JP2020076972A - Polarizing light emitting plate and optical apparatus having the same - Google Patents

Abstract

To provide a plate providing emission wavelength with highly bright polarizing light, from which films having different optical characteristics depending on the emission and non-emission states over visible and ultraviolet regions are obtained to achieve various features relating to security, design, etc.SOLUTION: A polarizing light emitting plate as a device capable of emitting polarizing light with light absorption comprises a polarizing light emitting device which emits polarizing light in a wavelength range of at least 400 to 700 nm, with a difference in wavelength between the light absorbed by the device and the polarizing light emitted from the device, and a layer which can reflect light in the wavelength range absorbed by the polarizing light emitting device.SELECTED DRAWING: None

Description

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

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

  Generally, a polarizing film constituting a polarizing plate is produced by stretching or aligning a film of polyvinyl alcohol or a derivative thereof by dyeing or containing iodine or a dichroic dye, or dehydrochlorination of a polyvinyl chloride film or It is produced by producing a polyene by dehydration of a polyvinyl alcohol film and orienting it. Since a polarizing plate composed of such a conventional polarizing film uses a dichroic dye having absorption in the visible region, its transmittance is lowered. For example, the transmittance of a commercially available general polarizing plate is 35 to 45%.

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

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

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

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

  The present invention relates to an element capable of emitting polarized light by utilizing absorption of light, in which the wavelength of light absorbed by the element is different from that of light emitted in polarized light, and the wavelength range is at least 400 to 700 nm. A polarized light emitting element which emits polarized light, and a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element, and a polarized light emitting plate having high brightness and absorption for each wavelength, An object of the present invention is to provide a polarized light emitting plate having different transmission and light emission, and a display device thereof.

  The inventors of the present invention have conducted extensive studies to achieve such an object, and as a result, in an element capable of emitting polarized light utilizing absorption of light, the element emits polarized light and the wavelength of light absorbed. Polarized light emission that includes a polarized light-emitting element that emits light polarized in a wavelength range of at least 400 to 700 nm and that is different from the wavelength of, and a layer that can reflect light in the absorption wavelength range of the polarized light-emitting element. It was found that the plate emits polarized light with high brightness while having a high degree of polarization, and that the absorption, transmission and light emission are different for each wavelength.

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

  The polarized light emitting plate, the optical film, and the optical device according to the present invention exhibit high polarization action at the emission wavelength while utilizing the incident light with high efficiency, and exhibit high brightness polarized light emission, and the wavelength. A polarized light emitting plate having different light absorption properties, light transmission properties, and light emission properties is provided. Since each of the polarized light emitting plate, the optical film and the optical device has a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element, it does not inhibit light emission and can maintain high transparency. Since the incident light can be used with high efficiency, the ultraviolet rays included in natural light can also be used with high efficiency, and for example, sunlight can also be used efficiently. Furthermore, when the light source that emits sunlight or light in the near-ultraviolet to near-ultraviolet visible range is used by converting the light into luminescence, it is possible to use light with a wavelength invisible to the human eye with high efficiency. Not only that, even if the incident light has a small amount of light, it is possible to realize polarized light emission with high efficiency. When the light reflected by the reflective layer has polarized light, the absorption anisotropy of the polarized light emitting element, that is, the polarization function in absorption and the polarization function in light emission, are used for absorption. The present invention leads to the present invention in which a special optical element utilizing the functions of polarization and anisotropy of each light in light emission and reflection can be manufactured.

  The present invention is an element capable of emitting polarized light by utilizing absorption of light, wherein the wavelength of light absorbed by the element is different from the wavelength of light emitted in polarized light, and the wavelength range is at least 400 to 700 nm. The present invention relates to a polarized light emitting plate that includes a polarized light emitting element that emits polarized light and a layer that can reflect light in the absorption wavelength range of the polarized light emitting element. The polarized light emitting plate is capable of emitting high brightness light while having a high degree of polarization, and by controlling the reflected polarization of the layer, reflection of light at each wavelength, transmission of light and It is possible to provide light having polarized lights having different light emission intensities. In general, an element that absorbs light of a specific wavelength and emits light of a wavelength different from the wavelength of the absorbed light is called a wavelength conversion element, but in the present application, the absorbed light is converted into emitted light having polarization. It is referred to as a “polarized light emitting element” in terms of conversion.

  An element capable of emitting polarized light by utilizing the absorption of light is used, and the wavelength of the light absorbed by the element is different from the wavelength of light emitted by polarized light, and the element is polarized in a wavelength range of at least 400 to 700 nm. The polarized light-emitting element that emits the light absorbs ultraviolet light to visible light, and emits light polarized at a wavelength different from the wavelength of the absorbed light and at least in the wavelength range of 400 to 700 nm. The layer is not limited as long as it is a moisturizing layer. In order to obtain an element capable of emitting the polarized light, it is necessary to include a compound having a light absorbing action in the element and utilize the light wavelength conversion function of the compound to emit polarized light. The material is not particularly limited as long as it can be formed or a material having a function of emitting polarized light can be formed as a layer. If it is limited to have a light absorbing effect on a specific wavelength, light of the specific wavelength is not transmitted, and thus it is also possible to optically design to transmit light of a wavelength other than the specific wavelength. It is possible to provide a light emitting element having a high transmittance only at a specific wavelength, not limited to the entire wavelength range. Particularly preferably, the element that absorbs light and emits polarized light has a light absorption wavelength in the near-ultraviolet to near-ultraviolet visible region. By having a light absorption wavelength in the near-ultraviolet to near-ultraviolet visible region, it is possible to provide an element having a high transmittance and capable of emitting visible-polarized light. As a preferable mode capable of emitting polarized light, the light absorption region of the polarized light emitting element is at least 350 to 430 nm, and the wavelength of light having emitted polarized light is at least 400 to 700 nm. Having it can be mentioned as one of the preferable forms of this application. In the specification of the present application, the above-mentioned polarized light-emitting element that emits light polarized in a wavelength range of at least 400 to 700 nm is referred to as a “polarized light-emitting element”. Enter. Further, the layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element may be referred to as a "reflection layer".

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

  The light emitted by the polarized light emitting element is preferably linearly polarized light. Linearly polarized light is light that can also be represented as a wave in the direction of a constant axis. By emitting linearly polarized light, that is, uniaxially polarized light, it becomes easy to design a display device such as a liquid crystal display. This means that most of commercially available liquid crystal displays and polarizing lenses use iodine-based polarizing plates or dye-based polarizing plates that can provide light that is linearly polarized light and that can provide linearly polarized light using dichroic dyes. Therefore, it can be easily considered that the linearly polarized light is suitable for industrial use. On the other hand, if you try to use circularly polarized light or elliptically polarized light, the design of the liquid crystal cell, and eventually the alignment of the liquid crystal used there, becomes complicated, or the design of the phase difference plate becomes significantly complicated, It is preferable that the polarized light is linearly polarized light, because industrial use is difficult and limited. The emission of linearly polarized light can be achieved, for example, by orienting the below-described polarized light-emitting dye in the same direction in the substrate. Further, the polarized light-emitting dye emits light that is uniaxially polarized, so that the intensity of the transmitted light is increased, and it is possible to provide light that is stronger than the theoretical theoretical emission intensity of the dye. Leading to. That is, it is possible to provide light having linearly polarized light with higher brightness. In addition, the linearly polarizing plate can be changed into various polarized lights by combining a retardation plate, which facilitates optical design. For example, it is possible to emit circularly polarized light by providing ¼λ for the emission wavelength, or it is possible to rotate the emitted linearly polarized light by 90 ° by providing ½λ for the emission wavelength. .. Therefore, since it is possible to adjust the polarization in various ways, it can be said that providing the retardation plate for the polarized light emitting element is one preferable mode of the present application.

  The polarized light-emitting dye preferably has an absorption anisotropy at a wavelength that absorbs light, in addition to emitting linearly polarized light by being oriented. The polarized light-emitting dye, for example, absorbs light in the near-ultraviolet to near-ultraviolet visible region, emits light in the visible region that is polarized by wavelength conversion of the absorbed light, but in the absorbed light, the orientation direction of the light It is preferable that the light absorption amount is different between the orientation direction and a direction different from the orientation direction. This indicates that the layer has a light absorption anisotropy, that is, has dichroism in absorption, and when a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element is provided, light transmission and light reflection are performed. Alternatively, in the light obtained by absorption, light having various polarization states different from those of the polarized light emitting element can be provided. When the reflective layer has an anisotropy of reflected light, that is, a polarized light reflection function, when used in combination with a polarized light emitting element having anisotropy of absorption of light, transmission, reflection, or absorption Since the obtained light can further provide different polarization states, light transmission or light non-transmission, or adjustment of the light amount thereof can be performed by controlling the polarization. The light absorption anisotropy obtained by orienting a polarized light emitting dye may be represented as a dichroic ratio (hereinafter, also referred to as RD). From the value of this dichroic ratio, the degree of orientation of the dye (hereinafter, (Described as Order Parameter) can be calculated. The dichroic ratio is the ratio of the absorption amount of the axis having the strongest absorption to the absorption amount of the axis having the lowest absorption. If the dichroic ratio is 5 to 80, light having high polarization can be emitted. It is preferably 10 or more and 80 or less, preferably 20 or more, more preferably 30 or more, and particularly preferably 40 or more. The orientation degree of the dye is a numerical value given by the following formula (I), preferably 0.85 or more and 1.00 or less, and particularly preferably 0.90 or more and 1.00 or less.

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

  A preferred example of the polarized light emitting device is a polarized light emitting device in which the polarized light emitting dye has at least a stilbene skeleton or a biphenyl skeleton in the dye molecule and the dye is oriented in a substrate. Below, one form of the manufacturing method is shown as an example.

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

<Method of manufacturing polarized light emitting element>
The method for producing the above polarized light emitting device is not limited to the following production method, but it is preferable to mainly use a film made of a polyvinyl alcohol resin and its derivative. A method of manufacturing a polarized light emitting device will be described by taking a case of using a film made of a polyvinyl alcohol-based resin and its derivative as an example.
The method for producing a polarized light emitting device comprises at least a step of preparing a base material, a swelling step of immersing the base material in a swelling liquid to swell the base material, and at least one of the polarized luminescent dyes having the swollen base material. Dyeing step of impregnating a dyeing solution to adsorb the polarized light-emission dye to the substrate, cross-linking the polarized light-emission dye in the substrate by immersing the substrate adsorbing the polarized light-emission dye in a solution containing boric acid Step, a stretching step of uniaxially stretching the crosslinked base material of the polarized light-emitting dye in a certain direction to arrange the polarized light-emitting dye in a certain direction, and further, if necessary, washing the washed base material with a cleaning liquid And / or a drying step of drying the washed substrate.

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

(Dyeing process)
The dyeing step will be described. In the dyeing step, one or more polarized luminescent dyes described below are adsorbed on the substrate obtained through the swelling step. The dyeing step is not particularly limited as long as it is a method capable of adsorbing a polarized light emitting dye on a substrate, for example, a method of immersing the substrate in a dyeing solution containing a polarized light emitting dye, or a substrate. Examples thereof include a method of applying a dyeing solution containing a polarized light emitting dye, and a method of immersing in a dyeing solution containing a polarized light emitting dye is preferable. The concentration of the polarized light emitting dye in the dyeing solution is not particularly limited as long as the polarized light emitting dye is sufficiently adsorbed in the substrate, but, for example, the concentration of the polarized light emitting dye in the dyeing solution is 0. It is preferably 0.0001 to 1% by mass, and more preferably 0.0001 to 0.5% by mass. The temperature of the dyeing solution in the dyeing step is preferably 5 to 80 ° C, more preferably 20 to 50 ° C, particularly preferably 40 to 50 ° C. The time for immersing the substrate in the dyeing solution can be adjusted as appropriate, and is preferably adjusted within 30 seconds to 20 minutes, more preferably 1 to 10 minutes. The polarized light-emitting dye contained in the dyeing solution may be used alone or in combination of two or more. The above-mentioned polarized light-emitting dyes have different emission colors due to differences in dye structure and the like. Therefore, by incorporating two or more types of the above-described polarized light-emitting dyes in the base material, the emission colors produced are appropriately adjusted to various colors. be able to. Further, if necessary, the dyeing solution may further contain one or more kinds of organic dyes and / or fluorescent dyes in addition to the polarized light emitting dyes.

(Polarized luminescent dye)
The polarized light-emitting dye is a compound or a salt thereof that has at least one of a stilbene skeleton and a biphenyl skeleton in the dye molecule in the structure and emits light by utilizing absorbed light, and emits fluorescence or phosphorescence. Examples thereof include those that emit fluorescence, and those that emit fluorescence are preferable. The polarized light-emitting dye has a fluorescent emission function, and at the same time, the dye has a dichroic ratio at an absorption wavelength of light, whereby polarized light can be emitted. In particular, a polarized light-emitting dye having a stilbene skeleton or a biphenyl skeleton in the dye molecule has excellent fluorescence emission properties and, when oriented, has the property of having a high dichroic ratio at the absorption wavelength. These are derived from the characteristics of each skeleton, and further improve these characteristics, and adjust various characteristics such as absorption wavelength, emission wavelength, light resistance, moisture resistance, ozone gas resistance, and other robustness and solubility. Depending on the purpose, it is possible to further introduce an arbitrary substituent into each of the above skeletons. In the introduction of the substituent, if the kind of the substituent or the selection of the substitution position is not preferable, even if a high degree of polarization can be realized as in the conventional dye-based polarizing plate, the amount of emitted light is significantly reduced. Since problems may occur, the selection of the type of substituent and the substitution position is particularly important in order to have excellent fluorescence emission characteristics and a high dichroic ratio. In addition, the above polarized luminescent dyes may be used alone or in combination of two or more.

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

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

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

  Examples of the carboxyalkyl group include a methylcarboxy group and an ethylcarboxy group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. Examples of the alkoxyl group include a methoxy group, an ethoxy group and a propoxy group. Examples of the aryloxy group include a phenoxy group and a naphthoxy group.

As good carbonylamido group optionally having the above substituent, for example, N- methyl - carbonyl amide group (-CONHCH _3), N- ethyl - carbonyl amide group (-CONHC ₂ H _5), N- phenyl - carbonyl and amide group (-CONHC ₆ H ₅₎ can be mentioned.

  Examples of the naphthotriazole group which may have a substituent include a benzotriazole group and a naphthotriazole group.

  Examples of the alkyl group having 1 to 20 carbon atoms which may have a substituent include direct groups such as methyl group, ethyl group, n-butyl group, n-hexyl group, n-octyl group and n-dodecyl group. Examples thereof include branched chain alkyl groups such as chain alkyl groups, isopropyl groups, sec-butyl groups, and tert-butyl groups, and cyclic alkyl groups such as cyclohexyl groups and cyclopentyl groups.

  Examples of the vinyl group which may have a substituent include a vinyl group, a methylvinyl group, an ethylvinyl group, a divinyl group, a pentadiene group and the like.

As good amido group optionally having the above substituent, for example, acetamide group (-NHCOCH _3), such as benzamido group (-NHCOC ₆ H ₅₎ can be mentioned.

  Examples of the aryl group which may have a substituent include a phenyl group, a naphthyl group, a proposed toracenyl group, a biphenyl group and the like.

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

  The above-mentioned optionally substituted carbonylamide group, optionally substituted naphthotriazole group, optionally substituted C1-20 alkyl group, optionally substituted As a substituent in a vinyl group, an amide group which may have a substituent, an ureido group which may have a substituent, an aryl group which may have a substituent, and a carbonyl group which may have a substituent Is not particularly limited, but may be the same as the substituent described in the above-mentioned amino group which may have a substituent.

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

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

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

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

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

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

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

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

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

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

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

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

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

The salts of the compounds represented by the above formulas (1) to (5) are salts formed with an inorganic cation or an organic cation. Examples of the inorganic cations include cations of alkali metals such as lithium, sodium, and potassium, and ammonium ions (NH ₄ ⁺ ). Examples of the organic cation include organic ammonium represented by the following formula (D).

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

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

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

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

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

(2) Other Dyes The polarized light emitting device preferably contains one or more dyes or salts thereof having a stilbene skeleton or biphenyl skeleton, but for the purpose of color adjustment and the like within a range that does not impair the polarized light emitting function. If desired, one or more other organic dyes or other fluorescent dyes may be further included. Other organic dyes are not particularly limited as long as they can control the color (hue) of the polarized light emitting element or the emission color, but those having a high dichroic property are preferable, and a stilbene skeleton or a biphenyl skeleton is used. A dye that has little influence on the polarization performance in the ultraviolet region is preferable. Examples of such other organic dyes include C.I. I. Direct. Yellow 12, C.I. I. Direct. Yellow 28, C.I. I. Direct. Yellow 44, C.I. I. Direct. Orange 26, C.I. I. Direct. Orange 39, C.I. I. Direct. Orange 71, C.I. I. Direct. Orange 107, C.I. I. Direct. Red2, C.I. I. Direct. Red31, C.I. I. Direct. Red 79, C.I. I. Direct. Red81, C.I. I. Direct. Red247, C.I. I. Direct. Blue69, C.I. I. Direct. Blue78, C.I. I. Direct. Green80, and C.I. I. Direct. Green59 etc. are mentioned. These organic dyes may be free acids or may be alkali metal salts (for example, Na salt, K salt, Li salt), ammonium salts or salts of amines. Further, as the other fluorescent dyes, generally disclosed fluorescent dyes can also be used for the purpose of adjusting the emission color, and are not particularly limited.

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

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

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

(Crosslinking process)
After the dyeing step or the preliminary washing step, the base material may contain a crosslinking agent. As a method of incorporating the crosslinking agent into the substrate, it is preferable to immerse the substrate in the treatment solution containing the crosslinking agent, while the treatment solution may be applied or applied to the substrate. As the crosslinking agent in the treatment solution, for example, a solution containing boric acid is used. The solvent in the treatment solution is not particularly limited, but water is preferable. The concentration of boric acid in the treatment solution is preferably 0.1 to 15% by mass, and more preferably 0.1 to 10% by mass. The temperature of the treatment solution is preferably 30 to 80 ° C, more preferably 40 to 75 ° C. Further, the treatment time of this crosslinking step is preferably 30 seconds to 10 minutes, more preferably 1 to 6 minutes. Since the method for producing a polarized light emitting device according to the present invention includes this cross-linking step, the obtained polarizing device has a high degree of polarization of the emitted light and exhibits a high contrast as a display body. This is an excellent action which cannot be expected from the function of boric acid used for the purpose of improving water resistance or light transmission in the prior art. Further, in the crosslinking step, if necessary, a fixing treatment may be additionally performed with an aqueous solution containing a cationic polymer compound. By the fixing treatment, the dye can be fixed in the polarized light emitting device. At this time, as the cationic polymer compound, for example, cation, dicyanamide and formalin polymerization condensate as a dicyan system, dicyandiamide / diethylenetriamine polycondensate as a polyamine system, epichlorohydrin / dimethylamine addition polymer as a polycation system, dimethyl A diallylammonium chloride / dioxide copolymer, a diallylamine salt polymer, a dimethyldiallylammonium chloride polymer, an allylamine salt polymer, a dialkylaminoethyl acrylate quaternary salt polymer and the like are used.

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

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

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

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

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

(Drying process)
After the washing step, a base material drying step is performed. The drying treatment can be carried out by natural drying, but in order to further improve the drying efficiency, it can be carried out by compression with a roll, removal of water on the surface with an air knife, a water-absorbing roll, or the like. It is also possible to do so. The temperature of the drying treatment is preferably 20 to 100 ° C, more preferably 60 to 100 ° C. The drying time is preferably 30 seconds to 20 minutes, more preferably 5 to 10 minutes.

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

  The above, a polarized light-emitting device having at least one of a stilbene skeleton or a biphenyl skeleton in the structure and containing a compound or a salt thereof that emits fluorescence is near-ultraviolet to near-ultraviolet visible region, that is, light in the invisible light region. Is absorbed by light in the near-ultraviolet to near-ultraviolet visible region, and the energy thereof is used to emit polarized light in the visible light region. Since the light emitted by the polarized light emitting element is polarized light in the visible light region, when the polarized light emitting element is observed through a general polarizing plate having a polarization function for light in the visible light region, the visible light By changing the angle of the axis of a general polarizing plate that has a polarizing function in the light region, it is possible to visually recognize polarized light with strong emission axis light and weak emission axis light (or non-emission axis light). You can 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, further preferably 95% or more, and particularly preferably 98% or more.

  The polarized light emitting element can transmit light in the visible light region without absorbing it. That is, the transmittance of light in the visible light region of the polarized light emitting device can be high with the transmittance corrected for the visibility, and the transmittance of 30 to 100% which is the transmittance of a general polarizing plate is provided. It is possible to If it is 60% or more, a liquid crystal display having a significantly high transparency can be obtained as compared with a conventional liquid crystal display, but it is preferably 70% or more, more preferably 80% or more, further preferably 85% or more, particularly It is preferably 90% or more. The above polarized light emitting device having at least one of the stilbene skeleton or the biphenyl skeleton in the structure and containing a compound or a salt thereof that emits fluorescence has a small absorption in the visible light region in the non-emission state, This is preferable because a polarized light emitting device having high transparency can be obtained, and since it is possible to emit light with a high degree of polarization in light emission, it is possible to provide a polarized light emitting film with high brightness.

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

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

  Examples of the member that can be used for the reflective layer include a reflective film having silver or aluminum deposited thereon, a dichroic filter, an anisotropic birefringent laminate, a film provided with a cholesteric liquid crystal layer having a helical alignment, and the like. It is not limited to these. Since the polarized light-emitting device mentioned as the preferred embodiment of the present application has absorption anisotropy, it is preferable that the layer capable of reflecting light in the near ultraviolet to visible region can reflect polarized light. Can be mentioned. Since the layer capable of reflecting light in the ultraviolet to visible region can reflect polarized light, various polarized light emitting plates using the reflected polarized light can be manufactured. For example, when the direction of the reflected polarized light and the orientation direction of the dye capable of emitting the polarized light in the polarized light emitting element are the same, not only the light absorbed by the dye in the polarized light emitting element but also the reflective layer Since the reflected light can be further absorbed, more light can be absorbed with respect to the light incident for the light emission of the polarized light emitting element, and the wavelength conversion can be performed to convert the visible light. Can be made to emit light. In this case, the polarized light that is not absorbed by the oriented dye contained in the polarized light-emitting element or that does not reflect the polarized light of the ultraviolet to visible region is transmitted as the polarized light, and thus is not transmitted. It can be separately used as highly polarized light in the ultraviolet to visible range. On the other hand, when the direction of the reflected polarized light is orthogonal to the orientation method of the dye capable of emitting polarized light in the polarized light emitting element, the axis in which the dye in the polarized light emitting element absorbs light and the orientation axis of the dye Since the light with a different axis from the absorption of the light is reflected by the reflective medium, it can function as a polarized light emitting plate that does not transmit the incident light at the wavelength where the absorption wavelength of the polarized light emitting element matches the wavelength that can be reflected. It is also possible to obtain the optical system using the reflected polarized light by using the light having the polarized light in the ultraviolet to visible range which is transmitted without being absorbed by the polarized light emitting element and which is reflected by the reflective layer. ..

  The dichroic filter capable of reflecting light of 300 to 430 nm refers to a lens or a film made of a dielectric multilayer film, and as a product, dichroic mirror glass (product name: HeatBuster) manufactured by Sigma Koki Co., Ltd., dichroic mirror filter ( Product name: NHOTH) and the like.

  It is preferable that the layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element is a multilayer film laminated structure containing two kinds of substances having different refractive indexes, and a layer capable of dividing polarized light into a plurality of layers. .. For example, it is possible to split polarized light by forming a multilayer film of two types of resins with different refractive indexes, and having an axis that reflects by utilizing the principle of thin film interference and an axis that transmits without reflection with no difference in refractive index. It can be used as a layer that reflects polarized light at a specific wavelength. In this case, transmitted light can also be used as polarized light. As the above-mentioned reflective layer formed of a multilayer film of two kinds of resins having different refractive indexes, the technology is disclosed in, for example, Japanese Patent No. 36241515, and is generally used as a reflective polarizing plate or a brightness enhancement film. It is used. Examples of the reflective polarizing plate and the brightness enhancement film include, for example, U.S. Pat. No. 3,610,729, WO95 / 17303, WO95 / 17692, WO95 / 17699, WO96 / 19347, WO99 / 36262, It is also disclosed in WO2005 / 0888363, JP2007-298634A, WO2011 / 074701, etc., and examples of the product include DBEF (manufactured by 3M Company). Further, it is preferable to use the above-mentioned reflection type polarizing plate because not only can uniaxial linearly polarized light be transmitted, but also light having a reversible axis can be reflected to the polarized light emitting element and the light can be effectively used. Therefore, the use of a reflective polarizing plate made of a multilayer film of two kinds of resins having different refractive indexes described above is mentioned as one preferable mode of the present invention.

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

  The cholesteric liquid crystal generally comprises a nematic liquid crystal having chirality or a mixture of a nematic liquid crystal and a chiral agent. Depending on the kind and addition amount of the chiral agent, or the film thickness and orientation of the liquid crystal containing the chiral agent, the direction of the spiral and the reflection wavelength can be arbitrarily designed. The method of obtaining is preferred. The nematic liquid crystal used in the present invention is used by fixing the helical alignment state unlike the liquid crystal operated by a so-called electric field. Therefore, it is preferable to use a nematic liquid crystal monomer having a polymerizable group.

  Examples of the nematic liquid crystal monomer having a polymerizable group include compounds having a polymerizable group in the molecule and exhibiting liquid crystallinity in a specific temperature range or concentration range. Examples of the polymerizable group include a (meth) acryloyl group, a vinyl group, a chalcone group, a cinnamoyl group, and an epoxy group. Further, in order to exhibit liquid crystallinity, it is preferable that a mesogen group is present in the molecule. Examples of the mesogen group include biphenyl group, terphenyl group, (poly) benzoic acid phenyl ester group, (poly) ether group and benzylideneaniline. Group, or a rod-like or plate-like group such as an acenaphthoquinoxaline group, or a discotic substituent such as a triphenylene group, a phthalocyanine group, or an azacrown group, that is, a group capable of inducing liquid crystal phase behavior. Liquid crystal compounds having rod-shaped or plate-shaped groups are known in the art as calamitic liquid crystals. Specific examples of the nematic liquid crystal monomer having a polymerizable group include polymerizable liquid crystals described in JP-A-2003-315556 and 2004-29824, PALIOCOLOR series (manufactured by BASF), and RMM series. (Manufactured by Merck) and the like. These nematic liquid crystal monomers having a polymerizable group can be used alone or in combination of two or more.

  The chiral agent is capable of right-handed or left-handed helical alignment of the nematic liquid crystal monomer having the polymerizable group, and like the nematic liquid crystal monomer having the polymerizable group, a compound having a polymerizable group is preferable. Examples of the chiral agent include Paliocolor LC756 (manufactured by BASF), compounds described in JP-A-2002-179668, and the like. The type of the chiral agent determines the direction of reflected circularly polarized light, and the reflection wavelength of the light reflecting layer can be changed according to the amount of the chiral agent added to the nematic liquid crystal. For example, as the amount of the chiral agent added increases, a light reflection layer that reflects a wavelength on the short wavelength side can be obtained. The addition amount of the chiral agent varies depending on the type of the chiral agent and the wavelength to be reflected, but in order to adjust the central reflection wavelength of the light reflection layer for normal light to a desired wavelength region, for example, a nematic liquid crystal having a polymerizable group is used. The amount is preferably about 0.5 to 30 parts by weight, more preferably about 1 to 20 parts by weight, and further preferably about 3 to 10 parts by weight, based on 100 parts by weight of the monomer.

  Further, it is also possible to add a polymerizable compound having no liquid crystallinity, which is capable of reacting with the nematic liquid crystal monomer having a polymerizable group. Examples of the polymerizable compound include ultraviolet curable resins and the like. Examples of the ultraviolet curable resin include dipentaerythritol hexa (meth) acrylate, a reaction product of dipentaerythritol penta (meth) acrylate and 1,6-hexamethylene diisocyanate, triisocyanate having an isocyanuric ring, and pentaerythritol triacrylate. Reaction product with (meth) acrylate, reaction product with pentaerythritol tri (meth) acrylate and isophorone diisocyanate, dipentaerythritol penta (meth) acrylate, dipentaerythritol tetra (meth) acrylate, pentaerythritol tetra (meth) Acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, tris (acryloxyethyl) isocyanurate, tris (methacryloxyethyl) isocyanurate, glycerol triglycidyl Reaction product of ether and (meth) acrylic acid, caprolactone-modified tris (acryloxyethyl) isocyanurate, reaction product of trimethylolpropane triglycidyl ether and (meth) acrylic acid, triglycerol di (meth) acrylate, Reaction product of propylene glycol diglycidyl ether and (meth) acrylic acid, polypropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate , Triethylene glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, reaction product of 1,6-hexanediol diglycidyl ether and (meth) acrylic acid, 1,6-hexanediol di (meth) acrylate , Glycerol di (meth) acrylate, reaction product of ethylene glycol diglycidyl ether and (meth) acrylic acid, reaction product of diethylene glycol diglycidyl ether and (meth) acrylic acid, bis (acryloxyethyl) hydroxyethyl isocyanate Nulate, bis (methacryloxyethyl) hydroxyethyl isocyanurate, reaction product of bisphenol A diglycidyl ether and (meth) acrylic acid, tetrahydrofurfuryl (meth) acrylate, caprolactone-modified tetrahydrofurfuryl (meth) acrylate, 2 -Hi Droxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, polypropylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, phenoxyhydroxypropyl (meth) acrylate, acryloylmorpholine, methoxypolyethylene glycol (meth) acrylate, methoxytetra Ethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, methoxyethyl (meth) acrylate, glycidyl (meth) acrylate, glycerol (meth) acrylate, ethylcarbitol (meth) acrylate , 2-ethoxyethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, 2-cyanoethyl (meth) acrylate, a reaction product of butyl glycidyl ether and (meth) acrylic acid, butoxytriethylene glycol ( Examples thereof include (meth) acrylate and butanediol mono (meth) acrylate. These may be used alone or in combination of two or more. It is important to add these UV curable resins having no liquid crystallinity to the extent that the nematic liquid crystal monomer having a polymerizable group does not lose liquid crystallinity, and preferably 100 parts by weight of the nematic liquid crystal monomer having a polymerizable group. With respect to 0.1 to 20 parts by weight, more preferably about 1.0 to 10 parts by weight.

  When the nematic liquid crystal monomer having the polymerizable group and the polymerizable compound are both UV-curable, a photopolymerization initiator may be added to cure the composition containing them by UV. .. As the photopolymerization initiator, for example, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1 (IRGACURE 907 manufactured by BASF), 1-hydroxycyclohexyl phenyl ketone (IRGA manufactured by BASF) Cure 184), 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone (BASF Corporation Irgacure 2959), 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropane. -1-one (Darocur 953 manufactured by Merck), 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one (Darocur 1116 manufactured by Merck), 2-hydroxy-2-methyl-1. -Phenylpropan-1-one (BASF Corporation Irgacure 1173), acetophenone compounds such as diethoxyacetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-2 -Benzoin compounds such as phenylacetophenone (IRGACURE 651 manufactured by BASF), benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyldiphenylsulfide, 3,3'- Benzophenone compounds such as dimethyl-4-methoxybenzophenone (Kayakyu MBP manufactured by Nippon Kayaku), thioxanthone, 2-chlorothioxanthone (Kayacure CTX manufactured by Nippon Kayaku), 2-methylthioxanthone, 2,4-dimethylthioxanthone (Kayakyu RTX) , Isopropylthioxanthone, 2,4-dicloiothioxanthone (Nippon Kayaku Kayakyu CTX), 2,4-diethylthioxanthone (Nippon Kayaku DEATX), or 2,4-diisopropylthioxanthone (Nippon Kayaku DITX) And other thioxanthone compounds. Preferably, for example, Irgacure TPO, Irgacure TPO-L, Irgacure OXE01, Irgacure OXE02, Irgacure 1300, Irgacure 184, Irgacure 369, Irgacure 379, Irgacure 819, Irgacure 127, Irgacure 907 or Irgacure 1173 (all manufactured by BASF), Particularly preferred are Irgacure TPO, Irgacure TPO-L, Irgacure OXE01, Irgacure OXE02, Irgacure 1300 or Irgacure 907. These photopolymerization initiators may be used alone or in a mixture of two or more at an arbitrary ratio.

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

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

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

  Using the cholesteric liquid crystal, as a method for producing the reflective layer, for example, a nematic liquid crystal monomer having a polymerizable group, reflecting a desired wavelength, and the helical alignment is right-handed or left-handed, Add the required amount of chiral agent. Next, these are dissolved in a solvent and a photopolymerization initiator is added. After that, this solution is applied on a polarized light emitting device or a plastic substrate such as PET film so that the thickness is as uniform as possible, and while removing the solvent by heating, it becomes a cholesteric liquid crystal on the substrate to form a desired spiral alignment. Let it stand for a certain period of time under such temperature conditions. At this time, if the plastic film surface is subjected to orientation treatment such as rubbing or stretching before coating, the orientation of the cholesteric liquid crystal can be made more uniform, and the haze value of each light reflecting layer can be reduced. Becomes Then, while maintaining this alignment state, the above reflection layer is obtained by irradiating ultraviolet rays with a high pressure mercury lamp or the like to fix the alignment. For example, when a right-handed spiral orientation chiral agent is selected, the resulting light-reflecting layer and light-reflecting layer selectively reflect light that is right-handed circularly polarized light, and a left-handed helical orientation chiral agent is selected. The visible light reflection layer and the light reflection layer thus obtained selectively reflect light that is left-handed circularly polarized light. The phenomenon of selectively reflecting specific circularly polarized light is called selective reflection, and the wavelength band in which selective reflection is performed is called the selective reflection region.

  Another method of adjusting the reflectance of the reflective layer with respect to ordinary light is to change the thickness of the reflective layer according to the type of cholesteric liquid crystal or chiral agent. The thickness of the reflective layer varies depending on the type of cholesteric liquid crystal and chiral agent used, but is, for example, about 0.5 to 10 μm. When the polarizing layer is produced by laminating the reflective layer thus obtained on the polarized light emitting element, the polarized light emitting element is coated directly on the polarized light emitting element, or the thickness is made as uniform as possible on a plastic substrate such as a PET film. It may be provided by being transferred and adhered to the polarized light emitting element with an adhesive or the like. Since the cholesteric liquid crystal layer having a helical alignment has a function of selectively reflecting circularly polarized light, it reflects a specific wavelength as circularly polarized light. Therefore, in order to convert the circularly polarized light reflected from the cholesteric liquid crystal layer having the helical alignment into light having another polarization state, for example, linearly polarized light, a 1 / 4λ phase difference plate or the like is used. In that case, since the cholesteric liquid crystal layer having a helical alignment can function as a polarizing plate capable of reflecting light that is linearly polarized light, it is also possible to use a retardation plate together. It can be mentioned as one preferable form. That is, an optical device provided with the above-mentioned polarized light emitting plate and a general retardation film, for example, a film or layer capable of controlling the phase with respect to the wavelength of ultraviolet light that can be reflected or the visible wavelength that can be reflected. Film is one of the forms.

  Since the reflectance of light is 30 to 100% in the reflective layer, it is possible to develop a high degree of polarization at an emission wavelength and a high-brightness polarized light emission while utilizing light with higher efficiency. To provide the above optical device. In particular, the ability to use light in the near ultraviolet to visible region with high efficiency also leads to the efficient use of ultraviolet light in the natural world, for example, sunlight, and further emits light in the near ultraviolet to visible region. When a light source is used, polarized light emission can be realized with high efficiency even with a limited light output. As described above, when the light reflectance is 30 to 100%, more highly efficient polarized light emission can be realized in the absorption band of the polarized light emitting element, preferably 40 to 100%, more preferably 50 to 100. %, Particularly preferably 60 to 100%.

  Further, when the visible light transmittance of the reflective layer is 50 to 100%, a polarized light emitting plate having high transmittance can be provided. The high transmittance in the visible region makes it possible to impart transparency to the polarized light emitting plate while emitting light. In particular, by emitting polarized light, display using the polarized light becomes possible and it becomes possible to use as a polarized light source having transparency. For example, when applied to a liquid crystal display device, it can be used as a see-through display having transparency, a transparent polarized light source for liquid crystal display, and the like. As described above, when the light transmittance of the reflective layer in the visible region is 50 to 100%, the transmittance is 30 to 45%, which is the transmittance of general polarizing plates such as iodine type polarizing plates and dye type polarizing plates. It is also possible to impart high transparency, more preferably 60 to 100%, more preferably 70 to 100%, particularly preferably 90 to 100%.

  A polarized light emitting plate having a transparent protective layer, which is provided so as to be in contact with the polarized light emitting element or the reflective layer, or with respect to a polarized light emitting plate in which a polarized light emitting element and a reflective layer are laminated, Can also be The transparent protective layer is used to improve the durability and handleability of the polarized light emitting element, and the transparent protective layer has no influence on the polarization function of the polarized light emitting element or the light reflection by the reflective layer. is not. The transparent protective layer may be provided on both sides of the polarized light emitting plate, but may be provided on either one side, that is, only one side, or may be laminated between the reflection plate and the polarized light emitting element. good.

  The transparent protective layer is preferably a transparent protective film having excellent optical transparency and mechanical strength. Further, the transparent protective layer is preferably a film having a layer shape capable of maintaining the film shape, and in addition to transparency and mechanical strength, it is a plastic film excellent in thermal stability, moisture shielding property, etc. preferable. Examples of the material for forming such a transparent protective layer include a cellulose acetate film, an acrylic film, a fluorine film such as a tetrafluoroethylene / propylene hexafluoride copolymer, a polyester resin, and a polyolefin. Examples thereof include a film made of a resin or a polyamide resin, and a triacetyl cellulose (TAC) film or a cycloolefin film is preferably used. The thickness of the transparent protective layer is preferably 1 μm to 200 μm, more preferably 10 μm to 150 μm, and particularly preferably 40 μm to 100 μm. The method for providing the transparent protective layer on the polarized light emitting element is not particularly limited, but for example, it is also possible to stack the transparent protective layer on the polarized light emitting element and laminate it by a known formulation.

  The polarized light emitting plate may further include an adhesive layer for bonding the transparent protective layer and the polarized light emitting element, and the transparent protective layer and the reflective layer, respectively. The adhesive constituting the adhesive layer is not particularly limited, and examples thereof include polyvinyl alcohol adhesives, urethane emulsion adhesives, acrylic adhesives, polyester-isocyanate adhesives, and the like. A polyvinyl alcohol adhesive is preferably used. After forming the adhesive layer, drying or heat treatment is performed at an appropriate temperature to produce the polarized light emitting plate.

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

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

  INDUSTRIAL APPLICABILITY The polarized light emitting plate, the optical film, and the display device of the present application can be effectively used as a highly efficient polarized backlight for a liquid crystal display, and can also be used as a see-through display or a polarized light source that can emit light with high efficiency. Furthermore, it can be utilized as an element, a light source, or a display device that can efficiently emit polarized light such as natural light as light in the visible range. That is, the polarized light emitting plate, the optical film, and the display device of the present application can efficiently emit polarized light particularly outdoors.

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

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

  62.3 parts of the formula (6) obtained above was added to 300 parts of water and stirred, and the pH was adjusted to 10.0 using a 25% aqueous sodium hydroxide solution. 20 parts of 28% ammonia water and 9.0 parts of copper sulfate pentahydrate were added to the obtained solution, and the mixture was stirred at 90 ° C. for 2 hours. 25 parts of sodium chloride was added to the obtained reaction solution, the precipitated solid was separated by filtration, and further washed with 100 parts of acetone to obtain 40.0 parts of a wet cake of the compound of the following formula (7). By drying this wet cake with a hot air dryer at 80 ° C., 20.0 parts of a compound of formula (7) below (λmax: 376 nm), which is a dye capable of emitting polarized light used in the present application, was obtained.

(Production of polarized light emitting element)
A polyvinyl alcohol film (VF-PS # 7500 manufactured by Kuraray Co., Ltd.) having a thickness of 75 μm was immersed in warm water at 40 ° C. for 3 minutes to swell the film. The film obtained by swelling was 1.0 part by weight of 4,4′-bis- (sulfostyryl) biphenyl disodium aqueous solution (Tinopal NFW Liquid manufactured by BASF) described in Compound Example 5-1. The obtained compound (7) was immersed for 4 minutes in an aqueous solution containing 0.4 parts by weight of Glauber's salt, 1.0 part by weight of Glauber's salt and 1500 parts by weight of water at 45 ° C. After the dipping, the obtained film was stretched in a 3% aqueous solution of boric acid at 50 ° C. for 5 minutes so as to have a length of 5 times. The stretched film was washed with water at room temperature for 20 seconds while maintaining the stretched state, and then dried to obtain a polarized light emitting device of the present application. The order parameter of the polarized light emitting device calculated by the above formula (I) was 0.91, the wavelength of maximum absorption was 379 nm, and its absorption band was 350 to 410 nm. When the polarized light emitting device was irradiated with ultraviolet rays, white light was emitted, and the emitted light was confirmed through a general polarizing plate (SKN-18243P manufactured by Polatechno Co., Ltd.). In the direction, white polarized light emission was shown, while polarized light emission was not confirmed in the axis orthogonal to the stretching axis. That is, the polarized light emitting element was an element that emits linearly polarized light.

(Production of polarized light emitting plate using polarized light emitting element)
A triacetylcellulose film (ZRD-60 manufactured by Fuji Film Co., Ltd.) containing no ultraviolet absorber is treated with a 1.5 N aqueous sodium hydroxide solution at 35 ° C. for 10 minutes, washed with water, and then dried at 70 ° C. for 10 minutes. Let The triacetyl cellulose film obtained by the alkali treatment was laminated on one surface of the polarized light emitting element with 100 parts by weight of water and 4 parts by weight of polyvinyl alcohol resin (NH-26 manufactured by Nippon Vinegar Bipovar Co., Ltd.), and the mixture was heated at 70 ° C. for 10 days. It was dried for a minute. The obtained film had the properties of a polarized light emitting film without impairing the optical properties of the obtained polarized light emitting device. As a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting device through a pressure-sensitive adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) on the film obtained by drying, a reflectance of 350 to 780 nm. A reflective film having a performance of about 88% and a visible transmittance of 0% (BL film manufactured by Oike Kogyo Co., Ltd.) is laminated to form a triacetyl cellulose film / polarized light emitting device / adhesive layer / reflection layer. A polarized light emitting plate was obtained.

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

[Example 3]
Instead of the BL film used as a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element in Example 1, reflection type polarized light having optical characteristics of reflectance of about 50% and transmittance of about 45% at 380 to 780 nm. A plate (DBEF manufactured by 3M Co.) was used in the same manner, and the bonding was performed in the same manner except that the transmission axis of the reflective polarizing plate and the polarized light emission axis of the polarized light emitting element were bonded at right angles. A polarized light emitting plate was obtained.

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

[Example 5]
(Preparation of cholesteric liquid crystal layer having fixed helical alignment)
10 parts by weight of a polymerizable liquid crystal monomer (LC242, manufactured by BASF), 0.66 parts by weight of a chiral agent (LC756, manufactured by BASF), 0.38 parts by weight of a polymerization initiator (Irgacure TPO, manufactured by BASF), and 24.9 parts by weight of toluene. Parts, a composition comprising 0.005 parts by weight of a surfactant (BYK-361N manufactured by BYK Chemie) is rubbed by the method described in Example 1 of JP-A-2002-90743, PET film (Toyobo Co., Ltd. A4100 manufactured by A4100, which has no undercoat layer) is coated with a spin coater at 250 rpm for 30 seconds, 2000 rpm for 5 seconds, and 20 rpm for 10 seconds. After coating, the coating is dried at 80 ° C. for 1 minute, and dried. A high-pressure mercury lamp (manufactured by Harrison Toshiba Lighting Co., Ltd.) was used for UV irradiation at 80 W output for 5 seconds to fix the cholesteric liquid crystal phase to obtain a single reflective medium on each PET film. The obtained liquid crystal layer was coated with an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) so as to have a thickness of 20 μm, the adhesive layer was attached to glass, and then the PET film was peeled off to obtain a liquid crystal layer / adhesive layer / glass. Absolute specular reflection measurement was performed with a spectrophotometer (UV-3600 manufactured by Shimadzu Corp.) to find that the cholesteric liquid crystal layer (A) had a maximum selective reflection wavelength at 394 nm and a reflectance of 41.0% at the wavelength. It turned out that it was obtained.

(Fabrication of Polarized Light Emitting Plate with Cholesteric Liquid Crystal Layer Having Fixed Helical Alignment)
The BL film used as a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting device in Example 1 was replaced with a cholesteric liquid crystal layer (A) having a helical alignment having an adhesive layer, and a triacetyl cellulose film / polarized light emission was used. A sample having a structure of element / adhesive layer / cholesteric liquid crystal layer (A) was prepared to obtain a polarized light emitting plate of the present application.

[Example 6]
In the preparation of the cholesteric liquid crystal layer having the fixed helical alignment of Example 5, the chiral agent was replaced by 0.724 parts by weight, and the cholesteric liquid crystal had a helical alignment of 365 nm and a reflectance of 39.4% at the wavelength. A liquid crystal layer (B) was prepared and further bonded to the polarized light emitting plate of Example 5, and the BL film used as a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element of Example 1 was used as an adhesive layer. In place of the cholesteric liquid crystal layer (A) and the cholesteric liquid crystal layer (B) having a helical alignment having a triacetyl cellulose film / polarized light emitting device / adhesive layer / cholesteric liquid crystal layer (A) / adhesive layer / cholesteric liquid crystal layer (B). A sample having the above structure was prepared to obtain the polarized light emitting plate of the present application.

[Example 7]
In the production of a polarized light emitting plate using the polarized light emitting element in Example 1, a triacetyl cellulose film (ZRD-60 manufactured by Fuji Film Co., Ltd.) containing no ultraviolet absorber was treated with a 1.5 N sodium hydroxide aqueous solution at 35 ° C. At room temperature for 10 minutes, washed with water, and then dried at 70 ° C. for 10 minutes. The triacetyl cellulose film obtained by the alkali treatment was laminated on one surface of the polarized light emitting element with 100 parts by weight of water and 4 parts by weight of polyvinyl alcohol resin (NH-26 manufactured by Nippon Vinegar Bipovar Co., Ltd.), and the mixture was heated at 70 ° C. for 10 days. The same process is performed until the film is dried, and the film obtained by the drying is subjected to an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) as a 1/4 λ retardation plate at a wavelength of 380 nm and a retardation value of 95 nm. A polyvinyl alcohol film having a slow axis of 45 ° with respect to the stretching axis of the polarized light-emitting device, and a reflective film (tail) through an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.). (BL film manufactured by Ike Kogyo Co., Ltd.) was attached to obtain a polarized light emitting plate of the present application having a structure of triacetyl cellulose film / polarized light emitting element / adhesive layer / retarder / adhesive layer / reflection layer.

[Comparative Example 1]
In the production of the polarized light emitting plate of Example 1, 100 parts by weight of water was added to both sides of the polarized light emitting element of the triacetyl cellulose film obtained by alkali treatment, and 4 parts by weight of polyvinyl alcohol resin (NH-26 manufactured by Nippon Vinegar Bipovar Co., Ltd.). Comparative example sample was prepared in the same manner as above except that a triacetyl cellulose film / polarized light emitting device / triacetyl cellulose film was obtained by laminating via a part and drying at 70 ° C. for 10 minutes. The obtained sample had the performance of a polarized light emitting element, and it was confirmed that triacetyl cellulose did not impair the optical characteristics of the polarized light emitting element.

[Comparative Example 2]
A comparative example sample was prepared in the same manner as in Example 5, except that a cholesteric liquid crystal layer having no helical alignment (a liquid crystal layer that does not perform selective reflection) was prepared without using a chiral agent.

The obtained polarizing plate was evaluated as follows.
[Evaluation]
(H-1) Single transmittance Ts
The single transmittance Ts of each measurement sample was measured using a spectrophotometer (“U-4100” manufactured by Hitachi, Ltd.). Here, the single-piece transmittance Ts is the transmittance of each wavelength when one measurement sample is measured. The measurement was performed over a wavelength range of 220 to 780 nm.
(H-2) Polarization degree ρ and visibility correction polarization degree ρy
The polarization degree ρ of each measurement sample was obtained by substituting the parallel transmittance Tp and the orthogonal transmittance Tc into the following formula (II). For ρy, the value displayed after measurement by U-4100 was used as this result.

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

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

(Formula 3)

(H-4) Measurement of reflectance The relative reflectance was measured with a spectrophotometer (UV-3600 manufactured by Shimadzu Corp.) at an incident angle and a reflection angle of 5 ° with reference to the triacetylcellulose film. The obtained results of the respective wavelengths were used as the reflectances of Examples and Comparative Examples.

  The polarized light-emitting device obtained in Example 1 had a single transmittance of 375 nm (Ts 375 (%)), a polarization degree of 375 nm (ρ 375 (%)), a single transmittance of 390 nm (Ts 390 (%)), 390 nm. Degree of polarization (ρ 390 (%)), single transmittance at 465 nm (Ts 465 (%)), polarization degree at 465 nm (ρ 465 (%)), transmittance corrected to visual sensitivity (Ys (%)), Table 1 shows the polarization degree (ρy (%)) corrected to the luminosity factor. From the results in Table 1, the polarization performances of the obtained polarized light emitting device in the ultraviolet region and the visible region can be known.

(H-5) Measurement of polarization of emitted light As a light source, an ultraviolet LED 375 nm hand-light type black light (“PW-UV943H-04” manufactured by Nichia Corporation) was used, and an ultraviolet light transmitting / visible cut filter was used for the light source. (IUV-340 manufactured by Isuzu Seiko Glass Co., Ltd.) was installed to cut visible light, and only light in the ultraviolet region was made incident from the triacetyl cellulose side of the measurement samples obtained in each Example and Comparative Example. The polarized light emitting element was irradiated with light in the ultraviolet region before the reflective medium. The light emitted by the polarized light emitting element by the light irradiation, the light on the side of the polarized light emitting element and the light on the side of the reflective medium (the transmitted light from the reflective medium of the polarized light emitting element) is measured by a spectral irradiance meter (USH- 40 "), a polarizing plate having a polarizing function for light in the visible range and the ultraviolet range (" SKN-18043P "manufactured by Polatechno Co., thickness 180 μm, Ys is 43%) is provided in the light receiving part thereof, and The absorption axis of the polarizing plate was changed and the state of polarized light emission was measured. That is, the light from the ultraviolet light source is transmitted through the ultraviolet ray transmitting / visible cut filter so that only the ultraviolet rays can be irradiated to the polarized light emitting element, and the ultraviolet light is incident on the polarized light emitting element and the reflective medium in this order. Then, the emission brightness of the polarized light at that time was measured on both the polarized light emitting element side and the reflective medium side. Lw and Ls were measured with Lw (weak emission axis) as the light of the axis that gives the weakest emission of each measurement sample and Ls (strong emission axis) as the amount of emission of the strongest emission axis of the measurement sample. By evaluating the amount of light emitted in the visible range when the absorption axes of the measurement sample and a general polarizing plate are parallel and when they are orthogonal, the evaluation of the polarized emission in the visible range of 400 to 700 nm can be performed. went.

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

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

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

  Table 3 shows the optical characteristics based on the wavelength showing the maximum polarization degree of the polarized light emitting plates obtained in Examples 1 to 7 and Comparative Example 1. Since the transmittances of Examples 1 and 7 were 0%, the wavelength showing the maximum degree of polarization in reflection was taken as the maximum polarization wavelength. On the other hand, the comparative example 2 has almost the same performance as the comparative example 1, and therefore the description is omitted. In Table 3,-(hyphen) indicates that polarization was not observed due to no light transmission or light reflection.

  Comparative Example 1 has the performance of a polarized light emitting device, and its transmittance is 44.43% at the wavelength showing the polarization degree at the time of maximum absorption, and the kind of polarized light when transmitted is It was linearly polarized light, and light reflection was 0% (equivalent to a triacetyl cellulose film). On the other hand, in Example 1, the transmittance was 0%, and the polarized light emitting plate showing the reflected polarized light was obtained. On the other hand, in Example 7, by using the ¼λ retardation plate at the absorption wavelength of the polarized light emitting element in Example 1, the reflectance measured from the polarized light emitting element side was a remarkably low value of 0.23%. I understand that. It can be seen that in Example 2, a polarized light emitting plate that can obtain linearly polarized light in light transmission and light reflection is obtained. In addition, in Example 3 and Example 4, it can be seen that even if the same reflective polarizing plate is used as the reflective medium, if the axes are different, the transmittance and reflectance in the absorption band of the polarized light emitting plate are significantly different. .. In Example 5 and Example 6, it was found that by providing the cholesteric liquid crystal layer having the helical alignment, the transmitted light becomes circularly polarized light, and the reflected light can be provided although the transmittance is high. In addition, in Examples 5 and 6, the transmittance is equal to that in Comparative Example 1 except for the wavelength reflected by the cholesteric liquid crystal layer having the helical alignment, and the linearly polarized light emitted by the polarized light emitting element is used. Was transparent. That is, it was found that the fifth and sixth embodiments can provide different polarization states depending on the wavelength.

  Table 4 shows the optical characteristics of the polarized light emitting elements of the polarized light emitting plates obtained in Examples 1 to 7 and Comparative Example 1 at the emission wavelengths when emitting light and when not emitting light. Since the comparative example 2 had the same performance as the comparative example 1, the description thereof was omitted. The emission intensity (emission brightness) indicates the emission intensity when the emission intensity of Comparative Example 1 is 1.00. For example, since Example 1 has 1.76, it means that the emission intensity is 1.76 times. In Table 4,-(hyphen) indicates that polarization was not observed due to no light transmission or light reflection.

  Comparative Example 1 had the performance of a polarized light emitting element, the emitted light thereof was also linearly polarized light, and had a high transmittance of 91.22% when not emitting light. On the other hand, the reflection was 0% (equivalent to the triacetyl cellulose film). On the other hand, in Example 1, the emission brightness on the polarized light emitting element side was improved. In Example 7, the emission luminance on the polarization light emitting element side was further improved as compared with Example 1 by using the ¼λ retardation plate at the absorption wavelength of the polarization light emitting element in Example 1. In the second embodiment, not only the emission brightness is improved, but also polarized light emission on the reflective medium side appears, so that light emission can be provided to the back surface. In Example 3, not only the light emission intensity on the side of the polarized light emitting element was improved, but also the light transmission and reflected light had a polarization function even when no light was emitted. Example 4 can provide polarized light to the reflective medium side as well, although the emission brightness improvement is 4%. In each of Example 5 and Example 6, the emission brightness toward the polarized light emitting element side and the reflection medium side was improved by 14% or more, and the light transmittance in the non-emission state was 90% or more. . In addition, in Examples 5 and 6, although the light transmitted to the reflection medium side had circular polarization, linearly polarized light was emitted at the wavelength based on the light emission of the polarized light emitting element, and non-polarized light was not emitted. It was found that the light of was transmitted. From the above results, the present invention is a polarized light emitting plate capable of improving the light emission brightness of the polarized light emitting element, and at the same time, providing the optical characteristics of the absorption wavelength and the different polarization states when emitting light and not emitting light. I understand.

  Further, using the polarized light emitting plate obtained in Example 3, the polarizing plates on both sides which were attached to the liquid crystal cell of the liquid crystal display (Daiso Digital Watch Tee Blue Clock DO11 Watch A No. 7) were peeled off, A display device having a structure of a polarizing plate (SKN-18043 manufactured by Polatechno Co., Ltd.) / Adhesive / liquid crystal cell / adhesive / polarized light emitting plate was prepared. Then, ultraviolet rays were irradiated from the polarizing plate side with an ultraviolet LED 375 nm hand light type black light (“PW-UV943H-04” manufactured by Nichia Corporation). The polarizing plate is laminated so that its absorption axis is coaxial with the polarizing plate laminated on the liquid crystal cell, and the polarizing plate initially laminated on the facing surface of the liquid crystal cell. The transmission axis and the emission axis of the polarized light emitting plate of the present application were attached so as to be the same axis. When the visibility of the obtained display device was confirmed, it was found that a display device having apparently high brightness was obtained. Further, when a display device was produced in the same manner using the polarized light emitting plate obtained in Example 5, it was found that in Example 5 as well, a display device having high brightness was obtained.

  From the above, the polarized light emitting plate of the present application can provide polarized light having a high emission wavelength when used in an optical device such as a polarized light source or a display device, particularly in a liquid crystal display device. Further, since a film having different optical characteristics in ultraviolet, visible, and luminescent / non-luminescent states can be obtained, the present invention can provide various characteristics such as security and design.

Claims (11)

  In an element capable of emitting polarized light by utilizing absorption of light, the wavelength of light absorbed by the element is different from the wavelength of light emitted in polarized light, and light polarized in a wavelength range of at least 400 to 700 nm is used. A polarized light emitting plate comprising: a polarized light emitting element that emits light; and a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element.   In the polarized light emitting device, the wavelength range of light absorbed for use in polarized light emission has a range from near ultraviolet to near ultraviolet visible region, and by a layer capable of reflecting light in the absorption wavelength range of the polarized light emitting device. The polarized light emitting plate according to claim 1, wherein the reflected light is a layer capable of reflecting light in the near-ultraviolet region, the near-ultraviolet visible region, or the near-ultraviolet to near-ultraviolet visible region.   The polarized light emitting plate according to claim 1 or 2, wherein the layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element is a layer capable of reflecting polarized light.   The layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element is a multilayer film laminated structure containing two kinds of substances having different refractive indexes, and is a layer capable of dividing polarized light into a plurality of pieces. 4. The polarized light emitting plate according to any one of 3 to 3.   The polarized light emitting plate according to claim 1, wherein the layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element is a cholesteric liquid crystal layer having a fixed helical alignment.   The polarized light emitting plate according to any one of claims 1 to 5, wherein the polarized light emitting element is an element that emits linearly polarized light.   The polarized light emitting plate according to any one of claims 1 to 6, wherein the layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element has a light reflectance of 30 to 100%.   The polarized light emitting plate according to any one of claims 1 to 7, wherein the layer capable of reflecting light in the absorption wavelength range of the polarized light emitting element has a light transmittance in the visible region of 30 to 100%.   An optical film in which the polarized light emitting plate according to any one of claims 1 to 8 and a retardation plate are laminated.   The polarized light emitting plate according to any one of claims 1 to 8, or the optical film according to claim 9, wherein when the light absorbed by the polarized light emitting element is incident, the polarized light emitting element and the absorption wavelength of the polarized light emitting element. An optical device comprising: a layer capable of reflecting light in the range, and light which can be absorbed by a polarized light emitting element, incident from the side of the polarized light emitting element.   The optical device according to claim 10, which has a liquid crystal display function.