TWI846899B - Luminescent compound or salt thereof, and polarizing luminescent element, polarizing luminescent plate, and display using the same - Google Patents

Abstract

The present invention is a luminescent compound or salt thereof represented by the following formula (1).

(In formula (1), k is 0 or 1, at least one of X and Y represents a heterocyclic group containing a nitrogen atom or a sulfur atom which may have a substituent or a group of formula (2), the other X and Y are selected from 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 or an alkoxy group having 1 to 4 carbon atoms which may have a substituent, a heterocyclic group containing a nitrogen atom or a sulfur atom which may have a substituent, or a group of formula (2). M represents a hydrogen atom, a metal ion or an ammonium ion, m represents an integer of 0 to 2. In formula (2), ※indicates the bonding position of X and Y in formula (1), Z is selected from 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 or a heterocyclic group which may have a substituent. t represents an integer of 0 or 1.)

Description

Luminescent compound or its salt, and polarized light emitting element, polarized light emitting plate and display device obtained by using the compound

The present invention relates to a novel luminescent compound or its salt, and a polarized light emitting element, polarized light emitting plate and display using the compound.

Polarizing plates with penetrating/shielding functions and liquid crystals with light switching functions are both components of displays such as liquid crystal displays (LCDs). The application areas of LCDs equipped with such polarizing plates have also expanded from small machines such as computers and clocks in the early days to laptops, word processors, LCD projectors, LCD TVs, car navigation systems, and indoor and outdoor measuring machines. In addition, polarizing plates can also be applied to lenses with polarizing functions, such as sunglasses with higher visibility or polarized glasses that have been used in recent years for 3D TVs. As mentioned above, the use of polarizing plates has expanded to a wide range, and the conditions of use also span from low temperature to high temperature, low humidity to high humidity, and low light intensity to high light intensity, so polarizing plates with high polarization performance and high durability are required.

Generally, the polarizing film constituting the polarizing plate is made by dyeing the film of polyvinyl alcohol or its derivatives as the polarizing film substrate, or by stretching and aligning the film containing iodine or dichroic dyes, or by dehydrogenating polyvinyl chloride film or dehydrating polyvinyl alcohol film to generate polyene and aligning it. The polarizing plate composed of such a conventional polarizing film has a reduced transmittance because it uses a dichroic dye that absorbs in the visible light region. For example, the transmittance of a general polarizing plate on the market is 35 to 45%. Conventional polarizing plates have a problem of reduced transmittance in the visible light region. As a technology that maintains a certain degree of transmittance in the visible light region and has a polarizing function, a technology for polarizing plates for ultraviolet rays has been described in Patent Document 1. However, since this technology also uses a yellow pigment that absorbs in the visible light region, the transmittance is insufficient and a strong yellow coloring is confirmed. When a polarizing plate with low transmittance in the visible light range is used on a display, the transmittance of the entire display will decrease, so a method of obtaining polarized light without using a conventional polarizing plate is being studied. As such a method, components that emit polarized light are described in patent documents 2 to 4.

However, the polarized light emitting elements described in Patent Documents 2 to 4 use special metals, such as rare and expensive metals such as tantalum or methanogen, so they are expensive and difficult to manufacture and are not suitable for mass production. In addition, these polarized light emitting elements are difficult to use in displays because the polarized light they emit is weak; in addition, linearly polarized light cannot be obtained. Therefore, it is desired to develop a novel element and material used therefor that exhibits the effect of emitting polarized light, has high transmittance (transparency) in the visible light range, and can be applied to liquid crystal displays that require durability in harsh environments.

[Prior Art Literature]

[Patent Literature]

[Patent document 1] WO2005/015275

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

[Patent Document 3] Japanese Patent Publication No. 5849255

[Patent Document 4] Japanese Patent No. 5713360

[Patent Document 5] Japanese Patent Publication No. 2001-240762

[Patent Document 6] WO2016/186196

The purpose of the present invention is to provide a novel compound, and a polarized light emitting element, a polarized light emitting plate and a display device using the compound, which can be applied to liquid crystal displays that require high transmittance in the visible light range and high durability in harsh environments.

As a result of in-depth research to achieve this goal, the inventors of the present invention have found that polarized light emitting elements and polarized light emitting plates containing compounds or salts with specific structures have high dichroic ratios in the ultraviolet to near ultraviolet visible light range (e.g., light of 300 to 430nm), high transmittance in the visible light range, and excellent durability in harsh and harsh environments. In addition, it was found that compounds or salts with such specific structures can emit polarized light in the visible light range by irradiation with light in the ultraviolet to near ultraviolet visible light range (e.g., light of 300 to 430nm), thus completing the present invention.

That is, the present invention relates to the following types [1] to [11].

[1] A luminescent compound represented by the following formula (1) or a salt thereof.

(In formula (1), k is independently an integer of 0 or 1, at least one of X and Y is a heterocyclic group containing a nitrogen atom or a sulfur atom which may have a substituent, or a group represented by formula (2), and the other X and Y are independently selected from 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, a heterocyclic group containing a nitrogen atom or a sulfur atom which may have a substituent, or a group represented by formula (2) M represents a hydrogen atom, a metal ion or an ammonium ion, and m represents an integer from 0 to 2 independently. In formula (2), ※ represents the bonding position of X and Y in formula (1), and Z is a group consisting of a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a distyryl group which may have a substituent, a benzoyl group which may have a substituent, or a heterocyclic group which may have a substituent. t represents an integer of 0 or 1. )

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

(In the above formulae (3) and (4), each A is independently a group selected from the group consisting of a hydrogen atom, a halogen group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms with a sulfonic acid group, an alkyl group having 1 to 4 carbon atoms with a hydroxyl group, an alkyl group having 1 to 4 carbon atoms with a carboxyl group, an alkoxy group having 1 to 4 carbon atoms with a sulfonic acid group, an alkoxy group having 1 to 4 carbon atoms with a hydroxyl group, and an alkoxy group having 1 to 4 carbon atoms with a carboxyl group, and ^q1 represents an integer from 0 to 4. M in the above formulae (3) to (7) is as defined in the above formula (1), and M in the formulae (3) to (7) and M in the formula (1) may be the same, and n1, ⁿ² , and n3 may be the same. ² each independently represents an integer from 0 to 3. The * in the above formulas (3) to (7) respectively represents a bonding position in X or Y in the above formula (1), or a bonding position in Z in the above formula (2).

[3] A luminescent compound or a salt thereof as described in item [1] or [2], wherein k in the above formula (1) is 0 or 1, at least one of X and Y is any group selected from the group consisting of formulas (2) to (7), and when at least one of X and Y is formula (2), Z is any group selected from the group consisting of formulas (3) to (7).

[4] A luminescent compound or a salt thereof as described in item [1] or [2], wherein each k in the above formula (1) is 0, X and Y are each a group selected from the group consisting of formulas (2) to (7), and when X and Y are formula (2), Z is a group selected from the group consisting of formulas (3) to (7).

[5] A luminescent compound or a salt thereof as described in item [1] or [2], wherein each k in the above formula (1) is 1, X and Y are each a group selected from the group consisting of formulas (2) to (7), and when X and Y are formula (2), Z is any group selected from the group consisting of formulas (3) to (7).

[6] A polarized light emitting element having a polarized light emitting function and containing a light emitting compound or a salt thereof as described in any one of items [1] to [5].

[7] The polarized light emitting element as described in item [6] further contains one or more organic dyes or fluorescent dyes other than the above-mentioned light emitting compounds or their salts.

[8] The polarized light emitting element as described in item [6] or [7] further comprises a substrate.

[9] The polarized light emitting element as described in item [8], wherein the substrate is a film containing polyvinyl alcohol resin or its derivatives.

[10] A polarizing light emitting plate, wherein at least one side of the polarizing light emitting element described in any one of items [6] to [9] is provided with a transparent protective film.

[11] A display device having a polarized light emitting element as described in any one of items [6] to [9] or a polarized light emitting plate as described in item [10].

The luminescent compound or its salt having a specific structure of the present invention absorbs light in the ultraviolet to visible range (e.g., light in the ultraviolet to near ultraviolet visible range, specifically, light of 300 to 430 nm), and uses its energy to exhibit polarized luminescence in the visible range. In addition, the polarized luminescent element and polarized luminescent plate made using the luminescent compound or its salt exhibit high polarization in the absorbed wavelength. Therefore, by using the compound of formula (1) or its salt, even without using a highly rare and valuable titanium metal, it is possible to have a high polarization in the ultraviolet to near ultraviolet visible range, and at the same time provide a novel polarized luminescent element and polarized luminescent plate exhibiting polarized luminescence. In addition, the polarized light emitting element and polarized light emitting plate of the present invention show high transmittance in the visible light domain and excellent durability against heat, humidity, etc. Therefore, the polarized light emitting element and polarized light emitting plate can be applied to display devices such as liquid crystal displays that require high transmittance in the visible light domain and high durability in harsh environments.

[Luminescent compounds]

The luminescent compound of the present invention is represented by the above formula (1). The luminescent compound may be in the form of a salt. In this specification, the luminescent compound or its salt is sometimes referred to as a luminescent compound.

In formula (1), k is independently an integer of 0 or 1, at least one of X and Y is a heterocyclic group containing a nitrogen atom or a sulfur atom which may have a substituent, or a group represented by formula (2), and the other X and Y are independently a group selected from the group consisting of a nitro group, an amino group which may have a substituent, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms which may have a substituent, a heterocyclic group containing a nitrogen atom or a sulfur atom which may have a substituent, or a structure of formula (2). M is a hydrogen atom, a metal ion, or an ammonium ion, and m is independently an integer of 0 to 2. In formula (2), ※ represents the bonding position of X and Y in formula (1), and Z is a group selected from the group consisting of a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a distyryl group which may have a substituent, a benzoyl group which may have a substituent, or a heterocyclic group which may have a substituent. t represents an integer of 0 or 1.

The heterocyclic group containing nitrogen atoms or sulfur atoms which may have a substituent is, for example, a heterocyclic group having at least one of nitrogen atoms and sulfur atoms as a ring constituent, and the heterocyclic group also contains a polycyclic heterocyclic group further including an aromatic ring such as a benzene ring or a naphthyl ring. The heterocyclic group having at least one of the nitrogen atoms and sulfur atoms as a ring constituent includes, for example, pyrrolyl, benzopyrrolyl, thienyl, benzothienyl, thiazolyl, benzothiazolyl, naphthiothiazolyl, triazolyl, naphthiotriazolyl, naphthiotriazolyl, thiadiazolyl, benzothiadiazolyl, pyridine, etc.

The above-mentioned amino groups that may have substituents can be enumerated as follows: for example, amino groups; monosubstituted amino groups such as methylamino groups, ethylamino groups, n-butylamino groups, phenylamino groups, and naphthylamino groups; disubstituted amino groups such as dimethylamino groups, diethylamino groups, di-n-butylamino groups, diphenylamino groups, ethylmethylamino groups, and ethylphenylamino groups, etc.

The above-mentioned alkyl groups with 1 to 4 carbon atoms which may have substituents include, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, cyclobutyl, etc.

The alkoxy groups with 1 to 4 carbon atoms that may have substituents include, for example, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, cyclobutoxy, etc.

The substituents in the above-mentioned heterocyclic group containing nitrogen atoms or sulfur atoms which may have a substituent, the amino group which may have a substituent, the alkyl group having 1 to 4 carbon atoms which may have a substituent, and the alkoxy group having 1 to 4 carbon atoms which may have a substituent are not particularly limited, but examples thereof include: hydroxyl group, cyano group, phosphoric acid group, sulfonic acid group, carboxyl group, amino group, etc.

In the above formula (1), M 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 ion, methylammonium ion, dimethylammonium ion, triethylammonium ion, tetraethylammonium ion, tetra-n-propylammonium ion, tetra-n-butylammonium ion, monoethoxide ammonium ion, diethoxide ammonium ion, triethoxide ammonium ion, monoisopropoxide ammonium ion, diisopropoxide ammonium ion, triisopropoxide ammonium ion, triethoxide ammonium ion, etc. More specifically, for example, when M is a hydrogen atom, sulfonic acid (-SO ₃ H) is represented, when M is a sodium ion, sodium sulfonate (-SO ₃ Na) is represented, and when M is an ammonium ion, ammonium sulfonate (-SO ₃ NH ₄ ) is represented. Among these, particularly preferred ones include lithium ions, ammonium ions and sodium ions.

In the above formula (2), ※ represents the bonding position of X and Y in formula (1), and Z is a group selected from the group consisting of a phenyl group that may have a substituent, a naphthyl group that may have a substituent, a distyryl group that may have a substituent, a benzoyl group that may have a substituent, or a heterocyclic group that may have a substituent. t represents an integer of 0 or 1. The substituent that Z may have here is not particularly limited, and can be listed as follows: for example, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an amino group, a nitro group, a sulfonic acid group, a hydroxyl group, a cyano group, a phosphoric acid group, a carboxyl group, etc.

The above-mentioned heterocyclic group which may have a substituent may be the same as the heterocyclic group containing a nitrogen atom or a sulfur atom which may have a substituent in the above formula (1), and may also be a furanyl group, a benzofuranyl group, etc. containing an oxygen atom as a ring component.

When X and Y in the above formula (1) are represented by the above formula (2), and when at least one of X and Y in the above formula (1) is represented by the above formula (2), at least one Z is preferably a radical selected from the group consisting of the above formulas (3) to (7).

In the above formulae (3) and (4), each A is independently a group selected from the group consisting of a hydrogen atom, a halogen group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms with a sulfonic acid group, an alkyl group having 1 to 4 carbon atoms with a hydroxyl group, an alkyl group having 1 to 4 carbon atoms with a carboxyl group, an alkoxy group having 1 to 4 carbon atoms with a sulfonic acid group, an alkoxy group having 1 to 4 carbon atoms with a hydroxyl group, and an alkoxy group having 1 to 4 carbon atoms with a carboxyl group; ^q1 represents an integer from 0 to 4; M in the above formulae (3) to (7) is as defined in the above formula (1); M in the formulae (3) to (7) and M in the formula (1) may be the same; and ⁿ¹ and ⁿ² each independently represent an integer from 0 to 3. In the above formulae (3) to (7), * represents a bonding position in X or Y in the above formula (1), or a bonding position in Z in the above formula (2).

The above-mentioned alkyl groups with 1 to 4 carbon atoms include, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, cyclobutyl, etc.

The above-mentioned alkyl groups with 1 to 4 carbon atoms and having a sulfonic acid group can be enumerated as follows: for example, sulfonic acid methyl, sulfonic acid ethyl, sulfonic acid n-propyl, sulfonic acid n-butyl, sulfonic acid sec-butyl, etc.

The above-mentioned halogen groups can be listed as: for example, fluorine, chlorine, bromine, iodine, etc.

The above-mentioned alkoxy groups with 1 to 4 carbon atoms include, for example, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, cyclobutoxy, etc.

The above-mentioned alkyl groups with 1 to 4 carbon atoms and having a hydroxyl group can be exemplified as follows: for example, hydroxymethyl, hydroxyethyl, hydroxyn-propyl, hydroxyisopropyl, hydroxyn-butyl, hydroxysec-butyl, hydroxytert-butyl, hydroxycyclobutyl, etc.

The above-mentioned alkyl groups with 1 to 4 carbon atoms and having a carboxyl group can be enumerated as follows: for example, carboxymethyl, carboxyethyl, carboxy-n-propyl, carboxy-i-propyl, carboxy-n-butyl, carboxy-sec-butyl, carboxy-tert-butyl, carboxy-cyclobutyl, etc.

The above-mentioned alkoxy groups with 1 to 4 carbon atoms and having a sulfonic acid group can be exemplified as: sulfonic acid methoxy group, sulfonic acid ethoxy group, sulfonic acid n-propoxy group, sulfonic acid isopropoxy group, sulfonic acid n-butoxy group, sulfonic acid sec-butoxy group, sulfonic acid tert-butoxy group, sulfonic acid cyclobutoxy group, etc.

The above-mentioned alkoxy groups with 1 to 4 carbon atoms and having a hydroxyl group can be exemplified as follows: for example, hydroxymethoxy, hydroxyethoxy, hydroxyn-propoxy, hydroxyisopropoxy, hydroxyn-butoxy, hydroxysec-butoxy, hydroxytert-butoxy, hydroxycyclobutoxy, etc.

The above-mentioned alkoxy groups with 1 to 4 carbon atoms and having a carboxyl group can be exemplified as: carboxymethoxy, carboxyethoxy, carboxy-n-propoxy, carboxy-i-propoxy, carboxy-n-butoxy, carboxy-sec-butoxy, carboxy-tert-butoxy, carboxy-cyclobutoxy, etc.

In one embodiment, k in the above formula (1) is 0 or 1, at least one of X and Y is selected from any group consisting of formulas (2) to (7), and when at least one of X and Y is formula (2), Z can be selected from any group consisting of formulas (3) to (7). In the above formula (1), each k is 0, X and Y are selected from any group consisting of formulas (2) to (7), and when X and Y are formula (2), Z is preferably selected from any group consisting of formulas (3) to (7). In the above formula (1), each k is 1, X and Y are selected from any group consisting of formulas (2) to (7), and when X and Y are formula (2), Z is particularly preferably selected from any group consisting of formulas (3) to (7).

The following is a preferred example of a method for synthesizing the compound represented by formula (1). The method for synthesizing the present compound is not limited to the following example. For example, the compound represented by formula (1) can be obtained by the method disclosed in the above-mentioned patent document 5 and patent document 6.

For example, one equivalent of the compound represented by the following formula (10) and one equivalent of the compound represented by (11) are heated in water and dissolved by adding caustic soda. Phenyl chloroformate represented by the commercially available formula (9) is added to the solution to cause ureidation. The conditions of the ureidation reaction are not particularly limited, but for example, the reaction is carried out at a temperature of 30°C to 100°C (preferably 40°C to 90°C) for about 30 minutes to 15 hours (preferably about 1 hour to 10 hours). After the reaction is completed, it is cooled to room temperature, or salt is added to precipitate and filtered to obtain the target product.

(In the above formulas (9) to (11), each X, Y, k, M, and m may be the same as in the above formula (1).)

Next, specific examples of the luminescent compound represented by the above formula (1) are listed below. In addition, the sulfonic acid group and the like in the formula are represented in the form of free acid.

The compound represented by the above formula (1) or its salt can be used as a compound capable of polarized light emission. A polarized light emitting element can be manufactured by combining the luminescent compound represented by the formula (1) or its salt with one or more organic dyes or fluorescent dyes known in the industry (without particular limitation) other than the above luminescent compound or its salt as needed, and then incorporating and aligning the organic dyes in a substrate such as a polymer film of polyvinyl alcohol or its derivatives by a known method. The obtained polarized light emitting element is formed into a polarized light emitting plate by adding a transparent protective film, and a hard coating layer or AR (anti-reflection) layer and a support body are further provided on the polarized light emitting plate as needed. It can be applied to liquid crystal projectors, computers, clocks, notebook computers, word processors, liquid crystal televisions, car navigation systems, security displays, anti-counterfeiting and indoor and outdoor measuring instruments and displays, lenses or glasses. In addition, in this specification, organic dyes or fluorescent dyes known in the industry other than luminescent compounds or their salts are simply referred to as other organic dyes.

[Polarized light emitting element]

The polarized light-emitting element containing the light-emitting compound represented by the above formula (1) or its salt is also included in the present invention.

The polarized light emitting element is preferably a polarized light emitting element containing a light emitting compound or a salt thereof represented by the above formula (1) and a substrate on which the light emitting compound or a salt thereof has been adsorbed and aligned. The polarized light emitting element may contain one or more light emitting compounds or salts thereof represented by the above formula (1).

The substrate is preferably a film made of a hydrophilic polymer that can adsorb the luminescent compound or its salt. The hydrophilic polymer is not particularly limited, but examples thereof include polyvinyl alcohol resins, linear amylose resins, starch resins, cellulose resins, and polyacrylate resins. From the viewpoints of the adsorption, processability, and orientation of the luminescent compound or the salt, polyvinyl alcohol resins or their derivatives are preferred. Polyvinyl alcohol resins or their derivatives may also be modified with olefins such as ethylene and propylene, or unsaturated carboxylic acids such as crotonic acid, acrylic acid, methacrylic acid, and succinic acid. The shape of the substrate is not particularly limited, and can be made into any shape such as a film, sheet, flat plate, curved plate, hemispherical, etc. In addition, the thickness of the substrate (before swelling treatment) is usually 10μm to 100μm, preferably 20μm to 80μm.

The content of the luminescent compound or its salt represented by the above formula (1) in the above polarized light emitting element is not particularly limited and can be designed with any transmittance. The content can be arbitrarily set in accordance with the transmittance required by the polarized light emitting element. The polarization performance of the polarized light emitting element depends not only on the content of the luminescent compound or its salt represented by the formula (1) in the polarized light emitting element, but also on various factors such as the swelling property of the substrate adsorbing the luminescent compound, the elongation ratio, the dyeing time, the dyeing temperature, the pH during dyeing, and the influence of the salt. Therefore, the content of the luminescent compound or its salt represented by the formula (1) in the polarized light emitting element can be determined in accordance with the swelling property of the substrate, the temperature, time, pH, type of salt, concentration of salt, and elongation ratio during dyeing. Such content adjustment can be carried out as appropriate.

The polarized light emitting element may further contain one or more other organic dyes as needed within the range that does not hinder the polarization performance or for the purpose of color adjustment. The other organic dyes that can be used in combination are not particularly limited, but dyes with high dichroism are preferred, and dyes that do not affect the polarization performance of the light emitting compound of formula (1) in the ultraviolet light range to the near ultraviolet visible light range are preferred. Other organic dyes that can be used together include, for example, C.I.Direct.Yellow 12, C.I.Direct.Yellow 28, C.I.Direct.Yellow 44, C.I.Direct.Orange 26, C.I.Direct.Orange 39, C.I.Direct.Orange 71, C.I.Direct.Orange 107, C.I.Direct.Red 2, C.I.Direct.Red 31, C.I.Direct.Red 79, C.I.Direct.Red 81, C.I.Direct.Red 247, C.I.Direct.Blue 69, C.I.Direct.Blue 78, C.I.Direct.Green 80 and C.I.Direct.Green 59. These other organic dyes may be in the form of free acids, alkaline metal salts (such as Na salts, K salts and Li salts), ammonium salts or amine salts.

When the above-mentioned other organic dyes are used in combination as needed, the types of other organic dyes to be used can be selected for the purpose of adjusting the color of the polarized light-emitting element for manufacturing. In addition, although there is no particular restriction on the content of other organic dyes, it is usually (when used) preferably in the range of 1 to 1,000 parts by mass of the other organic dyes used in combination with 100 parts by mass of the luminescent compound of formula (1) or its salt.

<Method for manufacturing polarized light emitting element>

Next, the manufacturing method of the polarized light emitting element of the present invention is described. The manufacturing method is not limited, and includes the following steps: for example, a step of preparing a substrate, a swelling step of soaking the substrate in a swelling liquid so that the substrate is stretched due to 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 luminescent compound represented by the formula (1) as a luminescent compound or a salt thereof to be adsorbed on the substrate, and a dyeing step of adsorbing the luminescent compound represented by the formula (1) adsorbed on the substrate. The substrate of the luminescent compound or its salt is immersed in a solution containing boric acid, and the luminescent compound or its salt represented by formula (1) is crosslinked in the substrate, a crosslinking step is performed, the substrate crosslinked with the luminescent compound or its salt is axially extended in a certain direction, and the luminescent compound or its salt represented by formula (1) is arranged in a certain direction, a washing step is performed, and the washed substrate is washed with a washing solution, and a drying step is performed to dry the washed substrate.

(Preparation of substrate)

Prepare a substrate for adsorbing/aligning the luminescent compound represented by the above formula (1). The substrate can be, for example, a film composed of a commercially available polyvinyl alcohol resin or its derivatives, or can be made by film-forming a polyvinyl alcohol resin. The film-forming method of the polyvinyl alcohol resin is not particularly limited, and can be a known film-forming method such as a method of melt extruding aqueous polyvinyl alcohol, a cast film method, a wet film method, a gel film method (after a polyvinyl alcohol aqueous solution is briefly cooled to gel, the solvent is extracted and removed), a casting film method (the polyvinyl alcohol aqueous solution is cast on a substrate and dried), and a combination of these methods. The degree of polymerization of polyethylene can be 1,000 to 10,000, but preferably 1,500 to 6,000, and more preferably 2,000 to 6,000.

(Swelling step)

Secondly, the above-mentioned substrate is subjected to 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. The swelling liquid is preferably water. The elongation ratio of the substrate by the swelling liquid is preferably adjusted to 1.00 to 1.50 times, and more preferably adjusted to 1.10 to 1.35 times.

(Dyeing step)

Next, at least one luminescent compound of formula (1) or its salt is adsorbed and impregnated on the substrate subjected to the swelling treatment as described above. The dyeing step is not particularly limited as long as the luminescent compound or its salt is adsorbed and impregnated on the substrate. It is preferably to immerse the substrate in a dyeing solution (generally an aqueous solution) containing the luminescent compound or its salt. Alternatively, the luminescent compound or its salt may be adsorbed by applying the dyeing solution on the substrate. The concentration of the luminescent compound or its salt in the dyeing solution is not particularly limited as long as the luminescent compound or its salt is sufficiently adsorbed on the substrate. For example, 0.001 to 3% by mass is preferred, and 0.001 to 1.0% by mass is more preferred.

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 adjusted appropriately, preferably between 30 seconds and 20 minutes, and more preferably between 1 to 10 minutes.

As the luminescent compound or its salt represented by the above formula (1) as the compound contained in the above dyeing solution, one kind alone or two or more kinds may be used in combination. Since the luminescent compound or its salt represented by the above formula (1) has different luminescent colors due to different structures, the luminescent color produced can be appropriately adjusted to the required color by containing two or more luminescent compounds or their salts in the substrate. In addition, the dyeing solution may further contain one or two or more other organic dyes as needed. In the manufacture of the polarized light emitting element and the polarized light emitting plate described in this specification, the luminescent compound represented by formula (1) (or its salt) and other organic dyes are sometimes collectively referred to as "polarizing pigments".

In addition to the polarizing pigments mentioned above, the dyeing solution may also contain dyeing auxiliaries as needed. Dyeing auxiliaries include, for example, sodium carbonate, sodium bicarbonate, sodium chloride, sodium sulfate (glauber's salt), anhydrous sodium sulfate and sodium tripolyphosphate, etc., preferably sulfuric acid. The content of the dyeing auxiliaries can be adjusted arbitrarily according to the dyeing properties of the polarizing pigment used, by the above-mentioned immersion time and the temperature of the dyeing solution. The content of the dyeing auxiliaries is preferably 0.05 to 10% by mass in the dyeing solution (when used), and more preferably 0.05 to 2% by mass.

After the dyeing step, a preliminary cleaning step may be arbitrarily performed to remove the residual dyeing solution attached to the surface of the substrate in the dyeing step. By performing the preliminary cleaning step, the luminescent compound or its salt remaining on the surface of the substrate can be inhibited from transferring to the post-treatment liquid. Usually, water is used as the cleaning liquid in the preliminary cleaning step. The cleaning method is preferably to immerse the dyed substrate in the cleaning liquid. On the other hand, the cleaning liquid may be applied to the substrate for cleaning. Although there is no particular limitation on the cleaning time, 1 to 300 seconds is preferred, and 1 to 60 seconds is more preferred. The temperature of the cleaning liquid in the preliminary cleaning step must be a temperature that will not dissolve the material constituting the substrate, and can usually be 5 to 40°C. Furthermore, since there is no preliminary cleaning step, the performance of the polarized light emitting element will not be significantly affected, the preliminary cleaning step can be omitted.

(Cross-linking step)

After the dyeing step or the pre-cleaning step, the substrate may contain a crosslinking agent. The method of making the substrate contain a crosslinking agent is preferably to immerse the substrate in a treatment solution containing the crosslinking agent. On the other hand, the treatment solution may be applied or coated on the substrate. The crosslinking agent in the treatment solution is preferably a solution containing boric acid. Although there is no particular limitation on the solvent in the treatment solution, water is preferred. The boric acid concentration in the treatment solution is preferably 0.1 to 15 mass %, and more preferably 0.1 to 10 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 this crosslinking step is preferably 30 seconds to 10 minutes, and more preferably 1 to 6 minutes. The manufacturing method of the polarized light emitting element of the present invention has this crosslinking step, so that the obtained polarized light emitting element emits polarized light with high brightness and high polarization degree. This is an excellent effect that the function of boric acid used in the prior art for the purpose of improving water resistance or light transmittance is completely unexpected. In addition, the crosslinking step can be further combined with a repairing step by an aqueous solution containing a cationic polymer compound as needed. The repairing step can fix the polarized pigment. At this time, the cationic polymer compound that can be used includes, for example, dicyanamide and formalin polycondensates as dicyandiamide, dicyandiamide/diethylenetriamine polycondensates as polyamines, epichlorohydrin/dimethylamine-added polymers as polycations, dimethyldiallylammonium chloride/dioxide ion copolymers, diallylamine salt polymers, dimethyldiallylammonium chloride polymers, allylamine salt polymers, and dialkylaminoethyl acrylate quaternary salt polymers.

(Extended steps)

After or at the same time as the crosslinking step, the stretching step is performed. The stretching step is performed by axially stretching the substrate in a certain direction. The stretching method can be either a wet stretching method or a dry stretching method. The stretching ratio is preferably 3 times or more, and 5 to 9 times is more preferred.

In the dry stretching method, if the stretching heating medium is an air medium, it is best to stretch the substrate at a temperature of the air medium between room temperature and 180°C. In addition, the humidity is preferably in an environment of 20 to 95% RH. Although the substrate heating method can be listed, such as roller belt stretching method, roller heating stretching method, hot pressure stretching method and infrared heating stretching method, it is not limited to these stretching methods. The dry stretching step can implement a single stage stretching, or a multi-stage stretching of more than two stages.

In the wet stretching method, it is preferred to stretch the substrate in water, a water-soluble organic solvent or a mixed solution thereof. It is preferred to perform the stretching treatment while immersing the substrate in a solution containing at least one crosslinking agent (i.e., the crosslinking step and the stretching step may also be performed simultaneously). The crosslinking agent may be, for example, boric acid in the crosslinking agent step described above, and it is preferred to perform the stretching treatment in the treatment solution used in the crosslinking step. The stretching temperature is preferably 40 to 70°C, more preferably 45 to 60°C. The stretching time is usually 30 seconds to 20 minutes, preferably 2 to 7 minutes. The wet stretching step may be performed in a single-stage stretching, or in a multi-stage stretching of two or more stages. Furthermore, the extension treatment can be performed arbitrarily before the dyeing step, and the alignment of the luminescent compound of formula (1) or its salt can also be performed at the same time as the dyeing step.

(Washing step)

After the extension step, a cleaning step can be performed to clean the surface of the substrate because there will be precipitation of the crosslinking agent or foreign matter attached to the substrate surface. The cleaning time is preferably 1 second to 5 minutes. The cleaning method is preferably to immerse the substrate in a cleaning solution. On the other hand, the cleaning solution can also be applied or coated on the substrate. The cleaning solution is preferably water. The cleaning treatment can be performed in one stage or in multiple stages of two or more stages. Although there is no special restriction on the temperature of the cleaning solution in the cleaning step, it is usually 5 to 50°C, preferably 10 to 40°C, and can also be room temperature.

In addition to water, the solvents of the solutions or treatment liquids used in the above steps can also include: for example, dimethyl sulfoxide, N-methyl pyrrolidone, methanol, ethanol, propanol, isopropanol, glycerol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol or trihydroxymethyl propane and other alcohols, amines such as ethylenediamine and diethylenetriamine, etc. Although the solvent of the solution or treatment liquid is not limited to these, water is the best. In addition, one of the solvents of the solution or treatment liquid can be used alone, or a mixture of two or more can be used.

(Drying step)

After the cleaning step, the substrate is dried. The drying process can be carried out by natural drying, but in order to further improve the drying efficiency, it can also be carried out by compression using a roller or by removing surface moisture using an air knife or a water-absorbing roller. In addition, air drying can also be carried out. The temperature of the drying process is preferably 20 to 100°C, and more preferably 60 to 100°C. The drying time is preferably 30 seconds to 20 minutes, and more preferably 5 to 10 minutes.

The above-mentioned examples can be used to prepare the polarized light-emitting element of the present invention. In addition, the luminescent compound represented by formula (1) or its salt in the present invention can be mixed with liquid crystal and aligned on a substrate, or the coating method of the liquid crystal distributed on the substrate can be used to align the luminescent compound, thereby manufacturing a polarized light-emitting element with various colors or neutral gray.

[Polarized light emitting plate]

The polarizing light-emitting plate containing the above-mentioned polarizing light-emitting element is also included in the present invention.

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 handling properties of the polarized light emitting element. Therefore, it is preferred that the transparent protective film does not have any effect on the polarization effect displayed by the polarized light emitting element of the present invention.

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, the transparent protective film is preferably a plastic film with excellent thermal stability and moisture shielding properties. The materials forming such a transparent protective film can be listed as: for example, 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. It is better to use triacetyl cellulose (TAC) film or cycloolefin film. The thickness of the transparent protective film is preferably in the range of 1μm to 200μm, more preferably in the range of 10μm to 150μm, and particularly preferably in the range of 40μm to 100μm. Although there is no particular limitation on the method of manufacturing the polarizing light-emitting plate of the present invention, for example, the transparent protective film can be superimposed on the polarizing light-emitting element and laminated according to a known formula to manufacture the polarizing light-emitting plate.

The polarizing plate may also have an adhesive layer between the transparent protective film and the polarizing element for bonding the transparent protective film to the polarizing element. The adhesive constituting the adhesive layer is not particularly limited, and polyvinyl alcohol adhesives, urethane emulsion adhesives, acrylic adhesives, polyester-isocyanate adhesives, etc. may be used. Polyvinyl alcohol adhesives are preferably used. After bonding the transparent protective film and the polarizing element with the adhesive, the polarizing plate may be manufactured by drying or heat treating at an appropriate temperature.

In addition, the polarizing plate may have various known functional layers such as an anti-reflection layer, an anti-glare layer, and other protective films on the exposed surface of the transparent protective film. When making such layers with various functions, it is preferred to apply the materials with various functions on the exposed surface of the transparent protective film. On the other hand, the layer or film with such functions may be attached to the exposed surface of the transparent protective film through an adhesive.

The above-mentioned other transparent protective films include: for example, acrylic, urethane, polysiloxane and other hard coatings. In addition, in order to further improve the monomer transmittance, an anti-reflection layer can also be set on the exposed surface of the transparent protective film. The anti-reflection layer can be formed by, for example, evaporating or sputtering silicon dioxide, titanium oxide and other substances on the transparent protective film, or applying a thin layer of fluorine-based substances on the transparent protective film.

The above-mentioned polarized light emitting plate can be further provided with a transparent support body such as glass, crystal, sapphire, etc. as needed. There is no particular limitation on such a support body, but it is preferred to have a flat portion for attaching the polarized light emitting plate. In addition, from the perspective of optical use, the support body is preferably a transparent support body. The transparent support body can be divided into an inorganic support body and an organic support body. For example, the support body composed of inorganic materials can be listed as a support body composed of sodium glass, borosilicate glass, crystal, sapphire, spinel and the like. The organic support body can be listed as a support body composed of acrylic, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, cycloolefin polymer and the like. The thickness and size of the transparent support are not particularly limited and can 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 preferred to set an anti-reflection layer on one or both sides of the support surface or the polarized light emitting plate surface. In order to make the polarized light emitting plate and the support body bond, it is only necessary to apply a transparent bonding (adhesive) agent on the support body and then attach the polarized light emitting plate of the present invention to the coated surface. There is no particular limitation on the bonding agent or adhesive used, and commercially available ones can be used, and acrylic bonding agents or adhesives are preferred.

In addition, the above-mentioned polarized light emitting plate can also be used as a circularly polarized light emitting plate or an elliptical 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 also be a phase difference plate. Although the phase difference plate can generally be exemplified as one having a phase difference value of 1/4λ or a phase difference value of 1/2λ for the absorption wavelength or emission wavelength of light, it is not limited to these. By having a phase difference value of 1/4λ, the function of a circularly polarized light plate or a circularly polarized light emitting plate can be exerted at the wavelength, and by using 1/2λ, the purpose of converting the polarized light in the direction of 90° can be achieved. In this way, various functional layers, support bodies, etc. can be further provided on the polarized light emitting plate. This type of polarized light emitting plate can be used in a variety of products such as LCD projectors, computers, clocks, laptops, word processors, LCD TVs, car navigation systems, indoor and outdoor measuring instruments or displays, lenses or glasses, etc.

The polarized light emitting element and polarized light emitting plate of the present invention show high polarization degree in the ultraviolet to near-ultraviolet visible light range (e.g., 300 to 430nm), and at the same time show polarized light emitting effect and high transmittance in the visible light range. In addition, since the polarized light emitting element and polarized light emitting plate of the present invention show excellent durability to heat, humidity, light, etc., their performance can be maintained even in harsh environments, and they have higher durability than traditional iodine-based polarizing plates. Therefore, the polarized light emitting element and polarized light emitting plate of the present invention can be applied to liquid crystal displays that require high transparency in the visible light range and high durability in harsh environments, such as televisions, wearable devices, tablet computers, smart phones, vehicle-mounted surveillance, outdoor or indoor digital signs, smart windows and other displays.

[Display device]

A display containing the above-mentioned polarized light emitting element or polarized light emitting plate is also included in the present invention.

The above display shows polarized light luminescence by irradiating light from the ultraviolet range to the visible range (for example, light from the ultraviolet range to the near-ultraviolet visible range, specifically, light of 300 to 430 nm), and uses this effect to achieve display. The display of the present invention has a high transmittance in the visible light range, so it does not have a reduced transmittance in the visible light range like a traditional polarizing plate, and even if the transmittance is reduced, the reduction in transmittance is significantly less than that of a traditional polarizer. For example, when the polarization degree of a traditional polarizing plate, an iodine polarizing plate or a dye-based polarizing plate using other dye compounds, is set to be almost 100%, the luminescence factor in the visible light range is corrected to about 35 to 43%. The reason is that although the conventional polarizing plate has both the longitudinal and transverse axes as light absorption axes, in order to obtain almost 100% polarization, the incident light of one of the longitudinal or transverse axes is absorbed, that is, the polarization is generated by absorbing light in one of the axes and transmitting light in the other axis. In this case, since the light of one axis is absorbed and not transmitted, the transmittance is necessarily less than 50%. In addition, the conventional polarizing plate is made by aligning the dichroic pigment in the stretched film. However, dichroic pigments are not necessarily 100% aligned. In addition, since they also have a slight absorption component relative to the transmission axis of light, if the transmittance caused by the surface reflection of the material is not less than about 43%, it is impossible to achieve almost 100% polarization. In other words, if the transmittance is not reduced, it is impossible to achieve a high polarization. On the contrary, the polarized light emitting element and polarized light emitting plate of the present invention have an axis (its polarization function) that absorbs light in the ultraviolet range to the near ultraviolet visible light range (for example, 300 to 430nm), that is, they have a light absorption effect in the ultraviolet range to the near ultraviolet visible light range (for example, 300 to 430nm), showing a polarized light emitting effect of emitting polarized light in the visible light range, and on the other hand, they hardly absorb light in the visible light range, so that the transmittance in the visible light range becomes very high. In addition, since polarized light is used for display in the visible light range, there is no light loss compared to the use of conventional polarizers, that is, the reduction in transmittance like conventional polarizers is very small. Therefore, a display using the polarized light emitting element and polarized light emitting plate of the present invention, such as a liquid crystal display, can obtain a higher brightness than a liquid crystal display using conventional polarizers. In addition, since the display using the polarized light emitting element and polarized light emitting plate of the present invention has high transparency, in the case of a liquid crystal display, an almost transparent display can also be obtained. In addition, when displaying text and images, since it can be designed to allow polarized light to pass through, a display that can display even a transparent liquid crystal display can be obtained, that is, a display that can display text, etc. on a transparent display. Moreover, the display of the present invention can obtain a transparent liquid crystal display without light loss, and in particular, can obtain a see-through display.

In addition, since the above-mentioned display can also generate polarized light for light in the ultraviolet to near ultraviolet visible light range (e.g., 300 to 430nm) that is invisible or difficult to see to the naked eye, it can be applied to liquid crystal displays that can display light in the ultraviolet to near ultraviolet visible light range. For example, by using a computer to identify images displayed in the ultraviolet to near ultraviolet visible light range, a simple and highly secure liquid crystal display that can only be identified when irradiated with light in the ultraviolet to near ultraviolet visible light range (e.g., 300 to 430nm) can be produced.

In addition, the above-mentioned display shows polarized light luminescence by irradiating light in the ultraviolet to near-ultraviolet visible light range (e.g., 300 to 430nm). Since a liquid crystal display using this polarized light luminescence can be made, a liquid crystal display using light in the ultraviolet to near-ultraviolet range can be realized, rather than a general liquid crystal display using visible light. That is, even in a dark space without light, as long as a space that can irradiate light in the ultraviolet to near-ultraviolet range can be used, a luminescent liquid crystal display that can display text, images, etc. can be made.

In addition, since the visible light domain and the ultraviolet light are different light domains, it is also possible to produce a display that combines two different displays, a liquid crystal display unit that displays the visible light domain with light in the visible light domain and a liquid crystal display unit that displays light with the polarized light emission effect of ultraviolet light. Although there are displays that can achieve two different displays, there is no display that can achieve different displays in the ultraviolet light domain and the visible light domain by using different light sources under the same liquid crystal panel. Therefore, the display of the present invention can produce a novel display because it has the above-mentioned polarized light emitting element and polarized light emitting plate.

The present invention also includes a liquid crystal display using the above-mentioned polarized light emitting element, polarized light emitting plate or display. The liquid crystal unit used in the liquid crystal display is not limited to, for example, TN liquid crystal unit, STN liquid crystal unit, VA liquid crystal unit, IPS liquid crystal unit, etc. The above-mentioned polarized light emitting element and polarized light emitting plate can use any liquid crystal display mode. Since the liquid crystal display has high durability, a liquid crystal display for vehicle use or outdoor display can be provided.

The neutral gray polarized light emitting plate for vehicle or outdoor display using the above polarized light emitting element or the display containing the same is also included in the present invention. The neutral gray polarized light emitting plate for vehicle or outdoor display has excellent polarized light emitting performance, and does not cause discoloration or reduction of polarized light performance even in high temperature and high humidity conditions inside the car or outdoors. In addition, neutral gray refers to the transmittance of each wavelength in the vertical position of the visible light domain of the polarized light emitting plate, which is significantly low or has a certain transmittance. Specifically, the vertical transmittance is less than 0.3%, preferably less than 0.1%, more preferably less than 0.03%, and particularly preferably less than 0.01%; a certain transmittance refers to the average transmittance for each wavelength, and the difference in transmittance is within 1%.

(Implementation example)

Although the present invention is described in more detail below through examples, these are illustrative only and the present invention is not limited thereto. In addition, unless otherwise specified, the "%" and "parts" described below are based on mass. In addition, in each structural formula of the compound used in each example and comparative example, the acidic functional group such as sulfonic acid group is recorded in the form of free acid.

[Implementation Example 1]

(Synthesis Example 1)

84 parts of the compound of formula (28) were added to 800 parts of water, dissolved with sodium hydroxide, and 15.6 parts of phenyl chloroformate were added, and stirred at 50 to 70°C for 6 hours to ureidize. Salt precipitation was performed with sodium chloride, and the mixture was filtered and dried at 70°C to obtain 56.6 parts of the ureido compound represented by formula (24) of the compound example of the present invention.

(Production of polarized light emitting elements and polarized light emitting plates)

A polyvinyl alcohol film (VF-PS #7500 manufactured by Kuraray Co., Ltd.) having 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 of the present invention of the above formula (24) obtained in Synthesis Example 1, 1.0 parts by mass of sodium sulfate and 1,000 parts by mass of water for 4 minutes to allow the film to contain the compound of formula (24). The film containing the compound of formula (24) was stretched to 5 times in a 3% boric acid aqueous solution at 50°C for 5 minutes. The stretched film was washed with water at room temperature for 20 seconds while being maintained in a stretched state, and dried at 70°C for 9 minutes to obtain a polarized light emitting element. On both sides of the obtained polarized light emitting element, a triacetyl cellulose film (ZRD-60 manufactured by Fuji Film Co., Ltd.) without ultraviolet absorber was laminated with a known formula to obtain a polarized light emitting plate. Moreover, even if the triacetyl cellulose film was laminated on both sides of the polarized light emitting element, the optical properties of the polarized light emitting element were not affected.

[Example 2]

(Synthesis Example 2)

136 parts of the compound of formula (29) were added to 1,000 parts of water, dissolved with sodium hydroxide, and 15.6 parts of phenyl chloroformate were added, and stirred at 50 to 70°C for 6 hours to ureidize. Salt precipitation was performed with sodium chloride, and after filtering, it was dried at 70°C to obtain 92.3 parts of the ureido compound represented by formula (12) of the compound example of the present invention. The polarized light-emitting element and polarized light-emitting plate of Example 1 were obtained by the same operation except that the compound represented by formula (12) was used instead of formula (24).

[Implementation Example 3]

(Synthesis Example 3)

61.6 parts of the compound of formula (30) were added to 600 parts of water, dissolved with sodium hydroxide, and 15.6 parts of phenyl chloroformate were added, and stirred at 50 to 70°C for 6 hours to ureidize it. Salt precipitation was performed with sodium chloride, and after filtering, it was dried at 70°C to obtain 48.4 parts of the ureido compound represented by formula (23) of the compound example of the present invention. The polarized light-emitting element and polarized light-emitting plate of Example 1 were obtained by the same operation except that the compound represented by formula (23) was used instead of formula (24).

[Implementation Example 4]

(Synthesis Example 4)

21.8 parts of the compound of formula (31) and 37.0 parts of the compound of formula (32) were added to 500 parts of water, dissolved with sodium hydroxide, and 20.0 parts of terephthaloyl chloride were slowly added over about 1 hour. After the addition was complete, the mixture was stirred at 60°C for 1 hour. After the reaction was completed, it was cooled to room temperature, filtered, and dried at 70°C to obtain 10.3 parts of the compound represented by formula (33). 50.3 parts of the compound of formula (33) were added to 600 parts of water, dissolved with sodium hydroxide, and 7.8 parts of phenyl chloroformate were added. The mixture was stirred at 50 to 70°C for 6 hours to ureidize the mixture. The product was precipitated with sodium chloride, filtered and dried at 70°C to obtain 5.8 parts of the urea compound represented by formula (16). The polarized light-emitting element and polarized light-emitting plate of Example 1 were obtained by the same operation except that the compound represented by formula (16) was used instead of formula (24).

[Implementation Example 5]

(Synthesis Example 5)

40.0 parts of the compound of formula (34) are added to 500 parts of water, dissolved with sodium hydroxide, and then 15.6 parts of phenyl chloroformate are slowly added over about 1 hour, stirred at 50 to 70°C for 6 hours to react, and then 37.0 parts of the compound of formula (32) are added to react. Then, 14.2 parts of the compound described in formula (35) are added to dissolve, and 14.1 parts of terephthaloyl chloride are slowly added over about 1 hour. After the addition is complete, stir at 60°C for 1 hour. After the reaction is completed, it is cooled to room temperature, filtered, and dried at 70°C to obtain 54.2 parts of the compound represented by formula (36) of the compound example of the present invention. The polarized light emitting element and polarized light emitting plate of Example 1 are obtained by performing the same operation except that the compound represented by formula (36) is used instead of formula (24).

[Implementation Example 6]

(Synthesis Example 6)

71.2 parts of the compound of formula (37) were added to 600 parts of water, and sodium hydroxide was added while dissolving. After 15.6 parts of phenyl chloroformate was slowly added over about 1 hour, it was stirred at 50 to 70°C for 6 hours to ureidize. Salt precipitation was performed with sodium chloride, and after filtering, it was dried at 70°C to obtain 50.2 parts of the ureido compound represented by formula (21) of the compound example of the present invention. The polarized light-emitting element and polarized light-emitting plate of Example 1 were obtained by the same operation except that the compound represented by formula (21) was used instead of formula (24).

[Comparison Example 1]

The polarized light emitting element and polarized light emitting plate of Example 1 were obtained by the same operation except that the compound represented by formula (38) described in Japanese Patent Publication No. 4-226162 was used instead of formula (24). The polarized light emitting element and polarized light emitting plate were used as the sample of Comparative Example 1.

[Comparison Example 2]

Except that C.I. Direct Yellow 4 of the compound represented by formula (39) is used instead of formula (24) in the polarized light emitting element and polarized light emitting plate of Example 1, the same operation is performed to obtain the polarized light emitting element and polarized light emitting plate, and this polarized light emitting plate is used as the sample of Comparative Example 2.

[Comparison Example 3]

Except that the compound represented by formula (40) is used in place of formula (24) in the polarized light emitting element and polarized light emitting plate of Example 1, the polarized light emitting element and polarized light emitting plate are obtained by the same operation, and the polarized light emitting plate is used as the sample of Comparative Example 3.

[Assessment]

The polarized light-emitting plates obtained in Examples 1 to 6 and Comparative Examples 1 to 3 were used as test samples and evaluated as follows.

(a) Single body transmittance Ts, parallel position transmittance Tp and vertical position transmittance Tc

The single transmittance Ts(%), parallel transmittance Tp(%) and perpendicular transmittance Tc(%) of each test sample were measured using a spectrophotometer ("U-4100" manufactured by Hitachi, Ltd.). Here, the single transmittance Ts(%) is the transmittance of each wavelength when one test sample is measured. The parallel transmittance Tp(%) is the spectral transmittance of each wavelength measured by overlapping two test samples so that their absorption axes are parallel. The perpendicular transmittance Tc(%) is the spectral transmittance of each wavelength measured by overlapping two test samples so that their absorption axes are perpendicular. Each transmittance was measured in the wavelength range of 220 to 780nm.

(b) Polarization degree ρ

Substitute the parallel transmittance Tp and the vertical transmittance Tc into the following formula (I) to obtain the polarization degree ρ (%) of each measured sample.

ρ={(Tp-Tc)/(Tp+Tc)} ^1/2 ×100． ． ． Formula (I)

(c) Single body transmittance Ys after correcting the luminescence factor

The single body transmittance Ys (%) of each test sample is the transmittance after the luminescence factor is corrected according to JIS Z 8722:2009 for the above single body transmittance Ts obtained at predetermined wavelength intervals dλ (5nm in this case) in the wavelength range of 400 to 700nm in the visible light range. Specifically, the single body transmittance Ts is substituted into formula (II) and calculated. In the following formula (II), Pλ represents the spectral distribution of standard light (C light source), and yλ represents the 2-degree viewing angle isochromatic function.

(d) Measurement of emitted polarized light

A 375nm hand light type black light (PW-UV943H-04 manufactured by Nichia Chemical Co., Ltd.) belonging to an ultraviolet LED was used as a light source, and a filter (IUV-340 manufactured by Isuzu Seiko Glass Co., Ltd.) that transmits ultraviolet light/blocks visible light was set on the light source to block visible light. A polarizing plate (SKN-18043P manufactured by Pola Techno, thickness 180μm, Ys43%) with polarization in the visible and ultraviolet regions and the measurement samples obtained in each embodiment and comparative example were set above it, and the polarized light emitted by the measurement samples was measured using a spectroradiometer (USR-40 manufactured by Ushio Electric Co., Ltd.). That is, the light from the light source is configured to sequentially pass through a filter that transmits ultraviolet light/blocks visible light, a polarizing plate that has polarization in the visible light range and ultraviolet light range, and a measurement sample, and is incident on a spectroradiometer to measure polarized luminescence. At this time, the absorption axis when the ultraviolet absorption of the measured sample is maximum is overlapped in parallel with the absorption axis direction of the polarizing plate ("SKN-18043P" manufactured by Pola Techno) with polarization in the visible light domain and the ultraviolet light domain, and the spectral luminescence amount of each wavelength is measured as Lw (weak luminescence axis), and the absorption axis when the ultraviolet absorption of the measured sample is maximum is overlapped in a perpendicular manner with the polarizing plate ("SKN-18043P" manufactured by Pola Techno) with polarization in the visible light domain and the ultraviolet light domain, and the spectral luminescence amount of each wavelength is measured as Ls (strong luminescence axis), and Lw and Ls are measured. When the absorption axes between the sample and the general polarizing plate are parallel, the energy of the light emitted in the visible light range when perpendicular is confirmed. The polarized light emitted in the visible light range of 400nm to 700nm is evaluated.

(e) Lightfastness test

Using SX-75 manufactured by Suga Testing Co., Ltd., the light irradiation was performed for 500 hours at an irradiation illumination of 60W, an ambient temperature of 30°C, and a relative humidity of 30%RH, and the light resistance test was performed. The changes in Ls and Lw at each wavelength were confirmed at this time.

Table 1 shows the wavelength of the maximum polarization degree of the measured samples obtained in Examples 1 to 6 and Comparative Examples 1 to 3, the single body transmittance (Ts, %), parallel position transmittance (Tp, %), perpendicular position transmittance (Tc, %) and polarization degree (ρ, %) at the wavelength showing the maximum polarization degree, the single body transmittance after correcting the luminescence factor (Ys, %), and the polarization degree after correcting the luminescence factor (ρy, %).

[Table 1]

Table 2 shows Ls and Lw of each wavelength in Examples 1 to 6 and Comparative Examples 1 to 3.

Table 3 shows the Ls and Lw of each wavelength after the light resistance test in Examples 1 to 4 and Comparative Example 1.

As shown in Table 1, it can be seen that the test samples of Examples 1 to 6 and Comparative Example 1 have absorption in the ultraviolet light domain and function as a polarizer in this band. On the other hand, it can be seen that the transmittance in the visible light domain (luminescence factor corrected transmittance Ys) is shown to be above 90%, and even if it has a polarization function in the ultraviolet light domain, the visible light transparency is also high. In contrast, since Comparative Examples 2 and 3 show a wavelength of maximum polarization above 400nm and the luminescence factor corrected transmittance Ys is reduced, a reduction in visible light transmittance can be observed. On the other hand, as shown in Table 2, in the test samples of Comparative Examples 2 and 3, Lw and Ls are both 0, indicating that no light is emitted due to ultraviolet irradiation. In addition, it can be seen that since Lw and Ls are detected in Examples 1 to 6 and Comparative Example 1, polarized light is emitted due to ultraviolet irradiation. On the other hand, the luminous brightness in Examples 1 to 6 is higher than that in Comparative Example 1, and the wavelength thereof is high polarized light in a wide band range of 400 to 700 nm. In addition, as shown in Table 3, when confirming Lw and Ls after the light resistance test, Examples 1 to 4 have higher light resistance than Comparative Example 1. Therefore, the measured samples of Examples 1 to 4 represent the function of a polarized light emitting element that emits polarized light in the visible light range due to ultraviolet irradiation.

(f) Durability test

The polarized light-emitting plates obtained in Examples 1 to 6 were placed in an environment of 105°C for 1,000 hours and in an environment of 60°C and 90% relative humidity for 1,000 hours. When durability tests were performed, no decrease in polarization degree or change in polarized light emission was observed. This shows that the polarized light-emitting elements and polarized light-emitting plates of Examples 1 to 6 have high durability even in harsh environments.

[Industrial applicability]

By using a substrate containing the luminescent compound of the present invention or a salt thereof, a polarized light-emitting element and a polarized light-emitting plate that not only have a high degree of polarization at the absorption wavelength but also exhibit a polarized light-emitting effect can be obtained. Therefore, the polarized light-emitting element and the polarized light-emitting plate using the luminescent compound of the present invention can be used as a self-luminous polarizing element that plays the role of a polarizing plate at the absorption wavelength and can emit polarized light. In addition, such polarized light-emitting elements and polarized light-emitting plates have excellent durability and high transmittance in the visible light region. Therefore, the display using the polarized light-emitting element and the polarized light-emitting plate of the present invention can be widely used in televisions, personal computers, tablet computer settings, transparent displays (see-through displays), etc., because it has high transparency in the visible light region and can display images caused by polarized light for a long time. In addition, since the polarized light-emitting element or its polarized light-emitting plate made using the light-emitting compound of the present invention can emit light by ultraviolet light, it can also be applied to displays or media that require high safety.

Claims (10)

A polarized light emitting element comprising a light emitting compound represented by formula (1) or a salt thereof;

In formula (1), k independently represents an integer of 0 or 1, at least one of X and Y represents a heterocyclic group containing a nitrogen atom or a sulfur atom which may have a substituent, or a group represented by formula (2), and the other X and Y independently represent 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, or an alkoxy group having 1 to 4 carbon atoms which may have a substituent, a heterocyclic group containing a nitrogen atom or a sulfur atom which may have a substituent, or a group represented by formula (2) ; M represents a hydrogen atom, a metal ion or an ammonium ion, and m independently represents an integer from 0 to 2; in formula (2), ※ represents the bonding position of X and Y in formula (1), Z is a group selected from the group consisting of a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a distyryl group which may have a substituent, a benzoyl group which may have a substituent or a heterocyclic group which may have a substituent; and t represents an integer of 0 or 1. The polarized light emitting element as claimed in claim 1, wherein X and Y in the above formula (1) and at least one of Z when at least one of X and Y in the above formula (1) is represented by the above formula (2) are selected from the group consisting of the following formulas (3) to (7);

In the above formulae (3) and (4), each A is independently a group selected from the group consisting of a hydrogen atom, a halogen group, a nitro group, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms with a sulfonic acid group, an alkyl group having 1 to 4 carbon atoms with a hydroxyl group, an alkyl group having 1 to 4 carbon atoms with a carboxyl group, an alkoxy group having 1 to 4 carbon atoms with a sulfonic acid group, an alkoxy group having 1 to 4 carbon atoms with a hydroxyl group, and an alkoxy group having 1 to 4 carbon atoms with a carboxyl group, ^q1 represents an integer from 0 to 4, M in the above formulae (3) to (7) is as defined in the above formula (1), and M in the formulae (3) to (7) and M in the formula (1) may be the same, and ⁿ¹ , n2, n3, n4, n5, n6, n7, n8, n9, n10, n111, n122, n13, n14, n15, n16, n17, n18, n19, n20, n219, n10, n111 ² each independently represents an integer from 0 to 3; * in the above formulas (3) to (7) respectively represents the bonding position in X or Y of the above formula (1), or the bonding position in Z of the above formula (2). A polarized light emitting element as described in claim 2, wherein k in the above formula (1) is 0 or 1, at least one of X and Y is selected from any group consisting of formulas (2) to (7), and when at least one of X and Y is formula (2), Z is selected from any group consisting of formulas (3) to (7). A polarized light emitting element as described in claim 2, wherein each k in the above formula (1) is 0, X and Y are each selected from any group consisting of formulas (2) to (7), and when X and Y are formula (2), Z is selected from any group consisting of formulas (3) to (7). A polarized light emitting element as described in claim 2, wherein each k in the above formula (1) is 1, X and Y are each a base selected from the group consisting of formulas (2) to (7), and when X and Y are formula (2), Z is selected from the group consisting of formulas (3) to (7). The polarized light emitting element as described in any one of claims 1 to 5 further contains one or more organic dyes or fluorescent dyes other than the above-mentioned light emitting compounds or their salts. The polarized light emitting element as described in any one of claims 1 to 5 further comprises a substrate. The polarized light emitting element as described in claim 7, wherein the substrate is a film containing polyvinyl alcohol resin or its derivatives. A polarized light emitting plate, wherein at least one side of the polarized light emitting element described in any one of claims 1 to 8 is provided with a transparent protective film. A display device having a polarized light emitting element as described in any one of claims 1 to 8 or a polarized light emitting plate as described in claim 9.