Copper-complex trisazo compound having 6-amino-1-naphthol-3,5-disulfonic acid moiety or salt thereof, polarizing film comprising same, polarizing plate, and display device

Abstract

Provided is a copper-complex azo compound represented by formula (1), or a salt thereof. (In formula (1), A represents a sulfo group or a carboxy group; Q1, Q2, and R1 to R3 each independently represent an arbitrary substituent; and n represents an integer of 0-3.)

Description

Copper trisazo compounds having a 6-amino-1-naphthol-3,5-disulfonic acid moiety or salts thereof, and polarizing films, polarizing plates, and display devices containing the same.

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

[0002] Polarizing plates, which have light transmission and shielding functions, are fundamental components of display devices such as liquid crystal displays (LCDs), along with liquid crystals, which have light switching functions. Applications of LCDs range from small devices such as calculators and watches in the early days to laptop computers, word processors, LCD projectors, LCD televisions, car navigation systems, and indoor and outdoor measuring instruments. They can also be applied to lenses with polarizing functions, and have been used in sunglasses with improved visibility and, more recently, in polarized glasses for 3D televisions. Because the applications of polarizing plates are so widespread, they are used in a wide range of conditions, from low to high temperatures, low to high humidity, and low to high light intensity, so there is a demand for polarizing plates with high polarization performance and high durability.

[0003] Currently, polarizing plates are manufactured by dyeing or impregnating a film of polyvinyl alcohol or its derivatives with iodine or dichroic dyes, then stretching and oriented it, or by generating polyenes through dehydrochlorination of polyvinyl chloride film or dehydration of polyvinyl alcohol-based film, and then oriented them. Generally, iodine-based polarizing films using iodine have excellent polarization performance, but they are weak against water and heat, and their durability is problematic when used for long periods in high temperature and high humidity conditions. Methods such as treatment with an aqueous solution containing formalin or boric acid, and the use of a polymer film with low moisture permeability as a protective film have been considered to improve durability, but their effectiveness is not considered sufficient.

[0004] Dye-based polarizing films using dichroic dyes can cover a wide variety of absorption bands by using multiple dyes, allowing for the creation of polarizing films suited to various purposes. For example, by mixing dyes of any color from yellow to orange, red to violet, and blue to green, a polarizing film that transmits and absorbs across the entire visible wavelength range can be obtained. On the other hand, while dye-based polarizing films have superior heat resistance, humidity resistance, and light resistance compared to iodine, their optical properties are inferior.

[0005] In recent years, display devices have predominantly utilized LED backlights as their light source, and their photometric colorimetric measurement is defined in JIS Z8724:2015. This standard specifies that the wavelength range for color matching functions is 360 nm to 830 nm, and that when performing spectral measurements of LED light sources for colorimetric purposes, the wavelength range may also be 380 nm to 780 nm.

[0006] Furthermore, polarizing films and polarizing plates in organic electroluminescent (EL) display devices (hereinafter referred to as OLEDs) are used to provide an anti-reflective function against the phenomenon of external light being reflected off the metal electrodes and other components that constitute the OLED (internal reflection). In this case, an optical laminate (circular polarizer) made by laminating a phase difference film such as a λ / 4 film and a polarizing film is generally bonded to the surface of the OLED so that the polarizing film is on the visible side, thereby achieving the anti-reflective function. However, even polarizing films used in this way to suppress internal reflection do not have high optical properties, especially in the wavelength range of 700 nm or more, so reflected light may appear colored, which significantly deteriorates the display quality in bright indoor and outdoor environments.

[0007] Patent Document 1 describes that when the reflected light of an OLED has a reddish tint, it gives a particularly bad impression to the user, and therefore, it is recommended to use a dye that absorbs at longer wavelengths of 630 nm to 780 nm. It reports that using oil-soluble dichroic dyes such as cyanine, anthraquinone, and squarylium in a guest-host type light-absorbing anisotropic layer or barrier layer using liquid crystal is effective in preventing reflection of OLEDs. However, although the anti-reflection effect is acknowledged, there is no mention of transmittance or polarization in the visible region, and depending on the display device used, it may impair the display quality, such as reducing brightness.

[0008] Therefore, while improvements in optical properties above 700 nm are required for polarizing plates used in display devices, patent applications for polarizing plates for display devices reported to date have either specified "400 nm to 700 nm in terms of the wavelength range for optical measurement" or "the wavelength range for optical measurement itself" as in Patent Document 2, and have not discussed optical properties above 700 nm. In fact, the dye-based polarizing plate described in Patent Document 2 has low absorption performance above 700 nm, so when the absorption axes of the two polarizing plates are placed perpendicular to each other, a phenomenon occurs where the light from the backlight appears to leak through (hereinafter referred to as light leakage).

[0009] Copperized azo compounds are known as dichroic dyes that have absorption above 700 nm and can cover the long wavelength region of 700 nm and above, and have been developed for a long time as described in Patent Documents 3 to 6. In particular, copperized azo compounds using 6-amino-1-naphthol-3-sulfonic acids (common name: J acid) have been actively developed in recent years. For example, Patent Document 7 reports on copperized azo compounds using J acid, and discloses that copperized tetrakiss azo compounds with an increased number of azo groups have good polarization performance.

[0010] However, while increasing the number of azo groups improves polarization performance, in practice, solubility in water, which is necessary for dyeing, is often poor. Furthermore, even if solubility in water is increased, the larger molecular size due to the large number of azo groups makes it difficult for them to penetrate into polymer chains, resulting in poor dyeability. In fact, with the example compound described in Patent Document 7, the desired transmittance could not be achieved without increasing the concentration of the dyeing solution. Moreover, increasing the concentration of the dyeing solution due to poor dyeability can easily lead to uneven dyeing of the polarizing film during manufacturing. In addition, at high concentrations of the dyeing solution, the dye is more likely to precipitate, potentially leaving foreign matter on the polarizing film. Therefore, there is a need for the development of dichroic copper azo compounds that are more water-soluble and have better dyeability, that is, that can dye at low concentrations.

[0011] Analogues of J acid include 6-amino-1-naphthol-3,5-disulfonic acids (commonly known as sulfo-J acid). For example, Patent Document 3 describes an azo compound using sulfo-J acid as shown in formula (4).

[0012] Japanese Patent No. 7377833, International Publication No. 2016 / 186183, Japanese Unexamined Patent Publication No. 2003-313451, Japanese Unexamined Patent Publication No. 05-311086, Japanese Unexamined Patent Publication No. 03-012606, Japanese Unexamined Patent Publication No. 59-145255, International Publication No. 2017 / 135392

[0013] "Dye Chemistry," by Yutaka Hosoda, Gihodo Publishing, 1957. "Applications of Functional Dyes," CMC Publishing Co., Ltd., 1st edition, pp. 98-100.

[0014] One object of the present invention is to provide a novel copper trisazo compound. Optionally, another object of the present invention is to provide a novel dichroic dye copper azo compound and a polarizing film and polarizing plate containing the same, having excellent polarizing performance. Another object of the present invention is to provide a polarizing film and polarizing plate that has the solubility in water necessary for dyeing, good dyeability to hydrophilic polymers, and further exhibits excellent polarizing performance at wavelengths of 700 nm or higher.

[0015] As a result of intensive research conducted by the present inventors to achieve such an object, the present inventors have found a novel copperized trisazo compound that can be used as a dichroic dye constituting a polarizing film and a polarizing plate, and have found that by using the copperized azo compound, a polarizing film and a polarizing plate having excellent polarizing performance can be realized, thereby completing the present invention.

[0016] That is, the present invention relates to the following [1] to [7], but is not limited thereto. [1] A copperized azo compound represented by the following formula (1) or a salt thereof: (In formula (1), A represents a sulfo group or a carboxy group, and Q １ , Q ２ , and R １ to R ３ each independently represent any substituent, and n represents an integer of 0 to 3). [2] In formula (1), A is a sulfo group, and R １ to R ３ are each independently a hydrogen atom, a chlorine atom, C １ to C ４ alkyl group, C １ to C ４ alkoxy group, C １ to C ４ alkoxy group having a sulfo group, or C １ to C ４ alkylcarbonylamino group, and Q １ and Q ２ are each independently a hydrogen atom, a chlorine atom, a nitro group, a hydroxy group, C １ to C ４ alkyl group, C １ to C ４ alkoxy group, C １ to C ４ alkoxy group having a sulfo group, C ６ to C １２ arylcarbamoyl group, C ６ to C １２ arylcarbamoyl group having a sulfo group and / or a carboxy group, or C １ to C ４ alkylcarbonylamino group, the copperized azo compound or a salt thereof according to [1]. [3] In formula (1), A is a sulfo group, and R １ to R ３Each of them independently forms a hydrogen atom, C １ ~C ４ alkyl group, C １ ~C ４ C having an alkoxy group and a sulfo group １ ~C ４ It is an alkoxy group or an acetylamino group, Q １ and Q ２ Each of these independently consists of a hydrogen atom, a chlorine atom, a nitro group, and C. １ ~C ４ alkyl group, C １ ~C ４ C having an alkoxy group and a sulfo group １ ~C ４ An alkoxy group, the copper azo compound or salt thereof as described in [1]. [4] The copper azo compound or salt thereof represented by formula (1) is the azo compound or salt thereof as described in any of [1] to [3], represented by the following formula (2): (In formula (2), A represents a sulfo group, and R １ and R ２ Each of them independently forms a hydrogen atom, C １ ~C ４ alkyl group, C １ ~C ４ C having an alkoxy group and a sulfo group １ ~C ４ It is an alkoxy group, Q １ and Q ２ Each of these independently consists of a hydrogen atom, a chlorine atom, a nitro group, and C. １ ~C ４ alkyl group, C １ ~C ４ C having an alkoxy group and a sulfo group １ ~C ４ (An alkoxy group, where n is an integer from 0 to 3.) [5] A polarizing film containing a substrate, characterized in that the substrate contains a copper azo compound or a salt thereof as described in any of [1] to [4]. [6] A polarizing plate comprising a transparent protective film provided on one or both sides of the polarizing film described in [5]. [7] A display device comprising the polarizing film described in [5] or the polarizing plate described in [6].

[0017] The copper 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, as it possesses sufficient solubility in water and high dyeability. Furthermore, the polarizing film and polarizing plate of the present invention have excellent polarization performance. Moreover, the polarizing film and polarizing plate of one embodiment of the present invention also have excellent polarization performance at wavelengths of 700 nm or higher. In addition, the polarizing film and polarizing plate of one embodiment of the present invention have excellent durability (moisture resistance, heat resistance, and light resistance).

[0018] In this specification and in the claims, unless it is clearly referring to a free form, “copperized azo compound or a salt thereof” may also be simply referred to as “copperized azo compound.” In this specification and in the claims, since “substituents” may include hydrogen atoms, hydrogen atoms may also be described as “substituents” for convenience. “May have substituents” means that it also includes cases without substituents. For example, “a phenyl group that may have substituents” includes an unsubstituted, simple phenyl group and a phenyl group with substituents.

[0019] The copper azo compound or salt thereof of the present invention is represented by the following formula (1). (In formula (1), A represents a sulfo group or a carboxyl group, Q １ Q ２ , and R １ ~R ３ Each of these independently represents an arbitrary substituent, and n is an integer between 0 and 3.

[0020] In formula (1), the ring structures drawn with solid and dashed lines represent a phenyl (phenylene) group or a naphthyl (naphthylene) group.

[0021] In the above formula (1), Q １ Q ２ , and R １ ~R ３ Each of these independently represents an arbitrary substituent. Q １ Q ２ , and R １ ~R ３Any substituents in this group include, for example, 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, 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, an arylsulfonylamino group, an alkylsulfamoyl 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 hydroxyl group (-OH), a cyano group (-CN), a nitro group (-NO) ２ ), mercapto group (-SH), halogen atom, carboxyl group (-CO ２ H), sulfo group (-SO ３ H), amino group (-NH ２ Examples include hydrogen atoms, etc.

[0022] Examples of such heterocyclic amino groups include five- or six-membered heterocyclic amino groups containing one to three heteroatoms selected from the group consisting of nitrogen, oxygen, and sulfur atoms. Specific examples of such heterocyclic amino groups include, for example, five-membered heteroalicyclic amino groups such as pyrrolidinylamino, tetrahydrofurylamino, tetrahydrothiophen-2-ylamino, and tetrahydrothiophen-3-ylamino; six-membered heteroalicyclic amino groups such as piperidinylamino, piperazinylamino, dioxan-2-ylamino, morpholinylamino, and thiomorpholinylamino; five-membered aromatic heterocyclic amino groups such as pyrroleamino, pyrazoleamino, imidazoleamino, triazoleamino, furylamino, thiophen-2-ylamino, thiophen-3-ylamino, oxazoleamino, and thiazoleamino; or six-membered aromatic heterocyclic amino groups such as pyridylamino, pyrazylamino, pyridadinylamino, and triazinylamino. The heterocyclic ring preferably has an aromatic ring as its heterocyclic portion. Furthermore, the heteroatoms constituting the heterocyclic ring are preferably selected from nitrogen atoms and sulfur atoms.

[0023] Examples of the fused heterocyclic amino group mentioned above include a fused heterocyclic amino group of a 5 or 6-membered ring, in which one benzene ring is fused to a 5 or 6-membered heterocycle containing one to three heteroatoms selected from the group consisting of nitrogen, oxygen, and sulfur atoms. Specific examples of such fused heterocyclic amino groups include, for example, fused heterocyclic amino groups in which the heterocyclic portion is a five-membered alicyclic ring, such as phthalanylamino; fused heterocyclic amino groups in which the heterocyclic portion is a six-membered alicyclic ring, such as benzopyranylamino; fused aromatic heterocyclic amino groups in which the heterocyclic portion is an aromatic five-membered ring, such as benzopyrroleamino, benzopyrazoleamino, benzimidazoleamino, benzotriazoleamino, benzofuranylamino, benzothiophen-2-ylamino, benzothiophen-3-ylamino, benzoxazoleamino, and benzothiazoleamino; or fused aromatic heterocyclic amino groups in which the heterocyclic portion is an aromatic six-membered ring, such as quinolinylamino, synnolinylamino, phthalazinylamino, quinazolinylamino, and quinoxalinylamino. It is preferable that the heterocyclic portion is an aromatic ring. Furthermore, it is preferable that the heteroatoms constituting the heterocyclic ring be selected from nitrogen atoms and sulfur atoms.

[0024] The alkyl group mentioned above is a linear, branched, or cyclic alkyl group, preferably C １ ~C １０ Alkyl groups are examples. C １ ~C １０ Specific examples of alkyl groups include linear C molecules such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl. １ ~C １０ Alkyl groups; branched C 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. ３ ~C １０ Alkyl groups; or cyclic C such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, etc. ３ ~C７ Examples include alkyl groups. Among these, linear or branched alkyl groups are preferred, and C １ to C ４ linear alkyl groups are more preferred.

[0025] The above alkoxy group includes linear, branched or cyclic alkoxy groups, preferably C １ to C １０ alkoxy groups. C １ to C １０ Specific examples of the alkoxy group include, for example, linear C such as methoxy, ethoxy, n-propoxy, n-butoxy, n-pentoxy, n-hexyloxy, n-heptoxy, n-octyloxy, n-nonyloxy, and n-decyloxy １ to C １０ alkoxy groups; branched C 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 ３ to C １０ alkoxy groups; or cyclic C such as cyclopropoxy, cyclobutoxy, cyclopentoxy, cyclohexyloxy, and cycloheptoxy ３ to C ７ alkoxy groups may be mentioned. Among these, linear or branched alkoxy groups are preferred, and C １ to C ４ linear alkoxy groups are more preferred.

[0026] As the alkoxy group having a sulfo group described above, a linear alkoxy group is preferred, and the terminal of the alkoxy group is preferred as the substitution position of the sulfo group. More preferably, it is C having a sulfo group １ to C ４ alkoxy group, more preferably 3-sulfopropoxy group and 4-sulfobutoxy group, and particularly preferably 3-sulfopropoxy group.

[0027] The above aryloxy group is preferably C ６ to C １２These are aryloxy groups, and specific examples include phenoxy, naphthyloxy, and biphenyloxy.

[0028] The alkylcarbonylamino group mentioned above is a linear, branched, or cyclic alkylcarbonylamino group, preferably C １ ~C １０ Examples include alkylcarbonylamino groups. １ ~C １０ Specific examples of alkylcarbonylamino groups include linear carbonylamino groups such as methylcarbonylamino (acetylamino), ethylcarbonylamino, n-propylcarbonylamino, n-butylcarbonylamino, n-pentylcarbonylamino, n-hexylcarbonylamino, n-heptylcarbonylamino, n-octylcarbonylamino, n-nonylcarbonylamino, and n-decylcarbonylamino. １ ~C １０ Alkylcarbonylamino groups; branched-chain carbons such as isopropylcarbonylamino, isobutylcarbonylamino, sec-butylcarbonylamino, t-butylcarbonylamino, isoamylcarbonylamino, t-amylcarbonylamino, isohexylcarbonylamino, t-hexylcarbonylamino, isoheptylcarbonylamino, t-heptylcarbonylamino, isooctylcarbonylamino, t-octylcarbonylamino, 2-ethylhexylcarbonylamino, isononylcarbonylamino, isodecylcarbonylamino, etc. ３ ~C １０ Alkylcarbonylamino group; or cyclic C such as cyclopropylcarbonylamino, cyclobutylcarbonylamino, cyclopentylcarbonylamino, cyclohexylcarbonylamino, cycloheptylcarbonylamino, etc. ３ ~C ７ Examples include alkylcarbonylamino groups. Among these, linear or branched alkylcarbonylamino groups are preferred, and linear alkylcarbonylamino groups are more preferred.

[0029] The above arylcarbonylamino group is preferably C ６ ~C １２These are arylcarbonylamino groups, and specific examples include phenylcarbonylamino (benzoylamino), naphthylcarbonylamino, and biphenylcarbonylamino.

[0030] The alkylcarbonyloxy group mentioned above is a linear, branched, or cyclic alkylcarbonyloxy group, preferably C １ ~C １０ Examples include alkylcarbonyloxy groups. １ ~C １０ Specific examples of alkylcarbonyloxy groups include linear carbonyloxy groups such as methylcarbonyloxy, ethylcarbonyloxy, n-propylcarbonyloxy, n-butylcarbonyloxy, n-pentylcarbonyloxy, n-hexylcarbonyloxy, n-heptylcarbonyloxy, n-octylcarbonyloxy, n-nonylcarbonyloxy, and n-decylcarbonyloxy. １ ~C １０ Alkylcarbonyloxy groups; branched-chain carbonyloxy groups such as isopropylcarbonyloxy, isobutylcarbonyloxy, sec-butylcarbonyloxy, t-butylcarbonyloxy, isoamylcarbonyloxy, t-amylcarbonyloxy, isohexylcarbonyloxy, t-hexylcarbonyloxy, isoheptylcarbonyloxy, t-heptylcarbonyloxy, isooctylcarbonyloxy, t-octylcarbonyloxy, 2-ethylhexylcarbonyloxy, isononylcarbonyloxy, isodecylcarbonyloxy, etc. ３ ~C １０ Alkylcarbonyloxy group; or cyclic C such as cyclopropylcarbonyloxy, cyclobutylcarbonyloxy, cyclopentylcarbonyloxy, cyclohexylcarbonyloxy, cycloheptylcarbonyloxy. ３ ~C ７ Examples include alkylcarbonyloxy groups. Among these, linear or branched alkylcarbonyloxy groups are preferred, and linear alkylcarbonyloxy groups are more preferred.

[0031] The above arylcarbonyloxy group is preferably C ６ ~C１２ These are arylcarbonyloxy groups, and specific examples include phenylcarbonyloxy, naphthylcarbonyloxy, and biphenylcarbonyloxy.

[0032] The alkylcarbonyl group mentioned above is a linear, branched, or cyclic alkylcarbonyl group, preferably C １ ~C １０ Examples include alkylcarbonyl groups. １ ~C １０ Specific examples of alkylcarbonyl groups include linear carbonyl groups such as methylcarbonyl, ethylcarbonyl, n-propylcarbonyl, n-butylcarbonyl, n-pentylcarbonyl, n-hexylcarbonyl, n-heptylcarbonyl, n-octylcarbonyl, n-nonylcarbonyl, and n-decylcarbonyl. １ ~C １０ Alkyl carbonyl groups; branched C groups 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. ３ ~C １０ Alkyl carbonyl group; or cyclic carbon such as cyclopropyl carbonyl, cyclobutyl carbonyl, cyclopentyl carbonyl, cyclohexyl carbonyl, cycloheptyl carbonyl, etc. ３ ~C ７ Examples include alkylcarbonyl groups. Among these, linear or branched alkylcarbonyl groups are preferred, and linear alkylcarbonyl groups are more preferred.

[0033] The above arylcarbonyl group is preferably C ６ ~C １２ These are arylcarbonyl groups, and specific examples include phenylcarbonyl (benzoyl), naphthylcarbonyl, and biphenylcarbonyl.

[0034] Examples of the alkylcarbamoyl groups mentioned above include linear, branched, or cyclic monoalkylcarbamoyl groups or dialkylcarbamoyl groups.

[0035] The monoalkylcarbamoyl group is preferably monoC １ ~C １０ These are alkylcarbamoyl groups, and specific examples include linear mono-C groups such as methylcarbamoyl, ethylcarbamoyl, n-propylcarbamoyl, n-butylcarbamoyl, n-pentylcarbamoyl, n-hexylcarbamoyl, n-heptylcarbamoyl, n-octylcarbamoyl, n-nonylcarbamoyl, and n-decylcarbamoyl. １ ~C １０ Alkylcarbamoyl groups; branched mono-C groups 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. ３ ~C １０ Alkylcarbamoyl group; or cyclic mono-C such as cyclopropylcarbamoyl, cyclobutylcarbamoyl, cyclopentylcarbamoyl, cyclohexylcarbamoyl, cycloheptylcarbamoyl, etc. ３ ~C ７ Examples include alkylcarbamoyl groups. Among these, linear or branched monoalkylcarbamoyl groups are preferred, and linear monoalkylcarbamoyl groups are more preferred.

[0036] The dialkylcarbamoyl group is preferably diC １ ~C １０These are alkylcarbamoyl groups, and specific examples include linear diC 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. １ ~C １０ Alkylcarbamoyl group; branched-chain diC2, 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, diisodecylcarbamoyl, etc. ３ ~C １０ Alkylcarbamoyl group; or a cyclic diC having two rings, such as dicyclopropylcarbamoyl, dicyclobutylcarbamoyl, dicyclopentylcarbamoyl, dicyclohexylcarbamoyl, or dicycloheptylcarbamoyl. ３ ~C ７ Examples include alkylcarbamoyl groups. Among these, linear or branched dialkylcarbamoyl groups are preferred, and linear dialkylcarbamoyl groups are more preferred.

[0037] Examples of the arylcarbamoyl group mentioned above include a monoarylcarbamoyl group or a diarylcarbamoyl group.

[0038] The monoarylcarbamoyl group is preferably mono-C ６ ~C １２ These are arylcarbamoyl groups, and specific examples include phenylcarbamoyl, naphthylcarbamoyl, and biphenylcarbamoyl.

[0039] Preferably, the diarylcarbamoyl group is diC ６ ~C １２These are arylcarbamoyl groups, and specific examples include diphenylcarbamoyl, dinaphthylcarbamoyl, and di(biphenyl)carbamoyl.

[0040] The alkoxycarbonyl group mentioned above is a linear, branched, or cyclic alkoxycarbonyl group, preferably C １ ~C １０ An example is the alkoxycarbonyl group. １ ~C １０ Specific examples of alkoxycarbonyl groups include, for example, linear carbon atoms such as methoxycarbonyl, ethoxycarbonyl, n-propoxycarbonyl, n-butoxycarbonyl, n-pentoxycarbonyl, n-hexyloxycarbonyl, n-heptoxycarbonyl, n-octyloxycarbonyl, n-nonyloxycarbonyl, and n-decyloxycarbonyl. １ ~C １０ Alkoxycarbonyl groups; branched C groups 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. ３ ~C １０ Alkoxycarbonyl group; or cyclic C such as cyclopropoxycarbonyl, cyclobutoxycarbonyl, cyclopentoxycarbonyl, cyclohexyloxycarbonyl, and cycloheptoxycarbonyl. ３ ~C ７ Examples include alkoxycarbonyl groups. Among these, linear or branched alkoxycarbonyl groups are preferred, and linear alkoxycarbonyl groups are more preferred.

[0041] The above aryloxycarbonyl group is preferably C ６ ~C １２These are aryloxycarbonyl groups, and specific examples include phenoxycarbonyl, naphthyloxycarbonyl, and biphenyloxycarbonyl.

[0042] The alkylsulfonylamino group mentioned above is a linear, branched, or cyclic alkylsulfonylamino group, preferably C １ ~C １０ Examples include alkylsulfonylamino groups. １ ~C １０ Specific examples of alkylsulfonylamino groups include linear C groups such as methylsulfonylamino, ethylsulfonylamino, n-propylsulfonylamino, n-butylsulfonylamino, n-pentylsulfonylamino, n-hexylsulfonylamino, n-heptylsulfonylamino, n-octylsulfonylamino, n-nonylsulfonylamino, and n-decylsulfonylamino. １ ~C １０ Alkylsulfonylamino groups; branched C groups 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. ３ ~C １０ Alkyl sulfonylamino group; or cyclic C such as cyclopropyl sulfonylamino, cyclobutyl sulfonylamino, cyclopentyl sulfonylamino, cyclohexyl sulfonylamino, cycloheptyl sulfonylamino, etc. ３ ~C ７ Examples include alkylsulfonylamino groups. Among these, linear or branched alkylsulfonylamino groups are preferred, and linear alkylsulfonylamino groups are more preferred.

[0043] The above arylsulfonylamino group is preferably C ６ ~C １２These are arylsulfonylamino groups, and specific examples include phenylsulfonylamino, toluenesulfonylamino, naphthylsulfonylamino, and biphenylsulfonylamino.

[0044] Examples of the alkylsulfamoyl groups mentioned above include linear, branched, or cyclic monoalkylsulfamoyl groups or dialkylsulfamoyl groups.

[0045] The monoalkylsulfamoyl group is preferably monoC １ ~C １０ These are alkylsulfamoyl groups, and specific examples include linear mono-C groups such as methylsulfamoyl, ethylsulfamoyl, n-propylsulfamoyl, n-butylsulfamoyl, n-pentylsulfamoyl, n-hexylsulfamoyl, n-heptylsulfamoyl, n-octylsulfamoyl, n-nonylsulfamoyl, and n-decylsulfamoyl. １ ~C １０ Alkyl sulfamoyl groups; branched mono-C groups such as isopropyl sulfamoyl, isobutyl sulfamoyl, sec-butyl sulfamoyl, t-butyl sulfamoyl, isoamyl sulfamoyl, t-amyl sulfamoyl, isohexyl sulfamoyl, t-hexyl sulfamoyl, isoheptyl sulfamoyl, t-heptyl sulfamoyl, isooctyl sulfamoyl, t-octyl sulfamoyl, 2-ethylhexyl sulfamoyl, isononyl sulfamoyl, and isodecyl sulfamoyl. ３ ~C １０ Alkyl sulfamoyl group; or cyclic mono-C such as cyclopropyl sulfamoyl, cyclobutyl sulfamoyl, cyclopentyl sulfamoyl, cyclohexyl sulfamoyl, cycloheptyl sulfamoyl ３ ~C ７ Examples include alkylsulfamoyl groups. Among these, linear or branched monoalkylsulfamoyl groups are preferred, and linear monoalkylsulfamoyl groups are more preferred.

[0046] The dialkylsulfamoyl group is preferably diC １ ~C１０ These are alkylsulfamoyl groups, and specific examples include linear diC groups such as 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. １ ~C １０ Alkyl sulfamoyl group; branched C2C2 having two branched chains, such as diisopropyl sulfamoyl, diisobutyl sulfamoyl, di-sec-butyl sulfamoyl, di-t-butyl sulfamoyl, diisoamyl sulfamoyl, di-t-amyl sulfamoyl, diisohexyl sulfamoyl, di-t-hexyl sulfamoyl, diisoheptyl sulfamoyl, di-t-heptyl sulfamoyl, diisooctyl sulfamoyl, di-t-octyl sulfamoyl, di-(2-ethylhexyl) sulfamoyl, diisononyl sulfamoyl, diisodecyl sulfamoyl, etc. ３ ~C １０ Alkyl sulfamoyl group; or a cyclic diC having two rings, such as dicyclopropyl sulfamoyl, dicyclobutyl sulfamoyl, dicyclopentyl sulfamoyl, dicyclohexyl sulfamoyl, or dicycloheptyl sulfamoyl. ３ ~C ７ Examples include alkylsulfamoyl groups. Among these, linear or branched dialkylsulfamoyl groups are preferred, and linear dialkylsulfamoyl groups are more preferred.

[0047] Examples of the arylsulfamoyl group mentioned above include a monoarylsulfamoyl group or a diarylsulfamoyl group.

[0048] The monoarylsulfamoyl group is preferably monoC ６ ~C １２ These are arylsulfamoyl groups, and specific examples include phenylsulfamoyl, naphthylsulfamoyl, and biphenylsulfamoyl.

[0049] The diarylsulfamoyl group is preferably diC ６ ~C １２ These are arylsulfamoyl groups, and specific examples include diphenylsulfamoyl, dinaphthylsulfamoyl, and di(biphenyl)sulfamoyl.

[0050] The alkylsulfonyl group mentioned above is a linear, branched, or cyclic alkylsulfonyl group, preferably C １ ~C １２ Examples include alkylsulfonyl groups. １ ~C １２ Specific examples of alkylsulfonyl groups include linear C 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. １ ~C １２ Alkyl sulfonyl groups; branched C groups such as isopropyl sulfonyl, isobutyl sulfonyl, sec-butyl sulfonyl, t-butyl sulfonyl, isoamyl sulfonyl, t-amyl sulfonyl, isohexyl sulfonyl, t-hexyl sulfonyl, isoheptyl sulfonyl, t-heptyl sulfonyl, isooctyl sulfonyl, t-octyl sulfonyl, 2-ethylhexyl sulfonyl, isononyl sulfonyl, isodecyl sulfonyl, isoundecyl sulfonyl, t-undecyl sulfonyl, isododecyl sulfonyl, t-dodecyl sulfonyl, etc. ３ ~C １２ Alkyl sulfonyl group; or cyclic C such as cyclopropyl sulfonyl, cyclobutyl sulfonyl, cyclopentyl sulfonyl, cyclohexyl sulfonyl, cycloheptyl sulfonyl, etc. ３ ~C ７ Examples include alkylsulfonyl groups. Among these, linear or branched alkylsulfonyl groups are preferred, and linear alkylsulfonyl groups are more preferred.

[0051] The above aryl sulfonyl group is preferably C ６ ~C１２ These are arylsulfonyl groups, and specific examples include phenylsulfonyl, naphthylsulfonyl, and biphenylsulfonyl.

[0052] The alkylthio group mentioned above is a linear, branched, or cyclic alkylthio group, preferably C １ ~C １０ Examples include alkylthio groups. １ ~C １０ Specific examples of alkylthio groups include linear C groups such as methylthio, ethylthio, n-propylthio, n-butylthio, n-pentylthio, n-hexylthio, n-heptylthio, n-octylthio, n-nonylthio, and n-decylthio. １ ~C １０ Alkylthio groups; branched C groups such as isopropylthio, isobutylthio, sec-butylthio, t-butylthio, isoamylthio, t-amylthio, isohexylthio, t-hexylthio, isoheptylthio, t-heptylthio, isooctylthio, t-octylthio, 2-ethylhexylthio, isononylthio, isodecylthio, etc. ３ ~C １０ Alkylthio group; or cyclic C such as cyclopropylthio, cyclobutylthio, cyclopentylthio, cyclohexylthio, cycloheptylthio, etc. ３ ~C ７ Examples include alkylthio groups. Among these, linear or branched alkylthio groups are preferred, and linear alkylthio groups are more preferred.

[0053] The above arylthio group is preferably C ６ ~C １２ These are arylthio groups, and specific examples include phenylthio, naphthylthio, and biphenylthio.

[0054] Examples of the alkylureido groups mentioned above include linear, branched, or cyclic monoalkylureido groups or dialkylureido groups.

[0055] The monoalkylureide group is preferably monoC １ ~C １０These are alkylureide groups, and specific examples include linear mono-C groups such as methylureide, ethylureide, n-propylureide, n-butylureide, n-pentylureide, n-hexylureide, n-heptylureide, n-octylureide, n-nonylureide, and n-decylureide. １ ~C １０ Alkylureide groups; branched mono-C groups such as isopropylureide, isobutylureide, sec-butylureide, t-butylureide, isoamylureide, t-amylureide, isohexylureide, t-hexylureide, isoheptylureide, t-heptylureide, isooctylureide, t-octylureide, 2-ethylhexylureide, isononylureide, and isodecylureide. ３ ~C １０ Alkylureide group; or cyclic mono-C such as cyclopropylureide, cyclobutylureide, cyclopentylureide, cyclohexylureide, and cycloheptylureide. ３ ~C ７ Examples include alkylureido groups. Among these, linear or branched alkylureido groups are preferred, with linear alkylureido groups being a prime example.

[0056] The dialkylureide group is preferably diC １ ~C １０ These are alkylureide groups, and specific examples include linear diC groups such as dimethylureide, diethylureide, di-n-propylureide, di-n-butylureide, di-n-pentylureide, di-n-hexylureide, di-n-heptylureide, di-n-octylureide, di-n-nonylureide, and di-n-decylureide. １ ~C １０Alkylureide group; branched-chain diC with two branched chains, such as diisopropylureide, diisobutylureide, di-sec-butylureide, di-t-butylureide, diisoamylureide, di-t-amylureide, diisohexylureide, di-t-hexylureide, diisoheptylureide, di-t-heptylureide, diisooctylureide, di-t-octylureide, di-(2-ethylhexyl)ureide, diisononylureide, diisodecylureide, etc. ３ ~C １０ Alkylureide group; or a cyclic diC having two rings, such as dicyclopropylureide, dicyclobutylureide, dicyclopentylureide, dicyclohexylureide, or dicycloheptylureide. ３ ~C ７ Examples include alkylureido groups. Among these, linear or branched dialkylureido groups are preferred, and linear dialkylureido groups are more preferred.

[0057] Examples of the above-mentioned arylureide group include a monoarylureide group or a diarylureide group.

[0058] The monoarylureide group is preferably monoC ６ ~C １２ These are arylureide groups, and specific examples include phenylureide, naphthylureide, and biphenylureide.

[0059] The diaryluide group is preferably diC ６ ~C １２ These are aryl ureido groups, and specific examples include diphenylureido, dinaphthylureido, and di(biphenyl)ureido.

[0060] The alkoxycarbonylamino group mentioned above is a linear, branched, or cyclic alkoxycarbonylamino group, preferably C １ ~C １０ An example is the alkoxycarbonylamino group. １ ~C １０Specific examples of alkoxycarbonylamino groups include linear carbon atoms such as methoxycarbonylamino, ethoxycarbonylamino, n-propoxycarbonylamino, n-butoxycarbonylamino, n-pentoxycarbonylamino, n-hexyloxycarbonylamino, n-heptoxycarbonylamino, n-octyloxycarbonylamino, n-nonyloxycarbonylamino, and n-decyloxycarbonylamino. １ ~C １０ Alkoxycarbonylamino group; branched chain C such as isopropoxycarbonylamino, isobutoxycarbonylamino, sec-butoxycarbonylamino, t-butoxycarbonylamino, isoamyloxycarbonylamino, t-amyloxycarbonylamino, isohexyloxycarbonylamino, t-hexyloxycarbonylamino, isoheptoxycarbonylamino, t-heptoxycarbonylamino, isooctyloxycarbonylamino, t-octyloxycarbonylamino, 2-ethylhexyloxycarbonylamino, isononyloxycarbonylamino, isodecyloxycarbonylamino, etc. ３ ~C １０ Alkoxycarbonylamino group; or cyclic C such as cyclopropoxycarbonylamino, cyclobutoxycarbonylamino, cyclopentoxycarbonylamino, cyclohexyloxycarbonylamino, cycloheptoxycarbonylamino, etc. ３ ~C ７ Examples include alkoxycarbonylamino groups. Among these, linear or branched alkoxycarbonylamino groups are preferred, and linear alkoxycarbonylamino groups are more preferred.

[0061] The above aryloxycarbonylamino group is preferably C ６ ~C １２ These are aryloxycarbonylamino groups, and specific examples include phenylcarbonylamino, naphthylcarbonylamino, and biphenylcarbonylamino.

[0062] Examples of the alkylamino groups mentioned above include linear, branched, or cyclic monoalkylamino groups or dialkylamino groups.

[0063] The monoalkylamino group is preferably monoC １ ~C １０ These are alkylamino groups, and specific examples include linear mono-C groups such as methylamino, ethylamino, n-propylamino, n-butylamino, n-pentylamino, n-hexylamino, n-heptylamino, n-octylamino, n-nonylamino, and n-decylamino. １ ~C １０ Alkylamino groups; branched mono-C groups 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. ３ ~C １０ Alkylamino group; or cyclic mono-C such as cyclopropylamino, cyclobutylamino, cyclopentylamino, cyclohexylamino, cycloheptylamino, etc. ３ ~C ７ Examples include alkylamino groups. Among these, linear or branched monoalkylamino groups are preferred, and linear monoalkylamino groups are more preferred.

[0064] The dialkylamino group is preferably diC １ ~C １０ These are alkylamino groups, and specific examples include linear diC groups 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. １ ~C １０Alkylamino group; branched C2 molecules 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. ３ ~C １０ Alkylamino group; or a cyclic diC having two rings such as dicyclopropylamino, dicyclobutylamino, dicyclopentylamino, dicyclohexylamino, dicycloheptylamino, etc. ３ ~C ７ Examples include alkylamino groups. Among these, linear or branched dialkylamino groups are preferred, and linear dialkylamino groups are more preferred.

[0065] Examples of the arylamino group mentioned above include a monoarylamino group or a diarylamino group.

[0066] The monoarylamino group is preferably mono-C. ６ ~C １２ These are arylamino groups, and specific examples include phenylamino (anilino), naphthylamino, and biphenylamino.

[0067] The diarylamino group is preferably diC ６ ~C １２ These are arylamino groups, and specific examples include diphenylamino, dinaphthylamino, and di(biphenyl)amino.

[0068] Examples of the halogen atoms mentioned above include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, with fluorine atoms, chlorine atoms, or bromine atoms being preferred.

[0069] A more favorable Q １ and Q ２ Examples include hydrogen atoms, chlorine atoms, nitro groups, hydroxyl groups, and C. １ ~C ４ alkyl group, C １ ~C４ C having an alkoxy group and a sulfo group １ ~C ４ Alkoxy group, C ６ ~C １２ C having an arylcarbamoyl group, a sulfo group and / or a carboxyl group ６ ~C １２ Arylcarbamoyl group, or C １ ~C ４ Examples include alkylcarbonylamino groups. More preferred R １ ~R ３ Examples include hydrogen atoms, chlorine atoms, and C １ ~C ４ alkyl group, C １ ~C ４ C having an alkoxy group and a sulfo group １ ~C ４ Alkoxy group, C １ ~C ４ Examples include alkylcarbonylamino groups. Preferably, n is 1 or 2, and preferably A is a sulfo group.

[0070] When the azo compound or salt thereof represented by formula (1) is the azo compound or salt thereof represented by formula (2) below, it is preferable because it can provide a polarizing film with higher transmittance and higher polarization. (In formula (2), A represents a sulfo group or a carboxyl group, Q １ Q ２ , R １ , and R ２ Each of these independently represents an arbitrary substituent, and n is an integer between 0 and 3.

[0071] In the above equation (2), Q １ Q ２ , R １ , and R ２ Each of these independently represents an arbitrary substituent, and examples of arbitrary substituents include the same substituents that may be present in formula (1). However, Q １ Q ２ , R １ , and R ２ Each substituent is selected independently. Preferred R １ and R ２ Each is an independent hydrogen atom, C １ ~C４ alkyl group, C １ ~C ４ C having an alkoxy group or a sulfo group １ ~C ４ It is an alkoxy group, and Q is preferred. １ and Q ２ Each of these is independently a hydrogen atom, a chlorine atom, a nitro group, and C １ ~C ４ alkyl group, C １ ~C ４ C having an alkoxy group or a sulfo group １ ~C ４ It is an alkoxy group. Preferably A is a sulfo group, and preferably n is 1 or 2.

[0072] In equations (1) and (2), "C １ ~C ４ Examples of "alkyl groups" include linear alkyl groups such as methyl, ethyl, n-propyl, and n-butyl groups, and segmented alkyl groups such as sec-butyl and tert-butyl groups.

[0073] In equations (1) and (2), "C １ ~C ４ Examples of "alkoxy groups" include methoxy groups, ethoxy groups, propoxy groups, n-butoxy groups, sec-butoxy groups, and tert-butoxy groups.

[0074] In formulas (1) and (2), "C having a sulfo group" １ ~C ４ As the "alkoxy group," a linear alkoxy group is preferred, and the substitution position of the sulfo group is preferably the alkoxy group terminus. More preferably are 3-sulfopropoxy groups and 4-sulfobutoxy groups, and particularly preferably 3-sulfopropoxy groups.

[0075] The azo compound represented by formula (1) above, or a salt thereof, can be easily produced by known diazotization and coupling, following the usual methods for producing azo compounds as described in Non-Patent Document 1. The synthesis method is illustrated using the azo compound of formula (1) as an example.

[0076] First, aromatic amines represented by formula (a) below are diazotized by a known method as described in Non-Patent Document 1, and then subjected to primary coupling with aromatic amines represented by formula (b) below to obtain a monoazoamino compound represented by formula (c) below. (In formulas (a) to (c), A, Q １ Q ２ , R １ , R ２ ,n represents the same meaning as in equation (1).

[0077] Next, this monoazoamino compound (c) is diazotized by a known method as described in Non-Patent Document 1, and then secondary coupling with an aromatic amine of the following formula (d) to obtain a disazoamino compound represented by the following formula (e). (In equations (d) and (e), A, Q １ Q ２ , and R １ ~R ３ ,n represents the same meaning as in equation (1).

[0078] Next, formula (e) is diazotized by a known method as described in Non-Patent Document 1, and coupled with 6-amino-1-naphthol-3,5-disulfonic acid of formula (f) below, or a salt thereof, to obtain the trisazo compound of formula (g) below. (In formula (g), A, Q １ Q ２ , and R １ ~R ３ ,n represents the same meaning as in equation (1).

[0079] Next, the copperized azo compound of formula (1) is obtained by copperizing formula (g) using copper sulfate and amines, preferably aminoethanols, in a known method as described in Patent Document 7.

[0080] In the above reaction, the diazotization step is carried out either by a forward method, in which a nitrite such as sodium nitrite is mixed with an aqueous solution of a mineral acid such as hydrochloric acid or sulfuric acid, or a turbidity of the diazo component, or by a reverse method, in which a nitrite is added to a neutral or weakly alkaline aqueous solution of the diazo component, and then mixed with the mineral acid. The appropriate temperature for diazotization is -10 to 40°C. Furthermore, the coupling step with aromatic amines is carried out by mixing an acidic aqueous solution such as hydrochloric acid or acetic acid with the above-mentioned diazo solutions, under acidic conditions at a temperature of -10 to 40°C and a pH of 2 to 7.

[0081] The monoazo, disazo, and trisazo compounds obtained by coupling can be used as is, precipitated by acid precipitation or salting out and filtered, or the solution or turbidity can be used to proceed to the next step. If the monoazo, disazo, or trisazo compounds obtained by coupling are poorly soluble and form a turbidity, they can be filtered and used as a pressed cake (wet cake) in the next coupling step.

[0082] The coupling reaction between the diazotized disazo compound and 6-amino-1-naphthol-3,5-disulfonic acid represented by formula (f), or a salt thereof, is carried out under neutral to alkaline conditions at a temperature of -10 to 40°C and a pH of 7 to 10. After the reaction is complete, the compound represented by formula (g) is precipitated by salting out and then removed by filtration.

[0083] A copper azo compound of formula (1) can be obtained by adding copper sulfate, an amine, or an aminoethanol to a solution of the trisazo compound (g) and reacting it at 90°C or higher. After the reaction is complete, the compound is precipitated by salting out and then filtered. If further purification is required, the salting out process can be repeated or the compound can be precipitated from water using an organic solvent. Examples of organic solvents used for purification include water-soluble organic solvents such as alcohols like methanol and ethanol, and ketones like acetone.

[0084] When the aromatic amines represented by formula (a) that serve as starting materials for synthesizing the copper azo compound represented by formula (1) or its salt are substituted naphthylamine compounds, for example, 2-aminonaphthalene-6-sulfonic acid, 2-aminonaphthalene-6,8-disulfonic acid, 2-aminonaphthalene-5,7-disulfonic acid, 2-aminonaphthalene-4,8-disulfonic acid, 2-aminonaphthalene-4,6,8-trisulfonic acid, 2-aminonaphthalene-3,6,8-trisulfonic acid Sulfonic acid, 2-amino-1-hydroxynaphthalene-6-sulfonic acid, 3-amino-1-hydroxynaphthalene-6-sulfonic acid, 2-amino-8-hydroxynaphthalene-6-sulfonic acid, 3-amino-8-hydroxynaphthalene-6-sulfonic acid, 2-amino-1,8-dihydroxynaphthalene-6-sulfonic acid, 3-amino-1,8-dihydroxynaphthalene-6-sulfonic acid, 2-amino-1,8-dihydroxynaphthalene-3-sulfonic acid 2-amino-1,8-dihydroxynaphthalene-3,6-disulfonic acid, 2-amino-1-methoxy-8-hydroxynaphthalene-6-sulfonic acid, 3-amino-1-methoxy-8-hydroxynaphthalene-6-sulfonic acid, 2-amino-1-hydroxy-8-methoxynaphthalene-6-sulfonic acid, 3-amino-1-hydroxy-8-methoxynaphthalene-6-sulfonic acid, 2-amino-1-hydroxy-8-(3-sulfopropoxy) Examples include, but are not limited to, naphthalene-3-sulfonic acid, 2-amino-1-hydroxy-8-(4-sulfobutoxy)-naphthalene-3-sulfonic acid, 2-amino-1-(3-sulfopropoxy)-8-hydroxynaphthalene-3-sulfonic acid, 2-amino-1-(4-sulfobutoxy)-8-hydroxynaphthalene-3-sulfonic acid, and 2-amino-1,8-dihydroxynaphthalene-6-aminomethyl-3-disulfonic acid. Preferably, these are 2-aminonaphthalene-6,8-disulfonic acid, 2-aminonaphthalene-5,7-disulfonic acid, 2-aminonaphthalene-4,8-disulfonic acid, and 2-aminonaphthalene-3,6,8-trisulfonic acid.

[0085] When the aromatic amines represented by formula (a) that serve as starting materials for synthesizing the copper azo compound represented by formula (1) or a salt thereof are substituted phenylamine compounds, examples include, but are not limited to, 4-sulfoaniline, 3-sulfoaniline, 2-sulfoaniline, 2,4-disulfoaniline, 2,5-disulfoaniline, 4-nitro-2-sulfoaniline, 2-nitro-4-sulfoaniline, 4-methoxy-2-sulfoaniline, 2-methoxy-4-sulfoaniline, 4-chloro-3-sulfoaniline, 4-chloro-3-sulfoaniline, 4-(3-sulfopropoxy)-2-sulfoaniline, and 2-carboxy-4-sulfoaniline. Preferably, they are 4-sulfoaniline, 2,4-disulfoaniline, and 2-carboxy-4-sulfoaniline.

[0086] When the aromatic amines represented by formula (b) that serve as starting materials for synthesizing the copper azo compound represented by formula (1) or its salt are substituted phenylamine compounds, for example, aniline, 2-methylaniline, 2-ethylaniline, 2-propylaniline, 2-butylaniline, 3-methylaniline, 3-ethylaniline, 3-propylaniline, 3-butylaniline, 2,5-dimethylaniline, 2,5-diethylaniline, 2-methoxyaniline, 2-ethoxyaniline, 2-propoxyaniline, 2-butoxyaniline, 3-methoxyaniline, 3-ethoxyaniline, 3-propoxyaniline, 3-butoxyaniline, 2-methoxy-5-methylaniline, 2,5-Dimethoxyaniline, 3-(2-amino-4-methylphenoxy)propane-1-sulfonic acid, 3-(2-aminophenoxy)propane-1-sulfonic acid, 4-(2-amino-4-methylphenoxy)butane-1-sulfonic acid, 4-(2-aminophenoxy)butane-1-sulfonic acid, 2-(2-amino-4-methylphenoxy)ethane-1-sulfonic acid, 2-(2-aminophenoxy)ethane-1-sulfonic acid, 3-(3-amino 4-methylphenoxy)propane-1-sulfonic acid, 3-(3-aminophenoxy)propane-1-sulfonic acid, 4-(3-amino-4-methylphenoxy)butane-1-sulfonic acid, 4-(3-aminophenoxy)butane-1-sulfonic acid, 2-(3-amino-4-methylphenoxy)ethane-1-sulfonic acid, 2-(3-aminophenoxy)ethane-1-sulfonic acid, 3-(2-amino-4-methoxyphenoxy)propane-1-sulfonic acid Sulfonic acid, 4-(2-amino-4-methoxyphenoxy)butane-1-sulfonic acid, 2-(2-amino-4-methoxyphenoxy)ethane-1-sulfonic acid, 3-(3-amino-4-methoxyphenoxy)propane-1-sulfonic acid, 4-(3-amino-4-methoxyphenoxy)butane-1-sulfonic acid, 2-(3-amino-4-methoxyphenoxy)ethane-1-sulfonic acid, 3-(2-amino-4-ethoxyphenoxy)propane- Examples include, but are not limited to, 1-sulfonic acid, 4-(2-amino-4-ethoxyphenoxy)butane-1-sulfonic acid, 2-(2-amino-4-ethoxyphenoxy)ethane-1-sulfonic acid, 3-(3-amino-4-ethoxyphenoxy)propane-1-sulfonic acid, 4-(3-amino-4-ethoxyphenoxy)butane-1-sulfonic acid, and 2-(3-amino-4-ethoxyphenoxy)ethane-1-sulfonic acid. Furthermore, these aromatic amines may have protected amino groups. Examples of protecting groups include the ω-methanesulfone group.

[0087] Specific examples of copper azo compounds or their salts represented by formula (1) are given below. Note that copper azo compounds are expressed in the form of free acids.

[0088] The copper azo compounds represented by formula (1) above may be in the form of free acids or salts, or they may be salts of metal ions or ammonium ions. Examples of metal ions include alkali metal ions such as lithium ions, sodium ions, and potassium ions, and alkaline earth metal ions such as calcium ions and magnesium ions. Examples of ammonium ions include ammonium ions in the narrow sense (NH₄). ４ ＋ Examples include methylammonium ion, dimethylammonium ion, triethylammonium ion, tetraethylammonium ion, tetra-n-propylammonium ion, tetra-n-butylammonium ion, monoethanolammonium ion, diethanolammonium ion, triethanolammonium ion, N-methyl-N-monoethanolammonium ion, etc. More specifically, for example, in the case of free acids, sulfonic acid (-SO ３ H) is used, and in the case of sodium ions, sodium sulfonate (-SO ３ In the case of ammonium ions, use Na, and ammonium sulfonate (-SO ３ NH ４ ) represents. In the case of the N-methyl-N-monoethanolammonium ion, it is represented as "-SO ３ － ・[MeNH ２ CH ２ CH ２ OH] ＋ "represent.

[0089] <Polarizing Film> The polarizing film of the present invention contains, as a dichroic dye, a copper azo compound represented by formula (1) above or a salt thereof, either alone or in combination of several types, and may optionally further contain one or more other organic dyes other than the copper azo compound represented by formula (1) above. The other organic dyes are not particularly limited, but dyes that have absorption characteristics in a wavelength region different from the absorption wavelength region of the copper azo compound represented by formula (1) above or a salt thereof, and that have high dichroism are preferred. Examples of other organic dyes include C.I. Direct. Yellow 12, C.I. Direct. Yellow 28, C.I. Direct. Yellow 44, C.I. Direct. Orange 26, C.I. Direct. Orange 39, C.I. Direct. Orange 71, C.I. Direct. Orange 107, C.I. Direct. Red 2, C.I. Direct. Red 31, C.I. Direct. Representative examples include Red 79, C.I. Direct. Red 81, C.I. Direct. Red 247, C.I. Direct. Blue 69, C.I. Direct. Green 80, and C.I. Direct. Green 59, as well as the dyes described in Non-Patent Literature 2. However, depending on the purpose, it is preferable to use dyes developed for polarizing plates, such as those described in International Publication No. 2017 / 146212, International Publication No. 2019 / 117131, International Publication No. 2020 / 050333, and International Publication No. 2021 / 015188. These organic dyes are used as free acids, alkali metal salts (e.g., Na salts, K salts, Li salts), ammonium salts, or amine salts.

[0090] In one embodiment of the present invention, polarizing films made using a copper azo compound represented by formula (1) or a salt thereof as a dichroic dye and other dichroic dyes include neutral gray polarizing films and color polarizing films, which can be used depending on the application. Here, "neutral gray" means that when two polarizing films are superimposed so that their orientation directions are orthogonal to each other (hereinafter also referred to as "orthogonal position"), there is little light leakage (color leakage) of specific wavelengths in the visible light wavelength range.

[0091] The polarizing film of the present invention can be suitably used to control optical performance in the wavelength range of 700 nm and above, particularly 730 nm and above. For example, in applications requiring high optical properties in the wavelength range of 730 nm and beyond, the desirable optical performance is such that, when Ts = 44.0 ± 0.5%, the degree of polarization at 730 nm is preferably 78.0% or higher, more preferably 80.0% or higher, and even more preferably 90.0% or higher. Also, when Ts = 44.0 ± 0.5%, the orthogonal transmittance (Tc) at 730 nm is preferably 10.0% or less, and more preferably 5.0% or less. By having such polarization performance, a high-quality polarizing film without color bleeding can be provided.

[0092] The polarizing film of the present invention can be suitably used in applications requiring high optical properties. Desirable optical performance for such applications is, for example, when Ts = 44.0 ± 0.5%, the degree of polarization at the maximum absorption wavelength of the polarizing film is preferably 96% or higher, more preferably 96.5% or higher, and even more preferably 97.0% or higher. Also, when Ts = 44.0 ± 0.5%, the dichromatic ratio at the maximum absorption wavelength of the polarizing film is preferably 30 or higher, more preferably 30.5 or higher.

[0093] When using a copper azo compound of formula (1) or a salt thereof in combination with multiple dichroic dyes, the types of organic dyes used will differ depending on whether the target polarizing film is a neutral gray polarizing film, a color polarizing film for liquid crystal projectors, or other color polarizing films. The mixing ratio is not particularly limited, but generally, it is preferable to use a total of at least one of the other organic dyes in the range of 0.01 to 100 parts, and more preferably in the range of 0.1 to 10 parts, per 1 part of the copper azo compound of formula (1) or a salt thereof.

[0094] When the target polarizing film is a neutral gray polarizing film, the types and proportions of other organic dyes used in combination are adjusted so that the resulting polarizing film has minimal color leakage in the visible light wavelength range.

[0095] When the target polarizing film is a color polarizing film, the types and proportions 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 at orthogonal positions.

[0096] The polarizing film of the present invention can be produced by incorporating a dichroic dye, which includes a copper azo compound represented by formula (1) or a salt thereof, and optionally other dyes, into a polarizing film substrate (also simply referred to as "substrate") in a known manner and oriented it.

[0097] The polarizing film substrate is preferably a polymer film, and more preferably a film made of polyvinyl alcohol resin or a derivative thereof. Specific examples of the polarizing film substrate include polyvinyl alcohol resin or polyvinyl alcohol resin modified with olefins such as ethylene and propylene, or unsaturated carboxylic acids such as crotonic acid, acrylic acid, methacrylic acid, and maleic acid. As the polarizing film substrate, a film made of polyvinyl alcohol resin or a derivative thereof is preferably used from the viewpoint of dye adsorption and orientation. The thickness of the polarizing film substrate is usually 10 to 100 μm, and preferably about 20 to 80 μm.

[0098] When the polarizing film substrate is a polymer film, a method of dyeing the polymer film is usually employed to incorporate the copper azo compound of formula (1) or a salt thereof. Dyeing is carried out, for example, as follows: First, a dye bath is prepared by dissolving the copper azo compound represented by formula (1) or a salt thereof, and optionally other organic dyes, in water. The dye concentration in the dye bath is not particularly limited, but is usually selected from a range of about 0.001 to 10%. Dyeing aids may also be used if necessary; for example, it is preferable to use Glauber's salt at a concentration of about 0.1 to 10%. The polymer film can be immersed in the dye bath prepared in this way for, for example, 1 to 10 minutes to perform dyeing. The dyeing temperature is preferably about 30 to 80°C.

[0099] The orientation of the copper azo compound or its salt represented by formula (1) above is performed 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 method may be used for stretching, such as the wet method or the dry method. Stretching of the polymer film may be performed before dyeing, if necessary. In this case, the orientation of the water-soluble dye is performed at the time of dyeing. The polymer film containing the water-soluble dye and oriented is then subjected to post-treatment such as boric acid treatment by known methods as needed. Such post-treatment is performed to improve the transmittance and polarization degree of the polarizing film. The conditions for boric acid treatment vary depending on the type of polymer film and dye used, but generally the boric acid concentration of the boric acid aqueous solution is, for example, 0.1 to 15%, preferably 1 to 10%, the treatment temperature is 30 to 80°C, preferably 40 to 75°C, and the treatment is performed by immersion for 0.5 to 10 minutes. Furthermore, if necessary, a fixation treatment may be carried out in conjunction with an aqueous solution containing a cationic polymer compound.

[0100] <Polarizing Plate> The polarizing plate of the present invention (hereinafter also referred to as the "dye-based polarizing plate") can be obtained by using the compound of the present invention as a dichroic dye to control the transmittance in the long-wavelength region, and laminating a transparent protective film to one or both sides of the polarizing film produced. The material for forming the transparent protective film is preferably a material that is excellent in optical transparency, mechanical strength, thermal stability, moisture shielding properties, etc. Examples include, but are not limited to, cellulose acetate films, acrylic films, fluorine-based films such as tetrafluoroethylene / hexafluoropropylene copolymers, polyester resins, polyolefin resins, or polyamide resins. The transparent protective film is preferably a triacetylcellulose (TAC) film, an acrylic film, or a cycloolefin film, and the thickness of the protective film is usually preferably 10 to 200 μm. Furthermore, the transparent protective film is not limited to a film; a transparent protective layer may also be provided by forming a protective layer on the polarizing film made of an organic composition, an inorganic composition, or a mixed composition thereof, which is made of a material that is excellent in optical transparency, mechanical strength, thermal stability, moisture shielding properties, etc.

[0101] Furthermore, the polarizing film of the present invention can also be applied as a supported integrated polarizing plate in which a transparent substrate thicker than the film is laminated to both sides or one side of the polarizing film. The support can be broadly divided into inorganic substrates and organic substrates, including 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 polyolefins.

[0102] Adhesives or adhesives can be used to bond the polarizing film to the transparent protective film or protective substrate of a polarizing plate. Examples of adhesives include thermosetting adhesives and UV-curing adhesives, and include, but are not limited to, polyvinyl alcohol-based adhesives, urethane emulsion-based adhesives, acrylic-based adhesives, and polyester-isocyanate-based adhesives. Crosslinking agents, water-resistant agents, and other additives can be added to the adhesive to improve adhesive strength or water resistance. These are not particularly limited and can be selected as appropriate.

[0103] A transparent protective layer or functional layer may be provided on one or both sides of a polarizing plate on which a transparent protective film or the like has been formed. Examples of transparent protective layers include hard coat layers made of acrylic, polysiloxane, or urethane. As a functional layer, to further improve the transmittance of the single layer, an anti-reflective layer (anti-reflection layer, low-reflection layer, or a combination thereof), an anti-glare layer, an anti-fouling layer, etc., may be provided on the transparent protective film, transparent substrate, or transparent protective layer. The anti-reflection layer can be formed by vapor deposition or sputtering of a substance such as silicon dioxide or titanium dioxide, or by thinly coating a fluorine-based substance. On the other hand, it is also possible to bond such a functional layer or film to the exposed surface of the transparent protective film or the like via an adhesive or tack.

[0104] Optical components may be laminated on one or both sides of the polarizing plate, or optical components may be directly bonded to the polarizing film. Examples of optical components include cover glass, light diffusion film, and phase difference film.

[0105] For example, phase difference films include phase difference films made of transparent resins such as polycarbonate resin, and phase difference films made of liquid crystal coating. The thickness and optical properties of the phase difference film (the in-plane retardation value Re and the retardation value Rth in the thickness direction of the phase difference film) are not particularly limited, and it may be a phase difference film consisting of multiple layers. The polarizing plate and the phase difference film can be bonded together using an adhesive or bonding agent. The polarizing plate to which the phase difference film is bonded becomes an elliptical polarizing plate or a circular polarizing plate, which can be appropriately selected depending on the display device used to obtain viewing angle compensation effects, anti-reflective effects, etc. It is also possible to directly bond such a phase difference film to a polarizing film to create a transparent protective film.

[0106] A support can be provided on one or both sides of the polarizing plate of the present invention, and it may be used as a polarizing plate with a support. The support preferably has a flat surface for bonding the polarizing plate, and since it is for optical applications, it is preferably a transparent substrate. Transparent substrates can be broadly divided into inorganic substrates and organic substrates, and examples of inorganic substrates include soda glass, borosilicate glass, quartz substrates, sapphire substrates, and spinel substrates, as well as organic substrates such as acrylic, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, and cycloolefin polymers.

[0107] To bond the polarizing plate to optical components, supports, or display devices, an adhesive layer may be formed on one or both sides of the polarizing plate. While adhesives and tacks can be used as the adhesive layer, acrylic resins, polyester resins, polyurethane resins, and other tacks are preferred. However, the adhesives and tacks used are not limited to these and can be appropriately selected depending on the application and components.

[0108] The polarizing plate of the present invention may be either a neutral gray polarizing plate or a color polarizing plate, depending on the application. Furthermore, these polarizing plates have excellent polarization performance, and discoloration and deterioration of polarization performance are suppressed even in high temperature and high humidity conditions, making them suitable for automotive or outdoor display applications.

[0109] <Display Device> The display device of the present invention comprises a polarizing film or polarizing plate of the present invention. Examples of display devices include liquid crystal display devices, projector devices, or OLEDs, which are known technologies, and can be applied to, but are not limited to, calculators, watches, laptop computers, liquid crystal televisions, car navigation systems, and indoor and outdoor measuring instruments and displays. In particular, it is suitably used in various displays that require high polarization performance and durability, such as in-vehicle display devices or outdoor display devices (for example, for display applications in industrial instruments and wearable applications). The dye-based polarizing film or dye-based polarizing plate provided in the display device is preferably neutral gray.

[0110] For example, in the case of a liquid crystal display device, a dye-based polarizer is placed on either the incident side or the output side of the liquid crystal cell, or both. 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. If the dye-based polarizer is in contact with the liquid crystal cell on the output side of the liquid crystal cell, the liquid crystal cell can be used as a support for the dye-based polarizer. If the dye-based polarizer is not in contact with the liquid crystal cell, it is preferable to use a dye-based polarizer with a support other than the liquid crystal cell. Furthermore, from the viewpoint of durability, it is preferable to place the dye-based polarizer on both the incident and output sides of the liquid crystal cell, and it is even preferable to place the polarizer surface of the dye-based polarizer on the liquid crystal cell side and the support surface on the light source side. The incident side of the liquid crystal cell is the light source side, and the opposite side is called the output side.

[0111] The driving method for the liquid crystal display device can be any appropriate method from known technologies. For example, it is preferable to use an active matrix drive type in which liquid crystal is sealed between a transparent substrate on which electrodes and thin-film transistors are formed and a transparent substrate on which counter electrodes are formed. Light emitted from a light source such as a cold cathode lamp or white LED passes through a dye-based polarizing plate, then through a liquid crystal cell, a color filter, and another dye-based polarizing plate, and is projected onto the display screen.

[0112] Furthermore, in recent years, OLEDs are increasingly being applied to applications requiring high durability, such as in-vehicle or indoor display devices. In OLEDs, a circular polarizer (a combination of a polarizer and a phase difference film) is sometimes placed on the viewing surface of the image display panel to suppress internal reflection phenomena, and the dye-based polarizer of the present invention can be used as the polarizer in this case. The phase difference film that can be combined with the dye-based polarizer can be, for example, only a λ / 4 film, or a configuration in which a λ / 2 film and a λ / 4 film are laminated, but is not limited to these and can be combined with known technologies.

[0113] The present invention will be described in more detail below with reference to examples, but these are illustrative and do not limit the invention in any way. Unless otherwise specified, percentages and parts in the examples are based on weight.

[0114] [Example 1] (Synthesis Step 1) 27.7 parts of commercially available 4-(4-aminophenyldiazenyl)benzenesulfonic acid were added to 300 parts of water and stirred to suspend the mixture. The pH was adjusted to 9.0 using 25% sodium hydroxide, and 17.3 parts of 40% sodium nitrite aqueous solution were added. The resulting aqueous solution was added dropwise to a mixture of 200 parts of water and 42 parts of 35% hydrochloric acid to prepare a diazo solution. 15.3 parts of 2,5-dimethoxyaniline were added to the obtained diazo solution, and the mixture was stirred for 8 hours while maintaining the pH at 1.5 to 4.0 with 15% sodium carbonate aqueous solution to complete the coupling reaction. After that, the mixture was salted out with sodium chloride and filtered to obtain 200 parts of a wet cake of the disazo compound shown in formula (11).

[0115] (Synthesis Step 2) 200 parts of the wet cake of the disazo compound represented by formula (11) obtained were added to 500 parts of water and stirred to suspend the mixture. The pH was adjusted to 9.0 using 25% sodium hydroxide, and 17.3 parts of 40% sodium nitrite aqueous solution were added. The resulting suspension was added dropwise to a mixture of 100 parts of water and 42 parts of 35% hydrochloric acid to prepare the diazo solution. Meanwhile, 31.9 parts of 1-hydroxy-6-amino-3,5-naphthalenedisulfonic acid were added to 300 parts of water and dissolved in 25% sodium hydroxide aqueous solution to make it weakly alkaline. The previously obtained diazo solution was added dropwise to this solution, maintaining the pH at 7.0 to 10.0, and stirred to complete the coupling reaction. After that, the mixture was salted out with sodium chloride and then filtered to obtain 200 parts of the wet cake of the trisazo compound represented by formula (12).

[0116] (Synthesis Step 3) 200 parts of the wet cake of the trisazo compound obtained in Synthesis Step 2 were added to 900 parts of water and stirred to suspend. 61 parts of monoethanolamine and 25 parts of copper sulfate pentahydrate were added and the mixture was reacted at 90-98°C for 10 hours to complete the copperification reaction. After that, the mixture was salted out with sodium chloride, filtered, and dried to obtain 20 parts of the copper azo compound shown in formula (13).

[0117] (Preparation of polarizing film) A polyvinyl alcohol resin film (VF-PE#6000 manufactured by Kuraray Co., Ltd., hereinafter referred to as "film") with a saponification degree of 99 mol% or more and a film thickness of 60 μm was immersed in 35°C hot water for 3 minutes to swell. The swollen film was immersed in a 45°C aqueous solution consisting of 0.2 parts of an azo compound represented by formula (13), 1.0 part of sodium tripolyphosphate, 1.0 part of anhydrous sodium sulfate, and 1000 parts of water to incorporate the azo compound. The film containing the azo compound was washed with water, and after washing, 2.7% boric acid was added. A crosslinking treatment with boric acid was performed for 1 minute in an aqueous solution at 40°C. The film obtained by the crosslinking treatment was stretched to 6.0 times its original size while being crosslinked for 5 minutes in an aqueous solution at 58°C containing 3.0% boric acid. While maintaining the tension of the stretched film, it was washed with room temperature water for 10 seconds. The film obtained by the washing treatment was dried at 70°C for 3 minutes to obtain a polarizing film. By the above method, a polarizing film according to the present invention containing an azo compound having the structure of formula (1) was prepared. This polarizing film was used as the measurement sample for Example 1.

[0118] [Example 2] The process was carried out in the same manner as in Example 1, except that 27.7 parts of 4-(4-aminophenyldiazenyl)benzenesulfonic acid in synthesis step 1 of Example 1 were replaced with 42.1 parts of 7-(4-amino-2-methylphenyldiazenyl)naphthalene-1,3-disulfonic acid, to obtain 30 parts of the copper azo compound represented by the following formula (14).

[0119] (Preparation of polarizing film) The measurement sample for Example 2 was obtained using the same procedure as for the preparation of the polarizing film in Example 1, except that 0.2 parts of the azo compound represented by formula (13) used in the preparation of the polarizing film in Example 1 were replaced with 0.2 parts of the compound represented by formula (14).

[0120] [Example 3] The procedure was the same as in Example 1, except that 27.7 parts of 4-(4-aminophenyldiazenyl)benzenesulfonic acid in synthesis step 1 of Example 1 was replaced with 39.3 parts of 4-(4-amino-2-methyl-5-(3'-sulfopropoxy)phenyldiazenyl)benzoic acid to obtain 28 parts of the copper azo compound represented by the following formula (15).

[0121] (Preparation of polarizing film) The measurement sample for Example 3 was obtained using the same procedure as for the preparation of the polarizing film in Example 1, except that 0.2 parts of the azo compound represented by formula (13) used in the preparation of the polarizing film in Example 1 were replaced with 0.5 parts of the compound represented by formula (15).

[0122] [Example 4] The procedure was the same as in Example 1, except that 15.3 parts of 2,5-dimethoxyaniline in synthesis step 1 of Example 1 was replaced with 18.0 parts of 5-acetylamino-2-methoxyaniline to obtain 18 parts of a copper azo compound represented by the following formula (16).

[0123] (Preparation of polarizing film) The measurement sample for Example 4 was obtained using the same procedure as for the preparation of the polarizing film in Example 1, except that 0.2 parts of the azo compound represented by formula (13) used in the preparation of the polarizing film in Example 1 were replaced with 0.5 parts of the compound represented by formula (16).

[0124] [Example 5] The procedure was the same as in Example 1, except that 15.3 parts of 2,5-dimethoxyaniline in synthesis step 1 of Example 1 was replaced with 15.3 parts of 2-methoxy-5-methylaniline to obtain 21.0 parts of the copper azo compound represented by the following formula (17).

[0125] (Preparation of polarizing film) The measurement sample for Example 5 was obtained using the same procedure as for the preparation of the polarizing film in Example 1, except that 0.2 parts of the azo compound represented by formula (13) used in the preparation of the polarizing film in Example 1 were replaced with 0.2 parts of the compound represented by formula (17).

[0126] [Example 6] Except that 27.7 parts of 4-(4-aminophenyldiazenyl)benzenesulfonic acid in synthesis step 1 of Example 1 were replaced with 32.1 parts of 4-(4-amino-5-methoxy-2-methylphenyldiazenyl)benzenesulfonic acid and 15.3 parts of 2,5-dimethoxyaniline were replaced with 15.3 parts of 2-methoxy-5-methylaniline, the same procedure as in Example 1 was followed to obtain 22 parts of a copper azo compound represented by the following formula (18).

[0127] (Preparation of polarizing film) The measurement sample for Example 6 was obtained using the same procedure as for the preparation of the polarizing film in Example 1, except that 0.2 parts of the azo compound represented by formula (13) used in the preparation of the polarizing film in Example 1 were replaced with 0.2 parts of the compound represented by formula (18).

[0128] [Comparative Example 1] (Preparation of Polarizing Film) A measurement sample for Comparative Example 1 was obtained using the same procedure as for the preparation of the polarizing film in Example 1, except that 0.2 parts of the azo compound represented by formula (13) used in the preparation of the polarizing film in Example 1 were replaced with 1.0 part of the compound described in Example 2 of Patent Document 7. The structure of the compound is shown in formula (21).

[0129] [Comparative Examples 2 and 3] A polarizing film containing the compound described in "Examples 5 and 9 (Formula (5))" of Patent Document 3 was used as a comparative example. Its structure is shown in the following formula (22). For Comparative Example 2, the compound represented by the following formula (22) was obtained in accordance with the description of Example 5 of Patent Document 3. For Comparative Example 3, the measurement sample for Comparative Example 3 was obtained in the same procedure as for the preparation of the polarizing film in Example 1, except that 0.2 parts of the azo compound represented by formula (13) used in the preparation of the polarizing film in Example 1 were replaced with 0.3 parts of the compound represented by formula (22).

[0130] [Comparative Examples 4 and 5] Comparative examples include polarizing films containing the compound described in "Examples 7 and 9 (Formula (7))" of Patent Document 3. The structure is shown in the following formula (23). For Comparative Example 4, the compound represented by the following formula (23) was obtained in accordance with the description of Example 7 of Patent Document 3. For Comparative Example 5, the measurement sample for Comparative Example 5 was obtained in the same procedure as for the preparation of the polarizing film in Example 1, except that 0.2 parts of the azo compound represented by formula (13) used in the preparation of the polarizing film in Example 1 of this specification were replaced with 0.3 parts of the compound represented by formula (23).

[0131] [Comparative Example 6] (Preparation of Polarizing Film) A measurement sample for Comparative Example 6 was obtained using the same procedure as for the preparation of the polarizing film in Example 1, except that 0.2 parts of the azo compound represented by formula (13) used in the preparation of the polarizing film in Example 1 were replaced with 0.2 parts of the compound described in Example 5 of Patent Document 5. The structure of the compound is shown in formula (24).

[0132] [Comparative Example 7] (Preparation of Polarizing Film) A measurement sample for Comparative Example 7 was obtained using the same procedure as for the preparation of the polarizing film in Example 1, except that 0.2 parts of the azo compound represented by formula (13) used in the preparation of the polarizing film in Example 1 were replaced with 0.5 parts of the compound described in Example 12 of Patent Document 4. The structure of the compound is shown in formula (25).

[0133] <Evaluation> The measurement samples obtained in each example and comparative example were evaluated as follows.

[0134] <Parallel Polarization Transmittance Ky, Orthogonal Polarization Transmittance Kz> The parallel polarization transmittance (Ky) and orthogonal polarization transmittance (Kz) of each sample were measured using a spectrophotometer (UH-4150, Hitachi High-Tech Science Co., Ltd.). Here, Ky is the transmittance when the absorption axis of the absolute polarizer and the absorption axis of the polarizing film are placed parallel to each other, and Kz is the transmittance when the absorption axis of the absolute polarizer and the absorption axis of the polarizing film are placed orthogonally to each other. The parallel polarization transmittances Ky and Kz for each wavelength were measured in the range of 380 nm to 780 nm, at wavelength intervals of 1 nm to 10 nm.

[0135] <Single-sample transmittance Ts, parallel-position transmittance Tp, and orthogonal-position transmittance Tc> Single-sample transmittance Ts is the spectral transmittance at each wavelength when the measurement sample is measured with a single sample. Parallel-position transmittance Tp is the spectral transmittance at each wavelength when two measurement samples are superimposed so that their absorption axes are parallel. Orthogonal-position transmittance Tc is the spectral transmittance when two measurement samples are superimposed so that their absorption axes are orthogonal. Using the Ky and Kz values ​​obtained from the measurements in the range of 380 nm to 780 nm, various transmittances in the range of 380 nm to 780 nm were calculated using the following formulas (I) to (III).

[0136] <Degree of Polarization ρ, Dichromatic Ratio> For each sample, the degree of polarization ρ and dichromatic ratio were determined using the following formulas.

[0137] <Evaluation of Uniformity> The brightness of a typical LED backlight (Dentsu Sangyo Co., Ltd. LP-160M-310310H) is approximately 8000 cd / m². ２After adjusting the settings accordingly, a standard iodine-based polarizing plate (SKN-18243P, manufactured by Nippon Kayaku Co., Ltd.) was placed on top of the backlight. Furthermore, the fabricated polarizing film was placed on top of the iodine-based polarizing plate so that its absorption axis was perpendicular to that of the polarizing film, and the uniformity of the fabricated polarizing film was evaluated.

[0138] Table 1 shows the staining solution concentrations required for Examples 1 to 6 and Comparative Example 1 to achieve a single-element transmittance (Ts) of 44% ± 0.5%.

[0139] As shown in Table 1, Comparative Example 1, which is a copper-modified tetrakisazo compound, required a dyeing solution concentration 2 to 5 times higher than that of Examples 1 to 6 of the present application, which are copper-modified trisazo compounds, in order to achieve almost the same transmittance. This indicates that while increasing the number of azo groups, i.e., converting to a copper-modified tetrakisazo compound, is effective in improving polarization properties, as described in Patent Document 7, the increased molecular size of the dye structure makes it difficult for the dye to penetrate the polymer network of polyvinyl alcohol, thus worsening the dyeing performance.

[0140] Table 2 shows the staining temperatures for Examples 1-6 and Comparative Examples 2-7, as well as the maximum absorption wavelength (λmax), single-color transmittance (Ts@λmax), polarization degree (ρ), dichromatic ratio, and uniformity evaluation results for the measured samples. Regarding uniformity, three experts skilled in the art evaluated the samples using the following criteria: "○: almost no uniformity," "△: some uniformity visible," and "×: clearly visible uniformity," and obtained a unified opinion.

[0141] In Table 2, Comparative Examples 2 and 4 refer to the description of Example 9 in Patent Document 3.

[0142] As shown in Table 2, Comparative Examples 2 and 4 required a high dyeing temperature of 70°C as described in Patent Document 3. In Comparative Example 3, although the azo compound of formula (22) was actually synthesized and dyeing was attempted at 45°C, the azo compound hardly dissolved in water at 45°C, and dyeing was not possible. In Comparative Example 5, although the compound of formula (23) dissolved in water at 45°C and dyeing was possible, the resulting polarizing film had many streaks and irregularities due to its low water solubility, making it unsuitable for use as a polarizing film or polarizing plate. In contrast, Examples 1 to 6 yielded good polarizing films, demonstrating sufficient solubility in water and dyeability of the copper trisazo compound of the present invention. Furthermore, while the dichromatic ratio of each comparative example was 30 or less, the dichromatic ratio of Examples 1 to 6 was 30 or more, showing a higher value than each comparative example and demonstrating high polarization characteristics.

[0143] Table 3 shows the orthogonal transmittance (Tc) and polarization degree (ρ) at 730 nm for Examples 1-4 and Comparative Examples 1 and 5-7.

[0144] As shown in Table 3, Examples 1-4 showed a higher degree of polarization at 730 nm than Comparative Examples 1, 5, and 6. Specifically, Examples 1-4 showed an orthogonal transmittance of less than 10% at 730 nm, and Examples 1-3 in particular showed an orthogonal transmittance of less than 5% at 730 nm. Furthermore, since Examples 1-4 showed a higher degree of polarization than Comparative Example 1, which is a copper-based tetrakisazo compound, and Comparative Examples 5 and 6, which are copper-based trisazo compounds, it was shown that the present compound has better polarization performance in the long-wavelength region. Although Comparative Example 7 showed a high degree of polarization at 730 nm, as shown in Table 2, its degree of polarization and dichromatic ratio at the maximum absorption wavelength (λmax) were the lowest among all examples and comparative examples, and it also showed unevenness, making it clearly inferior to the present compound when considering its use as a polarizing film.

[0145] <Example 7: Dye-based polarizing plate> A dye-based polarizing plate was prepared by laminating both sides of the polarizing film obtained in Example 1 with a triacetylcellulose film (TG-60UL, manufactured by Fujifilm Corporation) via a polyvinyl alcohol-based adhesive. One side of the obtained polarizing plate was laminated to glass using an adhesive and used as the observation sample for Example 7.

[0146] <Comparative Example 8: Iodine-based polarizer> As a general iodine-based polarizer, an iodine-based polarizer manufactured by Nippon Kayaku Co., Ltd. (product name: SKN-18243P) was bonded to glass using an adhesive on one side and used as the observation sample for Comparative Example 8.

[0147] The polarizing plates of Example 7 and Comparative Example 8 were observed for visual hue changes after 500 hours under heat-resistant conditions at an ambient temperature of 105°C, and after 500 hours under high-temperature and high-humidity conditions at an ambient temperature of 80°C and relative humidity of 90%. Three persons skilled in the art evaluated the plates using the following criteria: "○: almost no hue change", "△: hue change present", and "×: significant hue change", and obtained a unified opinion. The results are shown in Table 4.

[0148] As shown in Table 4, the dye-based polarizer of Example 7 showed almost no hue change even under high temperature and high humidity conditions. On the other hand, the iodine-based polarizer of Comparative Example 8 showed a very large hue change. In other words, the dye-based polarizer of the present invention has high environmental resistance and is suitable for use in display devices used in harsh environments.

[0149] [Example 11] Except that 27.7 parts of 4-(4-aminophenyldiazenyl)benzenesulfonic acid in synthesis step 1 of Example 1 were replaced with 31.1 parts of 4-(4-amino-3-chlorophenyldiazenyl)benzenesulfonic acid, 18 parts of a copper azo compound represented by the following formula (26) were obtained in the same manner as in Example 1.

[0150]

[0151] (Preparation of polarizing film) The measurement sample for Example 11 was obtained using the same procedure as for the preparation of the polarizing film in Example 1, except that 0.2 parts of the azo compound represented by formula (13) used in the preparation of the polarizing film in Example 1 were replaced with 0.2 parts of the compound represented by formula (26).

[0152] [Example 12] The procedure was the same as in Example 1, except that 27.7 parts of 4-(4-aminophenyldiazenyl)benzenesulfonic acid in synthesis step 1 of Example 1 were replaced with 33.5 parts of 2-(4-amino-2,5-dimethylphenyldiazenyl)-5-methoxybenzenesulfonic acid to obtain 21 parts of a copper azo compound represented by the following formula (27).

[0153]

[0154] (Preparation of polarizing film) The measurement sample for Example 12 was obtained using the same procedure as for the preparation of the polarizing film in Example 1, except that 0.2 parts of the azo compound represented by formula (13) used in the preparation of the polarizing film in Example 1 were replaced with 0.2 parts of the compound represented by formula (27).

[0155] Table 5 shows the staining solution concentrations for Examples 11 and 12 required to achieve a single-component transmittance (Ts) of 44% ± 0.5%.

[0156]

[0157] As shown in Tables 1 and 5, Comparative Example 1, which is a copper-based tetrakisazo compound, required a staining solution concentration five times higher than that of Examples 11 and 12 of the present application, which are copper-based trisazo compounds, in order to achieve almost the same transmittance.

[0158] Next, Table 6 shows the staining temperature for Examples 11 and 12, as well as the maximum absorption wavelength (λmax), single-color transmittance (Ts@λmax), polarization degree (ρ), dichromatic ratio, and evaluation results for unevenness of the measured samples. Here, unevenness was evaluated as follows: "○: Almost no unevenness", "△: Some unevenness is visible", and "×: Unevenness is clearly visible".

[0159]

[0160] As shown in Table 6, Examples 11 and 12 yielded good polarizing films, demonstrating sufficient solubility and staining properties in water of the copper trisazo compound of the present invention. Furthermore, the dichromatic ratio of Examples 11 and 12 was 30 or higher, which is higher than that of Comparative Examples 2 to 7 shown in Table 6, indicating high polarization characteristics.

[0161] Table 7 shows the orthogonal transmittance (Tc) and polarization degree (ρ) at 730 nm for Examples 11 and 12.

[0162]

[0163] As shown in Tables 7 and 3, Examples 11 and 12 showed a higher degree of polarization at 730 nm than Comparative Examples 1, 5, and 6. Specifically, Examples 11 and 12 showed orthogonal transmittance at 730 nm to a value lower than 10%, and in particular, Example 11 showed an orthogonal transmittance at 730 nm to a value lower than 5%. Furthermore, since Examples 11 and 12 showed a higher degree of polarization than Comparative Example 1, which is a copper-modified tetrakisazo compound, and Comparative Examples 5 and 6, which are copper-modified trisazo compounds, it was shown that the present compound has better polarization performance in the long-wavelength region.

[0164] Polarizing films or polarizing plates made using the azo compound of the present invention can be optionally equipped with a protective or functional layer and a transparent support such as glass, quartz, or sapphire, and are applicable to liquid crystal projectors, calculators, watches, laptop computers, liquid crystal televisions, polarizing lenses, polarizing glasses, car navigation systems, and indoor and outdoor measuring instruments and displays. In particular, the polarizing films or polarizing plates of the present invention can be suitably used in liquid crystal display devices, such as reflective liquid crystal display devices, semi-transparent liquid crystal display devices, and other non-liquid crystal display devices such as OLEDs. Furthermore, the polarizing films or polarizing plates of the present invention can also provide high durability. This durability means that the display device exhibits virtually no hue change even in an environment of 85°C with an ambient temperature of 105°C or a relative humidity of 85%. Particularly preferred applications include in-vehicle displays, liquid crystal projectors, head-up displays, and outdoor displays, where not only high contrast but also heat resistance, humidity resistance, and light resistance are required.

Claims

1. Copper azo compounds or salts thereof represented by the following formula (1): (In formula (1), A represents a sulfo group or a carboxyl group, Q １ Q ２ , and R １ ~R ３ Each of the terms independently represents an arbitrary substituent, and n is an integer between 0 and 3.

2. In formula (1), A is a sulfo group, and R １ to R ３ are each independently a hydrogen atom, a chlorine atom, C １ to C ４ alkyl group, C １ to C ４ alkoxy group, C １ to C ４ alkoxy group having a sulfo group, or C １ to C ４ alkylcarbonylamino group, Q １ and Q ２ are each independently a hydrogen atom, a chlorine atom, a nitro group, a hydroxy group, C １ to C ４ alkyl group, C １ to C ４ alkoxy group, C １ to C ４ alkoxy group having a sulfo group, C ６ to C １２ arylcarbamoyl group, C ６ to C １２ arylcarbamoyl group having a sulfo group and / or a carboxy group, or C １ to C ４ alkylcarbonylamino group. The copperized azo compound or a salt thereof according to claim 1, 3. In formula (1), A is a sulfo group, and R １ ~R ３ Each of them independently forms a hydrogen atom, C １ ~C ４ alkyl group, C １ ~C ４ C having an alkoxy group and a sulfo group １ ~C ４ It is an alkoxy group or an acetylamino group, Q １ and Q ２ Each of these independently consists of a hydrogen atom, a chlorine atom, a nitro group, and C. １ ~C ４ alkyl group, C １ ~C ４ C having an alkoxy group and a sulfo group １ ~C ４ The copper azo compound or salt thereof according to claim 1, wherein the compound is an alkoxy group.

4. The copper azo compound or salt thereof represented by formula (1) is the azo compound or salt thereof according to any one of claims 1 to 3, represented by the following formula (2): (In formula (2), A represents a sulfo group, and R １ and R ２ Each of them independently forms a hydrogen atom, C １ ~C ４ alkyl group, C １ ~C ４ C having an alkoxy group and a sulfo group １ ~C ４ It is an alkoxy group, Q １ and Q ２ Each of these independently consists of a hydrogen atom, a chlorine atom, a nitro group, and C. １ ~C ４ alkyl group, C １ ~C ４ C having an alkoxy group and a sulfo group １ ~C ４ (This is an alkoxy group, where n is an integer between 0 and 3.) 5. A polarizing film containing a substrate, characterized in that the substrate contains a copper azo compound or a salt thereof as described in any one of claims 1 to 4.

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

7. A display device comprising the polarizing film described in claim 5 or the polarizing plate described in claim 6.

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