JP2023052132A - Visible region and infrared region polarization element, and polarizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new polarization element, a polarizer and an optical device.

SOLUTION: The polarization element includes at lease one type of dichroic dye exhibiting polarization property in 400 nm to 700 nm, and water-soluble compound absorbing light of 700 nm to 1400 nm or salt thereof. The polarization element contains iodine as the at least one type of dichroic dye, and satisfies at least one of the conditions of having orthogonal transmissivity of 3.569% or less at wavelength of 780 nm and of having polarization degree of 90% or more at wavelength of 850 nm.

SELECTED DRAWING: None

COPYRIGHT: (C)2023,JPO&INPIT

Description

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

A polarizing film is generally produced by adsorbing and orienting a dichroic dye such as iodine or a dichroic dye on a polyvinyl alcohol-based resin film. A polarizing film using iodine as a dichroic dye is called an iodine-based polarizing film, while 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 attached to at least one side of these polarizing films via an adhesive layer to form a polarizing plate, which is used in a liquid crystal display device or the like. Iodine-based polarizing plates made of iodine-based polarizing films exhibit higher transmittance and a higher degree of polarization, that is, higher contrast than dye-based polarizing plates made of dye-based polarizing films. It is widely used in mobile phones, PDAs, and the like. However, although the iodine-based polarizing plate is superior to the dye-based polarizing plate in terms of optical properties, it is inferior to the dye-based polarizing plate in terms of optical durability. However, decolorization causes problems such as an increase in transmittance and a decrease in the degree of polarization. There is a demand for a polarizing plate with high transmittance and degree of polarization, high contrast, and excellent heat resistance and resistance to moisture and heat. For example, there is a demand for a polarizing plate that is also excellent in dry heat durability. Inventions to meet this demand include patents containing zinc such as Patent Documents 1 to 3, a polarizing plate obtained by treating with a triterpenoid glycoside such as Patent Document 4, and a polyvalent plate such as Patent Document 5. There is a technique for improving durability against heat by aldehyde. However, no polarizing plate that sufficiently satisfies the above requirements has been obtained, and there is a strong demand for a polarizing plate that can be manufactured inexpensively and easily, and that has high durability, such as improved dry heat durability.

A general polarizing plate is a polarizing film such as a stretch-oriented polyvinyl alcohol or its derivative film, or a polyene-based film obtained by generating polyene by dehydrochlorination of a polyvinyl chloride film or dehydration of a polyvinyl alcohol-based film. It is manufactured by dyeing or containing iodine or a dichroic dye as a polarizing element in a base material. Of these, the iodine-based polarizing film using iodine as the polarizing element has excellent polarizing performance, but it is weak against water and heat, and its durability deteriorates when used for a long time under high temperature and high humidity conditions. However, it has problems and cannot control the transmittance up to the infrared region. On the other hand, a dye-based polarizing film using a dichroic dye as a polarizing element is superior in moisture resistance and heat resistance to an iodine-based polarizing film, but is a polarizing plate having a polarizing function for wavelengths in the visible wavelength range, It was not a polarizing plate capable of controlling the transmittance in the infrared wavelength region.

In recent years, in applications such as recognition light sources for touch panels, security cameras, sensors, anti-counterfeiting devices, and communication devices, not only polarizing plates for visible wavelengths but also polarizing plates for use in the infrared region are in demand. In response to such a demand, an infrared polarizing plate obtained by converting an iodine-based polarizing plate into a polyene as in Patent Document 15, an infrared polarizing plate using wire grids as in Patent Documents 16 or 14, and an infrared polarizing plate such as Patent Document 17 Infrared polarizers in which glass containing fine particles is stretched and types using cholesteric liquid crystals as in Patent Documents 18 and 6 have been reported. In Patent Document 15, durability is weak, and heat resistance, wet heat durability, and light resistance are weak, and it has not reached practical use. The wire grid type as disclosed in Patent Documents 16 and 14 is becoming popular because it can be processed into a film type and is stable as a product. However, since the optical properties cannot be maintained without nano-level irregularities on the surface, the surface must not be touched, which limits the applications in which it can be used, and even requires anti-reflection and anti-glare processing. is difficult. A drawn glass type containing fine particles such as that disclosed in Patent Document 17 has high durability and high dichroism, and has been put to practical use. However, since the glass is stretched while containing fine particles, the element itself is fragile and fragile, and it lacks the flexibility of conventional polarizing plates, making surface processing and bonding to other substrates difficult. There was a problem. The technique of reference 5 is a technique using circularly polarized light that has been published for a long time. However, it is difficult to form absolutely polarized light. In other words, there has been no polarizing plate that is an absorptive polarizing element like a general polarizing plate, is a film type, has flexibility, and is compatible with the infrared wavelength region and has high durability.

JP-A-61-175602 JP-A-2003-50318 Japanese Patent Application Laid-Open No. 2003-29042 JP 2005-241689 A JP-A-6-235815 JP-A-2-167791 JP-A-61-221264 Japanese Patent Publication No. 2006-508034 JP-A-63-33477 WO2013/035560 JP-A-59-11385 JP 2010-106248 A Japanese Patent Application Laid-Open No. 2001-181184 JP 2013-24982 A U.S. Pat. No. 2,494,686 JP 2016-148871 A Japanese Patent Application Laid-Open No. 2004-86100 JP 2013-64798 A JP 2004-251962 A JP-A-2001-033627 Japanese Patent Application Laid-Open No. 2001-290029 JP 2010-072548 A JP 2007-084803 A JP 2007-238888 A

Application of functional dyes 1st printing edition, CMC Publishing Co., Ltd., supervised by Masahiro Irie, pp98-100 Dye Chemistry; Written by Yutaka Hosoda, 1957, page 621

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

As a result of intensive studies aimed at solving the above problems, the present inventors have developed a novel polarizing element containing a water-soluble compound or a salt thereof that absorbs light in the infrared region.

In one aspect, the polarizing element of the present invention contains iodine

In one aspect, the polarizing element of the present invention is produced with a specific transmittance set.

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

式中、Ａｉ_１、Ａｉ_２は各々独立に水素原子、アゾ基、又は下記式（２）（ただし、Ａｉ_１、Ａｉ_２がともに水素原子であるものは除く）で表され、
－ＮＨ－は、ａとａ’、ｂとｂ’、ａとｂ’、ｂとａ’の組合せのいずれかの位置で両ナフタレン環と結合し、

式中、Ｒｉ_１が置換している環は、各々独立に、破線で表される環が存在しない場合にはベンゼン環であり、破線で表される環が存在する場合にはナフタレン環であり、
Ｒｉ_１は各々独立に、塩素原子、スルホ基、ニトロ基、ヒドロキシ基、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、スルホ基を有する炭素数１～４のアルキル基、ヒドロキシ基を有する炭素数１～４のアルキル基、カルボキシ基を有する炭素数１～４のアルキル基、スルホ基を有する炭素数１～４のアルコキシ基、ヒドロキシ基を有する炭素数１～４のアルコキシ基、又はカルボキシ基を有する炭素数１～４のアルコキシ基であり、
Ｂｉは各々独立に、置換基を有してもよいフェニル基又は置換基を有してもよいナフチル基であり、前記置換基は、水素原子、塩素原子、スルホ基、ニトロ基、ヒドロキシ基、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、スルホ基を有する炭素数１～４のアルキル基、ヒドロキシ基を有する炭素数１～４のアルキル基、カルボキシ基を有する炭素数１～４のアルキル基、スルホ基を有する炭素数１～４のアルコキシ基、ヒドロキシ基を有する炭素数１～４のアルコキシ基、又はカルボキシ基を有する炭素数１～４のアルコキシ基であり、
ｍは１～３の整数を示し、
Ｂｉがヒドロキシ基を置換基として有する場合、前記ヒドロキシ基は上記式（１）中のヒドロキシ基と銅原子とで－Ｏ－Ｃｕ－Ｏ－を形成することが可能である。）
発明４
式（２）が式（３）で表される発明１～３のいずれか一項に記載の偏光素子：

式中、Ｒｉ_１が置換されている環、Ｒｉ_１、ｍはそれぞれ式（２）と同じであり、
－Ｏ－結合で表される酸素原子は式（１）中の－ＯＨ及び銅原子とで－Ｏ－Ｃｕ－Ｏ－を形成し、
Ｒｉ_２は水素原子、塩素原子、スルホ基、ニトロ基、ヒドロキシ基、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、スルホ基を有する炭素数１～４のアルキル基、ヒドロキシ基を有する炭素数１～４のアルキル基、カルボキシ基を有する炭素数１～４のアルキル基、スルホ基を有する炭素数１～４のアルコキシ基、ヒドロキシ基を有する炭素数１～４のアルコキシ基、又はカルボキシ基を有する炭素数１～４のアルコキシ基である。
発明５
前記式（１）で表されるアゾ化合物が、下記式（４）で表されるアゾ化合物である発明１～４のいずれか一項に記載の偏光素子：

式中、Ｒｉ_３は水素原子、塩素原子、スルホ基、ニトロ基、ヒドロキシ基、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、スルホ基を有する炭素数１～４のアルキル基、ヒドロキシ基を有する炭素数１～４のアルキル基、カルボキシ基を有する炭素数１～４のアルキル基、スルホ基を有する炭素数１～４のアルコキシ基、ヒドロキシ基を有する炭素数１～４のアルコキシ基、又はカルボキシ基を有する炭素数１～４のアルコキシ基であり、
ｍは式（２）と同じである。
発明６
前記少なくとも１種の二色性色素が式（５）または式（６）で示される化合物又はその塩である、発明１～５のいずれか一項に記載の偏光素子：

式中、Ａｂ_１、Ａｂ_２はそれぞれ独立に、置換基を有するナフチル基又は置換基を有するフェニル基を示し、その置換基の少なくとも１つが水素原子、スルホ基、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、スルホ基を有する炭素数１～４のアルコキシ基、カルボキシ基、ニトロ基、アミノ基、又は置換アミノ基であり、
Ｒｂ_１、Ｒｂ_２は各々独立に、水素原子、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、スルホ基、又はスルホ基を有する炭素数１～４のアルコキシ基を示し、

式中、Ａｇ_１は置換基を有するフェニル基または置換基を有するナフチル基を示し、
ＢｇおよびＣｇは、各々独立に、下記式（７）または下記式（８）で表され、少なくとも一方が式（７）を示し、
Ｘｇ_１は、置換基を有していてもよいアミノ基、置換基を有していてもよいフェニルアミノ基、置換基を有していてもよいフェニルアゾ基、または置換基を有していてもよいベンゾイルアミノ基を示し、

式中、Ｒｇ_１は水素原子、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、またはスルホ基を有する炭素数１～４のアルコキシ基を示し、
ｋは０～２の整数を示し、

式中、Ｒｇ_２およびＲｇ_３は各々独立に水素原子、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、またはスルホ基を有する炭素数１～４のアルコキシ基を示す。
発明７
前記少なくとも１種の二色性色素が下記式（９）又は式（１０）で示される化合物、その金属錯体化合物、又はその塩である、発明１～６のいずれか一項に記載の偏光素子：

式中、Ａｃ_１は、スルホ基及びカルボキシ基からなる群から選択される置換基を少なくとも１つ有するフェニル基又はナフチル基を表し、
Ｒｃ_１１～Ｒｃ_１４は、各々独立して、水素原子、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、又はスルホ基を有する炭素数１～４のアルコキシ基を表し、

式中、Ａｃ_２は、スルホ基及びカルボキシ基からなる群から選択される置換基を少なくとも１つ有するフェニル基又はナフチル基を表し、
Ｒｃ_２１～Ｒｃ_２５は、各々独立して、水素原子、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、又はスルホ基を有する炭素数１～４のアルコキシ基を表し、
Ｒｃ_２６は、水素原子、炭素数１～４のアルキル基、又はスルホ基を有する炭素数１～４のアルコキシ基を表し、
Ｘｃ_２は、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、スルホ基、炭素数１～４のアルキルアミノ基、ヒドロキシ基、アミノ基、置換アミノ基、カルボキシ基、及びカルボキシエチルアミノ基からなる群から選択される置換基を少なくとも１つ有していてもよいアミノ基、置換基を有してもよいフェニルアミノ基、置換基を有してもよいフェニルアゾ基、置換基を有してもよいナフトトリアゾール基、置換基を有してもよいベンゾイル基、又は置換基を有してもよいベンゾイルアミノ基を表し、
ｐ、ｑはそれぞれ独立に０又は１の整数を表す。
発明８
前記少なくとも１種の二色性色素が下記式（１１）で示されるアゾ化合物、その金属錯体化合物又はその塩、又は、式（１２）で示されるアゾ化合物又はその塩である、発明１～７のいずれか一項に記載の偏光素子：

式中、Ａｂ_１は、スルホ基及びカルボキシ基からなる群から選択される置換基を少なくとも１つ有するフェニル基又はナフチル基を表し、
Ｒｂ_１１～Ｒｂ_１４は、各々独立して、水素原子、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基又はスルホ基を有する炭素数１～４のアルコキシ基を表し、Ｒｂ_１５及びＲｂ_１６は、各々独立して炭素数１～４のアルコキシ基を示し、
Ｘｂ_１は、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、スルホ基、アミノ基、炭素数１～４のアルキルアミノ基、ヒドロキシ基、カルボキシ基及びカルボキシエチルアミノ基からなる群から選択される置換基を少なくとも１つ有していてもよいアミノ基、置換基を有してもよいフェニルアミノ基、置換基を有してもよいフェニルアゾ基、置換基を有してもよいナフトトリアゾール基、置換基を有してもよいベンゾイルアミノ基、または置換基を有してもよいベンゾイル基を表し、
ｄは０または１を表し；

式中、Ａｂ_２は、スルホ基及びカルボキシ基からなる群から選択される置換基を少なくとも１つ有するフェニル基又はナフチル基を表し、
Ｒｂ_２１は水素原子、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、又はスルホ基を有する炭素数１～４のアルコキシ基を表し、Ｘｂ_２は、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、炭素数１～４のアルキルアミン基、ヒドロキシ基、カルボキシ基、スルホ基、アミノ基及び置換アミノ基からなる群から選択される置換基を少なくとも１つ有してもよいアミノ基、置換基を有してもよいフェニルアミノ基、置換基を有してもよいフェニルアゾ基、置換基を有してもよいナフトトリアゾール基、置換基を有してもよいベンゾイルアミノ基、または置換基を有してもよいベンゾイル基を表す。
発明９
前記少なくとも１種の二色性色素が下記式（１３）で示されるアゾ化合物又はその塩である、発明１～８のいずれか一項に記載の偏光素子：

式中、Ａｙ_１は、水素原子、スルホ基、カルボキシ基、ヒドロキシ基、炭素数１～４のアルキル基、又は炭素数１～４のアルコキシ基を表し、
Ｒｙ_１及びＲｙ_２は、各々独立して、水素原子、スルホ基、炭素数１～４のアルキル基、又は炭素数１～４のアルコキシ基、又はスルホ基を有する炭素数１～４のアルコキシ基を表し、
ｈは１～３の整数である。
発明１０
前記少なくとも１種の二色性色素がヨウ素である、発明１～９のいずれか一項に記載の偏光素子。
発明１１
基材が、ポリビニルアルコール系樹脂フィルムである発明１～１０のいずれか一項に記載の偏光素子。
発明１２
偏光度が９９％以上である発明１～１１のいずれか一項に記載の偏光素子。
発明１３
前記偏光素子２枚を、各々の吸収軸が互いに平行になるように重ねて配置した状態で求められる透過率において、
５２０ｎｍ～５９０ｎｍの各波長の平均透過率と４２０ｎｍ～４８０ｎｍの各波長の平均透過率との差が絶対値として５％以下であり、かつ、６００ｎｍ～６４０ｎｍの各波長の平均透過率と５２０ｎｍ～５９０ｎｍの各波長の平均透過率の平均値との差が絶対値として３％以下である、
発明１～１２のいずれか一項に記載の偏光素子。
発明１４
ＪＩＳ Ｚ ８７８１－４：２０１３に従い、自然光の透過率測定時に求められるａ＊値及びｂ＊値の絶対値が、
前記偏光素子単体で、ともに１以下（－１≦ａ＊－ｓ≦１、－１≦ｂ＊－ｓ≦１）であり、
前記偏光素子２枚を、各々の吸収軸が互いに平行になるよう重ねて配置した状態で、ともに２以下（－２≦ａ＊－ｐ≦２、－２≦ｂ＊－ｐ≦２）である、
発明１～１３のいずれか一項に記載の偏光素子（ａ＊－ｓは単体でのａ＊値を示し、ｂ＊－ｓは単体でのｂ＊値を示し、ａ＊－ｐは平行位でのａ＊値を示し、ｂ＊－ｐは平行位でのｂ＊を示す）。
発明１５
前記偏光素子２枚を、各々の吸収軸が互いに直交するように重ねて配置した状態で求められる透過率において、
５２０ｎｍ～５９０ｎｍの各波長の平均透過率と４２０ｎｍ～４８０ｎｍの各波長の平均透過率との差が絶対値として３％以下であり、かつ、６００ｎｍ～６４０ｎｍの各波長の平均透過率と５２０ｎｍ～５９０ｎｍの各波長の平均透過率との差が絶対値として２％以下である、
発明１～１４のいずれか一項に記載の偏光素子。
発明１６
発明１～１５のいずれか一項に記載の偏光素子と、該偏光素子の少なくとも一方の面に透明保護層を備えた偏光板。
発明１７
発明１～１５のいずれか一項に記載の偏光素子又は発明１６に記載の偏光板を含む光学装置。
発明１８
液晶表示装置である、発明１７に記載の光学装置。 That is, the gist and configuration of the present invention are as follows.
Invention 1
A polarizing element comprising at least one dichroic dye exhibiting polarization characteristics in the visible region and a water-soluble compound or its salt absorbing 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):

wherein Ai ₁ and Ai ₂ are each independently represented by a hydrogen atom, an azo group, or the following formula (2) (excluding those in which both Ai ₁ and Ai ₂ are hydrogen atoms),
—NH— is bound to both naphthalene rings at any position of combinations of a and a′, b and b′, a and b′, and b and a′,

In the formula, each of the rings substituted by Ri ₁ is independently a benzene ring when the ring represented by the dashed line does not exist, and a naphthalene ring when the ring represented by the dashed line exists. ,
Ri ₁ each independently represents a chlorine atom, a sulfo group, a nitro group, a hydroxy 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 having a sulfo group, C1-4 alkyl group having a hydroxy group, C1-4 alkyl group having a carboxy group, C1-4 alkoxy group having a sulfo group, C1-4 alkoxy group having a hydroxy group or an alkoxy group having 1 to 4 carbon atoms having a carboxy group,
Each Bi is independently a phenyl group which may have a substituent or a naphthyl group which may have a substituent, and the substituents may be a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxy group, Alkyl groups with 1 to 4 carbon atoms, alkoxy groups with 1 to 4 carbon atoms, alkyl groups with sulfo groups with 1 to 4 carbon atoms, alkyl groups with hydroxy groups with 1 to 4 carbon atoms, and carbon atoms with carboxy groups an alkyl group of 1 to 4, an alkoxy group of 1 to 4 carbon atoms having a sulfo group, an alkoxy group of 1 to 4 carbon atoms having a hydroxy group, or an alkoxy group of 1 to 4 carbon atoms having a carboxy group;
m represents an integer of 1 to 3,
When Bi has a hydroxy group as a substituent, the hydroxy group can form -O-Cu-O- with the hydroxy group in the above formula (1) and the copper atom. )
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, the ring in which Ri ₁ is substituted, Ri ₁ and m are respectively the same as in formula (2),
The oxygen atom represented by the -O- bond forms -O-Cu-O- with -OH and the copper atom in formula (1),
Ri ₂ is a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxy 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 having a sulfo group, hydroxy C 1-4 alkyl group having a group, C 1-4 alkyl group having a carboxy group, C 1-4 alkoxy group having a sulfo group, C 1-4 alkoxy group having a hydroxy group , or an alkoxy group having 1 to 4 carbon atoms having a carboxy group.
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, Ri ₃ is a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkyl having 1 to 4 carbon atoms having a sulfo group. C 1-4 alkyl group having a hydroxy group, C 1-4 alkyl group having a carboxy group, C 1-4 alkoxy group having a sulfo group, C 1-4 having a hydroxy group or an alkoxy group having 1 to 4 carbon atoms having a carboxy group,
m is the same as in formula (2).
Invention 6
The polarizing element according to any one of Inventions 1 to 5, wherein the at least one dichroic dye is a compound represented by formula (5) or formula (6) or a salt thereof:

In the formula, Ab ₁ and Ab ₂ each independently represent a substituted naphthyl group or a substituted phenyl group, at least one of which is a hydrogen atom, a sulfo group, or an alkyl group having 1 to 4 carbon atoms. , an alkoxy group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, a carboxy group, a nitro group, an amino group, or a substituted amino group;
Rb ₁ and Rb ₂ each 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 having a sulfo group;

wherein Ag ₁ represents 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), at least one of which represents formula (7),
Xg ₁ is an optionally substituted amino group, an optionally substituted phenylamino group, an optionally substituted phenylazo group, or an optionally substituted showing a good benzoylamino group,

In the formula, Rg ₁ 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;
k represents an integer of 0 to 2,

In the formula, Rg ₂ and Rg ₃ each independently represent 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 sulfo group and having 1 to 4 carbon atoms.
Invention 7
The polarizing element according to any one of Inventions 1 to 6, wherein the at least one dichroic dye is a compound represented by the following formula (9) or formula (10), a metal complex compound thereof, or a salt thereof. :

wherein Ac ₁ represents a phenyl or naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group;
Rc ₁₁ to Rc ₁₄ each 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 sulfo group and having 1 to 4 carbon atoms;

wherein Ac ₂ represents a phenyl or naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group;
Rc ₂₁ to Rc ₂₅ each independently represent 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 sulfo group and having 1 to 4 carbon atoms;
Rc ₂₆ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms having a sulfo group;
Xc ₂ is 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 hydroxy group, an amino group, a substituted amino group, a carboxy group, and a carboxy an amino group optionally having at least one substituent selected from the group consisting of an ethylamino group, a phenylamino group optionally having a substituent, a phenylazo group optionally having a substituent, a substituent Represents a naphthotriazole group which may have a, 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
Inventions 1 to 7, wherein the at least one 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 formula (12) or a salt thereof. The polarizing element according to any one of

wherein Ab ₁ represents a phenyl or naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group;
Rb ₁₁ to Rb ₁₄ each independently represent 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 a _sulfo group; and Rb ₁₆ each independently represents an alkoxy group having 1 to 4 carbon atoms,
Xb ₁ consists 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 hydroxy group, a carboxy group and a carboxyethylamino group. an amino group optionally having at least one substituent selected from the group, a phenylamino group optionally having a substituent, a phenylazo group optionally having a substituent, a substituent optionally having represents a naphthotriazole group, an optionally substituted benzoylamino group, or an optionally substituted benzoyl group,
d represents 0 or 1;

wherein Ab ₂ represents a phenyl or naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group;
Rb ₂₁ 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 having a sulfo group; at least one substituent selected from the group consisting of an alkyl group, an alkoxy group having 1 to 4 carbon atoms, an alkylamine group having 1 to 4 carbon atoms, a hydroxy group, a carboxy group, a sulfo group, an amino group and a substituted amino group; optionally substituted amino group, optionally substituted phenylamino group, optionally substituted phenylazo group, optionally substituted naphthotriazole group, optionally substituted It represents a benzoylamino group or a benzoyl group which may have a substituent.
Invention 9
The polarizing element according to any one of Inventions 1 to 8, wherein the at least one dichroic dye is an azo compound represented by the following formula (13) or a salt thereof:

In the formula, Ay ₁ represents a hydrogen atom, a sulfo group, a carboxy group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms,
Ry ₁ and Ry ₂ are each independently 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 having a sulfo group. represents
h is an integer from 1 to 3;
Invention 10
The polarizing element according to any one of Inventions 1 to 9, wherein the at least one dichroic dye is iodine.
Invention 11
The polarizing element according to any one of Inventions 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, which has a degree of polarization of 99% or more.
Invention 13
The transmittance obtained when the two polarizing elements are stacked so that their absorption axes are parallel to each other,
The difference between the average transmittance of each wavelength of 520 nm to 590 nm and the average transmittance of each wavelength of 420 nm to 480 nm is 5% or less as an absolute value, and the average transmittance of each wavelength of 600 nm to 640 nm and 520 nm to 590 nm The difference between the average value of the average transmittance of each wavelength is 3% or less as an absolute value,
The polarizing element according to any one of Inventions 1 to 12.
Invention 14
According to JIS Z 8781-4: 2013, the absolute values of the a* and b* values obtained when measuring the transmittance of natural light are
Both of the polarizing elements alone are 1 or less (-1 ≤ a*-s ≤ 1, -1 ≤ b*-s ≤ 1),
When the two polarizing elements are stacked so that their absorption axes are parallel to each other, both are 2 or less (-2 ≤ a*-p ≤ 2, -2 ≤ b*-p ≤ 2). ,
The polarizing element according to any one of Inventions 1 to 13 (a*-s indicates an a* value of a single unit, b*-s indicates a b* value of a single unit, and a*-p is a parallel position and b*-p indicates b* in the parallel position).
Invention 15
In the transmittance obtained in a state in which the two polarizing elements are stacked so that their absorption axes are orthogonal to each other,
The difference between the average transmittance of each wavelength of 520 nm to 590 nm and the average transmittance of each wavelength of 420 nm to 480 nm is 3% or less as an absolute value, and the average transmittance of each wavelength of 600 nm to 640 nm and 520 nm to 590 nm The difference between the average transmittance of each wavelength is 2% or less as an absolute value,
The polarizing element according to any one of Inventions 1 to 14.
Invention 16
A polarizing plate comprising the polarizing element according to any one of Inventions 1 to 15 and a transparent protective layer 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 optical device according to Invention 17, which is a liquid crystal display device.

The polarizing element of the present invention has high polarizing properties in the visible region and absorbs light in the infrared region. In one aspect, it has high polarizing performance over a wide band from the visible region to the infrared region. In one embodiment, the polarizing element of the present invention is used not only for polarizing plates and liquid crystal display devices, but also for sensors and security devices that function with light from the visible region to the infrared region, and sensing light from the visible region to the infrared region. It can be used for a camera or the like capable of

In one aspect, the polarizing element of the present invention has a high transmittance and a high contrast comparable to those of an iodine-based polarizing plate, and also has high durability (moisture resistance, heat resistance, and/or light resistance), particularly high heat resistance. have.

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

In one aspect, the polarizing element of the present invention has an achromatic color in the visible region, absorption in the infrared region, and high durability.

In this specification, a water-soluble compound or a salt thereof that absorbs light in the infrared region may be abbreviated as an "infrared light-absorbing water-soluble compound."

In the claims and the specification of the present application, the "substituent" may include a hydrogen atom, and therefore the hydrogen atom is sometimes described as a "substituent" for convenience. The phrase "optionally having a substituent" means that the case where no substituent is included is also included. For example, "a phenyl group which may have a substituent" includes a simple unsubstituted phenyl group and a phenyl group having a substituent. In addition, unless otherwise specified, "lower" such as a lower alkyl group and a lower alkoxy group in the present application means having 1 to 4 carbon atoms, preferably 1 to 3 carbon atoms.

Examples of the "lower aliphatic hydrocarbon group (having 1 to 4 carbon atoms)" include, for example, straight-chain alkyl groups such as methyl group, ethyl group, n-propyl group, n-butyl group, sec-butyl group, tert- A branched alkyl group such as a butyl group, an unsaturated hydrocarbon group such as a vinyl group, and the like are included.

Examples of the "lower alkoxy group (having 1 to 4 carbon atoms)" include methoxy group, ethoxy group, propoxy group, n-butoxy group, sec-butoxy group, tert-butoxy group and the like.

In the present specification, all of "azo compound or its salt" or "azo compound, its metal complex compound, or its salt" may be simply referred to as "azo compound".

[Polarizing element]
The present application relates to a polarizing element containing at least one dichroic dye exhibiting polarization characteristics in the visible region and a water-soluble compound or its salt absorbing light in the infrared region.

Dichroic dyes that exhibit polarization properties in the visible region are generally known to be compounds composed of iodine and iodine compounds such as potassium iodide and lithium iodide. Other dichroic dyes include: It is known that the dye described in Non-Patent Document 1 is used. Specifically, examples of iodine-based polarizing plates include Patent Documents 21 and 22, and examples of dye-based polarizing plates include Patent Documents 19 and 20. A dye-based polarizing plate capable of polarization control of only a specific wavelength can be cited. As for the polarizing plate, Patent Documents 23 and 24 can be mentioned, and dichroic dyes having a polarizing function in the visible range can be mentioned. In particular, it is preferable to use the azo dyes described in formulas (5) to (14) described later, because an achromatic polarizing plate and a polarizing plate with higher performance can be obtained.

(Water-soluble compound that absorbs light in the infrared region)

By using an infrared light-absorbing water-soluble compound capable of absorbing light in the near-infrared region, the polarizing element of the present invention can be imparted with high durability. It is preferable to use a dye having a maximum absorption in the near-infrared region, particularly 700 to 1400 nm. A dye having a maximum absorption at 700 to 1100 nm, more preferably 700 to 1000 nm, and particularly preferably 700 to 900 nm is used.

Types of the above infrared light absorbing water-soluble compounds include phthalocyanine-based, naphthalocyanine-based, metal complex-based, boron complex-based, cyanine-based, squarylium-based, diimonium-based, diphenylamine/triphenylamine-based, quinone-based and azo-based compounds. etc. In general, these dyes have longer absorption wavelengths by extending the existing π-conjugated system, and exhibit a wide variety of absorption wavelengths depending on their structures. Also, most of them take the form of hydrophobic dyes or pigments, but they can also be used as hydrophilic dyes by making them water-soluble.

The phthalocyanine-naphthalocyanine system is a dye having a planar structure and a wide π-conjugated plane. Various absorptions are exhibited by the central metal represented by M ₁ in the general formula (A-1). , W, Mn, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, Ag, Au, Zn, Cd, Hg, Al, Ga, In, Si, Ge, Sn, Pb, Sb etc. VO, GeO, TiO etc. are mentioned as a metal oxide. Examples of metal hydroxides include Si(OH) ₂ , Cr(OH) ₂ , Sn(OH) ₂ and AlOH. Examples of metal halides include SiCl ₂ , VCl, VCl ₂ , VOCl, FeCl, GaCl, ZrCl, AlCl and the like. Among these, metal atoms such as Fe, Co, Cu, Ni, Zn, Al, and V, metal oxides such as VO, and metal hydroxides such as AlOH are preferred, and metal oxides such as VO are more preferred. Although it is usually used as a pigment, it can be dissolved in water by imparting a water-soluble group, as in general formula 1 described in JP-A-2-167791.

The dye represented by the following general formula (A-1) is preferably a dye represented by, for example, the following compound example (A-1-1). The dashed aromatic ring in general formula (A-1) means that it may or may not be present. e and f in the compound example (A-1-1) each independently represents an integer of 0 to 12, indicating that the sum of e and f is 0 to 12, especially e is 1 to 4 and f is 0 is preferably

A quinone-based dye has a wide absorption range and is represented by the following general formula (A-2). In the formula, Ar ₁ and Ar ₂ preferably have a cyclic structure composed of an aromatic ring or a heterocyclic ring, and a heterocyclic ring is more preferred for lengthening the absorption wavelength. Examples thereof include anthraquinone dyes as described in JP-A-61-221264. In addition, these rings may have a substituent, for example, an optionally substituted amino group, nitro group, sulfo group, alkyl group, alkoxy group, alkyl group having a sulfo group, 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 is a hydrogen adduct NH, an alkyl group having 1 to 4 carbon atoms, or a nitrogen atom substituted with a phenyl group which may have a substituent. .
Most of the quinone-based compounds are hydrophobic, and some have been reported to be soluble in water by adding a water-soluble group. Examples thereof include indanthrone dyes as described in JP-T-2006-508034.
The amino group which may have a substituent represents a substituted or unsubstituted amino group, and the substituted amino group includes a monomethylamino group, a monoethylamino group, a monobutylamino group, a monophenylamino group and the like. Di-substituted amino groups such as a mono-substituted amino group, a dimethylamino group, a diethylamino group, a dibutylamino group, a diphenylamino group and a methylphenylamino group can be mentioned. Alkyl groups include straight-chain alkyl groups such as methyl, ethyl, propyl, n-butyl and n-octyl groups, branched-chain alkyl groups such as isopropyl, secondary butyl and tertiary butyl groups, and cyclopentyl groups. , a cyclic alkyl group such as a cyclohexyl group, and the like. Alkoxy groups include methoxy, ethoxy, propoxy, and butoxy groups. The alkyl group having a sulfo group includes sulfomethyl group, sulfoethyl group, sulfopropyl group, sulfobutyl group and the like. The alkyl group having a hydroxyl group includes a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, a hydroxybutyl group and the like.

The dye represented by general formula (A-2) below is preferably, for example, a dye represented by compound example (A-2-1) below. n in the compound example (A-2-1) 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 a free Both forms and salt forms may be included in any proportion.

Cyanine-based dyes have strong absorption in the near-infrared region and are represented by general formula (A-3) or general formula (A-4), where Ar ₃ to Ar ₆ represent heterocycles. Examples of heterocyclic rings include thiazole ring, benzothiazole ring, naphthothiazole ring, thiazoline ring, oxazole ring, benzoxazole ring, naphthoxazole ring, oxazoline ring, selenazole ring, benzoselenazole ring, naphthoselenazole ring, quinoline ring, and the like. and preferably a benzothiazole ring or a naphthothiazole ring. Each heterocyclic ring may have an optional substituent, and preferably has an aqueous solution group. Examples of the water-soluble group include a sulfo group, a hydroxyl group, an alkyl group having a sulfo group, and an alkyl group having a hydroxyl group. These substituents may be substituted on the rings of Ar ₃ to Ar ₆ or bonded to the nitrogen atom in the heterocyclic ring. The number c of methine chains in general formula (A-3) is represented by an integer of 1 to 7, with 3 to 5 being particularly preferred. This methine chain may optionally have a substituent _R4 , such as a phenyl group optionally having a substituent. When c is 2 or more and there are a plurality of R ₄ s, each R ₄ may be the same or different. Ar ₇ in the general formula (A-4) represents a cyclic skeleton having 5 to 7 carbon atoms, and the substituent W is a halogen, an optionally substituted phenylamino group, an optionally substituted phenoxy group, a phenylthio group optionally having a substituent, and the like. The substituent in this case may have a water-soluble group. In addition, this dye is an intramolecular salt type or an intermolecular salt type, and in the case of an intermolecular salt type, a halide salt, a perchlorate, an antimony fluoride salt, a phosphorus fluoride salt, a boron fluoride salt, a trifluoro organic salts such as romethanesulfonate, bis(trifluoromethane)sulfonic acid imide salt, naphthalenesulfonic acid, and the like; Specific examples include indocyanine green and water-soluble dyes described in JP-A-63-33477. For example, the following compound examples (A-3-1) and (A-4-1) to (A- 4-3). The alkyl group having a sulfo group and the alkyl group having a hydroxyl group may be the same as those described above. Examples of the halogen include fluorine, chlorine, bromine, and iodine, and chlorine is preferred.

Squarylium-based dyes, which have a similar structure to cyanine-based dyes, are dyes having squaric acid as a central skeleton, as represented by the following general formula (A-5). Ar ₈ and Ar ₉ in general formula (A-5) desirably have a heterocyclic ring similar to that of the cyanine system. In addition, this dye also takes an intramolecular salt type and an intermolecular type, and takes a salt form similar to the cyanine series. Although many of these dyes are hydrophobic, they can be dissolved in water by adding a water-soluble group as in the case of cyanine dyes.

Azo dyes are dyes that absorb visible light and are mainly used in water-soluble inks, but there are dyes on the market that can absorb up to the near-infrared region by widening the absorption band. For example, C.I. I. Acid Black 2 (manufactured by Orient Chemical Industry Co., Ltd.), C.I. I. An example using Direct Black 19 (manufactured by Aldrich Industrial Co., Ltd.) can be given. Also, these azo dyes can be complexed with metals. In this case, it is represented by the following general formula (A-6), the central metal M ₂ includes cobalt, nickel, etc., and Ar ₁₁ and B ₁ are exemplified by an aromatic ring such as a benzene ring or a naphthalene ring. Specifically, the dye structure described in JP-A-59-11385 is suitable.

The metal complex system is represented by the following general formula (A-7) or the following general formula (A-8). M ₃ and M ₄ in the formula represent metals, and are generally Pd, Ni, Co, and Cu, but Ni is particularly preferred. R ₇₁ , R ₇₂ , R ₈₁ , and R ₈₂ represent arbitrary substituents, and specific examples include halogen atoms, alkyl groups optionally having a sulfo group, alkoxy groups optionally having a sulfo group, cyano group, an amino group, a nitro group, a phenyl group optionally having a substituent, and the like. X ₁ to X ₄ each independently represent a nitrogen atom, an oxygen atom or a sulfur atom. When X ₁ to X ₄ are nitrogen atoms, the nitrogen atoms are 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. It may be a nitrogen atom.

The boron complex system is represented by the following general formula (A-9), and the dye structure described in JP-A-2010-106248 is suitable.

In general formula (A-9) above, R ₉₃ and R ₉₄ are preferably a hydrogen atom, an alkyl group or a phenyl group, R ₉₅ is preferably a strong electron-attracting group such as a nitro group or a cyano group, and Ar ₉₀ is a substituent. Ar ₁₂ is preferably a cyclic structure composed of an aromatic ring or a heterocyclic ring, more preferably a heterocyclic ring in order to lengthen the absorption wavelength. Y is preferably a sulfur atom or an oxygen atom.

Diimonium-based dyes are dyes having absorption on the relatively long wavelength side (950 to 1100 nm) even in the near-infrared region, and are represented by the following general formula (A-10).

In general formula (A-10) above, R ₆ to R ₁₃ include an optionally substituted alkyl group, an optionally substituted aromatic ring, and the like. Generally, the dyes are hydrophobic dyes, but the dyes shown in Japanese Unexamined Patent Application Publication No. 2001-181184 are also disclosed to which a water-soluble group is added. This dye is also an inner salt type, an intermolecular salt type, and in the case of an intermolecular salt type, Q is a halide ion, perchlorate ion, antimony fluoride ion, phosphorus fluoride ion, boron fluoride ion, trifluoromethane sulfonate ion, bis(trifluoromethane)sulfonimide ion, naphthalenesulfonate ion, and the like. Examples of alkyl groups which may have substituents include halogens, hydroxyl groups, cyano groups, substituted or unsubstituted amino groups, carboxy groups, sulfo groups, phosphoric groups, carboxyalkyl groups, alkoxy groups, phenoxy groups, and the like. and a linear or branched or cyclic C1-C8 alkyl group substituted with . Halogen may be the same as above. Examples of substituted or unsubstituted amino groups include amino group, methylamino group, dimethylamino group, dibutylamino group, phenylamino group, diphenylamino group and the like. The carboxyalkyl group includes, for example, a methylcarboxy group, an ethylcarboxy group, and the like. Examples of alkoxy groups include methoxy, ethoxy, butoxy, and tertiary butoxy groups.

Diphenylamine/triphenylamines are represented by the following general formula (A-11) or the following general formula (A-12).

R ₁₄ to R ₁₇ in general formula (A-11) and R ₁₈ to R ₂₃ in general formula (A-12) are each independently a hydrogen atom or an alkyl group containing at least one carbon atom, The alkyl group optionally contains one or more heteroatoms selected from nitrogen, oxygen, sulfur and halogen atoms, wherein one or more nitrogen atoms is a cation radical, said one or more A cation radical is charge balanced by one or more anions.

As the infrared light absorbing water-soluble compound, an azo compound or a salt thereof is preferable.

As the azo compound, an azo compound represented by the above formula (1) is preferable.

By incorporating the azo compound represented by the above formula (1) or a salt thereof into the polarizing element of the present invention, it is possible to impart remarkably high durability. Furthermore, it is possible to obtain a polarizing element that can provide highly polarized light over a wide range of wavelengths in the infrared region. Regarding general dye-based polarizing elements, for example, Patent Documents 19 and 20 can obtain a polarizing element that exhibits a high degree of polarization in the visible region, but cannot provide a polarizing element that has polarization in the infrared region. In addition, there was a problem that the change in light transmittance in the wavelength region longer than 680 nm was extremely large in the durability test, and the polarizing plate changed color, for example, turned red after the durability test. To solve this problem, the use of the azo compound represented by the formula (1) is extremely preferable because a polarizing element having both higher durability and broadband polarizing function can be obtained.

In the above formula (1), Ai ₁ and Ai ₂ are each independently represented by a hydrogen atom, an azo group, or the above formula (2) (excluding those in which both Ai ₁ and Ai ₂ are hydrogen atoms), Ai ₁ and Ai ₂ are preferably represented by Formula (2). -NH- is any combination of a and a', b and b', a and b', b and a', preferably a and a'.

In the above formula (2), the rings substituted by Ri ₁ are each independently a benzene ring when the ring represented by the dashed line does not exist, and a naphthalene ring when the ring represented by the dashed line exists. is. Ri ₁ each independently represents a chlorine atom, a sulfo group, a nitro group, a hydroxy 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 having a sulfo group, C1-4 alkyl group having a hydroxy group, C1-4 alkyl group having a carboxy group, C1-4 alkoxy group having a sulfo group, C1-4 alkoxy group having a hydroxy group represents a substituent selected from the group consisting of an alkoxy group having 1 to 4 carbon atoms and a carboxy group.

Examples of the alkyl group having 1 to 4 carbon atoms include linear alkyl groups such as methyl group, ethyl group, propyl group and normal butyl group, and chain alkyl groups such as secondary butyl group and tertiary butyl group. Examples of alkoxy groups having 1 to 4 carbon atoms include methoxy, ethoxy, propoxy and butoxy groups. The alkyl group having 1 to 4 carbon atoms and having a sulfo group includes sulfomethyl group, sulfoethyl group, sulfopropyl group, sulfobutyl group and the like. The alkyl group having 1 to 4 carbon atoms and having a hydroxy group includes hydroxymethyl group, hydroxyethyl group, hydroxypropyl group, hydroxybutyl group and the like.

The alkoxy group having 1 to 4 carbon atoms and having a hydroxy group is preferably a straight-chain alkoxy group having a hydroxy group substituted at the end of the alkoxy group, more preferably a 4-hydroxypropoxy group or a 4-hydroxybutoxy group. be. The alkoxy group having 1 to 4 carbon atoms and having a carboxy group is preferably a linear alkoxy group in which the alkoxy group terminal is substituted with a carboxy group, more preferably a 4-carboxypropoxy group or a 4-carboxybutoxy group. . The alkoxy group having 1 to 4 carbon atoms and having a sulfo group is preferably a linear alkoxy group having a sulfo group substituted at the end of the alkoxy group, more preferably a 4-sulfopropoxy group or a 4-sulfobutoxy group. .

In the above formula (2), each Bi independently represents an optionally substituted phenyl group or an optionally substituted naphthyl group.

Examples of substituents that the phenyl group and naphthyl group may have include a chlorine atom, a sulfo group, a nitro group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a sulfo group. an alkyl group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms having a hydroxy group, an alkyl group having 1 to 4 carbon atoms having a carboxy group, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, represents a substituent selected from the group consisting of an alkoxy group having 1 to 4 carbon atoms and having a hydroxy group and an alkoxy group having 1 to 4 carbon atoms and having a carboxy group;

When Bi in the above formula (2) has a hydroxy group as a substituent, the hydroxy group and the copper atom in formula (1) form an —O—Cu—O— bond to form an azo metal complex compound or its It can be salted.

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

When Bi has a substituent but is more a phenyl group, the substitution position is not particularly limited, but a combination of 2-position and 4-position, 2-position and 5-position, or 3-position and 5-position is preferred, and 2-position and 4-position are preferred. rank is particularly preferred. When Bi is a naphthyl group which may have a substituent, the substitution position is not particularly limited. , 2 and 7 are particularly preferred. In formula (1), Ai ₁ and Ai ₂ are each independently represented by a hydrogen atom or by formula (2), except when both Ai ₁ and Ai ₂ are hydrogen atoms, and a hydrogen atom and formula (2 ), or a combination of formula (2) for both Ai ₁ and Ai ₂ , and particularly preferably a combination of formula (2) for both Ai ₁ and Ai ₂ .

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

In the above formula (3), Ri ₂ is a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and 1 carbon atom having a sulfo group. -4 alkyl groups, C1-4 alkyl groups having a hydroxy group, C1-4 alkyl groups having a carboxy group, C1-4 alkoxy groups having a sulfo group, carbon having a hydroxy group It represents a substituent selected from the group consisting of alkoxy groups of 1 to 4 carbon atoms and alkoxy groups of 1 to 4 carbon atoms having a carboxy group. The substitution position of Ri ₂ in formula (3) may be ortho, meta or para with respect to the position where the oxygen atom is substituted, but the substitution is preferably at the para position. Further, it is preferable that the oxygen atom in the formula (3), the --OH in the formula (1) and the copper atom form --O--Cu--O--. When the azo compound represented by the above formula (1) is the above formula (4), it is possible to provide an infrared polarizing element having higher performance and a broader band, which is more preferable. In formula (4), m is the same as in formula (2) above, Ri ₃ may be the same as Ri ₂ in formula (3), and the substitution position of Ri ₃ may also be the same as Ri ₂ .

The azo compounds represented by formulas (1) to (4) may be in free form or in salt form. Salts may be, for example, alkali metal salts such as lithium, sodium and potassium salts, alkaline earth metal salts such as calcium salts, organic salts such as ammonium salts and alkylamine salts, preferably sodium salts. is.

Specific examples of the azo compound represented by formula (1) are shown below, but are not limited to these. A sulfo group, a carboxy group and a hydroxy group in the formula are represented as free acids.

The azo compound represented by the above formula (1) or a salt thereof can be diazotized and coupled according to a conventional azo dye production method as described in, for example, Patent Document 14, Patent Document 15 and Non-Patent Document 2. It can be manufactured by performing

Examples of specific manufacturing methods include the following methods. For example, aminothiazoles represented by the following formula (A) are diazotized and subjected to primary coupling with anilines represented by the following formula (B) or aminonaphthalenes represented by the following formula (C) to obtain the following formula (D). Alternatively, a monoazoamino compound represented by the following formula (E) is obtained.
This disazoamino compound (D) or (E) is diazotized as Ai ₁ component or Ai ₂ component, respectively, and subjected to secondary coupling with a naphthol of the following formula (F) to obtain an azo compound of formula (1). is obtained.

In the above formulas (A) to (F), the presence or absence of a dashed line in Ri ₁ and the ring substituted by Ri ₁ has the same meaning as in formula (2), and Ri ₂ is the same as in formula (3). R ₂₄ or R ₂₅ each independently represents a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a sulfo group. an alkyl group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms having a hydroxy group, an alkyl group having 1 to 4 carbon atoms having a carboxy group, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, An alkoxy group having 1 to 4 carbon atoms having a hydroxy group and an alkoxy group having 1 to 4 carbon atoms having a carboxy group are represented, and m has the same meaning as in formula (2).
Alkyl groups with 1 to 4 carbon atoms, alkoxy groups with 1 to 4 carbon atoms, alkyl groups with sulfo groups with 1 to 4 carbon atoms, alkyl groups with hydroxy groups with 1 to 4 carbon atoms, and carbon atoms with carboxy groups Examples of the alkyl group having 1 to 4, the alkoxy group having 1 to 4 carbon atoms having a sulfo group, the alkoxy group having 1 to 4 carbon atoms having a hydroxy group, and the alkoxy group having 1 to 4 carbon atoms having a carboxy group are the above-mentioned can be the same as

In the above production method, the diazotization step is carried out by the so-called "normal method" of mixing a mineral acid aqueous solution or suspension such as hydrochloric acid or sulfuric acid as a diazo component with a nitrite such as sodium nitrite, or by It is preferable to use the so-called "reverse method" in which a nitrite is added to a neutral or weakly alkaline aqueous solution and mixed with a mineral acid. A suitable temperature for diazotization is -10 to 40°C. The coupling step with anilines is preferably 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 at a temperature of -10 to 40°C and a pH of 2 to 7.

The monoazo compound of formula (D) or formula (E) obtained by the coupling reaction is filtered as it is, precipitated by acid precipitation or salting out and then filtered out, or is taken out as a solution or suspension in the next step. You can also go to If the diazonium salt is sparingly soluble and forms a suspension, it can be filtered and used as a presscake for the next coupling step.

The tertiary coupling reaction between the diazotized product of the monoazo compound of formula (D) or formula (E) and the naphthols represented by formula (F) is carried out at a temperature of -10 to 40°C and a neutral to pH of 7 to 10. It is preferably carried out under alkaline conditions. After completion of the reaction, the obtained azo compound or salt of formula (1) is preferably precipitated by salting out and filtered out. Further, when purification is required, salting-out may be repeated, or an organic solvent may be used to precipitate out of water. Examples of organic solvents used for purification include water-soluble organic solvents such as alcohols such as methanol and ethanol, and ketones such as acetone.

The compounds represented by formula (A) above are 2-aminobenzothiazoles when the ring represented by the dashed line is absent, for example, 2-amino-6-sulfobenzothiazole, 2-amino-7 -methoxy-6-sulfobenzothiazole, 2-amino-4,6-disulfobenzothiazole, 2-amino-7-methoxy-4,6-disulfobenzothiazole, and the like. When a ring represented by a dashed line is present, it is a 2-aminonaphthothiazole, such as 2-amino-6,8-disulfonaphthothiazole, 2-amino-4,6,8-trisulfonaphthothiazole. , 2-amino-4-chloro-6,8-disulfonaphthothiazole, 2-amino-6-sulfopropoxy-4,8-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-sulfo propoxy-5,7,9-trisulfonaphthothiazole, and the like, 2-amino-6-sulfobenzothiazole, 2-amino-7-methoxy-6-sulfobenzothiazole, 2-amino-6,8- Disulfonaphthothiazole is preferred.

Examples of the anilines of formula (B) include anilines having a lower alkoxy group having a sulfo group, such as 3-(2-amino-4-methylphenoxy)propane-1-sulfonic acid and 3-(2-aminophenoxy). Propane-1-sulfonic acid, 3-(2-amino-4-methylphenoxy)butane-1-sulfonic acid, and the like. Other anilines include, for example, 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, 3,5-dimethoxyaniline and the like. The amino group of these anilines may be protected. Examples of aminonaphthalenes of formula (C) include 1-aminonaphthalene, 1-aminonaphthalene-6-sulfonic acid, 1-aminonaphthalene-7-sulfonic acid, 1-amino-2-methoxynaphthalene-6-sulfone acids, 1-amino-2-methoxynaphthalene-7-sulfonic acid, 1-amino-2-ethoxynaphthalene-6-sulfonic acid and 1-amino-2-ethoxynaphthalene-7-sulfonic acid, preferably 1-aminonaphthalene-7-sulfonic acid and 1-amino-2-methoxynaphthalene-7-sulfonic acid. The amino group of these aminonaphthalenes may be protected. Protecting groups include, for example, the ω-methanesulfone group.

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

At least one kind of dichroic dye exhibiting polarization characteristics in the visible region is used in the polarizing element 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 one dichroic dye exhibiting polarization characteristics in the visible region may be contained other than the azo compound represented by formula (1).

In order to produce an achromatic polarizing element, the polarizing element of the present invention preferably contains an azo compound of formula (5) or formula (6) or a salt thereof, one of them, or both. The formulation provides a high transmittance, a high degree of polarization, and an achromatic polarizing element. A polarizing element containing the azo compound of the formula (5) or (6) has high durability and can provide a highly reliable liquid crystal display.

First, the expression (5) will be explained. In formula (5), Ab ₁ and Ab ₂ each independently represent a substituted naphthyl group or a substituted phenyl group, at least one of which is a hydrogen atom, a sulfo group, a lower alkyl group, a lower an alkoxy group, a lower alkoxy group having a sulfo group, a carboxy group, a nitro group, an amino group, or a substituted amino group, wherein each of Rb ₁ and Rb ₂ is independently a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a sulfo group; , or a lower alkoxy group having a sulfo group.

Furthermore, in order to obtain a polarizing element having a higher transmittance, a higher degree of polarization, and a more achromatic hue in parallel and orthogonal positions, Rb ₁ and Rb ₂ in formula (5) are Each independently substituted group is preferably a methyl group or a methoxy group, more preferably a methoxy group.

Furthermore, in order to obtain a polarizing element having a higher transmittance, a higher degree of polarization, and more achromatic hues in parallel and orthogonal positions, Ab ₁ and Ab ₂ in formula (5) are Each independently, a naphthyl group having a sulfo group or a carbonyl group is preferable, and a naphthyl group having a sulfo group is more preferable because a high-contrast polarizing plate can be obtained.

Specific examples of the azo compound represented by formula (5) used in the present application are shown below in the form of free acids.

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

In formula (6), Ag ₁ represents a substituted phenyl group or a substituted naphthyl group. When Ag ₁ is a phenyl group, it preferably has at least one sulfo group or carboxy group as its substituent. When the phenyl group has two or more substituents, at least one of the substituents is a sulfo group or a carboxy group, and the other substituents are a sulfo group, a carboxy group, a lower alkyl group, a lower alkoxy group, and a sulfo group. A lower alkoxy group, a nitro group, an amino group, an acetylamino group, or a lower alkylamino group-substituted amino group having Other substituents are more preferably sulfo group, methyl group, ethyl group, methoxy group, ethoxy group, carboxy group, nitro group or amino group, and particularly preferably sulfo group, methyl group, methoxy group or ethoxy group. or a carboxy group. As the lower alkoxy group having a sulfo group, straight-chain alkoxy is preferable, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group, more preferably 3-sulfopropoxy group and 4-sulfobutoxy group, particularly preferably 3- It is a sulfopropoxy group. The number of substituents on the phenyl group is preferably 1 or 2, and the substitution position is not particularly limited, but 4-position alone, a combination of 2-position and 4-position, and a combination of 3-position and 5-position are preferred.

When Ag ₁ is a substituted naphthyl group, it preferably has at least one sulfo group as its substituent. When the naphthyl group has two or more substituents, preferably at least one of the substituents is a sulfo group, and the other substituents are a sulfo group, a hydroxy group, a carboxy group, or a lower group having a sulfo group. It is an alkoxy group. It is particularly preferred that the naphthyl group has two or more sulfo groups as substituents. A lower alkoxy group having a sulfo group is preferably a straight-chain alkoxy, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. More preferred are 3-sulfopropoxy group and 4-sulfobutoxy group, and particularly preferred is 3-sulfopropoxy group. When the naphthyl group has two sulfo groups, the sulfo group substitution positions are preferably a combination of 4 and 8 positions and a combination of 6 and 8 positions, more preferably a combination of 6 and 8 positions. When the number of sulfo groups possessed by the naphthyl group is 3, the substitution positions of the sulfo groups are preferably a combination of 1, 3 and 6 positions.

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

In formulas (7) and (8) above, Rg ₁ to Rg ₃ each independently represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a lower alkoxy group having a sulfo group. In formula (7), Rg ₁ is preferably a hydrogen atom, a lower alkyl group, or a lower alkoxy group, more preferably a hydrogen atom, a methyl group, or a methoxy group, particularly preferably a hydrogen atom or a methoxy group. is. A lower alkoxy group having a sulfo group is preferably a straight-chain alkoxy, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. More preferred are 3-sulfopropoxy group and 4-sulfobutoxy group, and particularly preferred is 3-sulfopropoxy group. The substitution position of Rg ₁ is preferably the 2nd or 3rd position when the azo group on the Ag ₁ side is the 1st position. More preferably, when the azo group on the Ag ₁ side is the 1-position, the 3-position is more preferred. When a sulfo group is present, the sulfo group is preferably substituted at the 6-position or 7-position, more preferably at the 6-position. k represents an integer of 0 to 2; In formula (8), Rg ₂ or Rg ₃ are each independently preferably a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a lower alkoxy group having a sulfo group, more preferably a hydrogen atom or a methyl group. , methoxy, 3-sulfopropoxy, or 4-sulfopropoxy. The substitution positions of Rg ₂ or Rg ₃ are 2-position only, 5-position only, 2-position and 5-position, 3-position and 5-position, 2-position and 6-position when the azo group on the Xg ₁ side is the 1-position. Positions or a combination of positions 3 and 6 are applicable, preferably positions 2 only, 5 only, 2 and 5.

Xg ₁ in the above formula (6) is an optionally substituted amino group, an optionally substituted phenylamino group, an optionally substituted phenylazo group, or a substituted benzoylamino group. Xg ₁ is preferably an optionally substituted amino group or an optionally substituted phenylamino group, more preferably a phenylamino group. The amino group which may have a substituent is preferably an amino group having one or two selected from the group consisting of a hydrogen atom, a methyl group, a methoxy group, a sulfo group, an amino group and a lower alkylamino group. group, more preferably an amino group having one or two hydrogen atoms, methyl groups, or sulfo groups. A phenylamino group which may have a substituent is preferably one or two groups 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. A phenylamino group having a substituent, more preferably a phenylamino group having one or two substituents selected from the group consisting of a hydrogen atom, a methyl group, a methoxy group, a sulfo group, and an amino group. . The position of substitution is not particularly limited, but one of the substituents is preferably p-position with respect to the amino group of the phenylamino group. Phenylazo group is preferably 1 to 1 selected from the group consisting of hydrogen atom, hydroxy group, alkyl group having 1 to 4 carbon atoms, alkoxy group having 1 to 4 carbon atoms, amino group, hydroxy group and carboxyethylamino group It is a phenylazo group with three. A benzoylamino group which may have a substituent is preferably a benzoylamino group having one substituent selected from the group consisting of a hydrogen atom, a hydroxy group, an amino group and a carboxyethylamino group. The substitution position of Xg ₁ is preferably the 6th or 7th position, more preferably the 6th position, when the hydroxy group of the substituted naphthyl group is the 1st position.

The azo compound represented by the formula (6) or a salt thereof is preferably an azo compound represented by the following formula (6′) or a salt thereof, because the performance is particularly improved.

In the above formula (6′), Ag ₁ represents a substituted phenyl group or a substituted naphthyl group, Rg ₄ and Rg ₅ each independently have the same meaning as Rg ₁ in formula (7), Xg ₁ has the same meaning as Xg ₁ in formula (6). k ₁ and k ₂ each independently represent an integer of 0 to 2;

Specific examples of the azo compound represented by formula (6) include:
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 other azo compounds.

Specific examples of the azo compound represented by formula (6) are shown below in the form of free acids.

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 with respect to 100 parts by mass of the aqueous solution. , more preferably 0.001 to 1 part by mass.

The method for obtaining the azo compound represented by 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 formula (6) or a salt thereof is disclosed, for example, in JP-A-1-161202, JP-A-01-172907, JP-A-01-248105, JP-A-01-265205, and JP-B It can be synthesized by the method described in Japanese Patent Application Laid-Open No. 07-92531, etc., but is not limited thereto.

In one aspect, the polarizing element of the present invention contains an azo compound represented by formula (9) or formula (10), a metal complex compound thereof, or a salt thereof. In order to produce the polarizing element, it is preferable to use the infrared light absorbing compound and the azo compound of formula (9) or formula (10) independently or simultaneously. To provide an achromatic polarizing element having a high degree of polarization. In particular, the polarizing element using the azo compound of the formula (9) or (10) has high durability and can provide a highly reliable liquid crystal display.

First, the formula (9) will be explained below.

In the above formula (9), Ac ₁ represents a phenyl group or a naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group, and Rc ₁₁ to Rc ₁₄ each independently represents a lower alkoxy group having a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a sulfo group

In the above formula (9), when Ac ₁ is a phenyl group, it preferably has at least one sulfo group or carboxy group as its substituent. When the phenyl group has two or more substituents, at least one of the substituents is a sulfo group or a carboxy group, and the other substituents are preferably a sulfo group, a carboxy group, a lower alkyl group, or a lower alkoxy group. group, a lower alkoxy group having a sulfo group, a nitro group, an amino group, an acetylamino group and a lower alkylamino group-substituted amino group, more preferably a sulfo group, a methyl group, an ethyl group, a methoxy group, It is selected from the group consisting of ethoxy group, carboxy group, nitro group and amino group, particularly preferably from the group consisting of sulfo group, methyl group, methoxy group, ethoxy group and carboxy group. The lower alkoxy group having a sulfo group is preferably a straight-chain alkoxy group, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. As such a lower alkoxy group having a sulfo group, 3-sulfopropoxy group or 4-sulfobutoxy group is more preferred, and 3-sulfopropoxy group is particularly preferred. When the phenyl group has a sulfo group as a substituent, the number of sulfo groups is preferably one or two. The substitution position of the sulfo group is not particularly limited, but when there is one sulfo group, the position of the azo group is the 1-position, and the 4-position of the phenyl group is preferable, and there are two sulfo groups. When , a combination of the 2-,4-positions of the phenyl group or a combination of the 3-,5-positions of the phenyl group is preferred.

In the above formula (9), when Ac ₁ is a naphthyl group, it preferably has at least one sulfo group as its substituent. When the naphthyl group has two or more substituents, at least one of the substituents is a sulfo group, and the other substituents are preferably a sulfo group, a hydroxy group, a carboxy group and a lower alkoxy group having a sulfo group. selected from the group consisting of: As the lower alkoxy group having a sulfo group, a straight-chain alkoxy group is preferable, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. As such a lower alkoxy group having a sulfo group, 3-sulfopropoxy group or 4-sulfobutoxy group is more preferred, and 3-sulfopropoxy group is particularly preferred. When the number of sulfo groups substituted by the naphthyl group is two, the position of the azo group is the 2-position, and the substitution position of the sulfo group is a combination of the 4-, 8-positions or the 6-, 8-positions of the naphthyl group. is preferred, and a combination of 6-,8-positions is more preferred. When the number of sulfo groups substituted on the naphthyl group is three, the substitution positions of the sulfo groups are preferably a combination of 1-, 3- and 6-positions.

In the above formula (9), Rc ₁₁ to Rc ₁₄ each independently represent a hydrogen atom, a lower alkyl group, a lower alkoxy group or a lower alkoxy group having a sulfo group. As the lower alkoxy group having a sulfo group, a straight-chain alkoxy group is preferable, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. Rc ₁₁ to Rc ₁₄ are preferably each independently a hydrogen atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a 3-sulfopropoxy group or a 4-sulfobutoxy group, particularly preferably a hydrogen atom, It is a methyl group, a methoxy group or a 3-sulfopropoxy group. As the substitution position of the phenyl group on which Rc ₁₁ to Rc ₁₄ are substituted, when the substitution position of the azo group on the ureido skeleton side is the 1-position, preferably only the 2-position of the phenyl group, only the 5-position, 2- A combination of the 6-position and the 6-position, a combination of the 2-position and the 5-position, a combination of the 3-position and the 5-position, and particularly preferably only the 2-position, only the 5-position, 2-position and 5-position It is a combination of ranks. The above-mentioned 2-position only and 5-position only refer to the relationship between Rc ₁₁ and Rc ₁₂ and between Rc ₁₃ and Rc ₁₄ , where either one of Rc ₁₁ and Rc ₁₂ or Rc ₁₃ and Rc ₁₄ It means that it has one substituent other than a hydrogen atom only at the position or the 5-position, and the other is a hydrogen atom.

式中、Ａｃ_１、Ｒｃ_１１～Ｒｃ_１４は、上記式（９）に定義された通りである。このようなアゾ化合物の使用により、偏光素子の偏光性能をより向上させることができる。 Among the azo compounds represented by the above formula (9), an azo compound represented by the following formula (9b) is particularly preferable:

In the formula, Ac ₁ , Rc ₁₁ to Rc ₁₄ are as defined in formula (9) above. 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 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 JP-A-2009-155364 and similar methods, but is not limited thereto. For example, a base compound represented by formula (9-v) described below is reacted with a ureidating agent such as phenyl chlorocarbonate at 20 to 95° C. to obtain an azo compound represented by formula (9) above. can be made. As another synthesis method by ureidation, a method of using a phosgene compound or the like to ureidate an amine compound is known. By this synthesis method, the azo compound represented by formula (9) in the present invention having a ureido skeleton can be obtained.

A specific method for synthesizing the azo compound represented by the formula (9) is described below. First, an amine having a substituent represented by the following formula (9-i) is prepared, for example, by the method described in Yutaka Hosoda, "Dye Chemistry", Gihodo, 1957, pp. 135-234. A monoazoamino compound represented by the following formula (9-iii) is obtained by diazotization by a similar method and then coupling with an aniline represented by the following formula (9-ii).

In formula (9-i), Ac ₁ has the same meaning as Ac ₁ in formula (9) above. In formula (9-ii), Rc ₁₁ and Rc ₁₂ have the same meanings as Rc ₁₁ and Rc ₁₂ in formula (9) above. In formula (9-iii), Ac ₁ has the same meaning as Ac ₁ in formula (9) above, and Rc ₁₁ and Rc ₁₂ have the same meanings as Rc ₁₁ and Rc ₁₂ in formula (9) above, respectively.

Then, the monoazoamino compound represented by the above formula (9-iii) is diazotized, further coupled with an aniline represented by the following formula (9-iv) for secondary coupling, and the following formula (9-v) The disazoamino compound represented is obtained. In formula (9-iv), Rc ₁₃ and Rc ₁₄ have the same meanings as Rc ₁₃ and Rc ₁₄ in formula (9) above. In formula (9-v), Ac ₁ has the same meaning as Ac ₁ in formula (9) above, and Rc ₁₁ to Rc ₁₄ have the same meanings as Rc ₁₁ and Rc ₁₄ in formula (9) above.

The diazotization step in the above reaction pathway is carried out by a normal method such as mixing a nitrite such as sodium nitrite with an aqueous solution or suspension of a mineral acid such as hydrochloric acid or sulfuric acid as the diazo component, or by mixing a neutral salt of the diazo component. Alternatively, it is carried out by the reverse method of adding nitrite to a slightly alkaline aqueous solution and mixing it with a mineral acid. A suitable temperature for diazotization is -10 to 40°C. The coupling step 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°C and pH 2 to 7.

The monoazoamino compound or disazoamino compound obtained in the coupling step can be taken out by filtration as it is, or after being precipitated by acid precipitation or salting out, or subjected to further steps in the form of a solution or suspension. If the diazonium salt is sparingly soluble and is in suspension, it is also possible to filter the suspension and use the filtered diazonium salt as a presscake in further coupling steps.

The disazoamino compound obtained by the above steps is then subjected to a ureidation reaction with phenyl chlorocarbonate to synthesize the azo compound represented by the above formula (9). The ureido reaction is carried out under neutral to alkaline conditions at a temperature of 10 to 90° C. and a pH of 7 to 11, for example, according to the method described in JP-A-2009-155364. After completion of the ureidation reaction, the azo compound obtained by salting out is precipitated and then filtered. Further, when purification is required, the salting-out may be repeated, or an organic solvent may be used to precipitate the obtained azo compound from water. Examples of organic solvents 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 formula (9) used in the present invention can be synthesized.

Next, expression (10) will be described.

In formula (10) above, Ac ₂ represents a phenyl group or naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group. Rc ₂₁ to Rc ₂₅ each independently represent a hydrogen atom, a lower alkyl group, a lower alkoxy group or a lower alkoxy group having a sulfo group. _Rc26 represents a lower alkoxy group having a hydrogen atom, a lower alkyl group or a sulfo group. Xc ₂ is an amino group optionally having at least one substituent, a phenylazo group optionally having at least one substituent, a naphthotriazole group optionally having at least one substituent, or a substituent represents a benzoylamino group which may have at least one of the above substituents are a lower alkyl group, a lower alkoxy group, a sulfo group, a lower alkylamino group, a hydroxy group, an amino group, a substituted amino group, a carboxy group, and is selected from the group consisting of carboxyethylamino groups; p and q each independently represent an integer of 0 or 1;

In the above formula (10), Ac ₂ represents a substituted phenyl group or a substituted naphthyl group. When Ac ₂ is a substituted phenyl group, the phenyl group is a sulfo or carboxy group, and when the phenyl group has two or more substituents, at least one of those substituents is a sulfo group or a carboxy group, and the other substituents are sulfo a carboxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, a hydroxy group, a nitro group, an amino group, or a substituted amino group ( In particular, it is preferably an acetylamino group or an alkylamino group having 1 to 4 carbon atoms), and other substituents include a sulfo group, a carboxy group, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a hydroxy group, a nitro or an amino group, and particularly preferably a sulfo group, a carboxy group, a methyl group, a methoxy group, or an ethoxy group. The alkoxy group having 1 to 4 carbon atoms having a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. As the alkoxy group having 1 to 4 carbon atoms and having a sulfo group, 3-sulfopropoxy group or 4-sulfobutoxy group is more preferable, and 3-sulfopropoxy group is particularly preferable. 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 only the 4-position or a combination of the 2-position and the 4-position. , or a combination of the 3- and 5-positions.

In the above formula (10), when Ac ₂ is a naphthyl group having a substituent, the naphthyl group preferably has at least one sulfo group as a substituent, and when the naphthyl group has two or more substituents preferably, at least one of these substituents is a sulfo group, and the other substituent is a sulfo group, a hydroxy group, a carboxy group, or an alkoxy group having 1 to 4 carbon atoms having a sulfo group. The alkoxy group having 1 to 4 carbon atoms and having a sulfo group is preferably a linear alkoxy group, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. As the alkoxy group having 1 to 4 carbon atoms and having a sulfo group, 3-sulfopropoxy group or 4-sulfobutoxy group is more preferred, and 3-sulfopropoxy group is particularly preferred. When the number of 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 a combination of 4-position and 8-position or a combination of 6-position and 8-position. A combination of the 6-position and the 8-position is particularly preferred. When the number of sulfo groups on the naphthyl group is 3, the substitution positions of the sulfo groups are particularly preferably a combination of the 1-position, the 3-position and the 6-position with the substitution position of the azo group being the 2-position.

In the above formula (10), Xc ₂ is an amino group optionally having at least one substituent, a phenylamino group optionally having at least one substituent, or having at least one substituent a phenylazo group optionally having at least one substituent, a naphthotriazole group optionally having at least one substituent, a benzoyl group optionally having at least one substituent, or having at least one substituent represents a benzoylamino group, preferably a phenylamino group optionally having substituents, a phenylazo group optionally having substituents, a naphthotriazole group optionally having substituents, and and a benzoylamino group optionally having substituent(s). Particularly preferred Xc ₂ is a phenylamino group optionally having substituent(s), a phenylazo group optionally having substituent(s) and a benzoylamino group optionally having a substituent. The substituents are selected from the group consisting of lower alkyl groups, lower alkoxy groups, sulfo groups, lower alkylamino groups, hydroxy groups, amino groups, substituted amino groups, carboxy groups, and carboxyethylamino groups.

When Xc ₁ is an amino group optionally having at least one substituent, the amino group may be unsubstituted, but is preferably a lower alkyl group, a lower alkoxy group, a sulfo group, an amino group, having one or two substituents selected from the group consisting of a substituted amino group and a lower alkylamino group, more preferably the group consisting of a methyl group, a methoxy group, a sulfo group, an amino group and a lower alkylamino group has one or two substituents selected from

When Xc ₁ is a phenylamino group optionally having at least one substituent, the phenylamino group is unsubstituted or preferably a lower alkyl group, a lower alkoxy group or a sulfo group , an amino group and a lower alkylamino group, more preferably a substituent selected from the group consisting of a methyl group, a methoxy group, a sulfo group and an amino group have one or two

When Xc ₁ is a phenylazo group optionally having at least one substituent, the phenylazo group is unsubstituted or preferably a hydroxy group, a lower alkyl group, a lower alkoxy group, an amino 1 to 3 substituents selected from the group consisting of groups and carboxyethylamino groups, more preferably 1 to 3 substituents selected from the group consisting of methyl groups, methoxy groups, amino and hydroxy groups have one.

When Xc ₁ is a naphthotriazole group optionally having at least one substituent, the naphthotriazole group is unsubstituted or preferably consists of a sulfo group, an amino group and a carboxy group. It has one or two substituents selected from the group, and more preferably has one or two sulfo groups as substituents.

When Xc ₁ is a benzoylamino group optionally having at least one of the above substituents, the benzoylamino group is unsubstituted or preferably a hydroxy group, an amino group and a carboxyethylamino group. It has one substituent selected from the group consisting of groups, and more preferably has one or two hydroxy groups or amino groups as substituents.

When Xc ₁ is a benzoyl group optionally having at least one substituent, the benzoyl group is unsubstituted or preferably consists of a hydroxy group, an amino group and a carboxyethylamino group. It has one substituent selected from the group, and more preferably has one or two hydroxy groups or amino groups as substituents.

More preferable _Xc2 include the following.
- an amino group optionally having one or two 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 optionally having one or two 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 optionally having one substituent selected from the group consisting of an amino group and a carboxyethylamino group,
- a hydrogen atom, an amino group, and a benzoylamino group optionally having one substituent selected from the group consisting of a carboxyethylamino group, or - a hydrogen atom, a hydroxy group, a methyl group, a methoxy group, an amino group , and a phenylazo group optionally having 1 to 3 substituents selected from the group consisting of a carboxyethylamino group.
The position of the substituent is not particularly limited, but for example, when _Xc2 is a phenylamino group, at least one of the substituents on the phenyl group is particularly preferably at the p-position of the phenyl group with respect to the amino group. .

In the above formula (10), Rc ₂₁ to Rc ₂₅ each independently represent a hydrogen atom, a lower alkyl group, a lower alkoxy group or a lower alkoxy group having a sulfo group. Rc ₂₁ to Rc ₂₅ are each independently 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 terminal sulfo group, A hydrogen atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a 3-sulfopropoxy group, or a 4-sulfobutoxy group is more preferable, and a hydrogen atom, a methyl group, a methoxy group, or a 3-sulfopropoxy group. It is particularly preferred to have

In formula (10) above, Rc ₂₆ represents a hydrogen atom, a lower alkyl group or a lower alkoxy group having a sulfo group. It is preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a straight-chain alkoxy group having a sulfo group at the end, such as a hydrogen atom, a methyl group, an ethyl group, a 3-sulfopropoxy group, or a 4-sulfobutoxy group. is more preferred, and a hydrogen atom, a methyl group, or a 3-sulfopropoxy group is particularly preferred.

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

Among the azo compounds represented by the above formula (10), the azo compounds represented by the following formula (10b) are preferable. The use of such an azo compound can further improve the polarizing performance of the polarizing element. In formula (10b), Ac ₂ , Rc ₂₁ to Rc ₂₆ , Xc ₂ , p, and q are as defined in formula (10) above.

Next, specific examples of the azo compound whose free acid form is represented by Formula (10) are given below. In the following compound examples, the sulfo group and hydroxy group are represented in the form of free acids, but the sulfo group and hydroxy group may be in the form of salts.

Methods for synthesizing azo compounds whose free acid form is represented by formula (10) include, for example, JP-A-9-302250, JP-A-3-12606, International Publication No. 2005/075572, International Publication No. 2012/108169, International Publication No. 2012/108173, etc., but not limited thereto. Examples of the azo compound whose free acid form is represented by formula (10) include C.I. I. Direct Red 117, C.I. I. Direct Red 127, azo compounds described in JP-A-3-12606, azo compounds described in WO 2005/075572, azo compounds described in WO 2012/108169, etc. mentioned.

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

The compound represented by formula (11) will be described.

In formula (11), Ab ₁ represents a phenyl group or naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group, and Rb ₁₁ to Rb ₁₄ are each independently hydrogen atom, a lower alkyl group, a lower alkoxy group or a sulfo group, Rb ₁₅ and Rb ₁₆ each independently represent a lower alkoxy group, Xb ₁ represents a lower alkyl group, a lower alkoxy group, a sulfo an amino group, an amino group, a lower alkylamino group, a hydroxy group, a carboxy group, and a carboxyethylamino group, optionally having at least one substituent selected from the group consisting of phenylamino group, optionally substituted phenylazo group, optionally substituted naphthotriazole group or optionally substituted benzoylamino group, or optionally substituted benzoyl group represents d represents an integer of 0 or 1; Also, the compound may be a metal complex compound, preferably a copper complex compound.

The copper complex compound refers to, for example, the following formula (11b), where M in formula (11b) is a metal, and copper, nickel, cobalt and the like are used, but copper is preferred. In formula (11b), Ab ₁ , Rb ₁₁ to Rb ₁₄ , Rb ₁₆ , Xb ₁ and d each have the same meaning as in formula (11) above.

In formulas (11) and (11b) above, when Ab ₁ is a phenyl group, it preferably has at least one sulfo group or carboxy group as its substituent. When the phenyl group has two or more substituents, at least one of the substituents is a sulfo group or a carboxy group, and the other substituents are preferably a sulfo group, a carboxy group, a lower alkyl group, or a lower alkoxy group. , a lower alkoxy group having a sulfo group, a hydroxy group, a nitro group, a benzoyl group, an amino group, an acetylamino group and a lower alkylamino group-substituted amino group, more preferably a sulfo group, a methyl group, an ethyl group, methoxy group, ethoxy group, hydroxy group, carboxy group, nitro group, amino group, 3-sulfopropoxy group and 4-sulfobutoxy group, particularly preferably sulfo group, methyl group and methoxy group , a carboxy group and a 3-sulfopropoxy group. The lower alkoxy group having a sulfo group is preferably a straight-chain alkoxy group such as the above 3-sulfopropoxy group or 4-sulfobutoxy group, and the sulfo group is preferably substituted at the terminal of the alkoxy group. preferable. A phenyl group preferably has a sulfo group as a substituent, and the number of sulfo groups is preferably one or two. The substitution position of the substituent is not particularly limited, but when the position of the azo group is the 1-position, the 4-position of the phenyl group is preferable, and when there are two sulfo groups, the phenyl group A combination of 2-, 4-positions or a combination of 3-, 5-positions of is preferred.

In formulas (11) and (11b) above, when Ab ₁ is a naphthyl group, it preferably has at least one sulfo group as its substituent. When the naphthyl group has two or more substituents, at least one of the substituents is a sulfo group, and the other substituents are preferably a sulfo group, a hydroxy group, a carboxy group and a lower alkoxy group having a sulfo group. selected from the group consisting of: As the lower alkoxy group having a sulfo group, a straight-chain alkoxy group is preferable, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. As such a lower alkoxy group having a sulfo group, 3-sulfopropoxy group or 4-sulfobutoxy group is more preferred, and 3-sulfopropoxy group is particularly preferred. When the number of sulfo groups substituted by the naphthyl group is two, the substitution position of the sulfo group is a combination of the 4-, 8-positions or the 6-, 8-positions of the naphthyl group with the position of the azo group as the 2nd position. is preferred, and a combination of 6-,8-positions is more preferred. When the number of sulfo groups to be substituted on the naphthyl group is three, it is preferable that the position of the azo group is the 2-position and the substitution positions of the sulfo groups are a combination of the 3-, 6-, and 8-positions.

In formulas (11) and (11b) above, Rb ₁₁ to Rb ₁₄ each independently represent a hydrogen atom, a lower alkyl group, a lower alkoxy group or a lower alkoxy group having a sulfo group. As the lower alkoxy group having a sulfo group, a straight-chain alkoxy group is preferable, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. Rb ₁₁ to Rb ₁₄ are preferably hydrogen atom, methyl group, ethyl group, methoxy group, ethoxy group, 3-sulfopropoxy group or 4-sulfobutoxy group, particularly preferably sulfo group, methyl group, methoxy a carboxy group or a 3-sulfopropoxy group.

Rb ₁₅ and Rb ₁₆ in formula (11) and Rb ₁₆ in formula (11b) each independently represent a lower alkoxy group, preferably a methoxy group or an ethoxy group. A methoxy group is more preferable because it dramatically improves the polarizing performance of the polarizing element or polarizing plate according to the present invention.

In formulas (11) and (11b) above, Xb ₁ has at least one substituent 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. optionally substituted amino group, optionally substituted phenylamino group, optionally substituted phenylazo group, optionally substituted naphthotriazole group or optionally substituted benzoyl It represents an amino group or a benzoyl group which may have a substituent.

When Xb ₁ is an optionally substituted amino group, the amino group may be unsubstituted, but is preferably a lower alkyl group, a lower alkoxy group, a sulfo group, an amino group and a lower alkyl having one or two substituents selected from the group consisting of an amino group, more preferably having a substituent selected from the group consisting of a methyl group, a methoxy group, a sulfo group, an amino group and a lower alkylamino group; Have one or two.

When Xb ₁ is the above optionally substituted phenylamino group, the phenylamino group is unsubstituted or preferably a lower alkyl group, a lower alkoxy group, a sulfo group, an amino and a lower alkylamino group, more preferably one substituent selected from the group consisting of a methyl group, a methoxy group, a sulfo group and an amino group. have one or two.

When Xb ₁ is the above optionally substituted phenylazo group, the phenylazo group is unsubstituted or preferably a hydroxy group, a lower alkyl group, a lower alkoxy group, an amino group and 1 to 3 substituents selected from the group consisting of carboxyethylamino groups, more preferably 1 to 3 substituents selected from the group consisting of methyl groups, methoxy groups, amino and hydroxy groups .

When Xb ₁ is a naphthotriazole group optionally having a substituent, the naphthotriazole group is unsubstituted or preferably selected from the group consisting of a sulfo group, an amino group and a carboxy group. It has one or two selected substituents, more preferably one or two sulfo groups as substituents.

When Xb ₁ is the above optionally substituted benzoylamino group, the benzoylamino group is unsubstituted or preferably consists of a hydroxy group, an amino group and a carboxyethylamino group. It has one substituent selected from the group, and more preferably has one or two hydroxy groups or amino groups as substituents.

Xb ₁ is preferably a benzoylamino group or a phenylamino group optionally having at least one of the above substituents, most preferably a phenylamino group optionally having the above substituents . When the benzoylamino group or phenylamino group has the above substituents, the position of the substituents is not particularly limited, but in the case of the phenylamino group, one of the above substituents is p- position is preferred, whereas in the case of benzoylamino groups one of the above substituents is preferably in the p-position to the carbonyl group.

Among the azo compounds represented by the above formula (11), an 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), Ab ₁ , Rb ₁₁ to Rb ₁₆ , Xb ₁ and d are as defined in formula (11) above.

Specific examples of the azo compounds represented by the above formulas (11), (11b) and (11c) include, for example, JP-A-3-12606, JP-A-5-295281, JP-A-10-259311, Examples include the following azo compounds as described in WO 2007/145210, WO 2012/108169, and WO 2012/108173.

The azo compounds represented by the above formulas (11), (11b), and (11c) are, for example, JP-A-3-12606, JP-A-5-295281, JP-A-10-259311, International Publication No. 2007/145210, International Publication No. 2012/108169, and International Publication No. 2012/108173, etc., but not limited thereto.

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

In formula (12), Ab ₂ represents a phenyl group or naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group, and Rb ₂₁ represents a hydrogen atom, a lower alkyl group, a lower alkoxy group. or a lower alkoxy group having a sulfo group, and Xb ₂ is substituted selected from the group consisting of lower alkyl, lower alkoxy group, lower alkylamine group, hydroxy group, carboxy group, sulfo group, amino group and substituted amino group an amino group optionally having at least one group, a phenylamino group optionally having a substituent, a phenylazo group optionally having a substituent, a naphthotriazole group optionally having a substituent, a substituent or a benzoyl group which may have a substituent)

In formula (12), Ab ₂ represents a phenyl group or a naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group, and the phenyl group or the naphthyl group has two substituents. At least one of the substituents is a sulfo group or a carboxy group, and the other substituents are preferably a sulfo group, a lower alkyl group, a lower alkoxy group, a lower alkoxy group having a sulfo group, a carboxy nitro group, amino group and substituted amino group, more preferably selected from the group consisting of sulfo group, methyl group, ethyl group, methoxy group, ethoxy group, carboxy group, nitro group and amino group and particularly preferably selected from the group consisting of a sulfo group, a carboxy group, a lower alkyl group and a lower alkoxy group. As the lower alkoxy group having a sulfo group, a straight-chain alkoxy group is preferable, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. As such a lower alkoxy group having a sulfo group, a 3-sulfopropoxy group or a 4-sulfobutoxy group is more preferred, and a 3-sulfopropoxy group is particularly preferred. The number of substituents that the phenyl group has is preferably one or two, while the number of substituents that the naphthyl group has is preferably two or three. The positions of these substituents are not particularly limited, but when the number of substituents on the phenyl group is one, the position of the azo group is the 1-position and the 4-position of the phenyl group is Preferably, when the number of substituents is two, a combination of 2- and 4-positions or a combination of 3- and 5-positions of phenyl groups is preferred. On the other hand, the naphthyl group preferably has two or three sulfo groups as substituents. A combination of 4- and 8-positions or a combination of 6- and 8-positions is preferred, with the azo group substituted at the 2-position, and a combination of 6- and 8-positions is more preferred. Further, when the number of sulfo groups to be substituted on the naphthyl group is three, the substitution position of the sulfo group is a combination of 3-, 6-, and 8-positions with the substitution position of the azo group as 2-position. preferable.

In formula (12) above, Rb ₂₁ represents a lower alkoxy group having a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a sulfo group. As the lower alkoxy group having a sulfo group, a straight-chain alkoxy group is preferable, and the substitution position of the sulfo group is preferably the terminal of the alkoxy group. Rb ₂₁ is more preferably a hydrogen atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a 3-sulfopropoxy group or a 4-sulfobutoxy group, and particularly preferably a sulfo group, a methyl group, a methoxy group, A carboxy group or a 3-sulfopropoxy group. In particular, when Rb ₂₁ is a methoxy group, the polarizing performance of the polarizing element or polarizing plate according to the present invention is dramatically improved, which is preferable.

In the above formula (12), _Xb2 has at least one substituent selected from the group consisting of lower alkyl, lower alkoxy group, lower alkylamine group, hydroxy group, carboxy group, sulfo group, amino group and substituted amino group. or at least one substituent selected from the group consisting of a hydrogen atom, a lower alkyl group, a lower alkoxy group, a hydroxy group, a carboxy group, a sulfo group, an amino group, and a substituted amino group. represents a phenylamino group, phenylazo group, naphthotriazole group or benzoylamino group which may be substituted.

When _Xb2 is an optionally substituted amino group, the amino group may be unsubstituted, but is preferably a hydroxy group, a carboxy group, a sulfo group, an amino group or a lower alkylamino group. have one or two substituents selected from the group consisting of, more preferably one substituent selected from the group consisting of a methyl group, a methoxy group, a sulfo group, an amino group and a lower alkylamino group Or it is good to have two.

When Xb ₂ is a phenylamino group which may have one or more substituents, the phenylamino group is unsubstituted or methyl, methoxy, amino, substituted amino, and sulfo. It has a substituent selected from the group consisting of groups and preferably has a methoxy group, either unsubstituted or substituted. When the phenylamino group has the above substituents, the position of the substituents is not particularly limited, but one of the above substituents should be p-position with respect to the amino group bonded to the phenyl group. is preferred.

When Xb ₂ is a benzoylamino group optionally having a substituent, the benzoylamino group is unsubstituted or selected from the group consisting of an amino group, a substituted amino group and a hydroxy group. and preferably has an amino group as a substituent. When the benzoylamino group has the above substituents, the position of the substituents is not particularly limited, but one of the above substituents should be p-position with respect to the carbonyl group bonded to the phenyl group. is preferred.

When Xb ₂ is the above optionally substituted phenylazo group, the phenylazo group is unsubstituted or the group consisting of a hydroxy group, an amino group, a methyl group, a methoxy group and a carboxy group. It has a substituent selected from and more preferably has a hydroxy group as a substituent.

When _Xb2 is a naphthotriazole group optionally having a substituent, the phenylazo group is unsubstituted or has a sulfo group as a substituent.

Among the azo compounds represented by the above formula (12), the azo compounds represented by the following formula (12b) are preferable, and the use of such azo compounds can further improve the polarizing performance of the polarizing element.

In formula (12b), Ab ₂ , Rb ₂₁ and Xb ₂ are as defined in formula (12) above.

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

The azo compound represented by the above formula (12) can be produced by known diazotization and coupling as described in, for example, JP-B-64-5623 and JP-A-5-53014. It can be, but is not limited to.

In the 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 with respect to 100 parts by mass of the aqueous solution, and more It is preferably 0.001 to 1 part by mass.

In one aspect, the polarizing element of the present invention preferably contains at least one azo compound represented by the following formula (13) or (13′) or a salt thereof in order to further improve the polarizing performance.

In formula (13) above, Ay ₁ is a hydrogen atom, a sulfo group, a carboxy group, a hydroxy group, a lower alkyl group, or a lower alkoxy group, preferably a sulfo group or a carboxy group. Ry ₁ to Ry ₄ each independently represents a hydrogen atom, a sulfo group, a lower alkyl group, a lower alkoxy group or a lower alkoxy group having a sulfo group, preferably a hydrogen atom, a sulfo group, a lower alkyl group or a lower alkoxy group and more preferably a hydrogen atom, a methyl group, or a methoxy group. j represents an integer of 1 to 3;

i is 0 or 1 in said formula (13'). Ay ₁ , Ay ₂ , Ry ₁ , Ry ₂ , and j have the same meanings as in formula (13).

In formula (13′), Ay ₁ and Ay ₂ are preferably a sulfo group, a carboxy group or a lower alkoxy group, more preferably a sulfo group, a carboxy group, a methoxy group or an ethoxy group, still more preferably , a sulfo group or a carboxy group.

In formula (13′), Ry ₁ and Ry ₂ are preferably a hydrogen atom, a sulfo group, a methyl group, an ethyl group, a methoxy group or an ethoxy group, more preferably a hydrogen atom, a sulfo group, a methyl group or It is a methoxy group.

Among the azo compounds represented by the above formula (13) or (13′), an azo compound represented by the following formula (13b) is particularly preferable, and the use of such an azo compound improves the polarizing performance of the polarizing element. can be improved. In formula (13b), Ay ₁ , Ry ₁ , and Ry ₂ are as defined in formula (13) above.

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

In the polarizing element, the content of the azo compound represented by formula (13) or (13′) or a salt thereof is It is preferably 0.01 to 300 parts by mass, more preferably 0.1 to 200 parts by mass, even more preferably 30 to 200 parts by mass.

The azo compounds represented by formulas (13) and (13') affect the transmittance of 400 to 500 nm. In the polarizing element, the transmittance and the degree of polarization (dichroism), particularly on the short wavelength side of 400 to 500 nm, affect the loss of blue during black display and the yellowing of white during white display. The azo compounds represented by formulas (13) and (13′) improve the polarization characteristics (dichroism) of 400 to 500 nm while suppressing the decrease in transmittance on the short wavelength side in the parallel position of the polarizing element. , it is possible to further reduce the yellowness in white display and the lack of blue in black display. By further containing the azo compound represented by the formula (13) or (13'), the polarizing element alone has a more achromatic color, especially in the range of the single transmittance after the luminosity correction of 30 to 65%. , which is preferable because it expresses a high-quality paper-like white when white is displayed, and when the single transmittance after the visibility correction is 35 to 45%, the degree of polarization or the contrast is improved.

Specific examples of the azo compounds represented by formulas (13) and (13') include C.I. I. Direct Yellow 4, C.I. I. Direct Yellow 12, C.I. I. Direct Yellow 72, and C.I. I. Direct Orange 39, azo compounds having a stilbene structure described in International Publication No. 2007/138980, etc., but not limited thereto.

Further specific examples of the azo compounds represented by formulas (13) and (13') are given below. Compound examples are represented in the form of free acids.

The azo compounds represented by formulas (13) and (13′) or salts thereof can be synthesized, for example, by the method described in International Publication No. 2007/138980, etc., but commercially available products are also available. can.

The polarizing element of the invention may contain other azo compounds for the purpose of color correction to the extent that the performance of the invention is not impaired. As other azo compounds to be contained, those having high dichroism are particularly preferable. For example, azo compounds as shown in Non-Patent Document 1, C.I. I. Direct. Yellow 12, C.I. I. Direct Yellow 28, C.I. I. Direct. Yellow 44, C.I. I. Direct. Orange 26, C.I. I. Direct. Orange 39, C.I. I. Direct. Orange 107, C.I. I. Direct. Red2, C.I. I. Direct. Red31, C.I. I. Direct. Red79, C.I. I. Direct. Red 247, C.I. I. Direct. Green 80, C.I. I. Direct. Green 59, and azo compounds described in JP-A-2001-33627, JP-A-2002-296417 and JP-A-60-156759. In particular, an azo compound having phenyl J acid in the trisazo structure can be preferably used. It is suitable to use such other azo compound together with the azo compound represented by formula (1) or a salt thereof in the polarizing element. The above other azo compounds can be used not only as free acids, but also as alkali metal salts (eg, sodium salts, potassium salts, lithium salts), ammonium salts, salts of amines, copper complex compounds, or salts thereof. The other azo compounds are not limited to these, and known dichroic azo compounds can be used. Including another azo compound in the form of a free acid, a salt thereof, or a copper complex salt thereof makes it possible to improve optical properties in particular. Other azo compounds may be used alone or in combination.

In one aspect, the polarizing element of the present invention improves heat resistance durability by containing iodine. When iodine is added to the base material, iodine alone is difficult to dissolve in the solvent and impregnate the base material. Iodides such as zinc iodide and chlorides such as sodium chloride, lithium chloride and potassium chloride are generally included together with iodine. When a polarizing element is produced using the above iodide, it is usually possible to produce a polarizing element having a high degree of polarization in the visible region centered around 480 nm and 600 nm.

In one aspect, the polarizing element of the present invention may contain iodine, thereby having, for example, a single transmittance of 35 to 50% after visibility correction and a high degree of polarization, that is, a high contrast. While having high transmittance and high contrast, which are the characteristics of iodine-based polarizing plates, it has high durability, especially heat resistance, optical properties, especially little change in color, and little change in transmittance. be able to.

(Base material)
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 light absorbing water-soluble compound. and a molded body. Hydrophilic polymers include, for example, polyvinyl alcohol-based resins, amylose-based resins, starch-based resins, cellulose-based resins, polyacrylate-based resins, and the like. When a dichroic dye such as the above infrared light absorbing water-soluble compound is included in the base material, it is most preferable to use a polyvinyl alcohol resin as the base material from the viewpoint of workability, dyeability and crosslinkability. Although the shape of the substrate is not particularly limited, it is preferably in the form of a film.

(Transmittance)
Regarding the difference in average transmittance between two wavelength bands, the polarizing element of the present invention preferably has an absolute value of the difference in average transmittance between specific wavelength bands that is equal to or less than a predetermined value. The average transmittance is the average transmittance of each wavelength in a specific wavelength band.

In one aspect, the polarizing element of the present invention has an average value of transmittance at each wavelength at 520 nm to 590 nm and a transmittance at each wavelength at 420 nm to 480 nm when the absorption axes of the two polarizing elements are measured in parallel. The absolute value of the difference from the average value is 5% or less, and the absolute value of the difference between the average value of the transmittance of each wavelength in 600 nm to 640 nm and the average value of the transmittance of each wavelength in 520 nm to 640 nm is 3 % or less.

(Transmittance after visibility correction)
The transmittance after luminosity correction is the transmittance after luminosity correction obtained according to JIS Z 8722:2009. The transmittance used for correction is measured for each wavelength of 400 to 700 nm using a C light source (2-degree field of view) for a measurement sample (eg, polarizing element or polarizing plate), and the spectral transmittance is measured every 5 nm or 10 nm. can be obtained by measuring and correcting this to the visibility according to JIS Z 8722:2009. The transmittance after visual sensitivity correction is the single transmittance after visual sensitivity correction when the polarizing element or polarizing plate is measured alone, and the absorption axis of each of the two polarizing elements or polarizing plates is parallel. Parallel position transmittance after luminosity correction when the transmittance at time is corrected to luminosity; There is an orthogonal transmittance after luminosity correction in the case of

The wavelength bands from 420 nm to 480 nm, from 520 nm to 590 nm, and from 600 nm to 640 nm are the main wavelength bands based on color matching functions used in calculations to represent colors in JIS Z 8781-4:2013. Specifically, in the XYZ color matching function of JIS Z 8701, which is the basis of JIS Z 8781-4:2013, x (λ) with a maximum value of 600 nm, y (λ) with a maximum value of 550 nm, and 455 nm When the maximum value of z(λ), which is the maximum value, is 100, the wavelengths exhibiting values of 20 or more are the wavelength bands of 420 nm to 480 nm, 520 nm to 590 nm, and 600 nm to 640 nm.

The transmittance obtained by measuring the state (during bright display or white display) in which two polarizing elements are stacked so that their absorption axis directions are parallel is also referred to as "parallel position transmittance". Also, the average transmittance of each wavelength from ◯ nm to Δ nm is also referred to as “AT _◯−Δ ”. In one aspect of the polarizing element of the present invention, the absolute value of the difference between AT _420-480 and AT _520-590 in terms of parallel transmittance is within 5.0%, preferably 3.5% or less, more preferably 3.5% or less. is 2.5% or less, more preferably 2.0% or less, and particularly preferably 1.5% or less. In one aspect, the difference between AT _520-590 and AT _600-640 in terms of parallel position transmittance is within 3.0% as an absolute value, preferably 2.0% or less, more preferably 1.5. % or less, more preferably 1.0% or less. Such a polarizing element can display high-quality paper-like white in a parallel position.

The transmittance obtained by measuring the state (during black display or dark display) in which two polarizing elements are superimposed so that the absorption axis directions are perpendicular to each other is also referred to as "orthogonal transmittance". In one aspect of the polarizing element of the present invention, the difference in orthogonal transmittance between AT _420-480 and AT _520-590 is preferably 3.0% or less as an absolute value, and AT _520-590 and , and AT _600-640 as an absolute value is 2.0% or less. Such a polarizing element can display achromatic black in the orthogonal orientation. Furthermore, the difference in orthogonal transmittance between AT _420-480 and AT _520-590 is more preferably 1.5% or less, more preferably 1.0% or less, and particularly preferably 0.5 as an absolute value. % or less. Regarding orthogonal transmittance, the absolute value of the difference between AT _520-590 and AT _600-640 is more preferably 1.5% or less, more preferably 1.0% or less, and particularly preferably 0.5% or less. is.

Furthermore, the respective average transmittances of the single transmittance of each wavelength, the parallel transmittance of each wavelength, and the orthogonal transmittance of each wavelength in each of the wavelength bands of 380 nm to 420 nm, 480 nm to 520 nm, and 640 nm to 780 nm are When the average transmittance of each wavelength in the wavelength bands of 420 nm to 480 nm, 520 nm to 590 nm, and 600 nm to 640 nm is adjusted as described above, it is unlikely that the dye will be greatly affected, but it is possible that it is adjusted to some extent. preferable. Regarding the single transmittance of each wavelength, the difference between AT _380-420 and AT _420-480 is preferably 15% or less as an absolute value, and the difference between AT _480-520 and AT _420-480 is 15% as an absolute value. % or less, the difference between AT _480-520 and AT _520-590 is preferably 15% or less as an absolute value, and the difference between AT _640-780 and AT _600-640 is preferably 20% or less as an absolute value.

In one aspect, the polarizing element according to the present invention preferably has a single transmittance of 30% to 65% after visibility correction. The single transmittance after luminosity correction is the transmittance corrected to luminosity in accordance with JIS Z 8722:2009 for one measurement sample (eg, polarizing element or polarizing plate). As for the performance of the polarizing plate, a higher transmittance is required, but if the single transmittance after the luminosity correction is 30% to 65%, brightness can be expressed without discomfort even if it is used in a display device. Since the degree of polarization tends to decrease as the transmittance increases, from the viewpoint of balance with the degree of polarization, the single transmittance after visibility correction is preferably 35% to 50%, and more preferably 37%. % to 47%, particularly preferably 38% to 45%. If the single transmittance after visibility correction exceeds 65%, the degree of polarization may decrease. Single transmittance may exceed 65%.

It is preferable that AT _520-590 is 25% to 50% in the parallel position transmittance of the polarizing element. When such a polarizing element is provided in a display device, a bright, high-luminance and clear display device can be obtained. The transmittance of each wavelength in the wavelength band from 520 nm to 590 nm is one of the main wavelength bands based on the color-matching function used in calculations for indicating colors in JIS Z 8781-4:2013. In particular, each wavelength band from 520 nm to 590 nm is the wavelength band with the highest visibility based on the color matching function, and the transmittance in this range is close to the transmittance that can be visually confirmed. Therefore, it is very important to adjust the transmittance of each wavelength in the wavelength band from 520 nm to 590 nm. AT _520-590 measured in the parallel position is more preferably 28% to 45%, even more preferably 30% to 40%. Further, the degree of polarization of the polarizing element at this time may be 80% to 100%, preferably 90% to 100%, more preferably 97% to 100%, still more preferably 99% or more, and particularly Preferably it is 99.5% or more. A higher degree of polarization is preferable, but in the relationship between the degree of polarization and transmittance, it is necessary to adjust the transmittance and the degree of polarization appropriately depending on whether the brightness or the degree of polarization (or contrast) is emphasized. can be done.

The single transmittance after the visibility correction is the single transmittance after performing the visibility correction with the 2° visual field (C light source). The single transmittance after luminosity correction is obtained by calculating the single transmittance for each wavelength of 400 to 700 nm for each measurement sample (eg, polarizing element or polarizing plate) at intervals of 5 nm or 10 nm, and then measuring the 2° field of view ( C light source) can be obtained by performing visibility correction.

(degree of polarization)
The polarizing element of the present invention has polarizing performance with respect to light in at least part or all of the wavelength range of 700 nm 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%, it can be used for general purposes as a general polarizing element. It is preferable that the degree of polarization is 90% or more. If the degree of polarization of the polarizing element is 90% or more, the polarizing function can be expressed even if it is used in a liquid crystal display device. The degree of polarization is preferably 99% or higher, more preferably 99.9% or higher, still more preferably 99.95% or higher. However, since the required degree of polarization differs depending on the relationship between brightness (transmittance) and contrast (degree of polarization), it does not necessarily need to be 99%. can be used.

(chromaticity)
The chromaticity a* value and b* value are values obtained when measuring the transmittance of natural light according to JIS Z 8781-4:2013. The object color display method defined in JIS Z 8781-4:2013 corresponds to the object color display method defined by the International Commission on Illumination (abbreviation: CIE). The chromaticity a* value and b* value are measured by irradiating a measurement sample (for example, a polarizing element or a polarizing plate) with natural light. In the following, the chromaticity a* value and b* value obtained for one measurement sample are a*-s and b*-s, and two measurement samples are arranged so that their absorption axis directions are parallel to each other. The chromaticity a* value and b* value obtained for the state (white display) are a*-p and b*-p, and the two measurement samples are arranged so that their absorption axis directions are orthogonal to each other (black display Chromaticity a* and b* values determined for time) are denoted as a*-c and b*-c.

In one aspect, in the polarizing element according to the present invention, each of the absolute values of a*-s and b*-s is preferably 1.0 or less, and the absolute values of a*-p and b*-p are Each is preferably 2.0 or less. Such a polarizing element alone has a neutral color, and can display high-quality white when white is displayed. The absolute values of a*-p and b*-p of the polarizing element are each independently more preferably 1.5 or less, and still more preferably 1.0 or less. Furthermore, in the polarizing element, the absolute values of a*-c and b*-c are preferably 3.0 or less, more preferably 2.0 or less, and still more preferably 1.0 or less. is. Such a polarizing element can display achromatic black when black is displayed. Humans can perceive a color difference even if there is only a difference of 0.5 between the absolute values of the chromaticities a* and b*, and some people may perceive the color difference significantly. Therefore, it is very important to control these values in the polarizing element. In particular, when the absolute values of a*-p, b*-p, a*-c, and b*-c are each 1.0 or less, white during white display and black display A good polarizing plate can be obtained in which almost no other colors can be recognized in the black of . Such a polarizing plate can achieve achromaticity, that is, a high-grade paper-like white color in the parallel orientation, and achromatic, high-class, clear black color in the orthogonal orientation.

In one aspect, the polarizing element according to the present invention has achromaticity and a high degree of polarization by itself while having high contrast and high transmittance. The polarizing element of the present invention can express high-quality paper-like white (paper white) when displaying white, and can express achromatic black, especially clear black with a luxurious feel, when displaying black. . Until now, there has been no polarizing element having such high transmittance, achromaticity, absorption performance in the infrared region, and polarization performance in the infrared region. The polarizing element of the present invention is further characterized by high durability, particularly resistance to high temperatures and high humidity.

[Method for manufacturing polarizing element]
Hereinafter, a specific method for manufacturing a polarizing element will be described using a polyvinyl alcohol-based resin film as an example of the base material. The polarizing element is subjected to, for example, production of polyvinyl alcohol-based resin, production of original film, swelling treatment, dyeing treatment, first washing treatment, treatment for adding a cross-linking agent and/or water-resistant agent, stretching treatment, second washing treatment. , is manufactured by successively performing a drying process. Note that some of these processes can be omitted.

In the manufacturing method of the polarizing element, the degree of swelling of the base material in the swelling process, which will be described later, the mixing ratio of each azo compound in the dyeing process, the temperature and pH of the dyeing solution, the type of salt such as sodium chloride, mirabilite, and sodium tripolyphosphate, and their In one aspect, the concentration, the dyeing time, and the draw ratio in the drawing step are preferably adjusted so that the polarizing element satisfies at least one of the following conditions (i) to (v), and (vi ) is more preferably adjusted to further satisfy the condition.
(i) Regarding parallel position transmittance, the absolute value of the difference between AT _420-480 and AT _520-590 is 5% or less, and the absolute value of the difference between AT _520-590 and AT _600-640 is 3% or less. becomes.
(ii) With respect to orthogonal transmittance, the absolute value of the difference between AT _420-480 and AT _520-590 is 3% or less, and the absolute value of the difference between AT _520-590 and AT _600-640 is 2% or less. Become.
(iii) Single transmittance after visibility correction is 35% to 50%.
(iv) Each of the absolute values of the a* value and the b* value is 1.0 or less for the polarizing element alone, and 2.0 or less for the parallel position.
(v) Each of the absolute values of the a* and b* values measured at orthogonal positions is 3 or less.
(vi) for each of the single transmittance and the orthogonal transmittance, the absolute value of the difference between the average transmittance at each wavelength from 380 nm to 420 nm and the average transmittance at each wavelength from 420 nm to 480 nm is 15% or less; The difference between the average transmittance at each wavelength from 480 nm to 520 nm and the average transmittance at each wavelength from 420 nm to 480 nm is 15% or less as an absolute value, and the average transmittance at each wavelength from 480 nm to 520 nm and each wavelength from 520 nm to 590 nm The absolute value of the difference from the average transmittance is 15% or less, and/or the absolute value of the difference between the average transmittance of each wavelength from 640 nm to 780 nm and the average transmittance of each wavelength from 600 nm to 640 nm is 20% or less.

(Manufacturing of polyvinyl alcohol-based resin)
A method for producing the polyvinyl alcohol-based resin is not particularly limited, and a known method can be adopted. A polyvinyl alcohol-based resin can be obtained, for example, by saponifying a polyvinyl acetate-based resin. Examples of polyvinyl acetate-based resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Other monomers copolymerizable with vinyl acetate include, for example, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids and the like. The degree of saponification of the polyvinyl alcohol resin is usually about 85 to 100 mol %, preferably 95 mol % or more. This polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol-based resin means the viscosity average degree of polymerization, and can be determined by a method well known in the technical field. The degree of polymerization is usually about 1,000 to 10,000, preferably about 1,500 to 6,000.

(Preparation of raw film)
Next, a polyvinyl alcohol-based resin is formed into a film to produce a raw film. A method for forming a polyvinyl alcohol-based resin into a film is not particularly limited, and a known method can be adopted. The original film may contain glycerin, ethylene glycol, propylene glycol, low-molecular-weight polyethylene glycol, or the like as a plasticizer. The content of the plasticizer is 5 to 20% by weight, preferably 8 to 15% by weight, in the original film. Although the film thickness of the original film is not particularly limited, it is preferably about 5 μm to 150 μm, more preferably about 10 μm to 100 μm.

(Swelling treatment)
The raw film obtained as described above is then subjected to a swelling treatment. The swelling treatment is performed by immersing the original film in a solution at 20 to 50° C. for 30 seconds to 10 minutes. The solution is preferably an aqueous solution. The stretching ratio in the swelling treatment is preferably adjusted to 1.00 to 1.50 times, more preferably 1.10 to 1.35 times. Since swelling also occurs in the dyeing treatment to be described later, this swelling treatment may be omitted when shortening the time for fabricating the polarizing element.

(Dyeing treatment)
A dyeing process is performed after the swelling process. The dyeing process is a process of dyeing using a dye such as an infrared light absorbing water-soluble compound. Dyes that function as dichroic dyes in the visible range, such as iodine and iodine compounds, together with a water-soluble compound that absorbs light in at least the infrared region, Non-Patent Document 1, Patent Document 19, Patent Document 20, Patent Document 23, This is a dyeing treatment using the dyes shown in Patent Document 24, etc., preferably the azo compounds described in formulas (5) to (13). Dyeing is carried out, for example, by immersing the film after swelling treatment in a dyeing solution containing the above 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 dyeing solution is preferably 0.0001 wt% to 0.5 wt%, more preferably 0.001 wt% to 0.4 wt%, still more preferably 0.001 wt%. ~0.1% by weight.

The solution temperature in the dyeing treatment is preferably 5 to 60°C, more preferably 20 to 50°C, and particularly preferably 25 to 50°C. The time for immersion in the solution can 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. As the dyeing method, a method of immersing the film in a dyeing solution is preferable, but a method of applying the dyeing solution to the film after swelling treatment can also be adopted. The dyeing solution may contain sodium carbonate, sodium hydrogencarbonate, sodium chloride, sodium sulfate, anhydrous sodium sulfate, sodium tripolyphosphate, etc. as a dyeing aid. The content of the dyeing assistant can be arbitrarily adjusted by the time and temperature depending on the dyeability of the dichroic dye.

When dyeing with a plurality of dyes, the order of dyeing is not particularly limited. The dyes may be impregnated into the substrate in any order. When other azo compounds are used together with the infrared light-absorbing water-soluble compound, it is preferred that they are dyed at the same time. When iodine is used, it is preferable to impregnate the base material with the infrared light-absorbing water-soluble compound and any other azo compound, and then impregnate the base material with iodine, from the viewpoint of dyeing solution control and productivity.

(First cleaning treatment)
After the dyeing treatment, a washing treatment (hereinafter referred to as "first washing treatment") can be performed before performing the next treatment. The first washing treatment is a treatment for washing the dyeing solution adhering to the film surface during the dyeing treatment. By performing the first washing treatment, it is possible to prevent the dye from being mixed into the solution used in the next treatment. Water is generally used as the cleaning liquid in the first cleaning process. The washing method is preferably a method of immersing the dyed film in the washing liquid, but a method of applying the washing liquid to the dyed film can also be employed. Although the washing time is not particularly limited, it is preferably 1 to 300 seconds, more preferably 1 to 60 seconds. The temperature of the washing solution in the first washing process must be a temperature that does not dissolve the film after the dyeing process. It is generally washed at 5-40°C. However, this first cleaning process may be omitted because there is no problem in performance even if the first cleaning process is not performed.

(Processing to contain a cross-linking agent and/or a water-resistant agent)
After the first cleaning treatment, a treatment containing a cross-linking agent and/or a water-resistant agent can be performed. Examples of cross-linking agents include boron compounds such as boric acid, borax, and ammonium borate; polyvalent aldehydes such as glyoxal and glutaraldehyde; polyvalent isocyanate compounds such as biuret, isocyanurate, and block types; Examples include titanium-based compounds such as sulfate, as well as ethylene glycol glycidyl ether, polyamide epichlorohydrin, and the like. Examples of water resistant agents include succinic acid peroxide, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, ammonium chloride, magnesium chloride and the like. Among these, boric acid is most preferred. One type of crosslinking agent and waterproofing agent may be used alone, or a plurality thereof may be used in combination.

A method of immersing the film after the first washing treatment in a solution containing a cross-linking agent and/or a water-resistant agent is preferred, but the film after the first washing treatment is immersed in a solution containing a cross-linking agent and/or a water-resistant agent. can also be adopted. Preferably the solution is an aqueous solution. The content of the cross-linking agent and/or water-resistant agent in the solution is preferably 0.1 to 6.0% by weight, more preferably 1.0 to 4.0% by weight, taking boric acid as an example. The temperature of the solution is preferably 5-70°C, more preferably 5-50°C. The treatment time is preferably 30 seconds to 6 minutes, more preferably 1 to 5 minutes. However, the inclusion of a cross-linking agent and/or a water-resistant agent is not essential, and this treatment may be omitted if the time is desired to be shortened or cross-linking treatment or water-resistant treatment is unnecessary.

(Stretching treatment)
Stretching treatment is performed after the treatment for containing a cross-linking agent and/or a water-resistant agent. The stretching process is a process of uniaxially stretching the film. 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 case of the wet stretching method, the film is stretched in water, a water-soluble organic solvent, or a mixed solution thereof. It is preferable to stretch the film after the first washing treatment while immersing it in a solution containing a cross-linking agent and/or a water-resistant agent. Examples of the cross-linking agent and water-resistant agent include those described above. The content of the cross-linking agent and/or water-resistant agent in the solution is preferably 0.5 to 15% by weight, more preferably 2.0 to 8.0% by weight, taking boric acid 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 40-60°C, more preferably 45-58°C. The stretching time is usually 30 seconds to 20 minutes, preferably 2 to 5 minutes. Although the film can be stretched in one stage, it can also be stretched in two or more stages.

In the case of the dry stretching method, when the heating medium for stretching is an air medium, the temperature of the air medium is preferably normal temperature to 180°C. Moreover, it is preferable to carry out the treatment in an atmosphere with a humidity of 20 to 95% RH. Examples of the heating method include roll-to-roll zone stretching, roll heating stretching, compression stretching, infrared heating stretching, and the like, but the stretching method is not limited. Although the film can be stretched in one stage, it can also be stretched in two or more stages.

(Second cleaning process)
After the stretching treatment, a cross-linking agent and/or a water-resistant agent may precipitate on the film surface, or foreign substances may adhere. ) can be performed. The washing method is preferably a method of immersing the stretched film in a washing liquid, but a method of applying a washing liquid to the stretched film can also be employed. The washing treatment can be carried out in one stage, or can be carried out in multiple stages of two or more stages. The washing time is preferably 1 second to 5 minutes. Although the temperature of the washing solution is not particularly limited, it is usually 5 to 50°C, preferably 10 to 40°C.

Solvents used in the treatments up to this point include, for example, water, dimethylsulfoxide, N-methylpyrrolidone, methanol, ethanol, propanol, isopropyl alcohol, glycerin, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, or alcohols such as trimethylolpropane, amines such as ethylenediamine or diethylenetriamine, and the like, but are not limited thereto. Mixtures of one or more of these solvents can also be used. The most preferred solvent is water.

(drying process)
After the second washing treatment, a drying treatment for drying the film is performed. Drying treatment can be performed by natural drying. In order to further improve the drying efficiency, it may be compressed using rolls, moisture on the surface may be removed with an air knife or a water absorption roll, or air drying may be performed. The drying temperature is preferably 20 to 100°C, more preferably 60 to 100°C. The drying time is preferably 30 seconds to 20 minutes, more preferably 5 to 10 minutes.

By the above method, a polarizing element containing an infrared light absorbing water-soluble compound can be obtained.

In one aspect, the polarizing element of the present invention contains iodine and has high transmittance, contrast, and durability.

In one aspect, in the polarizing element of the present invention, the absolute value of the difference between AT _520-590 and AT _420-480 measured in the parallel position is 5% or less, and AT _600-640 and AT _520-590 The absolute value of the difference between is 3% or less, thereby having an achromatic color in the visible range, high transmittance and degree of polarization while having an absorption or polarization function in the infrared range, and a high Durable.

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

[Polarizer]
The polarizing plate of the present invention comprises a polarizing element and a transparent protective layer formed on at least one side of the polarizing element, that is, on one side or both sides. A transparent protective layer can be provided on at least one surface of the polarizing element by applying a polymer to at least one surface of the polarizing element and then performing drying or heat treatment. In addition, a transparent protective layer is formed by molding a polymer into a film, and after the transparent protective layer is attached to at least one surface of the polarizing element, drying or heat treatment is performed to obtain a transparent film on at least one surface of the polarizing element. A protective layer may be provided.

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

An adhesive is required to bond the transparent protective layer to at least one surface of the polarizing element. Although the adhesive is not particularly limited, an adhesive containing polyvinyl alcohol as a main component is preferable. Examples of polyvinyl alcohol-based adhesives include Gosenol NH-26 (manufactured by Nippon Synthetic Chemical Co., Ltd.) and Exeval RS-2117 (manufactured by Kuraray Co., Ltd.), but are not limited thereto. The polyvinyl alcohol-based adhesive can be mixed with a cross-linking agent and/or a waterproofing agent. Also, the polyvinyl alcohol-based adhesive may contain a copolymer of maleic anhydride and isobutylene, or a modified product thereof. Examples of copolymers of maleic anhydride and isobutylene include Isoban #18 (manufactured by Kuraray Co., Ltd.) and Isoban #04 (manufactured by Kuraray Co., Ltd.). #104 (manufactured by Kuraray Co., Ltd.) and Isovan #110 (manufactured by Kuraray Co., Ltd.). ). A water-soluble polyfunctional epoxy compound can be used as the cross-linking agent. Examples of water-soluble polyfunctional epoxy compounds include polyglycerol polyglycidyl ether (Denacol EX-521 (manufactured by Nagase Chemtech)), 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (TETRAD-C (manufactured by Mitsubishi Gas Chemical Company)) and the like. Also, known adhesives such as urethane-based adhesives, acrylic-based adhesives, and epoxy-based adhesives can be used. For the purpose of improving the adhesive strength of the adhesive or improving the water resistance, additives such as zinc compounds, chlorides, iodides, etc. may be added at a concentration of about 0.1 to 10% by weight at the same time.

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

In addition, 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 exposed later. can be done. A coating method is preferable for producing layers having various functions, but films having such functions can also be pasted together via an adhesive or a pressure-sensitive adhesive. Further, the various functional layers are, for example, layers that control retardation.

In one aspect, the iodine-containing polarizing plate of the present invention has a high degree of polarization around 480 nm and 600 nm, similar to a general iodine-based polarizing plate, and color change even when applied to a durability test. is less than that of conventional iodine-based polarizing plates.

In one embodiment, the base material contains an infrared light-absorbing water-soluble compound, and the average transmittance at 520 nm to 590 nm and the transmission at 420 nm to 480 nm when the absorption axes of two polarizing elements are measured in parallel. The absolute value of the difference from the average transmittance is 5% or less, and the absolute value of the difference between the average transmittance at 600 nm to 640 nm and the average transmittance at 520 nm to 590 nm is 3% or less. A polarizing plate using the polarizing element of the present invention characterized in that it has an achromatic color in the visible region, a high transmittance, a high degree of polarization, and high durability while having an absorption or polarizing function in the infrared region. can be obtained. In one embodiment, a polarizing plate using the polarizing element of the present invention containing an infrared light-absorbing water-soluble compound and an azo compound represented by formula (9) or formula (10) absorbs or polarizes in the infrared region. It is possible to obtain a dye-based polarizing element having a high transmittance in the visible region, a degree of polarization, and high durability while having functions. Conventional iodine-based polarizing plates or dye-based polarizing plates cannot provide a polarizing element having polarized light in the infrared region. There was a problem that the color changed, for example, changed to red after the sex test. That is, there is a problem that the a* value and b* value in the L*a*b* color system shown in JIS Z 8729 change. In the transmittance values obtained by overlapping measurements in the orthogonal position, there is a problem that the transmittance from 600 nm to 780 nm increases sharply and changes to red, that is, the a* value increases. However, according to the method of the present application, such a change in a* value is less, and a polarizing plate having high durability with less color change can be obtained.

The polarizing plate of the present invention may have a support on at least one surface. Since the support is attached to the polarizing plate, it preferably has a flat portion. 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. Since it is an optical application, the support is preferably a glass molded product. Glass molded articles include, for example, glass plates, lenses, prisms (eg, triangular prisms, cubic prisms), and the like. Examples of glass materials include soda glass and borosilicate glass. A lens having a polarizing plate attached thereto can be used as a condenser lens with a polarizing plate in a liquid crystal projector. A prism with a polarizing plate attached thereto can be used as a polarizing beam splitter with a polarizing plate or a dichroic prism with a polarizing plate in a liquid crystal projector. Also, a polarizing plate may be attached to the liquid crystal cell. The thickness and size of the support are not particularly limited.

A polarizing plate provided with glass is preferably provided with an antireflection layer on at least one surface of the glass or the polarizing plate in order to further improve the single transmittance. For example, after applying a transparent adhesive (adhesive) agent to the planar portion of the support, the polarizing plate of the present invention is attached to the applied surface. Alternatively, after applying a transparent adhesive (adhesive) agent to the polarizing plate, the support may be attached to the applied surface. The adhesive (adhesive) used here is preferably, for example, an acrylic ester-based one. When this polarizing plate is used as an elliptically 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 polarizing plate of the present invention can be used in liquid crystal display devices. A liquid crystal display device using the polarizing element or polarizing plate of the present invention is a liquid crystal display device having high reliability, high contrast over a long period of time, and high color reproducibility.

The polarizing element or polarizing plate of the present invention optionally comprises a protective layer or functional layer, a support, etc., and is used for liquid crystal projectors, calculators, clocks, notebook computers, word processors, liquid crystal televisions, polarized lenses, polarized glasses, car navigation systems. , sensors, cameras, analyzers, indoor and outdoor measuring instruments and indicators, etc. In particular, it is effectively used in reflective liquid crystal display devices, transflective liquid crystal display devices, organic electroluminescence devices, and the like.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these.

<<Example A>>
[Preparation of measurement sample]
(Example A1)
A polyvinyl alcohol film having a degree of saponification of 99% or more and an average degree of polymerization of 2400 (VF-PS manufactured by Kuraray Co., Ltd.) was immersed in hot water at 40°C for 2 minutes to perform swelling treatment so that the stretching ratio was 1.30 times. . Next, the swelling-treated film was mixed with 1500 parts by weight of water, 1.5 parts by weight of sodium tripolyphosphate, 1.5 parts by weight of anhydrous sodium sulfate, and a water-soluble compound that absorbs light in the infrared region of 700 nm to 1400 nm. C. having a structure represented by formula (101) as I. Direct Black 19 (manufactured by SHAOXING BIYING TEXITILE TECHNOLOGY Co., LTD) containing 0.30 parts by weight and immersed in an aqueous solution adjusted to 45° C. for 3 minutes and 30 seconds to incorporate the infrared light absorbing water-soluble compound into the film. rice field. Next, the resulting film was treated with 28.6 g/l boric acid (manufactured by Societa chimica lardrello spa), 0.25 g/l iodine (manufactured by Junsei Chemical Co., Ltd.), and potassium iodide (manufactured by Junsei Chemical Co., Ltd.). ) The film was made to contain iodine and an iodine compound by immersing 100 parts of an aqueous solution adjusted to 17.7 g/l in an aqueous solution diluted with 2000 parts of water at 30°C for 2 minutes. Next, the obtained film was stretched in an aqueous solution containing 30.0 g/l of boric acid at 50° C. for 5 minutes at a stretch ratio of 5.0. Next, while maintaining the tension of the obtained film, it was immersed in an aqueous solution containing 50 g/l of potassium iodide at 30°C for 20 seconds. Next, the resulting film was dried at 70° C. for 9 minutes to obtain a polarizing element. A polarizing plate was obtained by laminating an alkali-treated triacetyl cellulose film (ZRD-60 manufactured by Fuji Film Co., Ltd.) on the resulting polarizing element using a polyvinyl alcohol adhesive. The obtained polarizing plate maintained the optical properties of the polarizing element. The polarizing plate is cut into 40 mm squares and pasted to a transparent plate glass via an adhesive layer (AD-ROC manufactured by Polatechno Co., Ltd.) to prepare a durability test sample using the polarizing plate of the present application, and the measurement of the present application. It was used as a sample.

(Example A2)
The C.I. I. A measurement sample was prepared in the same manner as in Example A1, except that 0.30 parts by weight of Direct Black 19 was replaced with 0.30 parts by weight of S0378 manufactured by FEW CHEMICAL represented by formula (102).

(Example A3)
The C.I. I. A measurement sample was prepared in the same manner as in Example A1 except that 0.30 parts by weight of Direct Black 19 was replaced with 0.30 parts by weight of S2180 manufactured by FEW CHEMICAL represented by formula (103).

(Example A4)
The C.I. I. A measurement sample was prepared in the same manner as in Example A1, except that 0.30 parts by weight of Direct Black 19 was replaced with 0.30 parts by weight of the compound shown in Compound Example (1-10).

(Example A5)
The C.I. I. A measurement sample was prepared in the same manner as in Example A1, except that 0.30 parts by weight of Direct Black 19 was replaced with 0.30 parts by weight of the compound shown in Compound Example (1-21).

(Example A6)
The C.I. I. A measurement sample was prepared in the same manner as in Example A1, except that 0.30 parts by weight of Direct Black 19 was replaced with 1.0 parts by weight of the compound shown in Compound Example (1-10).

(Comparative Example A1)
In the dyeing step after swelling in Example A1, C.I. I. An iodine-based polarizing plate containing no azo dye was produced as a measurement sample in the same manner as in Example A1 except that it was not treated with an aqueous solution containing Direct Black 19.

(Comparative Example A2)
The C.I. I. A measurement sample was prepared in the same manner as in Example A1 except that 0.30 parts by weight of Direct Black 19 was replaced with 0.3 parts by weight of the azo compound shown in Example 1 of JP-A-3-12606.

[Evaluation method]
The measurement samples obtained in Examples A1 to A6 and Comparative Examples A1 to A2 were evaluated as follows.

(a) single transmittance Ts for each wavelength, parallel transmittance Tp for each wavelength, and orthogonal transmittance Tc for each wavelength
The single transmittance Ts of each wavelength, the parallel transmittance Tp of each wavelength, and the orthogonal transmittance Tc of each wavelength of each measurement sample are measured using a spectrophotometer ("U-4100" manufactured by Hitachi, Ltd.). bottom. Here, the single transmittance Ts of each wavelength is the transmittance of each wavelength when a single measurement sample is measured. The parallel transmittance Tp of each wavelength is the transmittance of each wavelength obtained by stacking two measurement samples so that their absorption axis directions are parallel to each other. The orthogonal transmittance Tc of each wavelength is the transmittance of each wavelength measured by stacking two measurement samples so that their absorption axis directions are orthogonal to each other. Measurements were taken at 5 nm intervals over the wavelength of 400-900 nm.

(b) Single Transmittance Ys after Visibility Correction, Parallel Transmittance Yp after Visibility Correction, and Orthogonal Transmittance Yc after Visibility Correction
Each optical characteristic (transmittance, degree of polarization, hue, etc.) was calculated based on JIS Z 8722:2009 (C light source 2° field of view). By performing luminosity correction based on the C light source 2° visual field equichromaticity function, the single transmittance Ys after luminosity correction, the parallel transmittance Yp after luminosity correction, and the orthogonal transmittance after luminosity correction A rate Yc was calculated.

(c) Degree of Polarization The degree of polarization ρy was obtained from the parallel position transmittance Yp after the visibility correction and the orthogonal position transmittance Yc after the visibility correction by the following formula (1).

ρy={(Yp−Yc)/(Yp+Yc)} ^1/2 ×100 (1)

(d) Chromaticity a* value and b* value For each measurement sample, according to JIS Z 8781-4: 2013, when measuring the single transmittance Ts, when measuring the parallel transmittance Tp, and when measuring the orthogonal transmittance Tc Chromaticity a* and b* values were measured for each. The above spectrophotometer was used for the measurement, and the C light source was used as the light source. where a*-s and b*-s, a*-p and b*-p, and a*-c and b*-c are the unitary transmittance Ts, the parallel transmittance Tp, and the orthogonal transmittance They respectively correspond to the chromaticity a* and b* values when measuring the rate Tc.

Single transmittance after initial luminosity correction (Ys-s), orthogonal transmittance after initial luminosity correction (Yc- s), the initial 780 nm orthogonal transmittance (Tc780-s), and the initial orthogonal a* value (a*c-s), and after 1000 hours application in a 105° C. environment as a durability test. Single transmittance after luminosity correction (Ys-e), orthogonal transmittance after luminosity correction (Yc-e), 780 nm orthogonal transmittance after durability test (Tc780-e), and durability test The post-orthogonal a* values (a*ce) are shown in Table A1. As a polarizing element, the value of orthogonal transmittance (Tc780-e) at 780 nm after the durability test is preferably 35 or less, more preferably 30 or less.

As shown in Table 1, it can be seen that Examples A1-6 have comparable transmittance and high degree of polarization as compared to Comparative Examples A1 and A2. Furthermore, even after applying 105 ° C. for 1000 hours, compared to the conventional iodine-based polarizing plate (Comparative Example A1), there was less change at 780 nm in the orthogonal position and less change in a * value, and the appearance It can be seen that it has high durability with little change in color. That is, the polarizing plate obtained using the polarizing element of the present invention maintains high durability even in environments where durability such as high temperature is applied, while achieving contrast equivalent to that of conventional iodine-based polarizing plates. I know you are. From the results of the present application, the liquid crystal display device using the polarizing element or polarizing plate of the present invention not only has high brightness and high contrast, but also has high reliability and long-term high contrast.

(e) Degree of Polarization in Near-Infrared Region In Examples A4 to A6, the single transmittance (Ts) at 850 nm, the orthogonal transmittance (Tc), and the degree of polarization (ρ) were measured. The results are shown in Table A2.

As shown in Table 2, it was found that Examples A4 to A6 had a high degree of polarization of 90% or more even at 850 nm, which is an infrared region. On the other hand, in Comparative Example A1, the degree of polarization was slightly less than 3%, and almost no polarization performance could be confirmed. That is, the polarizing plate of the present application not only has a degree of polarization as high as that of an iodine-based polarizing plate in the visible region, but also has a high degree of polarization up to the infrared region. I understand.

<<Example B>>
[Preparation of measurement sample]
(Example B1)
A polyvinyl alcohol film having a degree of saponification of 99% or more and an average degree of polymerization of 2400 (VF-PS manufactured by Kuraray Co., Ltd.) was immersed in hot water at 40° C. for 2 minutes to perform swelling treatment so that the stretching ratio was 1.30 times. Next, the swollen film was treated with 1500 parts by weight of water, 1.5 parts by weight of sodium tripolyphosphate, and 1.5 parts by weight of anhydrous sodium sulfate as a water-soluble compound that absorbs light in the infrared region of 700 nm to 1400 nm. A C.I. I. 0.30 parts by weight of Direct Black 19 (manufactured by SHAOXING BIYING TEXITILE TECHNOLOGY Co., LTD), 0.16 parts by weight of the azo compound shown in Example Compound (5-1) of the present application as the compound of formula (5), and the formula ( 10) 0.040 parts by weight of the azo compound represented by the above formula (10-22) as the compound having the structure of formula (10), .027 parts by weight and 0.16 parts by weight of Kayarus Supra Orange 2GL manufactured by Nippon Kayaku Co., Ltd. were immersed in an aqueous solution adjusted to 45° C. for 13 minutes to incorporate the infrared light absorbing water-soluble compound and the like into the film. . Next, the resulting film was immersed in an aqueous solution prepared by dissolving 40 parts by weight of boric acid (manufactured by Societa chimica lardrello spa) in 2000 parts of water at 30° C. for 2 minutes. Next, the obtained film was stretched in an aqueous solution containing 30.0 g/l of boric acid at 50° C. for 5 minutes at a stretch ratio of 5.0. Next, the obtained film was subjected to immersion treatment (washing treatment) in water at 20° C. for 20 seconds. Next, the resulting film was dried at 70° C. for 9 minutes to obtain a polarizing element. A polarizing plate was obtained by laminating an alkali-treated triacetyl cellulose film (ZRD-60 manufactured by Fuji Film Co., Ltd.) on the resulting polarizing element using a polyvinyl alcohol adhesive. The obtained polarizing plate maintained the optical properties of the polarizing element. The polarizing plate is cut into 40 mm squares and pasted to a transparent plate glass via an adhesive layer (AD-ROC manufactured by Polatechno Co., Ltd.) to prepare a durability test sample using the polarizing plate of the present application, and the measurement of the present application. It was used as a sample.

(Example B2)
The C.I. I. A measurement sample was prepared in the same manner as in Example B1 except that 0.30 parts by weight of Direct Black 19 was replaced with 0.30 parts by weight of S0378 manufactured by FEW CHEMICAL represented by the following formula (102).

(Example B3)
The C.I. I. A measurement sample was prepared in the same manner as in Example B1, except that 0.30 parts by weight of Direct Black 19 was replaced with 0.30 parts by weight of S2180 manufactured by FEW CHEMICAL represented by formula (103).

(Example B4)
The C.I. I. A measurement sample was prepared in the same manner as in Example B1, except that 0.30 parts by weight of Direct Black 19 was replaced with 0.30 parts by weight of the compound shown in Compound Example (1-10) of the present application.

(Example B5)
The C.I. I. A measurement sample was prepared in the same manner as in Example B1, except that 0.30 parts by weight of Direct Black 19 was replaced with 0.30 parts by weight of the compound shown in Compound Example (1-21) of the present application.

(Example B6)
The C.I. I. A measurement sample was prepared in the same manner as in Example B1, except that 0.30 parts by weight of Direct Black 19 was replaced with 1.0 parts by weight of the compound shown in Compound Example (1-10) of the present application.

(Example B7)
Measured in the same manner as in Example B6 except that 0.040 parts by weight of the azo compound represented by the formula (10-22) used in Example B6 was replaced with 0.3 parts by weight of the azo compound represented by the above formula (11-30) A sample was prepared.

(Example B8)
In Example B6, C.I. I. A measurement sample was prepared in the same manner as in Example B6, except that 0.3 parts by weight of Direct Blue 71 (Compound Example 6-9 of the present application) was used.

(Example B9)
In Example B6, C.I. I. A measurement sample was prepared in the same manner as in Example B6, except that 0.3 parts by weight of Direct Blue 69 (Compound Example 6-19 of the present application) was used.

(Example B10)
In Example B6, without using 0.16 parts by weight of the compound shown in the present compound example (5-1) and 0.040 parts by weight of the compound shown in the above formula (10-22), the present compound example (6- A measurement sample was prepared in the same manner as in Example B6, except that 0.3 parts by weight of the azo compound shown in 7) was used and the time for containing the azo compound was changed from 13 minutes to 9 minutes.

(Example B11)
A measurement sample was prepared in the same manner as in Example B10, except that the time for containing the azo compound was changed from 9 minutes to 13 minutes.

(Example B12)
C.I.C. I. A measurement sample was prepared in the same manner as in Example B6, except that 0.040 parts by weight of Direct Red 81 was used.

(Example B13)
Except for replacing 0.027 parts by weight of the compound shown in the present compound example (10-2) used in Example B6 with 0.027 parts by weight of the azo compound of formula (9-23) having the structure of formula (9) prepared a measurement sample in the same manner as in Example B6.

(Example B14)
0.16 parts by weight of Kayarus Supra Orange 2GL used in Example B6 was added to C.I. I. A measurement sample was prepared in the same manner as in Example B6, except that 0.16 parts by weight of Direct Orange 72 was used.

(Example B15)
0.16 parts by weight of Kayarus Supra Orange 2GL used in Example B6 was added to C.I. I. A measurement sample was prepared in the same manner as in Example B6, except that 0.16 parts by weight of Direct Yellow 28 was used.

(Comparative Example B1)
In Example B1, C.I. I. A measurement sample was prepared in the same manner as in Example B1, except that 0.30 parts by weight of Direct Black 19 was not used.

[Evaluation method]
The measurement samples obtained in Examples B1 to B15 and Comparative Example B1 were evaluated as follows.

(a) single transmittance Ts, parallel transmittance Tp, and orthogonal transmittance Tc
In the same manner as in [Evaluation method] (a) of Example A, the single transmittance Ts, the parallel transmittance Tp, and the orthogonal transmittance Tc of each measurement sample were measured.
The average value of each wavelength at 420 to 480 nm, the average value of each wavelength at 520 to 590 nm, and the average value of each wavelength at 600 to 640 nm of each of the parallel transmittance Tp and the orthogonal transmittance Tc, and a single unit of 800 nm Transmittance was determined. The results are shown in Table B1.

(b) Absolute value of difference in average transmittance between two wavelength bands The absolute value of the difference from the average value of each wavelength at ~480 nm and the absolute value of the difference between the average value of each wavelength from 520 to 590 nm and the average value of each wavelength from 600 to 640 nm are shown.

(c) Single Transmittance Ys after Visibility Correction, Parallel Transmittance Yp after Visibility Correction, and Orthogonal Transmittance Yc after Visibility Correction
The single transmittance Ys after luminosity correction of each measurement sample, the parallel transmittance Yp after luminosity correction, and the orthogonal transmittance Yc after luminosity correction were obtained. The single transmittance Ys after the luminosity correction, the parallel transmittance Yp after the luminosity correction, and the orthogonal transmittance Yc after the luminosity correction are in the wavelength region of 400 to 700 nm, with a predetermined wavelength interval dλ (here, 5 nm ) for each of the single transmittance Ts of each wavelength, the parallel transmittance Tp of each wavelength, and the orthogonal transmittance Tc of each wavelength, each of which is corrected to luminosity according to JIS Z 8722: 2009. be. Specifically, the single transmittance Ts of each wavelength, the parallel transmittance Tp of each wavelength, and the orthogonal transmittance Tc of each wavelength are substituted into the following formulas (V) to (VII), and calculated respectively. bottom. In the following formulas (V) to (VII), Pλ represents the spectral distribution of the standard light (C light source), and yλ represents the 2-degree visual field color matching function. The results are shown in Table B3. In this case, a value obtained by dividing Yp by Yc can be represented as contrast (CR).

(d) Degree of polarization after luminosity correction The degree of polarization ρy of each measurement sample after luminosity correction is obtained by the following formula ( VIII).

ρy={(Yp−Yc)/(Yp+Yc)} ^1/2 ×100 (VIII)

(e) Chromaticity a* and b* values In the same manner as in [Evaluation method] (d) of Example A, a*-s and b*-s, a*-p and b*-p, and a* -c and b*-c were measured.

Table B3 shows Ys, Yp, Yc, CR, ρy, and chromaticity of Examples B1 to B15 and Comparative Example B1.

Table B4 shows Tp, Tc, and degree of polarization at infrared wavelengths of 750 nm, 800 nm, and 850 nm for Examples B1 to B15 and Comparative Example B1.

Table B5 lists Tp, Tc, and degree of polarization at 700 nm, a wavelength in the visible region, for initial Examples B6, B10, B11, and Comparative Example B1, and after applying each polarizer at 105°C for 500 hours. shows each value of

From Tables B1 and B2 above, although the polarizing element of the present application is a base material containing a water-soluble compound that absorbs light in the infrared region of 700 nm to 1400 nm, the absorption axes of the two polarizing elements were measured in parallel. The absolute value of the difference between the average transmittance at each wavelength at 520 nm to 590 nm and the average transmittance at each wavelength at 420 nm to 480 nm is 5% or less, and the transmission at each wavelength at 600 nm to 640 nm A polarizing element or a polarizing plate using the same, characterized in that the absolute value of the difference between the average transmittance value and the average transmittance value for each wavelength in the range of 520 nm to 590 nm is 3% or less. I understand. Table B3 shows that the obtained polarizing element has achromaticity, since the absolute values of a*-s and b*-s are both within 1.0. Moreover, since the absolute values of a*-p and b*-p are both 2.0 or less, it can be seen that the polarizing plate achieves high-quality whiteness in the parallel position. On the other hand, it can be seen that Comparative Example B1 has remarkably low absorption and polarization in the infrared region of 700 nm or more. Further, from Table B4, it can be seen that the polarizing plate of the present application has a high degree of polarization in the infrared region while realizing an achromatic color. Further, from Table B5, it can be seen that a polarizing plate with little change in the transmittance of 700 nm, which is the visible region, and the degree of polarization is obtained.

<<Example C>>
[Preparation of measurement sample]
(Example C1)
A polyvinyl alcohol film having a degree of saponification of 99% or more and an average degree of polymerization of 2400 (VF-PS manufactured by Kuraray Co., Ltd.) was immersed in hot water at 40° C. for 2 minutes to perform swelling treatment so that the stretching ratio was 1.30 times. Next, the swollen film was treated with 1500 parts by weight of water, 1.5 parts by weight of sodium tripolyphosphate, 1.5 parts by weight of anhydrous sodium sulfate, and a water-soluble compound that absorbs light in the infrared region of 700 nm to 1400 nm. , having a structure represented by the following formula (101). I. 0.30 parts by weight of Direct Black 19 (manufactured by SHAOXING BIYING TEXITILE TECHNOLOGY Co., LTD), and 0.22 of the azo compound shown in Example Compound (9-23) of the present application as an azo compound having the structure of 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 formula (11), and compound example (13-2) of the present application as a compound having a structure of formula (13) The film was immersed in an aqueous solution containing 0.13 parts by weight of the azo compound shown in Fig. 1 and adjusted to 45°C for 13 minutes and 00 seconds to incorporate the infrared light absorbing water-soluble compound and the like into the film. Next, the resulting film was immersed in an aqueous solution prepared by dissolving 40 parts by weight of boric acid (manufactured by Societa chimica lardrello spa) in 2000 parts of water at 30° C. for 2 minutes. Next, the obtained film was stretched in an aqueous solution containing 30.0 g/l of boric acid at 50° C. for 5 minutes at a stretch ratio of 5.0. Next, the obtained film was subjected to immersion treatment (washing treatment) in water at 20° C. for 20 seconds. Next, the resulting film was dried at 70° C. for 9 minutes to obtain a polarizing element. A polarizing plate was obtained by laminating an alkali-treated triacetyl cellulose film (ZRD-60 manufactured by Fuji Film Co., Ltd.) on the resulting polarizing element using a polyvinyl alcohol adhesive. The obtained polarizing plate maintained the optical properties of the polarizing element. The polarizing plate is cut into 40 mm squares and pasted to a transparent plate glass via an adhesive layer (AD-ROC manufactured by Polatechno Co., Ltd.) to prepare a durability test sample using the polarizing plate of the present application, and the measurement of the present application. It was used as a sample.

(Example C2)
The C.I. I. A measurement sample was prepared in the same manner as in Example C1, except that 0.30 parts by weight of Direct Black 19 was replaced with S0378 (0.30 parts by weight) manufactured by FEW CHEMICAL represented by the following formula (102).

(Example C3)
The C.I. I. A measurement sample was prepared in the same manner as in Example C1, except that 0.30 parts by weight of Direct Black 19 was replaced with S2180 (0.30 parts by weight) manufactured by FEW CHEMICAL represented by formula (103).

(Example C4)
The C.I. I. A measurement sample was prepared in the same manner as in Example C1, except that 0.30 parts by weight of Direct Black 19 was replaced with 0.30 parts by weight of the compound shown in Compound Example (1-10).

(Example C5)
A measurement sample was prepared in the same manner as in Example C1 except that 0.30 parts by weight of the infrared light absorbing water-soluble compound used in Example C1 was replaced with 0.30 parts by weight of the compound shown in Compound Example (1-21). bottom.

(Example C6)
The C.I. I. A measurement sample was prepared in the same manner as in Example C1, except that 0.30 parts by weight of Direct Black 19 was replaced with 1.0 parts by weight of the compound shown in Compound Example (1-10).

(Example C7)
Same as Example C6 except that 0.54 parts by weight of the compound shown in Example Compound (11-45) of the present application used in Example C6 was replaced with 0.33 parts by weight of the azo compound shown in Example Compound (11-5) of the present application. A measurement sample was prepared in the same manner.

(Example C8)
Example C6 except that 0.54 parts by weight of the compound shown in Example Compound (11-45) of the present application used in Example C6 was replaced with 0.33 parts by weight of the azo compound shown in Example Compound (12-12) of the present application. A measurement sample was prepared in the same manner.

(Example C9)
Example C6 except that 0.54 parts by weight of the compound shown in the formula present compound example (11-45) used in Example C6 was replaced with 0.46 parts by weight of the azo compound shown in the present compound example (11-14) A measurement sample was prepared in the same manner.

(Example C10)
0.22 parts by weight of the compound shown in Example Compound (9-23) of the present application used in Example C6 was I. A measurement sample was prepared in the same manner as in Example C6, except that DIRECT RED 81 (Compound Example 10-1 of the present application) was changed to 0.19 parts by weight.

(Example C11)
Same as Example C6 except that 0.22 parts by weight of the compound shown in Example Compound (9-23) of the present application used in Example C6 was replaced with 0.21 parts by weight of the azo compound shown by the following formula (10-85). A measurement sample was prepared.

(Example C12)
Same as Example C6 except that 0.22 parts by weight of the compound shown in Example Compound (9-23) of the present application used in Example C6 was replaced with 0.40 parts by weight of the compound shown in Example Compound (10-51) of the present application. A measurement sample was prepared.

(Example C13)
0.13 parts by weight of the compound shown in Example Compound (13-2) of the present application used in Example C6 was I. A measurement sample was prepared in the same manner as in Example C6, except that 0.11 parts by weight of Direct Orange 72 was used.

(Example C14)
0.13 parts by weight of the compound shown in Example Compound (13-2) of the present application used in Example C6 was I. A measurement sample was prepared in the same manner as in Example C6, except that 0.16 parts by weight of Direct Yellow 28 was used.

(Comparative Example C1)
In Example C1, C.I. I. A measurement sample was prepared in the same manner as in Example C1, except that 0.30 parts by weight of Direct Black 19 was not used.

[Evaluation method]
The measurement samples obtained in Examples C1 to C14 and Comparative Example C1 were evaluated as follows.

(a) single transmittance Ts for each wavelength, parallel transmittance Tp for each wavelength, and orthogonal transmittance Tc for each wavelength
In the same manner as in [Evaluation method] (a) of Example A, the single transmittance Ts of each wavelength, the parallel transmittance Tp of each wavelength, and the orthogonal transmittance Tc of each wavelength of each measurement sample were measured.

(c) Single Transmittance Ys after Visibility Correction, Parallel Transmittance Yp after Visibility Correction, and Orthogonal Transmittance Yc after Visibility Correction
In the same manner as in [Evaluation method] (c) of Example B, the single transmittance Ys after luminosity correction of each measurement sample, the parallel transmittance Yp after luminosity correction, and the orthogonal transmittance after luminosity correction Yc was determined respectively. Results are shown in Table C1. In this case, a value obtained by dividing Yp by Yc can be represented as contrast (CR).

(d) Degree of polarization The degree of polarization ρy was obtained in the same manner as in [Evaluation method] (d) of Example B.

Ys, Yp, Yc, CR, and ρy of Examples C1 to C14 and Comparative Example C1 are shown in Table C1.

Table C2 shows Tp, Tc, and degrees of polarization at near-infrared wavelengths of 750 nm, 800 nm, and 850 nm for Examples C1 to C14 and Comparative Example C1.

Table C3 shows the Tp, Tc, and degree of polarization at 700 nm, which is the wavelength in the visible region, of Example C6 and Comparative Example C1 at the initial stage, and each value after applying each polarizing plate at 105 ° C. for 500 hours. .

Tables C1 and C2 show that the polarizing element of the present application has a high degree of polarization in the visible region while containing a water-soluble compound or its salt that absorbs light in the infrared region of 700 nm to 1400 nm. Furthermore, from Table C2, it can be seen that the polarizing element of the present application not only absorbs light in the infrared region, but also has high polarizing performance. From this, it can be seen that the polarizing element of the present application has a high degree of polarization from the visible region to the infrared region. In addition, from Table C3, it can be seen that a polarizing plate with little change in the transmittance of 700 nm, which is the visible region, and the degree of polarization is obtained. Therefore, it can be seen that the polarizing plate of the present application has high durability. I understand.

As shown in Tables C1 to C3 above, the polarizing element or polarizing plate of the present application has absorption in the infrared region while realizing achromaticity in the visible region, and has a high degree of polarization. It can be seen that a broadband polarizing plate having a high degree of polarization up to the outer region is obtained. It was also shown that the polarizing plate can achieve high durability in the visible region.

The polarizing element or polarizing plate of the present invention can be used for liquid crystal displays, organic EL, liquid crystal projectors, calculators, clocks, notebook computers, word processors, liquid crystal televisions, polarizing lenses, polarizing glasses, car navigation systems, indoor and outdoor measuring instruments and displays. devices, infrared sensors, infrared cameras, optical isolators, security systems and other optical devices. In particular, it can be effectively used in reflective liquid crystal display devices, transflective liquid crystal display devices, organic electroluminescence devices, and the like.

Claims (16)

A polarizing element comprising at least one dichroic dye exhibiting polarization characteristics at 400 nm to 700 nm and a water-soluble compound or its salt absorbing light at 700 nm to 1400 nm ,
The polarizing element contains iodine as the at least one dichroic dye,
At least one of the orthogonal transmittance at a wavelength of 780 nm is 3.569% or less and the degree of polarization at a wavelength of 850 nm is 90% or more,
Polarizing element. 2. The polarizing element according to claim 1, wherein the water-soluble compound is an azo compound. The polarizing element according to claim 2, wherein the azo compound is an azo compound represented by the following formula (1):

wherein Ai ₁ and Ai ₂ are each independently represented by a hydrogen atom, an azo group, or the following formula (2) (excluding those in which both Ai ₁ and Ai ₂ are hydrogen atoms),
—NH— is bound to both naphthalene rings at any position of combinations of a and a′, b and b′, a and b′, and b and a′,

In the formula, each of the rings substituted by Ri ₁ is independently a benzene ring when the ring represented by the dashed line does not exist, and a naphthalene ring when the ring represented by the dashed line exists. ,
Ri ₁ each independently represents a chlorine atom, a sulfo group, a nitro group, a hydroxy 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 having a sulfo group, C1-4 alkyl group having a hydroxy group, C1-4 alkyl group having a carboxy group, C1-4 alkoxy group having a sulfo group, C1-4 alkoxy group having a hydroxy group or an alkoxy group having 1 to 4 carbon atoms having a carboxy group,
Each Bi is independently a phenylene group which may have a substituent or a naphthylene group which may have a substituent, and the substituents may be a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxy 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 having a sulfo group, an alkyl group having 1 to 4 carbon atoms having a hydroxy group, and a carboxy group an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, an alkoxy group having 1 to 4 carbon atoms having a hydroxy group, or an alkoxy group having 1 to 4 carbon atoms having a carboxy group; ,
m represents an integer of 1 to 3,
When Bi has a hydroxy group as a substituent, the hydroxy group can form -O-Cu-O- with the hydroxy group in the above formula (1) and the copper atom. ) The polarizing element according to claim 3 , wherein formula (2) is represented by formula (3):

In the formula, the ring in which Ri ₁ is substituted, Ri ₁ and m are respectively the same as in formula (2),
The oxygen atom represented by the -O- bond forms -O-Cu-O- with -OH and the copper atom in formula (1),
Ri ₂ is a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxy 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 having a sulfo group, hydroxy C 1-4 alkyl group having a group, C 1-4 alkyl group having a carboxy group, C 1-4 alkoxy group having a sulfo group, C 1-4 alkoxy group having a hydroxy group , or an alkoxy group having 1 to 4 carbon atoms having a carboxy group. The polarizing element according to claim 3 , wherein the azo compound represented by the formula (1) is an azo compound represented by the following formula (4):

In the formula, Ri ₃ is a hydrogen atom, a chlorine atom, a sulfo group, a nitro group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkyl having 1 to 4 carbon atoms having a sulfo group. C 1-4 alkyl group having a hydroxy group, C 1-4 alkyl group having a carboxy group, C 1-4 alkoxy group having a sulfo group, C 1-4 having a hydroxy group or an alkoxy group having 1 to 4 carbon atoms having a carboxy group,
m is the same as in formula (2). The polarizing element according to any one of claims 1 to 5, further comprising a compound represented by formula (5) or formula (6) or a salt thereof as the at least one dichroic dye:

In the formula, Ab ₁ and Ab ₂ each independently represent a substituted naphthyl group or a substituted phenyl group, at least one of which is a hydrogen atom, a sulfo group, or an alkyl group having 1 to 4 carbon atoms. , an alkoxy group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, a carboxy group, a nitro group, an amino group, or a substituted amino group;
Rb ₁ and Rb ₂ each 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 having a sulfo group;

wherein Ag ₁ represents 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), at least one of which represents formula (7),
Xg ₁ is an optionally substituted amino group, an optionally substituted phenylamino group, an optionally substituted phenylazo group, or an optionally substituted showing a good benzoylamino group,

In the formula, Rg ₁ 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;
k represents an integer of 0 to 2,

In the formula, Rg ₂ and Rg ₃ each independently represent 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 sulfo group and having 1 to 4 carbon atoms. Claim 1, wherein the at least one dichroic dye further comprises 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. 7. The polarizing element according to any one of 6 :

wherein Ab ₁ represents a phenyl or naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group;
Rb ₁₁ to Rb ₁₄ each independently represent 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 a _sulfo group; and Rb ₁₆ each independently represents an alkoxy group having 1 to 4 carbon atoms,
Xb ₁ consists 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 hydroxy group, a carboxy group and a carboxyethylamino group. an amino group optionally having at least one substituent selected from the group, a phenylamino group optionally having a substituent, a phenylazo group optionally having a substituent, a substituent optionally having represents a naphthotriazole group, an optionally substituted benzoylamino group, or an optionally substituted benzoyl group,
d represents 0 or 1;

wherein Ab ₂ represents a phenyl or naphthyl group having at least one substituent selected from the group consisting of a sulfo group and a carboxy group;
Rb ₂₁ 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 having a sulfo group; at least one substituent selected from the group consisting of an alkyl group, an alkoxy group having 1 to 4 carbon atoms, an alkylamine group having 1 to 4 carbon atoms, a hydroxy group, a carboxy group, a sulfo group, an amino group and a substituted amino group; optionally substituted amino group, optionally substituted phenylamino group, optionally substituted phenylazo group, optionally substituted naphthotriazole group, optionally substituted It represents a benzoylamino group or a benzoyl group which may have a substituent. The polarizing element according to any one of claims 1 to 7 , further comprising an azo compound represented by the following formula (13) or a salt thereof as the at least one dichroic dye:

In the formula, Ay ₁ represents a hydrogen atom, a sulfo group, a carboxy group, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms,
Ry ₁ and Ry ₂ are each independently 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 having a sulfo group. represents
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. The polarizing element according to any one of claims 1 to 9 , having a degree of polarization of 99% or more at a wavelength of 850 nm . The transmittance obtained when the two polarizing elements are stacked so that their absorption axes are parallel to each other,
The difference between the average transmittance of each wavelength of 520 nm to 590 nm and the average transmittance of each wavelength of 420 nm to 480 nm is 5% or less as an absolute value, and the average transmittance of each wavelength of 600 nm to 640 nm and 520 nm to 590 nm The difference between the average value of the average transmittance of each wavelength is 3% or less as an absolute value,
The polarizing element according to any one of claims 1-10 . According to JIS Z 8781-4: 2013, the absolute values of the a* and b* values obtained when measuring the transmittance of natural light are
Both of the polarizing elements alone are 1 or less (-1 ≤ a*-s ≤ 1, -1 ≤ b*-s ≤ 1),
When the two polarizing elements are stacked so that their absorption axes are parallel to each other, both are 2 or less (-2 ≤ a*-p ≤ 2, -2 ≤ b*-p ≤ 2). ,
The polarizing element according to any one of claims 1 to 11 (a*-s indicates an a* value of a single unit, b*-s indicates a b* value of a single unit, and a*-p is a parallel (b*-p indicates b* in parallel position). In the transmittance obtained in a state in which the two polarizing elements are stacked so that their absorption axes are orthogonal to each other,
The difference between the average transmittance of each wavelength of 520 nm to 590 nm and the average transmittance of each wavelength of 420 nm to 480 nm is 3% or less as an absolute value, and the average transmittance of each wavelength of 600 nm to 640 nm and 520 nm to 590 nm The difference between the average transmittance of each wavelength is 2% or less as an absolute value,
The polarizing element according to any one of claims 1-12 . A polarizing plate comprising 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. 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 according to claim 15 , which is a liquid crystal display.