JP2007106832A - Method for producing phosphor and the phosphor produced by the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing phosphor fine particles having a narrow particle diameter distribution and a high brightness, and the phosphor fine particles produced by the method. <P>SOLUTION: This method for producing the phosphor, forming a precursor of the phosphor by a liquid phase method, then forming liquid droplet state suspension containing the precursor, drying and heating to form the phosphor is characterized with that the precursor has an amorphous structure and the changing rate of the component ratio of each of the main constituting elements of the precursor and phosphor is ≤5%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a phosphor and a fine particle phosphor produced by the method.

  Phosphors are materials that convert the energy of excitation rays into light (ultraviolet rays, visible light, infrared rays, etc.) by irradiating excitation rays (ultraviolet rays, visible light, infrared rays, heat rays, electron rays, X-rays, etc.). As commonly used. Examples of the device using the phosphor include a fluorescent lamp, an electron tube, a cold cathode display, a fluorescent display tube, a plasma display panel (hereinafter also referred to as “PDP”), an electroluminescence panel, a scintillation detector, An X-ray image intensifier, a thermofluorescence dosimeter, an imaging plate, etc. are mentioned (for example, refer nonpatent literature 1). Each of these devices is a device that converts electrical energy into excitation ray energy and further converts excitation ray energy into light. An electronic device in which such a device is combined with an electronic circuit or a device component (such as a lighting device, a computer, a keyboard, and an electronic device that does not use a phosphor) is widely used as a lighting device or a display device.

  In addition, as a phosphor-using article using a phosphor, a phosphor in which a powdery phosphor is combined with a substance other than the phosphor, such as a liquid such as water or an organic solvent, a resin, a plastic, a metal, or a ceramic material. These include, for example, liquids and pastes such as phosphor paints, solids such as ashtrays, display materials such as guide plates and guidance articles, seals, stationery, outdoor products, safety signs, etc. Widely used.

  Furthermore, not only the above-mentioned uses but also progress in utilization in the medical field and bio field such as use as a tracer is expected.

  As a method for manufacturing the phosphor, a solid phase method in which a predetermined amount of a compound containing an element constituting the phosphor matrix and a compound containing an activator element are mixed and baked to perform an inter-solid reaction, and a phosphor matrix are constructed. There is a liquid phase method in which a solution containing an element and a solution containing an activator element are mixed to form a precipitate of a phosphor precursor in the solution, and the precursor is solid-liquid separated and then fired.

  In order to increase the yield and luminous efficiency of the phosphor, it is necessary to make the phosphor composition as close to the stoichiometric composition as possible. In the solid-phase method, it is difficult to produce a phosphor having a purely stoichiometric composition. As a result of reaction between solids, excess impurities that do not react and by-products generated by the reaction remain, resulting in stoichiometrically. It is difficult to obtain a high-purity phosphor. Due to the effect that such impurities cannot be burned sufficiently, there are disadvantages such as a decrease in emission intensity, discoloration of the phosphor, uneven firing, etc., and there is a large variation in the emission intensity depending on the firing lot.

  The liquid phase method is more suitable than the solid phase method to obtain a compositionally uniform and high-purity fine particle phosphor.

  When manufacturing a phosphor by a liquid phase method, first, a precipitate which is a precursor of the phosphor is generated and baked to obtain a phosphor. The characteristics of the phosphor such as particle size distribution and emission characteristics are as follows. It depends greatly on the properties of the precursor. Therefore, it is necessary to consider the control of the particle size distribution of the precursor and the exclusion of impurities.

  As a method for improving the particle size distribution of the precursor, a method is known in which a solution or suspension containing a phosphor component is thermally decomposed into droplets (see, for example, Patent Documents 1 and 2). ).

  On the other hand, since II-VI group semiconductor nanoparticles can obtain better light absorption and emission characteristics than the bulk crystal structure, research reports have been actively made in recent years. The excellent optical properties of the semiconductor nanoparticles are thought to be due to the fact that the crystal grain size is as small as nanometers, which increases the band gap and manifests the quantum size effect.

  Here, the nanoparticle means a crystal grain having a particle diameter of about 1 nm to 100 nm, and is generally called a nanocrystal.

In recent years, there have been many reports on ZnS nanoparticles and doped ZnS: Mn ²⁺ nanoparticles produced by using a precipitation technique as an example of nanoparticle phosphors (for example, Patent Documents 3 and 4). reference.). In addition, it has been reported that emission intensity is increased by adding an organic acid such as acrylic acid during a liquid phase reaction utilizing coprecipitation to synthesize a nanoparticle phosphor (Patent Documents 5 and 6). reference.).
JP 2003-261867 A JP 2004-277543 A JP 2002-322468 A JP 2005-239775 A Japanese Patent Laid-Open No. 10-310770 JP 2000-104058 A “Phosphor Handbook” edited by Phosphors Society, Ohmsha, 1987

  Although some of the effects of the method for improving the particle size distribution of the precursor disclosed in the above-mentioned patent document are recognized, it cannot be said to be sufficient yet, and further improvements are required.

  In particular, when trying to reduce the particle size of the phosphor to the nano size for the purpose of high definition, the surface energy of the particles becomes larger and the particles tend to aggregate, so the dispersibility is deteriorated and the particle size distribution is also deteriorated. .

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a method for producing a fine phosphor having a narrow particle size distribution and a high luminance, and a fine particle phosphor produced by the method.

  The above object of the present invention is achieved by the following configurations.

  1. In a method for manufacturing a phosphor, a precursor of a phosphor is formed by a liquid phase method, and then a suspension containing the precursor is formed into droplets and dried and heated to form the phosphor. Has a amorphous structure, and the rate of change in the composition ratio of each of the main constituent elements of the precursor and the phosphor is 5% or less.

  2. 2. The method for producing a phosphor according to 1 above, wherein an average particle diameter of the phosphor is 1 nm or more and 100 nm or less.

  3. A phosphor formed by drying and heating a suspension containing a precursor of the phosphor in the form of droplets, and the rate of change in the composition ratio of each of the main constituent elements of the precursor and the phosphor is A phosphor characterized by being 5% or less.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for producing a fine phosphor having a narrow particle size distribution and a high luminance, and a fine particle phosphor produced by the method.

  Hereinafter, the present invention and its components will be described in detail.

  First, a typical method for producing a phosphor by the liquid phase method of the present invention will be described.

  The phosphor basically includes (A) a precursor formation step in which a solution containing a constituent metal element of an inorganic phosphor is mixed to form a precursor of the inorganic phosphor, and (B) a sub-step from the phosphor precursor. A desalting step for removing impurities such as salt, (C) a drying step for drying the precursor obtained by the precursor forming step after the precursor forming step, and (D) a dried precursor after the drying step. And a phosphor forming step of firing to form a phosphor.

  The present invention is characterized by including a firing step of obtaining phosphor particles by drying and heating the precursor obtained in the precursor formation step into droplets. Moreover, you may include the etching process of performing an etching process on the surface of the fluorescent substance particle obtained in the baking process, and removing an impurity.

  Here, the “precursor” of the phosphor according to the present invention is a crystal deposited from a mixed solution in the manufacturing method, and is not subjected to a baking treatment at a high temperature or the like, and is predetermined. It means a crystal in a state that hardly shows the light-emitting property of the wavelength.

  Below, each said process which comprises the manufacturing method of fluorescent substance is demonstrated.

(Precursor formation step)
In the precursor forming step according to the present invention, a precursor is synthesized by a liquid phase method (also referred to as “liquid phase synthesis method”).

  The liquid phase method is a method for producing (synthesizing) a precursor in the presence of a liquid or in a liquid. In the liquid phase method, since the phosphor raw material is reacted in the liquid phase, a reaction between element ions constituting the phosphor is performed, and a stoichiometrically high purity phosphor is easily obtained. Compared with the solid phase method in which the phosphor is produced while repeating the solid phase reaction and the pulverization step, particles having a small particle size can be obtained without performing the pulverization step. It is possible to prevent lattice defects in the crystal and prevent a decrease in light emission efficiency.

  In addition, as the liquid phase method in the present embodiment, a general crystallization method represented by cooling crystallization or a sol-gel method is used, but a reaction crystallization method can be particularly preferably used.

A method for producing a precursor of an inorganic phosphor by a sol-gel method generally includes, for example, Si (OCH ₃ ) ₄ or Eu ³⁺ (CH ₃ COCHCOCH ₃ ) ₃ as a matrix, activator or coactivator. metal alkoxides, Al (OC ₄ H _{9) 3} 2-butanol solution make by adding metal magnesium _{Mg [Al (OC 4 H 9} ) 3] the elemental metal addition to metal complexes or their organic solvent solution of ₂ such as This means a production method by mixing required amounts of double alkoxide, metal halide, metal salt of organic acid or simple metal, and thermally or chemically polycondensing them.

  A method for producing a precursor of an inorganic phosphor by a reaction crystallization method is to use a crystallization phenomenon to mix a solution or source gas containing an element as a phosphor raw material in a liquid phase or a gas phase. This is a method for producing a precursor by the above method. Here, the crystallization phenomenon refers to a change in physical or chemical environment due to cooling, evaporation, pH adjustment, concentration, etc., or a change in the state of the mixed system due to a chemical reaction, etc. In the reaction crystallization method, it means a production method by physical and chemical operations resulting from the occurrence of such a crystallization phenomenon.

  In addition, any solvent can be used as the solvent for applying the reaction crystallization method as long as the reaction raw material is dissolved, but water is preferable from the viewpoint of easy control over the degree of supersaturation. Moreover, when using a some reaction raw material, the order which adds a raw material may be simultaneous or different, and it is possible to select a suitable order suitably according to activity.

  Furthermore, in the formation of the precursor, in order to produce a phosphor with a finer particle size and a narrow particle size range, two or more raw material solutions, including a reaction crystallization method, are placed in a poor solvent in the presence of a protective colloid. It is preferable to add them in the middle. Moreover, it is more preferable to adjust various physical properties such as the temperature during the reaction, the addition rate, the stirring rate, and the pH depending on the type of the phosphor, and ultrasonic waves may be irradiated during the reaction. A surfactant or polymer may be added to control the particle size. It is also a preferred embodiment that the liquid is concentrated and / or aged as necessary after the addition of the raw materials.

  The protective colloid functions to prevent aggregation of the finely divided precursor particles, and various polymer compounds can be used regardless of natural or artificial, and among them, proteins can be preferably used.

  Examples of the protein include gelatin, water-soluble protein, and water-soluble glycoprotein. Specific examples include albumin, ovalbumin, casein, soy protein, synthetic protein, and genetically synthesized protein.

  Examples of gelatin include lime-processed gelatin and acid-processed gelatin, and these may be used in combination. Furthermore, a hydrolyzate of these gelatins and an enzyme degradation product of these gelatins may be used.

  The protective colloid need not have a single composition, and various binders may be mixed. Specifically, for example, a graft polymer of the above gelatin and another polymer can be used.

  The average molecular weight of the protective colloid is preferably 10,000 or more, more preferably 10,000 to 300,000, and particularly preferably 10,000 to 30,000. The protective colloid can be added to one or more of the raw material solutions, and may be added to all of the raw material solutions. Depending on the amount of protective colloid added and the addition rate of the reaction liquid, the particle size of the precursor may be added. Can be controlled.

  In addition, since various properties of the phosphor, such as the particle size, particle size distribution, and emission characteristics of the phosphor particles after firing, are greatly influenced by the properties of the precursor, the particle size control of the precursor is performed in the precursor formation process. It is preferable to make the precursor sufficiently small by performing the above. In addition, when the precursor is microparticulated, aggregation between the precursors is likely to occur, so it is extremely effective to synthesize the precursor after preventing aggregation between the precursors by adding a protective colloid, Particle size control becomes easy. When the reaction is carried out in the presence of a protective colloid, it is necessary to give sufficient consideration to the control of the particle size distribution of the precursor and the exclusion of impurities such as secondary salts.

  In the present invention, the transmittance for visible light having a wavelength of 550 nm of a suspension (including a dispersion) containing a precursor obtained by a liquid phase method is 0.1% or more and 90% or less. It is preferable. Furthermore, it is preferably 0.1% to 80%, more preferably 0.1% to 60%.

  The transmittance of visible light having a wavelength of 550 nm after standing for 1 hour in the suspension of the precursor is preferably 0.1% or more and 10% or less with respect to the initial standing. Furthermore, it is preferably 0.1% or more and 5% or less, more preferably 0.1% or more and 3% or less.

  The precursor of the present invention needs to have an amorphous structure. Here, the “amorphous structure” means that it is amorphous and does not have a clear crystal structure, that is, it is amorphous.

  By firing a precursor having an amorphous structure, a phosphor having a uniform internal composition and high luminous efficiency can be obtained.

  The crystal structure of the obtained precursor is analyzed by powder X-ray diffraction measurement. If the precursor has an amorphous structure, a clear diffraction peak cannot be obtained.

(Desalting step)
After synthesizing the phosphor precursor in the phosphor precursor forming step, it is preferable to remove impurities such as by-salt from the phosphor precursor by performing a desalting step prior to the drying step and the firing step. Desalting may be performed from the start to the end of precursor formation, or desalting may be performed at the end of precursor formation. Moreover, depending on the reaction degree of a raw material, it may be given for the fixed time in the middle of precursor formation, and may be given several times.

  There is no particular limitation on the desalting method, and any method can be applied. For example, a precipitation desalting method, an electrodialysis method, various membrane separation methods, and a centrifugal separation method are preferably applied, and it is particularly desirable to perform an ultrafiltration treatment.

  As the desalting step, various membrane separation methods, coagulation sedimentation methods, electrodialysis methods, methods using ion exchange resins, Nudelle washing methods, and the like can be applied.

  By conducting the desalting step, the electrical conductivity after desalting of the precursor is preferably in the range of 0.01 to 20 mS / cm, more preferably 0.01 to 10 mS / cm, and particularly preferably 0. 0.01 to 5 mS / cm.

  When the electrical conductivity is less than 0.01 mS / cm, the productivity is lowered. On the other hand, if it exceeds 20 mS / cm, the secondary salt and impurities are not sufficiently removed, so that the coarsening of the particles and the particle size distribution become wide, and the emission intensity deteriorates. Any method can be used as the method for measuring the electrical conductivity, but a commercially available electrical conductivity measuring device may be used. Thereafter, the precursor is recovered by a method such as filtration, evaporation to dryness, and centrifugation.

(Drying and firing process)
The present invention is characterized in that a precursor suspension (including a dispersion) obtained by a liquid phase method is sprayed as fine droplets in a gas atmosphere and dried and heated. At this time, the precursor may be once dried and then sprayed. In the present invention, it is more preferable to spray the precursor suspension after performing wet dispersion treatment.

  As a method of forming a minute droplet, for example, a method of forming a droplet of 1 to 50 μm by spraying a liquid while sucking a liquid with pressurized air, or 4 to 4 using an ultrasonic wave of about 2 MHz from a piezoelectric crystal. A method of forming a 10 μm droplet, a method of vibrating an orifice having a pore diameter of 10 to 20 μm with a vibrator, dropping it at a constant speed, and forming a 20 to 100 μm droplet by centrifugal force, For example, a method of generating a droplet of 0.5 to 10 μm by applying a high voltage can be used.

  The droplets formed by the method as described above are then introduced into a pyrolysis reactor together with a carrier gas, dried and heated to become a phosphor. In order to obtain the type of phosphor and desired characteristics, the type of solvent, the type of carrier gas, the carrier gas flow rate, and the temperature in the pyrolysis reactor can be selected as necessary. For example, the droplet heat treatment step uses a carrier gas such as air, nitrogen, helium, argon or hydrogen, and is heated at an optimum flow rate in the flow path in the pyrolysis reactor. By setting the temperature in the pyrolysis reactor so that the temperature can be controlled, the size / distribution and crystallinity of the fine particles targeted by the present invention can be controlled.

  In the present invention, the solvent is preferably water or a low-boiling organic solvent having a boiling point equal to or lower than water. For example, alcohols such as ethanol and methanol are preferably used. Further, a mixed solvent of water and a low boiling point solvent may be used.

  In the present invention, the gas atmosphere for spraying the precursor-containing droplets is not particularly limited, and may be any of an oxidizing atmosphere, a reducing atmosphere, or an inert atmosphere, and contributes to the type of phosphor main phase and light emission. It selects suitably according to the kind of activator ion. For example, when a phosphor having an oxide as a main phase is synthesized, air, oxygen, nitrogen, hydrogen, nitrogen containing a small amount of hydrogen, or argon is preferable.

On the other hand, when synthesizing a phosphor having sulfide or oxysulfide as the main phase, nitrogen, hydrogen, nitrogen or argon containing a small amount of hydrogen, nitrogen containing hydrogen sulfide or carbon dioxide, hydrogen or argon, etc. are preferable. . Also, when the maintaining valency easily Eu ³⁺ and the like in an oxidizing atmosphere and activating ions, and preferably an oxidizing gas such as air or oxygen, maintaining the valence easily Eu ³⁺ and the like in a reducing atmosphere activator ions In this case, a reducing gas such as hydrogen, nitrogen containing a small amount of hydrogen, or argon is preferable.

  In the present invention, the temperature in the thermal decomposition reactor when spraying the precursor droplets is a temperature within the range of 600 ° C to 1900 ° C. If the temperature is too low, crystallization does not proceed sufficiently, and if the temperature is too high, unnecessary energy is consumed, which is not preferable in terms of cost. The residence time in the furnace is preferably 1 second or more and 24 hours or less. If the residence time is too short, crystallization does not proceed sufficiently, and if the residence time is too long, unnecessary energy is consumed, which is not preferable in terms of cost.

  Moreover, you may add a sintering inhibitor as needed. Of course, it is not necessary to add when there is no need to add. When a sintering inhibitor is added, it may be added as a slurry at the time of precursor formation, or a powdery sintering inhibitor may be added.

The sintering inhibitor is not particularly limited, and is appropriately selected depending on the type of phosphor and firing conditions. For example, depending on the firing temperature range of the phosphor, a metal oxide such as TiO ₂ is used for baking at 800 ° C. or lower, SiO ₂ is used for baking at 1000 ° C. or lower, and Al ₂ O ₃ is used for baking at 1700 ° C. or lower. Are preferably used. Therefore, in the present invention, it is preferable to use Al ₂ O ₃ .

(surface treatment)
The phosphor produced in the present invention can be subjected to surface treatment such as adsorption and coating for various purposes. The point at which the surface treatment is performed depends on the purpose, and the effect becomes more prominent when appropriately selected. For example, when the surface of the phosphor is coated with an oxide containing at least one element selected from Si, Ti, Al, Zr, Zn, In, and Sn at any point before the dispersion treatment process, The decrease in the crystallinity of the phosphor can be suppressed, and the decrease in the emission intensity can be suppressed by preventing the excitation energy from being captured by the surface defects of the phosphor. Moreover, when the surface of the phosphor is coated with an organic polymer compound or the like at any point after the dispersion treatment step, characteristics such as weather resistance are improved, and a phosphor having excellent durability can be obtained. The thickness and coverage of the coating layer when these surface treatments are performed can be arbitrarily controlled as appropriate.

  In the present invention, the change rate of the composition ratio of each of the main constituent elements of the precursor and the phosphor is required to be 0% or more and 5% or less. Preferably they are 0% or more and 3% or less, More preferably, they are 0% or more and 1% or less.

  The average particle size of the phosphor according to the present invention is preferably 1 nm or more and 100 nm or less. Preferably they are 1 nm or more and 70 nm or less, More preferably, they are 1 nm or more and 50 nm or less. The particle diameter shown here refers to the length of the twill of a particle when the particle is a cubic or octahedral so-called normal crystal. Moreover, when it is not a normal crystal, for example, in the case of a spherical shape, a rod shape, or a flat shape, it means a diameter when a sphere equivalent to the volume of the particle is considered.

  When the average particle size of the phosphor is r and the standard deviation in the particle size distribution is σ, σ / r is 0.5 or less, preferably 0.4 or less, more preferably 0.3 or less.

  In the production method of the present invention, phosphors having various compositions can be produced. Specific examples of the inorganic phosphor according to the present invention are shown below, but the application of the production method of the present invention is not limited thereto.

[Blue light emitting phosphor compound]
(BL-1): Sr ₂ P ₂ O ₇ : Sn ⁴⁺
(BL-2): Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺
(BL-3): BaMgAl ₁₀ O ₁₇ : Eu ²⁺
(BL-4): SrGa ₂ S ₄ : Ce ³⁺
(BL-5): CaGa ₂ S ₄ : Ce ³⁺
(BL-6): (Ba, Sr) (Mg, Mn) Al ₁₀ O ₁₇ : Eu ²⁺
(BL-7): (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) 6Cl ₂ : Eu ²⁺
(BL-8): ZnS: Ag
(BL-9): CaWO ₄
(BL-10): Y ₂ SiO ₅ : Ce
(BL-11): ZnS: Ag, Ga, Cl
(BL-12): Ca ₂ B ₅ O ₉ Cl: Eu ²⁺
(BL-13): BaMgAl ₁₄ O ₂₃ : Eu ²⁺
(BL-14): BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Tb ³⁺ , Sm ²⁺
(BL-15): BaMgAl ₁₄ O ₂₃ : Sm ²⁺
(BL-16): Ba ₂ Mg ₂ Al ₁₂ O ₂₂ : Eu ²⁺
(BL-17): Ba ₂ Mg ₄ Al ₈ O ₁₈ : Eu ²⁺
(BL-18): Ba ₃ Mg ₅ Al ₁₈ O ₃₅ : Eu ²⁺
(BL-19): (Ba, Sr, Ca) (Mg, Zn, Mn) Al ₁₀ O ₁₇ : Eu ²⁺
[Green light-emitting phosphor compound]
(GL-1): (Ba, Mg) Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺
(GL-2): Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺
(GL-3): (Sr, Ba) Al ₂ Si ₂ O ₈ : Eu ²⁺
(GL-4): (Ba, Mg) ₂ SiO ₄ : Eu ²⁺
(GL-5): Y ₂ SiO ₅ : Ce ³⁺ , Tb ³⁺
(GL-6): Sr ₂ P ₂ O ₇ —Sr ₂ B ₂ O ₅ : Eu ²⁺
(GL-7): (Ba, Ca, Mg) ₅ (PO ₄ ) ₃ Cl: Eu ²⁺
(GL-8): Sr ₂ Si ₃ O ₈ -2SrCl ₂ : Eu ²⁺
(GL-9): Zr ₂ SiO ₄ , MgAl ₁₁ O ₁₉ : Ce ³⁺ , Tb ³⁺
(GL-10): Ba ₂ SiO ₄ : Eu ²⁺
(GL-11): ZnS: Cu, Al
(GL-12): (Zn, Cd) S: Cu, Al
(GL-13): ZnS: Cu, Au, Al
(GL-14): Zn ₂ SiO ₄ : Mn ²⁺
(GL-15): ZnS: Ag, Cu
(GL-16) :( Zn, Cd) S: Cu
(GL-17): ZnS: Cu
(GL-18): Gd ₂ O ₂ S: Tb
(GL-19): La ₂ O ₂ S: Tb
(GL-20): Y ₂ SiO ₅ : Ce, Tb
(GL-21): Zn ₂ GeO ₄ : Mn
_{(GL-22): CeMgAl 11} O 19: Tb
(GL-23): SrGa ₂ S ₄ : Eu ²⁺
(GL-24): ZnS: Cu, Co
(GL-25): MgO.nB ₂ O ₃ : Ce, Tb
(GL-26): LaOBr: Tb, Tm
(GL-27): La ₂ O ₂ S: Tb
(GL-28): SrGa ₂ S ₄ : Eu ²⁺ , Tb ³⁺ , Sm ²⁺
[Red-emitting phosphor compound]
(RL-1): Y ₂ O ₂ S: Eu ³⁺
(RL-2): (Ba, Mg) ₂ SiO ₄ : Eu ³⁺
(RL-3): Ca ₂ Y ₈ (SiO ₄ ) ₆ O ₂ : Eu ³⁺
(RL-4): LiY ₉ (SiO ₄ ) ₆ O ₂ : Eu ³⁺
(RL-5): (Ba, Mg) Al ₁₆ O ₂₇ : Eu ³⁺
(RL-6): (Ba, Ca, Mg) ₅ (PO ₄ ) ₃ Cl: Eu ³⁺
(RL-7): YVO ₄ : Eu ³⁺
_{(RL-8): YVO 4} : Eu 3+, Bi 3+
(RL-9): CaS: Eu ³⁺
(RL-10): Y ₂ O ₃ : Eu ³⁺
(RL-11): 3.5MgO, 0.5MgF ₂ GeO ₂ : Mn
(RL-12): YAlO ₃ : Eu ³⁺
(RL-13): YBO ₃ : Eu ³⁺
(RL-14) :( Y, Gd) BO ₃ : Eu ³⁺
The fine particle phosphor according to the present invention, particularly the nano-sized phosphor, can be used for various purposes and applications as described in the “Background Art” section.

  For example, when a fine particle or nanoparticle phosphor of 100 nm or less is used in the form of a coating film, a coating method using an inkjet nozzle can be used. Conventional phosphors with a size of several μm are likely to be clogged with nozzles, and the nozzle diameter needs to be adjusted to the size of the phosphor, which is unsuitable for applying fine patterns. By applying the nanoparticles using an inkjet nozzle having a small nozzle diameter, a fine pattern can be applied.

  Examples of such application applications include the production of fluorescent panels such as PDP / FPD, and the production of fluorescent ink prints (posters, signboards, T-shirts, etc.) using nanoparticles.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to this.

Theoretically, the following seven phosphors represented by the composition formula: Zn ₂ SiO ₄ : Mn ²⁺ were prepared.

(Preparation of phosphor 1)
Liquid A was prepared by mixing 219 g of colloidal silica containing 45 g of silicon dioxide (PL-3 manufactured by Fuso Chemical Industry Co., Ltd.) and 219 g of aqueous ammonia (28%) with pure water to adjust the liquid volume to 1500 ml. Simultaneously, 424 g of zinc nitrate hexahydrate (Kanto Chemical Co., Ltd., purity 99.0%) and 21.5 g of manganese nitrate hexahydrate (Kanto Chemical Co., Ltd., purity 98.0%) are dissolved in pure water. Then, the liquid volume was set to 1500 ml to be B liquid.

  The liquid A and liquid B were kept at 50 ° C. and then supplied to the Y-shaped reactor shown in FIG. 1 using a roller pump at an addition rate of 5,000 Reynolds numbers in the mixing section.

The reaction solution obtained by the reaction was circulated at a circulation rate of 30 l / min of the reaction solution using Romicon HF 2-20-PM10 (fractionated molecular weight 10,000) as a separation membrane. While adding pure water, desalting was performed until the conductivity of the reaction solution reached 2 mS / m, and a suspension of precursor A was obtained. A part of this suspension was solid-liquid separated with a centrifuge and dried at 110 ° C., followed by powder X-ray diffraction measurement. As a result, a crystal diffraction peak due to Zn (OH) ₂ was detected. .

  The suspension of the precursor A is sprayed in a nitrogen atmosphere at 1000 ° C. using a spray pyrolysis apparatus (model: RH-2, manufactured by Okawara Processing Machine Co., Ltd.) and retained for 20 seconds to produce phosphor 1. did.

When a powder X-ray diffraction measurement was performed on the phosphor 1, a diffraction peak of a crystal due to Zn ₂ SiO ₄ was detected.

(Preparation of phosphor 2)
Precursor B was produced in the same manner as phosphor 1 except that the Reynolds number of the mixing part was changed to 300,000. When a powder X-ray diffraction measurement was performed, a diffraction peak of the crystal due to Zn (OH) ₂ was detected.

The suspension of the precursor B was sprayed in a nitrogen atmosphere at 1000 ° C. using a spray pyrolysis apparatus, and was retained for 60 seconds to produce phosphor 2. When a powder X-ray diffraction measurement was performed, a diffraction peak of crystals due to Zn ₂ SiO ₄ was detected.

(Preparation of phosphor 3)
Liquid A was prepared by mixing colloidal silica containing 45 g of silicon dioxide (PL-3 manufactured by Fuso Chemical Industry Co., Ltd.) and 180 g of potassium hydroxide in pure water to adjust the liquid volume to 1500 ml. Simultaneously, 402 g of zinc nitrate hexahydrate (Kanto Chemical Co., Ltd., purity 99.0%) and 34 g of manganese nitrate hexahydrate (Kanto Chemical Co., Ltd., purity 98.0%) were dissolved in pure water. Liquid B was made up to 1500 ml.

  The liquid A and liquid B were kept at 50 ° C. and then supplied to the Y-shaped reactor shown in FIG. 1 using a roller pump at an addition rate of 5,000 Reynolds numbers in the mixing section.

  The reaction solution obtained by the reaction was circulated at a reaction solution circulation rate of 30 l / min using Romicon HF 2-20-PM10 (fractionated molecular weight 10,000) as a separation membrane, while the reaction solution volume was constant. While adding pure water, desalting was performed until the conductivity of the reaction solution reached 2 mS / m, and a suspension of precursor C was obtained. A part of this suspension was subjected to solid-liquid separation with a centrifugal separator and dried at 110 ° C., followed by powder X-ray diffraction measurement. As a result, no diffraction peak was observed. This indicates an amorphous state.

The suspension of the precursor C was sprayed in a nitrogen atmosphere at 1000 ° C. using a spray pyrolysis apparatus, and stayed for 20 seconds to produce phosphor 3. When a powder X-ray diffraction measurement was performed, a diffraction peak of crystals due to Zn ₂ SiO ₄ was detected.

(Preparation of phosphor 4)
The suspension of the precursor C was sprayed in a nitrogen atmosphere at 1000 ° C. using a spray pyrolysis apparatus, and was retained for 60 seconds to produce phosphor 4. When a powder X-ray diffraction measurement was performed, a diffraction peak of crystals due to Zn ₂ SiO ₄ was detected.

(Preparation of phosphor 5)
Precursor D was produced in the same manner as phosphor 4, except that the Reynolds number of the mixing part was 300,000. When a powder X-ray diffraction measurement was performed, no diffraction peak was observed.

The suspension of the precursor D was sprayed in a nitrogen atmosphere at 1000 ° C. by using a spray pyrolysis apparatus, and was retained for 60 seconds to produce the phosphor 5. When a powder X-ray diffraction measurement was performed, a diffraction peak of crystals due to Zn ₂ SiO ₄ was detected.

(Preparation of phosphor 6)
The suspension of the precursor D was sprayed in a nitrogen atmosphere at 1000 ° C. using a spray pyrolysis apparatus, and was retained for 20 seconds to produce the phosphor 6. When a powder X-ray diffraction measurement was performed, a diffraction peak of crystals due to Zn ₂ SiO ₄ was detected.

(Preparation of phosphor 7)
While the suspension of the precursor D was kept at 50 ° C., aging was performed while stirring for 1 hour to prepare a precursor E. When a powder X-ray diffraction measurement was performed, no diffraction peak was observed.

A suspension of the precursor E was sprayed in a nitrogen atmosphere at 1000 ° C. using a spray pyrolysis apparatus, and was retained for 20 seconds to produce a phosphor 7. When a powder X-ray diffraction measurement was performed, a diffraction peak of crystals due to Zn ₂ SiO ₄ was detected.

(Measurement of composition ratio)
The obtained precursor and phosphor were quantified for Zn and Mn with respect to Si by inductively coupled plasma emission spectroscopy. Next, with respect to the quantitative values of Zn and Mn of the obtained precursors and phosphors, the “change rate of composition ratio (%)” was obtained by the following formula: change rate of composition ratio (%) = 100− ( Quantitative value of phosphor / quantitative value of precursor) × 100
Inductively coupled plasma emission spectroscopy is a method in which a sample is introduced into an argon plasma at a high temperature, and the light specific to each element generated is measured. The intensity of the light is proportional to the amount of elements in the sample. High-sensitivity qualitative and quantitative analysis of samples is possible. Because of the high temperature of the plasma, the optimum measurement conditions for most elements are almost the same, and simultaneous multi-element analysis and multi-element sequential analysis are possible.

(Evaluation of phosphor)
Table 1 shows the average particle diameter and monodispersity of the phosphors 1 to 7.

  The average particle diameter and σ / r were taken with a transmission electron microscope (JEOL Ltd., 2000FX type), directly with a magnification of 5000 times, and the negative was captured as a digital image with a scanner, and using appropriate image processing software 300 or more particles were measured, and the average particle size and standard deviation were calculated and determined.

  Luminance is obtained by irradiating each phosphor powder with a vacuum ultraviolet ray using an excimer 146 nm lamp (manufactured by USHIO INC.) In a vacuum chamber of 0.1 to 1.5 Pa, and detecting the obtained green light with a detector ( MCPD-3000 (manufactured by Otsuka Electronics Co., Ltd.) was used to calculate the relative luminance, which is a relative value when the luminance of the phosphor powder 1 is 100, and is shown in Table 1 as “relative luminance”.

  Next, in order to measure the durability of each phosphor powder, it was introduced into the discharge space filled with 100% argon gas in a sputtering apparatus (manufactured by Sanyu Electronics Co., Ltd .: SC-701), and a current of 1 mA was introduced. Was conducted for 15 minutes, and sputtering was performed. Then, the relative luminance was calculated by the above-described method, and the value obtained by dividing this luminance by “relative luminance” and converted into a percentage is shown in Table 1 as “endurance (%)”. The higher the numerical value of the durability, the less the luminance proposal is suppressed. That is, the phosphor is less likely to be damaged by VUV, ions, and electrons.

  As is apparent from Table 1, the phosphor according to the method for producing the phosphor of the example of the present invention is a fine particle phosphor having a narrow particle size distribution, and has high luminance and high durability.

Y-shaped reactor

Explanation of symbols

A phosphor raw material solution B phosphor raw material solution M mixer P roller pump

Claims (3)

In a method for manufacturing a phosphor, a precursor of a phosphor is formed by a liquid phase method, and then a suspension containing the precursor is formed into droplets and dried and heated to form the phosphor. Has a amorphous structure, and the rate of change in the composition ratio of each of the main constituent elements of the precursor and the phosphor is 5% or less. 2. The method for producing a phosphor according to claim 1, wherein an average particle diameter of the phosphor is 1 nm or more and 100 nm or less. A phosphor formed by drying and heating a suspension containing a precursor of the phosphor in the form of droplets, and the rate of change in the composition ratio of each of the main constituent elements of the precursor and the phosphor is A phosphor characterized by being 5% or less.

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