. Ai. direct. Orange 107, sea. Ai. direct. Red 81 is mentioned. Other than these dichroic dyes, other organic dyes can be used in combination as required. The blending ratio is not particularly limited, and the blending amount can be arbitrarily set according to demands such as a light source and a hue. By using the above dyes, the polarizing element of the present invention is produced.

After the dyeing process, a cleaning process (hereinafter referred to as cleaning process 1) can be performed before entering the next process. The dyeing process 1 is a process of washing the dye solvent adhering to the surface of the polyvinyl alcohol film in the dyeing process. By performing the washing step 1, it is possible to suppress the migration of the dye into the liquid to be processed next. In the cleaning step 1, water is generally used. The washing method is preferably immersed in the solution, but can be washed by applying the solution to a polyvinyl alcohol film. The washing time is not particularly limited, but is preferably 1 to 300 seconds, more preferably 1 to 60 seconds. The temperature of the solvent in the washing step 1 needs to be a temperature at which the hydrophilic polymer does not dissolve. Generally, it is washed at 5 to 40 ° C.

After the dyeing step or washing step 1, a step of adding a crosslinking agent and / or a water resistance agent can be performed. Examples of the crosslinking agent include boron compounds such as boric acid, borax or ammonium borate, polyvalent aldehydes such as glyoxal or glutaraldehyde, polyisocyanate compounds such as biuret type, isocyanurate type or block type, titanium oxy Titanium compounds such as sulfate can be used, but ethylene glycol glycidyl ether, polyamide epichlorohydrin, and the like can also be used. Examples of the water-resistant agent include succinic peroxide, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, ammonium chloride or magnesium chloride, preferably boric acid. Used. The step of containing a crosslinking agent and / or a water-resistant agent is performed using at least one kind of crosslinking agent and / or a water-resistant agent shown above. As a solvent in that case, water is preferable, but it is not limited. The concentration of the cross-linking agent and / or the water-proofing agent in the solvent in the step of adding the cross-linking agent and / or the water-proofing agent is 0.1 to 6.0 when boric acid is used as an example. % By weight is preferable, and 1.0 to 4.0% by weight is more preferable. The solvent temperature in this step is preferably 5 to 70 ° C, more preferably 5 to 50 ° C. Although it is preferable to immerse the polyvinyl alcohol film in a solution containing a crosslinking agent and / or a water-resistant agent, the solution may be applied to or applied to the polyvinyl alcohol film. The treatment time in this step is preferably 30 seconds to 6 minutes, more preferably 1 to 5 minutes. However, if it is not necessary to contain a crosslinking agent and / or a water-resistant agent and it is desired to shorten the time, this treatment step may be omitted if a crosslinking treatment or a water-resistant treatment is unnecessary. .

After the dyeing step, the washing step 1, or the step of adding a crosslinking agent and / or a water resistance agent, the stretching step is performed. The stretching step is a step of stretching the polyvinyl alcohol film uniaxially. The stretching method may be either a wet stretching method or a dry stretching method.

In the case of the dry stretching method, when the stretching heating medium is an air medium, the temperature of the air medium is preferably stretched at a room temperature to 180 ° C. The treatment is preferably performed in an atmosphere of 20 to 95% RH. Examples of the heating method include an inter-roll zone stretching method, a roll heating stretching method, a pressure stretching method, an infrared heating stretching method, and the like, but the stretching method is not limited. The stretching step can be performed in one step, but can also be performed by two or more multi-step stretching.

In the case of the wet stretching method, stretching is performed in water, a water-soluble organic solvent, or a mixed solution thereof. It is preferable to perform the stretching treatment while being immersed in a solution containing a crosslinking agent and / or a water resistance agent. Examples of the crosslinking agent include boron compounds such as boric acid, borax or ammonium borate, polyvalent aldehydes such as glyoxal or glutaraldehyde, polyisocyanate compounds such as biuret type, isocyanurate type or block type, titanium oxy Titanium compounds such as sulfate can be used, but ethylene glycol glycidyl ether, polyamide epichlorohydrin, and the like can also be used. Examples of water-proofing agents include succinic peroxide, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, ammonium chloride, and magnesium chloride. Stretching is performed in a solution containing at least one or more crosslinking agents and / or waterproofing agents as described above. The crosslinking agent is preferably boric acid. The concentration of the crosslinking agent and / or waterproofing agent in the stretching step is preferably, for example, 0.5 to 15% by weight, more preferably 2.0 to 8.0% by weight. The draw ratio is preferably 2 to 8 times, more preferably 5 to 7 times. The stretching temperature is preferably 40 to 60 ° C, more preferably 45 to 58 ° C. The stretching time is usually from 30 seconds to 20 minutes, more preferably from 2 to 5 minutes. The wet stretching step can be performed in one step, but can also be performed by two or more steps.

After performing the stretching step, the film surface may be subjected to a cleaning step (hereinafter referred to as a cleaning step 2) because the cross-linking agent and / or waterproofing agent may precipitate or foreign matter may adhere to the film surface. it can. The washing time is preferably 1 second to 5 minutes. The washing method is preferably immersed in a washing solution, but the solution can be washed on the polyvinyl alcohol resin film by coating or coating. The cleaning process can be performed in one stage, and the multi-stage process of two or more stages can be performed. The solution temperature in the washing step is not particularly limited, but is usually 5 to 50 ° C., preferably 10 to 40 ° C.

As the solvent used in the treatment steps so far, for example, water, dimethyl sulfoxide, N-methylpyrrolidone, methanol, ethanol, propanol, isopropyl alcohol, glycerin, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol or triethylene glycol Examples of the solvent include, but are not limited to, alcohols such as methylolpropane, and amines such as ethylenediamine or diethylenetriamine. A mixture of one or more of these solvents can also be used. The most preferred solvent is water.

After the stretching process or washing process 2, a film drying process is performed. The drying process can be performed by natural drying, but in order to further improve the drying efficiency, the surface can be removed by compression with a roll, an air knife, a water absorption roll, etc., and / or blow drying is performed. You can also. The drying treatment temperature is preferably 20 to 100 ° C., more preferably 60 to 100 ° C. A drying treatment time of 30 seconds to 20 minutes can be applied, but 5 to 10 minutes is preferable.

By the above method, a polarizing element comprising a stretched polyvinyl alcohol resin film formed by adsorbing the compound (1) and the compound (2) can be produced.

The obtained polarizing element is made into a polarizing plate by providing a transparent protective layer on one side or both sides thereof. The transparent protective layer can be provided as a polymer coating layer or as a film laminate layer. The transparent polymer or film forming the transparent protective layer is preferably a transparent polymer or film having high mechanical strength and good thermal stability. Examples of substances used as the transparent protective layer include cellulose acetate resins such as triacetyl cellulose and diacetyl cellulose or films thereof, acrylic resins or films thereof, polyvinyl chloride resins or films thereof, polyester resins or films thereof, polyarylate resins or The film, a cyclic polyolefin resin having a cyclic olefin such as norbornene or the film thereof, polyethylene, polypropylene, a polyolefin having a cyclo or norbornene skeleton or a copolymer thereof, and the main chain or side chain of which is imide and / or amide Examples thereof include a resin, a polymer, or a film thereof. In addition, a resin having liquid crystallinity or a film thereof can be provided as the transparent protective layer. The thickness of the protective film is, for example, about 0.5 to 200 μm. A polarizing plate is produced by providing one or more layers of the same or different types of resins or films on one side or both sides.

An adhesive is required to bond the transparent protective layer to the polarizing element. Although it does not specifically limit as an adhesive agent, A polyvinyl alcohol-type adhesive agent is preferable. Examples of the polyvinyl alcohol-based adhesive include, but are not limited to, Gohsenol NH-26 (manufactured by Nihon Gosei Co., Ltd.), EXEVAL RS-2117 (manufactured by Kuraray Co., Ltd.), and the like. A cross-linking agent and / or a waterproofing agent can be added to the adhesive. As the polyvinyl alcohol-based adhesive, a maleic anhydride-isobutylene copolymer is used, but if necessary, an adhesive mixed with a crosslinking agent can be used. As maleic anhydride-isobutylene copolymers, for example, isoban # 18 (manufactured by Kuraray), isoban # 04 (manufactured by Kuraray), ammonia-modified isoban # 104 (manufactured by Kuraray), ammonia-modified isoban # 110 (manufactured by Kuraray) ), Imidized isoban # 304 (manufactured by Kuraray), imidized isoban # 310 (manufactured by Kuraray), and the like. A water-soluble polyvalent epoxy compound can be used as the crosslinking agent at that time. Examples of the water-soluble polyvalent epoxy compound include Denacol EX-521 (manufactured by Nagase Chemtech) and Tetrat-C (manufactured by Mitsui Gas Chemical Co., Ltd.). Moreover, as adhesives other than polyvinyl alcohol-type resin, well-known adhesives, such as urethane type, an acrylic type, and an epoxy type, can also be used. Further, for the purpose of improving the adhesive strength of the adhesive or improving the water resistance, additives such as zinc compounds, chlorides, iodides and the like can be simultaneously contained at a concentration of about 0.1 to 10% by weight. The additive is not limited. After laminating the transparent protective layer with an adhesive, the polarizing plate is obtained by drying or heat treatment at a suitable temperature.

When the obtained polarizing plate is bonded to a display device such as liquid crystal or organic electroluminescence, various functional layers and luminance for improving the viewing angle and / or contrast on the surface of the protective layer or film that will be the non-exposed surface later. An improving layer or film can also be provided. In order to bond these polarizing plates to a film or a display device, it is preferable to use an adhesive.

The polarizing plate may have various known functional layers such as an antireflection layer, an antiglare layer, and a hard coat layer on the other surface, that is, the exposed surface of the protective layer or film. A coating method is preferable for producing the layer having various functions, but a film having the function can be bonded through an adhesive or a pressure-sensitive adhesive. The various functional layers can be a layer or a film for controlling the phase difference.

The polarizing plate for a liquid crystal projector, which is one form of use of the polarizing plate of the present invention, is usually used as a polarizing plate with a support. In order to attach a polarizing plate, the support preferably has a flat portion, and since it is used for optical purposes, a glass molded product is preferable. Examples of the glass molded product include a glass plate, a lens, and a prism (for example, a triangular prism and a cubic prism). A lens attached with a polarizing plate can be used as a condenser lens with a polarizing plate in a liquid crystal projector. Further, a prism with a polarizing plate attached thereto can be used as a polarizing beam splitter with a polarizing plate or a dichroic prism with a polarizing plate in a liquid crystal projector. Moreover, you may affix on a liquid crystal cell. Examples of the material of the glass include inorganic glass such as soda glass, borosilicate glass, inorganic base made of quartz, inorganic base made of sapphire, and organic plastic plates such as acrylic and polycarbonate. Is preferred. The glass plate may have a desired thickness and size. In order to further improve the single plate light transmittance, it is preferable to provide an AR layer on one or both of the glass surface and the polarizing plate surface of the polarizing plate with glass.

A polarizing plate with a support for a liquid crystal projector is produced by a method known per se. For example, a transparent adhesive (adhesive) agent is applied to a flat surface of a support, and then the polarizing plate of the present invention is applied to the coated surface. Affix. Alternatively, a transparent adhesive (adhesive) agent may be applied to the polarizing plate, and then a support may be attached to the coated surface. The adhesive (adhesive) agent used here is preferably, for example, an acrylic ester-based one. When this polarizing plate is used as an elliptical polarizing plate, the retardation plate side is usually attached to the support side, but the polarizing plate side may be attached to a glass molded product.

By the above method, a polarizing plate comprising a stretched polyvinyl alcohol resin film in which the compound (1) and the compound (2) are adsorbed can be produced.

The polarizing plate thus obtained is suitable as a polarizing plate for a light source having the highest emission intensity at 520 nm to 545 nm. In particular, it is suitable for an LED light source that emits green light or a laser light source. For example, a green LED light source often has the highest light emission intensity at 538 nm, and even the laser light source has the highest light emission intensity at 525 nm to 540 nm. It is known that the light source has a light source, and it is a polarizing element or a polarizing plate effective for such a green light emitting LED light source and a laser light source. ADVANTAGE OF THE INVENTION According to this invention, with respect to the video display apparatus using the liquid crystal cell corresponding to a LED light source or a Laser light source, a polarizing plate with high contrast and high durability with respect to light and / or heat can be provided. A display using the polarizing element or polarizing plate of the present invention is highly reliable, has a long-term high contrast, and has a high color reproducibility.

For example, when the polarizing plate of the present invention thus obtained is used for an LED light source or a laser light source of a liquid crystal projector, a liquid crystal projector with improved brightness, high contrast, and high durability is obtained. Conventionally, the wavelength of the polarizing plate required for the green light source of the liquid crystal projector is 500-600 nm, and it has been necessary to have a high degree of polarization particularly at a wavelength of 530-590 nm. When used for a light source or a laser light source, a polarization characteristic in a range of 510 to 570 nm centering on a range of 520 to 545 nm is required. The reason why the required wavelength differs from the conventional light source is that, in order to emit green light up to now, the white light source is dimmed by a dichroic mirror, etc., so that it is separated from the blue or red light source. Therefore, the band is required to be 500-600 nm because it is a separated wavelength that can be used as a green light source because 500 nm or less is blue, 600 nm or more is red, and 500 nm to 600 nm is green. It was. On the other hand, the LED light source and the laser light source itself are green light emission. As a result, the light emission band is narrow and sharp, and the light emission intensity is shorter than before (520 nm to 545 nm). Therefore, the desired center wavelength is 510-570 nm centered on 520-545 nm and the wavelength range is narrow, and the required wavelength is different from the conventional one. Therefore, since the required polarizing plate has also changed, it was important to select a dye around the required wavelength. In particular, in the case of an LED light source or a laser light source, the wavelength of the strongest light source is in the range of 520 nm to 545 nm. Therefore, the present invention is very effective for improving the polarization characteristics of the wavelength.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In the following, “part” represents “part by weight”. Moreover, the transmittance | permeability shown in an Example was performed as follows.

When measuring the transmittance using a spectrophotometer [“U-4100” manufactured by Hitachi, Ltd.], the transmittance after correcting the visibility based on JIS-Z8701 (C light source 2 ° field of view) on the light exit side. An iodine polarizing plate (SKN-18043P manufactured by Polatechno Co., Ltd.) having a polarization degree of 99.99% at 43% was installed so that absolute polarized light could be incident on the measurement sample. In this case, the protective layer of the iodine-based polarizing plate is triacetyl cellulose having no ultraviolet absorbing ability.

Absolutely polarized light is incident on the polarizing plate of the present invention, and the vibration direction of the absolute polarized light and the absorption axis direction of the polarizing plate of the present invention are orthogonal (the absorption axis of the absolute polarizer and the absorption axis of the polarizing plate of the present invention). Ky is the absolute parallel transmittance obtained by the measurement so that the polarization direction of the polarized light is parallel to the absorption axis direction of the polarizing plate of the present invention (the absorption axis of the absolute polarizer and this The absolute orthogonal transmittance obtained by measuring so that the absorption axis of the polarizing plate of the invention was orthogonal) was defined as Kz.

Each transmittance was measured using a spectrophotometer [“U-4100” manufactured by Hitachi, Ltd.].

Example 1
<Synthesis of Compound (1)>
13.7 parts of 4-aminobenzoic acid was added to 500 parts of water and dissolved with sodium hydroxide. At 10 ° C. or lower, 32 parts of 35% by weight hydrochloric acid was added, and then 6.9 parts of sodium nitrite was added, followed by stirring at 5 to 10 ° C. for 1 hour. Thereto was added 20.9 parts of aniline-ω-sodium methanesulfonate, and sodium carbonate was added to adjust the pH to 3.5 while stirring at 20-30 ° C. Further, the mixture was stirred to complete the coupling reaction and filtered to obtain a monoazo compound. The obtained monoazo compound was stirred at 90 ° C. in the presence of sodium hydroxide to obtain 17 parts of the monoazo compound of the formula (5). After dissolving 12 parts of the monoazo compound of the formula (5) and 21 parts of 4,4′-dinitrostilbene-2,2′-sulfonic acid in 300 parts of water, 12 parts of sodium hydroxide is added and condensed at 90 ° C. Reacted. Subsequently, after reducing with 9 parts of glucose and salting out with sodium chloride, the mixture was filtered at 90 ° C. and evaporated to dryness at 80 ° C. to obtain Dye A represented by the formula (1). When the dye A was dissolved in 20% by weight of pyridine water and measured by HPLC, the ratio of the compound of n = 1 to 4 in the formula (1) was such that n = 1 was 33%, n = 2 was 65%, n = 3 was a dye comprising 2%.

<Synthesis of Compound Example 10>
Add 20.3 parts of 2-amino-5-methoxybenzenesulfonic acid to 500 parts of water, dissolve with sodium hydroxide, cool, add 32 parts of 35% hydrochloric acid at 10 ° C. or lower, and then add sodium nitrite 6. 9 parts were added and stirred at 5-10 ° C. for 1 hour. Thereto was added 10.7 parts of 3-methylaniline dissolved in dilute hydrochloric acid, and while stirring at 30 to 40 ° C., sodium carbonate was added to pH 3, and further stirred to complete the coupling reaction, filtered, A monoazo compound was obtained. To the obtained monoazo compound, 32 parts of 35% hydrochloric acid and then 6.9 parts of sodium nitrite were added and stirred at 25-30 ° C. for 2 hours. Thereto was added 12.1 parts of 2,5-dimethylaniline dissolved in dilute hydrochloric acid, and while stirring at 20-30 ° C., sodium carbonate was added to pH 3, and further stirred to complete the coupling reaction and filtered. Thus, a disazo compound was obtained. After 15 parts of the resulting disazo compound is dispersed in 600 parts of water, 32 parts of 35% hydrochloric acid and then 6.9 parts of sodium nitrite are added, followed by stirring at 25-30 ° C. for 2 hours for diazotization. On the other hand, 35.8 parts of 6- (4 ″ -benzoyl) amino-3-sulfonic acid-1-naphthol was added to 250 parts of water and dissolved as weakly alkaline with sodium carbonate. The diazotized compound is injected while maintaining the pH of 7 to 10, and stirred to complete the coupling reaction. Salting out with sodium chloride and filtering, a trisazo compound represented by compound 10 of the present invention was obtained as a sodium salt.

<Production of polarizing element>
A 75-μm-thick polyvinyl alcohol resin film (VF series manufactured by Kuraray Co., Ltd.) having a saponification degree of 99% or more was immersed in warm water at 40 ° C. for 3 minutes for swelling treatment. The swelling-treated film was 0.02% by weight of the dye A represented by the compound (1), 0.1% by weight of the dye of Compound Example 10, 0.1% by weight of sodium tripolyphosphate, and 0.1% by weight of sodium sulfate. Was immersed in an aqueous solution containing 45 ° C. to adsorb the dye. The film on which the dye was adsorbed was washed with water, and after washing, boric acid treatment was carried out for 1 minute with a 40 ° C. aqueous solution containing 2% by weight of boric acid. The film obtained by the boric acid treatment was treated for 5 minutes in an aqueous solution at 55 ° C. containing 3.0% by weight of boric acid while stretching 5.0 times. While maintaining the tension of the film obtained by the boric acid treatment, the film was treated with water at room temperature for 15 seconds. The film obtained by the treatment was immediately dried at 60 ° C. for 5 minutes to obtain a polarizing element having a thickness of 28 μm. When the obtained polarizing element was immersed in 50% by weight of pyridine to extract the pigment, the ratio of the compounds of formula (1) where n = 1 to 4 was 13% for n = 1 and n = 2. 82%, n = 3 was 5%. 80 μm thick triacetyl cellulose film (TD-80U manufactured by Fuji Photo Film Co., Ltd., hereinafter abbreviated as TAC) obtained by subjecting the obtained polarizing element to an alkali treatment using a polyvinyl alcohol adhesive, TAC / adhesive layer / polarizing element / Adhesive layer / TAC are laminated and laminated to obtain a polarizing plate to obtain a measurement sample.

Example 2
Add 29.9 parts of sodium 4-aminoazobenzene-4-sulfonate to 600 parts of water and dissolve at 70 ° C. Cool to 30 ° C or less, add 32 parts of 35% hydrochloric acid, then add 6.9 parts of sodium nitrite and stir at 25-28 ° C for 2 hours. Thereto, 12.1 parts of 2,5 dimethylaniline was added and stirred at 25-30 ° C. for 2 hours. Then, sodium carbonate was added to adjust the pH to 3, further stirring to complete the coupling reaction, filtration, and disazo compound Get. After the obtained disazo compound is dispersed in 600 parts of water, 32 parts of 35% hydrochloric acid and then 6.9 parts of sodium nitrite are added, followed by stirring at 25-30 ° C. for 2 hours for diazotization. On the other hand, 35.8 parts of 4 ″ -aminobenzoyl J acid is added to 250 parts of water and dissolved with sodium carbonate as weakly alkaline. The diazo compound of the disazo compound obtained previously is neutralized to weakly alkaline. Pour and stir to complete the coupling reaction. A sample was prepared in the same manner as in Example 1 except that Compound Example 1 obtained by salting out with sodium chloride, filtering and evaporating to dryness was changed from Compound Example 10 used in Example 1, and a polarizing element was prepared. It was.

Example 3
Instead of 10.7 parts of 3-methylaniline in Example 1 and 13.7 parts of 2-methoxy-5-methylaniline, 6- (4′-benzoyl) amino-3-sulfonic acid-1-naphthol was used. , 6- (4′-aminobenzoyl) amino-3-sulfonic acid-1-naphthol Compound Example 12 obtained in the same manner as in Example 1 except that Compound Example 10 was used instead of Compound Example 10 to prepare a polarizing element. A sample was prepared in the same manner as in Example 1 to obtain a measurement sample.

Example 4
In Example 3, the filtration temperature after salting out with sodium chloride was 45 ° C., and in the ratio of n in formula (1), n = 1 was 58%, n = 2 was 40%, and n = 3 was 2%. A dye (hereinafter referred to as "Dye B") was used. In the dyeing process for preparing the polarizing element, the sample was prepared and measured in the same manner as in Example 3 except that the content of the dye B was 0.08% by weight and the temperature of the dyeing process was 30 ° C. A sample was used. When the obtained polarizing element was immersed in water containing 50% by weight of pyridine and the pigment was extracted, the adsorption ratio of the compound of n = 1 to 4 in the formula (1) was 56% for n = 1 and n = 2. Was 43% and n = 3 was 1%.

Example 5
38.3 parts of 7-aminonaphthalene-1,3,6-trisulfonic acid is added to 500 parts of water, cooled, 10 ° C. or below, 31.3% of 35% hydrochloric acid is added, and then 6.9 parts of sodium nitrite Was stirred at 5-10 ° C. for 1 hour to diazotize. Thereto was added 10.7 parts of 3-methylaniline dissolved in dilute hydrochloric acid, and while stirring at 10-30 ° C., sodium carbonate was added to pH 3, and further stirred to complete the coupling reaction, filtered, 40.1 parts of monoazoamino compound were obtained. The obtained monoazoamino compound is added to 400 parts of water, dissolved with sodium hydroxide, 25.0 parts of 35% hydrochloric acid at 10 to 30 ° C., and then 5.5 parts of sodium nitrite are added, and 20 to 30 ° C. For 1 hour and diazotized. Thereto was added 8.6 parts of 3-methylaniline dissolved in dilute hydrochloric acid, and while stirring at 20-30 ° C., sodium carbonate was added to pH 3, and further stirred to complete the coupling reaction, filtered, 39.7 parts of a disazoamino compound were obtained. The obtained disazoamino compound is added to 250 parts of water, dissolved with sodium hydroxide, 20.0 parts of 35% hydrochloric acid is added at 20-30 ° C., and then 4.4 parts of sodium nitrite is added. The mixture was stirred for 1 hour and diazotized. Thereto, 7.7 parts of 2,5-dimethylaniline dissolved in dilute hydrochloric acid was added, and while stirring at 20-30 ° C., sodium carbonate was added to pH 3.5, and further stirred to complete the coupling reaction. Filtration gave 38.5 parts of the trisazoamino compound. The obtained trisazoamino compound is added to 200 parts of water, dissolved with sodium hydroxide, 16.0 parts of 35% hydrochloric acid is added at 20 to 30 ° C., and then 3.5 parts of sodium nitrite is added to obtain 20 to 30 ° C. For 1 hour and diazotized. On the other hand, 16.1 parts of 6- (4′-aminobenzoyl) amino-3-sulfonic acid-1-naphthol was added to 50 parts of water and dissolved as weakly alkaline with sodium carbonate. The diazotized amino compound is injected while maintaining the pH at 8-10, and stirred to complete the coupling reaction. Salting out with sodium chloride and filtering, a tetrakisazo compound represented by compound example 17 was obtained. A sample was prepared in the same manner as the measurement sample, except that the polarizing element was prepared by changing the obtained dye of Compound Example 17 to Compound Example 10 used in Example 1.

Example 6
Add 25.3 parts of 4-aminobenzene-1,3-disulfonic acid to 500 parts of water, cool, add 31.3 of 35% hydrochloric acid at 10 ° C. or lower, then add 6.9 parts of sodium nitrite, The mixture was stirred at 5-10 ° C. for 1 hour to diazotize. Thereto was added 10.7 parts of 3-methylaniline dissolved in dilute hydrochloric acid, and while stirring at 10-30 ° C., sodium carbonate was added to pH 3, and further stirred to complete the coupling reaction, filtered, 29.7 parts of monoazoamino compound were obtained. The obtained monoazoamino compound is added to 400 parts of water, dissolved with sodium hydroxide, 25.0 parts of 35% hydrochloric acid at 10 to 30 ° C., and then 5.5 parts of sodium nitrite are added, and 20 to 30 ° C. For 1 hour and diazotized. Thereto was added 8.6 parts of 3-methylaniline dissolved in dilute hydrochloric acid, and while stirring at 20-30 ° C., sodium carbonate was added to pH 3, and further stirred to complete the coupling reaction, filtered, 31.3 parts of a disazoamino compound were obtained. The obtained disazoamino compound is added to 250 parts of water, dissolved with sodium hydroxide, 20.0 parts of 35% hydrochloric acid is added at 20-30 ° C., and then 4.4 parts of sodium nitrite is added. The mixture was stirred for 1 hour and diazotized. Thereto, 7.7 parts of 2,5-dimethylaniline dissolved in dilute hydrochloric acid was added, and while stirring at 20-30 ° C., sodium carbonate was added to pH 3.5, and further stirred to complete the coupling reaction. Filtration gave 31.8 parts of a trisazoamino compound. The obtained trisazoamino compound is added to 200 parts of water, dissolved with sodium hydroxide, 16.0 parts of 35% hydrochloric acid is added at 20 to 30 ° C., and then 3.5 parts of sodium nitrite is added to obtain 20 to 30 ° C. For 1 hour and diazotized. On the other hand, 16.1 parts of 6- (4′-benzoyl) amino-3-sulfonic acid-1-naphthol was added to 50 parts of water, dissolved as weakly alkaline with sodium carbonate, and the trisazoamino obtained previously in this liquid The compound diazotide is injected while maintaining pH 8-10 and stirred to complete the coupling reaction. Salting out with sodium chloride gave the tetrakisazo compound shown in Compound Example 19. A sample was prepared in the same manner as in Example 1 except that Compound Example 10 used in Example 1 was used in Compound Example 19 to prepare a measurement sample.

Example 7
Compound example obtained by changing 6- (4′-benzoyl) amino-3-sulfonic acid-1-naphthol in Example 6 to 6- (4′-aminobenzoyl) amino-3-sulfonic acid-1-naphthol 24 was changed to Compound Example 10 used in Example 1, and a sample was prepared in the same manner as in Example 1 except that a polarizing element was prepared.

Comparative Example 1
A sample was prepared in the same manner as in Example 1 except that Compound Example 10 used in Example 1 was used at 0.05% by weight of C.I.

Comparative Example 2
Add 29.9 parts of sodium 4-aminoazobenzene-4′-sulfonate to 600 parts of water and dissolve at 70 ° C. Cool to 30 ° C. or less, add 32 parts of 35% hydrochloric acid, then add 6.9 parts of sodium nitrite and stir at 25-28 ° C. for 2 hours to diazotize.
On the other hand, 31.5 parts of 6- (4′-aminobenzoyl) amino-3-sulfonic acid-1-naphthol was added to 250 parts of water and dissolved as weakly alkaline with sodium carbonate. A diazotized compound is injected while maintaining a pH of 7 to 9, and stirred to complete the coupling reaction. The cake obtained by salting out with sodium chloride and filtering was again dissolved and salted out, and evaporated to dryness to obtain a water-soluble dye of the disazo compound of formula (6). In Example 1, a polarizing plate was prepared in the same manner as the measurement sample except that the dye to be adsorbed was changed to 0.04% by weight of the dye represented by the formula (6).

Comparative Example 3
A polarizing plate SHC-PGW-306 for projector green light source sold by Polatechno Co., Ltd. was used as a comparative sample. A measurement sample using TAC / adhesive layer / polarizing element / adhesive layer / TAC having the same configuration as in Example 1 was used.

Comparative Example 4
A polarizing plate SHC-PGW-307 for projector green light source sold by Polatechno Co., Ltd. was used as a comparative sample. A measurement sample using TAC / adhesive layer / polarizing element / adhesive layer / TAC having the same configuration as in Example 1 was used.

Table 1 shows spectroscopic measurement values of 520 nm to 545 nm of polarizing plates obtained by measuring Examples 1 to 7 and Comparative Examples 1 to 4, and Table 2 shows spectroscopic measurement values of 510 nm to 570 nm, which are wider. Is shown. Ky520-545 is the average value of Ky from 520 nm to 545 nm when the average value of Kz from 520 nm to 545 nm is 0.01%, and shows the difference from Comparative Example 4 at that time. Yes. Ky510-570 is the average value of Ky from 510 nm to 570 nm when the average value of Kz from 510 nm to 570 nm is 0.01%, and Table 2 shows the comparison with Comparative Example 4 at that time. Showing the difference.

As can be seen from the comparison results of Examples 1 to 7 and Comparative Examples 1 to 4, the polarizing plate of the present invention has a high Ky when it has an equivalent orthogonal transmittance centered on 520 to 545 nm, and even at 510 nm to 570 nm. Similarly, Ky is high when it has orthogonal transmittance. This indicates that a polarizing plate having a high transmittance is obtained when it has an equivalent orthogonal transmittance. This shows that, by using the present invention, a display device that is designed to display equivalent black can display with higher white luminance. In particular, when Comparative Example 4 and Examples 1 to 7 are compared, the brightness of the polarizing plate is improved by 2% to 5%, and it can be seen that good results are obtained.

Example 8
Instead of the installed polarizing plate corresponding to the green light source of the Samsung projector (product name: SP-F10M) having a three-wavelength LED light source, the polarizing plate obtained in Example 3 is mounted in a dark room. The 50-inch size was irradiated, and the contrast at the time of white projection and black projection was measured with a color illuminance meter 520/06 manufactured by Yokogawa at the central portion 20 minutes after irradiation.

Example 9
In Example 8, the contrast was measured in the same manner except that the polarizing plate obtained in Example 7 was used.

Comparative Example 5
In Example 8, the contrast was measured in the same manner except that the polarizing plate obtained in Comparative Example 3 was used.

Comparative Example 6
In Example 8, the contrast was measured in the same manner except that the polarizing plate obtained in Comparative Example 4 was used.

The emission intensity of a green light source of a Samsung projector (product name: SP-F10M) having a three-wavelength LED light source was measured with a SPECTORADIOMETER (product name: USR-40) manufactured by USHIO using an ND filter. The emission intensity as shown in FIG. The wavelength with the highest emission intensity was 538 nm. This is an example in which the LED light source is found to have the highest emission intensity at 520 nm to 545 nm.

Table 3 shows the contrasts obtained by the measurements of Example 8, Example 9, Comparative Example 5, and Comparative Example 6.

As is clear from the above Example 8, Example 9, Comparative Example 5, and Comparative Example 6, the polarizing plate of the present invention is actually mounted on a projector having an LED light source to obtain a projector having high contrast. You can see that This also shows that the polarizing plate can provide high contrast in a liquid crystal projector having a light source having the highest light emission intensity at 520 to 545 nm.

Claims (10)

1. A polarizing element comprising a film of a polyvinyl alcohol resin or a derivative thereof containing the dichroic dye represented by the following formula (1) and the following formula (2) or a salt thereof and stretched.
   

   

   (In formula (1), n is an integer of 1 to 4.)
   

   

   (In Formula (2), X represents a phenyl group or a naphthyl group having at least one sulfo group, R _{1 to} R ₆ are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or 1 carbon atom. To an alkoxyl group or an acetylamino group which is 3 to 3, Y represents a hydrogen atom or an amino group, and m represents 0 or 1, respectively.
2. The polarizing element according to claim 1, wherein Y in formula (2) is an amino group.
3. The polarizing element according to claim 1, wherein when m = 0 in formula (2), X is a phenyl group having at least one sulfo group.
4. The polarizing element according to claim 3, wherein X has a structure represented by the following formula (3).
   

   

   
   (In formula (3), Z ₁ represents a sulfo group, a methoxy group or a carboxyl group, and Z ₂ represents a sulfo group.)
5. In the formula (2), when m = 1, X is a naphthyl group having at least two substituents, at least one of the substituents is a sulfo group, and the other substituents are a hydroxy group or a sulfo group The polarizing element according to claim 1, wherein the polarizing element is an alkoxy group having
6. In the formula (2), when m = 1, X is a phenyl group having at least two substituents, at least one of the substituents is a sulfo group, and the other substituents are a hydrogen atom, a sulfo group, The polarizing element according to claim 1, which is an alkyl group, an alkoxy group, an alkoxy group having a sulfo group, a carboxy group, a nitro group, an amino group, or an acetylamino group.
7. 7. The polarized light according to claim 1, wherein in the dichroic dye of the formula (1), the adsorption ratio of n = 2 with respect to the total adsorption amount of n = 1 to n = 4 is 55% or more. element.
8. The polarizing plate which provides a support body film in the at least single side | surface of the polarizing element of any one of Claims 1 thru | or 6.
9. A polarizing plate with an inorganic substrate, wherein the polarizing element according to any one of claims 1 to 7 or the polarizing plate according to claim 8 is laminated on an inorganic substrate.
10. A projector on which the polarizing element according to any one of claims 1 to 6 or the polarizing plate according to any one of claims 7 to 9 is mounted.

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