JP2019056904A - Plane polarized light emitting element - Google Patents

Abstract

To provide a transparent plane polarized light emitting element capable of emitting light, in which the light is emitted toward one plane direction and which has a polarization function.SOLUTION: The plane polarized light emitting element is an element which includes elements (polarized light emission element) which emits polarized light in the visible range by applying light in the ultraviolet to near-ultraviolet visible regions, and a polarizing plate which works with light in the visible range. The plane polarized light emitting element emits light toward one plane in the planes of the element.SELECTED DRAWING: None

Description

  The present invention relates to a planar polarized light-emitting element that irradiates light in one surface direction while being a flat film.

  A polarizing plate having a light transmitting / shielding function is a basic component of a display device such as a liquid crystal display (LCD) together with a liquid crystal having a light switching function. Applications of this LCD include small devices such as calculators and watches in the early days, notebook computers, word processors, liquid crystal projectors, liquid crystal televisions, car navigation, indoor / outdoor information display devices, measuring devices, and the like. In addition, such a polarizing plate can be applied to a lens having a polarizing function, and has been applied to sunglasses with improved visibility, recently polarized glasses for 3D televisions, etc. It is also being applied and put into practical use for familiar information terminals such as wearable terminals. Among them, the reflective liquid crystal display (reflective LCD) is a liquid crystal display device that does not have a backlight and displays using ambient light. Front lights are being developed. However, the conventional front light uses visible light, and the light is illuminated on the viewer side, so the front light shines brightly. There are spots in the brightness between the strong part and the weak part, resulting in a problem of low display quality.

  Generally, a polarizing element constituting a polarizing plate is a stretched and oriented polyvinyl alcohol film or a derivative film thereof, or a polyene system in which polyene is generated by dehydrochlorination of a polyvinyl chloride film or dehydration of a polyvinyl alcohol film and oriented. It is manufactured by dyeing or containing iodine or a dichroic dye as a polarizing element on a base material such as a film. Since such a conventional polarizing plate composed of a polarizing film uses a dichroic dye having a light absorbing action in the visible light region, the transmittance in the visible light region is lowered. For example, the transmittance of a commercially available general polarizing plate is 35 to 45%. In particular, a liquid crystal display generally uses two polarizing plates having a transmittance of 35 to 45%, so that the parallel transmittance is substantially about 30% when the two polarizing plates are used. . For this reason, display is performed using a backlight, but the liquid crystal display has become a liquid crystal display that is only about 30% of the actual backlight brightness due to the polarizing plate. In particular, in a reflection type liquid crystal display, the method of using two polarizing plates through a liquid crystal cell has a decrease in brightness when passing through the polarizing plate. Therefore, display quality improvement using a front light has been demanded.

JP 2003-5177 A JP 2008-26889 A JP 2012-226337 A

  The light emitting light that has been applied to the front light emits light toward both the front and back surfaces of the light. As a result, when light is emitted to the liquid crystal display side, light is also emitted to the viewer side, which is the opposite side of the liquid crystal display side, so that the liquid crystal display can be irradiated with light, but the contrast is lowered. I was sorry. In addition, a general fluorescent light emitting sheet has a light function and is a film, but is not transparent. Therefore, when it is used as a screen front light for a reflective liquid crystal, the display disappears and is used. I could not do it.

  The present invention can emit light while having transparency, and the emitted light is emitted toward one surface direction, or strongly emitted in one surface direction, and the emission is significantly reduced on the other surface. An object of the present invention is to provide a planar polarization light-emitting element that provides a state in which the light is emitted and whose light emission has a polarization function.

  As a result of diligent research to achieve such an object, the present inventors, as a result of irradiating light in the ultraviolet light region to the near ultraviolet visible light region, polarized light emission in the visible light region (polarized light emitting device) ) And a polarizing plate having a polarizing function with respect to light in the visible light region, and finds a planar polarized light-emitting element that emits light toward one of the planes of the element. It came to complete.

That is, the present invention relates to 1) to 9).
1)
It is an element that includes an element that emits polarized light by irradiating light in the ultraviolet light region to the near ultraviolet visible light region (polarized light emitting device) and a polarizing plate that functions with light in the visible light region. A planar polarization light-emitting element that emits light toward one of the surfaces of the element.
2)
The planar polarized light-emitting device according to 1), wherein the light transmittance in the visible light region is 30 to 90%.
3)
The planar polarized light-emitting device according to 2), wherein the polarizing plates are laminated.
4)
3. The planar polarized light-emitting element according to 3), wherein the light absorption axis of the planar polarized light-emitting element and the light absorption axis of the polarizing plate are laminated with different axes.
5)
The polarization emission axis of the polarization light-emitting element and the absorption axis of the polarizing plate are arranged at an angle of 90 °, the phase difference value is 1 / 2λ with respect to the wavelength in the visible light region, and 35 to 55 °. The planar polarized light-emitting device according to 4), which is disposed so as to have an angle of
6)
A retardation plate is provided between the planar polarized light emitting element and the polarizing plate, and the retardation plate has a retardation value in the ultraviolet light region to a near ultraviolet visible light region and a position of 450 to 700 nm in the visible light region. The planar polarized light-emitting device according to 5), which has different phase difference values.
7)
The planar polarized light-emitting device according to any one of 3) to 6), wherein the light transmittance in the ultraviolet region of the polarizing plate is 20 to 90%.
8)
The planar polarized light-emitting device according to any one of 1) to 7), wherein a polarizing plate provided on the planar polarized light-emitting device is provided on an observer side.
9)
The display device according to 8), which is a liquid crystal display device.

  An element that emits polarized light in the visible light region (polarized light emitting device) by irradiating light in the ultraviolet light region to the near ultraviolet visible light region, which is light that cannot be perceived by the human eye, or visible light, and visible light A planar polarization light-emitting element including a composite element including a polarizing plate having a polarization function with respect to light in a region is an element that emits light in one surface direction among the surfaces of the planar polarization light-emitting element. Or a planar polarization light emitting device that emits intense light in one surface direction and provides a state in which light emission is significantly reduced on the other surface. Further, since the planar polarized light-emitting element is highly transparent, even if it is provided on the front surface of the display device, particularly on the front surface of the reflective liquid crystal display device, the display quality such as contrast is not deteriorated, but rather the luminance is improved. Display quality can be improved.

  The present application relates to an element (polarized light emitting element) that polarizes and emits light in the visible light region by irradiating light in the ultraviolet light region to the near ultraviolet visible light region, and polarized light that has a polarization function for light in the visible light region. The present invention relates to a planar polarized light-emitting element including a composite element including a plate.

  By irradiating light in the above ultraviolet light region to near ultraviolet visible light region, an element that emits polarized light in the visible light region (polarized light emitting element) is, for example, light having a wavelength shorter than 430 nm in the light wavelength region. , An element that absorbs light in a range from the ultraviolet light region to the near ultraviolet visible light region and emits polarized light having an emission spectrum peak in a part or all of the visible light region in the range of 380 nm to 780 nm, It contains at least one substrate and one or more polarized luminescent dyes described later. As the light in the ultraviolet light region to the near ultraviolet visible light region, light having a wavelength of 300 to 430 nm can be preferably used, but invisible light or light having a wavelength with extremely low eye sensitivity is preferably used. Therefore, it is more preferable to use light having a wavelength of 340 to 415 nm, more preferably 350 to 400 nm, and particularly preferably 350 to 390 nm.

<Base material>
The polarized light-emitting element uses, as a base material, a polymer film for adsorbing and orienting a polarized light-emitting dye described later. The polymer film preferably has a hydrophilic property obtained by forming a hydrophilic polymer capable of adsorbing a polarized luminescent dye having general dichroism, 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 resin and a starch resin are preferable. From the viewpoint of the dyeability, processability, and crosslinkability of the polarized luminescent dye having the above dichroism, a polyvinyl alcohol resin is preferable. Resins and derivatives thereof are preferred. Examples of the polyvinyl alcohol resin and derivatives thereof include, for example, polyvinyl alcohol or derivatives thereof, and olefins such as ethylene and propylene, non-polymers such as crotonic acid, acrylic acid, methacrylic acid, and maleic acid. Examples thereof include those modified with saturated carboxylic acid and the like. Especially, the film which consists of polyvinyl alcohol or its derivative (s) is used suitably from the point of the adsorptivity and orientation of the polarized luminescent pigment | dye which has dichroism. For example, a film made of a commercially available polyvinyl alcohol resin or a derivative thereof may be used as the substrate, or the substrate may be produced by forming a polyvinyl alcohol resin. The method for forming a polyvinyl alcohol-based resin is not particularly limited. For example, a method of melt-extruding hydrous polyvinyl alcohol, a casting film forming method, a wet film forming method, a gel film forming method (cooling a polyvinyl alcohol aqueous solution once After gelling, a known film forming method such as a method of extracting and removing the solvent), a cast film forming method (flowing a polyvinyl alcohol aqueous solution on the substrate and drying), and a combination thereof can be employed. The thickness of a base material is 10-100 micrometers normally, Preferably it is about 20-80 micrometers.

<Method for producing polarized light-emitting element>
The method for producing the polarized light-emitting element is not limited to the following production method, but it is preferable to use a film mainly composed of polyvinyl alcohol or a derivative thereof. A method for manufacturing a polarized light emitting element will be described by taking as an example the case of using a film made of polyvinyl alcohol or a derivative thereof.
The method for producing the polarized light-emitting element includes a step of preparing a substrate, a swelling step of immersing the substrate in a swelling liquid to swell the substrate, and swollen the substrate with one or more types of the polarized luminescent dye. A dyeing step of impregnating a dye solution containing at least a dye, and adsorbing the polarized light-emitting dye on the substrate, and immersing the substrate on which the polarized light-emitting dye is adsorbed in a solution containing boric acid in the substrate A cross-linking step for cross-linking, a stretching step for uniaxially stretching a substrate cross-linked with a polarized luminescent dye in a certain direction and arranging the polarized luminescent dye in a certain direction, and if necessary, the stretched base material with a washing liquid It includes a washing step for washing and / or a drying step for drying the washed substrate.

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

(Dyeing process)
The dyeing process will be described. One or more kinds of polarized light-emitting dyes described later 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 the polarized luminescent dye to the substrate. For example, a method of immersing the substrate in a staining solution containing the polarized luminescent dye, Although the method of apply | coating the dyeing solution containing a polarizing luminescent pigment | dye etc. is mentioned, The method of immersing in the dyeing solution containing a polarizing luminescent pigment | dye is preferable. The concentration of the polarized light-emitting dye in the staining solution is not particularly limited as long as the polarized light-emitting dye is sufficiently adsorbed in the base material. For example, the concentration is 0.0001 to 1% by mass in the staining solution. It is preferable that it is 0.0001-0.5 mass%. The temperature of the dyeing solution in the dyeing step is preferably 5 to 80 ° C, more preferably 20 to 50 ° C, and particularly preferably 40 to 50 ° C. Moreover, the time for immersing the substrate in the dyeing solution can be appropriately adjusted, and is preferably adjusted between 30 seconds and 20 minutes, more preferably between 1 and 10 minutes. The polarized light-emitting dyes contained in the staining solution may be used alone or in combination of two or more. The polarized light-emitting dyes have different emission colors due to differences in the dye structure, etc., and therefore the base material contains one or more of the above-mentioned polarized light-emitting dyes to appropriately adjust the generated emission colors to various colors. be able to. Moreover, the dyeing | staining solution may further contain the 1 or more types of organic dye and / or fluorescent dye as needed.

(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 its structure and emits fluorescence. The polarized light emitting dye can emit polarized light by having a dichroic ratio while having fluorescence emission. In particular, a polarized light-emitting dye having a stilbene skeleton or a biphenyl skeleton is excellent in fluorescence emission characteristics and has characteristics of having a high dichroic ratio by being oriented. These characteristics are attributed to each of the above-mentioned skeletons, and in order to further improve these characteristics, or to adjust various characteristics such as various fastnesses such as absorption wavelength, emission wavelength, light resistance, moisture resistance, ozone gas resistance, solubility, etc. It is possible to introduce further arbitrary substituents into the skeleton. In introducing this substituent, although the degree of polarization can be realized depending on the type and position of the substituent as in the conventional dye-based polarizing plate, the amount of emitted light is remarkably reduced. In order to have a high dichroic ratio, it is important to select the type of substituent and the substitution position. Moreover, the said polarized luminescent pigment | dye may be used individually by 1 type or in combination of 2 or more types.

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

  In the above formula (1), L and M each independently have a nitro group, an amino group that may have a substituent, a carbonylamide group that 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, or a substituent. It represents a good ureido group, an aryl group which may have a substituent, and a carbonyl group which may have a substituent, but are not necessarily limited thereto. The dye having the stilbene skeleton represented by the formula (1) is known to have fluorescence emission and to obtain dichroism by orientation, which is mainly caused by the stilbene skeleton. In addition, an arbitrary substituent may be introduced. However, it is not preferable to have an azo group at the L position and the M position of the stilbene skeleton because fluorescence emission becomes extremely small.

  Examples of the amino group that may have a substituent include an unsubstituted amino group, a methylamino group, an ethylamino group, an n-butylamino group, a tertiary 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, which may have a substituent such as C1-C20 alkylamino group, phenylamino group, diphenyl Substitution of arylamino group, methylcarbonylamino group, ethylcarbonylamino group, n-butyl-carbonylamino group and the like which may have a substituent such as amino group, naphthylamino group, N-phenyl-N-naphthylamino group C1-C20 alkylcarbonylamino group, phenylcarbonylamino group, biphenyl Carbonyl such as arylcarbonylamino group, methylsulfonylamino group, ethylsulfonylamino group, propylsulfonylamino group, n-butyl-sulfonylamino group and the like which may have a substituent such as carbonylamino group and naphthylcarbonylamino group Arylsulfonylamino which may have a substituent such as -20 alkylsulfonylamino group, phenylsulfonylamino group, naphthylsulfonylamino group and the like, and an alkyl having 1 to 20 carbon atoms which may have a substituent A carbonylamino group, an arylcarbonylamino group which may have a substituent, an alkylsulfonylamino group having 1 to 20 carbon atoms, and an arylsulfonylamino group which may have a substituent are preferable. 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 substituent in the group, the arylcarbonylamino group that may have a substituent, the alkylsulfonylamino group having 1 to 20 carbon atoms, and the arylsulfonylamino group that may have a substituent is not particularly limited, Examples thereof include a nitro group, a cyano group, a hydroxyl group, a sulfonic acid group, a phosphoric acid group, a carboxyl group, a carboxyalkyl group, a halogen atom, an alkoxy group, and an aryloxy group.

  Examples of the carboxyalkyl group include a methyl carboxyl group and an ethyl carboxyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group. Examples of the aryloxy group include a phenoxy group and a naphthoxy group.

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

  As a naphthotriazole group which may have the said substituent, a benzotriazole group, a naphthotriazole group, etc. are mentioned, for example.

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

  Examples of the vinyl group that may have a substituent include a vinyl group, a methyl vinyl group, an ethyl vinyl group, a divinyl group, and a pentadiene group.

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

  Examples of the aryl group that may have a substituent include a phenyl group, a naphthyl group, a proposed tracenyl group, and a biphenyl group.

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

  The carbonylamide group which may have the said substituent, the naphthotriazole group which may have a substituent, the C1-C20 alkyl group which may have a substituent, and may have a substituent. 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, or a carbonyl group which may have a substituent Is not particularly limited, and may be the same as the substituent described in the paragraph of the amino group which may have the above-described 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. Use of these dyes is preferable because a polarized light-emitting element that emits brighter white light can be obtained.

  In the above formula (2), the substituent R is a hydrogen atom, a chlorine atom, a bromine atom, 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. The alkoxy group which may have or the amino group which may have a substituent is represented. The alkyl group which may have a substituent may be the same as that described in the section of the alkyl group having 1 to 20 carbon atoms which may have a substituent. The alkoxy group which may have a substituent is preferably a methoxy group, an ethoxy group, or the like. The amino group which may have a substituent may be the same as described above, and is preferably a methylamino group, a dimethylamino group, an ethylamino group, a diethylamino group, or a phenylamino group. The substituent R may be bonded to any carbon of the naphthalene ring in the naphthotriazole ring, but preferably, when the carbon condensed with the triazole ring is the 1-position and 2-position, the 3-position, 5-position Is linked to the 8th or 8th position.

In said formula (2), n is an integer of 0-3, Preferably it is 1 or 2. In the above formula (2), the — (SO ₃ H) group may be bonded to any carbon of the naphthalene ring in the naphthotriazole ring. The substitution position in the naphthalene ring of the — (SO ₃ H) group is n = 1, the 4-position, the 6-position, or the 7-position when the carbon condensed with the triazole ring is the 1-position and the 2-position. It is preferable that when n = 2, the fifth and seventh positions, and the sixth and eighth positions are preferable, and when n = 3, the third, sixth and eighth positions are combined. Is preferred. Moreover, it is particularly preferable that R is a hydrogen atom and n is 1.

  X in the above formula (2) represents a nitro group or an amino group which may have a substituent, and is preferably a nitro group. The amino optionally having substituent (s) may be the same as described above. The alkylcarbonylamino group having 1 to 20 carbon atoms which may have substituent (s), the arylcarbonylamino group optionally having substituent (s), An alkylsulfonylamino group having 1 to 20 carbon atoms or an arylsulfonylamino group which may have a substituent is preferable.

  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. An aryl group that may have a substituent is preferable, a naphthyl group that may have a substituent is more preferable, and a naphthyl group in which an amino group and a sulfo group are substituted as a substituent Is particularly preferred.

  Z in Formula (3) represents the same substituent as explained for X in Formula (2), and is preferably a nitro group.

  As a compound shown by Formula (1), Whiteex series (made by Sumitomo Chemical Co., Ltd.) etc., such as Kayphor series (made by Nippon Kayaku Co., Ltd.) and Whitex RP, etc. are mentioned. Moreover, although the compound shown by Formula (1) below is illustrated, it is not limited to these.

(B) Dye having a biphenyl skeleton The dye having the 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 that may have a substituent, a carbonylamide group that 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, or a substituent. It represents a good ureido group, or an aryl group that may have a substituent, a carbonyl group that may have a substituent, or an amino group that may have a substituent, but is not necessarily limited thereto. However, it is not preferable to have an azo group at the P position and / or Q position of the biphenyl skeleton because fluorescence emission becomes extremely small.

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

In said Formula (5), j shows the integer of 0-2. The preferred substitution position of the (SO ₃ H) — group is not particularly limited, but preferably the 2-position, 4-position, and 6-position, particularly preferably 4-position, when the vinyl group is the 1-position.

In the above formula (5), R ₁ , R ₂ , R ₃ , and R ₄ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an aralkyloxy group, an alkenyloxy A group selected from the group consisting of a group, an alkylsulfonyl group having 1 to 4 carbon atoms, an arylsulfonyl group having 6 to 20 carbon atoms, a carbonamido group, a sulfonamido group, and a carboxyalkyl group. The carboxyalkyl group may be the same as described 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 tertiary butyl group, and a cyclobutyl group.

  As said C1-C4 alkoxy group, a methoxy group, an ethoxy group, a propoxy group, n-butoxy group, a sec-butoxy group, a tertiary riboxy group, a cyclobutoxy group etc. are mentioned, for example.

  Examples of the aralkyloxy group include an aralkyloxy group having 7 to 18 carbon atoms.

  As said alkenyloxy group, a C1-C18 alkenyloxy group etc. are mentioned.

  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 tertiary butylsulfonyl group, and a cyclobutylsulfonyl group. It is 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, 4-position, and 6-position when the vinyl group is at the 1-position, and in particular, has a substituent at the 4-position. It is particularly preferable.

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

  The compound represented by the formula (5) is exemplified by the following compounds described in JP-A-4-226162.

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

In formula (D), Z ₁ to Z ₄ each independently represents 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 propyl, 2-hydroxypropyl, 4-hydroxybutyl, 3-hydroxybutyl, and 2-hydroxy _hydroxy-C 1 -C ₆ alkyl such as butyl, preferably a hydroxy _C 1 -C ₄ alkyl; and hydroxy ethoxymethyl, 2-hydroxy ethoxyethyl, 3-hydroxyethoxypropyl, 3-hydroxyethoxy-butyl, and 2-hydroxy _hydroxy-C 1 -C ₆ alkoxy _C 1 -C ₆ alkyl ethoxy butyl, preferably a hydroxy _C 1 -C ₄ alkoxy _C 1 -C _4- alkyl and the like can be mentioned.

  Among these inorganic cations and organic cations, more preferred are cations such as sodium, potassium, lithium, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, and ammonium. Is mentioned. Among these, lithium ion, ammonium ion, and sodium ion are more preferable.

Other examples of the polarized light-emitting dye that can be used in the polarized light-emitting element include, for example,
C. I. Fluorescent Brighter 5,
C. I. Fluorescent Brighter 8,
C. I. Fluorescent Bright 12,
C. I. Fluorescent Bright 28,
C. I. Fluorescent Brighter 30,
C. I. Fluorescent Brighter 33,
C. I. Fluorescent Bright 350,
C. I. Fluorescent Bright 360,
C. I. Fluorescent Bright 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 that emits polarized light can be obtained by combining and aligning one or more of the polarized light-emitting dyes obtained above. When two or more kinds of polarized light-emitting dyes are used in the polarized light-emitting element, it is possible to adjust the light emission colors by adjusting the blending ratio between the polarized light-emitting dyes. For example, by adjusting the chromaticity a ^* value and the absolute value of the b ^* value to be 5 or less, the polarized light emitted from the polarized light emitting element can be white. The chromaticity a ^* value and b ^* value are obtained according to JIS Z 8781-4: 2013 based on the spectral distribution measured for light emitted from the polarized light emitting element when light is incident on the polarized light emitting element. It is 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 (abbreviated as “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, the 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 measuring the emitted light. The absolute value of a ^* of the emitted light is 5 or less, preferably 4 or less, more preferably 3 or less, still more preferably 2 or less, and particularly preferably 1 or less. The absolute value of b ^* of the emitted light is 5 or less, preferably 4 or less, more preferably 3 or less, still more preferably 2 or less, and particularly preferably 1 or less. If the absolute values of the a ^* value and the b ^* value are independently 5 or less, they can be detected as white by human eyes, and if both are 5 or less, they are detected as more preferable white light emission. I can do it. Since the emitted polarized light is white, it can be used as a natural light source such as sunlight, a light source such as a paper white terminal, etc., and can be easily applied even when placed on a display using a color filter or the like. There is. As for the luminescence intensity, it can be applied to a display as long as it can sense that it is shining. In particular, as a feature of the present application, it is important that the emitted light has a high degree of polarization and that the transmittance in the visible region is high.

(2) Other dyes The polarized light-emitting element includes a stilbene skeleton, a dye having a biphenyl skeleton, or a salt thereof, in addition to a single substance or a plurality of salts thereof, for the purpose of color adjustment and the like within a range not inhibiting the polarized light emission function. If necessary, one or more other organic dyes or other fluorescent dyes may further be included. Although it does not specifically limit as another organic dye, A thing with high dichroism is preferable, and the pigment | dye which has little influence on the polarization performance of the ultraviolet region of a stilbene skeleton or a biphenyl skeleton is preferable. Examples of other organic dyes include C.I. Ai. direct. Yellow 12, sea. Ai. direct. Yellow 28, Sea. Ai. direct. Yellow 44, Sea. Ai. direct. Orange 26, Sea. Ai. direct. Orange 39, sea. Ai. direct. Orange 71, Sea. Ai. direct. Orange 107, sea. Ai. direct. Red 2, sea. Ai. direct. Red 31, sea. Ai. direct. Red 79, Sea. Ai. direct. Red 81, Sea. Ai. direct. Red 247, Sea. Ai. direct. Blue 69, Sea. Ai. direct. Blue 78, Sea. Ai. direct. Green 80 and Sea. Ai. direct. Green 59 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 amine salts.

  When other organic dyes or other fluorescent dyes are used in combination, it is possible to select a dye to be blended and adjust the blending ratio and the like in order to adjust the color of the desired polarized light-emitting element. The blending ratio of the organic dye or fluorescent dye is not particularly limited depending on the purpose of preparation, but generally, the total amount of these other organic dyes or other fluorescent dyes is 100 parts by weight of the polarized light emitting element. It is preferable to use in the range of 0.01 to 10 parts by mass.

  The dyeing solution may further contain a dyeing assistant as necessary in addition to the dyes described above. Examples of the dyeing assistant include sodium carbonate, sodium hydrogen carbonate, sodium chloride, sodium sulfate (sodium salt), anhydrous sodium sulfate, and sodium tripolyphosphate, and sodium sulfate is preferable. The content of the dyeing assistant can be arbitrarily adjusted by the immersion time based on the dyeability of the dye used, the temperature of the dyeing solution, and the like, but may be 0.0001 to 10% by mass in the dyeing solution. Preferably, it is 0.0001-2 mass%.

  In order to remove the dyeing solution adhering to the surface of the base material in the dyeing process after the dyeing process, a preliminary washing process can optionally be performed. By passing through the preliminary washing step, it is possible to suppress migration of the dye remaining on the surface of the base material in the liquid to be processed next. In the preliminary cleaning step, water is generally used as the cleaning liquid. As for the cleaning method, it is preferable to immerse the dyed base material in the cleaning liquid. On the other hand, the cleaning can be performed by applying the cleaning liquid to the base material. The washing time is not particularly limited, but is preferably 1 to 300 seconds, and 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 constituting the substrate does not dissolve, and the cleaning process is generally performed at 5 to 40 ° C. Even if the preliminary cleaning process is not performed, the performance of the polarized light emitting element is not particularly affected, and therefore the preliminary cleaning process can be omitted.

(Crosslinking process)
After the dyeing process or the preliminary washing process, the base material can contain a crosslinking agent. In the method of incorporating a crosslinking agent into the substrate, the substrate is preferably immersed in a treatment solution containing the crosslinking agent, while the treatment solution may be applied or applied to the substrate. As a crosslinking agent in the treatment solution, 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, and more preferably 1 to 6 minutes. When the method for producing a polarized light-emitting device according to the present invention includes this crosslinking step, the obtained polarization device has a high degree of polarization of light emitted and exhibits a high contrast as a display body. This is an excellent action that is totally unexpected from the function of boric acid used in the prior art for the purpose of improving water resistance or light transmission. In the cross-linking step, if necessary, a fix treatment may be further performed with an aqueous solution containing a cationic polymer compound. By this fixing treatment, it is possible to fix the dye in the polarized light emitting device. At this time, as the cationic polymer compound, for example, cation, dicyanamide and formalin polymerization condensate as dicyan, dicyandiamide / diethylenetriamine polycondensate as polyamine, epichlorohydrin / dimethylamine addition polymer as polycation, dimethyl Diallylammonium chloride / dioxide copolymer, diallylamine salt polymer, dimethyldiallylammonium chloride polymer, allylamine salt polymer, dialkylaminoethyl acrylate quaternary salt polymer and the like are used.

(Stretching process)
After passing through the crosslinking step, a stretching step is performed. The stretching step is performed by uniaxially stretching the substrate in a certain direction, and may be either a wet stretching method or a dry stretching method. The draw ratio is preferably 3 times or more, 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 the substrate is immersed 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 processing solution used in the cross-linking step. The stretching temperature is preferably 40 to 70 ° C, and more preferably 45 to 60 ° C. The stretching time is usually 30 seconds to 20 minutes, preferably 2 to 7 minutes. The wet stretching process may be performed by one-stage stretching or may be performed by two-stage or more multi-stage stretching. The stretching treatment may optionally be performed before the dyeing step, and in this case, the dye can be aligned 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 of normal temperature to 180 ° C. The humidity is preferably in an atmosphere of 20 to 95% RH. Examples of the heating method for the substrate include, but are not limited to, an inter-roll zone stretching method, a roll heating stretching method, a hot pressure stretching method, and an infrared heating stretching method. The dry stretching process may be performed by one-stage stretching or may be performed by multistage stretching of two or more stages.

(Washing process)
In the stretching process, since the precipitation of the crosslinking agent or foreign matter may adhere to the surface of the substrate, a cleaning process for cleaning the surface of the substrate can be performed. The washing time is preferably 1 second to 5 minutes. In the cleaning method, it is preferable to immerse the base material in a cleaning liquid. On the other hand, the cleaning liquid can also be cleaned by applying or coating the base material. As the cleaning liquid, water is preferable. The cleaning process may be performed in one stage or may be performed in two or more stages. 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 described above, in addition to the above water, for example, dimethyl sulfoxide, N-methylpyrrolidone, methanol, ethanol, propanol, isopropyl alcohol, glycerin, ethylene glycol, propylene glycol, diethylene glycol And alcohols such as triethylene glycol, tetraethylene glycol or trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. Although the solvent of the said solution or a process liquid is not limited to these, Most preferably, it is water. Moreover, the solvent of these solutions or a process liquid may be used individually by 1 type, and 2 or more types of mixtures may be used for it.

(Drying process)
After the cleaning step, a substrate drying step is performed. Although the drying treatment can be performed by natural drying, in order to further increase the drying efficiency, it can be performed by compression with a roll, removal of moisture on the surface by an air knife or a water absorption roll, etc. It is also possible to do this. It is preferable that the temperature of a drying process is 20-100 degreeC, and it is more preferable that it is 60-100 degreeC. The drying time is preferably 30 seconds to 20 minutes, and more preferably 5 to 10 minutes.

  With the above method, the polarized light-emitting device according to the present invention can be manufactured. The polarized light-emitting element according to the present invention is a polarized light element that exhibits polarized light emission and exhibits polarization in the ultraviolet region, and has high durability because the dichroic dye does not decompose even under high temperature or high humidity environment.

  The polarized light emitting element is irradiated with light in a non-visible light region such as an ultraviolet light region, absorbs light in the ultraviolet light region, and emits polarized light in the visible light region using the energy. Since the light emitted from the polarized light emitting device is polarized light in the visible light region, when the polarized light emitting device is observed through a general polarizing plate having a polarization function for the light in the visible light region, the visible light By changing the angle of the axis of a general polarizing plate having a polarizing function in the region, polarized emitted light and non-emitted light can be visually recognized. The degree of polarization of polarized light emitted from the polarized light emitting element is 70% or more, preferably 80% or more, more preferably 90% or more, still more preferably 95% or more, and particularly preferably 99% or more. The polarized light emitting element transmits light in the visible light region without absorbing it. If the transmittance of light in the visible light region of the polarized light-emitting element is 60% or more in the transmittance corrected for visibility, a liquid crystal display with a clearly dramatic high transmittance can be obtained as compared with a conventional liquid crystal display. However, it is preferably 70% or more, more preferably 80% or more, still more preferably 85% or more, and particularly preferably 90% or more. Since the polarized light-emitting device obtained in the present invention has a high degree of polarization, absorption in the visible light region is reduced in a non-light-emitting state, and a polarized light-emitting device having high transparency is obtained.

[Polarized light-emitting plate]
A polarizing light-emitting plate has a transparent protective layer on at least one surface of the polarizing light-emitting element. The transparent protective layer is used to improve the water resistance and handling properties of the polarized light-emitting element, and the transparent protective layer does not affect the polarization function exhibited by the polarized light-emitting element.

  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 shape of the polarized light-emitting element, and is a plastic film excellent in thermal stability, moisture shielding properties, etc. in addition to transparency and mechanical strength. Preferably there is. As a material for forming such a protective film, for example, a cellulose acetate film, an acrylic film, a fluorine film such as a tetrafluoroethylene / hexafluoropropylene copolymer, a polyester resin, a polyolefin resin, etc. Or the film which consists of polyamide-type resin, etc. are mentioned, A triacetyl cellulose (TAC) film and a cycloolefin type film are used preferably. The thickness of the transparent protective layer is preferably 1 μm to 200 μm, more preferably 10 μm to 150 μm, and particularly preferably 40 μm to 100 μm. The method for producing the polarizing plate is not particularly limited, but for example, the polarizing plate can be produced by laminating a transparent protective layer on a polarized light emitting element and laminating with a known formulation.

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

  The polarized light-emitting plate may appropriately include various known functional layers such as an antireflection layer, an antiglare layer, and a further transparent protective layer on the exposed surface of the transparent protective layer. When producing such a layer having various functionalities, a method of applying a material having various functionalities to 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 bond to the exposed surface of the transparent protective layer.

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

  The polarizing light emitting element, further a polarizing light emitting element, or a polarizing light emitting plate, a polarizing plate that is an element that absorbs uniaxial light of visible light and forms a polarizing function when light is captured as a wave, a so-called general polarizing plate. The planar polarized light-emitting element of the present application can be obtained by combining a polarizing plate or the like.

(Polarizer)
The polarizing plate having polarization performance with respect to light in the visible range is not particularly limited as long as it is a polarizing plate capable of controlling polarization at a wavelength in the visible range. The polarizing plate may be an iodine polarizing plate, a dye polarizing plate, a dye polarizing plate that can control only a specific wavelength, a polarizing plate using polyene, a wire grid polarizing plate, and the like. . The polarizing plate has polarization performance with respect to light in the visible range, and the polarization plate has polarization performance with respect to light in part or all of the wavelength range of 400 to 700 nm. Examples of the iodine-based polarizing plate include JP-A-2001-290029 and JP-A-2010-072548, and examples of the dye-based polarizing plate include JP-A-2001-033627 and JP-A-2004-251962, and control polarization of only a specific wavelength. JP-A-2007-084803 and JP-A-2007-238888 are examples of dye-type polarizing plates that can be used, and JP-A-2005-527847 and JP-A-2005-517974 are examples of polarizing plates that use polyene. As a grid type polarizing plate, Special Table 2003-518818, Special Table 2003-502708 are mentioned.

  The light transmittance of the above-mentioned planar polarized light emitting element is equivalent to 35 to 45% in terms of visibility correction transmittance which is the transmittance of a general polarizing plate, but there is no problem, but light is emitted from the polarized light emitting element or the polarized light emitting plate. There is no problem if the polarized light does not pass through its absorption axis. Therefore, it is possible to use a polarizing element having a visibility correction transmittance of 30% to 80% or a polarizing plate thereof. Preferably it is 30 to 65%, more preferably 35 to 55%, still more preferably 40 to 50%.

(Ultraviolet wavelength high transmission type polarizing element / polarizing plate)
As a preferable form of the polarizing plate used for the planar polarized light-emitting element, there is a polarizing element exhibiting high transmittance at a wavelength in the ultraviolet region, that is, an ultraviolet wavelength high transmission polarizing element, or a polarizing plate using the polarizing element. As the polarizing plate, a dye-type polarizing plate using a general azo dye can be preferably used, and since it absorbs light in the ultraviolet region low, it is preferably used in the planar polarized light-emitting device. The ultraviolet wavelength high transmission type polarizing element can be obtained by laminating a triacetyl cellulose film or the like having no ultraviolet absorbing ability on a dye-based polarizing plate. The light transmittance in the ultraviolet light region of the ultraviolet wavelength high transmission polarizing element or the polarizing plate using the same is preferably 20 to 95%, more preferably 35 to 95%, still more preferably. 50 to 95%, particularly preferably 60 to 95% is good.

  A planar polarized light emitting element is obtained by laminating the above polarized light emitting element or a polarizing plate using the polarized light emitting plate and an ultraviolet wavelength high transmission polarizing element. As one form of the planar light-emitting element in the present invention, it is coaxial with the polarizing plate used for the ultraviolet wavelength high transmission type polarizing element with respect to the light emitting axis of the polarized light emitting element or the polarizing light emitting plate (absorption axis for the ultraviolet region). Is arranged. By this method, the polarized light emitted from the polarized light emitting element or the polarized light emitting plate is absorbed by the polarizing plate on one surface, and the planar polarized light emitting device emits light only in one surface direction with respect to the surface.

  Furthermore, as one form of the planar light emitting device in the present invention, a light emitting axis (absorption axis for the ultraviolet region) of the polarized light emitting device or the polarized light emitting plate is provided by providing a medium for controlling the phase in the planar polarized light emitting device. On the other hand, a planar light emitting device in which a polarizing plate using an ultraviolet wavelength high transmission type polarizing element may be arranged on an axis different from the coaxial axis can be produced. As a result, even when ultraviolet light is irradiated from the side of the polarizing plate using the ultraviolet wavelength high transmission type polarizing element, the ultraviolet light is not attenuated on the absorption axis of the polarizing plate, or the polarized light is reduced. Since the light emitting element or the polarized light emitting plate is irradiated with light in the ultraviolet light region to the near ultraviolet visible light region, the light emitting device or the polarizing light emitting plate is further preferable.

(Phase control medium)
Examples of the medium having the phase include a phase difference plate (also referred to as a wave plate and a phase difference film), and a liquid crystal panel (liquid crystal cell) that electrically controls and controls liquid crystal. In particular, as a medium for phase control, a liquid crystal panel (liquid crystal cell) capable of electrically controlling the phase is preferable. Light has particle and wave properties, but when light is expressed as a wave, it means that the phase of the wave can be controlled. When focusing on the polarization performance, for example, the wave plate is an optical functional element that gives a predetermined phase difference to linearly polarized light, and the polarized light is in the other axis (for example, 90 °) with respect to the light of a specific axis. It is possible to provide different phases. That is, by providing a wavelength plate on the optical path for one polarized light, it becomes possible to obtain a polarized light of the opposite axis, or to newly add circularly polarized light, elliptically polarized light, or the like. Therefore, the wave plate is an element that can change the polarization state of incident light by adding a phase difference between two orthogonal polarization components using an oriented birefringent material (for example, a stretched film). I can say that. As a specific application of this wave plate, for example, when the wavelength of specific light is λ, by setting the slow axis of the retardation plate of λ / 2 to 45 ° with respect to the axis of polarization, The linearly polarized light incident on the wave plate (retardation plate) is rotated by 90 °, and can be emitted as polarized light having a polarization axis in a direction orthogonal to the incident polarization axis (90 °). Note that the angle of the axis can be allowed up to an error of about 10 ° when it is set at 45 ° with respect to the axis of the polarized light of interest, but it is preferably in the range of 40-50 °, more preferably 42-48. It is preferable to arrange in the range of °, particularly preferably in the range of 44 to 46 °. When the slow axis of the λ / 4 retardation plate is set at 45 ° with respect to the polarization axis, the linearly polarized light incident on the wave plate (retardation plate) is emitted as circularly polarized light. Make it possible.

  There are 45 phase difference plates in which the polarization emission axis of the polarization light emitting element or the polarization emission plate and the absorption axis of the polarizing plate are arranged at 90 °, and the retardation value is 1 / 2λ with respect to the wavelength in the visible range. A planar polarized light-emitting element is particularly preferred when arranged at an angle. Light is emitted from the polarized light emitting element or the polarizing light emitting plate by arranging a retardation plate having a retardation value of 1 / 2λ with respect to the wavelength in the visible range at 45 ° with respect to the light emitting axis of the polarized light emitting element or the polarized light emitting plate. The 90 ° axis of the polarized light changes. Thereby, the visible light emitted from the polarized light emitting axis of the polarized light emitting element or the polarized light emitting plate is absorbed by the absorption axis of the polarizing plate by changing by 90 °. Therefore, since polarized light is emitted on one surface, this structure functions as a planar polarized light-emitting element.

  In addition, the phase difference plate may have a constant phase difference depending on each wavelength or may not be constant. When the phase difference is not constant at each wavelength, it is said that there is chromatic dispersion, and wavelength dependency generally called positive dispersion or negative dispersion may occur. A phase difference plate is provided between the polarization light emitting element and the polarizing plate, and the phase difference plate has a phase difference in the ultraviolet light region to a near ultraviolet visible light region and a phase difference of 380 to 780 nm in the visible light region. If they are different, the planar polarized light-emitting element is preferable because light in the visible light region is absorbed by the absorption axis of the polarizing plate while transmitting light in the ultraviolet region even higher. For example, a polarized light emitting element or a polarized light emitting plate is provided with a polarized light emitting axis perpendicular to the absorption axis of the polarizing plate, and a retardation plate having a retardation value of 1 / 2λ with respect to the wavelength in the visible light region is polarized light emitted between them. Visible light emitted from the polarized light emitting axis when it is disposed at 45 ° with respect to the light emitting axis of the element or the polarized light emitting plate and irradiated with light from the ultraviolet light region to the near ultraviolet visible light region from the polarized light emitting device or the polarized light emitting plate side. In the side where the polarizing plate is provided, when the polarization is changed by 90 ° by the phase difference plate, the polarized light is absorbed by the absorption axis of the polarizing plate and light is not absorbed from the other surface but emits polarized light. Therefore, since visible light polarized on one surface is emitted, this structure functions as a planar polarization light-emitting element. On the other hand, even if the irradiated light in the ultraviolet region becomes linearly polarized light after passing through the polarizing plate, the polarizing plate and the polarized light-emitting element are provided orthogonally, and the linearly polarized light is the retardation plate and its retardation plate. Loss of transmitted ultraviolet light because the polarized light emitting element or polarized light emitting plate is irradiated while being converted into polarized light (circularly polarized light, elliptically polarized light, or linearly polarized light of a different axis) that is different from light in the visible light region due to wavelength dispersion. The polarized light-emitting element or the polarized light-emitting plate is irradiated with a small amount of light. From this, the light in the ultraviolet region is efficiently irradiated to the polarized light emitting element or the polarizing light emitting plate, and the light in the visible light region emitted from the polarized light emitting element or the polarized light emitting plate passes through the polarizing plate while enhancing the light emission luminance. Since it does not come out from one side, it functions suitably as a planar polarized light emitting element having high luminance.

  Further, by providing a polarized light-emitting element or a polarized light-emitting plate with a depolarization film, for example, a phase difference plate that generates random polarized light due to a high phase difference, light in the polarized visible light region emitted from the polarized light-emitting element has no polarization. It can be changed to light in the visible light region. For example, a phase difference plate in which the polarization emission axis of a polarization light emitting element or a polarization emission plate and the absorption axis of a polarizing plate are arranged at 90 °, and the retardation value is 1 / 2λ with respect to the wavelength in the visible light region between them. Is disposed at 45 °, and when a depolarizing film is spread on the polarized light emitting element or the polarized light emitting plate surface, the planar polarized light emitting element does not emit light from one side, but from the opposite side. Unpolarized visible light can be emitted. Therefore, this structure can also be mentioned as one preferable structure. In recent years, a depolarizing film is also sold, and for example, “Toyobo SRF” can be suitably used. The transmittance of the depolarizing film is preferably 50 to 99%, preferably 70 to 99%, and more preferably 80 to 99%.

  A display device provided with the above planar polarized light emitting element, wherein the polarizing plate using the ultraviolet wavelength high transmission type polarizing element included in the planar polarized light emitting element is provided on the viewer side or display Symmetric objects emit light in the visible light region by light irradiation in the ultraviolet light region where the planar polarized light-emitting element is not visible in the visible light region, so that the display object is not irradiated with light that is visible in the viewer direction. It is preferable because it can be a display device or a display symmetrical object that can be irradiated. In particular, when the display device is a reflection type liquid crystal display device, the planar polarized light emitting element is preferably a front light because it irradiates the reflection type liquid crystal display device with visible light but does not irradiate light toward the viewer. Function as. In particular, for reflective liquid crystal display devices, display is conventionally performed using a general polarizing plate, and since the polarizing plate has a visible transmittance of 35 to 45%, the display brightness is lowered and the display quality is lowered. However, since the above-mentioned planar polarized light emitting element emits polarized light, the transmittance is reduced, which is a problem of the conventional polarizing plate, and the brightness is increased. Can function as.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, these are illustrations and do not limit this invention at all. Further, “%” and “part” described below are based on mass unless otherwise specified. In addition, in each structural formula of the compound used by each Example and the comparative example, acidic functional groups, such as a sulfo group, were described with the form of the free acid.

(Synthesis Example 1)
Commercially available 35.2 parts of 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 using 35% hydrochloric acid. To the obtained solution, 10.9 parts of 40% aqueous sodium nitrite solution was added and stirred at 10 ° C. for 1 hour. Then, 17.2 parts of 6-aminonaphthalene-2-sulfonic acid was added, and 15% aqueous sodium carbonate solution was added. The mixture was stirred at pH 4.0 for 4 hours. 60 parts of sodium chloride was added to the obtained reaction solution, and the precipitated solid was separated by filtration and further washed with 100 parts of acetone to obtain 124.0 parts of a wet cake of the compound of formula (6) as an intermediate. .

  62.3 parts of the obtained intermediate of formula (6) was added to 300 parts of water and stirred, and the pH was adjusted to 10.0 using a 25% aqueous sodium hydroxide solution. To the obtained solution, 20 parts of 28% aqueous ammonia and 9.0 parts of copper sulfate pentahydrate were added and stirred at 90 ° C. for 2 hours. 25 parts of sodium chloride was added to the resulting reaction solution, and the precipitated solid was separated by filtration and further washed with 100 parts of acetone to obtain 40.0 parts of a wet cake of the compound of formula (7). The wet cake was dried with a hot air dryer at 80 ° C. to obtain 20.0 parts of a compound of formula (7) (λmax: 376 nm).

(Preparation of polarized light emitting device)
A 75 μm-thick polyvinyl alcohol film (VF-PS # 2400 manufactured by Kuraray Co., Ltd.) was immersed in warm water at 40 ° C. for 3 minutes to swell the film. In the synthesis example 1, 1.0 part by weight of the 4,4′-bis- (sulfostyryl) biphenyl disodium aqueous solution (BASF Tinopal NFW Liquid) described in Compound Example 5-1 was used as the film obtained by swelling. The obtained compound (7) was immersed for 4 minutes in a 45 ° C. aqueous solution containing 0.3 parts by weight, 1.0 part by weight of sodium sulfate, and 1500 parts by weight of water. The obtained film was stretched 5 times at 50 ° C. in a 3% boric acid aqueous solution for 5 minutes. The film obtained by stretching was washed with water at room temperature for 20 seconds while maintaining a tension state, and dried to obtain a polarized light emitting device.

(Preparation of polarized light emitting plate using polarized light emitting element)
A triacetylcellulose film containing no UV absorber (ZRD-60 manufactured by Fuji Film Co., Ltd.) was treated with 1.5N aqueous sodium hydroxide solution at 35 ° C. for 10 minutes, washed with water, and then dried at 70 ° C. for 10 minutes. I let you. The triacetyl cellulose film obtained by alkali treatment was laminated via an aqueous solution containing 4% polyvinyl alcohol resin (NH-26, manufactured by Nippon Vinegar Bipovar Co.) on both sides of the polarized light emitting device obtained above, and 70 ° C. And dried for 10 minutes to obtain a polarized light-emitting plate. When this polarized light emitting plate was irradiated with ultraviolet rays, white light was emitted, and when the emitted light was further confirmed through a polarizing plate, it was confirmed that white polarized light was emitted.

(Polarizer)
The display of this application was produced using SKN-18243P by Polatechno as a general polarizing plate. A general polarizing plate is a polarizing plate product having a high polarizing function in the visible region and a remarkably low transmittance of light in the ultraviolet region.

(Preparation of UV-transmission polarizing element)
A 75 μm-thick polyvinyl alcohol film (VF-PS # 2400 manufactured by Kuraray Co., Ltd.) was immersed in warm water at 40 ° C. for 3 minutes to swell the film. The film obtained by swelling is referred to as C.I. I. Direct Orange 39 (0.3 parts), C.I. 0.1 part of I.Direct Red 81, C.I. I. Direct Blue 69 was immersed for 4 minutes in an aqueous solution at 45 ° C. containing 0.3 part, 1.0 part of mirabilite, and 1500 parts of water. The obtained film was immersed in a 3% boric acid aqueous solution at 50 ° C. for 5 minutes and stretched 5 times. The film obtained by stretching was washed with water at room temperature for 20 seconds while keeping the tension state, and dried to obtain an ultraviolet region high transmission type polarizing element.

(Preparation of UV transmission plate)
A triacetylcellulose film containing no UV absorber (ZRD-60 manufactured by Fuji Film Co., Ltd.) was treated with 1.5N aqueous sodium hydroxide solution at 35 ° C. for 10 minutes, washed with water, and then dried at 70 ° C. for 10 minutes. I let you. The triacetyl cellulose film obtained by alkali treatment is laminated via an aqueous solution containing 4% polyvinyl alcohol resin (NH-26, manufactured by Nippon Vinegar Bipovar Co.) on both sides of the ultraviolet region high transmission polarizing element obtained above. And it was made to dry at 70 degreeC for 10 minute (s), and the polarizing plate was obtained. Hereinafter, this polarizing plate is referred to as an ultraviolet region high transmission polarizing plate.

  Each obtained polarizing plate was evaluated as follows.

[Evaluation]
(A) Single transmittance Ts, parallel transmittance Tp, and orthogonal transmittance Tc
The single transmittance Ts, parallel transmittance Tp, and orthogonal transmittance Tc of each measurement sample were measured using a spectrophotometer ("U-4100" manufactured by Hitachi, Ltd.). Here, the single transmittance Ts is a transmittance of each wavelength when a single measurement sample is measured. The parallel transmittance Tp is a spectral transmittance of each wavelength measured by superimposing two measurement samples so that their absorption axis directions are parallel to each other. The orthogonal transmittance Tc is a spectral transmittance measured by overlapping two polarizing plates so that their absorption axes are orthogonal. Measurements were made over a wavelength of 220-780 nm.

(B) Polarization degree ρ
The degree of polarization ρ of each measurement sample was determined by substituting the parallel transmittance Tp and the orthogonal transmittance Tc into the following formula (I).

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

(C) Single transmittance Ys corrected to visibility
The single transmittance Ys of each measurement sample is a visual sensitivity according to JIS Z 8722: 2009 for the single transmittance Ts obtained every predetermined wavelength interval dλ (here, 5 nm) in the wavelength region of 400 to 700 nm in the visible range. The corrected transmittance. Specifically, the single transmittance Ts was calculated by substituting into the formula (V). In the following formula (V), Pλ represents the spectral distribution of the standard light (C light source), and yλ represents the color matching function of the double field of view.

(Formula 2)

  375 nm single transmittance (Ts 375) and 375 nm polarization degree (ρ 375), transmittance corrected to visibility (Ys) in each of the obtained polarizing light-emitting plate, ultraviolet region light transmission type polarizing plate and polarizing plate, Table 1 shows the degree of polarization (ρy) corrected to the visibility. The polarizing function of the polarizing plate in the ultraviolet region and the visible region in each obtained polarizing plate can be understood.

(D) 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) is used, and an ultraviolet transmission / visible cut filter (5 bells) is used as the light source. Seiko Glass Co., Ltd. “IUV-340”) was installed to cut visible light. In addition, a polarizing plate having a polarization function with respect to light in the visible light region and ultraviolet light region ("SKN-18043P" manufactured by Polatechno Co., Ltd., thickness 180 μm, Ys is 43%), and each measurement obtained above. The sample was placed, and the polarized luminescence emitted from the measurement sample was measured with a spectral irradiance meter (“USR-40” manufactured by USHIO INC.). That is, the light from the light source was measured so as to pass through the UV transmissive / visible cut filter, the polarizing plate having polarized light in the visible range and in the UV, and the measurement sample in this order and enter the spectral irradiance meter. . At that time, the spectral emission amount of each wavelength measured by superimposing the absorption axis where the absorption of the ultraviolet ray of the measurement sample is maximum and the absorption axis direction of the ultraviolet / visible polarizing plate are parallel to each other is expressed as Lw (weak emission axis). ), Measurement is performed with the absorption axis where the absorption of the ultraviolet ray of the measurement sample is maximized and the absorption axis direction of the polarizing plate ("SKN-18043P" manufactured by Polatechno Co., Ltd.) having polarized light in the visible region and the ultraviolet ray being orthogonal to each other. Lw and Ls were measured using the spectral emission amount of each wavelength as Ls (strong emission axis). Light emission polarized in the visible range of 400 nm to 700 nm by confirming the energy amount of the light emitted in the visible range between the case where the absorption axis of the measurement sample and a general polarizing plate is parallel and the case where the absorption axis is orthogonal The light was evaluated.

  Table 2 shows the Ls value and the Lw value at each wavelength of 460 nm, 550 nm, 610 nm, and 670 nm of each polarizing plate obtained.

As shown in Table 2, the polarized light-emitting plate emits light strongly by irradiating with ultraviolet rays, because the Lw value and Ls value significantly higher than those in the ultraviolet region high transmission polarizing plate and the polarizing plate are detected. It can be seen that the emitted light has polarized light. In addition, it can be seen that the difference between the Lw value and the Ls value is more remarkable at each wavelength, and the contrast is good. Further, the chromaticity a ^* value and b ^* value at the time of Ls of the polarized light-emitting plate obtained from JIS Z 8781-4: 2013 were a ^* value of 0.68 and b ^* value of −1.2. . From this, it can be seen that the polarized light emitting plate emits white light.

Example 1
The UV wavelength high transmission type polarizing plate and the polarizing light emitting plate are combined with Nippon Kayaku Co., Ltd. adhesive "PTR-104", and the absorption axis of the UV wavelength high transmission type polarizing plate and the light emitting axis of the polarizing light emitting plate are coaxial. Thus, a planar polarized light-emitting element was obtained. As a result of irradiating the obtained planar polarized light-emitting element with ultraviolet light using an ultraviolet LED 375 nm hand light type black light (“PW-UV943H-04” manufactured by Nichia Corporation), an ultraviolet wavelength highly transmissive polarizing plate Light emission was not confirmed from the side of the surface where the material was bonded, and light emission was confirmed only on the polarizing light-emitting plate side. The light emission was polarized light emission.

(Example 2)
A general polarizing plate and a polarizing light-emitting plate were laminated and bonded together using an adhesive “PTR-104” manufactured by Nippon Kayaku Co., Ltd. Furthermore, a planar light-emitting device was obtained by laminating a light guide plate on the side of the polarized light-emitting plate. As a result of irradiating ultraviolet light with ultraviolet LED 375nm hand light type black light ("PW-UV943H-04" manufactured by Nichia Corporation) from the end of the light guide plate, light is emitted from the surface on the general polarizing plate side Was not confirmed, and light emission was confirmed from the polarized light emitting plate. Further, the light emission obtained from the polarizing light-emitting plate had polarized light.

(Example 3)
An ultraviolet wavelength high transmission type polarizing plate and a 270 nm retardation plate as a retardation plate having a phase difference of ½λ with respect to a wavelength of 540 nm are bonded so that the slow axis is 45 °, and further polarized The light-emitting plate is laminated using an adhesive “PTR-104” manufactured by Nippon Kayaku Co., Ltd. so that the absorption axis of the UV wavelength high transmission type polarizing plate and the light-emitting axis of the polarizing light-emitting plate are orthogonal to each other. An element was obtained. As a result of irradiating ultraviolet light with ultraviolet LED 375nm handlight type black light ("PW-UV943H-04" manufactured by Nichia Corporation), no light emission can be confirmed from the surface of the ultraviolet wavelength high transmission type polarizing plate side. The luminescence was confirmed from the polarized light emitting plate. Further, the light emission obtained from the polarizing light-emitting plate had polarized light. Even when the light was irradiated from the ultraviolet wavelength high transmission type polarizing plate, the obtained light emission luminance was higher than that of the planar polarized light emitting device of Example 1. The obtained planar polarized light-emitting element is provided on the front surface of a reflective LCD (Daiso Japan Digital Table Clock D011 (Watch A No. 7)), and an ultraviolet LED 375 nm hand light type black light (manufactured by Nichia Corporation) When PW-UV943H-04 ") was irradiated with ultraviolet light, the luminance was high and the visibility was improved.

Example 4
A polarizing light emitting plate obtained by laminating an ultraviolet wavelength high transmission type polarizing plate and a phase difference plate of 270 nm as a phase difference plate having a phase difference of 1 / 2λ with respect to a wavelength of 540 nm so that the slow axis is 45 °. Is laminated using an adhesive “PTR-104” manufactured by Nippon Kayaku Co., Ltd. so that the absorption axis of the UV wavelength high transmission polarizing plate and the emission axis of the polarizing light emitting plate are orthogonal to each other. Obtained. Furthermore, a depolarizing film (SRF manufactured by Toyobo Co., Ltd.) was bonded to the polarizing light emitting plate side to obtain a planar light emitting film. As a result of irradiating ultraviolet light with ultraviolet LED 375nm handlight type black light ("PW-UV943H-04" manufactured by Nichia Corporation), no light emission can be confirmed from the ultraviolet wavelength high transmission type polarizing plate side. It was confirmed that light was emitted from the light emitting plate, and the light irradiated from the depolarizing film did not have polarized light. Even when the light was irradiated from the ultraviolet wavelength high transmission type polarizing plate, the obtained light emission luminance was higher than that of the planar polarized light emitting device of Example 1. The obtained planar polarized light-emitting element is provided on the front surface of a reflective LCD (Daiso Japan Digital Table Clock D011 (Watch A No. 7)), and an ultraviolet LED 375 nm hand light type black light (manufactured by Nichia Corporation) When PW-UV943H-04 ") was irradiated with ultraviolet light, the luminance was higher than that in the case of not providing it, and the visibility was improved.

(Comparative Example 1)
In Example 1, ultraviolet light irradiation was performed without using an ultraviolet wavelength high transmission type polarizing plate. As a result, both sides of the polarized light-emitting plate emit strong light on both sides as well as the side of the surface not using the ultraviolet wavelength high transmission type polarizing plate in Example 1, so that strong polarized light is emitted from both sides. I confirmed.

(Comparative Example 2)
In Example 1, ultraviolet light irradiation was performed using a visible neutral density filter (ND-1.0 manufactured by Fuji Film Co., Ltd.) instead of the ultraviolet wavelength high transmission type polarizing plate. As a result, the amount of light emitted from one surface was reduced, and the amount of visible polarized light emitted from the surface provided with ND-1.0 was recognizable. In addition, when the ND-1.0 was used, it was also confirmed that the visible transmittance was lowered to 9.6%.

  From the above, the planar polarized light-emitting element of the present application, unlike conventional fluorescent light-emitting films, can emit polarized light and emit light on one side of the surface while having high transparency. I understand. This can be applied not only to an optical display device but also to display on various paper media and the like, and is particularly suitable for a reflective liquid crystal display. Furthermore, since the planar polarized light-emitting element of the present application can emit light by light in the ultraviolet region, it can emit polarized light by invisible light, thereby providing various security and design properties. Applications that take advantage of the advantages are possible.

Claims (9)

  It is an element that includes an element that emits polarized light by irradiating light in the ultraviolet light region to the near ultraviolet visible light region (polarized light emitting device) and a polarizing plate that functions with light in the visible light region. A planar polarization light-emitting element that emits light toward one of the surfaces of the element.   The planar polarized light-emitting element according to claim 1, wherein the light transmittance in the visible light region is 30 to 90%.   The planar polarization light-emitting element according to claim 2, wherein the polarizing plate is laminated.   The planar polarization light-emitting element according to claim 3, wherein the light absorption axis of the planar polarization light-emitting element and the light absorption axis of the polarizing plate are laminated with different axes.   The polarization emission axis of the polarization light-emitting element and the absorption axis of the polarizing plate are arranged at an angle of 90 °, the phase difference value is 1 / 2λ with respect to the wavelength in the visible light region, and 35 to 55 °. The planar polarized light-emitting element according to claim 4, which is arranged to have an angle of 5.   A retardation plate is provided between the planar polarized light emitting element and the polarizing plate, and the retardation plate has a retardation value in the ultraviolet light region to a near ultraviolet visible light region and a position of 450 to 700 nm in the visible light region. The planar polarized light-emitting device according to claim 5, wherein the phase difference values are different.   The planar polarized light-emitting device according to any one of claims 3 to 6, wherein the light transmittance in the ultraviolet region of the polarizing plate is 20 to 90%.   The planar polarized light emitting element according to claim 1, wherein a polarizing plate provided on the planar polarized light emitting element is provided on an observer side.   The display device according to claim 8, which is a liquid crystal display device.