JP2020091478A - Polarized light emitting device, polarized light emitting plate, and display using the same - Google Patents

Abstract

To provide a polarized light emitting device that has a high polarized light emission luminance and contrast, while emitting light with a high degree of polarization.SOLUTION: A polarized light emitting device has a function to absorb light in the near ultraviolet range to the near ultraviolet visible range and emit light by using the absorbed light, and a function to emit polarized light with a wavelength in the visible range by using the emitted light.SELECTED DRAWING: None

Description

The present invention relates to a polarized light emitting element that emits polarized light with high brightness, a polarized light emitting plate, and a display device using the same.

A polarizing plate having a light transmitting or shielding function is a basic constituent element of a display device such as a liquid crystal display (LCD) together with a liquid crystal having a light switching function. The field of application of this LCD is expanding from small instruments such as calculators and watches in the early stages of the market to notebook computers, word processors, liquid crystal projectors, liquid crystal televisions, car navigations, indoor and outdoor information display devices, and measuring instruments. In addition, the polarizing plate can be applied to a lens having a polarizing function, and has been applied to sunglasses with improved visibility, and in recent years, to polarizing glasses compatible with 3D televisions, etc., wearable terminals. It is being applied to familiar information terminals such as, and partly put into practical use. The polarizing plate has a wide variety of applications, and its use environment is wide range of conditions of low temperature to high temperature, low humidity to high humidity, and low light amount to high light amount. Therefore, it has high polarization performance and excellent durability. A polarizing plate is required.

In general, the polarizing film contained in the polarizing plate is made by dyeing or containing iodine or a dichroic dye in a stretched and oriented film of polyvinyl alcohol or a derivative thereof, or dehydrochlorination of a polyvinyl chloride film or a polyvinyl alcohol film. It is produced by producing polyene by dehydration and orienting it. Since the manufactured polarizing plate contains iodine or a dichroic dye having absorption in the visible region, the transmittance is generally lowered. For example, the transmittance of a commercially available general polarizing plate is 35 to 45%.

In addition, in order to obtain a polarization degree of 100% in “polarization degree” which is one of the indexes showing the polarization performance of a polarizing plate, when light of x axis and y axis exists in a two-dimensional plane, one of Only the light on the axis needs to be absorbed. Therefore, in a general polarizing plate, iodine or a dichroic dye is used in order to absorb only the light of one axis. When only the light of one axis is absorbed, the amount of light transmitted through the polarizing plate is 50% or less in principle with respect to the amount of incident light of 100%. Furthermore, due to the decrease in the polarization degree due to the poor orientation of iodine or dichroic dye, the light loss due to the film medium, the interface reflection on the film surface, etc., the transmittance actually decreases further than 50%, and as a result, The transmittance of the conventional polarizing plate is as low as 35 to 45%. For such a problem that the transmittance of a general polarizing plate is as low as 35 to 45%, as a technique for imparting a polarizing function while maintaining a certain degree of transmittance in the visible region, an ultraviolet polarizing plate This technique is described in Patent Document 1. However, the polarizing plate obtained by this technique is colored yellow and can only provide a polarizing plate exhibiting a polarizing function only for light near 410 nm. That is, it does not impart the polarization function to the visible light having high visibility.

If a polarizing plate having a low transmittance of light in the visible region or a polarizing plate having a low degree of polarization is used in, for example, a display, the brightness and contrast of the entire display are lowered. In order to solve this problem, a method of obtaining polarized light without using a conventional polarizing plate has been studied, and as one of the methods, an element that emits polarized light (polarized light emitting element) is described in Patent Documents 2 to 6. Has been done.

WO2005/001527 JP, 2008-224854, A Japanese Patent No. 5849255 Japanese Patent No. 5713360 US Pat. No. 3,276,316 JP-A-4-226162

However, the polarized light emitting elements described in Patent Documents 2 to 4 use a special metal, for example, a lanthanoid such as europium, which has a high rarity value, so that the manufacturing cost is high, and the manufacturing is difficult and mass-produced. Not suitable for. Furthermore, since these polarized light emitting elements have a low degree of polarization, it is difficult to use them for a display, and it is difficult to obtain the light emission of linearly polarized light. In addition, since only circularly polarized light having a specific wavelength can be obtained, its use is limited, and even if it is used for a display, both brightness and contrast are low, and there is a problem that the design of a liquid crystal cell is difficult. Therefore, a new polarizing plate exhibiting a polarized light emission action, having a high polarized light emission degree, a high transmittance in the visible light region, and being applicable to a liquid crystal display or the like which is required to have durability in a harsh environment, and The development of materials used for it is strongly desired. On the other hand, Patent Documents 5 and 6 disclose patents relating to an element that emits polarized light when irradiated with ultraviolet rays. However, since the degree of polarization and brightness of the element that emits light are extremely low and the so-called polarization contrast is low, it is not sufficient for use in displays and the like, and its light resistance is also low.

INDUSTRIAL APPLICABILITY The present invention emits polarized light that emits light having a high degree of polarization, has high polarized light emission brightness, and is applicable to liquid crystal displays and the like that require high durability in harsh environments. It is an object to provide a polarized light emitting element, a polarized light emitting plate using the same, and a display device.

The present inventors, as a result of intensive research to achieve such an object, absorb the light in the near-ultraviolet to near-ultraviolet visible region, emit light by utilizing the absorbed light, and the emitted light A polarized light emitting element having a function of emitting polarized light having a wavelength in the visible region by utilizing it, and a polarized light emitting plate using the same are capable of emitting polarized light with high brightness, They have found that they have durability and have completed the present invention.

That is, the present invention relates to 1) to 10).
1)
Near-ultraviolet to near-ultraviolet light in the visible range is absorbed, the function of emitting light by using the absorbed light, and the function of emitting polarized light having a wavelength in the visible range using the emitted light, A polarized light-emitting device having.
2)
The polarized light emitting element according to 1), wherein the polarized light emitting element absorbs light in a wavelength range of at least 300 to 360 nm and emits light having an emission wavelength in a wavelength range of at least 400 to 700 nm.
3)
The polarized light according to 1) or 2), wherein the polarized light-emitting element absorbs light in the wavelength range of at least 300 to 360 nm and emits light having an emission wavelength in the wavelength range of at least 350 to 430 nm. Light emitting element.
4)
Any one of 1) to 3) in which the polarized light emitting element includes a compound (b) that absorbs light in a wavelength range of at least 350 to 430 nm and emits light having an emission wavelength in a wavelength range of at least 400 to 700 nm. The polarized light-emitting device according to item.
5)
The polarized light emitting element according to any one of 1) to 4), wherein the light emitted by the polarized light emitting element is linearly polarized light.
6)
The polarized light emitting device according to 4) or 5), wherein the compound (b) is a compound that exhibits absorption anisotropy when oriented.
7)
The polarized light emitting device according to any one of 3) to 6), wherein the compound (a) is a compound that exhibits absorption anisotropy when oriented.
8)
The compound (b) has at least one skeleton selected from the group consisting of a stilbene skeleton, a biphenyl skeleton, and a coumarin skeleton in the molecule, at least in a molecule thereof. Polarized light emitting element.
9)
A polarized light emitting plate comprising the polarized light emitting element according to any one of 1) to 8).
10)
A display device comprising the polarized light emitting element according to any one of 1) to 8) or the polarized light emitting plate according to 9).

Polarized light emitting device according to the present invention, and a polarized light emitting plate using the same, while utilizing the incident light with high efficiency, while exhibiting a high polarization effect at the emission wavelength, to express a high-luminance light emitting effect, Also, high durability can be imparted. According to the present invention, highly efficient light emission is achieved by wavelength-converting the wavelength of the light to the absorption wavelength of the dye capable of absorbing the natural light or the artificial light with high efficiency and providing polarized light emission. It is possible to provide a polarized light emitting element which can be added and has a high light emission luminance while having a high transmittance in the visible light region. Further, it is generally known that a certain amount of light such as ultraviolet rays deteriorates polymers and dyes. However, in the present invention, the light energy that causes the deterioration is used for light emission, and therefore the energy that causes the deterioration is Provided is a polarized light-emitting device which can be suitably used for a display device capable of substantially suppressing the above and imparting high durability to the device itself, particularly a display device required to have high light resistance, for example, a display device such as a liquid crystal display. Leading to.

The present invention absorbs light in the near-ultraviolet to near-ultraviolet visible region and emits light by using the absorbed light, and emits polarized light having a wavelength in the visible region by using the emitted light. (EN) A polarized light emitting element having a function, a polarized light emitting plate using the same, and a display device including any one of them.

The polarized light emitting element is preferably an element that absorbs light in the wavelength range of at least 300 to 360 nm and emits light having an emission wavelength in the wavelength range of at least 400 to 700 nm. It is known that the light in the wavelength range of 300 to 360 nm is generally in the ultraviolet range and cannot be detected by human eyes. The wavelength of the light emitted by the polarized light emitting element is not particularly limited, and may be light in the near-ultraviolet to near-ultraviolet visible range, but is in the wavelength range of 400 to 700 nm, or at least part of the wavelength range. Is preferably emitted. That is, it is a preferred form of the polarized light emitting element that the polarized light emitting element emits light in the near-ultraviolet to near-ultraviolet visible region and uses the light to emit polarized light having a wavelength in the visible region. .. As a function of the polarized light emitting device of the present application, light in the wavelength range of 300 to 360 nm is absorbed, light is emitted using the light, the emitted light is further absorbed, and 400 to 700 nm which is light in the visible range. Polarized light is emitted, but as a function of the polarized light emitting element of the present application, light in the wavelength range of 300 to 360 nm is absorbed, and light emitted using the light is further absorbed by the total amount of the emitted light. When used to emit light having a wavelength of 700, the device substantially absorbs light in the wavelength range of at least 300 to 360 nm and emits light having an emission wavelength in the wavelength range of at least 400 to 700 nm. Will be shown.

The polarized light emitting device absorbs light in the near-ultraviolet to near-ultraviolet visible region, emits light by utilizing the absorbed light, absorbs light emitted by the compound (a), and absorbs the absorbed light. It is mentioned as a preferable embodiment of the present invention that each of the compounds (b) that emits polarized light having a wavelength in the visible range by utilizing the above is included.

The compound (a) is preferably a substance having a light absorbing function at 300 to 360 nm and capable of emitting light at 350 to 430 nm. Examples of the compound (a) include 2-(2-pyridylamino)ethylamine dihydrochloride (absorbing light of 300 nm and emitting light of 380 nm), 9,10-phenanthrenequinone (absorbing light of 310 nm, (Emission of light having a wavelength of 365 nm), diphenyl-1-perenylphosphine (absorption of light having a wavelength of 352 nm and emission of light having a wavelength of 380 nm) and the like can be used, but are not particularly limited. In particular, in recent years, the development of quantum dots, so-called quantum dots, has progressed, and it is known that quantum dot particles can also provide similar functions. Examples include gold quantum dots Au5-8 (excitation wavelength 330 nm, emission wavelength 405 nm), Au13 (excitation wavelength 330 nm, emission wavelength 510 nm), Au25 (excitation wavelength 360 nm, emission wavelength 670 nm) manufactured by Dainippon Paint Co., Ltd. However, the substance is not limited to these substances, and any inorganic substance or organic substance can be used. The above compound (a) may be used alone or in combination of two or more. Such a compound (a) can be added to the device containing the compound (b) described later, or the compound (a) can be attached to the surface of the device to obtain a preferred polarized light emitting device of the present application.

The compound (b) is not particularly limited as long as it is a compound that absorbs light in the ultraviolet to visible light region and can emit polarized visible light by exhibiting orientation or anisotropy. The compound (b) preferably absorbs light in the wavelength range of at least 350 to 430 nm and emits light having an emission wavelength in the wavelength range of at least 400 to 700 nm, and at least in the near ultraviolet to near ultraviolet visible range. It is preferable that the compound has a light absorbing function and can convert the wavelength of light to emit polarized light in the visible region. More preferably, the wavelength of the strongest absorption, that is, the maximum absorption wavelength is 350 to 430 nm, and the maximum emission emission wavelength is 400 to 700 nm. By having a light absorption function in the near-ultraviolet to near-ultraviolet visible region, it is possible to provide an element having a high transmittance without absorbing light having a wavelength in the visible region. That is, it is possible to provide an element capable of emitting visible polarized light despite having high transmittance.

The light emitted by the compound (b) is preferably linearly polarized light. Since the compound (b) is an element that emits linearly polarized light, there is an advantage that the degree of freedom of a display device such as a liquid crystal display is improved. Linearly polarized light is light that can also be represented as a wave in the direction of a constant axis. By emitting linearly polarized light, that is, uniaxially polarized light, it becomes easy to design a display device such as a liquid crystal display. Most of commercially available liquid crystal displays and polarizing lenses use an iodine-based polarizing plate or dye-based polarizing plate capable of providing linearly polarized light, that is, a polarizing plate using a dichroic dye having uniaxial absorption. Therefore, it can be easily considered that the linearly polarized light is suitable for industrial use. On the other hand, if you try to use circularly polarized light or elliptically polarized light, the design of the liquid crystal cell, and eventually the alignment of the liquid crystal used there, becomes complicated, or the design of the phase difference plate becomes significantly complicated, It is preferable that the polarized light is linearly polarized light because it is difficult to industrially use. The emission of light that is linearly polarized light can be achieved by orienting the compound (b) in the same direction in the device. In addition, by using the compound (b) to emit polarized light in the same direction, its emission intensity is increased, and is higher than the emission intensity when the compound (b) emits light in an aqueous solution at the same concentration. It can provide stronger light.

The compound (b) is preferably a compound having absorption anisotropy in the band that absorbs light due to the orientation of the compound. By orienting the compound (b) in the same direction in the polarized light emitting device, it is possible to provide light stronger than the original light emission intensity of the compound (b). At that time, the compound (b) preferably has absorption anisotropy as well as light emission. The absorption anisotropy may be generally represented as a dichroic ratio (hereinafter, also referred to as RD), and the degree of orientation of a dye depending on the dichroic ratio (hereinafter, may be referred to as an Order Parameter). Can be calculated. The dichroic ratio is a ratio between the absorption amount of the axis having the strongest absorption and the absorption amount of the axis having the lowest absorption. If the dichroic ratio has a value of 5 to 80, linearly polarized light is emitted. It is possible, and 10 or more is good, 20 or more is preferable, 30 or more is more preferable, and 40 or more is particularly preferable. The degree of orientation is a numerical value given by the following formula (I), preferably 0.85 or more and 1.00 or less, and particularly preferably 0.90 or more and 0.96 or less. The dichroic ratio is preferably measured in the state in which there is no interfacial reflection in the layer containing the compound (b), that is, the polarized light emitting device. The compound (b) may be used alone or in combination of two or more.

(Equation 1)
Order Parameter=(RD-1)/(RD+2) Formula (I)

The compound (b) preferably has at least one skeleton selected from the group consisting of a stilbene skeleton, a biphenyl skeleton, and a coumarin skeleton in the molecule, and the compound (b) is preferably oriented. As a method for manufacturing the polarized light emitting element, one of the following modes will be shown as an example.

<Substrate>
The polarized light emitting device uses a polymer film as a base material for adsorbing and orienting a polarized light emitting dye described later. The polymer film preferably adsorbs a polarized light-emitting dye having a general dichroism, particularly a dye having at least one skeleton selected from the group consisting of a stilbene skeleton, a biphenyl skeleton and a coumarin skeleton in its molecule. It is a hydrophilic polymer film obtained by forming a hydrophilic polymer into a film. The hydrophilic polymer is not particularly limited, but for example, a polyvinyl alcohol-based resin and a starch-based resin are preferable, and the polyvinyl alcohol-based resin is preferable from the viewpoints of the dyeability, processability and cross-linking property of the dichroic polarized light-emitting dye. It is preferably a resin or a derivative thereof. Examples of the polyvinyl alcohol-based resin and its derivative include polyvinyl alcohol or its derivative, and an olefin such as ethylene or propylene, or a vinyl alcohol or derivative thereof such as crotonic acid, acrylic acid, methacrylic acid, and maleic acid. Examples thereof include those modified with saturated carboxylic acid and the like. Among them, a film made of polyvinyl alcohol or a derivative thereof is preferably used from the viewpoint of the adsorptivity and orientation of the polarized light emitting dye having dichroism. As the base material, for example, a film made of a commercially available polyvinyl alcohol-based resin or a derivative thereof may be used, or may be produced by forming a film of the polyvinyl alcohol-based resin. The method for forming the polyvinyl alcohol-based resin film is not particularly limited, and examples thereof include a method of melt-extruding hydrous polyvinyl alcohol, a casting film forming method, a wet film forming method, and a gel film forming method (once cooling the polyvinyl alcohol aqueous solution. After the gelation, the solvent is extracted and removed), a cast film forming method (flowing an aqueous polyvinyl alcohol solution on a substrate and drying), and a combination of these methods can be used. The thickness of the substrate is usually 10 to 100 μm, preferably about 20 to 80 μm.

<Method of manufacturing polarized light emitting element>
The method for producing the polarized light-emitting element is not limited to the following production method, but it is mainly preferable to use a film made of polyvinyl alcohol or a derivative thereof, and a film made of polyvinyl alcohol or a derivative thereof is preferably used. A method of manufacturing a polarized light emitting device will be described by taking the case of using it as an example. The method for producing a polarized light-emitting device includes a step of preparing a base material, a swelling step of swelling the base material in a swelling liquid to swell the base material, and a swelled base material of a polarized light emitting dye described below. Dyeing step of impregnating a dyeing solution containing at least the above and adsorbing a polarized light emitting dye to a substrate, and dipping the substrate adsorbing the polarized light emitting dye into a solution containing boric acid In the cross-linking step of cross-linking, the stretching step of uniaxially stretching the polarized light-emitting dye cross-linked substrate in a certain direction to arrange the polarized light-emitting dye in a certain direction, and if necessary, a washing liquid for the stretched substrate. The washing step and/or the drying step of drying the washed substrate are included.

(Swelling process)
The swelling step will be described. The swelling step 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 draw ratio of the base material with the swelling liquid is preferably adjusted to 1.00 to 1.50 times, and more preferably 1.10 to 1.35 times.

(Dyeing process)
The dyeing step will be described. One or more polarized light-emitting dyes described below are adsorbed on the substrate obtained through the swelling step. The dyeing step is not particularly limited as long as it is a method capable of adsorbing a polarized light emitting dye described below on a substrate, but for example, a method of immersing the substrate in a dyeing solution containing a polarized light emitting dye, or a base Examples of the method include applying a dyeing solution containing a polarized light emitting dye to a material, and a method of immersing the material in a dyeing solution containing a polarized light emitting dye is preferable. The concentration of the polarized light emitting dye in the dyeing solution is not particularly limited as long as the polarized light emitting dye is sufficiently adsorbed in the substrate, but for example, the concentration of the polarized light emitting dye in the dyeing solution is It is preferably 0.0001 to 1% by mass, and more preferably 0.0001 to 0.5% by mass. The temperature of the dyeing solution in the dyeing step is preferably 5 to 80°C, more preferably 20 to 50°C, particularly preferably 40 to 50°C. The time for immersing the substrate in the dyeing solution can be adjusted as appropriate, and is preferably adjusted within 30 seconds to 20 minutes, more preferably 1 to 10 minutes. The polarized light-emitting dye contained in the dyeing solution may be used alone or in combination of two or more. The above-mentioned polarized light-emitting dyes have different emission colors due to differences in dye structure and the like. Therefore, by incorporating two or more types of the above-described polarized light-emitting dyes in the base material, the emission colors produced are appropriately adjusted to various colors. be able to. Further, if necessary, the dyeing solution may further contain one or more kinds of organic dyes and/or fluorescent dyes in addition to the polarized light-emitting dye described below.

(Polarized luminescent dye)
Examples of the polarized light-emitting dye include those that emit fluorescence or phosphorescence, and can be used as the compound (b). Preferred examples of the dye are compounds having a stilbene skeleton, biphenyl skeleton, and coumarin skeleton in the molecule, and a salt or a salt thereof that emits light by using absorbed light. As. Those that emit fluorescence or phosphorescence are mentioned as preferable ones. However, while the polarized light-emitting dye has a fluorescent emission function, the dye has a dichroic ratio at the absorption wavelength of light, so that a higher polarized light is obtained. Can be made to emit light. In particular, a polarized luminescent dye having at least one skeletal skeleton selected from the group consisting of a stilbene skeleton, a biphenyl skeleton, and a coumarin skeleton in the dye molecule has excellent fluorescence emission characteristics, and when aligned, has a high absorption wavelength. Combines the characteristics of having a dichroic ratio. These are derived from the characteristics of each skeleton, and further improve these characteristics, and adjust various characteristics such as absorption wavelength, emission wavelength, light resistance, moisture resistance, ozone gas resistance, and other robustness and solubility. Depending on the purpose, it is possible to further introduce an arbitrary substituent into each of the above skeletons. In the introduction of the substituent, if the kind of the substituent or the selection of the substitution position is not preferable, even if a high degree of polarization can be realized as in the conventional dye-based polarizing plate, the amount of emitted light is significantly reduced. Since problems may occur, the selection of the type of substituent and the substitution position is particularly important in order to have excellent fluorescence emission characteristics and a high dichroic ratio. In addition, the above polarized luminescent dyes may be used alone or in combination of two or more.

(B-1) Dye having stilbene skeleton The dye having a stilbene skeleton is preferably a compound represented by the following formula (1) or a salt thereof.

In the above formula (1), L and M may each independently have a nitro group, an amino group which may have a substituent, a carbonylamide group which may have a substituent, and a substituent. A naphthotriazole group, an alkyl group having 1 to 20 carbon atoms which may have a substituent, a vinyl group which may have a substituent, an amide group which may have a substituent, and a substituent which may have a substituent. It represents a good ureido group, an aryl group which may have a substituent or a carbonyl group which may have a substituent, but is not necessarily limited thereto. It is known that a dye having a stilbene skeleton represented by the formula (1) has fluorescence emission and can obtain dichroism by being oriented. This is mainly derived from the stilbene skeleton. In addition, any substituent may be introduced. However, when the stilbene skeleton has an azo group at the L position and the M position, fluorescence emission is significantly reduced, which is not preferable.

Examples of the amino group which may have a substituent include an unsubstituted amino group, a methylamino group, an ethylamino group, an n-butylamino group, a tert-butylamino group, an n-hexylamino group and a dodecylamino group. Group, dimethylamino group, diethylamino group, di-n-butylamino group, ethylmethylamino group, ethylhexylamino group, and the like, optionally substituted alkylamino group having 1 to 20 carbon atoms, phenylamino group, diphenyl Substitution of arylamino group, methylcarbonylamino group, ethylcarbonylamino group, n-butyl-carbonylamino group and the like which may have a substituent such as amino group, naphthylamino group and N-phenyl-N-naphthylamino group An optionally substituted arylcarbonylamino group having 1 to 20 carbon atoms, such as an alkylcarbonylamino group, a phenylcarbonylamino group, a biphenylcarbonylamino group, and a naphthylcarbonylamino group, and a methylsulfonylamino group. Group, an ethylsulfonylamino group, a propylsulfonylamino group, an n-butyl-sulfonylamino group, or another alkylsulfonylamino group having 1 to 20 carbon atoms, a phenylsulfonylamino group, a naphthylsulfonylamino group, or another substituent. Good arylsulfonylamino and the like, which may have a substituent, an alkylcarbonylamino group having 1 to 20 carbon atoms, an arylcarbonylamino group which may have a substituent, an alkylsulfonylamino having 1 to 20 carbon atoms. It is preferably an arylsulfonylamino group which may have a group or a substituent. Moreover, the C1-C20 alkylamino group which may have the said substituent, the arylamino group which may have a substituent, the C1-C20 alkylcarbonylamino which may have a substituent. The group, the arylcarbonylamino group which may have a substituent, the alkylsulfonylamino group having 1 to 20 carbon atoms, the substituent in the arylsulfonylamino group which may have a substituent are not particularly limited, Examples thereof include nitro group, cyano group, hydroxyl group, sulfonic acid group, phosphoric acid group, carboxy group, carboxyalkyl group, halogen atom, alkoxy group, aryloxy group and the like.

Examples of the carboxyalkyl group include a methylcarboxy group and an ethylcarboxy group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. Examples of the alkoxy group include a methoxy group, an ethoxy group and a propoxy group. Examples of the aryloxy group include a phenoxy group and a naphthoxy group. As good carbonylamido group optionally having the above substituent, for example, N- methyl - carbonyl amide group (-CONHCH _3), N- ethyl - carbonyl amide group (-CONHC ₂ H _5), N- phenyl - carbonyl and amide group (-CONHC ₆ H ₅₎ can be mentioned. Examples of the naphthotriazole group which may have a substituent include a benzotriazole group and a naphthotriazole group. Examples of the alkyl group having 1 to 20 carbon atoms which may have a substituent include direct groups such as methyl group, ethyl group, n-butyl group, n-hexyl group, n-octyl group and n-dodecyl group. Examples thereof include branched chain alkyl groups such as chain alkyl groups, isopropyl groups, sec-butyl groups, and tert-butyl groups, and cyclic alkyl groups such as cyclohexyl groups and cyclopentyl groups. Examples of the vinyl group which may have a substituent include a vinyl group, a methylvinyl group, an ethylvinyl group, a divinyl group, a pentadiene group and the like. As good amido group optionally having the above substituent, for example, acetamide group (-NHCOCH _3), such as benzamido group (-NHCOC ₆ H ₅₎ can be mentioned. Examples of the aryl group that may have a substituent include a phenyl group, a naphthyl group, an anthracenyl group, and a biphenyl group. Examples of the carbonyl group which may have a substituent include a methylcarbonyl group, an ethylcarbonyl group, an n-butyl-carbonyl group, a phenylcarbonyl group and the like. The above-mentioned optionally substituted carbonylamide group, optionally substituted naphthotriazole group, optionally substituted C1-20 alkyl group, optionally substituted As a substituent in a vinyl group, an amide group which may have a substituent, an ureido group which may have a substituent, an aryl group which may have a substituent, and a carbonyl group which may have a substituent Is not particularly limited, but may be the same as the substituent described in the above-mentioned amino group which may have a substituent.

The dye having a stilbene skeleton represented by the above formula (1) is particularly preferably a dye represented by the following formula (2) or a salt thereof, or a dye represented by the following formula (3) or a salt thereof. By using these dyes, it is possible to obtain a polarized light-emitting device that emits clear white light with higher brightness.

In the above formula (2), the substituent R is a hydrogen atom, a chlorine atom, a bromine atom, or a halogen atom such as a fluorine atom, a hydroxyl group, a carboxy group, a nitro group, an alkyl group which may have a substituent, or a substituent. It represents an alkoxy group which may have or an amino group which may have a substituent. The halogen atom may be the same as above. The alkyl group which may have a substituent may be the same as the alkyl group having 1 to 20 carbon atoms which may have a substituent. The alkoxy group which may have a substituent is preferably a methoxy group, an ethoxy group or the like. The amino group which may have a substituent may be the same as above, and is preferably a methylamino group, a dimethylamino group, an ethylamino group, a diethylamino group, a phenylamino group or the like. The substituent R may be bonded to any carbon of the naphthalene ring in the naphthotriazole ring, but when the carbon condensed with the triazole ring is the 1-position and the 2-position, the 3-position, the 5-position, or It is preferably bonded to the 8-position. n is an integer of 0 to 3, preferably 1 or 2. - (SO 3 _H) groups may be attached to any carbon of the naphthalene ring in naphthotriazole ring. The substitution position of the —(SO ₃ H) group in the naphthalene ring is, when n=1, when the carbon condensed with the triazole ring is the 1-position and the 2-position, the 4-position, the 6-position, or the 7-position. Is preferred, and when n=2, it is preferably at positions 5 and 7, and 6 and 8; when n=3, it is a combination of positions 3, 6 and 8. Preferably. Further, it is particularly preferable that R is a hydrogen atom and n is 1. X represents a nitro group or an amino group which may have a substituent, and is preferably a nitro group. The amino that may have a substituent may be the same as the above, an alkylcarbonylamino group having 1 to 20 carbon atoms that may have a substituent, an arylcarbonylamino group that may have a substituent, It is preferably an alkylsulfonylamino group having 1 to 20 carbon atoms or an arylsulfonylamino group which may have a substituent.

Y in the above formula (3) represents an alkyl group having 1 to 20 carbon atoms which may have a substituent, a vinyl group which may have a substituent, or an aryl group which may have a substituent. It is preferably an aryl group which may have a substituent, more preferably a naphthyl group which may have a substituent, and a naphthyl group in which an amino group and a sulfo group are substituted as a substituent. Is particularly preferable. Z represents the same substituent as described for X in the above formula (2), and is preferably a nitro group.

Examples of the compound represented by the above formula (1) include the Kayaphor series (manufactured by Nippon Kayaku Co., Ltd.) and the Whitex series (manufactured by Sumitomo Chemical Co., Ltd.) such as Whitex RP. In addition, the compound represented by the formula (1) is exemplified below, but the compound is not limited thereto.

(B-2) Dye having a biphenyl skeleton The dye having a biphenyl skeleton is preferably a compound represented by the following formula (4) or a salt thereof.

In the above formula (4), P and Q may each independently have a nitro group, an amino group which may have a substituent, a carbonylamide group which may have a substituent, or a substituent. A naphthotriazole group, an alkyl group having 1 to 20 carbon atoms which may have a substituent, a vinyl group which may have a substituent, an amide group which may have a substituent, and a substituent which may have a substituent. It represents a good ureido group, an optionally substituted aryl group, or an optionally substituted carbonyl group, but is not necessarily limited thereto. An amino group which may have a substituent, a carbonylamide group which may have a substituent, a naphthotriazole group which may have a substituent, and an alkyl group having 1 to 20 carbon atoms which may have a substituent. The group, the vinyl group which may have a substituent, the amide group which may have a substituent, the aryl group which may have a substituent and the carbonyl group which may have a substituent are respectively the same as above. Good. However, when an azo group is present at the P position and/or the Q position of the biphenyl skeleton in the above formula (4), fluorescence emission is significantly reduced, which is not preferable.

The compound represented by the above formula (4) is preferably a compound represented by the following formula (5).

In the above formula (5), j represents an integer of 0 to 2. The preferred substitution position of the —(SO ₃ H) group is not particularly limited, but when the vinyl group is the 1-position, the 2-position and 4-position are preferred, and the 2-position is particularly preferred.

In the above formula (5), R ₁ , R ₂ , R ₃ , and R ₄ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an aralkyloxy group, or an alkenyloxy group. A group, an alkylsulfonyl group having 1 to 4 carbon atoms, an arylsulfonyl group having 6 to 20 carbon atoms, a carbonamido group, a sulfonamide group, and a carboxyalkyl group. The carboxyalkyl group may be the same as above.

Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, a tert-butyl group and a cyclobutyl group. Examples of the alkoxy group having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group and a cyclobutoxy group. Examples of the aralkyloxy group include aralkyloxy groups having 7 to 18 carbon atoms. Examples of the alkenyloxy group include an alkenyloxy group having 1 to 18 carbon atoms. Examples of the alkylsulfonyl group having 1 to 4 carbon atoms include a methylsulfonyl group, an ethylsulfonyl group, a propylsulfonyl group, an n-butylsulfonyl group, a sec-butylsulfonyl group, a tert-butylsulfonyl group and a cyclobutylsulfonyl group. Be done. Examples of the arylsulfonyl group having 6 to 20 carbon atoms include a phenylsulfonyl group, a naphthylsulfonyl group and a biphenylsulfonyl group.

In the above formula (5), the preferred substitution positions of R _{1 to} R ₄ are preferably the 2-position and 4-position, when the vinyl group is preferably the 1-position.

The method for synthesizing the polarized light-emitting dye represented by the above formula (5) will be described below.

The polarized light-emitting dye represented by the above formula (5) can be produced by a known method, but for example, it can be obtained by condensing 4-nitrobenzaldehyde-2-sulfonic acid with a phosphonate and then reducing the nitro group.

As the compound represented by the formula (5), the compounds described in JP-A-4-226162 can be used, and specifically, the following compounds are exemplified.

(B-3) Dye having a coumarin skeleton The dye having a coumarin skeleton is preferably a compound represented by the following formula (6-1) or a salt thereof.

In the above formula (6-1), A represents a coumarin skeleton which may have a substituent, X represents a sulfo group or a carboxy group, and n represents an integer of 1 to 3.

The dye having a coumarin skeleton is more preferably represented by the following formula (6-2).

In the above formula (6-2), the group R represents a hydrocarbon group having 1 to 10 carbon atoms, Q represents a sulfur atom, an oxygen atom and a nitrogen atom, and n represents an integer of 1 to 3.

The dye having a coumarin skeleton is particularly preferably represented by the following formula (6-3).

In the above formula (6-3), the group R represents a hydrocarbon group having 1 to 10 carbon atoms, and it is extremely preferable that each of the two groups R is an ethyl group.

The salts of the compounds represented by the above formulas (1) to (6-3) are salts formed with an inorganic cation or an organic cation. Examples of the inorganic cations include cations of alkali metals such as lithium, sodium, and potassium, and ammonium ions (NH ₄ ⁺ ). Examples of the organic cation include organic ammonium represented by the following formula (D).

In formula (D), Z ₁ to Z ₄ each independently represent a hydrogen atom, alkyl, hydroxyalkyl, or hydroxyalkoxyalkyl, and at least one of Z ₁ to Z ₄ is a group other than a hydrogen atom.

Specific examples of Z ₁ to Z ₄ include C ₁ -C ₆ alkyl such as methyl, ethyl, butyl, pentyl, and hexyl, preferably C ₁ -C ₄ alkyl; hydroxymethyl, 2-hydroxyethyl, 3-hydroxy. Hydroxy C ₁ -C ₆ alkyl such as propyl, 2-hydroxypropyl, 4-hydroxybutyl, 3-hydroxybutyl, and 2-hydroxybutyl, preferably hydroxy C ₁ -C ₄ alkyl; and hydroxyethoxymethyl, 2-hydroxy. Hydroxy C ₁ -C ₆ alkoxy C ₁ -C ₆ alkyl such as ethoxyethyl, 3-hydroxyethoxypropyl, 3-hydroxyethoxybutyl, and 2-hydroxyethoxybutyl, preferably hydroxy C ₁ -C ₄ alkoxy C ₁ -C. _4- alkyl etc. are mentioned.

More preferred among these inorganic cations and organic cations are sodium ion, potassium ion, lithium ion, monoethanol ammonium ion, diethanol ammonium ion, triethanol ammonium ion, monoisopropanol ammonium ion, diisopropanol ammonium ion, tri ion. Examples include isopropanol ammonium ion and cations such as ammonium. Among these, lithium ion, ammonium ion, and sodium ion are more preferable.

In addition, as the polarized light emitting dye that can be used in the above polarized light emitting element, for example,
C. I. Fluorescent Brighter 5,
C. I. Fluorescent Brighter 8,
C. I. Fluorescent Brighter 12,
C. I. Fluorescent Brighter 28,
C. I. Fluorescent Brighter 30,
C. I. Fluorescent Brighter 33,
C. I. Fluorescent Brighter 350,
C. I. Fluorescent Brighter 360,
C. I. Fluorescent Brighter 365,
Etc. These fluorescent dyes may be free acids or may be alkali metal salts (for example, Na salt, K salt, Li salt), ammonium salts or salts of amines.

A polarized light emitting device which emits polarized light can be obtained by orienting one of the above polarized light emitting dyes or a combination of two or more thereof. When two or more types of polarized light emitting dyes are used in the polarized light emitting device, it is possible to adjust various emission colors by adjusting the mixing ratio between the polarized light emitting dyes. For example, the polarized light emitted from the polarized light emitting element can be made white by adjusting the absolute values of the chromaticity a ^* value and b ^* value to be 5 or less. The chromaticity a ^* value and b ^* value are obtained according to JIS Z 8781-4:2013 based on the spectral distribution measured for the light emitted from the polarized light emitting element when the light is incident on the polarized light emitting element. Be done. The object color display method defined in JIS Z 8781-4:2013 corresponds to the object color display method defined by the International Commission on Illumination (abbreviation "CIE"). The measurement of the chromaticity a ^* value and b ^* value is usually performed by irradiating a measurement sample with natural light. However, in the specification and claims of the present application, a polarized light emitting device has a short wavelength such as an ultraviolet light region. The chromaticity a ^* value and b ^* value can be confirmed by irradiating the above-mentioned light and measuring the emitted light. The absolute value of a ^* of the emitted light is 5 or less, preferably 4 or less, more preferably 3 or less, further preferably 2 or less, particularly preferably 1 or less. The absolute value of b ^* of the emitted light is 5 or less, preferably 4 or less, more preferably 3 or less, further preferably 2 or less, and particularly preferably 1 or less. If the absolute values of the a ^* value and the b ^* value are independently 5 or less, they can be sensed as white by human eyes, and if both are 5 or less, they are sensed as more preferable white light emission. be able to. Since the emitted polarized light is white, it can be used as a natural light source such as sunlight, a light source for a paper white terminal, etc., and is easy to apply even if placed on a display using a color filter or the like. There is. Regarding the emission intensity, there is no problem in applying it to a display as long as it can sense that it is glowing. In particular, as features of the present application, it is important that the emitted light has a high degree of polarization and that the visible region has a high transmittance.

(Other dyes)
The polarized light emitting device includes a dye having at least one skeleton selected from the group consisting of a stilbene skeleton, a biphenyl skeleton, and a coumarin skeleton in its molecule, or a salt thereof, alone or in addition, and inhibits a polarized light emitting function. If necessary, one or more kinds of other organic dyes or other fluorescent dyes may be further included within the range not to be included for the purpose of color adjustment and the like. Other organic dyes are not particularly limited as long as they can produce the color (hue) of the polarized light emitting element or the emission color, but those having high dichroism are preferable, and the stilbene skeleton, the biphenyl skeleton, and the coumarin. Dyes having at least one skeleton selected from the group consisting of skeletons in the molecule have little influence on the polarization performance in the ultraviolet region. Examples of such other organic dyes include C.I. Eye. direct. Yellow 12, sea. Eye. direct. Yellow 28, sea. Eye. direct. Yellow 44, C.I. I. Direct Orange 26, C.I. I. Direct Orange 39, C.I. I. Direct Orange 71, C.I. I. Direct Orange 107, C.I. I. Direct Red2, C.I. I. Direct Red 31, C.I. I. Direct Red 79, C.I. I. Direct Red 81, C.I. I. Direct Red 247, C.I. I. Direct Blue 69, C.I. I. Direct Blue 78, C.I. I. Direct Green 80, and C.I. I. Direct Green 59 and the like can be mentioned. These organic dyes may be free acids, or may be alkali metal salts (for example, Na salt, K salt, Li salt), ammonium salts or salts of amines. In addition, as the other fluorescent dye, a generally disclosed fluorescent dye can also be used for the purpose of adjusting the emission color, and is not particularly limited.

When the other organic dye or the other fluorescent dye is used in combination, it is possible to select the dye to be mixed and adjust the mixing ratio and the like in order to adjust the desired color of the polarized light emitting element. Depending on the purpose of preparation, the mixing ratio of other organic dyes or other fluorescent dyes is not particularly limited, but the total amount of these other organic dyes or other fluorescent dyes relative to 100 parts by mass of the polarized luminescent pigment is It is preferably used in the range of 0.01 to 10 parts by mass.

The dyeing solution may further contain a dyeing aid, if necessary, in addition to the above dyes. Examples of the dyeing aid include sodium carbonate, sodium hydrogen carbonate, sodium chloride, sodium sulfate (Glauber's salt), anhydrous sodium sulfate, sodium tripolyphosphate and the like, and preferably sodium sulfate. The content of the dyeing aid can be arbitrarily adjusted by the dyeability of the dye used, the immersion time, the temperature of the dyeing solution, etc., but is preferably 0.0001 to 10 mass% in the dyeing solution, It is more preferably 0.0001 to 2% by mass.

After the dyeing step, an optional pre-washing step may be performed in order to remove the dyeing solution attached to the surface of the substrate in the dyeing step. By passing through the preliminary washing step, it is possible to prevent the dye remaining on the surface of the substrate from being transferred to the liquid to be treated next. In the preliminary cleaning step, water is generally used as the cleaning liquid. As for the cleaning method, it is preferable to immerse the dyed substrate in the cleaning liquid, and it is also possible to perform cleaning by applying the cleaning liquid to the substrate. The washing time is not particularly limited, but is preferably 1 to 300 seconds, more preferably 1 to 60 seconds. The temperature of the cleaning liquid in the preliminary cleaning step needs to be a temperature at which the material forming the substrate is not dissolved, and the cleaning treatment is generally performed at 5 to 40°C. It should be noted that the performance of the polarized light emitting device is not significantly affected even without the preliminary cleaning step, and thus the preliminary cleaning step can be omitted.

(Crosslinking process)
After the dyeing step or the preliminary washing step, the base material may contain a crosslinking agent. As a method of incorporating the crosslinking agent into the substrate, it is preferable to immerse the substrate in the treatment solution containing the crosslinking agent, while the treatment solution may be applied or applied to the substrate. As the crosslinking agent in the treatment solution, for example, a solution containing boric acid is used. The solvent in the treatment solution is not particularly limited, but water is preferable. The concentration of 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, more preferably 40 to 75°C. Further, the treatment time of this crosslinking step is preferably 30 seconds to 10 minutes, more preferably 1 to 6 minutes. Since the method for producing a polarized light emitting device according to the present invention includes this cross-linking step, the obtained polarizing device has a high degree of polarization of the emitted light and exhibits a high contrast as a display body. This is an excellent action which cannot be expected from the function of boric acid used for the purpose of improving water resistance or light transmission in the prior art. Further, in the crosslinking step, if necessary, a fixing treatment may be further performed with an aqueous solution containing a cationic polymer compound. By the fixing treatment, the dye can be fixed in the polarized light emitting device. At this time, as the cationic polymer compound, for example, cation, dicyanamide and formalin polymerization condensate as a dicyan system, dicyandiamide/diethylenetriamine polycondensate as a polyamine system, epichlorohydrin/dimethylamine addition polymer as a polycation system, dimethyl A diallylammonium chloride/dioxide ion copolymer, a diallylamine salt polymer, a dimethyldiallylammonium chloride polymer, an allylamine salt polymer, a dialkylaminoethyl acrylate quaternary salt polymer and the like are used.

(Stretching process)
After passing through the above crosslinking step, a stretching step is carried out. The stretching step is performed by uniaxially stretching the substrate in a fixed direction, and may be either a wet stretching method or a dry stretching method. The draw ratio is preferably 3 times or more, and more preferably 5 to 8 times.

In the wet stretching method, it is preferable to stretch the substrate in water, a water-soluble organic solvent or a mixed solution thereof. More preferably, the stretching treatment is performed while immersing the substrate in a solution containing at least one crosslinking agent. As the cross-linking agent, for example, boric acid in the cross-linking agent step can be used, and preferably the stretching treatment can be performed in the treatment solution used in the cross-linking 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 one stage or in multiple stages of two or more stages. The stretching treatment may be optionally performed before the dyeing step, and in this case, the orientation of the dye can be also performed at the time of dyeing.

In the dry stretching method, when the stretching heating medium is an air medium, it is preferable to stretch the substrate at a temperature of the air medium from room temperature to 180°C. Further, the humidity is preferably in the atmosphere of 20 to 95% RH. Examples of the method for heating the base material include, but are not limited to, inter-roll zone stretching method, roll heating stretching method, hot pressure stretching method, and infrared heating stretching method. The dry stretching step may be performed in one stage or in multiple stages of two or more stages.

(Washing process)
During the stretching step, the cross-linking agent may be precipitated or foreign matter may adhere to the surface of the base material, so that a cleaning step for cleaning the surface of the base material can be performed. The washing time is preferably 1 second to 5 minutes. As for the cleaning method, it is preferable to immerse the base material in the cleaning liquid, while the cleaning liquid may be applied to or applied to the base material to be cleaned. Water is preferable as the cleaning liquid. The cleaning treatment may be carried out in one step or in a multi-step treatment of two or more steps. The temperature of the washing solution in the washing step is not particularly limited, but is usually 5 to 50°C, preferably 10 to 40°C, and may be room temperature.

As the solvent of the solution or treatment liquid used in each step, in addition to the water, for example, dimethyl sulfoxide, N-methylpyrrolidone, methanol, ethanol, propanol, isopropyl alcohol, glycerin, ethylene glycol, propylene glycol, diethylene glycol, Examples thereof include alcohols such as triethylene glycol, tetraethylene glycol or trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. The solvent of the solution or treatment liquid is not limited to these, but most preferably water. Moreover, the solvent of these solutions or a processing liquid may be used individually by 1 type, and may use 2 or more types of mixture.

(Drying process)
After the washing step, a base material drying step is performed. The drying treatment can be carried out by natural drying, but in order to further improve the drying efficiency, it can be carried out by compression with a roll, removal of water on the surface with an air knife, a water-absorbing roll, or the like. It is also possible to do so. 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.

A polarized light emitting element can be manufactured by the above method, and a polarized light emitting plate of the present invention can be obtained by providing a transparent protective layer on this. The polarized light emitting element is an element that exhibits polarized light emission and has a polarizing function in the ultraviolet region, that is, an element that exhibits absorption anisotropy. In particular, a compound having at least one skeleton selected from the group consisting of a stilbene skeleton, a biphenyl skeleton and a coumarin skeleton, which can be the compound (b) exemplified in the present application, in the molecule does not decompose even under a high temperature or high humidity heat environment, Has high durability.

The polarized light emitting element is irradiated with light in the invisible light region such as the ultraviolet light region, absorbs the light in the ultraviolet light region, and uses the energy to emit polarized light in the visible light region. Since the light emitted by the polarized light emitting element is polarized light in the visible light region, when observing the polarized light emitting element through a general polarizing plate having a polarizing function for light in the visible light region, By changing the angle of the axis of a general polarizing plate having a polarizing function in the visible light region, it is possible to visually recognize the light that has emitted polarized light. That is, the light of the strong emission axis and the light of the non-emission axis (or the axis of extremely weak emission) can be visually recognized. The polarization degree of the polarized light emitted by the polarized light emitting element is 70% or more, preferably 80% or more, more preferably 90% or more, further preferably 95% or more, particularly preferably 99% or more. Further, it is preferable that the polarized light emitting element transmits light in the visible light region without absorbing it. If the transmittance of light in the visible light region of the polarized light emitting element is 60% or more in the transmittance corrected for the visibility, a liquid crystal display having a significantly high transmission can be obtained, which is significantly more dramatic than the conventional liquid crystal display. Is preferably 70% or more, more preferably 80% or more, further preferably 85% or more, particularly preferably 90% or more. Since the polarized light-emitting device obtained in the present invention has a high degree of polarization, it not only has high transparency in the visible light region in the non-emission state, but also emits strong axial light even in the light emitting state. Since it is possible to absorb uniaxial light by visually recognizing it through a general polarizing plate, it is preferable to obtain a polarized light emitting element having a high transparency on the axis that does not emit light (or the axis on which light emission is extremely weak).

(Polarized light emitting plate)
A polarized light emitting plate including a polarized light emitting element is also included in the present application. The polarized light emitting plate can be achieved by having a transparent protective layer or the like for the polarized light emitting element. The transparent protective layer is used to improve the water resistance and handleability of the polarized light emitting device, and the transparent protective layer does not affect the polarization function of the polarized light emitting device.

The transparent protective layer is preferably a transparent protective layer having excellent optical transparency and mechanical strength. Further, the transparent protective layer is preferably a film having a layer shape capable of maintaining the shape of the polarized light emitting element, and is a plastic film excellent in thermal stability, moisture shielding property, etc. in addition to transparency and mechanical strength. Preferably there is. Examples of the material for forming such a protective film include a cellulose acetate film, an acrylic film, a fluorine film such as a tetrafluoroethylene/hexafluoropropylene copolymer, or a polyester resin or a polyolefin resin. Alternatively, a film made of a polyamide resin may be used, and preferably a triacetyl cellulose (TAC) film or a cycloolefin film is used. The thickness of the transparent protective layer is preferably 1 μm to 200 μm, more preferably 10 μm to 150 μm, and particularly preferably 40 μm to 100 μm. The method for producing the polarized light emitting plate is not particularly limited, but it can be produced, for example, by stacking a transparent protective layer on a polarized light emitting element and laminating it with a known formulation.

The polarized light emitting plate may further include an adhesive layer for bonding the transparent protective layer and the polarized light emitting element between the transparent protective layer and the polarized light emitting element. The adhesive constituting the adhesive layer is not particularly limited, and examples thereof include polyvinyl alcohol-based adhesive, urethane emulsion-based adhesive, acrylic adhesive, polyester-isocyanate-based adhesive, and the like. A polyvinyl alcohol adhesive is used. The above-mentioned polarized light emitting plate can be produced by bonding the transparent protective layer and the polarized light emitting element with an adhesive and then performing drying or heat treatment at an appropriate temperature.

Further, the polarized light emitting plate may appropriately include various known functional layers such as an antireflection layer, an antiglare layer, and a further transparent protective layer on the exposed surface of the transparent protective layer. When producing a layer having such various functionalities, a method of coating a material having various functionalities on the exposed surface of the transparent protective layer is preferable, and various functional layers or films are bonded via an adhesive or a pressure-sensitive adhesive. It is also possible to attach it to the exposed surface of the transparent protective layer.

Examples of the further transparent protective layer include hard coat layers such as acrylic and polysiloxane bases, and urethane based protective layers. Further, an antireflection layer may be provided on the exposed transparent protective layer in order to further improve the single transmittance. The antireflection layer can be formed, for example, by subjecting a material such as silicon dioxide or titanium oxide to vapor deposition or sputtering treatment on the transparent protective layer, or by applying a fluorine-based material thinly on the transparent protective layer.

With the above method, it is possible to provide a preferred embodiment of the polarized light emitting element or the polarized light emitting plate using the same.

In the present application, it is one of preferred modes that the compound (a) further has luminescence anisotropy. Since the compound (a) has the luminescence anisotropy, the luminescence can be emitted only by uniaxially polarized light, and the light in the luminescence axis coincides with the absorption and luminescence axis of the compound (b). The light emitted by the compound (a) can substantially provide the compound (b) with light with high efficiency. The emission anisotropy can be exhibited by having the absorption anisotropy of the compound (a), that is, the absorption anisotropy of the compound (a), like the compound (b). The absorption anisotropy is generally expressed as a dichroic ratio, and the orientation degree of the compound (a) can also be calculated from the dichroic ratio. The dichroic ratio is a ratio between the absorption amount of the axis having the strongest absorption and the absorption amount of the axis having the lowest absorption. If the dichroic ratio is 2 or more, linearly polarized light can be emitted, and therefore the upper limit is particularly high. Although not limited, a dichroic ratio of about 70 is sufficiently high. The dichroic ratio is preferably 5 or more, preferably 10 or more, more preferably 20 or more, and further preferably 30 or more. The degree of orientation is a numerical value given by the above-mentioned formula (I), and when it is 0.25 or more and 1.00 or less, the polarized light emitting device or the display device of the present application can be provided more efficiently, but it is particularly preferable. It is preferably 0.50 or more and 0.98 or less, more preferably 0.75 or more and 0.96 or less, and further preferably 0.85 or more and 0.96 or less.

The polarized light emitting element or the polarized light emitting plate can be used not only alone but also in a general display, particularly a display device such as a liquid crystal display. Furthermore, it is preferable to use a general polarizing plate and a polarized light emitting device of the present application, or a polarized light emitting plate thereof, because polarization control by absorption and polarization control by light emission can be performed.

The polarized light emitting device of the present application and the polarized light emitting plate using the same can be effectively utilized as a highly efficient polarized backlight for liquid crystal displays, and are highly transparent because they have higher transparency in the visible region than conventional polarized light. It can be used for a see-through display capable of emitting light and a polarized light source having transparency. Furthermore, it can be utilized as an element, a light source, or a display device that can efficiently emit natural light of ultraviolet light of 300 nm or more as polarized light in the visible region. That is, the polarized light emitting element of the present application and the polarized light emitting plate using the same can efficiently emit polarized light outdoors. Alternatively, by using a polarized light emitting element as in the present application, it is possible to provide a polarized light emitting plate having high light resistance and a display device using the same. In general, it is known that polymers and dyes are deteriorated by a certain amount of light, for example, ultraviolet rays. However, in the present invention, the light energy for the deterioration is used for light emission, so that the energy that causes the deterioration is Can be substantially suppressed, and can impart high durability to the polarized light emitting element or the display device itself, and can be suitably used for a display device particularly required to have high light resistance, for example, a display device such as an outdoor liquid crystal display. A polarized light emitting device, a polarized light emitting plate, or an optical device is provided.

Hereinafter, the present invention will be described in more detail with reference to Examples, but these are merely examples and do not limit the present invention in any way. Further, “%” and “part” described below are based on mass unless otherwise specified. In each structural formula of the compounds used in each of the examples and comparative examples, the acidic functional group such as a sulfo group is described in the form of a free acid.

[Example 1]
(Synthesis example 1)
35.2 parts of commercially available 4-amino-4′-nitrostilbene-2,2′-disulfonic acid was added to 300 parts of water and stirred, and the pH was adjusted to 0.5 with 35% hydrochloric acid. To the resulting solution was added 10.9 parts of a 40% sodium nitrite aqueous solution, and the mixture was stirred at 10° C. for 1 hour. Then, 17.2 parts of 6-aminonaphthalene-2-sulfonic acid was added, and a 15% sodium carbonate aqueous solution was added. After the pH was adjusted to 4.0, the mixture was stirred for 4 hours. 60 parts of sodium chloride was added to the obtained reaction solution, the precipitated solid was separated by filtration, further washed with 100 parts of acetone, and dried to obtain 62.3 parts of the compound represented by the following formula (7).

62.3 parts of the formula (7) obtained above was added to 300 parts of water and stirred, and the pH was adjusted to 10.0 using a 25% aqueous sodium hydroxide solution. 20 parts of 28% ammonia water and 9.0 parts of copper sulfate pentahydrate were added to the obtained solution, and the mixture was stirred at 90° C. for 2 hours. 25 parts of sodium chloride was added to the obtained reaction liquid, the precipitated solid was separated by filtration, and further washed with 100 parts of acetone to obtain 40.0 parts of a wet cake of the compound of the following formula (8). The wet cake was dried with a hot air dryer at 80° C. to obtain 20.0 parts of a compound (λmax: 376 nm) of the following formula (8).

(Production of Polarized Light Emitting Element A)
A polyvinyl alcohol film (VF-PS#7500 manufactured by Kuraray Co., Ltd.) having a thickness of 75 μm was immersed in warm water at 40° C. for 3 minutes to swell the film. The film obtained by swelling, 1.0 part by weight of the compound (b) described in Compound Example 5-1 and an aqueous solution of 4,4′-bis-(sulfostyryl)biphenyl disodium (BASF Corporation Tinopal NFW Liquid). In a 45° C. aqueous solution containing 0.3 part by weight of the compound (8) obtained in Synthesis Example 1, 1.0 part by weight of Glauber's salt and 1500 parts by weight of water, 2-(2) as the compound (a) was obtained. -Pyridylamino)ethylamine dihydrochloride (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) (0.3 parts by weight) was added, and the mixture was immersed for 4 minutes to contain it. The obtained film was stretched 5 times at 50° C. in a 3% aqueous solution of boric acid for 5 minutes. The film obtained by stretching was washed with water at room temperature for 20 seconds while maintaining the tension, and then dried to obtain a polarized light emitting device A. In the Order Parameter calculated from the above formula (I) of the polarized light emitting device A, the 318 nm Order Parameter based on the compound (a) is 0.72, and the 377 nm Order Parameter based on the compound (b) group is 0.90. Met. The maximum absorption wavelength of the compound (a) was 318 nm, the emission of the highest wavelength was 405 nm, and the emission band was 405 nm±30 nm. In addition, the compound (b) group had a characteristic that the wavelength of maximum absorption was 377 nm and that it emitted light of the highest wavelength, that is, emitted polarized light having a maximum emission wavelength of 465 nm.

Next, a triacetyl cellulose film containing no ultraviolet absorber (ZRD-60 manufactured by Fuji Film Co., Ltd.) was treated with a 1.5 N aqueous sodium hydroxide solution at 35° C. for 10 minutes, washed with water, and then at 70° C. It was dried for 10 minutes. An adhesive consisting of 100 parts by weight of water and 4 parts by weight of polyvinyl alcohol resin (NH-26 manufactured by Nihon Vineyard Bipovar Co., Ltd.) was applied to both surfaces of the polarized light emitting device A obtained by the alkali treatment to obtain the triacetyl cellulose film. After that, the film was dried at 70° C. for 10 minutes to obtain a polarized light emitting plate A having the same optical performance as the polarized light emitting element A. When the obtained polarized light emitting plate A was irradiated with ultraviolet rays using a 375 nm hand light type black light (“PW-UV943H-04” manufactured by Nichia Corporation), white light was emitted and a polarizing plate was further formed. As a result of confirming the emission through the above, it was confirmed that white polarized light was emitted in the stretching axis direction when the polarized light emitting device A was processed, while it was confirmed that polarized light was not emitted in the non-stretching axis. That is, the polarized light emitting plate A was an element that emits linearly polarized light. The obtained polarized light emitting plate A was attached to glass to give a measurement sample. As shown in Table 2, the emission band of the polarized light emitting plate A had a polarized emission wavelength in the entire visible region.

[Example 2]
(Synthesis example 2)
After commercially available 4-diamino-stilbene-2,2'-disulfonic acid (35.2 parts) was added to 300 parts of water and stirred, and 35 parts of 4-methoxy-benzoyl chloride was added little by little over about 1 hour. The mixture was stirred and reacted at 60° C. for 1 hour. After completion of the reaction, the mixture was allowed to cool to room temperature, the solid content was filtered, and dried at 70° C. to obtain 44.5 parts of the compound (a) of the present invention represented by the following formula (9).

(Synthesis example 3)
3.3 parts of commercially available 3-(2-benzimidazolyl)-7-(diethylamino)coumarin was added to a mixed solution of 45 parts of 98% sulfuric acid and 10 parts of 30% fuming sulfuric acid, and the mixture was stirred at 25°C for 24 hours. The obtained reaction solution was added to 300 parts of water, the precipitated solid was separated by filtration, and further washed with 100 parts of acetone to obtain 10.0 parts of a wet cake. The wet cake was dried with a hot air dryer at 80° C. to synthesize 3.0 parts of a water-soluble coumarin-based dichroic dye corresponding to the compound (b) of the present invention represented by the following formula (10).

(Production of Polarized Light Emitting Element B)
A polyvinyl alcohol film (VF-PS#7500 manufactured by Kuraray Co., Ltd.) having a thickness of 75 μm was immersed in warm water at 40° C. for 3 minutes to swell the film. The film obtained by swelling was used as a compound (a), 0.9 parts by weight of the compound of the formula (9) obtained in Synthesis Example 2, and as a compound (b), the compound of Formula (10) obtained in Synthesis Example 3. The compound was dipped for 4 minutes in an aqueous solution containing 0.7 parts by weight of Glauber's salt, 1.0 part by weight of Glauber's salt, and 1,500 parts by weight of water for 4 minutes. The obtained film was stretched 5 times at 50° C. in a 3% aqueous solution of boric acid for 5 minutes. The film obtained by stretching was washed with water at room temperature for 20 seconds while keeping the tension, and then dried to obtain a polarized light emitting device B. In the Order Parameter calculated from the above formula (I) of the polarized light emitting device B, the Order Parameter of 348 nm based on the formula (9) which is the compound (a) is 0.85 and the formula (10) which is the compound (b). ), the 450 nm Order Parameter was 0.78. The maximum absorption wavelength based on the formula (9) which is the compound (a) is 348 nm, the absorption band thereof is 310 to 390 nm, and the highest emission wavelength is 426 nm, and the emission band thereof is 380 to 500 nm. Met. Further, the maximum absorption wavelength based on the formula (10) which is the compound (b) is 450 nm, the absorption band of light is 360 to 500 nm, and the emission of the highest wavelength, that is, the maximum emission wavelength is 512 nm. It had the property of emitting polarized light.

Next, a triacetyl cellulose film containing no ultraviolet absorber (ZRD-60 manufactured by Fuji Film Co., Ltd.) was treated with a 1.5 N aqueous sodium hydroxide solution at 35° C. for 10 minutes, washed with water, and then at 70° C. It was dried for 10 minutes. An adhesive consisting of 100 parts by weight of water and 4 parts by weight of polyvinyl alcohol resin (NH-26 manufactured by Nihon Vineyard Bipovar Co., Ltd.) was used on both surfaces of the polarized light emitting device B obtained by the alkali treatment to obtain the triacetyl cellulose film. After that, it was laminated for 10 minutes and dried at 70° C. for 10 minutes to obtain a polarized light emitting plate B having the same optical characteristics as the polarized light emitting element B. When the polarized light emitting plate B was irradiated with ultraviolet rays using a 375 nm hand-light type black light (“PW-UV943H-04” manufactured by Nichia Corporation), the light emission was confirmed through a polarizing plate. It was confirmed that polarized light emission could be confirmed in the stretching axis direction when the light-emitting element B was processed, while polarized light emission was not observed in the non-stretching axis. That is, the polarized light emitting plate B was an element that emits linearly polarized light. The obtained polarized light emitting plate B was attached to glass to give a measurement sample. The emission band of the polarized light emitting plate B had the optical characteristics shown in Table 2 for emitting polarized light.

[Example 3]
(Synthesis example 4)
3.3 parts of commercially available 3-(2-benzimidazolyl)-7-(diethylamino)coumarin was added to a mixed solution of 45 parts of 98% sulfuric acid and 10 parts of 30% fuming sulfuric acid, and the mixture was stirred at 25°C for 24 hours. The obtained reaction solution was added to 300 parts of water, the precipitated solid was separated by filtration, and further washed with 100 parts of acetone to obtain 10.0 parts of a wet cake. The wet cake was dried with a hot air drier at 80° C. to synthesize 3.0 parts of the water-soluble coumarin-based dichroic dye represented by the following formula (11) according to the present invention.

(Production of Polarized Light Emitting Element C)
A polyvinyl alcohol film (VF-PS#7500 manufactured by Kuraray Co., Ltd.) having a thickness of 75 μm was immersed in warm water at 40° C. for 3 minutes to swell the film. The film obtained by swelling was used as the compound (a), 0.9 parts by weight of the compound of the formula (9) obtained in Synthesis Example 2, and the compound (b) of the formula (11) obtained in Synthesis Example 4. The compound was immersed for 4 minutes in an aqueous solution containing 0.85 part by weight of Glauber's salt, 1.0 part by weight of Glauber's salt, and 1,500 parts by weight of water for 4 minutes. The obtained film was stretched 5 times at 50° C. in a 3% aqueous solution of boric acid for 5 minutes. The film obtained by stretching was washed with water at room temperature for 20 seconds while keeping the tension, and then dried to obtain a polarized light emitting device C. In the Order Parameter calculated from the above formula (I) of the polarized light emitting device C, the Order Parameter of 348 nm based on the formula (9) which is the compound (a) is 0.85, and the formula (11) which is the compound (b). ), the 447 nm Order Parameter was 0.75. The maximum absorption wavelength based on the formula (9) which is the compound (a) is 348 nm, the absorption band thereof is 310 to 390 nm, and the highest emission wavelength is 426 nm, and the emission band thereof is 380 to 500 nm. Met. Further, the maximum absorption wavelength based on the formula (11) which is the compound (b) is 447 nm, the absorption band of light is 360 to 500 nm, and the emission of the highest wavelength, that is, the maximum emission wavelength is 510 nm. It had the property of emitting polarized light.

Next, a triacetyl cellulose film containing no ultraviolet absorber (ZRD-60 manufactured by Fuji Film Co., Ltd.) was treated with a 1.5 N aqueous sodium hydroxide solution at 35° C. for 10 minutes, washed with water, and then at 70° C. It was dried for 10 minutes. An adhesive consisting of 100 parts by weight of water and 4 parts by weight of polyvinyl alcohol resin (NH-26 manufactured by Nihon Vineyard Bipovar Co., Ltd.) on both surfaces of the polarized light emitting device C obtained by the alkali treatment was obtained. After that, the film was dried at 70° C. for 10 minutes to obtain a polarized light emitting plate C having the same optical characteristics as the polarized light emitting element C. The polarized light emitting plate C thus obtained was confirmed to emit light through a polarizing plate while irradiating it with ultraviolet rays using a 375 nm hand light type black light (“PW-UV943H-04” manufactured by Nichia Corporation). It was confirmed that polarized light emission could be confirmed in the stretching axis direction when the light-emitting element C was processed, while polarized light emission was not observed in the non-stretching axis direction. That is, the polarized light emitting plate C was an element that emits linearly polarized light. The obtained polarized light emitting plate was attached to glass to give a measurement sample. The emission band of the polarized light emitting plate C had the optical characteristics of emitting polarized light shown in Table 2.

[Comparative Example 1]
A polyvinyl alcohol film (VF-PS#7500 manufactured by Kuraray Co., Ltd.) having a thickness of 75 μm was immersed in warm water at 40° C. for 3 minutes to swell the film. The film obtained by swelling was 1.0 part by weight of 4,4′-bis-(sulfostyryl)biphenyl disodium aqueous solution (Tinopal NFW Liquid manufactured by BASF) described in Compound Example 5-1. The obtained compound (8) was immersed for 4 minutes in an aqueous solution containing 0.3 part by weight of Glauber's salt, 1.0 part by weight of Glauber's salt, and 1,500 parts by weight of water, for 4 minutes. The obtained film was stretched 5 times at 50° C. in a 3% aqueous solution of boric acid for 5 minutes. The film obtained by stretching was washed with water at room temperature for 20 seconds while maintaining the tension, and then dried to obtain a measurement sample of Comparative Example 1. The Order Parameter calculated from the above formula (I) of the system of Comparative Example 1 is 0.91, the wavelength of maximum absorption is 377 nm, its absorption band is 350 nm to 410 nm, and the maximum emission wavelength is 465 nm. A polarized light emitting dye having Further, it was found that the obtained measurement sample emitted linearly polarized light.

(Comparative example 2)
The film obtained by swelling in Example 2 was used as the compound (a) without using the compound of the formula (9) obtained in Synthesis Example 2, but with the compound (b) obtained in Synthesis Example 3 Comparative Example 2 was repeated in the same manner except that the compound of (10) was dipped in an aqueous solution of 0.7 parts by weight, 1.0 part by weight of Glauber's salt, and 1500 parts by weight of water at 45° C. for 4 minutes. A measurement sample was prepared. The Order Parameter at 447 nm based on the compound (b), formula (10), was 0.54.

(Comparative example 3)
The film obtained by swelling in Example 2 was used as the compound (a) without using the compound of the formula (9) obtained in Synthesis Example 2, but the compound (b) having the formula of Synthesis Example 4 obtained. Comparative Example 2 was repeated except that the compound of (11) was dipped in an aqueous solution containing 0.85 parts by weight of Glauber's salt, 1.0 parts by weight of Glauber's salt, and 1500 parts by weight of water at 45° C. for 4 minutes. A measurement sample was prepared. The Order Parameter at 447 nm based on the compound (b), formula (11), was 0.52.

Each obtained measurement sample was evaluated as follows.

[Evaluation]
(H-1) Single transmittance Ts, parallel transmittance Tp, and orthogonal transmittance Tc
The single-piece transmittance Ts, the parallel transmittance Tp, and the orthogonal transmittance Tc of each measurement sample were measured using a spectrophotometer (“U-4100” manufactured by Hitachi, Ltd.). Here, the single-piece transmittance Ts is the transmittance of each wavelength when one measurement sample is measured. The parallel transmittance Tp is a spectral transmittance of each wavelength measured by overlapping two measurement samples so that their absorption axis directions are parallel to each other. The orthogonal transmittance Tc is a spectral transmittance measured by overlapping two measurement samples so that their absorption axes are orthogonal to each other. The measurement was performed over a wavelength range of 220 to 780 nm.

(H-2) Degree of polarization ρ
The polarization degree ρ of each measurement sample was obtained by substituting the parallel transmittance Tp and the orthogonal transmittance Tc into the following formula (II).

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

(H-3) Single-element transmittance Ys corrected for luminosity and polarization degree ρy corrected for luminosity
The single transmittance Ys (%) of each measurement sample is JIS Z 8722 for the single transmittance Ts (%) obtained at every predetermined wavelength interval dλ (here, 5 nm) in the wavelength region of 400 to 700 nm in the visible region. : 2009, the transmittance is corrected to the luminosity factor. Specifically, it was calculated by substituting the single transmittance Ts (%) into the formula (V). In the formula (V) below, Pλ represents the spectral distribution of standard light (C light source), and yλ represents the 2-degree visual field color matching function. As the visibility-corrected polarization degree ρy (%) in each sample, a value obtained by calculation by an instrument when measured by U-4100 was used.

(Formula 3)

Correction of 375 nm simple substance transmittance (Ts 375 (%)), 375 nm polarization degree (ρ 375 (%)), and visual sensitivity in each of the measurement samples obtained in Examples 1 to 3 and Comparative Examples 1 to 3. Table 1 shows the transmissivity (Ys (%)) and the polarization degree (ρy (%)) corrected to the luminosity factor. The polarization function in the ultraviolet range and the visible range in each of the obtained measurement samples can be known.

[Table 1]

As shown in Table 1, it can be seen that the measurement samples shown in Examples 1 to 3 have high visibility-corrected single transmittance (Ys). In addition, from the values of the single transmittance (Ts 375) and the degree of polarization (ρ 375) at 375 nm, the compound of the present application has a function of converting light into polarized light at 375 nm and absorbs a little more than 50% of the irradiated light. It can be seen that the results showing that the action is being taken are obtained. On the other hand, the polarization degree at 375 nm of Comparative Examples 2 and 3 was significantly lower than that of Examples 2 and 3.

(H-4) Measurement of polarization of emitted light As a light source, an ultraviolet LED (M340L4 manufactured by THORLABOS) that has the strongest output at 348 nm and emits light in the range of 335 to 380 nm is used, and the light source transmits and is visible. A cut filter ("IUV-340" manufactured by Isuzu Seiko Glass Co., Ltd.) was installed to cut visible light. Then, a measurement sample obtained in each Example or Comparative Example, a polarizing plate having polarized light in the visible region and ultraviolet (“SKN-18043P” manufactured by Polatechno Co., thickness 180 μm, Ys 43%) were sequentially installed. Then, the polarized light emitted from the measurement sample was measured using a spectroradiometer (“USR-40” manufactured by Ushio Inc.). That is, the measurement was performed by arranging the light from the light source so that the light passed through the ultraviolet ray transmitting/visible cut filter, the measurement sample, and the polarizing plate having polarized light in the visible region and ultraviolet ray in this order, and was incident on the spectroradiometer. At that time, Lw (weak emission axis) is measured as the spectral emission amount of each wavelength measured by overlapping so that the axis of maximum emission of the measurement sample and the absorption axis direction of the ultraviolet/visible polarizing plate are parallel to each other. Spectral emission of each wavelength measured by superimposing so that the axis of maximum luminescence of the sample and the absorption axis direction of a polarizing plate (“SKN-18043P” manufactured by Polatechno Co., Ltd.) having polarization in the visible region and ultraviolet are orthogonal to each other. Lw and Ls were measured with the amount as Ls (strong emission axis). Light emission polarized in the visible range of 400 nm to 700 nm is confirmed by confirming the amount of energy of light emitted in the visible range when the absorption axes of the measurement sample and a general polarizing plate are parallel and when they are orthogonal. The light was evaluated.

Table 2 shows Ls and Lw at each wavelength of 460 nm, 550 nm, 610 nm, and 670 nm of the measurement samples obtained in Examples 1 to 3 and Comparative Examples 1 to 3.

[Table 2]

As shown in Table 2, since Example 1 has higher Ls than Comparative Example 1 at each wavelength of 460 nm, 550 nm and 610 nm, it can be seen that the emission luminance is increased and the visibility is improved. Further, in Example 1, the difference between Ls and Lw is larger at 460 nm, 550 nm and 610 nm than in Comparative Example 1, and the contrast in polarized light emission, that is, the obtained polarized light emitting element, and the light emission of the polarized light emitting plate obtained therefrom. It can be seen that the polarization degree of the light is increased. On the other hand, also in Example 2 and Example 3, Ls of Comparative Examples 2 and 3 was high at each wavelength of 460 nm and 550 nm, and further, the difference between Ls and Lw was large. From this, it is important for the compound (a) to be contained in order to improve the polarized brightness, and the compound (a) is oriented so that the compound (b) originally has polarized light emission. It was shown that a polarized light emitting device which emits polarized light having a higher brightness and a higher degree of polarization than the high contrast and the degree of polarization of the emitted polarized light, that is, high contrast can be obtained. From the above, according to the present application, the polarized light emitting device and the polarized light emitting plate obtained thereby can increase the emission brightness and can also increase the contrast of the obtained polarized light.

From the above, the polarized light emitting device and the polarized light emitting plate of the present application can be used while exhibiting a high polarization effect at an emission wavelength by being used in an optical device such as a polarized light source, a lens or a display device, particularly in a liquid crystal display device. It is possible to exert a bright light emitting effect and to impart high durability. According to the present invention, natural light can be efficiently used for light emission. In addition, the light that the dye has not absorbed so far can be used to emit light in the visible region with high efficiency, and light emission can be imparted with high efficiency, while having a high transmittance in the visible light region, It is possible to provide a polarized light emitting device having high emission brightness. Further, it is generally known that a certain amount of light such as ultraviolet rays deteriorates a polymer or a dye. However, in the present invention, the light energy for the deterioration is used for light emission in reverse, which causes the deterioration. The polarized light-emitting element that can be suitably used for a display device that can have high durability, and that is particularly required to have high light resistance, for example, a display device such as a liquid crystal display, Or to provide an optical device. Further, since a film which is transparent and emits polarized light by ultraviolet rays can be obtained, the present invention can be applied by making use of various advantages such as security and design.

Claims (10)

Near-ultraviolet to near-ultraviolet light in the visible range is absorbed, the function of emitting light by using the absorbed light, and the function of emitting polarized light having a wavelength in the visible range using the emitted light, A polarized light-emitting device having. The polarized light emitting element according to claim 1, wherein the polarized light emitting element absorbs light in a wavelength range of at least 300 to 360 nm and emits light having an emission wavelength in a wavelength range of at least 400 to 700 nm. The polarized light according to claim 1 or 2, wherein the polarized light emitting element contains a compound (a) that absorbs light in a wavelength range of at least 300 to 360 nm and emits light having an emission wavelength in a wavelength range of at least 350 to 430 nm. Light emitting element. 4. The polarized light emitting device according to claim 1, wherein the polarized light emitting device contains a compound (b) which absorbs light in a wavelength range of at least 350 to 430 nm and emits light having an emission wavelength in a wavelength range of at least 400 to 700 nm. The polarized light-emitting device according to item. The polarized light emitting element according to claim 1, wherein the light emitted by the polarized light emitting element is linearly polarized light. The polarized light emitting device according to claim 4 or 5, wherein the compound (b) is a compound that exhibits absorption anisotropy when oriented. The polarized light emitting device according to any one of claims 3 to 6, wherein the compound (a) is a compound that exhibits absorption anisotropy when oriented. The compound (b) has at least one skeleton selected from the group consisting of a stilbene skeleton, a biphenyl skeleton, and a coumarin skeleton in the molecule, at least in a molecule thereof. Polarized light emitting element. A polarized light emitting plate comprising the polarized light emitting element according to claim 1. A display device comprising the polarized light emitting element according to claim 1 or the polarized light emitting plate according to claim 9.