JP2006045319A - Method for producing phosphor particle, phosphor particle and dispersion type electroluminescence element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing phosphor particles that can reduce discoloration of particle surfaces and can introduce a large amount of copper into the phosphor without segregating copper and provide phosphor particles by using the method and can provide a high brightness electroluminescence element using the phosphor particles. <P>SOLUTION: This is a method for producing a zinc sulfide phosphor by calcinig the zinc sulfide activated with copper, in more detail, to provide a method for producing a zinc sulfide phosphor in which the calcined product includes copper in an amount of 0.05 mol% to less than 1.0 mol% and a copper introduction accelerating agent are arranged between the calcination products and the open air. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a phosphor particle, in particular, a phosphor particle suitable for a dispersed electroluminescence element, and a method for producing the same.

  A dispersive electroluminescence device has a structure in which a phosphor layer in which phosphor particles are dispersed in a binder having a high dielectric constant is sandwiched between two electrodes, at least one of which is transparent, and an AC electric field is generated between the two electrodes. Emits light when applied. A light-emitting element produced using electroluminescent phosphor particles can have a thickness of several millimeters or less, is a surface light emitter, and has many advantages such as less heat generation. Dispersion-type electroluminescent elements do not use high-temperature processes, so that flexible elements using plastic as a substrate are possible, and they can be manufactured at a low cost in a relatively simple process without using a vacuum device. In addition, it has a 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 various backlights. However, since the dispersion type electroluminescence element is not yet sufficient in terms of luminance, its use such as a backlight of a mobile phone has been limited.

  In order to expand the application, the electroluminescent phosphor particles are required to have high brightness. In the electroluminescent phosphor particles, it is considered that the electric field is concentrated in the CuxS needle-like crystal existing in the phosphor particles, electrons are generated, electrons are introduced into the emission center, and light is emitted (for example, Non-Patent Document 1). 2). In order to precipitate CuxS needle-like crystals in the phosphor particles, it is necessary to incorporate copper beyond the solid solution limit into the particles to precipitate CuxS needle-like crystals. In order to improve the luminance, it is necessary to increase the amount of copper incorporated into the particles in order to increase the amount of CuxS needle-like crystals that are electron generation sources.

  In order to prevent oxidation, zinc sulfide phosphors are known to be baked in an oxygen-blocked manner by firing in hydrogen sulfide or nitrogen, or firing using carbon or the like. . However, in an oxygen barrier atmosphere, when a large amount of copper is taken in, copper is segregated and colored on the surface. Since there is light absorption by the coloring component, electroluminescence with sufficient luminance cannot be obtained.

  Of zinc sulfide phosphors, phosphors particularly for electroluminescence are generally fired in air. (For example, refer to Patent Documents 1 and 2). When firing in air, copper uptake proceeds and coloration decreases. However, on the other hand, since zinc oxide is formed by oxygen, the luminance is also lowered.

Thus, conventionally, since it has been difficult to simultaneously improve copper uptake and suppress oxidation, it has been difficult to obtain an electroluminescent phosphor having sufficient luminance.
JP 2000-136381 A JP-A-6-33053 Fischer et al., "Journal of the Electrochemical Society", Vol. 109, No. 11, (1962) 1043 Fischer et al., "Journal of the Electrochemical Society", Vol. 110, No. 7, (1962) 733

  An object of the present invention is to provide a method for producing phosphor particles that reduces the coloration of the particle surface and introduces a large amount of copper without causing segregation of the phosphor, and further provides phosphor particles by the production method. Another object is to provide a high-brightness electroluminescent device using the phosphor particles.

The object of the present invention has been achieved by the following means.
(1) A method for producing a zinc sulfide phosphor in which zinc sulfide activated with copper is baked, wherein the baked article contains 0.05 mol% or more and less than 1.0 mol% of copper, and the baked article and the outside air A method for producing a zinc sulfide phosphor, comprising placing a copper introduction promoter between the two.
(2) The copper introduction accelerator is composed of any one of zinc sulfide powder, sulfur powder, ammonium chloride powder, or magnesium chloride powder, or a mixture of two or more thereof (1) A method for producing the zinc sulfide phosphor according to 1.
(3) The method for producing zinc sulfide phosphor particles according to (1) or (2), wherein the object to be fired contains 0.05 mol% or more and 0.2 mol% or less of copper.
(4) Zinc sulfide phosphor particles produced by the production method according to any one of (1) to (3).
(5) A dispersion type electroluminescent device comprising the zinc sulfide phosphor particles according to the item (4).

  According to the production method of the present invention, the phosphor particles obtained by the production method can be provided by reducing the coloring of the particle surface and providing phosphor particles introduced in a large amount without segregating copper into the phosphor. Can be used to provide a high-luminance electroluminescent element.

The present invention will be described in detail below.
The present invention is a method for producing a zinc sulfide phosphor basically utilizing a firing method (solid phase method) widely used in the industry.
In general, first, a zinc sulfide fine particle powder (usually referred to as raw powder) of preferably 1 nm to 1 μm, more preferably 5 nm to 500 nm, particularly preferably 10 nm to 200 nm is prepared by a liquid phase method. The particles are used as particles, and an impurity called an activator is mixed therein, and the first baking is performed in a crucible at a high temperature of 900 to 1300 ° C. for 30 minutes to 10 hours together with the flux to obtain particles. The phosphor intermediate powder obtained by the first firing is repeatedly washed with ion-exchanged water to remove alkali metal or alkaline earth metal, excess activator and coactivator. Next, the obtained phosphor intermediate powder is subjected to second baking. 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.

  In the present invention, a copper introduction accelerator is disposed between the zinc sulfide fine particle powder or the phosphor intermediate powder and the outside air in one or both of the first firing and the second firing described above. Firing is performed. In particular, it is preferable to carry out in both the first and second firing steps. In the present specification, the mixture of raw powder and flux in the first firing step and the phosphor intermediate in the second firing step are both referred to as “fired products”. The copper introduction promoter is disposed in a portion between the firing containers and the outside air that are filled with the firing objects of the first and second firing steps.

A preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the description of each drawing, the same elements are denoted by the same reference numerals. FIGS. 1-6 is sectional drawing which shows one embodiment of the baking container for enforcing the method of this invention. The present invention is not limited to the illustrated embodiment.
The embodiment of FIG. 1 uses three types of crucibles, large, medium and small. A copper introduction accelerator 17 is disposed in the large crucible 14, and the object to be fired 16 is placed on the copper accelerator 17. The small crucible 11 placed is covered with a lid 12, the small crucible 11 is covered with an inverted middle crucible 13, and these are covered with a lid 15 and fired.
The embodiment shown in FIG. 2 uses a quartz tube. An object to be fired 22 is disposed in the quartz tube 21, and a copper introduction accelerator 24 is disposed through the quartz wool 23 so as to sandwich the object to be fired 22. Bake.
The embodiment shown in FIGS. 3 to 6 uses one crucible. In FIG. 3, the copper introduction accelerator 34 is placed on the material 33 to be fired, and the crucible 31 is filled with the lid 32. Bake. In the embodiment of FIG. 4, quartz wool 35 is disposed between the object to be fired 33 and the copper introduction accelerator 34 in the embodiment of FIG. 3. In the embodiment shown in FIG. 5, the copper introduction accelerator 34 is also arranged below the material 33 to be fired in the embodiment shown in FIG. 3. In the embodiment shown in FIG. 6, quartz wool 35 is disposed between the object to be fired 33 and the copper introduction accelerator 34 in the embodiment shown in FIG.
The copper introduction promoter may be disposed between the object to be fired and the outside air, and even if it is disposed separately from the object to be fired as shown in FIG. You may arrange | position closely.

After baking, when a to-be-fired thing and a copper introduction | transduction agent are isolate | separated, as shown to FIGS.
As shown in FIGS. 3 and 5, when the object to be fired is in contact with the copper introduction accelerator, a substance having an average particle size different from that of the object to be fired is used as the copper introduction accelerator. After firing, the mixture of the copper introduction accelerator and the object to be fired is stirred in ion-exchanged water and then allowed to settle, and after a certain period of time, the floating particles are decanted and removed to repeat the copper introduction promotion. The agent and the material to be fired can be separated. In this case, as the copper introduction accelerator, it is preferable to use a substance having an average particle size smaller than that of the object to be fired. In order to facilitate separation of both, more preferably, the average particle diameter of the object to be fired is The average particle size of the copper introduction accelerator is 1 μm or less.

  By disposing a copper introduction accelerator, it is possible to form an atmosphere of a copper introduction accelerator and block oxygen to prevent oxidation of the object to be fired. Further, copper is added to the phosphor particles (fired object). Excess copper at the time of introduction can be taken in by the copper introduction accelerator, and coloring of the object to be fired can be prevented. The copper introduction accelerator is preferably composed of any one of zinc sulfide powder, sulfur powder, or magnesium chloride powder, or a mixture of two or more. The amount of the copper introduction accelerator is preferably 1/100 to 1000 times, more preferably 1/50 to 500 times, and particularly preferably 1/10 to 100 times the weight of the object to be fired. The copper introduction accelerator is preferably arranged so that the object to be fired does not come into direct contact with the outside air. The particle size of the copper introduction accelerator is not particularly limited, but particles having a large surface area are more effective, and therefore the particle size is preferably 5 μm or less, more preferably 1 μm or less. In order to reduce the particle size, the raw material powder is preferably used after being pulverized in a mortar or the like. When zinc sulfide powder is used as the copper introduction accelerator, zinc sulfide particles containing an element such as copper can be used as an activator, or zinc sulfide containing no impurities can be used.

  Since the atmosphere of the copper introduction accelerator is formed by the use of the copper introduction accelerator, any firing atmosphere can be used, for example, air, oxygen, nitrogen, argon, helium, hydrogen, hydrogen sulfide, Or a mixed gas thereof can be used, and the use in the air is most preferable.

In the present invention, the object to be fired contains 0.05 mol% or more and less than 1.0 mol%, preferably 0.05 mol% or more and 0.2 mol% or less of copper. As copper, copper compounds soluble in water, such as copper sulfate, copper nitrate, and copper acetate, can be preferably used. Copper may be added either before the first firing step or before the second firing step, or may be added at both times. Since the first baking step has a higher temperature and copper diffuses more uniformly, it is more preferable to add it before the first baking step.
Specifically, for example, when added before the first firing step, the zinc sulfide raw powder is suspended, and when added before the second firing step, the phosphor intermediate powder is suspended in water. An article to be fired can be obtained by preparing a slurry, adding the aqueous solution of the copper compound while stirring the slurry, continuing stirring, and drying.
Also, copper sulfide or the like that is insoluble in water can be used. In this case, firing is performed after mixing the raw material powder and the copper sulfide powder.

In the present invention, the flux is preferably mainly composed of a halide, and more preferably composed mainly of one substance or a mixture of two or more of alkali metal halides, alkaline earth metal halides, and ammonium halides. preferable.
Examples of the alkali metal halide include lithium chloride, lithium bromide, lithium iodide, sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, rubidium chloride, rubidium bromide, and rubidium iodide. Cesium chloride, cesium bromide, cesium iodide and the like.
Alkaline earth metal halides include, for example, magnesium chloride, magnesium bromide, magnesium iodide, calcium chloride, calcium bromide, calcium iodide, strontium chloride, strontium bromide, strontium iodide, barium chloride, barium bromide, Contains barium iodide.
The ammonium halide includes ammonium chloride, ammonium bromide / ammonium iodide, and the like.

  Although many stacking faults are generated in the phosphor particles by the first and second firings described above, the first firing and the second firing are performed so as to include fine particles and more stacking faults in the phosphor particles. It is preferable to select the firing conditions of 2 as appropriate. 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 impact force, a method of contacting and mixing phosphor intermediate particles, 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, etc. It can be preferably used. Thereafter, etching with an acid such as HCl removes the metal oxide adhering to the surface, and the copper sulfide adhering to the surface is removed by washing with KCN and dried to obtain phosphor particles.

  In order to obtain high-luminance electroluminescence, it is preferable that 50% (number) or more of the phosphor particles contain 10 or more stacking fault structures with an interval of 5 nm or less. More preferably, 75% (pieces) of phosphor particles have a stacking fault structure, and more preferably 100% (pieces) of phosphor particles have a stacking fault structure.

  Quantification of stacking faults inside the phosphor particles can be performed by observing with a transmission electron microscope. About 100 mg of phosphor particles to be quantified for stacking faults are suspended in a solvent such as methanol, ethanol, acetone, and pulverized for about 10 minutes in a mortar. When the phosphor particle fragments thus obtained are observed with a transmission electron microscope, the phosphor particle fragments having a stacking fault structure have streak lines in the fragments. On the other hand, particles having no stacking fault structure are observed as a smooth surface having no structure. When counting the streak-like lines, if the number of fragments having 10 or more lines at intervals of 5 nm or less is 50% (pieces) or more, 50% (pieces) or more of the phosphor particles are 5 nm or more. It can be considered that the stacking fault structure having the following interval contains 10 or more layers.

  At the time of observation, a transmission electron microscope having a high acceleration voltage, for example, about 400 kV is preferable because particles can be observed with good contrast. For observation with a transmission electron microscope, it is essential that electrons pass through the sample. Therefore, the phosphor particle fragments need to be pulverized to a thickness of 0.1 nm to 100 nm. A fragment having a thickness of 100 nm or more is not suitable for observation because it cannot be determined whether the fragment has no stacking fault or simply does not transmit electrons.

The phosphor element obtained by the present invention more preferably has a non-light emitting shell layer on the surface of the phosphor particles. The shell layer is preferably formed with a thickness of 0.1 μm or more using a chemical method following the preparation of the semiconductor fine particles serving as the core of the phosphor element. Preferably they are 0.1 micrometer or more and 1.0 micrometer or less.
The non-light emitting shell layer can be formed from an oxide, a nitride, an oxynitride, or a material having the same composition formed on the phosphor base material and containing no emission center. In addition, substances having different compositions can be epitaxially grown on the phosphor matrix material.
As a method for forming the non-light-emitting shell layer, a gas phase method such as laser, ablation method, CVD method, plasma method, sputtering, resistance heating, electron beam method, etc. Sol-gel method, ultrasonic chemistry method, precursor thermal decomposition method, reverse micelle method or combination of these methods with high temperature firing, urea melting method, freeze drying method, liquid phase method or spray pyrolysis method, etc. Can also be used.

In particular, 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 the zinc sulfide phosphor particles, the metal salt serving as the non-light emitting shell layer material is dissolved, and the zinc sulfide phosphor is added to the molten urea solution. 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.

  For example, when a non-light emitting shell layer is attached to the surface of the zinc sulfide phosphor particles by spray pyrolysis, the zinc sulfide phosphor is added to a solution in which a metal salt serving as a 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 oxide, sulfide, or nitride on the surface can be synthesized.

  The production method of the present invention is effective for phosphors of any particle size, but from the viewpoint of luminance, the particle size distribution of the obtained phosphor particles is narrow, and after the phosphor particles are baked It is preferable that the particle size of the is smaller. The average particle diameter after firing of the phosphor particles obtained by the present invention is not particularly limited, but is preferably 0.1 to 25 μm, more preferably 0.1 to 15 μm. Further, the particle size distribution of the phosphor particles obtained by the present invention can be calculated by a coefficient of variation (standard deviation of particle size distribution ÷ average particle size × 100%), preferably less than 35%. Each particle size is expressed in terms of its diameter by converting the volume into a sphere. The particle size may be measured by taking a photograph of the individual particle, the distribution may be measured optically, or the distribution may be determined from the sedimentation velocity.

The electroluminescent element 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, and a dielectric layer is preferably adjacent between the light emitting layer and the electrode.
For the light emitting layer, the phosphor of the present invention dispersed in a dispersant can be used. As the dispersant, 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 and SrTiO _{3 with} these resins. The thickness of the light emitting layer is preferably 0.5 to 50 μm, and more preferably 0.5 to 30 μm.
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 metal oxides are selected from 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.

The light emitting layer and the dielectric layer can be applied using a spin coating method, a dip method, a bar coating method, a screen printing method, a spray coating method, or the like.
The dielectric film may be prepared by a gas phase method such as sputtering or vacuum deposition. In this case, the thickness of the film is usually in the range of 100 to 1000 nm.
In the electroluminescent element, any transparent electrode material that is generally used is used as the transparent electrode. Examples thereof include oxides such as indium-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.
The electroluminescence element is preferably processed so as to eliminate the influence of humidity from the external environment by finally using an appropriate sealing material. 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.

  The use of the electroluminescence element preferably using the electroluminescence phosphor obtained by the present invention is not particularly limited, but considering the use as a light source, the emission color is preferably white. As a method for changing the emission color to white, it is preferable to mix a plurality of emission color phosphors in the emission layer of the electroluminescence element (blue-green-red combination, blue-green-orange combination, etc.).

It is also preferable to emit light at a short wavelength, such as blue, and to convert the wavelength of part of the emitted light to green or red to whiten.
In addition, in the structure of the electroluminescent element using the electroluminescent phosphor manufactured by the manufacturing method 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 are provided as necessary. be able to. 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.

  The phosphor particles obtained in the present invention are preferably combined with the above-described electroluminescence element configuration as appropriate, thereby providing a high-luminance and high-efficiency electroluminescence element.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these.

Example 1
ZnS raw powder (average grain) in which water was added to 150 g of ZnS (manufactured by Furuuchi Chemical Co., Ltd., purity 99.999%) to form a slurry, an aqueous solution containing 0.416 g of CuSO ₄ .5H ₂ O was added, and copper was partially substituted. 100 nm in diameter) was obtained. To 25 g of the obtained raw flour, NaCl
1.0 g, BaCl ₂ · 2H ₂ O
2.1g, MgCl ₂ · 6H ₂ O
4.2 g was mixed, filled in the triple crucible (made of alumina) shown in FIG. 1 and fired at 1200 ° C. for 4 hours to obtain a phosphor intermediate (first firing step). The particles were washed with ion exchange water 10 times and dried. 50 g of 0.5 mmφ alumina beads were mixed with 5 g of the obtained intermediate and subjected to a ball mill for 40 minutes. This was filled in the triple crucible shown in FIG. 1 and annealed in air at 700 ° C. for 6 hours (second firing step). The obtained phosphor particles were washed with a 10% KCN aqueous solution to remove excess copper (copper sulfide) on the surface, and then washed with water 5 times to obtain electroluminescent phosphor particles (average particle size 25 μm). , Particle size variation coefficient 48%).
However, in the first and second firing steps, the type and amount of the copper introduction accelerator were changed as shown in Table 1 to produce phosphor particles. Examples of the copper introduction accelerator include zinc sulfide (manufactured by Furuuchi Chemical, average particle size 100 nm), sulfur powder (manufactured by Wako Pure Chemical Industries, pulverized to an average particle size of 1 μm or less with a mortar), magnesium chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) And ammonium chloride (manufactured by Wako Pure Chemical Industries, Ltd., pulverized to an average particle size of 1 μm or less with a mortar) were used.

Comparative Example 1
Firing was performed in the same manner as in Example 1 except that the copper introduction accelerator was not used in either the first firing step or the second firing step.

Example 2
A phosphor intermediate was obtained in the same manner as in Example 1 (first firing step). The particles were washed with ion exchange water 10 times and dried. The obtained intermediate was filled in the quartz tube shown in FIG. 2, and annealed at 700 ° C. for 6 hours in a nitrogen flow using a copper introduction accelerator (second firing step). The obtained phosphor particles were washed with a 10% aqueous KCN solution to remove excess copper (copper sulfide) on the surface, and then washed with water five times to obtain electroluminescent phosphor particles. However, in the first and second firing steps, the amount of the copper introduction accelerator was changed as shown in Table 1 to produce phosphor particles.

Comparative Example 2
Firing was performed in the same manner as in Example 2 except that the copper introduction accelerator was not used in either the first firing step or the second firing step.

(Production of electroluminescence element)
Using the obtained phosphor particles, an element was produced as follows.
The phosphor particles obtained above are dispersed in 30 wt% of a DMF solution of Shin-Etsu Chemical's cyanoresin CR-S (trade name), and this is deposited on an ITO-deposited PET base so that the film thickness becomes 30 μm. It was applied and dried at 80 ° C. for 4 hours. Thereafter, barium titanate powder BT-02 (trade name) manufactured by Sakai Chemical was dispersed in the same 30 wt% cyanoresin, applied from above the phosphor layer, and dried at 80 ° C. for 4 hours. Aluminum was evaporated from above to produce an electroluminescence element. The produced element was driven by an AC power supply of 100 V and 1 kHz, and the luminance was evaluated by a luminance meter BM-9 (trade name) manufactured by TOPCOM. All were evaluated by relative evaluation when the result of the phosphor 6 (Comparative Example 1) was set to 100. Table 2 shows the results.

  Moreover, the copper introduction promoting effect of the present invention was evaluated by whether or not the particles were colored using the light absorption rate of the phosphor particles. The light absorption rate of the phosphor particles is determined by dispersing the phosphor particles in a DMF solution of the above cyanoresin CR-S (trade name) and applying it to a 5 mm square non-alkali glass so that the film thickness is 50 μm. It was evaluated. The spectroscope radiated 600 nm light and irradiated the sample, and using an integrating sphere, the reflectance and transmittance of the glass coating were obtained and subtracted from 1 to use the absorptivity. Since 600 nm is light absorption regardless of the light emission process of ZnS: Cu, Cl, coloring of the phosphor particles can be seen with some amount of light absorption.

  As is apparent from Table 2, when phosphors 1 to 6, 10 using a copper introduction accelerator are used in the element in both the first and second firing steps, the coloring of the element is reduced and the brightness is remarkably increased. It was found that In particular, the effects were significant in the phosphors 2 and 3 having a large total amount of the copper introduction accelerator. In addition, it was found that the luminance was improved in the phosphors 7, 8, 11 and 12 using the copper introduction accelerator only in either the first or second firing step as compared with Comparative Examples 1 and 2. .

Example 3 and Comparative Example 3
ZnS raw powder (average grain) in which water was added to 150 g of ZnS (manufactured by Furuuchi Chemical Co., Ltd., purity 99.999%) to form a slurry, an aqueous solution containing 0.416 g of CuSO ₄ .5H ₂ O was added, and copper was partially substituted. 100 nm in diameter) was obtained. To 25 g of the obtained raw flour, NaCl
6.0 g, BaCl ₂ · 2H ₂ O
12.6g, MgCl ₂ · 6H ₂ O
25.5 g was mixed, filled in the triple crucible (made of alumina) shown in FIG. 1 and fired at 1200 ° C. for 4 hours to obtain a phosphor intermediate (first firing step). The particles were washed with ion exchange water 10 times and dried. 50 g of 0.5 mmφ alumina beads were mixed with 5 g of the obtained intermediate and subjected to a ball mill for 40 minutes. This was filled in the triple crucible shown in FIG. 1 and annealed in air at 700 ° C. for 6 hours (second firing step). The obtained phosphor particles were washed with a 10% KCN aqueous solution to remove excess copper (copper sulfide) on the surface, and then washed with water five times to obtain electroluminescent phosphor particles (particle diameter 16 μm, coefficient of variation 42). %).
However, in the first and second firing steps, the type and amount of the copper introduction accelerator were changed as shown in Table 3 to produce phosphor particles. As the copper introduction accelerator, zinc sulfide (manufactured by Furuuchi Chemical, average particle size of 100 nm) was used.
Using the obtained phosphor particles, an electroluminescence element was produced in the same manner as in Example 1, and the relative luminance was evaluated. Table 3 shows the results.

Example 4 and Comparative Example 4
ZnS raw powder (average grain) in which water was added to 150 g of ZnS (manufactured by Furuuchi Chemical Co., Ltd., purity 99.999%) to form a slurry, an aqueous solution containing 0.416 g of CuSO ₄ .5H ₂ O was added, and copper was partially substituted. 100 nm in diameter) was obtained. To the resulting raw powder _{25g, BaCl 2 · 2H 2 O} 4.2g, MgCl 2 · 6H 2 O 11.1g, as a mixture of _{SrCl 2 · 6H 2 O 27.3g,} 3 double crucible shown in FIG. 1 Filled (made of alumina) and baked at 1200 ° C. for 4 hours to obtain a phosphor intermediate (first baking step). The particles were washed with ion exchange water 10 times and dried. 50 g of 0.5 mmφ alumina beads were mixed with 5 g of the obtained intermediate and subjected to a ball mill for 40 minutes. This was filled in the triple crucible shown in FIG. 1 and annealed in air at 700 ° C. for 6 hours (second firing step). The obtained phosphor particles were washed with 10% KCN aqueous solution to remove excess copper (copper sulfide) on the surface and then washed with water five times to obtain electroluminescent phosphor particles (particle size 14 μm, variation coefficient 34). %).
However, in the first and second firing steps, the type and amount of the copper introduction accelerator were changed as shown in Table 4 to produce phosphor particles. As the copper introduction accelerator, zinc sulfide (manufactured by Furuuchi Chemical, average particle size of 100 nm) was used.
Using the obtained phosphor particles, an electroluminescence element was produced in the same manner as in Example 1, and the relative luminance was evaluated. Table 4 shows the results.

Comparative Example 5
Example 1 except that water was added to 0.2 mol of ZnS to form a slurry, and an aqueous solution containing 0.00003 mol of CuSO ₄ .5H ₂ O was added to produce a ZnS raw powder partially substituted with copper. In the same manner as above, an electroluminescent phosphor was prepared, and an electroluminescent element was manufactured using the same. When the luminance of the element was measured in the same manner as in Example 1, the EL luminance could not be measured.
From this result, it was found that EL luminance could not be obtained when the amount of copper added was less than 0.05 mol%.

It is sectional drawing which shows one embodiment of the baking container for enforcing the method of this invention, and uses three types of large, medium, and small crucibles. It is sectional drawing which shows one embodiment of the baking container for enforcing the method of this invention, and uses a quartz tube. It is sectional drawing which shows one embodiment of the baking container for enforcing the method of this invention, and uses one crucible. It is sectional drawing which shows one embodiment of the baking container for enforcing the method of this invention, and has arrange | positioned quartz wool 35 between the to-be-baked material 33 and the copper introduction | transduction promoter 34 using one crucible. is there. It is sectional drawing which shows one embodiment of the baking container for enforcing the method of this invention, and uses one crucible. It is sectional drawing which shows one embodiment of the baking container for enforcing the method of this invention, and has arrange | positioned quartz wool 35 between the to-be-baked material 33 and the copper introduction | transduction promoter 34 using one crucible. is there.

Explanation of symbols

11 Small crucible 12 Small crucible cover 13 Medium crucible 14 Large crucible 15 Large crucible cover 16, 22, 33 Products to be fired 17, 24, 34 Copper introduction accelerator 21 Quartz tube 23, 35 Quartz wool 31 Crucible 32 Crucible cover

Claims (5)

  A method for producing a zinc sulfide phosphor in which zinc sulfide activated with copper is fired, wherein the fired material contains copper in an amount of 0.05 mol% or more and less than 1.0 mol%, and between the fired material and the outside air. A method for producing a zinc sulfide phosphor, comprising arranging a copper introduction promoter in   2. The sulfide according to claim 1, wherein the copper introduction accelerator is composed of any one of zinc sulfide powder, sulfur powder, ammonium chloride powder, or magnesium chloride powder, or a mixture of two or more thereof. A method for producing a zinc phosphor.   The method for producing zinc sulfide phosphor particles according to claim 1 or 2, wherein the object to be fired contains 0.05 mol% or more and 0.2 mol% or less of copper.   The zinc sulfide fluorescent substance particle produced with the manufacturing method of any one of Claims 1-3. A dispersion type electroluminescent device comprising the zinc sulfide phosphor particles according to claim 4.

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