JP2005116284A - Electroluminescent element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a layer-thinning technology of a luminous layer in which vibration and noises that increase accompanied by large area and high luminance of an EL element are improved and which has a particulate phosphor that is required for improving the vibration and noises, and improve manufacturing efficiency by coating a wide and each functional layer in order or by coating simultaneously (multi-layer) on a support body continuously transferred. <P>SOLUTION: This is an electroluminescent element which has at least a pair of electrodes opposed to each other and a luminous layer that is interposed between the pair of electrodes and contains electroluminescent phosphor particles. The electroluminescent element has a buffer material layer and/or a compensation electrode layer provided on the outside of the pair of electrodes through an insulating layer, and the thickness of the luminous layer is in the range 0.5 μm-30 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a dispersion-type EL element having a light-emitting layer in which electroluminescence (EL) phosphor particles are dispersedly applied and a method for producing the same.

  The EL phosphor is a voltage excitation type phosphor, and a dispersion type EL in which a phosphor powder is sandwiched between electrode pairs to form a light emitting element is known. The general shape of a dispersion-type EL phosphor consists of a structure in which phosphor powder is dispersed in a high dielectric constant binder and at least one is sandwiched between two transparent electrodes. Light is emitted by applying an alternating electric field. Light-emitting elements made using EL phosphor powder can have a thickness of several millimeters or less, are surface light emitters, and have many advantages such as low heat generation, so they are used for road signs, various interiors and exteriors. There are uses as light sources for flat panel displays such as liquid crystal displays, illumination light sources for large-area advertisements, and the like.

  The dispersion type does not use a high-temperature process, so that a flexible element using a plastic substrate is possible, it can be manufactured at a low cost by a relatively simple process without using a vacuum device, and It has the feature that the emission color of the element can be easily adjusted by mixing a plurality of phosphor particles having different emission colors, and is applied to backlights and display elements such as LCDs. However, since the light emission luminance and efficiency are low and a high voltage of 100 V or higher is necessary for high luminance light emission, the application range is limited, and further improvement of light emission luminance and light emission efficiency is desired.

  As a means for reducing the light emission luminance and the light emission voltage, a method of increasing the electric field in the phosphor layer by reducing the thickness of the phosphor layer is widely known. However, in general, when the phosphor particles are 20 μm or more, when trying to apply a smooth phosphor layer to suppress the film thickness to 60 μm or less, irregularities are formed, resulting in a decrease in the withstand voltage performance and lifetime of the device, Non-uniform emission occurs. On the other hand, it is well known that the reduction in the size of the particles leads to a decrease in luminance. In particular, in the case of particles having a size of less than 5 μm, the phosphor layer can be made thin, but high luminance and high efficiency are achieved. It is widely known in the industry that they are incompatible.

  As an EL phosphor powder, a powder in which an activator such as copper (metal ion as a light emission center) and a coactivator such as chlorine are added based on zinc sulfide is widely known. However, this light emitting device has the disadvantages of lower emission luminance and shorter light emission lifetime than light emitting devices based on other principles. For this reason, various improvements have been attempted in the past. Was not enough. These EL particles are usually irregular particles having a particle size of 20 μm or more. For example, as disclosed in Japanese Patent Application Laid-Open No. 7-62342 (Patent Document 1), the raw material zinc sulfide particles are mixed with an inorganic salt called flux. There is a method of obtaining zinc sulfide particles for EL having high luminous efficiency by growing particles by performing first firing at a very high temperature of from 1 to 1300 ° C., and subsequently performing second firing at from 500 to 1000 ° C. It was mainstream. This production method is described in, for example, the above-mentioned JP-A-7-62342 and JP-A-6-330035 (Patent Document 2). The conventional firing method cannot adopt a growth mode in which nucleation and growth are separated, and particle convection in the growth crucible cannot be expected. Therefore, it is easily affected by locality of temperature and atmosphere, and the size increases. At the same time, the particle size distribution becomes wider. That is, the particles that grow with growth grow larger, and the smaller particles grow slower and the distribution spreads. As a result, the inter-particle distribution of the light emission characteristics is increased, and it tends to be difficult to obtain high luminance unless a high voltage is applied.

  Further, in the conventional EL device manufacturing method, several methods for forming a light emitting layer containing an EL phosphor and a dielectric layer containing dielectric particles are disclosed, and the most commonly used method is disclosed. There is a screen printing method. However, this method has a problem that productivity is poor because the screen mesh is used and the coating film has uneven film thickness and a plurality of coatings must be applied to obtain the required film thickness. Furthermore, when applying a dielectric layer, the dielectric layer is laminated after the light emitting layer is applied, so that it is necessary to wait for the light emitting layer to dry, or the screen mesh must be replaced. Efficiency. Further, even when the area is increased, there is a limit due to the limitation of the size of the screen mesh and the apparatus, and it is difficult to manufacture an EL element having a diagonal size of 1 m or more.

  Further, as shown in, for example, Japanese Patent Application Laid-Open No. 5-251181 (Patent Document 3) and Japanese Patent Application Laid-Open No. 8-69880 (Patent Document 4), light emission is performed when a light emitting layer and a dielectric layer are sequentially laminated and applied. Since the interface between the layer and the dielectric layer dissolves the unevenness of the previously applied layer and the surface of the previously applied layer by the solvent of the subsequently applied layer, the smoothness is not maintained and the light emitting unevenness of the EL element is not maintained. There is a problem that occurs. On the other hand, as a continuous coating method, a doctor blade method described in Japanese Patent Application Laid-Open No. 6-151059 (Patent Document 5) is disclosed. However, this method has a problem that the coating liquid film surface is scraped off with a doctor blade, so that coating film failure such as film thickness unevenness and streaks tends to occur.

  Japanese Patent Application Laid-Open No. 11-233257 (Patent Document 6) discloses a method for manufacturing an EL element in which a plurality of layers of EL elements are simultaneously applied using an extrusion coater, as compared with a screen printing method. Although there is a description of the uniformity of the coating film and the reduction of the manufacturing process by simultaneous coating, the relationship between the viscosity of the coating liquid and the coating speed with respect to the film thickness of the target coating film is not suggested. Furthermore, there is no description of the particle size of the phosphor particles contained in the light emitting layer.

  Conventionally, an EL element is manufactured using an EL phosphor having an average particle size of 20 to 30 μm. However, when the particle size becomes large, there is a problem that a low-viscosity coating liquid cannot be maintained due to sedimentation of the EL phosphor particles. . Therefore, in the application of the light emitting layer, it is necessary to increase the viscosity of the coating solution, which is one of the factors that limit the coating method. Furthermore, even if it tries to make the film thickness of a light emitting layer thin, there exists a limit by the particle size of fluorescent substance particle, and the performance improvement of EL element is prevented significantly.

  In addition, since the EL element applies an alternating voltage, it has a problem that it generates vibrations during light emission and generates noise in the audible region. As a countermeasure, for example, as disclosed in Japanese Patent Laid-Open No. 9-266068 (Patent Document 7), a compensation electrode layer is provided outside the back electrode layer with an insulating layer interposed therebetween, and the transparent electrode layer and the shield electrode layer are electrically connected. Are connected to cancel the vibration generated by applying an alternating voltage of opposite phase between the transparent electrode layer and the back electrode layer and between the back electrode layer and the compensation electrode layer. Further, as shown in, for example, Japanese Patent Laid-Open No. 10-284247 (Patent Document 8) and Japanese Patent Laid-Open No. 2000-252057 (Patent Document 9), an EL element is provided with a material layer that absorbs vibration, thereby reducing vibration. Propagation is suppressed. In Japanese Patent Laid-Open No. 2001-230083 (Patent Document 10), vibration is further suppressed by a combination of a compensation electrode and a vibration damping layer. Since the vibration of the EL element is caused by distortion of the light emitting layer due to the piezoelectric effect, the configuration and driving conditions of the light emitting layer are a major factor. No mention is made of driving conditions. Further, if the luminance and area of the EL element are to be increased, it is essential to increase the driving voltage and frequency, and vibration and noise also increase at the same time, so conventional vibration countermeasures are insufficient.

JP-A-7-62342 JP-A-6-330035 JP-A-5-251181 JP-A-8-69880 Japanese Patent Laid-Open No. 6-151059 JP-A-11-233257 JP-A-9-266068 Japanese Patent Laid-Open No. 10-284247 JP 2000-252057 A Japanese Patent Laid-Open No. 2001-230083

  The present invention improves the generation of vibration and noise during light emission of a distributed EL element. In particular, it is an object to improve vibration and noise that increase with an increase in area and brightness of an EL element. In addition to providing technology to reduce the thickness of the light-emitting layer having the fine particle phosphor necessary to improve vibration and noise, each functional layer is applied sequentially or simultaneously on a support that is continuously transported (simultaneously). It aims at improving manufacturing efficiency by apply | coating.

The object of the present invention can be realized by the following means.
(1) In an electroluminescent device having at least an opposing electrode pair and a light emitting layer containing electroluminescent phosphor particles sandwiched between the electrode pair, on the buffer material layer and / or one or both sides outside the electrode pair An electroluminescence device comprising a compensation electrode layer provided through an insulating layer, wherein the light emitting layer has a thickness in a range of 0.5 to 30 μm.
(2) having a dielectric layer having a dielectric constant higher than that of the light emitting layer in addition to the light emitting layer containing the electroluminescent phosphor particles between the electrode pair, and the total film thickness thereof being in the range of 1 μm to 50 μm The electroluminescent device according to (1), wherein
(3) The electroluminescent phosphor particles according to either (1) or (2), wherein the electroluminescent phosphor particles contained in the light emitting layer have an average particle size in the range of 0.1 to 10 μm.
(4) The EL element according to any one of (1) to (3), wherein the EL phosphor contained in the light emitting layer has an average particle diameter in the range of 0.1 to 10 μm.
(5) A light emitting layer containing at least an opposing electrode pair, EL phosphor particles sandwiched between the electrode pair, a dielectric layer formed of a substance having a dielectric constant higher than that of the EL phosphor, a buffer layer, and A method for manufacturing an EL element comprising: a compensation electrode layer provided on an outer side of the electrode pair via an insulating layer, wherein at least one layer is continuously applied.
(6) A light emitting layer containing at least an opposing electrode pair, EL phosphor particles sandwiched between the electrode pair, a dielectric layer formed of a substance having a dielectric constant higher than that of the EL phosphor, a buffer layer, and A method for producing an EL element comprising: a compensation electrode layer provided on an outer side of the electrode pair via an insulating layer, wherein at least two types of overlapping layers are applied simultaneously and continuously.

  As in the present invention, by combining the thinning of the light emitting layer of the EL element with the buffer material layer and the compensation electrode layer, the generation of vibration and noise during light emission of the EL element can be greatly improved. The thinning of the light emitting layer has an effect that the luminance is increased because the voltage applied to the light emitting layer is higher than that in the case where the light emitting layer is thick as in the conventional EL element under the same driving conditions. Therefore, when driving with the same level of brightness as a conventional EL element, the drive voltage and frequency can be lowered, so that vibration and noise can be improved, and the area and the brightness of the EL element can be increased. Can also be supported. In addition to providing technology for thinning the light-emitting layer having fine particle phosphors necessary to improve vibration and noise, each functional layer is applied sequentially or simultaneously on a support that is continuously transported (simultaneously). By applying, it is possible to provide a suitable manufacturing method corresponding to a large area with a diagonal having a high manufacturing efficiency of 1 m or more.

  The present invention mainly relates to a manufacturing technique of fine EL phosphor particles necessary for thinning, a manufacturing technique of a thin light emitting layer using the fine EL phosphor particles, and vibration suppression that cancels or absorbs vibration during light emission. Consists of technology.

First, as the base material of particles preferably used in the present invention, specifically, one or more elements selected from the group consisting of Group II elements and Group VI elements, Group III elements and Group V elements are used. It is a semiconductor fine particle composed of one or a plurality of elements selected from the group consisting of group elements, and is arbitrarily selected according to the necessary emission wavelength region. Examples thereof include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, CaS, MgS, SrS, GaP, GaAs, and mixed crystals thereof. ZnS, CdS, CaS, and the like can be preferably used. Furthermore, as the base material of the _{particles, BaAl 2 S 4, CaGa 2} S 4, Ga 2 O 3, Zn 2 SiO 4, Zn 2 GaO 4, ZnGa 2 O 4, ZnGeO 3, ZnGeO 4, ZnAl 2 O 4, _{CaGa 2 O 4, CaGeO 3,} Ca 2 Ge 2 O 7, CaO, Ga 2 O 3, GeO 2, SrAl 2 O 4, SrGa 2 O 4, srP 2 O 7, MgGa 2 O 4, Mg 2 GeO 4, _{MgGeO 3, BaAl 2 O 4,} Ga 2 Ge 2 O 7, BeGa 2 O 4, Y 2 SiO 5, Y 2 GeO 5, Y 2 Ge 2 O 7, Y 4 GeO 8, Y 2 O 3, Y 2 O ₂ S, SnO ₂ and mixed crystals thereof can be preferably used. In addition, as the emission center, metal ions such as Mn and Cr and rare earths can be preferably used.

  The phosphor fine particles usable in the present invention can be formed by a firing method (solid phase method) widely used in the industry. For example, in the case of zinc sulfide, a fine particle powder (usually called raw powder) of 10 nm to 50 nm is prepared by a liquid phase method, and this is used as a primary particle, and an impurity called an activator is mixed therein together with a flux. First baking is performed in a crucible at a high temperature of 900 ° C. to 1300 ° C. for 30 minutes to 24 hours to obtain particles. The intermediate phosphor powder obtained by the first firing is repeatedly washed with ion exchange water to remove alkali metal or alkaline earth metal, excess activator and coactivator. Next, second baking is applied to the obtained intermediate phosphor powder. In the second baking, heating (annealing) is performed at a temperature lower than that of the first baking at 500 to 800 ° C. and for a short time of 30 minutes to 12 hours. These firings cause many stacking faults in the phosphor particles, but the conditions of the first firing and the second firing are appropriately set so that fine particles and more stacking faults are included in the phosphor particles. It is preferable to select.

  Further, by applying an impact force in a certain range to the first fired product, the density of stacking faults can be greatly increased without destroying the particles. As a method of applying an impact force, a method in which intermediate phosphor particles are brought into contact with each other, a method of mixing and mixing spheres such as alumina (ball mill), a method of accelerating and colliding particles, a method of irradiating ultrasonic waves, and the like are preferable. Can be used. Thereafter, the intermediate phosphor is etched with an acid such as HCl to remove the metal oxide adhering to the surface, and the copper sulfide adhering to the surface is removed by washing with KCN. Subsequently, the intermediate phosphor is dried to obtain an EL phosphor.

  In addition, in the case of zinc sulfide or the like, it is preferable to use a hydrothermal synthesis method as a method of forming phosphor particles because a multiple twin structure is introduced into the phosphor crystal. In the hydrothermal synthesis system, particles are dispersed in a well-stirred aqueous solvent, and zinc ions and / or sulfur ions that cause particle growth are determined from the outside of the reaction vessel at a flow rate controlled with an aqueous solution. Add for a long time. Therefore, in this system, the particles can move freely in an aqueous solvent, and the added ions can diffuse in water and cause particle growth uniformly. The concentration distribution of the agent can be changed, and particles that cannot be obtained by the firing method can be obtained. In controlling the particle size distribution, the nucleation process and the growth process can be clearly separated, and the particle size distribution can be controlled by freely controlling the degree of supersaturation during particle growth. Thus, monodispersed zinc sulfide particles having a narrow size distribution can be obtained. It is preferable to insert an Ostwald ripening step between the nucleation process and the growth process in order to adjust the grain size and realize a multiple twin structure.

  ZnS crystals have very low solubility in water, which is a very disadvantageous property in growing particles by ionic reaction in aqueous solution. The solubility of ZnS crystals in water increases as the temperature increases, but at 375 ° C. or higher, the water becomes a supercritical state, and the solubility of ions decreases drastically. Therefore, the particle preparation temperature. 100 degreeC or more and 375 degrees C or less are preferable, and 200 degreeC or more and 375 degrees C or less are more preferable. The time required for particle preparation is preferably within 100 hours, more preferably within 12 hours and 5 minutes or more.

  As another method for increasing the solubility of ZnS in water, a chelating agent is preferably used. As the chelating agent for Zn ions, those having an amino group and a carboxyl group are preferable. Specifically, ethylenediaminetetraacetic acid (hereinafter referred to as EDTA), N, 2-hydroxyethylethylenediaminetriacetic acid (hereinafter referred to as EDTA-OH). ), Diethylenetriaminepentaacetic acid, 2-aminoethylethyleneglycoltetraacetic acid, 1,3-diamino-2-hydroxypropanetetraacetic acid, nitrilotriacetic acid, 2-hydroxyethyliminodiacetic acid, iminodiacetic acid, 2-hydroxyethylglycine, Examples thereof include ammonia, methylamine, ethylamine, propylamine, diethylamine, diethylenetriamine, triaminotriethylamine, allylamine, and ethanolamine. In addition, in the case where the constituent metal ions and the cargoogen anion are directly precipitated by the precipitation reaction without using the precursors of the constituent elements, it is necessary to rapidly mix the solutions of both, and it is preferable to use a double jet mixer. .

  Moreover, it is preferable to use a urea melting method as a method for forming a phosphor usable in the present invention. The urea melting method is a method using molten urea as a medium for synthesizing a phosphor. A substance containing an element that forms a phosphor matrix or an activator is dissolved in a solution in which urea is maintained at a temperature equal to or higher than the melting point to be in a molten state. Add reactants as needed. For example, when a sulfide phosphor is synthesized, a sulfur source such as ammonium sulfate, thiourea or thioacetamide is added to cause a precipitation reaction. When the temperature of the melt is gradually raised to about 450 ° C., a solid in which phosphor particles and phosphor intermediates are uniformly dispersed in a resin derived from urea is obtained. After this solid is finely pulverized, it is fired while thermally decomposing the resin component in an electric furnace. By selecting an inert atmosphere, an oxidizing atmosphere, a reducing atmosphere, an ammonia atmosphere, or a vacuum atmosphere as the firing atmosphere, phosphor particles based on oxides, sulfides, and nitrides can be synthesized.

  Further, it is preferable to use a spray pyrolysis method as a method for forming a phosphor usable in the present invention. Phosphor precursor solution is made into fine droplets using an atomizer, and phosphor particles or phosphor intermediates are generated by condensation within the droplets, chemical reaction, or chemical reaction with the ambient gas surrounding the droplet. You can synthesize things. By making the conditions for droplet formation suitable, particles having a fine particle size, a uniform amount of impurities, a spherical shape, and a narrow particle size distribution can be obtained. As an atomizer that generates fine droplets, it is preferable to use a two-fluid nozzle, an ultrasonic atomizer, or an electrostatic atomizer. The fine droplets generated by the atomizer are introduced into an electric furnace with a carrier gas and heated to dehydrate and condense, and the chemical reaction and sintering of the substances in the droplets, or the chemistry with the atmosphere gas The target phosphor particles or phosphor intermediate product is obtained by the reaction. The obtained particles are additionally fired as necessary.

  For example, when synthesizing a zinc sulfide phosphor, a mixed solution of zinc nitrate and thiourea is atomized and thermally decomposed at about 800 ° C. in an inert gas (for example, nitrogen) to form a spherical zinc sulfide phosphor. obtain. If trace impurities such as Mn, Cu and rare earth are dissolved in the starting mixed solution, it acts as a luminescent center. Further, starting from a mixed solution of yttrium nitrate and europium nitrate at about 1000 ° C. in an oxygen atmosphere, an yttrium oxide phosphor activated with europium is obtained. The components in the droplet need not be completely dissolved, and may contain ultrafine particles such as silicon dioxide. Zinc silicate phosphor particles are obtained by thermochemical reaction of microdroplets containing zinc solution and ultrafine silicon dioxide particles.

  Further, as a method of forming a phosphor usable in the present invention, a gas phase method such as a laser ablation method, a CVD method, a plasma CVD method, a sputtering method, a resistance heating method, an electron beam method, a fluid oil surface deposition method, or the like. Further, a metathesis method, a method using a precursor thermal decomposition reaction, a reverse micelle method, a method combining these methods with high-temperature firing, a liquid phase method such as a freeze-drying method, and the like can also be used.

  In these methods, fine particles having a size of 0.1 μm or more and 10 μm or less that can be used in the present invention can be obtained by controlling the preparation conditions of the particles.

  More preferably, the phosphor particles have a non-light emitting shell layer on the surface of the particles. The shell layer is preferably formed with a thickness of 0.01 μm or more using a chemical method following the preparation of the semiconductor fine particles serving as the core of the phosphor particles. Preferably they are 0.01 micrometer or more and 1.0 micrometer or less. The non-light-emitting shell layer can be formed from an oxide, nitride, oxynitride, or a material that is formed on the base phosphor particles and has the same composition and does not contain an emission center. Moreover, it can form with the substance of a different composition grown epitaxially on the base | substrate fluorescent substance particle material. As a method of forming the non-light emitting shell layer, a laser ablation method, a CVD method, a plasma CVD method, a sputtering method, a resistance heating method, an electron beam method, and a gas phase method such as a method combining fluid oil surface deposition, a metathesis method, Sol-gel method, ultrasonic chemistry method, precursor thermal decomposition method, reverse micelle method or a combination of these methods with high-temperature firing, hydrothermal synthesis method, urea melting method, freeze drying method, etc. A thermal decomposition method or the like can also be used. In particular, the hydrothermal synthesis method, the urea melting method, and the spray pyrolysis method, which are preferably used in the formation of phosphor particles, are also suitable for the synthesis of a non-luminescent shell layer.

  For example, when a non-light-emitting shell layer is attached to the surface of zinc sulfide phosphor particles by using a hydrothermal synthesis method, a zinc sulfide phosphor serving as core particles is added and suspended in a solvent. As in the case of particle formation, a solution containing a metal ion to be a non-light emitting shell layer material and an anion as necessary is added from the outside of the reaction vessel at a controlled flow rate for a predetermined time. By sufficiently agitating the inside of the reaction vessel, the particles can move freely in the solvent, and the added ions can diffuse in the solvent and cause particle growth uniformly. The non-light emitting shell layer can be uniformly formed. By firing the particles as necessary, zinc sulfide phosphor particles having a non-light emitting shell layer on the surface can be synthesized.

  In addition, when a non-light emitting shell layer is attached to the surface of the zinc sulfide phosphor particles using the urea melting method, the metal salt that becomes the non-light emitting shell layer material is dissolved, and the zinc sulfide phosphor is dissolved in the molten urea solution. Add. Since zinc sulfide does not dissolve in urea, the temperature of the solution is raised as in the case of particle formation to obtain a solid in which the zinc sulfide phosphor and the non-light emitting shell layer material are uniformly dispersed in the urea-derived resin. After this solid is finely pulverized, it is fired while thermally decomposing the resin in an electric furnace. Zinc sulfide phosphor particles having a non-light emitting shell layer made of oxide, sulfide, or nitride on the surface by selecting an inert atmosphere, an oxidizing atmosphere, a reducing atmosphere, an ammonia atmosphere, or a vacuum atmosphere as a firing atmosphere Can be synthesized.

In addition, when a non-light emitting shell layer is attached to the surface of the zinc sulfide phosphor particles using the spray pyrolysis method, the zinc sulfide phosphor is added to a solution in which the metal salt as the non-light emitting shell layer material is dissolved. . By atomizing and thermally decomposing this solution, a non-light emitting shell layer is generated on the surface of the zinc sulfide phosphor particles. By selecting a pyrolysis atmosphere or an additional firing atmosphere, zinc sulfide phosphor particles having a non-light emitting shell layer made of an oxide, sulfide, or nitride on the surface can be synthesized.
The size of the electroluminescent phosphor used in the present invention is more preferably 0.5 to 5 μm.

The EL element of the present invention basically has a structure in which a light emitting layer is sandwiched between a pair of opposing electrodes, at least one of which is transparent. A dielectric layer is preferably adjacent between the light emitting layer and the electrode. Since the dielectric constant of a light emitting layer is about 10-100, the dielectric constant of a dielectric material layer becomes like this. Preferably it is 50-1000, More preferably, it is 100-600. Although the dielectric layer is designed to be relatively higher than the dielectric constant of the light emitting layer, it is preferable that the difference between the dielectric constants of the light emitting layer and the dielectric layer is large because the voltage distribution to the light emitting layer is large. As the light emitting layer, a material in which phosphor particles are dispersed in a binder can be used. As the binder, a polymer having a relatively high dielectric constant such as a cyanoethyl cellulose resin, or a resin such as polyethylene, polypropylene, polystyrene resin, silicone resin, epoxy resin, or vinylidene fluoride can be used. The dielectric constant can be adjusted by appropriately mixing fine particles having a high dielectric constant such as BaTiO ₃ or SrTiO _{3 with} these resins. As a solvent for dissolving the resin as a binder, dimethylformamide (DMF) or the like can be used. As a dispersion method, a homogenizer, a propeller mixer, a planetary kneader, a roll kneader, an ultrasonic disperser, or the like can be used.
In the present invention, the thickness of the light emitting layer (film thickness after drying of the coating film) is 0.5 μm or more and 30 μm or less, preferably 0.5 μm to 15 μm.
In the present invention, the light emitting layer contains a binder or the like with respect to the electroluminescent phosphor particles, but the content of the phosphor particles is preferably as high as possible, and preferably 40 to 95% by mass in the light emitting layer, more preferably 60 to 80% by mass.

As the dielectric layer, any material can be used as long as it has a high dielectric constant and insulation and has a high dielectric breakdown voltage. These are selected from metal oxides and nitrides, for example, TiO ₂ , BaTiO ₃ , SrTiO ₃ , PbTiO ₃ , KNbO ₃ , PbNbO ₃ , Ta ₂ O ₃ , BaTa ₂ O ₆ , LiTaO ₃ , Y ₂ O ₃ , Al ₂ O ₃ , ZrO ₂ , AlON, ZnS, or the like is used. These may be installed as a uniform film, or may be used as a film having a particle structure. In the case of a uniform film, the dielectric film may be prepared by a vapor phase method such as sputtering or vacuum deposition. In this case, the thickness of the film is usually in the range of 0.1 μm to 10 μm.

The EL phosphor-containing coating liquid or dielectric fine particle-containing coating liquid used in the method for producing an EL element of the present invention contains at least EL phosphor particles or dielectric fine particles, a binder, and a solvent that dissolves the binder. It is a coating solution. The viscosity of the EL phosphor-containing coating solution or dielectric fine particle-containing coating solution at room temperature is preferably 0.1 to 5 Pa · s, particularly preferably 0.3 to 1.0 Pa · s. If the viscosity of the EL phosphor-containing coating solution or the dielectric fine particle-containing coating solution is too low, coating film thickness unevenness is likely to occur, and the phosphor particles or dielectric fine particles separate and settle over time after dispersion. May end up. On the other hand, when the viscosity of the EL phosphor-containing coating liquid or the dielectric fine particle-containing coating liquid is too high, coating at a relatively high speed becomes difficult. The viscosity is a value measured at 16 ° C. which is the same as the coating temperature.
Further, the content of the dielectric fine particles in the derivative coating solution containing dielectric fine particles and a binder used in the present invention is preferably 40 to 95% by mass, more preferably 60 to 80% by mass.

Next, a preferred embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol in drawing shows the same thing.
The light-emitting layer is continuously applied on a plastic support with a transparent electrode, using a slide coater or extrusion coater, etc., so that the dry film thickness of the film is 0.5 μm or more and 30 μm or less. It is preferable to do. The application of the EL phosphor-containing coating solution can be suitably performed, for example, as shown in FIGS. Further, simultaneous application of the EL phosphor-containing coating film and the dielectric fine particle-containing coating film can be suitably performed, for example, as shown in FIGS.

  FIG. 1 is a schematic explanatory view for explaining a state in which an EL phosphor-containing coating solution is coated on a support using a slide coater in the EL element manufacturing method of the present invention. As shown in FIG. 1, a slide coater 3 is used as an application member for applying the EL phosphor-containing coating solution 4. The slide coater 3 is not particularly limited and can be appropriately selected from known ones. The slide coater 3 includes an accommodating portion 3a for accommodating the EL phosphor-containing coating solution 4 therein. When the slide coater 3 is activated, the EL phosphor-containing coating solution 4 is externally supplied from the accommodating portion 3a through the discharge port 3b. It moves on the surface inclined toward the discharge part tip 3c. The positional relationship between the slide coater 3 and the support 1 can be appropriately selected according to the purpose. For example, the support 1 is arranged on a plane, and the discharge portion tip 3c is located at a position facing the support 1. You may arrange | position the slide coater 3 so that it may. In this case, the support 1 is moved in parallel and the slide coater 3 is started. Conversely, the support 1 is fixedly arranged and the slide coater 3 is moved in parallel from one end of the support 1. Thus, the EL phosphor-containing coating solution 4 can be sequentially coated on the support 1. Furthermore, the EL phosphor-containing coating solution 4 may be applied to the support 1 by moving the slide coater 3 and the support 1 that are arranged to face each other in parallel as described above (in the same direction or in the opposite direction). it can.

  In the method for producing an EL element of the present invention, the application of the EL phosphor-containing coating solution 4 can be most suitably performed according to the following embodiment. That is, the slide coater 3 is arranged on the first plane, and its rotation axis is parallel to the direction perpendicular to the discharge direction of the EL phosphor-containing coating liquid 4 on the second plane located parallel to the first plane. It is the aspect by which the support body 1 is arrange | positioned so that it may wind on the roller 2 arrange | positioned so that C may be located. The roller 2 is particularly limited as long as it is a substrate having a circular cross section such as a so-called roller, such as a cylindrical shape or a columnar shape having an arbitrary constant inner diameter, at least in a portion where the support 1 is disposed. Instead, it can be appropriately selected from known ones. Further, the roller internal structure can be used in any form regardless of the hollow structure, the filling structure, or the like. The support 1 travels at a constant speed in the direction of arrow D together with the roller 2, and the EL phosphor-containing coating solution 4 is discharged from the slide coater 3 activated on the surface thereof and sequentially applied at a constant speed. A cooling water channel 5 in FIG. 1 passes through the inside of the slide coater 3, and cooling water such as well water is circulated in the cooling water channel 5 so that the slide coater 3 and the EL phosphor-containing coating solution 4 are kept at a constant temperature. Hold on. The moving speed when moving at least one of the support 1 and the slide coater 3 is preferably 1 to 100 m / min, and more preferably 5 to 50 m / min. If the relative movement speed is less than 1 m / min, not only the productivity is remarkably lowered, but also speed adjustment may be difficult. If the relative movement speed exceeds 100 m / min, the EL phosphor on the support 1 may be difficult. Stable coating of the containing coating solution 4 may be difficult.

In the present invention, the slide coater 3 is preferably disposed with a gap A (μm) between the discharge portion tip 3c from which the EL phosphor-containing coating solution 4 is discharged and the support 1. The gap A means the distance between the discharge portion tip 3c and the support 1 in the shortest distance direction between the rotation axis C of the roller 2 and the discharge portion tip 3c of the EL phosphor-containing coating liquid 4. A is determined from the relationship with the film thickness B (μm) of the coating film of the EL phosphor-containing coating solution coated on the support 1. In the present invention, the gap A and the film thickness B preferably satisfy the following relational expression:
0.25 × B ≦ A ≦ 0.55 × B
Furthermore, it is more preferable to satisfy the following relational expression.
0.30 × B ≦ A ≦ 0.50 × B
If the gap A is too small, streaky coating unevenness may occur on the coating surface, or a coating film with a uniform film thickness cannot be formed, that is, the film thickness difference due to coating unevenness may exceed the allowable value, If it is too large, the application suitability of the EL phosphor-containing coating solution is inferior, and the EL phosphor-containing coating solution may easily break during coating. Furthermore, when it is outside the above range, the film thickness of the coating film at the end in the width direction of the support becomes thick, and stable winding may not be performed.

  The slide coater 3 is disposed on the first plane, but is orthogonal to the discharge direction of the EL phosphor-containing coating liquid 4 on the second plane parallel to the first plane in the positional relationship with the roller 2. The rotation axis C of the roller 2 is located at a position parallel to the direction, and an angle θ between the rotation axis C and the shortest distance direction between the discharge portion tip 3c and the second plane is 5 to 45 °. It is preferable to arrange so that it is 10 to 30 °. If the angle θ is too small, streaky unevenness may occur on the coating surface, or a coating film with a uniform film thickness may not be formed. If the angle θ is too large, it is difficult to control the coating film thickness. May be.

  FIG. 3 is a view for explaining a state in which an EL phosphor-containing coating solution and a dielectric fine particle-containing coating solution are simultaneously coated on a support using a multi-stage slide coater in the EL device manufacturing method of the present invention. It is a schematic explanatory drawing. For simultaneous application of the EL phosphor-containing coating solution 4 and the dielectric fine particle-containing coating solution 6, a multistage slide coater 3 is used as a coating member. The multistage slide coater 3 is not particularly limited and can be appropriately selected from known ones. The multi-stage slide coater 3 includes an accommodating portion 3a for accommodating the EL phosphor-containing coating solution 4 therein, and an accommodating portion 3d for accommodating the dielectric fine particle-containing coating solution 6 therein, and activates the multi-stage slide coater 3. Then, the EL phosphor-containing coating solution 4 and the dielectric fine particle-containing coating solution 6 are discharged from the storage portions 3a and 3d to the outside through the discharge ports 3b and 3e, and move on the inclined surface toward the discharge portion tip 3c. The positional relationship between the multi-stage slide coater 3 and the support 1 can be appropriately selected according to the purpose. For example, the support 1 is arranged on a plane, and the discharge portion tip 3c is located at a position facing the support 1. The multistage slide coater 3 may be disposed so as to be positioned. In this case, the support 1 is moved in parallel and the multi-stage slide coater 3 is started. Conversely, the support 1 is fixedly arranged, and the multi-stage slide coater 3 is moved in parallel from one end of the support 1. By doing so, the EL phosphor-containing coating solution 4 and the dielectric fine particle-containing coating solution 6 can be simultaneously coated on the support 1. Furthermore, the EL phosphor-containing coating liquid 4 and the dielectric fine particles are formed on the support 1 by moving the multi-stage slide coater 3 and the support 1 which are arranged to face each other as described above in parallel (in the same direction or in the reverse direction). The containing coating liquid 6 can also be applied simultaneously. By further increasing the number of stages of the multistage slide coater, the back electrode layer can be applied simultaneously in addition to the light emitting layer and the dielectric layer. The most suitable conditions for simultaneous application using a multi-stage slide coater are the same as the most suitable conditions for applying the light emitting layer as a single layer using the above-mentioned slide coater.

  FIG. 2 is a schematic explanatory diagram for explaining a state in which an EL phosphor-containing coating solution is applied onto a support using an extrusion coater in the method for manufacturing an EL element of the present invention. As shown in FIG. 2, an extrusion coater 3 is used as an application member for applying the EL phosphor-containing application liquid. The extrusion coater 3 is not particularly limited and can be appropriately selected from known apparatuses. The extrusion coater 3 includes an EL phosphor-containing coating liquid container 3a that houses the EL phosphor-containing coating liquid 4 therein, and a tip discharge port 3b. When the extrusion coater 3 is activated, the EL phosphor The contained coating solution 4 is discharged from the storage portion 3a to the outside through the tip discharge port 3b. The positional relationship between the extrusion coater 3 and the support 1 can be appropriately selected according to the purpose. For example, the support 1 is arranged on a plane, and the tip discharge port 3b is located at a position facing the support 1. The extrusion coater 3 may be arranged so as to be positioned. In this case, for example, either one of the extrusion coater 3 or the support 1 is fixedly arranged, the other is sequentially translated, and the extrusion coater 3 is activated, whereby the surface of the support 1 is EL fluorescent. The body-containing coating solution 4 can be applied. In addition, the EL phosphor-containing coating solution 4 is applied to the surface of the support 1 by moving the extrusion coater 3 and the support 1 that are opposed to each other as described above in parallel (in the same direction or in the opposite direction). You can also.

  In the method for producing an EL element of the present invention, the application of the EL phosphor-containing coating solution can be most suitably performed according to the following embodiment. That is, the extrusion coater 3 is arranged on the first plane, and the EL phosphor-containing coating is on the second plane above the tip discharge port 3b of the extrusion coater 3 and parallel to the first plane. This is an aspect in which the support 1 is disposed on the roller 2 on which the axis C is positioned in parallel with the direction orthogonal to the discharge direction of the liquid 4. The roller 2 is not particularly limited as long as it is a cylindrical or columnar substrate having an arbitrary constant diameter at the portion where the support is disposed. The support 1 moves at a constant speed in the direction indicated by the arrow D together with the roller 2, and the EL phosphor-containing coating discharged from the EL phosphor-containing coating solution storage portion 3a on the surface of the support 1 with the activation of the extrusion coater 3 The liquid 4 is sequentially applied at a constant speed. The cooling water channel 5 in FIG. 1 passes through the inside of the extrusion coater 3, and in order to keep the extrusion coater 3 and the EL phosphor-containing coating solution 4 at a constant temperature, the cooling water channel 5 contains well water or the like. Cooling water is circulated. The moving speed when moving at least one of the extrusion coater 3 and the support 1 is preferably 1 to 100 m / min, and more preferably 5 to 50 m / min. If the relative movement speed is too low, not only the productivity is remarkably lowered, but also speed adjustment may be difficult. If it is too high, the EL phosphor-containing coating liquid 4 on the support 1 is stable. Application may be difficult.

The extrusion coater 3 is preferably disposed with a gap A (μm) between the tip discharge port 3 b from which the EL phosphor-containing coating solution 4 is discharged and the support 1. The gap A (μm) means the shortest distance between the tip discharge port 3b from which the EL phosphor-containing coating solution 4 is discharged and the support 1, and the EL phosphor-containing coating solution 4 applied on the support 1. It is determined from the relationship with the film thickness B (μm) of the coating film. In the present invention, the gap A (μm) and the film thickness B (μm) of the coating film preferably satisfy the following relational expression:
0.75 × B + 100 ≦ A ≦ 1.10 × B + 130
It is particularly preferable that the following relational expression is satisfied.
0.80 × B + 110 ≦ A ≦ 1.05 × B + 130
If the value of the gap A (μm) between the tip discharge port 3b of the extrusion coater 3 and the support 1 is too small, a coating streak that cannot be eliminated occurs, or a difference in film thickness within the same plane is allowed. The coating unevenness exceeding the value may occur, or the end may be thick and winding may be impossible. On the other hand, if the value of the gap A (μm) between the tip discharge port 3b of the extrusion coater 3 and the support 1 is too large, the application suitability of the EL phosphor-containing coating solution 4 is inferior, and the EL phosphor-containing coating solution is applied during coating. 4 running out of liquid may occur.

  In addition, the extrusion coater 3 is disposed on the first plane. At this time, the EL phosphor-containing coating solution 4 on the second plane located parallel to the first plane in the positional relationship with the roller 2. The axis C of the roller 2 is positioned in parallel to the direction perpendicular to the discharge direction, and the angle θ between the shortest distance direction between the tip discharge port 3b and the roller 2 and the second plane is preferably 0 to 30 °. 0 to 25 ° is particularly preferable. If the angle θ formed by the shortest distance direction between the tip discharge port 3b of the extrusion coater 3 and the roller 2 and the second plane is too large, unevenness in the thickness of the EL phosphor layer may easily occur. Further, the angle α formed between the discharge direction of the EL phosphor-containing coating liquid 4 and the second plane is preferably 5 to 60 °, and particularly preferably 5 to 30 °. If the angle α formed by the discharge direction of the EL phosphor-containing coating liquid 4 and the second plane is too small, coating stripes on the EL phosphor layer may easily occur. On the other hand, if α is too large, unevenness in the thickness of the EL phosphor layer may easily occur.

  FIG. 4 is a diagram for explaining a state in which an EL phosphor-containing coating solution and a dielectric fine particle-containing coating solution are simultaneously coated on a support using a multi-stage extrusion coater in the EL device manufacturing method of the present invention. It is a schematic explanatory drawing. As shown in FIG. 4, a multi-stage extrusion coater 3 is used as a coating member for the simultaneous application of the EL phosphor-containing coating solution and the dielectric fine particle-containing coating solution. The multistage extrusion coater 3 is not particularly limited and can be appropriately selected from known apparatuses. The multi-stage extrusion coater 3 includes an EL phosphor-containing coating liquid container 3a that houses an EL phosphor-containing coating liquid 4 therein, and a dielectric fine particle-containing coating liquid container that contains a dielectric fine particle-containing coating liquid 6 therein. 3c and tip discharge ports 3b and 3d, and when the multistage extrusion coater 3 is activated, the EL phosphor-containing coating solution 4 and the dielectric fine particle-containing coating solution 6 are respectively supplied from the storage portions 3a and 3c to the tip discharge ports. It is discharged outside from 3b and 3d. The positional relationship between the multistage extrusion coater 3 and the support 1 can be appropriately selected according to the purpose. For example, the support 1 is arranged on a plane and the tip discharge port 3b is located at a position facing the support 1. And the multistage extrusion coater 3 may be arranged so that 3d is located. In this case, for example, either the multi-stage extrusion coater 3 or the support 1 is fixedly arranged, the other is sequentially translated, and the multi-stage extrusion coater 3 is activated, so that the surface of the support 1 is The EL phosphor-containing coating solution 4 and the dielectric fine particle-containing coating solution 6 can be applied simultaneously. Further, the multi-stage extrusion coater 3 and the support 1 that are arranged to face each other as described above are moved in parallel (in the same direction or in the opposite direction), so that the EL phosphor-containing coating liquid 4 and the dielectric are formed on the surface of the support 1. The fine particle-containing coating solution 6 can also be applied. By further increasing the number of stages of the multistage extrusion coater, the back electrode layer can be applied simultaneously in addition to the light emitting layer and the dielectric layer. The most suitable conditions for simultaneous application using a multi-stage extrusion coater are the same as the most preferred conditions for applying the light emitting layer as a single layer using the above-described extrusion coater.

  Each functional layer coated on the support is preferably a continuous process from at least the coating to the drying process. The drying process is divided into a constant rate drying process until the coating film is dried and solidified, and a decreasing rate drying process for reducing the residual solvent of the coating film. In the present invention, since the binder ratio of each functional layer is high, when rapidly dried, only the surface is dried and convection occurs in the coating film, so-called Benard cell is likely to occur, and blister failure is caused by rapid solvent expansion. It tends to occur and remarkably impairs the uniformity of the coating film. On the other hand, if the final drying temperature is low, the solvent remains in each functional layer, which affects the subsequent process of forming EL elements such as a moisture-proof film laminating process. Therefore, it is preferable that the drying step is performed slowly at a constant rate drying step and performed at a temperature sufficient for the solvent to dry. As a method for slowly performing the constant rate drying step, it is preferable to divide the drying chamber in which the support travels into several zones and increase the drying temperature after the coating step in a stepwise manner.

  In the EL device of the present invention, any transparent electrode material that is generally used is used as the transparent electrode. Examples thereof include oxides such as tin-doped tin oxide, antimony-doped tin oxide, and zinc-doped tin oxide, a multilayer structure in which a silver thin film is sandwiched between high refractive index layers, and π-conjugated polymers such as polyaniline and polypyrrole. It is also preferred to improve the conductivity by arranging a comb-type or grid-type fine metal wire on these transparent electrodes. For the back electrode on the side from which light is not extracted, any conductive material can be used. It is selected from gold, silver, platinum, copper, iron, aluminum and other metals, graphite, etc. depending on the form of the element to be created, the temperature of the production process, etc. It may be used. Further, both electrodes can be prepared by preparing a conductive material-containing coating solution in which the conductive fine particle material is dispersed together with a binder, and using the above-described slide coater or extrusion coater.

  The conductive material described above can also be used when a compensation electrode is provided to suppress vibration of the EL element. In the present invention, the compensation electrode has a function (action) of applying a voltage having an opposite phase to the voltage applied to the light emitting layer to the element. For example, when a compensation electrode is provided outside the transparent electrode from which light is extracted, an oxide such as tin-doped tin oxide, antimony-doped tin oxide, or zinc-doped tin oxide, and a multilayer structure in which a thin film of silver is sandwiched between high refractive index layers It is preferable to use transparent electrode materials such as π-conjugated polymers such as polyaniline and polypyrrole. In addition, when a compensation electrode is provided outside the back electrode from which light is not extracted, any conductive material such as metal such as gold, silver, platinum, copper, iron, aluminum, graphite, etc. can be used. A transparent electrode such as ITO may be used as long as it has the property. The compensation electrode is attached to the transparent electrode or the back electrode via an insulating layer. The insulating layer material is an insulating inorganic material or polymer material, a dispersion liquid in which inorganic material powder is dispersed in a polymer material, or the like. Can be formed by vapor deposition, coating, or the like. Since the insulating layer has an insulating property, a dielectric layer containing high dielectric particles can also be used. Alternatively, a conductive material-containing coating solution in which the conductive fine particle material is dispersed together with a binder can be prepared and applied using the above-described slide coater or extrusion coater. Furthermore, an insulating material-containing coating solution in which the insulating material is dispersed together with a binder can be prepared and applied simultaneously with the conductive material-containing coating solution. A voltage is applied to the compensation electrode provided from the drive power supply. At this time, the vibration generated in the light emitting layer can be canceled by setting the phase opposite to the voltage applied to the light emitting layer. The compensation electrode has the same effect even if it is attached to either the outside of the transparent electrode or the outside of the back electrode with an insulating layer sandwiched between them. It is preferable because it is possible. In order to effectively suppress vibrations, it is preferable to adjust the dielectric constant of the light emitting layer (and the dielectric layer) and the dielectric constant of the insulating layer inside the compensation electrode to be substantially equal.

  As another method for suppressing vibration of the EL element, when a buffer material layer used for the EL element is provided, a polymer material having a high impact absorbing ability or a polymer material foamed by adding a foaming agent may be used. preferable. Examples of polymer materials with high impact absorption include natural rubber, styrene butadiene rubber, polyisoprene rubber, polybutadiene rubber, nitrile rubber, chloroprene rubber, butyl rubber, hyperon, silicon rubber, urethane rubber, ethylene propylene rubber, and fluorine rubber. Can be used. The hardness of these polymer materials is preferably 50 or less, more preferably 30 or less, from the viewpoint of vibration absorption ability. In addition, butyl rubber, silicon rubber, fluorine rubber, and the like are more preferable because they have low water absorption and function as a protective film that protects the EL element from moisture. It is also preferable to use as a buffer material a material obtained by adding a foaming agent to the above rubber material, polypropylene, polystyrene, or polyethylene resin. The buffer material layer using these buffer materials can be attached by adhering the buffer material layer to the EL element with an adhesive, but the buffer material is dissolved in a solvent to prepare a buffer material-containing coating solution, It can also apply | coat using the above-mentioned slide coater or extrusion coater. Although the thickness of the buffer layer depends on the hardness of the polymer material, it is preferably 20 μm or more and more preferably 50 μm or more in order to sufficiently absorb vibration. When the thickness is 200 μm or more, the thickness of the element increases greatly, which is not preferable in terms of mass and flexibility. The position of the buffer material layer is not particularly limited, but is preferably other than between the transparent electrode layer and the back electrode layer in order to cause a decrease in luminous efficiency. In particular, it is preferably provided between the EL element holding member and the EL element. Further, the combined use of the compensation electrode and the buffer material layer is preferable because vibration can be further suppressed.

  However, since the above-described vibration suppression technology alone is insufficient for the generation of vibration that increases due to the increase in the area of the EL element, it is preferable to obtain a synergistic effect in combination with a thinned light emitting layer. When the light emitting layer is thinned, the voltage applied to the light emitting layer is higher than that when the light emitting layer is thick as in the conventional EL element under the same driving conditions, so that the luminance is increased. In the case of driving with a luminance comparable to that of a conventional EL element, the driving voltage and frequency can be lowered, so that vibration and noise can be further improved. In order to obtain such an effect, the thickness of the light emitting layer is preferably 0.5 μm or more and 30 μm or less, and particularly preferably 15 μm or less. Furthermore, the phosphor layer in contact with the dielectric material is included in the light emitting layer, and the total film thickness of the dielectric layer including the inorganic dielectric material adjacent to the light emitting layer including the phosphor material as necessary is the thickness of the phosphor. The average particle size is preferably 3 to 10 times. The contact between the phosphor material and the dielectric material is preferably that the phosphor material is completely or partially covered with the non-light emitting shell layer. However, the phosphor material and the dielectric material may simply be in contact. Moreover, although the minimum of element thickness is a fluorescent substance particle size, in order to ensure the smoothness of an element, it is preferable that the thickness of an element is 3-10 times with respect to the size of a fluorescent substance particle. The thickness of the element here refers to the total thickness of the light emitting layer including the phosphor particles sandwiched between the electrodes and the dielectric layer adjacent thereto. In this case, the total thickness is preferably 1 μm or more and 50 μm or less, and particularly preferably 30 μm or less.

  As the phosphor particles used in the present invention, it is preferable to use particles having an average particle diameter of 0.1 to 10 μm in order to uniformly form a light emitting layer of 30 μm or less. By setting the particle size of the phosphor particles to 10 μm or less, the uniformity of the coating film thickness of the light emitting layer is improved, and the smoothness of the coating film surface is simultaneously improved. Furthermore, when the number of particles per unit area is greatly increased, fine light emission unevenness can be remarkably improved. For example, when using phosphor particles having an average particle diameter of 10 μm as compared with the conventional case where phosphor particles having an average particle diameter of 20 μm are used, the unit area is 8 times larger even if simply calculated at the same coating mass. If the average particle diameter is 1 μm, the number of particles per unit area is increased by 8000 times, and the uniformity of light emission can be improved. Furthermore, the decrease in the particle size leads to an increase in the applied voltage of the phosphor particles, which is preferable for improving the luminance of the EL element in combination with the increase in the electric field strength to the light emitting layer due to the thinning of the light emitting layer. It is also preferable for suppression of vibration.

  The dielectric material of the present invention may be a thin film crystal layer or a particle shape. A combination thereof may also be used. The dielectric layer containing the dielectric substance may be provided on one side of the phosphor particle layer, and is preferably provided on both sides of the phosphor particle layer. When the dielectric layer is formed by coating, it is preferable to use a slide coater or an extrusion coater similarly to the light emitting layer. In the case of a thin film crystal layer, a thin film may be formed on the substrate by a vapor phase method such as sputtering, or a sol-gel film using an alkoxide such as Ba or Sr. In the case of a particle shape, it is preferable that the size is sufficiently small with respect to the size of the phosphor particles. Specifically, a size of 1/3 to 1/1000 of the phosphor particle size is preferable. When the EL element is thin and excited by a high electric field as in the present invention, it is important that the distance between the electrodes sandwiching the EL element is uniform. Specifically, when the variation in the distance between the electrodes is viewed as the center line average roughness Ra, it is preferably (d × 1/8) μm or less with respect to the light emitting layer thickness d μm.

  The EL element of the present invention is preferably processed using a suitable sealing material so as to eliminate the influence of humidity from the external environment. When the element substrate itself has a sufficient shielding property, a shielding sheet is overlaid on the fabricated element, and the periphery is sealed with a curable material such as epoxy. Such a shielding sheet is selected from glass, metal, plastic film and the like according to the purpose.

  The use of the present invention is not particularly limited, but considering the use as a light source, the emission color is preferably white. Examples of the method for making the emission color white include a method using phosphor particles that emit white light alone, such as a zinc sulfide phosphor that is activated by manganese with copper and gradually cooled after firing, or three primary colors or A method of mixing a plurality of phosphors that emit light in complementary colors is preferable. (A combination of blue-green-red, a combination of blue-green-orange, etc.) Also, like the blue color described in JP-A-7-166161, JP-A-9-245511, and JP-A-2002-62530 Also preferred is a method in which light is emitted at a short wavelength, and a part of the light emission is converted into green or red by using a fluorescent pigment or a fluorescent dye (light emission) and whitened. Further, the CIE chromaticity coordinates (x, y) preferably have an x value in the range of 0.30 to 0.43 and a y value in the range of 0.27 to 0.41.

  In addition, in the element configuration of the present invention, a substrate, a transparent electrode, a back electrode, various protective layers, a filter, a light scattering reflection layer, and the like can be provided as necessary. In particular, regarding the substrate, in addition to a glass substrate or a ceramic substrate, a flexible resin sheet can be used for the flexible substrate.

In the present invention, it is preferable to appropriately combine the phosphor particles having the above-described characteristics and the EL element configuration, thereby providing an EL element with high luminance and large area and suppressing vibration.
5 to 9 show preferred embodiments of the electroluminescence element (EL element) in the present invention in cross-sectional views. In the figure, 7 is a protective film provided on the transparent film 8 or the compensation electrode layer 14, 9 is a transparent electrode layer, 10 is a light emitting layer containing phosphor particles, 11 is a dielectric layer, 12 is a back electrode layer, 13 Indicates an insulating layer. 7 and 8, 15 indicates a buffer layer. The dispersion state of the phosphor particles 10a in the light emitting layer 10 is schematically shown. FIG. 10 is a cross-sectional view of a conventional EL device, and the same reference numerals as those in FIGS.

  Although the Example in the manufacturing method of the light emitting layer of this invention is described, the Example of this invention is not restrict | limited to the following each Example. In addition, in a present Example, the viscosity of each coating liquid uses a viscometer (VISCONIC ELD.R and VISCOMETER CONTROLLER E-200 rotor No.71, Tokyo Keiki Co., Ltd. product), and is stirring (rotation speed: 20 rpm). , And measured at a liquid temperature of 16 ° C.

(Example 1)
ZnS: Cu, Mn, Cl phosphor particles emitting white light with an average particle size of 5 μm as an EL phosphor, cyanoresin (manufactured by Shin-Etsu Chemical Co., Ltd .; CR-S) as a binder, and DMF as a solvent for dissolving the binder are prepared. . The following composition was added to a DMF organic solvent and dispersed with a propeller mixer (rotation speed: 3000 rpm) to prepare an EL phosphor-containing coating solution having a viscosity at 16 ° C. of 0.5 Pa · s.
・ EL phosphor (ZnS: Cu, Mn, Cl): 100 parts by mass • Cyanoresin: 25 parts by mass

  Next, a roller having a circular cross section and a slide coater are arranged so as to face each other, and a coating apparatus similar to that shown in FIG. 1 in which a support is wound around the roller is prepared. The EL phosphor obtained as described above The containing coating liquid was introduced into the accommodating portion 3a in the slide coater 3 by a liquid feed pump. Polyethylene terephthalate (thickness: 100 μm) on which an ITO transparent electrode is sputtered as a support was provided so as to wind the roller 2, and the roller 2 was rotated so as to run at a constant speed in the direction of arrow D. The slide coater 3 has a gap A between the discharge portion tip 3c and the support 1 in the shortest distance direction between the rotation axis C of the roller 2 and the discharge portion tip 3c of the slide coater 3, and further rotates the roller 2. The angle θ formed by the shortest distance direction between the axis C and the discharge portion tip 3c and the horizontal plane was set to 15 °. Further, a cooling water channel 5 was provided in the slide coater 3, and the temperature of the slide coater 3 and the EL phosphor-containing coating solution 4 was maintained at about 16 ° C. by circulating well water. The slide coater 3 was activated, and the EL phosphor-containing coating solution accommodated in the accommodating portion 3a was discharged from the discharge port 3b in a fixed amount so that the target film thickness of the dried coating film was 20 μm by the liquid feeding pump. On the other hand, the moving speed of the support 1 that travels in the direction of arrow D is a constant speed of 10 m / min, moves along the inclination from the discharge port 3b, and is continuously applied to the support 1 with a width of 2 m for 1000 m. . After coating, the sheet was sequentially transferred to a drying chamber, gradually heated from 40 ° C. and dried at a final drying temperature of 120 ° C., and a sheet-like laminate in which a wound EL phosphor layer was formed on ITO was obtained. The obtained EL phosphor layer had a dielectric constant of 25.

A dielectric layer, a back electrode layer, an insulating layer, and a compensation electrode layer were formed on the sheet-like laminate obtained as described above to produce an EL element. As dielectric fine particles, barium titanate BT-8 (manufactured by Cabot Specialty Chemicals: average particle size 120 nm), cyanoresin (manufactured by Shin-Etsu Chemical Co., Ltd .; CR-S) as a binder, and DMF as a solvent for dissolving the binder are prepared. The following composition was added to a DMF organic solvent and dispersed with a propeller mixer (rotation speed: 3000 rpm) to prepare a coating solution containing dielectric fine particles having a viscosity at 25 ° C. of 0.5 Pa · s.
-BT-8 ... 90 parts by mass-Cyanoresin ... 30 parts by mass

  The sheet-like laminate is placed again on the coating apparatus provided with the above-described slide coater, and the coating solution containing the dielectric fine particles is applied onto the light-emitting layer of the sheet-like laminate by the same method as the application of the light-emitting layer. The dried film was applied and dried at a moving speed of 10 m / min so that the dry film thickness of the film became 10 μm. The dielectric constant of the obtained dielectric layer was 150. On top of that, a 30 μm thick aluminum foil as a back electrode, a 100 μm thick polyethylene terephthalate as an insulating layer, and a 30 μm thick aluminum foil as a compensation electrode were sequentially bonded together to cut out a sheet-like laminate having a size of 1 m × 1 m. . Thereafter, lead wires for supplying voltage to the transparent electrode, the back electrode, and the compensation electrode were provided. Finally, the entire sheet-like laminate was laminated with a moisture-proof film to produce an EL element having the configuration shown in FIG.

(Example 2)
In the same manner as in Example 1, an EL phosphor-containing coating solution having a viscosity of 0.5 Pa · s was prepared. Next, barium titanate BT-8 (manufactured by Cabot Specialty Chemicals: average particle size 120 nm) is prepared as dielectric fine particles, cyanoresin (manufactured by Shin-Etsu Chemical Co., Ltd .; CR-S), and DMF is prepared as a solvent for dissolving the binder. To do. The following composition was added to a DMF organic solvent and dispersed with a propeller mixer (rotation speed: 3000 rpm) to prepare a coating solution containing dielectric fine particles having a viscosity at 16 ° C. of 0.5 Pa · s.
-BT-8 ... 90 parts by mass-Cyanoresin ... 30 parts by mass

  Next, a roller having a circular cross section and a slide coater are arranged so as to face each other, and a coating device similar to that shown in FIG. 3 in which a support is wound around the roller is prepared. The EL phosphor obtained as described above The containing coating liquid and the dielectric fine particle-containing coating liquid were introduced into the accommodating portions 3a and 3d in the multistage slide coater 3 by separate liquid feeding pumps. The introduced EL phosphor-containing coating solution 4 and dielectric fine particle-containing coating solution 6 have the same viscosity. Polyethylene terephthalate (thickness: 100 μm) on which an ITO transparent electrode is sputtered as a support was provided so as to wind the roller 2, and the roller 2 was rotated so as to run at a constant speed in the direction of arrow D. The multi-stage slide coater 3 has a gap A between the discharge portion tip 3c and the support 1 in the shortest distance direction between the rotation axis C of the roller 2 and the discharge portion tip 3c of the multi-stage slide coater 3; The angle θ formed by the shortest distance direction between the rotation axis C and the discharge portion tip 3c and the horizontal plane is set to 15 °. Further, a cooling water channel 5 is provided in the multistage slide coater 3, and the temperature of the multistage slide coater 3, the EL phosphor-containing coating solution 4, and the dielectric fine particle-containing coating solution 6 is set to about 16 ° C. by circulating well water. Held on. The multi-stage slide coater 3 is activated, and the EL phosphor-containing coating solution 4 and the dielectric fine particle-containing coating solution 6 accommodated in the accommodating portions 3a and 3d by the liquid feeding pumps are respectively set to a target film thickness of 20 μm for the dry coating film. A fixed amount was discharged from the discharge ports 3b and 3e so as to be 10 μm. On the other hand, the moving speed of the support 1 that travels in the direction of arrow D is set to a constant speed of 10 m / min, and it moves along the inclination from the discharge ports 3b and 3d and contains the EL phosphor that flows out from the discharge portion tip 3c. The coating liquid 4 and the dielectric fine particle-containing coating liquid 6 were continuously coated on the support 1 with a width of 2 m for 1000 m. After coating, the sheet-like laminate is sequentially sent to a drying chamber, gradually heated from 40 ° C. and dried at a final drying temperature of 120 ° C., and a wound EL phosphor layer and a dielectric layer are formed on ITO. Got. The dielectric constants of the obtained EL phosphor layer and dielectric layer were 25 and 150, respectively. On top of that, a 30 μm thick aluminum foil as a back electrode, a 100 μm thick polyethylene terephthalate as an insulating layer, and a 30 μm thick aluminum foil as a compensation electrode were sequentially bonded together to cut out a sheet-like laminate having a size of 1 m × 1 m. . Thereafter, lead wires for supplying voltage to the transparent electrode, the back electrode, and the compensation electrode were provided. Finally, the entire sheet-like laminate was laminated with a moisture-proof film to produce an EL element having the configuration shown in FIG.

(Example 3)
In the same manner as in Example 1, a light emitting layer, a dielectric layer, and a back electrode were produced on a polyethylene terephthalate (100 μm thick) support on which an ITO transparent electrode was sputtered to obtain a sheet-like laminate. In order to produce a dielectric layer on the obtained sheet-like laminate, it was placed again on the coating apparatus on which the above-mentioned slide coater was placed. Coating and drying were performed so that the target film thickness was 10 μm. Furthermore, in order to produce a compensation electrode on the obtained sheet-like laminate, it was placed again on the coating apparatus on which the slide coater was placed, and 80 parts by mass of carbon powder and 10 parts by mass of polyester resin were dissolved in methyl ethyl ketone (MEK). The conductive material-containing coating solution was applied and dried at a viscosity of 0.5 Pa · s and a moving speed of the sheet-like laminate of 10 m / min so that the dry film thickness of the coating film was 20 μm. . The obtained sheet-like laminate was cut into a size of 1 m × 1 m. Thereafter, lead wires for supplying voltage to the transparent electrode, the back electrode, and the compensation electrode were provided. Finally, the entire sheet-like laminate was laminated with a moisture-proof film to produce an EL element having the configuration shown in FIG.

Example 4
In the same manner as in Example 1, a light emitting layer, a dielectric layer, and a back electrode were produced on a polyethylene terephthalate (100 μm thick) support on which an ITO transparent electrode was sputtered to obtain a sheet-like laminate. In order to produce a buffer material layer on the obtained sheet-like laminate, the coating material containing the buffer material in which butyl rubber was dissolved in toluene was placed again in the coating apparatus in which the above-described slide coater was placed, and the dry film thickness of the coating film Was applied and dried at a viscosity of 0.5 Pa · s and a moving speed of the sheet-like laminate of 10 m / min. The obtained sheet-like laminate was cut into a size of 1 m × 1 m. Thereafter, lead wires for supplying voltage to the transparent electrode and the back electrode were provided. Finally, the entire sheet-like laminate was laminated with a moisture-proof film to produce an EL element having the configuration shown in FIG.

(Example 5)
In the same manner as in Example 1, a light emitting layer, a dielectric layer, and a back electrode were produced on a polyethylene terephthalate (100 μm thick) support on which an ITO transparent electrode was sputtered to obtain a sheet-like laminate. The obtained sheet-like laminate was cut into a size of 1 m × 1 m. Then, the lead wire for supplying a voltage to a transparent electrode and a back electrode was attached, and the whole sheet-like laminated body was laminated with the moisture proof film. Finally, a buffer material layer of butyl rubber was formed to a thickness of 100 μm on the moisture-proof film surface on the back electrode side of the laminated sheet-like laminate to produce the EL device shown in FIG.

(Example 6)
An EL element was produced in the same manner as in Example 1. Furthermore, a butyl rubber buffer material layer was formed to a thickness of 100 μm on the moisture-proof film surface on the back electrode side of the laminated sheet-like laminate to produce the EL device shown in FIG.

(Comparative Example 1)
In the same manner as in Example 1, a light emitting layer, a dielectric layer, and a back electrode were produced on a polyethylene terephthalate (100 μm thick) support on which an ITO transparent electrode was sputtered to obtain a sheet-like laminate. The obtained sheet-like laminate was cut into a size of 1 m × 1 m. Thereafter, lead wires for supplying voltage to the transparent electrode and the back electrode were provided. Finally, the entire sheet-like laminate was laminated with a moisture-proof film to produce the EL element shown in FIG.

(Comparative Example 2)
An EL phosphor-containing coating solution was prepared in the same manner as in Comparative Example 1 using a ZnS: Cu, Cl phosphor having an average particle diameter of 15 μm as the EL phosphor, and a slide coater was used. As a constant speed of 10 m / min, 1000 m was continuously applied on the support 1 with a width of 2 m so that the target film thickness of the dried coating film was 50 μm. The EL element shown in FIG. 10 was produced in the same manner as in Comparative Example 1.

<Test Example 1 (Evaluation of EL element)>
In an anechoic chamber, the EL elements of Examples 1 to 6 and Comparative Examples 1 and 2 were attached to a 5 mm thick acrylic plate attached to an aluminum frame, respectively, and a transparent electrode and a back electrode as shown in the figure. A device provided with a compensation electrode was connected to the compensation electrode, and light was emitted by applying a sinusoidal AC voltage so that the luminance of each EL element was constant. Table 1 shows the results of the evaluation of the relative noise level relative to the noise level of Comparative Example 1 taken as 100 after stabilization.
The evaluation criteria are as follows.
◎: Less than 90 ○: 90 or more and less than 100 △: Relative noise level 100
X: Greater than 100

  As shown in Table 1, Comparative Example 1 is an EL element having a configuration in which neither a compensation electrode nor a buffer material layer is attached, and its noise level is very high. In Examples 1 to 3, a compensation electrode is provided, and an AC voltage of opposite phase is applied between the transparent electrode and the back electrode and between the back electrode and the compensation electrode, so that vibration caused by light emission is generated. The noise level was greatly improved as compared with Comparative Example 1. Further, in Examples 4 and 5, the noise level was greatly improved as compared with Comparative Example 1 by providing a buffer material layer, and became equivalent to Examples 1-3. Furthermore, Example 6 showed the lowest noise level in Examples by providing both the compensation electrode and the buffer material layer. In Comparative Example 2, since the average particle diameter of the phosphor particles contained in the light emitting layer is large and the film thickness of the light emitting layer is large, vibration generated during light emission is further deteriorated compared to Comparative Example 1 in which the light emitting layer is thin, The highest noise level was obtained among the manufactured EL elements. As is clear from the above, it can be seen that the vibration at the time of light emission is greatly improved by the combination of the thinning of the light emitting layer of the EL element and the vibration suppression technology using the buffer material layer and the compensation electrode.

FIG. 1 is a schematic explanatory diagram for explaining a state in which an electroluminescent phosphor-containing coating solution is applied onto a support using a slide coater in the method for manufacturing an electroluminescent element of the present invention. FIG. 2 is a schematic explanatory diagram for explaining a state in which an electroluminescent phosphor-containing coating solution is coated on a support using an extrusion coater in the method for producing an electroluminescent element of the present invention. FIG. 3 illustrates a state in which the electroluminescent phosphor-containing coating liquid and the dielectric fine particle-containing coating liquid are coated on a support using a multistage slide coater in the method for manufacturing an electroluminescent element of the present invention. It is a schematic explanatory drawing for this. FIG. 4 illustrates a state in which the electroluminescent phosphor-containing coating liquid and the dielectric fine particle-containing coating liquid are coated on a support using a multistage extrusion coater in the method for manufacturing an electroluminescent element of the present invention. It is a schematic explanatory drawing for doing. It is sectional drawing of the EL element of Example 1 or 2 of this invention. It is sectional drawing of the EL element of Example 3 of this invention. It is sectional drawing of the EL element of Example 4 of this invention. It is sectional drawing of the EL element of Example 5 of this invention. It is sectional drawing of the EL element of Example 6 of this invention. It is sectional drawing of the EL element of the comparative example 1 or 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support body 2 Roller 3 Coater 3a EL fluorescent substance containing coating liquid storage part 3b EL fluorescent substance containing coating liquid discharge port 3c Discharge part front end 3d Dielectric fine particle containing coating liquid storage part 3e Dielectric fine particle containing coating liquid discharge port 4 Coating liquid 5 Cooling channel 6 Coating liquid containing dielectric fine particles A Distance between coater discharge port tip and support B Coating film thickness C Roller axis of rotation D Support speed of rotation θ Rotary axis and discharge part of coater Angle between the shortest distance direction to the tip and the horizontal plane α Angle between the coating liquid discharge direction of the extrusion coater and the horizontal plane 7 Protective film 8 Transparent film (polyethylene terephthalate)
DESCRIPTION OF SYMBOLS 9 Transparent electrode layer 10 Light emitting layer 10a Phosphor particle 11 Dielectric layer 12 Back electrode layer 13 Insulating layer 14 Compensation electrode layer 15 Buffer material layer

Claims (5)

  In an electroluminescent device having at least an opposing electrode pair and a light emitting layer containing electroluminescent phosphor particles sandwiched between the electrode pair, a buffer layer and / or an insulating layer on one or both sides outside the electrode pair An electroluminescence device comprising a compensation electrode layer provided therebetween, wherein the light emitting layer has a thickness in a range of 0.5 μm to 30 μm.   In addition to a light emitting layer containing electroluminescent phosphor particles between electrode pairs, a dielectric layer having a dielectric constant higher than that of the light emitting layer, and a total film thickness thereof is in a range of 1 μm to 50 μm. The electroluminescent device according to claim 1.   The electroluminescent element according to claim 1, wherein the electroluminescent phosphor particles contained in the light emitting layer have an average particle size in the range of 0.1 to 10 μm.   A light emitting layer having a thickness of 0.5 to 30 μm containing at least an opposing electrode pair and electroluminescent phosphor particles sandwiched between the electrode pair and a material having a dielectric constant higher than that of the electroluminescent phosphor In a method of manufacturing an electroluminescent element having a dielectric layer and a buffer layer and / or a compensation electrode layer provided outside the electrode pair via an insulating layer, at least one layer is continuously applied. A method for manufacturing an electroluminescent element.   A light emitting layer having a thickness of 0.5 to 30 μm containing at least an opposing electrode pair and electroluminescent phosphor particles sandwiched between the electrode pair and a material having a dielectric constant higher than that of the electroluminescent phosphor In a method of manufacturing an electroluminescent device having a dielectric layer and a buffer layer and / or a compensation electrode layer provided outside the electrode pair via an insulating layer, at least two types of overlapping layers are applied simultaneously and continuously. A method of manufacturing an electroluminescent element characterized by the above.

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