HK40007786B - Azo compound or salt thereof, as well as dye-type polarizer film and dye-type polarizer plate including same - Google Patents

Description

Azo compound or salt thereof, and dye-based polarizing film and dye-based polarizing plate containing azo compound or salt thereof

Technical Field

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

Background

The polarizing plate having a light transmitting and shielding function can be used together with a Liquid Crystal having a light switching function in a Display such as a Liquid Crystal Display (LCD). The application fields of the LCD include small-sized devices such as early electronic computers and watches, notebook computers, word processors, liquid crystal projectors, liquid crystal televisions, car navigation systems, indoor and outdoor information displays, measuring instruments, and the like. Also, the present invention can be applied to lenses having a polarizing function, and is applied to sunglasses with improved visibility, polarizing glasses for recent 3D televisions, and the like. In recent years, not only display applications but also applications to the improvement of accuracy in an apparatus for determining authenticity, and applications to the improvement of an S/N ratio by cutting reflected light in an image sensor such as a CCD or a CMOS.

A general polarizing film is produced by dyeing a polarizing film substrate such as a polyvinyl alcohol film or a derivative thereof having an orientation stretched, or a polyene film having a polyene produced by dehydrochlorination of a polyvinyl chloride film or dehydration of a polyvinyl alcohol film and then orienting the film, or by containing iodine or a dichroic dye as a polarizing element. Among these, an iodine-based polarizing film using iodine as a polarizing element has a problem of durability when used for a long time in a high-temperature and high-humidity state, although it is excellent in polarizing performance, but is not resistant to water and heat. On the other hand, a dye-based polarizing film using a dichroic dye as a polarizing element is superior to an iodine-based polarizing film in moisture resistance and heat resistance, but is generally insufficient in polarizing performance.

In recent years, in applications to touch panel identification light sources, monitoring cameras, sensors, forgery prevention, and communication equipment, polarizing plates for use in not only visible light region wavelengths but also infrared regions have been required. To meet such a demand, an infrared polarizing plate obtained by polyalkyleneizing an iodine-based polarizing plate as in patent document 1, an infrared polarizing plate using a wire grid as in patent document 2 or 3, an infrared polarizer obtained by stretching glass containing fine particles as in patent document 4, or a type using a cholesteric liquid crystal as in patent document 5 or 6 have been reported. The infrared polarizing plate of patent document 1 is weak in durability, heat resistance, moist heat resistance and light resistance, and has not been practical. Such as a wire grid type of patent document 2 or 3, the wire grid type can be processed into a film type, and is becoming popular with the product stability. However, since the optical characteristics cannot be maintained and the surface cannot be touched without the nano-scale unevenness on the surface, the usable applications are limited and it is difficult to perform anti-reflection (AR) or anti-glare (anti-glare) processing. The glass drawn type containing fine particles of patent document 4 has high durability and high dichroism, and therefore, is practically used. However, since the glass contains fine particles and is stretched, the element itself is easily broken and fragile, and the glass is not flexible as in the conventional polarizing plate, and therefore, there is a problem that surface processing or bonding to another substrate is difficult. Patent documents 5 and 6 use the previously disclosed circular polarization technique, but since the color changes depending on the viewing angle or the polarization plate that reflects light is basically used, it is difficult to form stray light or absolutely polarized light. That is, there is no dye-based polarizing plate which is a film-type polarizing plate having flexibility and high durability and which corresponds to an infrared wavelength range, and which belongs to an absorption-type polarizing element such as a general iodine-based polarizing plate. This is because the conventional dichroic dye absorbs only in the visible wavelength region and does not absorb in the infrared wavelength region.

[ Prior art documents ]

[ patent document ]

[ patent document 1] specification of U.S. Pat. No. 2,494,686

[ patent document 2] Japanese patent laid-open publication No. 2016-148871

[ patent document 3] Japanese patent laid-open publication No. 2013-24982

[ patent document 4] Japanese patent application laid-open No. 2004-86100

[ patent document 5] International publication No. 2015/087709

[ patent document 6] Japanese patent publication No. Sho 45-1275.

Disclosure of Invention

[ problems to be solved by the invention ]

The invention aims to provide a method for preparing: a high-performance polarizing film and polarizing plate which are effective for light having a wavelength in the infrared region, and an azo compound or salt thereof which can produce the polarizing film and polarizing plate, although an extended film having a dichroic dye absorbing in the infrared region is used.

[ means for solving problems ]

As a result of intensive studies to achieve the object, the present inventors have newly found a polarizing plate that contains a film containing a dye having absorption in the infrared region and that acts on light having an infrared wavelength by aligning the dye in the film, and have completed the present invention.

That is, the present invention relates to the inventions of the following items [1] to [13 ].

[1] An azo compound represented by the following formula (1):

(in the formula, A)₁And A₂Each independently represents a hydrogen atom or a group represented by the following formula (2) or the following formula (3), except A₁And A₂All are the case of hydrogen atoms:

(in the formula, via R₁And a sulfo-substituted ring, a benzothiazole ring in the absence of the ring represented by the dotted line, a naphthothiazole ring in the presence of the ring represented by the dotted line, R₁Selected from chlorine atom, sulfo group, nitro group, hydroxyl group, alkyl group having 1 to 4 carbon atoms, alkoxy group having 1 to 4 carbon atoms, carbon having sulfo groupAlkyl group having 1 to 4 carbon atoms, alkyl group having 1 to 4 carbon atoms and having hydroxyl group, alkyl group having 1 to 4 carbon atoms and having carboxyl group, alkoxy group having 1 to 4 carbon atoms and having sulfo group, alkoxy group having 1 to 4 carbon atoms and having carboxyl group, R₁When there are plural, R is₁Each independently selected from the group described above,

R₂selected from the group consisting of a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms,

m represents an integer of 1 to 3),

(in the formula, via R₃And a sulfo-substituted ring, a benzothiazole ring in the absence of the ring represented by the dotted line, a naphthothiazole ring in the presence of the ring represented by the dotted line, R₃R in the formula (2)₁The same groups are used for the same groups,

R₄and R₅Each independently selected from the group consisting of a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having a sulfo group, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms,

n represents an integer of 1 to 3),

A₁when it is a hydrogen atom, R^aIs hydroxy, A₁When represented by formula (2) or formula (3), R^aAnd R^cOr R^dTogether form-O-Cu-O-,

A₂when it is a hydrogen atom, R^bIs hydroxy, A₂When represented by formula (2) or formula (3),R^band R^cOr R^dTogether form-O-Cu-O-,

two bonds of-NH-are each independently bonded to the substitution position represented by a or b).

[2]Such as [1]]The azo compound or a salt thereof, wherein A₁And A₂Each independently represented by formula (2) or formula (3).

[3]Such as [1]]The azo compound or a salt thereof, wherein A₁Represented by formula (2) or formula (3), A₂Is a hydrogen atom.

[4] The azo compound or a salt thereof according to any one of [1] to [3], wherein the substitution position of-NH-is a.

[5] The azo compound or a salt thereof according to [1], which is represented by the following formula (4):

(in the formula, R₆Is selected from the group consisting of a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having a sulfo group, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms,

x represents an integer of 1 to 3).

[6] A dye-based polarizing film comprising the azo compound of any one of [1] to [5] or a salt thereof and a polarizing film substrate, and having absorption at least in the near-infrared region.

[7] A dye-based polarizing film comprising the azo compound of any one of [1] to [5] or a salt thereof and a polarizing film substrate containing one or more organic dyes other than the azo compound or the salt thereof.

[8] A dye-based polarizing film comprising 2 or more azo compounds of any one of [1] to [5] or salts thereof, and one or more organic dyes other than these, and a polarizing film substrate.

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

[10] A dye-based polarizing plate obtained by laminating a transparent protective layer on at least one surface of the dye-based polarizing film according to any one of [6] to [9 ].

[11] A liquid crystal display comprising the dye-based polarizing film according to any one of [6] to [9] or the dye-based polarizing plate according to [10 ].

[12] The dye-based polarizing film according to any one of [6] to [9], which exhibits a neutral gray color.

[13] A display for a vehicle or an outdoor display, comprising the dye-based polarizing film according to [12] or a dye-based polarizing plate obtained by laminating a transparent protective layer on at least one side of the dye-based polarizing film.

[ Effect of the invention ]

The present invention may provide: a high-performance polarizing film and polarizing plate which are produced by using a stretched film having a dichroic dye absorbing in the infrared region, but which act on light having a wavelength in the infrared region, and an azo compound or a salt thereof from which the polarizing film and polarizing plate can be produced. The polarizing plate of the present invention can be used as a conventional dye-based polarizing plate for light in the infrared wavelength range. In one embodiment, the polarizing plate of the present invention has flexibility and/or physical stability. In one embodiment, the polarizing plate of the present invention is absorptive and thus does not generate stray light. In one embodiment, the polarizing plate of the present invention has high weather resistance (heat resistance, moist heat resistance, light resistance).

Detailed Description

< azo Compound or salt thereof >

The azo compound of the present invention is an azo compound represented by the following formula (1) or a salt thereof.

In the formula (1), the two bonds of-NH-are each independently bonded to the substitution position represented by a or b, and are preferably bonded to the substitution position represented by a.

In the formula (1), A₁And A₂Is a hydrogen atom or represented by the following formula (2):

or the following formula (3):

and (4) showing. However, remove A₁And A₂Both are the case of hydrogen atoms. A. the₁And A₂One is a hydrogen atom and the other is represented by the formula (2), or A₁And A₂Both of which are represented by formula (2). Preferably A₁And A₂Both of which are represented by formula (2).

In the formula (2), through R₁And a sulfonic acid group-substituted ring, which is a benzothiazole ring in the absence of the ring indicated by the dotted line and a naphthothiazole ring in the presence of the ring indicated by the dotted line. In the absence of a ring indicated by a dotted line, i.e. via R₁When the substituted ring is a benzothiazole ring, R is not limited₁And the substitution position of a sulfo group, but preferably only the 4-position, only the 6-position, a combination of substitution 4-position and 6-position and a combination of 6-position and 7-position, and more preferably only the 6-position and a combination of 4-position and 6-position. In the presence of a ring indicated by a dotted line, i.e. via R₁When the substituted ring is a naphthothiazole ring, although the substitution position is not limited, a combination of the 6-position and the 8-position, a combination of the 4-position and the 6-position and the 8-position, and a combination of the 4-position and the 7-position and the 9-position are preferable, and a combination of the 6-position and the 8-position is more preferable.

R₁Selected from the group consisting of a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having a sulfo group, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms. Preferably sulfo group, C1-C4 alkaneAn oxy group. With a plurality of R₁Each is independently selected.

The alkoxy group having a hydroxyl group and having 1 to 4 carbon atoms is preferably a linear alkoxy group having an alkoxy group end substituted with a hydroxyl group, and more preferably a 4-hydroxypropoxy group or a 4-hydroxybutoxy group. An alkoxy group having a carbon number of 1 to 4 of a carboxyl group, preferably a linear alkoxy group in which the alkoxy group is terminally substituted with a carboxyl group, and more preferably a 4-carboxypropoxy group or a 4-carboxybutoxy group. An alkoxy group having a sulfo group and having a carbon number of 1 to 4, preferably a linear alkoxy group in which the alkoxy group is substituted at the end with a sulfo group, and preferably a 4-sulfopropoxy group or a 4-sulfobutoxy group.

R₂Selected from the group consisting of a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having a sulfo group, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms. Preferred are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and an alkyl group having 1 to 4 carbon atoms and having a sulfo group. The substitution position is not particularly limited, and R is preferably^CAnd (4) contraposition.

m represents an integer of 1 to 3.

In the formula (3), through R₃The substituted ring is a benzothiazole ring in the absence of the ring indicated by the dotted line and a naphthothiazole ring in the presence of the ring indicated by the dotted line. In the absence of a ring indicated by a dotted line, i.e. via R₃When the substituted ring is a benzothiazole ring, R is not limited₃But preferably only the 4 th bit, only the 6 th bit, a combination of the 4 th bit and the 6 th bit and a combination of the 6 th bit and the 7 th bit, and more preferably only the 6 th bit and a combination of the 4 th bit and the 6 th bit. In the presence of a ring indicated by a dotted line, i.e. via R₃When the substituted ring is a naphthothiazole ring, although the substitution position is not limited, a combination of the 6-position and the 8-position, a combination of the 4-position and the 6-position and the 8-position, and a combination of the 4-position and the 7-position and the 9-position are preferable, and a combination of the 6-position and the 8-position is more preferable. Preferably only the number 2, only the number 6, only the number 7, a combination of the number 2 and the number 6, and a combination of the number 2 and the number 7, and in particularIt is preferably only bit number 2 and a combination of bits number 2 and 7.

R₃R in the formula (2)₁In the same sense, can be taken from R₁Are independently selected.

R₄And R₅Each independently selected from the group consisting of a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having a sulfo group, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms. And preferably a sulfo group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. The substitution position is not particularly limited, and only the 6-position and only the 7-position are preferred.

n represents an integer of 1 to 3.

A₁When it is a hydrogen atom, R^aIs hydroxy, A₁When represented by formula (2) or formula (3), R^aAnd R^cOr R^dTogether form-O-Cu-O-. A. the₂When it is a hydrogen atom, R^bIs hydroxy, A₂When represented by formula (2) or formula (3), R^bAnd R^cOr R^dTogether form-O-Cu-O-.

The azo compound represented by the formula (1) is preferably represented by the formula (4).

In the formula (4), R₆Selected from the group consisting of a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having a sulfo group, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms.

x represents an integer of 1 to 3.

The azo compound represented by the formula (1) may be in a free form or in a salt form. The salt may be, for example, an alkali metal salt such as a lithium salt, a sodium salt, or a potassium salt, or an organic salt such as an amine salt or an alkylamine salt. The salt is preferably a sodium salt.

Next, specific examples of the azo compound represented by the formula (1) are shown below. In the formula, sulfo group, carboxyl group and hydroxyl group are represented as free acids.

The azo compound represented by the formula (1) or a salt thereof can be produced by diazotization and coupling according to a general dye production method described in dye chemistry (published by FINITI Seisakusho, 1957, p. 621).

Specific examples of the production method include the following methods.

Diazotizing aminothiazoles represented by the following formula (A) and coupling the diazotized aminothiazoles with anilines represented by the following formula (B) or naphthylamines represented by the following formula (C) to obtain monoazo amino compounds represented by the following formula (D) or (E).

Diazotizing the monoazo amino compound (D) or (E) respectively, secondarily coupling the diazotized monoazo amino compound (D) or (E) with a naphthol represented by the following formula (F), and complexing copper by adding a copper salt to the obtained azo compound to obtain the azo compound represented by the formula (1).

In the formulae (A) to (F), R₀And through R₀Substituted ring is represented by the formula (2) wherein R₁Or R in the formula (3)₃In the same sense as in the description of (1), R₂Represents the same meaning as in formula (2), R₄And R₅Represents the same meaning as in formula (3), and l represents the same meaning as m in formula (2) or n in formula (3). Rp and Rq are substituents having an oxygen atom as precursors of the copper complex before the salination, and are generally a hydroxyl group or an alkoxy group having 1 to 4 carbon atoms.

In the above-mentioned production method, the diazotization step is preferably carried out by a forward method of mixing a nitrite such as sodium nitrite in an aqueous solution or suspension of a diazonium component in an inorganic acid such as hydrochloric acid or sulfuric acid, or by a reverse method of adding a nitrite to a neutral or weakly alkaline aqueous solution of a diazonium component and mixing the resulting solution with an inorganic acid. The temperature of the diazotization is suitably from-10 to 40 ℃. Further, in the step of coupling with anilines, it is preferable to mix an acidic aqueous solution such as hydrochloric acid or acetic acid with each of the above-mentioned diazo solutions and carry out the coupling under acidic conditions at a temperature of-10 to 40 ℃ and a pH of 2 to 7.

The monoazo compound of the formula (D) or the formula (E) obtained after the coupling may be directly filtered, or precipitated by acid precipitation or salting out, and then removed by filtration, or may be directly subjected to the next step as a solution or suspension. When the diazonium salt is poorly soluble and forms a suspension, it can be filtered to form a cake and used in the next coupling step.

The secondary coupling reaction of the diazo compound of formula (D) or formula (E) with the naphthol represented by formula (F) is preferably carried out under neutral to basic conditions at a temperature of-10 to 40 ℃ and a pH of 7 to 10. After the reaction is completed, the azo compound or salt thereof is preferably precipitated by salting out and then removed by filtration. When purification is required, salting-out may be repeated or precipitation from water may be carried out by 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.

In the reaction of copper complexation, a copper salt such as copper sulfate, copper chloride or copper acetate is added to an aqueous solution containing the azo compound or salt thereof obtained in the above-mentioned secondary coupling reaction, and the reaction is carried out in the presence of an amine such as ammonia, monoethanolamine or diethanolamine, for example, at 70 to 100 ℃. After the reaction is completed, the azo compound or salt thereof represented by formula (1) can be obtained by precipitating the obtained azo compound or salt thereof, preferably by salting out, filtering, and removing.

The aminothiazole compound represented by the formula (A) is represented by 2-aminobenzothiazole in the absence of the ring represented by the dotted line, and examples thereof include: 2-amino-6-sulfobenzothiazole, 2-amino-7-methoxy-6-sulfobenzothiazole, 2-amino-4, 6-disulfobenzothiazole and 2-amino-7-methoxy-4, 6-disulfobenzothiazole. The aminothiazole compound represented by the formula (A) is represented by 2-aminonaphthothiazoles in the presence of a ring represented by a dotted line, and examples thereof include: 2-amino-6, 8-disulfo-naphthothiazole, 2-amino-4, 6, 8-tri-sulfo-naphthothiazole, 2-amino-4-chloro-6, 8-di-sulfo-naphthothiazole, 2-amino-6-sulfo-propoxy-4, 7, 8-tri-sulfo-naphthothiazole, 2-amino-6-methoxy-4, 7, 8-tri-sulfo-naphthothiazole, 2-amino-7-sulfo-propoxy-4, 9-di-sulfo-naphthothiazole, 2-amino-4-sulfo-propoxy-5, 7, 9-tri-sulfo-naphthothiazole, etc., and preferably 2-amino-6-sulfobenzothiazole, 2-amino-7-methoxy-6-sulfobenzothiazole, 2-amino-6, 8-disulfo-naphthothiazole.

The anilines of the formula (B) include, for example: 2-methoxyaniline, 2-methoxy-5-methylaniline, 2, 5-dimethoxyaniline, 2, 6-dimethoxyaniline, 2-ethoxyaniline, 2-ethoxy-5-methylaniline, 2, 5-diethoxyaniline, 2, 6-diethoxyaniline, 2-methoxy-5-ethoxyaniline, 2-ethoxy-5-methoxyaniline, or 2-methoxy-5-chloroaniline. Preferred examples thereof include: 2-methoxy-5-methylaniline and 2, 5-dimethoxyaniline. The amine groups of these anilines may also be protected. Naphthylamines of the formula (C) include, for example: 1-amino-2-methoxynaphthalene-6-sulfonic acid, 1-amino-2-methoxynaphthalene-7-sulfonic acid, 1-amino-2-ethoxynaphthalene-6-sulfonic acid and 1-amino-2-ethoxynaphthalene-7-sulfonic acid. Preferably, 1-amino-2-methoxynaphthalene-6-sulfonic acid is used. The amine groups of these naphthylamines may also be protected. Examples of protecting groups include: omega-methane sulfonic group.

The azo compound of the present invention or a salt thereof has absorption in the near infrared region. The azo compound or a salt thereof of the present invention can be dyed, stretched and oriented on a film, exhibits anisotropic absorption, and is useful as a dye for a polarizing film. Here, the infrared region generally means 700 to 30,000nm, and the wavelength of the near infrared ray means 700 to 1,500 nm. The azo compound or a salt thereof of the present invention can be used to produce a high-performance dye-based near-infrared absorbing polarizing plate having polarizing properties in the near-infrared region. Further, by using a dye having a polarizing property in the visible light region in combination, a high-performance dye-based polarizing plate can be realized in which neutral gray color in the near infrared region can be controlled as well as in the current visible light region. In one embodiment, the azo compound or a salt thereof of the present invention is suitable for producing a neutral gray polarizing plate for vehicles or outdoor displays that can be used under high-temperature and high-humidity conditions, or for producing a near-infrared absorbing polarizing plate for various sensors required for controlling the near-infrared region.

< dye-based polarizing film >

The dye-based polarizing film comprises a dichroic dye containing at least an azo compound represented by the formula (1) or a salt thereof and a polarizing film substrate, and has absorption at least in the near infrared region. The dye-based polarizing film may be any of a color polarizing film, a neutral gray polarizing film and a near infrared ray absorption polarizing film, and is preferably a near infrared ray absorption polarizing film. Here, in the specification and claims of the present application, "neutral gray" means a state (vertical position) in which 2 polarizing films are stacked so that their alignment directions are perpendicular to each other, and reduces light leakage (color leakage) of a specific wavelength in the visible light region and the near infrared region.

The dye-based polarizing film contains one or more azo compounds represented by the formula (1) or salts thereof as dichroic dyes, and may contain one or more other organic dyes as needed. The organic dye to be used in combination is not particularly limited, but is preferably a dye having absorption characteristics in a wavelength region different from the absorption wavelength region of the azo compound or salt represented by the formula (1) and having high dichroism. Examples of the organic dyes used in combination include dyes such as 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 blue 67, c.i. direct blue 237, c.i. direct blue 273, c.i. direct blue 274, c.i. direct green 80, and c.i. direct green 59. These pigments are contained in the dye-based polarizing film as free acids, or as salts of alkali metals (e.g., Na salt, K salt, Li salt), ammonium salts, or amines.

When other organic dyes are used in combination, different kinds of other organic dyes can be prepared for the intended dye-based polarizing film, such as a near-infrared-absorbing polarizing film, a neutral gray polarizing film, a color polarizing film for a liquid crystal projector, and other color polarizing films. The blending ratio of the other organic dye is not particularly limited, but is preferably in the range of 0.1 to 10 parts by mass relative to 100 parts by mass of the azo compound of the formula (1) or a salt thereof and the total of 1 or more organic dyes.

In the case of a neutral gray polarizing film, the kind and blending ratio of the other organic dyes to be used in combination can be adjusted in such a manner that color leakage in the wavelength region of the visible light region of the obtained polarizing film is reduced.

The dye-based polarizing film contains at least the azo compound represented by the formula (1) or a salt thereof, and can be produced by adsorbing and aligning a dichroic dye containing another organic dye as needed on a polarizing film substrate (for example, a polymer film) by a known method, mixing the dichroic dye with a liquid crystal, or aligning the dichroic dye by a coating method.

The polarizing film substrate is preferably a polymer film, and more preferably a film made of a polyvinyl alcohol resin or a derivative thereof. Specific examples of the polarizing film base include polyvinyl alcohol or a derivative thereof, and any of these is modified with an olefin such as ethylene or propylene, and an unsaturated carboxylic acid such as crotonic acid, acrylic acid, methacrylic acid, or maleic acid. For the polarizing film substrate, a film made of polyvinyl alcohol or a derivative thereof is suitable in terms of the adsorption and alignment properties of the dye. The thickness of the polarizing film substrate is usually 30 to 100 μm, and preferably about 50 to 80 μm.

When the polarizing film substrate is a polymer film, when a dichroic dye containing at least the azo compound of formula (1) or a salt thereof is incorporated, a method of dyeing the polymer film is generally employed. The dyeing can be carried out, for example, as follows. First, the azo compound of the present invention or a salt thereof and, if necessary, another organic dye are dissolved in water to prepare a dye bath. The dye concentration in the dye bath is not particularly limited, and may be selected from a range of about 0.001 to 10 mass%. Further, a dyeing assistant may be used as needed, for example, mirabilite may be used at a concentration of about 0.1 to 10% by mass. The polymer film is immersed in the thus prepared dye bath to be dyed for 1 to 10 minutes. The dyeing temperature is preferably from about 40 to 80 ℃.

The alignment of the dichroic dye containing the azo compound of formula (1) or a salt thereof can be performed by stretching the dyed polymer film. Methods of extension may use, for example: wet method, dry method, and the like. The polymer film may be stretched before dyeing, depending on the case. In this case, the alignment of the water-soluble dye can be performed during dyeing. The polymer film containing the water-soluble dye and oriented may be subjected to a post-treatment such as a boric acid treatment by a known method as required. Such post-treatment is performed for the purpose of improving the light transmittance and polarization degree of the dye-based polarizing film. The conditions of the boric acid treatment may vary depending on the kind of the polymer film to be used or the kind of the dye to be used, but the boric acid concentration of the aqueous boric acid solution is usually made to be in the range of 0.1 to 15% by mass, and preferably 1 to 10% by mass, and the treatment is carried out, for example, by soaking for 0.5 to 10 minutes at a temperature in the range of, for example, 30 to 80 ℃, preferably 40 to 75 ℃. Further, the repair (fix) treatment may be carried out in parallel with an aqueous solution containing a cationic polymer compound as required.

The obtained dye-based polarizing film can be used as a polarizing plate with a protective film added thereto, and a protective layer, an AR (anti-reflection) layer, a support, and the like can be provided as required.

The colored and neutral gray dye-based polarizing film is preferably applicable to, for example: liquid crystal projectors, electronic computers, watches, notebook computers, word processors, liquid crystal televisions, car navigators, displays of indoor and outdoor measuring instruments and vehicles, and lenses and glasses. The infrared region absorbing polarizing film can be suitably used for an apparatus for determining authenticity, an image sensor such as a CCD or CMOS, or the like. The dye-based polarizing film has high polarizing performance comparable to that of a polarizing film using iodine, and is excellent in durability. Therefore, the polarizing plate is particularly suitable for various liquid crystal displays, liquid crystal projectors, vehicles, and indoor and outdoor displays (for example, display applications or wearing applications of industrial measuring instruments) which require high polarizing performance and durability, and for safety devices which require high reliability.

< dye-based polarizing plate >

The dye-based polarizing plate can be obtained by laminating a transparent protective film on one or both surfaces of a dye-based polarizing film. The dye-based polarizing plate has excellent polarizing performance, moisture resistance, heat resistance and light resistance because of the dye-based polarizing film. The material for forming the transparent protective film is preferably a material having excellent optical transparency and mechanical strength, and for example, a fluorine-based film such as a tetrafluoroethylene/hexafluoropropylene copolymer, a polyester resin, a polyolefin resin, or a polyamide resin may be used in addition to the cellulose acetate-based film or the acrylic film. The transparent protective film is preferably a triacetyl cellulose (TAC) film or a cycloolefin-based film. The thickness of the protective film is generally preferably 40 to 200 μm.

The adhesive used when the polarizing film is bonded to the protective film includes a polyvinyl alcohol adhesive, a polyurethane emulsion adhesive, an acrylic adhesive, a polyester-isocyanate adhesive, and the like, and a polyvinyl alcohol adhesive is most preferable.

The surface of the dye-based polarizing plate may be further provided with a transparent protective layer. Examples of the transparent protective layer include: acrylic or polysiloxane based hard coats or polyurethane based protective layers. 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 by vapor deposition or sputtering of a substance such as silicon dioxide or titanium oxide, or may be formed by coating a thin layer with a fluorine-based substance. The dye-based polarizing plate may be used as an elliptical polarizing plate by further attaching a retardation plate to the surface thereof.

The dye-based polarizing plate may be any of the near-infrared ray absorption polarizing plate, the neutral gray polarizing plate and the color polarizing plate described above in combination.

Neutral gray polarizers have the following characteristics: the light-emitting element is excellent in polarization performance and is prevented from being discolored or from being deteriorated in polarization performance even in a high-temperature and high-humidity state, and is less in light leakage at a vertical position in the visible light region, and is particularly suitable for safety equipment requiring high reliability for use in vehicles or outdoor displays.

In order to further improve the single-plate light transmittance of a neutral gray polarizing plate for use in a vehicle or for use in an outdoor display, it is preferable to provide an AR layer on a polarizing plate formed of a polarizing film and a protective film to form an AR layer-added polarizing plate, and it is more preferable to provide an AR layer of a support such as a transparent resin and a support-added polarizing plate. The AR layer may be provided on one side or both sides of the polarizing plate. The support is preferably provided on one surface of the polarizing plate, and may be provided on the polarizing plate through an AR layer or directly provided. The support preferably has a flat portion for adhering the polarizing plate, and further preferably a transparent substrate for optical use. The transparent substrate can be roughly classified into an inorganic substrate and an organic substrate, and examples thereof include inorganic substrates such as soda glass, borosilicate glass, crystal substrate, sapphire substrate and spinel substrate, and organic substrates such as acrylic, polycarbonate, polyethylene terephthalate, polyethylene naphthalate and cycloolefin polymer, and organic substrates are preferable. The thickness or size of the transparent substrate may be set to a desired size.

The near-infrared absorbing polarizing plate is excellent in polarizing performance, and does not cause discoloration or a reduction in polarizing performance even in a high-temperature and high-humidity state, and therefore, is suitable for a liquid crystal projector, a vehicle, and an outdoor display, and for a safety device requiring high reliability. These polarizing plates are obtained by adding a protective film to a dye-based polarizing film, and can be used by providing a protective layer, an AR layer, and a support as required.

The single-plate average light transmittance is an average value of light transmittance in a specific wavelength region when natural light is incident on a polarizing film or a single polarizing plate (hereinafter, simply referred to as a polarizing plate) having no support such as an AR layer or a transparent glass plate (the same applies to the case of a polarizing plate). The average light transmittance at the vertical position is an average value of light transmittance in a specific wavelength region when natural light is incident on 2 polarizing films or polarizing plates arranged so that the alignment direction is vertical.

The color polarizing plate with a support for vehicle or outdoor display can be produced, for example, by coating a transparent adhesive (adhesive) on the flat surface portion of the support and then adhering a dye-based polarizing plate on the coated surface. Meanwhile, a transparent adhesive (adhesive) may be applied to the dye-based polarizing plate, and then a support may be attached to the applied surface. The adhesive (bonding agent) used here is preferably, for example, an acrylate. When the dye-based polarizing plate is used as an elliptically polarizing plate, the retardation plate is usually bonded to the support, but the polarizing plate may be bonded to the transparent substrate.

< liquid crystal display >

A liquid crystal display comprising the dye-based polarizing film or the dye-based polarizing plate. Liquid crystal displays are displays for use in, for example, electronic computers, watches, notebook computers, word processors, liquid crystal televisions, car navigation systems, indoor and outdoor measuring instruments, displays and the like, and are particularly suitable for use in various liquid crystal displays requiring high polarization performance and durability, for example, for use in vehicles and outdoor displays (for example, for industrial measurement-type display applications or for wearing applications).

The liquid crystal display for vehicles or outdoor use preferably has a neutral gray polarizing film or polarizing plate. Since the neutral gray polarizing film or polarizing plate has brightness and excellent polarizing performance, durability and light resistance, it is less likely to cause discoloration or deterioration in polarizing performance even in a high-temperature and high-humidity state inside a vehicle or outside, and a highly reliable display for vehicles or outside can be realized.

[ examples ]

The present invention will be described in more detail with reference to the following examples, which are merely illustrative and are not intended to limit the scope of the present invention. Unless otherwise specified,% and parts are on a mass basis.

[ example 1]

36.0 parts of 2-aminonaphthothiazole-6, 8-disulfonic acid was added to 100 parts of 98% sulfuric acid and dissolved at 50 ℃, 12.6 parts of 60% nitric acid was added thereto, 50 parts of 40% nitrosylsulfuric acid was added dropwise at 5 to 10 ℃ for about 10 minutes, and a diazo reaction solution was obtained after 1 hour of reaction. Next, 15.3 parts of 2, 5-dimethoxyaniline was added to 10.4 parts of an acidic aqueous solution of hydrochloric acid diluted with 100 parts of water, and dissolved. The former diazo reaction solution was dropped into this aqueous solution over 3 hours and stirred overnight to complete the coupling reaction. Then, 41.9 parts of a monoazo amino compound represented by the following formula (45) was obtained by filtration.

The obtained 41.9 parts of monoazo amine-based compound (45) was added to 200 parts of water, and 25% sodium hydroxide was added thereto to dissolve the monoazo amine-based compound (45). 13.8 parts of 40% sodium nitrite aqueous solution was added, followed by addition of 25.0 parts of 35% hydrochloric acid at 20 to 30 ℃ and stirring at 20 to 30 ℃ for 1 hour to obtain a diazo compound. On the other hand, 36.9 parts of 6,6 '-iminobis (1-hydroxynaphthalene-3-sulfonic acid) was added to 100 parts of water, and a 25% aqueous sodium hydroxide solution was added thereto to make the mixture weakly alkaline, thereby dissolving 6, 6' -iminobis (1-hydroxynaphthalene-3-sulfonic acid). The diazotized product obtained before was kept at pH8 to 10 and dropped into this liquid, and stirred to complete the coupling reaction. Then, salting out was performed with sodium chloride, and the filtrate was filtrated to obtain 63.7 parts of the compound represented by the formula (46).

63.7 parts of the obtained diazoamino compound (46) was dissolved in 200 parts of water, and 19.2 parts of copper sulfate pentahydrate and 39.0 parts of monoethanolamine were added thereto to conduct a reaction at 95 ℃ for 3 hours. After completion of the reaction, the reaction mixture was cooled, salted out with sodium chloride, and filtered to obtain 53.5 parts of a compound represented by the formula (8). The maximum absorption wavelength of this compound in 20% aqueous pyridine solution was 752 nm.

[ example 2]

The same operations as in example 1 were carried out, except for replacing 36.9 parts of 6,6 '-iminobis (1-hydroxynaphthalene-3-sulfonic acid) with 36.9 parts of 7, 7' -iminobis (1-hydroxynaphthalene-3-sulfonic acid), to obtain 53.5 parts of a compound represented by the formula (9). The maximum absorption wavelength of this compound in 20% aqueous pyridine solution was 756 nm.

[ example 3]

The same operations as in example 1 were carried out, except for replacing 36.0 parts of 2-aminonaphthothiazole-6, 8-disulfonic acid by 26.0 parts of 2-amino-7-methoxybenzothiazole-6-sulfonic acid, to obtain 46.7 parts of a compound represented by the formula (15). The maximum absorption wavelength of this compound in 20% aqueous pyridine was 692 nm.

[ example 4]

In the same manner as in example 1, 41.9 parts of the compound represented by the formula (45) was diazotized, maintained at pH9 to 11, and dropped into an aqueous solution in which 79.6 parts of the compound represented by the formula (46) was added to 200 parts of water and dissolved, followed by stirring to complete the coupling reaction. Then, the salt was separated out with sodium chloride, and the solution was filtered to obtain 78.4 parts of a compound represented by the formula (47).

78.4 parts of the thus-obtained tetraazaamino compound (47) was dissolved in 200 parts of water, and then 30.7 parts of copper sulfate pentahydrate and 31.2 parts of monoethanolamine were added thereto to conduct a reaction at 95 ℃ for 3 hours. After completion of the reaction, the reaction mixture was cooled, salted out with sodium chloride, and filtered to obtain 66.6 parts of a compound represented by the formula (17). The maximum absorption wavelength of this compound in a 20% aqueous solution of pyridine was 802 nm.

[ example 5]

The same operations as in example 4 were carried out, except for replacing the compound represented by the above formula (8) with the compound represented by the above formula (9), to obtain 66.6 parts of a compound represented by the formula (18). The maximum absorption wavelength of this compound in 20% aqueous pyridine was 806 nm.

[ example 6]

The same procedures as in examples 1 and 4 were carried out, except for replacing 36.0 parts of 2-aminonaphthothiazole-6, 8-disulfonic acid by 23.0 parts of 2-aminobenzothiazole-6-sulfonic acid, to obtain 55.9 parts of a compound represented by the formula (27). The maximum absorption wavelength of this compound in 20% aqueous pyridine was 706 nm.

[ example 7]

55.9 parts of the compound represented by the formula (29) was obtained in the same manner as in example 1 and example 4, except that 36.0 parts of 2-aminonaphthothiazole-6, 8-disulfonic acid was replaced with 26.0 parts of 2-amino-7-methoxybenzothiazole-6-sulfonic acid. The maximum absorption wavelength of this compound in a 20% pyridine aqueous solution was 723 nm.

[ example 8]

The same operations as in example 1 were carried out, except for replacing 15.3 parts of 2, 5-dimethoxyaniline with 13.7 parts of 2-methoxy-5-methylaniline, to obtain 40.6 parts of a compound represented by formula (48).

The same operations as in example 4 were carried out, except for replacing 41.9 parts of the compound represented by the formula (45) with 40.6 parts of the compound represented by the formula (48), to obtain 65.9 parts of a compound represented by the formula (35). The maximum absorption wavelength of this compound in a 20% aqueous pyridine solution was 794 nm.

[ example 9]

The same operations as in example 1 were carried out, except for replacing 36.0 parts of 2-aminonaphthothiazole-6, 8-disulfonic acid by 23.0 parts of 2-aminobenzothiazole-6-sulfonic acid, to obtain 46.7 parts of a compound represented by formula (13). The maximum absorption wavelength of this compound in 20% aqueous pyridine was 652 nm.

Production example 1: polarizing film

Polyvinyl alcohol having a thickness of 75 μm was immersed in a staining solution prepared from an aqueous solution of the compound of formula (8) obtained in example 1 at 45 ℃ at a concentration of 0.03% and mirabilite at a concentration of 0.1% for 4 minutes. This film was stretched to 5 times in a 3% aqueous boric acid solution at 50 ℃, washed with water while being kept in a taut state, and dried to obtain a polarizing film.

Production examples 2 to 8: polarizing film

A polarizing film was obtained in the same manner as in production example 1, except that the azo compound of formula (9), (15), (17), (18), (27), (29), or (35) obtained in examples 2 to 8 was used in place of the compound of formula (8).

(measurement of maximum absorption wavelength and polarization Rate of polarizing film)

The maximum absorption wavelength and the polarization ratio were measured for the polarizing films obtained in production examples 1 to 9 of the polarizing films. The maximum absorption wavelength of the polarizing film and the polarization ratio were calculated by measuring the parallel transmittance and the perpendicular transmittance at the time of polarization incidence by a spectrophotometer (U-4100, manufactured by Hitachi Ltd.). The parallel transmittance (Ky) here means a transmittance when the absorption axis of the absolute polarizing plate is parallel to the absorption axis of the polarizing film; the vertical transmittance (Kz) is a transmittance when the absorption axis of the absolute polarizing plate is perpendicular to the absorption axis of the polarizing film. The parallel transmittance and the perpendicular transmittance at each wavelength were measured at 1nm intervals in a range of 380 to 1,100 nm. Using the respective measured values, the polarization ratios at the respective wavelengths were calculated by the following formula (i), and the maximum polarization ratio in 380 to 1,100nm and the absorption wavelength (nm) at that time were obtained. The results are shown in table 1.

Polarizing ratio (%) [ (Ky-Kz)/(Ky + Kz) ] × 100(i)

[ Table 1]

	Azo compound or salt thereof	Absorption wavelength (nm) at which polarization ratio is maximum	Polarization ratio (%)
				Production example 1	A compound of formula (8)	784	99.9
Production example 2	A compound of formula (9)	785	99.9
				Production example 3	A compound of formula (15)	724	99.9
Production example 4	A compound of formula (17)	835	99.9
				Production example 5	A compound of formula (18)	840	99.9
Production example 6	A compound of formula (27)	739	99.9
				Production example 7	A compound of formula (29)	754	99.9
Production example 8	A compound of formula (35)	826	99.9

As shown in Table 1, the polarizing films prepared by using these compounds all have absorption wavelengths in the near infrared region and have high polarization ratios.

Preparation example 9: neutral gray polarizing plate

A polarizing film was produced in the same manner as in production example 1, except that an aqueous solution of the compound of formula (17) at 45 ℃ having a concentration of 0.2%, c.i. direct orange 39 0.07%, c.i. direct red 81 0.02%, c.i. direct blue 274 0.03%, and mirabilite 0.1% was used as a dyeing solution. The obtained polarizing film had an average transmittance of single sheet of 38% in 380 to 850nm, an average light transmittance in the vertical position of 0.02%, and a high degree of polarization over a wide band. The transmittance in the visible light range is substantially constant at the parallel position and the vertical position, and the color tone is neutral gray.

A triacetyl cellulose Film (TAC Film; manufactured by Fuji Photo Film Co., Ltd.; trade name: TD-80U) was laminated one by one on both sides of this polarizing Film with an adhesive of an aqueous polyvinyl alcohol solution. Then, an AR support (REALEC X4010, manufactured by Nikkiso Co., Ltd.) was laminated on one TAC film using an adhesive to obtain a neutral gray dye-based polarizing plate to which the AR support was attached. The obtained polarizing plate has neutral gray color tone and higher polarizing rate, which are the same as those of the polarizing film.

In addition, although data is not shown, the obtained polarizing plate exhibits durability even in a high-temperature and high-humidity state for a long period of time, and has excellent light resistance even when exposed for a long period of time.

Claims (13)

1. An azo compound represented by the following formula (1):

in the formula, A₁And A₂Each independently a hydrogen atom or a group represented by the following formula (2) or (3) except A₁And A₂All are the case of hydrogen atoms:

in the formula, the main chain is represented by R₁And a sulfo-substituted ring, a benzothiazole ring in the absence of the ring represented by the dotted line, a naphthothiazole ring in the presence of the ring represented by the dotted line, R₁Selected from the group consisting of chlorine atom, sulfo group, nitro group, hydroxyl group, alkyl group having 1 to 4 carbon atoms, alkoxy group having 1 to 4 carbon atoms, alkyl group having 1 to 4 carbon atoms, alkoxy group having 1 to 4 carbon atoms, and alkoxy group having 1 to 4 carbon atoms, R₁When there are plural, R is₁Each independently selected from the group described above,

R₂selected from the group consisting of a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having a sulfo group, an alkoxy group having 1 to 4 carbon atoms, and a carbon group having a carboxyl groupAlkoxy groups having a number of 1 to 4,

m represents an integer of 1 to 3,

in the formula, the main chain is represented by R₃And a sulfo-substituted ring, a benzothiazole ring in the absence of the ring represented by the dotted line, a naphthothiazole ring in the presence of the ring represented by the dotted line, R₃R in the formula (2)₁The same groups are used for the same groups,

R₄and R₅Each independently selected from the group consisting of a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having a sulfo group, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms,

n represents an integer of 1 to 3,

A₁when it is a hydrogen atom, R^aIs hydroxy, A₁When represented by formula (2) or formula (3), R^aAnd R^cOr R^dTogether form-O-Cu-O-,

A₂when it is a hydrogen atom, R^bIs hydroxy, A₂When represented by formula (2) or formula (3), R^bAnd R^cOr R^dTogether form-O-Cu-O-,

the two bonds of-NH-are each independently bonded to the substitution position represented by a or b.

2. The azo compound or a salt thereof according to claim 1, wherein A is₁And A₂Each independently represented by formula (2) or formula (3).

3. The azo compound or a salt thereof according to claim 1, wherein A is₁Represented by formula (2) or formula (3), A₂Is a hydrogen atom.

4. The azo compound or a salt thereof according to any one of claims 1 to 3, wherein the substitution position of-NH-is a.

5. The azo compound or a salt thereof according to claim 1, represented by the following formula (4):

in the formula, R₆Selected from the group consisting of a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms,

x represents an integer of 1 to 3.

6. A dye-based polarizing film comprising the azo compound or salt thereof according to any one of claims 1 to 5 and a polarizing film substrate, and having absorption at least in the near infrared region.

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

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

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

10. A dye-based polarizing plate obtained by laminating a transparent protective layer on at least one side of the dye-based polarizing film according to any one of claims 6 to 9.

11. A liquid crystal display comprising the dye-based polarizing film according to any one of claims 6 to 9 or the dye-based polarizing plate according to claim 10.

12. A dye-based polarizing film according to any one of claims 6 to 9, exhibiting a neutral gray color.

13. A display for a vehicle or an outdoor display, comprising the dye-based polarizing film according to claim 12, or a dye-based polarizing plate obtained by laminating a transparent protective layer on at least one side of the dye-based polarizing film.