JP7429105B2 - Polarized light emitting plate and optical device equipped with the same - Google Patents

Description

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

BACKGROUND ART A polarizing plate having a light transmitting or blocking function is a basic component of a display device such as a liquid crystal display (LCD), along with a liquid crystal having a light switching function. The field of application of LCDs is expanding from small devices such as calculators and watches that were first commercially available to notebook computers, word processors, liquid crystal projectors, liquid crystal televisions, car navigation systems, indoor and outdoor information display devices, and measuring instruments. Polarizing plates can also be applied to lenses with a polarizing function, and have been applied to sunglasses with improved visibility and, in recent years, polarized glasses compatible with 3D TVs, etc. It is being applied to familiar information devices such as terminals, and some are even being put into practical use. Polarizing plates have a wide variety of uses, and the environments in which they are used range from low to high temperatures, low to high humidity, and low to high light levels. Polarizing plates are in demand.

In general, the polarizing film constituting the polarizing plate is manufactured by dyeing or containing iodine or dichroic dye and stretching and orienting a film of polyvinyl alcohol or its derivatives, or by dehydrochlorinating or It is produced by dehydrating a polyvinyl alcohol film to produce polyene and orienting it. Polarizing plates made of such conventional polarizing films use dichroic dyes that absorb in the visible region, so their transmittance decreases. For example, the transmittance of a typical commercially available polarizing plate is 35 to 45%.

In addition, regarding the "degree of polarization", which is one of the indicators of the polarization performance of a polarizing plate, in order to obtain a 100% degree of polarization, if there are x-axis and y-axis lights on a two-dimensional plane, one of the It is necessary to absorb only the axial light. Therefore, general polarizing plates use iodine or dichroic dyes to absorb only light along one axis. If only the light along one axis is absorbed, the amount of light transmitted through the polarizing plate will be 50% or less in principle compared to 100% of the amount of incident light. Furthermore, the transmittance actually decreases further than 50% due to a decrease in the degree of polarization due to poor orientation of iodine and dichroic dyes, light loss due to the film medium, and interfacial reflection on the film surface. However, the transmittance of conventional polarizing plates is as low as 35 to 45%. To address this problem of low transmittance of general polarizing plates, which is 35 to 45%, we have developed a polarizing plate for ultraviolet rays as a technology that provides a polarizing function while maintaining a certain degree of transmittance in the visible range. The 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 that exhibits a polarizing function only for light around 410 nm. In other words, it does not impart a polarizing function to light in the visible range.

If a polarizing plate with a low transmittance of light in the visible range or a polarizing plate with a low degree of polarization is used in a display, for example, the brightness and contrast of the entire display will decrease. In order to solve this problem, methods of obtaining polarized light without using conventional polarizing plates are being researched, and as one method, devices that emit polarized light (polarized light emitting devices) are described in Patent Documents 2 to 6. has been done.

WO2005/01527 Japanese Patent Application Publication No. 2008-224854 Patent No. 5849255 Patent No. 5713360 U.S. Patent No. 3,276,316 Japanese Patent Application Publication No. 4-226162

However, the polarized light emitting elements described in Patent Documents 2 to 4 are expensive to manufacture because they use special metals, such as rare metals such as lanthanoids such as europium, and are difficult to manufacture in large quantities. It is not suitable for Furthermore, since these polarized light emitting elements have a low degree of polarization, it is difficult to use them in displays, and it is also difficult to obtain emitted light that is linearly polarized light. In addition, because it can only emit circularly polarized light at a specific wavelength, its uses are limited, and even if it were used in displays, it would have low brightness and contrast, making it difficult to design liquid crystal cells. Therefore, we have created a new polarizing plate that exhibits polarized light emission, has a high degree of polarized light emission, has high transmittance in the visible light range, and can be applied to liquid crystal displays that require durability in harsh environments. There is a strong desire to develop materials for this purpose. On the other hand, patents related to elements that emit polarized light by irradiating ultraviolet rays are disclosed, such as Patent Documents 5 and 6. However, the degree of polarization and brightness of the light-emitting element are extremely low, and the so-called contrast of each axis of polarized light is low, so it is not sufficient for use in displays, etc., and in addition, its light resistance is low.

The present invention provides an element capable of emitting polarized light by utilizing absorption of light, in which the wavelength of the absorbed light is different from the wavelength of the polarized light emitted, and the wavelength range is at least 400 to 700 nm. By creating a polarized light emitting plate that includes a polarized light emitting element that emits light polarized to It is an object of the present invention to provide a polarized light emitting plate with different transmission and light emission, and a display device thereof.

As a result of intensive research to achieve this objective, the present inventors have discovered that an element capable of emitting polarized light by utilizing absorption of light has the following characteristics: a polarized light emitting element that emits polarized light in a wavelength range of at least 400 to 700 nm and that is different from the wavelength of the polarized light emitting element; and a layer that can reflect light in the absorption wavelength range of the polarized light emitting element. We discovered that the plate emits high-intensity polarized light while having a high degree of polarization, and we also newly discovered that absorption, transmission, and light emission differ depending on the wavelength.

That is, the present invention relates to 1) to 11).
1)
In an element capable of emitting polarized light by utilizing absorption of light, the wavelength of the light absorbed by the element is different from the wavelength of the light emitted as polarized light, and the light polarized in a wavelength range of at least 400 to 700 nm is used. A polarized light emitting plate comprising: a polarized light emitting element that emits light; and a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element.
2)
In the polarized light emitting element, the wavelength range of light to be absorbed for use in polarized light emission is in the near ultraviolet to near ultraviolet visible range, and the layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element, The polarizing light-emitting plate according to 1), which is a layer capable of reflecting light in the near-ultraviolet region, the near-ultraviolet-visible region, or the near-ultraviolet to near-ultraviolet-visible region.
3)
The polarized light emitting plate according to 1) or 2), wherein the layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element is a layer capable of reflecting polarized light.
4)
Claim 1: The layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element has a multilayer structure containing two types of substances with different refractive indexes, and is a layer capable of dividing polarized light into a plurality of parts. ) to 3).
5)
The polarized light emitting plate according to any one of 1) to 3), wherein the layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element is a cholesteric liquid crystal layer with fixed helical orientation.
6)
The polarized light emitting plate according to any one of 1) to 5), wherein the polarized light emitting element is an element that emits linearly polarized light.
7)
The polarized light emitting plate according to any one of 1) to 6), wherein the layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element has a light reflectance of 30 to 100%.
8)
The polarized light emitting plate according to any one of 1) to 7), wherein the layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element has a light transmittance in the visible range of 30 to 100%.
9)
An optical film in which the polarized light emitting plate according to any one of 1) to 8) and a retardation plate are laminated.
10)
In the polarized light emitting plate according to any one of 1) to 8) or the optical film described in 9), when the light absorbed by the polarized light emitting element is incident, the absorption wavelength range of the polarized light emitting element and the polarized light emitting element is 1. An optical device characterized in that a layer capable of reflecting light is provided in this order, and light that can be absorbed by the polarized light emitting element enters from the polarized light emitting element side.
11)
The optical device according to item 10) having a liquid crystal display function.

The polarized light-emitting plate, optical film, and optical device according to the present invention utilize incident light with high efficiency, exhibit a high polarization effect at the emission wavelength, and express high-intensity polarized light emission, and Provides polarized light-emitting plates with different light absorption, transmittance, and light-emitting properties. Since the polarized light emitting plate, optical film, and optical device all have a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element, they do not inhibit light emission and can maintain high transparency. Since the incident light can be used with high efficiency, ultraviolet rays contained in natural light can also be used with high efficiency, and for example, sunlight can also be used efficiently. Furthermore, when using sunlight or a light source that emits light in the near-ultraviolet to near-ultraviolet-visible range and converting the light into luminescence, it is possible to use light at wavelengths invisible to the human eye with high efficiency. However, even if the amount of incident light is small, polarized light emission can be achieved with high efficiency. In addition, when the light reflected by the reflective layer has polarization, absorption anisotropy of the polarized light emitting element, that is, the polarization function in absorption and the polarization function in emission, can be used. This invention has led to the creation of a special optical element that utilizes the functions of polarization and anisotropy of each light in light emission and reflection.

The present invention provides an element capable of emitting polarized light by utilizing light absorption, in which the wavelength of the light absorbed by the element is different from the wavelength of the polarized light emitted, and the wavelength range is at least 400 to 700 nm. The present invention relates to a polarized light emitting plate that includes a polarized light emitting element that emits polarized light, and a layer that can reflect light in the absorption wavelength range of the polarized light emitting element. The above-mentioned polarized light emitting plate is capable of emitting high-intensity light with a high degree of polarization, and by controlling the reflected polarization of the above-mentioned layer, light reflection, light transmission, and Light emission intensities can provide light having different polarizations. Generally, an element that absorbs light of a specific wavelength and emits light of a wavelength different from the wavelength of the absorbed light is called a wavelength conversion element, but in this application, the absorbed light is converted into emitted light with polarization. It is called a "polarized light emitting element" because it converts light.

An element capable of emitting polarized light by utilizing absorption of the light is used, and the element is capable of polarizing light in a wavelength range of at least 400 to 700 nm, where the wavelength of the light it absorbs is different from the wavelength of the light it emits polarized light. A polarized light emitting element that emits light is a device that absorbs ultraviolet light to visible light and emits light that is polarized to a wavelength different from the wavelength of the absorbed light and at least in the wavelength range of 400 to 700 nm. There is no limitation as long as it is a wet layer. In order to obtain an element capable of emitting polarized light, it is necessary to include a compound having a light absorption function in the element, and utilize the light wavelength conversion function of the compound to emit polarized light. There is no particular limitation as long as it can be formed as a layer of a substance that can emit polarized light or that can form a layer of a substance that has the function of emitting polarized light. If the light absorption effect is limited to a specific wavelength, the light of the specific wavelength will not be transmitted, so it is also possible to optically design it so that light of other wavelengths is transmitted. It is possible to provide a light emitting element that has high transmittance not only in the entire wavelength range but only in a specific wavelength. Particularly preferably, the element that absorbs light and emits polarized light has a light absorption wavelength in the near ultraviolet to near ultraviolet visible range. By having a light absorption wavelength in the near-ultraviolet to near-ultraviolet-visible range, it is possible to provide an element that has high transmittance and can emit polarized visible light. In a preferred embodiment capable of emitting polarized light, the light absorption range of the polarized light emitting element is at least 350 to 430 nm, and the wavelength of the emitted polarized light is at least in the wavelength range of 400 to 700 nm. One of the preferred embodiments of the present application is to have the following. In the present specification, a polarized light emitting element in which the wavelength of the light it absorbs is different from the wavelength of the polarized light it emits and that emits polarized light in a wavelength range of at least 400 to 700 nm is referred to as a "polarized light emitting element". Describe it. Further, the above-mentioned layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element is sometimes referred to as a "reflection layer".

The polarized light emitting element has a different wavelength from the wavelength of the light it absorbs and the wavelength of the light it emits, and emits polarized light within a wavelength range of at least 400 to 700 nm. For example, in the light wavelength region, it absorbs light with a wavelength shorter than 430 nm in the near ultraviolet to near ultraviolet visible range, and has an emission spectrum peak in part or all of the visible range of 380 to 780 nm. It is an element that emits polarized light with a polarized light. In the present application, light of a wavelength that preferably absorbs light in the near-ultraviolet to near-ultraviolet-visible range that is invisible to the human eye, that is, light of 300 to 430 nm, can be used as light emitted by the polarized light emitting element. In order to make it easier to visually recognize the light, it is preferable to use light that is invisible to the human eye, or light with a wavelength to which the human eye is extremely sensitive, as the light absorbed by the polarized light emitting element. Therefore, the absorption wavelength of light of the polarized light emitting element is preferably 340 to 420 nm, still more preferably 350 to 410 nm, particularly preferably 350 to 400 nm. The light in the near-ultraviolet to near-ultraviolet-visible range that is irradiated onto the polarized light emitting element may or may not be polarized. The polarized light-emitting element described above can obtain a preferable form by containing at least a base material and a polarized light-emitting dye, which will be described later, but is not necessarily limited thereto.

It is preferable that the light emitted by the polarized light emitting element is linearly polarized light. Linearly polarized light is light that can also be represented as waves oriented along a fixed axis. By emitting linearly polarized light, that is, uniaxially polarized light, it becomes easier to design display devices such as liquid crystal displays. This means that many commercially available liquid crystal displays and polarized lenses use iodine-based polarizing plates that can provide linearly polarized light, and dye-based polarizing plates that use dichroic dyes that can provide linearly polarized light. Therefore, it is easy to think that linearly polarized light is suitable for industrial use. On the other hand, if you try to use circularly or elliptically polarized light, the design of the liquid crystal cell and the orientation of the liquid crystal used therein will become complicated, or the design of the retardation plate etc. will become significantly complicated. Since industrial use is difficult and limited, it is preferable that the polarized light be linearly polarized light. Emission of linearly polarized light can be achieved, for example, by aligning the polarized light-emitting dyes described below in the same direction in the base material. Furthermore, by emitting light that is uniaxially polarized by the polarized light-emitting dye, the intensity of the propagating light increases, and it is possible to provide light that is stronger than the theoretically original emission intensity of the dye. leading to. That is, it is possible to provide linearly polarized light with higher brightness. In addition, by combining a linearly polarizing plate with a retardation plate, it becomes possible to change the polarization to various types, which facilitates optical design. For example, by providing 1/4λ to the emission wavelength, it is possible to emit circularly polarized light, or by providing 1/2λ to the emission wavelength, the emitted linearly polarized light can be rotated by 90 degrees. . Therefore, since the polarization can be adjusted in various ways, it can be said that providing a retardation plate for the polarized light emitting element is a preferable embodiment of the present application.

The polarized light-emitting dye preferably emits linearly polarized light by being oriented, and also has absorption anisotropy at the wavelength at which it absorbs light. For example, polarized light-emitting dyes absorb light in the near-ultraviolet to near-ultraviolet-visible range, convert the wavelength of the absorbed light, and emit polarized light in the visible range. It is preferable that the amount of light absorption differs between the orientation direction and a direction different from the orientation direction. This indicates that light has absorption anisotropy, that is, dichroism in absorption, and when a layer that can reflect light in the absorption wavelength range of the polarized light emitting element is provided, light transmission and light reflection occur. Alternatively, it is possible to provide light having various polarization states different from that of a polarized light emitting element in light obtained by absorption. In addition, when the reflective layer has anisotropy of reflected light, that is, a polarized light reflecting function, by using it together with a polarized light emitting element that has anisotropy of light absorption, it is possible to perform transmission, reflection, or absorption. Since the obtained light can be provided with further different polarization states, it is possible to transmit or not transmit light, or adjust the amount of light, etc. by controlling the polarized light. The light absorption anisotropy obtained by orienting a polarized light-emitting dye is sometimes expressed as a dichroic ratio (hereinafter also referred to as RD), and from the value of this dichroic ratio, the degree of orientation of the dye (hereinafter referred to as RD) is Order Parameter) can be calculated. Dichroic ratio is the ratio of the absorption amount of the axis with the strongest absorption to the absorption amount of the axis with the lowest absorption.If the dichroic ratio is 5 to 80, highly polarized light can be emitted. , preferably 10 or more and 80 or less, preferably 20 or more, more preferably 30 or more, particularly preferably 40 or more. The degree of orientation of the dye is a numerical value given by the following formula (I), and is preferably 0.85 or more and 1.00 or less, particularly preferably 0.90 or more and 1.00 or less.

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

A preferred example of the polarized light emitting device is a polarized light emitting device in which a polarized light emitting dye has at least a stilbene skeleton or a biphenyl skeleton in the dye molecule and the dye is oriented in a base material. One form of the manufacturing method will be shown below as an example.

<Base material>
The polarized light emitting element uses a polymer film as a base material for adsorbing and orienting a polarized light emitting dye, which will be described later. The polymer film is preferably a hydrophilic polymer film obtained by forming a hydrophilic polymer capable of adsorbing general dichroic polarized light-emitting dyes, particularly dyes having a stilbene skeleton or dyes having a biphenyl skeleton. It is a polymer film. The hydrophilic polymer is not particularly limited, but for example, polyvinyl alcohol-based resins and starch-based resins are preferable, and from the viewpoint of dyeability, processability, and crosslinking properties of the polarized light-emitting dye having dichroism, polyvinyl alcohol is preferred. Preferably, they are based on resins and derivatives thereof. Examples of the above-mentioned polyvinyl alcohol-based resins and derivatives thereof include polyvinyl alcohol or derivatives thereof, and combinations of any of these with olefins such as ethylene and propylene, and monomers such as crotonic acid, acrylic acid, methacrylic acid, and maleic acid. Examples include those modified with saturated carboxylic acids and the like. Among these, films made of polyvinyl alcohol resins and derivatives thereof are preferably used from the viewpoint of adsorption and orientation of polarized light-emitting dyes having dichroism. The base material may be, for example, a film made of a commercially available polyvinyl alcohol resin or a derivative thereof, or may be produced by forming a polyvinyl alcohol resin into a film. The method for forming a polyvinyl alcohol resin film is not particularly limited. Known film forming methods can be employed, such as gelling, extraction and removal of the solvent), cast film forming method (pouring an aqueous polyvinyl alcohol solution onto a substrate and drying), and a combination thereof. The thickness of the base material is usually about 10 to 100 μm, preferably about 20 to 80 μm.

<Method for manufacturing polarized light emitting element>
The method for manufacturing the polarized light emitting device is not limited to the following manufacturing method, but it is preferable to use a film mainly made of polyvinyl alcohol resin and its derivatives. A method for producing a polarized light emitting element using a film made of polyvinyl alcohol resin and its derivatives will be described.
The method for producing the polarized light-emitting element includes a step of preparing a base material, a swelling step of immersing the base material in a swelling liquid to swell the base material, and at least adding one or more of the polarized light-emitting dyes to the swollen base material. A dyeing process in which the substrate is impregnated with a dyeing solution and adsorbs the polarized luminescent pigment, and a crosslinking process in which the polarized luminescent pigment is crosslinked in the base material by immersing the substrate on which the polarized luminescent pigment has been adsorbed in a solution containing boric acid. step, a stretching step in which a base material crosslinked with a polarized light-emitting dye is uniaxially stretched in a certain direction to align the polarized light-emitting dye in a certain direction, and, if necessary, a washing step in which the stretched base material is washed with a cleaning solution. and/or a drying step of drying the washed substrate.

(swelling process)
The above swelling step will be explained. The swelling step is preferably carried out by immersing the base material in a swelling liquid at 20 to 50°C for 30 seconds to 10 minutes, and the swelling liquid is preferably water. The stretching ratio of the base material is preferably adjusted to 1.00 to 1.50 times, more preferably 1.10 to 1.35 times.

(dying process)
The above dyeing process will be explained. In the dyeing step, one or more polarized light-emitting dyes described below are adsorbed onto the base material obtained through the swelling step. The dyeing process is not particularly limited as long as it is a method that can adsorb the polarized light-emitting dye to the base material, but examples include a method in which the base material is immersed in a dyeing solution containing the polarized light-emitting dye, or a method that allows the base material to be adsorbed to the base material. Examples include a method of applying a dyeing solution containing a polarized light-emitting dye, but a method of immersing it in a dyeing solution containing a polarized light-emitting dye is preferred. 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 into the substrate, but for example, if the polarized light-emitting dye concentration in the dyeing solution is 0. It is preferably 0.0001 to 1% by weight, more preferably 0.0001 to 0.5% by weight. 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. Further, the time for immersing the substrate in the dyeing solution can be adjusted as appropriate, and is preferably adjusted between 30 seconds and 20 minutes, and more preferably between 1 and 10 minutes. The polarized light-emitting dyes contained in the dyeing solution may be used alone or in combination of two or more. The polarized light-emitting dyes emit different colors due to differences in dye structure, so by containing two or more types of the polarized light-emitting dyes in the base material, the emitted light colors produced can be appropriately adjusted to various colors. be able to. Further, if necessary, the dyeing solution may further contain one or more organic dyes and/or fluorescent dyes in addition to the polarized light-emitting dye.

(polarized light-emitting dye)
The above polarized light-emitting dye is a compound or a salt thereof that has at least one of a stilbene skeleton or a biphenyl skeleton in the structure of the dye molecule, and emits light using absorbed light, and emits fluorescence or phosphorescence. Examples include those that emit fluorescence, and those that emit fluorescence are preferred. The polarized light-emitting dye has a fluorescence emission function and also has a dichroic ratio at the absorption wavelength of light, so that polarized light can be emitted. In particular, polarized light-emitting dyes having a stilbene skeleton or a biphenyl skeleton in the dye molecule have excellent fluorescence emission characteristics, and when oriented, have a high dichroic ratio at the absorption wavelength. These are derived from the properties of each of the above-mentioned skeletons, and these properties can be further improved or various properties such as absorption wavelength, emission wavelength, fastness such as light resistance, moisture resistance, ozone gas resistance, and solubility can be adjusted. Depending on the purpose, it is possible to further introduce arbitrary substituents into each of the above skeletons. When introducing a substituent, if the type of substituent or the position of the substituent is unfavorable, even if a high degree of polarization can be achieved, as with conventional dye-based polarizing plates, the amount of emitted light may decrease significantly. Therefore, in order to have excellent fluorescence emission characteristics and a high dichroic ratio, it is particularly important to select the type of substituent and the substitution position. Moreover, the above-mentioned polarized light-emitting dyes may be used alone or in combination of two or more.

(a) Polarized light-emitting dye having a stilbene skeleton The dye having a stilbene skeleton is preferably a compound represented by formula (1) or a salt thereof.

In the above formula (1), L and M each independently include a nitro group, an amino group which may have a substituent, a carbonylamide group which may have a substituent, and a substituent. naphthotriazole group, alkyl group having 1 to 20 carbon atoms which may have a substituent, vinyl group which may have a substituent, amide group which may have a substituent, It represents a good ureido group, an aryl group which may have a substituent, and a carbonyl group which may have a substituent, but is not necessarily limited to these. It is known that the dye having a stilbene skeleton represented by formula (1) emits fluorescence and can obtain dichroism when oriented, but this is mainly due to the stilbene skeleton. and further arbitrary substituents may be introduced. However, when the stilbene skeleton has an azo group at the L position and the M position, the fluorescence emission becomes significantly small, which is not suitable.

Examples of the amino group that may have a substituent include an unsubstituted amino group, methylamino group, ethylamino group, n-butylamino group, tert-butylamino group, n-hexylamino group, dodecylamino group, Alkylamino group having 1 to 20 carbon atoms which may have a substituent such as dimethylamino group, diethylamino group, di-n-butylamino group, ethylmethylamino group, ethylhexylamino group, phenylamino group, diphenyl Substitution of arylamino groups that may have substituents such as amino groups, naphthylamino groups, N-phenyl-N-naphthylamino groups, methylcarbonylamino groups, ethylcarbonylamino groups, n-butyl-carbonylamino groups, etc. Alkylcarbonylamino group having 1 to 20 carbon atoms which may have a group, phenylcarbonylamino group, biphenylcarbonylamino group, arylcarbonylamino group which may have a substituent such as naphthylcarbonylamino group, methylsulfonylamino group group, an alkylsulfonylamino group having 1 to 20 carbon atoms such as an ethylsulfonylamino group, a propylsulfonylamino group, an n-butyl-sulfonylamino group, a phenylsulfonylamino group, a naphthylsulfonylamino group, etc. Good arylsulfonylamino, etc. include an alkylcarbonylamino group having 1 to 20 carbon atoms which may have a substituent, an arylcarbonylamino group which may have a substituent, and an alkylsulfonylamino group having 1 to 20 carbon atoms. An arylsulfonylamino group which may have a group or a substituent is preferable. In addition, an alkylamino group having 1 to 20 carbon atoms which may have the above substituents, an arylamino group having 1 to 20 carbon atoms which may have a substituent, and an alkylcarbonylamino group having 1 to 20 carbon atoms which may have a substituent. There are no particular restrictions on the substituents in the group, the arylcarbonylamino group that may have a substituent, the alkylsulfonylamino group having 1 to 20 carbon atoms, and the arylsulfonylamino group that may have a substituent, but Examples include a nitro group, a cyano group, a hydroxyl group, a sulfonic acid group, a phosphoric acid group, a carboxy group, a carboxyalkyl group, a halogen atom, an alkoxyl group, an 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, an iodine atom, and the like. Examples of the alkoxyl 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.

Examples of the carbonylamide group which may have a substituent include N-methyl-carbonylamide group (-CONHCH ₃ ), N-ethyl-carbonylamide group (-CONHC ₂ H ₅ ), N-phenyl-carbonyl Examples include amide group (-CONHC ₆ H ₅ ).

Examples of the naphthotriazole group which may have the above-mentioned 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 a methyl group, ethyl group, n-butyl group, n-hexyl group, n-octyl group, n-dodecyl group, etc. Examples include branched 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, and a pentadiene group.

Examples of the amide group which may have a substituent include an acetamido group (-NHCOCH ₃ ), a benzamide group (-NHCOC ₆ H ₅ ), and the like.

Examples of the above-mentioned aryl group which may have a substituent include a phenyl group, a naphthyl group, a ditracenyl group, a biphenyl group, and the like.

Examples of the carbonyl group which may have a substituent include a methylcarbonyl group, an ethylcarbonyl group, an n-butylcarbonyl group, and a phenylcarbonyl group.

A carbonylamide group which may have the above substituents, a naphthotriazole group which may have a substituent, an alkyl group having 1 to 20 carbon atoms which may have a substituent, and a substituent which may have a substituent. As a substituent in a vinyl group, an amide group which may have a substituent, a ureido group which may have a substituent, an aryl group which may have a substituent, a carbonyl group which may have a substituent is not particularly limited, but may be the same as the substituent described in the section of the 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 element that emits brighter white light.

In the above formula (2), the substituent R is a halogen atom such as a hydrogen atom, a chlorine atom, a bromine atom, or a fluorine atom, a hydroxyl group, a carboxy group, a nitro group, an alkyl group that may have a substituent, or a substituent. Represents an alkoxyl group that may have a substituent or an amino group that 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 those mentioned above in the section of the alkyl group having 1 to 20 carbon atoms which may have a substituent. The alkoxyl group which may have a substituent is preferably a methoxy group or an ethoxy group. The amino group which may have a substituent may be the same as mentioned above, and is preferably a methylamino group, dimethylamino group, ethylamino group, diethylamino group, or phenylamino group. 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 set to the 1st and 2nd positions, the substituent R may be bonded to the 3rd, 5th, or Preferably, it is bonded to the 8th position. n is an integer from 0 to 3, preferably 1 or 2. The -(SO ₃ H) group may be bonded to any carbon of the naphthalene ring in the naphthotriazole ring. The substitution position of the -(SO ₃ H) group in the naphthalene ring is, when n=1, the carbon condensed with the triazole ring is the 1st position, and when the 2nd position is the 4th, 6th, or 7th position. When n=2, preferably the 5th and 7th and 6th and 8th positions, and when n=3, a combination of the 3rd, 6th and 8th positions. It is preferable. 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 which may have a substituent may be the same as above, and may include an alkylcarbonylamino group having 1 to 20 carbon atoms which may have a substituent, an arylcarbonylamino group which may have a substituent, Preferably, it is 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. , preferably an aryl group that may have a substituent, more preferably a naphthyl group that may have a substituent, and a naphthyl group substituted with an amino group and a sulfo group as substituents. is particularly preferred. Z represents the same substituent as explained for X in formula (2) above, 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. Furthermore, the compounds represented by formula (1) are exemplified below, but are not limited thereto.

(b) Polarized light-emitting dye having a biphenyl skeleton The above dye having a biphenyl skeleton is preferably a compound represented by formula (4) or a salt thereof.

In the above formula (4), P and Q each independently include a nitro group, an amino group that may have a substituent, a carbonylamide group that may have a substituent, and a carbonylamide group that may have a substituent. naphthotriazole group, alkyl group having 1 to 20 carbon atoms which may have a substituent, vinyl group which may have a substituent, amide group 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 to these. Amino group which may have a substituent, carbonylamide group which may have a substituent, naphthotriazole group which may have a substituent, alkyl having 1 to 20 carbon atoms which may have a substituent The vinyl group that may have a substituent, the amide group that may have a substituent, the aryl group that may have a substituent, and the carbonyl group that may have a substituent are the same as above. That's fine. However, in the case where the biphenyl skeleton in the above formula (4) has an azo group at the P position and/or the Q position, the fluorescence emission becomes significantly small, which is not suitable.

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 from 0 to 2. The preferred substitution position of the -(SO ₃ H) group is not particularly limited, but when the vinyl group is the 1st position, the 2nd and 4th positions are preferred, and the 2nd position is particularly preferred.

In the above formula (5), R ₁ , R ₂ , R ₃ , and R ₄ each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, an aralkyloxy group, and an alkenyloxy group. alkylsulfonyl group having 1 to 4 carbon atoms, an arylsulfonyl group having 6 to 20 carbon atoms, a carbonamide 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 methyl group, ethyl group, propyl group, n-butyl group, sec-butyl group, tert-butyl group, and cyclobutyl group. Examples of the alkoxyl group having 1 to 4 carbon atoms include methoxy group, ethoxy group, propoxy group, n-butoxy group, sec-butoxy group, tert-butoxy group, and cyclobutoxy group. Examples of the aralkyloxy group include aralkyloxy groups having 7 to 18 carbon atoms. Examples of the alkenyloxy group include alkenyloxy groups having 1 to 18 carbon atoms. Examples of the alkylsulfonyl group having 1 to 4 carbon atoms include methylsulfonyl group, ethylsulfonyl group, propylsulfonyl group, n-butylsulfonyl group, sec-butylsulfonyl group, tert-butylsulfonyl group, and cyclobutylsulfonyl group. It will be done. Examples of the arylsulfonyl group having 6 to 20 carbon atoms include phenylsulfonyl group, naphthylsulfonyl group, biphenylsulfonyl group, and the like.

In the above formula (5), the preferred substitution positions of R ₁ to R ₄ are preferably the 2nd and 4th positions when the vinyl group is the 1st position.

A 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 formula (5) can be produced by a known method, for example, by condensing 4-nitrobenzaldehyde-2-sulfonic acid with a phosphonate and then reducing the nitro group.

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

The salts of the compounds represented by the above formulas (1) to (5) are salts formed with inorganic cations or organic cations. Inorganic cations include alkali metal cations 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, preferably C ₁ -C ₄ alkyl, such as methyl, ethyl, butyl, pentyl, and hexyl; hydroxymethyl, 2-hydroxyethyl, 3-hydroxy HydroxyC ₁ -C ₆ alkyl, preferably hydroxyC ₁ -C ₄ alkyl, such as propyl, 2-hydroxypropyl, 4-hydroxybutyl, 3-hydroxybutyl, and 2-hydroxybutyl; and hydroxyethoxymethyl, 2-hydroxy HydroxyC ₁ -C ₆ alkoxyC ₁ -C ₆ alkyl, preferably hydroxyC ₁ -C ₄ alkoxyC ₁ -C such as ethoxyethyl, 3-hydroxyethoxypropyl, 3-hydroxyethoxybutyl, and 2-hydroxyethoxybutyl ₄ alkyl and the like.

More preferred among these inorganic cations and organic cations are sodium ion, potassium ion, lithium ion, monoethanolammonium ion, diethanolammonium ion, triethanolammonium ion, monoisopropanolammonium ion, diisopropanolammonium ion, and triethanolammonium ion. Examples include cations such as isopropanol ammonium ion and ammonium. Among these, lithium ions, ammonium ions, and sodium ions are more preferred.

Other polarized light-emitting dyes that can be used in the polarized light-emitting element include, 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 (eg, Na salts, K salts, Li salts), ammonium salts, or salts of amines.

A polarized light-emitting element that emits polarized light can be obtained by orienting one type of the polarized light-emitting dye or a combination of two or more of the above polarized light-emitting dyes. In the case where two or more types of polarized light-emitting dyes are used in the polarized light-emitting element, by adjusting the blending ratio between the polarized light-emitting dyes, it is possible to adjust the emission colors to be various. For example, by adjusting the absolute values of the chromaticity a ^* value and b ^* value to be 5 or less, it is possible to make the polarized light emitted by the polarized light emitting element white. The above chromaticity a ^* value and b ^* value are determined 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. It will 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 (CIE). Measurement of chromaticity a ^* value and b ^* value is usually performed by irradiating the measurement sample with natural light, but in the specification and claims of this application, short wavelength light such as ultraviolet light is used in the polarized light emitting element. The chromaticity a ^* value and b ^* value can be confirmed by irradiating the 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, even more preferably 2 or less, particularly preferably 1 or less. Further, the absolute value of b ^* of the emitted light is 5 or less, preferably 4 or less, more preferably 3 or less, still more preferably 2 or less, particularly preferably 1 or less. If the absolute values of a ^* value and b ^* value are each independently 5 or less, the human eye can perceive it as white light, and if both of each is 5 or less, it is perceived as more preferable white light emission. be able to. Because the emitted polarized light is white, it can be used as a natural light source such as sunlight, or as a light source for paper white terminals, etc., and has the advantage that it can be easily applied to displays that use color filters, etc. There is. Regarding the luminous intensity, as long as the luminous intensity can be detected by the eye, there is no problem in applying it to displays. In particular, as a feature of the present application, it is important that the emitted light has a high degree of polarization and that the transmittance in the visible region is high.

(2) Other dyes It is preferable that the above polarized light emitting element contains one or more dyes having a stilbene skeleton or a biphenyl skeleton, or salts thereof, for the purpose of color adjustment, etc., to the extent that the polarized light emitting function is not inhibited. , if necessary, may further contain one or more other organic dyes or other fluorescent dyes. Other organic dyes are not particularly limited as long as they can control the color (hue) or emission color of the polarized light emitting element, but those with high dichroism are preferred and those with a stilbene skeleton or biphenyl skeleton are used. A dye that has little effect on polarization performance in the ultraviolet light region is preferred. Examples of such other organic dyes include C.I. I. Direct. Yellow12,C. I. Direct. Yellow28,C. I. Direct. Yellow44, C. I. Direct. Orange26,C. I. Direct. Orange39,C. I. Direct. Orange71,C. I. Direct. Orange107,C. I. Direct. Red2,C. I. Direct. Red31,C. I. Direct. Red79,C. I. Direct. Red81,C. I. Direct. Red247,C. I. Direct. Blue69,C. I. Direct. Blue78,C. I. Direct. Green80, and C. I. Direct. Green59 etc. are mentioned. These organic dyes may be free acids, or may be alkali metal salts (eg, Na salts, K salts, Li salts), ammonium salts, or salts of amines. In addition, as the other fluorescent dyes mentioned above, commonly disclosed fluorescent dyes can also be used for the purpose of adjusting the emission color, and there is no particular limitation.

When using the other organic dyes or other fluorescent dyes in combination, it is possible to select the dyes to be blended and adjust the blending ratio, etc., in order to adjust the desired color of the polarized light emitting element. Depending on the purpose of preparation, the blending ratio of organic dyes or fluorescent dyes is not particularly limited, but the total amount of these other organic dyes or other fluorescent dyes is 0.01 to 10 parts by mass relative to 100 parts by mass of the polarized light emitting element. It is preferable to use within the range of parts by mass.

In addition to each of the dyes mentioned above, the dyeing solution may further contain a dyeing aid as required. Examples of the dyeing aid include sodium carbonate, sodium bicarbonate, sodium chloride, sodium sulfate (mirabilite), anhydrous sodium sulfate, and sodium tripolyphosphate, with sodium sulfate being preferred. The content of the dyeing aid can be arbitrarily adjusted depending on the dyeing property of the dye used, the above-mentioned immersion time, the temperature of the dyeing solution, etc., but it is preferably 0.0001 to 10% by mass in the dyeing solution. More preferably, it is 0.0001 to 2% by mass.

After the dyeing step, a pre-cleaning step may optionally be performed to remove the dyeing solution adhering to the surface of the substrate during the dyeing step. By performing the pre-cleaning step, it is possible to suppress the dye remaining on the surface of the substrate from migrating into 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 base material in a cleaning liquid, but on the other hand, cleaning can also be carried out by applying a cleaning liquid to the base material. 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 must be at a temperature at which the material constituting the base material does not dissolve, and the cleaning treatment is generally performed at a temperature of 5 to 40°C. Note that even if the pre-cleaning step is not performed, the performance of the polarized light emitting element is not particularly affected, so the pre-cleaning step can be omitted.

(Crosslinking process)
After the dyeing step or the preliminary washing step, the base material can contain a crosslinking agent. The method for incorporating a crosslinking agent into a base material is preferably to immerse the base material in a treatment solution containing a crosslinking agent, and on the other hand, the treatment solution may be applied or coated onto the base material. 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 preferred. The concentration of boric acid in the treatment solution is preferably 0.1 to 15% by mass, 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 manufacturing a polarized light emitting element according to the present invention includes this crosslinking step, the polarization degree of the light emitted by the obtained polarizing element is high, and it exhibits high contrast as a display. This is an excellent effect that was completely unexpected from the function of boric acid, which was used in the prior art for the purpose of improving water resistance or light transmittance. In addition, in the crosslinking step, a fixing treatment may be further performed with an aqueous solution containing a cationic polymer compound, if necessary. This fixing treatment enables fixation of the dye in the polarized light emitting element. At this time, examples of cationic polymer compounds include cations, dicyanamide and formalin polymer condensates as dicyanic compounds, dicyandiamide/diethylenetriamine polycondensates as polyamine compounds, epichlorohydrin/dimethylamine addition polymers, dimethyl cationic compounds, etc. Diallylammonium chloride/dioxide ion copolymers, diallylamine salt polymers, dimethyldiallylammonium chloride polymers, allylamine salt polymers, dialkylaminoethyl acrylate quaternary salt polymers, and the like are used.

(Stretching process)
After passing through the above-mentioned crosslinking step, a stretching step is performed. The stretching step is performed by uniaxially stretching the base material in a certain direction, and may be performed by either a wet stretching method or a dry stretching method. The stretching ratio is preferably 3 times or more, more preferably 5 to 8 times.

In the wet stretching method, the base material is preferably stretched in water, a water-soluble organic solvent, or a mixed solution thereof. More preferably, the stretching treatment is performed while the base material is immersed in a solution containing at least one crosslinking agent. As the crosslinking agent, for example, boric acid used in the above-mentioned crosslinking agent step can be used, and preferably, the stretching treatment can be performed in the treatment solution used in the crosslinking step. The stretching temperature is preferably 40 to 70°C, more preferably 45 to 60°C. The stretching time is usually 30 seconds to 20 minutes, preferably 2 to 7 minutes. The wet stretching step may be performed in one stage or in multiple stages of two or more stages. Note that the stretching treatment may optionally be performed before the dyeing step, and in this case, the orientation of the dye can also be performed at the time of dyeing.

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

(Washing process)
During the stretching step, the crosslinking agent may precipitate or foreign matter may adhere to the surface of the base material, so a cleaning step may be performed to clean the surface of the base material. The washing time is preferably 1 second to 5 minutes. As for the cleaning method, it is preferable to immerse the substrate in a cleaning liquid, but it is also possible to clean the substrate by applying or coating the cleaning liquid onto the substrate. Water is preferred as the cleaning liquid. The cleaning treatment may be performed in one step or in multiple stages of two or more steps. The temperature of the cleaning solution in the cleaning step is not particularly limited, but is usually 5 to 50°C, preferably 10 to 40°C, and may be room temperature.

In addition to the above-mentioned water, examples of solvents for the solution or treatment liquid used in each of the above steps include dimethyl sulfoxide, N-methylpyrrolidone, methanol, ethanol, propanol, isopropyl alcohol, glycerin, ethylene glycol, propylene glycol, diethylene glycol, Examples 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 most preferably water, although it is not limited thereto. Further, the solvents for these solutions or treatment liquids may be used alone or in a mixture of two or more.

(drying process)
After the above-mentioned washing step, a step of drying the base material is performed. The drying process can be carried out by natural drying, but in order to further increase the drying efficiency, it is possible to carry out by compressing with a roll, removing moisture from the surface with an air knife or water absorbing roll, etc. Furthermore, air drying can be carried out. 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.

The above method is an example of a method for manufacturing a polarized light emitting element that can be used in the present invention. Since each of the above-mentioned dyes does not decompose even under high temperature and high humidity heat environments, a polarized light emitting element having high durability can be obtained.

The above-mentioned polarized light-emitting element containing a compound or a salt thereof that has at least one of a stilbene skeleton or a biphenyl skeleton in its structure and emits fluorescence can emit light in the near-ultraviolet to near-ultraviolet-visible region, that is, in the non-visible light region. It has the characteristic of being able to absorb light in the near-ultraviolet to near-ultraviolet-visible range when irradiated with it, and use that energy to emit polarized light in the visible light range. Since the light emitted by a polarized light emitting element is polarized light in the visible light range, when the polarized light emitting element is observed through a general polarizing plate that has a polarizing function for light in the visible light range, the visible By changing the angle of the axis of a general polarizing plate that has a polarization function in the optical region, it is possible to visually recognize the light of the strong emission axis and the light of the weak emission axis (or the light of the non-emission axis) of polarized light. Can be done. The degree of polarization of the polarized light emitted by the polarized light emitting element is 70% or more and 100% or less, preferably 80% or more, more preferably 90% or more, still more preferably 95% or more, particularly preferably 98% or more.

The polarized light emitting element can transmit light in the visible light range without absorbing it. In other words, the polarized light emitting element can provide high transmittance for light in the visible light range with visibility correction, and can provide a transmittance of 30 to 100%, which is the transmittance of a general polarizing plate. It is possible to do so. If it is 60% or more, a liquid crystal display with significantly higher transmittance than conventional liquid crystal displays can be obtained, but it is preferably 70% or more, more preferably 80% or more, still more preferably 85% or more, especially Preferably it is 90% or more. The polarized light-emitting element described above, which contains a compound or a salt thereof that emits fluorescence and has at least one of a stilbene skeleton or a biphenyl skeleton in its structure, has low absorption in the visible light region in the non-emission state, and visually It is preferable because a polarized light emitting element with high transparency can be obtained, and since it can emit light with a high degree of polarization, it is possible to provide a polarized light emitting film with high brightness.

[Polarized luminescent plate]
The polarized light emitting plate is characterized in that a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element is laminated on the polarized light emitting element. When laminating the polarized light emitting element and the layer, they may be laminated so that they are in contact with each other, or they may be laminated via an adhesive layer, an adhesive layer, a retardation film, or the like.

The layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element is not limited as long as it can reflect light of a wavelength absorbed by the polarized light emitting element in the near ultraviolet to visible range. For example, when the polarized light emitting element absorbs light of 300 to 430 nm, it is particularly preferable that the reflection layer reflects light of the same wavelength as 300 to 430 nm. The wavelength and the reflected wavelength of the light from the reflective layer do not necessarily have to match, and the effect of the present application can be achieved as long as the absorbed light wavelength and the reflected wavelength match even partially. For example, if the polarized light emitting element has a light absorption wavelength in the range of 300 to 430 nm, and if it has the reflection wavelength in the range of 300 to 350 nm or 350 to 400 nm, a part of the absorption wavelength range may be used. may include a reflection wavelength range, or a part of the reflection wavelength range may include an absorption wavelength range, such as when the absorption wavelength is 300 to 430 nm and the reflection wavelength is 250 to 450 nm.

Examples of members that can be used for the reflective layer include reflective films deposited with silver, aluminum, etc., dichroic filters, anisotropic birefringent laminates, films provided with cholesteric liquid crystal layers having helical orientation, etc. It is not limited to these. Since the polarized light emitting element mentioned as a preferred embodiment of the present application has absorption anisotropy, one preferred embodiment is that the layer capable of reflecting light in the near ultraviolet to visible range is capable of reflecting polarized light. can be mentioned. Since a layer that can reflect light in the ultraviolet to visible range can reflect polarized light, it becomes possible to produce various polarized light-emitting plates using the reflected polarized light. For example, if the direction of the reflected polarized light matches the orientation direction of the dye in the polarized light emitting element that can emit polarized light, not only the light absorbed by the dye in the polarized light emitting element but also the light absorbed by the reflective layer Since it is possible to absorb more of the reflected light, it is possible to absorb more light than the light that is incident on the polarized light emitting element, and further converts the wavelength to produce light in the visible range. can be made to emit light. In this case, the polarized light that is not absorbed by the oriented dye contained in the polarized light emitting element or that is not reflected from the polarized light in the ultraviolet to visible range is transmitted as polarized light, so it is not transmitted. It can be used separately as polarized light in the ultraviolet to visible range. On the other hand, if the direction of the reflected polarized light and the orientation of the dye in the polarized light emitting element that can emit polarized light are orthogonal, the axis in which the dye in the polarized light emitting element absorbs light and the orientation axis of the dye Since light with a different axis from absorption is reflected by the reflective medium, it is possible to function as a polarized light emitting plate that does not transmit incident light at wavelengths where the absorption wavelength of the polarized light emitting element matches the wavelength that can be reflected. It is also possible to obtain an optical system using reflected polarized light by using light having polarization in the ultraviolet to visible range that is transmitted without being absorbed by the polarized light emitting element and reflected by the reflective layer. .

The above-mentioned dichroic filter, which can reflect light in the range of 300 to 430 nm, refers to a lens or film made of a dielectric multilayer film.Products include dichroic mirror glass (product name: HeatBuster) manufactured by Sigma Koki Co., Ltd., and dichroic mirror filter (product name: HeatBuster). Product name: NHOTH), etc.

It is preferable that the layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element has a multilayer film laminated structure containing two types of substances with different refractive indexes, and is a layer capable of dividing polarized light into a plurality of parts. . For example, polarized light can be split by making a multilayer film of two types of resins with different refractive indexes, and having an axis that reflects using the principle of thin film interference and an axis that has no difference in refractive index and is transmitted without being reflected. , it can be used as a layer that reflects polarized light at a specific wavelength. In this case, the transmitted light can also be used as polarized light. The above-mentioned reflective layer made of a multilayer film of two types of resins with different refractive indexes is disclosed in, for example, Japanese Patent No. 3,621,415, and is generally used as a reflective polarizing plate or a brightness-enhancing film. It is something that is used. Examples of the reflective polarizing plate and the brightness enhancement film include US Pat. It is also disclosed in WO 2005/0888363, JP 2007-298634, WO 2011/074701, etc., and examples of the product include DBEF (manufactured by 3M). In addition, it is preferable to use the reflective polarizing plate because it not only allows uniaxial linearly polarized light to pass through, but also reflects axial light that can be reflected to the polarized light emitting element, allowing effective use of the light. Therefore, one preferable embodiment of the present invention is to use a reflective polarizing plate made of a multilayer film of two types of resins having different refractive indexes.

It is also exemplified as a preferred embodiment of the present application that the layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element is a cholesteric liquid crystal layer having a fixed helical orientation. It is generally known that a cholesteric liquid crystal layer having a helical orientation has a property of selectively reflecting circularly polarized light. The cholesteric liquid crystal layer can be configured to reflect either right-handed circularly polarized light or left-handed circularly polarized light. For example, when a plurality of light reflective layers are laminated, the visible light reflective layer to be laminated can be configured to reflect either right-handed or left-handed circularly polarized light. Both of the light reflecting layers may have the property of reflecting circularly polarized light in the same direction. The reflection of the cholesteric liquid crystal layer with fixed helical orientation can reflect or transmit circularly polarized light only at the reflected wavelength, but on the other hand, light at wavelengths other than the reflected wavelength is circularly polarized. It is known that the incident light does not become light, but passes through it while maintaining the same state as the incident light. That is, at wavelengths other than those at which reflection is controlled by the cholesteric liquid crystal layer having a fixed helical orientation, when linearly polarized light is incident, linearly polarized light is incident, and unpolarized light is incident. In this case, the layer becomes a layer through which unpolarized light is transmitted without being reflected.

The above-mentioned cholesteric liquid crystal generally consists of a nematic liquid crystal having chirality or a mixture of a nematic liquid crystal and a chiral agent added thereto. The direction of the helix and the reflection wavelength can be arbitrarily designed depending on the type and amount of the chiral agent added, or the thickness and orientation of the liquid crystal containing the chiral agent. Therefore, cholesteric liquid crystals can be created by adding a chiral agent to nematic liquid crystals. The method of obtaining is preferred. The nematic liquid crystal used in the present invention is different from a so-called liquid crystal operated by an electric field and is used with a fixed helical orientation state, so it is preferable to use a nematic liquid crystal monomer having a polymerizable group.

The above-mentioned nematic liquid crystal monomer having a polymerizable group includes, for example, a compound having a polymerizable group in the molecule and exhibiting liquid crystallinity in a specific temperature range or concentration range. Examples of the polymerizable group include a (meth)acryloyl group, a vinyl group, a chalconyl group, a cinnamoyl group, and an epoxy group. In addition, in order to exhibit liquid crystallinity, it is preferable that there is a mesogenic group in the molecule, and mesogenic groups include, for example, biphenyl group, terphenyl group, (poly)benzoic acid phenyl ester group, (poly)ether group, benzylideneaniline group, or a rod-shaped or plate-shaped substituent such as an acenaphthoquinoxaline group, or a disc-shaped substituent such as a triphenylene group, a phthalocyanine group, or an azacrown group, that is, a group having the ability to induce liquid crystal phase behavior. Liquid crystal compounds with rod-like or plate-like groups are known in the art as calamitic liquid crystals. Specifically, nematic liquid crystal monomers having such polymerizable groups include polymerizable liquid crystals described in JP-A-2003-315556 and JP-A-2004-29824, PALIOCOLOR series (manufactured by BASF), RMM series, etc. (manufactured by Merck), etc. These nematic liquid crystal monomers having a polymerizable group can be used alone or in combination.

The above-mentioned chiral agent can cause the above-mentioned nematic liquid crystal monomer having a polymerizable group to be aligned in a right-handed or left-handed helical orientation, and like the above-mentioned nematic liquid crystal monomer having a polymerizable group, a compound having a polymerizable group is preferable. Examples of the chiral agent include Paliocolor LC756 (manufactured by BASF) and the compound described in JP-A No. 2002-179668. The type of chiral agent determines the direction of circularly polarized light to be reflected, and further, the reflection wavelength of the light reflective layer can be changed depending on the amount of chiral agent added to the nematic liquid crystal. For example, the greater the amount of chiral agent added, the more a light reflecting layer that reflects wavelengths on the shorter wavelength side can be obtained. The amount of chiral agent added varies depending on the type of chiral agent and the wavelength to be reflected, but in order to adjust the center reflection wavelength of the light reflection layer for normal light to a desired wavelength range, for example, nematic liquid crystal having a polymerizable group is added. The amount is preferably about 0.5 to 30 parts by weight, more preferably about 1 to 20 parts by weight, and still more preferably about 3 to 10 parts by weight, based on 100 parts by weight of the monomer.

Furthermore, it is also possible to add a polymerizable compound having no liquid crystallinity and capable of reacting with the nematic liquid crystal monomer having a polymerizable group. Examples of the polymerizable compound include ultraviolet curable resins and the like. Examples of the ultraviolet curable resin include dipentaerythritol hexa(meth)acrylate, a reaction product of dipentaerythritol penta(meth)acrylate and 1,6-hexamethylene diisocyanate, and a triisocyanate having an isocyanuric ring and pentaerythritol trisacrylate. Reaction product with (meth)acrylate, reaction product between pentaerythritol tri(meth)acrylate and isophorone diisocyanate, dipentaerythritol penta(meth)acrylate, dipentaerythritol tetra(meth)acrylate, pentaerythritol tetra(meth) Acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, tris(acryloxyethyl)isocyanurate, tris(methacryloxyethyl)isocyanurate, glycerol triglycidyl reaction product between ether and (meth)acrylic acid, caprolactone-modified tris(acryloxyethyl)isocyanurate, reaction product between trimethylolpropane triglycidyl ether and (meth)acrylic acid, triglycerol di(meth)acrylate, Reaction product of propylene glycol diglycidyl ether and (meth)acrylic acid, polypropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate , triethylene glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, reaction product of 1,6-hexanediol diglycidyl ether and (meth)acrylic acid, 1,6-hexanediol di(meth)acrylate , glycerol di(meth)acrylate, reaction product of ethylene glycol diglycidyl ether and (meth)acrylic acid, reaction product of diethylene glycol diglycidyl ether and (meth)acrylic acid, bis(acryloxyethyl)hydroxyethyl isocyanate Nurate, bis(methacryloxyethyl)hydroxyethyl isocyanurate, reaction product of bisphenol A diglycidyl ether and (meth)acrylic acid, tetrahydrofurfuryl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl (meth)acrylate, 2 -Hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, polypropylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, phenoxyhydroxypropyl (meth)acrylate, acryloylmorpholine, methoxypolyethylene glycol (meth)acrylate, Methoxytetraethylene glycol (meth)acrylate, Methoxytriethylene glycol (meth)acrylate, Methoxyethylene glycol (meth)acrylate, Methoxyethyl (meth)acrylate, Glycidyl (meth)acrylate, Glycerol (meth)acrylate, Ethyl carbitol (meth)acrylate ) acrylate, 2-ethoxyethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, reaction product of butyl glycidyl ether and (meth)acrylic acid, butoxytriethylene Examples include glycol (meth)acrylate and butanediol mono(meth)acrylate, and these can be used alone or in combination. It is important to add these ultraviolet curable resins without liquid crystallinity to an extent that the nematic liquid crystal monomer having a polymerizable group does not lose its liquid crystallinity, and preferably 100 parts by weight of the nematic liquid crystal monomer having a polymerizable group. The amount is preferably about 0.1 to 20 parts by weight, more preferably about 1.0 to 10 parts by weight.

When the above-mentioned nematic liquid crystal monomer having a polymerizable group and the above-mentioned polymerizable compound are both UV-curable, a photopolymerization initiator may be added in order to cure the composition containing them with UV light. . Examples of photopolymerization initiators include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1 (Irgacure 907 manufactured by BASF), 1-hydroxycyclohexyl phenyl ketone (Irgacure 907 manufactured by BASF), Cure 184), 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl)ketone (Irgacure 2959 manufactured by BASF), 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropane -1-one (Merck Darocur 953), 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one (Merck Darocur 1116), 2-hydroxy-2-methyl-1 - Phenylpropan-1-one (Irgacure 1173 manufactured by BASF), acetophenone compounds such as diethoxyacetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-2 - Benzoin compounds such as phenylacetophenone (Irgacure 651 manufactured by BASF), benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3'- Benzophenone compounds such as dimethyl-4-methoxybenzophenone (Nippon Kayaku Kayacure MBP), thioxanthone, 2-chlorothioxanthone (Nippon Kayaku Kayacure CTX), 2-methylthioxanthone, 2,4-dimethylthioxanthone (Kayacure RTX) , isopropylthioxanthone, 2,4-dichlorothioxanthone (Nippon Kayaku Kayacure CTX), 2,4-diethylthioxanthone (Nippon Kayaku Kayacure DETX), or 2,4-diisopropylthioxanthone (Nippon Kayaku Kayacure DITX) Examples include thioxanthone compounds such as. Preferably, for example, Irgacure TPO, Irgacure TPO-L, Irgacure OXE01, Irgacure OXE02, Irgacure 1300, Irgacure 184, Irgacure 369, Irgacure 379, Irgacure e 819, Irgacure 127, Irgacure 907 or Irgacure 1173 (all manufactured by BASF), Particularly preferred are Irgacure TPO, Irgacure TPO-L, Irgacure OXE01, Irgacure OXE02, Irgacure 1300, and Irgacure 907. These photopolymerization initiators may be used alone or in combination in any proportion.

When a benzophenone compound or a thioxanthone compound is used as the photopolymerization initiator, it is also possible to use an auxiliary agent in order to promote the photopolymerization reaction. Examples of the auxiliary agent include triethanolamine, methyldiethanolamine, triisopropanolamine, n-butylamine, N-methyldiethanolamine, diethylaminoethyl methacrylate, Michler's ketone, 4,4'-diethylaminophenone, ethyl 4-dimethylaminobenzoate, Examples include amine compounds such as (n-butoxy)ethyl 4-dimethylaminobenzoate and isoamyl 4-dimethylaminobenzoate.

The amount of the photopolymerization initiator and auxiliary agent added is preferably within a range that does not affect the liquid crystallinity of the composition containing the nematic liquid crystal monomer, but is not limited. The amount added is preferably 0.5 parts by weight or more and 10 parts by weight or less, more preferably 2 parts by weight or more and 8 parts by weight or less, per 100 parts by weight of the ultraviolet curable compound in the composition. . Further, the amount of the auxiliary agent is preferably about 0.5 to 2 times the amount of the photopolymerization initiator.

The above composition may further contain a solvent. The solvent is not particularly limited as long as it can dissolve the liquid crystal compound, chiral agent, etc. used, and examples thereof include methyl ethyl ketone, toluene, methyl isobutyl ketone, cyclopentanone, acetone, anisole, etc., and preferably, Cyclopentanone has good properties. Moreover, these solvents can be added in any ratio, and only one type may be added, or a plurality of solvents may be used in combination. These solvents can be removed by drying in an oven or a drying zone of a film coater line.

The method for producing the reflective layer using the cholesteric liquid crystal includes, for example, applying a nematic liquid crystal monomer having a polymerizable group to reflect a desired wavelength, and adjusting the helical orientation to be right-handed or left-handed. Add the required amount of chiral agent. Next, these are dissolved in a solvent and a photopolymerization initiator is added. After that, this solution is applied onto a polarized light emitting device or a plastic substrate such as a PET film so that the thickness is as uniform as possible, and while the solvent is removed by heating, it becomes cholesteric liquid crystal on the substrate and the desired helical orientation is achieved. Leave it for a certain period of time under such temperature conditions. At this time, by applying an alignment treatment such as rubbing or stretching to the surface of the plastic film before coating, it is possible to make the alignment of the cholesteric liquid crystal more uniform and reduce the haze value of each light-reflecting layer. becomes. Next, while maintaining this orientation, ultraviolet rays are irradiated with a high-pressure mercury lamp or the like to fix the orientation, thereby obtaining the reflective layer. For example, if a chiral agent with a right-handed helical orientation is selected, the resulting light-reflecting layer and the light-reflecting layer will selectively reflect right-handed circularly polarized light, and if a chiral agent with a left-handed helical orientation is selected. Each of the resulting visible light reflective layers and light reflective layers selectively reflects left-handed circularly polarized light. The phenomenon of selectively reflecting specific circularly polarized light is called selective reflection, and the wavelength band that is selectively reflected is called the selective reflection region.

Another method for adjusting the reflectance of the reflective layer to normal light includes changing the thickness of the reflective layer depending on the type of cholesteric liquid crystal or chiral agent, for example. The thickness of the reflective layer varies depending on the type of cholesteric liquid crystal or chiral agent used, but is, for example, about 0.5 to 10 μm. When the reflective layer thus obtained is laminated on the polarized light emitting element to produce the polarized light emitting plate, it can be coated directly onto the polarized light emitting element or coated on a plastic substrate such as a PET film so that the thickness is as uniform as possible. It may also be provided by applying it to the polarized light emitting element and adhering it by transfer using an adhesive or the like. Since the cholesteric liquid crystal layer having a helical orientation has a function of selectively reflecting circularly polarized light, it reflects a specific wavelength as circularly polarized light. Therefore, in order to convert circularly polarized light reflected from a cholesteric liquid crystal layer having a helical orientation into light in another polarization state, for example, linearly polarized light, a 1/4λ retardation plate or the like must be used. In that case, the cholesteric liquid crystal layer with helical orientation can function as a polarizing plate that can reflect linearly polarized light. This can be cited as one preferred form. In other words, the above-mentioned polarized light emitting plate and a general retardation plate, for example, an optical film or layer that can control the phase of the wavelength of ultraviolet light that can be reflected or the wavelength of visible light that can be reflected, are provided. Film is one such form.

In the above-mentioned reflective layer, since the light reflectance is 30 to 100%, it is possible to utilize light with higher efficiency, to express a high degree of polarization in the emission wavelength, and to express high-intensity polarized light emission. , to provide the above optical device. In particular, the ability to use light in the near-ultraviolet to visible range with high efficiency also leads to the ability to efficiently use natural ultraviolet rays, such as sunlight, and furthermore, the ability to emit light in the near-ultraviolet to visible range. When using a light source, polarized light emission can be achieved with high efficiency even with limited light output. As mentioned above, by having a light reflectance of 30 to 100%, highly efficient polarized light emission can be achieved with respect to the absorption band of the polarized light emitting element, preferably 40 to 100%, more preferably 50 to 100%. %, particularly preferably 60 to 100%.

Furthermore, when the reflective layer has a transmittance in the visible range of 50 to 100%, it is possible to provide a polarized light-emitting plate with high transmittance. The high transmittance in the visible range makes it possible to impart transparency to the polarized light-emitting plate while still emitting light. In particular, by emitting polarized light, display using the polarized light becomes possible, and use as a transparent polarized light source becomes possible. For example, when applied to a liquid crystal display device, it can be used for transparent see-through displays, transparent polarized light sources for liquid crystal displays, etc. As mentioned above, when the light transmittance of the reflective layer in the visible range is 50 to 100%, it is higher than the transmittance of 30 to 45%, which is the transmittance of general polarizing plates such as iodine polarizing plates and dye polarizing plates. It is also possible to impart high transparency, more preferably from 60 to 100%, more preferably from 70 to 100%, particularly preferably from 90 to 100%.

A transparent protective layer is further provided on the polarized light emitting element or the polarized light emitting plate in which the polarized light emitting element and the reflective layer are laminated so as to be in contact with the above reflective layer, and the polarized light emitting plate has a transparent protective layer. It is also possible to do this. The transparent protective layer is used to improve the durability and handleability of the polarized light emitting element, and the transparent protective layer does not have any effect on the polarization function exhibited by the polarized light emitting element or the light reflection by the reflective layer. isn't it. The transparent protective layer may be provided on both sides of the polarized light emitting plate, but it may also be provided on either side, that is, only one side, or it may be laminated between the reflective plate and the polarized light emitting element. good.

The transparent protective layer is preferably a transparent protective film having excellent optical transparency and mechanical strength. Further, the transparent protective layer is preferably a film having a layer shape that can maintain its film shape, and is preferably a plastic film that has excellent thermal stability, moisture shielding properties, etc. in addition to transparency and mechanical strength. preferable. Examples of materials for forming such a transparent protective layer include cellulose acetate films, acrylic films, fluorine films such as tetrafluoroethylene/hexafluoropropylene copolymers, polyester resins, and polyolefins. Examples include films made of resins or polyamide resins, and triacetyl cellulose (TAC) films and cycloolefin films are preferably used. The thickness of the transparent protective layer is preferably in the range of 1 μm to 200 μm, more preferably in the range of 10 μm to 150 μm, and particularly preferably in the range of 40 μm to 100 μm. The method for providing the transparent protective layer on the polarized light emitting element is not particularly limited, but for example, it is also possible to overlay the transparent protective layer on the polarized light emitting element and laminate it using a known recipe.

The polarized light emitting plate may further include an adhesive layer for bonding the transparent protective layer and the polarized light emitting element, and the transparent protective layer and reflective layer, respectively. The adhesive constituting the adhesive layer is not particularly limited, but examples include polyvinyl alcohol adhesives, urethane emulsion adhesives, acrylic adhesives, polyester-isocyanate adhesives, etc. Preferably, a polyvinyl alcohol adhesive is used. After forming the adhesive layer, the polarized light emitting plate can be produced by drying or heat treating at an appropriate temperature.

Further, the polarized light emitting plate may be provided with various known functional layers such as an antireflection layer, an antiglare layer, and an additional transparent protective layer on its exposed surface. When producing such layers with various functionalities, it is preferable to apply materials with various functionalities to the exposed surface of the transparent protective layer. It is also possible to attach it to the exposed surface of the transparent protective layer.

Examples of the further transparent protective layer include a hard coat layer made of acrylic resin, polysiloxane resin, etc., and a protective layer made of urethane resin. Further, in order to further improve the single transmittance, an antireflection layer can be provided on the exposed portion of the transparent protective layer. The antireflection layer may be formed by, for example, depositing or sputtering a substance such as silicon dioxide or titanium oxide on the transparent protective layer, or by thinly coating a fluorine-based substance on the transparent protective layer. Can be done.

The polarized light emitting plate, optical film, and display device of the present application can not only be effectively used as a highly efficient polarized backlight for liquid crystal displays, but also be used in see-through displays and polarized light sources that can emit light with high efficiency. Furthermore, it can be utilized as an element, a light source, or a display device that can efficiently convert light such as natural light into polarized light in the visible range. In other words, the polarized light emitting plate, optical film, and display device of the present invention can efficiently emit polarized light especially outdoors.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but these are merely illustrative and do not limit the present invention in any way. Further, "%" and "parts" described below are based on mass unless otherwise specified. In addition, in each structural formula of the compound used in each Example and Comparative Example, the acidic functional group such as a sulfo group is described in the form of a free acid.

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

62.3 parts of the formula (6) 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. To the obtained solution were added 20 parts of 28% aqueous ammonia and 9.0 parts of copper sulfate pentahydrate, and the mixture was stirred at 90°C for 2 hours. 25 parts of sodium chloride was added to the resulting reaction solution, and 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 formula (7) below. By drying this wet cake in a hot air dryer at 80°C, 20.0 parts of a compound (λmax: 376 nm) of the following formula (7), which is a dye capable of emitting polarized light used in the present application, was obtained.

(Preparation of polarized light emitting device)
A polyvinyl alcohol film (manufactured by Kuraray Co., Ltd., VF-PS#7500) 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 mixed with 1.0 parts by weight of the 4,4'-bis-(sulfostyryl)biphenyl disodium aqueous solution (Tinopal NFW Liquid manufactured by BASF) described in Compound Example 5-1 and in Synthesis Example 1. The obtained compound (7) was immersed for 4 minutes in a 45° C. aqueous solution containing 0.4 parts by weight, 1.0 parts by weight of Glauber's salt, and 1500 parts by weight of water. After dipping, the obtained film was stretched in a 3% boric acid aqueous solution at 50° C. for 5 minutes so as to be 5 times the length. The film obtained by stretching was washed with water at room temperature for 20 seconds while maintaining the stretched state, and then dried to obtain a polarized light emitting device of the present application. The Order Parameter of the polarized light emitting device calculated by the above formula (I) was 0.91, the maximum absorption wavelength was 379 nm, and the absorption band was 350 to 410 nm. When this polarized light emitting element was irradiated with ultraviolet rays, it emitted white light, and when the emitted light was confirmed through a general polarizing plate (SKN-18243P manufactured by Polatechno), it was found that when processing the polarized light emitting element, the stretching axis White polarized light emission was observed in the direction, while no polarized light emission was observed in the axis perpendicular to the stretching axis. In other words, a polarized light emitting element is an element that emits linearly polarized light.

(Preparation of polarized light emitting plate using polarized light emitting elements)
A triacetyl cellulose film (ZRD-60 manufactured by Fuji Film Co., Ltd.) containing no ultraviolet absorber was treated with a 1.5N aqueous sodium hydroxide solution at 35°C for 10 minutes, washed with water, and then dried at 70°C for 10 minutes. I let it happen. The triacetyl cellulose film obtained by the alkali treatment was laminated on one side of a polarized light emitting element with 100 parts by weight of water and 4 parts by weight of polyvinyl alcohol resin (NH-26, manufactured by Nippon Vinegar Vipoval Co., Ltd.), and then heated at 70°C for 10 minutes. Dry for a minute. The obtained film had the characteristics of a polarized light emitting film without impairing the optical properties of the obtained polarized light emitting device. The film obtained by drying is coated with an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) as a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element. A reflective film (BL film manufactured by Oike Kogyo Co., Ltd.) having a performance of approximately 88% and visible transmittance of 0% is laminated to form a triacetyl cellulose film/polarized light emitting element/adhesive layer/reflective layer composition. A polarized light emitting plate was obtained.

[Example 2]
In place of the BL film used as a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element in Example 1, a semi-transmissive film having a reflectance of about 67% and a visible transmittance of about 31% from 350 to 780 nm was used. A polarized light emitting plate of the present application was obtained in the same manner except that (HR film manufactured by Oike Kogyo Co., Ltd.) was used as the semi-reflective film.

[Example 3]
Instead of the BL film used as a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element in Example 1, a reflective polarized light having optical properties of about 50% reflectance and about 45% transmittance in the wavelength range of 380 to 780 nm was used. The method of the present application was performed in the same manner except that a plate (DBEF manufactured by 3M Company) was used, and when laminating, the transmission axis of the reflective polarizing plate and the polarized light emission axis of the polarized light emitting element were orthogonal to each other. A polarized light emitting plate was obtained.

[Example 4]
In the same manner as in Example 1 except that a reflective polarizing plate (DBEF manufactured by 3M) was used instead of the BL film used as a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element, and when bonding, A polarized light emitting plate of the present application was obtained in the same manner except that the reflective polarizing plate was laminated so that the transmission axis of the polarized light emitting element was parallel to the polarized light emitting axis of the polarized light emitting element.

[Example 5]
(Preparation of cholesteric liquid crystal layer with fixed helical orientation)
10 parts by weight of polymerizable liquid crystal monomer (LC242, manufactured by BASF), 0.66 parts by weight of chiral agent (LC756, manufactured by BASF), 0.38 parts by weight of polymerization initiator (Irgacure TPO, manufactured by BASF), 24.9 parts by weight of toluene. 0.005 parts by weight of a surfactant (BYK-361N manufactured by BYK Chemie Co., Ltd.) was rubbed on a PET film (Toyobo Co., Ltd.) by the method described in Example 1 of JP-A No. 2002-90743. Coated with a spin coater at 250 rpm for 30 seconds, 2000 rpm for 5 seconds, and 20 rpm for 10 seconds. A single reflective medium was obtained on each PET film by fixing the cholesteric liquid crystal phase by UV irradiation with a high-pressure mercury lamp (manufactured by Harrison Toshiba Lighting Co., Ltd.) at an output of 80 W for 5 seconds. The obtained liquid crystal layer was coated with an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) to a thickness of 20 μm, and after bonding the adhesive layer to glass, the PET film was peeled off to form a liquid crystal layer/adhesive layer/glass. When absolute specular reflection was measured using a spectrophotometer (UV-3600 manufactured by Shimadzu Corporation), the cholesteric liquid crystal layer (A) had a maximum selective reflection wavelength of 394 nm and a reflectance of 41.0% at this wavelength. I found out that I was getting it.

(Preparation of polarized light emitting plate having cholesteric liquid crystal layer with fixed helical orientation)
The BL film used as a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element in Example 1 was replaced with a cholesteric liquid crystal layer (A) having a helical orientation and an adhesive layer, and a triacetylcellulose film/polarized light emitting element was used. A sample having the structure of element/adhesive layer/cholesteric liquid crystal layer (A) was prepared to obtain the polarized light emitting plate of the present application.

[Example 6]
In the preparation of the cholesteric liquid crystal layer with a fixed helical orientation in Example 5, 0.724 parts by weight of the chiral agent was replaced with a cholesteric liquid crystal layer with a helical orientation of 365 nm and a reflectance of 39.4% at this wavelength. A liquid crystal layer (B) was produced, and the BL film used as a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element in Example 1 was bonded to the polarized light emitting plate of Example 5, and the adhesive layer Instead of the cholesteric liquid crystal layer (A) and cholesteric liquid crystal layer (B) having a helical orientation having ) was prepared, and the polarized light emitting plate of the present application was obtained.

[Example 7]
In the production of a polarized light emitting plate using a polarized light emitting element in Example 1, a triacetyl cellulose film (ZRD-60 manufactured by Fuji Film Co., Ltd.) containing no ultraviolet absorber was heated at 35°C in a 1.5 N aqueous sodium hydroxide solution. for 10 minutes, washed with water, and then dried at 70° C. for 10 minutes. The triacetyl cellulose film obtained by the alkali treatment was laminated on one side of a polarized light emitting element with 100 parts by weight of water and 4 parts by weight of polyvinyl alcohol resin (NH-26, manufactured by Nippon Vinegar Vipoval Co., Ltd.), and then heated at 70°C for 10 minutes. The same procedure was carried out until the film was dried for 30 minutes, and the film obtained by drying was coated with an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) as a 1/4λ retardation plate with a retardation value of 95 nm at 380 nm. A polyvinyl alcohol film having a polyvinyl alcohol film having a polyvinyl alcohol film having BL film (manufactured by Ike Kogyo Co., Ltd.) was laminated to obtain the polarized light emitting plate of the present application having a structure of triacetyl cellulose film/polarized light emitting element/adhesive layer/retardation plate/adhesive layer/reflection layer.

[Comparative example 1]
In the production of the polarized light emitting plate of Example 1, the triacetyl cellulose film obtained by alkali treatment was coated on both sides of the polarized light emitting element with 100 parts by weight of water and 4 parts by weight of polyvinyl alcohol resin (NH-26 manufactured by Nippon Vinegar Vipoval Co., Ltd.). A comparative sample was prepared in the same manner as above, except that the film was laminated with a portion of the film in between and dried at 70° C. for 10 minutes to obtain a triacetyl cellulose film/polarized light emitting device/triacetyl cellulose film. The obtained sample had the performance of a polarized light emitting device, and it was confirmed that the optical properties of the polarized light emitting device were not impaired by triacetyl cellulose.

[Comparative example 2]
A comparative example sample was prepared in the same manner as in Example 5, except that a cholesteric liquid crystal layer without helical alignment (liquid crystal layer without selective reflection) was prepared without using a chiral agent.

The obtained polarizing plate was evaluated as follows.
[evaluation]
(h-1) Single transmittance Ts
The single transmittance Ts of each measurement sample was measured using a spectrophotometer (“U-4100” manufactured by Hitachi, Ltd.). Here, the single transmittance Ts is the transmittance of each wavelength when measuring one measurement sample. Measurements were performed over wavelengths from 220 to 780 nm.
(h-2) Polarization degree ρ and visibility correction polarization degree ρy
The polarization degree ρ of each measurement sample was determined by substituting the parallel transmittance Tp and the orthogonal transmittance Tc into the following equation (II). Regarding ρy, the value displayed after measurement by U-4100 was taken as the present result.

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

(h-3) Single transmittance Ys (%) corrected to visibility
The single transmittance Ys (%) of each measurement sample is determined according to JIS Z 8722 for the single transmittance Ts (%) obtained at predetermined wavelength intervals dλ (here, 5 nm) in the wavelength range of 400 to 700 nm in the visible range. : Transmittance corrected for visibility according to 2009. Specifically, it was calculated by substituting the single transmittance Ts (%) into equation (V). In addition, in the following formula (V), Pλ represents the spectral distribution of the standard light (C light source), and yλ represents the 2-degree visual field color matching function.

(Formula 3)

(h-4) Measurement of reflectance Reflectance was determined by relative specular reflection measurement using a spectrophotometer (UV-3600 manufactured by Shimadzu Corporation) at an incident angle and a reflection angle of 5 degrees each with respect to the triacetyl cellulose film. The results obtained for each wavelength were used as the reflectance of Examples and Comparative Examples.

Single transmittance at 375 nm (Ts 375 (%)), degree of polarization at 375 nm (ρ 375 (%)), single transmittance at 390 nm (Ts 390 (%)), 390 nm of the polarized light emitting element obtained in Example 1 degree of polarization (ρ 390 (%)), single transmittance at 465 nm (Ts 465 (%)), degree of polarization at 465 nm (ρ 465 (%)), transmittance corrected for visibility (Ys (%)), Table 1 shows the degree of polarization (ρy (%)) corrected to the visibility. From the results in Table 1, the polarization performance of the obtained polarized light emitting device in the ultraviolet region and the visible region can be seen.

(h-5) Measurement of polarization of emitted light As a light source, an ultraviolet LED 375nm hand light type black light (PW-UV943H-04 manufactured by Nichia Chemical Industries, Ltd.) is used, and the light source is provided with an ultraviolet transmission/visible cut filter. ("IUV-340" manufactured by Isuzu Seiko Glass Co., Ltd.) was installed to cut visible light, and only light in the ultraviolet region was made to enter from the triacetyl cellulose side of the measurement samples obtained in each example and comparative example. The polarized light emitting element is irradiated with light in the ultraviolet region before the reflective medium is irradiated. The light emitted by the polarized light emitting element by light irradiation was measured on the polarized light emitting element side and the light on its reflective medium side (light transmitted from the reflective medium of the polarized light emitting element) using a spectral irradiance meter (manufactured by Ushio Inc. "USR-"). 40"), a polarizing plate ("SKN-18043P" manufactured by Polatechno, thickness 180 μm, Ys is 43%) having a polarizing function for light in the visible and ultraviolet regions is provided in the light receiving part, and, The state of polarized light emission was measured by changing the absorption axis of the polarizing plate. In other words, the light from the ultraviolet light source passes through the ultraviolet transmission/visible cut filter so that only ultraviolet light can be irradiated onto the polarized light emitting element, and the ultraviolet light is then irradiated onto the polarized light emitting element and then the reflective medium. The luminance of the polarized light was measured on both the polarized light emitting element side and the reflective medium side. Lw and Ls were measured by setting the light on the axis of each measurement sample that emits the weakest light as Lw (weak emission axis), and the light emission amount of the strongest emission axis of the measurement sample as Ls (strong emission axis). By checking the amount of light emitted in the visible range when the absorption axes of the measurement sample and a general polarizing plate are parallel and perpendicular, it is possible to evaluate polarized light emission in the visible range of 400 to 700 nm. went.

When the polarized luminescence intensity of the polarized light emitting element obtained in Example 1 was measured, it was confirmed that polarized light was emitted in the visible wavelength range (400 to 700 nm).

Table 2 shows Ls and Lw of the polarized light emitting device obtained in Example 1 at each wavelength of 465 nm, 550 nm, 610 nm, and 670 nm. Table 2 shows that the polarized light emitting elements emit polarized light at each wavelength. In addition, the chromaticity a ^* value and b ^* value at Ls of the polarized light emitting plate determined from JIS Z 8781-4:2013 were 0.77 for a ^* value and -0.8 for b ^* value. . From this, it was found that the polarized light emitting plate emits polarized white light.

(h-6) Measurement of the type (state) of polarized light Regarding the type (state) of polarized light emission, circularly polarized light, elliptically polarized light, and linearly polarized light were measured using the generally known Stokes parameter method. The type of polarized light at 400 to 700 nm was measured using a spectrophotometer (Poxi-Spectra, a spectropolarimeter manufactured by Tokyo Instruments).

Table 3 shows the optical properties of the polarized light emitting plates obtained in Examples 1 to 7 and Comparative Example 1 based on the wavelength showing the maximum degree of polarization. In addition, since the transmittance of Examples 1 and 7 was 0%, the wavelength showing the maximum polarization degree in reflection was defined as the maximum polarization wavelength. On the other hand, Comparative Example 2 had almost the same performance as Comparative Example 1, so its description was omitted. In Table 3, a hyphen (-) indicates that polarized light was not observed due to no light transmission or light reflection.

Comparative Example 1 has the performance of a polarized light emitting element, and its transmittance is 44.43% at the wavelength showing the maximum degree of polarization at the time of absorption, and the type of polarized light when transmitted is It was linearly polarized light, and the light reflection was 0% (equivalent to triacetyl cellulose film). On the other hand, in Example 1, the transmittance was 0%, and a polarized light emitting plate exhibiting reflected polarized light was obtained. On the other hand, in Example 7, by using a 1/4λ retardation plate at the absorption wavelength of the polarized light emitting element in Example 1, a significantly low reflectance of 0.23% was obtained when measured from the polarized light emitting element side. I can see that It can be seen that in Example 2, a polarized light-emitting plate was obtained in which linearly polarized light was obtained in light transmission and light reflection. In addition, in Examples 3 and 4, it can be seen that even if the same reflective polarizing plate is used as the reflecting medium, the transmittance and reflectance of the absorption band of the polarized light emitting plate differ greatly if the axes of the plates are different. . In Examples 5 and 6, it was found that by providing a cholesteric liquid crystal layer having a helical orientation, the transmitted light became circularly polarized light, and reflected light could be provided despite its high transmittance. In addition, in Examples 5 and 6, except for the wavelength reflected by the cholesteric liquid crystal layer having a helical orientation, the transmittance was the same as that in Comparative Example 1, and the linearly polarized light emitted by the polarized light emitting element was was passing through. That is, in Examples 5 and 6, it was found that different polarization states could be provided depending on the wavelength.

Table 4 shows the optical properties of each polarized light emitting plate obtained in Examples 1 to 7 and Comparative Example 1 at the emission wavelength of the polarized light emitting element during light emission and non-light emission. Comparative Example 2 had the same performance as Comparative Example 1, so its description was omitted. The emission intensity (emission brightness) indicates the emission intensity when the emission intensity of Comparative Example 1 is set to 1.00. For example, in Example 1, it was 1.76, which means that the emission intensity was 1.76 times higher. In Table 4, a - (hyphen) indicates that no polarized light was observed due to no light transmission or light reflection.

Comparative Example 1 had the performance of a polarized light emitting element, the emitted light was also linearly polarized light, and the transmittance was as high as 91.22% when no light was emitted. On the other hand, the reflection was 0% (equivalent to triacetylcellulose film). On the other hand, in Example 1, the luminance on the polarized light emitting element side was improved. In Example 7, by using a 1/4λ retardation plate at the absorption wavelength of the polarized light emitting element in Example 1, the luminance of light emitted by the polarized light emitting element was further improved than in Example 1. In Example 2, not only the emission brightness is improved, but also polarized light emission appears on the reflective medium side, so that light emission can also be provided on the back side. In Example 3, not only the emission intensity on the polarized light emitting element side was improved, but also the polarization function was achieved in light transmission and reflected light even when not emitting light. In Example 4, although the emission brightness was improved by 4%, polarized light could also be provided to the reflective medium side. In Examples 5 and 6, the luminance of light emitted to the polarized light emitting element side and the reflective medium side was improved by 14% or more, and the light transmittance when not emitting light was 90% or more. . In addition, in Examples 5 and 6, although the light transmitted to the reflective medium side was circularly polarized, at the wavelength based on the emission of the polarized light emitting element, it was linearly polarized when emitting light, and non-polarized when not emitting light. It was found that the light was transmitted through it. From the above results, the present invention has become a polarized light-emitting plate that can improve the luminance of the polarized light-emitting element and at the same time provide optical characteristics of the absorption wavelength and different polarization states when emitting light and when not emitting light. I understand that.

In addition, using the polarized luminescent plate obtained in Example 3, the polarizing plates on both sides that had been pasted on the liquid crystal cell of a liquid crystal display (Digital Clock Table Blue Clock DO11 Clock A No. 7 manufactured by Daiso Corporation) were peeled off. A display device having a configuration of polarizing plate (SKN-18043 manufactured by Polatechno)/adhesive/liquid crystal cell/adhesive/polarized light emitting plate was produced. Next, ultraviolet rays were irradiated from the polarizing plate side using an ultraviolet LED 375 nm hand light type black light ("PW-UV943H-04" manufactured by Nichia Chemical Industries, Ltd.). The above polarizing plate is attached so that its absorption axis is coaxial with the polarizing plate that was attached to the liquid crystal cell, and the polarizing plate that was attached initially to the opposite surface of the liquid crystal cell is attached. They were laminated so that the transmission axis and the emission axis of the polarized light emitting plate of the present application were aligned on the same axis. When the visibility of the obtained display device was confirmed, it was found that a display device with clearly high brightness was obtained. Furthermore, when a display device was produced in the same manner using the polarized light emitting plate obtained in Example 5, it was found that a display device with high brightness was similarly obtained in Example 5.

From the above, the polarized light emitting plate of the present application can provide polarized light with high brightness at the emission wavelength when used in a polarized light emitting light source or an optical device such as a display device, particularly a liquid crystal display device. Furthermore, since it is possible to obtain a film that has different optical properties in ultraviolet light, visible light, and in its light-emitting and non-light-emitting states, the present invention can provide various features such as security and design.

Claims (5)

In an element capable of emitting polarized light by utilizing absorption of light, the wavelength of the light absorbed by the element is different from the wavelength of the light emitted as polarized light, and the light polarized in a wavelength range of at least 400 to 700 nm is used. A polarized light emitting plate including a polarized light emitting element that emits light and a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element,
The polarized light emitting element includes a polarized light emitting dye,
The polarized light-emitting dye is a compound or a salt thereof having at least one of a stilbene skeleton or a biphenyl skeleton in the dye molecule,
The layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element is a cholesteric liquid crystal layer with fixed helical orientation,
When the light to be absorbed by the polarized light emitting element is incident, the polarized light emitting element and a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element are provided in this order, and the light that can be absorbed by the polarized light emitting element enters the polarized light emitting element. Enters from the element side, emits light from the polarized light emitting element side ,
An optical device characterized in that the light in the absorption wavelength range of the polarized light emitting element that has passed through the layer capable of reflecting light is circularly polarized light . In the polarized light emitting element, the wavelength range of light to be absorbed for use in polarized light emission is in the near ultraviolet to near ultraviolet visible range, and the layer is capable of reflecting light in the absorption wavelength range of the polarized light emitting element. 2. The optical device according to claim 1, wherein the layer is capable of reflecting light in the near-ultraviolet region, near-ultraviolet-visible region, or near-ultraviolet to near-ultraviolet-visible region. 3. The optical device according to claim 1, wherein the layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element is a layer capable of reflecting polarized light. The optical device according to any one of claims 1 to 3 , wherein the polarized light emitting element is an element that emits linearly polarized light. The optical device according to claim 4 , having a liquid crystal display function.