CN111448494B

CN111448494B - Polarizer for visible light region and infrared light region, and polarizing plate

Info

Publication number: CN111448494B
Application number: CN201880079433.7A
Authority: CN
Inventors: 望月典明; 樋下田贵大
Original assignee: Nippon Kayaku Co Ltd; Polatechno Co Ltd
Current assignee: Nippon Kayaku Co Ltd; Polatechno Co Ltd
Priority date: 2017-12-13
Filing date: 2018-12-11
Publication date: 2022-05-31
Anticipated expiration: 2038-12-11
Also published as: JP2023052132A; CN111448494A; CN114350175A; JP2023040123A; TW201932542A; JPWO2019117123A1; TWI783092B; JP7319195B2; WO2019117123A1

Abstract

Provided is a polarizing element comprising a water-soluble compound that absorbs light in the infrared region or a salt thereof.

Description

Polarizing element for visible light region and infrared region, and polarizing plate

Technical Field

The present invention relates to a polarizing element, a polarizing plate, and a liquid crystal display device each containing a water-soluble compound or a salt thereof that absorbs light in the near infrared region.

Background

The polarizing film is generally produced by adsorbing and orienting iodine or a dichroic dye of a dichroic dye to a polyvinyl alcohol resin film. A polarizing film using iodine as a dichroic dye is called an iodine-based polarizing film, and a polarizing film using a dichroic dye as a dichroic dye is called a dye-based polarizing film. A protective film made of triacetyl cellulose or the like is bonded to at least one surface of these polarizing films via an adhesive layer, and the polarizing films are used for a liquid crystal display device or the like. An iodine-based polarizing plate composed of an iodine-based polarizing film has a higher transmittance and exhibits a higher degree of polarization, that is, a higher contrast, than a dye-based polarizing plate composed of a dye-based polarizing film, and thus can be widely used in general liquid crystal monitors, liquid crystal televisions, cellular phones, PDAs, and the like. However, although the iodine-based polarizing plate is superior to the dye-based polarizing plate in terms of optical characteristics, it is inferior to the dye-based polarizing plate in terms of optical durability, and for example, when the iodine-based polarizing plate is left under high temperature and humidity, the transmittance increases due to discoloration, and problems such as a decrease in polarization degree occur. A polarizing plate having high transmittance and polarization degree, high contrast, and excellent heat resistance and humidity resistance is required, and a polarizing plate having high transmittance and polarization degree, high contrast, and excellent environmental test such as dry heat durability is required for the required invention. The inventions claimed for this purpose are zinc-containing patents such as patent documents 1 to 3, polarizing plates treated with triterpene-like glycosides such as patent document 4, and techniques for improving heat resistance by polyaldehyde such as patent document 5. However, the above-mentioned requirements have not been sufficiently satisfied, and a polarizing plate that can be easily produced at low cost is desired to have high resistance such as dry heat resistance.

A general polarizing plate is manufactured by dyeing or containing iodine or a dichroic dye as a polarizing element on a polarizing film substrate such as a film of polyvinyl alcohol or a derivative thereof oriented by stretching, or a polyene film in which polyene is produced by dehydrochlorination of a polyvinyl chloride film or dehydration of a polyvinyl alcohol film and oriented. Of these, an iodine-based polarizing film using iodine as a polarizing element has excellent polarizing performance, but has a problem in durability when used for a long time under a high temperature and high humidity state due to weak water and heat, and cannot control transmittance to an infrared region. On the other hand, a dye-based polarizing film using a dichroic dye as a polarizing element is superior to an iodine-based polarizing film in moisture resistance and heat resistance, but is a polarizing plate having a polarizing function for wavelengths in the visible light wavelength range, and is not a polarizing plate in which the transmittance in the infrared wavelength range is controllable.

In recent years, polarizing plates for use in not only visible light wavelengths but also infrared wavelengths have been required for use in applications such as recognition light sources for touch panels, image monitors, sensors, anti-counterfeiting devices, and communication devices. For such a demand, the following reports have been made: an infrared polarizing plate in which an iodine polarizing plate is polyalkylenated as in patent document 15, an infrared polarizing plate to which a wire grid as in patent document 16 or 14 is applied, an infrared polarizer in which a glass containing fine particles is stretched as in patent document 17, or a type using a cholesteric liquid crystal as in patent document 18 or 6. Patent document 15 is not practical because of poor durability, heat resistance, moist heat resistance, and light resistance. The wire grid type, as disclosed in patent documents 16 and 14, is also processed into a film type and is stabilized as a product, and thus has been widely used. However, if the surface has no nano-level unevenness, the optical characteristics cannot be maintained, and the surface does not touch, so that the application thereof is limited, and anti-reflection or anti-glare (anti-glare) processing is difficult. The glass drawn type including fine particles as in patent document 17 has been put to practical use because it has high durability and high dichroism. However, since the glass contains fine particles and is stretched, the element itself is easily cracked and weakened, and the glass is not as flexible as a conventional polarizing plate and has a problem that it is difficult to surface-process or bond other substrates. The technique of reference 5 uses circular polarization as disclosed in the related art, but it is difficult to form stray light or absolute polarization because the color changes depending on the angle of recognition or the technique is basically a polarizing plate using reflection. That is, a general polarizing plate is an absorption-type polarizing element, and is a film-type polarizing plate having flexibility and no wavelength region corresponding to infrared rays having high durability.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent application laid-open No. S61-175602

[ patent document 2] Japanese patent application laid-open No. 2003-50318

[ patent document 3] Japanese patent application laid-open No. 2003-29042

[ patent document 4] Japanese patent laid-open No. 2005-241689

[ patent document 5] Japanese patent application laid-open No. 6-235815

[ patent document 6] Japanese patent application laid-open No. 2-167791

[ patent document 7] Japanese patent application laid-open No. S61-221264

[ patent document 8] Japanese Kokai publication 2006-508034

[ patent document 9] Japanese patent application laid-open No. Sho 63-33477

[ patent document 10] International publication No. 2013/035560

[ patent document 11] Japanese patent application laid-open No. S59-11385

[ patent document 12] Japanese patent application laid-open No. 2010-106248

[ patent document 13] Japanese patent application laid-open No. 2001-181184

[ patent document 14] Japanese patent laid-open publication No. 2013-24982

[ patent document 15] U.S. Pat. No. 5,94686

[ patent document 16] Japanese patent laid-open publication No. 2016-148871

[ patent document 17] Japanese patent application laid-open No. 2004-86100

[ patent document 18] Japanese patent application laid-open No. 2013-64798

[ patent document 19] Japanese patent application laid-open No. 2004-251962

[ patent document 20] Japanese patent application laid-open No. 2001-033627

[ patent document 21] Japanese patent application laid-open No. 2001-290029

[ patent document 22] Japanese patent application laid-open No. 2010-072548

[ patent document 23] Japanese patent laid-open No. 2007 and 084803

[ patent document 24] Japanese patent laid-open No. 2007-238888.

[ non-patent document ]

[ non-patent document 1]

Application of functional pigment, release 1 edition, CMC (stock) publication, Jiangjiang Zhenghao, 98-100 pages

[ non-patent document 2]

Dye chemistry; thin field was plentiful 621 pages 1957.

Disclosure of Invention

[ problem to be solved by the invention ]

The present invention has been made in view of the above circumstances, and an object thereof is to provide a novel polarizing element, a polarizing plate, and an optical device.

[ means for solving the problems ]

As a result of diligent research directed toward solving the above-described problems, the present inventors have developed a novel polarizing element including a water-soluble compound or a salt thereof that absorbs light in the infrared region.

In one embodiment, the polarizing element of the present invention comprises iodine.

In one embodiment, the polarizing element of the present invention is fabricated by setting a specific transmittance.

In one embodiment, the polarizing element of the present invention contains a specific azo compound.

That is, the gist of the present invention is as follows.

Invention 1

A polarizing element comprising: at least 1 dichroic dye exhibiting polarization characteristics in the visible light region, and a water-soluble compound or salt thereof that absorbs light in the infrared region.

Invention 2

The polarizing element according to invention 1, wherein the water-soluble compound that absorbs light in the infrared region is an azo compound.

Invention 3

The polarizing element according to invention 2, wherein the azo compound is an azo compound represented by the following formula (1):

in the formula, Ai₁、Ai₂Each independently a hydrogen atom, an azo group, or the following formula (2) (wherein Ai is excluded)₁、Ai₂All are hydrogen atoms) are shown,

-NH-is bonded to both naphthalene rings at any of the combinations of a and a ', b and b', a and b ', b and a',

in the formula, Ri₁The substituted rings are independently a benzene ring in the absence of a ring shown by a dotted line and a naphthalene ring in the presence of a ring shown by a dotted line,

Ri₁each independently is a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms,

bi is each independently a phenyl group which may have a substituent or a naphthyl group which may have a substituent, the aforementioned substituents being a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms,

m represents an integer of 1 to 3,

when Bi has a hydroxyl group as a substituent, the hydroxyl group can form-O-Cu-O-with a copper atom in the hydroxyl group in the above formula (1).

Invention 4

The polarizing element according to any one of inventions 1 to 3, wherein formula (2) is represented by formula (3):

in the formula, is₁Substituted ring, Ri₁M is the same as formula (2) respectively,

the oxygen atom represented by the-O-bond forms-O-Cu-O-with the copper atom as-OH in the formula (1),

Ri₂is a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms.

Invention 5

The polarizing element according to any one of inventions 1 to 4, wherein the azo compound represented by the formula (1) is an azo compound represented by the following formula (4):

in the formula, Ri₃Is a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms,

m is the same as in formula (2).

Invention 6

The polarizing element according to any one of inventions 1 to 5, wherein at least 1 of the dichroic dyes is a compound represented by formula (5) or formula (6) or a salt thereof:

in the formula, Ab₁、Ab₂Each independently represents a substituted naphthyl group or a substituted phenyl group, at least 1 of the substituents being a hydrogen atom, a sulfo group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms and a sulfo groupA group, a carboxyl group, a nitro group, an amino group, or a substituted amino group,

Rb₁、Rb₂each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a sulfo group, or an alkoxy group having 1 to 4 carbon atoms and having a sulfo group,

in the formula, Ag₁Represents a substituted phenyl group or a substituted naphthyl group,

bg and Cg are each independently represented by the following formula (7) or the following formula (8), and at least one represents formula (7),

Xg₁represents 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,

in the formula, Rg₁Represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms and having a sulfo group,

k represents an integer of 0 to 2,

in the formula, Rg₂And Rg₃Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms and having a sulfo group.

Invention 7

The polarizing element according to any one of inventions 1 to 6, wherein at least 1 of the dichroic dyes is a compound represented by the following formula (9) or formula (10), a metal complex compound thereof, or a salt thereof:

in the formula, Ac₁Represents a phenyl group or a naphthyl group having at least 1 substituent selected from the group consisting of a sulfo group and a carboxyl group,

Rc₁₁to Rc₁₄Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms and having a sulfo group,

in the formula, Ac₂Represents a phenyl group or a naphthyl group having at least 1 substituent selected from the group consisting of a sulfo group and a carboxyl group,

Rc₂₁to Rc₂₅Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms and having a sulfo group,

Rc₂₆represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms and having a sulfo group,

Xc₂represents an amino group having at least 1 substituent selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a sulfo group, an alkylamino group having 1 to 4 carbon atoms, a hydroxyl group, an amino group, a substituted amino group, a carboxyl group, and a carboxyethylamino 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 benzoyl group which may have a substituent, or a benzoylamino group which may have a substituent,

p and q each independently represent an integer of 0 or 1.

Invention 8

The polarizing element according to any one of inventions 1 to 7, wherein at least 1 of the dichroic dyes is an azo compound represented by the following formula (11), a metal complex compound thereof, or a salt thereof, or an azo compound represented by the formula (12), or a salt thereof:

in the formula, Ab₁Represents a phenyl group or a naphthyl group having at least 1 substituent selected from the group consisting of a sulfo group and a carboxyl group,

Rb₁₁to Rb₁₄Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms and having a sulfo group, Rb₁₅And Rb₁₆Each independently represents an alkoxy group having 1 to 4 carbon atoms,

Xb₁represents an amino group which may have at least 1 substituent selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a sulfo group, an amino group, an alkylamino group having 1 to 4 carbon atoms, a hydroxyl group, a carboxyl group and a carboxyethylamino 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,

d represents 0 or 1;

in the formula, Ab₂Represents a phenyl group or a naphthyl group having at least 1 substituent selected from the group consisting of a sulfo group and a carboxyl group,

Rb₂₁represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms and having a sulfo group, Xb₂Represents an amino group which may have at least 1 substituent selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkylamino group having 1 to 4 carbon atoms, a hydroxyl group, a carboxyl group, a sulfo group, an amino group and a substituted amino 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.

Invention 9

The polarizing element according to any one of inventions 1 to 8, wherein at least 1 of the dichroic dyes is an azo compound represented by the following formula (13) or a salt thereof:

in the formula, Ay₁Represents a hydrogen atom, a sulfo group, a carboxyl group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms,

Ry₁and Ry₂Each independently represents a hydrogen atom, a sulfo group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms and having a sulfo group,

h is an integer of 1 to 3.

Invention 10

The polarizing element according to any one of inventions 1 to 9, wherein at least 1 of the dichroic pigments is iodine.

Invention 11

The polarizing element according to any one of claims 1 to 10, wherein the substrate is a polyvinyl alcohol resin film.

Invention 12

The polarizing element according to any one of inventions 1 to 11, wherein a degree of polarization is 99% or more.

Invention 13

The polarizing element according to any one of inventions 1 to 12, wherein in a transmittance determined in a state where 2 sheets of the polarizing element are stacked with their respective absorption axes parallel to each other,

the difference between the average transmittance at each wavelength of 520nm to 590nm and the average transmittance at each wavelength of 420nm to 480nm is 5% or less in absolute value, and the difference between the average transmittance at each wavelength of 600nm to 640nm and the average transmittance at each wavelength of 520nm to 590nm is 3% or less in absolute value.

Invention 14

The polarizing element according to any one of inventions 1 to 13, wherein the refractive index is measured in accordance with JIS Z8781-4: 2013 measuring the absolute values of a-value and b-value obtained when the transmittance of natural light is measured,

the number of the polarizing element monomers is 1 or less (-1. ltoreq. a.ltoreq. a-s.ltoreq.1, -1. ltoreq. b.ltoreq. s.ltoreq.1),

the state where 2 sheets of the above-mentioned polarizing elements are arranged in a stacked manner with their respective absorption axes parallel to each other is 2 or less (-2. ltoreq. a.ltoreq. a.ltoreq.p.ltoreq.2, -2. ltoreq. b.ltoreq. p.ltoreq.2),

(a represents a-s in the monomer, b represents b in the monomer, a-p represents a-p in the parallel position, b represents b in the parallel position.)

Invention 15

The polarizing element according to any one of inventions 1 to 14, wherein in a transmittance obtained in a state where 2 sheets of the polarizing element are stacked with their respective absorption axes orthogonal to each other,

the difference between the average transmittance at each wavelength of 520nm to 590nm and the average transmittance at each wavelength of 420nm to 480nm is 3% or less in absolute value, and the difference between the average transmittance at each wavelength of 600nm to 640nm and the average transmittance at each wavelength of 520nm to 590nm is 2% or less in absolute value.

Invention 16

A polarizing plate includes: the polarizing element according to any one of inventions 1 to 15, and a transparent protective layer provided on at least one surface of the polarizing element.

Invention 17

An optical device, comprising: the polarizing element according to any one of inventions 1 to 15 or the polarizing plate according to invention 16.

Invention 18

The polarizing device according to claim 17, which is a liquid crystal display device.

[ Effect of the invention ]

The polarizing element of the present invention has high polarization characteristics in the visible light region and absorbs light in the infrared region. In one embodiment, a wide band from the visible region to the infrared region has high polarization properties. In one embodiment, the polarizing element of the present invention can be used not only for a polarizing plate and a liquid crystal display device, but also for a sensor or a security device that functions with light from a visible light region to an infrared region, a camera that can detect light from a visible light region to an infrared region, and the like.

In one embodiment, the polarizing element of the present invention has high transmittance and high contrast ratio consistent with iodine-based polarizing plates, and also has high durability (moisture resistance, heat resistance, and/or light resistance), particularly high heat resistance.

In one embodiment, the polarizing element of the present invention has absorption in the infrared region while having high durability.

In one embodiment, the polarizing element of the present invention has a colorless color in the visible light region, has absorption in the infrared region, and has high durability.

Detailed Description

In the present specification, a water-soluble compound or a salt thereof that absorbs light in the infrared region may be simply referred to as "infrared light-absorbing water-soluble compound".

In the claims and the specification of the present application, since a "substituent" may contain a hydrogen atom, the hydrogen atom is sometimes described as a "substituent" for convenience. "may have a substituent" means that the case without a substituent is also included. For example, "phenyl group which may have a substituent" includes unsubstituted pure phenyl groups and phenyl groups having a substituent. In addition, "lower" in the present application, such as lower alkyl and lower alkoxy, means a carbon number of 1 to 4, preferably 1 to 3, unless otherwise specified.

Examples of the "lower (C1-C4) aliphatic hydrocarbon group" include straight-chain alkyl groups such as methyl, ethyl, n-propyl and n-butyl, branched alkyl groups such as sec-butyl and tert-butyl, and unsaturated hydrocarbon groups such as vinyl.

Examples of the "lower (C1-C4) alkoxy group" include methoxy, ethoxy, propoxy, n-butoxy, sec-butoxy and tert-butoxy groups.

In the present specification, the term "azo compound or a salt thereof" or "azo compound, a metal complex compound thereof, or a salt thereof" may be used in its entirety, and may be abbreviated as "azo compound".

[ polarizing element ]

The present invention relates to a polarizing element comprising at least 1 type of dichroic dye exhibiting polarization properties in the visible light region, and a water-soluble compound or a salt thereof that absorbs light in the infrared region.

As a dichroic dye exhibiting polarization characteristics in a visible light region, a compound composed of iodine and an iodine compound such as potassium iodide or lithium iodide is generally known, and as another 2-color dye, a dye described in non-patent document 1 is known. Specifically, the iodine-based polarizing plate is exemplified by patent documents 21 and 22, the dye-based polarizing plate is exemplified by patent documents 19 and 20, and the dichroic dye having a polarizing function in the visible light region is exemplified by patent documents 23 and 24 as long as the dye-based polarizing plate can control only the polarization of a specific wavelength. In particular, the use of the azo dyes described in the following formulae (5) to (14) is preferable because a colorless polarizing plate or a higher-performance polarizing plate can be obtained.

(Water-soluble Compound that absorbs light in the Infrared region)

The polarizing element of the present invention can be provided with high durability by using an infrared light absorbing water-soluble compound having a property of absorbing light in the near infrared region. The near infrared region is particularly preferable to use a dye having an absorption maximum at 700 to 1400 nm. More preferably, a dye having an absorption maximum is used at 700 to 1100nm, still more preferably at 700 to 1000m, particularly preferably at 700 to 900 nm.

Examples of the kind of the infrared light absorbing water-soluble compound include phthalocyanine compounds, naphthalocyanine compounds, metal complex compounds, boron complex compounds, cyanine compounds, squarylium compounds, diimmonium compounds, diphenylamine/triphenylamine compounds, quinone compounds, and azo compounds. In general, these dyes have a long absorption wavelength by extending an existing pi-conjugated system, and exhibit various absorption wavelengths based on their structures. Many of them take the form of hydrophobic dyes or pigments, but they can also be used as hydrophilic dyes by water-solubility.

The phthalocyanine group and the naphthalocyanine group are dyes having a planar structure and a wide pi-conjugated plane. By M of the formula (A-1)₁The central metal shows various absorptions, and examples of the central metal generally include Li, Na, K, Mg, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, Ag, Au, Zn, Cd, Hg, Al, Ga, In, Si, Ge, Sn, Pb, and Sb. Examples of the metal oxide include VO, GeO, TiO and the like. Examples of the metal hydroxide include Si (OH)₂、Cr(OH)₂、Sn(OH)₂AlOH, etc. Examples of metal halides are SiCl₂、VCl、VCl₂VOCl, FeCl, GaCl, ZrCl, AlCl, and the like. Of these, metal atoms such as Fe, Co, Cu, Ni, Zn, Al, and V, metal oxides such as VO, metal hydroxides such as AlOH, and the like are preferable, and metal oxides such as VO are more preferable. As the pigment, a pigment represented by the general formula 1 described in Japanese patent application laid-open No. 2-167791 can be usually used, and a water-soluble group can be added to dissolve the pigment in water.

The dye represented by the following general formula (A-1) is preferably a dye represented by the following compound example (A-1-1). The dotted aromatic ring in the general formula (A-1) may or may not be present. In the compound example (A-1-1), e and f each independently represent an integer of 0 to 12, and the sum of e and f is 0 to 12, and it is particularly preferable that e is 1 to 4 and f is 0.

(A-1)

(A-1-1)

Quinone is a dye having broad absorption, such as a dye represented by the following general formula (A-2). In the formula, Ar is more preferable₁、Ar₂The ring structure is preferably a cyclic structure composed of an aromatic ring or a heterocyclic ring, and the heterocyclic ring is more preferably used for absorbing a long wavelength. For example, JapaneseAn anthraquinone-based dye disclosed in JP-A-61-221264. The ring may have a substituent, and examples thereof include an amino group, a nitro group, a sulfo group, an alkyl group, an alkoxy group, an alkyl group having a sulfo group, an alkyl group having a hydroxyl group, and the like. X is preferably an oxygen atom or a nitrogen atom. When X is a nitrogen atom, the nitrogen atom represents NH which is a hydrogen adduct, an alkyl group having 1 to 4 carbon atoms, a nitrogen atom substituted with an optionally substituted phenyl group, or the like.

Many structures of quinone series exhibit hydrophobicity, but it has also been reported that water-solubility by imparting water-soluble groups is also reported. For example, indanthrene dyes described in Japanese patent application laid-open No. 2006-508034 can be cited.

The amino group which may have a substituent(s) represents a substituted or unsubstituted amino group, and examples of the substituted amino group include a mono-substituted amino group such as a monomethylamino group, a monoethylamino group, a monobutylamino group and a monophenylamino group, and a di-substituted amino group such as a dimethylamino group, a diethylamino group, a dibutylamino group, a diphenylamino group and a methylphenylamino group. Examples of the alkyl group include a straight-chain alkyl group such as a methyl group, an ethyl group, a propyl group, a n-butyl group and a n-octyl group, a branched-chain alkyl group such as an isopropyl group, a sec-butyl group and a tert-butyl group, and a cyclic alkyl group such as a cyclopentyl group and a cyclohexyl group. Examples of the alkoxy group include methoxy, ethoxy, propoxy, butoxy and the like. Examples of the alkyl group having a sulfo group include a sulfomethyl group, a sulfoethyl group, a sulfopropyl group, and a sulfobutyl group. Examples of the alkyl group having a hydroxyl group include a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, a hydroxybutyl group and the like.

The dye represented by the following general formula (A-2) is preferably a dye represented by the following compound example (A-2-1). In the compound example (A-2-1), n represents an integer of 1 to 12, and when n is 1 or more, each sulfo group may be in a free form, a salt form, or both a free form and a salt form in any ratio.

(A-2)

(A-2-1)

The cyanine dye is a dye having strong absorption in the near infrared region, and is represented by the general formula (A-3) or (A-4), Ar₃To Ar₆Represents a heterocycle. The heterocyclic ring may be exemplified by a thiazole ring, a benzothiazole ring, a naphthothiazole ring, a thiazoline ring, an oxazole ring, a benzoxazole ring, a naphthooxazole ring, an oxazoline ring, a selenazole ring, a benzoselenazole ring, a naphthoselenazole ring, a quinoline ring and the like, and a benzothiazole ring and a naphthothiazole ring are preferable. The individual heterocycles may each have an optional substituent, preferably an aqueous radical. Examples of the water-soluble group include a sulfo group, a hydroxyl group, an alkyl group having a sulfo group, an alkyl group having a hydroxyl group and the like. These substituents may be in Ar₃To Ar₆May be bonded to a nitrogen atom in the heterocycle. The number c of methylene chains in the general formula (A-3) is represented by an integer of 1 to 7, particularly preferably 3 to 5. The methylene chain may have a substituent R₄Examples thereof include phenyl groups which may have a substituent. In addition, c is more than 2 and R₄When plural, each R₄They may be the same or different. Ar in the general formula (A-4)₇The substituent W represents a cyclic skeleton having 5 to 7 carbon atoms, and examples thereof include halogen, a phenylamino group which may have a substituent, a phenoxy group which may have a substituent, a phenylthio group which may have a substituent, and the like. The substituent in this case may have a water-solubilizing group. In addition, the dye is an intramolecular salt type or an intermolecular salt type, and when the dye is an intermolecular salt type, examples thereof include organic salts such as a halide salt, a perchlorate salt, an antimony fluoride salt, a phosphorus fluoride salt, a boron fluoride salt, a trifluoromethanesulfonate salt, a bis (trifluoromethane) sulfonimide salt, and naphthalenesulfonic acid. Specific examples thereof include indocyanine green and water-soluble dyes described in Japanese patent application laid-open No. Sho 63-33477, and the following compounds (A-3-1) and (A-4-1) to (A-4-3) are exemplified. The alkyl group having a sulfo group and the alkyl group having a hydroxyl group may be the same as described above. Examples of the halogen include fluorine, chlorine, bromine, iodine, etc., and chlorine is preferred.

(A-3)

(A-4)

(A-3-1)

(A-4-1)

(A-4-2)

(A-4-3)

The squarylium acid having a structure similar to that of the cyanine system is a dye having a tetragonal acid as a central skeleton, represented by the following general formula (A-5). Ar in the general formula (A-5)₈、Ar₉It is preferable to have the same heterocyclic ring as the cyanine system. The dye also has an intramolecular salt form and an intermolecular salt form, and has the same salt form as the cyanine dye. The dye shows a large amount of hydrophobicity, but can be dissolved in water by providing a water-soluble group similarly to the cyanine system.

(A-5)

The azo series isDyes that absorb visible light in the visible light range and water-soluble inks are mainly used, and dyes that absorb near infrared light by making the absorption band wide are commercially available. Examples of the ink include C.I.acid Black2 (manufactured by Orient chemical industries, Ltd.) and C.I.direct Black 19 (manufactured by Aldrich industries, Ltd.) which are generally used for the purpose of manufacturing Black ink described in International publication No. 2013/035560. In addition, these azo dyes can form a complex with a metal. In this case, the central metal M is represented by the following general formula (A-6)₂Examples thereof include cobalt, nickel and the like, Ar₁₁、B₁Examples of the aromatic ring include a benzene ring and a naphthalene ring, and more specifically, the dye structure described in Japanese patent application laid-open No. 59-11385 is preferable.

(A-6)

The metal complex is represented by the following general formula (A-7) or the following general formula (A-8). M in the formula₃、M₄The metal is generally Pd, Ni, Co or Cu, but Ni is particularly preferred. R₇₁、R₇₂、R₈₁、R₈₂Examples of the substituent include a halogen atom, an alkyl group which may have a sulfo group, an alkoxy group which may have a sulfo group, a cyano group, an amino group, a nitro group, and a phenyl group which may have a substituent. X₁To X₄Each independently represents a nitrogen atom, an oxygen atom, or a sulfur atom. In addition, X₁To X₄When it is a nitrogen atom, the nitrogen atom may be a nitrogen atom substituted with NH which is a hydrogen adduct, an alkyl group having 1 to 4 carbon atoms, a phenyl group which may have a substituent, or the like.

(A-7)

(A-8)

The boron complex is a dye structure represented by the following general formula (A-9, preferably Japanese patent application laid-open No. 2010-106248).

(A-9)

In the above general formula (A-9), R₉₃、R₉₄Preferably hydrogen atom, alkyl group, phenyl group, R₉₅Being strong electron-withdrawing groups, e.g. nitro, cyano being preferred, Ar₉₀Phenyl which may have a substituent is preferable, Ar₁₂The cyclic structure is preferably an aromatic ring or a heterocyclic ring, and the heterocyclic ring is more preferably a heterocyclic ring for absorbing a long wavelength. Y is preferably a sulfur atom or an oxygen atom.

The diimine dye is a dye having absorption in a relatively long wavelength region (950 to 1100nm) even in the near infrared region, and is represented by the following general formula (A-10).

(A-10)

In the above general formula (A-10), R₆To R₁₃Examples thereof include an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and the like. Generally, a hydrophobic dye, but a dye as shown in Japanese patent laid-open No. 2001-181184, which imparts a water-soluble group, has also been disclosed. The dye is also of an intramolecular salt type, an intermolecular salt type, for example, in the case of an intermolecular salt type, Q-is exemplified by a halide ion, a perchlorate ion, an antimony fluoride ion, a phosphorus fluoride ion, a boron fluoride ion, a trifluoromethanesulfonate ion, a bis (trifluoromethanesulfonate) sulfonimide ion, a naphthalenesulfonate ion or the like. Examples of the alkyl group which may have a substituent include a halogen, a hydroxyl group, a cyano group, a substituted or unsubstituted amine group, a carboxyl group, a sulfo group, a phosphate group, a carboxyalkyl group, an alkoxy group, a phenoxy group, and the like, and a linear, branched or cyclic C1 to C8 alkyl group and the like.The halogen may be the same as described above. Examples of the substituted or unsubstituted amino group include an amino group, a methylamino group, a dimethylamino group, a dibutylamino group, a phenylamino group, and a diphenylamino group. Examples of the carboxyalkyl group include a methylcarboxyl group, an ethylcarboxyl group and the like. Examples of the alkoxy group include methoxy, ethoxy, butoxy, t-butoxy and the like.

The diphenylamine/triphenylamine is represented by the following general formula (A-11) or the following general formula (A-12).

R in the above general formula (A-11)₁₄To R₁₇R in the general formula (A-12)₁₈To R₂₃Each independently represents a hydrogen atom or an alkyl group having at least 1 carbon atom, wherein the alkyl group contains 1 or more hetero atoms selected from a nitrogen atom, an oxygen atom, a sulfur atom and a halogen atom, and 1 or more nitrogen atoms are cationic radicals, and the 1 or more cationic radicals are charge-balanced by 1 or more anions.

The infrared-absorbing water-soluble compound is preferably an azo compound or a salt thereof.

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

By containing the azo compound represented by the above formula (1) or a salt thereof in the polarizing element of the present invention, very high durability can be imparted. In addition, a polarizing element which provides high polarization over a wide wavelength range in the infrared region can be obtained. Regarding general dye-based polarizing elements, for example, patent documents 19 and 20 can provide a polarizing element exhibiting a high degree of polarization in the visible light region, but cannot provide a polarizing element having polarization in the infrared region, and also has a problem that the light transmittance in the durability test is greatly changed from 680nm to a long wavelength region, and a polarizing plate is changed in color, for example, becomes red after the durability test. In view of this problem, the use of the azo compound represented by formula (1) is highly preferred because a polarizing element having both higher durability and a polarizing function in a wide band can be obtained.

In the above formula (1), Ai₁、Ai₂Each independently represents a hydrogen atom, an azo group, or the above formula (2) (excluding Ai)₁、Ai₂All are hydrogen atoms), Ai₁、Ai₂More preferably, they are each represented by the formula (2). Further, -NH-is any one of combinations of a and a ', b and b', a and b ', and b and a', and a 'are preferably a combination of a and a'.

In the above formula (2), Ri₁The substituted rings are independently benzene rings in the absence of a ring represented by a dotted line, and naphthalene rings in the presence of a ring represented by a dotted line. Ri₁Each independently represents a substituent selected from the group consisting of a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having a sulfo group, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms.

Examples of the alkyl group having 1 to 4 carbon atoms include a straight-chain alkyl group such as a methyl group, an ethyl group, a propyl group, or an n-butyl group, and a chain alkyl group such as a sec-butyl group or a tert-butyl group. The alkoxy group having 1 to 4 carbon atoms is exemplified by methoxy, ethoxy, propoxy, butoxy and the like. Examples of the alkyl group having a sulfo group and having 1 to 4 carbon atoms include a sulfomethyl group, a sulfoethyl group, a sulfopropyl group, a sulfobutyl group and the like. Examples of the alkyl group having 1 to 4 carbon atoms and a hydroxyl group include hydroxymethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl and the like.

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

In the above formula (2), Bi each independently represents a phenyl group which may have a substituent or a naphthyl group which may have a substituent.

The substituent that the phenyl group and the naphthyl group may have represents a substituent selected from the group consisting of a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms.

When Bi in the above formula (2) has a hydroxyl group as a substituent, the hydroxyl group in the formula (1) may form an-O-Cu-O-linkage with a copper atom, and may be an azo metal complex compound or a salt thereof.

In the above formula (2), m represents an integer of 1 to 3, preferably 1 or 2, more preferably 2.

When Bi is a phenyl group having a substituent, the substitution position is not particularly limited, but a combination of the 2-position and the 4-position, the 2-position and the 5-position, or the 3-position and the 5-position is preferable, and the 2-position and the 4-position are particularly preferable. When Bi is a naphthyl group which may have a substituent, the substitution position is not particularly limited, but the 2-position, 6-position, 7-position, a combination of the 2-position and 6-position, and the 2-position and 7-position are preferable, and the 2-position, 2-position and 7-position are particularly preferable. Ai in formula (1)₁、Ai₂Each independently a hydrogen atom, or a compound of formula (2) with the proviso that Ai is excluded₁、Ai₂All being hydrogen atoms, a combination of a hydrogen atom and formula (2), or Ai₁、Ai₂All preferably in a combination of the formula (2), Ai₁、Ai₂The combination of the formula (2) is particularly preferable.

When the formula (2) is represented by the formula (3), the durability of the polarizing element of the present invention can be further improved, and the polarization performance in the infrared region can be improved, which is preferable. In the above formula (3), Ri₁Is the same as Ri of the above formula (2)₁The same is true.

In the above formula (3), Ri₂Represents a group selected from a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms and having a sulfo group, an alkyl group having 1 to 4 carbon atoms and having a hydroxyl group, an alkyl group having 1 to 4 carbon atoms and having a carboxyl group, an alkyl group having a sulfo groupAn alkoxy group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms and a carboxyl group, and an alkoxy group having 1 to 4 carbon atoms. Ri in formula (3)₂The substitution position (2) may be ortho, meta or para with respect to the substitution position of the oxygen atom, but substitution into para is preferred. Further, it is preferable that the oxygen atom in the formula (3) and-OH in the formula (1) and the copper atom form-O-Cu-O-. The azo compound represented by the formula (1) is more preferable because it can provide a polarizing element for infrared region having higher performance and a wide band region by the formula (4). In the formula (4), m is the same as the above formula (2), and Ri₃Can be combined with Ri in formula (3)₂Same for Ri₃Is also substituted with Ri₂The same is true.

The azo compounds represented by the formulae (1) to (4) may be in the form of a free form or a salt. The salt may be, for example, an alkali metal salt such as a lithium salt, a sodium salt, and a potassium salt, an alkaline earth metal salt such as a calcium salt, an organic salt such as an ammonium salt or an alkylamine salt, and a sodium salt is more preferable.

Specific examples of the azo compound represented by the above formula (1) are as follows, but not particularly limited thereto. In the formula, sulfo, carboxyl and hydroxyl are represented as free acids.

The azo compound represented by the above formula (1) or a salt thereof can be produced by diazotization and coupling according to a usual production method of an azo dye described in, for example, patent document 14, patent document 15, and non-patent document 2.

Specific examples of the production method include the following methods. For example, aminothiazoles represented by the following formula (A) are diazotized, anilines represented by the following formula (B) or aminonaphthalenes represented by the following formula (C) are coupled at once, and a monoazo amino compound represented by the following formula (D) or (E) is obtained.

The bisazo amino compound (D) or (E) is each Ai₁Component or Ai₂Diazotizing the component (A) to secondarily couple naphthols represented by the following formula (F) to obtain azo compounds represented by the formula (1).

In the above formulae (A) to (F), in Ri₁And Ri₁The presence or absence of a dotted line in the substituted ring indicates the same meaning as in formula (2), Ri₂Represents the same meaning as in formula (3), R₂₄Or R₂₅Each independently represents a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having a sulfo group, an alkoxy group having 1 to 4 carbon atoms, an alkoxy group having a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy group having a carboxyl group, and m represents the same meaning as in formula (2).

The alkyl group having 1 to 4 carbon atoms, the alkoxy group having 1 to 4 carbon atoms, the alkyl group having 1 to 4 carbon atoms of a sulfo group, the alkyl group having 1 to 4 carbon atoms of a hydroxyl group, the alkyl group having 1 to 4 carbon atoms of a carboxyl group, the alkoxy group having 1 to 4 carbon atoms of a sulfo group, the alkoxy group having 1 to 4 carbon atoms of a hydroxyl group, and the alkoxy group having 1 to 4 carbon atoms of a carboxyl group may be respectively the same as described above.

In the above-mentioned production method, the diazotization step is preferably carried out by a so-called "cis method" in which a nitrite such as sodium nitrite is mixed in an aqueous solution or suspension of a diazo component in an inorganic acid such as hydrochloric acid or sulfuric acid, or by a so-called "reverse method" in which a nitrite is added in advance to a neutral or weakly alkaline aqueous solution of a diazo component and then the mixture is mixed with an inorganic acid. The temperature of the diazotization is suitably from-10 to 40 ℃. In addition, the aniline coupling step is preferably carried out under acidic conditions of-10 to 40 ℃ and pH2 to 7 by mixing an acidic aqueous solution such as hydrochloric acid or acetic acid with each of the above diazo solutions.

The monoazo compound of the formula (D) or the formula (E) obtained by the coupling reaction may be directly filtered, or may be separated out by acid precipitation or salt precipitation and filtered, or may be directly subjected to the following step as a solution or suspension. When the diazonium salt is rendered insoluble to form a suspension, it may be filtered to form a cake and used in the following coupling step.

The tertiary coupling reaction of the diazotized monoazo compound of the formula (D) or the formula (E) with the naphthol represented by the formula (F) is preferably carried out at a temperature of-10 to 40 ℃ under neutral to alkaline conditions at a pH of 7 to 10. After the reaction is terminated, the azo compound or salt of formula (1) obtained is preferably removed by salting out and filtration. In addition, when purification is required, salting out may be repeated or precipitation from water may be performed by using an organic solvent. Examples of the organic solvent used for purification include water-soluble organic solvents such as alcohols such as methanol and ethanol, and ketones such as acetone.

When the compound represented by the above formula (A) does not have a ring represented by a dotted line, it is a 2-aminobenzothiazole, and examples thereof include 2-amino-6-sulfobenzothiazole, 2-amino-7-methoxy-6-sulfobenzothiazole, 2-amino-4, 6-disulfobenzothiazole, and 2-amino-7-methoxy-4, 6-disulfobenzothiazole. When a ring represented by a dotted line is present, it is a 2-aminonaphthothiazole, and examples thereof include 2-amino-6, 8-disulfonaphthothiazole, 2-amino-4, 6, 8-trisulfonaphthothiazole, 2-amino-4-chloro-6, 8-disulfonaphthothiazole, 2-amino-6-sulfopropoxy-4, 7, 8-trisulfonaphthothiazole, 2-amino-6-methoxy-4, 7, 8-trisulfonaphthothiazole, 2-amino-7-sulfopropoxy-4, 9-disulfonaphthothiazole, 2-amino-4-sulfopropoxy-5, 7, 9-trisulfonaphthothiazole, etc., preferably 2-amino-6-sulfobenzothiazole, 2-amino-7-methoxy-6-sulfobenzothiazole, 2-amino-6, 8-disulfonaphthothiazole.

The aniline of the formula (B) is an aniline having a lower alkoxy group and having a sulfo group, and examples thereof include 3- (2-amino-4-methylphenoxy) propane-1-sulfonic acid, 3- (2-aminophenoxy) propane-1-sulfonic acid, and 3- (2-amino-4-methylphenoxy) butane-1-sulfonic acid. Examples of the aniline include aniline, 2-methylaniline, 3-methylaniline, 2-ethylaniline, 3-ethylaniline, 2, 5-dimethylaniline, 2, 5-diethylaniline, 2-methoxyaniline, 3-methoxyaniline, 2-methoxy-5-methylaniline, 2, 5-dimethoxyaniline, 3, 5-dimethylaniline, 2, 6-dimethylaniline and 3, 5-dimethoxyaniline. These anilines are protected amine groups. The aminonaphthalenes of the formula (C) may be exemplified by 1-aminonaphthalene, 1-aminonaphthalene-6-sulfonic acid, 1-aminonaphthalene-7-sulfonic acid, 1-amino-2-methoxynaphthalene-6-sulfonic acid, 1-amino-2-methoxynaphthalene-7-sulfonic acid, 1-amino-2-ethoxynaphthalene-6-sulfonic acid, and 1-amino-2-ethoxynaphthalene-7-sulfonic acid, with 1-aminonaphthalene-7-sulfonic acid and 1-amino-2-methoxynaphthalene-7-sulfonic acid being more preferred. These aminonaphthalenes are protected amine groups. Examples of protecting groups include the omega-methylsulfonyl group.

The azo compound represented by the above formula (1) or a salt thereof is a polarizing plate which provides high polarizing performance in the infrared region and high performance having moisture resistance, heat resistance, and/or light resistance. Therefore, the polarizing element according to the present invention is suitable for manufacturing various sensors that are used under high-temperature and high-humidity conditions, such as a polarizing plate for vehicles, a neutral gray polarizing plate for outdoor display, and light control in the infrared region.

In the above-described polarizing element, at least 1 type of dichroic dye exhibiting polarization characteristics in the visible light region is used for the purpose of color correction and/or improvement of polarization performance to the extent that the performance of the present invention is not impaired. For example, at least 1 type of dichroic dye that exhibits polarization properties in a visible light region other than the azo compound represented by formula (1) may be contained.

In the production of a colorless polarizing element, the polarizing element of the present invention preferably contains one or both of the azo compounds of the formula (5) or (6) or salts thereof. The formulation provides a high transmittance, even high polarization, but colorless polarizer. A polarizing element comprising the azo compound of the formula (5) or (6) can provide a highly durable and highly reliable liquid crystal display.

First, the following describes equation (5). In formula (5), Ab₁、Ab₂Each independently represents a substituted naphthyl group or a substituted phenyl group, at least 1 of the substituents being a hydrogen atom, a sulfo group, a lower alkyl group, a lower alkoxy group having a sulfo group, a carboxyl group, a nitro group, an amino group, or a substituted amino group, Rb₁、Rb₂Each 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.

Further, in order to obtain a polarizing element having a higher transmittance and a high degree of polarization and having a more achromatic hue in the parallel and orthogonal phases, Rb of formula (5) is more preferable₁、Rb₂The substituents of (a) are each independently methyl or methoxy, with methoxy being more preferred.

Further, in order to obtain a polarizing element having a higher transmittance and a high degree of polarization and having a more achromatic hue in the parallel and orthogonal phases, Rb of formula (5) is more preferable₁、Rb₂Naphthyl groups each independently having a sulfo group or a carbonyl group, and naphthyl groups having a sulfo group are more preferable for obtaining a polarizing plate of high contrast.

Specific examples of the azo compound represented by the formula (5) used herein are shown below in the form of a free acid.

Next, the compound of the formula (6) will be described.

In formula (6), Ag₁Represents a substituted phenyl group or a substituted naphthyl group. Ag₁In the case of a phenyl group, it is preferable that at least 1 sulfo group or carboxyl group is contained as a substituent. When the phenyl group has 2 or more substituents, at least 1 of the substituents is a sulfo group or a carboxyl group, and the other substituents are preferably a sulfo group, a carboxyl group, a lower alkyl group, a lower alkoxy group having a sulfo group, a nitro group, an amino group, an acetylamino group, or an amino group substituted with a lower alkylamino group. The other substituent is more preferably a sulfo group, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a carboxyl group, a nitro group, or an amine group, and particularly preferably a sulfo group, a methyl group, a methoxy group, an ethoxy group, or a carboxyl 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 an alkoxy terminal, more preferably 3-sulfopropoxy and 4-sulfobutoxy, particularly preferably 3-sulfopropoxy. The number of substituents of the phenyl group is preferably 1 or 2, and the substitution position is not particularly limited, but only the 4-position, the combination of the 2-position and the 4-position, and the combination of the 3-position and the 5-position are preferable.

Ag₁In the case of a substituted naphthyl group, the substituent preferably has at least 1 sulfo group. When the naphthyl group has 2 or more substituents, it is more preferable that at least 1 of the substituents is a sulfo group, and the other substituents are a sulfo group, a hydroxyl group, a carboxyl group, or a lower alkoxy group having a sulfo group. The naphthyl group particularly preferably has 2 or more sulfo groups as substituents. The lower alkoxy group having a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably an alkoxy group terminal. More preferred are 3-sulfopropoxy and 4-sulfobutoxy, and particularly preferred is 3-sulfopropoxy. When the number of sulfo groups contained in the naphthyl group is 2, the substitution position of the sulfo group is more preferably 4,The combination of 8 bits and the combination of 6 and 8 bits are preferable, and the combination of 6 and 8 bits is more preferable. When the number of sulfo groups contained in the naphthyl group is 3, the substitution position of the sulfo group is preferably a combination of 1,3 and 6 positions.

Bg and Cg in the formula (6) are each independently represented by the following formula (7) or the following formula (8), but at least one of Bg and Cg is represented by the following formula (7).

In the above formulas (7) and (8), Rg₁To Rg₃Each independently represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a lower alkoxy group having a sulfo group. In the formula (7), Rg₁More preferred is a hydrogen atom, a lower alkyl group, or a lower alkoxy group, still more preferred is a hydrogen atom, a methyl group, or a methoxy group, and particularly preferred is a hydrogen atom or a methoxy 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 an alkoxy terminal. More preferred are 3-sulfopropoxy and 4-sulfobutoxy, and particularly preferred is 3-sulfopropoxy. Rg (Rg)₁The substitution position of (A) is Ag₁When the azo group on the side is the 1-position, the 2-position or 3-position is preferred. More preferably Ag₁When the azo group on the side is the 1-position, the 3-position is more preferable. When a sulfo group is present, the substitution position of the sulfo group is preferably the 6-or 7-position, more preferably the 6-position. k represents an integer of 0 to 2. In the formula (8), Rg₂Or and Rg₃Each independently is 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. Rg (Rg)₂Or Rg₃Is Xg at the substitution position₁When the azo group on the side is 1-position, a combination of only 2-position, only 5-position, 2-position and 5-position, 3-position and 5-position, 2-position and 6-position, or 3-position and 6-position may be applied, and only 2-position, only 5-position, 2-position and 5-position are more preferable.

Xg in the above formula (6)₁Represents 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 benzene which may have a substituentA formylamino group. Xg₁More preferred is an amino group which may have a substituent or a phenylamino group which may have a substituent, and still more preferred is a phenylamino group. The amino group which may have a substituent is more preferably an amino group having 1 or 2 hydrogen atoms, methyl groups, methoxy groups, sulfo groups, amino groups, and lower alkylamino groups, and still more preferably an amino group having 1 or 2 hydrogen atoms, methyl groups, sulfo groups. The phenylamino group which may have a substituent is more preferably a phenylamino group having 1 or 2 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, and still more preferably a phenylamino group having 1 or 2 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 1 of the substituents is preferably the p-position with respect to the amino group of the phenylamino group. The phenylazo group is preferably a phenylazo group having 1 to 3 groups selected from the group consisting of a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an amino group, a hydroxyl group and a carboxyethylamino group. The benzoylamino group which may have a substituent is more preferably a benzoylamino group having 1 substituent selected from the group consisting of a hydrogen atom, a hydroxyl group, an amino group, and a carboxyethylamino group. Xg₁When the substitution position of (2) is the 1-position of the hydroxyl group of the substituted naphthyl group, the 6-position or the 7-position is preferred, and the 6-position is more preferred.

The azo compound represented by the formula (6) or a salt thereof is particularly preferable for improving the performance, and the azo compound represented by the following formula (6') or a salt thereof is preferable.

In the above formula (6'), Ag₁Represents a substituted phenyl group or a substituted naphthyl group, Rg₄And Rg₅Each independently represents Rg in the formula (7)₁In the same sense, Xg₁Xg in the formula (6)₁Are the same meaning. k is a radical of₁And k₂Each independently represents an integer of 0 to 2.

Specific examples of the azo compound represented by the formula (6) are illustrated by

C.I.Direct Blue 34、

C.I.Direct Blue 69、

C.I.Direct Blue 70、

C.I.Direct Blue 71、

C.I.Direct Blue 72、

C.I.Direct Blue 75、

C.I.Direct Blue 78、

C.I.Direct Blue 81、

C.I.Direct Blue 82、

C.I.Direct Blue 83、

C.I.Direct Blue 186、

C.I.Direct Blue 258、

Benzo Fast Chrome Blue FG(C.I.34225)、

Benzo Fast Blue BN(C.I.34120)、

C.I.Direct Green 51

And azo compounds.

Specific examples of the azo compound represented by the formula (6) are shown below as a free acid.

In the polarizing element of the present invention, the content of the azo compound represented by formula (5) or formula (6) or a salt thereof is preferably 0.0001 to 5 parts by mass, more preferably 0.001 to 1 part by mass, relative to 100 parts by mass of the aqueous solution.

The method for obtaining the azo compound represented by the formula (5) and the azo compound can be obtained, for example, by the method described in international publication No. 2012/165223, but are not limited thereto.

The azo compound represented by the formula (6) or a salt thereof can be synthesized, for example, by the methods described in, but not limited to, Japanese patent application laid-open Nos. 1-161202, 01-172907, 01-248105, 01-265205, and 07-92531.

In one embodiment, the polarizing element of the present invention comprises an azo compound represented by the above formula (9) or formula (10), a metal complex compound thereof, or a salt thereof. When the above-mentioned polarizing element is produced, it is preferable to use the infrared light absorbing compound and the azo compound of the formula (9) or the formula (10) independently or simultaneously, respectively, and a colorless polarizing element can be provided although the transmittance is high and the polarization degree is high. In particular, a polarizing element using the azo compound of formula (9) or (10) can provide a liquid crystal display having high durability and high reliability.

First, the following will describe the formula (9).

In the above formula (9), Ac₁Represents a phenyl group or a naphthyl group having at least 1 substituent selected from the group consisting of a sulfo group and a carboxyl group, Rc₁₁To Rc₁₄Each independently represents a hydrogen atom, a lower alkyl group, a lower alkoxy group or a lower alkoxy group having a sulfo group.

In the above formula (9), Ac₁In the case of a phenyl group, it is more preferable to have at least 1 sulfo group or carboxyl group as a substituent thereof. When the phenyl group has 2 or more substituents, at least 1 of the substituents is sulfo or carboxyl, and the other substituents are preferably selected from the group consisting of sulfo, carboxyl, lower alkyl, lower alkoxy having sulfo, nitro, amino, acetylamino and amino substituted with lower alkylamino, more preferably from the group consisting of sulfo, methyl, ethyl, methoxy, ethoxy, carboxyl, nitro and amino, and particularly preferably from the group consisting of sulfo, methyl, ethyl, methoxy, ethoxy, carboxyl, nitro and aminoIs selected from the group consisting of sulfo, methyl, methoxy, ethoxy and carboxyl. The lower alkoxy group having a sulfo group is more preferably a linear alkoxy group, and the substitution position of the sulfo group is more preferably a terminal of the alkoxy group. Such a lower alkoxy group having a sulfo group is more preferably 3-sulfopropoxy or 4-sulfobutoxy, particularly preferably 3-sulfopropoxy. When the phenyl group has a sulfo group as a substituent, the number of the sulfo groups is preferably 1 or 2. The substitution position of the sulfo group is not particularly limited, but when the sulfo group is 1, the azo group is at the 1-position, preferably at the 4-position of the phenyl group, and when the sulfo group is 2, the combination of the 2-and 4-positions of the phenyl group or the combination of the 3-and 5-positions of the phenyl group is more preferred.

In the above formula (9), Ac₁In the case of a naphthyl group, it is more preferable to have at least 1 sulfo group as a substituent thereof. When the naphthyl group has 2 or more substituents, at least 1 of the substituents is a sulfo group, and the other substituents are preferably selected from the group consisting of a sulfo group, a hydroxyl group, a carboxyl group and 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 more preferably a terminal of the alkoxy group. Such a lower alkoxy group having a sulfo group is more preferably 3-sulfopropoxy or 4-sulfobutoxy, particularly preferably 3-sulfopropoxy. When the number of sulfo groups substituted by a naphthyl group is 2, the position of the azo group is the 2-position, and the substitution position of the sulfo group is preferably a combination of the 4-, 8-positions or a combination of the 6-, 8-positions of the naphthyl group, more preferably a combination of the 6-, 8-positions. When the number of sulfo groups substituted by a naphthyl group is 3, the substitution position of the sulfo group is more preferably a combination of 1-, 3-, and 6-positions.

In the above formula (9), Rc₁₁To Rc₁₄Each 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 more preferably a linear alkoxy group, and the substitution position of the sulfo group is more preferably a terminal of the alkoxy group. Rc (Rc)₁₁To Rc₁₄More 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. Is Rc (r) coated with₁₁To Rc₁₄Substituted benzenesWhen the substitution position of the group is the 1-position of the azo group on the ureido skeleton side, the phenyl group is preferably the only 2-position, the only 5-position, the combination of the 2-position and the 6-position, the combination of the 2-position and the 5-position, the combination of the 3-position and the 5-position, and particularly preferably the only 2-position, the only 5-position, the combination of the 2-position and the 5-position. In addition, only the 2-position and only the 5-position are Rc₁₁And Rc₁₂、Rc₁₃And Rc₁₄Meaning Rc₁₁And Rc₁₂Or Rc₁₃And Rc₁₄Either of which has a substituent other than 1 hydrogen atom only at the 2-position or 5-position, and the other is a hydrogen atom.

Among the azo compounds represented by the above formula (9), in particular, the azo compound represented by the following formula (9b) is preferable:

in the formula, Ac₁、Rc₁₁To Rc₁₄As defined above for formula (9). By using such an azo compound, the polarizing performance of the polarizing element can be further improved.

Specific examples of the azo compound represented by the above formula (9) include the following compounds.

The azo compound represented by the above formula (9) can be synthesized, for example, by the method described in Japanese patent laid-open publication No. 2009-155364 or a method similar thereto, but is not limited thereto. For example, the azo compound represented by the above formula (9) can be produced by reacting a compound to be a base material represented by the below-described formula (9-v) with a ureidoing agent such as phenyl chlorocarbonate at 20 to 95 ℃. As another synthetic method for ureidoization, a method of ureidoizing an amine compound using a phosgene compound or the like is known. By this synthesis method, the azo compound represented by formula (9) in the present invention having a ureido skeleton can be obtained.

The specific synthesis method of the azo compound represented by the above formula (9) is explained below. First, an amine having a substituent represented by the following formula (9-i) is diazotized by the same production method as that described in Toyota rich, "dye chemistry", Techno, 1957, P.135-234, and then coupled with an aniline represented by the following formula (9-ii), thereby obtaining a monoazo amino compound represented by the following formula (9-iii).

In the formula (9-i), Ac₁Ac of the above formula (9)₁The same meaning is true. In the formula (9-ii), Rc₁₁And Rc₁₂Represents Rc in the above formula (9)₁₁And Rc₁₂Are the same in each case. In the formula (9-iii), Ac₁Ac represented by the above formula (9)₁In the same sense, Rc₁₁And Rc₁₂Represents Rc in the above formula (9)₁₁And Rc₁₂Are the same in each case.

Then, the monoazo amino compound represented by the above formula (9-iii) is diazotized, and further coupled 2 times with anilines represented by the following formula (9-iv), to obtain a disazo amino compound represented by the following formula (9-v). In the formula (9-iv), Rc₁₃And Rc₁₄Represents Rc in the above formula (9)₁₃And Rc₁₄Are the same in each case. In the formula (9-v), Ac₁Ac represented by the above formula (9)₁Are in the same sense, Rc₁₁To Rc₁₄Is represented by the formula(9) Rc in (A)₁₁And Rc₁₄Are the same in each case.

The diazotization step in the above reaction process is carried out by a forward method in which a diazo component is mixed with a nitrite such as sodium nitrite in an aqueous solution or suspension of an inorganic acid such as hydrochloric acid or sulfuric acid, or by a reverse method in which a diazo component is previously added to a neutral or weakly alkaline aqueous solution and then mixed with an inorganic acid. The temperature of the diazotization is suitably from-10 to 40 ℃. In addition, the step of coupling with anilines is carried out by mixing an acidic aqueous solution such as hydrochloric acid or acetic acid with each of the above diazo solutions under acidic conditions of-10 to 40 ℃ and pH2 to 7.

The monoazo amino compound or disazo amino compound obtained in the coupling step may be isolated directly or by precipitation by acid precipitation or salt precipitation and filtered, or the solution or suspension may be subjected directly to the further step. When the diazonium salt is a sparingly soluble suspension, the suspension may be filtered and the filtered diazonium salt may be used in a further coupling step as a cake.

The bisazo amino compound obtained in the above step is then subjected to a urethanization reaction with phenyl chlorocarbonate to synthesize an azo compound represented by the above formula (9). The urethanization reaction is carried out under neutral to alkaline conditions at a temperature of 10 to 90 ℃ and a pH of 7 to 11 by, for example, a method of preparation described in Japanese patent laid-open No. 2009-155364. After termination of the urethanization reaction, the azo compound obtained by salting out was precipitated and then filtered. When purification is required, the salting out may be repeated or the azo compound obtained from water may be precipitated by using an organic solvent. Examples of the organic solvent used for purification include water-soluble organic solvents such as alcohols such as methanol and ethanol, and ketones such as acetone. In this manner, the azo compound represented by the above formula (9) used in the present invention can be synthesized.

Next, the following describes the formula (10).

In the above formula (10), Ac₂Represents a phenyl group or a naphthyl group having at least 1 substituent selected from the group consisting of a sulfo group and a carboxyl group. Rc (Rc)₂₁To Rc₂₅Each independently represents a hydrogen atom or lowerAlkyl, lower alkoxy or lower alkoxy having a sulfo group. Rc (Rc)₂₆Represents a hydrogen atom, a lower alkyl group or a lower alkoxy group having a sulfo group. Xc₂Represents an amino group which may have at least 1 substituent, a phenylazo group which may have at least 1 substituent, a naphthotriazole group which may have at least 1 substituent, or a benzoylamino group which may have at least 1 substituent, the substituents being selected from the group consisting of a lower alkyl group, a lower alkoxy group, a sulfo group, a lower alkylamino group, a hydroxyl group, an amino group, a substituted amino group, a carboxyl group, and a carboxyethylamino group. p and q each independently represent an integer of 0 or 1.

In the above formula (10), Ac₂Represents a substituted phenyl group or a substituted naphthyl group, provided that Ac₂In the case of a substituted phenyl group, it is more preferable that the phenyl group has at least 1 sulfo group or carboxyl group as a substituent, and when the phenyl group has at least 2 or more substituents, at least 1 of these substituents is a sulfo group or a carboxyl group, and the other substituents are preferably a sulfo group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having a sulfo group, a hydroxyl group, a nitro group, an amino group, or a substituted amino group (particularly, an acetylamino group or an alkylamino group having 1 to 4 carbon atoms), and the other substituents are more preferably a sulfo group, a carboxyl group, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a hydroxyl group, a nitro group, or an amino group, and particularly preferably a sulfo group, a carboxyl group, a methyl group, a methoxy group, or an ethoxy group. The alkoxy group having a sulfo group and 1 to 4 carbon atoms is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably an alkoxy terminal. The alkoxy group having a sulfo group and having 1 to 4 carbon atoms 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 position of the substituent on the phenyl group is not particularly limited, but is 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.

In the above formula (10), Ac₂In the case of a substituted naphthyl group, it is more preferable that the naphthyl group has at least 1 sulfo group as a substituent, and in the case of a naphthyl group having 2 or more substituents, at least 1 of these substituents is a sulfo group, and it is more preferable that the other substituent is a sulfo groupA hydroxyl group, a carboxyl group, or an alkoxy group having a sulfo group and having 1 to 4 carbon atoms. The alkoxy group having 1 to 4 carbon atoms and a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is more preferably an alkoxy terminal. The alkoxy group having a carbon number of 1 to 4 of a sulfo group is more preferably a 3-sulfopropoxy group or a 4-sulfobutoxy group, and particularly preferably a 3-sulfopropoxy group. When the number of the sulfo groups on the naphthyl group is 2, the substitution position of the azo group is the 2-position, and the substitution position of the sulfo group is more preferably a combination of the 4-position and the 8-position or a combination of the 6-position and the 8-position, particularly preferably a combination of the 6-position and the 8-position. When the number of sulfo groups on the naphthyl group is 3, the substitution position of the sulfo group is particularly preferably the substitution position of the azo group is the 2-position and a combination of the 1-position, the 3-position and the 6-position.

In the above formula (10), Xc₂Represents an amine group which may have at least 1 substituent, a phenylamino group which may have at least 1 substituent, a phenylazo group which may have at least 1 substituent, a naphthotriazole group which may have at least 1 substituent, a benzoyl group which may have at least 1 substituent, or a benzoylamine group which may have at least 1 substituent, and more preferably, for example, 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 benzoylamine group which may have a substituent, and particularly preferably, Xc₂Is 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. The above-mentioned substituent is selected from the group consisting of lower alkyl, lower alkoxy, sulfo, lower alkylamino, hydroxy, amino, substituted amino, carboxy, and carboxyethylamino.

Xc₁In the case of an amino group which may have at least 1 substituent, the amino group may be unsubstituted, but it is more preferably 1 or 2 substituents selected from the group consisting of lower alkyl, lower alkoxy, sulfo, amino, substituted amino, and lower alkylamino, and still more preferably 1 or 2 substituents selected from the group consisting of methyl, methoxy, sulfo, amino, and lower alkylamino.

Xc₁Is a phenylamino group which may have at least 1 substituentWhen the phenylamino group is unsubstituted, or, more preferably, has 1 or 2 substituents selected from the group consisting of lower alkyl, lower alkoxy, sulfo, amino and lower alkylamino, and, still more preferably, has 1 or 2 substituents selected from the group consisting of methyl, methoxy, sulfo and amino.

Xc₁When it is a phenylazo group which may have at least 1 substituent, the phenylazo group is unsubstituted, or more preferably has 1 to 3 substituents selected from the group consisting of a hydroxyl group, a lower alkyl group, a lower alkoxy group, an amine group and a carboxyethylamino group, and still more preferably has 1 to 3 substituents selected from the group consisting of a methyl group, a methoxy group, an amine group and a hydroxyl group.

Xc₁When it is a naphthotriazolyl group which may have at least 1 substituent, the naphthotriazolyl group is unsubstituted, or more preferably has 1 or 2 substituents selected from the group consisting of a sulfo group, an amine group and a carboxyl group, and still more preferably has 1 or 2 sulfo groups as substituents.

Xc₁In the case of a benzoylamino group which may have at least 1 of the above-mentioned substituents, the benzoylamino group is unsubstituted or more preferably has 1 substituent selected from the group consisting of a hydroxyl group, an amino group and a carboxyethylamino group, and still more preferably has 1 or 2 hydroxyl groups or amino groups as substituents.

Xc₁When it is a benzoyl group which may have at least 1 substituent, the benzoyl group is unsubstituted, or more preferably has 1 substituent selected from the group consisting of a hydroxyl group, an amine group and a carboxyethylamino group, and still more preferably has 1 or 2 hydroxyl groups or amine groups as substituents.

Further, Xc is more preferable₂The following can be exemplified.

An amino group which may have 1 or 2 substituents selected from the group consisting of a hydrogen atom, a methyl group, a methoxy group, a sulfo group, an amino group and an alkylamino group having 1 to 4 carbon atoms,

A phenylamino group which may have 1 or 2 substituents selected from the group consisting of a hydrogen atom, a methyl group, a methoxy group, a sulfo group, an amino group, and an alkylamino group having 1 to 4 carbon atoms,

A benzoyl group which may have 1 substituent selected from the group consisting of an amino group and a carboxyethylamino group,

Benzoylamino group which may have 1 substituent selected from the group consisting of a hydrogen atom, an amino group and a carboxyethylamino group, or

A phenylazo group which may have 1 to 3 substituents selected from the group consisting of a hydrogen atom, a hydroxyl group, a methyl group, a methoxy group, an amino group, and a carboxyethylamino group.

The position of the substituent is not particularly limited, but is exemplified by Xc₂In the case of a phenylamino group, it is particularly preferred that at least 1 of the substituents on the phenyl group is in the p-position of the phenyl group relative to the amino group.

In the above formula (10), Rc₂₁To Rc₂₅Each independently represents a hydrogen atom, a lower alkyl group, a lower alkoxy group or a lower alkoxy group having a sulfo group. Rc (Rc)₂₁To Rc₂₅More preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a linear 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, particularly preferably a hydrogen atom, a methyl group, a methoxy group, or a 3-sulfopropoxy group.

In the above formula (10), Rc₂₆Represents a hydrogen atom, a lower alkyl group or a lower alkoxy group having a sulfo group. More preferred is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a linear alkoxy group having a sulfo group at the terminal, still more preferred is a hydrogen atom, a methyl group, an ethyl group, a 3-sulfopropoxy group, or a 4-sulfobutoxy group, and particularly preferred is a hydrogen atom, a methyl group, or a 3-sulfopropoxy group.

In the formula (10), p and q are each independently an integer of 0 or 1. In the polarizing element of the present invention, in order to obtain good polarizing performance, when one of p and q is 0, the other is preferably 1, and more preferably, p and q are 1.

Among the azo compounds represented by the above formula (10), the azo compound represented by the following formula (10b) is preferable. By using such an azo compound, the polarizing performance of the polarizing element can be further improved. In the formula (10b), Ac₂、Rc₂₁To Rc₂₆、Xc₂P, and q are as defined above for formula (10).

Next, specific examples of the azo compound represented by the formula (10) in the form of a free acid are shown below. In the following examples of compounds, sulfo groups and hydroxyl groups are shown as free acids, but sulfo groups and hydroxyl groups may be in the form of salts.

Examples of the method for synthesizing the azo compound represented by the formula (10) in the form of a free acid include, but are not limited to, the methods described in, for example, Japanese patent application laid-open No. 9-302250, Japanese patent application laid-open No. 3-12606, International publication No. 2005/075572, International publication No. 2012/108169, and International publication No. 2012/108173. Examples of the azo compound having the free acid form represented by the formula (10) include azo compounds described in c.i. direct Red 117, c.i. direct Red 127, japanese unexamined patent application publication No. 3-12606, azo compounds described in international publication No. 2005/075572, and azo compounds described in international publication No. 2012/108169.

In one embodiment, the polarizing element of the present invention further comprises an azo compound represented by the above formula (11), a metal complex compound thereof, or a salt thereof, or an azo compound represented by the formula (12), or a salt thereof.

A compound represented by the formula (11) will be described.

In formula (11), Ab₁Represents a phenyl group or naphthyl group having at least 1 substituent selected from the group consisting of a sulfo group and a carboxyl group, Rb₁₁To Rb₁₄Each independently represents a hydrogen atom, a lower alkyl group, a lower alkoxy group or a lower alkoxy group having a sulfo group, Rb₁₅And Rb₁₆Each independently represents a lower alkoxy group, Xb₁Represents an amino group having at least 1 member 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 hydroxyl group, a carboxyl group and a carboxyethylamino 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, and a benzoyl group which may have a substituent. d represents an integer of 0 or 1. Further, the compound may be a metal complex compound, and more preferably, may be a copper complex compound.

The copper complex compound is, for example, represented by the following formula (11b), and M in the formula (11b) is a metal, and copper, nickel, cobalt, or the like can be used, but copper is more preferable. In addition, in formula (11b), Ab₁、Rb₁₁To Rb₁₄、Rb₁₆、Xb₁And d each represents the same meaning as in the above formula (11).

Ab in the above formulae (11) and (11b)₁In the case of a phenyl group, it is more preferred to have at least 1 sulfo or carboxyl group as a substituent thereof. When the phenyl group has 2 or more substituents, at least 1 of the substituents is a sulfo group or a carboxyl group, and the other substituents are preferably selected from the group consisting of a sulfo group, a carboxyl group, a lower alkyl group, a lower alkoxy group having a sulfo group, a hydroxyl group, a nitro group, a benzoyl group, an amino group, an acetylamino group and an amino group substituted with 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 hydroxyl group, a carboxyl 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 carboxyl group and a 3-sulfopropoxy group. The lower alkoxy group having a sulfo group is preferably a linear alkoxy group as described above, such as 3-sulfopropoxy or 4-sulfobutoxy, and the substitution position of the sulfo group is preferably a 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 azo groupWhen the position of the group is 1-position, the 4-position of the phenyl group is preferred, and when the number of sulfo groups is 2, the combination of the 2-position and 4-position or the combination of the 3-position and 5-position of the phenyl group is more preferred.

Ab in the above formulae (11) and (11b)₁In the case of a naphthyl group, it is more preferable to have at least 1 sulfo group as a substituent thereof. When the naphthyl group has 2 or more substituents, at least 1 of the substituents is a sulfo group, and the other substituents are preferably selected from the group consisting of a sulfo group, a hydroxyl group, a carboxyl group and 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 a terminal of the alkoxy group. Such a lower alkoxy group having a sulfo group is more preferably 3-sulfopropoxy or 4-sulfobutoxy, particularly preferably 3-sulfopropoxy. When the number of sulfo groups substituted with a naphthyl group is 2, the combination of the 4-and 8-positions or the 6-and 8-positions of the naphthyl group in which the substitution position of the sulfo group is the azo group is preferred, and the combination of the 6-and 8-positions is more preferred. When the number of sulfo groups substituted by a naphthyl group is 3, the position of the azo group is the 2-position, and the substitution position of the sulfo group is preferably a combination of the 3-, 6-, and 8-positions.

In the above formulae (11) and (11b), Rb is₁₁To Rb₁₄Each 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 a terminal of the alkoxy group. Rb₁₁To Rb₁₄More preferred is a hydrogen atom, methyl group, ethyl group, methoxy group, ethoxy group, 3-sulfopropoxy group or 4-sulfobutoxy group, and particularly preferred is sulfo group, methyl group, methoxy group, carboxyl group or 3-sulfopropoxy group.

Rb in the above formula (11)₁₅And Rb₁₆Rb in formula (11b)₁₆Each independently represents a lower alkoxy group, more preferably a methoxy group or an ethoxy group. In order to significantly improve the polarizing performance of the polarizing element or the polarizing plate of the present invention, methoxy is preferred.

Xb in the above formulae (11) and (11b)₁Represents a compound having at least 1 substituent selected from the group consisting of lower alkyl, lower alkoxy, sulfo, amino, and lower alkylaminoA substituted amino 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, or a benzoylamino group which may have a substituent, or a benzoyl group which may have a substituent.

Xb₁In the case of an amino group which may have the above-mentioned substituent, the amino group may be unsubstituted, but it is more preferable to have 1 or 2 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 it is still more preferable to have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfo group, an amino group and a lower alkylamino group.

Xb₁In the case of a phenylamino group which may have the above substituent, the phenylamino group is unsubstituted or more preferably has 1 or 2 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 still more preferably has 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfo group and an amino group.

Xb₁In the case of the phenylazo group which may have the above substituent, the phenylazo group is unsubstituted, or more preferably has 1 to 3 substituents selected from the group consisting of a hydroxyl group, a lower alkyl group, a lower alkoxy group, an amine group and a carboxyethylamino group, and still more preferably has 1 to 3 substituents selected from the group consisting of a methyl group, a methoxy group, an amine group and a hydroxyl group.

Xb₁In the case of the naphthotriazolyl group which may have the above-mentioned substituent, the naphthotriazolyl group is unsubstituted, or more preferably has 1 or 2 substituents selected from the group consisting of a sulfo group, an amine group and a carboxyl group, and still more preferably has 1 or 2 sulfo groups as the substituents.

Xb₁In the case of a benzoylamino group which may have the above-mentioned substituent(s), the benzoylamino group is unsubstituted, or more preferably has 1 substituent selected from the group consisting of a hydroxyl group, an amino group and a carboxyethylamino group, and still more preferably has 1 or 2 hydroxyl groups or amino groups as substituents.

Xb₁May have at least 1 of the above-mentioned substituents, and is more preferablyBenzoylamino group or phenylamino group, and most preferred is phenylamino group which may have the above-mentioned substituent. When benzoylamino group or phenylamino group has the above-mentioned substituent, the position of the substituent is not particularly limited, but in the case of phenylamino group, 1 of the above-mentioned substituents is more preferably p-position to amino group, and in the case of benzoylamino group, 1 of the above-mentioned substituents is more preferably p-position to carbonyl group.

Among the azo compounds represented by the above formula (11), the azo compound represented by the following formula (11c) is preferable, and the use of such an azo compound can further improve the polarizing performance of the polarizing element. In formula (11c), Ab₁、Rb₁₁To Rb₁₆、Xb₁And d are each as defined in the above formula (11).

Specific examples of the azo compounds represented by the above formulae (11), (11b) and (11c) include the following azo compounds described in, for example, Japanese patent application laid-open Nos. 3-12606, 5-295281, 10-259311, 2007/145210, 2012/108169 and 2012/108173.

The azo compounds represented by the above-mentioned formulae (11), (11b) and (11c) can be produced by, for example, the methods described in, but not limited to, Japanese patent application laid-open Nos. 3-12606, 5-295281, 10-259311, 2007/145210, 2012/108169 and 2012/108173.

Next, the azo compound represented by the above formula (12) will be described.

In formula (12), Ab₂Represents a phenyl group or naphthyl group having at least 1 substituent selected from the group consisting of a sulfo group and a carboxyl group, Rb₂₁Represents a hydrogen atom, a lower alkyl group, a lower alkoxy group or a lower alkoxy group having a sulfo group, Xb₂Represents an amino group having at least 1 substituent selected from the group consisting of a lower alkyl group, a lower alkoxy group, a lower alkylamino group, a hydroxyl group, a carboxyl group, a sulfo group, an amino group and a substituted amino 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.

In formula (12), Ab₂Represents a phenyl group or a naphthyl group having at least 1 substituent selected from the group consisting of a sulfo group and a carboxyl group, and when the phenyl group or the naphthyl group has 2 or more substituents, at least 1 of the substituents is a sulfo group or a carboxyl group, and the other substituents are preferably selected from the group consisting of a sulfo group, a lower alkyl group, a lower alkoxy group having a sulfo group, a carboxyl 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 carboxyl group, a nitro group and an amino group, particularly preferably selected from the group consisting of a sulfo group, a carboxyl group, a low alkoxy group, a carboxyl group, a nitro group and an amino group, and particularly preferably selected from the group consisting of a sulfo group, a carboxyl group and a sulfo groupLower alkyl and lower alkoxy. The lower alkoxy group having a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably a terminal of the alkoxy group. Such a lower alkoxy group having a sulfo group is more preferably 3-sulfopropoxy or 4-sulfobutoxy, particularly preferably 3-sulfopropoxy. In addition, the number of substituents possessed by the phenyl group is preferably 1 or 2, and on the other hand, the number of substituents possessed by the naphthyl group is preferably 2 or 3. The position of these substituents is not particularly limited, but when the number of substituents of the phenyl group is 1, the position of the azo group is 1 position and the 4-position of the phenyl group is preferred, and the number of substituents is 2, and 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, naphthyl group has preferably 2 or 3 sulfo groups as substituents, in the naphthyl group substituted sulfo number is 2, sulfo group substitution position is naphthyl azo group substitution position is 2, 4-, 8-position combination or 6-, 8-position combination is preferred, in 6-, 8-position combination is more preferred. When the number of sulfo groups substituted by a naphthyl group is 3, the substitution position of the sulfo group is the 2-position of the azo group, and a combination of the 3-, 6-, and 8-positions is preferred.

In the above formula (12), Rb₂₁Represents 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 a terminal of the alkoxy group. Rb₂₁More preferred 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 preferred is a sulfo group, a methyl group, a methoxy group, a carboxyl group or a 3-sulfopropoxy group. In particular, Rb₂₁The methoxy group is preferred because it significantly improves the polarizing performance of the polarizing element or polarizing plate of the present invention.

In the above formula (12), Xb₂Represents an amino group having at least 1 substituent selected from the group consisting of a lower alkyl group, a lower alkoxy group, a lower alkylamino group, a hydroxyl group, a carboxyl group, a sulfo group, an amino group and a substituted amino group, or an amino group having at least 1 substituent selected from the group consisting of a hydrogen atom, a lower alkyl group, a lower alkoxy group, a hydroxyl group, a carboxyl group, an amino group and a substituted amino group,A phenylamino group, a phenylazo group, a naphthotriazolyl group or a benzoylamino group as a substituent in the group consisting of a carboxyl group, a sulfo group, an amino group and a substituted amino group.

Xb₂In the case of an amino group which may have the above-mentioned substituent, the amino group may be unsubstituted, but may preferably have 1 or 2 substituents selected from the group consisting of a hydroxyl group, a carboxyl group, a sulfo group, an amino group and a lower alkylamino group, and more preferably may have 1 or 2 substituents selected from the group consisting of a methyl group, a methoxy group, a sulfo group, an amino group and a lower alkylamino group.

Xb₂In the case of a phenylamino group which may have the above substituent, the phenylamino group is unsubstituted or 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 more preferably unsubstituted or has a methoxy group as a substituent. When the phenylamino group has the substituent, the position of the substituent is not particularly limited, but 1 of the substituents is preferably the p-position with respect to the amino group bonded to the phenyl group.

Xb₂In the case of a benzoylamino group which may have the above-mentioned substituent, the benzoylamino group may be unsubstituted or may have a substituent selected from the group consisting of an amino group, a substituted amino group and a hydroxyl group, and it is more preferable to have an amino group as the substituent. When the benzoylamino group has the above substituent, the position of the substituent is not particularly limited, but 1 of the above substituents is more preferably p-position with respect to the carbonyl group bonded to the phenyl group.

Xb₂In the case of the phenylazo group which may have the above substituent, the phenylazo group may be unsubstituted or may have a substituent selected from the group consisting of a hydroxyl group, an amine group, a methyl group, a methoxy group and a carboxyl group, and more preferably has a hydroxyl group as a substituent.

Xb₂In the case of a naphthotriazolyl group which may have the above-mentioned substituent, the phenylazo group may be unsubstituted or have a sulfo group as a substituent.

Among the azo compounds represented by the above formula (12), the azo compound represented by the following formula (12b) is preferable, and the polarizing performance of the polarizing element can be further improved by using such an azo compound.

In formula (12b), Ab₂、Rb₂₁And Xb₂Each as defined above for formula (12).

Specific examples of the azo compound represented by the formula (12) include the following azo compounds.

The azo compound represented by the above formula (12) can be produced by, for example, known diazotization and coupling methods described in Japanese patent application laid-open No. 64-5623 and Japanese patent application laid-open No. 5-53014, but is not limited thereto.

In the above polarizing element, the content of the azo compound represented by formula (11) or formula (12) or a salt thereof is preferably 0.0001 to 5 parts by mass, more preferably 0.001 to 1 part by mass, relative to 100 parts by mass of the aqueous solution.

In one embodiment, the polarizing element of the present invention is more preferably a polarizing element comprising at least 1 of the azo compounds represented by the following formula (13) or (13') or salts thereof in order to further improve polarizing performance.

In the above formula (13), Ay₁Is a hydrogen atom, sulfo group, carboxyl group, hydroxyl group, lower alkyl group, or lower alkoxy group, and is preferably sulfo group or carboxyl group. Ry₁To Ry₄Each independently represents a hydrogen atom, a sulfo group, a lower alkyl group, a lower alkoxy group having a sulfo group, more preferably a hydrogen atom,Sulfo group, lower alkyl group, lower alkoxy group, more preferably hydrogen atom, methyl group, methoxy group. j represents an integer of 1 to 3.

In the above formula (13'), i is 0 or 1. Ay₁、Ay₂、Ry₁、Ry₂And j represents the same meaning as in formula (13).

In formula (13'), Ay₁And Ay₂More preferably sulfo, carboxyl or lower alkoxy, more preferably sulfo, carboxyl, methoxy or ethoxy, more preferably sulfo or carboxyl.

In formula (13'), Ry₁And Ry₂More preferably a hydrogen atom, sulfo group, methyl group, ethyl group, methoxy group or ethoxy group, and still more preferably a hydrogen atom, sulfo group, methyl group or methoxy group.

Among the azo compounds represented by the above formula (13) or (13'), particularly preferred is an azo compound represented by the following formula (13b), and by using such an azo compound, the polarizing performance of the polarizing element can be further improved. In formula (13b), Ay₁、Ry₁、Ry₂As defined in formula (13) above.

In a more preferred embodiment, the azo compound represented by the formula (13) or (13') may be used together with the azo compound represented by the formula (5) or (6).

In the above polarizing element, the content of the azo compound represented by the above formula (13) or (13') or a salt thereof is preferably 0.01 to 300 parts by mass, more preferably 0.1 to 200 parts by mass, and still more preferably 30 to 200 parts by mass, relative to 100 parts by mass of the content of the azo compound of the formula (5) or (6).

The azo compounds represented by the above formulae (13) and (13') have an influence on the transmittance of 400 to 500 nm. In the polarizing element, in particular, transmittance and polarization degree (dichroism) on the short wavelength side of 400 to 500nm may affect blue spots in black display or white yellowing in white display. The azo compounds represented by the formulae (13) and (13') can improve the polarization properties (dichroism) of 400 to 500nm while suppressing a decrease in transmittance on the short wavelength side of the parallel position of the polarizing element, and further reduce yellowing in white display and blue spots in black display. The polarizing element further contains an azo compound represented by the formula (13) or (13'), and is preferably a monomer and colorless, particularly in the range of 30 to 65% of the monomer transmittance after the visibility correction, to express a higher quality white color of paper in white display, and particularly, in the range of 35 to 45% of the monomer transmittance after the visibility correction, to improve the polarization degree or contrast.

Specific examples of the azo compounds represented by the formulae (13) and (13') include, but are not limited to, azo compounds having a stilbene structure described in, for example, c.i. direct Yellow4, c.i. direct Yellow12, c.i. direct Yellow 72, and c.i. direct Orange39, and international publication No. 2007/138980.

Further specific examples of the azo compounds represented by the formulae (13) and (13') are shown below. In addition, examples of the compounds are shown in the form of free acids.

The azo compounds represented by the formulae (13) and (13') or salts thereof can be synthesized, for example, by the method described in international publication No. 2007/138980, but they can also be obtained from commercial sources.

The polarizing element of the present invention may contain other azo compounds for the purpose of color correction to such an extent that the performance of the present invention is not impaired. The other azo compound contained is particularly preferably high in dichroism. Examples of the azo compounds include azo compounds described in non-patent document 1, c.i.direct.yellow12, c.i.direct yellow28, c.i.direct.yellow44, c.i.direct.orange26, c.i.direct.orange39, c.i.direct.orange107, c.i.direct.red2, c.i.direct.red31, c.i.direct.red79, c.i.direct.red247, c.i.direct.green80, c.i.direct.green59, and japanese patent application laid-open nos. 2001-33627, 2002-296417 and 60-156759. In particular, azo compounds having a phenylJ acid in the azo structure can be suitably used. Such other azo compounds are suitably used for the polarizing element together with the azo compound represented by formula (1) or a salt thereof. The other azo compounds mentioned above are free acids, and may be used as alkali metal salts (for example, sodium salt, potassium salt, lithium salt), ammonium salts, or salts of amines, or copper complex compounds or salts thereof. The other azo compounds are not limited to these, and known dichroic azo compounds can be used. The optical properties can be improved by including another azo compound in the form of a free acid, a salt thereof, or a copper complex salt thereof. The other azo compounds may be used alone in an amount of 1, or in combination of two or more.

In one embodiment, the polarizing element of the present invention has improved heat resistance and durability by containing iodine. When the substrate contains iodine, iodine is only hardly dissolved in a solvent and hardly impregnated into the substrate, and therefore, iodine is generally contained together with iodides such as potassium iodide, ammonium iodide, copper iodide, sodium iodide, calcium iodide, cobalt iodide, and zinc iodide, and chlorides such as sodium chloride, lithium chloride, and potassium chloride. When a polarizer is produced using the iodide, a polarizer having a high degree of polarization in the visible light region around 480nm and around 600nm can be usually produced.

In one embodiment, the polarizing element of the present invention may contain iodine, by which, for example, the transmittance of the monomer after the visibility correction is 35 to 50% and has a high degree of polarization, that is, a contrast. The iodine-based polarizing plate has high transmittance and high contrast, and also has optical characteristics, particularly little color change, and little transmittance change, while having high durability, particularly heat resistance.

(substrate)

The base material used for producing the polarizing element is not particularly limited as long as it can contain a dichroic dye such as an infrared-absorbing water-soluble compound, and examples thereof include a molded body formed of a hydrophilic polymer. Examples of the hydrophilic polymer include polyvinyl alcohol-based resins, amylose-based resins, starch-based resins, cellulose-based resins, and polyacrylate-based resins. When the base material contains a dichroic dye such as the infrared light absorbing water-soluble compound, it is most preferable to use a polyvinyl alcohol resin as the base material from the viewpoint of processability, dyeability, and crosslinkability. The shape of the substrate is not particularly limited, but is preferably a film.

(penetration Rate)

In the polarizing element of the present invention, the absolute value of the difference in average transmittance between specific wavelength bands is preferably equal to or less than a predetermined value, in terms of the difference in average transmittance between 2 wavelength bands. The average transmittance is an average value of the transmittance of each wavelength in a specific wavelength band.

In one embodiment, the polarizing element of the present invention is characterized by; the absolute value of the difference between the average value of the transmittance at each wavelength of 520nm to 590nm and the average value of the transmittance at each wavelength of 420nm to 480nm, when measured with the absorption axes of the 2-plate polarizers parallel, is 5% or less, and the absolute value of the difference between the average value of the transmittance at each wavelength of 600nm to 640nm and the average value of the transmittance at each wavelength of 520nm to 640nm is 3% or less.

(penetration after visibility correction)

The transmittance after the visual sensitivity correction was in accordance with JIS Z8722: 2009 obtained visibility corrected transmittance. The transmittance used for correction is measured by measuring the spectral transmittance for each wavelength of 400 to 700nm using a C light source (2 degree field of view) for a measurement sample (for example, a polarizer or a polarizing plate) at every 5nm or 10nm, which can be measured in accordance with JIS Z8722: 2009 by sensitivity correction. The transmittance after the visual sensitivity correction is a single transmittance after the visual sensitivity correction when the polarizing element or the polarizing plate is measured by a single body, a transmittance when the respective absorption axes are made parallel by using 2 polarizing elements or polarizing plates is corrected to a parallel bit transmittance after the visual sensitivity correction when the visual sensitivity is measured, and a transmittance when the respective absorption axes are made orthogonal by using 2 polarizing elements or polarizing plates is corrected to an orthogonal bit transmittance after the visual sensitivity correction when the visual sensitivity is measured.

The wavelength bands of 420nm to 480nm, 520nm to 590nm, and 600nm to 640nm are determined according to the following formula in JIS Z8781-4: 2013 to calculate the dominant wavelength band of the color matching function used. Specifically, the following is a method according to JIS Z8781-4: 2013, wherein X (lambda) with a maximum value of 600nm, Y (lambda) with a maximum value of 550nm, and Z (lambda) with a maximum value of 455nm are set to 100, and the respective wavelength bands with respective wavelengths of 420nm to 480nm, 520nm to 590nm, and 600nm to 640nm are represented as values of 20 or more.

The transmittance measured in a state where 2 polarizing elements are arranged one on top of another so that the absorption axis directions thereof are parallel (in the case of luminance display or white display) is referred to as "parallel bit transmittance". Further, the average transmittance AT each wavelength of O nm to Δ nm is also referred to as "AT_○-△"in the following. In one embodiment of the polarizer of the present invention, the transmittance of parallel bits, AT_420-480And AT_520-590The difference of (b) is not more than 5.0% in absolute value, more preferably not more than 3.5%, still more preferably not more than 2.5%, particularly preferably not more than 1.5%. In addition, in one embodiment, regarding the parallel bit penetration, AT_520-590And AT_600-640The difference of (b) is not more than 3.0% in absolute value, more preferably not more than 2.0%, still more preferably not more than 1.5%, and still more preferably not more than 1.0%. Such a polarizing element is parallel and can display a high-quality paper-like white color.

The transmittance measured in a state where 2 polarizing elements are arranged in a superimposed manner so that the absorption axis direction is orthogonal (in the case of black display or in the case of dark display) is referred to as "orthogonal bit transmittance". In one embodiment of the polarizing element of the present invention, AT is more preferable as the cross-bit transmittance_420-480And AT_520-590The difference of (a) is 3.0% or less in absolute value, and AT_520-590And AT_600-640The difference of (d) is 2.0% or less in absolute value. Such a polarizer can display achromatic black in the orthogonal position. In addition, regarding the orthogonal bit penetration, AT_420-480And AT_520-590The difference in (b) is more preferably 1.5% or less, still more preferably 1.0% or less, particularly preferably 0.5% or less in absolute value. Relating to quadrature bit penetrationRate, AT_520-590And AT_600-640The difference in (b) is more preferably 1.5% or less, still more preferably 1.0% or less, particularly preferably 0.5% or less in absolute value.

In addition, the monomer transmittance at each wavelength in the wavelength bands of 380nm to 420nm, 480nm to 520nm, and 640nm to 780nm, the parallel bit transmittance at each wavelength, and the average transmittance at each orthogonal bit transmittance at each wavelength are preferably adjusted to some extent so that it is difficult to largely affect the color element when the average transmittance at each wavelength in the wavelength bands of 420nm to 480nm, 520nm to 590nm, and 600nm to 640nm is adjusted as described above. Regarding the transmittance of the monomer AT each wavelength, AT is more preferable_380-420And AT_420-480The difference of (A) is 15% or less in absolute value, and AT is more preferable_480-520And AT_420-480The difference of (A) is 15% or less in absolute value, AT_480-520And AT_520-590The difference of (A) is 15% or less in absolute value, AT_640-780And AT_600-640The difference of (c) is 20% or less in absolute value.

In one embodiment, the transmittance of the polarizer of the present invention after the visual acuity correction can be 30% to 65%. The monomer transmittance after the visual sensitivity correction was measured for 1 measurement sample (for example, a polarizing element or a polarizing plate) in accordance with JIS Z8722: 2009 to adjust for sensitivity dependent transmittance. Although higher transmittance can be obtained for the performance of the polarizing plate, if the single transmittance after the visibility correction is 30% to 65%, brightness without harmony and unevenness can be exhibited even when the polarizing plate is used in a display device. The higher the transmittance, the more the degree of polarization tends to decrease, so from the viewpoint of balance with the degree of polarization, the monomer transmittance after the sensitivity correction is more preferably from 35% to 50%, still more preferably from 37% to 47%, particularly preferably from 38% to 45%. When the transmittance of the monomer after the visual sensitivity correction exceeds 65%, the polarization degree may be decreased, but when the transmittance of the polarizer is found to be bright, or when the polarization performance or the contrast is specified, the transmittance of the monomer after the visual sensitivity correction may exceed 65%.

In the parallel-bit transmittance in the polarizing element, AT_520-590Can be from 25% to 50%. Such a polarizing element is providedWhen the display device is used, the display device can be bright and clear with high brightness. Transmittance of each wavelength in the wavelength band of 520nm to 590nm is measured in accordance with JIS Z8781-4: 2013 to calculate 1 of the main wavelength band of the color matching function used. In particular, each wavelength band of 520nm to 590nm is a wavelength band having the highest visibility according to the color matching function, and the transmittance that can be visually confirmed is close to the transmittance in this range. Therefore, it is very important to adjust the transmittance of each wavelength in the wavelength band of 520nm to 590 nm. AT measured in parallel_520-590More preferably 28% to 45%, still more preferably 30% to 40%. In addition, the degree of polarization of the polarizing element at this time may be 80% to 100%, but is preferably 90% to 100%, more preferably 97% to 100%, still more preferably 99% or more, and particularly preferably 99.5% or more. The degree of polarization is preferably high, and the degree of polarization and the degree of transmittance can be adjusted to be appropriate by giving importance to the brightness or the degree of polarization (or contrast).

The single transmittance after the visual sensitivity correction is a single transmittance obtained by performing the visual sensitivity correction through a2 ° field of view (C light source). The transmittance of the monomer after the visual sensitivity correction is obtained by calculating the transmittance of the monomer for each wavelength of 400 to 700nm for 1 measurement sample (for example, a polarizing element or a polarizing plate) at 5nm or 10nm and further performing the visual sensitivity correction with a2 ° visual field (C light source).

(degree of polarization)

The polarizing element of the present invention has a polarizing property at least for light of a part or all of the wavelength region of 700nm to 1400 nm.

The degree of polarization of the polarizing element of the present invention is not particularly limited, but if the degree of polarization is 80% to 100%, a general polarizing element can be used in general-purpose applications. The degree of polarization is more preferably 90% or more. When the polarization degree of the polarizer is 90% or more, the polarizer can exhibit a polarizing function even when used in a liquid crystal display device. The degree of polarization is more preferably 99% or more, still more preferably 99.9% or more, and still more preferably 99.95% or more. However, since the requirement of the polarization degree is different in the application in which the brightness (transmittance) and the contrast (polarization degree) are used, the requirement is not necessarily 99%, and the polarization degree can be set and used in accordance with the requirement.

(chroma)

The chroma a and b are expressed in accordance with JIS Z8781-4: 2013, and a value obtained when the transmittance of natural light is measured. In JIS Z8781-4: 2013 is equivalent to the object color display method defined by the Commission on International illumination Commission (CIE for short). The chromaticity a and b are measured by irradiating a sample (for example, a polarizing element or a polarizing plate) with natural light. In addition, the values of chromaticity a and b are expressed as a x-s and b x-s for 1 piece of measurement sample, the values of chromaticity a and b x are expressed as a x-p and b x-p for 2 pieces of measurement sample arranged in a state where the absorption axis directions thereof are parallel to each other (in white display), and the values of chromaticity a and b x are expressed as a x-c and b x-c for 2 pieces of measurement sample arranged in a state where the absorption axis directions thereof are orthogonal to each other (in black display).

In one embodiment, the polarizing element of the present invention preferably has absolute values of a-s and b-s of 1.0 or less, and more preferably absolute values of a-p and b-p of 2.0 or less. Such a polarizing element is a single body and has a neutral color, and can display high-quality white in white display. The absolute values of a and b of the polarizing element are each preferably 1.5 or less, more preferably 1.0 or less. The absolute values of a, b, c and a are preferably 3.0 or less, more preferably 2.0 or less, and still more preferably 1.0 or less, independently of each other. Such a polarizing element can display achromatic black when displaying black. Even if the absolute values of the chromaticity a and b have a difference of 0.5, a human can perceive a color difference and sometimes a human perceives a large color difference. Therefore, in the polarizing element, it is very important to control these values. In particular, when the absolute values of a, b, a, and b are 1.0 or less, the other colors are hardly observed in white display and black display, and a good polarizing plate can be obtained. Thus, the polarizing plate can realize a high-quality white color like paper without coloring at the parallel position and a clear black color with a high-grade feeling without coloring at the orthogonal position.

In one embodiment, the polarizer of the present invention has high contrast and high transmittance, while having no color and high polarization degree in the monomer. The polarizing element of the present invention can exhibit high-quality paper-like white (paper white) when white is displayed, and can exhibit achromatic black, particularly clear black having a high-grade feeling, when black is displayed. Such a polarizing element having high transmittance and achromatic property, and having absorption performance in the infrared region and further having polarization performance in the infrared region does not exist. The polarizing element of the present invention is further characterized by high durability, particularly, durability at high temperature and high humidity.

[ method for producing polarizing element ]

Hereinafter, a specific method for producing a polarizing element will be described with respect to a substrate, taking a polyvinyl alcohol resin film as an example. The polarizing element can be produced by, for example, sequentially performing the production of a polyvinyl alcohol resin, the production of a blank mold, a swelling treatment, a dyeing treatment, the 1 st washing treatment, a treatment containing a crosslinking agent and/or a water-resistant agent, an elongation treatment, the 2 nd washing treatment, and a drying treatment. In addition, part of these processes may be omitted.

The method for producing the polarizer is to adjust the swelling degree of the base material in the swelling step, the blending ratio of each azo compound in the dyeing step, the temperature of the dyeing solution, the pH, the kind of salt such as sodium chloride, sodium sulfate, sodium tripolyphosphate, or the like, or the concentration thereof, and the dyeing time, and the stretching ratio in the stretching step, which will be described later, and in one embodiment, the polarizer is adjusted so as to satisfy at least 1 of the following conditions (i) to (v), and more preferably so as to satisfy the condition (vi).

(i) For parallel bit penetration, AT_420-480And AT_520-590The absolute value of the difference of (A) is 5% or less, AT_520-590And AT_600-640The absolute value of the difference of (a) is 3% or less.

(ii) For orthogonal bit penetration, AT_420-480And AT_520-590OfAbsolute value of 3% or less, AT_520-590And AT_600-640The absolute value of the difference of (2) or less.

(iii) The monomer transmittance after the visual sensitivity correction was changed from 35% to 50%.

(iv) The absolute values of a and b are 1.0 or less in the polarizing element monomer and 2.0 or less in the parallel position.

(v) The absolute values of a-value and b-value measured at the orthogonal positions are both 3 or less.

(vi) The difference between the average transmittance for wavelengths from 380nm to 420nm and the average transmittance for wavelengths from 420nm to 480nm, the difference between the average transmittance for wavelengths from 480nm to 520nm and the average transmittance for wavelengths from 520nm to 590nm, the difference between the average transmittance for wavelengths from 640nm to 780nm and the average transmittance for wavelengths from 600nm to 640nm, is 15% or less in absolute terms, and/or the difference between the average transmittance for wavelengths from 640nm to 780nm and the average transmittance for wavelengths from 600nm to 640nm, is 20% or less in absolute terms.

(production of polyvinyl alcohol resin)

The method for producing the polyvinyl alcohol resin is not particularly limited, and a known method can be used. The polyvinyl alcohol resin can be obtained, for example, by saponifying a polyvinyl acetate resin. The polyvinyl acetate-based resin may be exemplified by a copolymer of vinyl acetate and another monomer copolymerizable therewith, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. Other monomers copolymerizable with vinyl acetate are, for example, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids and the like. 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, for example, polyvinyl formaldehyde or polyvinyl acetal modified with aldehydes. The polymerization degree of the polyvinyl alcohol resin is a viscosity-average polymerization degree, and can be determined by a known method in the art. The polymerization degree is usually about 1,000 to 10,000, and more preferably about 1,500 to 6,000.

(preparation of embryo Membrane)

Next, a polyvinyl alcohol resin film is produced, and a green film is produced. The method for producing the polyvinyl alcohol resin film is not particularly limited, and a known method can be used. The embryonic membrane may contain glycerol, ethylene glycol, propylene glycol, low molecular weight polyethylene glycol, etc. as plasticizers. The plasticizer content is 5 to 20% by weight, more preferably 8 to 15% by weight in the embryonic film. The thickness of the green film is not particularly limited, but is preferably about 5 μm to 150 μm, more preferably about 10 μm to 100 μm.

(swelling treatment)

The obtained embryonic membrane was passed through, and then, swelling treatment was performed. The swelling treatment is performed by immersing the embryonic membrane in a solution at 20 to 50 ℃ for 30 seconds to 10 minutes. The solution is preferably an aqueous solution. The draw ratio in the swelling treatment is more preferably adjusted to 1.00 to 1.50 times, and still more preferably 1.10 to 1.35 times. In order to swell in the dyeing treatment described later, the swelling treatment can be omitted when the time for producing the polarizing element is shortened.

(dyeing treatment)

After the swelling treatment, dyeing treatment is performed. The dyeing treatment is carried out using a dye such as an infrared light absorbing water-soluble compound. The dyeing is carried out by using a water-soluble compound which absorbs light at least in the infrared region and a dye which acts as a dichroic dye in the visible light region, for example, iodine and iodine compounds, dyes disclosed in non-patent document 1, patent document 19, patent document 20, patent document 23, patent document 24, and the like, and azo compounds described in formulae (5) to (13) are more preferable. The dyeing is performed, for example, by immersing the swollen film in a dyeing solution containing the above-mentioned compound. When iodine is used as the dichroic dye, the iodide is not particularly limited, but examples thereof include potassium iodide, ammonium iodide, cobalt iodide, and zinc iodide. The concentration of iodine in the solution for dyeing is more preferably 0.0001 to 0.5% by weight, still more preferably 0.001 to 0.4% by weight, and still more preferably 0.001 to 0.1% by weight.

The temperature of the solution for the dyeing treatment is preferably 5 to 60 ℃, more preferably 20 to 50 ℃, particularly preferably 25 to 50 ℃. The time for immersion in the solution may be appropriately adjusted, but is preferably 30 seconds to 20 minutes, more preferably 1 to 10 minutes. The dyeing solution is preferably an aqueous solution. The dyeing method is preferably a method of immersing in a dyeing solution, but a method of coating a dyeing solution on a film after swelling treatment may be employed. 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 may be arbitrarily adjusted depending on the time and temperature of the dyeing property of the dichroic dye, but is preferably 0 to 5% by weight, more preferably 0.1 to 2% by weight.

When dyeing is performed using a plurality of dyes, the order of dyeing treatment is not particularly limited. The impregnation of the dyes into the substrate may be carried out simultaneously or in any order. When infrared light absorbing water soluble compounds are used with other azo compounds, these dyeings are preferred to be carried out simultaneously. When iodine is used, it is preferable to impregnate the base material with the infrared absorbing water-soluble compound and optionally other azo compounds, from the viewpoint of management of the dyeing liquid, productivity, and the like.

(1 st washing treatment)

After the dyeing treatment, a washing treatment (hereinafter, referred to as "1 st washing treatment") may be performed before the subsequent treatment. The 1 st washing treatment is a treatment of washing the dyeing solution adhering to the surface of the film in a dyeing treatment. By performing the 1 st washing treatment, the contamination of the dye in the solution used in the subsequent treatment can be suppressed. In the 1 st washing treatment, water is generally used as a washing liquid. The washing method is preferably a method of immersing the dyed film in a washing liquid, but a method of applying a washing liquid to the dyed film may be employed. 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 1 st washing treatment must be a temperature at which the dyed film is not dissolved. Washing is generally carried out at from 5 to 40 ℃. However, since no problem occurs in performance even if the 1 st washing treatment is not performed, the 1 st washing treatment can be omitted.

(treatment with crosslinking agent and/or Water-resistant agent)

After the 1 st washing treatment, a treatment containing a crosslinking agent and/or a water-resistant agent may be performed. Examples of the crosslinking agent include boric acid, boron compounds such as borax and ammonium borate, polyaldehydes such as glyoxal and glutaraldehyde, polyisocyanate-based compounds such as biuret-type, isocyanurate-type and block-type, titanium-based compounds such as titanyl sulfate, ethylene glycol glycidyl ether, and polyamide epichlorohydrin. Examples of the water-resistant agent include succinic peroxide, ammonium persulfate, calcium perchlorate, benzidine ethyl ether, ethylene glycol diglycidyl ether, glycerol diglycidyl ether, ammonium chloride, magnesium chloride, and the like. Among these, boric acid is most preferred. The crosslinking agent and the water-resistant agent may be used alone in 1 kind or in combination of two or more kinds.

The method of immersing the 1 st washed film in a solution containing a crosslinking agent and/or a water-resistant agent is more preferable, but a method of applying a solution containing a crosslinking agent and/or a water-resistant agent to the 1 st washed film may be also used. The solution is preferably an aqueous solution. The content of the crosslinking agent and/or the water resistant agent in the solution is preferably 0.1 to 6.0% by weight, more preferably 1.0 to 4.0% by weight, in the case where boric acid is used as an example. The temperature of the solution is preferably 5 to 70 ℃, more preferably 5 to 50 ℃. The treatment time is preferably 30 seconds to 6 minutes, more preferably 1 to 5 minutes. However, if it is not necessary to contain a crosslinking agent and/or a water-resistant agent and the time is to be shortened, the treatment can be omitted when the crosslinking treatment or the water-resistant treatment is not necessary.

(elongation treatment)

After the treatment with the crosslinking agent and/or the water-resistant agent, the stretching treatment is performed. The stretching process is a process of stretching the film in one direction. The stretching method may be either a wet stretching method or a dry stretching method. The draw ratio is 3 times or more, preferably 5 to 7 times.

In the wet stretching method, stretching is performed in water, a water-soluble organic solvent, or a mixed solution thereof. It is more preferable to perform the stretching treatment while immersing the film after the 1 st washing treatment in a solution containing a crosslinking agent and/or a water-resistant agent. Examples of the crosslinking agent and the water-resistant agent include those described above. The content of the crosslinking agent and/or the water resistant agent in the solution is preferably 0.5 to 15% by weight, more preferably 2.0 to 8.0% by weight, in the case where boric acid is used as an example. The draw ratio is preferably 2 to 8 times, more preferably 5 to 7 times. The temperature of the solution is preferably 40 to 60 ℃, more preferably 45 to 58 ℃. The extension time is usually 30 seconds to 20 minutes, but 2 to 5 minutes is more preferable. The film may be stretched in 1 stage, but may be stretched in 2 or more stages.

In the dry drawing method, when the drawing heating medium is an air medium, the temperature of the air medium is preferably from room temperature to 180 ℃. Further, it is more preferable to treat in an atmosphere of humidity 20 to 95% RH. Examples of the heating method include inter-roll zone stretching, roll heating stretching, rolling stretching, infrared heating stretching, and the like, and the stretching method is not limited. The film may be stretched in 1 stage, but may be stretched in a plurality of stages of 2 stages or more.

(2 nd washing treatment)

After the stretching treatment, a crosslinking agent and/or a water resistant agent may be precipitated on the film surface, or foreign matter may be attached, so that a cleaning treatment for cleaning the film surface (hereinafter, referred to as "2 nd cleaning treatment") may be performed. The washing method is more preferably a method of immersing the stretched film in a washing liquid, but a method of applying a washing liquid to the stretched film may be employed. The washing treatment may be carried out in 1 stage, or a multi-stage treatment of 2 stages or more may be carried out. 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 ℃ and more preferably 10 to 40 ℃.

Examples of the solvent used in the treatment include, but are not limited to, water, dimethyl sulfoxide, N-methylpyrrolidone (Methyl pyrrolidone), alcohols such as methanol, ethanol, propanol, isopropanol, glycerol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. In addition, a mixture of 1 or more of these solvents may also be used. Most preferably, the solvent is water.

(drying treatment)

After the 2 nd washing treatment, a drying treatment for drying the film is performed. The drying treatment may be performed by natural drying. To improve the drying efficiency, the drying may be performed by compression using a roller, or by removing water from the surface using an air knife, a water suction roller, or the like, or by air-blowing. The drying temperature is preferably 20 to 100 ℃ and more preferably 60 to 100 ℃. The drying time is preferably 30 seconds to 20 minutes, more preferably 5 to 10 minutes.

In this way, a polarizing element containing an infrared-absorbing water-soluble compound can be obtained.

In one embodiment, the polarizer of the present invention contains iodine and has high transmittance, contrast and durability.

In one embodiment, the polarizing element of the present invention is an AT measured in the parallel position_520-590And AT_420-480Has an absolute value of the difference of 5% or less, and AT_600-640And AT_520-590The absolute value of the difference of (a) is 3% or less, and thus the film has an absorption or polarization function in the infrared region, a colorless color in the visible light region, high transmittance, and high degree of polarization, and has high durability.

In one embodiment, the polarizing element of the present invention contains a compound represented by formula (9) or formula (10), and thus has an absorption or polarization function in the infrared region, while having high transmittance, polarization degree and high durability in the visible region.

[ polarizing plate ]

The polarizing plate of the present invention includes a polarizing element and a transparent protective layer formed on at least one side, i.e., one or both sides, of the polarizing element. After coating a polymer on at least one surface of the polarizing element, the polarizing element is dried or heat-treated, and thereby a transparent protective layer is provided on at least one surface of the polarizing element. In addition, a transparent protective layer may be provided on at least one surface of the polarizing element by forming a polymer into a film as the transparent protective layer, and then attaching the transparent protective layer to at least one surface of the polarizing element, followed by drying or heat treatment.

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 triacetylcellulose and diacetylcellulose, cyclic polyolefin resins using cyclic olefins as monomers such as acrylic resins, polyvinyl chloride resins, nylon resins, polyester resins, polyacrylate resins and norborene, polyethylene, polypropylene, cyclic olefin polymer resins, polyolefins having a norborene skeleton or copolymers thereof, and resins having imide groups and/or amide groups in the main chain or side chains. In addition, 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 μm to 200 μm. The polarizing plate having a transparent protective layer has optical characteristics equivalent to those of the polarizing element.

In order to bond the transparent protective layer to at least one surface of the polarizing element, an adhesive is required. The adhesive is not particularly limited, but an adhesive containing polyvinyl alcohol as a main component is preferable. Examples of the polyvinyl alcohol-based adhesive include, but are not limited to, Gohsenol NH-26 (manufactured by Nippon synthetic Chemicals Co., Ltd.), EXCEVAL RS-2117 (manufactured by Kuraray Co., Ltd.). The polyvinyl alcohol-based binder may contain a crosslinking agent and/or a water resistance agent. 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 Isoban #18 (manufactured by Kuraray Co., Ltd.) and Isoban #04 (manufactured by Kuraray Co., Ltd.), examples of the ammonia-modified maleic anhydride-isobutylene copolymer include Isoban #104 (manufactured by Kuraray Co., Ltd.) and Isoban #110 (manufactured by Kuraray Co., Ltd.), and examples of the imidized maleic anhydride-isoprene copolymer include Isoban #304 (manufactured by Kuraray Co., Ltd.) and Isoban #310 (manufactured by Kuraray Co., Ltd.). Water-soluble polyfunctional epoxy compounds can be used as the crosslinking agent. Examples of the water-soluble polyfunctional epoxy compound include polyglycerol polyglycidyl ether (Denacol EX-521 (manufactured by Nagase Chemtec Co., Ltd.)), 1, 3-bis (N, N-diglycidylaminomethyl) cyclohexane (TETRAD-C (manufactured by Mitsubishi gas chemical corporation)), and the like. In addition, known adhesives such as urethane adhesives, acrylic adhesives, and epoxy adhesives can be used. In addition, additives such as zinc compounds, chlorides, iodides, and the like may be added in a concentration of about 0.1 to 10 wt% in order to improve the adhesion of the adhesive or improve the water resistance.

When a polarizing plate is attached to a display device such as a liquid crystal display or an organic electroluminescence display, various functional layers for improving a viewing angle and/or contrast and layers having luminance improvement properties may be provided on the surface that is not exposed. The polarizing plate is preferably bonded to these layers or the display device using an adhesive.

When the polarizing plate is attached to a display device such as a liquid crystal display or an organic electroluminescence display, various known functional layers such as an antireflection layer, an antiglare layer, and a hard coat layer may be provided on the surface to be an exposed surface. The layer having these various functionalities is preferably produced by a coating method, but a film having the functions may be bonded by an adhesive or a bonding agent. The various functional layers are, for example, layers for controlling retardation.

In one embodiment, the polarizing plate of the present invention containing iodine has a high degree of polarization centering around 480nm and around 600nm as in the case of a general iodine polarizing plate, and even when applied to a durability test, has less color change than a conventional iodine-based polarizing plate.

In one embodiment, a polarizing plate using a polarizing element of the present invention, which is composed of a base material containing an infrared light absorbing water-soluble compound, and is characterized in that the absolute value of the difference between the average value of transmittances at 520nm to 590nm and the average value of transmittances at 420nm to 480nm when measured with the absorption axes of 2 polarizing elements being parallel is 5% or less, and the absolute value of the difference between the average value of transmittances at 600nm to 640nm and the average value of transmittances at 520nm to 590nm is 3% or less, is a dye-based polarizing element having an absorbing or polarizing function in the infrared region, a colorless color in the visible region, and high transmittance, polarization degree, and high durability. In one embodiment, a polarizing plate using the infrared light absorbing water-soluble compound and the polarizing element of the present invention containing the azo compound represented by formula (9) or formula (10) is a polarizing element capable of obtaining a dye having an absorbing or polarizing function in the infrared region, and having high transmittance, polarization degree and high durability in the visible region. The conventional iodine-based polarizing plate or dye is a problem that the polarizing plate cannot provide a polarizing element having polarization in the infrared region, and the transmittance of 600nm to 780nm in the durability test is greatly changed, and the polarizing plate has color change such as reddening after the durability test. That is, there is a problem that the values of a and b in the L a b color shown in JIS Z8729 are changed, and particularly, in the transmittance values measured by superposing 2 polarizing plates so that the absorption axis direction is orthogonal, the transmittance of 600nm to 780nm is remarkably increased and the red change, that is, the value of a is increased. However, the method of the present application can provide a highly durable polarizing plate with less variation in a value and less color variation.

The polarizing plate of the present invention may have a support on at least one surface. The support is preferably provided with a flat surface portion for bonding to the polarizing plate. Examples of the support include molded articles made of inorganic materials such as glass, crystal and sapphire, and organic plastic plates such as acrylic and polycarbonate. The support is preferably a glass molded product for optical use. Examples of the glass molded article include a glass plate, a lens, and a prism (e.g., a triangular prism and a cubic prism). The glass material may be soda glass or borosilicate glass. A lens with a polarizing plate attached thereto is a capacitor lens that can be used as a polarizing plate in a liquid crystal projector. In addition, a prism having a polarizing plate attached thereto can be used as a polarizing beam splitter having a polarizing plate or a dichroic prism having a polarizing plate attached thereto in a liquid crystal projector. In addition, a polarizing plate may be attached to the liquid crystal cell. The thickness and size of the support are not particularly limited.

In order to further increase the transmittance of the monomer, the polarizing plate having glass is preferably provided with an antireflection layer on at least one surface of the glass or the polarizing plate. For example, a transparent adhesive (pressure-sensitive adhesive) is applied to the flat surface of the support, and then the polarizing plate of the present invention is attached to the applied surface. After the transparent adhesive is applied to the polarizing plate, a support may be attached to the applied surface. The adhesive used herein is preferably acrylate. When the 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.

[ liquid Crystal display device ]

The polarizing element or the polarizing plate of the present invention can be used for a liquid crystal display device. A liquid crystal display device using the polarizing element or the polarizing plate of the present invention has high reliability, high contrast for a long period of time, and high color reproducibility.

The polarizing element or the polarizing plate of the present invention is provided with a protective layer, a functional layer, a support, and the like as required, and can be used in a liquid crystal projector, a computer, a clock, a notebook computer, a document processor, a liquid crystal television, a polarizing lens, polarizing glasses, a navigator, a sensor, a camera, an analyzer, a measurement instrument for indoor and outdoor use, a display, and the like. Particularly, the organic electroluminescence device can be effectively used in a reflective liquid crystal display device, a transflective liquid crystal display device, and the like.

[ examples ]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

< example A >)

[ preparation of measurement sample ]

(example A1)

A polyvinyl alcohol film (VF-PS, manufactured by Kuraray Co., Ltd.) having an average polymerization degree of 2400 or more and a saponification degree of 99% was immersed in warm water at 40 ℃ for 2 minutes, and subjected to swelling treatment so that the draw ratio became 1.30 times. Next, the film subjected to the swelling treatment was immersed in an aqueous solution containing 1500 parts by weight of water, 1.5 parts by weight of sodium tripolyphosphate, 1.5 parts by weight of anhydrous sodium sulfate, and 0.30 part by weight of c.i. direct Black 19 (manufactured by LTD) having a structure represented by formula (101) as a water-soluble compound absorbing light in the infrared region of 700nm to 1400nm, for 3 minutes and 30 seconds, and adjusted to 45 ℃. The obtained membrane was immersed in an aqueous solution containing iodine and an iodine compound at 30 ℃ for 2 minutes, and the aqueous solution was diluted with 2000 parts of water to prepare 100 parts of an aqueous solution of boric acid (Societa chip dragello.p.a.) in an amount of 28.6g/l, iodine (Takara Shuzo Co., Ltd.) in an amount of 0.25g/l, and potassium iodide (Takara Shuzo Co., Ltd.) in an amount of 17.7 g/l. Next, the obtained film was subjected to an elongation treatment at 50 ℃ for 5 minutes in an aqueous solution containing 30.0g/l of boric acid so that the elongation ratio was 5.0 times. The obtained film was immersed in an aqueous solution containing 50g/l of potassium iodide at 30 ℃ for 20 seconds while maintaining the stretched state. Then, the obtained film was dried at 70 ℃ for 9 minutes to obtain a polarizing element. The obtained polarizing element was laminated with an alkali-treated triacetyl cellulose film (ZRD-60, manufactured by Fuji film Co.) using a polyvinyl alcohol adhesive to obtain a polarizing plate. The obtained polarizing plate maintains the optical characteristics of the polarizing element. The polarizing plate was cut into a square size of 40mm and bonded to transparent plate glass with an adhesive layer (AD-ROC manufactured by Polatechno corporation) interposed therebetween, to prepare a durability test sample using the polarizing plate of the present application as a measurement sample of the present application.

(example A2)

A measurement sample was prepared in the same manner as in example a1, except that 0.30 part by weight of c.i. direct Black 19 used in example a1 was replaced with 0.30 part by weight of S0378 manufactured by FEW CHEMICAL corporation represented by formula (102).

(example A3)

A measurement sample was prepared in the same manner as in example a1, except that 0.30 part by weight of c.i.direct Black 19 used in example a1 was replaced with 0.30 part by weight of S2180 manufactured by FEW CHEMICAL company represented by formula (103).

(example A4)

A measurement sample was prepared in the same manner as in example a1, except that 0.30 parts by weight of c.i. direct Black 19 used in example a1 was replaced with 0.30 parts by weight of the compound shown in compound examples (1 to 10).

(example A5)

A measurement sample was prepared in the same manner as in example a1, except that 0.30 part by weight of c.i. direct Black 19 used in example a1 was replaced with 0.30 part by weight of the compound shown in compound examples (1 to 21).

(example A6)

A measurement sample was prepared in the same manner as in example a1, except that 0.30 part by weight of c.i. direct Black 19 used in example a1 was replaced with 1.0 part by weight of the compound shown in compound examples (1 to 10).

Comparative example A1

In example a1, a polarizing plate containing no azo dye was prepared as a measurement sample in the same manner as in example a1 except that the staining step after swelling was not carried out with an aqueous solution containing c.i. direct Black 19 having a structure represented by formula (101).

Comparative example A2

A measurement sample was prepared in the same manner as in example A1, except that 0.30 part by weight of C.I. direct Black 19 used in example A1 was replaced with 0.3 part by weight of the azo compound shown in example 1 of Japanese patent application laid-open No. 3-12606.

[ evaluation method ]

Evaluation of the measurement samples obtained in examples A1 to A6 and comparative examples A1 to A2 was carried out in the following manner.

(a) Single transmittance Ts for each wavelength, parallel bit transmittance Tp for each wavelength, and orthogonal bit transmittance Tc for each wavelength

The single transmittance Ts at each wavelength, the parallel bit transmittance Tp at each wavelength, and the orthogonal bit transmittance Tc at each wavelength of each measurement sample were measured using a spectrophotometer ("U-4100" manufactured by hitachi corporation). Here, the transmittance Ts of the monomer at each wavelength is a transmittance at each wavelength when the measurement sample is measured in 1 sheet. The parallel transmittance Tp for each wavelength is a transmittance for each wavelength measured by overlapping 2 measurement samples so that the absorption axis directions thereof are parallel to each other. The orthogonal transmittance Tc for each wavelength is a transmittance for each wavelength measured by overlapping 2 measurement samples so that the absorption axis directions thereof are orthogonal to each other. The measurements were performed at 5nm intervals covering wavelengths of 400 to 900 nm.

(b) Monomer transmittance Ys after visual sensitivity correction, parallel bit transmittance Yp after visual sensitivity correction, and quadrature bit transmittance Yc after visual sensitivity correction

According to JIS Z8722: 2009(C light source 2 ° field), each optical characteristic (transmittance, polarization degree, color phase, etc.) was calculated. The visibility correction is performed based on the C light source 2 DEG visual field color matching function, and the single transmittance Ys after the visibility correction, the parallel bit transmittance Yp after the visibility correction, and the orthogonal bit transmittance Yc after the visibility correction are calculated based on the visibility correction.

(c) Degree of polarization

The polarization degree ρ y is obtained from the parallel bit transmittance Yp after the visibility correction and the orthogonal bit transmittance Yc after the visibility correction according to the following equation (1).

ρy＝{(Yp-Yc)/(Yp+Yc)}^1/2×100 (1)

(d) Colour a and b

For each measurement sample, the reaction conditions were determined in accordance with JIS Z8781-4: 2013, when the monomer transmittance Ts is measured, the parallel bit transmittance Tp is measured, and the orthogonal bit transmittance Tc is measured, the respective chromaticity a and b are measured. The spectrophotometer described above was used for the measurement, and the light source used was a C light source. Here, a is a-s and b is a b, a is p and b is p, and a is c and b is a chromaticity a value and b value respectively corresponding to the measured chromaticity at the monomer transmittance Ts, the parallel bit transmittance Tp, and the orthogonal bit transmittance Tc.

The initial visibility-corrected monomer transmittance (Ys-s), the initial visibility-corrected orthosteric transmittance (Yc-s), the initial 780nm orthosteric transmittance (Tc780-s), and the initial orthosteric value (a < c-s) of the durability test samples obtained in examples A1 to 6, comparative examples A1, and A2, and the visibility-corrected monomer transmittance (Ys-e), the visibility-corrected orthosteric transmittance (Yc-e), the durability-corrected orthosteric transmittance (Tc-e), and the durability-corrected orthosteric value (a < c-e) after applying the durability test samples for 1000 hours at 105 ℃ are shown in Table A1. The polarizing element preferably has a value of transmittance at perpendicular position of 780nm (Tc780-e) after the durability test of 35 or less, more preferably 30 or less.

[ Table A1]

As shown in Table 1, it is understood that examples A1 to 6 have the same transmittance and the high degree of polarization as comparative examples A1 and 2. Further, it was found that, when applied at 105 ℃ for 1000 hours, the film exhibited less change in 780nm at the ortho position, less change in a-value, less change in color in appearance, and high durability, as compared with the conventional iodine polarizing plate (comparative example A1). That is, it was found that the polarizing plate obtained using the polarizing element of the present invention achieved a contrast equivalent to that of the conventional iodine polarizing plate, and maintained high durability even in an environment where durability such as high temperature was applied. As a result of the present application, a liquid crystal display device using the polarizing element or the polarizing plate of the present invention has high luminance and high contrast, and has high reliability and high contrast for a long period of time.

(e) Degree of polarization in the near infrared region

In examples A4 to A6, the monomer transmittance (Ts), the cross-site transmittance (Tc), and the degree of polarization (. rho.) were measured at 850 nm. The results are shown in Table A2.

[ Table A2]

As shown in table 2, examples a4 to 6 had a high polarization degree of 90% or more at 850nm in the infrared region. In contrast, in comparative example a1, the degree of co-polarization was less than 3%, and the polarizing performance was hardly observed. That is, the polarizing plate of the present application has a high degree of polarization in the visible light region, which is consistent with iodine, and a wide-band polarizing plate having a high degree of polarization up to the infrared region.

< example B >

[ preparation of measurement sample ]

(example B1)

A polyvinyl alcohol film (VF-PS, manufactured by Kuraray Co., Ltd.) having an average polymerization degree of 2400 or more and a saponification degree of 99% was immersed in warm water at 40 ℃ for 2 minutes, and subjected to swelling treatment so that the draw ratio became 1.30 times. Next, the swollen film was immersed in an aqueous solution containing the infrared light absorbing water-soluble compound for 13 minutes, the aqueous solution containing: 1500 parts by weight of water, 1.5 parts by weight of sodium tripolyphosphate, 1.5 parts by weight of anhydrous sodium sulfate, and c.i. direct Black 19 (shoxing BIYING TEXILE TECHNOLOGY Co., manufactured by LTD) having a structure represented by formula (101) below as a water-soluble compound which absorbs light in the infrared region of 700nm to 1400nm, 0.16 parts by weight of an azo compound represented by the present application compound example (5-1) as a compound of formula (5), 0.040 parts by weight of the azo compound represented by the above formula (10-22) as a compound having a structure of formula (10), 0.027 parts by weight of an azo compound represented by the present application compound example (10-2) as a compound having a structure of formula (10), 0.16 parts by weight of Kayarus Supra Orange 2GL 2 manufactured by japan chemical company, adjusted to 45 ℃. Then, the obtained membrane was immersed in an aqueous solution prepared by dissolving 40 parts by weight of boric acid (manufactured by Societa chimica polar research, p.a.) in 2000 parts by weight of water at 30 ℃ for 2 minutes. Next, the obtained film was subjected to an elongation treatment at 50 ℃ for 5 minutes in an aqueous solution containing 30.0g/l of boric acid so that the elongation ratio was 5.0 times. The obtained film was subjected to immersion treatment (washing treatment) in water at 20 ℃ for 20 seconds. Then, the obtained film was subjected to a drying treatment at 70 ℃ for 9 minutes to obtain a polarizing element. The obtained polarizing element was laminated with an alkali-treated triacetyl cellulose film (ZRD-60, manufactured by Fuji film Co.) using a polyvinyl alcohol adhesive to obtain a polarizing plate. The obtained polarizing plate maintains the optical characteristics of the polarizing element. The polarizing plate was cut into a square size of 40mm, and bonded to transparent plate glass with an adhesive layer (AD-ROC manufactured by Polatechno corporation) interposed therebetween, to prepare a durability test sample using the polarizing plate of the present application as a measurement sample of the present application.

(example B2)

A measurement sample was prepared in the same manner as in example B1, except that 0.30 part by weight of c.i.direct Black 19 used in example B1 was replaced with 0.30 part by weight of S0378 manufactured by FEW CHEMICAL company represented by the following formula (102).

(example B3)

A measurement sample was prepared in the same manner as in example B1, except that 0.30 part by weight of c.i. direct Black 19 used in example B1 was replaced with 0.30 part by weight of S2180 manufactured by FEW CHEMICAL company of formula (103).

(example B4)

A measurement sample was prepared in the same manner as in example B1, except that 0.30 part by weight of c.i. direct Black 19 used in example B1 was used in place of 0.30 part by weight of the compound shown in compound examples (1 to 10) of this application.

(example B5)

A measurement sample was prepared in the same manner as in example B1, except that 0.30 part by weight of c.i. direct Black 19 used in example B1 was used in place of 0.30 part by weight of the compound shown in compound examples (1 to 21) of this application.

(example B6)

A measurement sample was prepared in the same manner as in example B1, except that 0.30 part by weight of c.i. direct Black 19 used in example B1 was used in place of 1.0 part by weight of the compound shown in compound examples (1 to 10) of this application.

(example B7)

A measurement sample was prepared in the same manner as in example B6, except that 0.040 part by weight of the azo compound represented by the formula (10-22) used in example B6 was replaced with 0.30 part by weight of the azo compound represented by the formula (11-30).

(example B8)

A measurement sample was prepared in the same manner as in example B6 except that in example B6, 0.16 part by weight of the compound represented by compound example (5-1) of the present application and 0.040 part by weight of the compound represented by the above formula (10-22) were not used and 0.3 part by weight of C.I. direct Blue71 (compound examples 6-9 of the present application) was used instead of each other.

(example B9)

A measurement sample was prepared in the same manner as in example B6 except that in example B6, 0.16 part by weight of the compound represented by compound example (5-1) of the present application and 0.040 part by weight of the compound represented by the above formula (10-22) were not used and 0.3 part by weight of C.I. direct Blue69 (compound examples 6-19 of the present application) was used instead of each other.

(example B10)

A measurement sample was prepared in the same manner as in example B6, except that in example B6, 0.16 parts by weight of the compound represented by compound example (5-1) of the present application and 0.040 parts by weight of the compound represented by formula (10-22) were not used, but 0.3 parts by weight of the azo compound represented by compound example (6-7) of the present application was used instead, and the time during which the azo compound was contained was changed to 13 minutes to 9 minutes.

(example B11)

A measurement sample was prepared in the same manner as in example B10, except that in example B10, the time for containing the azo compound was changed to 9 minutes to 13 minutes.

(example B12)

A measurement sample was prepared in the same manner as in example B6, except that 0.027 parts by weight of the compound represented by the compound example (10-2) used in example B6 was replaced with 0.040 parts by weight of C.I. direct Red 81 in the compound example (10-1) having the structure of formula (10).

(example B13)

A measurement sample was prepared in the same manner as in example B6, except that 0.027 parts by weight of the compound shown in compound example (10-2) of the present application used in example B6 was replaced with 0.027 parts by weight of formula (9-23) which is an azo compound having the structure of formula (9).

(example B14)

A measurement sample was prepared in the same manner as in example B6, except that 0.16 part by weight of Kayarus Supra Orange 2GL used in example B6 was replaced with 0.16 part by weight of c.i. direct Orange 72.

(example B15)

A measurement sample was prepared in the same manner as in example B6, except that 0.16 part by weight of Kayarus Supra Orange 2GL used in example B6 was replaced with 0.16 part by weight of c.i. direct Orange 28.

Comparative example B1

A measurement sample was prepared in the same manner as in example B1, except that in example B1, 0.30 parts by weight of c.i. direct Black 19 was not used.

[ evaluation method ]

Evaluation of the measurement samples obtained in examples B1 to B15 and comparative example B1 was carried out in the following manner

(a) Monomer transmittance Ts, parallel bit transmittance Tp, and orthogonal bit transmittance Tc

The cell transmittance Ts, the parallel bit transmittance Tp, and the orthogonal bit transmittance Tc of each measurement sample were measured in the same manner as in the [ evaluation method ] (a) of example a.

The average value of the parallel bit transmittance Tp and the orthogonal bit transmittance Tc at each wavelength of 420 to 480nm, the average value of 520 to 590nm, the average value of 600 to 640nm, and the monomer transmittance at 800nm were determined. The results are shown in Table B1.

[ Table B1]

(b) Absolute value of difference in average transmittance of 2 wavelength bands

In table B2, the absolute value of the difference between the average value of each wavelength at 520 to 590nm and the average value of each wavelength at 420 to 480nm, and the absolute value of the difference between the average value of each wavelength at 520 to 590nm and the average value of each wavelength at 600 to 640nm are shown for each of the parallel bit transmittance Tp and the orthogonal bit transmittance Tc of each measurement sample.

[ Table B2]

(c) Monomer transmittance Ys after visual sensitivity correction, parallel bit transmittance Yp after visual sensitivity correction, and cross bit transmittance Yc after visual sensitivity correction

The single transmittance Ys after the sensitivity correction, the parallel bit transmittance Yp after the sensitivity correction, and the quadrature bit transmittance Yc after the sensitivity correction were obtained for each measurement sample. The monomer transmittance Ys after the sensitivity correction, the parallel bit transmittance Yp after the sensitivity correction, and the orthogonal bit transmittance Yc after the sensitivity correction are in a wavelength region of 400 to 700nm, and the monomer transmittance Ts, the parallel bit transmittance Tp of each wavelength, and the orthogonal bit transmittance Tc of each wavelength, which are obtained at predetermined wavelength intervals d λ (here, 5nm), are respectively in accordance with JIS Z8722: 2009 in the visibility correction. Specifically, the single transmittance Ts for each wavelength, the parallel bit transmittance Tp for each wavelength, and the orthogonal bit transmittance Tc for each wavelength are calculated by substituting the following expressions (V) to (VII). In the following formulas (V) to (VII), P λ represents the spectral distribution of the standard light (C light source), and y λ represents a 2-degree visual field color matching function. The results are shown in Table B3. In addition, at this time, a value of Yp divided by Yc may be expressed as a Contrast Ratio (CR).

[ mathematical formula 1]

(d) Polarization degree after visual sensitivity correction

The polarization degree ρ y after the visibility correction of each measurement sample is obtained from the parallel bit transmittance Yp after the visibility correction and the cross bit transmittance Yc after the visibility correction according to the following formula (VIII).

ρy＝{(Yp-Yc)/(Yp+Yc)}^1/2×100 (VIII)

(e) Colour a and b

A, b, a, c, b, c are measured in the same manner as in [ evaluation method ] (d) of example A.

The Ys, Yp, Yc, CR, ρ y, and chromaticity of examples B1 to B15 and comparative example B1 are shown in table B3.

[ Table B3]

Table B4 shows Tp, Tc and polarization degree in the infrared region wavelengths of 750nm, 800nm and 850nm in examples B1 to B15 and comparative example B1.

[ Table B4]

Table B5 shows Tp, Tc, and polarization degree in the wavelength of 700nm in the visible light region of examples B6, B10, B11, and comparative example B1 at the initial stage, and the values after applying each polarizing plate at 105 ℃ for 500 hours.

[ Table B5]

From the above-mentioned tables B1 and B2, it is understood that the polarizing element of the present invention, which is characterized by containing a base material of a water-soluble compound that absorbs light in the infrared region of 700nm to 1400nm, and in which the absolute value of the difference between the average value of the transmittance at each wavelength of 520nm to 590nm and the average value of the transmittance at each wavelength of 420nm to 480nm when measured with the absorption axes of 2 polarizing elements parallel is 5% or less, and the absolute value of the difference between the average value of the transmittance at each wavelength of 600nm to 640nm and the average value of the transmittance at each wavelength of 520nm to 590nm is 3% or less, or a polarizing plate using the same. According to Table B3, the obtained polarizing element has achromatic properties because a < a > s and B s are both within 1.0 in absolute value. In addition, a and b are both 2.0 or less in absolute value, so that the polarizing plate can realize high-quality white in parallel position. On the other hand, in comparative example B1, the absorption and polarization degree in the infrared region of 700nm or more were significantly low. In addition, from table B4, it can be seen that the polarizing plate of the present application can realize a colorless color while having a high degree of polarization in the infrared region. Further, as is clear from Table B5, a polarizing plate with little change in transmittance at 700nm in the visible light region and little change in polarization degree was obtained.

< example C >

[ preparation of measurement sample ]

(example C1)

A polyvinyl alcohol film (VF-PS, manufactured by Kuraray Co., Ltd.) having an average polymerization degree of 2400 or more and a saponification degree of 99% was immersed in warm water at 40 ℃ for 2 minutes, and subjected to swelling treatment so that the draw ratio became 1.30 times. Next, the swollen film was immersed in an aqueous solution containing 1500 parts by weight of water, 1.5 parts by weight of sodium tripolyphosphate, 1.5 parts by weight of anhydrous sodium sulfate, and 0.30 parts by weight of a water-soluble compound having a structure represented by the following formula (101) as a light-absorbing compound that absorbs light in the infrared region of 700nm to 1400nm (made by LTD Co., Ltd.), 0.22 parts by weight of an azo compound represented by the present application example (9-23) as an azo compound having a structure of the formula (9), 0.54 parts by weight of an azo compound represented by the following formula (11-45) as an azo compound having a structure of the formula (11), and 0.13 parts by weight of an azo compound represented by the present application example (13-2) as an azo compound having a structure of the formula (13) for 13 minutes to allow the film to contain the infrared-absorbing water-soluble compound, and adjusted to 45 ℃. Then, the obtained membrane was immersed in an aqueous solution prepared by dissolving 40 parts by weight of boric acid (manufactured by Societa chip lardrello. p.a.) in 2000 parts by weight of water at 30 ℃ for 2 minutes. Next, the obtained film was subjected to an elongation treatment at 50 ℃ for 5 minutes in an aqueous solution containing 30.0g/l of boric acid so that the elongation ratio was 5.0 times. The obtained film was subjected to immersion treatment (washing treatment) in water at 20 ℃ for 20 seconds. Then, the obtained film was subjected to a drying treatment at 70 ℃ for 9 minutes to obtain a polarizing element. The obtained polarizing element was laminated with an alkali-treated triacetyl cellulose film (ZRD-60, manufactured by Fuji film Co.) using a polyvinyl alcohol adhesive to obtain a polarizing plate. The obtained polarizing plate maintains the optical characteristics of the polarizing element. A durability test sample using the polarizing plate of the present application was prepared by cutting a polarizing plate into 40mm squares, and adhering the cut plates to a transparent plate glass with an adhesive layer (AD-ROC manufactured by Polatechno) interposed therebetween.

(example C2)

A measurement sample was prepared in the same manner as in example C1, except that 0.30 part by weight of c.i. direct Black 19 used in example C1 was replaced with S0378(0.30 part by weight) manufactured by FEW CHEMICAL and represented by formula (102).

(example C3)

A measurement sample was prepared in the same manner as in example C1, except that 0.30 part by weight of c.i. direct Black 19 used in example C1 was replaced with S2180(0.30 part by weight) manufactured by FEW CHEMICAL company represented by the following formula (103).

(example C4)

A measurement sample was prepared in the same manner as in example C1, except that 0.30 part by weight of c.i. direct Black 19 used in example C1 was replaced with 0.30 part by weight of the compound shown in compound examples (1 to 10).

(example C5)

A measurement sample was prepared in the same manner as in example C1, except that 0.30 part by weight of the infrared light-absorbing water-soluble compound used in example C1 was replaced with 0.30 part by weight of the compound shown in compound examples (1 to 21).

(example C6)

A measurement sample was prepared in the same manner as in example C1, except that 0.30 part by weight of c.i. direct Black 19 used in example C1 was replaced with 1.0 part by weight of the compound shown in compound examples (1 to 10).

(example C7)

A measurement sample was prepared in the same manner as in example C6, except that 0.54 part by weight of the compound shown in compound example (11-45) of the present application used in example C6 was replaced with 0.33 part by weight of the azo compound shown in compound example (11-5) of the present application.

(example C8)

A measurement sample was prepared in the same manner as in example C6, except that 0.54 part by weight of the compound shown in compound example (11-45) of the present application used in example C6 was replaced with 0.33 part by weight of the azo compound shown in compound example (12-12) of the present application.

(example C9)

A measurement sample was prepared in the same manner as in example C6, except that 0.54 part by weight of the compound shown in compound example (11-45) of the present application used in example C6 was replaced with 0.46 part by weight of the azo compound shown in compound example (11-14) of the present application.

(example C10)

A measurement sample was prepared in the same manner as in example C6, except that 0.22 part by weight of the compound shown in compound example (9-23) of the present application used in example C6 was replaced with 0.19 part by weight of C.I. DIRECT RED 81 (compound example 10-1 of the present application).

(example C11)

A measurement sample was prepared in the same manner as in example C6, except that 0.22 part by weight of the compound represented by the compound example (9 to 23) of the present application used in example C6 was replaced with 0.21 part by weight of the azo compound represented by the following formula (10 to 85).

(example C12)

A measurement sample was prepared in the same manner as in example C6, except that 0.22 part by weight of the compound shown in compound example (9-23) of the present application used in example C6 was replaced with 0.40 part by weight of the compound shown in compound example (10-51) of the present application.

(example C13)

A measurement sample was prepared in the same manner as in example C6, except that 0.13 part by weight of the compound shown in compound example (13-2) of the present application used in example C6 was replaced with 0.11 part by weight of C.I. direct Orange 72.

(example C14)

A measurement sample was prepared in the same manner as in example C6, except that 0.13 part by weight of the compound used in example C6 and shown in compound example (13-2) of the present application was replaced with 0.16 part by weight of c.i. direct Yellow 28.

Comparative example C1

A measurement sample was prepared in the same manner as in example C1, except that in example C1, 0.30 parts by weight of c.i. direct Black 19 was not used.

[ evaluation method ]

The measurement samples obtained in examples C1 to C14 and comparative example C1 were evaluated in the following manner (a) for the single transmittance Ts at each wavelength, the parallel bit transmittance Tp at each wavelength, and the orthogonal bit transmittance Tc at each wavelength

In the same manner as in [ evaluation method ] (a) of example a, the single transmittance Ts at each wavelength, the parallel bit transmittance Tp at each wavelength, and the orthogonal bit transmittance Tc at each wavelength of each measurement sample were measured.

In the same manner as in the [ evaluation method ] (c) of example B, the single-body transmittance Ys after the sensitivity correction, the parallel bit transmittance Yp after the sensitivity correction, and the quadrature bit transmittance Yc after the sensitivity correction were obtained for each measurement sample. The results are shown in Table C1. In addition, at this time, a value of Yp divided by Yc may be expressed as a Contrast Ratio (CR).

(d) Degree of polarization

The degree of polarization ρ y was determined in the same manner as in [ evaluation method ] (d) of example B.

The Ys, Yp, Yc, CR, ρ y of examples C1 to C14 and comparative example C1 are shown in table C1.

[ Table C1]

Table C2 shows Tp, Tc and polarization degree in the wavelengths of the near infrared region of 750nm, 800nm and 850nm in examples C1 to C14 and comparative example C1.

[ Table C2]

Table C3 shows Tp, Tc, and polarization degree at 700nm of the wavelength in the visible light region of the initial examples C6 and comparative examples C1, and the values after applying each polarizing plate at 105 ℃ for 500 hours.

[ Table C3]

From tables C1 and C2, it is understood that the polarizing element of the present application contains a water-soluble compound or a salt thereof that absorbs light in the infrared region of 700nm to 1400nm, and has a high degree of polarization in the visible region. In addition, from table C2, it is understood that the polarizing element of the present application absorbs light not only in the infrared region, but also has high polarizing performance. From this, it is understood that the polarizing element of the present invention has a high degree of polarization from the visible light region to the infrared region. Further, from table C3, it is understood that the polarizing plate with less transmittance at 700nm in the visible light region and less change in polarization degree is obtained, and the polarizing plate of the present invention has high durability.

As shown in tables C1 to C3, the polarizing element or the polarizing plate of the present invention has no color in the visible light region, but has absorption in the infrared region and a high degree of polarization, and thus a wide-band polarizing plate having a high degree of polarization up to the infrared region can be obtained. In addition, the polarizing plate is shown to achieve high durability in the visible light region.

[ industrial applicability ]

The polarizing element or polarizing plate of the present invention is used in optical devices such as liquid crystal displays, organic EL, liquid crystal projectors, electronic computers, clocks, notebook computers, document processing machines, liquid crystal televisions, polarizing lenses, polarizing glasses, navigators, and indoor and outdoor detectors, displays, infrared sensors, infrared cameras, optical isolators, and security systems. Particularly, the organic electroluminescence device can be effectively used in a reflective liquid crystal display device, a transflective liquid crystal display device, an organic electroluminescence device, and the like.

Claims

1. A polarizing element comprising: at least 1 kind of dichroism pigment showing polarization characteristic in visible light region, and water-soluble azo compound or its salt absorbing light of 700-1400 nm in infrared region;

wherein the at least 1 kind of dichroic dye is a compound represented by the following formula (6) or a salt thereof, a compound represented by the following formula (9) or formula (10), a metal complex compound thereof, or a salt thereof, an azo compound represented by the following formula (11), a metal complex compound thereof, or a salt thereof, or an azo compound represented by the following formula (12) or a salt thereof;

bg and Cg are each independently represented by the following formula (7) or the following formula (8), at least one of which represents formula (7),

k represents an integer of 0 to 2,

in the formula, Rg₂And Rg₃Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms and having a sulfo group;

Rc₁₁to Rc₁₄Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms and having a sulfo group;

Xc₂represents an amino group which may have at least 1 substituent selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a sulfo group, an alkylamino group having 1 to 4 carbon atoms, a hydroxyl group, an amino group, a substituted amino group, a carboxyl group, and a carboxyethylamino 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 benzoyl group which may have a substituent, or a benzoylamino group which may have a substituent,

p and q each independently represent an integer of 0 or 1,

but excluding the case where the compound represented by formula (10) is c.i. direct red 81;

d represents 0 or 1;

Rb₂₁represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms and having a sulfo group,

Xb₂represents an amino group which may have at least 1 substituent selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkylamino group having 1 to 4 carbon atoms, a hydroxyl group, a carboxyl group, a sulfo group, an amino group and a substituted amino 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, and a naphthotriazole group which may have a substituentA substituted benzoylamino group, or a substituted benzoyl group.

2. The polarizing element according to claim 1, wherein the azo compound is an azo compound represented by the following formula (1):

in the formula, Ai₁、Ai₂Each independently a hydrogen atom, an azo group, or a compound represented by the following formula (2) with the proviso that Ai is excluded₁、Ai₂Are all hydrogen atoms, and are,

-NH-is bonded to both naphthalene rings at any position of the combination of a and a ', b and b', a and b ', b and a',

m represents an integer of 1 to 3,

when Bi has a hydroxyl group as a substituent, the hydroxyl group can form-O-Cu-O-with the copper atom as the hydroxyl group in the above formula (1).

3. The polarizing element according to claim 1, wherein formula (2) is represented by formula (3):

4. The polarizing element according to claim 1, wherein the azo compound represented by the formula (1) is an azo compound represented by the following formula (4):

m is the same as in formula (2).

5. The polarizing element according to claim 1, wherein the at least 1 kind of dichroic dye is a compound represented by formula (6) or a salt thereof:

k represents an integer of 0 to 2,

6. The polarizing element according to claim 1, wherein the at least 1 kind of dichroic dye is a compound represented by formula (9) or formula (10), a metal complex compound thereof, or a salt thereof:

p and q each independently represent an integer of 0 or 1,

but excluding the case where the compound represented by formula (10) is c.i. direct red 81.

7. The polarizing element according to claim 1, wherein the at least 1 kind of dichroic dye is an azo compound represented by the following formula (11), a metal complex compound thereof, or a salt thereof, or an azo compound represented by the following formula (12), or a salt thereof:

d represents 0 or 1;

Rb₂₁represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms and having a sulfo group, Xb₂Represents an amino group which may have at least 1 substituent selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkylamino group having 1 to 4 carbon atoms, a hydroxyl group, a carboxyl group, a sulfo group, an amino group and a substituted amino group, a phenylamino group which may have a substituentAn azo group, 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.

8. The polarizing element according to claim 1, comprising an azo compound represented by the following formula (13) or a salt thereof:

wherein Ay1 represents a hydrogen atom, a sulfo group, a carboxyl group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms,

ry1 and Ry2 each independently represent a hydrogen atom, a sulfo group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms and having a sulfo group,

h is an integer from 1 to 3.

9. The polarizing element according to any one of claims 1 to 8, wherein the substrate is a polyvinyl alcohol resin film.

10. The polarizing element according to any one of claims 1 to 8, wherein a degree of polarization is 99% or more.

11. The polarizing element according to any one of claims 1 to 8, wherein in a transmittance determined in a state in which 2 sheets of the polarizing element are arranged one on top of another so that absorption axes thereof are parallel to each other,

12. The polarizing element according to any one of claims 1 to 8, wherein the refractive index is measured in accordance with JIS Z8781-4: 2013, the absolute values of a and b obtained by measuring the transmittance of natural light are each 1 or less in the polarizing element monomer, that is, -1. ltoreq. a.ltoreq.s.ltoreq.1, -1. ltoreq. b.ltoreq. s.ltoreq.1,

the state of the 2 pieces of the above-mentioned polarization elements overlapped with each absorption axis parallel to each other is 2 or less, that is, -2 < a > a 2, -2 p < 2,

a represents the a value of the monomer, b represents the b value of the monomer, a represents the a value in the parallel position, b represents the b value in the parallel position.

13. The polarizing element according to any one of claims 1 to 8, wherein in a transmittance determined in a state where 2 sheets of the polarizing element are stacked with their respective absorption axes orthogonal to each other,

14. A polarizing plate includes: the polarizing element according to any one of claims 1 to 13, and a transparent protective layer on at least one surface of the polarizing element.

15. An optical device, comprising: the polarizing element according to any one of claims 1 to 13 or the polarizing plate according to claim 14.

16. The optical device of claim 15, which is a liquid crystal display device.