Azo compound or salt thereof, and polarizing film, polarizer, and display device containing the same

Abstract

To provide a dichroic dye, a polarizing film, and a polarizer capable of exhibiting excellent polarization performance in a blue-green system with a maximum absorption wavelength longer than 600 nm.SOLUTION: An azo compound or a salt thereof is represented by formula (1) (where Ar represents a benzene ring, a naphthalene ring, or a heterocyclic ring, each of which may have a substituent; R1-R5 each independently represent a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C1-C4 alkoxy group having a sulfo group; Q represents any substituent; and n represents an integer of 1-3).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a novel azo compound or a salt thereof, and a polarizing film, a polarizing plate and a display device containing the same. [Background technology]

[0002] Polarizing plates, which have the ability to transmit and block light, are fundamental components of displays such as liquid crystal displays (LCDs), along with liquid crystals, which have the ability to switch light. Applications of LCDs range from early compact devices such as calculators and clocks to laptops, word processors, LCD projectors, LCD televisions, car navigation systems, and indoor and outdoor measuring instruments. Polarizing plates can also be applied to lenses, leading to applications such as sunglasses with improved visibility and, more recently, polarized glasses for 3D televisions. As polarizing plates are used in a wide range of applications, including low to high temperatures, low to high humidity, and low to high light levels, polarizing plates with high polarization performance and durability are in demand.

[0003] Currently, polarizing plates are manufactured by dyeing or impregnating a film of polyvinyl alcohol or its derivatives with iodine or a dichroic dye, stretching it, and then orienting it. Alternatively, polyenes are produced by dehydrochlorinating a polyvinyl chloride film or dehydrating a polyvinyl alcohol film to form and orient the polyenes. These substances significantly affect the polarization performance (e.g., polarization rate, dichroic ratio, etc.) and durability of polarizing plates. Iodine-based polarizing films, which use iodine, have excellent polarization performance but are vulnerable to water and heat, resulting in poor durability when used for long periods of time under high-temperature and high-humidity conditions. To improve durability, methods such as treating the film with an aqueous solution containing formalin or boric acid or using a polymer film with low moisture permeability as a protective film have been considered, but these methods are not sufficiently effective.

[0004] On the other hand, dye-based polarizing films using dyes have superior moisture resistance and heat resistance compared to iodine-based polarizing films. For example, dye-based polarizing films are generally manufactured by combining multiple dyes, and are often manufactured in three colors, yellow-orange, red-purple, and blue-green, or in four colors that complement each intermediate color. However, the polarization performance of dye-based polarizing films is still insufficient, and the development of dichroic dyes with good polarization performance for each color used is necessary. In particular, there is a demand for improved performance of blue-green dichroic dyes that have a maximum absorption wavelength in the long wavelength region above 600 nm.

[0005] Azo compounds are often used as blue to green dichroic dyes, and for example, Patent Documents 1 to 8 disclose examples in which tetrakis azo compounds are used as dichroic dyes. However, these have not yet achieved sufficient polarization performance. Patent Document 9 describes the improvement of dichroic ratio performance by using tetrakis azo copper compounds. However, copper compounds generally have poor dichroic ratios and strong side absorption on the short wavelength side. For these reasons, a dichroic dye with a maximum absorption wavelength in the long wavelength region exceeding 600 nm that can exhibit sufficient performance has not yet been developed, and further improvement in performance has been desired. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-220544 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-327858 [Patent Document 3] Japanese Patent Application Laid-Open No. 2005-255846 [Patent Document 4] International Publication No. 2012 / 108169 [Patent Document 5] International Publication No. 2012 / 108173 [Patent Document 6] International Publication No. 2016 / 186183 [Patent Document 7] International Publication No. 2015 / 152026 [Patent Document 8] International Publication No. 2022 / 054786 [Patent Document 9] International Publication No. 2017 / 135392 [Patent Document 10] Japanese Patent Application Publication No. 07-159615 [Non-patent literature]

[0007] [Non-Patent Document 1] Dye Chemistry; Yutaka Hosoda, Gihodo Publishing, 1957 [Non-patent document 2] Application of Functional Dyes (CMC Publishing Co., Ltd., 1st edition, supervised by Masahiro Irie, pp. 98-100) Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a dichroic dye, a polarizing film, and a polarizing plate that have excellent polarization performance in the blue to green range with a maximum absorption wavelength in the long wavelength region exceeding 600 nm. [Means for solving the problem]

[0009] As a result of intensive research conducted by the present inventors to achieve this object, they have found that a polarizing film and a polarizing plate containing a specific azo compound or a salt thereof have excellent polarizing performance and durability.

[0010] That is, the present invention relates to the following [1] to [5]. [1] An azo compound represented by the following formula (1) or a salt thereof:

[0011] [ka] In formula (1), Ar represents a benzene ring which may have a substituent, a naphthalene ring which may have a substituent, or a heterocycle which may have a substituent; R 1 ~R 5 each independently represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C1-C4 alkoxy group having a sulfo group, Q represents an optional substituent, and n represents an integer of 1 to 3). [2] The azo compound or salt thereof according to [1], wherein the azo compound represented by formula (1) or a salt thereof is represented by the following formula (2) or a salt thereof:

[0012] [ka] (In formula (2), R 1 ~R 6 each independently represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C1-C4 alkoxy group having a sulfo group, and n represents an integer of 1 to 3). [3] The azo compound or salt thereof according to [1], wherein the azo compound represented by formula (1) or a salt thereof is represented by the following formula (3) or a salt thereof:

[0013] [ka] (In the above formula (3), R 6 represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C1-C4 alkoxy group having a sulfo group, and n represents an integer of 1 to 3). [4] A polarizing film containing the azo compound or a salt thereof according to any one of [1] to [3]. [5] The polarizing film according to any one of [1] to [3], which comprises a substrate. [6] [5] A polarizing plate having a transparent protective film provided on one side and both sides of the polarizing film, and a display device using the polarizing plate. [Effects of the Invention]

[0014] The azo compound or salt thereof of the present invention is useful as a dichroic dye for blue to green polarizing films having a maximum absorption wavelength in the long wavelength region exceeding 600 nm, and the polarizing film and polarizing plate of the present invention have excellent polarizing performance. The polarizing film and polarizing plate of the present invention also have excellent durability (moisture resistance, heat resistance, and light fastness). Furthermore, a polarizing film and polarizing plate having a neutral gray color, which are produced by using the azo compound or salt thereof of the present invention in combination with a known organic dichroic dye, exhibit a high-quality hue with extremely little light leakage (color leakage) of orthogonal colors in the visible light wavelength range, and a polarizing plate with excellent polarizing performance and durability can be realized. DETAILED DESCRIPTION OF THE INVENTION

[0015] In this specification and claims, unless it is clearly in a free form, the "azo compound or a salt thereof" may be simply referred to as the "azo compound." In this specification and claims, a "substituent" may include a hydrogen atom, and therefore, for convenience, a hydrogen atom is sometimes described as a "substituent." The phrase "may have a substituent" means that the group may have no substituent. For example, a "phenyl group which may have a substituent" includes a simple unsubstituted phenyl group and a phenyl group which has a substituent.

[0016] The azo compound or a salt thereof of the present invention is represented by the following formula (1) and has a hydroxy group at a specific position.

[0017] [ka] In formula (1), Ar represents a benzene ring which may have a substituent, a naphthalene ring which may have a substituent, or a heterocycle which may have a substituent; R 1 ~R 5 each independently represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C1-C4 alkoxy group having a sulfo group, Q represents an optional substituent, and n represents an integer of 1 to 3).

[0018] In formula (1), the ring structures drawn with solid and broken lines represent a phenyl (phenylene) group or a naphthyl (naphthylene) group.

[0019] In the above formula (1), Ar represents a benzene ring which may have a substituent, a naphthalene ring which may have a substituent, or a heterocycle which may have a substituent, and Q represents an optional substituent. Examples of the optional substituent and the optional substituent represented by Q include a diazenyl group, a heterocyclic amino group, a fused heterocyclic amino group, an alkyl group, an alkoxy group, an alkoxy group having a sulfo group (-SO3H), an aryloxy group, an alkylcarbonylamino group, an arylcarbonylamino group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkylcarbonyl group, an arylcarbonyl group, an alkylcarbamoyl group, an arylcarbamoyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonylamino group, Examples of such an alkyl group include an arylsulfonylamino group, an alkylsulfamoyl group, an arylsulfamoyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkylthio group, an arylthio group, an alkylureido group, an arylureido group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, an alkylamino group, an arylamino group, a hydroxy group (-OH), a cyano group (-CN), a nitro group (-NO2), a mercapto group (-SH), a halogen atom, a carboxy group (-CO2H), a sulfo group (-SO3H), an amino group (-NH2), and a hydrogen atom.

[0020] The heterocyclic amino group includes a 5- or 6-membered heterocyclic amino group containing 1 to 3 heteroatoms selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom. Specific examples of such heterocyclic amino groups include: 5-membered heteroalicyclic amino groups such as pyrrolidinylamino, tetrahydrofurylamino, tetrahydrothiophen-2-ylamino, and tetrahydrothiophen-3-ylamino; 6-membered heteroalicyclic amino groups such as piperidinylamino, piperazinylamino, dioxan-2-ylamino, morpholinylamino, and thiomorpholinylamino; 5-membered aromatic heterocyclic amino groups such as pyrroleamino, pyrazoleamino, imidazoleamino, triazoleamino, furylamino, thiophen-2-ylamino, thiophen-3-ylamino, oxazoleamino, and thiazoleamino; or Examples thereof include 6-membered aromatic heterocyclic amino groups such as pyridylamino, pyrazylamino, pyridazinylamino, and triazinylamino. The heterocyclic ring preferably has a heterocyclic moiety that is an aromatic ring, and the heteroatom constituting the heterocyclic ring is preferably selected from a nitrogen atom and a sulfur atom.

[0021] The fused heterocyclic amino group includes a fused 5- or 6-membered heterocyclic amino group in which one benzene ring is fused to a 5- or 6-membered heterocyclic ring containing 1 to 3 heteroatoms selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom. Specific examples of such a fused heterocyclic amino group include, for example, fused heteroalicyclic amino groups in which the heterocyclic moiety is a five-membered alicyclic ring, such as phthalanylamino; fused heteroalicyclic amino groups in which the heterocyclic moiety is a six-membered alicyclic ring, such as benzopyranylamino; a fused aromatic heterocyclic amino group in which the heterocyclic moiety is an aromatic 5-membered ring, such as benzopyrroleamino, benzopyrazoleamino, benzimidazoleamino, benzotriazoleamino, benzofuranylamino, benzothiophen-2-ylamino, benzothiophen-3-ylamino, benzoxazoleamino, or benzothiazoleamino; or Examples thereof include fused aromatic heterocyclic amino groups in which the heterocyclic moiety is an aromatic 6-membered ring, such as quinolinylamino, cinnolinylamino, phthalazinylamino, quinazolinylamino, and quinoxalinylamino. The heterocyclic ring preferably has a heterocyclic moiety that is an aromatic ring, and the heteroatom constituting the heterocyclic ring is preferably selected from a nitrogen atom and a sulfur atom.

[0022] The alkyl group may be a linear, branched or cyclic alkyl group, preferably a C1-C 10 C1-C alkyl groups.10 Specific examples of the alkyl group include: Straight-chain C1-C alkyl esters such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl 10 alkyl groups; Branched C3-C alkyl esters such as isopropyl, isobutyl, sec-butyl, t-butyl, isoamyl, t-amyl, isohexyl, t-hexyl, isoheptyl, t-heptyl, isooctyl, t-octyl, 2-ethylhexyl, isononyl, and isodecyl. 10 an alkyl group; or Examples include cyclic C3-C7 alkoxy groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, etc. Among these, linear or branched alkyl groups are preferred, and linear C1-C4 alkyl groups are more preferred.

[0023] The alkoxy group may be a linear, branched, or cyclic alkoxy group, preferably a C1-C 10 Alkoxy groups include C1-C 10 Specific examples of the alkoxy group include: Straight-chain C1-C alkoxy groups such as methoxy, ethoxy, n-propoxy, n-butoxy, n-pentoxy, n-hexyloxy, n-heptoxy, n-octyloxy, n-nonyloxy, and n-decyloxy. 10 Alkoxy groups; Branched C3-C alkoxy groups such as isopropoxy, isobutoxy, sec-butoxy, t-butoxy, isoamyloxy, t-amyloxy, isohexyloxy, t-hexyloxy, isoheptoxy, t-heptoxy, isooctyloxy, t-octyloxy, 2-ethylhexyloxy, isononyloxy, and isodecyloxy. 10 an alkoxy group; or Examples include cyclic C3-C7 alkoxy groups such as cyclopropoxy, cyclobutoxy, cyclopentoxy, cyclohexyloxy, cycloheptoxy, etc. Among these, linear or branched alkoxy groups are preferred, and linear C1-C4 alkoxy groups are more preferred.

[0024] Examples of the alkoxy group having a sulfo group (-SO3H) include a C1-C4 alkoxy group having a sulfo group. The C1-C4 alkoxy group having a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably the terminal alkoxy group. More preferred are a 3-sulfopropoxy group and a 4-sulfobutoxy group, and particularly preferred is a 3-sulfopropoxy group.

[0025] The aryloxy group is preferably C6-C 12 It is an aryloxy group, and specific examples include phenoxy, naphthyloxy, biphenyloxy, and the like.

[0026] The alkylcarbonylamino group is a linear, branched or cyclic alkylcarbonylamino group, preferably a C1-C 10 Examples include alkylcarbonylamino groups. 10 Specific examples of the alkylcarbonylamino group include, for example, Straight-chain C1-C methylcarbonylamino (acetylamino), ethylcarbonylamino, n-propylcarbonylamino, n-butylcarbonylamino, n-pentylcarbonylamino, n-hexylcarbonylamino, n-heptylcarbonylamino, n-octylcarbonylamino, n-nonylcarbonylamino, and n-decylcarbonylamino 10 Alkylcarbonylamino group; Branched C3-C arylcarbonylamino such as isopropylcarbonylamino, isobutylcarbonylamino, sec-butylcarbonylamino, t-butylcarbonylamino, isoamylcarbonylamino, t-amylcarbonylamino, isohexylcarbonylamino, t-hexylcarbonylamino, isoheptylcarbonylamino, t-heptylcarbonylamino, isooctylcarbonylamino, t-octylcarbonylamino, 2-ethylhexylcarbonylamino, isononylcarbonylamino, and isodecylcarbonylamino 10 an alkylcarbonylamino group; or Examples include cyclic C3-C7 alkylcarbonylamino groups such as cyclopropylcarbonylamino, cyclobutylcarbonylamino, cyclopentylcarbonylamino, cyclohexylcarbonylamino, cycloheptylcarbonylamino, etc. Among these, linear or branched alkylcarbonylamino groups are preferred, and linear alkylcarbonylamino groups are more preferred.

[0027] The arylcarbonylamino group is preferably C6-C 12 It is an arylcarbonylamino group, and specific examples include phenylcarbonylamino (benzoylamino), naphthylcarbonylamino, biphenylcarbonylamino, and the like.

[0028] The alkylcarbonyloxy group is a linear, branched or cyclic alkylcarbonyloxy group, preferably a C1-C 10 Examples include alkylcarbonyloxy groups. 10 Specific examples of the alkylcarbonyloxy group include, for example, Straight-chain C1-C methylcarbonyloxy, ethylcarbonyloxy, n-propylcarbonyloxy, n-butylcarbonyloxy, n-pentylcarbonyloxy, n-hexylcarbonyloxy, n-heptylcarbonyloxy, n-octylcarbonyloxy, n-nonylcarbonyloxy, and n-decylcarbonyloxy. 10 Alkylcarbonyloxy group; Branched C3-C carbonyloxy such as isopropylcarbonyloxy, isobutylcarbonyloxy, sec-butylcarbonyloxy, t-butylcarbonyloxy, isoamylcarbonyloxy, t-amylcarbonyloxy, isohexylcarbonyloxy, t-hexylcarbonyloxy, isoheptylcarbonyloxy, t-heptylcarbonyloxy, isooctylcarbonyloxy, t-octylcarbonyloxy, 2-ethylhexylcarbonyloxy, isononylcarbonyloxy, and isodecylcarbonyloxy. 10 an alkylcarbonyloxy group; or Examples include cyclic C3-C7 alkylcarbonyloxy groups such as cyclopropylcarbonyloxy, cyclobutylcarbonyloxy, cyclopentylcarbonyloxy, cyclohexylcarbonyloxy, cycloheptylcarbonyloxy, etc. Among these, linear or branched alkylcarbonyloxy groups are preferred, and linear alkylcarbonyloxy groups are more preferred.

[0029] The arylcarbonyloxy group is preferably C6-C 12 It is an arylcarbonyloxy group, and specific examples include phenylcarbonyloxy, naphthylcarbonyloxy, biphenylcarbonyloxy, and the like.

[0030] The alkylcarbonyl group may be a linear, branched, or cyclic alkylcarbonyl group, preferably a C1-C 10 Examples include alkylcarbonyl groups. 10 Specific examples of the alkylcarbonyl group include, for example, Straight-chain C1-C carbonyls such as methylcarbonyl, ethylcarbonyl, n-propylcarbonyl, n-butylcarbonyl, n-pentylcarbonyl, n-hexylcarbonyl, n-heptylcarbonyl, n-octylcarbonyl, n-nonylcarbonyl, and n-decylcarbonyl 10 Alkylcarbonyl group; Branched C3-C carbonyls such as isopropyl carbonyl, isobutyl carbonyl, sec-butyl carbonyl, t-butyl carbonyl, isoamyl carbonyl, t-amyl carbonyl, isohexyl carbonyl, t-hexyl carbonyl, isoheptyl carbonyl, t-heptyl carbonyl, isooctyl carbonyl, t-octyl carbonyl, 2-ethylhexyl carbonyl, isononyl carbonyl, and isodecyl carbonyl 10 an alkylcarbonyl group; or Examples include cyclic C3-C7 alkylcarbonyl groups such as cyclopropylcarbonyl, cyclobutylcarbonyl, cyclopentylcarbonyl, cyclohexylcarbonyl, cycloheptylcarbonyl, etc. Among these, linear or branched alkylcarbonyl groups are preferred, and linear alkylcarbonyl groups are more preferred.

[0031] The arylcarbonyl group is preferably a C6-C 12 It is an arylcarbonyl group, and specific examples include phenylcarbonyl (benzoyl), naphthylcarbonyl, biphenylcarbonyl, and the like.

[0032] The alkylcarbamoyl group may be a linear, branched or cyclic monoalkylcarbamoyl group or a dialkylcarbamoyl group.

[0033] The monoalkylcarbamoyl group is preferably a mono-C-C 10 alkylcarbamoyl groups, and specific examples thereof include: Straight-chain mono C1-C aryls such as methylcarbamoyl, ethylcarbamoyl, n-propylcarbamoyl, n-butylcarbamoyl, n-pentylcarbamoyl, n-hexylcarbamoyl, n-heptylcarbamoyl, n-octylcarbamoyl, n-nonylcarbamoyl, and n-decylcarbamoyl 10 Alkylcarbamoyl group; Branched-chain mono C3-C aryls such as isopropylcarbamoyl, isobutylcarbamoyl, sec-butylcarbamoyl, t-butylcarbamoyl, isoamylcarbamoyl, t-amylcarbamoyl, isohexylcarbamoyl, t-hexylcarbamoyl, isoheptylcarbamoyl, t-heptylcarbamoyl, isooctylcarbamoyl, t-octylcarbamoyl, 2-ethylhexylcarbamoyl, isononylcarbamoyl, and isodecylcarbamoyl 10 an alkylcarbamoyl group; or Examples of such cyclic mono-C3-C7 alkylcarbamoyl groups include cyclopropylcarbamoyl, cyclobutylcarbamoyl, cyclopentylcarbamoyl, cyclohexylcarbamoyl, cycloheptylcarbamoyl, etc. Among these, linear or branched mono-alkylcarbamoyl groups are preferred, and linear mono-alkylcarbamoyl groups are more preferred.

[0034] The dialkylcarbamoyl group is preferably a di-C1-C 10 alkylcarbamoyl groups, and specific examples thereof include: Linear di-C1-C aryls such as dimethylcarbamoyl, diethylcarbamoyl, di-n-propylcarbamoyl, di-n-butylcarbamoyl, di-n-pentylcarbamoyl, di-n-hexylcarbamoyl, di-n-heptylcarbamoyl, di-n-octylcarbamoyl, di-n-nonylcarbamoyl, and di-n-decylcarbamoyl 10 Alkylcarbamoyl group; Branched di-C3-C alkyl esters with two branched chains, such as diisopropylcarbamoyl, diisobutylcarbamoyl, di-sec-butylcarbamoyl, di-t-butylcarbamoyl, diisoamylcarbamoyl, di-t-amylcarbamoyl, diisohexylcarbamoyl, di-t-hexylcarbamoyl, diisoheptylcarbamoyl, di-t-heptylcarbamoyl, diisooctylcarbamoyl, di-t-octylcarbamoyl, di-(2-ethylhexyl)carbamoyl, diisononylcarbamoyl, and diisodecylcarbamoyl. 10 an alkylcarbamoyl group; or Examples of such cyclic diC3-C7 alkylcarbamoyl groups include dicyclopropylcarbamoyl, dicyclobutylcarbamoyl, dicyclopentylcarbamoyl, dicyclohexylcarbamoyl, dicycloheptylcarbamoyl, etc. Among these, linear or branched dialkylcarbamoyl groups are preferred, and linear dialkylcarbamoyl groups are more preferred.

[0035] The arylcarbamoyl group includes a monoarylcarbamoyl group and a diarylcarbamoyl group.

[0036] The monoarylcarbamoyl group is preferably a mono C-C 12 It is an arylcarbamoyl group, and specific examples include phenylcarbamoyl, naphthylcarbamoyl, biphenylcarbamoyl, and the like.

[0037] The diarylcarbamoyl group is preferably a di-C6-C 12 It is an arylcarbamoyl group, and specific examples include diphenylcarbamoyl, dinaphthylcarbamoyl, di(biphenyl)carbamoyl, and the like.

[0038] The alkoxycarbonyl group may be a linear, branched, or cyclic alkoxycarbonyl group, preferably a C1-C 10 Examples include alkoxycarbonyl groups. C1-C 10 Specific examples of the alkoxycarbonyl group include: For example, straight-chain C1-C alkoxycarbonyls such as methoxycarbonyl, ethoxycarbonyl, n-propoxycarbonyl, n-butoxycarbonyl, n-pentoxycarbonyl, n-hexyloxycarbonyl, n-heptoxycarbonyl, n-octyloxycarbonyl, n-nonyloxycarbonyl, and n-decyloxycarbonyl. 10 alkoxycarbonyl groups; Branched C3-C carbonyls such as isopropoxycarbonyl, isobutoxycarbonyl, sec-butoxycarbonyl, t-butoxycarbonyl, isoamyloxycarbonyl, t-amyloxycarbonyl, isohexyloxycarbonyl, t-hexyloxycarbonyl, isoheptoxycarbonyl, t-heptoxycarbonyl, isooctyloxycarbonyl, t-octyloxycarbonyl, 2-ethylhexyloxycarbonyl, isononyloxycarbonyl, and isodecyloxycarbonyl 10 an alkoxycarbonyl group; or Examples include cyclic C3-C7 alkoxycarbonyl groups such as cyclopropoxycarbonyl, cyclobutoxycarbonyl, cyclopentoxycarbonyl, cyclohexyloxycarbonyl, cycloheptoxycarbonyl, etc. Among these, linear or branched alkoxycarbonyl groups are preferred, and linear alkoxycarbonyl groups are more preferred.

[0039] The aryloxycarbonyl group is preferably C6-C 12 It is an aryloxycarbonyl group, and specific examples include phenoxycarbonyl, naphthyloxycarbonyl, biphenyloxycarbonyl, and the like.

[0040] The alkylsulfonylamino group may be a linear, branched or cyclic alkylsulfonylamino group, preferably a C1-C 10 alkylsulfonylamino groups. 10 Specific examples of the alkylsulfonylamino group include, for example, Straight-chain C1-C sulfonylamino, such as methylsulfonylamino, ethylsulfonylamino, n-propylsulfonylamino, n-butylsulfonylamino, n-pentylsulfonylamino, n-hexylsulfonylamino, n-heptylsulfonylamino, n-octylsulfonylamino, n-nonylsulfonylamino, and n-decylsulfonylamino 10 Alkylsulfonylamino group; Branched C3-C sulfonylamino such as isopropylsulfonylamino, isobutylsulfonylamino, sec-butylsulfonylamino, t-butylsulfonylamino, isoamylsulfonylamino, t-amylsulfonylamino, isohexylsulfonylamino, t-hexylsulfonylamino, isoheptylsulfonylamino, t-heptylsulfonylamino, isooctylsulfonylamino, t-octylsulfonylamino, 2-ethylhexylsulfonylamino, isononylsulfonylamino, and isodecylsulfonylamino 10 an alkylsulfonylamino group; or Examples of such cyclic C3-C7 alkylsulfonylamino groups include cyclopropylsulfonylamino, cyclobutylsulfonylamino, cyclopentylsulfonylamino, cyclohexylsulfonylamino, cycloheptylsulfonylamino, etc. Among these, linear or branched alkylsulfonylamino groups are preferred, and linear alkylsulfonylamino groups are more preferred.

[0041] The arylsulfonylamino group is preferably C6-C 12 It is an arylsulfonylamino group, and specific examples include phenylsulfonylamino, toluenesulfonylamino, naphthylsulfonylamino, biphenylsulfonylamino, and the like.

[0042] The alkylsulfamoyl group may be a linear, branched or cyclic monoalkylsulfamoyl group or a dialkylsulfamoyl group.

[0043] The monoalkylsulfamoyl group is preferably mono C-C 10 It is an alkylsulfamoyl group, and specific examples thereof include: Straight-chain mono C1-C methylsulfamoyl, ethylsulfamoyl, n-propylsulfamoyl, n-butylsulfamoyl, n-pentylsulfamoyl, n-hexylsulfamoyl, n-heptylsulfamoyl, n-octylsulfamoyl, n-nonylsulfamoyl, and n-decylsulfamoyl 10 Alkylsulfamoyl group; Branched-chain mono C3-C alkyl esters such as isopropylsulfamoyl, isobutylsulfamoyl, sec-butylsulfamoyl, t-butylsulfamoyl, isoamylsulfamoyl, t-amylsulfamoyl, isohexylsulfamoyl, t-hexylsulfamoyl, isoheptylsulfamoyl, t-heptylsulfamoyl, isooctylsulfamoyl, t-octylsulfamoyl, 2-ethylhexylsulfamoyl, isononylsulfamoyl, and isodecylsulfamoyl 10 an alkylsulfamoyl group; or Examples of such groups include cyclic mono C3-C7 alkylsulfamoyl groups, such as cyclopropylsulfamoyl, cyclobutylsulfamoyl, cyclopentylsulfamoyl, cyclohexylsulfamoyl, and cycloheptylsulfamoyl. Among these, linear or branched monoalkylsulfamoyl groups are preferred, and linear monoalkylsulfamoyl groups are more preferred.

[0044] The dialkylsulfamoyl group is preferably a di-C-C 10 It is an alkylsulfamoyl group, and specific examples thereof include: Straight-chain di-C1-C dimethylsulfamoyl, diethylsulfamoyl, di-n-propylsulfamoyl, di-n-butylsulfamoyl, di-n-pentylsulfamoyl, di-n-hexylsulfamoyl, di-n-heptylsulfamoyl, di-n-octylsulfamoyl, di-n-nonylsulfamoyl, and di-n-decylsulfamoyl 10 Alkylsulfamoyl group; Branched chain di-C3-C alkyl esters having two branched chains, such as diisopropylsulfamoyl, diisobutylsulfamoyl, di-sec-butylsulfamoyl, di-t-butylsulfamoyl, diisoamylsulfamoyl, di-t-amylsulfamoyl, diisohexylsulfamoyl, di-t-hexylsulfamoyl, diisoheptylsulfamoyl, di-t-heptylsulfamoyl, diisooctylsulfamoyl, di-t-octylsulfamoyl, di-(2-ethylhexyl)sulfamoyl, diisononylsulfamoyl, and diisodecylsulfamoyl. 10 an alkylsulfamoyl group; or Examples of such groups include cyclic diC3-C7 alkylsulfamoyl groups having two rings, such as dicyclopropylsulfamoyl, dicyclobutylsulfamoyl, dicyclopentylsulfamoyl, dicyclohexylsulfamoyl, and dicycloheptylsulfamoyl. Among these, linear or branched dialkylsulfamoyl groups are preferred, and linear dialkylsulfamoyl groups are more preferred.

[0045] The arylsulfamoyl group includes a monoarylsulfamoyl group and a diarylsulfamoyl group.

[0046] The monoarylsulfamoyl group is preferably a mono C-C 12 It is an arylsulfamoyl group, and specific examples include phenylsulfamoyl, naphthylsulfamoyl, biphenylsulfamoyl, and the like.

[0047] The diarylsulfamoyl group is preferably a di-C-C 12 It is an arylsulfamoyl group, and specific examples include diphenylsulfamoyl, dinaphthylsulfamoyl, di(biphenyl)sulfamoyl, and the like.

[0048] The alkylsulfonyl group may be a linear, branched or cyclic alkylsulfonyl group, preferably a C1-C 12 Examples include alkylsulfonyl groups. 12 Specific examples of the alkylsulfonyl group include, for example, Linear C1-C sulfonyl groups such as methylsulfonyl, ethylsulfonyl, n-propylsulfonyl, n-butylsulfonyl, n-pentylsulfonyl, n-hexylsulfonyl, n-heptylsulfonyl, n-octylsulfonyl, n-nonylsulfonyl, n-decylsulfonyl, n-undecylsulfonyl, and n-dodecylsulfonyl 12 Alkylsulfonyl groups; Branched C3-C sulfonyl groups such as isopropylsulfonyl, isobutylsulfonyl, sec-butylsulfonyl, t-butylsulfonyl, isoamylsulfonyl, t-amylsulfonyl, isohexylsulfonyl, t-hexylsulfonyl, isoheptylsulfonyl, t-heptylsulfonyl, isooctylsulfonyl, t-octylsulfonyl, 2-ethylhexylsulfonyl, isononylsulfonyl, isodecylsulfonyl, isoundecylsulfonyl, t-undecylsulfonyl, isododecylsulfonyl, and t-dodecylsulfonyl 12 an alkylsulfonyl group; or Examples include cyclic C3-C7 alkylsulfonyl groups such as cyclopropylsulfonyl, cyclobutylsulfonyl, cyclopentylsulfonyl, cyclohexylsulfonyl, cycloheptylsulfonyl, etc. Among these, linear or branched alkylsulfonyl groups are preferred, and linear alkylsulfonyl groups are more preferred.

[0049] The arylsulfonyl group is preferably C6-C 12 It is an arylsulfonyl group, and specific examples include phenylsulfonyl, naphthylsulfonyl, biphenylsulfonyl, and the like.

[0050] The alkylthio group may be a linear, branched or cyclic alkylthio group, preferably a C1-C 10 Examples include alkylthio groups. 10 Specific examples of the alkylthio group include, for example, Straight-chain C1-C thiols such as methylthio, ethylthio, n-propylthio, n-butylthio, n-pentylthio, n-hexylthio, n-heptylthio, n-octylthio, n-nonylthio, and n-decylthio. 10 Alkylthio groups; Branched C3-C thiols such as isopropylthio, isobutylthio, sec-butylthio, t-butylthio, isoamylthio, t-amylthio, isohexylthio, t-hexylthio, isoheptylthio, t-heptylthio, isooctylthio, t-octylthio, 2-ethylhexylthio, isononylthio, and isodecylthio. 10 an alkylthio group; or Examples include cyclic C3-C7 alkylthio groups such as cyclopropylthio, cyclobutylthio, cyclopentylthio, cyclohexylthio, cycloheptylthio, etc. Among these, linear or branched alkylthio groups are preferred, and linear alkylthio groups are more preferred.

[0051] The arylthio group is preferably C6-C 12It is an arylthio group, and specific examples include phenylthio, naphthylthio, biphenylthio, and the like.

[0052] The alkylureido group may be a linear, branched or cyclic monoalkylureido group or a dialkylureido group.

[0053] The monoalkylureido group is preferably a mono C-C 10 It is an alkylureido group, and specific examples thereof include, for example, Linear mono C1-C ureido such as methylureido, ethylureido, n-propylureido, n-butylureido, n-pentylureido, n-hexylureido, n-heptylureido, n-octylureido, n-nonylureido, and n-decylureido 10 Alkylureido group; Branched-chain mono C3-C ureido such as isopropyl ureido, isobutyl ureido, sec-butyl ureido, t-butyl ureido, isoamyl ureido, t-amyl ureido, isohexyl ureido, t-hexyl ureido, isoheptyl ureido, t-heptyl ureido, isooctyl ureido, t-octyl ureido, 2-ethylhexyl ureido, isononyl ureido, and isodecyl ureido 10 an alkylureido group; or Examples of such alkylureido groups include cyclic mono C3-C7 alkylureido groups such as cyclopropylureido, cyclobutylureido, cyclopentylureido, cyclohexylureido, and cycloheptylureido. Among these, linear or branched alkylureido groups are preferred, and examples thereof include linear alkylureido groups.

[0054] The dialkylureido group is preferably a diC-C 10 It is an alkylureido group, and specific examples thereof include, for example, Linear di-C1-C ureido such as dimethylureido, diethylureido, di-n-propylureido, di-n-butylureido, di-n-pentylureido, di-n-hexylureido, di-n-heptylureido, di-n-octylureido, di-n-nonylureido, and di-n-decylureido 10 Alkylureido group; Branched chain di-C3-C alkyl esters with two branched chains, such as diisopropyl ureide, diisobutyl ureide, di-sec-butyl ureide, di-t-butyl ureide, diisoamyl ureide, di-t-amyl ureide, diisohexyl ureide, di-t-hexyl ureide, diisoheptyl ureide, di-t-heptyl ureide, diisooctyl ureide, di-t-octyl ureide, di-(2-ethylhexyl) ureide, diisononyl ureide, and diisodecyl ureide 10 an alkylureido group; or Examples of such alkylureido groups include cyclic diC3-C7 alkylureido groups having two rings, such as dicyclopropylureido, dicyclobutylureido, dicyclopentylureido, dicyclohexylureido, and dicycloheptylureido. Among these, linear or branched dialkylureido groups are preferred, and linear dialkylureido groups are more preferred.

[0055] The arylureido group includes a monoarylureido group and a diarylureido group.

[0056] The monoarylureido group is preferably a mono C-C 12 It is an arylureido group, and specific examples include phenylureido, naphthylureido, biphenylureido, and the like.

[0057] The diarylureido group is preferably a di-C-C 12 It is an arylureido group, and specific examples include diphenylureido, dinaphthylureido, and di(biphenyl)ureido.

[0058] The alkoxycarbonylamino group may be a linear, branched, or cyclic alkoxycarbonylamino group, preferably a C1-C 10 Examples include alkoxycarbonylamino groups. 10 Specific examples of the alkoxycarbonylamino group include, for example, Straight-chain C1-C alkoxycarbonylamino, such as methoxycarbonylamino, ethoxycarbonylamino, n-propoxycarbonylamino, n-butoxycarbonylamino, n-pentoxycarbonylamino, n-hexyloxycarbonylamino, n-heptoxycarbonylamino, n-octyloxycarbonylamino, n-nonyloxycarbonylamino, and n-decyloxycarbonylamino. 10 Alkoxycarbonylamino group; Branched C3-C carbonylamino such as isopropoxycarbonylamino, isobutoxycarbonylamino, sec-butoxycarbonylamino, t-butoxycarbonylamino, isoamyloxycarbonylamino, t-amyloxycarbonylamino, isohexyloxycarbonylamino, t-hexyloxycarbonylamino, isoheptoxycarbonylamino, t-heptoxycarbonylamino, isooctyloxycarbonylamino, t-octyloxycarbonylamino, 2-ethylhexyloxycarbonylamino, isononyloxycarbonylamino, and isodecyloxycarbonylamino 10 an alkoxycarbonylamino group; or Examples of cyclic C3-C7 alkoxycarbonylamino groups include cyclopropoxycarbonylamino, cyclobutoxycarbonylamino, cyclopentoxycarbonylamino, cyclohexyloxycarbonylamino, cycloheptoxycarbonylamino, etc. Among these, linear or branched alkoxycarbonylamino groups are preferred, and linear alkoxycarbonylamino groups are more preferred.

[0059] The aryloxycarbonylamino group is preferably a C6-C 12 It is an aryloxycarbonylamino group, and specific examples include phenylcarbonylamino, naphthylcarbonylamino, biphenylcarbonylamino, and the like.

[0060] The alkylamino group may be a linear, branched, or cyclic monoalkylamino group or dialkylamino group.

[0061] The monoalkylamino group is preferably mono C-C 10 It is an alkylamino group, and specific examples thereof include: Straight-chain mono C1-C amino acids such as methylamino, ethylamino, n-propylamino, n-butylamino, n-pentylamino, n-hexylamino, n-heptylamino, n-octylamino, n-nonylamino, and n-decylamino 10 alkylamino groups; Branched-chain mono C3-C amino acids such as isopropylamino, isobutylamino, sec-butylamino, t-butylamino, isoamylamino, t-amylamino, isohexylamino, t-hexylamino, isoheptylamino, t-heptylamino, isooctylamino, t-octylamino, 2-ethylhexylamino, isononylamino, and isodecylamino 10 an alkylamino group; or Examples include cyclic mono C3-C7 alkylamino groups such as cyclopropylamino, cyclobutylamino, cyclopentylamino, cyclohexylamino, cycloheptylamino, etc. Among these, linear or branched monoalkylamino groups are preferred, and linear monoalkylamino groups are more preferred.

[0062] The dialkylamino group is preferably a di-C-C 10 It is an alkylamino group, and specific examples thereof include: Straight-chain di-C1-C amino acids such as dimethylamino, diethylamino, di-n-propylamino, di-n-butylamino, di-n-pentylamino, di-n-hexylamino, di-n-heptylamino, di-n-octylamino, di-n-nonylamino, and di-n-decylamino 10 alkylamino groups; Branched di-C3-C amino groups having two branched chains, such as diisopropylamino, diisobutylamino, di-sec-butylamino, di-t-butylamino, diisoamylamino, di-t-amylamino, diisohexylamino, di-t-hexylamino, diisoheptylamino, di-t-heptylamino, diisooctylamino, di-t-octylamino, di-(2-ethylhexyl)amino, diisononylamino, and diisodecylamino 10 an alkylamino group; or Examples of such alkylamino groups include cyclic di-C3-C7 alkylamino groups having two rings, such as dicyclopropylamino, dicyclobutylamino, dicyclopentylamino, dicyclohexylamino, dicycloheptylamino, etc. Among these, linear or branched dialkylamino groups are preferred, and linear dialkylamino groups are more preferred.

[0063] The arylamino group may be a monoarylamino group or a diarylamino group.

[0064] The monoarylamino group is preferably a mono C-C 12 It is an arylamino group, and specific examples include phenylamino (anilino), naphthylamino, biphenylamino, and the like.

[0065] The diarylamino group is preferably a di-C-C 12 It is an arylamino group, and specific examples include diphenylamino, dinaphthylamino, and di(biphenyl)amino.

[0066] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a fluorine atom, a chlorine atom, or a bromine atom being preferred.

[0067] More preferred examples of Q include a hydrogen atom, a chlorine atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C1-C4 alkoxy group having a sulfo group, a nitro group, a carboxy group, and a sulfo group.

[0068] In the above formula (1), Ar represents a benzene ring which may have a substituent, a naphthalene ring which may have a substituent, or a heterocycle which may have a substituent. When Ar is a heterocycle, examples thereof include a 5- or 6-membered heterocycle containing 1 to 3 heteroatoms selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom. Specific examples of such heterocycles include, for example, Alicyclic five-membered heterocyclic rings such as pyrrolidine, tetrahydrofuran, and tetrahydrothiophene; Alicyclic six-membered heterocyclic rings such as piperidine, piperazine, dioxane, morpholine, and thiomorpholine; Aromatic five-membered heterocyclic rings such as pyrrole, pyrazole, imidazole, triazole, furan, thiophene, oxazole, and thiazole; Aromatic six-membered heterocyclic rings such as pyridine, pyrazine, pyridazine, and triazine; fused aliphatic heterocycles with five-membered alicyclic heterocyclic moieties such as phthalane, indoline, and isoindoline; A fused aromatic heterocycle in which the heterocyclic moiety is an aromatic 5-membered ring, such as benzopyrrole, benzopyrazole, benzimidazole, benzotriazole, benzofuranyl, benzothiophene, benzoxazole, benzothiazole, or naphthothiazole; or Examples include condensed aromatic heterocycles in which the heterocyclic moiety is an aromatic 6-membered ring, such as quinoline, cinnoline, phthalazine, quinazoline, and quinoxaline. The heterocyclic ring preferably has a heterocyclic moiety that is an aromatic ring, and the heteroatom constituting the heterocyclic ring is preferably selected from a nitrogen atom and a sulfur atom.

[0069] In formula (1), R 1 ~R 5 each independently represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C1-C4 alkoxy group having a sulfo group; and n represents an integer of 1 to 3.

[0070] In formula (1), examples of the "C1-C4 alkyl group" include straight-chain alkyl groups such as methyl, ethyl, n-propyl, and n-butyl, and branched-chain alkyl groups such as sec-butyl and tert-butyl.

[0071] In formula (1), examples of the "C1-C4 alkoxy group" include a methoxy group, an ethoxy group, a propoxy group, an n-butoxy group, a sec-butoxy group, and a tert-butoxy group.

[0072] In formula (1), the "C1-C4 alkoxy group having a sulfo group" is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably the terminal alkoxy group. More preferred are 3-sulfopropoxy and 4-sulfobutoxy groups, and particularly preferred is 3-sulfopropoxy.

[0073] Preferred R 1 ~R 5 represents a hydrogen atom, a methyl group, or a methoxy group, and n is preferably 2 or 3.

[0074] When the azo compound represented by formula (1) or a salt thereof is an azo compound represented by the following formula (2) or a salt thereof, a polarizing film with higher transmittance and a higher polarization degree can be provided, which is preferable.

[0075] [ka] (In formula (2), R 1 ~R 6 each independently represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C1-C4 alkoxy group having a sulfo group, and n represents an integer of 1 to 3).

[0076] In formula (2), the ring structures drawn with solid and broken lines represent a phenyl (phenylene) group or a naphthyl (naphthylene) group.

[0077] In the above formula (2), R 1 ~R 6 each independently represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C1-C4 alkoxy group having a sulfo group, and n represents an integer of 1 to 3. 1 ~R 5is a hydrogen atom, a methyl group, or a methoxy group, and preferred R 6 represents a hydrogen atom, a methyl group, or a methoxy group, and n is preferably 2 or 3.

[0078] The azo compound represented by formula (2) or a salt thereof is more preferably an azo compound represented by the following formula (3) or a salt thereof.

[0079] [ka] (In the above formula (3), R 6 represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C1-C4 alkoxy group having a sulfo group, and n represents an integer of 1 to 3).

[0080] In the above formula (3), R 6 has the same meaning as in formula (2), and is preferably a hydrogen atom, a methyl group, or a methoxy group. Furthermore, n represents an integer of 1 to 3, and preferably n is 2 or 3.

[0081] The azo compound represented by the above formula (1) or a salt thereof can be easily produced by known diazotization and coupling processes according to the usual azo dye production methods described in Non-Patent Document 1 and Patent Documents 3 to 5. Introduction of a hydroxy group at a specific position can be achieved by synthesizing a known coppered azo compound dye by the method described in Patent Document 9, followed by a decopperization reaction described in Patent Document 10. An example of a typical synthesis method is shown below.

[0082] First, according to the procedures described in Patent Documents 3 to 5, a tetrakisazo compound represented by the following formula (A) is obtained.

[0083] [ka] (In formula (A), Q, Ar, R 1 ~R 5 , n have the same meaning as in formula (1).

[0084] Next, this tetrakis azo compound (A) is copperized by a known method such as that described in Patent Document 9 to obtain a tetrakis azo copper compound (B).

[0085] [ka] (In formula (B), Q, Ar, R 1 ~R 5 , n have the same meaning as in formula (1).

[0086] Next, the azo compound of formula (1) is obtained by decoupling the compound of formula (B) by a known method such as that described in Patent Document 10.

[0087] After the completion of the decopperization reaction, the azo compound of formula (1) is precipitated by salting out and filtered. If purification is required, the salting out process may be repeated or the compound may be precipitated from water using an organic solvent. Examples of organic solvents used for purification include water-soluble organic solvents such as alcohols (e.g., methanol, ethanol) and ketones (e.g., acetone).

[0088] Specific examples of the azo compound represented by the formula (1) or a salt thereof are listed below. The azo compound is represented in the form of a free acid.

[0089] [ka]

[0090] [ka]

[0091] [ka]

[0092] [ka]

[0093] [ka]

[0094] [ka]

[0095] The azo compound represented by formula (1) may be in the form of a free acid or a salt, or may be a salt of a metal ion or an ammonium ion. Examples of metal ions include alkali metal ions such as lithium ion, sodium ion, and potassium ion, and alkaline earth metal ions such as calcium ion and magnesium ion. Examples of ammonium ions include ammonium ion, methylammonium ion, dimethylammonium ion, triethylammonium ion, tetraethylammonium ion, tetra-n-propylammonium ion, tetra-n-butylammonium ion, monoethanolammonium ion, diethanolammonium ion, triethanolammonium ion, and N-methyl-N-monoethanolammonium ion. More specifically, for example, the free acid represents sulfonic acid (-SO3H), the sodium ion represents sodium sulfonate (-SO3Na), and the ammonium ion represents ammonium sulfonate (-SO3NH4).

[0096] <Polarizing film> The polarizing film of the present invention contains, as a dichroic dye, one or more azo compounds represented by the above formula (1) or salts thereof, and may further contain, as necessary, one or more organic dyes other than the azo compound represented by the above formula (1). The other organic dye is not particularly limited, but is preferably a dye having absorption characteristics in a wavelength range different from the absorption wavelength range of the azo compound represented by the above formula (1) or salts thereof and having high dichroic properties. Representative examples of other organic dyes include CI Direct Yellow 12, CI Direct Yellow 28, CI Direct Yellow 44, CI Direct Orange 26, CI Direct Orange 39, CI Direct Orange 71, CI Direct Orange 107, CI Direct Red 2, CI Direct Red 31, CI Direct Red 79, CI Direct Red 81, CI Direct Red 247, CI Direct Blue 69, CI Direct Green 80, and CI Direct Green 59, as well as dyes described in Non-Patent Document 2. However, depending on the purpose, it is preferable to use dyes developed for polarizing plates such as those described in Patent Documents 1 to 4. These organic dyes are used as free acids, alkali metal salts (e.g., sodium salts, potassium salts, and lithium salts), ammonium salts, or salts of amines. When the polarizing film of the present invention has a single transmittance (Ts) adjusted to 40 to 45%, it is possible to obtain a polarizing film having excellent polarizing performance with a dichroic ratio of 40 to 45, more preferably 45 or more.

[0097] The polarizing film of the present invention, which is produced using the azo compound represented by formula (1) or its salt as a dichroic dye and another dichroic dye, is a neutral gray polarizing film, a paper white polarizing film, a color polarizing film, etc., and can be used depending on the application. Here, "neutral gray" means that when two polarizing films are superimposed so that their orientation directions are perpendicular to each other (hereinafter also referred to as "orthogonal orientation"), there is little light leakage (color leakage) of a specific wavelength in the visible light wavelength range.

[0098] When the azo compound of formula (1) or its salt is used in combination with multiple dichroic dyes, the blending ratio of the organic dyes to be blended varies depending on whether the target polarizing film is a neutral gray polarizing film, a paper white polarizing film, or a color polarizing film. The blending ratio is not particularly limited, but generally, the total amount of at least one or more other organic dyes is preferably in the range of 0.01 to 100 parts by mass, more preferably 0.1 to 10 parts by mass, per part by mass of the azo compound of formula (1) or its salt.

[0099] When the intended polarizing film is a neutral gray polarizing film, the types and blending ratios of other organic dyes used in combination are adjusted so that the resulting polarizing film will have less color leakage in the visible light wavelength region.

[0100] When the intended polarizing film is a paper white polarizing film, the types and blending ratios of other dichroic dyes used in combination are adjusted so that the resulting polarizing film has a uniform transmittance in the visible light wavelength range.

[0101] When the intended polarizing film is a color polarizing film, the types and blending ratios of other organic dyes used in combination are adjusted so that the resulting polarizing film has a high single-plate average light transmittance in a specific wavelength range and a low average light transmittance in the orthogonal direction.

[0102] The polarizing film of the present invention can be produced by incorporating a dichroic dye containing the azo compound represented by the above formula (1) or a salt thereof and, if necessary, other dyes into a substrate (also referred to as a "polarizing film substrate") by a known method and orienting the resulting dyes.

[0103] The substrate is preferably a polymer film, more preferably a film made of polyvinyl alcohol resin or its derivatives. Specific examples of the substrate include polyvinyl alcohol resin and those modified with olefins such as ethylene and propylene, or unsaturated carboxylic acids such as crotonic acid, acrylic acid, methacrylic acid, and maleic acid. A film made of polyvinyl alcohol resin or its derivatives is preferably used as the substrate from the viewpoint of dye adsorption and orientation. The thickness of the substrate is usually 10 to 100 μm, and preferably about 20 to 80 μm.

[0104] When the substrate is a polymer film, the azo compound of formula (1) or its salt is usually incorporated by dyeing the polymer film. Dyeing can be performed, for example, as follows: First, a dye bath is prepared by dissolving the azo compound of formula (1) or its salt, and, if necessary, other organic dyes, in water. The dye concentration in the dye bath is not particularly limited, but is usually selected from the range of about 0.001 to 10% by mass. If necessary, a dyeing assistant may be used; for example, it is preferable to use mirabilite at a concentration of about 0.1 to 10% by mass. The polymer film can be immersed in the dye bath prepared in this manner for, for example, 1 to 10 minutes to dye it. The dyeing temperature is preferably about 30 to 80°C.

[0105] Orientation of the azo compound represented by formula (1) or its salt is achieved by stretching a polymer film dyed with a dichroic dye. The stretching ratio is generally 2 to 9 times, preferably 3 to 8 times, and more preferably 4 to 7 times. Any known stretching method, such as a wet method or a dry method, may be used. Stretching of the polymer film may be performed before dyeing, as needed. In this case, orientation of the water-soluble dye occurs at the time of dyeing. The oriented polymer film containing the water-soluble dye may be subjected to post-treatment, such as boric acid treatment, by a known method, as needed. This post-treatment is performed to improve the light transmittance and polarization degree of the polarizing film. The conditions for 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 boric acid aqueous solution is generally, for example, 0.1 to 15% by mass, preferably 1 to 10% by mass, at a treatment temperature of 30 to 80°C, preferably 40 to 75°C, and the film is immersed for 0.5 to 10 minutes. Furthermore, if necessary, a fixing treatment may also be carried out using an aqueous solution containing a cationic polymer compound.

[0106] <Polarizing plate> The polarizing plate of the present invention (hereinafter also referred to as a "dye-based polarizing plate") can be obtained by forming a transparent protective film on one or both sides of a polarizing film prepared using the dye of the present invention as a dye for the blue to green region. Materials for forming the transparent protective film are preferably those having excellent optical transparency, mechanical strength, thermal stability, moisture-blocking properties, etc. Examples of such materials include, but are not limited to, cellulose acetate films, acrylic films, fluorine-based films such as tetrafluoroethylene / hexafluoropropylene copolymers, and films made of polyester resins, polyolefin resins, or polyamide resins. The transparent protective film is preferably a triacetyl cellulose (TAC) film or a cycloolefin film, and its thickness is preferably typically 10 to 200 μm. The transparent protective film is not limited to films. A protective layer made of an organic or inorganic composition or a mixture thereof made of a material having excellent optical transparency, mechanical strength, thermal stability, moisture-blocking properties, etc. may also be formed on the polarizing film.

[0107] Furthermore, the polarizing film can be applied as a support-integrated polarizing plate in which a transparent substrate having a thickness greater than that of the film is attached to one or both sides of the polarizing film. Supports can be broadly divided into inorganic substrates and organic substrates, and examples of such substrates include inorganic substrates such as soda glass, borosilicate glass, quartz substrates, sapphire substrates, and spinel substrates, and organic substrates such as acrylic, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, and polyolefin.

[0108] The polarizing plate can use an adhesive or pressure-sensitive adhesive to bond the polarizing film to the transparent protective film or protective substrate. Examples of the adhesive include a heat-curable adhesive and an ultraviolet-curable adhesive, and examples of the adhesive include, but are not limited to, a polyvinyl alcohol adhesive, a urethane emulsion adhesive, an acrylic adhesive, and a polyester-isocyanate adhesive. For the purpose of improving adhesive strength or water resistance, a crosslinking agent, a water-resistant agent, an additive, etc. may be added to the adhesive. These are not particularly limited and can be selected appropriately.

[0109] A transparent protective layer or functional layer may be further provided on one or both sides of the polarizing plate on which the transparent protective film or the like is formed. Examples of transparent protective layers include hard coat layers made of acrylic, polysiloxane, or urethane materials. To further improve the unit transmittance, functional layers such as an antireflection layer (such as an antireflection layer or a low-reflection layer, or a combination thereof), an antiglare layer (antiglare layer), or an antifouling layer may be provided on the transparent protective film, transparent substrate, or transparent protective layer. The antireflection layer can be formed by vapor deposition or sputtering of a material such as silicon dioxide or titanium oxide, or by thinly coating a fluorine-based material.

[0110] An optical member may be laminated on one or both sides of the polarizing plate, or may be directly attached to the polarizing film. Examples of the optical member include a cover glass, a light diffusion film, and a retardation film.

[0111] For example, retardation films include retardation films made of transparent resins such as polycarbonate resins, and retardation films made of liquid crystal coatings. The polarizing plate and retardation film can be attached to each other via an adhesive or pressure-sensitive adhesive. A polarizing plate attached with a retardation film becomes an elliptical polarizing plate or a circular polarizing plate, and can be appropriately selected depending on the display device used to provide viewing angle compensation effects, interfacial reflection prevention effects, etc.

[0112] A support may be provided on one or both sides of the polarizing plate of the present invention, and the polarizing plate may be used as a support-attached polarizing plate. The support preferably has a flat surface for attaching the polarizing plate, and is preferably a transparent substrate because it is used for optical purposes. Transparent substrates are broadly divided into inorganic substrates and organic substrates, and examples thereof include inorganic substrates such as soda glass, borosilicate glass, quartz substrates, sapphire substrates, and spinel substrates, and organic substrates such as acrylic, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, and cycloolefin polymers.

[0113] In order to bond the polarizing plate to an optical member or a support, an adhesive layer may be formed on one or both sides of the polarizing plate. The adhesive layer formed can be an adhesive or a pressure-sensitive adhesive, but pressure-sensitive adhesives such as acrylic resin, polyester resin, and polyurethane resin are preferably used. The pressure-sensitive adhesive used is not limited to these and can be selected appropriately depending on the application and the member.

[0114] The polarizing plate of the present invention may be any of a neutral gray polarizing plate, a paper white polarizing plate, and a color polarizing plate depending on the application. These polarizing plates have excellent polarization performance and are further prevented from discoloring or decreasing in polarization performance even under high-temperature and high-humidity conditions, and are therefore suitable for in-vehicle or outdoor displays.

[0115] <Display device> The display device of the present invention includes the polarizing film or polarizing plate of the present invention. Examples of the display device include known liquid crystal display devices, projectors, and organic electronics display devices, and are applicable to, but not limited to, displays for calculators, clocks, laptops, LCD televisions, car navigation systems, and indoor and outdoor measuring instruments and displays. The polarizing film or polarizing plate is particularly suitable for various displays requiring high polarization performance and durability, such as in-vehicle displays or outdoor displays (e.g., displays for industrial instruments or wearable applications). The dye-based polarizing film or dye-based polarizing plate included in the display device is preferably neutral gray.

[0116] For example, in the case of a liquid crystal display device, a dye-based polarizer is disposed on either the entrance side or the exit side or both of the liquid crystal cell. The dye-based polarizer may or may not be in contact with the liquid crystal cell, but from the viewpoint of durability, it is preferable that it is not in contact. When the dye-based polarizer is in contact with the liquid crystal cell on the exit side of the liquid crystal cell, the liquid crystal cell can be used as a support for the dye-based polarizer. When the dye-based polarizer is not in contact with the liquid crystal cell, it is preferable to use a dye-based polarizer provided with a support other than the liquid crystal cell. Furthermore, from the viewpoint of durability, it is preferable to dispose a dye-based polarizer on both the entrance side and the exit side of the liquid crystal cell, and further it is preferable to dispose the polarizer surface of the dye-based polarizer on the liquid crystal cell side and the support surface on the light source side. Note that the entrance side of the liquid crystal cell refers to the light source side, and the opposite side is called the exit side.

[0117] The liquid crystal display device can be driven by any known driving method. For example, an active matrix drive type is preferred, in which a liquid crystal is sealed between a transparent substrate on which electrodes and thin film transistors are formed and a transparent substrate on which a counter electrode is formed. Light emitted from a light source such as a cold cathode tube lamp or a white LED passes through a dye-based polarizer, then passes through a liquid crystal cell, a color filter, and another dye-based polarizer, and is projected onto a display screen. [Example]

[0118] The present invention will be described in more detail below with reference to examples, but these are merely illustrative and do not limit the present invention in any way. % and parts in the examples are by weight unless otherwise specified.

[0119] [Example 1] The compound of formula (57) of Patent Document 4 was synthesized by the method described in Patent Document 4. 10 parts of the compound of formula (57) of Patent Document 4, 4.0 parts of copper sulfate pentahydrate, and 8.0 parts of monoethanolamine were added to 100 parts of water and reacted at 95°C for 10 hours. After that, the mixture was salted out using sodium chloride and separated by filtration to obtain 20 parts of a wet cake. The resulting wet cake was added to 100 parts of water, and 6.0 parts of disodium ethylenediaminetetraacetate and NMP were added, followed by a reaction at pH 3.0 to 6.0 for 10 hours. The resulting reaction mixture was salted out using sodium chloride, filtered, and dried to obtain 4.0 parts of the azo compound of the present invention represented by formula (101).

[0120] [ka]

[0121] [Example 2] In the same manner as in Example 1, except that 10 parts of the compound of formula (57) of Patent Document 4 described in Example 1 were replaced with 10 parts of the compound [compound 2-27] of Patent Document 6, which can be synthesized by the method described in Patent Document 5, 3.5 parts of the azo compound of the present invention represented by formula (102) were obtained.

[0122] [ka]

[0123] [Example 3] In the same manner as in Example 1, except that 10 parts of the compound of formula (57) of Patent Document 4 described in Example 1 were replaced with 10 parts of the compound of formula (42) of Patent Document 4, which can be synthesized by the method described in Patent Document 4, 3.7 parts of the azo compound of the present application represented by formula (103) were obtained.

[0124] [ka]

[0125] [Comparative Example 1] The compound described in formula (1) of Patent Document 1 was synthesized with reference to Example 1 of Patent Document 1. The structure is shown in formula (104).

[0126] [ka]

[0127] Comparative Example 2 The compound described in formula (4) of Patent Document 2 was synthesized with reference to Example 2 of Patent Document 2. The structure is shown in formula (105).

[0128] [ka]

[0129] Comparative Example 3 The compound described in formula (I-3) of Patent Document 3 was synthesized with reference to Example 1 of Patent Document 3. The structure is shown in formula (106).

[0130] [ka]

[0131] Comparative Example 4 With reference to Patent Document 4, the compound described in formula (57) of Patent Document 4 was synthesized. The structure is shown in formula (107).

[0132] [ka]

[0133] Comparative Example 5 The compound described in [Compound Example 2-27] of Patent Document 6 was synthesized with reference to Patent Document 5 and Patent Document 6. The structure is shown in formula (108).

[0134] [ka]

[0135] Comparative Example 6 The compound described in formula (56) of Patent Document 7 was synthesized with reference to Example 5 of Patent Document 7. The structure is shown in formula (109).

[0136] [ka]

[0137] Comparative Example 7 With reference to Patent Document 4, the compound described in formula (19) of Patent Document 4 was synthesized. The structure is shown in formula (110).

[0138] [ka]

[0139] [Comparative Example 8] With reference to WO 2006 / 057214, the compound described in formula (10) in WO 2006 / 057214 was synthesized as a structure in which a hydroxy group was introduced to facilitate comparison with the compound of the present invention, thereby synthesizing the compound described in formula (111) below.

[0140] [ka]

[0141] Comparative Example 9 With reference to JP-A Nos. 03-12606 and 11-218611, the compound described in formula (5) of JP-B No. 11-218611 was synthesized. The structure is shown in formula (112) below.

[0142] [ka]

[0143] [Comparative Example 10] In the same manner as in Example 1, except that 10 parts of the compound of formula (101) in Example 1 was replaced with 10 parts of the compound described in formula (2) of JP-A-11-218611, 3.2 parts of a trisazo compound having an introduced hydroxy group represented by formula (113) was obtained.

[0144] [ka]

[0145] [Comparative Example 11] The compound described in formula (1-42) of Patent Document 7 was synthesized with reference to Example F6 of Patent Document 8. The structure is shown in formula (114).

[0146] [ka]

[0147] [Comparative Example 12] The compound described in formula (1-47) of Patent Document 7 was synthesized with reference to Example F5 of Patent Document 8. The structure is shown in formula (115).

[0148] [ka]

[0149] [Comparative Example 13] The commercially available CI Direct Blue 67 was evaluated as a comparative example. Its structure is shown in formula (116).

[0150] [ka]

[0151] [Comparative Example 14] With reference to WO 2020 / 137691, the compound described in formula (14) of Example 2 of WO 2020 / 137691 was synthesized. The structure is shown in formula (117).

[0152] [ka]

[0153] [Comparative Example 15] With reference to Patent Document 9, the compound described in Example 1, Compound Example 1 of Patent Document 9 was synthesized. The structure is shown in formula (118).

[0154] [ka]

[0155] <Examples 1 to 3 and Comparative Examples 1 to 16: Preparation of Polarizing Film> A 75 μm thick polyvinyl alcohol film was immersed for 4 minutes in an aqueous solution (dye bath) containing 0.03% of each of the azo compounds obtained in Examples 1 to 3 and Comparative Examples 1 to 16 and 0.1% of sodium sulfate at 45° C. This film was stretched 5 times in a 3% aqueous boric acid solution at 50° C., and then washed with water and dried while maintaining the tension to obtain a polarizing film.

[0156] The polarizing films containing the compounds obtained in Examples 1 to 3 and Comparative Examples 1 to 16 were evaluated as follows. (a) Polarized parallel transmittance (Ky) and polarized orthogonal transmittance (Kz) The maximum absorption wavelength (λmax), parallel polarized transmittance (Ky), and crossed polarized transmittance (Kz) of the polarizing film were measured using a spectrophotometer (UH-4150, manufactured by Hitachi High-Tech Corporation). Ky refers to the transmittance when the absorption axis of the absolute polarizer and the polarizing film are placed in parallel and overlapped, and Kz refers to the transmittance when the absorption axis of the absolute polarizer and the polarizing film are placed in perpendicular and overlapped. The parallel polarized transmittances Ky and Kz for each wavelength were measured from 380 nm to 780 nm at wavelength intervals of 1 to 10 nm. (b) Single transmittance (Ts), parallel transmittance (Tp), cross transmittance (Tc) The single transmittance (Ts) indicates the spectral transmittance when one polarizing film is used, the parallel transmittance (Tp) indicates the spectral transmittance when two polarizing films are placed with their absorption axes parallel to each other, and the crossed transmittance (Tc) indicates the spectral transmittance when two polarizing films are placed with their absorption axes perpendicular to each other. The transmittances were calculated using the Ky and Kz values ​​at λmax obtained by measurement using the following formulas (I) to (III).

[0157] (Number 1) Ts(%)=(Ky+Kz) / 2 Calculation formula (I) Tp(%)=(Ky 2 +Kz 2 ) / 200 Formula (II) Tc(%)=(Ky×Kz) / 100 Calculation formula (III)

[0158] (c) Polarization rate (ρ), dichroic ratio The polarization rate (ρ) and dichroic ratio at λmax of each measurement sample were calculated using the following formulas (IV) and (V).

[0159] (Number 2) ρ(%)=[(Ky-Kz) / (Ky+Kz)]×100 Formula (IV) Dichroic ratio =log(Kz / 100) / log(Ky / 100) Calculation formula (V)

[0160] Table 1 shows the λmax of the compounds of the present invention in a polarizing film.

[0161] [Table 1]

[0162] As shown in Table 1, the tetrakisazo compound of the present invention has a λmax of 600 nm or more due to the presence of a hydroxy group at a specific position, and it has been confirmed that the compound is a dichroic dye with an absorption band on the long wavelength side of blue to green.

[0163] Next, Table 2 shows the values ​​obtained by measurement and calculation of the polarizing films of Examples 1 and 2 and Comparative Examples 1 to 16.

[0164] [Table 2]

[0165] The polarizing films were evaluated by adjusting the Ts of the films to 43.10 to 44.36%, as shown in Table 2. The polarizing films prepared using the azo compounds of Examples 1 and 2 had higher dichroic ratios than any of the polarizing films of Comparative Examples 1 to 15. Specifically, the compounds of the present invention have different structures in that they have hydroxy groups at specific positions between Example 1 and Comparative Example 4, and between Example 2 and Comparative Example 5. Comparison of the polarization performance of these compounds showed that the compounds of the present invention having hydroxy groups at specific positions have a higher dichroic ratio. Furthermore, in comparison with Comparative Examples 1, 7, and 14, the results showed that the dichroic ratio was higher when there were no naphthalene rings other than at both ends of the linked azo group, demonstrating that the compound of the present invention was sufficiently superior. Typical trisazo compounds are used in Comparative Examples 8 to 10. Compared with Comparative Examples 8 to 10, the polarizing plates of Examples 1 and 2 had higher dichroic ratios than typical trisazo compounds. Comparative Example 9 is a trisazo copper compound, and Comparative Example 15 is a tetrakis azo copper compound. Compared with general trisazo copper compounds and tetrakis azo copper compounds, the polarizing plates of Examples 1 and 2 showed superiority in dichroic ratio. From the above, it was shown that the presence of a hydroxy group at a specific position in the tetrakisazo compound of the present invention contributes to improved performance.

[0166] <Example 4: Dye-based polarizing plate> A dye-based polarizing plate was prepared by laminating triacetyl cellulose films to both sides of the polarizing film obtained in Example 1 via a polyvinyl alcohol-based adhesive. One side of the obtained polarizing plate was attached to glass using a pressure-sensitive adhesive, and the resulting plate was used as Example 4.

[0167] <Comparative Example 16: Iodine-based polarizing plate> As a general iodine-based polarizing plate, an iodine-based polarizing plate (product name: SKN-18243P) manufactured by Nippon Kayaku Co., Ltd. was attached to glass on one side using an adhesive, and used as Comparative Example 16.

[0168] The polarizing plates of Example 4 and Comparative Example 16 were visually observed for hue change after 500 hours under heat-resistant conditions at an ambient temperature of 105°C and 500 hours under high-temperature, high-humidity conditions at an ambient temperature of 80°C and a relative humidity of 90%. The results are shown in Table 3 (almost no hue change: ◯, hue change: △, significant hue change: ×).

[0169] [Table 3]

[0170] As shown in Table 3, the dye-based polarizing plate of Example 4 showed almost no change in hue even under heat-resistant, high-temperature, and high-humidity conditions. On the other hand, the iodine-based polarizing plate of Comparative Example 16 showed a very large change in hue. In other words, the dye-based polarizing plate of the present invention has high environmental resistance and is suitable for use in display devices used in harsh environments. [Industrial Applicability]

[0171] A polarizing film or polarizing plate prepared using the azo compound of the present invention may be provided with a protective layer or functional layer and a transparent support such as glass, quartz, or sapphire, as necessary, and is used in liquid crystal projectors, calculators, clocks, notebook computers, liquid crystal televisions, polarized lenses, polarized glasses, car navigation systems, and indoor and outdoor measuring instruments and displays, etc. In particular, the polarizing film or polarizing plate of the present invention can be suitably used in liquid crystal displays, such as reflective liquid crystal displays and semi-transmissive liquid crystal displays, and in organic electroluminescence devices other than liquid crystal displays.

Claims

1. An azo compound represented by the following formula (1) or a salt thereof: 【Chemical 1】 (In formula (1), Ar represents a benzene ring which may have a substituent, a naphthalene ring which may have a substituent, or a heterocycle which may have a substituent; R １ ~R ５ are each independently a hydrogen atom, C １ -C ４ Alkyl group, C １ -C ４ C having an alkoxy group or a sulfo group １ -C ４ wherein Q represents an optional substituent, and n represents an integer of 1 to 3).

2. The azo compound or salt thereof according to claim 1, wherein the azo compound represented by formula (1) or a salt thereof is represented by the following formula (2) or a salt thereof: 【Chemistry 2】 (In formula (2), R １ ~R ６ are each independently a hydrogen atom, C １ -C ４ Alkyl group, C １ -C ４ C having an alkoxy group or a sulfo group １ -C ４ and n is an integer of 1 to 3).

3. The azo compound or salt thereof according to claim 1, wherein the azo compound represented by formula (1) or a salt thereof is represented by the following formula (3) or a salt thereof: 【Chemistry 3】 (In the above formula (3), R ６ is a hydrogen atom, C １ - ４ Alkyl group, C １ - ４ C having an alkoxy group or a sulfo group １ -C ４ and n is an integer of 1 to 3).

4. A polarizing film comprising the azo compound or a salt thereof according to any one of claims 1 to 3.

5. The polarizing film according to any one of claims 1 to 3, comprising a substrate.

6. A polarizing plate comprising a transparent protective film provided on one or both sides of the polarizing film according to claim 5, and a display device using the polarizing plate.

Images