TWI885058B - Optical system and optical device having the same - Google Patents

Abstract

The present invention relates to an optical system having a polarized light emitting element and a filter, wherein at least a part of the wavelengths of the absorbed light and the wavelengths of the emitted light of the polarized light emitting element are different, and the polarized light emitting element has an axial absorption anisotropy in which the amounts of absorbed light are different, and can emit polarized light in the visible region by absorbing light, the filter can absorb light in the visible region having a luminosity correction unit transmittance of 45 to 100%, and the optical system satisfies the relationship of equation (1) or equation (2). A _em-L-λmax× F _em-L＜ 0.6×A _fi-em-λmax＜ 0.35 Equation (1) 0 ＜ TAF _em-L＜ 0.7×TA _fi-emEquation (2)

Description

Optical system and optical device having the same

The present invention relates to an optical system and a display device (display) having the optical system, wherein the optical system emits high-brightness polarized light.

Polarizing plates, which have the function of transmitting or shielding light, are the basic components of liquid crystals and liquid crystal displays (LCDs) that have the function of switching light. The application fields of LCDs have gradually expanded from small machines such as electronic computers and clocks in the early days of the market to laptops, word processors, liquid crystal projectors, liquid crystal televisions, car navigation systems, indoor and outdoor information display devices, measuring machines, etc. In addition, polarizing plates can also be applied to lenses with polarizing functions, and are used in sunglasses with improved visibility, and polarized glasses corresponding to 3D televisions in recent years, etc., and are used in wearable terminals and portable information terminals, and have been partially put into practical use. Polarizing plates have a wide range of uses, and their use environments also range from low to high temperatures, low to high humidity, and low to high light intensity. Therefore, polarizing plates with high polarization performance and excellent durability are sought.

Generally speaking, the polarizing film constituting the polarizing plate can be made by dyeing the film substrate of polyvinyl alcohol or its derivatives with iodine or dichroic dyes (or making the aforementioned substrate contain the aforementioned dyes, etc.), and stretching and orienting it; or, it can be made by dehydrogenating polyvinyl chloride film or dehydrating polyvinyl alcohol film to generate polyene and orienting it. It is known that the polarizing plate composed of such polarizing film generally uses dichroic pigments that have absorption in the visible light region, so the transmittance is reduced. For example, the transmittance of the general polarizing plate sold on the market is 35 to 45%.

In addition, regarding the "polarization degree" which is one of the indicators showing the polarization performance of the polarizing plate, in order to show 100% polarization degree, when there are x-axis and y-axis light in a two-dimensional plane, only one-axis light must be absorbed. Therefore, a general polarizing plate uses iodine or a dichroic dye to absorb only one-axis light. When only one-axis light is absorbed, the amount of light that theoretically penetrates the polarizing plate becomes less than 50% relative to 100% of the incident light. Furthermore, due to the decrease in polarization degree caused by poor orientation of iodine or dichroic dyes, the actual transmittance is lower than 50% due to light loss caused by the film medium, interface reflection on the film surface, etc., and as a result, the transmittance of the conventional polarizing plate is as low as 35 to 45%. In order to solve the problem that the transmittance of a general polarizing plate is as low as 35 to 45%, Patent Document 1 has described a technology for a polarizing plate for ultraviolet light, which is a technology that maintains a certain degree of transmittance in the visible light region while exerting a polarization function. However, although the polarizing plate obtained by this technology has a high transmittance, it does not provide a high degree of polarization in the entire visible light region, but can only be used in devices that display images using light near 400nm.

If a polarizing plate with low transmittance of light in the visible light region or a polarizing plate with low polarization degree is used in a display, for example, the overall brightness or contrast of the display will be reduced. To solve this problem, methods of obtaining polarized light without using conventional polarizing plates have been studied. As for one of the methods, an element that emits polarized light (polarized light emitting element) has been described in patent documents 2 to 6.

[Prior Art Literature] [Patent Literature]

[Patent document 1] WO2005/01527 publication

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

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

[Patent document 4] WO2011/111607 publication

[Patent Document 5] U.S. Patent No. 3,276,316

[Patent Document 6] Japanese Patent Publication No. 4-226162

[Patent Document 7] WO2014/162635 Publication

[Patent document 8] WO2007/138980

[Non-patent literature]

[Non-patent document 1] "Application of functional pigments", published by CMC (Co., Ltd.), 1st edition, supervised by Masahiro Irie, pages 98 to 100

However, the polarized light emitting elements described in Patent Documents 2 to 4 use special metals, such as rare and expensive metals such as ruthenium and other ruthenium-based elements, so the manufacturing cost is high, and the manufacturing is difficult and not suitable for mass production. Furthermore, these polarized light emitting elements are difficult to use in displays because of their low polarization degree, and it is difficult to obtain linearly polarized light. In addition, since only circularly polarized light of a specific wavelength is obtained, the use is limited. For example, even if used in a display, the brightness and contrast are low, and the design of the liquid crystal unit is difficult. Therefore, it is strongly desired to develop a novel polarizing plate that can display polarized light emission, has high polarized light emission, and has high transmittance in the visible light region, and can also be used in liquid crystal displays that require durability in harsh environments, and materials using the polarizing plate. On the other hand, Japanese Patent Documents 5 or 6 disclose an element that emits polarized light by irradiating ultraviolet light. However, the polarization degree and brightness of the luminous element are significantly low, and the contrast of each axis of the so-called polarized light is low, so it is not sufficient for use in displays, etc., and its light resistance is also low.

The purpose of the present invention is to provide an optical system which has polarized light emission, a high degree of polarization, and a high contrast. Another arbitrary purpose of the present invention is to provide an optical system with high transparency. Another arbitrary purpose of the present invention is to provide a display device using the optical system.

The inventors of the present invention have made great efforts to achieve the above-mentioned purpose and have found an optical system having a polarized light emitting element and a filter, wherein the polarized light emitting element is a light absorbing element having at least a part of a different wavelength from the light emitting element and having axes with different light absorption amounts, and can emit polarized light in the visible light region by absorbing light; the filter is a light intensity correction (also called visual sensitivity correction) single body with a transmittance of 45 to 100% and absorbs light in the visible light region; and the optical system having a specific relationship between the polarized light emitting element and the filter can provide polarized light with high transparency and high contrast.

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

[Invention 1] An optical system comprising a polarized light emitting element and a filter, wherein the polarized light emitting element absorbs light of at least a portion of a different wavelength from the light emitted, has axial absorption anisotropy with different amounts of light absorption, and can emit polarized light in the visible light region by absorbing light; the light correction unit of the filter has a transmittance of 45 to 100% and can absorb light in the visible light region; and the optical system satisfies the relationship of formula (1) or formula (2): A _em-L-λmax × F _em-L <0.6 × A _fi-em-λmax <0.35 Formula (1)

In the formula, Aem _-L-λmax represents the absorbance at the maximum absorption wavelength of the axis where the light absorption of the polarized light emitting element is the lowest, _Fem-L represents the quantum yield at the axis where the light absorption of the polarized light emitting element is the lowest, and _Afi-em-λmax represents the absorbance of the filter at the maximum emission wavelength of the polarized light emitting element. 0<TAFem _-L <0.7×TAfi _-em Formula (2)

In the formula, TA _fi-em represents the value of the accumulated absorbance of each wavelength of the filter in the wavelength range where the polarized light emitting element emits light, and TAF _em-L represents the product of the absorbance of each wavelength on the axis where the light absorption of the polarized light emitting element is the lowest and the quantum yield on the axis where the light absorption of the polarized light emitting element is the lowest, accumulated in the light absorption wavelength range of the aforementioned polarized light emitting element.

[Invention 2] The optical system described in Invention 1 at least satisfies the aforementioned formula (2).

[Invention 3] An optical system as described in Invention 1 or 2, wherein the transmittance of the photometric correction unit of the aforementioned filter is 50 to 99.9%.

[Invention 4] An optical system as described in any one of Inventions 1 to 3, wherein the filter is a polarizing element satisfying formula (3): A _em-L-λmax × F _em-L <0.6 × A _{Pol-Kz-em-L-λmax} <0.7 Formula (3)

In the formula, A _em-L-λmax represents the absorbance at the maximum absorption wavelength on the axis where the light absorption of the polarized light emitting element is the lowest, F _em-L represents the quantum yield on the axis where the light absorption of the polarized light emitting element is the lowest, and A _{Pol-Kz-em-L-λmax} represents the absorbance at the highest absorption axis of the polarized light emitting element at the wavelength with the maximum emission on the axis where the emission of the polarized light emitting element is the weakest.

[Invention 5] An optical system as described in any one of Inventions 1 to 4, wherein the filter is a polarizing element satisfying formula (4): 0<TAF _em-L <0.7×TA _pol-Kz-em Formula (4)

In the formula, TApol _-Kz-em represents the value of the accumulated absorbance of each wavelength of the polarizing element at the highest absorption axis within the wavelength range in which the polarizing element emits light, and TAFem _-L represents the same as formula (2).

[Invention 6] An optical system as described in any one of Inventions 1 to 5, wherein the filter is a polarizing element, and the polarizing element and the filter are provided in such a manner that the axis of the weakest light emission of the polarizing element and the axis of the high absorbance of the polarizing element are parallel.

[Invention 7] An optical system as described in any one of Inventions 1 to 6, wherein the hue of the aforementioned filter is -5<a*<+3 and b*<±3.

[Invention 8] An optical system as described in any one of Inventions 1 to 7, wherein the polarized light emitting element contains a polarized light emitting pigment, and the polarized light emitting pigment is directional.

[Invention 9] An optical system as described in any one of Inventions 1 to 8, wherein the polarized light emitting element emits polarized light by absorbing light in the ultraviolet region to the near-ultraviolet visible region.

[Invention 10] An optical system as described in any one of Inventions 1 to 9, wherein the polarized light emitting element has a maximum absorption wavelength of light in the ultraviolet region to the near-ultraviolet visible light region.

[Invention 11] An optical system as described in any one of Inventions 1 to 10, wherein the aforementioned polarized light emitting element and the aforementioned filter are layered.

[Invention 12] An optical system as described in any one of Inventions 1 to 11, which has a phase difference plate.

[Invention 13] An optical system as described in any one of Inventions 1 to 12, wherein the filter is located on the viewing side.

[Invention 14] A display device having an optical system as described in any one of Inventions 1 to 13.

The optical system of the present invention can emit polarized light with high contrast. In some aspects, it can further have high transparency. Furthermore, in some aspects, it can provide high contrast and high transparency in a display device using the optical system.

Figure 1 is a graph showing the transmittance (Ky and Kz) of polarized light emitting elements A to C at various wavelengths.

Figure 2 is a graph showing the luminous intensity ratio of polarized light emitting plates A to C at various wavelengths.

Figure 3 is a graph showing the polarization degree of polarizing plates A to C at various wavelengths.

Figure 4 is a graph showing the transmittance (Ky and Kz) of polarizers A to E at various wavelengths.

Figure 5 is a graph showing the transmittance of filters F to H at various wavelengths.

Figure 6 is a graph showing the transmittance (Ky and Kz) of the ultraviolet polarizing plate J at each wavelength.

The optical system of the present invention is provided with a polarized light emitting element and a filter that absorbs light in the visible light region (also referred to as a "visible light absorption filter" or simply a "filter"). The polarized light emitting element absorbs light of at least a portion of a different wavelength from the light emitted, has axes with different light absorption amounts, and can emit polarized light in the visible light region by absorbing light; the filter is a photometric correction unit with a transmittance of 45 to 100% and absorbs light in the visible light region; the optical system satisfies the relationship of formula (1) or formula (2).

A _em-L-λmax ×F _em-L <0.6×A _fi-em-λmax <0.35 Formula (1)

In the formula, A _em-L-λmax represents the absorbance at the wavelength of maximum absorption on the axis where the light absorption of the polarized light emitting element is the lowest, F _em-L represents the quantum yield on the axis where the light absorption of the polarized light emitting element is the lowest, and A _fi-em-λmax represents the absorbance of the filter before the wavelength where the polarized light emitting element shows the maximum emission wavelength.

0<TAF _em-L <0.7×TA _fi-em formula (2)

In the formula, TA _fi-em represents the value of the accumulated absorbance of each wavelength of the aforementioned filter within the wavelength range in which the polarized light emitting element emits light, and TAF _em-L represents the product of the absorbance of each wavelength on the axis where the light absorption of the polarized light emitting element is the lowest and the quantum yield on the axis where the light absorption of the polarized light emitting element is the lowest, accumulated within the light absorption wavelength range of the polarized light emitting element.

Here, "the wavelength of the absorbed light is different from at least a part of the wavelength of the emitted light" means that the wavelength range of the light absorbed by the polarized light emitting element is completely or partially different from the wavelength range of the polarized light emitting light. The so-called polarized light that can emit the visible light region by absorbing light means an element that can perform polarized light emission by absorbing light, and emits polarized light in the wavelength range of at least 400 to 700nm. In addition, an element that absorbs light of a specific wavelength and emits light of a wavelength different from the wavelength of the absorbed light is also called a wavelength conversion element, but in the patent scope and specification of this application, it is called a "polarized light emitting element" in terms of the point of converting the absorbed light into polarized light emission.

The polarized light emitting element used in the present invention contains a compound having a light absorbing function (such as the polarized light emitting pigment described below) in the element, and is not particularly limited as long as the light wavelength conversion function of the compound can be utilized to emit polarized light, or a compound having a function of emitting polarized light can be formed as a layer. If it is limited in a manner of having a light absorbing function at a specific wavelength, it can be optically designed to transmit light other than the wavelength, and is not limited to the full wavelength region of visible light, but a light emitting element with high transmittance only at a specific wavelength can be provided. It is particularly preferred that the element that absorbs light and emits polarized light has an absorption wavelength of light in the ultraviolet region to the near ultraviolet visible light region. By having an absorption wavelength of light in the ultraviolet region to the near ultraviolet visible light region, the light-emitting element can be illuminated by light that is invisible to the eyes or difficult to see, and can provide a light-emitting element that has a high transmittance in visual perception and emits polarized visible light. As for the preferred form of the polarized light-emitting element that emits polarized light, one of the preferred forms of the present application is: the absorption region of light is at least in the ultraviolet region to the near ultraviolet visible light region, for example, in the range of 300 to 430nm, and the emission wavelength of the polarized light is at least in the wavelength range of 400 to 700nm in the visible light region.

The polarized light emitting element used in the present invention absorbs light in the range of the ultraviolet region to the near ultraviolet visible light region, and emits polarized light having a luminescence spectrum peak in at least part or all of the visible light region set to the range of 400 to 700 nm. In the present application, preferably, it is light in the ultraviolet region to the near ultraviolet visible light region that is invisible to the human eye or difficult to see clearly, that is, light of 300 to 430 nm. Moreover, from the perspective of improving visibility, the absorption wavelength of the light of the polarized light emitting element is more preferably 340 to 420 nm, more preferably 350 to 410 nm, and particularly preferably 350 to 400 nm. The light in the ultraviolet region to the near ultraviolet visible light region irradiated on the polarized light emitting element may or may not be polarized, but may have polarization. One method of obtaining the above-mentioned polarized light emitting element is to obtain it by at least including the substrate and polarized light emitting pigment described below.

The polarized light emitted by the polarized light emitting element used in the present invention can be listed as follows: linear polarized light, circular polarized light, elliptical polarized light, etc. However, from the perspective of display device design, linear polarized light is preferred. The so-called linear polarized light can also be expressed as a wave in the direction of a certain axis. By using the polarized light emitting element to emit linear polarized light, that is, by emitting light polarized on one axis, it becomes easy to design display devices such as liquid crystal displays. This is also suitable for industrial use as most commercially available liquid crystal displays and polarized lenses use iodine-based polarizing plates or dye-based polarizing plates corresponding to linear polarization.

In order to emit linearly polarized light, for example, it can be achieved by orienting the polarized light emitting dye described later in the same direction in the substrate. In addition, by orienting the polarized light emitting dye in the same axis, polarized light with the same axis can be emitted, and the intensity of the light being conducted can be increased, and the dye can provide light with a stronger luminous intensity than it theoretically originally has. That is, when the polarized light emitting dye is oriented in the same direction in the substrate, linearly polarized light with higher brightness can be provided. In addition, the linear polarizer can be transformed into various polarizations by combining a phase difference plate, which can facilitate optical design. For example, circularly polarized light can be emitted by setting a 1/4 λ plate for the emission wavelength, or the emitted linearly polarized light can be rotated 90° by setting a 1/2 λ plate for the emission wavelength. As described above, polarization can be adjusted in various ways by using a phase difference plate, so providing a phase difference plate for a polarized light emitting element can be regarded as one of the preferred forms of the present application.

The polarized light emitting element that can be used in the present invention is, for example, a polarized light emitting element that includes a polarized light emitting pigment, performs linear polarized light emission by orienting the polarized light emitting pigment, and exhibits axial absorption anisotropy at the wavelength of absorbed light. The so-called axial absorption anisotropy means having an axis of strong absorption and an axis of weak absorption. For example, when the polarized light emitting element absorbs light from the ultraviolet region to the near-ultraviolet visible region, and uses the absorbed light to emit polarized light in the visible region, it is a phenomenon that the orientation direction of the polarized light emitting pigment in the absorbed light and the absorption amount of light in a direction opposite to the orientation direction are different. Generally speaking, when having this axial absorption anisotropy, it is also called having dichroism. The magnitude of the axial absorption anisotropy (dichroism) obtained by orienting the polarized light-emitting pigment is expressed as the dichroic ratio (hereinafter also referred to as "RD"). The so-called dichroic ratio refers to the ratio of the absorption amount of the highest absorption axis to the absorption amount of the lowest absorption axis. Generally, if it is 3 or more, it is expressed as having a dichroic ratio (axial absorption anisotropy), and the higher the better, preferably 5 or more, more preferably 10 or more, particularly preferably 20 or more, and even more preferably 30 or more. If it is around 50, it means that light with a high degree of polarization (or polarization rate) is emitted. If it is around 70, it means that the dichroic ratio (anisotropy) is more evident, and it also means that the appearance of the dichroic ratio can emit polarized light with a higher degree of polarization. In addition, the orientation degree of the pigment can also be calculated from the value of the two-color ratio [hereinafter referred to as the order parameter]. The orientation degree of the pigment is a value calculated according to the following formula (5), and is preferably 0.80 or more and 1.00 or less, and is particularly preferably 0.9 or more and 1.00 or less.

Order Parameter=(RD-1)/(RD+2) Formula (5)

(Manufacturing method of polarized light emitting element)

The method for manufacturing the polarized light emitting element that can be used in the present invention can be manufactured, for example, by the following steps: a step of preparing a substrate; a swelling step of immersing the substrate in a swelling liquid and causing the substrate to swell; a dyeing step of immersing the swollen substrate in a dyeing solution containing at least one of the above-mentioned polarized light emitting pigments, so that the substrate adsorbs the polarized light emitting pigment; a crosslinking step of crosslinking the substrate adsorbed with the polarized light emitting pigment. The substrate is immersed in a solution containing boric acid to crosslink the polarized light emitting pigment in the substrate; the stretching step is to uniaxially stretch the substrate with the crosslinked polarized light emitting pigment in a certain direction to align the polarized light emitting pigment in a certain direction; further, a cleaning step and/or drying step is required, the aforementioned cleaning step is to clean the stretched substrate with a cleaning solution; the aforementioned drying step is to dry the washed substrate.

<Base material>

The substrate may be a polymer film for absorbing and orienting the polarized light emitting dye described later. The polymer film is preferably a hydrophilic polymer film obtained by forming a hydrophilic polymer capable of absorbing a polarized light emitting dye having a general dichroic property, and more preferably a hydrophilic polymer film obtained by forming a hydrophilic polymer capable of absorbing a dye having a stilbene skeleton or a dye having a biphenyl skeleton. The hydrophilic polymer is not particularly limited, but for example, polyvinyl alcohol resins and starch resins are preferred, and from the viewpoint of dyeability, processability, and crosslinking of the polarized light emitting dye having the above dichroic property, polyvinyl alcohol resins and their derivatives are preferred. The polyvinyl alcohol resin and its derivatives include, for example, polyvinyl alcohol or its derivatives, and any of these modified with olefins such as ethylene and propylene, or unsaturated carboxylic acids such as crotonic acid, acrylic acid, methacrylic acid, and maleic acid. Among them, from the point of view of the adsorption and orientation of the polarized light-emitting pigment having dichroism, a film formed of polyvinyl alcohol resin and its derivatives is preferably used. The substrate can be, for example, a film formed of a commercially available polyvinyl alcohol resin or its derivatives, or can be produced by film-forming a polyvinyl alcohol resin. The film-forming method of polyvinyl alcohol resin is not particularly limited. For example, the following methods can be used: melt extrusion of aqueous polyvinyl alcohol, flow film-forming method, wet film-forming method, gel film-forming method (temporarily cooling the polyvinyl alcohol aqueous solution to gel, then extracting and removing the solvent), casting film-forming method (flowing the polyvinyl alcohol aqueous solution on a substrate and drying), and methods combining these methods and other well-known film-forming methods. The thickness of the substrate is usually 10 to 100 μm, preferably about 20 to 80 μm.

The following describes the method for producing a polarized light emitting element using a film made of polyvinyl alcohol resin and its derivatives as an example.

(Swelling step)

The swelling step is preferably carried out by immersing the above-mentioned substrate in a swelling liquid at 20 to 50°C for 30 seconds to 10 minutes, and the swelling liquid is preferably water. The elongation ratio of the substrate is preferably adjusted to 1.00 to 1.50 times, and more preferably adjusted to 1.10 to 1.35 times.

(Dyeing step)

The dyeing step is to make the substrate obtained through the swelling step adsorb one or more polarized light emitting dyes described below. The dyeing step is not particularly limited as long as it is a method that can make the polarized light emitting dye adsorbed on the substrate, and for example, it can be listed as: a method of immersing the substrate in a dyeing solution containing a polarized light emitting dye; or, a method of coating a dyeing solution containing a polarized light emitting dye on the substrate, etc., but the method of immersing 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 it is a concentration that sufficiently adsorbs the polarized light emitting dye in the substrate, but for example, the concentration of the polarized light emitting dye in the dyeing solution is preferably 0.0001 to 1 mass %, and more preferably 0.0001 to 0.5 mass %. The temperature of the dyeing solution in the dyeing step is preferably 5 to 80°C, more preferably 20 to 50°C, and particularly preferably 40 to 50°C. In addition, the time for immersing the substrate in the dyeing solution can be appropriately adjusted, and is preferably adjusted between 30 seconds and 20 minutes, and more preferably between 1 and 10 minutes. The polarized light-emitting pigment contained in the dyeing solution can be used alone or in combination of two or more. The polarized light-emitting pigment has different luminescent colors due to differences in its pigment structure, so by containing two or more polarized light-emitting pigments in the substrate, the luminescent color produced can be appropriately adjusted to various colors. In addition, as needed, the dyeing solution may also contain one or more organic dyes and/or fluorescent dyes in addition to the polarized light-emitting pigments.

(Polarized light emitting pigment)

The polarized light emitting dyes include, for example, compounds or salts thereof that have at least one of a stilbene skeleton or a biphenyl skeleton in the molecule and emit light by utilizing the absorbed light, and those that emit fluorescence or phosphorescence, and those that emit fluorescence are preferred. The polarized light emitting dyes have a fluorescence emitting function, and the dyes have 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 emitting properties, and have a high dichroic ratio at the absorption wavelength by orienting them. These are derived from the characteristics of the above-mentioned skeletons. These characteristics can be further improved. In order to adjust the absorption wavelength and emission wavelength, light resistance, moisture resistance, ozone resistance and other various fastness and solubility and other characteristics, any substituent can be further introduced into the above-mentioned skeletons. When the type of substituent or the substitution position is poorly selected in the introduction of substituents, even if a high degree of polarization is achieved, there is a situation where the luminous light amount is significantly reduced, as in the known dye-based polarizing plate. Therefore, in order to make the fluorescent luminescence characteristics excellent and have a high dichroic ratio, the type of substituent or the selection of the substitution position becomes particularly important. In addition, the above-mentioned polarized light emitting pigment can be used alone or in combination of two or more.

(a) Polarized light-emitting pigment with a diphenylethylene skeleton

The above-mentioned pigment having a diphenylethylene skeleton is preferably a compound represented by the following formula (S) or a salt thereof.

In formula (S), L and M each independently represent a nitro group, an amino group which may have a substituent, a carbonylamide group which may have a substituent, a naphthotriazole group which may have a substituent, an alkyl group having 1 to 20 carbon atoms which may have a substituent, a vinyl group which may have a substituent, an amide group which may have a substituent, a urea group which may have a substituent, an aryl group which may have a substituent, or a carbonyl group which may have a substituent.

It is known that the pigment having a diphenylethylene skeleton represented by the above formula (S) has fluorescence luminescence and can obtain dichroism by orientation, but this is mainly derived from the diphenylethylene skeleton, and any substituent can be further introduced.

The amino groups which may have a substituent include, for example, unsubstituted amino groups, methylamino groups, ethylamino groups, n-butylamino groups, tert-butylamino groups, n-hexylamino groups, dodecylamino groups, dimethylamino groups, diethylamino groups, di-n-butylamino groups, ethylmethylamino groups, ethylhexylamino groups, etc., which may have a substituent, and alkylamino groups having 1 to 20 carbon atoms; phenylamino groups, diphenylamino groups, naphthylamino groups, N-phenyl-N-naphthylamino groups, etc., which may have a substituent, and arylamino groups having 1 to 20 carbon atoms; methylcarbonylamino groups, ethylcarbonylamino groups, n-butyl-carbonylamino groups, etc., which may have a substituent, and substituted arylcarbonylamino groups such as phenylcarbonylamino, biphenylcarbonylamino and naphthylcarbonylamino; alkylsulfonylamino groups having 1 to 20 carbon atoms such as methylsulfonylamino, ethylsulfonylamino, propylsulfonylamino and n-butylsulfonylamino; arylsulfonylamino groups having substituted arylsulfonylamino groups such as phenylsulfonylamino and naphthylsulfonylamino, etc., preferably alkylcarbonylamino groups having 1 to 20 carbon atoms which may have a substituent, arylcarbonylamino groups which may have a substituent, alkylsulfonylamino groups having 1 to 20 carbon atoms, and arylsulfonylamino groups which may have a substituent. Furthermore, the substituents in the above-mentioned alkylamino group with 1 to 20 carbon atoms which may have a substituent, arylamino group with 1 to 20 carbon atoms which may have a substituent, alkylcarbonylamino group with 1 to 20 carbon atoms which may have a substituent, arylcarbonylamino group with 1 to 20 carbon atoms which may have a substituent, alkylsulfonylamino group with 1 to 20 carbon atoms, and arylsulfonylamino group with 1 to 20 carbon atoms which may have a substituent are not particularly limited, but examples thereof include: nitro group, cyano group, hydroxyl group, sulfonic acid group, phosphoric acid group, carboxyl group, carboxylalkyl group, halogen atom, alkoxy group, aryloxy group, etc.

Examples of the above-mentioned carboxylalkyl group include methylcarboxyl, ethylcarboxyl, etc. Examples of the halogen atom include fluorine atom, chlorine atom, bromine atom, iodine atom, etc. Examples of the alkoxy group include methoxy, ethoxy, propoxy, etc. Examples of the aryloxy group include phenoxy, naphthoxy, etc.

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 ), and N-phenyl-carbonylamide group (-CONHC ₆ H ₅ ).

The naphthotriazole group that may have a substituent may include, for example, benzotriazole group, naphthotriazole group, etc.

The alkyl groups with 1 to 20 carbon atoms that may have substituents include, for example: straight chain alkyl groups such as methyl, ethyl, n-butyl, n-hexyl, n-octyl, and n-dodecyl; branched chain alkyl groups such as isopropyl, sec-butyl, and tert-butyl; cyclic alkyl groups such as cyclohexyl and cyclopentyl, etc.

Examples of the vinyl groups that may have substituents include: vinyl, methylvinyl, ethylvinyl, divinyl, pentadienyl, etc.

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

The above-mentioned aryl groups that may have substituents include, for example, phenyl, naphthyl, anthracenyl, biphenyl, etc.

The carbonyl groups that may have substituents include, for example, methylcarbonyl, ethylcarbonyl, n-butyl-carbonyl, phenylcarbonyl, etc.

There are no particular restrictions on the substituents in the above-mentioned carbonylamide group which may have a substituent, naphthotriazole group which may have a substituent, 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, urea group which may have a substituent, aryl group which may have a substituent, and carbonyl group which may have a substituent, but they may be the same as the substituents described in the above-mentioned paragraph of amino group which may have a substituent.

The pigment having a diphenylethylene skeleton represented by the above formula (S) is preferably a pigment represented by the following formula (S-a) or a salt thereof or a pigment represented by the following formula (S-b) or a salt thereof. By using these pigments, it is possible to emit light of various colors by combining multiple types of the pigments, for example, a polarized light-emitting element emitting white light can be obtained.

In formula (S-a), R represents a hydrogen atom, a halogen atom, a hydroxyl group, a carboxyl group, a nitro group, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or an amino group which may have a substituent, and n represents an integer from 0 to 3.

In formula (S-b), Y 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.

In the above formula (Sa), the halogen atom may be the same as described above. The alkyl group which may have a substituent may be the same as described in the above paragraph of the alkyl group having 1 to 20 carbon atoms which may have a substituent. The alkoxy group which may have a substituent is preferably a methoxy group or an ethoxy group. The amino group which may have a substituent may be the same as described above, preferably a methylamino group, a dimethylamino group, an ethylamino group, a diethylamino group, or a phenylamino group. The substituent R may be bonded to any carbon of the naphthyl ring in the naphthotriazole ring, but when the carbon condensed with the triazole ring is at the 1st and 2nd positions, it is preferably bonded to the 3rd, 5th or 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 naphthyl ring in the naphththotriazole ring. Regarding the substitution position in the naphthyl ring of the -(SO ₃ H) group, when n=1, and the carbon atoms condensed with the triazole ring are the 1st and 2nd positions, the 4th, 6th, or 7th positions are preferred; when n=2, the 5th and 7th positions, and the 6th and 8th positions are preferred; when n=3, the combination of the 3rd, 6th, and 8th positions is preferred. In particular, it is preferred 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 a nitro group is preferred. The amino group which may have a substituent may be the same as described above, and is preferably an alkylcarbonylamino group having 1 to 20 carbon atoms which may have a substituent, an arylcarbonylamino group which may have a substituent, an alkylsulfonylamino group having 1 to 20 carbon atoms, or an arylsulfonylamino group which may have a substituent.

In the above formula (S-b), Y is preferably an aryl group which may have a substituent, more preferably a naphthyl group which may have a substituent, and particularly preferably a naphthyl group substituted with an amino group or a sulfo group as a substituent. Z represents the same substituent as described for X in the above formula (S-a), preferably a nitro group.

As for the compounds represented by the above formula (S), for example, Kayaphor series (manufactured by Nippon Kayaku Co., Ltd.), Whitex series such as Whitex RP (manufactured by Sumitomo Chemical Co., Ltd.), etc. are listed. In addition, the following are examples of compounds represented by formula (S), but they are not limited to these.

(b) Polarized light-emitting pigment with biphenyl skeleton

The above-mentioned pigment having a biphenyl skeleton is preferably a compound represented by the following formula (B) or a salt thereof.

In formula (B), P and Q each independently represent a nitro group, an amino group which may have a substituent, a carbonylamide group which may have a substituent, a naphthotriazole group which may have a substituent, an alkyl group having 1 to 20 carbon atoms which may have a substituent, a vinyl group which may have a substituent, an amide group which may have a substituent, a urea group which may have a substituent, an aryl group which may have a substituent, or a carbonyl group which may have a substituent.

In the above formula (B), P and Q each independently represent a nitro group, an amino group which may have a substituent, a carbonylamide group which may have a substituent, a naphthotriazole group which may have a substituent, an alkyl group having 1 to 20 carbon atoms which may have a substituent, a vinyl group which may have a substituent, an amide group which may have a substituent, an urea group which may have a substituent, or an aryl group which may have a substituent, or a carbonyl group which may have a substituent, but are not necessarily limited to these. The amino group which may have a substituent, the carbonylamide group which may have a substituent, the naphthotriazole group which may have a substituent, the alkyl group having 1 to 20 carbon atoms which may have a substituent, the vinyl group which may have a substituent, the amide group which may have a substituent, the aryl group which may have a substituent, and the carbonyl group which may have a substituent may be the same as those mentioned above.

The compound represented by the above formula (B) is preferably the compound represented by the following formula (B-a).

In formula (Ba), 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 alkoxy group having 1 to 4 carbon atoms, an aralkyloxy group, an alkenyloxy group, an alkylsulfonyl group having 1 to 4 carbon atoms, an arylsulfonyl group having 6 to 20 carbon atoms, a carboxamide group, a sulfonamide group, or a carboxyalkyl group, and j or k each independently represents an integer from 0 to 2.

The preferred substitution position of the -(SO ₃ H) group in the above formula (Ba) is not particularly limited, but when the vinyl group is at the 1-position, the 2-position and 4-position are preferred, and the 2-position is particularly preferred.

In the above formula (B-a), the carboxyl alkyl group may be the same as above.

Examples of the alkyl group having 1 to 4 carbon atoms include methyl, ethyl, propyl, n-butyl, sec-butyl, t-butyl, and cyclobutyl. Examples of the alkoxy group having 1 to 4 carbon atoms include methoxy, ethoxy, propoxy, n-butoxy, sec-butoxy, t-butoxy, and cyclobutoxy. 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, ethylsulfonyl, propylsulfonyl, n-butylsulfonyl, sec-butylsulfonyl, t-butylsulfonyl, and cyclobutylsulfonyl. The above-mentioned arylsulfonyl groups with carbon numbers of 6 to 20 can be exemplified as: phenylsulfonyl, naphthylsulfonyl, biphenylsulfonyl, etc.

In the above formula (Ba), 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.

The synthesis method of the polarized light-emitting pigment represented by the above formula (B-a) can be prepared by a known method, for example, by condensing 4-nitrobenzaldehyde-2-sulfonic acid with a phosphonate and then reducing the nitro group.

The compound represented by the above formula (B) may be the compound described in Patent Document 6, and specifically, the following compounds are exemplified.

(c) Luminescent pigment with coumarin skeleton

The compound having a coumarin skeleton that becomes a luminescent pigment is preferably a compound represented by the following formula (C) or a salt thereof.

In formula (C), A represents a coumarin compound which may have a substituent, X represents a sulfo group or a carboxyl group, and p represents an integer from 1 to 3. The coumarin compound represented by formula (C) represents a water-soluble luminescent pigment having a coumarin skeleton.

When the above formula (C) is the following formula (Ca), the contrast of polarized light emission is further improved, so it is a preferred example. In formula (Ca), the groups _R5 and _R6 are each independently a alkyl group having 1 to 10 carbon atoms, Q is a sulfur atom, an oxygen atom, or a nitrogen atom, and q is an integer from 1 to 3.

As described above, the luminescent pigment of the water-soluble coumarin compound represented by formula (C) or formula (C-a) in the present invention has at least one coumarin skeleton in the molecule. The luminescent pigment of the water-soluble coumarin compound in the present invention exhibits polarized luminescence by irradiating ultraviolet light and visible light (specifically, light of 300 to 600 nm) because it has a coumarin skeleton.

The salts of the compounds represented by the above formulae (S), (B) and (C) are salts formed with inorganic cations or organic cations. Inorganic cations are alkaline metals, such as lithium, sodium, potassium, and ammonium ions (NH ₄ ⁺ ). Organic cations are, for example, organic ammonium represented by the following formula (A).

In formula (A), _Z1 to _Z4 each independently represent a hydrogen atom, an alkyl group, a hydroxyalkyl group, or a hydroxyalkoxyalkyl group, and at least one of _Z1 to _Z4 is a group other than a hydrogen atom.

Specific examples of _Z1 to _Z4 include _C1 - _C6 alkyl groups such as methyl, ethyl, butyl, pentyl and hexyl, preferably _C1 - _C4 alkyl groups; hydroxy C1-C6 alkyl groups such as hydroxymethyl, 2-hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl, 4-hydroxybutyl, 3-hydroxybutyl and 2-hydroxybutyl, preferably _{hydroxy C1} - _C4 alkyl groups; and hydroxy C1-C6 alkoxy C1- _C6 alkyl groups such as hydroxyethoxymethyl, 2-hydroxyethoxyethyl, 3-hydroxyethoxypropyl, ₃ -hydroxyethoxybutyl and 2 _- hydroxyethoxybutyl, preferably hydroxy _C1 - _C4 alkoxy _C1 - _C6 alkyl groups _{. 4} alkyl, etc.

Among these inorganic cations and organic cations, the more preferred ones include: sodium ions, potassium ions, lithium ions, ammonium monoethanolate ions, ammonium diethanolate ions, ammonium triethanolate ions, ammonium monoisopropoxide ions, ammonium diisopropoxide ions, ammonium triisopropoxide ions and cations such as ammonium. Among these, lithium ions, ammonium ions and sodium ions are more preferred.

As for other polarized light emitting pigments that can be used in the above polarized light emitting elements, for example, they can be listed as: 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 can be free acids, or alkaline metal salts (such as Na salts, K salts, Li salts), ammonium salts or amine salts.

The above-mentioned polarized light emitting pigments can be oriented individually or in combination of two or more. When two or more polarized light emitting pigments are used in combination, various luminous colors can be adjusted by adjusting the mixing ratio between the polarized light emitting pigments. For example, by adjusting the absolute values of the chromaticity a* value and the b* value to be 5 or less, the polarized light emitted by the polarized light emitting element can be made white. The above-mentioned chromaticity a* value and b* value are based on the spectral distribution measured for the light emitted from the polarized light emitting element when the light is incident on each polarized light emitting element, and are obtained in accordance with JIS Z 8781-4:2013. The method of expressing the color of an object determined in accordance with JIS Z 8781-4:2013 is equivalent to the method of expressing the color of an object established by the International Commission on Illumination (abbreviated as "CIE"). The measurement of chromaticity a* and b* values is usually performed by irradiating the measurement sample with natural light, but in the specification and patent scope of this application, the chromaticity a* and b* values can be determined by irradiating the polarized light emitting element with short-wavelength light such as the ultraviolet light region 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, still more preferably 2 or less, and particularly preferably 1 or less. In addition, 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, and particularly preferably 1 or less. If the absolute values of a* and b* are independently 5 or less, the human eye can perceive it as white, and if they are both 5 or less, it can be perceived as better white emission. Since the polarized light emitted is white, it can be used as a natural light source such as sunlight, a light source for a paper-white terminal, etc., and has the advantage of being easy to use even when placed in a display using a color filter. As for the light intensity, if the light can be perceived by the eyes, it can be used in a display without any problem. In particular, for this application, it is important that the light emitted has a high degree of polarization and a high transmittance in the visible light region.

(D) Other pigments

The polarized light emitting element preferably includes a single or multiple pigments or salts thereof having a stilbene skeleton, a biphenyl skeleton or a coumarin skeleton, but may further include one or more other organic dyes or other fluorescent dyes as needed for the purpose of adjusting the color, etc., within the range that does not hinder the polarized light emitting function. Other organic dyes are not particularly limited as long as they can control the color (hue) or luminescent color of the polarized light emitting element, but those with high dichroism are preferred, and those with little influence on the polarization of the stilbene skeleton or the biphenyl skeleton in the ultraviolet light region are preferred. Such other organic dyes include, for example, C.I. Direct Yellow 12, C.I. Direct Yellow 28, C.I. Direct Yellow 44, C.I. Direct Orange 26, C.I. Direct Orange 39, C.I. Direct Orange 71, C.I. Direct Orange 107, C.I. Direct Red 2, C.I. Direct Red 31, C.I. Direct Red 79, C.I. Direct Red 81, C.I. Direct Red 247, C.I. Direct Blue 69, C.I. Direct Blue 78, C.I. Direct Green 80, and C.I. Direct Green 59. These organic dyes may be free acids, or may be alkali metal salts (e.g., Na salts, K salts, Li salts), ammonium salts, or amine salts. In addition, regarding the other fluorescent dyes mentioned above, generally speaking, the fluorescent dyes disclosed can also be used for the purpose of adjusting the luminescent color without any special limitation.

When the above-mentioned other organic dyes or other fluorescent dyes are used together, in order to adjust the color of the desired polarized light emitting element, the dyes to be mixed and the mixing ratio can be adjusted. According to the purpose of the preparation, the mixing ratio of organic dyes or fluorescent dyes is not particularly limited, but relative to 100 parts by mass of the polarized light emitting element, the total amount of these other organic dyes or other fluorescent dyes is preferably used in the range of 0.01 to 10 parts by mass.

In addition to the dyes mentioned above, the dyeing solution may further contain dyeing auxiliaries as needed. Examples of dyeing auxiliaries include sodium carbonate, sodium bicarbonate, sodium chloride, sodium sulfate (glauber's salt), anhydrous sodium sulfate, and sodium tripolyphosphate, preferably sodium sulfate. The content of the dyeing auxiliaries can be arbitrarily adjusted according to the dyeing properties of the dye used, the immersion time mentioned above, and the temperature of the dyeing solution, but preferably 0.0001 to 10% by mass, and more preferably 0.0001 to 2% by mass in the dyeing solution.

After the dyeing step, a preliminary cleaning step may be optionally performed to remove the dyeing solution attached to the surface of the substrate during the dyeing step. By performing the preliminary cleaning step, the dye remaining on the surface of the substrate can be inhibited from migrating to the liquid to be subsequently treated. For the preliminary cleaning step, water is generally used as the cleaning liquid. The cleaning method is preferably to immerse the dyed substrate in the cleaning liquid. On the other hand, the cleaning can also be performed by applying the cleaning liquid to the substrate. The cleaning time is not particularly limited, but is preferably 1 to 300 seconds, and more preferably 1 to 60 seconds. The temperature of the cleaning solution in the pre-cleaning step must be a temperature at which the material constituting the substrate will not dissolve, and generally the cleaning process is performed at 5 to 40°C. Moreover, even if the pre-cleaning step is not performed, it will not have a particularly large impact on the performance of the polarized light emitting element, so the pre-cleaning step can also be omitted.

(Cross-linking step)

After the dyeing step or the preparatory washing step, the substrate may be provided with a crosslinking agent. The method for providing the substrate with a crosslinking agent is preferably to immerse the substrate in a treatment solution containing the crosslinking agent. Alternatively, the treatment solution may be spread or applied to the substrate. The crosslinking agent in the treatment solution is, for example, a solution containing boric acid. 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. Furthermore, the treatment time of the crosslinking step is preferably 30 seconds to 10 minutes, and more preferably 1 to 6 minutes. The manufacturing method of the polarized light emitting element of the present invention has the crosslinking step, whereby the polarization degree of the light emitted by the obtained polarized light emitting element is high, and the display body shows a high contrast. Such an effect is an excellent effect that is completely unpredictable by the function of boric acid used in the known technology for the purpose of improving water resistance or light transmittance. Moreover, in the crosslinking step, as needed, an aqueous solution of a cationic polymer compound can also be included to further combine a fixation treatment. By means of the fixation treatment, the dye in the polarized light emitting element can be fixed. At this time, as for cationic polymer compounds, for example, cations can be used; for dicyanotype, dicyanamide and formalin polycondensates can be used; for polyamine, dicyandiamide/diethylenetriamine polycondensates can be used; for polycationic system, epichlorohydrin/dimethylamine addition polymers, dimethyldiallylammonium chloride/dioxide ion copolymers, diallylamine salt polymers, dimethyldiallylammonium chloride polymers, allylamine salt polymers, dialkylaminoethyl acrylate quaternary salt polymers, etc. can be used.

(Extended steps)

After the above cross-linking step, the stretching step is performed. The stretching step is performed by uniaxially stretching the substrate in a certain direction, which can be either a wet stretching method or a dry stretching method. The stretching ratio is preferably 3 times or more, and more preferably 5 to 8 times.

In the above-mentioned wet stretching method, it is preferred to stretch the substrate in water, a water-soluble organic solvent or a mixed solution thereof. It is more preferred to immerse the substrate in a solution containing at least one crosslinking agent and simultaneously perform the stretching treatment. The crosslinking agent may be, for example, the boric acid in the above-mentioned crosslinking agent step, and it is preferred that the stretching treatment 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 generally 30 seconds to 20 minutes, preferably 2 to 7 minutes. The wet stretching step may be implemented as a single-stage stretching, or as a multi-stage stretching of more than two stages. In addition, the extension treatment can be arbitrarily performed before the dyeing step, and at this time, the dye orientation can also be performed at the same time as the dyeing.

In the above-mentioned dry stretching method, when the stretching heating medium is an air medium, it is preferred to stretch the substrate at a temperature of the air medium ranging from room temperature to 180°C. In addition, the humidity is preferably in an environment of 20 to 95% RH. The substrate heating method can be, for example, an inter-roller area stretching method, a roller heating stretching method, a hot press stretching method, and an infrared heating stretching method, but is not limited to these stretching methods. The dry stretching step can be implemented by a single-stage stretching or a multi-stage stretching of more than two stages.

(Washing step)

During the above-mentioned extension step, since there may be precipitation of the crosslinking agent or foreign matter attached to the surface of the substrate, a cleaning step of cleaning the surface of the substrate may be performed. The cleaning time is preferably 1 second to 5 minutes. The cleaning method is preferably to immerse the substrate in a cleaning solution, or it may be cleaned by applying or coating the cleaning solution on the substrate. The cleaning solution is preferably water. The cleaning treatment may be performed in one stage or in multiple stages of more than two stages. 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, or room temperature.

As for the solvents of the solutions or treatment liquids used in the above steps, in addition to the above-mentioned water, for example, alcohols such as dimethyl sulfoxide, N-methylpyrrolidone, methanol, ethanol, propanol, isopropanol, glycerol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol or trihydroxymethylpropane; amines such as ethylenediamine and diethylenetriamine, etc. The solvents of the solution or treatment liquid are not limited to these, but water is the best. Moreover, the solvents of these solutions or treatment liquids can be used alone or as a mixture of two or more.

(Drying step)

After the above-mentioned cleaning step, the substrate is dried. Although the drying process can be carried out by natural drying, in order to improve the drying efficiency, it can be carried out by roller compression and removing surface moisture by air knife or water absorption roller, etc., and air supply drying can also be carried out. The temperature of the drying process is preferably 20 to 100°C, and more preferably 60 to 100°C. The drying time is preferably 30 seconds to 20 minutes, and more preferably 5 to 10 minutes.

The above method is an example of a method for producing a polarized light emitting element that can be used in the present invention. The above pigments do not decompose even in a high temperature or high humidity and heat environment, so a polarized light emitting element with high durability can be obtained.

With respect to a polarized light emitting dye used in the present application, for example, a polarized light emitting dye used in the present application preferably having at least any one of the above-mentioned diphenylethylene skeleton, biphenyl skeleton or coumarin skeleton in its structure, and a polarized light emitting compound or its salt, it is irradiated with light in the ultraviolet region to the near-ultraviolet visible light region, that is, irradiated with light in the non-visible light region, and absorbs light in the ultraviolet region to the near-ultraviolet visible light region, and can utilize the energy of the light to emit polarized light in the visible light region. The light emitted by the polarized light emitting element is polarized light in the visible light region. Therefore, when the polarized light emitting element is observed through a general polarizing plate in the visible light region, by changing the angle of the axis of the polarizing plate in the visible light region, the light of the strong emission axis and the light of the weak emission axis (or the non-emission axis) of the polarized light can be respectively seen. The polarization degree 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, more preferably 95% or more, and particularly preferably 98% or more.

The polarized light emitting dye used in the present application, for example, the preferred polarized light emitting dye used in the present application, has at least one of the above-mentioned diphenylethylene skeleton, biphenyl skeleton or coumarin skeleton in the structure, and the polarized light emitting element containing the fluorescent compound or its salt can not absorb the light in the visible light region and allow it to pass through. That is, the transmittance of the polarized light emitting element in the visible light region can provide a high transmittance after the transmittance is corrected by the light intensity, and can provide a transmittance that is 30 to 35% higher than the parallel transmittance in the case where the liquid crystal display uses a general polarizing plate structure. In the polarized light emitting element used in this application, if the light-corrected monomer transmittance is 50% or more, a liquid crystal display with significantly higher transmittance than the conventional liquid crystal display can be obtained, and preferably 60% or more, more preferably 70% or more, even more preferably 80% or more, and particularly preferably 90% or more. The polarized light emitting element having at least one of a stilbene skeleton, a biphenyl skeleton or a coumarin skeleton in the structure and containing a fluorescent compound or its salt is preferably a polarized light emitting element with a high appearance of transparency because its absorption in the visible light region is reduced in the non-luminescent state. Moreover, since it can emit polarized light with high brightness, it can provide a polarized light emitting element with high brightness.

[Polarized light emitting plate]

For the polarized light emitting element, a transparent protective film can be further provided to make a polarized light emitting plate with a transparent protective film. The transparent protective film is used to improve the durability and operability of the polarized light emitting element, and the transparent protective film does not have any influence on the axial absorption anisotropy or polarized light emitting displayed by the polarized light emitting element. The transparent protective film can be provided on both sides of the polarized light emitting element, but can also be provided on only one side, that is, can be provided on only one side.

The above-mentioned transparent protective film is preferably a transparent protective film with excellent optical transparency and mechanical strength. In addition, the transparent protective film is preferably a film with a layer shape that can maintain the film shape, and is preferably a plastic film that is excellent in thermal stability, moisture shielding, etc. in addition to transparency and mechanical strength. The materials that form such a transparent protective film can be listed, for example: cellulose acetate film, acrylic film, fluorine film such as tetrafluoroethylene/hexafluoropropylene copolymer, or a film composed of polyester resin, polyolefin resin or polyamide resin, etc., preferably using triacetyl cellulose (TAC) film or cycloolefin film. The thickness of the transparent protective film is preferably in the range of 1μm to 200μm, more preferably in the range of 10μm to 150μm, and particularly preferably in the range of 40μm to 100μm. The method of providing the transparent protective film on the polarized light emitting element is not particularly limited, but for example, the transparent protective film may be superimposed on the polarized light emitting element and layered in a known manner.

The polarized light emitting plate can be further provided with an adhesive layer for respectively attaching a transparent protective film and a polarized light emitting element. The adhesive constituting the adhesive layer is not particularly limited, but examples thereof include: polyvinyl alcohol adhesive, amine emulsion adhesive, acrylic adhesive, polyester/isocyanate adhesive, etc., preferably a polyvinyl alcohol adhesive. After forming the adhesive layer, the polarized light emitting plate can be manufactured by drying or heat treatment at an appropriate temperature.

Furthermore, the polarized light emitting plate may be appropriately provided with various known functional layers such as an anti-reflection layer, an anti-glare layer, and a further transparent protective layer on its exposed surface. When making such various functional layers, it is preferred to apply various functional materials to the exposed surface of the transparent protective layer, or it is also possible to adhere various functional layers or films to the exposed surface of the transparent protective layer via a bonding agent or an adhesive. For example, the further transparent protective layer may include protective layers such as hard coating layers of acrylic resins, polysiloxane resins, and amine resins. Furthermore, in order to further improve the transmittance, an anti-reflection layer may also be provided on the exposed portion of the transparent protective layer. The anti-reflection layer can be formed by, for example, evaporating or sputtering silicon dioxide, titanium oxide, or other materials onto the transparent protective layer, or by thinly coating a fluorine-based material on the transparent protective layer.

(Optical system)

The optical system of the present invention can be obtained by setting a light absorption filter with a light intensity correction unit transmittance of 45 to 100% on the polarized light emitting element or polarized light emitting plate obtained above in a manner satisfying the following formula (1) or formula (2).

A _em-L-λmax ×F _em-L <0.6×A _fi-em-λmax <0.35 Formula (1)

In the formula, A _em-L-λmax represents the absorbance at the maximum absorption wavelength of the axis where the light absorption of the polarized light emitting element is the lowest, F _em-L represents the quantum yield of the axis where the light absorption of the polarized light emitting element is the lowest, and A _fi-em-λmax represents the absorbance of the aforementioned filter at the maximum emission wavelength of the polarized light emitting element.

0<TAF _em-L <0.7×TA _fi-em formula (2)

In the formula, TA _fi-em represents the value of the accumulated absorbance of each wavelength of the aforementioned filter within the wavelength range of light emission of the polarized light emitting element, and TAF _em-L represents the product of the absorbance of each wavelength on the axis where the light absorption of the polarized light emitting element is the lowest and the quantum yield on the axis where the light absorption of the polarized light emitting element is the lowest, accumulated within the light absorption wavelength range of the polarized light emitting element.

Here, the light absorption filter is a filter that absorbs the wavelength of light emitted by the polarized light emitting element. By satisfying the above formula (1), the light of the polarized light emitting element with the maximum emission wavelength on the weak axis can be effectively reduced, thereby obtaining an optical system with a high contrast of polarized light emission.

It is preferable to effectively reduce the wavelength of the light with the maximum emission on the weak axis of the polarized light emitting element by satisfying the following formula (1-a).

A _em-L-λmax ×F _em-L <0.9×A _fi-em-λmax <0.35 Formula (1-a)

It is better to substantially eliminate the luminous intensity of the wavelength where the luminescence of the polarized light emitting element on the weak axis is the strongest (spectral peak intensity of the weak axis) by satisfying the following formula (1-b), and obtain an optical system with high brightness, that is, an optical system with high contrast of polarized light emission, which is better.

A _em-L-λmax ×F _em-L <1.0×A _fi-em-λmax <0.35 Formula (1-b)

Because the use of a light absorption filter can effectively reduce the light of the wavelength of the maximum emission of the polarized light emitting element on the weak axis, the product of the absorbance of the filter that absorbs the light in the visible light region of the wavelength where the polarized light emitting element shows the maximum emission wavelength (hereinafter, also expressed as "A _fi-em-λmax ") and 0.6 is preferably 0.35 or less. By setting it to 0.35 or less, an optical system capable of providing high-brightness polarized light can be obtained. The value of 0.6×A _fi-em-λmax is more preferably 0.30 or less, more preferably 0.22 or less, particularly preferably 0.18 or less, and even more preferably 0.15 or less. By setting it to be less than 0.30, an optical system having high transmittance and capable of providing high-contrast polarized light emission can be obtained, which is preferred.

Alternatively, by satisfying the above formula (2), the light emission of the polarized light emitting element on the weak axis can be reduced, thereby obtaining an optical system with a high contrast of polarized light emission.

It is better to further reduce the luminous intensity of the polarized light emitting element on the weak axis by satisfying the following formula (2-a).

0<TAF _em-L <0.85×TA _fi-em formula (2-a)

It is better to substantially eliminate the light emission of the polarized light emitting element on the weak axis by satisfying the following formula (2-b), thereby obtaining an optical system with high contrast of polarized light emission.

0<TAF _em-L <1.0×TA _fi-em formula (2-b)

As described above, the optical system of the present invention can be achieved by satisfying the above formula (1) or the above formula (2). By satisfying formula (1) or formula (2), an optical system with high transmittance and high polarization, that is, a bright light position and an extinction position with high contrast can be obtained. The luminous spectrum of the polarized light emitting element at the weak light emitting position can be suppressed by formula (1), and the light amount of the polarized light emitting element at the weak light emitting position can be suppressed by formula (2). Therefore, in order to obtain a light with high transmittance and high polarization, that is, an optical system with high contrast bright light position and extinction position, formula (1) and formula (2) are respectively suitable conditions. It is better to satisfy at least formula (2), and it is more preferable to satisfy both formula (1) and formula (2).

(Filter that absorbs visible light)

By making the transmittance of the photometric correction unit of the filter used in the present invention 45 to 100%, an optical system with high transparency can be obtained. When the polarized light emitting element used in the present invention has all or part of the absorption wavelength of light in the ultraviolet region to the near-ultraviolet visible light region (specifically 300 to 430nm), it has high transparency because the absorption of light in the range of 400 to 700nm is significantly lower. Therefore, an optical system with higher transparency can be obtained by making the transmittance of the photometric correction unit of the aforementioned filter 50 to 99.9%, preferably 60 to 99.9%, more preferably 70 to 99.9%, and even more preferably 80 to 99.9%.

Furthermore, when the aforementioned filter is provided, it is more preferable that the transmittance of each wavelength of the polarized light emitting element, especially the transmittance of each wavelength in the wavelength band region for light emission is 45 to 100%, thereby more effectively obtaining an optical system with high contrast and high transparency, which is preferred. By having the transmittance of the aforementioned filter in the light emission wavelength of the polarized light emitting element be 50 to 99.9%, a better form of the present application can be achieved, and preferably 60 to 99.9%, more preferably 70 to 99.9%, and even more preferably 80 to 99.9%. By placing such a filter on the side where people are visually recognizing, it is more effective to provide a high contrast in the optical system of the present application for the visually recognizing person, which is preferred.

The visible light absorption filter used in the present invention is preferably a polarizing element or a polarizing plate. The so-called polarizing plate means a polarizing element provided with a transparent protective film (in other words, a polarizing plate has a polarizing element and a transparent protective film). The transparent protective film is preferably one that does not cause any obstruction to the optical properties of the aforementioned polarizing element, and does not absorb light in the ultraviolet region. The aforementioned polarizing element is not particularly limited if it has axial absorption anisotropy for light in the visible light region, that is, has a polarizing function, because by using a polarizing element whose monomer transmittance or its monomer absorbance satisfies the above formula (1) or the above formula (2), an optical system with high brightness or high contrast equal to or higher than that of the aforementioned filter (the aforementioned polarizing element) can be provided, which is preferred.

Polarizing plates using the aforementioned polarizing elements include, for example, iodine-based polarizing plates, dye-based polarizing plates, dye-based polarizing plates capable of controlling only polarized light of a specific wavelength, polarizing plates utilizing a type of polyene, wire-grid-type polarizing plates, and reflective polarizing plates. The aforementioned polarizing elements have polarizing properties for light in a partial or entire wavelength range of 400 to 700 nm. Examples of iodine-based polarizing plates include Japanese Patent Laid-Open No. 2001-290029 and Japanese Patent Laid-Open No. 2010-072548; examples of dye-based polarizing plates include Japanese Patent Laid-Open No. 2001-033627, Japanese Patent Laid-Open No. 2004-251962, and Patent Document 7; and examples of dye-based polarizing plates capable of controlling only polarized light of a specific wavelength include Japanese Patent Laid-Open No. 2007-0848. 03, Japanese Patent Publication No. 2007-238888, WO2012-165223, Patent Document 8; For polarizing plates using polyene, Japanese Patent Publication No. 2005-527847 and Japanese Patent Publication No. 2005-517974 can be cited as examples; For wire-grid type polarizing plates, Japanese Patent Publication No. 2003-519818 and Japanese Patent Publication No. 2003-502708 can be cited as examples. Examples of reflective polarizing plates include U.S. Patent No. 3,610,729, WO95/17303, WO95/17692, WO95/17699, WO96/19347, WO99/36262, WO2005/0888363, Japanese Patent Application Laid-Open No. 2007-298634, and WO2011/074701. Examples of products include 3M Company's DBEF. As for the polarizing element, it is preferred that the transmittance of the monomer satisfies the above formula (1) or the above formula (2), or satisfies the following formula (3) or the following formula (4) described later, and has high long-term storage stability and stable durability even under severe conditions. Therefore, it is preferred to use a dye-based polarizing plate and a polarizing plate using a polyene type. In terms of high durability even in high temperature and high temperature and high humidity environments, a dye-based polarizing plate obtained by containing a dichroic dye in a substrate such as a polyvinyl alcohol film and extending it in a boric acid aqueous solution is particularly preferred. In addition, the so-called dichroic dye is exemplified by those described in non-patent document 1.

If the ratio of the absorption of the strongest axis to the absorption of the lowest axis is 3 or more, that is, the dichroic ratio is 3 or more, the polarizing element has the function of a polarizing element, so it is preferred. More preferably, it is 10 or more, more preferably, it is 20 or more, especially preferably, it is 35 or more, and even more preferably, it is 40 or more. In addition, the polarization degree of the polarizing element can be 30% or more, more preferably, it is 40% or more, more preferably, it is 60% or more, even more preferably, it is 80% or more, and even more preferably, it is 90% or more.

As for the visible light absorption filter used in the present invention, when using a polarizing element or a polarizing plate using the polarizing element, it is preferred to use the polarizing element with the weakest luminous axis parallel to the polarizing element with the highest absorbance. The angles of the state where the weakest luminous axis of the polarizing element and the highest absorbance axis of the polarizing element are parallel do not need to be completely consistent, and can be a convenient parallel state. By making the weakest luminous axis of the polarizing element and the highest absorbance axis of the polarizing element completely parallel, it is possible to provide the highest brightness and high contrast in the optical system of the present invention, so it is particularly preferred. Although it is possible to achieve a state where the axis with the weakest light emission of the polarized light emitting element is parallel to the axis with the highest absorbance of the polarized light emitting element, it is better to be within 10°, more preferably within 5°, more preferably within 2°, and particularly preferably within 1° relative to completely parallel axes.

The aforementioned filter is a polarizing element and satisfies the following formula (3), which is an optical system that can obtain a high contrast of polarized light emission, and is therefore preferred.

A _em-L-λmax ×F _em-L <0.6×A _{Pol-Kz-em-L-λmax} <0.7 Formula (3)

In the formula, A _em-L-λmax represents the absorbance at the maximum absorption wavelength on the axis where the light absorption of the polarized light emitting element is the lowest, F _em-L represents the quantum yield on the axis where the light absorption of the polarized light emitting element is the lowest, and A _{Pol-Kz-em-L-λmax} represents the absorbance at the highest absorption axis of the polarized light emitting element at the wavelength with the maximum emission on the axis where the emission of the polarized light emitting element is the weakest.

By satisfying the above formula (3), compared with the case where a visible light absorption filter that is not a polarizing element is used, an optical system with high transmittance, high brightness at the luminous position, high brightness at the extinction position, and especially significantly less luminous brightness at the maximum luminous wavelength at the extinction position can be obtained, that is, a high contrast optical system.

It is preferred that the aforementioned filter satisfies the following formula (3-a) to obtain an optical system with high brightness and low luminous brightness at the extinction position, that is, a high-contrast optical system can be obtained. It is more preferred that the aforementioned filter satisfies the following formula (3-b).

A _em-L-λmax ×F _em-L <0.8×A _{Pol-Kz-em-L-λmax} <0.7 Formula (3-a)

A _em-L-λmax ×F _em-L <1.0×A _{Pol-Kz-em-L-λmax} <0.7 Formula (3-b)

In the above formula (3), the value of 0.6×A _{Pol-Kz-em-L-λmax} is preferably less than 0.6, more preferably less than 0.5, still more preferably less than 0.4, and particularly preferably less than 0.3. With the above preferred aspects, an optical system with higher transmittance, higher brightness, and/or less luminous brightness at the extinction position can be obtained, that is, an optical system with higher contrast and/or higher transmittance can be obtained.

In a preferred embodiment, when the filter is a polarizing element, an optical system can be obtained by satisfying the following formula (4), in which the light emission of the weak axis of the polarized light emitting element is reduced and the contrast of the polarized light emission is high compared to when the filter is not a polarizing element.

0<TAF _em-L <0.7×TA _pol-Kz-em formula (4)

In the formula, TApol _-Kz-em represents the value obtained by accumulating the absorbance of each wavelength of the polarizing element at the highest absorption axis within the wavelength range in which the polarizing element emits light, and TAFem _-L represents the same as formula (2).

Preferably, the amount of light emitted along the weak axis of the polarized light emitting element can be further reduced by satisfying the following formula (4-a), and the optical system can display high-contrast polarized light.

0<TAF _em-L <0.8×TA _pol-Kz-em formula (4-a)

It is more preferable to satisfy the following formula (4-b), and it is even more preferable to satisfy the following formula (4-c).

0<TAF _em-L <0.9×TA _pol-Kz-em formula (4-b)

0<TAF _em-L <1.0×TA _pol-Kz-em formula (4-c)

In the visible light absorption filter used in the present invention, by making the hue of the monomer obtained according to JIS Z 8781-4:2013 -5<a*<+3 and b*<±3, a neutral color optical system can be obtained, which is preferred. In particular, when the polarized light emitting element has a neutral color or a high transmittance, the aforementioned filter is preferably a neutral color, that is, a* and b* both have values close to zero. When the aforementioned filter is a polarizing element, the same effect can also be obtained by being a monomer and the hue of the monomer is -5<a*<+3 and b*<±3. The value of a* is preferably -3 or more and 2 or less, and more preferably -2 or more and 1 or less. The value of b* is preferably -2 or more and 2 or less, and more preferably -1 or more and 1 or less.

In the optical system of the present invention, polarized light emitting elements and filters can be configured separately, and by stacking polarized light emitting elements and filters, an optical system with higher brightness and high transmittance can be provided, so is preferred. It is known that when light is incident on the interface of an optical component, the light transmittance is reduced due to interface reflection. Therefore, in the optical system of the present invention, in order to obtain an optical system with high brightness and high transmittance, it is important to reduce the interface and reduce the interface reflection on the optical path of the optical system. Therefore, stacking polarized light emitting elements and polarized elements is a preferred type.

Furthermore, in one form of the present invention, a medium for controlling the phase may be provided in the above-mentioned optical system. The so-called medium having a phase may be a phase difference plate (also called a wavelength plate, phase difference film), or a liquid crystal panel (liquid crystal unit) that electrically drives and regulates the liquid crystal. In particular, since a liquid crystal display device can be obtained by using a liquid crystal panel (liquid crystal unit) that can electrically control the phase as a medium for controlling the phase, it is one of the better forms of the present invention. When using the optical system of the present invention, since the polarized light-emitting element will emit light, a self-luminous liquid crystal display can be produced. Moreover, since a liquid crystal display with high transmittance and high contrast can be obtained, a display device with very high transmittance and high contrast compared to a liquid crystal display using a general polarizing plate can be obtained. Generally speaking, liquid crystal displays use two polarizing plates, but the parallel transmittance when two plates are used is 25 to 35%. The liquid crystal display using the known polarizing plate with a parallel transmittance of 25 to 35% has low quality as a see-through display due to low transmittance. Also, since it is not self-luminous, a backlight must be provided, but since the backlight unit uses CCFL or LED, transparency cannot be obtained. In contrast, the polarized light-emitting element used in the optical system of the present invention is transparent and luminous, so it can be used as a transparent and self-luminous liquid crystal display device.

Furthermore, by using a medium with a phase, when polarized light is presented as a wave, which has the properties of particles and waves, the phase of the wave can be controlled. When focusing on polarized light, for example, a wavelength plate is an optical functional element that gives a predetermined phase difference to linearly polarized light, and polarized light is able to set a different phase on other axes (such as 90°) for light on a specific axis. That is, by setting a wavelength plate on the optical path of a polarized light, it can be converted into polarized light on the opposite axis and re-assigned circular polarization, elliptical polarization, etc. A wavelength plate can be said to be an element that can change the state of polarization of incident light by giving a phase difference to two orthogonal polarized light components using an oriented birefringent material (such as a stretched film). The specific use of the wavelength plate is, for example, when the wavelength of a specific light is set to λ, the slow axis of the λ/2 phase difference plate is set to 45° relative to the axis of polarization, thereby rotating the linear polarization that has been incident on the wavelength plate (phase difference plate) by 90° and emitting the polarization light having a polarization axis in a direction orthogonal (90°) to the incident polarization axis. Furthermore, when the angle of the axis is set to 45° relative to the axis of the polarized light as the target, although the function of the phase difference plate is exhibited to a certain extent even if it is offset by about ±10°, it is preferably within the range of ±5°, more preferably within the range of ±3°, still more preferably within the range of ±2°, and particularly preferably within the range of ±1°. Furthermore, when the slow axis of the λ/4 phase difference plate is set to 45° relative to the polarization axis, the linearly polarized light incident on the wavelength plate (phase difference plate) can be emitted as circularly polarized light.

The optical system of the present invention manufactured in this way is an optical system that exhibits polarized light luminescence in the visible light region and high transmittance, that is, high brightness and high contrast. In addition, the optical system of the present invention exhibits excellent durability against heat, humidity, light, etc., so it can maintain its performance even in harsh environments, and has higher durability than the conventional iodine-based polarizer. Therefore, the optical system of the present invention can be effectively used not only in lenses, glasses, and liquid crystal displays that require high transparency in the visible light region and high durability in harsh environments, but also in various display devices such as televisions, wearable terminals, desktop terminals, smart phones, car screens, see-through displays, and electronic billboards and smart windows used outdoors or indoors. The highly efficient polarized backlight for the orientation of liquid crystal displays can also be applied to polarized light sources that can emit light with high efficiency.

(Display device)

In the present invention, when a specific polarized light luminescent pigment is used, the polarized light luminescent effect is exhibited by irradiating light in the ultraviolet to near ultraviolet visible light region (specifically, irradiating light in the range of 300 to 430 nm), and display can be performed by utilizing this effect. The display device of the present invention has a high transmittance in the visible light region, so the decrease in transmittance in the visible light region of the conventional polarizing plate can be significantly reduced. In particular, since the display device having the optical system of the present invention has high transparency, a substantially transparent display can be obtained despite being a liquid crystal display. Furthermore, since it can be designed so that even when displaying text, images, etc., the environment and images on the back can be viewed from the viewing side through the display device, a display that is transparent while displaying and can view the back side can be obtained, that is, a display that can display text, etc. although it is transparent can be obtained. Moreover, the display device of the present invention is effectively applied as a transparent liquid crystal display without light loss, especially a see-through display.

Furthermore, the display device of the present invention can be used to produce a liquid crystal display, for example, which displays polarized light by irradiating ultraviolet light and uses the polarized light to emit light. Therefore, a liquid crystal display that uses ultraviolet light, which is invisible light, instead of a normal liquid crystal display that uses visible light, can be realized. In other words, a self-luminous liquid crystal display can be produced, which can display the desired text, image, etc. even in a dark space without light, if it is a space that can be irradiated with ultraviolet light.

In a vehicle or outdoor display liquid crystal display using the optical system of the present invention, the liquid crystal unit used is not limited to TN liquid crystal, STN liquid crystal, VA liquid crystal, IPS liquid crystal, etc., and the liquid crystal display can be used in all liquid crystal display modes.

The optical system of the present invention has excellent polarized light luminescence performance, and can suppress discoloration and reduction of polarized light luminescence performance even in high temperature and high humidity conditions inside the car or outdoors. Therefore, it can help improve the long-term reliability of liquid crystal displays for vehicles or outdoor displays.

[Implementation example]

The present invention is described in more detail below by way of examples, but these are illustrative examples and are not intended to limit the present invention. In addition, the "%" 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 sulfonic acid is described in the form of free acid.

[Evaluation Method]

Each polarized light emitting element or polarized light emitting plate obtained in the following embodiments and comparative examples is used as a test sample and evaluated in the following manner.

[Measurement of penetration rate]

A spectrophotometer ("U-4100" manufactured by Hitachi HIGH TECHNOLOGIES) was used to evaluate the transmittance and absorbance of polarized light emitting elements, polarized light emitting plates, polarized elements, polarized plates, and optical systems. A Gram Thomson polarizer was set up to irradiate each polarized light emitting element (measurement sample) produced in each embodiment and comparative example with light having 100% polarization in the wavelength range of 220nm to 2600nm (hereinafter also referred to as "absolute polarization"), and the transmittance of light of each wavelength when each measurement sample was irradiated with absolute polarization was measured.

[Photometric correction single body transmittance Ys, photometric correction orthogonal transmittance Yc]

For a polarized light emitting element, a polarized light emitting plate, a polarizing element, a polarizing plate or an optical system, the transmittance of light measured when polarized light is incident in an orthogonal position relative to the axis of light absorption that is highest due to the orientation of the pigment when irradiated with absolute polarized light (i.e., the transmittance of light along the axis with the least absorption when absolutely polarized light is incident) is set as Ky, and the transmittance of light measured when polarized light is incident in a parallel position relative to the axis of light absorption that is highest due to the orientation of the pigment when irradiated with absolute polarized light to the polarized light emitting element or the polarizing element (i.e., the transmittance of light along the axis with the most absorption when absolutely polarized light is incident) is set as Kz. In addition, Ky in the polarized light emitting element is the transmittance of the light on the axis showing the weakest emission, and Kz in the polarized light emitting element is the transmittance of the light on the axis showing the strongest emission. The photometrically corrected single transmittance Ys and photometrically corrected orthogonal transmittance Yc of each measured sample are obtained by substituting the above Ky and Kz obtained for each predetermined wavelength interval dλ (5nm in this case) into formula (I) to calculate the single transmittance Ts at each wavelength, and into formula (II) to calculate the single transmittance Tc at each wavelength, and correcting them into photometric transmittance according to JIS Z 8722:2009. Specifically, the photometrically corrected single transmittance Ys is calculated by substituting the single transmittance Ts of each wavelength into the following formula (III), and the photometrically corrected orthogonal transmittance Yc is calculated by substituting the orthogonal transmittance Tc of each wavelength into the following formula (IV). In the following formula (III) or (IV), Pλ represents the spectral distribution of the standard light (C light source), and yλ represents the 2D visual field color matching function. The so-called photometrically corrected single transmittance Ys represents the transmittance when viewed as a single body, and the so-called photometrically corrected orthogonal transmittance Yc represents the transmittance when two pieces of the test sample are viewed orthogonally.

Ts=(Ky+Kz)/2 (I)

Tc=(Ky×Kz)/100 (II)

(chromaticity a* value and b* value)

For each test sample, the chromaticity a* value and b* value when measuring the single transmittance Ts are measured according to JIS Z 8781-4:2013. During the measurement, the above-mentioned spectrophotometer is used to measure the transmittance of each wavelength, and the light source is a C 2° field of view. a*-s and b*-s correspond to the chromaticity a* value and b* value when measuring the single transmittance Ts, respectively.

(Absorbance)

The absorbance (Abs) at each wavelength on each axis of each measurement sample is obtained by substituting the above Ky and Kz into Tr of the following formula (V).

Abs=-Log(Tr) (V)

(Quantum yield of polarized light emitting element)

The quantum yield of each axis of the polarized light emitting element is the value obtained by using FP-8500 manufactured by JASCO Corporation as the measured value. Specifically, when the quantum yield of the polarized light emitting element is measured by FP-8500 manufactured by JASCO Corporation, the quantum yield obtained by irradiating the axis showing the highest light absorption due to the orientation of the polarized light emitting dye through the polarization axis and the quantum yield obtained by irradiating the axis showing the lowest light absorption due to the orientation of the polarized light emitting dye through the polarization axis are measured in such a way that the polarized light can be incident on the polarized light emitting element, and the quantum yield obtained by irradiating the axis showing the lowest light absorption due to the orientation of the polarized light emitting dye through the polarization axis are measured as the quantum yield of the polarized light emitting element of the present invention.

(The luminous intensity of each wavelength of the polarized light emitting element and the degree of polarization (DOP) of the emitted light)

The luminous intensity of each wavelength of the polarized light emitting element and the degree of polarization (DOP) of the emitted light are values obtained by measuring using the Stokes parameter method. Specifically, they are values measured using a spectropolarimeter (Poxi-Spectra, manufactured by Tokyo Instruments). In addition, the types (states) of polarized light emitted by the polarized light emitting elements or polarized light emitting plates used in the following embodiments or comparative examples confirmed using the Poxi-Spectra, manufactured by Tokyo Instruments, are all linearly polarized light.

(Production of polarized light emitting element A)

A polyvinyl alcohol film (VF-PS #7500 manufactured by KURARAY) with a thickness of 75 μm was immersed in 40°C warm water for 3 minutes to swell the film. The swollen film was immersed in a 45°C aqueous solution containing 0.8 parts by weight of a 4,4'-bis-(sulfonylphenyl)biphenyl disodium aqueous solution represented by formula (B-1) (Tinopal NFW Liquid manufactured by BASF), 1.0 parts by weight of sodium sulfate, and 1500 parts by weight of water for 4 minutes. After immersion, the obtained film was stretched for 5 minutes in a 3% boric acid aqueous solution at 50°C to a length 5 times that of the film. The stretched film was washed with water at room temperature for 20 seconds while maintaining the original stretched state, and then dried at 70°C for 9 minutes to obtain a polarized light emitting element A. The order parameter of polarized light emitting element A calculated according to the above formula (5) is 0.91, and the wavelength of maximum absorption is 375nm. When polarized light emitting element A is irradiated with ultraviolet light and its luminescence is confirmed through a general polarizing plate (SKN-18243P manufactured by POLATECHNO), blue polarized light is emitted in the direction of the stretching axis during the processing of the polarized light emitting element. On the other hand, the polarized light emission in the orthogonal axis relative to the stretching axis is significantly lower. In other words, the polarized light emitting element is an element that emits linear polarization.

(Production of polarizing plate A using polarizing light emitting element A)

A triacetylcellulose film (ZRD-60 manufactured by Fuji Film Co., Ltd.) containing no ultraviolet absorber was treated with a 1.5 equivalent sodium hydroxide aqueous solution at 35°C for 10 minutes, washed with water, and then dried at 70°C for 10 minutes. A triacetylcellulose film (hereinafter referred to as TAC) obtained by alkaline treatment was laminated on both sides of the polarized light-emitting element A through an aqueous solution containing 4% polyvinyl alcohol resin (NH-26 manufactured by VAM & POVAL Co., Ltd., Japan), and dried at 70°C for 10 minutes to prepare a polarized light-emitting plate A having a structure of TAC/polarized light-emitting element A/TAC. The obtained polarized light-emitting plate A has the characteristics of the polarized light-emitting element A without deteriorating the optical characteristics of the obtained polarized light-emitting element A.

(Production of polarized light emitting element B and polarized light emitting plate B)

Polarized light emitting element B and polarized light emitting plate B were prepared in the same manner except that 0.05 parts by weight of the aqueous solution of the compound described in formula (B-1) was used instead of 0.8 parts by weight of the aqueous solution of the compound described in formula (B-1) in the preparation of polarized light emitting element A and polarized light emitting plate A. The order parameter of polarized light emitting element B calculated by the above formula (5) is 0.84, and the maximum absorption wavelength is 380nm. When the polarized light emitting plate B was irradiated with ultraviolet light and its luminescence was confirmed through a general polarizing plate (SKN-18243P manufactured by POLATECHNOL), blue polarized light was emitted in the direction of the stretching axis during the processing of the polarized light emitting element. On the other hand, the polarized light emission in the orthogonal axis relative to the stretching axis was significantly lower. In other words, the polarized light emitting element is an element that emits linear polarized light.

(Synthesis example 1)

35.2 parts of commercially available 4-diamino-stilbene-2,2'-disulfonic acid were added to 300 parts of water and stirred, and 35% hydrochloric acid was used to adjust the pH to 0.5. 10.9 parts of 40% sodium nitrite aqueous solution were added to the obtained solution, and stirred at 10°C for 1 hour, followed by 34.4 parts of 6-aminonaphthalene-2-sulfonic acid, and the pH was adjusted to 4.0 with 15% sodium carbonate aqueous solution, and stirred for 4 hours. 60 parts of sodium chloride were added to the obtained reaction solution, and the precipitated solid was separated by filtration, and then washed with 100 parts of acetone and dried to obtain 62.3 parts of the compound described by the following formula (S-7p).

62.3 parts of the compound of formula (S-7p) obtained above were added to 300 parts of water and stirred, and a 25% sodium hydroxide aqueous solution was used to adjust the pH to 10.0. 20 parts of 28% ammonia water and 9.0 parts of copper sulfate pentahydrate were added to the obtained solution, and stirred at 90°C for 2 hours. 25 parts of sodium chloride were added to the obtained reaction solution, and the precipitated solid was filtered and separated, and then washed with 100 parts of acetone to obtain 40.0 parts of a wet cake. The wet cake was dried in a hot air dryer at 80°C to obtain 20.0 parts of the polarized light-emitting pigment represented by formula (S-7).

(Production of polarized light emitting element C and polarized light emitting plate C)

Polarized light emitting element C and polarized light emitting plate C were prepared in the same manner except that 0.1 parts by weight of the polarized light emitting dye represented by formula (S-7) was used instead of 0.8 parts by weight of the aqueous solution of the compound represented by formula (B-1) as the polarized light emitting dye in the preparation of polarized light emitting element A and polarized light emitting plate A. The order parameter of polarized light emitting element C calculated by the above formula (5) was 0.84, and the wavelength of maximum absorption was 400 nm. When the polarized light emitting plate C was irradiated with ultraviolet light and its luminescence was confirmed through a general polarizing plate (SKN-18243P manufactured by POLATECHNOL), blue polarized light was emitted in the direction of the stretching axis during the processing of the polarized light emitting element, and on the other hand, the polarized light emission in the orthogonal axis relative to the stretching axis was significantly lower. In other words, the polarized light emitting element C is an element that emits linearly polarized light.

Figure 1 shows the Ky and Kz of each wavelength of polarized light emitting plates A to C measured every 5 nm using a spectrophotometer ("U-4100" manufactured by Hitachi HIGH TECHNOLOGIES). Figure 2 shows the ratio of the luminous intensity of each wavelength of polarized light emitting plates A to C measured by a spectropolarimeter (Poxi-Spectra manufactured by Tokyo Instruments) when the intensity of the luminous wavelength showing the maximum value is set to 1. Figure 3 shows the degree of polarization (DOP) of the wavelength above 0.05 when the intensity of the luminous intensity of each wavelength of polarized light emitting plates A to C is set to 1.

Table 1 shows: the photometrically corrected monomer transmittance (Ys- _em ) of polarized light emitting plates A to C measured every 5nm, the maximum absorption wavelength ( λ max- _Aem ), the absorbance at the wavelength of maximum absorption on the axis where the light absorption of the polarized light emitting plate showing the maximum absorption wavelength is the highest (Aem _-H-λmax ), the value after the absorbance of each wavelength on the axis where the light absorption of the polarized light emitting plate is the highest is accumulated in the light absorption wavelength range (TAem _-H ), the quantum yield on the axis where the light absorption of the polarized light emitting plate is the highest (Fem _-H ), the absorbance at the wavelength of maximum absorption on the axis where the light absorption of the polarized light emitting plate showing the maximum absorption wavelength is the lowest (Aem _-L-λmax ), the value after accumulating the absorbance of each wavelength on the axis with the lowest light absorption of the polarizing plate in the light absorption wavelength range (TA _em-L ), the quantum yield on the axis with the lowest light absorption of the polarizing plate (F _em-L ), the maximum emission wavelength (λmax-EM _em ), and the emission wavelength range (Range-EM _em ).

In addition, Table 2 shows: the product of the absorbance of the wavelength of the maximum absorption of the axis where the light absorption of the polarizing plate is the highest (A _em-H-λmax ) and the quantum yield of the axis where the light absorption of the polarizing plate is the highest, measured every _{5 nm} ; the value after accumulating the product of the absorbance of each wavelength of the axis where the light absorption of the polarizing plate is the highest and the quantum yield of the axis where the light absorption of the polarizing plate is the highest in the light absorption wavelength range of the polarizing plate (TAF _em-H ); the absorbance of the wavelength of the maximum absorption of the axis where the light absorption of the polarizing plate is the lowest (A _em-L-λmax ) and the quantum yield of the axis where the light absorption of the polarizing plate is the lowest (F _em-L ), the product of the absorbance of each wavelength on the axis where the light absorption of the polarizing plate is the lowest and the quantum yield on the axis where the light absorption of the polarizing plate is the lowest, accumulated over the light absorption wavelength range of the polarizing plate (TAF _em-L ).

From the results shown in Figure 1, Table 1, and Table 2, it can be seen that polarizing plate A absorbs light below about 425nm, polarizing plate B absorbs light below about 405nm, and polarizing plate C absorbs light below 440nm, and has axial absorption anisotropy of light, that is, it has a polarization function. In addition, from the results shown in Figure 2 and Figure 3, it can be seen that polarizing plate A and polarizing plate B emit light at 400 to 570nm, and polarizing plate C emits light at 430 to 600nm, and the light emitted by each polarizing plate has a high degree of polarization (DOP).

(Production of polarizing element A and polarizing plate A)

According to the method of Example 1 of Patent Document 7, a polyvinyl alcohol film (VF-PS #7500 manufactured by KURARAY Co., Ltd.) with a thickness of 75 μm was immersed in warm water at 45°C for 2 minutes and subjected to a swelling treatment to set the stretching ratio to 1.30 times. In the dyeing step, the membrane after swelling treatment was immersed in a solution containing 2000 parts by weight of water, 2.0 parts by weight of anhydrous sodium sulfate, 0.34 parts by weight of the azo compound described in Synthesis Example 1 of International Publication No. WO2012/165223, 0.027 parts by weight of the azo compound described in Synthesis Example 1 of Japanese Patent Application Laid-Open No. 2003-215338, 0.040 parts by weight of the azo compound described in Example 1 of Japanese Patent No. 2622748, and 0.16 parts by weight of C.I. Direct Orange 39 for 1 minute and 00 seconds at 45°C, so that the azo compound was contained in the membrane. The obtained membrane was immersed in a 40°C aqueous solution containing 20 g/l of boric acid (manufactured by Societa Chimica Larderello s.p.a.) for 1 minute. The obtained film was stretched 5.0 times and stretched in a 50°C aqueous solution containing 30.0 g/l of boric acid for 5 minutes. The obtained film was kept in a tight state and treated with 25°C water for 20 seconds. The obtained film was dried at 70°C for 9 minutes to obtain a polarizing element A in the form of a visible light absorption filter. A triacetyl cellulose film (ZRD-60 manufactured by Fuji Film Co., Ltd.) without an ultraviolet absorber was treated with a 1.5 equivalent sodium hydroxide aqueous solution at 35°C for 10 minutes, washed with water, and then dried at 70°C for 10 minutes. The triacetyl cellulose film obtained by alkali treatment is layered on both sides of polarizing element A through an aqueous solution containing 4% polyvinyl alcohol resin (NH-26 manufactured by VAM & POVAL Co., Ltd., Japan), dried at 70°C for 10 minutes, and an anti-reflection layer (AR layer) is provided on the surface to form a polarizing plate A which is one of the forms of a visible light absorption filter and has a structure of AR layer/TAC/polarizing element A/TAC/AR layer. The obtained polarizing plate A has the characteristics of polarizing element A without sacrificing the optical characteristics of the obtained polarizing element A.

(Production of polarizing element B and polarizing plate B)

Polarizing element B and polarizing plate B, which are one of the forms of visible light absorption filters, were obtained in the same manner except that the immersion time of polarizing element A in the aqueous solution containing azo compounds was changed to 2 minutes.

(Production of polarizing element C and polarizing plate C)

Except that the immersion time of the aqueous solution containing azo compounds in the production of polarizing element A was changed to 3 minutes, the polarizing element C and polarizing plate C, which are one of the forms of visible light absorption filters, were obtained in the same manner.

<Production of polarizing element D and polarizing plate D>

In the preparation of polarizing element A, except that a 75μm thick polyvinyl alcohol film (VF-PS # 7500 manufactured by KURARAY Co., Ltd.) was immersed in 40℃ warm water for 3 minutes to swell the film, and the swollen film was immersed in a 45℃ aqueous solution containing 0.04 parts by weight of azo compound described in Example 1 of Patent Document 8, 1.0 parts by weight of sodium sulfate, and 1500 parts by weight of water for 4 minutes, the rest was prepared in the same manner as the polarizing element D and polarizing plate D, which are one of the forms of the filter absorbing visible light region used in this application. The obtained polarizing plate D has the characteristics of polarizing element D without deteriorating the optical characteristics of the obtained polarizing element D.

<Production of polarizing element E and polarizing plate E>

In the preparation of polarizing element A, except that a polyvinyl alcohol film (VF-PS # 7500 manufactured by KURARAY Co., Ltd.) with a thickness of 75 μm was immersed in 40°C warm water for 3 minutes to swell the film, and the swollen film was immersed in a 45°C aqueous solution containing 0.03 parts by weight of azo compound described in Synthesis Example 1 of Japanese Patent Application Laid-Open No. 2003-215338, 1.0 parts by weight of sodium sulfate, and 1500 parts by weight of water for 4 minutes, the rest was prepared in the same manner to prepare polarizing element E and polarizing plate E, which are one of the forms of visible light absorption filters. The obtained polarizing plate E has the characteristics of polarizing element E without deteriorating the optical characteristics of the obtained polarizing element E.

The following method is used to make a visible light absorption filter F, which is a laminate with two sides that can be adhered/joined and has a transmittance of about 70% at each wavelength in the visible light region.

With respect to 100 parts of the resin solid content of the adhesive PTR-3000 manufactured by Nippon Kayaku Co., Ltd., 0.095 parts of KAYASET BLACK A-N (manufactured by Nippon Kayaku Co., Ltd.) and 0.0048 parts of KAYASET BLUE A-D (manufactured by Nippon Kayaku Co., Ltd.) were mixed, and methyl ethyl ketone was added in such a manner that the solid content of the obtained prepared composition was 17 parts, and mixed for 1 hour to prepare an adhesive composition for a light filter. Using a coating machine, the obtained adhesive composition for a light filter was sandwiched between two release films (polyethylene terephthalate films) to form a sheet with a thickness of 25μm, and a light filter F was prepared.

Neutral density filter ND-0.1 (manufactured by Fuji Film Co., Ltd.) was used as visible light absorption filter G with a transmittance of 80% at each wavelength in the visible light region.

The visible light absorption filter H is manufactured by the following method. It is a laminate that can be bonded on both sides and has a transmittance of about 90% in the visible light region at all wavelengths.

With respect to 100 parts of the resin solid content in the adhesive PTR-3000 manufactured by Nippon Kayaku Co., Ltd., 0.0092 parts of KAYASET BLACK A-N (manufactured by Nippon Kayaku Co., Ltd.) and 0.001 parts of KAYASET BLUE A-D (manufactured by Nippon Kayaku Co., Ltd.) were mixed and stirred to obtain a prepared composition, and methyl ethyl ketone was added in such a manner that the solid content content was 17 parts with respect to 100 parts of the prepared composition, and the mixture was mixed for 1 hour to prepare an adhesive composition for a light filter. Using a coating machine, the obtained adhesive composition for a light filter was sandwiched between two release films (polyethylene terephthalate films) and formed into a sheet with a thickness of 25μm, thereby preparing a light filter H.

The visible light absorption filter used in the comparison example is the SKN-18243P (hereinafter referred to as polarizing plate I) manufactured by POLATECHNO, which is a general iodine-based polarizing plate with a transmittance of 43%.

Figure 4 shows the Ky and Kz of polarizer A, polarizer B, polarizer C, polarizer D, and polarizer E measured at every 5nm, and Figure 5 shows the transmittance of filter F sandwiched by TAC film, filter H sandwiched by TAC film, and filter G not sandwiched by TAC film at every 5nm.

Table 3 shows: the photometrically corrected single transmittance (Ys- _fi ), photometrically corrected orthogonal transmittance (Yc-fi), single hue (a*-s and b*-s), single absorbance at 435nm (Afi-em-435), single absorbance at 465nm (Afi- _{em -465), the value of the accumulated absorbance of the single at each wavelength from 400 to 570nm} (TAfi-em 400-570), the value of the accumulated absorbance of the single at each wavelength from 430 to _600nm (TAfi _{-em 430-600} ) obtained by measuring every 5nm of polarizing plate A, polarizing plate B, polarizing plate C, polarizing plate D, polarizing plate E, and polarizing plate I (SKN _-18243P ) belonging to the visible light absorption filter. ), the absorbance at 435nm on the axis with the strongest absorption (A _{pol-Kz-em-L-435} ), the absorbance at 465nm on the axis with the strongest absorption (A _{pol-Kz-em-L-465} ), the accumulated value of the absorbance at each wavelength on the axis with the strongest absorption from 400 to 570nm (TA _{pol-Kz-em-400-570} ), the accumulated value of the absorbance at each wavelength on the axis with the strongest absorption from 430 to 600nm (TA _{pol-Kz-em-430-600} ).

Table 4 shows the photometrically corrected monomer transmittance (Ys- _fi ), the monomer hue (a*-s and b*-s), the absorbance at 435nm (Afi _{-em-435), the absorbance at 465nm (Afi-em-465} ), the accumulated absorbance of the filter at each wavelength from 400 to 570nm (TAfi- _{em 400-570} ), and the accumulated absorbance of the filter at each wavelength from 430 to 600nm (TAfi _{-em 430-600} ). In addition, since filter F, filter G, and filter H are not polarizers, the photometrically corrected orthogonal transmittance (Yc- _fi ) is omitted.

As can be seen from Figures 4 and 5, the visible light absorption filter used in this application has the function of absorbing light for the wavelengths emitted by polarized light emitting plates A to C. In addition, polarized plates A to E have axial absorption anisotropy for the wavelengths emitted by polarized light emitting plates A to C, that is, they have polarization characteristics. When polarized plates A to E have a photometric correction monomer transmittance that is roughly the same as that of filter F with a transmittance of 70%, filter G with a transmittance of 80%, and filter H with a transmittance of 90%, the absorbance of the axis showing the strongest absorption is high.

From Table 3 and Table 4, we can see that the highest absolute values of a*-s and b*-s of polarizers A to C and filters F to H are also within 2.072. In particular, the absolute values of a*-s and b*-s of polarizers A to C are within 1, which means they have a neutral color hue.

(Production of polarizing plate J for ultraviolet region)

A polyvinyl alcohol film (VF-PS #7500 manufactured by KURARAY) with a thickness of 75 μm was immersed in 40°C warm water for 3 minutes to swell the film. The swollen film was immersed in a 45°C aqueous solution containing 0.8 parts of C.I. Direct Yellow 28, 1.0 parts of Glauber's salt, and 1500 parts of water for 5 minutes to contain the solution. The obtained film was immersed in a 3% boric acid aqueous solution at 50°C for 5 minutes and stretched 5 times at the same time. The stretched film was kept in the original tight state and washed with water at room temperature for 20 seconds, and dried at 70°C for 9 minutes to obtain a polarizing element for the ultraviolet region. On the other hand, a triacetylcellulose film (ZRD-60 manufactured by Fuji Film Co., Ltd.) containing no ultraviolet absorber was treated with a 1.5 equivalent sodium hydroxide aqueous solution at 35°C for 10 minutes on both sides, washed with water, and dried at 70°C for 10 minutes. Then, an aqueous solution containing 4% polyvinyl alcohol resin (NH-26 manufactured by VAM & POVAL Co., Ltd. of Japan) was layered on both sides of the prepared polarizing element for the ultraviolet region, dried at 70°C for 8 minutes, and an anti-reflection layer (AR layer) was set on the surface to obtain a polarizing plate J for the ultraviolet region with a light correction monomer transmittance of 90.26% consisting of AR layer/TAC/polarizing element for the ultraviolet region/TAC/AR layer.

Table 5 shows the Ky, Kz, single transmittance Ts, orthogonal transmittance Tc, polarization degree ρ, and photometrically corrected single transmittance (Ys) of the obtained polarizing plate J for the ultraviolet region at 375nm and its λmax (405nm); Figure 6 shows the Ky and Kz of each wavelength of the obtained polarizing plate for the ultraviolet region. It can be seen from Table 5 and Figure 6 that the polarizing plate for the ultraviolet region used in this application has high polarization characteristics in the range of 350 to 450nm.

<Implementation Example 1>

The polarized light emitting plate A and the filter G (neutral density filter ND-0.1 manufactured by Fuji Film Co., Ltd.) are bonded together with an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) to form the optical system of the present invention. From Tables 1, 2 and 4, it can be seen that the optical system satisfies formula (2).

<Implementation Example 2>

The polarized light emitting plate A, the filter F with adhesive function, and TAC are bonded in this order to form the optical system of the present invention. From Table 1, Table 2, and Table 4, it can be seen that the optical system satisfies equations (1) and (2).

<Implementation Example 3>

The optical system of the present invention is formed by bonding the two plates with an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) in such a way that the axis with the highest light absorption of polarizing plate A (the orientation axis of polarizing pigment) and the axis with the highest light absorption of polarizing plate A (the orientation axis of dichroic pigment) are orthogonal. From Table 1, Table 2 and Table 3, it can be seen that the optical system satisfies equations (2), (3) and (4).

<Implementation Example 4>

The optical system of the present invention is formed by bonding the two plates with an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) in such a way that the axis with the highest light absorption of polarizing plate A (the orientation axis of polarizing pigment) and the axis with the highest light absorption of polarizing plate D (the orientation axis of dichroic pigment) are orthogonal. From Table 1, Table 2 and Table 3, it can be seen that the optical system satisfies equations (1), (2), (3) and (4).

<Implementation Example 5>

The optical system of the present invention is formed by bonding the two plates with an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) in such a way that the axis with the highest light absorption of polarizing plate B (the orientation axis of polarizing pigment) and the axis with the highest light absorption of polarizing plate B (the orientation axis of dichroic pigment) are orthogonal. From Tables 1, 2 and 3, it can be seen that the optical system satisfies equations (1), (2), (3) and (4).

<Implementation Example 6>

The optical system of the present invention is formed by bonding the two plates with an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) in such a way that the axis with the highest light absorption of polarizing plate B (the orientation axis of polarizing pigment) and the axis with the highest light absorption of polarizing plate A (the orientation axis of dichroic pigment) are orthogonal. From Tables 1, 2 and 3, it can be seen that the optical system satisfies equations (1), (2), (3) and (4).

<Implementation Example 7>

The optical system of the present invention is formed by bonding the two plates with an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) in such a way that the axis with the highest light absorption of polarizing plate B (the orientation axis of polarizing pigment) and the axis with the highest light absorption of polarizing plate D (the orientation axis of dichroic pigment) are orthogonal. From Table 1, Table 2 and Table 3, it can be seen that the optical system satisfies equations (1), (2), (3) and (4).

<Implementation Example 8>

The optical system of the present invention is formed by bonding the two plates with an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) in such a way that the axis with the highest light absorption of the polarizing plate C (the orientation axis of the polarizing pigment) and the axis with the highest light absorption of the polarizing plate C (the orientation axis of the dichroic pigment) are orthogonal. From Tables 1, 2 and 3, it can be seen that the optical system satisfies equations (1), (2), (3) and (4).

<Implementation Example 9>

The optical system of the present invention is formed by bonding the two plates with an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) in such a way that the axis with the highest light absorption of polarizing plate C (the orientation axis of polarizing pigment) and the axis with the highest light absorption of polarizing plate B (the orientation axis of dichroic pigment) are orthogonal. From Table 1, Table 2 and Table 3, it can be seen that the optical system satisfies equations (1), (2), (3) and (4).

<Implementation Example 10>

The optical system of the present invention is formed by bonding the two plates with an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) in such a way that the axis with the highest light absorption of polarizing plate A (the orientation axis of polarizing pigment) and the axis with the highest light absorption of polarizing plate E (the orientation axis of dichroic pigment) are orthogonal. From Table 1, Table 2 and Table 3, it can be seen that the optical system satisfies equations (2) and (4).

<Comparative Example 1>

Only polarized light emitting plate A is used as a sample of comparative example 1 without a visible light absorption filter.

<Comparative example 2>

The polarized light emitting plate A, the filter H with adhesive function, and TAC are sequentially attached to form an optical system. From Table 1, Table 2, and Table 3, it can be seen that the optical system does not satisfy equations (1) and (2).

<Comparative Example 3>

Only polarized light emitting plate B is used as a sample of comparative example 3 without a visible light absorption filter.

<Comparative Example 4>

The axis with the highest light absorption of polarizing plate B (the orientation axis of polarizing pigment) and the axis with the highest light absorption of polarizing plate I (iodine-based polarizing plate SKN-18243P) are orthogonal, and the two plates are bonded together with an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) to produce a sample for comparison.

<Comparative example 5>

Only polarized light emitting plate C is used as a comparative sample without a visible light absorption filter.

For the optical systems obtained in Examples 1 to 10 and the samples obtained in Comparative Examples 1 to 5, a 375nm LED light source (LED M375L4° with a mounting base manufactured by THORLABS) was used as a light source, and a liquid crystal unit was used as a phase control medium. The light source, the polarizing plate J for the ultraviolet region, the liquid crystal unit, the optical system of the present invention or the comparative sample were arranged in sequence to produce a display device capable of polarized light emission. The optical systems of Examples 3 to 10 or the samples of Comparative Examples 1 and Comparative Examples 3 to 5 were attached in a manner that the polarizing plate was located on the side of the liquid crystal unit, and the polarized light from the polarizing plate J for the ultraviolet region was irradiated through the liquid crystal unit in a manner that the polarized light emitting plate side was irradiated. The optical system of Example 1, Example 2 and Comparative Example 2 is to sequentially bond a polarized light emitting plate, a filter, and TAC to the liquid crystal unit, and the irradiation of polarized light from the polarizing plate J in the ultraviolet region is performed in a manner of irradiating the side of each polarized light emitting plate.

In the obtained polarized light emitting display device, the display device using the optical system of Examples 1 to 10 and the sample of Comparative Examples 1 to 5 was used as the object, and the light from the ultraviolet region to the near ultraviolet visible region was irradiated from a 375nm LED light source through a polarizing plate J for the ultraviolet region, and the luminous intensity (brightness) of the light state and the dark state when the liquid crystal unit was driven was measured using a 2D colorimeter (ProMetric IC-PMI2 manufactured by KONICAL MINOLTA Co., Ltd.). In addition, the liquid crystal unit used was a liquid crystal empty cell (KSRS-05/B111M1NSS05 manufactured by EHC Co.) sealed with a liquid crystal (ZLI-1083 manufactured by MERCK Co., Ltd.). In this application, the luminous intensity (brightness) of the bright state and the dark state is evaluated using the values when there is no external voltage (0V) and when an external voltage of 4V is applied.

Table 6 shows: the optical systems of Examples 1 to 10, the photometrically corrected single body transmittance (Ys- _{sys) measured every 5 nm of the liquid crystal unit bonded with the samples of Comparative Examples 1 to 5, the hue (a*-s, b*-s) of the liquid crystal unit, and the luminance in the bright state (EM-SYS -H} ), the luminance in the dark state (EM- _SYS-L ), and the contrast between the bright state and the dark state (CR- _SYS ) of a display device capable of polarized light emission using the liquid crystal unit.

From the results in Table 6, it can be seen that the display device using the optical system satisfying the above formula (1) or/and the above formula (2) has a light correction unit transmittance of more than 50% and displays a high contrast. When the optical system (a*-s, b*-s) of the present invention has a hue with a neutral color, it can be seen that the liquid crystal unit and the display device using the optical system of the present invention also have a neutral color. Furthermore, by comparing Example 1 with Example 3, it can be seen that although a visible light absorption filter with the same light correction unit transmittance is provided, when the visible light absorption filter is a polarizing plate as in Example 3, the display device using the optical system of the present invention has a high transmittance and a high contrast. Compared to the case of using only polarized light-emitting plates in Comparative Example 1, Comparative Example 3, and Comparative Example 5, or the case of using a filter with a transmittance of 90% that does not satisfy Formula (1) and Formula (2), the contrast of the display device in these embodiments is significantly higher, which shows the superiority of the optical system of the present invention. Furthermore, from the comparison between Embodiments 5 to 7 and Comparative Example 4, it can be seen that a display device with high transmittance and high luminous brightness can be obtained compared to the case of using a general polarizing plate.

[Industrial availability]

The optical system of the present invention can provide high contrast when emitting polarized light. In one aspect, the optical system of the present invention can improve the contrast of the luminous brightness on each axis of the film and has high transmittance in the visible light region. Therefore, in one aspect, an optical component and a display device such as a lens having the optical system of the present invention have high transparency in the visible light region and can display images by emitting polarized light, so it can be applied to a wide range of uses such as televisions, personal computers, tablet computer terminals, lenses, and further see-through displays. Furthermore, since ultraviolet light can be used to emit light, in one embodiment, the polarized light emitting element and polarized light emitting plate of the present invention can also be applied to functional media such as displays and sensors that require high safety. The functional media are required to be able to display functions by irradiating non-visible light such as ultraviolet light that is difficult for human eyes to see.

Claims (14)

An optical system comprises a polarized light emitting element and a filter, wherein the wavelength of the light absorbed by the polarized light emitting element is different from that of the light emitted by the polarized light emitting element at least in part, and the polarized light emitting element has an axial absorption anisotropy with different light absorption amounts, and can emit polarized light in the visible light region by absorbing light; the transmittance of the photometric correction monomer of the filter is 45 to 100% and can absorb light in the visible light region; and the optical system satisfies the relationship of formula (1) or formula (2), A _em-L-λmax × F _em-L ＜ 0.6×A _fi-em-λmax ＜ 0.35 Formula (1) In the formula, A _{em-L- λ max} represents the absorbance of the maximum absorption wavelength on the axis where the light absorption amount of the polarized light emitting element is the lowest, and F A _fi-em - _{λ max} represents the absorbance of the filter at the maximum emission wavelength of the polarized light emitting element; 0 ＜ TAF _{em -L} ＜ 0.7×TA _fi-em Formula (2) Wherein, TA _fi-em represents the value obtained by accumulating the absorbance of each wavelength of the filter within the wavelength range in which the polarized light emitting element emits light, and TAF _em-L represents the product of the absorbance of each wavelength on the axis with the lowest light absorption of the polarized light emitting element and the quantum yield on the axis with the lowest light absorption of the polarized light emitting element, which is the value accumulated within the aforementioned light absorption wavelength range of the polarized light emitting element. The optical system as described in claim 1 at least satisfies the aforementioned formula (2). An optical system as described in claim 1 or 2, wherein the transmittance of the photometric correction unit of the aforementioned filter is 50 to 99.9%. An optical system as described in claim 1 or 2, wherein the aforementioned filter is a polarizing element satisfying formula (3), A _{em-L- λ max} × F _em-L ＜ 0.6×A _{Pol-Kz-em-L- λ max} ＜ 0.7 Formula (3) In the formula, A _{em-L- λ max} represents the absorbance at the maximum absorption wavelength on the axis where the light absorption of the polarizing light-emitting element is the lowest, F _em-L represents the quantum yield on the axis where the light absorption of the polarizing light-emitting element is the lowest, and A _{Pol-Kz-em-L- λ max} represents the absorbance at the highest absorption axis of the polarizing element at the wavelength with the maximum emission on the axis where the emission of the polarizing light-emitting element is the weakest. An optical system as described in claim 1 or 2, wherein the aforementioned filter is a polarizing element satisfying formula (4), 0 < TAF _em-L < 0.7×TA _pol-Kz-em Formula (4) wherein TA _pol-Kz-em represents the accumulated absorbance of the polarizing element at each wavelength on the highest absorption axis within the wavelength range in which the polarizing element emits light, and TAF _em-L represents the same as formula (2). An optical system as described in claim 1 or 2, wherein the aforementioned filter is a polarizing element, and the aforementioned polarizing element and the aforementioned filter are provided in a manner such that an axis where the light emission of the aforementioned polarizing element is weakest and an axis where the absorbance of the aforementioned polarizing element is high are parallel. An optical system as claimed in claim 1 or 2, wherein the hue of the filter is -5＜a ^* ＜+3 and b ^* ＜±3. An optical system as described in claim 1 or 2, wherein the polarized light-emitting element contains a polarized light-emitting pigment, and the polarized light-emitting pigment is directional. An optical system as described in claim 1 or 2, wherein the polarized light emitting element emits polarized light by absorbing light in the ultraviolet region to the near-ultraviolet visible light region. An optical system as described in claim 1 or 2, wherein the polarized light emitting element has a maximum absorption wavelength of light in the ultraviolet region to the near-ultraviolet visible light region. An optical system as described in claim 1 or 2, wherein the aforementioned polarized light emitting element and the aforementioned filter are layered. The optical system as described in claim 1 or 2 is provided with a phase difference plate. An optical system as described in claim 1 or 2, wherein the filter is located on the viewing side. A display device comprises an optical system as described in any one of claims 1 to 13.

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