JP2003171661A - Method for producing phosphor and phosphor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a phosphor which can be produced by using a liquid phase method, has a small particle diameter and, simultaneously, a narrow particle diameter distribution, and furthermore has a good light emission intensity. <P>SOLUTION: In the method for producing a phosphor to which a liquid phase method is applied, the method comprises a desalting step between the initiation and the completion of forming a precursor. Further, the desalting is preferably carried out by the ultrafiltration treatment. In the method for producing a phosphor to which a liquid phase method is applied, the electric conductivity at least at the time of completing the formation of a precursor is controlled in the range of 0.01-20 mS/cm. In the phosphor produced by the above method, the electric conductivity after firing is in the range of 0.01-5 mS/cm. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a precursor produced by a liquid phase method, a phosphor produced from 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 in a predetermined amount and baked to cause a solid-solid reaction,
A liquid phase in which a solution containing an element forming the phosphor matrix and a solution containing an activator element are mixed 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 increase 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. Although it has been attempted to atomize the phosphors by a treatment such as pulverization after forming the phosphors, there are problems such as damage to the phosphor particles and a wide 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 formed and then fired to obtain a phosphor, which has a particle size distribution and a luminescent property. The properties of s are largely dependent on the properties of the precursor. For that reason,
It is necessary to consider the control of the particle size distribution of the precursor and the exclusion of impurities.

However, the particle size of the phosphor obtained by the liquid phase method is extremely small, which makes washing and solid-liquid separation difficult, and it is difficult to control the particle size and particle size distribution. There was a problem that impurities were mixed in.

Therefore, although many improved methods for producing a phosphor by the liquid phase method have been proposed, various performances of the phosphor,
Particularly, in terms of improving the emission intensity, a sufficient improvement method has not necessarily been obtained. For example, Japanese Patent Laid-Open No. 2001-172627
No. 3, pp. 187-242, regarding a method for producing a rare earth phosphate phosphor, a solution in which ions of rare earth elements and phosphate ions coexist is specified.
There is a description that it is added to a solution having an H value to form a precursor. With this method, a high-purity composition can be obtained as compared with the solid-phase method, but it is difficult to form a fine particle phosphor, and further improvements have been desired to obtain desired performances.

[0007]

An object of the present invention is to provide a phosphor produced by using a liquid phase method, which has a small particle size, a narrow particle size distribution, and a good emission intensity. It is to provide a method for manufacturing a body.

[0008]

[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-mentioned object, and as a result, by controlling the production conditions of a precursor of the phosphor, It was possible to produce a phosphor having a small particle size and a narrow particle size distribution with a high yield. Furthermore, they have found that a phosphor having good emission intensity can be obtained, and completed the present invention.

The structure of the present invention is as follows. 1) A method for producing a phosphor, which comprises a desalting step between the start and the end of precursor formation in the method for producing a phosphor using a liquid phase method.

2) The method for producing a phosphor according to 1), wherein desalting is performed by ultrafiltration. 3) In the method for producing a phosphor using the liquid phase method, at least the electric conductivity at the end of precursor formation is 0.01 to 20.
A method for producing a phosphor controlled to a range of mS / cm.

4) The method for producing a phosphor according to 1) or 2), wherein the electrical conductivity at least at the end of precursor formation is controlled to be in the range of 0.01 to 20 mS / cm.

5) In the phosphor manufactured by the liquid phase method,
A phosphor having an electric conductivity of 0.01 to 5 mS / cm after firing.

6) A phosphor manufactured by the manufacturing method according to any one of 1) to 4), wherein the electric conductivity after firing is in the range of 0.01 to 5 mS / cm.

The present invention will be described in more detail below. First, a method for manufacturing the phosphor according to the present invention will be described.

In the present invention, the particle size is small and the particle size distribution is narrow by controlling the conditions for producing the precursor of the phosphor, particularly the desalting method and conditions from the start to the end of precursor formation. The phosphor could be produced in high yield.

As the method for producing the phosphor of the present invention, a solution containing an element constituting the phosphor matrix and a solution containing an activator element are mixed to form a precipitate of the precursor of the phosphor in the solution. A liquid phase method in which this precursor is solid-liquid separated and then calcined is preferably used.

The method for precipitating the precursor is not particularly limited, but it is preferable to add two or more phosphor raw material solutions into the poor solvent in order to produce a phosphor having a finer particle size and a narrow particle size distribution. Is a preferred embodiment. Further, it is more preferable to adjust various physical properties such as addition speed, addition position, stirring conditions, pH, etc., depending on the type of phosphor. Thus, monodisperse fine particles having a narrow particle size distribution with an average particle size of about 0.05 to 0.5 μm can be obtained.

The term "average particle size" as used herein means the length of the edges of particles when the particles are cubic or octahedral so-called normal crystals. Further, in the case of non-normal crystals, for example, in the case of spherical, rod-shaped or tabular grains, it means the diameter when considering a sphere equivalent to the volume of the grains.

The particles are preferably monodisperse.
The term “monodispersion” as used herein refers to a case where the monodispersity calculated 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, desalting is preferably performed from the start to the end of precursor formation. Desalting may be performed from the beginning to the end of precursor formation, or may be desalted at the end of precursor formation. Further, depending on the degree of reaction of the raw materials, the treatment may be performed for a certain period of time during the precursor formation, or may be performed a plurality of times.
The desalting method is not particularly limited, and any method can be applied. For example, a sedimentation desalting method, an electrodialysis method and various membrane separation methods are preferably applied, but it is particularly preferable to carry out an ultrafiltration treatment.

FIG. 1 shows a conceptual diagram of an example of the method for producing a phosphor according to the present invention. In FIG. 1, the reaction vessel 1 initially contains pure water 2. The agitation mechanism 3 is shown as having a rotatable shaft with blades attached, but the mechanism can be of any conventional shape. While operating the stirring mechanism, the phosphor raw material (matrix constituent element) solution A is introduced into the reaction vessel through the first introduction pipe 4, and at the same time, the phosphor raw material (inhibitor element) is introduced through the second introduction pipe 5. Pour solution B into the reaction vessel. Also, the first introduction pipe 4
Alternatively, the crystal nuclei previously generated in another reaction vessel may be added through the second introduction pipe 5, or may be performed by another mixer and continuously supplied to the reaction vessel.

The pouring nozzle position can be set at any position, but it is preferably set at a position where it is added into the liquid from the lower part of the reaction vessel. The volume of the substance contained in the reaction vessel can be adjusted by taking out a part of it through the external circulation line 6 (to the ultrafiltration unit 7) as shown in the figure. The ultrafiltration device
Impurities are separated as shown by drainage line 8 and the precursor is returned to the reaction vessel as shown by external circulation line 9. The external circulation lines 6 and 9, the ultrafiltration unit 7, and any other components not specifically described here that are obvious to a person skilled in the art, such as one or more valves, pumps or meters. They make up groups and these elements are collectively called the ultrafiltration loop.

In the present invention, it is desirable that the phosphor is manufactured so that the electrical conductivity at the end of precursor formation is at least 0.01 to 20 mS / cm. It is more preferably 0.01 to 10 mS / cm, and even more preferably 0.01 to 5 mS / cm. Even if the electric conductivity is less than 0.01 mS / cm, the effect is not particularly large,
Productivity will be low. If it exceeds 20 mS / cm, impurities and by-salts cannot be sufficiently removed, so that the particle size becomes coarse and the particle size distribution becomes wide, and the emission intensity deteriorates.

The solid-liquid separation method of the precursor is not particularly limited,
Decantation, centrifugation, suction filtration and the like are preferably used. The method for drying the precursor is also not particularly limited, and any method such as vacuum drying, gas stream drying, fluidized bed drying, spray drying and the like can be used.

In the present invention, the temperature and time during firing are not particularly limited and can be appropriately selected according to the type of phosphor.
Furthermore, the gas atmosphere during firing may be any of an oxidizing atmosphere, a reducing atmosphere or an inert atmosphere, and can be appropriately selected according to the purpose. The firing device is not particularly limited, and any device can be used. For example, a box furnace, a crucible furnace, a rotary kiln, etc. are preferably used.

A sintering inhibitor may or may not be added during firing. When it is added, it may be added as a slurry at the time of forming the precursor, or a method in which a powdery material is mixed with a dried precursor and fired is also preferably used. Furthermore,
The sintering inhibitor is not particularly limited and may be appropriately selected depending on the type of phosphor and firing conditions. For example, depending on the firing temperature range of the phosphor, metal oxide such as TiO ₂ is used for firing at 800 ° C. or lower, and SiO ₂ is used for firing at 1000 ° C. or lower.
Al ₂ O ₃ is preferably used for firing at 00 ° C. or lower.

The electric conductivity after firing is 0.01-5 mS /
It is desirable that the phosphor is manufactured in the range of cm.
It is more preferably 0.01 to 1 mS / cm, and even more preferably 0.01 to 0.5 mS / cm. The electrical conductivity after firing refers to the electrical conductivity of a filtrate obtained by dispersing 10 g of the phosphor in 1 liter of pure water for a certain period of time and then filtering.

Although it is desirable to wash the phosphor after firing, it is not always necessary to wash it. It is appropriately selected depending on the electric conductivity after firing.

The phosphor may be an organic substance or an inorganic substance as long as it can be produced by the liquid phase method, and it can be used without any particular limitation. Examples of organic phosphors that can be used include brilliant sulfofla.
vine FF, basic yellow HG, eo
sine, rhodamine 6G, rhodami
ne B, a fluorescent substance having a pyrene ring, sodium pyrene trisulfonate and 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. 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. Acid Red 52, C.I. I. Acid Red 92, C.I. I. Acid Red, C.I. I. Basic Violet 1, C.I. I. Basic Violet 3,
C. I. Basic Violet 7, C.I. I. Basic Violet 10, C.I. I. Basic Violet 14 and the like can be mentioned.

Examples of the inorganic fluorescent substance include, for example, Japanese Patent Laid-Open No.
-6410, 61-65226, 64-229.
No. 87, No. 64-60671, JP-A-1-16891.
No. 1, etc., fluorescent materials such as ZnS: Ag, C
aWO_Four, Y₂SiO_Five: Ce, ZnS: Ag, Ga, C
l, Ca₂B_FiveO₉Cl: Eu²⁺, BaMgAl₁₄O_{twenty three}:
Eu²⁺Blue-emitting inorganic fluorescent substances such as ZnS: C
u, Al, (Zn, Cd) S: Cu, Al, ZnS: C
u, Au, Al, Zn₂SiO_Four: Mn, ZnS: Ag,
Cu, (Zn, Cd) S: Cu, ZnS: Cu, Gd₂
O₂S: Tb, La ₂O₂S: Tb, Y2SiO5: C
e, Tb, Zn₂GeO_Four: Mn, CeMgAl ₁₁O₁₉:
Tb, SrGa₂S_Four: Eu²⁺, ZnS: Cu, Co, M
gO ・ nB₂O₃: Ce, Tb, LaOBr: Tb, T
m, La₂O₂S: Tb or other green-emitting inorganic fluorescent substance;
If Y₂O₃: Eu, YVO_Four: Eu, Y₂O₂S: Eu,
3.5MgO, 0.5MgF₂GeO₂: Mn, (Y, C
d) BO₃Examples include red light emitting inorganic fluorescent substances such as Eu.
It In addition, the fluorescent substances used for three-wavelength fluorescent substances,
Calcium halophosphate and the like can also be preferably used.

[0031]

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

Example 1 <Production of phosphor H-1> Pure water heated to 60 ° C. 333.
During 3 ml, strontium chloride (SrCl ₂ · 6H
₂ O) 133.3 g, europium nitrate (Eu (NO ₃ ))
₃ · 6H ₂ O) 2.2g was added and well stirred to completely dissolve. This solution is designated as A-1.

Next, pure water 333.3 heated to 60 ° C.
In ml, potassium dihydrogen phosphate (KH ₂ (PO ₄ ) ₄ )
0.8 g was added and thoroughly stirred to completely dissolve it. This solution is designated as B-1.

Separately from this, 28% ammonia water was gradually added to 333.3 ml of pure water to adjust the pH to 9.
Adjusted to 5. This solution is designated as C-1.

Next, A-1 and B-1 were simultaneously added to C-1 in the liquid at an addition rate of 1000 ml / min to form a precipitate. At this time, C was added together with A-1 and B-1.
Since the pH of -1 changes from moment to moment, ammonia water was added each time to adjust the pH of C-1 to be constantly maintained at about 9.5.

The resulting precipitate was filtered to remove the solid content and then dried at 120 ° C. for 6 hours to obtain a dried precursor 78.4.
g was obtained. The composition of the generated precursor is Sr _9.9 (P
O _{4) 6} Cl _2: it was Eu ³⁺ _0.1.

Next, 50 g of the precursor and alumina (Al
₂ O ₃ ) 0.25g is mixed well and put in a quartz crucible.
% At 3 at 1050 ° C. under nitrogen gas atmosphere containing 3% hydrogen
Burned for hours. The obtained fired product was used as a comparative phosphor H-1. The composition of H-1 is Sr _9.9 (PO ₄ ) ₆ Cl ₂ : Eu ²⁺
It was _0.1 .

<Production of Phosphor K-1> In C-1, A-
1 and B-1 simultaneously at an addition rate of 1000 ml / min
Addition in liquid produced a precipitate. At this time, A-1 and B-
Since the pH of C-1 changed with the addition of 1,
Always add ammonia water at the same time to constantly adjust the pH of C-1 to approx.
Adjusted to 9.5. Then, the resulting precipitate is
Electric conductivity reaches 30 mS / cm by cantation
Washed to dryness, filtered and dried at 120 ° C for 6 hours.
As a result, 75.4 g of a dried precursor was obtained. Precursor generated
The composition of Sr _9.9(PO_Four)₆Cl₂: Eu³⁺ _0.1And
It was

Next, 50 g of the precursor and alumina (Al
₂ O ₃ ) 0.25g is mixed thoroughly and put in a quartz crucible,
Baking was performed at 1050 ° C. for 3 hours in a nitrogen gas atmosphere containing 5% hydrogen. The obtained fired product was used as the phosphor K- of the present invention.
Set to 1. The composition of _{K-1 Sr 9. 9 (PO} 4) 6 Cl 2: E
It was u ²⁺ _0.1 .

<Preparation of Phosphor K-2> Instead of decantation, the obtained precipitate was washed by an ultrafiltration device (ultrafiltration membrane: NTU-315 manufactured by Nitto Denko) as shown in FIG.
Perform the same method as K-1 except that
The phosphor K-2 of the present invention was obtained.

<Preparation of Phosphor K-3> In C-1, A-
1 and B-1 were added to the liquid, and at the same time, the above ultrafiltration device was activated so that the amount of liquid passing through the ultrafiltration membrane was 200 ml / m 2.
The cleaning was performed while controlling to be in. At this time, 200
Ammonia water was added to C-1 at an addition rate of ml / min to control the amount of liquid passing through the membrane and the amount of ammonia water to be equal, and the pH to be 9.5. Otherwise, the same method as in K-1 above was carried out to provide the phosphor K- of the present invention.
Got 3.

<< Evaluation of Phosphors >> Phosphors H-1 and K-1
~ 3 average particle size, particle size distribution (monodispersity) and 365 nm
The emission intensity when irradiated with the ultraviolet rays of was measured. The average particle size and particle size distribution were calculated from the particle size of each particle by randomly selecting 200 particles from the particle photograph obtained by TEM photography.

The emission intensity is measured by a fluorescence photometer (HITAC
HI: F3010), excitation wavelength 365 nm,
The measurement was performed under the condition of the measurement temperature of 25 ° C. The emission intensity is shown as a relative value when the emission intensity of H-1 is 100%.

The results are shown in Table 1.

[0045]

[Table 1]

The phosphor of the present invention has a smaller particle size, a narrower particle size distribution, and higher emission intensity than the comparative phosphor.

Example 2 <Production of Phosphor K-4> Phosphor K-4 was obtained in the same manner as phosphor K-3 except that the electric conductivity was changed to 18 mS / cm.

<Preparation of Phosphor K-5> Electric conductivity of 5 m
Phosphor K-5 was obtained in the same manner as in phosphor K-3 except that S / cm was changed.

<Preparation of Phosphor K-6> The electric conductivity is set to 0.
A phosphor K-6 was obtained in the same manner as the phosphor K-3, except that the phosphor K-6 was changed to 8 mS / cm.

<Preparation of Phosphor K-7> The electric conductivity was set to 0.
A phosphor K-7 was obtained in the same manner as the phosphor K-3, except that the phosphor K-7 was changed to 1 mS / cm.

<< Evaluation of Phosphor >> By the same method as in Example 1, the average particle size, the particle size distribution and the emission intensity were measured. The results are shown in Table 2.

[0052]

[Table 2]

The phosphor of the present invention is excellent in any evaluation. The emission intensity increases as the values of the average particle size and the particle size distribution decrease.

Example 3 <Preparation of Phosphor K-8> An aqueous dispersion containing phosphor K-3 was washed by decantation until the electric conductivity reached 8 mS / cm, filtered and heated at 120 ° C. for 1 hour. It was dried to obtain a phosphor K-8.

<Preparation of Phosphor K-9> An aqueous dispersion containing phosphor K-3 was decanted to have an electrical conductivity of 4 m.
It was washed until it reached S / cm, filtered, and dried at 120 ° C. for 1 hour to obtain phosphor K-9.

<Preparation of Phosphor K-10> An aqueous dispersion containing phosphor K-3 was washed by decantation until the electric conductivity reached 0.3 mS / cm, filtered, and filtered.
It was dried at 0 ° C. for 1 hour to obtain phosphor K-10.

<< Evaluation of Phosphor >> The average particle size, particle size distribution and emission intensity were measured by the same method as in Example 1. The results are shown in Table 3.

[0058]

[Table 3]

The phosphor of the present invention was excellent in all evaluations, and the same tendency as in Table 2 was observed.

[0060]

According to the present invention, it is possible to provide a phosphor having a small particle size, a narrow particle size distribution, and good emission intensity.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a method for producing a phosphor of the present invention.

[Explanation of symbols]

Solution of phosphor matrix constituent elements B activator element solution 1 reaction vessel 2 pure water 3 stirring mechanism 4 First introduction tube 5 Second introduction pipe 6,9 External circulation line 7 Ultrafiltration unit 8 drainage lines

   ─────────────────────────────────────────────────── ─── 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 (72) Inventor Tokiko Hoshino             Konica Stock Market, 1 Sakura-cho, Hino City, Tokyo             In-house F-term (reference) 4H001 CA01 CA02 CF02 XA08 XA15                       XA17 XA38 YA63

Claims (6)

[Claims] 1. A method for producing a phosphor using a liquid phase method, which comprises a desalting step between the start and the end of precursor formation. 2. The method for producing a phosphor according to claim 1, wherein desalting is performed by ultrafiltration. 3. A method for producing a phosphor using a liquid phase method, wherein the electrical conductivity is at least 0.
A method for producing a phosphor, wherein the phosphor is controlled in a range of 01 to 20 mS / cm. 4. The method for producing a phosphor according to claim 1, wherein the electrical conductivity at least at the end of precursor formation is controlled in the range of 0.01 to 20 mS / cm. 5. A phosphor produced by a liquid phase method, which has an electric conductivity of 0.01 to 5 mS / cm after firing. 6. The phosphor manufactured by the manufacturing method according to claim 1, wherein the electric conductivity after firing is in the range of 0.01 to 5 mS / cm. Fluorescent substance.