JP2006274137A - Phosphor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phosphor short in afterglow time and high in emission intensity. <P>SOLUTION: The phosphor emits light on excitation by being irradiated with exciting rays, being such that a zinc silicate compound is doped with manganese, wherein the abundance of Mn-Mn pairs is ≥10% based on the total Mn amount. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a phosphor that can be widely used in devices such as a plasma display and various phosphor-using articles.

  The phosphor is a material that converts the energy of the excitation line into light when irradiated with the excitation line. Devices using the phosphor include fluorescent lamps, electron tubes, cold cathode displays, fluorescent display tubes, plasma display panels (PDP), electroluminescence panels, scintillation detectors, X-ray image intensifiers, thermofluorescence dosimeters, An imaging plate etc. are mentioned. Each of these devices is a device that converts electrical energy into the energy of the excitation line and further converts the energy of the excitation line into the 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. There are inclusions, and these are widely used, for example, as liquid materials such as phosphor paints, pastes, solid materials such as ashtrays, display materials such as guide plates and guides, seals, stationery, outdoor products, safety signs, etc. It is used.

  In recent years, the PDP has been attracting attention as a flat panel display that can replace a cathode ray tube (CRT) because the screen can be enlarged and thinned. A PDP is a display element configured by arranging a large number of minute discharge spaces (hereinafter referred to as “display cells”) in a matrix. Each display cell is provided with a discharge electrode, and the inner wall of each display cell is fluorescent. The body is applied. A rare gas such as He—Xe, Ne—Xe, or Ar is sealed in the space in each display cell. By applying a voltage to the discharge electrode, the rare gas discharge occurs in the display cell, and vacuum ultraviolet rays are generated. Is emitted. The phosphor is excited by the vacuum ultraviolet rays and emits visible light. An image is displayed by light emission of the phosphor of the display cell at a predetermined position of the display element. Full-color display can be performed by using phosphors that emit blue, green, and red as the phosphors used in each display cell and coating them in a matrix.

The phosphors currently used mainly as PDP phosphors are (Y, Gd) BO ₃ : Eu phosphor as red phosphor, Zn ₂ SiO ₄ : Mn phosphor as green phosphor, and BaMgAl ₁₀ as blue phosphor. There are O ₁₇ : Eu phosphors, and in particular, Patent Document 1 discloses a method for producing an aluminate phosphor using an aluminum compound.
JP 2001-172621 A

By the way, in order to improve white luminance among these phosphors, it is important to increase the emission intensity of the green phosphor having particularly high visibility. From such a point, it is strongly demanded to further improve the light emission intensity of the green phosphor by vacuum ultraviolet excitation. Furthermore, a long afterglow time is regarded as a problem in manganese-activated phosphors such as Zn ₂ SiO ₄ : Mn. On the other hand, it is known that the afterglow time is shortened by increasing the amount of Mn. However, when the Mn concentration is increased, the emission intensity is decreased. Thus, at present, the afterglow time and the emission intensity are in a trade-off relationship.
An object of the present invention is to provide a phosphor having a short afterglow time and a high emission intensity.

In order to solve the above problem, the invention according to claim 1
A manganese-doped zinc silicate phosphor in which a zinc silicate compound is doped with manganese and emits light when excited by irradiation with an excitation line,
The abundance of Mn—Mn pairs with respect to the total amount of Mn is 10% or more.

The invention described in claim 2
The manganese-doped zinc silicate phosphor according to claim 1,
The amount of Mn is 10 mol% or more with respect to Si.

The invention according to claim 3
The manganese-doped zinc silicate phosphor according to claim 1 or 2,
The time from when the light is emitted until the intensity of the light is attenuated to 1/10 is 10 ms or less.

  According to the first to third aspects of the present invention, a phosphor having a short afterglow time and a high emission intensity can be provided (see the following examples).

Hereinafter, the best mode for carrying out the present invention will be described.
The phosphor according to the present invention is generally excited by irradiation with excitation rays (ultraviolet rays, visible light, infrared rays, heat rays, electron beams, X-rays, radiation, etc.) and light (ultraviolet rays, visible rays, infrared rays, etc.). And a solution containing a silicon compound (hereinafter referred to as “silicon compound solution”) and a solution containing a metal element (hereinafter referred to as “metal element solution”). The formed precursor is baked and manufactured.

The silicon compound contained in the silicon compound solution may be any silicon compound as long as it is a solid containing silicon and is substantially insoluble in the solution used. For example, silica (silicon dioxide), silicon (single substance) Among them, it is preferable to use silica. Examples of the silica include gas phase method silica, wet silica, colloidal silica, and the like. The BET specific surface area of the silicon compound is preferably 50 m ² / g or more, more preferably 100 m ² / g or more, and further preferably 200 m ² / g or more. The silicon compound preferably has a primary particle size or secondary aggregate particle size of 1 μm or less, more preferably 0.5 μm or less, and even more preferably 0.1 μm or less.

  The solution constituting the silicon compound solution may be any solution as long as the silicon compound is not substantially dissolved, and is preferably water, alcohols, or a mixture thereof. The alcohol may be any alcohol that disperses the silicon compound, and examples thereof include methanol, ethanol, isopropanol, propanol, and butanol. Among these, it is preferable to apply ethanol in which the silicon compound is relatively easily dispersed.

The metal element contained in the metal element solution may be any metal element that can form a silicate phosphor by firing. Zn, Mn, Mg, Ca, Sr, Ba, Y, Zr, Al , Ga, La, Ce, Eu, Tb are preferably one or more metal elements selected from the group consisting of. For example, when producing a green phosphor (Zn ₂ SiO ₄ : Mn or the like), Zn and Mn may be applied as a metal element. The metal element may be a solid that is substantially insoluble in the solution used, or may be composed of chloride, nitrate, or the like and dissolved in the solution used.

  The mixture of the silicon compound solution and the metal element solution may contain a precipitant. Such a precipitating agent is preferably an organic acid or an alkali hydroxide.

  As the organic acid, an organic acid having a —COOH group is preferable, and examples thereof include oxalic acid, formic acid, acetic acid, and tartaric acid. In particular, when oxalic acid is used, it easily reacts with cations of Zn, Mn, Mg, Ca, Sr, Ba, Y, Zr, Al, Ga, La, Ce, Eu, and Tb, and these cations are oxalic acid. Oxalic acid is preferably used as the organic acid because it is likely to precipitate as a salt. Moreover, you may use as a precipitating agent what produces oxalic acid by a hydrolysis etc., for example, dimethyl oxalate etc.

  The alkali hydroxide may be any one having an —OH group, one that reacts with water to produce an —OH group, or one that produces an —OH group by hydrolysis, such as ammonia, sodium hydroxide, Examples thereof include potassium hydroxide and urea. Preferably, ammonia containing no alkali metal is used.

  Note that at least one metal element selected from the group consisting of Zn, Mn, Mg, Ca, Sr, Ba, Y, Zr, Al, Ga, La, Ce, Eu, and Tb is deposited around the silicon compound. It is preferable. Furthermore, it is more preferable that an organic acid or alkali hydroxide is used as a precipitating agent and reacted with them to be deposited around the silicon compound as an organic acid salt or hydroxide. The amount of the organic acid or alkali hydroxide to be used is preferably 1 or more times the stoichiometric amount necessary for depositing a metal element other than silicon as an organic acid salt or hydroxide.

Here, specifically, the phosphor according to the present invention is obtained by applying Zn, Mn as a metal element contained in the metal element solution. The metal element solution containing the metal element, the silicon compound solution, Is produced by firing a precursor formed by mixing. The phosphor is a manganese-doped zinc silicate phosphor (Zn ₂ SiO ₄ : Mn ²⁺ ) in which a zinc silicate compound is doped with manganese, and the abundance of Mn—Mn pairs with respect to the total amount of Mn is 10% or more. is there.

  The abundance ratio of the Mn—Mn pair can be measured by comparing the emission intensity at an emission wavelength of 535 nm and the emission intensity at an emission wavelength of 525 nm. The abundance of the Mn—Mn pair with respect to the total amount of Mn is 10% or more. In this case, the ratio of the emission intensity of 535 nm to the emission intensity of 525 nm (= (emission intensity of emission wavelength 535 nm) / (emission intensity of emission wavelength 525 nm)) is 0.95 or more.

  Further, the phosphor has a Mn amount of 10 mol% or more with respect to Si, and the time from emission to decay of the emission intensity to 1/10 is 10 ms or less.

  Then, the manufacturing method of the fluorescent substance concerning this invention is demonstrated.

  The manufacturing method includes a preparation step of preparing a silicon compound solution, a mixing step of mixing the silicon compound solution and the metal element solution, a precursor forming step of forming a precursor from the mixed liquid obtained in the mixing step, A firing step of firing the precursor obtained in the body forming step.

(1) Preparation Step In manufacturing the phosphor, first, a silicon compound solution is prepared in advance. “Preparation” as used herein means that the particle size and dispersion state of the silicon compound in the solution are adjusted in advance to obtain a desired state. As an example of the preparation method, the silicon compound solution may be treated by a combination of the rotational speed of stirring and the time. As a more effective method, it is preferable to ultrasonically disperse the silicon compound solution. In that case, you may add surfactant and a dispersing agent as needed.

  In addition, the solution temperature in the preparation is preferably 50 ° C. or lower, preferably 30 ° C. or lower, more preferably 10 ° C. or lower in order to prevent an increase in viscosity due to reaggregation of the silicon compound. The aggregate particle diameter is preferably 1 μm or less, preferably 0.5 μm or less, and more preferably 0.1 μm or less in order to obtain a finer phosphor.

  Moreover, in this preparation process, you may use the colloidal silica by which the particle size and dispersion state in the solution were prepared beforehand. The colloidal silica is preferably anionic, and the particle size is preferably 1 μm or less, preferably 0.5 μm or less, more preferably 0.1 μm or less in order to obtain a finer phosphor.

(2) Mixing step When the preparation step is completed, the prepared silicon compound solution and the metal element solution are mixed. Any method may be used for mixing the silicon compound solution and the metal element solution. For example, the mixing method by stirring is easy to control and is low in cost. Further, the mixing method may be any method such as batch type, continuous type, external circulation mixing, etc., for example, a method in which a silicon compound solution is used as a mother liquor and a metal element solution is added to the mother liquor while stirring, or A method of circulating the mother liquor externally and adding the metal element solution to a mixer provided in the external circulation path is preferable from the viewpoint of dispersion of the silicon compound.

  Further, even when a precipitant is added, the mixing method may be any method and order. For example, a silicon compound solution is used as a mother liquor, and the metal liquid and precipitant are mixed with a double jet while stirring the mother liquor. A method of adding them simultaneously or a method of circulating the mother liquor externally and simultaneously adding the metal element solution and the precipitating agent to a mixer provided in the external circulation path by a double jet is preferred. The addition position of the metal element solution or the precipitating agent may be either on the mother liquor surface or in the mother liquor, and is preferably in the mother liquor from the viewpoint of more uniform mixing.

  As a mixing device used for mixing the silicon compound solution and the metal element solution, a device in which the supply port of each solution is constituted by a stainless steel pipe is generally applied. When this apparatus is used, when a later-described firing step is performed in a state where the stainless steel powder constituting the pipe is mixed in a precursor obtained from the mixture in the mixing step, Na, Fe, Cr are contained inside the phosphor crystal. , Ni, Mo, Ti, Nb, and the like have been found to adversely affect the performance of the phosphor. Therefore, it is preferable to coat the inside of the pipe with Teflon (registered trademark), and the pipe itself is PP ( More preferably, it is composed of a resin such as PolyPropylen).

In the present mixing step, when the silicon compound solution and the metal element solution are stirred, the stirring Reynolds number is preferably 1000 or more, preferably 3000 or more, more preferably 5000 or more from the viewpoint of uniform mixing. “Reynolds number (Re)” is a value obtained by the following equation (4), where D is the typical length of an object in the flow, U is the velocity, ρ is the density, and η is the viscosity. The number of dimensions.
Re = ρDU / η (4)

  Further, the mixing method of the silicon compound solution and the metal element solution in this mixing step is to continuously collide and mix the silicon compound solution from the first channel and the metal element solution fed from the second channel. Then, the mixture is continuously fed into the third flow path, and the mixed liquid after the collision is fed for 0.001 second or more so that the Reynolds number is 3000 or more, and then continuously discharged. Is preferred. The Reynolds number after the collision is more preferably 5000 or more, and most preferably 10,000 or more. The liquid feeding time is preferably 0.001 seconds or more, more preferably 0.01 seconds or more, and most preferably 0.1 seconds or more.

(3) Precursor formation step When the mixing step is completed, an existing method for directly drying the mixture of the silicon compound solution and the metal element solution or removing insoluble salts as necessary, for example, filtration water washing, membrane separation After that, the solid is separated from the liquid by a method such as filtration or centrifugation, and then dried to obtain a precursor. The drying temperature is preferably in the range of 20 to 300 ° C, more preferably 90 to 200 ° C. Examples of the direct drying method include evaporation and spray drying which is dried while granulating. The average particle size of the precursor is preferably 1 μm or less, more preferably 0.8 μm or less, and most preferably 0.5 μm. The coefficient of variation of the precursor particles is preferably 50% or less, more preferably 30% or less, and most preferably 15% or less. “Coefficient of variation” is the standard deviation of particle size divided by the average particle size.

(4) Firing step After the precursor forming step, the precursor obtained in the precursor forming step is fired. Any method may be used for firing the precursor. For example, a desired phosphor can be obtained by filling the precursor in an alumina boat and firing the precursor in a predetermined gas atmosphere at a predetermined temperature. For example, when firing a precursor of a green phosphor (Zn ₂ SiO ₄ : Mn or the like), firing is performed at least once in a temperature range of 400 to 1400 ° C. and a range of 0.5 to 40 hours in an inert atmosphere. Is preferred. Furthermore, you may combine air atmosphere (or oxygen atmosphere) and reducing atmosphere as needed. When combined with a reducing atmosphere, firing is preferably performed at a temperature of 800 ° C. or lower in order to prevent evaporation of zinc from the crystal. Examples of a method for obtaining a reducing atmosphere include a method of placing a graphite block in a boat filled with a precursor, a method of firing in a nitrogen-hydrogen atmosphere, or a rare gas / hydrogen atmosphere. Water vapor may be contained in these atmospheres. You may process dispersion | distribution, water washing, drying, sieving, etc. to the silicate type | system | group fluorescent substance obtained after baking.

  The fluorescence according to the present invention can be manufactured by going through the baking step (4) from the above (1) preparation step. And the phosphor according to the present invention manufactured through the above steps is a fluorescent lamp, a fluorescent display tube, a device such as a plasma display panel (PDP), a fluorescent paint, an ashtray, a display object such as a guide plate or an inducer, It can be suitably used for fluorescent materials such as seals, stationery, outdoor goods, and safety signs.

  In Example 1, three types of phosphors were manufactured, the luminance of each phosphor was measured, and the characteristics of each phosphor were evaluated.

(1) Production of phosphors First, three types of phosphors (phosphors 1 to 3) were produced.

(1.1) Manufacture of phosphor 1 Colloidal silica containing 45 g of silicon dioxide and 219 g of ammonia water (28%) are mixed with pure water to prepare a liquid amount of 1500 cc. It was. Separately, 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%) The solution was dissolved in pure water to adjust the amount of the solution to 1500 cc, and this solution was designated as “solution B”.

  Then, A liquid and B liquid were kept at 40 degreeC, and the said A liquid and B liquid were supplied to the Y-shaped reactor. Specifically, liquid A and liquid B kept at 40 ° C. were supplied to a stainless steel supply pipe coated with Teflon using a roller pump. The supply speed was 1800 cc / min.

  Thereafter, the product obtained by the reaction of the Y-shaped reactor was diluted with pure water, filtered under pressure, and solid-liquid separated. Thereafter, the product obtained by solid-liquid separation was dried at 100 ° C. for 12 hours to prepare “Precursor 1”. Thereafter, the precursor 1 was baked at 1280 ° C. for 3 hours in an air atmosphere to prepare “phosphor 1”.

(1.2) Production of Phosphor 2 The above Precursor 1 was baked at 1280 ° C. for 3 hours in a 100% nitrogen atmosphere to produce “Phosphor 2”.

(1.3) Production of Phosphor 3 The above Precursor 1 was fired at 1280 ° C. for 3 hours in an atmosphere of 1% hydrogen and 99% nitrogen to produce “Phosphor 3”.

(2) Evaluation of phosphors The initial luminance, emission intensity, afterglow time, and luminance associated with changes over time of the phosphors 1 to 3 were measured to evaluate the characteristics of the phosphors 1 to 3.

(2.1) Measurement of initial luminance, emission intensity, and afterglow time Excimer lamps (UER20H-146A manufactured by Ushio Electric Co., Ltd.) are turned on in a vacuum chamber of 0.1 to 1.5 Pa, and each phosphor 1 to 3 is turned on. Were irradiated with excitation light having a wavelength of 146 nm, and green light was emitted from each of the phosphors 1 to 3. When each of the phosphors 1 to 3 emits green light, the green light is detected by a detector (MCPD-2000 manufactured by Otsuka Electronics Co., Ltd.), and its initial luminance and emission intensity (an emission intensity of 535 nm with respect to an emission intensity of 525 nm). (= (Emission intensity at emission wavelength 535 nm) / (emission intensity at emission wavelength 525 nm))) and afterglow time (elapsed time when emission intensity (initial luminance) is attenuated to 1/10). These measurement results are shown in Table 1 below.

(2.2) Measurement of luminance with time change Each phosphor 1-3 was pasted, and each paste-like phosphor 1-3 was baked at 500 ° C. for 30 minutes in an air atmosphere. Thereafter, the phosphors 1 to 3 are irradiated with excitation light having a wavelength of 146 nm from an excimer lamp (UER20H-146A manufactured by USHIO INC.) For 500 hours, and the luminance of each phosphor 1 to 3 after 500 hours has been detected. Measured with a vessel (MCPD-2000 manufactured by Otsuka Electronics Co., Ltd.). The measurement results are shown in Table 1 below.

(2.3) Characterization of phosphors As shown in Table 1, phosphors 2 and 3 have a shorter afterglow time and larger emission intensity (initial luminance and luminance with time) than phosphor 1. . From the above, a phosphor having a ratio of the 535 nm emission intensity to the 525 nm emission intensity of 0.95 or more (that is, a phosphor in which the abundance of Mn-Mn pairs with respect to the total Mn content is 10% or more) It can be seen that the afterglow time is short and the emission intensity is high compared to phosphors that are not satisfied.

  In Example 1, three types of phosphors were manufactured, the luminance of each phosphor was measured, and the characteristics of each phosphor were evaluated.

(1) Production of phosphors First, three types of phosphors (phosphors 4 to 6) were produced.

(1.1) Manufacture of phosphor 4 “Precursor 1” was prepared as described in item (1.1) of Example 1 above, and the precursor 1 was subjected to 1280 ° C. in a nitrogen atmosphere for 3 hours. Baking was performed, and then baking was performed at 1280 ° C. for 3 hours in a 100% nitrogen atmosphere to produce “phosphor 4”.

(1.2) Manufacture of phosphor 5 “Precursor 1” was prepared as described in item (1.1) of Example 1 above, and the precursor 1 was subjected to 1280 ° C. in an air atmosphere for 3 hours. Baking was performed, and then baking was performed at 1280 ° C. for 3 hours in a 100% nitrogen atmosphere to prepare “phosphor 5”.

(1.3) Manufacture of Phosphor 6 “Precursor 1” was prepared as described in item (1.1) of Example 1 above, and the precursor 1 was subjected to atmospheric conditions at 1280 ° C. for 3 hours. Baking was performed, and then baking was performed at 1240 ° C. for 3 hours in a 100% nitrogen atmosphere to prepare “phosphor 6”.
(2) Evaluation of phosphors The initial luminance of the phosphors 4 to 6 and the luminance with time change were measured to evaluate the characteristics of the phosphors 4 to 6.

(2.1) Measurement of initial luminance Each of two types of excimer lamps (UER20H-146A made by USHIO INC., UER20H-172A made by USHIO ELECTRIC CO., LTD.) Is turned on in a vacuum chamber of 0.1 to 1.5 Pa. The phosphors 4 to 6 were irradiated with excitation light having a wavelength of 146 nm and excitation light having a wavelength of 172 nm, and green light was emitted from the phosphors 4 to 6. When each phosphor 4-6 emitted green light, the green light was detected with a detector (CS-200 manufactured by Konica Minolta Sensing), and the initial luminance was measured. These measurement results are shown in Table 2 below.

(2.2) Measurement of luminance with time change Each phosphor 4 to 6 is irradiated with excitation light having a wavelength of 146 nm from an excimer lamp (UER20H-146A manufactured by USHIO INC.) For 500 hours, and after 500 hours have elapsed. The luminance of each phosphor 4-6 was measured with a detector (MCPD-2000 manufactured by Otsuka Electronics Co., Ltd.). The measurement results are shown in Table 2 below.

(2.3) Characteristic Evaluation of Phosphor As shown in Table 2, it can be seen that phosphors 5 and 6 have higher emission intensity (initial luminance and luminance with time) than phosphor 4.

Claims (3)

A phosphor in which zinc is doped with manganese in a zinc silicate compound that emits light when excited by irradiation with an excitation line,
A phosphor characterized in that the abundance of Mn—Mn pairs with respect to the total amount of Mn is 10% or more. The phosphor according to claim 1,
A phosphor having a Mn content of 10 mol% or more with respect to Si. The phosphor according to claim 1 or 2,
A phosphor characterized in that the time from when the light is emitted until the emission intensity is attenuated to 1/10 is 10 ms or less.