KR20070021141A - Silicate Phosphor, Silicate Phosphor Precursors, Method for Producing These, and Apparatus for Producing Silicate Phosphor Precursors - Google Patents

Abstract

The present invention provides a silicate-based green phosphor having a high luminescence intensity and a short afterglow time, and a method for producing the same. Supplying a suspension containing a silicon compound to a first flow path, supplying a solution containing a metal compound capable of forming a silicate-based phosphor precursor to a second flow path, and mixing the suspension and the solution in a third flow path, After forming the flow of the mixed liquid of Reynolds number 3 * 10 <^3> -1 * 10 <^6> , the fluorescent substance precursor is manufactured by discharge | emitting the said mixed solution from the said 3rd flow path.

Silicate-based phosphors, silicate-based phosphor precursors, Reynolds number

Description

SILICATE PHOSPHOR, PRECURSOR OF SILICATE PHOSPHOR, PROCESS FOR PRODUCING THEM AND APPARATUS FOR PRODUCTION OF PRECURSOR OF SILICATE PHOPPHOR}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for producing phosphors that can be widely used in devices such as display devices such as plasma display panels and lighting devices such as tubular fluorescent lamps, electronic devices, and various phosphor-use articles.

The phosphor is a material that converts the energy of the excitation line into light (ultraviolet light, visible light, infrared light, etc.) by irradiating excitation lines (ultraviolet rays, visible light, infrared rays, heat rays, electron beams, X-rays, radiation, etc.). 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 (PDP), an electroluminescent panel, a scintillation detector, an X-ray image intensifier, a thermal fluorescence dosimeter, and an imaging plate. (See, eg, "Fluorescent Handbook", Phosphor Dynamics Society, Ohmsa). All of these devices are devices which convert electrical energy into energy of the excitation line and also convert energy of the excitation line into the light. BACKGROUND Electronic devices that combine such devices with electronic circuits or device components (such as lighting devices, computers, keyboards, electronic devices without phosphors, etc.) are widely used as lighting devices, display devices, and the like. In addition, as a phosphor-use article using phosphors, there are phosphor-containing substances in which powdery phosphors and substances other than phosphors such as liquids such as water or organic solvents, resins, plastics, metals or ceramics materials are combined, and these are phosphors, for example. BACKGROUND ART It is widely used as liquids such as paints, pasty materials, solids such as ashtrays, signs such as guide plates and induction articles, seals, stationery, outdoor goods, safety signs, and the like.

Recently, in particular, PDP is attracting attention as a flat panel display that can replace the cathode ray tube (CRT) because the screen can be made larger and thinner. A PDP is a display element formed by arranging a plurality of micro discharge spaces (hereinafter sometimes referred to as "display cells") in a matrix form. A discharge electrode is provided in each display cell, and a phosphor is coated on an inner wall of each display cell. have. A rare gas such as He-Xe, Ne-Xe, Ar, or the like is sealed in the space in each display cell. Discharge of the rare gas occurs in the display cell by applying a voltage to the discharge electrode, and vacuum ultraviolet rays are radiated. The fluorescent substance is excited by this vacuum ultraviolet ray and emits visible light. An image is displayed by phosphor light emission of the cell which shows the position where a signal was input in the display element. As the phosphor used for each display cell, phosphors emitting blue, green, and red, respectively, can be used to display full color by distinguishing them in matrix form.

Currently, mainly used as phosphors for PDPs are (Y, Gd) BO ₃ : Eu phosphors as red phosphors, Zn ₂ SiO ₄ : Mn phosphors as green phosphors, and BaMgAl ₁₀ O ₁₇ : Eu phosphors as blue phosphors. Among them, in order to improve the white luminance, it is particularly important to increase the emission intensity of the green phosphor having high visibility. In this regard, there is a strong demand for further improving the luminescence intensity by vacuum ultraviolet excitation of the green phosphor.

In addition, manganese activating phosphors including Zn ₂ SiO ₄ : Mn have a long afterglow time problem. In view of this, it is known that the afterglow time is shortened by increasing the amount of Mn. However, when the Mn concentration is increased, the luminance decreases. As such, in reality, afterglow time and luminance are in a trade-off relationship.

From this, it is an important subject to shorten afterglow time, suppressing the fall of the brightness | luminance of the said silicate type fluorescent substance.

Conventionally, as a general manufacturing method of the above-mentioned phosphors, by a solid phase method of mixing a predetermined amount of a compound containing an element constituting the phosphor matrix and a compound containing an activator element, firing at a predetermined temperature to obtain a phosphor by a solid-phase reaction Manufacturing methods (see "Phosphor Handbook") have been widely adopted.

However, in the solid phase method, it is difficult to produce a phosphor having a pure stoichiometric composition, and as a result of the interphase reaction, a surplus of unreacted impurities, by-product salts generated by the reaction, etc. remain, and thus, a stoichiometric high purity phosphor is produced. It's hard to get As a result, problems such as lowering of luminance of the phosphor have been pointed out.

On the other hand, it is known that the liquid phase method is more suitable than the solid phase method to obtain a compositionally uniform and high-purity particulate phosphor. As a conventional method for producing a phosphor by a liquid phase method, a method of synthesizing by a reaction crystallization method, a sol gel method, a coprecipitation method, a hydrothermal synthesis method, or the like and converting them into an oxide by recovery, washing, drying, firing or the like is known.

In addition, Patent Document 1 discloses a method of forming a precursor by depositing another element as a salt of an organic acid on the surface of a compound containing some elements constituting the phosphor. However, this method relates to an aluminate phosphor using an aluminum compound, and a discovery for producing a silicate-based phosphor which is a green phosphor cannot be obtained from Patent Document 1.

Similarly, Patent Literature 2 does not provide a discovery for producing a silicate-based phosphor. Similarly, Patent Literature 2 discloses a method for forming phosphor precursor particles by a reaction tube. There is no definition, it is insufficient in terms of reaction, and no consideration is given to problems due to wear inside the reaction tube.

Patent Document 1: Japanese Patent Application Laid-Open No. 2001-172621

Patent Document 2: Japanese Patent Laid-Open No. 2003-138253

<Start of invention>

An object of the present invention is to provide a method for producing a phosphor having excellent luminescence intensity and a short afterglow time and a phosphor, and a device, an electronic device, and an article for use of the phosphor, which have not been achieved by the conventional manufacturing method. It is done.

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

(Configuration 1) A production method for forming a silicate-based phosphor precursor by a suspension containing a silicon compound and a solution containing a metal compound, wherein the suspension of the first flow path and the solution of the second flow path are continuously mixed, and A method of continuously discharging from said third flow path after forming a flow of a mixed solution of Reynolds number 3x10 ³ to 1x10 ⁶ in three flow paths.

(Configuration 2) Extension from a first flow path, first liquid feed means for sending liquid to the first flow path, second flow path, second liquid feed means for sending liquid to the second flow path, and confluence of the first and second flow paths And a first flow path, wherein the first and second liquid feeding means each feed a suspension containing a silicon compound in the first flow path and a solution containing a metal compound forming a silicate-based phosphor precursor in the second flow path. By continuously sending the suspension and the solution to the third flow path, and continuously forming the flow of the mixed solution of Reynolds number 3 × 10 ³ to 1 × 10 ^{6 in} the ^third flow path. An apparatus for producing a silicate-based phosphor precursor discharged from a third flow path.

(Configuration 3) A silicate-based phosphor precursor prepared by the production method described in Configuration 1 above.

(Configuration 4) The method for producing the silicate-based phosphor precursor according to Configuration 1, wherein at least the third flow path is made of a material having low abrasion with respect to the suspension, the solution, and the mixed solution.

(Configuration 5) The apparatus for producing a silicate-based phosphor precursor according to Configuration 2, wherein at least the third flow path is made of a material having low abrasion with respect to the suspension, the solution, and the mixed solution.

(Configuration 6) A method for producing the silicate-based fluorescent material according to Configuration 1, wherein the discharged liquid is liquefied and then the phosphor precursor obtained by liquefaction is fired.

(Configuration 7) A silicate-based phosphor produced by the production method described in Configuration 6.

(Configuration 8) The silicate-based phosphor according to Configuration 7, wherein the average particle diameter is 1 µm or less and the variation coefficient of the particles is within 50%.

(Configuration 9) The silicate-based phosphor according to Configuration 7 or Configuration 8, wherein the total content of sodium and iron is 100 ppm or less.

1 is a view showing a reaction device of a comparative example.

2 is a view showing an example of a reaction apparatus used in the embodiment of the present invention.

Best Mode for Carrying Out the Invention

The inventors of the present invention have variously studied the problems described above, and as a result, as described in claim 1 in the method for producing a phosphor, a solution containing a metal compound capable of forming a silicate-based phosphor by firing with a suspension containing a silicon compound By using the method of mixing and forming a precursor, and baking it, the manufacturing method of the fluorescent substance which was excellent in the luminescent intensity which was not able to be achieved by the conventional manufacturing method, and also has a short afterglow time, and this fluorescent substance and the device using the said fluorescent substance, an electron It has been found that it is possible to provide instruments and articles for use with phosphors.

Preferred examples of the crystal matrix of the silicate-based phosphor according to the present invention includes, for example, such as _{Y 2 Si0 5, Zn 2 Si0} 4.

These crystal matrixes and activators or study agents may be partially substituted with the cognate element, and there is no particular limitation on the element composition. Although the compound example of the silicate type fluorescent substance which concerns on this invention is shown below, this invention is not limited to these compounds.

[Blue Luminous Inorganic Fluorescent Compound]

Y ₂ SiO ₅ ㆍ Ce ^{3 +}

[Green Luminous Inorganic Phosphor]

_{(Ba, Mg) 2 SiO 4} : Eu 2 + Y 2 SiO 5: Ce 3 +, Tb 3 + Sr 2 Si 3 O 8 -2SrCl 2: Eu 2 + Zr 2 SiO 4, MgAl 11 O 19: Ce 3 + , Tb ³⁺ Ba ₂ SiO ₄ : Eu ²⁺ Zn ₂ SiO ₄ : Mn ²⁺ Y ₂ SiO ₅ : Ce ³⁺ , Tb ^{3 +}

[Red-emitting Inorganic Phosphor]

(Ba, Mg) ₂ SiO ₄ : Eu ^{3 +} Ca ₂ Y ₈ (SiO ₄ ) ₆ O ₂ : Eu ^{3 +} LiY ₉ (SiO ₄ ) ₆ O ₂ : Eu ^{3 +}

In the present invention, a silicon compound is used, wherein the silicon compound is a solid containing silicon, and any may be used as long as it is substantially insoluble with respect to the solution used. Examples thereof include silica (silicon dioxide) and the like. Preference is given to using silica. As silica, vapor-phase silica, wet silica, colloidal silica, etc. are mentioned.

The BET specific surface area of the silicon compound in the present invention is preferably 50 m ² / g or more, more preferably 100 m ² / g or more, still more preferably 200 m ² / g or more.

1 micrometer or less is preferable, and, as for the primary particle size or secondary aggregation particle size of the silicon compound in this invention, More preferably, it is 0.5 micrometer or less, More preferably, it is 0.1 micrometer or less.

The metal element in the metal compound in the present invention may be any one as long as it can form a silicate-based phosphor by firing, and Zn, Mn, Mg, Ca, Sr, Ba, Y, Zr, Al, Ga, La, It is preferable that it is at least 1 type of metal element selected from the group which consists of Ce, Eu, and Tb. For example, when manufacturing a green phosphor (Zn ₂ SiO ₄ : Mn, etc.), those containing Zn and Mn can be used. The metal element may be a solid which is substantially insoluble with respect to the solution to be used, or may be composed of chloride or nitrate and dissolved in the solution to be used.

It is preferable 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, Tb is precipitated around the silicon compound. Moreover, it is more preferable to use organic acid, alkali hydroxide, etc. as a precipitating agent, and to react with these and to precipitate around a silicon compound as organic acid salt or hydroxide. As the amount of the organic acid or alkali hydroxide to be used, preferably one or more times the stoichiometric amount required for the precipitation of metal elements other than silicon as organic acid salts or hydroxides is preferable.

In the present invention, the solution constituting the suspension containing the silicon compound may be any one as long as the silicon compound is not substantially dissolved as described above, and is preferably water or alcohols or a mixture thereof. As alcohol, what kind of thing may be used as long as it disperse | distributes a silicon compound, For example, methanol, ethanol, isopropanol, propanol, butanol, etc. are mentioned. Among these, ethanol is preferred in which the silicon compound is relatively easily dispersed.

The method of mixing the suspension containing the silicon compound in the present invention with a solution containing a metal compound capable of forming a silicate-based phosphor by firing may be any method, for example, controlled by the mixing method by stirring. It is desirable because it is easy and low cost. The mixing method may be any of batch, continuous, and external circulation mixing. For example, a solution containing a silicon compound is used as a mother liquid, and a method of adding another solution therein while stirring the mother liquid. Or a method of adding another liquid to a mixer installed in an external circulation path by externally circulating the mother liquid is preferable from the viewpoint of dispersion of the silicon compound. In addition, also in the case of adding a precipitant, the mixing method may be in accordance with any method or order. For example, a solution containing a silicon compound is used as a mother liquid, and the other liquid is simultaneously added by a double jet while stirring the mother liquid. The method, or the method of externally circulating the mother liquor and simultaneously adding another liquid to the mixer installed in the external circulation path by a double jet, is preferred. The addition position of the solution may be either the mother liquid surface or the mother liquid, which is preferably in the mother liquid from the viewpoint of more uniform mixing. In addition, the stirred Reynolds number is preferably 1 × 10 ³ or more, preferably 3 × 10 ³ , more preferably 5 × 10 ³ or more, from the viewpoint of uniform mixing and stirring.

If the Reynolds number is lower than 1 × 10 ³ , the mixed state deteriorates and the uniformity of the phosphor particles decreases.

Moreover, the mixing method of the solution containing the silicon compound in this invention, and the solution containing the metal compound which can form a silicate type fluorescent substance by baking is made into the suspension containing the silica sent from at least 1st flow path, The raw material solution and suspension fed from two flow paths are continuously mixed, and then fed to the third flow path continuously, and the mixed solution is 1 × 10 ⁻³ to 3.6 × at a Reynolds number of 3 × 10 ³ to 1 × 10 ⁶ . It is more preferable to use the apparatus for producing a phosphor precursor, which is configured to be discharged continuously after feeding for 10 ³ seconds, and the lower limit of the Reynolds number is more preferably 5 × 10 ³ , and preferably 1 × 10 ⁴ . Most preferred. The lower limit of the liquid-delivery time is 1 × 10 ^-3 seconds is preferable, more preferably 1 × 10 ^-2 seconds, 1 × 10 ^-1 seconds being most preferred.

Reynolds number is a dimensionless number obtained by the following formula, when the representative length of an object in a flow is D, velocity U, density p, and viscosity.

Re = ρDU / η

If the feeding time is shorter than 1 × 10 ⁻³ seconds, the mixing is not sufficient and the uniformity of the phosphor particles is lowered.

In this invention, it is preferable to adjust the suspension containing a silicon compound beforehand. The adjustment in the present invention means that the particle size and the dispersion state in the suspension containing the silicon compound are adjusted beforehand to obtain a desired state. As an example of the adjustment method, a combination of the stirring speed and the time for the suspension containing the silicon compound may be used, and as a more effective method, it is preferable to ultrasonically disperse the suspension containing the silicon compound. In that case, surfactant and a dispersing agent can also be added as needed. Moreover, adjustment is preferable at 50 degrees C or less of solution temperature, Preferably it is 30 degrees C or less, More preferably, it is 10 degrees C or less in order to prevent the viscosity rise by reaggregation of a silicon compound. As a coagulation particle diameter, it is preferable to adjust to 1 micrometer or less, Preferably it is 0.5 micrometer or less, More preferably, it is 0.1 micrometer or less in order to obtain a micro fluorescent substance.

In addition, in this invention, the colloidal silica manufactured by the particle size and dispersion state in suspension can also be used. The colloidal silica is preferably anionic, and the particle diameter thereof is preferably 1 µm or less, preferably 0.5 µm or less, more preferably 0.1 µm or less, in order to obtain a microphosphor.

In the method of the present invention, in order to make a mixture containing a suspension containing a silicon compound and a solution containing a metal compound capable of forming a silicate-based phosphor by firing, it is directly dried or insoluble if necessary. It is preferable to remove phosphorus salts by existing methods, for example, filtration washing with water, membrane separation, and the like, and thereafter to separate the solids from the liquid by methods such as filtration and centrifugation, followed by drying. The drying temperature is preferably in the range of 20 to 300 ° C, more preferably 90 to 200 ° C. As a method of direct drying, evaporation and spray drying drying while granulating are mentioned.

Next, any method can be used for baking the precursor of a silicate-based phosphor, and for example, a desired phosphor can be obtained by filling a precursor into an alumina boat and baking at a predetermined temperature in a predetermined gas atmosphere. For example, when firing the precursor of the green phosphor (Zn ₂ SiO ₄ : Mn, etc.), it is preferable to bake 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. If necessary, an atmospheric atmosphere (or an oxygen atmosphere) and a reducing atmosphere may be combined. When combining a reducing atmosphere, it is preferable to bake at the temperature of 800 degrees C or less in order to prevent the evaporation of zinc in a crystal | crystallization. As a method of obtaining a reducing atmosphere, there may be mentioned a method of placing a graphite mass in a filled boat of a precursor, baking in a nitrogen-hydrogen atmosphere, or a rare gas or hydrogen atmosphere. Water vapor may be contained in these atmospheres. The silicate-based phosphor obtained after firing may be subjected to treatment such as dispersion, washing with water, drying and sieving.

In this invention, it is preferable to use a precipitant as needed, and an organic acid or alkali hydroxide is preferable as a precipitant used at this time.

As an organic acid, the organic acid which has a -COOH group is preferable, For example, oxalic acid, formic acid, acetic acid, tartaric acid, etc. are mentioned. In particular, when oxalic acid is used, it is easy to react with cations of Zn, Mn, Mg, Ca, Sr, Ba, Y, Zr, Al, Ga, La, Ce, Eu, Tb, and Zn, Mn, Mg, Ca, Sr It is more preferable because cations of, Ba, Y, Zr, Al, Ga, La, Ce, Eu, and Tb tend to precipitate as oxalates. Moreover, what produces | generates oxalic acid by hydrolysis etc. as a precipitant, for example, dimethyl oxalate etc. can also be used.

The alkali hydroxide in the present invention may be any of those having an -OH group or reacting with water to form a -0H group or a -OH group by hydrolysis, for example, ammonia, sodium hydroxide or potassium hydroxide. Although urea etc. are mentioned, Preferably, ammonia which does not contain an alkali metal is preferable.

In addition, the precursor prepared in this invention is dried by filtration separation using suitable means, such as centrifugation. Thereafter, firing is carried out in a specific atmosphere to produce a phosphor. At this time, as a preferable aspect, an oxidizing atmosphere (for example, nitrogen-oxygen (21%)) baking is performed in 1000 to 1400 degreeC. In addition, by appropriately changing the firing atmosphere, time, temperature, firing frequency, etc., the concentration of the europium on the particle surface can be controlled to a desired concentration. For example, a method of firing an oxidizing atmosphere (for example, nitrogen-oxygen (21%)) in a high temperature region around 1200 to 1400 ° C., and then performing an inert atmosphere firing at a low temperature around 800 to 1000 ° C. is preferable. It is one aspect.

It is also preferable to wash the phosphor obtained by firing with an acid and then dry it. By acid washing, the improvement of the luminescence brightness considered to be caused by the change of a particle surface state, the dissolution of the impurity etc. which entered in the baking process is seen. Although there is no restriction | limiting in particular about the kind of acid, Inorganic acids, such as hydrochloric acid, nitric acid, and a sulfuric acid, are mentioned. In addition, formic acid, acetic acid, butyric acid, palmitic acid, stearic acid, acrylic acid, methacrylic acid, oleic acid, linoleic acid, linolenic acid, oxalic acid, adipic acid, maleic acid, fumaric acid, lactic acid, malic acid, tartaric acid, benzoic acid, salicylic acid, phthalic acid And carboxylic acids such as propionic acid, isobutyric acid, valeric acid, pivalic acid, lauric acid, myristic acid, propiolic acid and crotonic acid are also effective. The acid concentration, the washing time, the temperature, and the like also depend on the method for producing the phosphor, but it is preferable to stir and wash for 5 to 60 minutes at approximately 0.01 to 1 rule, and to treat it at around 20 to 30 ° C.

The phosphor of the present invention is a device such as a fluorescent lamp, a fluorescent display tube, a plasma display panel (PDP), or a display such as a fluorescent paint, an ashtray, a guide plate or an inductive material, a seal, a stationery, an outdoor article, a safety sign or the like. It is preferable to use for use articles.

In synthesizing the precipitate in the reaction apparatus, it is common to configure the apparatus with stainless steel piping. However, when stainless steel piping is used, a problem often occurs that the luminous efficiency of the phosphor is reduced.

As a result of earnestly examining by the present inventors, since the hardness of a fluorescent substance precursor was high, it discovered that the container and the stirring blades were abrasion during stirring, and it was a problem that stainless powder mixed in a precursor. When firing the precursor in which the stainless powder is mixed in this way, it is evident that Na, Fe, Cr, Ni, Mo, Ti, Nb, etc. are mixed inside the phosphor crystal, which adversely affects the performance of the phosphor. For this reason, it is preferable to coat the inside of stainless piping with Teflon (trademark), or it is more preferable to comprise the piping itself by resin, such as polypropylene.

It is preferable that the average particle diameter of fluorescent substance is 1 micrometer or less, It is more preferable that it is 0.8 micrometer or less, It is most preferable that it is 0.5 micrometer or less.

The coefficient of variation is the standard deviation of the particle size divided by the average particle diameter. It is preferable that the variation coefficient of fluorescent substance particles is 50% or less, It is more preferable that it is 30% or less, It is most preferable that it is 15% or less.

(1) Preparation of Phosphor S1 (see FIG. 1)

2000 ml of pure water was called A liquid, and colloidal silica containing 45 g of silicon dioxide and 219 g of ammonia water (28%) were mixed in pure water to adjust the liquid amount to 500 ml. In addition, 424 g of zinc nitrate hexahydrate (manufactured by Kanto Chemical Co., Ltd., purity 99.0%) and 21.5 g of manganese nitrate hexahydrate (manufactured by Kanto Chemical Co., Ltd., purity 98.0%) were dissolved in pure water to make the amount 500 What was adjusted to ml was called C liquid. A liquid was poured into the stainless reaction container 1 of FIG. 1, the temperature was maintained at 40 degreeC, the stirring was performed at 900 rpm using the stirring blade of diameter 5cm, and the Reynolds number was 0.0375. In the same state, B liquid and C liquid, which were kept at 40 ° C. in the same state, were subjected to constant velocity addition at a rate of 60 ml / min from the liquid level of the container containing A liquid. The precipitate obtained by the reaction was subjected to pressure filtration to solid-liquid separation. Subsequently, it dried at 100 degreeC for 12 hours, and obtained the dried precursor. Next, the obtained precursor was calcined at 1200 ° C for 3 hours in an atmosphere of 100% nitrogen to obtain phosphor S1 as a comparative example. In addition, the Reynolds number Re can be controlled by controlling the flow rate and the pipe diameter of the mixing section. The tube diameter of the mixing portion is preferably 0.1 mm to 51 nm, more preferably 0.5 mm to 10 mm. The flow rate is preferably 0.5 to 30 L / min. 0.005-5.0 mol / L is preferable and, as for the density | concentration of the liquid to mix, 0.1-0.10 mol / L is more preferable.

(2) Preparation of Phosphor S2 (see FIG. 2)

A colloidal silica containing 45 g of silicon dioxide and 219 g of ammonia water (28%) were mixed in pure water to adjust the liquid amount to 1500 ml. At the same time, 424 g of zinc nitrate hexahydrate (manufactured by Kanto Chemical Co., Ltd., purity 99.0%) and 21.5 g of manganese nitrate hexahydrate (manufactured by Kanto Chemical Co., Ltd., purity 98.0%) were dissolved in pure water, and the liquid amount was 1500 ml. What was adjusted to be referred to as "B liquid."

After the liquids A and B were kept at 40 ° C., a stainless Y-shaped reaction was carried out at an addition rate of 1800 ml / min using the roller pump 10 as the first liquid feeding means and the roller pump 11 as the second liquid feeding means. The apparatus 12 was supplied. In the Y-shaped reaction device 12, as illustrated, the first flow passage 13 to which the A liquid is supplied, the second flow passage 14 to which the B liquid is supplied, and the A liquid and the B liquid are mixed to form a flow of the mixed liquid. The third flow path 15 is provided. The precipitate obtained by the liquid reaction discharged | emitted from the 3rd flow path 15 and contained in the liquid accumulated in the container 16 was subjected to pressure filtration, and solid-liquid separation was carried out. Subsequently, it dried at 100 degreeC for 12 hours, and obtained the dried precursor. Next, the obtained precursor was calcined at 1200 ° C. for 3 hours in an atmosphere of 100% nitrogen to obtain phosphor S2 according to the present invention. In this case, the tube diameter is 1 mm and the Reynolds number is 38274.

(3) Preparation of Phosphor S3 (see FIG. 2)

A colloidal silica containing 45 g of silicon dioxide and 219 g of ammonia water (28%) were mixed in pure water to adjust the liquid amount to 1500 ml. At the same time, 424 g of zinc nitrate hexahydrate (manufactured by Kanto Chemical Co., Ltd., purity 99.0%) and 21.5 g of manganese nitrate hexahydrate (manufactured by Kanto Chemical Co., Ltd., purity 98,0%) were dissolved in pure water. What was adjusted to 1500 ml was called B liquid.

Y-shaped reaction in which A and B liquids were kept at 40 ° C, and then Teflon (registered trademark) coding was applied to the stainless steel shown in FIG. 2 using a roller pump (10) or (11) at an addition rate of 1800 ml / min. The apparatus 12 was supplied. The precipitate obtained by the reaction was diluted with pure water, and then filtered under reduced pressure to separate solid and liquid. Subsequently, 100 degreeC was dried for 12 hours and the dried precursor 3 was obtained. Next, the obtained precursor was calcined at 1200 ° C. for 3 hours in an atmosphere of 100% nitrogen to obtain phosphor S3 according to the present invention.

[evaluation]

The luminescence intensity, afterglow time and composition were analyzed for the phosphors S1 to S3 obtained in the above (1) to (3).

1. Evaluation of luminescence intensity

The phosphors S1 to S3 were irradiated with ultraviolet rays using an excimer 146 nm lamp (manufactured by Ushio Denki Co., Ltd.) in a vacuum chamber of 0.1 to 1.5 Pa, respectively, to emit green light from the phosphor. Next, the intensity | strength of the obtained green light was measured using the detector MCMC-3000 (made by Otsuka Denshi Co., Ltd.). In addition, the peak intensity of luminescence was obtained by a relative value of phosphor S1 as 100. Table 1 shows the results obtained together with the average particle diameter of the phosphor.

2. Composition Analysis

The composition of the phosphor was quantitatively determined by alkali melting for silicon and inductively coupled plasma emission spectroscopy after dissolution with hydrofluoric acid for elements other than silicon.

In the alkali melting method, 0.1 g of each phosphor was weighed in a platinum crucible, and then 2.5 g of sodium carbonate (made by Wako Junyaku Co., Ltd.) was added and melted at 1000 ° C. in an electric furnace for 1 hour. If there is an insoluble matter, it is filtered appropriately and then fixed to 50 ml. A solution obtained by dissolving only 2.5 g of sodium carbonate separately was prepared, and a standard concentration solution was prepared by adding the Kanto Chemical Co., Ltd. silicon standard stock solution (for atomic absorption spectrometry).

Dissolution by hydrofluoric acid was measured by weighing 0.1 g of each phosphor in a Teflon (registered trademark) beaker, followed by heating and drying by adding 10 ml of hydrofluoric acid (Ultra Pure Purity, Kanto Chemical). After repeating this twice, 10 ml of nitric acid (Kanto Chemical Co., Ltd. high purity) was added, dissolved, and 50 ml was used. This is called test liquid.

Seiko Denshi Kogyo Inductively Coupled Plasma Emission Spectrometer SPS4000 or VG Elemental Inductively Coupled Plasma Mass Spectrometer QP-Ω was used for qualitative and quantitative determination of elements. At the time of quantification, a standard concentration solution prepared by Kanto Chemical Co., Ltd. and a nitric acid (ultra high purity Kanto Chemical Co., Ltd.) was prepared separately and quantitatively determined by a calibration curve method.

Table 1 shows the impurity contents other than the phosphor composition. From Table 1, it was obtained that the phosphor of the present invention had a short afterglow time and improved luminescence intensity.

As a result of obtaining a phosphor having improved luminescence intensity by the invention of any of the structures 1 to 9, it is possible to increase the intensity of green with high visibility and to improve the white luminance of the full color PDP.

According to the invention of Configuration 4 or 5, as a result of preventing elution of impurities such as sodium and iron from abrasion from the reaction vessel, it is possible to produce a phosphor having a high luminescence intensity in which a decrease in luminescence intensity by these impurities is prevented. It becomes possible.

According to the invention of the constitution 8, a phosphor having a uniform particle size is produced to produce a phosphor of uniform quality.

By the invention of the structure 9, the phosphor which has little content of the impurity which reduces light emission intensity, and has high light emission intensity is manufactured.

Claims (9)

A method for producing a silicate-based phosphor precursor by a suspension containing a silicon compound and a solution containing a metal compound, wherein the suspension of the first flow path and the solution of the second flow path are continuously mixed, and the ray is discharged in the third flow path. A method for continuously discharging from the third flow path after forming a flow of a mixed solution of Nod water 3 × 10 ³ to 1 × 10 ⁶ . A first flow path means for sending the liquid to the first flow path, the first flow path, the second flow path, the second flow path means for sending the liquid to the second flow path and a third flow path extending from the confluence of the first and second flow paths And the first and second liquid feeding means each supply a suspension containing a silicon compound in the first flow path and a solution containing a metal compound forming a silicate-based phosphor precursor together with the silicon compound in the second flow path. By continuously sending the suspension and the solution to the third flow path, and continuously forming the flow of the mixed solution of Reynolds number 3 × 10 ³ to 1 × 10 ^{6 in} the ^third flow path. An apparatus for producing a silicate-based phosphor precursor discharged from a third flow path. A silicate-based phosphor precursor produced by the production method according to claim 1. The method for producing a silicate-based phosphor precursor according to claim 1, wherein at least the third flow path is made of a material having less abrasion with respect to the suspension, the solution, and the mixed solution. 3. The apparatus for producing a silicate-based phosphor precursor according to claim 2, wherein at least said third flow path is made of a material having low abrasion with respect to the suspension, the solution, and the mixed solution. The method for producing a silicate-based phosphor according to claim 1, wherein after releasing the discharged liquid, the phosphor precursor obtained by releasing the liquid is calcined. The silicate-based phosphor produced by the production method according to claim 6. 8. The silicate-based phosphor according to claim 7, wherein the average particle diameter is 1 µm or less and the variation coefficient of the particles is within 50%. The silicate-based phosphor according to claim 7 or 8, wherein the total content of sodium and iron is 100 ppm or less.

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