HK1152066B - Azo compounds, and dye-based polarizing films and polarizing plates comprising the same - Google Patents

Description

Azo compound, and dye-based polarizing film and polarizing plate comprising the same

Technical Field

The present invention relates to a novel azo compound and a salt thereof, and a dye-based polarizing film and a polarizing plate comprising the same.

Background

Both the polarizing plate having a light transmission/shielding function and the liquid crystal having a light conversion function are essential components of a display device such as a Liquid Crystal Display (LCD). The application fields of LCDs have been expanded from the earliest small-sized machines such as electronic calculators and clocks to laptop personal computers, word processors, liquid crystal projectors, liquid crystal televisions, car navigation systems, and measuring instruments for indoor or outdoor use, etc.; and its use conditions have been expanded from low temperature to high temperature, from low humidity to high humidity, and from low light amount to high light amount. Under such circumstances, it is desired to develop a polarizing plate having high polarizing performance and excellent durability.

Now, a polarizing film is manufactured by dyeing a polarizing film substrate such as a stretched/oriented film of polyvinyl alcohol or a derivative thereof or a polyene-based film formed by: producing a polyene by removing hydrochloric acid from a polyvinyl chloride film or by removing water from a polyvinyl alcohol-based film, the polyene being oriented with iodine or a dichromatic dye serving as a polarizing element; or by including iodine or a bicolor dye in the polarizing film substrate. Among them, an iodine-based polarizing film using iodine as a polarizing element is excellent in polarizing performance, but is inferior in water resistance and heat resistance, and thus has a problem in durability when it is used under high temperature/high humidity conditions for a long time. In order to improve durability, a treatment using formalin or an aqueous solution containing boric acid, and a method using a polymer film having a low water vapor transmission rate as a protective film have been considered; however, their effects are always insufficient. On the other hand, a dye-based polarizing film using a dichromatic dye as a polarizing element is excellent in moisture resistance and heat resistance as compared with an iodine-based polarizing film, but is generally insufficient in polarizing performance.

In a neutral color polarizing film formed by allowing a polymer film to adsorb several kinds of dichroic dyes and orienting it, if light leakage (color leakage) occurs at a specific wavelength in the visible light wavelength region in a state where two polarizing films are stacked such that their orientation directions intersect perpendicularly (perpendicularly intersecting state), the color tone of a liquid crystal display may sometimes change in a dark state when the polarizing films are mounted in a liquid crystal panel. Then, when a polarizing film is mounted in a liquid crystal display device, in order to prevent the liquid crystal display from discoloring in a dark state due to color leakage at a specific wavelength, in a neutral color polarizing film formed by allowing a polymer film to absorb several kinds of dichroic dyes and orienting it, transmittance in a perpendicular intersecting state (perpendicular intersecting transmittance) in a visible light wavelength region must be uniformly reduced.

Further, in the case of a color liquid crystal projection type display using a polarizing plate for a liquid crystal image forming portion, i.e., a color liquid crystal projector, an iodine-based polarizing plate having satisfactory polarization performance and displaying neutral gray color has been used in the past. However, as described above, since the iodine-based polarizing plate uses iodine as a polarizing element, light resistance, heat resistance, and moist heat resistance are insufficient. This is a problem. To solve this problem, a neutral gray polarizing plate using a dye-based two-color pigment as a polarizer (polarizer) has been started to be used. However, the neutral gray polarizing plate has the following problems. Since the three primary color pigments are generally used in combination in order to uniformly improve transmittance and polarization performance in the entire visible light wavelength region as in the case of a color liquid crystal projector, light transmittance is low with respect to the requirement for improvement in luminance. In order to increase the brightness, the intensity of the light source must be increased. In order to solve this problem, three polarizing plates corresponding to three primary colors, in other words, three polarizing plates for a blue channel, a green channel, and a red channel have been used.

However, the brightness is inevitably reduced due to the fact that light is absorbed by the polarizing plate in a large amount and an image having a size as small as 0.5 to 3 inches is enlarged to about several tens of inches to several hundreds of inches, etc. Therefore, a light source having high luminance is used. In addition, there is still a strong desire to further improve the luminance of liquid crystal projectors. As a result, needless to say, the intensity of the light source used is increasingly stronger, and therefore, light and heat applied to the polarizing plate are also increased.

As the dye used for producing the above dye-based polarizing film, for example, water-soluble azo compounds described in, for example, patent documents 1 to 5 are mentioned.

However, the conventional polarizing plate containing the above water-soluble dye has not yet satisfied the market demand in view of the polarization characteristics, the absorption wavelength region, the color tone, and the like. Further, three polarizing plates corresponding to the three primary colors of a color liquid crystal projector, more specifically, polarizing plates for blue, green, and red channels, having the following properties have not been obtained: satisfactory brightness, polarizing properties, durability under high temperature and high humidity conditions and, in addition, satisfactory light resistance to long-term exposure. Improvements in this are desired.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 2622748

Patent document 2: japanese patent laid-open publication No. 2001-33627

Patent document 3: japanese patent laid-open publication No. 2004-51645

Patent document 4: WO2005/075572 publication

Patent document 5: WO2007/148757 publication

Patent document 6: japanese patent laid-open publication No. 2004-075719

Non-patent document

Non-patent document 1: dye chemistry; thin field with high quality

Disclosure of Invention

Problems to be solved by the invention

An object of the present invention is to provide a high-performance polarizing plate having excellent polarizing performance, moisture resistance, heat resistance and light resistance. Further, another object of the present invention is to provide a neutral-color polarizing plate in which two or more two-color dyes are adsorbed onto a polymer film and are oriented, and which is a high-performance polarizing plate having no color leakage in a state of being crossed perpendicularly in a visible light wavelength region and having excellent polarizing performance, moisture resistance, heat resistance and light resistance.

It is still another object to provide a high-performance polarizing plate corresponding to the three primary colors of a color liquid crystal projector, which is all satisfactory in terms of brightness, polarizing performance, durability, and light resistance.

Means for solving the problems

The present inventors have conducted intensive studies in order to achieve these objects. As a result, it has been found that a polarizing film and a polarizing plate containing a specific azo compound and/or a salt thereof are excellent in polarizing performance, moisture resistance, heat resistance and light resistance. Based on this finding, the present invention has been completed.

More particularly, the present invention relates to

(1) An azo compound represented by the formula (1) or (2) and a salt thereof

Wherein A represents a phenyl group or a naphthyl group each having at least one substituent, R₁～R₄At least one of them is a lower alkoxy group having a sulfo group, the remaining each independently represents a hydrogen atom, a lower alkyl group or a lower alkoxy group, and X represents an amino group which may have a substituent, a benzoylamino group which may have a substituent, a phenylamino group which may have a substituent, a phenylazo group which may have a substituent or a naphthotriazole group which may have a substituent.

(2) The azo compound according to (1) wherein X is a benzoylamino group which may have a substituent, a phenylamino group which may have a substituent, a phenylazo group which may have a substituent or a naphthotriazole group which may have a substituent, and these substituents are a hydrogen atom, a lower alkyl group, a lower alkoxy group, a hydroxyl group, a carboxyl group, a sulfo group, an amino group or a substituted amino group, and a salt thereof.

(3) The azo compound according to (1) or (2) wherein X is a phenylamino group represented by the formula (3), and salts thereof

Wherein R is₅And R₆Each independently represents a hydrogen atom, a methyl group, a methoxy group, a sulfo group, an amino group or a substituted amino group.

(4) The azo compound according to (1) or (2) wherein X is a benzoylamino group represented by the formula (4), and salts thereof

Wherein R is₇Represents a hydrogen atom, a hydroxyl group, an amino group or a substituted amino group.

(5) The azo compound according to (1) or (2) wherein X is a naphthotriazolyl group represented by the formula (5), and a salt thereof

Wherein m represents 1 or 2.

(6) The azo compound according to (1) or (2) wherein X is a phenylazo group represented by the formula (6), and salts thereof

Wherein R is₈～R₁₀Each independently represents a hydrogen atom, a hydroxyl group, a lower alkyl group, a lower alkoxy group, an amino group or a substituted amino group.

(7) The azo compound according to any one of (1) to (6) and a salt thereof, wherein A is a phenyl group or a naphthyl group each having at least one substituent, and at least one of the substituents is a sulfo group or a carboxyl group.

(8) The azo compound according to any one of (3) to (7) wherein A is a phenyl group having two or more substituents, and at least one of the substituents is a sulfo group, and the remaining substituents are a lower alkyl group, a lower alkoxy group, a carboxyl group, a nitro group, an amino group, or a substituted amino group, and a salt thereof.

(9) The azo compound according to any one of (3) to (8) wherein A is represented by the formula (7), and a salt thereof

Wherein R is₁₁And R₁₂One of which is a sulfo group and the other of which represents a sulfo group, a lower alkyl group, a lower alkoxy group, a carboxyl group, an amino group or a substituted amino group.

(10) The azo compound according to any one of (3) to (8) wherein A is represented by the formula (8), and a salt thereof

Wherein R is₁₃Represents a hydrogen atom, a lower alkoxy group having a hydroxyl group or a sulfo group, and n represents 1 to 3.

(11) The azo compound according to any one of (1) to (10) wherein R is₁～R₄At least one of which is a sulfopropoxy group or a sulfobutoxy group, and the remaining are each independently a hydrogen atom, a methyl group or a methoxy group.

(12) A dye-based polarizing film comprising a polarizing film substrate containing the azo compound of any one of (1) to (11) and/or a salt thereof.

(13) A dye-based polarizing film comprising a polarizing film substrate containing the azo compound of any one of (1) to (11) and/or a salt thereof, and at least one organic dye other than the azo compound and/or a salt thereof.

(14) A dye-based polarizing film comprising a polarizing film substrate containing two or more azo compounds and/or salts thereof according to any one of (1) to (11) and at least one organic dye other than the azo compounds and/or salts thereof.

(15) The dye-based polarizing film according to any one of (12) to (14), wherein the polarizing film substrate is a film comprising a polyvinyl alcohol resin or a derivative thereof.

(16) A dye-based polarizing plate obtainable by laminating a transparent protective layer to at least one surface of the dye-based polarizing film according to any one of (12) to (14).

(17) A polarizing plate for liquid crystal displays, which uses the dye-based polarizing film or the dye-based polarizing plate according to any one of (12) to (16).

(18) A color polarizing plate for a liquid crystal projector, which uses the dye-based polarizing film or the dye-based polarizing plate according to any one of (12) to (16).

(19) A liquid crystal display device using the dye-based polarizing plate according to any one of (16) to (18).

Effects of the invention

Since the polarizing film containing the azo compound or salt thereof of the present invention has high polarizing properties comparable to those of polarizing films using iodine and excellent durability, the polarizing film is suitably used for liquid crystal displays and liquid crystal projectors, and further, it is suitably used for in-vehicle applications requiring high polarizing properties and durability and display applications of industrial measuring instruments for various environments.

Detailed Description

The azo compound of the present invention is represented by the above formula (1) or (2). In the formula (1) or (2), A represents phenyl or naphthyl each having a substituent, R₁～R₄At least one of them is a lower alkoxy group having a sulfo group, the remaining each independently represents a hydrogen atom, a lower alkyl group or a lower alkoxy group, and X represents an amino group which may have a substituent, a benzoylamino group which may have a substituent, a phenylamino group which may have a substituent, a phenylazo group which may have a substituent or a naphthotriazole group which may have a substituent. A represents phenyl or naphthyl each having a substituent. As said substituent, selected from sulfoAnd a carboxyl group are preferable. When two or more substituents are present, at least one of the substituents is a sulfo group or a carboxyl group, and the remaining substituents preferably include a hydrogen atom, a lower alkyl group, a lower alkoxy group, a carboxyl group, a nitro group, an amino group, a substituted amino group, and a lower alkoxy group having a hydroxyl group or a sulfo group. In particular, A is more preferably a phenyl group represented by the above formula (7) or a naphthyl group represented by the above formula (8). In the above formula (7), R₁₁And R₁₂One is a sulfo group, and the other is any one of a sulfo group, a lower alkyl group, a lower alkoxy group, a carboxyl group, an amino group, and a substituted amino group; however, it is preferred that R₁₁And R₁₂Are all sulfo groups, or one of them is sulfo and the other is methoxy, carboxy or acetamido, more preferably R₁₁Is a sulfo group. In the above formula (1), R₁～R₄At least one of which is a lower alkoxy group having a sulfo group, and the remainder each independently represents a hydrogen atom, a lower alkyl group or a lower alkoxy group. In the above formula (2), R is shown₁And R₂One is a lower alkoxy group having a sulfo group, and the other is a hydrogen atom, a lower alkyl group or a lower alkoxy group. As the lower alkoxy group having a sulfo group, a sulfopropoxy group or a sulfobutoxy group is preferable, and the other is preferably a hydrogen atom, a methyl group or a methoxy group. As the substitution position, R is particularly preferred₁Is a lower alkoxy group having a sulfo group. X represents a benzoylamino group which may have a substituent, a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, or a naphthotriazole group which may have a substituent. However, in the case where X represents a benzoylamino group which may have a substituent, a phenylamino group which may have a substituent or a phenylazo group which may have a substituent, the substituent is preferably a hydrogen atom, a lower alkyl group, a lower alkoxy group, a hydroxyl group, a carboxyl group, a sulfo group, an amino group or a substituted amino group. In the case of a naphthotriazolyl group which may have a substituent, the substituent thereof is preferably a sulfo group. In the case where X is a phenylamino group which may have a substituent, the substituent is preferably a hydrogen atom, a methyl group, a methoxy group, an amino group, a substituted amino group or a sulfo group. Although the substitution position is not particularly limited, the para position is particularly preferred. In X is a group havingIn the case of a substituted benzoylamino group, the substituent is preferably a hydrogen atom, an amino group, a substituted amino group or a hydroxyl group, and particularly preferably a hydrogen atom or an amino group. In the case where X is a phenylazo group having a substituent, the substituent is preferably a hydroxyl group, an amino group, a methyl group, a methoxy group or a carboxyl group, and particularly preferably a hydroxyl group. The symbol m represents 1 or 2, and n represents any of integers 1 to 3. It should be noted that, herein, the term "lower" of lower alkyl and lower alkoxy means alkyl and alkoxy groups having 1 to 5 carbon atoms.

Next, specific examples of the azo compound represented by formula (1) and used in the present invention will be mentioned below. Note that sulfo, carboxyl and hydroxyl groups in the formula are represented in the form of free acids.

The azo compound represented by formula (1) or a salt thereof can be easily produced by diazotization and coupling known in the art according to a general azo dye production method as described in non-patent document 1. As a specific production method, an aromatic amine represented by the following formula (a) is diazotized and primary-coupled with an aniline compound of the following formula (B), thereby obtaining a monoazo amino compound represented by the following formula (C).

A-NH₂(A)

Wherein A represents the same meaning as A in the formula (1).

Wherein R is₁And R₂Respectively represent R in the formula (1)₁And R₂The same meaning is used.

Wherein R is₁、R₂And A represents R in the formula (1)₁、R₂The same as A.

Next, the monoazo amino compound is diazotized and subjected to secondary coupling with an aniline compound of the following formula (D), thereby obtaining a disazo amino compound represented by the following formula (E).

Wherein R is₃And R₄Respectively represent R in the formula (1)₃And R₄The same meaning is used.

Wherein R is₁、R₂、R₃、R₄And A represents R in the formula (1)₁、R₂、R₃、R₄The same as A.

The bisazo amino compound is diazotized and subjected to tertiary coupling with naphthol represented by the following formula (F), thereby obtaining an azo compound represented by the formula (1).

Wherein X represents the same meaning as X in the formula (1).

In the case of formula (2), formula (C) is diazotized and subjected to tertiary coupling with naphthol represented by the above formula (F), thereby obtaining an azo compound of formula (2).

In the above reaction, the diazotization step is carried out by a cis method in which a nitrite such as sodium nitrite is mixed with a component for diazotization dissolved or suspended in an aqueous solution of an inorganic acid such as hydrochloric acid or sulfuric acid; or by the reverse method in which a nitrite is added to a neutral or weakly alkaline solution of the diazo component and mixed with an inorganic acid. The temperature of diazotization is about-10-40 ℃. Further, the step of coupling with the aniline compound is carried out by mixing an aqueous solution of an acid such as hydrochloric acid or acetic acid with each of the above diazo solutions and reacting them at a temperature of-10 to 40 ℃ under acidic conditions of pH 2 to 7.

The monoazo compound and the disazo compound obtained by coupling are removed by direct filtration or after they are precipitated by acid precipitation or salting out, or the solution or suspension thereof may be directly subjected to the next step. In case the diazonium salt is insoluble and forms a suspension, filtration is performed, obtaining a filter cake (precake) that can be used for the next coupling step.

Performing a tertiary coupling reaction between a diazotized bisazo-amino compound and a naphthol represented by the formula (F) at a temperature of-10 to 40 ℃ under a neutral to alkaline condition of pH 7 to 10. After completion of the reaction, a precipitate was obtained by salting out and taken out by filtration. Further, in the case where purification is required, salting-out may be repeated or precipitation from water may be performed using an organic solvent. Examples of the organic solvent to be used for the purification include water-soluble organic solvents such as alcohols such as methanol and ethanol, and ketones such as acetone.

Note that, in the present invention, the azo compound represented by the formula (1) or (2) is used in the form of a free acid, or can be used in the form of a salt of the azo compound. Examples of such salts include alkali metal salts such as lithium, sodium and potassium salts, ammonium salts, and organic salts such as amine salts. Typically, a sodium salt is used.

The aromatic amine represented by the above formula (a) and serving as a raw material for synthesizing the water-soluble dye represented by the formula (1) or (2) represents a phenyl group or a naphthyl group each having at least one substituent, at least one of which is preferably a substituent selected from a sulfo group and a carboxyl group. In the case where A is a phenyl group having at least one substituent, examples thereof include 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, 3-amino-4-methoxybenzenesulfonic acid, 2-amino-4-nitrobenzenesulfonic acid, 2, 5-diaminobenzenesulfonic acid, 3-acetamido-5-aminobenzenesulfonic acid, 2-amino-4-sulfobenzoic acid, 2-amino-5-sulfobenzoic acid, 4-amino-3-sulfobenzoic acid, and 5-aminoisophthalic acid; however, 4-aminobenzenesulfonic acid, 2-amino-5-methoxybenzenesulfonic acid, 4-amino-2-methylbenzenesulfonic acid, 2-amino-4-sulfobenzoic acid, 3-acetamido-5-aminobenzenesulfonic acid, and 4-amino-3-sulfobenzoic acid are preferred. As a substituent of the phenyl group, a naphthotriazolyl group (represented by the above-mentioned (5)) may be present. Other examples include 6, 8-disulfo-naphthotriazolyl, 7, 9-disulfo-naphthotriazolyl, 7-sulfonaphthotriazolyl and 5-sulfonaphthotriazolyl. In this case, the substituent is particularly preferably present in the para-position to the azo group. In the case where A is a naphthyl group having a sulfo group, examples thereof include 4-aminonaphthalene sulfonic acid, 6-aminonaphthalene-2-sulfonic acid, 5-aminonaphthalene-2-sulfonic acid, 8-aminonaphthalene-2-sulfonic acid, 7-aminonaphthalene-1, 3-disulfonic acid, 6-aminonaphthalene-1, 3-disulfonic acid, 7-aminonaphthalene-1, 5-disulfonic acid, 6-aminonaphthalene-1, 5-disulfonic acid, 7-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, and 7-amino-3- (3-sulfopropoxy) naphthalene-1, 5-disulfonic acid; however, 7-aminonaphthalene-3-sulfonic acid, 6-aminonaphthalene-1, 3-disulfonic acid and 7-amino-3- (3-sulfopropoxy) naphthalene-1-sulfonic acid are preferred.

May have substituents (R) serving as primary and secondary coupling components₁～R₄) At least one of the substituents of the aniline compound of (1) is a lower alkoxy group having a sulfo group, and the remaining substituents each independently represent a hydrogen atom, a lower alkyl group or a lower alkoxy group. As the lower alkoxy group having a sulfo group, 3-sulfopropoxy and 4-sulfobutoxy are preferable. As the remaining substituents, hydrogen atoms, methyl groups and methoxy groups are preferable. These substituents may be combined alone or in a combination of both. The binding position is preferably 2-position relative to the amino group; 3-position; 2-position and 5-position; 3-position and 5-position; or 2-and 6-positions. However, the 3-position is preferred; and 2-and 5-positions. Examples of the aniline compound having a lower alkoxy group containing a sulfo group include 3- (2-amino-4-methylphenoxy) propane-1-sulfonic acid, 3- (3-amino-4-methylphenoxy) propane-1-sulfonic acid, 3- (2-aminophenoxy) propane-1-sulfonic acid and 3- (2-amino-4-methylphenoxy) butane-1-sulfonic acid. Examples of the aniline compounds other than those described above include aniline, 2-methylaniline, 3-methylaniline, 2-ethylaniline, 3-ethylaniline, 2, 5-dimethylaniline, 2, 5-diethylaniline, 2-methoxyaniline, 3-methoxyaniline, 2-methoxy-5-methylaniline, 2, 5-dimethoxyaniline, 3, 5-dimethylanilineAniline, 2, 6-dimethylaniline or 3, 5-dimethoxyaniline. The amino group in these aniline compounds may be protected. As the protective group, for example, an ω -methanesulfonic acid group is mentioned. The aniline compound to be used for the primary coupling and the aniline compound to be used for the secondary coupling may be the same or different.

Examples of X in the naphthol having X as the tertiary coupling component include a benzoylamino group which may have a substituent, a phenylamino group which may have a substituent, a phenylazo group which may have a substituent or a naphthotriazole group which may have a substituent. Examples of the various substituents preferably include a hydrogen atom, a lower alkyl group, a lower alkoxy group, a hydroxyl group, a carboxyl group, a sulfo group or an amino group which may have a substituent.

In the case where X is an optionally substituted phenylamino group, X is preferably optionally substituted (R)₅、R₆) And a phenylamino group represented by formula (3). The substituent (R)₅、R₆) Each independently represents a hydrogen atom, a methyl group, a methoxy group, a sulfo group, an amino group or a substituted amino group; however, a hydrogen atom, a methyl group, a methoxy group or an amino group is more preferable. More preferably, at least one of the substituents is present para to the amino group. Examples thereof include phenylamino, 4-methylphenylamino, 4-methoxyphenylamino, 4-aminophenylamino, 4-amino-2-sulfophenylamino, 4-amino-3-sulfophenylamino, 4-sulfomethylaminophenylamino and 4-carboxyethylaminophenylamino.

In the case where X is a benzoylamino group which may have a substituent, X preferably has a substituent (R)₇) And a benzoylamino group represented by formula (4). The substituent (R)₇) Represents a hydrogen atom, a hydroxyl group, an amino group or a substituted amino group; however, it preferably represents a hydrogen atom, an amino group or an amino group which may have a substituent. The substitution position is more preferably the para position. Examples of the benzoylamino group which may have a substituent include a benzoylamino group, a 4-aminobenzoylamino group, a 4-hydroxybenzoylamino group and a 4-carboxyethylanthylaminobenzoylamino group.

In the case where X is a naphthotriazolyl group which may have a substituent, X is preferably a naphthotriazolyl group having a sulfo group and represented by formula (5). The reference m denotes 1 or 2, preferably 2. Examples thereof include 6, 8-disulfo-naphthotriazolyl, 7, 9-disulfo-naphthotriazolyl, 7-sulfonaphthotriazolyl and 5-sulfonaphthotriazolyl, and 6, 8-disulfo-naphthotriazolyl and 5-sulfonaphthotriazolyl are preferable.

In the case where X is a phenylazo group which may have a substituent, X is preferably a phenylazo group having a substituent (R)₈～R₁₀) And a phenylazo group represented by formula (6). Substituent (R)₈～R₁₀) Each independently represents a hydrogen atom, a hydroxyl group, a lower alkyl group, a lower alkoxy group, an amino group or a substituted amino group; however, the number of substituents is preferably one. As the substituent, a hydroxyl group, an amino group, or a substituted amino group is more preferable. Examples of the phenylazo group which may have a substituent include a 2-methylphenylazo group, a 3-methylphenylazo group, a 2, 5-dimethylphenylazo group, a 3-methoxyphenylazo group, a 2-methoxy-5-methylphenylazo group, a 2, 5-dimethoxyphenylazo group, a 4-aminophenylazo group, a 4-hydroxyphenylazo group and a 4-carboxyethylaminoazo group; however, 4-aminophenylazo, 4-hydroxyphenylazo and 4-carboxyethylaminoazo are preferred.

In the dye-based polarizing film or dye-based polarizing plate of the present invention, the azo compound represented by formula (1) or a salt thereof is used alone or in combination of two or more. Furthermore, more than one other organic dye may be used in combination, if necessary. The organic dyes to be used in combination are not particularly limited; however, a dye having absorption properties in a wavelength region different from the absorption wavelength region of the azo compound of the present invention or a salt thereof and having high dichroism is preferable. Typical examples thereof include c.i. direct yellow 12, c.i. direct yellow 28, c.i. direct yellow 44, c.i. direct orange 26, c.i. direct orange 39, c.i. direct orange 71, c.i. direct orange 107, c.i. direct red 2, c.i. direct red 31, c.i. direct red 79, c.i. direct red 81, c.i. direct red 247, c.i. direct green 80, c.i. direct green 59, and dyes described in patent documents 1 to 5. More preferably, dyes developed for polarizing plates as described in patent documents 1 to 5 are more preferably used according to the purpose. These pigments are used in the form of free acids, alkali metal salts (e.g., Na salts, K salts, Li salts), ammonium salts, and amine salts.

In the case of using another organic dye in combination, when necessary, the type of the dye to be mixed differs depending on the case where the desired polarizing film is a neutral color polarizing film, a color polarizing film for a liquid crystal projector, or other color polarizing film. The mixing ratio thereof is not particularly limited; however, the total amount of the at least one organic dye generally preferably falls within the range of 0.1 to 10 parts by weight based on the weight of the azo compound of formula (1) or a salt thereof.

The polarizing film to be used for the dye-based polarizing film or the color polarizing plate for a liquid crystal projector of the present invention can be produced by adding the azo compound represented by the formula (1) or a salt thereof, if necessary, in combination with another organic dye to a polarizing film material, i.e., a polymer film, by a known method so as to have various types of color tones and neutral colors. The obtained polarizing film was used as a polarizing plate by providing it with a protective film; and, if necessary, the polarizing film is used in a liquid crystal projector, an electronic calculator, a clock, a notebook personal computer, a word processor, a liquid crystal television, a car navigation system, a measuring instrument for indoor or outdoor use, a display, and the like by providing a protective layer or an AR (anti-reflection) layer and a support thereto.

As the polarizing film substrate (polymer film) to be used for the dye-based polarizing film of the present invention, a film formed of a polyvinyl alcohol resin or a derivative thereof is preferably used. Specific examples include polyvinyl alcohol or a derivative thereof, and any of these denatured with an olefin such as ethylene or propylene or an unsaturated carboxylic acid such as crotonic acid, acrylic acid, methacrylic acid, or maleic acid. Among them, a film formed of polyvinyl alcohol or a derivative thereof is suitably used in view of the adsorption property and the orientation of the dye. The thickness of the substrate is usually 30 to 100 μm, preferably about 50 to 80 μm.

When the azo compound of formula (1) and/or a salt thereof is added to such a polarizing film substrate (polymer film), a method of dyeing the polymer film is generally employed. For example, dyeing is performed as follows. First, the azo compound of the present invention and/or a salt thereof, and if necessary, a dye other than these are dissolved in water to prepare a dyeing bath. The dye concentration in the dyeing bath is not particularly limited; however, it is generally selected from the range of about 0.001 to 10 wt%. In addition, a dyeing assistant may be used if necessary. For example, mirabilite is suitably used at a concentration of about 0.1 to 10 wt%. In the dyeing bath thus prepared, the polymer film is soaked for 1 to 10 minutes to dye the film. The dyeing temperature is preferably about 40 to 80 ℃.

The orientation of the azo compound of the formula (1) and/or a salt thereof is carried out by stretching the polymer film dyed as described above. As the stretching method, for example, any of known methods such as a wet method and a dry method can be used. When desired, the polymer film may be stretched prior to dyeing. In this case, the water-soluble dye is oriented during dyeing. If necessary, post-treatment such as boric acid treatment is applied to the water-soluble dye-containing and oriented polymer film by a known method. This post-treatment is performed in order to improve the beam transmittance and the degree of polarization of the polarizing film. The conditions of the boric acid treatment vary depending on the type of polymer film and the type of dye used; however, the boric acid concentration of the aqueous boric acid solution is usually set in the range of 0.1 to 15 wt%, preferably in the range of 1 to 10 wt%, and the treatment is performed by soaking in the temperature range of 30 to 80 ℃, preferably in the temperature range of 40 to 75 ℃ for 0.5 to 10 minutes. Furthermore, if necessary, the fixation treatment may be carried out simultaneously in an aqueous solution containing the cationic-based polymer.

A transparent protective film having excellent optical transparency and mechanical strength is attached to one or both surfaces of the dye-based polarizing film of the present invention thus obtained using an adhesive, thereby forming a polarizing plate. Examples of the material for forming the protective film include cellulose acetate-based films and acrylic films, and also include fluorine-based films such as films of tetrafluoroethylene/hexafluoropropylene-based copolymers, and films formed of polyester resins, polyolefin resins, polyamide-based resins, or the like. Preferably, a triacetyl cellulose (TAC) film and a cycloolefin-based film are used. The thickness of the protective film is usually 40 to 200 μm.

Examples of the adhesive to be used for attaching the polarizing film and the protective film include a polyvinyl alcohol-based adhesive, a polyurethane emulsion-based adhesive, an acrylic adhesive, and a polyester-isocyanate-based adhesive. Polyvinyl alcohol-based adhesives are suitable.

A transparent protective layer may be additionally provided to the surface of the dye-based polarizing plate of the present invention. Examples of the protective layer include an acrylic polysiloxane-based hard coat layer and a polyurethane-based protective layer. In addition, in order to further improve the single-plate light transmittance, an AR layer is preferably provided on the protective layer. The AR layer may be formed, for example, by deposition or sputtering of a substance such as silicon dioxide, titanium dioxide, or by applying a thin coating of a fluorine-based substance. It is to be noted that the dye-based polarizing plate of the present invention can be used as an elliptical polarizing plate having a phase difference plate attached thereto.

The dye-based polarizing plate of the present invention thus constituted is characterized in that: it has a neutral color; no color leakage in a vertically crossed state in a visible light wavelength region; the polarizing film has excellent polarizing performance; in addition, it does not cause discoloration and does not cause a decrease in polarization performance even under high temperature/high humidity conditions; and less light leakage in the visible light region in a vertically crossed state.

The color polarizing plate for a liquid crystal projector in the present invention contains the azo compound represented by formula (1) and/or a salt thereof as a two-color molecule, and if necessary, other organic dyes as described above. Further, the polarizing film to be used for the color polarizing plate for liquid crystal projectors of the present invention is also manufactured by the method described in the section describing the manufacturing method of the dye-based polarizing film of the present invention, and is further used as a polarizing plate by providing it with a protective film, and is used as a color polarizing plate for liquid crystal projectors by providing it with a protective layer or an AR layer and a support or the like, when necessary.

In a necessary wavelength region of a polarizing plate (A. when an ultra-high pressure mercury lamp is used, 420-500 nm for a blue channel, 500-580 nm for a green channel, and 600-680 nm for a red channel, and B. when a three-color LED lamp is used, 430-450 nm for a peak wavelength of the blue channel, 520-535 nm for the green channel, and 620-635 nm for the red channel), an average light transmittance of a single plate of the color polarizing plate for a liquid crystal projector is 39% or more and an average light transmittance in a state of vertical crossing is 0.4% or less. More preferably, the polarizing plate has an average single-plate transmittance of 41% or more and an average transmittance in a vertically crossed state of 0.3% or less, more preferably 0.2% or less, in a wavelength region necessary for the polarizing plate. Further preferably, the polarizing plate has an average single-plate transmittance of 42% or more and an average transmittance of 0.1% or less in a perpendicular crossing state in a wavelength region required for the polarizing plate. As described above, the color polarizing plate for a liquid crystal projector in the present invention has brightness and excellent polarization performance.

The color polarizing plate for a liquid crystal projector of the present invention is preferably composed of a polarizing plate composed of a polarizing film and a protective film, and an AR layer provided thereon. In short, a polarizing plate with an AR layer is preferable. Further, it is preferably attached to a support such as a transparent glass plate, and in short, a polarizing plate with an AR layer and a support is more preferable.

It should be noted that the single-plate average light transmittance is an average value of the light beam transmittance in a specific wavelength region when natural light is incident on a single polarizing plate (hereinafter, if simply referred to as a polarizing plate, the same definition is used) on which neither an AR layer nor a support such as transparent glass is provided. The average light transmittance in the state of perpendicular crossing is an average light beam transmittance value in a specific wavelength region when natural light is incident on two polarizing plates arranged with the alignment directions perpendicularly crossing.

The color polarizing plate for a liquid crystal projector of the present invention is generally used in the form of a polarizing plate with a support. The support preferably has a flat portion for attaching the polarizing plate. Further, for optical applications, glass shaped products are preferred. Examples of the glass shaped product include a glass plate, a lens, and a prism (e.g., a triangular prism, a cubic prism). A lens having a polarizing plate attached thereto can be used as a condenser lens provided with a polarizing plate in a liquid crystal projector. In addition, a prism to which a polarizing plate is attached can be used as a polarizing beam splitter with a polarizing plate and a dichroic prism with a polarizing plate in a liquid crystal projector. In addition, a polarizing plate may be attached to the liquid crystal cell. Examples of the material for the glass include inorganic glasses such as soda glass, borosilicate glass, and sapphire glass, and organic glasses such as acrylates and polycarbonates; however, inorganic glasses are preferred. The thickness and size of the glass sheet can be set as desired. In addition, for a polarizing plate with glass, in order to improve single-plate light transmittance, an AR layer is preferably provided on one or both surfaces of the glass surface or the polarizing plate surface.

To manufacture a color polarizing plate with a support for a liquid crystal projector, for example, a transparent adhesive (sticker) is applied to a flat portion of the support, and then, the dye-based polarizing plate of the present invention may be attached to the coated surface. Further, a transparent adhesive (tacky agent) is applied to the polarizing plate, and then, a support may be attached to the coated surface. As the adhesive (sticker) used herein, for example, an acrylate-based adhesive is preferable. Note that when a polarizing plate is used as the elliptically polarizing plate, adhesion is generally performed so that the phase difference plate side faces the support; however, the adhesion may be performed so that the polarizer side may face the glass shaped product.

More specifically, in a color liquid crystal projector using the dye-based polarizing plate of the present invention, the dye-based polarizing plate of the present invention is disposed on either or both of the incident side and the exit side of the liquid crystal cell. The polarizer may be disposed in contact with the liquid crystal cell or not; however, the polarizer is preferably not in contact with the liquid crystal cell in view of durability. When the polarizing plate is placed in contact with a liquid crystal cell on the exit side, the dye-based polarizing plate of the present invention using the liquid crystal cell as a support can be used. When the polarizer is disposed so as not to be in contact with the liquid crystal cell, the dye-based polarizer of the present invention using a support other than the liquid crystal cell is preferably used. Further, the dye-based polarizing plate of the present invention is preferably disposed on both the incident side and the exit side of the liquid crystal cell in view of durability. Further, it is preferable to arrange the dye-based polarizer of the present invention such that the polarizer surface thereof is close to the liquid crystal cell and the support surface is close to the light source. Note that the incident side of the liquid crystal cell refers to the light source side, and the other side thereof refers to the exit side.

A color liquid crystal projector using the dye-based polarizing plate of the present invention preferably has a UV ray cut filter between the light source and the above-described polarizing plate provided with a support on the incident side. Further, the liquid crystal cell to be used is preferably, for example, an active matrix type liquid crystal cell formed by enclosing liquid crystal in a space between a transparent substrate in which an electrode and a TFT are formed and a transparent substrate in which a counter electrode is formed. Light emitted from a light source such as an ultra-high pressure mercury lamp (UHP lamp), a metal halide lamp, or a white LED passes through a UV ray cut filter, is separated into three colors, then passes through color polarizing plates provided with supports for blue, green, and red channels, respectively, after which the three colors are combined into one, is enlarged by a projection lens, and is projected onto a screen. Alternatively, the following methods are also known: light beams respectively emitted from the blue, green, and red LEDs pass through color polarizing plates provided with supports for blue, green, and red channels, respectively, and are combined into one kind, enlarged by a projection lens, and projected onto a screen.

The color polarizing plate for a liquid crystal projector thus configured is characterized by having excellent polarization performance and not causing discoloration or degradation of polarization performance even under high temperature/high humidity conditions.

Examples

The present invention will be explained more specifically by examples. These examples are only examples and do not limit the present invention. In the examples,% and parts are on a weight basis unless otherwise specified.

Example 1

4- (4' -aminophenyl) -azobenzenesulfonic acid (27.7 parts) was added to water (500 parts) and dissolved with sodium hydroxide. 35% hydrochloric acid (32 parts) was added, followed by sodium nitrite (6.9 parts) and the resulting mixture was stirred for one hour. To this was added dropwise a solution containing 24.5 parts of a compound of the following formula (38) described in example 1 of patent document 6. Completing the coupling at pH 3-4, and crystallizing by using sodium chloride to obtain the disazo compound represented by the following formula (39).

To the obtained disazo compound, 35% hydrochloric acid (32 parts) was added, followed by sodium nitrite (6.9 parts), and the resulting mixture was stirred at 25 to 30 ℃ for 2 hours, thereby performing diazotization. On the other hand, 6- (4' -aminobenzoyl) amino-1-naphthol-3-sulfonic acid (31.0 parts) was added to water (200 parts) and dissolved under weakly alkaline conditions with sodium carbonate. And (3) while keeping the pH value of 8-10, pouring a diazotized diazo compound obtained in advance into the solution, and stirring the obtained mixture to complete the coupling reaction. Salting out was performed with sodium chloride and filtration was performed to obtain a trisazo compound (45 parts) represented by the above formula (9). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution is 575 nm.

Example 2

4-Aminobenzenesulfonic acid (18.3 parts) was added to water (500 parts), dissolved with sodium hydroxide and cooled. 35% hydrochloric acid (32 parts) was added at 10 ℃ or lower, followed by sodium nitrite (6.9 parts), and the resulting mixture was stirred at 5 to 10 ℃ for one hour. To this was added dropwise a solution containing a compound of the above formula (38) (24.5 parts). Completing the coupling at a pH of 3-4 to obtain a solution containing a monoazo compound of the following formula (40).

To the obtained monoazo solution was added 35% hydrochloric acid (32 parts) again, followed by sodium nitrite (6.9 parts), and the resulting mixture was stirred at 25 to 30 ℃ for 2 hours, thereby performing diazotization. To this was added 2, 5-dimethylaniline (12.1 parts) and sodium carbonate to adjust the pH to 3, thereby completing the coupling. From the resulting solution, a precipitate was obtained by salting out with sodium chloride, and was filtered, thereby obtaining a bisazo compound of the following formula (41).

Diazotization, coupling and crystallization were carried out in the same manner as in example 1 except that the obtained disazo compound (41) was used in place of the compound (39), thereby obtaining a trisazo compound (46.0 parts) represented by the above formula (10). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution is 568 nm.

Example 3

4-Aminobenzenesulfonic acid (18.3 parts) was added to water (500 parts), dissolved with sodium hydroxide and cooled. 35% hydrochloric acid (32 parts) was added at 10 ℃ or lower, followed by sodium nitrite (6.9 parts), and the resulting mixture was stirred at 5 to 10 ℃ for one hour. To this was added a solution containing a compound represented by the following formula (42) (23 parts). Completing the coupling at a pH of 3-4 to obtain a solution containing a monoazo compound of the following formula (43).

Diazotization, coupling and crystallization were carried out in the same manner as in example 2 except that the obtained monoazo compound (43) was used in place of the compound (40), thereby obtaining a disazo compound, which was then diazotized, coupled and crystallized in the same manner as in example 2, thereby obtaining a trisazo compound (40 parts) represented by the above formula (11). The maximum absorption wavelength of this compound in a 20% aqueous solution of pyridine was 566 nm.

Example 4

6- (4' -methoxyphenyl) amino-1-naphthol-3-sulfonic acid (34.5 parts) was added to water (200 parts) and dissolved under weakly alkaline conditions with sodium carbonate. While maintaining the pH of 8 to 10, the diazotized solution of the disazo compound used in example 3 was added to the solution and stirred to complete the coupling reaction. Salting out was performed with sodium chloride and filtration was performed to obtain a trisazo compound (37 parts) represented by the above formula (12). The maximum absorption wavelength of this compound in a 20% aqueous solution of pyridine was 580 nm.

Example 5

A disazo compound of the following formula (44) was obtained in the same manner as in example 2, except that 2-amino-5-methoxybenzenesulfonic acid (20.9 parts) was used in place of the starting 4-aminobenzenesulfonic acid (18.3 parts).

Diazotization, coupling and crystallization were carried out in the same manner as in example 4 except that the obtained disazo compound (44) was used in place of the above formula (43), thereby obtaining a trisazo compound (30 parts) represented by the above formula (13). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution is 580 nm.

Example 6

6-phenylamino-1-naphthol-3-sulfonic acid (31.5 parts) is added to water (200 parts) and dissolved under weakly basic conditions with sodium carbonate. To the solution was added a diazotized solution obtained by diazotizing the disazo compound of the above formula (44) in the same manner as in example 2 to maintain pH 8 to 10 and to stir it, thereby completing the coupling reaction. Salting out was performed with sodium chloride and filtration was performed to obtain a trisazo compound (43 parts) represented by the above formula (14). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution is 577 nm.

Example 7

2-amino-5-methoxybenzenesulfonic acid (20.9 parts) was added to water (500 parts), dissolved with sodium hydroxide, and cooled. 35% hydrochloric acid (32 parts) was added at 10 ℃ or lower, followed by sodium nitrite (6.9 parts), and the resulting mixture was stirred at 5 to 10 ℃ for one hour. A solution containing a compound represented by the following formula (45) (24.5 parts) was added dropwise thereto, and coupling was completed at pH 3 to 4, thereby obtaining a solution containing a monoazo compound of the following formula (46).

To the obtained monoazo solution was added 35% hydrochloric acid (32 parts) again, followed by sodium nitrite (6.9 parts), and stirred at 25 to 30 ℃ for 2 hours to perform diazotization. To this was added 2, 5-dimethylaniline (12.1 parts) and sodium carbonate, and the coupling was completed by adjusting the pH to 3. From the resulting solution, a precipitate was obtained by salting out with sodium chloride, and was filtered, thereby obtaining a bisazo compound of the following formula (47).

6- (4' -methoxyphenyl) amino-1-naphthol-3-sulfonic acid (34.5 parts) was added to water (200 parts) and dissolved under weakly alkaline conditions with sodium carbonate. To the solution was added a diazotized solution obtained by diazotizing the disazo compound of the above formula (47) in the same manner as in example 2 to maintain pH 8 to 10 and to stir it, thereby completing the coupling reaction. Salting out was performed with sodium chloride and filtration was performed to obtain a trisazo compound (37 parts) represented by the above formula (15). The maximum absorption wavelength of the compound in a 20% aqueous solution of pyridine was 581 nm.

Example 8

2-amino-5-methoxybenzenesulfonic acid (20.9 parts) was added to water (500 parts), dissolved with sodium hydroxide, and cooled. 35% hydrochloric acid (32 parts) was added at 10 ℃ or lower, followed by sodium nitrite (6.9 parts), and the resulting mixture was stirred at 5 to 10 ℃ for one hour. To this was added 2, 5-dimethylaniline (12.1 parts) and sodium carbonate, and the coupling was completed by adjusting the pH to 3. The obtained monoazo compound was diazotized and coupled with the above formula (38) according to example 1, to obtain a disazo compound of the following formula (48).

6-phenylamino-1-naphthol-3-sulfonic acid (31.5 parts) is added to water (200 parts) and dissolved under weakly basic conditions with sodium carbonate. While maintaining the pH of 8 to 10, a diazotized solution obtained by diazotizing the disazo compound of the above formula (48) in the same manner as in example 2 was added to the solution and stirred, thereby completing the coupling reaction. Salting out was performed with sodium chloride and filtration was performed to obtain a trisazo compound (33 parts) represented by the above formula (16). The maximum absorption wavelength of the compound in a 20% aqueous solution of pyridine was 581 nm.

Example 9

The monoazo compound of the above formula (46) was diazotized and coupled with the above formula (38) according to example 1, to obtain a disazo compound of the following formula (49).

6-phenylamino-1-naphthol-3-sulfonic acid (31.5 parts) is added to water (200 parts) and dissolved under weakly basic conditions with sodium carbonate. While maintaining the pH of 8 to 10, a diazotized solution of the disazo compound of the above formula (49) obtained in the same manner as in example 2 was added to the solution and stirred, thereby completing the coupling reaction. Salting out was performed with sodium chloride and filtration was performed to obtain a trisazo compound (28 parts) represented by the above formula (17). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution is 590 nm.

Example 10

2-amino-5-methoxybenzenesulfonic acid (20.9 parts) was added to water (500 parts), dissolved with sodium hydroxide, and cooled. 35% hydrochloric acid (32 parts) was added at 10 ℃ or lower, followed by sodium nitrite (6.9 parts), and the resulting mixture was stirred at 5 to 10 ℃ for one hour. A solution containing a compound represented by the following formula (50) (24.5 parts) was added dropwise thereto, and coupling was completed at pH 3 to 4, thereby obtaining a solution containing a monoazo compound of the following formula (51).

To the obtained monoazo solution was added 35% hydrochloric acid (32 parts) again, followed by addition of sodium nitrite (6.9 parts) again, and stirring was performed at 25 to 30 ℃ for 2 hours, thereby performing diazotization. To this was added 2, 5-dimethylaniline (12.1 parts) and sodium carbonate, and the coupling was completed by adjusting the pH to 3. From the resulting solution, a precipitate was obtained by salting out with sodium chloride, and was filtered, thereby obtaining a bisazo compound of the following formula (52).

6- (4' -methoxyphenyl) amino-1-naphthol-3-sulfonic acid (34.5 parts) was added to water (200 parts) and dissolved under weakly alkaline conditions with sodium carbonate. While maintaining the pH of 8 to 10, a diazotized solution obtained by diazotizing the disazo compound of the above formula (52) in the same manner as in example 2 was added to the solution and stirred, thereby completing the coupling reaction. Salting out was performed with sodium chloride and filtration was performed to obtain a trisazo compound (33 parts) represented by the above formula (18). The maximum absorption wavelength of this compound in 20% aqueous pyridine solution was 578 nm.

2-amino-5-methoxybenzenesulfonic acid (20.9 parts) was added to water (500 parts), dissolved with sodium hydroxide, and cooled. 35% hydrochloric acid (32 parts) was added at 10 ℃ or lower, followed by sodium nitrite (6.9 parts), and the resulting mixture was stirred at 5 to 10 ℃ for one hour. To this was added 2, 5-dimethylaniline (12.1 parts) and sodium carbonate, and the coupling was completed by adjusting the pH to 3. The obtained monoazo compound was diazotized and coupled with the above formula (50) according to example 1, to obtain a disazo compound of the following formula (53).

6- (4' -methoxyphenyl) amino-1-naphthol-3-sulfonic acid (34.5 parts) was added to water (200 parts) and dissolved under weakly alkaline conditions with sodium carbonate. While maintaining the pH of 8 to 10, a diazotized solution obtained by diazotizing the disazo compound of the above formula (53) in the same manner as in example 2 was added to the solution and stirred, thereby completing the coupling reaction. Salting out was performed with sodium chloride and filtration was performed to obtain a trisazo compound (36 parts) represented by the above formula (19). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution is 584 nm.

Example 12

A trisazo compound represented by the above formula (20) (30 parts) was obtained in the same manner as in example 7, except that 4-amino-3-sulfobenzoic acid (21.7 parts) was used in place of the starting material 2-amino-5-methoxybenzenesulfonic acid (20.9 parts). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution was 582 nm.

Example 13

5-acetylamino-2-aminobenzenesulfonic acid (18.9 parts) was added to water (500 parts), dissolved with sodium hydroxide and cooled. 35% hydrochloric acid (32 parts) was added at 10 ℃ or lower, followed by sodium nitrite (6.9 parts), and the resulting mixture was stirred at 5 to 10 ℃ for one hour. A solution containing a compound represented by the above formula (38) (24.5 parts) was added dropwise thereto, and coupling was completed at pH 3 to 4, thereby obtaining a solution containing a monoazo compound of the following formula (54).

To the obtained monoazo solution was added 35% hydrochloric acid (32 parts) again, followed by addition of sodium nitrite (6.9 parts) again, and stirring was performed at 25 to 30 ℃ for 2 hours, thereby performing diazotization. 3-methylaniline (10.7 parts) and sodium carbonate were added thereto, and coupling was accomplished by adjusting the pH to 3. From the resulting solution, a precipitate was obtained by salting out with sodium chloride, and was filtered, thereby obtaining a bisazo compound of the following formula (55).

6- (4 '-amino-3' -sulfophenyl) amino-1-naphthol-3-sulfonic acid (41.0 parts) was added to water (200 parts) and dissolved under weakly alkaline conditions with sodium carbonate. While maintaining the pH of 8 to 10, a diazotized solution obtained by diazotizing the disazo compound of the above formula (55) in the same manner as in example 2 was added to the solution and stirred, thereby completing the coupling reaction. Salting out was performed with sodium chloride and filtration was performed to obtain a trisazo compound (18 parts) represented by the above formula (21). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution was 572 nm.

Example 14

To 10 parts of compound (21), water (200 parts) and sodium hydroxide (8 parts) were added, and the resulting mixture was stirred at 80 ℃ for 2 hours. Then, salting out was performed with sodium chloride and filtration was performed to obtain a trisazo compound (7 parts) represented by the above formula (22). The maximum absorption wavelength of this compound in 20% aqueous pyridine solution was 578 nm.

Example 15

A trisazo compound represented by the above formula (23) (30 parts) was obtained in the same manner as in example 13, except that 2-amino-5-nitrobenzenesulfonic acid (20.8 parts) was used in place of the raw material 5-acetylamino-2-aminobenzenesulfonic acid (18.9 parts). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution was 582 nm.

Example 16

6-methylamino-1-naphthol-3-sulfonic acid (25.3 parts) was added to water (200 parts) and dissolved under weakly alkaline conditions with sodium carbonate. While maintaining the pH of 8 to 10, a diazotized solution obtained by diazotizing the disazo compound of the above formula (55) in the same manner as in example 2 was added to the solution and stirred, thereby completing the coupling reaction. Salting out was performed with sodium chloride and filtration was performed to obtain a trisazo compound (33 parts) represented by the above formula (24). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution is 562 nm.

Example 17

A trisazo compound represented by the above formula (25) (44 parts) was obtained in the same manner as in example 6, except that 4-amino-2-methylbenzenesulfonic acid (19.7 parts) was used in place of the starting material 2-amino-5-methoxybenzenesulfonic acid (20.9 parts). The maximum absorption wavelength of this compound in 20% aqueous pyridine solution was 578 nm.

Example 18

A trisazo compound represented by the above formula (26) (49 parts) was obtained in the same manner as in example 5, except that 5-aminoisophthalic acid (18.1 parts) was used in place of the raw material 2-amino-5-methoxybenzenesulfonic acid (20.9 parts). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution is 580 nm.

Example 19

A trisazo compound represented by the above formula (27) (49 parts) was obtained in the same manner as in example 5, except that 5-amino-2- (6, 8-disulfo-2H-naphthotriazol-2-yl) benzoic acid (43 parts) was used in place of the starting material 2-amino-5-methoxybenzenesulfonic acid (20.9 parts). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution was 582 nm.

Example 20

A trisazo compound represented by the above formula (28) (44 parts) was obtained in the same manner as in example 6, except that 6-aminonaphthalene-1, 3-disulfonic acid (30.2 parts) was used in place of the starting material, 2-amino-5-methoxybenzenesulfonic acid (20.9 parts). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution is 579 nm.

Example 21

A trisazo compound represented by the above formula (29) was obtained in the same manner as in example 13, except that 7-aminonaphthalene-1, 3-disulfonic acid (30.2 parts) was used in place of the starting material 2-amino-5-methoxybenzenesulfonic acid (20.9 parts) and the secondary coupling agent was changed from 3-methylaniline to 2, 5-dimethylaniline. The maximum absorption wavelength of this compound in 20% aqueous pyridine solution was 585 nm.

Example 22

A trisazo compound was obtained in the same manner as in example 6 except that the monoazo compound represented by the compound (22) described in example 1 of patent document 6 was heated to 75 ℃, and sodium hydroxide was added to obtain 5 wt% and stirring was performed for one hour. Thereafter, neutralization was performed to pH 8 with hydrochloric acid and crystallization was performed with sodium chloride, thereby obtaining a trisazo compound (20 parts) represented by the above formula (30). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution is 596 nm.

Example 23

A trisazo compound represented by the above formula (31) was obtained in the same manner as in example 5, except that 6-amino-3- (3-sulfopropoxy) naphthalene-1-sulfonic acid (36.1 parts) was used in place of the starting material 2-amino-5-methoxybenzenesulfonic acid (20.9 parts). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution is 590 nm.

Example 24

A trisazo compound represented by the above formula (33) was obtained in the same manner as in example 5, except that 2-amino-5- (3-sulfopropoxy) naphthalene-1, 7-disulfonic acid (44.1 parts) was used in place of the starting material 2-amino-5-methoxybenzenesulfonic acid (20.9 parts). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution is 586 nm.

Example 25

A trisazo compound represented by the above formula (34) was obtained in the same manner as in example 24, except that the secondary coupling agent of the compound of the formula (33) was changed from 2, 5-dimethylaniline (12.1 parts) to 2, 5-dimethoxyaniline (15.3 parts). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution is 623 nm.

Example 26

A trisazo compound represented by the above formula (35) was obtained in the same manner as in example 24, except that the final coupling agent of the compound of the above formula (34) was changed from 6- (4' -methoxyphenyl) amino-1-naphthol-3-sulfonic acid (34.5 parts) to 2- (5-hydroxy-7-sulfonaphthalen-2-yl) -2H-naphthotriazole-6, 8-disulfonic acid (55.0 parts). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution is 557 nm.

Example 27

A trisazo compound represented by the above formula (36) was obtained in the same manner as in example 24, except that the secondary coupling agent of the compound of the above formula (35) was changed from 2, 5-dimethylaniline (12.1 parts) to 2-methoxy-5-methylaniline (13.7 parts). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution is 596 nm.

Example 28

A trisazo compound represented by the above formula (37) was obtained in the same manner as in example 24, except that the final coupling agent of the compound of the above formula (34) was replaced with 6- (4 '-methoxyphenyl) amino-1-naphthol-3-sulfonic acid (34.5 parts) to 6- (4' -hydroxyphenylazo) -1-naphthol-3-sulfonic acid (34.4 parts). The maximum absorption wavelength of the compound in a 20% pyridine aqueous solution is 606 nm.

Example 29

Polyvinyl alcohol having a thickness of 75 μm was soaked in an aqueous solution (45 ℃ C.) containing the dye (concentration: 0.03%) of the compound (9) obtained in example 1 and mirabilite (concentration: 0.1%) for 4 minutes. The film was stretched to 5 times in 3% boric acid in water at 50 ℃. While being kept taut, the film was washed with water and dried, thereby obtaining a polarizing film.

The maximum absorption wavelength of the obtained polarizing film is 585nm, and the polarization rate is as high as 99.9%.

Examples 30 to 57

Similarly to the case of the compound (9), a polarizing film was obtained in the same manner as in example 29 using the azo compounds described in examples 2 to 28. The maximum absorption wavelength and the polarization ratio of the obtained polarizing film are shown in table 1. As shown in table 1, the polarizing films formed by using these compounds have high polarization ratios.

TABLE 1

EXAMPLES maximum absorption wavelength (nm) polarization ratio (%)

Compound 58599.9 of formula (9) 29

Compound 56299.9 of formula (10) 30

31 Compound 55899.9 of formula (11)

32 Compound 58699.9 of formula (12)

33 Compound 58699.9 of formula (13)

34 Compound 57599.9 of formula (14)

35 Compound 58499.9 of formula (15)

36 Compound 59399.9 of formula (16)

Compound 59399.9 of formula (17) 37

Compound 59099.9 of formula (18)

39 Compound 58899.9 of formula (19)

Compound 58699.9 of formula 40 (20)

41 Compound 58499.9 of formula (21)

Compound 59199.9 of formula (22) 42

43 Compound 59099.9 of formula (23)

44 Compound 55899.9 of formula (24)

Compound 57799.9 of formula (25)

Compound 58999.9 of formula (26)

Compound 59199.9 of formula (27)

Compound 57899.9 of formula 48 (28)

Compound 59399.9 of formula (29)

Compound 60199.9 of formula 50 (30)

Compound 58799.9 of formula (31) 51

52 Compound 58099.9 of formula (32)

53 Compound 58299.9 of formula (33)

54 Compound 63199.9 of formula (34)

Compound 55799.9 of formula (35) 55

56 Compound 59399.9 of formula (36)

57 Compound 60899.9 of formula (37)

Examples 58 and 59

On both surfaces of each of the polarizing films obtained in example 29 and example 30, triacetyl cellulose films (TAC films; manufactured by Fuji Photo film co., Ltd; trade name TD-80U) were laminated with an aqueous polyvinyl alcohol solution serving as an adhesive, and bonded to glass with an adhesive, thereby obtaining polarizing plates. The polarizing plate was irradiated with light for 432 hours by an accelerated xenon lamp tester (accelerated xenon lamp tester manufactured by Wacom corporation), and the change in the polarization ratio before and after the irradiation with light was measured. The rate of change of the polarization rate was calculated by the following formula

{ (polarization ratio before irradiation) - (polarization ratio after irradiation) }/(polarization ratio before irradiation).

As a result, they were 0.6% and 0.8%, showing excellent durability.

Comparative example 1

A polarizing film was formed in the same manner as in example 20 using the following compound (56) described in example 1 of patent document 2 in place of the compound (9) of example 1, and laminated in the same manner as in example 39, thereby obtaining a polarizing plate. The polarizing plate was irradiated with light for 432 hours by an acceleration xenon lamp tester (acceleration xenon lamp tester manufactured by Wacom corporation), and the change in the polarization ratio before and after the irradiation with light was measured. In the same manner, the rate of change in the polarization rate was calculated. As a result, the change rate was 4.5%, which was lower than the polarizing plates of examples 39 and 40. The durability is poor.

Examples 60 to 67

Using the polarizing films obtained in examples 33, 35, 41, 46, 47, 49, 52, and 53, in the same manner as in example 58, a polarizing plate was formed. The polarizing plate was irradiated with light for 200 hours by an accelerated xenon lamp tester (SX-75 manufactured by Shiga Seiki Co., Ltd.), and the change in the polarization ratio before and after the light irradiation was measured. The rate of change of the polarization rate was calculated by the following formula

{ (polarization ratio before irradiation) - (polarization ratio after irradiation) }/(polarization ratio before irradiation).

As a result, the rate of change is as shown in table 2, showing excellent durability.

TABLE 2

Examples rate of change in polarization ratio of polarizing film (%)

60 polarizing film of example (33) 1.8%

61 polarizing film of example (35) 1.7%

62 polarizing film of example (41) 2.0%

63 polarizing film of example (46) 0.9%

64 polarizing film of example (47) 2.5%

65 polarizing film of example (49) 2.0%

66 polarizing film of example (52) 0.6%

67 polarizing film of example (53) 0.8%

Comparative example 2 polarizing film of comparative example 2 4.4%

Comparative example 2

The same procedure was repeated using the compound (41) of example 7 of patent document 5 instead of the compound of example 33, thereby obtaining a polarizing film, which was laminated in the same manner as in example 33. Light irradiation was carried out for 200 hours by an accelerated xenon lamp tester (SX-75 manufactured by Shiga Seiki Co., Ltd.). The change in the degree of polarization before and after light irradiation was 4.4%. The durability was significantly reduced compared to the compounds of the examples.

Example 68

A polarizing film was formed in the same manner as in example 20, except that the compound (13) obtained in example 5 and an aqueous solution (45 ℃) containing a dye (concentration: 0.2%), c.i. direct orange 39 (concentration: 0.07%), c.i. direct red 81 (concentration: 0.02%) and mirabilite (concentration: 0.1%) were used. On one surface of the obtained polarizing Film, a TAC Film (Film thickness: 80 μm, trade name TD-80U, manufactured by Fuji Photo Film co.ltd.) was attached, and on the other surface, a Film having a UV (ultraviolet) hardening hard coat layer (about 10 μm) formed on one surface of the TAC Film was attached using a PVA-based adhesive, thereby obtaining a polarizing plate of the present invention. On one surface of the polarizer, an acrylate-based adhesive was coated, thereby obtaining an adhesive-carrying polarizer. Further, an AR (anti-reflection) multilayer coating was applied to the outside of the hard coat layer by vacuum deposition, and it was cut into pieces having a size of 30mm × 40mm, and attached to a glass plate of the same size having a transparent AR layer on one surface, thereby obtaining a polarizing plate of the present invention provided with an AR support (liquid crystal projector for green channel). The polarizing plate of this example, that is, the polarizing plate of the present invention (liquid crystal projector for green channel) had a maximum absorption wavelength (λ max) of 570nm and an average transmittance of the single plate at 500 to 580nm of 45%, and an average transmittance in a state of perpendicular intersection of 0.02%, and had a high degree of polarization. The polarizing plate of this example has high polarization rate and durability even under high temperature and high humidity conditions for a long time. In addition, the polarizing plate is excellent in light resistance to long-time exposure.

Industrial applicability

The azo compound of the present invention and a salt thereof can be suitably used as a raw material for a polarizing plate.

Claims (13)

1. An azo compound represented by the formula (1) and a salt thereof

Wherein A is represented by the formula (8)

Wherein R is₁₃Represents a hydrogen atom, C having a sulfo group₁-C₅Lower alkoxy, and n represents 1 to 3, R₁～R₄Is C having a sulfo group₁-C₅Lower alkoxy, and the rest independently represent a hydrogen atom, C₁-C₅Lower alkyl or C₁-C₅Lower alkoxy, and

x is a phenylamino group which may have a substituent, a phenylazo group which may have a substituent or a naphthotriazole group which may have a substituent, and these substituents are a hydrogen atom, C₁-C₅Lower alkyl, C₁-C₅Lower alkoxy, hydroxy, carboxy, sulfo or amino, or X is 4-sulfomethylaminophenylamino or 4-carboxyethylaminophenylamino.

2. The azo compound and the salt thereof according to claim 1, wherein X is a phenylamino group represented by the formula (3)

Wherein R is₅And R₆Each independently represents a hydrogen atom, a methyl group, a methoxy group, a sulfo group or an amino group.

3. The azo compound and the salt thereof according to claim 1, wherein X is a naphthotriazolyl group represented by the formula (5)

Wherein m represents 1 or 2.

4. The azo compound and the salt thereof according to claim 1, wherein X is a phenylazo group represented by the formula (6)

Wherein R is₈～R₁₀Each independently represents a hydrogen atom, a hydroxyl group, C₁-C₅Lower alkyl, C₁-C₅Lower alkoxy or amino.

5. The azo compound of claim 1, wherein R is₁～R₄At least one of which is a sulfopropoxy group or a sulfobutoxy group, and the remaining are each independently a hydrogen atom, a methyl group or a methoxy group.

6. A dye-based polarizing film comprising a polarizing film substrate containing the azo compound of any one of claims 1 to 5 and/or a salt thereof.

7. A dye-based polarizing film comprising a polarizing film substrate containing the azo compound and/or salt thereof according to any one of claims 1 to 5, and at least one organic dye other than the azo compound and/or salt thereof.

8. A dye-based polarizing film comprising a polarizing film substrate containing two or more azo compounds and/or salts thereof according to any one of claims 1 to 5, and at least one organic dye other than the azo compounds and/or salts thereof.

9. The dye-based polarizing film according to any one of claims 6 to 8, wherein the polarizing film substrate is a film comprising a polyvinyl alcohol resin or a derivative thereof.

10. A dye-based polarizing plate obtainable by attaching a transparent protective layer to at least one surface of the dye-based polarizing film according to any one of claims 6 to 8.

11. A polarizing plate for liquid crystal display using the dye-based polarizing film or the dye-based polarizing plate according to any one of claims 6 to 10.

12. A color polarizing plate for a liquid crystal projector, using the dye-based polarizing film or the dye-based polarizing plate according to any one of claims 6 to 10.

13. A liquid crystal display device using the dye-based polarizing plate according to any one of claims 10 to 12.