JP2003261867A - Manufacturing method for fluorescent material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a fine particulate fluorescent material having a narrow particle size distribution and good luminous intensity using a liquid phase method. <P>SOLUTION: The fluorescent material is manufactured by a method wherein a solution containing constituent metal elements of the fluorescent material is preliminarily prepared, a precursor suspension of the fluorescent substance is manufactured by the liquid phase method to be discharged into a gaseous atomosphere as fine liquid drops and these fine liquid drops are dried and heated. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a precursor of a phosphor produced by a liquid phase method, a phosphor produced by the precursor, and a technique for producing the phosphor.

[0002]

2. Description of the Related Art As a method for producing a phosphor, a solid phase method in which a compound containing an element constituting a phosphor matrix and a compound containing an activator element are mixed together in a predetermined amount and baked to carry out an inter-solid reaction, A liquid phase in which a solution containing an element constituting the phosphor matrix and a solution containing an activator element are mixed together to generate a precipitate of a precursor of the phosphor in the solution, and the precursor is solid-liquid separated and then baked. There is a law.

In order to improve the yield and luminous efficiency of the phosphor, it is necessary to make the composition of the phosphor as close to the stoichiometric composition as possible. Furthermore, the specific surface area increases as the particle size of the phosphor is reduced, so that the ratio contributing to light emission increases. It is difficult to produce a phosphor having a purely stoichiometric composition by the solid phase method, and as a result of the reaction between solids, excess impurities that do not react and side salts generated by the reaction remain, resulting in stoichiometry. It is difficult to obtain a high-purity phosphor.
Further, it is difficult to reduce the particle size because of the reaction between solids. Attempts have been made to reduce the size of the phosphor by a process such as crushing after forming the phosphor, but there are problems such as damage to the phosphor particles and a broad particle size distribution. The liquid phase method is more suitable than the solid phase method in order to obtain a fine particle fluorescent material having a uniform composition and high purity.

In the case of producing a phosphor by the liquid phase method, first, a precipitate which is a precursor of the phosphor is generated, and the precipitate is solid-liquid separated, dried, and then baked to obtain a phosphor. JP-A-9
No. 71415 describes a method of dispersing and suspending a rare earth oxalate produced by a coprecipitation method in water, spray-drying the mixture, and then firing a dried precursor to produce a phosphor.
However, if a box type furnace, a material stationary type such as a crucible furnace, or a material rotating type such as a rotary kiln that is used as a conventional firing method is used, fusion or adhesion between materials during firing, material-to-apparatus However, even though a fine and highly pure precursor is obtained by the liquid phase method, there are problems that the phosphor particles are coarsened by firing and the desired emission intensity cannot be obtained. Yes, and improvement was desired.

Further, in Japanese Patent Laid-Open No. 2001-107042, a solution containing a constituent metal element of a phosphor prepared in advance is made into fine liquid droplets by an ultrasonic atomizer or the like and heated in a pyrolysis reaction furnace to produce the phosphor. Although there is a description of a method for producing a fine particle, this method shows coarsening of the particles and widening of the particle size range as the concentration of the droplet is increased. I had no choice but to do it. However, if the concentration of the constituent metal elements is lowered, there is a problem that the amount of water brought in during spraying is too large, resulting in poor drying or poor crystallization, and both high productivity and high emission intensity of the fine particle phosphor are achieved. It wasn't enough to do it.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a fine particle phosphor having a narrow particle size distribution and good emission intensity by using a liquid phase method.

[0007]

Means for Solving the Problems The inventors of the present invention have made earnest studies on a method for producing a phosphor by a liquid phase method in order to achieve the above object, and as a result, have found that the particle size distribution is narrow and that the emission intensity is good. The inventors have found that a fine particle phosphor can be obtained, and completed the present invention. The above object of the present invention has been achieved by the following configurations.

1. A solution containing the constituent metal elements of the phosphor is prepared in advance, a precursor suspension of the phosphor is manufactured by a liquid phase method, and the precursor suspension is discharged as fine droplets into a gas atmosphere. A method for producing a phosphor, which comprises drying and heating the droplets.

2. 2. The method for producing a phosphor according to the above 1, wherein the precursor suspension is subjected to a wet dispersion treatment to form a precursor dispersion, and then the droplets are discharged as fine droplets into a gas atmosphere.

3. A solution or suspension containing a constituent metal element of the phosphor is prepared in advance using a solvent containing a low-boiling organic solvent, and the solution or suspension is baked by a spray method. Production method.

4. An aqueous solution containing a constituent metal element of the phosphor is prepared in advance, a precursor suspension of the phosphor is produced from the aqueous solution by a reaction crystallization method, and a low boiling point organic solvent is contained after a drying step. A method for producing a phosphor, which comprises forming a solution or suspension using a solvent, and firing the solution or suspension by a spray method.

5. 5. The method for producing a phosphor according to the above 4, wherein the precursor dispersion liquid is subjected to a wet dispersion treatment using a solvent containing a low boiling point organic solvent, and then the precursor dispersion liquid is baked.

6. A method for producing a phosphor, characterized in that a solution or suspension containing a constituent metal element of the phosphor is prepared in advance, and when the solution or suspension is pyrolyzed by spraying, it is carried out in the presence of a sintering inhibitor. .

7. 6. The method for producing a phosphor according to any one of 1 to 5 above, wherein at least one step is performed in the presence of a sintering inhibitor.

The method for producing the phosphor used in the present invention will be described in more detail below. In the present invention, a fine particle phosphor having high productivity and good emission intensity is used by using a manufacturing method in which a precursor manufactured by a liquid phase method is sprayed in a gas atmosphere as fine droplets and dried and heated. Can now be provided.

As the method for producing the phosphor of the present invention, a solution containing the constituent metal elements of the phosphor is mixed to form a precursor of the phosphor in the solution, and then fine droplets containing the precursor are mixed. Is sprayed in a specific gas atmosphere. At this time, the precursor may be once dried, suspended in a low boiling point solvent and then sprayed. Further, in the present invention, a more preferable form is that the precursor suspension is wet-dispersed and then sprayed.

In the present invention, it is preferable to use the liquid phase method as the method for producing the precursor. The coprecipitation method may be used, or the sol-gel method may be used, depending on the type and application of the phosphor. In the coprecipitation method, adding two or more liquids of the phosphor raw material into the poor solvent is a preferable mode for producing a phosphor having a finer and narrow particle size distribution.

At this time, in order to obtain the kind of the phosphor and the desired performance, it is more preferable to adjust various physical properties such as the addition speed, the addition position, the stirring condition, and the pH. For example, when strontium phosphate-based composite oxide is used for the mother crystal and europium is used as the activator, two solutions of an aqueous solution in which strontium chloride and europium nitrate are dissolved and an aqueous solution of ammonium dihydrogen phosphate are used.
When the solution is added to the pure water mother liquor at 60 ° C in the high-speed liquid, the pH
When the mother liquor is controlled to 6 and the two liquids are mixed, Sr ₁₀ (PO ₄ ) ₆
Cl ₂ precipitates, but when mixed at pH 10, Sr
A precipitate of ₁₀ (PO ₄ ) ₆ (OH) ₂ is produced. Further, according to this method, monodisperse fine particles having a narrow particle size distribution with an average particle size of about 0.05 μm to 1 μm can be obtained.

In the case of spherical, rod-shaped, or tabular particles, the average particle diameter shown here is the diameter of a sphere having the same volume as the particle.

The term "monodispersion" as used herein means that the degree of monodispersion obtained by the following formula is 40% or less. In the present invention, the monodispersity is more preferably 30% or less, particularly preferably 0.1 to 20%.

Monodispersity = (standard deviation of particle size) / (average value of particle size) × 100 In the present invention, the phosphor may be an organic substance or an inorganic substance as long as it can be produced by the liquid phase method as described above. Or may be used without particular limitation.

As the organic phosphor that can be used,
For example, brilliant sulfo flavi
ne FF, basic yellow HG, eos
ine, rhodamine 6G, rhodamine
e B, a fluorescent substance having a pyrene ring, sodium pyrene trisulfonate, sodium pyrene tetrasulfonate and their hydroxy-substituted products, amino-substituted products, acetamide-substituted products, C.I. I. Basic Red 1, C.I. I. Basic Red 2, C.I. I. Basic Red 9, C.I.
I. Basic Red 12, C.I. I. Basic Red 13, C.I. I. Basic Red 14, C.I. I. Basic Red 17, C.I. I. Acid Red 51, C.I.
I. Acid Red 52, C.I. I. Acid Red 9
2, C.I. I. Acid Red, C.I. I. Basic Violet 1, C.I. I. Basic Violet 3, C.I.
I. Basic Violet 7, C.I. I. Basic Violet 10, C.I. I. Basic violet 14
Etc.

Examples of the inorganic fluorescent substance include, for example, Japanese Patent Laid-Open No.
0-6410, 61-65226, 6
No. 4-22987, No. 64-60671, and
Fluorescent substances described in the publications such as Kaihei 1-168811,
For example, ZnS: Ag, CaWO_Four, Y₂SiO_Five: C
e, ZnS: Ag, Ga, Cl, Ca₂B_FiveO₉Cl: E
u ²⁺, BaMgAl₁₄O_{twenty three}: Eu²⁺Blue luminous inorganic firefly such as
Optical material, for example ZnS: Cu, Al, (Zn, Cd)
S: Cu, Al, ZnS: Cu, Au, Al, Zn ₂S
iO_Four: Mn, ZnS: Ag, Cu, (Zn, Cd)
S: Cu, ZnS: Cu, Gd₂O₂S: Tb, La₂O₂
S: Tb, Y₂SiO_Five: Ce, Tb, Zn₂GeO_Four: M
n, CeMgAl₁₁O₁₉: Tb, SrGa₂S_Four: E
u²⁺, ZnS: Cu, Co, MgO.nB₂O₃: Ce,
Tb, LaOBr: Tb, Tm, La₂O₂S: such as Tb
Green-emitting inorganic phosphor, eg Y₂O₃: Eu, YVO
_Four: Eu, Y₂O₂S: Eu, 3.5MgO, 0.5Mg
F₂GeO₂: Mn, (Y, Cd) BO₃: Red such as Eu
Examples include luminescent inorganic fluorescent substances. Also, three-wavelength fluorescent substance
Fluorescent substances used in, calcium halophosphate, etc.
Can also be preferably used.

In the present invention, it is preferable to spray the precursor suspension and / or dispersion as fine droplets. As a method of forming minute droplets, for example, a method of forming a droplet of 1 to 50 μm by sucking the liquid with pressurized air to form a droplet and a method of using ultrasonic waves of about 2 MHz from a piezoelectric crystal Method of forming droplets of 10 μm, method of vibrating an orifice having a hole diameter of 10 to 20 μm by a vibrator, supplying liquid at a constant speed thereto, and discharging droplets of 5 to 50 μm according to the frequency of vibration , The liquid is dropped on the rotating disk at a constant speed, and centrifugal force causes 20 to 1
Examples include a method of forming droplets of 00 μm and a method of applying a high voltage to the surface of the liquid to generate droplets of 0.5 to 10 μm.

In the present invention, the concentration of the precursor contained in the precursor suspension and / or dispersion is not particularly limited,
The preferred range is 0.01 mol / L or more 10
It is below mol / L. When the amount is 0.01 mol / L or less, the productivity is poor, and when the amount is 10 mol / L or more, coarse particles are likely to be formed.

The droplets formed by the above method are then introduced into the thermal decomposition reaction furnace together with a carrier gas, dried and heated to become phosphors. In order to obtain the type of phosphor and the desired characteristics, the type of solvent, the type of carrier gas, the flow rate of carrier gas, and the temperature in the thermal decomposition reaction furnace can be selected as necessary.

In the present invention, the solvent is preferably water or a low-boiling organic solvent having a boiling point lower than that of water. For example, alcohols such as ethanol and methanol are preferably used. In addition, a mixed solvent of water and a low boiling point organic solvent can be used without any problem.

In the present invention, the gas atmosphere in which the precursor-containing droplets are sprayed is not particularly limited, and may be any of an oxidizing atmosphere, a reducing atmosphere, or an inert atmosphere, and the type of phosphor main phase and light emission. It is appropriately selected according to the type of activator ion that contributes to. For example, when synthesizing a phosphor having an oxide as a main phase, air, oxygen, nitrogen, hydrogen, and nitrogen or argon containing a small amount of hydrogen are 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 or hydrogen containing hydrogen sulfide or carbon disulfide, or Argon and the like are preferred. Also, when Eu ³⁺ or the like, which is easy to maintain valence in an oxidizing atmosphere, is used as the activating ion,
Oxidizing gases such as air and oxygen are preferable, and when Eu ²⁺ or the like, which easily maintains the valence in a reducing atmosphere, is used as the activating ions, hydrogen or a reducing gas such as nitrogen or argon containing a small amount of hydrogen is preferable.

In the present invention, the temperature in the pyrolysis reaction furnace when spraying the precursor droplets is carried out at 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 will not proceed sufficiently, and if the residence time is too long, unnecessary energy will be consumed, which is not preferable in terms of cost.

In the present invention, it is more preferable to subject the precursor suspension to a wet dispersion treatment as a pretreatment to be introduced into the spray pyrolysis furnace. There is no particular limitation on the processing method,
High-speed stirrer, ball mill, sand mill, colloid mill,
A vibration mill and a homogenizer can be preferably applied. Moreover, you may add a dispersing agent etc. to this as needed.
For example, a method in which a precursor suspension obtained by the liquid phase method is prepared by adding a dispersant or the like, and then the prepared liquid is passed through a media mill filled with media to perform a mechanical dispersion treatment. Is mentioned. The time and energy required for the treatment are appropriately selected depending on the type of phosphor, desired performance, treatment amount, and the like.

In the present invention, it is more preferable to add a sintering inhibitor. It may be added as a slurry,
Further, powdery one may be added. Further, it may be added at the time of forming the precursor or may be added at the time of wet dispersion treatment. Further, the anti-sintering agent is not particularly limited and is appropriately selected depending on the kind of the phosphor and the desired performance. For example, when the temperature range for spraying the precursor-containing droplets is 800 ° C. or lower, T
Metal oxides such as io ₂ are SiO at 1000 ° C or lower.
₂ and Al ₂ O ₃ are preferably used at 1700 ° C. or lower.

The phosphor obtained by using the method of the present invention can be applied to a phosphor for a color television, but it is used for a fluorescent lamp, a plasma display panel (PDP), and a field. It can be preferably applied to phosphors for other purposes such as emission display (FED).

[0034]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

<< Preparation of (Y _0.95 Eu _0.05 ) ₂ O ₃ >> Comparative Example 1 Yttrium nitrate (Y (NO ₃ ) ₃ .6H ₂ O) 65.5
g and europium nitrate _{(Eu (NO 3) 3 ·} 6H 2 O)
4.0 g of each was dissolved in 500 ml of pure water to prepare a raw material solution C-1. Then, C-1 was sprayed into a 900 ° C. air atmosphere with raw material droplets by using a spray pyrolyzer (Model: RH-2, manufactured by Okawara Machinery Co., Ltd.), and allowed to stay for 20 seconds to cause phosphor H -1 was produced. The chemical composition of the H-1 was _{(Y 0.95 Eu 0.05) 2 O} 3.

Example 1 Yttrium nitrate was added to 250 ml of pure water heated to 40 ° C.
(Y (NO₃)₃・ 6H ₂O) 65.5 g and europium nitrate
Umm (Eu (NO₃)₃・ 6H₂O) 4.0g was added.
Stir well to dissolve completely. This solution is called A-1
It Then, oxalic acid was added to 250 ml of pure water heated to 40 ° C.
((COOH)₂・ 2H₂0) Add 34.0 g and stir well.
Stir to dissolve completely. This solution is designated as B-1.

Next, 100 ml of A-1 and B-1 were simultaneously added to 500 ml of pure water adjusted to pH 8 with ammonia.
Addition was performed in the liquid at an addition rate of ml / min to generate a precipitate. At this time, the pH changed every moment with the addition of A-1 and B-1.
Was always adjusted to 8 ± 0.5. A-1 and B-
1 was completely added to obtain a suspension D-1 containing a precursor.

Then, D-1 was sprayed into the air atmosphere at 900 ° C. in an air atmosphere by using a spray pyrolyzer (Model: RH-2 manufactured by Okawara Koki Co., Ltd.) and allowed to stay for 20 seconds. Phosphor K-1 was produced.

Example 2 The precursor-containing suspension D-1 was placed in a media type wet dispersion device (Model: SL-C12 manufactured by SC Adchem Co., Ltd.) before being charged into the spray pyrolysis device. 2500
Phosphor K-2 was produced by the same method except that the wet dispersion treatment was performed for 20 minutes at rpm.

Example 3 Before being charged into a spray pyrolysis apparatus, 450 ml of ethanol was mixed with dried precursor powder obtained by spray drying the above-mentioned precursor-containing suspension D-1 at 120 ° C. Precursor suspension D
-1 'was obtained. The obtained precursor suspension D-1 ′ was used as a media type wet dispersion device (manufactured by SSC Adychem Co., Ltd.).
Phosphor K by the same method except that wet dispersion treatment is performed at 2500 rpm for 20 minutes using a model: SL-C12).
-3 was produced.

Example 4 Alumina powder (Nippon Aerosil Co., Ltd.) during wet dispersion treatment
Phosphor K-4 was produced by the same method as K-3 except that 1% by mass of Aluminum Oxide C) manufactured by the same company was added for treatment.

<< Preparation of (Y _0.9 Eu _0.1 ) VO ₄ >> Comparative Example 2 Y (CH ₃ was added to 500 ml of ethanol heated to 50 ° C.
COCHCOCH _{3) 3} · 3H ₂ O of 10.6g and Eu
_{(CH 3 COCHCOCH 3) 3 ·} 2H 2 O-of 1.0g was added, and completely dissolved thoroughly stirring. This solution is A-2
And Then, 250m of methanol heated to 50 ° C
13.2 g of VO (CH ₃ COCHCOCH ₃ ) ₃ in 1
Was added and thoroughly stirred to dissolve completely. This solution is B
-Set to 2. Both solutions A-2 and B-2 were mixed and mixed well to form a uniform solution, and 70 ml of pure water was added dropwise over 30 minutes. At this time, since the pH changed every moment as pure water was dropped, ammonia water was added at each time so that the pH was constantly adjusted to 10 ± 0.5. After dropping, 60
The temperature was raised to ° C and aging was carried out for 10 hours to obtain a suspension D-2 containing a precursor.

Next, D-2 was washed with 300 ml of ethanol and then filtered to obtain a precursor cake. This precursor cake was dried at 65 ° C. for 12 hours, crushed in a mortar, placed in an alumina crucible, and placed in an electric furnace (manufactured by Motoyama Co., Ltd., model: SBT2025D) at 900 ° C. in an atmospheric atmosphere. Phosphor H-2 was produced by firing for a time.
The chemical composition of H-2 was (Y _0.9 Eu _0.1 ) VO ₄ .

Example 5 The above precursor-containing suspension D-2 was sprayed with a spray pyrolysis apparatus (Model: RH-2, manufactured by Okawara Koki Co., Ltd.) to form raw material droplets at 900 ° C. and 100% nitrogen gas. 2 in the atmosphere of
Phosphor K-5 was prepared by allowing it to stay for 0 seconds.

Example 6 The precursor-containing suspension D-2 was charged in a media type wet dispersion device (VMA-GETZ) before being charged into a spray pyrolysis device.
Mann GMBH model: DISPERMAT
A phosphor K-6 was produced in the same manner as in Example 5 except that the dispersion treatment was performed using SL-C12 EX) at 2500 rpm for 20 minutes.

<Evaluation of Phosphor> (Measurement of Luminous Intensity) Regarding phosphor powders H-1 to K-6,
The emission intensity when irradiated with 254 nm ultraviolet light was confirmed.

The emission intensity is measured by a fluorescence photometer (HITAC
Excitation wavelength 254n using HI F3010)
m, measurement temperature was measured at 25 ° C.

The emission intensities of the phosphors K-1 to K-4 of the present invention are shown as relative values when the emission intensity of the comparative phosphor H-1 is 100%. Phosphors K-5 to K- of the present invention
The emission intensity of 6 is 100% of that of the comparative phosphor H-2.
It was shown as a relative value when.

(Measurement of average particle size) Phosphor powders H-1 to K-
Six hundred particles were randomly selected from the electron micrograph of No. 6, and the average particle diameter of each of the phosphor powders H-1 to K-6 was determined.

(Measurement of Monodispersity) Phosphor powders H-1 to K-
Six hundred particles were randomly selected from the electron micrograph of No. 6, and the monodispersity of each of the phosphor powders H-1 to K-6 was determined.

The monodispersity shown here means that the monodispersity calculated by the following formula is 40% or less.

Monodispersity = (standard deviation of particle size) / (average value of particle size) × 100

[0053]

[Table 1]

As is clear from Table 1, the sample of the present invention is a fine particle phosphor having a narrow particle size distribution and good emission intensity.

[0055]

Industrial Applicability According to the present invention, a precursor produced by the liquid phase method is sprayed in a gas atmosphere as fine droplets, dried and heated, and a fine particle phosphor having a narrow particle size distribution and good emission intensity. Got

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takayuki Suzuki             Konica Stock Market, 1 Sakura-cho, Hino City, Tokyo             In-house (72) Inventor Naohiro Okada             Konica Stock Market, 1 Sakura-cho, Hino City, Tokyo             In-house F-term (reference) 4G048 AA03 AB02 AC08 AE07                 4G076 AA02 AB07 AB11 AB12 BA11                       DA11                 4H001 CA01 CF02

Claims (7)

[Claims] 1. A solution containing a constituent metal element of a phosphor is prepared in advance, and a precursor suspension of the phosphor is produced by a liquid phase method,
A method for producing a phosphor, characterized in that the precursor suspension is discharged as fine droplets into a gas atmosphere to dry and heat the droplets. 2. The phosphor according to claim 1, wherein the precursor suspension is subjected to a wet dispersion treatment to form a precursor dispersion, which is then discharged as fine droplets into a gas atmosphere. Production method. 3. A solution or suspension containing a constituent metal element of a phosphor is prepared in advance using a solvent containing a low-boiling organic solvent, and the solution or suspension is fired by a spray method. And a method for producing a phosphor. 4. An aqueous solution containing a constituent metal element of a phosphor is prepared in advance, a precursor suspension of the phosphor is produced from the aqueous solution by a reaction crystallization method, and after a drying step, a low boiling point is obtained. A method for producing a phosphor, which comprises forming a solution or suspension using a solvent containing an organic solvent, and firing the solution or suspension by a spray method. 5. The phosphor according to claim 4, wherein the precursor dispersion liquid is subjected to a wet dispersion treatment using a solvent containing a low boiling point organic solvent, and then the precursor dispersion liquid is fired by a spray method. Method. 6. A solution or suspension containing a constituent metal element of a phosphor is prepared in advance, and spray pyrolysis of the solution or suspension is performed in the presence of a sintering inhibitor. Method for manufacturing phosphor. 7. The method for producing a phosphor according to claim 1, wherein at least one step is performed in the presence of a sintering inhibitor.