Polarizing element and polarizing plate for visible and infrared regions, and liquid crystal display device including the same

Abstract

A polarizing element characterized by containing at least an azo compound represented by formula (1) or a salt thereof and further containing a specific azo compound.

Description

Technical Field

[0001] The present invention relates to a polarizing element, a polarizing plate, and a liquid crystal display device containing an azo compound or a salt thereof that absorbs light in the visible region and the near-infrared region.

Background Art

[0002] Polarizing elements are generally manufactured by adsorbing and aligning iodine, which is a dichroic dye, or a dichroic dye on a polyvinyl alcohol-based resin film. A polarizing element using iodine as a dichroic dye is called an iodine-based polarizing element, while a polarizing film using a dichroic dye as a dichroic dye is called a dye-based polarizing element. A film made of triacetyl cellulose or the like is laminated on at least one side of these polarizing elements via an adhesive layer to form a polarizing plate, which is used in a liquid crystal display device or the like. Although the polarizing film using iodine or a dye as a dichroic dye in such a polarizing element is excellent in polarizing performance, it is not a polarizing plate capable of controlling the transmittance in the infrared wavelength region.

[0003] In recent years, in applications such as recognition light sources for touch panels, security cameras, sensors, counterfeit prevention, and communication devices, polarizing plates for use in the infrared region as well as polarizing plates for visible wavelengths are in demand. In response to such demands, infrared polarizing plates in which iodine-based polarizing plates are polyenized as in Patent Document 1, infrared polarizing plates using wire grids as in Patent Documents 2 and 3, infrared polarizers in which glass containing fine particles is stretched as in Patent Document 4, and types using cholesteric liquid crystals as in Patent Document 5 have been reported. Patent Document 1 has poor durability, poor heat resistance, wet heat resistance, and light resistance, and is not practical. Wire grid types as in Patent Documents 2 and 3 can be processed into film types and are stable as products, so they are becoming more and more popular. However, since the optical properties cannot be maintained without nano-level unevenness on the surface, the surface must not be touched, which limits the applications in which they can be used, and it is difficult to perform anti-reflection or anti-glare processing. Glass stretching types containing fine particles as in Patent Document 4 have high durability and high dichroism, which makes them practical. However, since it is a glass that is stretched while containing fine particles, the element itself is easily broken and fragile, and since it does not have the flexibility of conventional polarizing plates, there are problems in that it is difficult to perform surface processing or to attach it to other substrates. The technology of Patent Document 5 is a technology that uses circularly polarized light that has been publicly disclosed for a long time, but it is difficult to form stray light or absolute polarized light because the color changes depending on the viewing angle and it is basically a polarizing plate that uses reflection. In other words, there was no polarizing plate that is an absorption type polarizing element like a general polarizing plate, is a film type, is flexible, and has high durability and is compatible with the infrared wavelength region. Patent Document 6 and Patent Document 7 are disclosed as technologies that can correspond to such polarizing plates compatible with the infrared wavelength region with high durability, but a polarizing plate that has a wider band and a higher polarization degree in the visible and infrared wavelength regions was desired. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 2,494,686 [Patent Document 2] JP 2013-24982 A [Patent Document 3] JP 2016-148871 A [Patent Document 4] JP 2004-86100 A [Patent Document 5] JP 2013-64798 A [Patent Document 6] International Publication No. 2018 / 088558 [Patent Document 7] International Publication No. 2019 / 117123 [Patent Document 8] JP 2009-132794 A [Non-patent literature]

[0005] [Non-Patent Document 1] Dye Chemistry; by Yutaka Hosoda, Gihodo Publishing, 1957 [Non-Patent Document 2] Application of Functional Dyes, 1st Edition, CMC Publishing Co., Ltd., Supervised by Masahiro Irie, p98-100 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present application is to provide a polarizing element, a polarizing plate, and an optical device having high polarizing function over a wide band from the visible region to the infrared region. [Means for solving the problem]

[0007] As a result of extensive investigations aimed at solving the above problems, the present inventors have developed a novel polarizing element containing the following azo compound or a salt thereof. [Invention 1] Contains at least an azo compound represented by formula (1) or a salt thereof, and An azo compound represented by formula (2) or a salt thereof, An azo compound represented by formula (3) or a salt thereof, An azo compound represented by formula (6) or a salt thereof An azo compound represented by formula (7) or a salt thereof, An azo compound represented by formula (8) or a salt thereof An azo compound represented by formula (9) or a salt thereof, An azo compound represented by formula (10) or a salt thereof, and An azo compound represented by formula (11) or a salt thereof Further containing an azo compound selected from A polarizing element characterized by: [ka] (In formula (1), A 1 is an optionally substituted phenyl group, an optionally substituted naphthyl group, or an optionally substituted heterocyclic group; A 2 , A 3 , A 4 each independently represents a phenyl group which may have a substituent or a naphthyl group which may have a substituent; R 1 is a hydrogen atom, a hydroxy group, a C1-4 alkoxy group, or a substituted or unsubstituted amino group, m is an integer of 0 to 5, n is 1 or 2, and k is 0 or 1; the hydrogen atoms of ring a and ring b are each independently selected from the group consisting of a substituent R 1 , substituent SO 3 may be substituted with H. [ka] (In formula (2), Ab 11 , Ab 12 each independently represents a naphthyl group having a substituent or a phenyl group having a substituent, at least one of the substituents being a hydrogen atom, a sulfo group, a C1-4 alkyl group, a C1-4 alkoxy group, a C1-4 alkoxy group having a sulfo group, a carboxy group, a nitro group, an amino group, or a substituted amino group; Rb 11 , Rb 12each independently represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, a sulfo group, or a C1-4 alkoxy group having a sulfo group. [ka] (In formula (3), Ag 1 represents a phenyl group having a substituent or a naphthyl group having a substituent, Bg and Cg are each independently represented by the following formula (4) or the following formula (5), and at least one of them represents formula (4), Xg 1 represents an amino group which may have a substituent, a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a naphthotriazole group which may have a substituent, or a benzoylamino group which may have a substituent. [ka] (In formula (4), Rg 1 represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group, and j represents an integer of 0 to 2. [ka] (In formula (5), Rg 2 and Rg 3 each independently represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group. [ka] (In formula (6), Ab 21 represents a phenyl group or a naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group, Rb 21 ~Rb 24each independently represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group; Rb 25 and Rb 26 each independently represents a hydrogen atom, a hydroxyl group, a C1-4 alkyl group, or a C1-4 alkoxy group, Xb 21 represents an unsubstituted amino group, an amino group having one or two C1-4 alkyl groups which may have substituents (selected from the group consisting of C1-4 alkoxy groups, sulfo groups, amino groups, C1-4 alkylamino groups, hydroxy groups, carboxy groups, and carboxyethylamino groups), a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a naphthotriazole group which may have a substituent, or a benzoylamino group which may have a substituent; d represents 0 or 1, and when d is 1, Rb 25 and a metal complex compound based on the hydroxy group of the naphthyl group and a metal atom; Rb 26 represents a hydrogen atom, a lower alkyl group, or a lower alkoxy group. [ka] (In formula (7), Ab 31 represents a phenyl group or a naphthyl group having at least one substituent selected from the group consisting of a sulfo group, a carboxy group, a nitro group, and an amino group, Rb 31 ~Rb 33 represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group; Xb 31 represents an unsubstituted amino group, an amino group having one or two C1-4 alkyl groups which may have substituents (selected from the group consisting of C1-4 alkoxy groups, C1-4 alkylamino groups, hydroxy groups, carboxy groups, sulfo groups, amino groups, and substituted amino groups), a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a naphthotriazole group which may have a substituent, a benzoylamino group which may have a substituent, or a benzoyl group which may have a substituent,1 or e 2 each independently represents 0 or 1) [ka] (In formula (8), Ac 1 represents a phenyl group or a naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group, Rc 11 ~Rc 14 each independently represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group. [ka] (In formula (9), Ac 2 represents a phenyl group or a naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group, Rc 21 ~Rc 27 each independently represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group, Rc 28 represents a hydrogen atom, a C1-4 alkyl group, or a C1-4 alkoxy group having a sulfo group, Xc 2 represents an unsubstituted amino group, an amino group having one or two C1-4 alkyl groups which may have a substituent (selected from the group consisting of C1-4 alkoxy groups, sulfo groups, C1-4 alkylamino groups, hydroxy groups, amino groups, substituted amino groups, carboxy groups, and carboxyethylamino groups), a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a naphthotriazole group which may have a substituent, or a benzoylamino group which may have a substituent, and r, p, and q each independently represent 0 or 1, except for the case where r, p, and q are all 1. [ka] (In formula (10), Ay 11 represents a sulfo group, a carboxy group, a hydroxy group, a C1-4 alkyl group, or a C1-4 alkoxy group; Ry 11 ~Ry 14 each independently represents a hydrogen atom, a sulfo group, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group, and f represents an integer of 1 to 3. [ka] (In formula (11), Ay 21 and Ay 22 each independently represents a naphthyl group which may have a substituent or a phenyl group which may have a substituent; R 21 , Ry 22 , Ry 27 , Ry 28 are each independently a hydrogen atom, a C1-4 alkyl group, or a C1-4 alkoxy group; Ry 23 ~Ry 26 each independently represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group, and each of s and t independently represents 0 or 1. [Invention 2] 2. The polarizing element according to claim 1, comprising at least an azo compound selected from the group consisting of formulas (2), (3), (6) and (7) or a salt thereof. [Invention 3] The polarizing element according to invention 1, comprising at least an azo compound selected from formula (8) and formula (9) or a salt thereof. [Invention 4] 2. The polarizing element according to claim 1, comprising at least an azo compound selected from formula (10) and formula (11) or a salt thereof. [Invention 5] An azo compound selected from the group consisting of formula (2), formula (3), formula (6), and formula (7) or a salt thereof; An azo compound or a salt thereof selected from the group consisting of formula (8) and formula (9), The polarizing element according to claim 1, comprising at least [Invention 6] An azo compound selected from the group consisting of formula (2), formula (3), formula (6), and formula (7) or a salt thereof; An azo compound or a salt thereof selected from the group consisting of formula (10) and formula (11), The polarizing element according to claim 1, comprising at least [Invention 7] An azo compound or a salt thereof selected from the group consisting of formula (8) and formula (9), An azo compound or a salt thereof selected from the group consisting of formula (10) and formula (11), The polarizing element according to claim 1, comprising at least [Invention 8] 8. The polarizing element according to any one of claims 1 to 7, comprising a substrate which is a polyvinyl alcohol-based resin film. [Invention 9] A polarizing plate comprising the polarizing element according to any one of Inventions 1 to 8 and a transparent protective layer on at least one surface of the polarizing element. [Invention 10] An optical device comprising the polarizing element according to any one of Inventions 1 to 8 or the polarizing plate according to Invention 9. [Invention 11] The optical device according to invention 10, which is a liquid crystal display device. Effect of the Invention

[0008] The polarizing element of the present invention has high polarization performance over a wide band from the visible region to the infrared region. In one embodiment, the polarizing element of the present invention has high durability while absorbing in the infrared region. In one embodiment, the polarizing element of the present invention has an achromatic color in the visible region, absorbs in the infrared region, and has high durability. In one embodiment, the polarizing element of the present invention can be used not only in polarizing plates and liquid crystal display devices, but also in sensors and security devices that function with light from the visible range to the infrared range, cameras that can sense light from the visible range to the infrared range, and the like. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In the claims and the specification of the present application, the "substituent" may contain a hydrogen atom, and therefore the hydrogen atom may be described as the "substituent" for convenience. "May have a substituent" means that it may have no substituent. For example, "a phenyl group which may have a substituent" includes a simple unsubstituted phenyl group and a phenyl group which has a substituent. In addition, in the present application, "lower" in lower alkyl groups, lower alkoxy groups, etc., indicates that the number of carbon atoms is 1 to 4 (C1 to 4), preferably 1 to 3 (C1 to 3), unless otherwise specified.

[0010] Examples of the "lower (C1-4) alkyl group" include straight-chain alkyl groups such as methyl, ethyl, n-propyl, and n-butyl; branched-chain alkyl groups such as sec-butyl and tert-butyl; and unsaturated hydrocarbon groups such as vinyl.

[0011] Examples of the "lower (C1-4) alkoxy group" include a methoxy group, an ethoxy group, a propoxy group, an n-butoxy group, a sec-butoxy group, and a tert-butoxy group.

[0012] In this specification, "an azo compound, a metal complex compound thereof, or a salt thereof" may be collectively referred to simply as "an azo compound" or "an azo compound or a salt thereof".

[0013] The present invention relates to a polarizing element using an azo-based compound having absorption in the visible range and an azo-based compound having absorption in the infrared range. The azo compound is a dye, and the azo compound is dyed (contained (impregnated)) in a substrate, and the substrate is stretched to orient the substrate, thereby exhibiting anisotropic absorption, thereby obtaining a polarizing element. The above-mentioned visible range generally refers to 400 to 7000 nm. The above-mentioned infrared range generally refers to 700 to 30000 nm, but the polarizing film containing a dichroic dye formed by absorbing the infrared range obtained in the present invention functions as a near-infrared polarizing film, and the wavelength of near-infrared refers to a wavelength of 700 to 1500 nm, and the polarizing element exhibits high polarizing function at this wavelength and in the visible range.

[0014] The polarizing element of the present invention contains an azo compound represented by formula (1) or a salt thereof.

Chemical formula

[0015] In formula (1), A 1 is a phenyl group which may have a substituent, a naphthyl group which may have a substituent, or a heterocyclic group which may have a substituent, and A 2 , A 3 , A 4 are each independently a phenyl group which may have a substituent or a naphthyl group which may have a substituent, R 1 is a hydrogen atom, a hydroxy group, a C1-4 alkoxy group, a substituted or unsubstituted amino group, m is an integer of 0-5, n is 1 or 2, k is 0 or 1, and the hydrogen atoms of ring a and ring b may be substituted with substituent R 1 , substituent SO 3 H.

[0016] Regarding the above A 1 , the substituents of the phenyl group which may have a substituent are not particularly limited. For example, a C1-4 alkyl group which may have a substituent, a C1-4 alkoxy group which may have a substituent, a C1-4 alkoxy group which may have a sulfo group, an aryloxy group which may have a substituent, a hydroxy group, a sulfo group, a carboxy group, a nitro group, a substituted or unsubstituted amino group, an amide group, a halogen atom, etc. may be mentioned. Substituents selected from the group consisting of a C1-4 alkoxy group which may have a substituent, a sulfo group, a nitro group, and a carboxy group are preferable.

[0017] Regarding the above A 1In the above formula, the substituent of the naphthyl group which may have a substituent is not particularly limited, and examples thereof include a C1-4 alkyl group which may have a substituent, a C1-4 alkoxy group which may have a substituent, a C1-4 alkoxy group which may have a sulfo group, an aryloxy group which may have a substituent, a hydroxy group, a sulfo group, a carboxy group, a nitro group, a substituted or unsubstituted amino group, an amido group, and the like. Of these, a substituent selected from the group consisting of a C1-4 alkoxy group which may have a substituent, a sulfo group, a hydroxy group, a nitro group, and a carboxy group, is preferred, and a sulfo group or a hydroxy group is more preferred.

[0018] Examples of the "C1 to 4 alkyl group" in the C1 to 4 alkyl group which may have the above-mentioned substituent include straight-chain alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an n-butyl group, etc., branched-chain alkyl groups such as an isopropyl group, a sec-butyl group, a tert-butyl group, etc., and cyclic aliphatic hydrocarbon groups such as a cyclobutyl group.

[0019] Examples of the "C1 to 4 alkoxy group" in the C1 to 4 alkoxy group which may have a substituent include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an isopropoxy group, a sec-butoxy group, a tert-butoxy group, and a cyclobutoxy group.

[0020] Examples of the C1 to C4 alkoxy group optionally having a sulfo group include a sulfomethoxy group, a sulfoethoxy group, a 3-sulfopropoxy group, a 4-sulfobutoxy group, and a 3-sulfobutoxy group.

[0021] Examples of the "aryloxy group" of the above-mentioned optionally substituted aryloxy group include a phenoxy group, a naphthoxy group, and the like.

[0022] Examples of the substituted or unsubstituted amino group include mono-substituted amino groups such as amino group, methylamino group, ethylamino group, n-propylamino group, n-butylamino group, monophenylamino group, and mononaphthylamino group, and di-substituted amino groups such as dimethylamino group, diethylamino group, diphenylamino group, N-ethyl-N-methylamino group, and N-ethyl-N-phenylamino group. These substituted amino groups may further have a substituent.

[0023] Examples of the amide group include a formamide group (HC(=O)-NH-), an acetamide group (H 3 CC(=O)-NH-), benzoylamino group (C 6 H 5 -C(=O)-NH- etc. X -C(=O)-NH- group and aminocarbonyl group (H 2 NC(=O)-), substituted or unsubstituted aminocarbonyl group (R Y R Z NC(=O)-). X , R Y , R Z Examples of the substituent include the substituents exemplified for the above "substituted or unsubstituted amino group".

[0024] The "substituents" in the C1-4 alkyl group which may have a substituent and the C1-4 alkoxy group which may have a substituent are not particularly limited and include, for example, a hydroxy group, a sulfo group, a carboxy group, the above-mentioned substituted or unsubstituted amino group, an amido group, etc. The "substituents" in the aryloxy group which may have a substituent and the "substituents" which the substituted amino group may further have are not particularly limited and include, for example, a C1-4 alkyl group which may have a substituent.

[0025] Above A 1When n is a naphthyl group which may have a substituent, the bonding position of the azo group bonded to the naphthyl group is not particularly limited, but is preferably the 1st position. When the substitution position of the azo group is the 1st position, a form in which a hydroxy group is substituted at the 8th position counterclockwise is more preferable, and further, a naphthyl group represented by formula (12) in which a sulfo group is substituted at any position is particularly preferable. In formula (12), n 2 is 1 or 2. [ka]

[0026] Above A 1 It is also preferable that the heterocyclic group may have a substituent. Examples of the "heterocyclic group" of the heterocyclic group that may have a substituent include a thiazole group, an oxazole group, an imidazole group, a thiophene group, a furan group, a pyrrole group, a thiadiazole group, a pyrazole group, a pyridyl group, a piperazinyl group, a quinolyl group, a benzimidazole group, a naphthoimidazole group, a benzothiazole group, a naphthothiazole group, a benzothiadiazole group, a benzotriazole, and a naphthotriazole, and the like. The "substituent" in the heterocyclic group that may have a substituent is not particularly limited, and may be the same as the substituent in the C1-4 alkyl group that may have a substituent and the C1-4 alkoxy group that may have a substituent, and it is preferable that the heterocyclic group has a sulfo group as a substituent.

[0027] In the above formula (1), A 2 , A 3 , A 4 are each independently a phenyl group which may have a substituent or a naphthyl group which may have a substituent. The substituent in the phenyl group which may have a substituent or the naphthyl group which may have a substituent is not particularly limited, and examples thereof include A 1 As described below, the substituents A in the above formula (1) can be independently selected from those exemplified above. 2 , A 3 , A 4are each independently represented by formula (13) or formula (14) described below, 2 , A 3 , A 4 At least one of these is preferably represented by formula (13).

[0028] In the above formula (1), R 1 R is a hydrogen atom, a hydroxyl group, a C1-4 alkoxy group, or a substituted or unsubstituted amino group. 1 R is preferably a hydrogen atom or a hydroxyl group, more preferably a hydroxyl group. 1 The substitution position of is not particularly limited, but when the azo bond site to ring a is the 1-position, substitution at the 8-position is preferred.

[0029] The above formula (1) may be an azo compound represented in the form of a free acid, but may also be a salt of a metal ion or an ammonium ion. Examples of metal ions include alkali metal ions such as lithium ion, sodium ion, and potassium ion, and alkaline earth metal ions such as calcium ion and magnesium ion. Examples of ammonium ions include ammonium ion, methylammonium ion, dimethylammonium ion, triethylammonium ion, tetraethylammonium ion, tetra-n-propylammonium ion, tetra-n-butylammonium ion, and triethanolammonium ion. More specifically, in the case of a free acid, for example, sulfonic acid (-SO 3 H) for sodium ions, and sodium sulfonate (-SO 3 Na) for ammonium ion, and ammonium sulfonate (-SO 3 NH 4 )

[0030] The hydrogen atoms of the rings a and b in the above formula (1) are each independently selected from the group consisting of the above substituents R 1 and / or the substituent SO 3 It may be substituted with H.

[0031] In the above formula (1), it is preferable that either one or both of the rings a and b are substituted with a sulfo group. It is also preferable that the ring b is substituted with a hydroxy group. Among them, when the azo bond site to the ring a is the 1st position, it is particularly preferable that the 8th position is substituted with a hydroxy group, the 3rd and 7th positions are substituted with a sulfo group, the 6th position is substituted with a hydroxy group, the 8th position is substituted with a sulfo group, and the 3rd position is substituted with a sulfo group.

[0032] In the above formula (1), A 2 , A 3 , A 4 are each independently represented by formula (13) or formula (14), 2 , A 3 , A 4 At least one of the above is preferably expressed by formula (13) since a broadband polarizing element can be obtained. [ka] [ka]

[0033] In formula (13), R 2 represents a hydrogen atom, a halogen atom, an amido group, a sulfo group, a carboxy group, a hydroxy group, a C1-4 alkyl group, a C1-4 alkoxy group, a substituted or unsubstituted amino group, a C1-4 alkoxy group having a sulfo group, or a C1-4 alkoxy group having a carboxy group, m 2 represents an integer from 0 to 6. 3 represents an integer from 0 to 2.

[0034] In formula (14), R 3 and R 4 each independently represents a hydrogen atom, a halogen atom, an amido group, a sulfo group, a carboxy group, a C1-4 alkyl group, a C1-4 alkoxy group, a C1-4 alkoxy group having a hydroxy group, a C1-4 alkoxy group having a sulfo group, or a C1-4 alkoxy group having a carboxy group.

[0035] In the above formula (13), m 2 is preferably 0 to 4, more preferably 0 to 2, and particularly preferably 0 or 1. 2 is preferably a hydrogen atom or a hydroxyl group. 3 is preferably 0 or 1, and more preferably 1. 2 The substitution position of is A in formula (1). 1 When the position of the azo group on the side is regarded as the 1st position, the 2nd, 3rd or 5th position is preferred. More preferably, a hydrogen atom or a methoxy group is substituted at the 2nd or 3rd position, and even more preferably, a hydrogen atom or a methoxy group is substituted at the 3rd position. A hydrogen atom or a hydroxy group is preferably substituted at the 8th position, and more preferably, a hydroxy group is substituted. In the above formula (1), A 3 , A 4 When the compound has a structure represented by formula (13), it is preferable because it is a dye for obtaining a polarizing film having a wide band and a high degree of polarization. Specifically, k=0 and A 3 has the structure of formula (13), or k=1 and A 4 It is particularly preferred when the compound has the structure of formula (13):

[0036] In the above formula (14), R 3 and R 4 each independently represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, a C1-4 alkoxy group having a hydroxyl group, or a C1-4 alkoxy group having a sulfo group. The C1-4 alkyl group, the C1-4 alkoxy group, the C1-4 alkoxy group having a hydroxyl group, and the C1-4 alkoxy group having a sulfo group may each be the same as above. In the above formula (1), A 3 , A 4 has a structure represented by formula (14), and R 3 or R 4 When each independently represents a hydrogen atom or a C1-4 alkoxy group, the polarizing film of the present invention has a broad wavelength band and a high polarization degree. 3 or R 4 are preferably each independently a methoxy group or an ethoxy group, and particularly preferably R 3and R 4 is a methoxy group. Specifically, k=0 and A 3 has a structure of formula (14), and R 3 and R 4 is preferably a methoxy group, or k=1, 4 has a structure of formula (14), and R 3 and R 4 is particularly preferred when is a methoxy group.

[0037] The above formula (1) is preferably represented by formula (15) in the form of a free acid. 1 ~A 4 , n, k, ring a, and ring b may be the same as those in the above formula (1). When the above formula (1) is represented by formula (15), it is preferable because a near-infrared polarizing film having a wider band and a higher polarization degree can be obtained. [ka]

[0038] It is also preferable that the above formula (1) is represented by formula (16) in the form of a free acid. 5 , R 6 , R 7 each independently represents a hydrogen atom, a hydroxyl group, a C1-4 alkoxy group, or a substituted or unsubstituted amino group; m 3 ~m 5 Each represents an integer of 0 to 5. 4 and n 5 Each independently represents 1 or 2. 1 may be the same as k in the above formula (1). The C1-4 alkoxy group and the substituted or unsubstituted amino group may be the same as those described above. It is preferable that the above formula (1) is represented by formula (16), because a near-infrared polarizing film having a wider bandwidth and a higher polarization degree can be obtained. [ka]

[0039] Next, specific examples of the water-soluble dichroic dye represented by the above formula (1) or a salt thereof are given below. In the formula, the sulfo group, carboxy group and hydroxy group are represented in the form of free acid. [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0040] The azo compounds represented by the above formula (1), formula (15) and formula (16) or salts thereof can be produced by diazotization and coupling according to a typical method for producing an azo dye as described in, for example, Non-Patent Document 1.

[0041] As an example of a specific production method, a production method for the azo compound represented by the above formula (15) in the case of k=0 will be described below.

[0042] The aminonaphthalenes or anilines of the following formula (1-A) are diazotized and subjected to primary coupling with the aminonaphthalenes or anilines of the following formula (1-B) to obtain a monoazoamino compound of the following formula (1-C). The monoazoamino compound (1-C) is diazotized and subjected to secondary coupling with the aminonaphthalenes or anilines of the following formula (1-D) to obtain a disazoamino compound of the following formula (1-E). The disazoamino compound (1-E) is diazotized and subjected to tertiary coupling with naphthols of the following formula (1-F) to obtain an azo compound of the formula (15). [ka]

[0043] In the above-mentioned production method, the diazotization step is preferably carried out by a forward method of mixing a nitrite such as sodium nitrite with an aqueous solution or suspension of a mineral acid such as hydrochloric acid or sulfuric acid of the diazo component, or by a reverse method of adding a nitrite to a neutral or weakly alkaline aqueous solution of the diazo component and then mixing this with a mineral acid. The temperature of the diazotization is suitably -10 to 40°C. The coupling step with anilines is preferably carried out by mixing an aqueous acidic solution such as hydrochloric acid or acetic acid with each of the above-mentioned diazo solutions under acidic conditions at a temperature of -10 to 40°C and a pH of 2 to 7.

[0044] The azo compounds of the above formulae (1-C) and (1-E) obtained by coupling can be filtered as they are, precipitated by acid precipitation or salt precipitation and filtered, or can proceed to the next step as a solution or suspension. If the diazonium salt is poorly soluble and in the form of a suspension, it can be filtered and used as a press cake in the next coupling step.

[0045] The tertiary coupling reaction between the diazotized product of the disazoamino compound of the above formula (1-E) and the naphthols of the above formula (1-F) is preferably 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 completed, the obtained azo compound or salt of the formula (15) is preferably precipitated by salting out and filtered out. If purification is required, the salting out may be repeated or an organic solvent may be used to precipitate the compound from water. Examples of the organic solvent used for purification include water-soluble organic solvents such as alcohols such as methanol and ethanol, and ketones such as acetone.

[0046] In the polarizing element of the present invention, the content of the azo compound represented by formula (1) or a salt thereof is preferably 0.0001 to 5 parts by mass, and more preferably 0.001 to 1 part by mass, relative to 100 parts by mass of the aqueous solution.

[0047] The azo compound of formula (1) or its salt used in the present invention is useful as a dye for a polarizing element. In one embodiment, the azo compound of formula (1) or its salt can be used to produce a high-performance dye-based near-infrared polarizing element that has polarizing properties in the near-infrared region and is moisture-resistant, heat-resistant, and light-resistant.

[0048] The polarizing function may be generally indicated by a dichroic ratio calculated from the difference in transmittance, the degree of polarization, or the ratio of light absorption in different axes (absorbance ratio). One index of the polarizing function in the present application is the degree of polarization. In one preferred embodiment of the present application, the absorbance ratio is 5 or more in the wavelength range of 700 to 1500 nm in the transmittance when polarized light is incident in the infrared region, between the absorbance of the axis showing the highest transmittance for polarized light and the absorbance of the axis showing the lowest transmittance for polarized light. The absorbance ratio is generally called the dichroic ratio, and a dichroic ratio of 5 or more indicates that the polarizing function has general absorption anisotropy. The higher the dichroic ratio, the more preferable it is, and more preferably 10 or more, and even more preferably 20 or more. The dichroic ratio is preferably 5 or more in terms of significantly increasing the number of uses depending on the absorption anisotropy, i.e., the polarizing function. In addition, it is more preferable that the wavelength at which the dichroic ratio shows the highest value is 700 to 1500 nm, but this is not necessarily limited thereto, and the present application is characterized in that the compound of formula (1) is used to provide an absorption anisotropy, i.e., a polarizing function, as a dichroic ratio of 5 or more at 700 to 1500 nm, and one embodiment of the present invention is characterized in that a polarizing element having an even higher dichroic ratio of 10 or more at 700 to 1500 nm can be obtained. Specifically, when the single transmittance is 30%, a dichroic ratio of 5 means that the degree of polarization is 88.2%, which is about 90%, and a dichroic ratio of 10 means that the degree of polarization is 98.3%, which is about 99%.

[0049] In the polarizing element, at least one dichroic dye exhibiting polarization properties in the visible range is used for the purpose of color correction and / or improving polarization performance to an extent that does not impair the performance of the present invention. For example, at least one dichroic dye exhibiting polarization properties in the visible range other than the azo compound represented by formula (1) may be contained. By using a dye having polarization properties in the visible light range in combination, a high-performance dye-based polarizing element of neutral gray that can be controlled not only in the visible light range as in the past, but also in the near-infrared range can be realized. Therefore, the azo compound or its salt is suitable for producing a neutral gray polarizing plate for vehicle-mounted or outdoor display used under high temperature and high humidity conditions, and for various sensors that require control of the near-infrared range.

[0050] In order to prepare a neutral gray visible / near infrared polarizing element having high transmittance and high polarization degree, it is preferable to have an azo compound of formula (2) to (11) in addition to the azo compound of formula (1), and the polarizing element using the azo compound has high durability, so that optical devices using the polarizing element, such as liquid crystal displays, can provide high reliability. In order to prepare an achromatic polarizing element, it is preferable that the polarizing element of the present invention contains either one or both of the azo compound of formula (2) or formula (3) or a salt thereof. The formulation can provide an achromatic polarizing element with high transmittance and high polarization degree.

[0051] First, equation (2) will be explained. [ka]

[0052] In formula (2), Ab 11 , Ab 12 each independently represents a naphthyl group having a substituent or a phenyl group having a substituent, at least one of the substituents being a hydrogen atom, a sulfo group, a lower alkyl group, a lower alkoxy group, a lower alkoxy group having a sulfo group, a carboxy group, a nitro group, an amino group, or a substituted amino group; Rb 11 , Rb 12each independently represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a sulfo group, or a lower alkoxy group having a sulfo group.

[0053] Furthermore, in order to obtain a polarizing element having a higher transmittance and a higher polarization degree and a more achromatic hue in the parallel and perpendicular directions, the substituent Rb 11 , Rb 12 are each preferably independently a methyl group or a methoxy group, and more preferably a methoxy group.

[0054] Furthermore, in order to obtain a polarizing element having a higher transmittance and a higher degree of polarization, and having a more achromatic hue in the parallel and perpendicular directions, it is necessary to set Ab 1 , Ab 2 are each preferably independently a naphthyl group having a sulfo group or a carbonyl group, and more preferably a naphthyl group having a sulfo group, in order to obtain a polarizing plate with high contrast.

[0055] The method for obtaining the azo compound represented by formula (2) and the azo compound can be obtained by, for example, the method described in WO 2012 / 165223, but are not limited thereto.

[0056] Specific examples of the azo compound represented by formula (2) used in the present application are shown below in the form of a free acid. [ka]

[0057] In the polarizing element of the present invention, the content of the azo compound represented by formula (2) or a salt thereof is preferably 0.0001 to 5 parts by mass, and more preferably 0.001 to 1 part by mass, relative to 100 parts by mass of the aqueous solution.

[0058] Next, the compound of formula (3) will be described. [ka]

[0059] In formula (3), Ag 1 represents a phenyl group having a substituent or a naphthyl group having a substituent.

[0060] Ag 1 When is a phenyl group, it is preferable that it has at least one sulfo group or carboxy group as a substituent. When the phenyl group has two or more substituents, it is preferable that at least one of the substituents is a sulfo group or a carboxy group, and the other substituents are a sulfo group, a carboxy group, a hydroxy group, a lower alkyl group, a lower alkoxy group, a lower alkoxy group having a sulfo group, a nitro group, an amino group, an acetylamino group, or a lower alkylamino group. The other substituents are more preferably a sulfo group, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a carboxy group, a nitro group, or an amino group, and particularly preferably a sulfo group, a methyl group, a methoxy group, an ethoxy group, or a carboxy group. As the lower alkoxy group having a sulfo group, a straight-chain alkoxy is preferable, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group, more preferably a 3-sulfopropoxy group and a 4-sulfobutoxy group, and particularly preferably a 3-sulfopropoxy group. The number of substituents on the phenyl group is preferably 1 or 2, and the substitution positions are not particularly limited, but are preferably only the 4-position, a combination of the 2- and 4-positions, and a combination of the 3- and 5-positions.

[0061] Ag 1When is a naphthyl group having a substituent, it is preferable that the substituent has at least one sulfo group. When the naphthyl group has two or more substituents, preferably, at least one of the substituents is a sulfo group, and the other substituents are a sulfo group, a hydroxy group, a carboxy group, or a lower alkoxy group having a sulfo group. It is particularly preferable that the naphthyl group has two or more sulfo groups as a substituent. As the lower alkoxy group having a sulfo group, a straight-chain alkoxy is preferable, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. More preferably, it is a 3-sulfopropoxy group and a 4-sulfobutoxy group, and particularly preferably, it is a 3-sulfopropoxy group. When the number of sulfo groups in the naphthyl group is 2, the substitution positions of the sulfo groups are preferably a combination of 4- and 8-positions, and a combination of 6- and 8-positions, and more preferably a combination of 6- and 8-positions. When the number of sulfo groups in the naphthyl group is 3, the substitution positions of the sulfo groups are preferably a combination of 1-, 3-, and 6-positions.

[0062] Bg and Cg in the above formula (3) are each independently represented by the following formula (4) or formula (5), and at least one of Bg and Cg is represented by formula (4). [ka]

[0063] In the above formulas (4) and (5), Rg 1 From Rg 3 Each of Rg independently represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a lower alkoxy group having a sulfo group. 1 is preferably a hydrogen atom, a lower alkyl group, or a lower alkoxy group, more preferably a hydrogen atom, a methyl group, or a methoxy group, and particularly preferably a hydrogen atom or a methoxy group. As the lower alkoxy group having a sulfo group, a straight-chain alkoxy is preferred, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. More preferably, it is a 3-sulfopropoxy group or a 4-sulfobutoxy group, and particularly preferably a 3-sulfopropoxy group. 1 The substitution position of Ag1 When the position of the azo group on the side is the 1st position, the 2nd or 3rd position is preferable, and the 3rd position is more preferable. When a sulfo group is present, the substitution position of the sulfo group is preferably the 6th or 7th position, and the 6th position is more preferable. j represents an integer of 0 to 2, and preferably represents 1. In formula (5), Rg 2 or and Rg 3 are each independently preferably a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a lower alkoxy group having a sulfo group, and more preferably a hydrogen atom, a methyl group, a methoxy group, a 3-sulfopropoxy group, or a 4-sulfopropoxy group. 2 or Rg 3 The substitution position of Xg 1 When the position of the azo group on the side is the 1st position, the combination of only the 2nd position, only the 5th position, the 2nd and 5th positions, the 3rd and 5th positions, the 2nd and 6th positions, or the 3rd and 6th positions can be applied, and preferably only the 2nd position, only the 5th position, or the 2nd and 5th positions.

[0064] Xg in the above formula (3) 1 represents an amino group which may have a substituent, a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, or a benzoylamino group which may have a substituent. 1is preferably an amino group which may have a substituent or a phenylamino group which may have a substituent, more preferably a phenylamino group which may have a substituent. The amino group which may have a substituent is preferably an unsubstituted amino group, an amino group having one or two C1-4 alkyl groups which may have a substituent (hydroxy group, methoxy group, ethoxy group, amino group, carboxy group, sulfo group), more preferably an amino group having one or two hydrogen atoms or methyl groups. The phenylamino group which may have a substituent is preferably a phenylamino group having one or two substituents selected from the group consisting of a hydrogen atom, a lower alkyl group, a lower alkoxy group, a sulfo group, an amino group, and a lower alkylamino group, more preferably a phenylamino group having one or two substituents selected from the group consisting of a hydrogen atom, a methyl group, a methoxy group, a sulfo group, and an amino group. The substitution position is not particularly limited, but it is preferable that one of the substituents is at the p-position with respect to the amino group of the phenylamino group. The phenylazo group which may have a substituent is preferably a phenylazo group having one to three substituents selected from the group consisting of a hydrogen atom, a hydroxy group, a C1-4 alkyl group, a C1-4 alkoxy group, an amino group, a hydroxy group, and a carboxyethylamino group. The benzoylamino group which may have a substituent is preferably a benzoylamino group having one substituent selected from the group consisting of a hydrogen atom, a hydroxy group, an amino group, and a carboxyethylamino group. 1 The substitution position of is preferably the 6th or 7th position, more preferably the 6th position, when the position of the hydroxy group of the substituting naphthyl group is regarded as the 1st position.

[0065] The azo compound represented by formula (3) or a salt thereof is preferably an azo compound represented by the following formula (3b) or a salt thereof, since the performance is particularly improved. [ka]

[0066] In the above formula (3b), Ag 1Rg represents a phenyl group having a substituent or a naphthyl group having a substituent. 4 and Rg 5 Each independently represents Rg in formula (4). 1 and Xg 1 is Xg in formula (3) 1 It has the same meaning as j 1 and j 2 each independently represents an integer of 0 to 2.

[0067] The azo compound represented by formula (3) or a salt thereof can be synthesized by, for example, the methods described in JP-A-1-161202, JP-A-01-172907, JP-A-01-248105, JP-A-01-265205, and JP-B-07-92531, but is not limited thereto.

[0068] Specific examples of the azo compound represented by formula (3) include, for example, CIDirect Blue 34, CIDirect Blue 69, CIDirect Blue 70, CIDirect Blue 71, CIDirect Blue 72, CIDirect Blue 75, CIDirect Blue 78, CIDirect Blue 81, CIDirect Blue 82, CIDirect Blue 83, CIDirect Blue 186, CIDirect Blue 258, Benzo Fast Chrome Blue FG(CI34225), Benzo Fast Blue BN(CI34120), CIDirect Green 51, Examples of the azo compounds include:

[0069] Specific examples of the azo compound represented by formula (3) are shown below in the form of a free acid. [ka] [ka] [ka] [ka]

[0070] In the polarizing element of the present invention, the content of the azo compound represented by formula (3) or a salt thereof is preferably 0.0001 to 5 parts by mass, and more preferably 0.001 to 1 part by mass, relative to 100 parts by mass of the aqueous solution.

[0071] The compound represented by formula (6) will be described.

[0072] In one embodiment, the polarizing element of the present invention can achieve higher transmittance and higher performance by further containing an azo compound represented by formula (6), a metal complex compound thereof, or a salt thereof. [ka]

[0073] In formula (6), Ab 21 represents a phenyl group or a naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group; Rb 21 ~Rb 24 each independently represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a lower alkoxy group having a sulfo group; Rb 25 and Rb 26 each independently represents a hydrogen atom, a hydroxyl group, a lower alkyl group, or a lower alkoxy group; 21represents an unsubstituted amino group, an amino group having one or two C1-4 alkyl groups which may have a substituent (hydroxy group, methoxy group, ethoxy group, amino group, carboxy group, sulfo group), a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a naphthotriazole group which may have a substituent, a benzoylamino group which may have a substituent, or a benzoyl group which may have a substituent. The substituent in the phenylamino group which may have a substituent, the phenylazo group which may have a substituent, the naphthotriazole group which may have a substituent, and the benzoylamino group which may have a substituent is selected from the group consisting of a lower alkyl group, a lower alkoxy group, a sulfo group, an amino group, a lower alkylamino group, a hydroxy group, a carboxy group, and a carboxyethylamino group. d represents 0 or 1. When d is 1, the compound is such that Rb 25 and a metal complex compound based on the hydroxy group of the naphthyl group and a metal atom; Rb 26 represents a hydrogen atom, a lower alkyl group or a lower alkoxy group.

[0074] The metal complex compound is, for example, the following formula (6b), in which M is a metal, such as copper, nickel, or cobalt, and is preferably copper. 21 , Rb 21 ~Rb 24 , Rb 26 , Xb 21 have the same meanings as in the above formula (6). [ka]

[0075] In the above formula (6) and formula (6b), Ab 21When is a phenyl group, it is preferable that it has at least one sulfo group or carboxy group as a substituent. When the phenyl group has two or more substituents, at least one of the substituents is a sulfo group or a carboxy group, and the other substituents are preferably selected from the group consisting of a sulfo group, a carboxy group, a hydroxy group, a lower alkyl group, a lower alkoxy group, a lower alkoxy group having a sulfo group, a hydroxy group, a nitro group, a benzoyl group, an amino group, an acetylamino group, and a lower alkylamino group, more preferably selected from the group consisting of a sulfo group, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a hydroxy group, a carboxy group, a nitro group, an amino group, a 3-sulfopropoxy group, and a 4-sulfobutoxy group, and particularly preferably selected from the group consisting of a sulfo group, a methyl group, a methoxy group, a carboxy group, and a 3-sulfopropoxy group. As the lower alkoxy group having a sulfo group, a linear alkoxy group such as the above-mentioned 3-sulfopropoxy group or 4-sulfobutoxy group is preferable, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. It is preferable that the phenyl group has a sulfo group as a substituent, and the number of sulfo groups is preferably 1 or 2. The substitution position of the substituent is not particularly limited, but when the position of the azo group is the 1st position, the 4th position of the phenyl group is preferable, and when there are two sulfo groups, a combination of the 2nd and 4th positions or a combination of the 3rd and 5th positions of the phenyl group is preferable.

[0076] In the above formula (6) and formula (6b), Ab 21When the naphthyl group has two or more substituents, at least one of the substituents is a sulfo group, and the other substituents are preferably selected from the group consisting of a sulfo group, a hydroxy group, a carboxy group, and a lower alkoxy group having a sulfo group. The lower alkoxy group having a sulfo group is preferably a straight-chain alkoxy group, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. Such a lower alkoxy group having a sulfo group is more preferably a 3-sulfopropoxy group or a 4-sulfobutoxy group, and particularly preferably a 3-sulfopropoxy group. When the naphthyl group has two sulfo groups, the substitution positions of the sulfo groups are preferably a combination of the 4- and 8-positions or a combination of the 6- and 8-positions of the naphthyl group, with the azo group being the 2-position, and more preferably a combination of the 6- and 8-positions. When the number of sulfo groups substituted on the naphthyl group is three, the substitution positions of the sulfo groups are preferably a combination of the 3-, 6-, and 8-positions, with the azo group being the 2-position.

[0077] In the above formula (6) and formula (6b), Rb 21 ~Rb 24 Rb each independently represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a lower alkoxy group having a sulfo group. The lower alkoxy group having a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. 21 ~Rb 24 is preferably a hydrogen atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a 3-sulfopropoxy group, or a 4-sulfobutoxy group, and particularly preferably a sulfo group, a methyl group, a methoxy group, a carboxy group, or a 3-sulfopropoxy group.

[0078] Rb in the above formula (6) 25 and Rb 26 , Rb in formula (6b) 26are preferably each independently a lower alkoxy group, more preferably a methoxy group or an ethoxy group. A methoxy group is even more preferable because it dramatically improves the polarizing performance of the polarizing element or polarizing plate according to the present invention.

[0079] Xb 21 When is an amino group which may have the above-mentioned substituent, the amino group may be unsubstituted, but preferably has one or two C1-4 alkyl groups which may have a substituent (a hydroxy group, a methoxy group, an ethoxy group, an amino group, a carboxy group, a sulfo group), more preferably has one or two C1-4 alkyl groups which may have a substituent (selected from the group consisting of a methoxy group, a sulfo group, and an amino group), such as a methyl group, and further preferably has one or two hydrogen atoms or methyl groups.

[0080] Xb 21 is a phenylamino group which may have the above-mentioned substituents, the phenylamino group is unsubstituted or preferably has one or two substituents selected from the group consisting of a lower alkyl group, a lower alkoxy group, a sulfo group, an amino group, and a lower alkylamino group, and more preferably has one or two substituents selected from the group consisting of a methyl group, a methoxy group, a sulfo group, and an amino group.

[0081] Xb 21 is a phenylazo group which may have the above-mentioned substituents, the phenylazo group is unsubstituted or preferably has 1 to 3 substituents selected from the group consisting of a hydroxy group, a lower alkyl group, a lower alkoxy group, an amino group, and a carboxyethylamino group, and more preferably has 1 to 3 substituents selected from the group consisting of a methyl group, a methoxy group, an amino group, and a hydroxy group.

[0082] Xb 21is a naphthotriazole group which may have the above-mentioned substituent, the naphthotriazole group is unsubstituted or preferably has one or two substituents selected from the group consisting of a sulfo group, an amino group, and a carboxy group, and more preferably has one or two sulfo groups as substituents.

[0083] Xb 21 is a benzoylamino group which may have the above-mentioned substituent, the benzoylamino group is unsubstituted or preferably has one substituent selected from the group consisting of a hydroxy group, an amino group, and a carboxyethylamino group, and more preferably has one or two hydroxy groups or amino groups as substituents.

[0084] Xb 21 is preferably a benzoylamino group or a phenylamino group which may have at least one of the above-mentioned substituents, and most preferably a phenylamino group which may have the above-mentioned substituents. When the benzoylamino group or the phenylamino group has the above-mentioned substituents, the position of the substituent is not particularly limited, but it is preferable that one of the substituents is at the p-position with respect to the amino group of the phenylamino group or the carbonyl group of the benzoylamino group.

[0085] Among the azo compounds represented by the above formula (6), the azo compounds represented by the following formula (6c) are preferred. By using such an azo compound, the polarization performance of the polarizing element can be further improved. In formula (6c), Ab 21 , Rb 21 ~Rb 26 , Xb 21 and d are as defined in the above formula (6). [ka]

[0086] Specific examples of the azo compounds represented by the above formulas (6), (6b), and (6c) include the following azo compounds in the form of free acids, as described in, for example, JP-A-3-12606, JP-A-5-295281, JP-A-10-259311, WO 2007 / 145210, WO 2012 / 108169, and WO 2012 / 108173. [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0087] The azo compounds represented by the above formula (6), formula (6b), and formula (6c) can be produced by, for example, methods described in JP-A-3-12606, JP-A-5-295281, JP-A-10-259311, WO 2007 / 145210, WO 2012 / 108169, and WO 2012 / 108173, but are not limited to these.

[0088] In the above polarizing element, the content of the azo compound represented by formula (6), formula (6b), or formula (6c) or a salt thereof is preferably 0.0001 to 5 parts by mass, and more preferably 0.001 to 1 part by mass, relative to 100 parts by mass of the aqueous solution.

[0089] Next, the azo compound represented by formula (7) will be described. [ka]

[0090] In formula (7), Ab 31 represents a phenyl group or a naphthyl group having at least one substituent selected from the group consisting of a sulfo group, a carboxy group, a nitro group, and an amino group, Rb 31 ~Rb 33 represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group, Xb 31 represents an unsubstituted amino group, an amino group having one or two C1-4 alkyl groups which may have substituents (selected from the group consisting of C1-4 alkoxy groups, C1-4 alkylamino groups, hydroxy groups, carboxy groups, sulfo groups, amino groups, and substituted amino groups), a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a naphthotriazole group which may have a substituent, a benzoylamino group which may have a substituent, or a benzoyl group which may have a substituent, and the substituent in the phenylamino group which may have a substituent, the benzoylamino group which may have a substituent, the phenylazo group which may have a substituent, the naphthotriazole group which may have a substituent, and the benzoyl group which may have at least one substituent is preferably selected from the group consisting of a C1-4 alkyl group, a C1-4 alkoxy group, a C1-4 alkylamino group, a hydroxy group, a carboxy group, a sulfo group, an amino group, and a substituted amino group, e 1 or e 2 each independently represents 0 or 1.

[0091] In formula (7), Ab 31 represents a phenyl group or naphthyl group having at least one substituent selected from the group consisting of a sulfo group, a carboxy group, a nitro group, and an amino group, and when the phenyl group or naphthyl group has two or more substituents, at least one of the substituents is a sulfo group, a carboxy group, a nitro group, or an amino group, preferably a sulfo group or a carboxy group, and the other substituents are preferably selected from the group consisting of a sulfo group, a lower alkyl group, a lower alkoxy group, a lower alkoxy group having a sulfo group, a carboxy group, a nitro group, an amino group, and a substituted amino group, more preferably selected from the group consisting of a sulfo group, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a carboxy group, a nitro group, and an amino group, and particularly preferably selected from the group consisting of a sulfo group, a carboxy group, a lower alkyl group, and a lower alkoxy group. As the lower alkoxy group having a sulfo group, a straight-chain alkoxy group is preferred, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. As such a lower alkoxy group having a sulfo group, a 3-sulfopropoxy group or a 4-sulfobutoxy group is more preferred, and a 3-sulfopropoxy group is particularly preferred. The number of substituents that the phenyl group has is preferably one or two, while the number of substituents that the naphthyl group has is preferably two or three. The positions of these substituents are not particularly limited, but when the phenyl group has one substituent, the 4-position of the phenyl group is preferred, with the azo group being the 1st position, and when the phenyl group has two substituents, a combination of the 2-position and 4-position or a combination of the 3-position and 5-position of the phenyl group is preferred. On the other hand, the naphthyl group preferably has two or three sulfo groups as substituents, and when the naphthyl group has two sulfo groups as substituents, the substitution positions of the sulfo groups are preferably a combination of the 4-position and 8-position or a combination of the 6-position and 8-position, with the azo group being the 2nd position, and a combination of the 6-position and 8-position is more preferred. When the number of sulfo groups substituted on the naphthyl group is three, the substitution positions of the sulfo groups are preferably a combination of the 3-, 6-, and 8-positions with the substitution position of the azo group being the 2-position.

[0092] In the above formula (7), Rb 31 ~Rb 33 Rb represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a lower alkoxy group having a sulfo group. The lower alkoxy group having a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. 31 ~Rb 33 More preferably, Rb is a hydrogen atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a 3-sulfopropoxy group, or a 4-sulfobutoxy group, and particularly preferably a sulfo group, a methyl group, a methoxy group, a carboxy group, or a 3-sulfopropoxy group. 33 is a methoxy group, the polarizing performance of the polarizing element or polarizing plate according to the present invention is dramatically improved, which is preferable.

[0093] In the above formula (7), Xb 31 represents an unsubstituted amino group, an amino group having one or two C1-4 alkyl groups which may have a substituent (selected from the group consisting of a C1-4 alkoxy group, a C1-4 alkylamine group, a hydroxy group, a carboxy group, a sulfo group, an amino group, and a substituted amino group), a phenylamino group which may have at least one substituent selected from the group consisting of a hydrogen atom, a lower alkyl group, a lower alkoxy group, a hydroxy group, a carboxy group, a sulfo group, an amino group, and a substituted amino group, a phenylazo group, a naphthotriazole group, a benzoylamino group, or a benzoyl group.

[0094] Xb 31 When is an amino group which may have the above-mentioned substituent, the amino group may be unsubstituted, but preferably has one or two C1-4 alkyl groups which may have a substituent (selected from the group consisting of a hydroxy group, a C1-4 alkoxy group, a carboxy group, a sulfo group, an amino group, and a lower alkylamino group), more preferably has one or two C1-4 alkyl groups which may have a substituent (selected from the group consisting of a methyl group, a methoxy group, a sulfo group, an amino group, and a lower alkylamino group), and even more preferably has one or two hydrogen atoms or methyl groups.

[0095] Xb 31 is a phenylamino group which may have the above-mentioned substituents, the phenylamino group is unsubstituted or preferably has a substituent selected from the group consisting of a methyl group, a methoxy group, an amino group, a substituted amino group, and a sulfo group, and is preferably unsubstituted or has a methoxy group as a substituent. When the phenylamino group has the above-mentioned substituents, the position of the substituent is not particularly limited, but one of the above-mentioned substituents is preferably at the p-position with respect to the amino group bonded to the phenyl group.

[0096] Xb 31 is a benzoylamino group which may have the above-mentioned substituents, the benzoylamino group is unsubstituted or preferably has a substituent selected from the group consisting of an amino group, a substituted amino group, and a hydroxy group, more preferably has an amino group as a substituent. When the benzoylamino group has the above-mentioned substituents, the position of the substituent is not particularly limited, but one of the substituents is preferably at the p-position with respect to the carbonyl group bonded to the phenyl group.

[0097] Xb 31 is a phenylazo group which may have the above-mentioned substituent, the phenylazo group is unsubstituted or preferably has a substituent selected from the group consisting of a hydroxy group, an amino group, a methyl group, a methoxy group and a carboxy group, and more preferably has a hydroxy group as a substituent.

[0098] Xb 31 When is a naphthotriazole group which may have the above-mentioned substituent, the phenylazo group is unsubstituted or preferably has a sulfo group as a substituent.

[0099] Xb 31is a benzoyl group which may have at least one of the above-mentioned substituents, the benzoyl group is unsubstituted or preferably has one substituent selected from the group consisting of a hydroxy group, an amino group, and a carboxyethylamino group, and more preferably has one or two hydroxy groups or amino groups as substituents.

[0100] Among the azo compounds represented by the above formula (7), an azo compound represented by the following formula (7b) is preferred, and the use of such an azo compound can further improve the polarization performance of the polarizing element. [ka]

[0101] In formula (7b), Ab 31 , Rb 31 ~Rb 33 and Xb 31 , e 1 And e 2 are as defined in the above equation (7).

[0102] The azo compound represented by the above formula (7) or formula (7b) can be produced by known methods such as diazotization, coupling, and copper complexation as described in, for example, JP-B-64-5623 and JP-A-5-53014, but is not limited thereto.

[0103] Specific examples of the azo compound represented by formula (7) include the following azo compounds in the form of free acid. [ka] [ka] [ka] [ka] [ka]

[0104] In the polarizing element, the content of the azo compound represented by formula (7) or formula (7b) or a salt thereof is preferably 0.0001 to 5 parts by mass, and more preferably 0.001 to 1 part by mass, relative to 100 parts by mass of the aqueous solution.

[0105] In one embodiment, the polarizing element of the present invention contains an azo compound represented by the above formula (8) or formula (9), a metal complex compound thereof, or a salt thereof. In order to prepare a polarizing element with high transmittance and high polarization degree, it is also suitable to use an infrared light absorbing compound and an azo compound represented by formula (8) or formula (9) independently or simultaneously. In particular, a polarizing element using an azo compound represented by formula (8) or formula (9) can provide a polarizing element with high polarization degree at 500 to 600 nm, which has high luminosity, and high durability, thereby making it possible to provide a highly reliable liquid crystal display.

[0106] First, equation (8) will be explained below. [ka]

[0107] In formula (8), Ac 1 represents a phenyl group or a naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group; 11 ~Rc 14 each independently represents a hydrogen atom, a C1 to 4 alkyl group, a C1 to 4 alkoxy group, or a C1 to 4 alkoxy group having a sulfo group.

[0108] In the above formula (8), Ac 1When is a phenyl group, it is preferable that it has at least one sulfo group or carboxy group as a substituent. When the phenyl group has two or more substituents, at least one of the substituents is a sulfo group or a carboxy group, and the other substituents are preferably selected from the group consisting of a sulfo group, a carboxy group, a lower alkyl group, a lower alkoxy group, a lower alkoxy group having a sulfo group, a nitro group, an amino group, an acetylamino group, and a lower alkylamino group, more preferably selected from the group consisting of a sulfo group, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a carboxy group, a nitro group, and an amino group, and particularly preferably selected from the group consisting of a sulfo group, a methyl group, a methoxy group, an ethoxy group, and a carboxy group. As the lower alkoxy group having a sulfo group, a linear alkoxy group is preferable, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. As such a lower alkoxy group having a sulfo group, more preferably, a 3-sulfopropoxy group or a 4-sulfobutoxy group, and particularly preferably, a 3-sulfopropoxy group. When the phenyl group has a sulfo group as a substituent, the number of sulfo groups is preferably 1 or 2. The substitution position of the sulfo group is not particularly limited, but when there is one sulfo group, the 4-position of the phenyl group is preferred, with the position of the azo group being the 1-position, and when there are two sulfo groups, a combination of the 2- and 4-positions of the phenyl group or a combination of the 3- and 5-positions of the phenyl group is preferred.

[0109] In the above formula (8), Ac 1When is a naphthyl group, it is preferable that the naphthyl group has at least one sulfo group as a substituent. When the naphthyl group has two or more substituents, at least one of the substituents is a sulfo group, and the other substituents are preferably selected from the group consisting of a hydroxy group, a carboxy group, a sulfo group, and a lower alkoxy group having a sulfo group. As the lower alkoxy group having a sulfo group, a straight-chain alkoxy group is preferable, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. As such a lower alkoxy group having a sulfo group, a 3-sulfopropoxy group or a 4-sulfobutoxy group is more preferable, and a 3-sulfopropoxy group is particularly preferable. When the number of sulfo groups substituted on the naphthyl group is two, the substitution positions of the sulfo group are preferably a combination of the 4- and 8-positions or a combination of the 6- and 8-positions of the naphthyl group, with the position of the azo group being the 2-position, and a combination of the 6- and 8-positions is more preferable. When the number of sulfo groups substituted on the naphthyl group is three, the substitution positions of the sulfo groups are preferably a combination of the 1-, 3- and 6-positions.

[0110] In the above formula (8), Rc 11 ~Rc 14 Rc each independently represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a lower alkoxy group having a sulfo group. The lower alkoxy group having a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. 11 ~Rc 14 are preferably each independently a hydrogen atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a 3-sulfopropoxy group, or a 4-sulfobutoxy group, and particularly preferably a hydrogen atom, a methyl group, a methoxy group, or a 3-sulfopropoxy group. 11 ~Rc 14 The substitution position of the phenyl group where Rc is substituted is preferably only the 2-position, only the 5-position, a combination of the 2-position and the 6-position, a combination of the 2-position and the 5-position, or a combination of the 3-position and the 5-position of the phenyl group, and particularly preferably only the 2-position, only the 5-position, or a combination of the 2-position and the 5-position.11 and Rc 12 , Rc 13 and Rc 14 In relation to Rc 11 and Rc 12 or Rc 13 and Rc 14 has one substituent other than a hydrogen atom only at the 2-position or 5-position, and the other is a hydrogen atom.

[0111] Among the azo compounds represented by the above formula (8), the azo compounds represented by the following formula (8b) are particularly preferred. 1 , Rc 11 ~Rc 14 is as defined in the above formula (8). By using such an azo compound, the polarization performance of the polarizing element can be further improved. [ka]

[0112] The azo compound represented by the above formula (8) or formula (8b) can be produced by known diazotization or ureidation methods, for example, as described in WO2016 / 186194, WO2016 / 186195, and WO2016 / 186196, but is not limited thereto.

[0113] Specific examples of the azo compound represented by formula (8) include the following azo compounds in the form of free acid. [ka] [ka] [ka] [ka]

[0114] Next, equation (9) will be explained. [ka]

[0115] In formula (9), Ac 2 represents a phenyl group or a naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group, Rc 21 ~Rc 27 Rc each independently represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group; 28 represents a hydrogen atom, a C1-4 alkyl group, or a C1-4 alkoxy group having a sulfo group, Xc 2 represents an unsubstituted amino group, an amino group having one or two C1-4 alkyl groups which may have a substituent (selected from the group consisting of C1-4 alkoxy groups, sulfo groups, C1-4 alkylamino groups, hydroxy groups, amino groups, substituted amino groups, carboxy groups, and carboxyethylamino groups), a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a naphthotriazole group which may have a substituent, or a benzoylamino group which may have a substituent, wherein the substituent in the phenylamino group which may have a substituent, the phenylazo group which may have a substituent, the naphthotriazole group which may have a substituent, and the benzoylamino group which may have a substituent is selected from the group consisting of a C1-4 alkyl group, a C1-4 alkoxy group, a sulfo group, a C1-4 alkylamino group, a hydroxy group, an amino group, a substituted amino group, a carboxy group, and a carboxyethylamino group; r, p, and q each independently represent 0 or 1, except for the case where r, p, and q are all 1.

[0116] In the above formula (9), Ac 2 represents a phenyl group having a substituent or a naphthyl group having a substituent, 2When is a phenyl group having a substituent, the phenyl group preferably has at least one sulfo group or carboxy group as a substituent, and when the phenyl group has two or more substituents, at least one of the substituents is a sulfo group or carboxy group, and the other substituents are preferably a sulfo group, a carboxy group, a C1-4 alkyl group, a C1-4 alkoxy group, a C1-4 alkoxy group having a sulfo group, a hydroxy group, a nitro group, an amino group, or a substituted amino group (particularly, an acetylamino group or a C1-4 alkylamino group), and the other substituents are more preferably a sulfo group, a carboxy group, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a hydroxy group, a nitro group, or an amino group, and particularly preferably a sulfo group, a carboxy group, a methyl group, a methoxy group, or an ethoxy group. In addition, the C1-4 alkoxy group having a sulfo group is preferably a straight-chain alkoxy group, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. The C1-4 alkoxy group having a sulfo group is more preferably a 3-sulfopropoxy group or a 4-sulfobutoxy group, and particularly preferably a 3-sulfopropoxy group. The number of substituents on the phenyl group is preferably 1 or 2, and the positions of the substituents on the phenyl group are not particularly limited, but are preferably only the 4-position, or a combination of the 2-position and the 4-position, or a combination of the 3-position and the 5-position.

[0117] In the above formula (9), Ac 2When is a naphthyl group having a substituent, it is preferable that the naphthyl group has at least one sulfo group as a substituent, and when the naphthyl group has two or more substituents, it is preferable that at least one of the substituents is a sulfo group, and the other substituents are a sulfo group, a hydroxy group, a carboxy group, or a C1-4 alkoxy group having a sulfo group. In addition, the C1-4 alkoxy group having a sulfo group is preferably a straight-chain alkoxy group, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. As the C1-4 alkoxy group having a sulfo group, a 3-sulfopropoxy group or a 4-sulfobutoxy group is more preferable, and a 3-sulfopropoxy group is particularly preferable. When the number of sulfo groups on the naphthyl group is two, the substitution positions of the sulfo group are preferably a combination of the 4-position and the 8-position or a combination of the 6-position and the 8-position, and a combination of the 6-position and the 8-position is particularly preferable, with the substitution position of the azo group being the 2-position. When the number of sulfo groups on the naphthyl group is 3, the substitution positions of the sulfo groups are particularly preferably a combination of the 1-position, the 3-position and the 6-position, with the substitution position of the azo group being the 2-position.

[0118] In the above formula (9), Xc 2 represents an amino group which may have at least one substituent, a phenylamino group which may have at least one substituent, a phenylazo group which may have at least one substituent, a naphthotriazole group which may have at least one substituent, a benzoyl group which may have at least one substituent, or a benzoylamino group which may have at least one substituent, and preferably includes a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a naphthotriazole group which may have a substituent, a benzoyl group which may have a substituent, or a benzoylamino group which may have a substituent, and particularly preferably Xc 2Examples of the amino group which may have at least one substituent include a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, and a benzoylamino group which may have a substituent. Examples of the amino group which may have at least one substituent include an unsubstituted amino group and an amino group which has one or two C1-4 alkyl groups which may have a substituent (hydroxy group, methoxy group, ethoxy group, amino group, carboxy group, sulfo group). The substituent in the phenylamino group which may have at least one substituent, the phenylazo group which may have at least one substituent, the naphthotriazole group which may have at least one substituent, the benzoyl group which may have at least one substituent, or the benzoylamino group which may have at least one substituent is selected from the group consisting of a lower alkyl group, a lower alkoxy group, a sulfo group, a lower alkylamino group, a hydroxy group, an amino group, a substituted amino group, a carboxy group, and a carboxyethylamino group.

[0119] Xc 2 is an amino group which may have at least one substituent, the amino group may be unsubstituted, but preferably has one or two C1-4 alkyl groups which may have a substituent (a hydroxy group, a methoxy group, an ethoxy group, an amino group, a carboxy group, a sulfo group), more preferably has one or two C1-4 alkyl groups which may have a substituent selected from the group consisting of a methoxy group, a sulfo group, and an amino group, and even more preferably has one or two hydrogen atoms or methyl groups.

[0120] Xc 2 is a phenylamino group which may have at least one substituent, the phenylamino group is unsubstituted or preferably has one or two substituents selected from the group consisting of a lower alkyl group, a lower alkoxy group, a sulfo group, an amino group, and a lower alkylamino group, and more preferably has one or two substituents selected from the group consisting of a methyl group, a methoxy group, a sulfo group, and an amino group.

[0121] Xc 2When it is a phenylazo group which may have at least one substituent, the phenylazo group is unsubstituted or, preferably, has 1 to 3 substituents selected from the group consisting of a hydroxy group, a lower alkyl group, a lower alkoxy group, an amino group and a carboxyethylamino group, and more preferably has 1 to 3 substituents selected from the group consisting of a methyl group, a methoxy group, a carboxyethylamino group, an amino group and a hydroxy group.

[0122] Xc 2 When it is a naphthotriazole group which may have at least one substituent, the naphthotriazole group is unsubstituted or, preferably, has one or two substituents selected from the group consisting of a sulfo group, an amino group and a carboxy group, and more preferably has one or two sulfo groups as substituents.

[0123] Xc 2 When it is a benzoylamino group which may have at least one substituent, the benzoylamino group is unsubstituted or, preferably, has one substituent selected from the group consisting of a hydroxy group, an amino group and a carboxyethylamino group, and more preferably has one or two hydroxy groups or amino groups as substituents.

[0124] Xc 2 When it is a benzoyl group which may have at least one substituent, the benzoyl group is unsubstituted or, preferably, has one substituent selected from the group consisting of a hydroxy group, an amino group and a carboxyethylamino group, and more preferably has one or two hydroxy groups or amino groups as substituents.

[0125] In the above formula (9), Rc 21 ~Rc 27 each independently represents a hydrogen atom, a lower alkyl group, a lower alkoxy group or a lower alkoxy group having a sulfo group. Rc 21 ~Rc 27are each independently preferably a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a straight-chain alkoxy group having a sulfo group at the terminal, more preferably a hydrogen atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a 3-sulfopropoxy group, or a 4-sulfobutoxy group, and particularly preferably a hydrogen atom, a methyl group, a methoxy group, or a 3-sulfopropoxy group.

[0126] In the above formula (9), Rc 28 represents a hydrogen atom, a lower alkyl group, or a lower alkoxy group having a sulfo group, and is preferably a hydrogen atom, a C1-4 alkyl group, or a straight-chain alkoxy group having a terminal sulfo group, more preferably a hydrogen atom, a methyl group, an ethyl group, a 3-sulfopropoxy group, or a 4-sulfobutoxy group, and particularly preferably a hydrogen atom, a methyl group, or a 3-sulfopropoxy group.

[0127] In the above formula (9), r, p, and q are each independently 0 or 1, except when r, p, and q are all 1. In order to obtain good polarization performance in the polarizing element of the present invention, when either one of p and q is 0, it is preferable that the other is 1, and it is more preferable that p and q are 1. In addition, in order to obtain even better polarization properties, it is preferable that r is 1 and either one or both of p and q are 0. When r, p, and q are all 1, the inclusion property in the substrate, for example the dyeability to a polyvinyl alcohol film, is reduced, which is inappropriate.

[0128] Among the azo compounds represented by the above formula (9), the azo compounds represented by the following formula (9b) are preferred. By using such an azo compound, the polarization performance of the polarizing element can be further improved. In formula (9b), Ac 2 , Rc 21 ~Rc 28 , Xc 2 , r, p, and q are as defined in formula (9) above. [ka]

[0129] Next, specific examples of azo compounds whose free acid form is represented by formula (9) or (9b) are given below. In the following compound examples, the sulfo group and hydroxy group are represented in the form of free acid, but the sulfo group and hydroxy group may be in the form of a salt. [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0130] Examples of methods for synthesizing azo compounds whose free acid forms are represented by formula (9) and formula (9b) include, but are not limited to, methods described in JP-A-9-302250, JP-A-3-12606, WO 2005 / 075572, WO 2012 / 108169, and WO 2012 / 108173.

[0131] Examples of azo compounds whose free acid form is represented by formula (9) and formula (9b) include CI Direct Red 117, CI Direct Red 127, the azo compounds described in JP-A-03-12606, the azo compounds described in WO 2005 / 075572, and the azo compounds described in WO 2012 / 108169.

[0132] In one embodiment, the polarizing element of the present invention preferably contains at least one azo compound represented by the following formula (10) or formula (11) or a salt thereof together with the azo compound represented by formula (1) in order to further improve the polarization performance. The azo compound represented by formula (10) or formula (11) affects the transmittance of 400 to 500 nm. In the polarizing element, the transmittance and the degree of polarization (dichroism) on the short wavelength side of 400 to 500 nm in particular affect blue bleeding during black display and yellowing of white during white display. The azo compound represented by formula (10) can improve the polarization characteristics (dichroism) of 400 to 500 nm while suppressing the decrease in the transmittance on the short wavelength side in the parallel position of the polarizing element, and can further reduce the yellowishness during white display and the blue bleeding during black display. By further containing the azo compound represented by formula (10), the polarizing element shows more achromaticity by itself, particularly in the range of 30 to 65% of the single transmittance after luminosity correction, and expresses a higher quality paper-like white color during white display. Furthermore, when the single transmittance after luminosity correction is particularly from 35 to 45%, the degree of polarization or contrast is improved, which is preferable.

[0133] Next, equation (10) will be explained. [ka]

[0134] In the above formula (10), Ay 11 Ry is a sulfo group, a carboxy group, a hydroxy group, a lower alkyl group, or a lower alkoxy group, and is preferably a sulfo group or a carboxy group. 11 ~Ry 14 are each independently a hydrogen atom, a sulfo group, a lower alkyl group, a lower alkoxy group, or a lower alkoxy group having a sulfo group, preferably a hydrogen atom, a sulfo group, a lower alkyl group, or a lower alkoxy group, more preferably a hydrogen atom, a methyl group, or a methoxy group. f represents an integer of 1 to 3.

[0135] In the polarizing element, the content of the azo compound represented by formula (10) or a salt thereof is preferably 0.01 to 1000 parts by mass, more preferably 0.1 to 300 parts by mass, and even more preferably 0.2 to 200 parts by mass, relative to 100 parts by mass of the azo compound represented by formula (1).

[0136] Specific examples of the azo compound represented by formula (10) include, for example, CI Direct Yellow 4, CI Direct Yellow 12, CI Direct Yellow 72, and CI Direct Orange 39, as well as azo compounds having a stilbene structure described in WO 2007 / 138980, but are not limited thereto.

[0137] The azo compound represented by formula (10) or a salt thereof can be synthesized by the method described in, for example, WO 2007 / 138980, but is also commercially available.

[0138] Further specific examples of the azo compound represented by formula (10) are given below. The compound examples are shown in the form of a free acid. [ka]

[0139] Next, equation (11) will be explained. [ka]

[0140] In formula (11), Ay 21 and Ay 22 each independently represents a naphthyl group which may have a substituent or a phenyl group which may have a substituent; R 21 , Ry 22 , Ry 27 , Ry 28 are each independently a hydrogen atom, a C1-4 alkyl group, or a C1-4 alkoxy group; Ry 23 ~Ry 26 each independently represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group; and each of s and t independently represents 0 or 1.

[0141] In formula (11), Ay 21 and Ay 22 each independently represents a naphthyl group which may have a substituent selected from the group consisting of a hydroxy group, a sulfo group, and a C1-4 alkoxy group having a sulfo group, or a phenyl group which may have a substituent; s and t each independently represent 0 or 1; Ry 21 , Ry 22 , Ry 27 , Ry 28 are each independently a hydrogen atom, a C1-4 alkyl group, or a C1-4 alkoxy group; Ry 23 ~Ry 26 each independently represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group. In s and t, either s or t is preferably 1 since the polarization properties are improved.

[0142] The phenyl group having a substituent is preferably a phenyl group having one or more substituents selected from the group consisting of a carboxy group, a sulfo group, a lower alkoxy group having a sulfo group, a lower alkoxy group, a lower alkyl group, a halogen group, a nitro group, an amino group, a lower alkyl-substituted amino group, and a lower acylamino group. When the phenyl group has two or more substituents, it is preferable that at least one of the substituents is a carboxy group, a sulfo group, or a lower alkoxy group having a sulfo group, and the other substituents are a sulfo group, a hydrogen atom, a lower alkyl group, a lower alkoxy group, a lower alkoxy group having a sulfo group, a carboxy group, a chloro group, a bromo group, a nitro group, an amino group, a lower alkyl-substituted amino group, or a lower acylamino group. The other substituents are more preferably sulfo, hydrogen, methyl, ethyl, methoxy, ethoxy, carboxy, sulfoethoxy, sulfopropoxy, sulfobutoxy, chloro, nitro, or amino, and particularly preferably sulfo, carboxy, hydrogen, methyl, methoxy, sulfoethoxy, sulfopropoxy, or sulfobutoxy. The substitution position is not particularly limited, but is preferably only at the 2-position, only at the 4-position, a combination of the 2-position and the 6-position, a combination of the 2-position and the 4-position, or a combination of the 3-position and the 5-position, and particularly preferably only at the 2-position, only at the 4-position, a combination of the 2-position and the 4-position, or a combination of the 3-position and the 5-position. Note that only at the 2-position and only at the 4-position indicate that only at the 2-position or only at the 4-position there is one substituent other than a hydrogen atom.

[0143] The phenyl group having a substituent is preferably represented by the following formula (17). [ka]

[0144] In formula (17), Ry 2a and Ry 2bAt least one of Ry is a sulfo group, a carboxy group, or a lower alkoxy group having a sulfo group, and the other is a hydrogen atom, a sulfo group, a carboxy group, a lower alkoxy group having a sulfo group, a lower alkyl group, a lower alkoxy group, a halogen group, a nitro group, an amino group, a lower alkyl-substituted amino group, or a lower alkyl-substituted acylamino group. 2a and Ry 2b One of these is a sulfo group or a carboxy group, and the other is a hydrogen atom, a sulfo group, a carboxy group, a methyl group, or a methoxy group.

[0145] The naphthyl group which may have a substituent is preferably a naphthyl group which may have one or more substituents selected from the group consisting of a hydroxy group, a lower alkoxy group having a sulfo group, and a sulfo group.

[0146] The naphthyl group which may have a substituent is preferably a naphthyl group represented by the following formula (18). [ka]

[0147] In formula (18), Ry 2c is a hydrogen atom, a hydroxyl group, a lower alkoxy group having a sulfo group, or a sulfo group. h is an integer of 1 to 3. The position of the sulfo group may be on any benzene nucleus of the naphthalene ring. 2c is a hydrogen atom, and h is 2. As the lower alkoxy group having a sulfo group, a straight-chain alkoxy group is preferable, and the substitution position of the sulfo group is preferably the terminal end of the alkoxy group. As the lower alkoxy group having a sulfo group, a 3-sulfopropoxy group and a 4-sulfobutoxy group are more preferable. The positions of the substituents of the naphthyl group are not particularly limited, but in terms of the numbers shown in formula (18), when there are two substituents, a combination of the 5-position and the 7-position, or the 6-position and the 8-position is preferable, and when there are three substituents, the 3-position, the 5-position and the 7-position, or the 3-position, the 6-position and the 8-position are preferable.

[0148] Ry 21 , Ry22 , Ry 27 , Ry 28 are each independently a hydrogen atom, a lower alkoxy group, or a lower alkyl group, and preferably a hydrogen atom, a methyl group, an ethyl group, a methoxy group, or an ethoxy group.

[0149] Ry 23 ~Ry 26 are each independently a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a lower alkoxy group having a sulfo group, 23 ~Ry 26 are each independently preferably a hydrogen atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a 3-sulfopropoxy group, or a 4-sulfobutoxy group, and more preferably a hydrogen atom, a methyl group, an ethyl group, a methoxy group, or a 3-sulfopropoxy group. 3 ~Ry 6 The positions of are preferably only the 2-position, only the 5-position, a combination of the 2-position and the 6-position, a combination of the 2-position and the 5-position, or a combination of the 3-position and the 5-position, and more preferably only the 2-position, only the 5-position, or a combination of the 2-position and the 5-position. Note that only the 2-position and only the 5-position indicate that only the 2-position or the 5-position has one substituent other than a hydrogen atom.

[0150] The azo compound represented by formula (11) is preferably represented by the following formula (11b). [ka]

[0151] The azo compound represented by the above formula (11) or formula (11b) or a salt thereof can be produced by carrying out diazotization and coupling in accordance with a method for producing a normal azo dye as described in Non-Patent Document 2, and reacting the resulting compound with a ureidation agent as described in Patent Document 8.

[0152] Next, specific examples of the azo compound represented by formula (11) or formula (11b) are given below. In the formula, the sulfo group, carboxy group and hydroxy group are represented in the free acid form.

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[0153] The above formulas (1) to (11) may be free acids, or may be salts of metal ions or ammonium ions. Examples of metal ions include alkali metal ions such as lithium ion, sodium ion, and potassium ion, and alkaline earth metal ions such as calcium ion and magnesium ion. Examples of ammonium ions include ammonium ion, methylammonium ion, dimethylammonium ion, triethylammonium ion, tetraethylammonium ion, tetra-n-propylammonium ion, tetra-n-butylammonium ion, and triethanolammonium ion. More specifically, in the case of free acids, sulfonic acid (-SO 3 H) for sodium ions, and sodium sulfonate (-SO 3 Na) for ammonium ion, and ammonium sulfonate (-SO 3 NH 4 )

[0154] The polarizing element of the present invention contains an azo compound represented by formula (1) or a salt thereof, and further contains at least one azo compound selected from the azo compounds represented by formulas (2) to (11) or salts thereof, and usually contains a substrate.

[0155] The substrate is usually a polymer film, preferably a film obtained by forming a hydrophilic polymer into a film, more preferably a film made of polyvinyl alcohol resin or its derivative. The hydrophilic polymer that can be used for the substrate is not particularly limited, but a film having a high affinity with water is preferable. For example, a film that contains water or swells when immersed in or contacted with water as a medium is preferable. Specifically, polyvinyl alcohol resin, amylose resin, starch resin, cellulose resin, polyacrylate resin, and derivatives thereof can be used. A dichroic dye having absorption in the infrared wavelength range is added to a film made of such a resin (the film is dyed with the dye), and the film is stretched to obtain an orientation plate. Considering the inclusion of an azo compound of formula (1) to formula (11) and orientation, a film made of polyvinyl alcohol resin is most preferable.

[0156] When the substrate is a polymer film, the azo compound of formula (1) to formula (11) or a salt thereof can be incorporated by dyeing the polymer film with the azo compound or dyeing the raw material before forming the raw film with the azo compound, but usually, a method of dyeing the polymer film can be adopted. For example, the azo compound of formula (1) to formula (11) or a salt thereof, and other organic dyes as necessary, are dissolved in water to prepare a dye bath. The dye concentration in the dye bath is not particularly limited, but is usually selected and adjusted from a range of about 0.001 to 10 mass%. If necessary, a dyeing assistant may be used, and for example, it is preferable to use mirabilite at a concentration of about 0.1 to 10 mass%. The dye bath thus prepared is adjusted to, for example, 30 to 90°C, and the polymer film is immersed in the dye bath for, for example, 1 to 10 minutes to perform dyeing.

[0157] A polarizing element can be obtained by incorporating the azo compounds of formulas (1) to (11) or salts thereof into a substrate and then orienting the substrate by stretching or the like to orient the azo compounds of formulas (1) to (11) or salts thereof contained in the substrate. A specific method for producing a polarizing element will be described below using a polyvinyl alcohol-based resin film as an example of the substrate.

[0158] [Method of manufacturing polarizing element] The polarizing element is manufactured, for example, by carrying out the following steps in order: production of a polyvinyl alcohol resin, preparation of a raw film, swelling treatment, dyeing treatment, first washing treatment, treatment for incorporating a crosslinking agent and / or a water-resistant agent, stretching treatment, second washing treatment, and drying treatment. Note that some of these treatments can be omitted.

[0159] (Production of polyvinyl alcohol resin) The method for producing the polyvinyl alcohol resin is not particularly limited, and a known method can be adopted. The polyvinyl alcohol resin can be obtained, for example, by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, and preferably 95 mol% or more. The polyvinyl alcohol resin may be further modified, and examples of the modified resin include polyvinyl alcohol or its derivatives, and olefins such as ethylene and propylene, and unsaturated carboxylic acids such as crotonic acid, acrylic acid, methacrylic acid, and maleic acid. Polyvinyl formal and polyvinyl acetal modified with aldehydes can also be used. The degree of polymerization of the polyvinyl alcohol resin means the viscosity average degree of polymerization, and can be determined by a method well known in the art. The degree of polymerization is usually about 1,000 to 10,000, and preferably about 1,500 to 6,000.

[0160] (Preparation of original film) Next, the polyvinyl alcohol resin is formed into a film to prepare a raw film. The method for forming the polyvinyl alcohol resin into a film is not particularly limited, and a known method can be adopted. The raw film may contain glycerin, ethylene glycol, propylene glycol, low molecular weight polyethylene glycol, etc. as a plasticizer. The content of the plasticizer in the raw film is 5 to 20 mass %, preferably 8 to 15 mass %. The thickness of the raw film is not particularly limited, but is preferably about 5 to 150 μm, more preferably about 10 to 100 μm.

[0161] (Swelling treatment) The raw film obtained as above is then subjected to a swelling treatment. The swelling treatment is carried out by immersing the raw film in a solution at 20 to 50°C for 30 seconds to 10 minutes. The solution is preferably an aqueous solution. The stretching ratio in the swelling treatment is preferably adjusted to 1.00 to 1.50 times, more preferably 1.10 to 1.35 times. Since the film also swells in the dyeing treatment described below, this swelling treatment may be omitted when the time required to produce a polarizing element is to be shortened.

[0162] (Dyeing process) After the swelling treatment, a dyeing treatment is carried out. The dyeing treatment is a treatment for dyeing the azo compounds represented by formulas (1) to (11). The dyeing treatment is carried out using the azo compound represented by formula (1) that absorbs light at least in the infrared region, and the azo compounds represented by formulas (2) to (11) that function as dichroic dyes in the visible region. The dyeing is carried out, for example, by immersing the film after the swelling treatment in a dyeing solution containing the above compounds.

[0163] The polarizing element of the present invention may contain a known azo compound other than those of formulas (1) to (11) for the purpose of color correction, to the extent that the performance of the present invention is not impaired. As the azo compound other than those of formulas (1) to (11) to be contained, a compound having a high dichroic property is particularly preferable. For example, azo compounds as shown in Non-Patent Document 2, CIDirect Yellow 12, CIDirect Yellow 28, CIDirect Yellow 44, CIDirect Orange 26, CIDirect Orange 39, CIDirect Orange 107, CIDirect Red 2, CIDirect Red 31, CIDirect Red 79, CIDirect Red 247, CIDirect Green 80, CIDirect Green 59, and azo compounds described in JP-A-2001-33627, JP-A-2002-296417, and JP-A-60-156759 can be mentioned. Such azo compounds other than those of formulas (1) to (11) can be used in a polarizing element together with at least one selected from the azo compound represented by formula (1) or its salt and the azo compounds represented by formulas (2) to (11). The azo compounds other than those of formulas (1) to (11) can be used as free acids, as well as alkali metal salts (e.g., sodium salts, potassium salts, lithium salts), ammonium salts, salts of amines, or copper complex compounds or their salts. The azo compounds other than those of formulas (1) to (11) can be used not only as one type, but also as a mixture of two or more types.

[0164] The solution temperature in the dyeing process can be 5 to 60°C, preferably 20 to 55°C, and more preferably 25 to 50°C. The time for immersion in the solution can be adjusted appropriately, but is preferably 30 seconds to 20 minutes, and more preferably 1 to 10 minutes. The dyeing solution is preferably an aqueous solution. The dyeing method is preferably a method in which the film after the swelling treatment is immersed in the dyeing solution, but a method in which the dyeing solution is applied to the film after the swelling treatment can also be adopted. The dyeing solution may contain sodium carbonate, sodium bicarbonate, sodium chloride, sodium sulfate, anhydrous sodium sulfate, sodium tripolyphosphate, etc. as a dyeing assistant. The content of the dyeing assistant can be arbitrarily adjusted depending on the time and temperature depending on the dyeability of the dichroic dye, but is preferably 0 to 5 mass%, and more preferably 0.1 to 2 mass%. When dyeing using multiple dyes, the order of the dyeing treatment is not particularly limited, and may be performed simultaneously, or each dye may be impregnated into the substrate in any order. When an azo compound represented by formula (1) or a salt thereof and at least one selected from the azo compounds represented by formulae (2) to (11) are used together, it is preferable to dye them simultaneously.

[0165] (First cleaning process) After the dyeing process, a washing process (hereinafter referred to as "first washing process") can be performed before the next process. The first washing process is a process for washing the dyeing solution attached to the film surface in the dyeing process. By performing the first washing process, it is possible to prevent the dye from being mixed into the solution used in the next process. In the first washing process, water is generally used as the washing liquid. As a washing method, a method in which the film after the dyeing process is immersed in a washing liquid is preferable, but a method in which the washing liquid is applied to the film after the dyeing process can also be adopted. The washing time is not particularly limited, but is preferably 1 to 300 seconds, more preferably 1 to 60 seconds. The temperature of the washing liquid in the first washing process needs to be a temperature at which the film after the dyeing process does not dissolve. Washing is generally performed at 5 to 40°C. However, since there is no problem in performance even if the first washing process is not performed, this first washing process may be omitted.

[0166] (Treatment for adding a crosslinking agent and / or a water-resistant agent) After the first cleaning treatment, a treatment to add a crosslinking agent and / or a water-resistant agent can be performed. Examples of crosslinking agents include boron compounds such as boric acid, borax, or ammonium borate, polyaldehydes such as glyoxal or glutaraldehyde, polyisocyanate compounds such as biuret type, isocyanurate type, or block type, and titanium compounds such as titanium oxysulfate. Other examples include ethylene glycol glycidyl ether and polyamide epichlorohydrin. Examples of water-resistant agents include succinic peroxide, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, ammonium chloride, or magnesium chloride. Among these, boric acid is the most preferable. Only one type of crosslinking agent or water-resistant agent may be used, or a combination of two or more types may be used.

[0167] Although a method of immersing the film after the first washing treatment in a solution containing a crosslinking agent and / or a water-resistant agent is preferred, a method of applying a solution containing a crosslinking agent and / or a water-resistant agent to the film after the first washing treatment can also be adopted. The solution is preferably an aqueous solution. The content of the crosslinking agent and / or water-resistant agent in the solution is preferably 0.1 to 6.0 mass %, more preferably 1.0 to 4.0 mass %, taking boric acid as an example. The temperature of the solution is preferably 5 to 70°C, more preferably 5 to 50°C. The treatment time is preferably 30 seconds to 6 minutes, more preferably 1 to 5 minutes. However, it is not essential to include a crosslinking agent and / or a water-resistant agent, and when it is desired to shorten the time or when crosslinking treatment or water-resistant treatment is not necessary, this treatment may be omitted.

[0168] (Stretching process) After the treatment of incorporating a crosslinking agent and / or a water-resistant agent, a stretching treatment is carried out. The stretching treatment is a treatment of uniaxially stretching the film. The stretching method may be either a wet stretching method or a dry stretching method. The stretching ratio is preferably 3 times or more, and more preferably 5 to 7 times.

[0169] In the case of the wet stretching method, the film is stretched in water, a water-soluble organic solvent, or a mixed solution thereof. It is preferable to perform the stretching treatment while immersing the film after the first washing treatment in a solution containing a crosslinking agent and / or a water-resistant agent. Examples of the crosslinking agent and water-resistant agent include those mentioned above. The content of the crosslinking agent and / or water-resistant agent in the solution is preferably 0.5 to 15 mass %, more preferably 2.0 to 8.0 mass %, taking boric acid as an example. The stretching ratio is preferably 2 to 8 times, more preferably 5 to 7 times. The temperature of the solution is preferably 40 to 60°C, more preferably 45 to 58°C. The stretching time is usually 30 seconds to 20 minutes, more preferably 2 to 5 minutes. The film can be stretched in one stage, but can also be stretched in multiple stages of two or more stages.

[0170] In the case of the dry stretching method, when the stretching heating medium is air, the temperature of the air medium is preferably room temperature to 180°C. In addition, it is preferable to treat in an atmosphere with a humidity of 20 to 95% RH. Examples of the heating method include a zone stretching method between rolls, a roll heating stretching method, a rolling stretching method, and an infrared heating stretching method, but the stretching method is not limited. The film can be stretched in one stage, but can also be stretched in two or more stages.

[0171] (Second cleaning process) After the stretching treatment, a crosslinking agent and / or a water-resistant agent may precipitate on the film surface, or foreign matter may adhere to the film surface, so a washing treatment (hereinafter referred to as "second washing treatment") may be performed to wash the film surface. The washing method is preferably a method in which the stretched film is immersed in a washing liquid, but a method in which a washing liquid is applied to the stretched film may also be adopted. The washing treatment may be performed in one step, or in multiple steps of two or more steps. The washing time is preferably 1 second to 5 minutes. The temperature of the washing liquid is not particularly limited, but is usually 5 to 50°C, preferably 10 to 40°C.

[0172] Examples of the solvents used in the above treatments include, but are not limited to, alcohols such as water, dimethyl sulfoxide, N-methylpyrrolidone, methanol, ethanol, propanol, isopropyl alcohol, glycerin, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. Mixtures of one or more of these solvents can also be used. The most preferred solvent is water.

[0173] (Drying process) After the second washing treatment, a drying treatment is carried out to dry the film. The drying treatment can be carried out by natural drying. To further increase the drying efficiency, the film may be compressed using a roll, or the surface moisture may be removed using an air knife or a water absorbing roll, or air may be blown to dry the film. The drying temperature is preferably 20 to 100°C, and more preferably 60 to 100°C. The drying time is preferably 30 seconds to 20 minutes, and more preferably 5 to 10 minutes.

[0174] By the above method, the polarizing element of the present invention containing at least the azo compound represented by formula (1) or a salt thereof, and the azo compound selected from formulas (2) to (11) or a salt thereof can be obtained.

[0175] In one embodiment, the polarizing element of the present invention contains at least an azo compound represented by formula (1) or a salt thereof, and an azo compound or a salt thereof selected from formulas (2), (3), (6), and (7), thereby making it possible to obtain a polarizing element having high transmittance and a high degree of polarization in the visible and near infrared regions. By using an azo compound or a salt thereof selected from formulas (2), (3), (6), and (7), it is possible to obtain a polarizing element that exhibits a high degree of polarization not only in the near infrared region, but particularly in the region from 550 to 780 nm.

[0176] In one embodiment, the polarizing element of the present invention contains at least an azo compound represented by formula (1) or a salt thereof, and an azo compound selected from formula (8) or (9) or a salt thereof, thereby making it possible to obtain a polarizing element having high transmittance and a high degree of polarization in the visible and near infrared regions. By using an azo compound selected from formula (8) or (9) or a salt thereof, it is possible to obtain a polarizing element that exhibits a high degree of polarization not only in the near infrared region, but particularly in the region of 500 to 650 nm.

[0177] In one embodiment, the polarizing element of the present invention contains at least an azo compound represented by formula (1) or a salt thereof, and an azo compound selected from formulas (10) and (11) or a salt thereof, thereby making it possible to obtain a polarizing element having high transmittance and a high degree of polarization in the visible and near infrared regions. By using an azo compound selected from formulas (10) and (11) or a salt thereof, it is possible to obtain a polarizing element that exhibits a high degree of polarization not only in the near infrared region, but particularly in the region of 400 to 500 nm.

[0178] In one embodiment, the polarizing element of the present invention contains at least an azo compound represented by formula (1) or a salt thereof, an azo compound selected from formulas (2), (3), (6), and (7) or a salt thereof, and an azo compound selected from formulas (8) and (9) or a salt thereof, thereby obtaining a polarizing element having high transmittance and high polarization degree in the visible and near infrared regions. By using an azo compound selected from formulas (2), (3), (6), and (7) or a salt thereof, and an azo compound selected from formulas (8) and (9) or a salt thereof, a polarizing element showing a high polarization degree not only in the near infrared region but also particularly in the region of 500 to 780 nm can be obtained.

[0179] In one embodiment, the polarizing element of the present invention contains at least an azo compound or a salt thereof represented by formula (1), an azo compound or a salt thereof selected from formulas (2), (3), (6), and (7), and an azo compound or a salt thereof selected from formulas (10) and (11), thereby obtaining a polarizing element having high transmittance and high polarization degree in the visible and near infrared regions. By using an azo compound or a salt thereof selected from formulas (2), (3), (6), and (7), and an azo compound or a salt thereof selected from formulas (10) and (11), a polarizing element showing a high polarization degree not only in the near infrared region but also particularly in the region of 400 to 780 nm can be obtained.

[0180] In one embodiment, the polarizing element of the present invention contains at least an azo compound represented by formula (1) or a salt thereof, an azo compound selected from formulas (8) and (9) or a salt thereof, and an azo compound selected from formulas (10) and (11) or a salt thereof, thereby obtaining a polarizing element having high transmittance and a high degree of polarization in the visible and near infrared regions. By using an azo compound selected from formulas (8) and (9) or a salt thereof, and an azo compound selected from formulas (10) and (11) or a salt thereof, a polarizing element that exhibits a high degree of polarization not only in the near infrared region but also particularly in the region of 400 to 650 nm can be obtained.

[0181] In one embodiment, the polarizing element of the present invention comprises: An azo compound represented by formula (1) or a salt thereof, An azo compound selected from the group consisting of formula (2), formula (3), formula (6), and formula (7) or a salt thereof; An azo compound or a salt thereof selected from the group consisting of formula (8) and formula (9), An azo compound or a salt thereof selected from the group consisting of formula (10) and formula (11), By containing at least one of these, it is possible to obtain a polarizing element having high transmittance and a high degree of polarization in the visible and near infrared regions. An azo compound selected from the group consisting of formula (2), formula (3), formula (6), and formula (7) or a salt thereof; An azo compound or a salt thereof selected from the group consisting of formula (8) and formula (9), An azo compound or a salt thereof selected from the group consisting of formula (10) and formula (11), By using this, it is possible to obtain a polarizing element that exhibits a high degree of polarization not only in the near infrared region but also in the region of 400 to 780 nm in particular, and that has high transmittance and a high degree of polarization even in terms of luminosity-corrected transmittance and polarization degree, i.e., transmittance and polarization degree as seen with the naked eye.

[0182] (Transmittance after visual sensitivity correction) The transmittance after luminosity correction is the transmittance after luminosity correction obtained according to JIS Z 8722:2009. The transmittance used for correction can be measured by measuring the spectral transmittance for each wavelength of 380 to 780 nm for a measurement sample (for example, a polarizing element or a polarizing plate) at intervals of 5 nm or 10 nm using a C light source (2-degree visual field) and correcting the transmittance to luminosity according to JIS Z 8722:2009. The transmittance after luminosity correction includes the single transmittance after luminosity correction when a polarizing element or a polarizing plate is measured alone, the parallel transmittance after luminosity correction when the transmittance when two polarizing elements or polarizing plates are used and the absorption axes of each are parallel is corrected to luminosity, and the orthogonal transmittance after luminosity correction when the transmittance when two polarizing elements or polarizing plates are used and the absorption axes of each are perpendicular is corrected to luminosity.

[0183] The single transmittance after luminosity correction is the single transmittance after luminosity correction using a 2-degree visual field (C light source). The single transmittance after luminosity correction can be obtained by calculating the single transmittance for each 5 nm or 10 nm for each wavelength of 380 to 780 nm for one measurement sample (for example, a polarizing element or polarizing plate), and then performing luminosity correction using a 2-degree visual field (C light source).

[0184] In one embodiment, the polarizing element according to the present invention may have a single transmittance after luminosity correction of 30% to 65%. The single transmittance after luminosity correction is the transmittance corrected to luminosity according to JIS Z 8722:2009 for one measurement sample (for example, a polarizing element or a polarizing plate). A polarizing plate is required to have a higher transmittance, and if the single transmittance after luminosity correction is 30% to 65%, it can express brightness without discomfort even when used in a display device. Since the higher the transmittance, the lower the degree of polarization tends to be, from the viewpoint of balance with the degree of polarization, the single transmittance after luminosity correction is more preferably 35% to 50%, further preferably 37% to 47%, and particularly preferably 38% to 45%. If the single transmittance after luminosity correction exceeds 65%, the degree of polarization may decrease, but if a bright transmittance of the polarizing element or a specific polarization performance or contrast is required, the single transmittance after luminosity correction may exceed 65%.

[0185] (degree of polarization) The polarizing element of the present invention has polarizing performance for light at least in part or all of the visible range of 380 to 780 nm, and at least in part or all of the near-infrared range of 700 to 1400 nm.

[0186] The polarization degree after luminosity correction and the polarization degree at 700 to 1400 nm of the polarizing element of the present invention are not particularly limited, but if the polarization degree after luminosity correction and the polarization degree at 700 to 1400 nm are 80 to 100%, the polarizing element can be used for general-purpose applications. The polarization degree is preferably 90% or more. If the polarization degree of the polarizing element is 90% or more, it can exhibit a polarizing function even when used in a liquid crystal display device. The polarization degree is preferably 99% or more, more preferably 99.9% or more, and even more preferably 99.95% or more. However, the polarization degree requirement is different depending on the application in relation to brightness (transmittance) and contrast (polarization degree), so it does not necessarily have to be 99%, and the polarization degree can be set and used according to the requirement.

[0187] (chromaticity) The chromaticity a* and b* values ​​are values ​​obtained when measuring the transmittance of natural light according to JIS Z 8781-4:2013. The method of displaying object colors defined in JIS Z 8781-4:2013 corresponds to the method of displaying object colors defined by the International Commission on Illumination (abbreviated as CIE). The chromaticity a* and b* values ​​are measured by irradiating a measurement sample (e.g., a polarizing element or a polarizing plate) with natural light. In the following, the chromaticity a* and b* values ​​obtained for one measurement sample are indicated as a*-s and b*-s, the chromaticity a* and b* values ​​obtained for a state in which two measurement samples are arranged so that their absorption axis directions are parallel to each other (when displaying white) are indicated as a*-p and b*-p, and the chromaticity a* and b* values ​​obtained for a state in which two measurement samples are arranged so that their absorption axis directions are perpendicular to each other (when displaying black) are indicated as a*-c and b*-c.

[0188] In one embodiment, the polarizing element according to the present invention preferably has absolute values ​​of a*-s and b*-s of 1.0 or less, and more preferably has absolute values ​​of a*-p and b*-p of 2.0 or less. Such a polarizing element is a neutral color by itself, and can display high-quality white when white is displayed. The absolute values ​​of a*-p and b*-p of the polarizing element are each preferably 1.5 or less, and more preferably 1.0 or less. Furthermore, the absolute values ​​of a*-c and b*-c of the polarizing element are preferably 3.0 or less, and more preferably 2.0 or less, and more preferably 1.0 or less. Such a polarizing element can display achromatic black when black is displayed. Even if the absolute values ​​of the chromaticity a* and b* values ​​have a difference of only 0.5, humans can perceive a difference in color, and some people may feel a large difference in color. For this reason, it is very important to control these values ​​in the polarizing element. In particular, when the absolute values ​​of a*-p, b*-p, a*-c, and b*-c are each 1.0 or less, a good polarizing plate can be obtained in which other colors are hardly discernible in the white color when white is displayed and in the black color when black is displayed. Such a polarizing plate can realize achromaticity in the parallel position, i.e., a high-quality paper-like white color, and can realize achromatic, clear, luxurious black color in the perpendicular position.

[0189] In one embodiment, the polarizing element according to the present invention has high contrast and high transmittance, while also having achromaticity and a high degree of polarization by itself. The polarizing element according to the present invention can express a high-quality paper-like white color (paper white) when displaying white, and can express an achromatic black color, particularly a clear black color with a luxurious feel, when displaying black. Until now, there has been no polarizing element that combines such high transmittance and achromaticity, infrared absorption performance, and infrared polarization performance. The polarizing element according to the present invention is further characterized by being highly durable, particularly durable against high temperatures and high humidity.

[0190] [Polarizing plate] The polarizing plate of the present invention has a transparent protective layer formed on at least one surface of the polarizing element, i.e., on one or both surfaces. A polymer is applied to at least one surface of the polarizing element, and then drying or heat treatment is performed to provide a transparent protective layer on at least one surface of the polarizing element. Alternatively, a polymer is molded into a film to form a transparent protective layer, and the transparent protective layer is attached to at least one surface of the polarizing element, and then drying or heat treatment is performed to provide a transparent protective layer on at least one surface of the polarizing element.

[0191] The polymer forming the transparent protective layer is preferably a transparent polymer having high mechanical strength and good thermal stability. Examples of such polymers include cellulose acetate resins such as triacetyl cellulose and diacetyl cellulose, acrylic resins, polyvinyl chloride resins, nylon resins, polyester resins, polyarylate resins, cyclic polyolefin resins having cyclic olefins such as norbornene as monomers, polyethylene, polypropylene, cycloolefin polymer resins, polyolefins having a norbornene skeleton or copolymers thereof, and resins having imide groups and / or amide groups in the main chain or side chain. The polymer forming the transparent protective layer may be a liquid crystal polymer. The thickness of the transparent protective layer is, for example, about 0.5 to 200 μm. A polarizing plate having a transparent protective layer has optical properties equivalent to those of a polarizing element.

[0192] An adhesive is required to bond the transparent protective layer to at least one surface of the polarizing element. The adhesive is not particularly limited, but an adhesive containing polyvinyl alcohol as a main component is preferable. Examples of polyvinyl alcohol-based adhesives include, but are not limited to, Gohsenol NH-26 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and Exeval RS-2117 (manufactured by Kuraray Co., Ltd.). A crosslinking agent and / or a water-resistant agent can be mixed into the polyvinyl alcohol-based adhesive. In addition, the polyvinyl alcohol-based adhesive may contain a copolymer of maleic anhydride and isobutylene, or a modified product thereof. Examples of the copolymer of maleic anhydride and isobutylene include ISOBAM #18 (manufactured by Kuraray Co., Ltd.) and ISOBAM #04 (manufactured by Kuraray Co., Ltd.). Examples of the ammonia-modified maleic anhydride-isobutylene copolymer include ISOBAM #104 (manufactured by Kuraray Co., Ltd.) and ISOBAM #110 (manufactured by Kuraray Co., Ltd.). Examples of the imidized maleic anhydride-isobutylene copolymer include ISOBAM #304 (manufactured by Kuraray Co., Ltd.) and ISOBAM #310 (manufactured by Kuraray Co., Ltd.). As the crosslinking agent, a water-soluble multifunctional epoxy compound can be used. Examples of the water-soluble multifunctional epoxy compound include polyglycerol polyglycidyl ether (Denacol EX-521 (manufactured by Nagase Chemtec Corporation)) and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (TETRAD-C (manufactured by Mitsubishi Gas Chemical Co., Ltd.)). Also, known adhesives such as urethane adhesives, acrylic adhesives, and epoxy adhesives can be used. Furthermore, for the purpose of improving the adhesive strength of the adhesive or improving water resistance, additives such as zinc compounds, chlorides, iodides, etc. may also be simultaneously contained at a concentration of about 0.1 to 10 mass %.

[0193] When the polarizing plate is attached to a display device such as a liquid crystal display or an organic electroluminescence display, various functional layers for improving the viewing angle and / or contrast, or a layer having a brightness improving property can be provided on the surface that will later become the non-exposed surface. It is preferable to use an adhesive to attach the polarizing plate to these layers or the display device.

[0194] In addition, when the polarizing plate is laminated to a display device such as a liquid crystal display or an organic electroluminescence display, various known functional layers such as an anti-reflection layer, an anti-glare layer, a hard coat layer, etc. can be provided on the surface that will be exposed later. A coating method is preferable for producing the layers having various functions, but a film having the functions can also be laminated via an adhesive or a pressure sensitive adhesive. In addition, the various functional layers are, for example, layers that control the retardation.

[0195] The polarizing plate of the present invention may have a support on at least one surface. The support preferably has a flat surface in order to be bonded to the polarizing plate. Examples of the support include molded products made of inorganic materials such as glass, quartz, and sapphire, and organic plastic plates such as acrylic and polycarbonate. Since the polarizing plate is used for optical purposes, the support is preferably a molded glass product. Examples of the molded glass product include glass plates, lenses, and prisms (e.g., triangular prisms and cubic prisms). Examples of glass materials include soda glass and borosilicate glass. A lens with a polarizing plate attached thereto can be used as a condenser lens with a polarizing plate in a liquid crystal projector. A prism with a polarizing plate attached thereto can be used as a polarizing beam splitter with a polarizing plate or a dichroic prism with a polarizing plate in a liquid crystal projector. The polarizing plate may also be attached to a liquid crystal cell. The thickness and size of the support are not particularly limited.

[0196] In order to further improve the single-piece transmittance of the polarizing plate having glass, it is preferable to provide an anti-reflection layer on at least one surface of the glass or the polarizing plate. For example, a transparent adhesive (sticky) agent is applied to the flat surface of the support, and then the polarizing plate of the present invention is attached to this coated surface. Alternatively, a transparent adhesive (sticky) agent may be applied to the polarizing plate, and then the support may be attached to this coated surface. The adhesive (sticky) agent used here is preferably, for example, an acrylic acid ester-based one. When this polarizing plate is used as an elliptical polarizing plate, the retardation layer is usually attached to the support, but the polarizing plate may be attached to the support.

[0197] [Liquid crystal display device] The polarizing element or polarizing plate of the present invention can be used in a liquid crystal display device. A liquid crystal display device using the polarizing element or polarizing plate of the present invention is a liquid crystal display device having high reliability, high contrast over a long period of time, and high color reproducibility.

[0198] The polarizing element or polarizing plate of the present invention is provided with a protective layer or functional layer, a support, etc. as necessary, and is used in liquid crystal projectors, calculators, clocks, notebook computers, word processors, liquid crystal televisions, polarizing lenses, polarizing glasses, car navigation systems, sensors, cameras, analytical devices, and indoor and outdoor measuring instruments and displays, etc. In particular, it is effectively used in reflective liquid crystal displays, semi-transmissive liquid crystal displays, organic electroluminescence, etc. EXAMPLES

[0199] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0200] <Example 1> A polyvinyl alcohol film (VF-PS manufactured by Kuraray Co., Ltd.) with an average polymerization degree of 2400 and a saponification degree of 99% or more was used as a substrate, and it was immersed in warm water at 40°C for 2 minutes and swelled to a stretching ratio of 1.30. Next, 1500 parts by mass of water, 1.5 parts by mass of sodium tripolyphosphate, 1.5 parts by mass of anhydrous sodium sulfate, 1.3 parts by mass of Example Compound 1-16 of the present application as the azo compound of formula (1), 0.15 parts by mass of Example Compound 2-1 of the present application as an azo compound of formula (2), 0.15 parts by mass of Example Compound 8-16 of the present application as an azo compound of formula (8), 0.078 parts by mass of Example Compound 10-1 of the present application as the azo compound of formula (10), The swelling-treated film was immersed for 15 minutes in an aqueous dyeing solution containing each of the above and adjusted to 45°C. Next, the obtained film was immersed in an aqueous solution prepared by dissolving 40 parts by mass of boric acid (manufactured by Società chimica lardrello s.p.a) in 2000 parts of water at 40°C for 2 minutes. Next, the obtained film was subjected to a stretching treatment at 50°C for 5 minutes in an aqueous solution containing 30.0 g / l of boric acid so that the stretching ratio became 5.0 times. Next, the obtained film was immersed in water at 20°C for 20 seconds (washing treatment). Next, the obtained film was dried at 70°C for 9 minutes to obtain a polarizing element. Using a polyvinyl alcohol adhesive, an alkali-treated triacetyl cellulose film (ZRD-60 manufactured by Fujifilm Corporation) was laminated on the obtained polarizing element to obtain a polarizing plate. The obtained polarizing plate maintained the optical properties of the polarizing element. The polarizing plate was cut into a 40 mm square and bonded to a transparent plate glass via an adhesive layer (AD-ROC manufactured by Polatechno) to prepare a durability test sample using the polarizing plate of the present application, which was used as the measurement sample of the present application.

[0201] <Example 2> In Example 1, the azo compound used was 1.3 parts by mass of Compound Example 1-16 of the present application as the azo compound of formula (1), 0.08 part by mass of Compound Example 7-7 of the present application as the azo compound of formula (7), 0.05 part by mass of Compound Example 9-25 of the present application as the azo compound of formula (9), 0.078 part by mass of Compound Example 10-1 of the present application as the azo compound of formula (10), was changed to, and a polarizing element, a polarizing plate, and a durability test sample were prepared in the same manner as in Example 1 except that the immersion time of the swollen film was changed to 14 minutes, which was used as the measurement sample of the present application.

[0202] <Example 3> In Example 1, the azo compound used was 1.3 parts by mass of Compound Example 1-16 of the present application as the azo compound of formula (1), 0.07 part by mass of Compound Example 6-13 of the present application as the azo compound of formula (6), 0.06 part by mass of Compound Example 9-45 of the present application as the azo compound of formula (9), 0.078 parts by mass of Example Compound 10-1 of the present application as the azo compound of formula (10), A polarizing element, a polarizing plate, and a durability test sample were prepared in the same manner as in Example 1, except that the immersion time of the swollen film was changed to 17 minutes instead of 15 minutes. These were used as the measurement samples of the present application.

[0203] <Example 4> The azo compound used in Example 1 was 0.9 parts by mass of Example Compound 1-43 of the present application as the azo compound of formula (1), 0.06 parts by mass of Example Compound 7-20 of the present application as an azo compound of formula (7), 0.05 parts by mass of Example Compound 9-41 of the present application as an azo compound of formula (9), 0.05 parts by mass of Example Compound 11-86 of the present application as an azo compound of the formula (11), A polarizing element, a polarizing plate, and a durability test sample were prepared in the same manner as in Example 1, except that the immersion time of the swollen film was changed to 16 minutes 30 seconds instead of 1.0 minutes 10 seconds. These were used as the measurement samples of the present application.

[0204] <Example 5> The azo compound used in Example 1 was 0.9 parts by mass of Example Compound 1-43 of the present application as the azo compound of formula (1), 0.1 parts by mass of Example Compound 6-32 of the present application as an azo compound of formula (6), 0.04 parts by mass of Example Compound 9-77 of the present application as an azo compound of formula (9), 0.05 parts by mass of Example Compound 11-86 of the present application as an azo compound of the formula (11), A polarizing element, a polarizing plate, and a durability test sample were prepared in the same manner as in Example 1, except that the immersion time of the swollen film was changed to 18 minutes and 00 seconds, and these were used as the measurement samples of the present application.

[0205] <Example 6> The azo compound used in Example 1 was 0.7 parts by mass of Example Compound 1-27 of the present application as the azo compound of formula (1), 0.065 parts by mass of Example Compound 7-23 of the present application as the azo compound of formula (7), 0.03 parts by mass of Example Compound 9-8 of the present application as an azo compound of formula (9), 0.05 parts by mass of Example Compound 10-2 (f=2) of the present application as an azo compound of formula (10), A polarizing element, a polarizing plate, and a durability test sample were prepared in the same manner as in Example 1, except that the immersion time of the swollen film was changed to 12 minutes and 00 seconds, and these were used as the measurement samples of the present application.

[0206] <Example 7> The azo compound used in Example 1 was 0.7 parts by mass of Example Compound 1-27 of the present application as the azo compound of formula (1), 0.07 parts by mass of Example Compound 7-28 of the present application as an azo compound of formula (7), 0.02 parts by mass of Example Compound 9-9 of the present application as an azo compound of formula (9), 0.05 parts by mass of Example Compound 10-2 (f=2) of the present application as an azo compound of formula (10), A polarizing element, a polarizing plate, and a durability test sample were prepared in the same manner as in Example 1, except that the immersion time of the swollen film was changed to 13 minutes and 30 seconds instead of the above, and these were used as the measurement samples of the present application.

[0207] <Example 8> The azo compound used in Example 1 was 0.7 parts by mass of Example Compound 1-27 of the present application as the azo compound of formula (1), 0.1 parts by mass of Example Compound 3-9 of the present application as an azo compound of formula (3), 0.04 parts by mass of Example Compound 9-50 of the present application as an azo compound of the formula (9), 0.05 parts by mass of Example Compound 11-84 of the present application as an azo compound of formula (11), A polarizing element, a polarizing plate, and a durability test sample were prepared in the same manner as in Example 1, except that the immersion time of the swollen film was changed to 15 minutes instead of 15 minutes, and these were used as the measurement samples of the present application.

[0208] <Example 9> The azo compound used in Example 1 was 1.0 part by mass of Example Compound 1-5 of the present application as an azo compound of formula (1), 0.05 parts by mass of Example Compound 6-30 of the present application as an azo compound of formula (6), 0.18 parts by mass of Example Compound 8-23 of the present application as an azo compound of formula (8), 0.05 parts by mass of Example Compound 10-2 (f=2) of the present application as an azo compound of formula (10), A polarizing element, a polarizing plate, and a durability test sample were prepared in the same manner as in Example 1, except that the immersion time of the swollen film was changed to 11 minutes instead of 1.0 minutes. These were used as the measurement samples of the present application.

[0209] <Example 10> The azo compound used in Example 1 was 1.0 part by mass of Example Compound 1-5 of the present application as an azo compound of formula (1), 0.03 parts by mass of Example Compound 9-29 of the present application as an azo compound of formula (9), 0.05 parts by mass of Example Compound 9-6 of the present application as an azo compound of formula (9), 0.05 parts by mass of Example Compound 10-2 (f=2) of the present application as an azo compound of formula (10), A polarizing element, a polarizing plate, and a durability test sample were prepared in the same manner as in Example 1, except that the immersion time of the swollen film was changed to 12 minutes instead of 1.0 minutes. These were used as the measurement samples of the present application.

[0210] <Example 11> The azo compound used in Example 1 was 1.0 part by mass of Example Compound 1-5 of the present application as an azo compound of formula (1), 0.07 parts by mass of Example Compound 3-7 of the present application as the azo compound of formula (3), 0.07 parts by mass of Example Compound 9-89 of the present application as an azo compound of formula (9), 0.05 parts by mass of Example Compound 11-84 of the present application as an azo compound of formula (11), A polarizing element, a polarizing plate, and a durability test sample were prepared in the same manner as in Example 1, except that the immersion time of the swollen film was changed to 18 minutes instead of 15 minutes. These were used as the measurement samples of the present application.

[0211] <Comparative Example 1> A polarizing plate was prepared as a measurement sample in the same manner as in Example 1 of the present application, except that a polarizing element was prepared using an azo compound according to Comparative Example B1 of Patent Document 7. Comparative Example B1 of Patent Document 7 is the same as the experimental example of preparing a polarizing element obtained from a dyeing aqueous solution not using the azo compound represented by formula (1) in Example 11 of the present application.

[0212] <Comparative Example 2> A polarizing plate was prepared as a measurement sample in the same manner as in Example 1 of the present application, except that a polarizing element was prepared using an azo compound according to Comparative Example C1 of Patent Document 7. Comparative Example C1 of Patent Document 7 is the same as the experimental example of preparing a polarizing element obtained from a dyeing aqueous solution not using the azo compound represented by formula (1) in Example 9 of the present application.

[0213] <Comparative Example 3> A polarizing plate was prepared as a measurement sample in the same manner as in Example 1 of the present application, except that a polarizing element was prepared using an azo compound according to Example B6 of Patent Document 7.

[0214] [Evaluation method] The polarizing plates obtained in Examples 1 to 11 and Comparative Examples 1 to 3 were evaluated as follows.

[0215] (a) Single transmittance Ts of each wavelength, parallel transmittance Tp of each wavelength, and cross transmittance Tc of each wavelength The single transmittance Ts, parallel transmittance Tp, and cross transmittance Tc of each wavelength of each measurement sample were measured using a spectrophotometer (Hitachi's "U-4100"). Here, the single transmittance Ts of each wavelength is the transmittance of each wavelength when one measurement sample is measured. The parallel transmittance Tp of each wavelength is the transmittance of each wavelength measured by stacking two measurement samples so that their absorption axis directions are parallel to each other. The cross transmittance Tc of each wavelength is the transmittance of each wavelength measured by stacking two measurement samples so that their absorption axis directions are perpendicular to each other. The measurements were performed at 5 nm intervals over wavelengths from 380 to 1200 nm.

[0216] (b) Single transmittance Ys after luminosity correction, parallel transmittance Yp after luminosity correction, and perpendicular transmittance Yc after luminosity correction The luminosity-corrected single transmittance Ys, the luminosity-corrected parallel transmittance Yp, and the luminosity-corrected cross-phase transmittance Yc of each measurement sample were obtained. The luminosity-corrected single transmittance Ys, the luminosity-corrected parallel transmittance Yp, and the luminosity-corrected cross-phase transmittance Yc are transmittances corrected to luminosity according to JIS Z 8722:2009 for the single transmittance Ts, the parallel transmittance Tp, and the cross-phase transmittance Tc of each wavelength obtained at a predetermined wavelength interval dλ (here, 5 nm) in the wavelength range of 380 to 780 nm. Specifically, the single transmittance Ts, the parallel transmittance Tp, and the cross-phase transmittance Tc of each wavelength were calculated by substituting them into the following formulas (I) to (III). In the following formulas (I) to (III), Pλ represents the spectral distribution of standard light (C light source), and yλ represents the 2-degree visual field color matching function.

number

[0217] (c) Degree of polarization The degree of polarization ρy was calculated from the luminosity-corrected parallel transmittance Yp and the luminosity-corrected perpendicular transmittance Yc according to the following calculation formula (IV).

number

[0218] (d) Dichroic ratio (Rd) In the polarizing elements shown in Examples 1 to 11 and Comparative Examples 1 to 3, the absorbance of the polarizing elements was evaluated using a spectrophotometer (Hitachi High-Technologies Corporation's "U-4100"). A Gram-Thompson polarizer capable of irradiating light having 100% polarization in the wavelength region of 380 to 1200 nm (hereinafter referred to as "absolutely polarized light") was installed in each polarizing element produced in each of Examples 1 to 11 and Comparative Examples 1 to 3, and the absorbance of light of each wavelength when the absolute polarized light was irradiated on each measurement sample was measured. The absorbance measured when the absolute polarized light was irradiated and light polarized in a direction perpendicular to the axis showing the highest light absorption in the polarizing element was made Abs-Ky, and the absorbance at that time was made Abs-Ky. The light transmittance measured when the absolute polarized light was irradiated and light polarized in a direction parallel to the axis showing the highest light absorption in the polarizing element was made Abs-Kz. The ratio of Abs-Ky to Abs-Kz, i.e., Abs-Kz / Abs-Ky, was calculated, and the wavelength region where the dichroic ratio (Rd) was 5 or more and the wavelength region where the dichroic ratio (Rd) was 10 or more were confirmed.

[0219] Table 1 shows Ys, Yp, Yc, contrast (CR), ρy, wavelength ranges where the dichroic ratio (Rd) is 5 or more, and wavelength ranges where the dichroic ratio (Rd) is 10 or more for Examples 1 to 11 and Comparative Examples 1 to 3. The value obtained by dividing Yp by Yc is represented as contrast (CR). [Table 1]

[0220] <Durability test> The durability test samples of Examples 1 to 11 were subjected to an environment of 85°C and 85% RH for 240 hours. As a result, no change in transmittance or hue was observed in the measurement samples of Examples 1 to 11. It was found that Examples 1 to 11 have high durability.

[0221] From Table 1 above, it is evident that the polarizing element of the present invention has a high degree of polarization in the visible range, and functions as a polarizing element over a wide band even in the infrared range. It is understood that the polarizing element or polarizing plate of the present application has a high transmittance and polarization degree in the visible range, while having a high polarization degree in the infrared range over a wide wavelength range. It has also been shown that the polarizing plate can achieve high durability in the visible and infrared ranges. [Industrial Applicability]

[0222] The polarizing element or polarizing plate of the present invention is used in optical devices such as liquid crystal displays, organic electroluminescence (EL), liquid crystal projectors, calculators, clocks, notebook computers, word processors, liquid crystal televisions, polarized lenses, polarized glasses, car navigation systems, and indoor and outdoor measuring instruments and displays, infrared sensors, infrared cameras, optical isolators, security systems, etc. In particular, it can be effectively used in lenses, sensors, liquid crystal display devices, organic electroluminescence, etc.

Claims

1. Contains at least an azo compound represented by formula (15) or a salt thereof, and An azo compound represented by formula (2) or a salt thereof, An azo compound represented by formula (3) or a salt thereof, An azo compound represented by formula (6) or a salt thereof, An azo compound represented by formula (7) or a salt thereof, An azo compound represented by formula (8) or a salt thereof, An azo compound represented by formula (9) or a salt thereof, An azo compound represented by formula (10) or a salt thereof, and An azo compound represented by formula (11) or a salt thereof, Further containing an azo compound selected from A polarizing element characterized by: 【Chemistry 1】 (In formula (15), A １ represents an optionally substituted phenyl group, an optionally substituted naphthyl group, or an optionally substituted heterocyclic group; A ２ , A ３ , A ４ each independently represents a phenyl group which may have a substituent or a naphthyl group which may have a substituent, n is 1 or 2, k is 0 or 1, and the hydrogen atoms of the rings a and b are each independently selected from the group consisting of a substituent SO ３ may be substituted with H. 【Chemistry 2】 (In formula (2), Ab １１ , Ab １２ each independently represents a naphthyl group having a substituent or a phenyl group having a substituent, at least one of the substituents being a hydrogen atom, a sulfo group, a C1-4 alkyl group, a C1-4 alkoxy group, a C1-4 alkoxy group having a sulfo group, a carboxy group, a nitro group, an amino group, or a substituted amino group; Rb １１ , Rb １２ each independently represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, a sulfo group, or a C1-4 alkoxy group having a sulfo group. 【Chemistry 3】 (In formula (3), Ag １ represents a phenyl group having a substituent or a naphthyl group having a substituent, Bg and Cg are each independently represented by the following formula (4) or the following formula (5), and at least one of them represents formula (4), Xg １ represents an amino group which may have a substituent, a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a naphthotriazole group which may have a substituent, or a benzoylamino group which may have a substituent. 【Chemistry 4】 (In formula (4), Rg １ represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group, and j represents an integer of 0 to 2. 【Chemistry 5】 (In formula (5), Rg ２ and Rg ３ each independently represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group. 【Chemistry 6】 (In formula (6), Ab ２１ represents a phenyl group or a naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group, Rb ２１ ~Rb ２４ each independently represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group; Rb ２５ and Rb ２６ each independently represents a hydrogen atom, a hydroxyl group, a C1-4 alkyl group, or a C1-4 alkoxy group, Xb ２１ represents an unsubstituted amino group, an amino group having one or two C1-4 alkyl groups which may have substituents (selected from the group consisting of C1-4 alkoxy groups, sulfo groups, amino groups, C1-4 alkylamino groups, hydroxy groups, carboxy groups, and carboxyethylamino groups), a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a naphthotriazole group which may have a substituent, or a benzoylamino group which may have a substituent; d represents 0 or 1, and when d is 1, Rb ２５ and a metal complex compound based on a hydroxy group of the naphthyl group and a metal atom; Rb ２６ represents a hydrogen atom, a lower alkyl group, or a lower alkoxy group. 【Chemistry 7】 (In formula (7), Ab ３１ represents a phenyl group or a naphthyl group having at least one substituent selected from the group consisting of a sulfo group, a carboxy group, a nitro group, and an amino group; Rb ３１ ~Rb ３３ represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group; Xb ３１ represents an unsubstituted amino group, an amino group having one or two C1-4 alkyl groups which may have substituents (selected from the group consisting of C1-4 alkoxy groups, C1-4 alkylamino groups, hydroxy groups, carboxy groups, sulfo groups, amino groups, and substituted amino groups), a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a naphthotriazole group which may have a substituent, a benzoylamino group which may have a substituent, or a benzoyl group which may have a substituent; e １ Or e ２ each independently represents 0 or 1) 【Chemistry 8】 (In formula (8), Ac １ represents a phenyl group or a naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group, Rc １１ ~Rc １４ each independently represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group. 【Chemistry 9】 (In formula (9), Ac ２ represents a phenyl group or a naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group, Rc ２１ ~Rc ２７ each independently represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group, Rc ２８ represents a hydrogen atom, a C1-4 alkyl group, or a C1-4 alkoxy group having a sulfo group, Xc ２ represents an unsubstituted amino group, an amino group having one or two C1-4 alkyl groups which may have substituents (selected from the group consisting of C1-4 alkoxy groups, sulfo groups, C1-4 alkylamino groups, hydroxy groups, amino groups, substituted amino groups, carboxy groups, and carboxyethylamino groups), a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a naphthotriazole group which may have a substituent, or a benzoylamino group which may have a substituent, and r, p, and q each independently represent 0 or 1, except for the case where r, p, and q are all 1. 【Chemistry 10】 (In formula (10), Ay １１ represents a sulfo group, a carboxy group, a hydroxy group, a C1-4 alkyl group, or a C1-4 alkoxy group; Ry １１ ~Ry １４ each independently represents a hydrogen atom, a sulfo group, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group, and f represents an integer of 1 to 3. 【Chemistry 11】 (In formula (11), Ay ２１ and Ay ２２ each independently represents a naphthyl group which may have a substituent or a phenyl group which may have a substituent; R ２１ , Ry ２２ , Ry ２７ , Ry ２８ are each independently a hydrogen atom, a C1-4 alkyl group, or a C1-4 alkoxy group; R ２３ ~Ry ２６ each independently represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group, and each of s and t independently represents 0 or 1.

2. 2. The polarizing element according to claim 1, comprising at least an azo compound selected from the group consisting of those represented by formula (2), (3), (6) and (7) or a salt thereof.

3. 2. The polarizing element according to claim 1, comprising at least an azo compound selected from formula (8) or formula (9) or a salt thereof.

4. 2. The polarizing element according to claim 1, comprising at least an azo compound selected from formula (10) or (11) or a salt thereof.

5. An azo compound or a salt thereof selected from the group consisting of formula (2), formula (3), formula (6), and formula (7); An azo compound or a salt thereof selected from formula (8) and formula (9), The polarizing element according to claim 1 , comprising at least

6. An azo compound or a salt thereof selected from the group consisting of formula (2), formula (3), formula (6), and formula (7); An azo compound or a salt thereof selected from formula (10) and formula (11), The polarizing element according to claim 1 , comprising at least

7. An azo compound or a salt thereof selected from formula (8) and formula (9), An azo compound or a salt thereof selected from formula (10) and formula (11), The polarizing element according to claim 1 , comprising at least

8. 8. The polarizing element according to claim 1, which comprises a substrate which is a polyvinyl alcohol-based resin film.

9. A polarizing plate comprising the polarizing element according to claim 8 and a transparent protective layer on at least one surface of the polarizing element.

10. An optical device comprising the polarizing plate according to claim 9.

11. 11. The optical device according to claim 10, which is a liquid crystal display device.

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