JP2007119618A - Inorganic phosphor and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a particulate, monodispersed inorganic phosphor which is stable, shows no deterioration in the luminous intensity and exerts a favorable luminous efficiency, and a method for producing the same. <P>SOLUTION: In the method for producing the inorganic phosphor, a precursor is formed by mixing a solution containing a compound (e.g. silicon dioxide) serving as a parent with a solution containing a metal element (e.g. Zn, Mn, Mg, Ca, Sr, Ba, Y, Zr, Al, Ga, La, Ce, Eu, Tb) that forms the phosphor by reacting with the parent when burned, and spray-firing of a precursor dispersion is performed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing an inorganic phosphor (hereinafter, also simply referred to as phosphor) and an inorganic phosphor, and more specifically, the inorganic phosphor obtained by the production method is fine particles and monodispersed. The present invention relates to an inorganic phosphor of a spherical phosphor.

  Conventional inorganic phosphors generally have a flat shape with individual particles of about 2 to 10 μm or an irregular multi-face shape, and the surface is generally rough.

  One type of light emitting device using an inorganic phosphor is a picture tube. The picture tube has a phosphor layer formed by applying phosphors in multiple layers, and light is generated from the phosphor by accelerating electrons scattered or absorbed by the phosphors in the phosphor layer. To do.

  With the progress of the information society in recent years, the picture tube is expected to have a larger screen, higher contrast, and higher definition as symbolized by a high-definition CRT and a high-definition display tube.

  Also, in the field of biotechnology, a method of measuring fluorescence emitted by ultraviolet irradiation with an optical microscope or photodetector in the past for research of viruses and enzymes, or for clinical tests, using phosphors as labels. Has been taken.

  As such a method, for example, an antigen-antibody fluorescence method is widely known. In this method, an antibody (referred to as a specific binding substance) bound with an organic fluorescent substance that emits fluorescence is used. Since the antigen-antibody reaction is very selective, the position of the antigen can be known from the fluorescence intensity distribution. In recent years, higher light emission and higher stability are expected with the expansion of the market.

  However, when a phosphor layer of a picture tube is formed using a conventional phosphor, for example, the phosphor cannot form a dense array structure, and the density of the phosphor in the phosphor layer is low. End up. In order to obtain a predetermined luminance, the phosphor layer must contain a certain amount of phosphor. However, if the phosphor layer is thick, scattering of light emitted from the phosphor increases, The resolution will be reduced. Conversely, if the thickness of the phosphor layer is reduced, the amount of the phosphor is insufficient and the light emission intensity is reduced.

  As one means for achieving and achieving both of these characteristics, there is a demand for finely divided and monodispersed inorganic phosphors.

  In the field of biotechnology, in recent years, there has been a strong demand for studying more precise antibody distribution by observing objects smaller than about 1 μm. In order to achieve this, it is necessary to rely on an electron microscope.

  In observation with an electron microscope, an image is observed using the difference in electron beam reflectance or transmittance of the specimen. For this reason, when an antibody is observed with an electron microscope, a molecule containing iron or osmium having a large atomic weight or a gold colloid having a size of about 1 to 100 nm is currently used as a label for the antibody.

  For example, when gold colloid is used as a label, a complex of protein A and gold colloid is bound to the antibody. Since this antibody binds to the corresponding antigen by an antigen-antibody reaction, the location of the antigen can be clarified by measuring the position of the gold colloid on the specimen.

  Furthermore, if two or more types of gold colloids having different sizes are bound to a plurality of types of antibodies, a plurality of antigens can be observed simultaneously. However, this method has a drawback that colloids may overlap at the time of measurement, and quantitative determination is difficult only by measuring the number of colloids.

  It is also difficult to observe the cathodoluminescence image using the above-described organic phosphor as a label. In other words, in addition to the low luminous efficiency inherently, organic phosphors are easily broken due to electron beam irradiation, and the light emission ability is reduced by a single scan. It does not endure. These organic phosphors also lack stability during storage and cause deterioration. In addition to molecular organic fluorescent dyes, polystyrene spheres having a particle size of several tens of nm and emitting red, green, or blue light are known as phosphors composed of organic molecules. There are exactly the same problems.

  On the other hand, inorganic phosphors are stable to ultraviolet irradiation and electron beam irradiation and have little deterioration. However, since conventional phosphors are usually 2 to 10 μm in size, they cannot be used as they are for the antigen-antibody reaction. In order to reduce the particle size, it is conceivable to pulverize the phosphor or etch it with an acid. However, in these methods, the ratio of the non-light emitting layer covering the surface of each particle increases, so that the luminous efficiency is improved. It will drop significantly.

  As one means for achieving and achieving both of these characteristics, there is a demand for finely divided and monodispersed inorganic phosphors.

  For example, Patent Document 1 discloses a method for producing a fine particle phosphor using coprecipitation as a method for producing the fine particle phosphor. Nanosized phosphor particles doped with an activator are formed by a liquid phase reaction utilizing coprecipitation, and an organic acid such as acrylic acid or methacrylic acid is added during the liquid phase reaction.

  As a result, the surface of the phosphor particles is coated with an organic acid, and defects on the surface of the phosphor particles are reduced, thereby improving luminous efficiency.

  However, since the above technique coats the organic acid on the particle surface, there is a problem in stabilization because the emission intensity is greatly deteriorated when irradiated with ultraviolet rays and electron beams.

  For example, Patent Document 2 discloses a method for producing a spherical phosphor based on silicon oxide dioxide having a spherical or almost spherical particle shape as a method for producing a spherical phosphor. A spherical zinc silicate phosphor is produced by a solid phase reaction by heating and firing a powder mixture of spherical polymethylsilsesquioxy acid, zinc oxide and manganese carbonate. As a result, a dense phosphor layer is formed to improve the light emission characteristics.

  However, the above technique is produced by a solid phase method and can be monodispersed, but it is difficult to produce a phosphor that is atomized to the nanometer order.

For example, Patent Document 3 discloses a phosphor manufacturing method for manufacturing a Zn ₂ SiO ₄ : Mn phosphor using a liquid phase method as a phosphor manufacturing method. By producing a precursor using anionic colloidal silica, the surface of the silica particles is coated with zinc hydroxide to achieve a fine particle phosphor.

  However, in the above technology, the precursor once dried is produced by using a baking kiln such as a rotary kiln, so that aggregation and fusion occur during drying and firing. It has been difficult to obtain a phosphor that has been converted into a phosphor.

Therefore, there has been a demand for a method for producing an inorganic phosphor that is monodispersed with fine particles, is stable with no deterioration in light emission intensity, and has high light emission efficiency.
Japanese Patent Laid-Open No. 10-310770 Japanese Patent Laid-Open No. 9-278446 JP 2004-292804 A

  An object of the present invention is to provide an inorganic phosphor that is finely dispersed, monodispersed, stable without deterioration of emission intensity, and having high emission efficiency, and a method for producing the same.

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

  1. A precursor is formed by mixing a solution containing a compound serving as a mother nucleus and a solution containing a metal element that can react with the mother nucleus by firing to form a phosphor, and spray firing the precursor dispersion. The manufacturing method of the inorganic fluorescent substance characterized by the above-mentioned.

  2. 2. The method for producing an inorganic phosphor according to 1 above, wherein the particle surface of the compound serving as a mother nucleus has a function of specifically contacting the metal element.

  3. 3. The method for producing an inorganic phosphor according to 1 or 2 above, wherein the compound serving as a mother nucleus has a particle size of 1 to 100 nm.

  4). 4. The method for producing an inorganic phosphor according to any one of items 1 to 3, wherein the shape of the compound serving as a mother nucleus is spherical or almost spherical.

  5. 5. The method for producing an inorganic phosphor according to any one of 1 to 4, wherein the dispersity of the compound serving as a mother nucleus is 15% or less.

  6). 6. The method for producing an inorganic phosphor according to any one of 1 to 5, wherein a firing temperature of the spray firing is controlled in at least two stages.

  7). 7. The method for producing an inorganic phosphor according to any one of 1 to 6, wherein the compound serving as a mother nucleus is silicon dioxide.

8). 8. The method for producing an inorganic phosphor according to any one of 1 to 7, wherein a density of silanol groups on the surface of the silicon dioxide particles is 4 to 9 / nm ² .

  9. Wherein the metal element is at least one metal element selected from Zn, Mn, Mg, Ca, Sr, Ba, Y, Zr, Al, Ga, La, Ce, Eu, and Tb. 9. The method for producing an inorganic phosphor according to any one of 8 above.

  10. 10. An inorganic phosphor produced by the method for producing an inorganic phosphor according to any one of 1 to 9 above.

  That is, as a result of various investigations on the above-described problems, the present inventors, in the method for producing a phosphor, as described in the claims, a solution containing a compound serving as a mother nucleus and firing the mother nucleus by firing. Fluorescence monodispersed with fine particles that could not be achieved by conventional manufacturing methods by forming a precursor by mixing with a solution containing a metal element that can form a phosphor by reacting with a phosphor. I found that I can provide a body.

  The method for producing an inorganic phosphor and the inorganic phosphor according to the present invention are fine particles and monodispersed, have no deterioration in emission intensity, are stable, and have an excellent effect of good emission efficiency.

  Hereinafter, the present invention will be described in detail.

  First, the method for producing the inorganic phosphor of the present invention will be described.

<< Process for producing precursor >>
In the method for producing a phosphor of the present invention, a precursor is prepared by mixing a solution containing a compound serving as a mother nucleus and a solution containing a metal element that can react with the mother nucleus by firing to constitute the phosphor. It is essential that the precursor dispersion thus formed is spray-fired.

  The mother nucleus as used herein refers to a particle that becomes the core in forming the phosphor, and the surface of the compound particle that serves as the mother nucleus is coated with a metal element that can react with the mother nucleus to form the phosphor. Then, the precursor is formed by forming a shell shape.

  In the method for producing the phosphor of the present invention, the compound serving as a mother nucleus is not particularly limited, and any compound may be used as long as it is substantially insoluble in the solution used. Aluminum oxide, titanium oxide, barium titanate Silicon dioxide or the like is preferably used, but silicon dioxide (silica) is particularly preferably used. Examples of the silica include gas phase method silica, wet silica, colloidal silica, and the like.

In the method for producing a phosphor of the present invention, it is preferable that the surface of the particle of the compound serving as a mother nucleus has a function of specifically contacting the metal element. The specific contact function (hereinafter simply referred to as function) is not particularly limited and may be either a physical or chemical function, but preferably has a chemical function. For example, what has a chemical function on the particle surface of silicon dioxide (silica) refers to a silanol group of silicon dioxide (silica), and it is preferable that many silanol groups exist. Specifically, the silanol group density is 4 to 9 / nm ² , more preferably 7 to 9 / nm ² .

  The measurement of the silanol group density is obtained by heating the silica at a temperature of 110 ° C. to 1200 ° C. and converting the reduced weight to a silanol group density.

  In the method for producing the phosphor of the present invention, the particle size of the compound serving as a mother nucleus is preferably 1 to 100 nm. More preferably, it is 2-70 nm, More preferably, it is 5-50 nm. When the thickness is less than 1 nm, it is difficult for the metal element to be in uniform contact with the particle surface. When the thickness exceeds 100 nm, it is difficult to obtain a desired effect.

  Here, the particle size means an average value obtained by measuring an average particle size of 300 particles using an electron microscope (for example, S-900 manufactured by Hitachi, Ltd.). In the present invention, the shape of the compound serving as the mother nucleus is preferably spherical or almost spherical. Specifically, the ratio of the maximum diameter to the minimum diameter is 1.0 to 1.2, more preferably 1.0 to 1.2. It is preferable to be in the range of 1.1. When the ratio of the maximum diameter to the minimum diameter exceeds 1.2, for example, when a phosphor layer of a picture tube is formed, it is desirable that the phosphor density in the phosphor layer is reduced and the layer thickness tends to be uneven. The characteristics cannot be obtained.

  In the phosphor of the present invention, the compound serving as a mother nucleus is preferably monodispersed. The monodispersion here refers to a case where the monodispersity obtained by the following formula is 15% or less. In the present invention, the monodispersity is more preferably 10% or less, particularly preferably 1 to 5%.

Monodispersity = (standard deviation of particle size / average value of particle size) × 100
In the phosphor manufacturing method of the present invention, it is preferable that the raw materials containing the constituent elements of the phosphor are dissolved and mixed in advance. The raw material is not particularly limited as long as it can be dissolved in the solvent used, but it is preferable to use water for environmental reasons. As a raw material in the case of water, for example, chloride, nitrate, sulfate and the like are preferably used.

  Furthermore, these may be used individually by 1 type and may be used in combination of 2 or more type. Any combination or concentration of raw materials may be used as long as it dissolves in water and does not react and cause precipitation or precipitation when mixed, and may be prepared in advance so as to have a target composition.

  The metal element in the present invention may be any element as long as it can constitute an inorganic phosphor by firing. Zn, Mn, Mg, Ca, Sr, Ba, Y, Zr, Al, Ga, La, It is preferably at least one metal element selected from Ce, Eu and Tb.

For example, when manufacturing Zn ₂ SiO ₄ : Mn, which is the most common phosphor, a material containing Zn and Mn may be used. However, as described above, the metal element must be dissolved in the solution to be used, and when mixed with a solution containing a compound serving as a mother nucleus, the metal element specifically adheres to the surface of the mother nucleus particle. After contact, it is essential to deposit into a shell.

  At this time, if a precipitating agent such as an organic acid or alkali hydroxide is used, particles containing a metal element are deposited on the surface other than the surface of the mother core particles, and a precursor having a desired particle size and shape cannot be obtained.

  In the production method of the present invention, the mixing method of the solution containing the compound serving as the mother nucleus and the solution containing the metal element that can constitute the inorganic phosphor by firing may be any method, for example, a mixing method by stirring. It is preferable because it is easy to control and low cost.

  The mixing method may be any method such as batch type, continuous type, and external circulation mixing. For example, a solution containing a compound serving as a mother nucleus is used as a mother liquor, and the other solution is stirred in the mother liquor. Or a method in which the mother liquor is externally circulated and the other liquid is added to a mixer provided in the external circulation path. The addition position of the solution 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. Further, the stirring Reynolds number is preferably 1000 or more, preferably 3000 or more, more preferably 5000 or more, from the viewpoint of uniform mixing.

  In addition, the temperature of the solution when mixing is 50 ° C. or lower, preferably 30 ° C. or lower, more preferably 10 ° C. or lower.

  In the production method of the present invention, it is preferable to remove insoluble salts from a solution containing a compound serving as a mother nucleus and a solution containing a metal element capable of constituting an inorganic phosphor by firing. . The removal method is not particularly limited, but various membrane separation methods are preferably used.

In the production method of the present invention, it is essential to spray-fire the inorganic phosphor precursor dispersion. In a commonly used firing method using a box furnace, a rotary kiln or the like, aggregation and fusion occur during firing, and a phosphor having a desired particle size and shape cannot be obtained.
Spray firing is a method in which fine particles are obtained by spraying a solution, slurry, etc. into a high-temperature furnace by means such as an ultrasonic nozzle and instantaneously performing thermal decomposition, reaction, synthesis, or roasting. Used in the manufacture of

  In the present invention, the firing temperature of the precursor dispersion, the time gas atmosphere and the like are not particularly limited and can be appropriately selected according to the type of the phosphor, but it is preferable that the firing temperature is controlled at least in two stages. It is. More preferably, it is preferable to perform firing in a low temperature range immediately after spraying, and gradually fire in a high temperature range. Here, the low temperature region indicates 200 to 700 ° C., and the high temperature region indicates 500 ° C. or higher.

  It is essential that the phosphor produced by the production method of the present invention has a particle size and shape that maintain substantially the same particle size and shape as the compound serving as the mother nucleus.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, the embodiment of this invention is not limited to these.

Example 1
(Preparation of phosphor 1-1)
Mixed aqueous solutions A and B having the following composition were prepared.

(Mixed aqueous solution A)
Zinc nitrate _{(Zn (NO 3) 2 ·} 6H 2 O) 1270g
Manganese nitrate _{(Mn (NO 3) 2 ·} 6H 2 O) 194g
8233g of pure water
(Mixed aqueous solution B)
Colloidal silica (SiO ₂ ) 693g
(25 nm, silanol group density 3, spherical particles, solid content concentration 20% by mass)
Pure water -8640g
Using the apparatus of FIG. 1, liquid A and liquid B were each fed to a mixer having a constant flow rate of 4000 ml / min, an angle of 30 °, and a diameter of 3 mm to obtain a precursor dispersion.

  Next, the obtained precursor dispersion is put into a centrifuge, and after separation of by-products until the electric conductivity reaches 20 μS / cm, it is dehydrated, dried by standing at 100 ° C. and dried. A finished precursor was obtained.

(Phosphor production by firing process)
The dried precursor was baked at 1300 ° C. for 2 hours in a nitrogen atmosphere to obtain phosphor 1-1.

(Preparation of phosphor 1-2)
In the production of phosphor 1-1, phosphor 1-2 was produced in the same manner except that colloidal silica having a silanol group density of 8 was used.

(Preparation of phosphor 1-3)
By using a UF film, the secondary salt was removed from the precursor dispersion obtained in the preparation of the phosphor 1-2 until the electric conductivity reached 20 μS / cm.

  Then, it was fired by spraying into the furnace at a spray rate of 1 liter / hour in a nitrogen atmosphere in the form of a slurry. At this time, operation was performed at a furnace temperature of 1100 ° C.

(Preparation of phosphor 1-4)
In the production of the phosphor 1-3, the temperature in the spray firing furnace is set to 350 ° C. in the furnace temperature on the spray nozzle side (1/2 of the furnace body length), and the remaining half length is set to 1100 ° C. Adjusted and operated.

(Evaluation of phosphor)
The obtained phosphors 1-1 to 1-4 were measured for particle size and degree of dispersion using the method described above. Further, the emission intensity and the deterioration of the emission intensity were evaluated by the following methods. The results are shown in Table 1.

  Table 1 shows that the present invention is superior.

It is the schematic which shows an example of the apparatus which manufactures the precursor dispersion liquid of the fluorescent substance of this invention.

Explanation of symbols

1 Phosphor firing dispersion 2 Stirrer

Claims (10)

A precursor is formed by mixing a solution containing a compound serving as a mother nucleus and a solution containing a metal element that can react with the mother nucleus by firing to form a phosphor, and spray firing the precursor dispersion. The manufacturing method of the inorganic fluorescent substance characterized by the above-mentioned. The method for producing an inorganic phosphor according to claim 1, wherein the surface of the particle of the compound serving as a mother nucleus has a function of specifically contacting the metal element. The method for producing an inorganic phosphor according to claim 1 or 2, wherein the compound serving as a mother nucleus has a particle size of 1 to 100 nm. The method for producing an inorganic phosphor according to any one of claims 1 to 3, wherein the shape of the compound serving as a mother nucleus is spherical or almost spherical. The method for producing an inorganic phosphor according to any one of claims 1 to 4, wherein the dispersity of the compound serving as a mother nucleus is 15% or less. The method for producing an inorganic phosphor according to any one of claims 1 to 5, wherein a firing temperature of the spray firing is controlled in at least two stages. The method for producing an inorganic phosphor according to any one of claims 1 to 6, wherein the compound serving as a mother nucleus is silicon dioxide. Method of producing an inorganic phosphor according to claim 1, wherein the silanol group density on the particle surfaces of the silicon dioxide is 4-9 pieces / nm ^2. The metal element is at least one metal element selected from Zn, Mn, Mg, Ca, Sr, Ba, Y, Zr, Al, Ga, La, Ce, Eu, and Tb. The manufacturing method of the inorganic fluorescent substance of any one of -8. An inorganic phosphor produced by the method for producing an inorganic phosphor according to claim 1.

Images