Luminescent compound or its salt, and polarized light emitting element, polarized light emitting plate and display device containing the same

Abstract

A luminescent compound or a salt thereof, wherein the luminescent compound is represented by the following formula (1).

Description

Technical Field

[0001] The present invention relates to a novel luminescent compound or a salt thereof, and a polarized light emitting element, a polarized light emitting plate and a display device (display) containing the compound. Background Art

[0002] Polarizing plates with light transmission and / or shielding functions are basic components of display devices such as liquid crystal displays (LCDs) together with liquid crystals with light switching functions. The application fields of this LCD have expanded from small machines such as early computers and clocks to notebook computers, word processors, liquid crystal projectors, liquid crystal televisions, car navigation, and indoor and outdoor measuring machines. In addition, it can also be applied to lenses with polarizing functions, such as sunglasses for improving visibility, or polarized glasses for 3D televisions in recent years. As mentioned above, polarizing plates have a wide range of uses, and their use environment has also expanded from low temperature to high temperature, low humidity to high humidity, low light intensity to high light intensity, etc., so polarizing plates with high polarization performance and high durability are required.

[0003] Generally speaking, the polarizing film constituting the polarizing plate is manufactured by stretching and aligning a film of polyvinyl alcohol or its derivatives containing iodine or dichroic dyes, or by dehydrating a polyvinyl chloride film or dehydrating a polyvinyl alcohol film to generate polyene and aligning it. Since the polarizing plate composed of such a conventional polarizing film contains a dichroic pigment having absorption in the visible light region, the transmittance is reduced. For example, the transmittance of a general polarizing plate sold on the market is 35 to 45%.

[0004] In order to solve the problem of conventional polarizing plates that the transmittance in the visible light region is reduced, as a technology that maintains a certain degree of transmittance in the visible light region and imparts a polarizing function, a technology for a polarizing plate for ultraviolet light is described in Patent Document 1. However, this technology uses a yellow pigment that absorbs in the visible light region, so the transmittance is insufficient and dark yellow coloring is confirmed.

[0005] If a polarizing plate with low transmittance in the visible light region is used in a display or the like, the transmittance of the entire display will be reduced, so a method of obtaining polarized light without using a conventional polarizing plate has been studied. As such a method, Patent Documents 2 to 4 describe a polarized light emitting element.

[0006] However, the polarized light emitting elements described in Patent Documents 2 to 4 contain special metals, such as rare and expensive metals such as lanthanide elements or europium, so the cost is high. In addition, the manufacturing is very difficult and not conducive to mass production. In addition, these polarized light emitting elements are difficult to use in displays because the polarized light emission is weak, and linear polarized light emission cannot be obtained. Therefore, it is required to develop a novel polarized light emitting plate that exhibits polarized light emission, has high transparency in the visible light region, and can be used in liquid crystal displays that require durability in harsh environments, and a material for forming the polarized light emitting plate.

[0007] [Prior art literature]

[0008] [Patent Document]

[0009] Patent Document 1: WO2005 / 015275

[0010] Patent Document 2: Japanese Patent Application Publication No. 2008-224854

[0011] Patent Document 3: Japanese Patent Application Publication No. 2013-121921

[0012] Patent document 4: WO2011 / 111607. Summary of the invention

[0013] [Problems to be solved by the invention]

[0014] The object of the present application is to provide a novel luminescent compound, and a polarized light emitting element, a polarized light emitting plate and a display device containing the compound.

[0015] [Methods to solve the problem]

[0016] The present inventors have devoted themselves to research to achieve this purpose, and found that a polarized light-emitting element and a polarized light-emitting plate containing a compound or a salt thereof having a specific structure have a high dichroic ratio in the ultraviolet region, high transmittance in the visible region, and excellent durability under harsh environments. In addition, the compound or a salt thereof having such a specific structure exhibits the effect of emitting polarized light in the visible region by irradiating light in the ultraviolet region to the near-ultraviolet visible region, such as light of 300 to 430 nm, thereby completing the present invention.

[0017] That is, the present invention is related to the following, but is not limited thereto.

[0018] [Invention 1]

[0019] A light-emitting compound or a salt thereof, wherein the light-emitting compound is a compound represented by the following formula (1).

[0020]

[0021] (In formula (1), (i) X and Y each independently include at least one selected from the group consisting of a group represented by formula (2), a heterocyclic group containing a nitrogen atom or a sulfur atom, and a nitro group, but excluding the case where both X and Y are nitro groups; or (ii) at least one of X and Y (each independently) is a nitro group, an amino group which may have a substituent, a C1 to 4 alkyl group which may have a substituent, a C1 to 4 alkoxy group which may have a substituent, an aromatic group which may have a substituent, a heterocyclic group containing an oxygen atom, a nitrogen atom or a sulfur atom which may have a substituent, or a group represented by formula (2), wherein X or Y is not a group selected from the above, and the X or Y is selected from any substituent,

[0022] M each independently represents a hydrogen atom, a metal ion, or an ammonium ion, m each independently represents an integer from 0 to 2, s is 0 or 1,

[0023] In formula (2), ※ represents the bonding position of X and / or Y in formula (1), Z is selected from the group consisting of a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a stilbene group which may have a substituent, a benzoyl group which may have a substituent, and a heterocyclic group which may have a substituent, and t represents an integer of 0 or 1).

[0024] [Invention 2]

[0025] A luminescent compound or a salt thereof as described in Invention 1, wherein X, Y in the above formula (1), and when at least one of X and Y is a compound represented by the above formula (2), at least one of Z in the above formula (2) is selected from the group consisting of substituents represented by the following formulas (3) to (7).

[0026]

[0027] (In the above formulae (3) and (4), A is each independently selected from the group consisting of a hydrogen atom, a halogen group, a nitro group, a hydroxyl group, a C1-4 alkyl group, a C1-4 alkoxy group, a C1-4 alkyl group having a sulfonic acid group, a C1-4 alkyl group having a hydroxyl group, a C1-4 alkyl group having a carboxyl group, a C1-4 alkoxy group having a sulfonic acid group, a C1-4 alkoxy group having a hydroxyl group, and a C1-4 alkoxy group having a carboxyl group, and q 1 represents an integer from 0 to 4, M in the above formulae (3) to (7) is as defined in the above formula (1), and n 1 and n 2 Each independently represents an integer from 0 to 3, and * in the above formulae (3) to (7) respectively represents the bonding position of X or Y in the above formula (1), or the bonding position of Z in the above formula (2).

[0028] [Invention 3]

[0029] A luminescent compound or a salt thereof as described in Invention 1 or 2, wherein X and Y in the above formula (1) are each independently selected from the group consisting of substituents represented by formulas (2) to (7), and when formula (2) is selected, Z is selected from the group consisting of substituents represented by formulas (3) to (7).

[0030] [Invention 4]

[0031] A luminescent compound or salt thereof as described in Invention 1 or 2, wherein X and Y in the above formula (1) are both selected from the group consisting of substituents represented by formulas (2) to (7), and when formula (2) is selected, Z is selected from the group consisting of substituents represented by formulas (3) to (7).

[0032] [Invention 5]

[0033] The luminescent compound or the salt thereof according to any one of Inventions 1 to 4, wherein each m in the above formula (1) is 0.

[0034] [Invention 6]

[0035] The luminescent compound or the salt thereof according to any one of Inventions 1 to 5, wherein s is 0.

[0036] [Invention 7]

[0037] The luminescent compound or the salt thereof according to any one of Inventions 1 to 5, wherein s is 1.

[0038] [Invention 8]

[0039] The luminescent compound or the salt thereof according to Invention 7, wherein the above formula (1) is represented by the following formula (1').

[0040]

[0041] (In the above formula (1'), X and Y are respectively as defined in the above formula (1)).

[0042] [Invention 9]

[0043] A polarized light emitting element having a polarized light emitting function, comprising the luminescent compound or a salt thereof according to any one of Inventions 1 to 8.

[0044] [Invention 10]

[0045] The polarized light emitting element according to Invention 9 further contains one or more organic dyes or fluorescent dyes other than the above-mentioned light emitting compound or its salt.

[0046] [Invention 11]

[0047] The polarized light emitting element according to Invention 9 or 10 further comprises a substrate.

[0048] [Invention 12]

[0049] In the polarized light emitting element according to Invention 11, the substrate is a film containing a polyvinyl alcohol resin or a derivative thereof.

[0050] [Invention 13]

[0051] A polarized light emitting plate comprising a transparent protective film on at least one side of the polarized light emitting element according to any one of Inventions 9 to 12.

[0052] [Invention 14]

[0053] A display device comprising the polarized light emitting element according to any one of Inventions 9 to 12 or the polarized light emitting plate according to Invention 13.

[0054] [Effects of the invention]

[0055] The luminescent compound or its salt with a specific structure of the present invention absorbs light from ultraviolet light to the visible light region, such as light from the ultraviolet light region to the near-ultraviolet visible light region, specifically 300 to 430nm light, and uses its energy to display polarized light luminescence in the visible light region. In addition, the polarizing element and polarizing plate made using the luminescent compound or its salt are novel polarized light luminescent elements and polarized light luminescent plates showing polarized light luminescence. In one aspect, the luminescent compound or its salt of the present invention and the polarized light luminescent element and polarized light luminescent plate containing the compound show high polarization in the absorption wavelength. Therefore, by using a compound or its salt as shown in formula (1), even if rare and expensive lanthanide metals are not used, a high polarization degree can be provided in the absorption wavelength, and a novel polarized light luminescent element and polarized light luminescent plate showing polarized light luminescence can be provided. In one aspect, the polarized light luminescent element and polarized light luminescent plate of the present invention show high transmittance in the visible light region. In one aspect, the polarized light luminescent element and polarized light luminescent plate of the present invention show excellent durability with respect to heat, humidity, etc. Therefore, the polarized light emitting element and the polarized light emitting plate can be applied to display devices such as liquid crystal displays that require high transmittance in the visible light region and high durability in harsh environments. DETAILED DESCRIPTION

[0056] In the present specification and claims, "substituent" conveniently includes hydrogen atom. "May have a substituent" means that it also includes the case of not having a substituent. For example, "phenyl group which may have a substituent" includes unsubstituted simple phenyl group and phenyl group which has a substituent.

[0057] [Luminescent Compounds]

[0058] The light-emitting compound or a salt thereof of the present invention is represented by the above-mentioned formula (1). In the present specification, "light-emitting compound or a salt thereof" may be simply referred to as "light-emitting compound".

[0059] In formula (1), (i) X and Y each independently include at least one selected from the group consisting of the group represented by formula (2), a heterocyclic group containing a nitrogen atom or a sulfur atom, and a nitro group, excluding the case where both X and Y are nitro groups; or (ii) at least one of X and Y (each independently) is a nitro group, an amino group which may have a substituent, an alkyl group having 1 to 4 carbon atoms which may have a substituent, an alkoxy group having 1 to 4 carbon atoms which may have a substituent, an aromatic group which may have a substituent, a heterocyclic group containing an oxygen atom, a nitrogen atom or a sulfur atom which may have a substituent, or a group represented by formula (2), wherein when X or Y is not a group selected from the above, the X or Y is selected from any substituent,

[0060] M each independently represents a hydrogen atom, a metal ion, or an ammonium ion, m each independently represents an integer from 0 to 2, and s is 0 or 1.

[0061] In formula (2), ※ represents the bonding position of X and / or Y in formula (1), Z is selected from the group consisting of a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a stilbene group which may have a substituent, a benzoyl group which may have a substituent, and a heterocyclic group which may have a substituent, and t represents an integer of 0 or 1.

[0062] The above-mentioned "amino group which may have a substituent" in the definition of X and Y includes, for example, amino group; monosubstituted amino groups such as methylamino group, ethylamino group, n-butylamino group, aniline group, naphthylamino group, acetylamino group (that is, acetamide group); disubstituted amino groups such as dimethylamino group, diethylamino group, di-n-butylamino group, diphenylamino group, ethylmethylamino group, ethylaniline group, etc. In addition, the above-mentioned formula (2) described later is also included in the amino group which may have a substituent.

[0063] Examples of the "C1-4 alkyl group" of the "C1-4 alkyl group which may have a substituent" in the definitions of X and Y include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl and cyclobutyl.

[0064] Examples of the "C1-4 alkoxy group" in the "C1-4 alkoxy group which may have a substituent" in the definitions of X and Y include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy and cyclobutoxy.

[0065] Examples of the “aromatic group” in the above-mentioned “aromatic group which may have a substituent” in the definitions of X and Y include phenyl, naphthyl, anthracenyl and the like.

[0066] The "heterocyclic group containing a nitrogen atom or a sulfur atom" in the definition of X and Y means a heterocyclic ring having at least one of a nitrogen atom and a sulfur atom as a ring constituent, and the "heterocyclic group containing an oxygen atom, a nitrogen atom or a sulfur atom" in the above-mentioned "heterocyclic group containing an oxygen atom, a nitrogen atom or a sulfur atom which may have a substituent" means a heterocyclic ring having at least one of an oxygen atom, a nitrogen atom and a sulfur atom as a ring constituent. These include not only monocyclic heterocyclic rings but also polycyclic heterocyclic rings in which the monocyclic heterocyclic ring further contains an aromatic ring such as a benzene ring or a naphthalene ring. Examples of the "heterocyclic group containing an oxygen atom, a nitrogen atom or a sulfur atom" include pyrrolyl, benzopyrrolyl, thienyl, benzothienyl, thiazolyl, benzothiazolyl, naphthiazolyl, triazolyl, benzotriazolyl, naphthiatriazolyl, thiadiazolyl, benzothiadiazolyl, pyridyl and the like.

[0067] The substituents in the above-mentioned "amino group which may have a substituent", "C1 to 4 alkyl group which may have a substituent", "C1 to 4 alkoxy group which may have a substituent", "aromatic group which may have a substituent" and "heterocyclic group containing an oxygen atom, a nitrogen atom or a sulfur atom which may have a substituent" are not particularly limited, and examples thereof include hydroxyl group, cyano group, phosphoric acid group, sulfonic acid group, carboxyl group, amino group, etc. The "amino group which may have a substituent" may further have a substituent as exemplified herein.

[0068] In the above formula (1), M each independently represents a hydrogen atom, a metal ion, or an ammonium ion. Examples of the metal ion include alkali metal ions such as lithium ions, sodium ions, and potassium ions, and alkaline earth metal ions such as calcium ions and magnesium ions. Examples of the ammonium ion include ammonium ions in a narrow sense (NH 4 + ), methylammonium ion, dimethylammonium ion, triethylammonium ion, tetraethylammonium ion, tetra-n-propylammonium ion, tetra-n-butylammonium ion, monoethanolammonium ion, diethanolammonium ion, triethanolammonium ion, monoisopropanolammonium ion, diisopropanolammonium ion, triisopropanolammonium ion, triethanolammonium ion, etc. More specifically, for example, when M is a hydrogen atom, it represents a sulfonic acid (-SO 3 H), when M is sodium ion, it means sodium sulfonate (-SO 3 Na), when M is ammonium ion, it means ammonium sulfonate (-SO 3 NH 4 Among these, preferred ones include lithium ions, ammonium ions, and sodium ions.

[0069] In the above formula (2), ※ represents the bonding position of X and / or Y in formula (1), Z is selected from the group consisting of a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a stilbene group which may have a substituent, a benzoyl group which may have a substituent, and a heterocyclic group which may have a substituent. t represents an integer of 0 or 1.

[0070] The above-mentioned "heterocyclic group which may have a substituent" in the definition of Z may be the same as, for example, the "heterocyclic group containing an oxygen atom, a nitrogen atom or a sulfur atom which may have a substituent" in the definitions of X and Y in the above formula (1), and may also be a furanyl group, a benzofuranyl group or the like containing an oxygen atom as a ring component.

[0071] Preferred substituents for the above-mentioned "phenyl group which may have a substituent" in the definition of Z include C1-4 alkoxy groups, nitro groups, sulfonic acid groups, and substituents represented by formulae (3) to (7). Preferred substituents for the above-mentioned "naphthyl group which may have a substituent" in the definition of Z include hydroxyl groups, sulfonic acid groups, nitro groups, and C1-4 alkoxy groups having sulfonic acid groups. Preferred substituents for the above-mentioned "stilbene group which may have a substituent" in the definition of Z include sulfonic acid groups, nitro groups, amine groups which may have a substituent, and substituents represented by formulae (3) to (7). Z Preferred substituents for the above-mentioned “benzoyl group which may have a substituent” in the definition of are, for example, a sulfonic acid group, a nitro group, etc. Preferred substituents for the above-mentioned “heterocyclic group which may have a substituent” in the definition of Z are, for example, a sulfonic acid group, a halogen group, a hydroxyl group, a C1-4 alkyl group, a C1-4 alkoxy group, a C1-4 alkyl group having a sulfonic acid group, a C1-4 alkyl group having a hydroxyl group, a C1-4 alkyl group having a carboxyl group, a C1-4 alkoxy group having a sulfonic acid group, a C1-4 alkoxy group having a hydroxyl group, a C1-4 alkoxy group having a carboxyl group, etc.

[0072] Examples of the "halogen group" in the definition of Z include a fluoro group, a chloro group, a bromo group, and an iodo group.

[0073] Examples of the "C1-4 alkyl group" in the definition of Z include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl and cyclobutyl.

[0074] Examples of the "C1-4 alkoxy group" in the definition of Z include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy and cyclobutoxy.

[0075] The above-mentioned "C1-4 alkyl group having a sulfonic acid group", "C1-4 alkyl group having a hydroxyl group" and "C1-4 alkyl group having a carboxyl group" in the definition of Z can be exemplified by having a sulfonic acid group, a hydroxyl group or a carboxyl group as a substituent at any position of the above-mentioned "C1-4 alkyl group".

[0076] The above-mentioned "C1-4 alkoxy group having a sulfonic acid group", "C1-4 alkoxy group having a hydroxyl group" and "C1-4 alkoxy group having a carboxyl group" in the definition of Z can be exemplified by having a sulfonic acid group, a hydroxyl group or a carboxyl group as a substituent at any position of the above-mentioned "C1-4 alkoxy group".

[0077] More preferably, X, Y in the above formula (1), and when at least one of X and Y is represented by the above formula (2), at least one of Z in the above formula (2) is selected from the group consisting of substituents represented by the above formulas (3) to (7).

[0078] In the above formula (3) and formula (4), A is independently selected from the group consisting of a hydrogen atom, a halogen group, a nitro group, a hydroxyl group, a C1-4 alkyl group, a C1-4 alkoxy group, a C1-4 alkyl group having a sulfonic acid group, a C1-4 alkyl group having a hydroxyl group, a C1-4 alkyl group having a carboxyl group, a C1-4 alkoxy group having a sulfonic acid group, a C1-4 alkoxy group having a hydroxyl group, and a C1-4 alkoxy group having a carboxyl group, and q 1 represents an integer from 0 to 4, M in the above formulae (3) to (7) is as defined in the above formula (1), and n 1 and n 2 Each independently represents an integer of 0 to 3, and * in the above formulae (3) to (7) respectively represents the bonding position of X or Y in the above formula (1), or the bonding position of Z in the above formula (2).

[0079] Examples of the "C1-4 alkyl group" in the definition of A include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, and cyclobutyl.

[0080] Examples of the "C1-4 alkyl group having a sulfonic acid group" in the definition of A include sulfomethyl, sulfoethyl, sulfo-n-propyl, sulfo-n-butyl, and sulfo-sec-butyl.

[0081] Examples of the "halogen group" in the definition of A include a fluoro group, a chloro group, a bromo group, an iodo group and the like.

[0082] Examples of the "C1-4 alkoxy group" in the definition of A include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy and cyclobutoxy.

[0083] Examples of the "C1-4 alkyl group having a hydroxy group" in the definition of A include hydroxymethyl, hydroxyethyl, hydroxy-n-propyl, hydroxyisopropyl, hydroxy-n-butyl, hydroxy-sec-butyl, hydroxy-tert-butyl and hydroxycyclobutyl.

[0084] Examples of the "C1-4 alkyl group having a carboxyl group" in the definition of A include carboxymethyl, carboxyethyl, carboxy-n-propyl, carboxy-isopropyl, carboxy-n-butyl, carboxy-sec-butyl, carboxy-tert-butyl and carboxycyclobutyl.

[0085] Examples of the "C1 to 4 alkoxy group having a sulfonic acid group" in the definition of A include sulfonic acid methoxy, sulfonic acid ethoxy, sulfonic acid n-propoxy, sulfonic acid isopropoxy, sulfonic acid n-butoxy, sulfonic acid sec-butoxy, sulfonic acid tert-butoxy, and sulfonic acid cyclobutoxy.

[0086] Examples of the "C1-4 alkoxy group having a hydroxy group" in the definition of A include hydroxymethoxy, hydroxyethoxy, hydroxy-n-propoxy, hydroxy-isopropoxy, hydroxy-n-butoxy, hydroxy-sec-butoxy, hydroxy-tert-butoxy and hydroxycyclobutoxy.

[0087] Examples of the "C1-4 alkoxy group having a carboxyl group" in the definition of A include carboxymethoxy, carboxyethoxy, carboxy-n-propoxy, carboxy-isopropoxy, carboxy-n-butoxy, carboxy-sec-butoxy, carboxy-tert-butoxy and carboxycyclobutoxy.

[0088] It is more preferred that at least one of X and Y in the above formula (1) is selected from the group consisting of substituents represented by formulas (2) to (7), and when formula (2) is selected, Z is selected from the group consisting of substituents represented by formulas (3) to (7). It is more preferred that X and Y in the above formula (1) are each independently selected from the group consisting of substituents represented by formulas (2) to (7), and when formula (2) is selected, Z is selected from the group consisting of substituents represented by formulas (3) to (7). It is even more preferred that both X and Y in the above formula (1) are selected from the group consisting of substituents represented by formulas (2) to (7), and when formula (2) is selected, Z is selected from the group consisting of substituents represented by formulas (3) to (7).

[0089] In one aspect of the present invention, each m is 0.

[0090] In one aspect of the present invention, s is 0.

[0091] In one aspect of the present invention, s is 1. In this aspect, the above formula (1) is more preferably represented by the above formula (1'). In the formula (1'), X and Y are respectively as defined in the above formula (1).

[0092] Next, a method for synthesizing the compound represented by formula (1) wherein s is 0 is described.

[0093] For example, one equivalent of the compound represented by formula (9) and one equivalent of the compound represented by formula (10) are heated in water, sodium hydroxide is added and dissolved, and one equivalent of terephthaloyl chloride represented by formula (8) which is commercially available is added and reacted to obtain the target product.

[0094]

[0095] In the above formulae (8) to (10), each of X, Y, M, and m is as defined in the above formula (1).

[0096] Next, specific examples of the light-emitting compound or its salt represented by the above formula (1) wherein s is 0 are listed below. In addition, the sulfonic acid group and the like in the formula are represented in the form of a free acid.

[0097]

[0098]

[0099] Next, a method for synthesizing the compound represented by formula (1) wherein s is 1 is described.

[0100] For example, one equivalent of the compound represented by the following formula (8-A) and one equivalent of the compound represented by the following formula (8-B) are heated in water, sodium hydroxide is added and dissolved, and one equivalent of terephthaloyl chloride represented by the commercially available formula (8) is added and reacted to obtain the target product.

[0101]

[0102] In formula (8), (8-A) and (8-B), X, Y, M and m are respectively defined as in formula (1).

[0103] Next, specific examples of the light-emitting compound or its salt represented by the above formula (1) wherein s is 1 are given below. In addition, the sulfonic acid group and the like in the formula are represented in the form of a free acid.

[0104]

[0105]

[0106] The compound represented by the above formula (1) or its salt can be used as a compound capable of polarized light emission. The compound represented by formula (1) or its salt, and one or more organic dyes or fluorescent dyes other than the optional luminescent compound or its salt are combined, and are contained in a substrate, such as a polymer film such as polyvinyl alcohol or its derivatives, and oriented by a publicly known method, thereby manufacturing a polarized light-emitting element. The obtained polarized light-emitting element is attached with a transparent protective film and used as a polarized light-emitting plate, and a hard coating (protective layer) or AR (anti-reflection) layer and a support are optionally further provided on the polarized light-emitting plate, and is applied to liquid crystal projectors, computers, clocks, notebook computers, word processors, liquid crystal televisions, car navigation, safety displays, anti-counterfeiting, and indoor and outdoor measuring instruments or displays, lenses, glasses, etc. In addition, in this specification, organic dyes or fluorescent dyes other than the luminescent compound or its salt of the present invention are sometimes referred to as "other organic dyes".

[0107] [Polarized light emitting element]

[0108] The present invention also includes a polarized light emitting device containing the light emitting compound represented by the above formula (1) or a salt thereof.

[0109] The polarized light emitting element preferably contains the luminescent compound represented by formula (1) or its salt, and a substrate on which the polarized light emitting compound or its salt is adsorbed and aligned. The polarized light emitting element may contain one or more of the luminescent compound represented by formula (1) or its salt.

[0110] The substrate is preferably a film obtained by forming a hydrophilic polymer film that can adsorb the luminescent compound or its salt shown in the above formula (1). The hydrophilic polymer is not particularly limited, and examples thereof include polyvinyl alcohol resins, straight-chain starch resins, starch resins, cellulose resins, and polyacrylate resins. Among such resins, polyvinyl alcohol resins or derivatives thereof are more preferably used from the viewpoints of the adsorption, processability, and orientation of the luminescent compound or its salt shown in the above formula (1). Any polyvinyl alcohol resin derivative generally known in the art can be used as the polyvinyl alcohol resin derivative. Although not particularly limited, examples thereof include unsaturated carboxylic acids such as crotonic acid, acrylic acid, methacrylic acid, and maleic acid, unsaturated sulfonic acids such as ethylene sulfonic acid, propylene sulfonic acid, methacrylic acid, p-styrene sulfonic acid, 2-acrylamide-2-methylpropane sulfonic acid, (meth)acryloyloxyethyl sulfonic acid, or modified polyvinyl alcohol resins copolymerized with olefins such as ethylene or propylene and vinyl alcohol. The shape of the substrate is not particularly limited, and the substrate can be made into any shape, such as a film, a sheet, a flat plate, a curved plate, a hemispherical shape, etc. The thickness of the substrate is usually 10 to 100 μm, and more preferably 20 to 80 μm.

[0111] The content of the luminescent compound represented by the above formula (1) in the above polarized light-emitting element is not particularly limited, and the content can be set according to any transmittance, and the blending amount (content) can be arbitrarily set according to the transmittance required by the polarized light-emitting element. The polarization performance of the polarized light-emitting element will not only change due to the blending ratio of the luminescent compound represented by the formula (1) contained in the polarized light-emitting element, but also due to various factors such as the swelling degree of the substrate adsorbing the luminescent compound, the elongation ratio, the dyeing time, the dyeing temperature, the pH during dyeing, the influence of salt, etc. Therefore, the blending ratio of the luminescent compound represented by the formula (1) contained in the polarized light-emitting element can be determined according to the swelling degree of the substrate, the dyeing temperature, the dyeing time, the pH during dyeing, the salt type, the salt concentration, the elongation ratio, etc. The above blending ratio can be adjusted appropriately.

[0112] The above-mentioned polarized light emitting element may optionally further contain one or more other organic dyes in the range that does not hinder the polarization performance or for the purpose of color adjustment. There is no particular limitation on the other organic dyes used in combination, but it is preferably a dye with high dichroism, and it is more preferably a dye that has less influence on the polarization performance of the absorption band region of the luminescent compound shown in formula (1), such as the ultraviolet region to the near-ultraviolet visible region. Other organic dyes used in combination can be cited as CI direct yellow 12, CI direct yellow 28, CI direct yellow 44, CI direct orange 26, CI direct orange 39, CI direct orange 71, CI direct orange 107, CI direct red 2, CI direct red 31, CI direct red 79, CI direct red 81, CI direct red 247, CI direct blue 69, CI direct blue 78, CI direct green 80, and CI direct green 59. These other organic dyes can be in the form of free acids, alkali metal salts (such as Na salts, K salts, and Li salts), ammonium salts, or amine salts.

[0113] When the above-mentioned other organic dyes are optionally used in combination, the types of other organic dyes to be blended can be selected according to the purpose of color adjustment of the polarized light-emitting element to be manufactured. In addition, the content thereof is not particularly limited, and generally, when the mass of the luminescent compound represented by the above formula (1) is 1, the total mass of the other organic dyes used is preferably in the range of 0.01 to 10.

[0114] <Method for manufacturing polarized light emitting element>

[0115] Next, the method for manufacturing the polarized light-emitting element of the present invention is described. The manufacturing method is not limited to the following method, and may include the following steps: a step of preparing a substrate; a swelling step of immersing the substrate in a swelling liquid and extending the substrate by swelling; a dyeing step of immersing the swollen substrate in a dyeing solution containing at least one luminescent compound represented by the above formula (1) and allowing the substrate to adsorb the luminescent compound represented by the formula (1); a crosslinking step of immersing the substrate adsorbed with the luminescent compound represented by the formula (1) in a solution containing a crosslinking agent such as boric acid to crosslink the luminescent compound represented by the formula (1) in the substrate; a stretching step of uniaxially stretching the crosslinked substrate represented by the luminescent compound represented by the formula (1) in a fixed direction to arrange the luminescent compound represented by the formula (1) in a fixed direction; a washing step of washing the stretched substrate with a washing liquid; and a drying step of drying the washed substrate.

[0116] (Prepare the substrate)

[0117] A substrate containing the luminescent compound represented by the above formula (1) is prepared. The substrate can be, for example, a commercially available film containing a polyvinyl alcohol resin or a derivative thereof, and the substrate can be prepared by film-forming the polyvinyl alcohol resin. The film-forming method of the polyvinyl alcohol resin is not particularly limited, and for example, publicly known film-forming methods such as a method of melt-extruding aqueous polyvinyl alcohol, a cast film-forming method, a wet film-forming method, a gel film-forming method (temporarily cooling a polyvinyl alcohol aqueous solution to gel, and then extracting and removing the solvent), a casting film-forming method (flowing a polyvinyl alcohol aqueous solution on a substrate and drying it), and a combination of these methods can be used. The degree of polymerization of polyvinyl alcohol can be polyvinyl alcohol having a degree of polymerization of 1000 to 10000, and the degree of polymerization is preferably 1500 to 6000, and more preferably 2000 to 6000.

[0118] (Swelling step)

[0119] Next, the substrate is subjected to a swelling treatment. The swelling treatment is preferably performed by immersing the substrate in a swelling liquid at 20 to 50° C. for 30 seconds to 10 minutes, and the swelling liquid is preferably water. The stretching ratio of the swelling liquid to the substrate is preferably adjusted to 1.00 to 1.50 times, and more preferably adjusted to 1.10 to 1.35 times.

[0120] (Dyeing Steps)

[0121] Then, the substrate obtained by the swelling treatment as described above is adsorbed and impregnated with at least one luminescent compound represented by formula (1) or its salt. The dyeing step is not particularly limited as long as it is a method for adsorbing and impregnating the substrate with the luminescent compound represented by formula (1) or its salt. For example, it is more preferred to immerse the substrate in a dyeing solution containing the luminescent compound represented by formula (1) or its salt. Alternatively, the adsorption can also be achieved by coating the dyeing solution on the substrate. The concentration of the luminescent compound represented by formula (1) or its salt in the dyeing solution is not particularly limited as long as the luminescent compound represented by formula (1) or its salt can be sufficiently adsorbed in the substrate. For example, it is more preferably 0.0001 to 3% by mass in the dyeing solution, and more preferably 0.001 to 1% by mass.

[0122] The temperature of the dyeing solution in the dyeing step is preferably 5 to 80° C., more preferably 20 to 50° C., and particularly preferably 40 to 50° C. In addition, the time for immersing the substrate in the dyeing solution can be appropriately adjusted, preferably between 30 seconds and 20 minutes, and more preferably between 1 to 10 minutes.

[0123] As the compound contained in the above-mentioned dyeing solution, the luminescent compound represented by the above-mentioned formula (1) can be used alone or in combination of two or more. In this way, the luminescent compound represented by the above-mentioned formula (1) will have different luminescent colors due to structural differences. Therefore, by making the substrate contain two or more luminescent compounds represented by the above-mentioned formula (1) or their salts, or the luminescent compound represented by the above-mentioned formula (1) or its salt and one or more other luminescent compounds, the luminescent color produced can be appropriately adjusted to the desired color. In addition, the dyeing solution may optionally further contain one or more of the above-mentioned other organic dyes. In the description of the manufacture of polarized light-emitting elements and polarized light-emitting plates in this specification, the luminescent compounds represented by formula (1) and other organic dyes are sometimes collectively referred to as "polarizing pigments".

[0124] The dyeing solution may optionally further contain a dyeing auxiliary in addition to the polarizing pigment. Examples of the dyeing auxiliary include sodium carbonate, sodium bicarbonate, sodium chloride, sodium sulfate (glauber's salt), anhydrous sodium sulfate, and sodium tripolyphosphate, and sodium sulfate is more preferred. The content of the dyeing auxiliary may be arbitrarily adjusted according to the dyeability of the polarizing pigment used, by the immersion time and the temperature of the dyeing solution, but is more preferably 0.1 to 10% by mass, more preferably 0.1 to 2% by mass, in the dyeing solution.

[0125] After the dyeing step, a preliminary washing step may be arbitrarily performed in order to remove the dyeing solution attached to the surface of the substrate in the dyeing step. By performing the preliminary washing step, the luminescent compound represented by formula (1) or its salt remaining on the surface of the substrate can be inhibited from being transferred to the treatment solution in the following step. In the preliminary washing step, water is generally used as the washing liquid. The washing method is preferably to immerse the dyed substrate in the washing liquid. On the other hand, the substrate can also be washed by applying the washing liquid to the substrate. The washing time is not particularly limited, but is preferably 1 to 300 seconds, and more preferably 1 to 60 seconds. In the preliminary washing step, the temperature of the washing liquid needs to be a temperature that does not dissolve the material constituting the substrate, and the washing treatment is generally performed at 5 to 40°C. In addition, even if there is no preliminary washing step, it will not significantly affect the performance of the polarized light-emitting element, so the preliminary washing step can also be omitted.

[0126] (Cross-linking step)

[0127] After the dyeing step or the preliminary washing step, a crosslinking agent may be included in the substrate. The method of including a crosslinking agent in the substrate is preferably to immerse the substrate in a treatment solution containing a crosslinking agent. On the other hand, the treatment solution can be coated or applied to the substrate. The crosslinking agent in the treatment solution is preferably a solution containing boric acid. The solvent in the treatment solution is not particularly limited, and water is more preferred. The concentration of the crosslinking agent such as boric acid in the treatment solution is preferably 0.1 to 15% by mass, and more preferably 0.1 to 10% by mass. The temperature of the treatment solution is preferably 30 to 80°C, and more preferably 40 to 75°C. In addition, the treatment time of the crosslinking step is more preferably 30 seconds to 10 minutes, and more preferably 1 to 6 minutes. The method for manufacturing a polarized light-emitting element of the present invention has the crosslinking step, and the resulting polarized light-emitting element can emit light with high brightness and high polarization. This is an excellent effect that is completely unexpected by the function of boric acid used in the prior art for the purpose of improving moisture resistance or light transmittance. In addition, in the crosslinking step, an aqueous solution containing a cationic polymer compound can be optionally used to further perform a fixing treatment. Polarized pigments can be fixed by fixation treatment. At this time, cationic polymer compounds can be, for example, cationic releasing compounds, dicyano compounds, polyamine compounds, polycationic compounds, dimethyldiallyl ammonium chloride / dioxide ion copolymers, diallylamine salt polymers, dimethyldiallyl ammonium chloride polymers, polymers of allylamine salts, and quaternary salt polymers of dialkylaminoethyl acrylate. Examples of dicyano compounds include dicyandiamide / formalin polycondensates. Examples of polyamine compounds include dicyandiamide / diethylenetriamine polycondensates. Examples of polycationic compounds include epichlorohydrin / dimethylamine addition polymers.

[0128] (Extended Steps)

[0129] The stretching step may be performed after or at the same time as the crosslinking step. The stretching step is performed by uniaxially stretching the substrate in a fixed direction. The stretching method may be either a wet stretching method or a dry stretching method. The stretching ratio is preferably 3 times or more, more preferably 5 to 9 times.

[0130] In the dry stretching method, when the stretching heating medium is an air medium, it is more preferred to stretch the substrate at a temperature of the air medium of room temperature to 180°C. In addition, the humidity is preferably in an environment of 20 to 95% RH. The substrate heating method may include, for example, a roller zone stretching method, a roller heating stretching method, a hot inter-pressure stretching method, and an infrared heating stretching method, but is not limited to these stretching methods. The dry stretching step may be implemented with a single stretching step or with a multi-stage stretching step of two or more stages.

[0131] In the wet stretching method, it is more preferred to stretch the substrate in water, a water-soluble organic solvent, or a mixed solution thereof. It is more preferred to perform the stretching treatment while immersing the substrate in a solution containing at least one cross-linking agent. The cross-linking agent may be, for example, boric acid in the cross-linking agent step, and it is more preferred to perform the stretching treatment in the treatment solution used in the cross-linking step. The stretching temperature is more preferably 40 to 70°C, more preferably 45 to 60°C. The stretching time is generally 30 seconds to 20 minutes, more preferably 2 to 7 minutes. The wet stretching step may be implemented with a single stretching step or with more than two stretching steps. In addition, the stretching treatment may also be arbitrarily performed before the dyeing step, in which case the orientation of the luminescent compound represented by formula (1) or its salt may be performed together at the time of dyeing.

[0132] (Washing Steps)

[0133] After the extension step is performed, the crosslinking agent may be precipitated or foreign matter may be attached to the surface of the substrate, so a washing step may be performed to wash the surface of the substrate. The washing time is preferably 1 second to 5 minutes. The washing method is preferably to immerse the substrate in a washing liquid, but on the other hand, the washing liquid may be applied or coated on the substrate. The washing liquid is preferably water. The washing treatment may be performed in one stage or in multiple stages of two or more stages. The temperature of the washing liquid in the washing step is not particularly limited, and is usually 5 to 50°C, preferably 10 to 40°C, and may also be room temperature.

[0134] The solvent of the solution or treatment liquid used in each of the above steps may be, in addition to the above water, alcohols, amines, etc. Alcohols may be, for example, dimethyl sulfoxide, N-methylpyrrolidone (Methyl pyrrolidone), methanol, ethanol, propanol, isopropanol, glycerol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and trimethylolpropane, etc. Amines may be, for example, ethylenediamine and diethylenetriamine, etc. The solvent of the solution or treatment liquid is not limited to these, but water is most preferably used. In addition, the solvent of these solutions or treatment liquids may be used alone or as a mixture of two or more.

[0135] (Drying Step)

[0136] After the washing step, it is preferred to perform a drying step of the substrate. The drying treatment may be performed by natural drying, but in order to improve the drying efficiency, it may be performed by compression with a roller, or by removing surface moisture with an air knife or a water-absorbing roller, etc., and air drying may also be performed. The temperature of the drying treatment 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.

[0137] The polarized light emitting element of the present invention can be manufactured by taking the above description as an example. In addition, the luminescent compound represented by formula (1) in the present invention can be oriented by a method of mixing with liquid crystal and aligning on a substrate, or by a method of sharing and coating on a substrate, thereby manufacturing polarized light emitting elements with various colors or neutral gray.

[0138] [Polarized light panel]

[0139] The present invention also includes a polarized light emitting plate including the polarized light emitting element.

[0140] The polarized light emitting plate of the present invention preferably has a transparent protective film on at least one side of the polarized light emitting element. The transparent protective film is used to improve the water resistance or handleability of the polarized light emitting element. Therefore, such a transparent protective film is preferably a transparent protective film that does not have any effect on the polarization effect displayed by the polarized light emitting element of the present invention.

[0141] The above-mentioned transparent protective film is preferably a transparent protective film with excellent optical transparency and mechanical strength. In addition, the transparent protective film is preferably a film with a layer shape that can maintain the shape of the polarized light-emitting element. In addition to transparency and mechanical strength, it is more preferably a plastic film that is also excellent in thermal stability and moisture shielding. The material forming such a transparent protective film can be cellulose acetate film, acrylic film, fluorine film such as tetrafluoroethylene / hexafluoropropylene copolymer, or a film composed of polyester resin, polyolefin resin or polyamide resin, etc., and it is more preferred to use triacetyl cellulose (TAC) film or cycloolefin film. The thickness of the transparent protective film is more preferably in the range of 1 to 200 μm, more preferably in the range of 10 to 150 μm, and particularly preferably 40 to 100 μm. The method for manufacturing the polarized light-emitting plate of the present invention is not particularly limited. For example, a polarized light-emitting plate can be made by overlapping a transparent protective film on a polarized light-emitting element and laminating it with a publicly known formula.

[0142] The polarized light emitting plate may further include an adhesive layer between the transparent protective film and the polarized light emitting element for bonding the transparent protective film to the polarized light emitting element. The adhesive constituting the adhesive layer is not particularly limited, and examples thereof include polyvinyl alcohol adhesives, urethane emulsion adhesives, acrylic adhesives, polyester isocyanate adhesives, etc., and polyvinyl alcohol adhesives are preferably used. After bonding the transparent protective film and the polarized light emitting element with the adhesive, drying or heat treatment is performed at an appropriate temperature, thereby manufacturing the polarized light emitting plate.

[0143] In addition, the polarized light emitting plate may be appropriately provided with various publicly known functional layers such as an anti-reflection layer, an anti-glare layer, and a reinforced transparent protective film on the exposed surface of the transparent protective film. When preparing layers having such various functions, it is more preferred to apply materials having various functions to the exposed surface of the transparent protective film. On the other hand, the layer or film having such functions may be attached to the exposed surface of the transparent protective film via an adhesive or a bonding agent.

[0144] The above-mentioned reinforced transparent protective film may be, for example, a hard coating layer of acrylic, urethane, or polysiloxane. In addition, in order to further improve the monomer transmittance, an anti-reflection layer may be provided on the exposed surface of the transparent protective film. The anti-reflection layer may be formed, for example, by vapor-depositing or sputtering silicon dioxide, titanium oxide, or the like on the transparent protective film, or by thinly coating a fluorine-based material on the transparent protective film.

[0145] The polarized light emitting plate may be further provided with a transparent support such as glass, crystal, sapphire, etc. In order to fit the polarized light emitting plate, the support is preferably provided with a planar portion. In addition, from the viewpoint of optical use, a transparent support is more preferably provided. The transparent support is divided into an inorganic support and an organic support. For example, the support composed of inorganic materials may include supports formed by materials such as sodium glass, borosilicate glass, crystal, sapphire, spinel, etc., and the organic support may include supports composed of materials such as acrylate, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, cycloolefin polymer, etc. The thickness and size of the transparent support are not particularly limited and may be appropriately determined. In addition, in the polarized light emitting plate having such a transparent support, in order to further improve the monomer transmittance, it is more preferably provided with an anti-reflection layer on one or both sides of the support surface or the polarized light emitting plate surface. In order to bond the polarized light emitting plate to the plane of the support, a transparent adhesive can be applied to the plane of the support, and then the polarized light emitting plate of the present invention can be attached to the coated surface. The adhesive or adhesive used is not particularly limited, and commercially available products can be used, preferably an acrylic adhesive or adhesive.

[0146] In addition, the above-mentioned polarized light emitting plate can be used as a circularly polarized light emitting plate or an elliptically polarized light emitting plate with a phase difference plate attached. At this time, when a support body is further provided on the polarized light emitting plate, the support body can be a phase difference plate. The phase difference plate generally includes a phase difference plate with a phase difference value of 1 / 4λ or a phase difference plate with a phase difference value of 1 / 2λ relative to the absorption wavelength or emission wavelength of light, but is not limited thereto. By having a phase difference value of 1 / 4λ, it functions as a circular polarizer or a circularly polarized light emitting plate relative to the wavelength, and by using 1 / 2λ, it can be used to convert the polarization to a 90° direction. As described above, various functional layers, supports, etc. can be further provided on the polarized light emitting plate, so that the polarized light emitting plate can be used, for example, for liquid crystal projectors, computers, clocks, laptops, word processors, liquid crystal televisions, car navigation, and various products such as lenses or displays for indoor and outdoor measuring instruments or displays, or glasses.

[0147] The polarized light emitting element and polarized light emitting plate of the present invention can show high polarization in the light of ultraviolet region to near ultraviolet visible light region, for example, in the region of 300 to 430nm, and also show polarized light emitting effect and high transmittance in the visible light region. In addition, the polarized light emitting element and polarized light emitting plate of the present invention show excellent durability with respect to heat, humidity, light, etc., so even in harsh environments, their performance can be maintained, and they have high durability compared to the previous iodine-based polarizer system. Therefore, the polarized light emitting element and polarized light emitting plate of the present invention can be applied to liquid crystal displays requiring high transparency in the visible light region and high durability in harsh environments, such as televisions, portable terminals, tablet terminals, smart phones, car displays, digital signage for outdoor or indoor use, smart windows and other various display devices.

[0148] [Display device]

[0149] The present invention also includes a display device (display) including the above-mentioned polarized light emitting element or polarized light emitting plate.

[0150] The above-mentioned display device can display polarized light emission by irradiating light from the ultraviolet region to the visible light region, for example, light from the ultraviolet region to the near-ultraviolet visible light region, specifically, light of 300 to 430 nm, and can display by utilizing this effect. The display device of the present invention has a high transmittance in the visible light region, so there is no reduction in transmittance in the visible light region like the previous polarizing plate. Even if there is a reduction in transmittance, the reduction in transmittance is significantly reduced compared to the transmittance of the previous polarizing plate. For example, the iodine-based polarizing plate that belongs to the previous polarizing plate, or the dye-based polarizing plate using other dyes, in order to make the polarization degree almost 100%, the visibility in the visible light region is corrected to about 35 to 45%. The reason is: the previous polarizing plate has both a longitudinal axis and a transverse axis as the absorption axis of light, but in order to obtain a polarization degree of almost 100%, it is necessary to absorb the incident light of one of the longitudinal axis or the transverse axis, that is, to absorb light in one axis and generate polarization in the other axis by transmitting light. At this time, the light of one axis is absorbed without penetration, so the transmittance will inevitably become less than 50%. In addition, in the past, polarizing plates were made to align dichroic pigments in stretched films, but dichroic pigments are not necessarily 100% aligned, and also have a slight absorption component relative to the transmission axis of light. Therefore, if the transmittance is not reduced to about 45% or less by reflection on the surface of the material, it is impossible to achieve almost 100% polarization, that is, if the transmittance is not reduced, it is impossible to achieve high polarization. In this regard, the polarized light-emitting element and polarized light-emitting plate of the present invention have an axis (its polarization function) that absorbs light from the ultraviolet region to the near-ultraviolet visible light region, for example, 300 to 430nm, that is, it has the effect of absorbing light for the light from the ultraviolet region to the near-ultraviolet visible light region, for example, 300 to 430nm, and shows a polarized light-emitting effect of emitting polarized light in the visible light region. On the other hand, it hardly absorbs light in the visible light region, so the transmittance in the visible light region is very high. In addition, the polarized light emitting effect is displayed in the visible light region, so the light loss is less than that using the previous polarizing plate, that is, the decrease in the transmittance of the previous polarizing plate is very small. Therefore, the display device using the polarized light emitting element and the polarized light emitting plate of the present invention, such as a liquid crystal display, can obtain high brightness compared to the liquid crystal display with the previous polarizing plate. In addition, the display device using the polarized light emitting element and the polarized light emitting plate of the present invention has high transparency, so although it is a liquid crystal display, it can be an almost transparent display. In addition, when displaying text and images, the polarized light emission can be designed to be penetrable, so although it is a transparent liquid crystal display, a display that can be displayed can be obtained, that is, a display that can display text, etc. on a transparent display can be obtained. Therefore, the display device of the present invention can obtain a transparent liquid crystal display without light loss, and in particular, a perspective display can be obtained.

[0151] In addition, the display device can also be polarized with respect to light in the ultraviolet region to the near ultraviolet visible region that is invisible or difficult to be seen by the human eye, for example, with respect to light of 300 to 430 nm, so it can be applied to a liquid crystal display that can display by ultraviolet light. For example, an image displayed in the ultraviolet region to the near ultraviolet visible region can be confirmed by a computer, etc., and accordingly, a simple and highly safe liquid crystal display can be made, which can be seen only when irradiated with light in the ultraviolet region to the near ultraviolet visible region, for example, light of 300 to 430 nm.

[0152] In addition, the display device irradiates light from the ultraviolet region to the near ultraviolet visible region, such as light of 300 to 430 nm, and thereby displays polarized light emission, and a liquid crystal display utilizing the polarized light emission can be manufactured, so it is not a general liquid crystal display using visible light, but a liquid crystal display utilizing light from the ultraviolet region to the near ultraviolet visible region. That is, a light-emitting liquid crystal display can be manufactured, which can display text, images, etc. to be displayed in a dark space without visible light, as long as it is a space that can irradiate light from the ultraviolet region to the near ultraviolet visible region.

[0153] In addition, the bands of light in the visible light region and the ultraviolet light region are different, so a display can be made that has two different displays at the same time, which is a liquid crystal display part in the visible light region that can be displayed by light in the visible light region, and a liquid crystal display part that displays light by polarized light luminescence caused by ultraviolet light. So far, there are displays that can perform two different displays, but there is no display in which the same liquid crystal panel can perform different displays by different light sources in the ultraviolet light region and the visible light region. In this regard, the display device of the present invention can produce a novel display by using the above-mentioned polarized light emitting element or polarized light emitting plate.

[0154] The present invention also includes a liquid crystal display having the above-mentioned polarized light emitting element, polarized light emitting plate or display device. The liquid crystal cell used in the liquid crystal display is not limited to, for example, a TN liquid crystal cell, an STN liquid crystal cell, a VA liquid crystal cell, an IPS liquid crystal cell, etc., and can be used in various liquid crystal display modes. The liquid crystal display has high durability, so a liquid crystal display for vehicle use or outdoor display can be provided.

[0155] The present invention also includes a neutral gray polarized light-emitting plate for vehicle or outdoor display having the above-mentioned polarized light-emitting element, polarized light-emitting plate or display device. The neutral gray polarized light-emitting plate for vehicle or outdoor display has excellent polarized light-emitting performance, and does not change color or reduce polarization performance even under high temperature and high humidity conditions inside the vehicle or outdoors. In addition, neutral gray means that the transmittance of each wavelength in the orthogonal position of the visible light region of the polarized light-emitting plate is significantly reduced, or has a fixed transmittance. Specifically, the orthogonal position transmittance is less than 0.3%, more preferably less than 0.1%, more preferably less than 0.03%, and particularly preferably less than 0.01%. The fixed transmittance means that the difference in transmittance relative to the average transmittance of each wavelength is within 1%.

[0156] [Example]

[0157] The present invention is further described in detail below by examples, but the present invention is not limited to these exemplified examples. In addition, the "%" and "parts" recorded below are weight references unless otherwise specified. In addition, in each structural formula of the compound used in each example and comparative example, the acidic functional groups such as sulfonic acid group are recorded in the form of free acid.

[0158] [Example 1]

[0159] (synthesis example)

[0160] 84 parts of the compound represented by formula (25) were added to 600 parts of water and heated to 60°C. While adjusting the pH to 6 to 7, 25% sodium hydroxide was added to dissolve the compound. 20.2 parts of terephthaloyl chloride were added in small portions over about 1 hour. After all the additions were made, the mixture was stirred at 60°C for 1 hour and reacted. After the reaction was completed, the mixture was cooled to room temperature and filtered. The solid obtained was dried at 70°C to obtain 67.4 parts of the compound represented by formula (15).

[0161]

[0162] (Manufacturing of polarized light emitting elements and polarized light emitting plates)

[0163] A polyvinyl alcohol film (VF-PS#7500 manufactured by Kuraray Co., Ltd.) with a thickness of 75 μm was immersed in water at 40°C for 3 minutes to swell the film. The swollen film was immersed in a 45°C aqueous solution containing 0.2 parts by mass of the compound represented by formula (15) obtained in Synthesis Example 1, 1.0 parts by mass of Glauber's salt, and 1000 parts by mass of water for 4 minutes to contain the compound represented by formula (15) in the film. The film containing the compound represented by formula (15) was stretched 5 times in a 3% concentration boric acid aqueous solution at 50°C for 5 minutes. The stretched film was washed with water at room temperature for 20 seconds while maintaining tension, and dried at 70°C to obtain a polarized light-emitting element. On both sides of the obtained polarized light emitting element, a 60 μm thick triacetate cellulose film (ZRD-60 manufactured by FUJIFILM) containing no ultraviolet absorber and surface saponified with 1.5N sodium hydroxide was laminated with a 4 mass % polyvinyl alcohol (NH-26 manufactured by JAPAN VAN & POVAL) aqueous solution as an adhesive to obtain a polarized light emitting plate, which was used as a measurement sample for Example 1.

[0164] In addition, even if a triacetyl cellulose film (ZRD-60 manufactured by FUJIFILM) containing no ultraviolet absorber is attached to the polarized light emitting element, it will not affect the optical properties of the polarized light emitting element. The following examples and comparative examples also attach a triacetyl cellulose film containing no ultraviolet absorber to the polarized light emitting element, and similarly, it will not affect the optical properties.

[0165] [Example 2]

[0166] Add 60 parts of the compound represented by formula (26) to 600 parts of water and heat to 60°C. While adjusting the pH to 6 to 7, add 25% sodium hydroxide to dissolve the compound. Add 20 parts of terephthaloyl chloride in small portions over about 1 hour. After all the addition, stir at 60°C for 1 hour and react. After the reaction is completed, cool to room temperature and filter, and dry the resulting solid at 70°C to obtain 51.5 parts of the compound represented by formula (14). In the preparation of the polarized light-emitting element and the polarized light-emitting plate of Example 1, the measurement sample of Example 2 is obtained in the same manner, except that the compound represented by formula (14) is used instead of the compound represented by formula (15).

[0167]

[0168] [Example 3]

[0169] 21.8 parts of the compound represented by formula (27) and 10.8 parts of the compound represented by formula (28) were added to 400 parts of water, and 25% sodium hydroxide was added while adjusting the pH to 6 to 7 to dissolve the aforementioned compounds. 15.6 parts of phenyl chloroformate were stirred at 50 to 70°C for 6 hours and ureidated. Salting out with sodium chloride, filtering, and drying at 70°C to obtain 24.6 parts of the ureido compound represented by formula (29). 24.6 parts of the obtained compound represented by formula (29) were added to 500 parts of water and heated to 60°C, and 25% sodium hydroxide was added while adjusting the pH to 6 to 7 to dissolve the aforementioned compounds. 7.0 parts of terephthaloyl chloride were added in small portions over about 1 hour. After all the additions were made, stirring was performed at 60°C for 1 hour to react. After the reaction was completed, the mixture was cooled to room temperature and filtered, and the obtained solid was dried at 70°C to obtain 5.7 parts of a mixture of the compound represented by formula (16) and the compound represented by formula (30). In the preparation of the polarized light-emitting element and the polarized light-emitting plate of Example 1, the measurement sample of Example 3 is obtained in the same manner except that a mixture of the compound represented by formula (16) and the compound represented by formula (30) is used to replace the compound represented by formula (15).

[0170]

[0171] [Example 4]

[0172] 21.8 parts of the compound represented by formula (28) are added to 400 parts of water, and sodium hydroxide is added while dissolving it. 20.2 parts of terephthaloyl chloride are added in small portions over about 1 hour. After all the additions are made, stir at 60°C for 1 hour and react. After the reaction is completed, 80.0 parts of 4-nitro-4'-aminostilbene-2,2'-disulfonic acid are added, and sodium hydroxide is added while dissolving it. 31.2 parts of phenyl chloroformate are added in small portions over about 1 hour. After all the additions are made, stir at 60°C for 1 hour and react. After the reaction is completed, cool to room temperature and filter, and dry the obtained solid at 70°C to obtain 12.4 parts of a mixture of the compound represented by formula (18) and the compound represented by formula (31). In the preparation of the polarized light-emitting element and the polarized light-emitting plate of Example 1, the measurement sample of Example 4 is obtained in the same manner except that a mixture of the compound represented by formula (18) and the compound represented by formula (31) is used to replace the compound represented by formula (15).

[0173]

[0174] [Example 5]

[0175] 40.0 parts of 4-nitro-4'-aminostilbene-2,2'-disulfonic acid and 10.8 parts of the compound represented by formula (28) are added to 400 parts of water, and sodium hydroxide is added while dissolving them. 20.2 parts of terephthaloyl chloride are added in small portions over about 1 hour. After all the additions are made, the mixture is stirred at 60°C for 1 hour and reacted. After the reaction is completed, 40.0 parts of 4-nitro-4'-aminostilbene-2,2'-disulfonic acid are added, and sodium hydroxide is added while dissolving them. 15.6 parts of phenyl chloroformate are added in small portions over about 1 hour. After all the additions are made, the mixture is stirred at 60°C for 1 hour and reacted. After the reaction is completed, the mixture is cooled to room temperature and filtered, and the obtained solid is dried at 70°C to obtain 8.9 parts of a mixture of the compound represented by formula (22) and the compound represented by formula (32). In the preparation of the polarized light-emitting element and the polarized light-emitting plate of Example 1, the measurement sample of Example 5 is obtained in the same manner except that a mixture of the compound represented by formula (22) and the compound represented by formula (32) is used to replace the compound represented by formula (15).

[0176]

[0177] [Example s1]

[0178] Add 120.4 parts of the compound represented by formula (s28) to 500 parts of water and heat to 60°C. While adjusting the pH to 6 to 7, add 25% sodium hydroxide to dissolve the compound. Add 20.2 parts of terephthaloyl chloride in small portions over about 1 hour. After all the addition, stir at 60°C for 1 hour and react. After the reaction is completed, cool to room temperature and filter, and dry the resulting solid at 70°C to obtain 93.4 parts of the compound represented by formula (s29). In the preparation of the polarized light-emitting element and polarized light-emitting plate of Example 1, the measurement sample of Example s1 is obtained in the same manner, except that the compound represented by formula (s29) is used instead of the compound represented by formula (15).

[0179]

[0180] [Example s2]

[0181] Add 114 parts of the compound represented by formula (s30) to 500 parts of water and heat to 60°C. While adjusting the pH to 6 to 7, add 25% sodium hydroxide to dissolve the compound. Add 20.2 parts of terephthaloyl chloride in small portions over about 1 hour. After all the addition, stir at 60°C for 1 hour and react. After the reaction is completed, cool to room temperature and filter, and dry the resulting solid at 70°C to obtain 103 parts of the compound represented by formula (s14). In the preparation of the polarized light-emitting element and the polarized light-emitting plate of Example 1, the measurement sample of Example s2 is obtained in the same manner, except that the compound represented by formula (s14) is used instead of the compound represented by formula (15).

[0182]

[0183] [Example s3]

[0184] 40 parts of 4-nitro-4'-aminostilbene-2,2'-disulfonic acid and 60.2 parts of the compound represented by formula (s28) are added to 500 parts of water and heated to 60°C. While adjusting the pH to 6 to 7, 25% sodium hydroxide is added to dissolve the aforementioned compounds. 20.2 parts of terephthaloyl chloride are added in small portions over about 1 hour. After all are added, stir at 60°C for 1 hour and react. After the reaction is completed, cool to room temperature and filter, and dry the obtained solid at 70°C to obtain 84.1 parts of the compound represented by formula (s31). In the preparation of the polarized light-emitting element and the polarized light-emitting plate of Example 1, the measurement sample of Example s3 is obtained in the same manner, except that the compound represented by formula (s31) is used instead of the compound represented by formula (15).

[0185]

[0186] [Example s4]

[0187] 21.8 parts by weight of the compound represented by formula (s32) and 37 parts by weight of 4,4'-diaminostilbene-2,2'-disulfonic acid are added to 500 parts of water and heated to 60°C. While adjusting the pH to 6 to 7, 25% sodium hydroxide is added to dissolve the aforementioned compounds. 20.2 parts of terephthaloyl chloride are added in small portions over about 1 hour. After all are added, stir at 60°C for 1 hour and react. After the reaction is completed, cool to room temperature and filter, and dry the resulting solid at 70°C to obtain 24.5 parts of a mixture of compounds represented by formula (s15) and formula (s33). In the preparation of the polarized light-emitting element and polarized light-emitting plate of Example 1, the measurement sample of Example s4 is obtained in the same manner, except that a mixture of compounds represented by formula (s15) and formula (s33) is used instead of the compound represented by formula (15).

[0188]

[0189] [Example s5]

[0190] 40 parts of 4-nitro-4'-aminostilbene-2,2'-disulfonic acid are added to 500 parts of water and heated to 60°C. While adjusting the pH to 6 to 7, 25% sodium hydroxide is added to dissolve the aforementioned compound. 15.6 parts of phenyl chloroformate and 37 parts of 4,4'-diaminostilbene-2,2'-disulfonic acid are added in small portions over about 1 hour. After all are added, stir at 60°C for 1 hour. To the resulting solution, 10.1 parts of terephthaloyl chloride are added in small portions over about 1 hour. After all are added, stir at 60°C for 1 hour and react. After the reaction is completed, cool to room temperature and filter, and dry the resulting solid at 70°C to obtain 22.3 parts of the compound represented by formula (s19). In the preparation of the polarized light-emitting element and polarized light-emitting plate of Example 1, the measurement sample of Example s5 is obtained in the same manner except that the compound represented by formula (s19) is used instead of the compound represented by formula (15).

[0191]

[0192] [Comparative Example 1]

[0193] In the preparation of the polarized light emitting element and polarized light emitting plate of Example 1, the measurement sample of Comparative Example 1 was obtained in the same manner except that the compound represented by formula (c1) described in Japanese Patent Application Laid-Open No. 4-226162 was used instead of the compound represented by formula (15).

[0194]

[0195] [Comparative Example 2]

[0196] In the preparation of the polarized light emitting element and the polarized light emitting plate of Example 1, the measurement sample of Comparative Example 2 was obtained in the same manner except that CI Direct Yellow 4 of the compound represented by formula (c2) was used instead of the compound represented by formula (15).

[0197]

[0198] [Comparative Example 3]

[0199] In the preparation of the polarized light emitting element and the polarized light emitting plate of Example 1, the measurement sample of Comparative Example 3 was obtained in the same manner except that the compound represented by formula (c3) was used instead of the compound represented by formula (15).

[0200]

[0201] [evaluate]

[0202] Evaluation was performed in the following manner using the measurement samples obtained in Examples 1 to 5 and s1 to s5 and Comparative Examples 1 to 3.

[0203] (a) Measurement of single-element transmittance Ts, parallel position transmittance Tp, and orthogonal position transmittance Tc

[0204] The single transmittance Ts (%), parallel transmittance Tp (%), and orthogonal transmittance Tc (%) of each measurement sample were measured using a spectrophotometer ("U-4100" manufactured by Hitachi, Ltd.). Here, the single transmittance Ts (%) is the transmittance of each wavelength when measuring one measurement sample. The parallel transmittance Tp (%) is the spectral transmittance of each wavelength measured by overlapping two measurement samples in a manner that their absorption axes are parallel. The orthogonal transmittance Tc (%) is the spectral transmittance measured by overlapping and combining two measurement samples in a manner that their absorption axes are orthogonal. The measurement of each transmittance is performed at a wavelength of 220 to 780 nm.

[0205] (b) Calculation of polarization degree ρ

[0206] The degree of polarization ρ (%) of each measurement sample was calculated by substituting the parallel transmittance Tp and the orthogonal transmittance Tc into the following formula (I).

[0207] ρ={(Tp-Tc) / (Tp+Tc)} 1 / 2 ×100 (I)

[0208] (c) Calculation of visibility-corrected single-unit transmittance Ys

[0209] The visibility-corrected single transmittance Ys (%) of each measurement sample is the transmittance obtained by correcting the above-mentioned single transmittance Ts at a specific wavelength interval dλ (here, 5 nm) in the wavelength range of 400 to 700 nm in the visible light region according to JIS Z 8722: 2009. Specifically, the single transmittance Ts is substituted into the formula (II) to calculate the visibility-corrected single transmittance Ys. In the following formula (II), Pλ represents the spectral distribution of the standard light (C light source), and yλ represents the 2-degree field of view color matching function.

[0210]

[0211] (d) Measurement of polarized light

[0212] The light source used was an ultraviolet LED 375nm handheld black light ("PW-UV943H-04" manufactured by Nichia Chemical Industries, Ltd.), and an ultraviolet transmission and visible light cut filter ("IUV-340" manufactured by Isuzu Seiko Glass Co., Ltd.) was set on the light source to cut off the visible light. The measurement samples obtained in each embodiment and comparative example were set, and the polarized light emitted by the measurement samples was measured using a spectroradiometer ("USR-40" manufactured by USHIO Electric Co., Ltd.). At this time, a polarizing plate having a polarizing function in the visible light region and the ultraviolet light region ("SKN-18043P" manufactured by Polatechno, thickness 180μm, Ys 43%) was set on the light receiving part of the spectroradiometer, and the polarized light emission of the measurement samples obtained in each embodiment and comparative example was measured. That is, the light from the light source is arranged and measured in such a manner that it passes through the ultraviolet transmission and visible light cut-off filters, the measurement sample, and the polarizing plate with polarization in the visible light region and the ultraviolet light region in sequence, and is incident on the spectroradiometer. At this time, the absorption axis of the maximum ultraviolet absorption of the measurement sample is overlapped in a manner that is parallel to the absorption axis direction of the polarizing plate ("SKN-18043P" manufactured by Polatechno) with polarization in the visible light region and the ultraviolet light region, and the spectral luminescence amount of each wavelength measured in this way is Lw (weak luminescence axis). The absorption axis of the maximum ultraviolet absorption of the measurement sample is overlapped in a manner that is orthogonal to the absorption axis direction of the polarizing plate ("SKN-18043P" manufactured by Polatechno) with polarization in the visible light region and the ultraviolet light region, and the spectral luminescence amount of each wavelength measured in this way is Ls (strong luminescence axis), and Lw and Ls are measured. By confirming the light energy emitted in the visible light region when the sample is parallel to or perpendicular to the absorption axis of a general polarizing plate, the polarized light emission in the visible light region of 400 to 700 nm can be evaluated.

[0213] (e) Light resistance test

[0214] The light resistance test was conducted by irradiating light for 500 hours at an illuminance of 60 W, an ambient temperature of 50° C., and a relative humidity of 30% RH using SX-75 manufactured by Suga Testing Instruments Co., Ltd. The changes in Ls and Lw at each wavelength were checked.

[0215] Table 1 shows the wavelength showing the maximum polarization degree, the single transmittance Ts (%), the parallel position transmittance Tp (%), the orthogonal position transmittance Tc (%), and the polarization degree ρ (%), the visibility corrected single transmittance Ys (%), and the visibility corrected polarization degree ρy (%) of each measured sample obtained in Examples 1 to 5, s1 to s5, and Comparative Examples 1 to 3.

[0216] [Table 1]

[0217]

[0218] Table 2 below shows Ls and Lw at each wavelength for each measurement sample obtained in Examples 1 to 5 and s1 to s5 and Comparative Examples 1 to 3.

[0219] [Table 2]

[0220]

[0221] Table 3 below shows Ls and Lw at each wavelength of each measurement sample obtained in Examples 1 to 5 and s1 to s5 and Comparative Example 1 after the light resistance test.

[0222] [Table 3]

[0223]

[0224] As shown in Table 1, it can be seen that the test samples of Examples 1 to 5 and s1 to s5 and Comparative Example 1 have absorption in the ultraviolet region to the near ultraviolet visible region, and function as a polarized light emitting plate in this band. On the other hand, the transmittance in the visible region (visibility-corrected transmittance Ys) shows about 90%, which shows that it has a polarization function in the ultraviolet region to the near ultraviolet visible region, and the visible transparency is high. In contrast, in Comparative Examples 2 and 3, the wavelength showing the maximum polarization degree is above 400nm, the visibility-corrected transmittance Ys decreases, and a decrease in visible transmittance can be observed.

[0225] In addition, as shown in Table 2, Lw and Ls were detected in Examples 1 to 5, s1 to s5, and Comparative Example 1, so it can be seen that these samples emit polarized light by irradiating with ultraviolet rays. On the other hand, compared with Comparative Example 1, Examples 1 to 5 and s1 to s5 have a higher maximum luminous brightness or emit higher polarized light in a wide band of 400 to 700 nm.

[0226] In addition, as shown in Table 3, Examples 1 to 5 and s1 to s5 have higher light resistance than Comparative Example 1. Therefore, the measured samples of Examples 1 to 5 and s1 to s5 not only function as polarized light emitting elements capable of emitting polarized light in the visible light region by ultraviolet irradiation, but also have higher light resistance.

[0227] (f) Durability test

[0228] The polarized light-emitting plates obtained in Examples 1 to 5 and s1 to s5 were placed in an environment of 105°C for 1000 hours and in an environment of 60°C and 90% relative humidity for 1000 hours, and a durability test was performed. No decrease in polarization degree or change in polarized light emission was observed. In this regard, the polarized light-emitting elements and polarized light-emitting plates of Examples 1 to 5 and s1 to s5 have high durability even in harsh environments.

[0229] [Industrial Applicability]

[0230] When the luminescent compound of the present invention is contained in a substrate and used, a polarized light-emitting element and a polarized light-emitting plate having a high degree of polarization at the absorption wavelength and showing a polarized light-emitting effect can be obtained. In addition, such a polarized light-emitting element and a polarized light-emitting plate have excellent durability and high transmittance in the visible light region. Therefore, the display device having the polarized light-emitting element or the polarized light-emitting plate of the present invention has high transparency in the visible light region, and can display images with polarized light emission for a long time, so it can be applied to a wide range of uses such as televisions, computers, tablet terminals, and even transparent displays (perspective displays). In addition, the polarized light-emitting element and the polarized light-emitting plate containing the luminescent compound of the present invention can emit light from the ultraviolet region to the near-ultraviolet visible light region, such as light from 300 to 430nm, so it can be applied to displays or media requiring high safety.

Claims

1. A polarized light-emitting element, comprising at least one selected from the group consisting of a light-emitting compound represented by the following formula (1) or a salt thereof, a light-emitting compound represented by the following formula (31) or a salt thereof, and a light-emitting compound represented by the following formula (32) or a salt thereof, In formula (1), X and Y each independently include at least a substituent selected from the group consisting of the group represented by formula (2), a nitro group, an amino group, and the groups represented by formulas (3) to (7) below, excluding the case where both X and Y are nitro groups; M each independently represents a hydrogen atom, a metal ion, or an ammonium ion, m each independently represents an integer from 0 to 2, s is 0 or 1, In formula (2), * represents the bonding position of X and / or Y in formula (1), Z is selected from the group consisting of a phenyl group which may have a substituent selected from the group consisting of a nitro group, a sulfonic acid group, a C1 to 4 alkoxy group and a group represented by the following formulas (3) to (7), a naphthyl group which may have a substituent selected from the group consisting of a hydroxyl group and a sulfonic acid group, and a stilbene group which may have a substituent selected from the group consisting of an amino group, a nitro group, a sulfonic acid group and a group represented by the following formulas (3) to (7), t represents an integer of 0 or 1, In the above formulae (3) and (4), A is independently selected from the group consisting of a hydrogen atom and a C1 to C4 alkyl group, 1 represents an integer from 0 to 4, M in the above formulae (3) to (7) is as defined in the above formula (1), and n 1 and n 2 Each independently represents an integer of 0 to 3, and * in the above formulae (3) to (7) respectively represents the bonding position of X or Y in the above formula (1), or the bonding position of Z in the above formula (2).

2. The polarized light-emitting element according to claim 1, comprising a light-emitting compound or a salt thereof, wherein X and Y in the above formula (1) are each independently selected from the group consisting of substituents represented by formulas (2) to (7).

3. The polarized light-emitting element according to claim 1 or 2, comprising a light-emitting compound or a salt thereof, wherein X and Y in the above formula (1) are both selected from the group consisting of substituents represented by formulas (2) to (7). 4 . The polarized light-emitting element according to claim 1 , comprising a light-emitting compound or a salt thereof, wherein each m in the above formula (1) is 0. 5 . The polarized light-emitting element according to claim 1 , comprising a light-emitting compound or a salt thereof, wherein s is 0. The polarized light-emitting element according to claim 1 or 2, comprising a light-emitting compound or a salt thereof, wherein s is 1.

7. The polarized light emitting element according to claim 6, comprising a light emitting compound or a salt thereof, wherein the above formula (1) is represented by the following formula (1'): In the above formula (1'), X and Y are respectively as defined in the above formula (1).

8. The polarized light emitting element according to claim 1 or 2, further comprising one or more organic dyes or fluorescent dyes other than the above-mentioned light emitting compound or its salt.

9. The polarized light emitting element according to claim 1 or 2, further comprising a substrate. 10 . The polarized light emitting element according to claim 9 , wherein the substrate is a film containing a polyvinyl alcohol resin or a derivative thereof. 11 . A polarized light emitting plate, comprising: a polarized light emitting element according to claim 1 , wherein at least one surface thereof is provided with a transparent protective film. 12 . A display device comprising the polarized light emitting element according to claim 1 or the polarized light emitting plate according to claim 11 .

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