JP2002327173A - Method for producing particulate luminous fluorescent powder and particulate luminous fluorescent powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing particulate luminous fluorescent powder having strong emission intensity and long emission time, excellent in water resistance and having narrow particle size distribution, and to provide particulate luminous fluorescent powder by using the method. SOLUTION: The precursor of luminous fluorescent powder is obtained by using Al(NO3 )3 .9H2 O as the raw material for constituent Al, Sr(NO3 )2 as the raw material for constituent Sr, Eu2 O3 as the raw material for constituent Eu and Dy2 O3 as the raw material for constituent Dy and adding a particulate refining agent before precipitating the raw materials from a solution mixed with the raw materials by coprecipitation method. The particulate refining agent is one or more selected from saccharose, glucose, starch and cellulose ether. And, the precursor is irradiated with a microwave and applied to solid state reaction so as to directly obtain luminous fluorescent powder of particulate (having 2-5 μm particle diameter). The compounding mole ratios of the raw materials are preferably adjusted within the following ranges. Sr(NO3 )2 :Al(NO3 )3 .9H2 O=1:1.5-4, Eu2 O3 :Dy2 O3 =1:1.5-3 and Sr(NO3 )2 :Eu2 O3 =1:0.001-0.02.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing finely particulate luminous fluorescent powder and a finely particulate luminous fluorescent powder obtained by the method.
The present invention relates to a method for producing a particulate phosphorescent phosphor powder obtained by irradiating the precursor of the phosphorescent phosphor powder with microwaves, and a particulate phosphorescent phosphor powder produced by the method. In the present specification, the luminous fluorescent powder refers to a material which is irradiated by the sun or another light source, stores light, emits light for a long time in a dark place, and can repeatedly store and emit light.

[0002]

2. Description of the Related Art Conventional phosphorescent phosphor powders are almost sulfur compounds and are formed of, for example, ZnS: Cu, Co or CaS: Ce. These phosphorescent fluorescent powders can absorb energy from the outside and emit light in a dark place, but the emission time is only about 1 to 2 hours, the chemical stability is low, and the water resistance is poor. However, since it is liable to be deteriorated, the light emitting ability is rapidly lowered in several tens of hours, and there are drawbacks such as a short service life. The addition of radioactive substances to phosphorescent phosphor powders of sulfur compounds, can emit light for a long time,
Radioactive material is considered a dangerous source of pollution. Therefore, in order to suppress the possibility of causing human body pollution and environmental pollution due to the use of such radioactive materials, the use is prohibited internationally.

In view of the above-mentioned drawbacks of the prior art, many years of research led to the development of phosphorescent phosphor powders based on alkaline earth metal aluminates in the early 1990s. This phosphorescent phosphor powder is an aluminate activated by Eu, has a high luminous intensity, a long luminous time of 24 hours or more, is chemically stable, resistant to moisture, and resistant to light. It is widely used in various fields due to its excellent properties and long service life. For example, it is used for fluorescent ink, fluorescent paint, fluorescent glass printing, various signs, decorations, low intensity light source, etc. I have.

However, this kind of phosphorescent phosphorescent aluminate is industrially produced by mixing α-Al ₂ O ₃ and several kinds of necessary compounds and reacting them in a solid phase at a high temperature of 1300 ° C. or higher. As a result, the product becomes a ceramic-like hard solid. This high temperature treatment at 1300 ° C. or higher causes a ceramic-like hard solid because α-Al ₂ O ₃ has low chemical activity and reacts with components such as alkaline earth metals unless the temperature is high enough. The reaction at high temperatures produces monoclinic aluminates, and lanthanoid metal activators such as Eu ₂ O ₃ are introduced into the crystals to form luminescent centers and lattice defects. This ceramic-like hard product can be applied to practically 10 μm or less, especially 5 μm unless it is subjected to strong pulverizing treatment.
Powders of the following particle size cannot be obtained. However, when the luminescent crystal is damaged during the pulverization, it absorbs the activation energy, so that the luminescent ability is reduced. Further, when the particle diameter is 10 μm or more, the luminance sharply drops, and the particle diameter becomes 2 μm.
m or less, light emission is too weak, it is difficult to put to practical use, therefore, in intaglio printing, offset printing fluorescent ink, copier fluorescent toner, fiber dye,
The application of the finely powdered phosphorescent powder is limited. Further, conventionally, many studies have been made to improve disadvantages such as an excessively large particle size or a wide particle size distribution, but they have not been very successful.

On the other hand, the phosphorescent phosphor powder composed of aluminate is a low-valent Eu ion. As is well known, as an activator, the Eu ion is a variable ion, and has +2 and +3 valences.
When Eu ions act as activators of the fluorescent material, they emit a completely different optical spectrum. In alkaline earth metal aluminates, only divalent Eu ions can form lattice defects, and therefore, when producing phosphorescent phosphor powder, usually +3 valent
Eu ₂ O ₃ is added to the mixture as a source of Eu ions before heating at high temperature. In order to reduce Eu ³⁺ to Eu ²⁺ , the solid-state reaction must be performed in a reducing atmosphere. All Eu ³⁺
It is an important issue to determine whether the phosphorescent phosphor can be reduced to Eu ²⁺ , which affects the luminance and phosphorescent performance of the phosphorescent phosphor. Since the conventional method uses a flow of N ₂ gas containing 5% of H ₂ to reduce Eu ³⁺ to Eu ²⁺ , the reduction reaction must be performed in a closed tubular container. In addition, the operation is complicated, and the cost of equipment such as facilities is high, and large-scale production is difficult.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to overcome the above-mentioned drawbacks, to provide a high luminous intensity, a long luminous time, excellent water resistance, and to control the particle size distribution in a narrow range. It is an object of the present invention to provide a method for producing a particulate phosphorescent phosphor powder having characteristics and a particulate phosphorescent phosphor powder.

[0007]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of intensive studies to solve the above problems, Al,
In the production of the phosphorescent phosphor powder containing Sr, Eu and Dy as constituents, each raw material of these constituents has a specific blending ratio, and by dropping a particle thinning agent to a mixed solution of the raw materials. The precursor of the phosphorescent phosphor powder is manufactured, and further, by irradiating the precursor with microwaves, it is found that a fine particulate phosphorescent phosphor powder having a narrow particle size distribution with an average particle size of 2 μm to 5 μm can be obtained, Based on these findings, the present invention has been completed.

Namely, first the of the present invention, Al, Sr, and constituents Eu and Dy, and a raw material of _{Al (NO 3) 3 · 9H} 2 O constituents Al, constituting the Sr (NO _{3) 2} Eu ₂ O ₃ as a raw material for component Sr
A raw material of the constituent Eu, a method for producing a fine phosphorescent powder in the form of Dy ₂ O ₃ as a raw material of the constituent Dy,
Method for producing a particulate phosphorescent powder blending ratio of each raw material, characterized in that it is adjusted to a range of below expressed in terms of mole _{ratios: Sr (NO 3) 2:} Al (NO 3) 3 · 9H 2 O = 1: 1.5 to 4 Eu ₂ O ₃ : Dy ₂ O ₃ = 1: 1.5 to ₃ Sr (NO ₃ ) ₂ : Eu ₂ O ₃ = 1: 0.001 to 0.02

According to the present invention, the above-mentioned constituent Eu and
And Dy raw material Eu_TwoO_ThreeAnd Dy_TwoO_ThreeAnd nitrate solution obtained by mixing
Liquid [Eu (NO_Three)_Three, Dy (NO_Three)_Three] And the components Sr and Al
Sr (NO_Three)_TwoAnd Al (NO_Three) _Three・ 9H_TwoObtained by mixing with O
Ammonium is added to the mixed solution obtained by mixing with the second solution.
To obtain a saturated ammonium solution,
1% to 10% of a particle thinning agent is dropped into a saturated solution of monium.
After stirring to form a precipitate, and then aging,
The precipitate formed is filtered, washed and dried by heating to luminesce
A step of obtaining a precursor of the fluorescent powder.
A method for producing a particulate phosphorescent powder is provided.

Further, according to the present invention, after the addition of the particle thinning agent, the precursor of the luminous fluorescent powder produced by the coprecipitation method is irradiated with microwaves, so that the precursor of the luminous fluorescent powder is Wherein the method further comprises a step of causing a solid-phase reaction to directly synthesize and obtain fine-grain phosphorescent powder.

A second aspect of the present invention is a luminous phosphor powder obtained by the method for producing a luminous phosphor powder according to the first aspect of the present invention, which has an average particle size of 2 μm to 5 μm. The present invention relates to a particulate phosphorescent phosphor powder characterized by having.

The present invention relates to a method for producing a particulate phosphorescent phosphor powder and a particulate phosphorescent phosphor powder obtained by the method as described above. As a more preferred embodiment, at least the following steps are carried out. Include. (1) A method for producing a particulate luminous phosphor powder containing Al, Sr, Eu and Dy as constituent components, wherein a nitrate solution obtained by dissolving Eu ₂ O ₃ and Dy ₂ O ₃ in HNO ₃ I (Eu (NO ₃ ) ₃ and Dy (N
O _{3) 3} mixed solution of) the Sr (NO _{3) 2} and Al (solution of NO _{3) 3} · 9H ₂ O
2. A phosphorescent fluorescence comprising a step of adding an ammonium compound to a mixed solution obtained by mixing II and an ammonium saturated solution to prepare an ammonium saturated solution, and agitating while dropping a particle thinning agent to the saturated solution to ripen a generated precipitate. Powder manufacturing method. (2) A step of adding a particle thinning agent to a mixed solution of the raw materials of the constituent components and irradiating the precursor obtained by co-precipitation of the components with microwaves to prepare an aggregate of luminescent phosphor fine particles.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for producing a phosphorescent phosphor powder according to the present invention is characterized by providing a phosphorescent phosphor particle aggregate having a novel composition and characteristics having the above-mentioned constitution. In a preferred embodiment, the production method employs a step of preparing a phosphorescent phosphor powder precursor by adding a particle thinner before precipitating the constituent components by a coprecipitation method. As the particle thinning agent, at least one selected from the group consisting of sucrose, glucose, starch, and cellulose ether is selected. 0.5% of the weight of the precursor was added
Preferably, it accounts for 〜10%, especially 1% 、 １9%.

As a preferred embodiment, a step of irradiating the precursor with microwaves and subjecting the precursor to a solid phase reaction is employed. Fine particles (with a particle size of 2 μm to
5 μm) can be obtained. The microwave is a very high frequency wave, and has a frequency of 1000 MHz or more and a range in contact with far infrared rays.

[0015] Preparation material of the _{precursor, Al (NO 3) 3 ·} 9H
_{By using 2} O as a raw material of the constituent Al, Sr (NO ₃ ) ₂ as a raw material of the constituent Sr, Eu ₂ O ₃ as a raw material of the constituent Eu, and Dy ₂ O ₃ as a raw material of the constituent Dy. The mixing ratio of each raw material is represented by a molar ratio as follows. _{Sr (NO 3) 2: Al} (NO 3) 3 · 9H 2 O = 1: 1.5~4 ( Molecular _{proportional) Eu 2 O 3: Dy 2} O 3 = 1: 1.5~3 ( Molecular proportional) Sr (NO ₃ ) ₂ : Eu ₂ O ₃ = 1: 0.001 to 0.02 (molecular proportion)

[0016]

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the examples and the like.

In the embodiment of the present invention, Al (NO_Three)_Three・ 9H_TwoO
Is the raw material of the component Al, and Sr (NO_Three) _TwoThe component Sr
Material and Eu_TwoO_ThreeIs the raw material of the constituent Eu, and Dy_TwoO_ThreeIs composed
A product was manufactured as a raw material of the component Dy.

The following raw materials were accurately measured and prepared. 1. _{Al (NO 3) 3 · 9H} 2 O 375.13g 2. Sr (NO ₃ ) ₂ 105.8 g 3. Eu ₂ O ₃ 1.76 g 4. Dy ₂ O ₃ 3.73 g 5. Glucose 9.7g 6. (NH ₄ ) ₂ CO ₃ 96 g 7. 7. NH ₄ HCO ₃ 79.06 g HNO ₃ (65%) 10ml

First, Eu ³⁺ by Eu ₂ O ₃ , Dy ₂ O ₃ and HNO ₃
And a solution I in which Dy ³⁺ is mixed. Then, Sr (NO ₃ ) ₂ and A
l (NO ₃ ) ₃・ 9H ₂ O and pure water at the same time
I got Dextrose was added to the mixed solution obtained by mixing the solution I and the solution II to prepare a glucose solution of the mixed solution (I + II). Finally, (NH ₄ ) ₂ CO ₃ and NH ₄ HCO ₃ are dissolved in pure water until they are saturated, and a mixed ammonium salt saturated solution III
I got The glucose solution of the mixed solution (I + II) is slowly dropped into the mixed ammonium salt saturated solution III, and the mixture is vigorously stirred. After the reaction is completed, the mixture is kept and matured for 24 hours, filtered, washed, heated and dried, and then luminous. A precursor of the fluorescent powder was obtained. Further, the precursor of the phosphorescent phosphor powder was placed in a microwave oven in a slightly oxidizing atmosphere and heated for 30 minutes. In this case, the efficiency of microwave oven is 800w and the frequency is 2450M
Hz. Next, the precursor was placed in a microwave oven in a reducing atmosphere, heated and cooled for 30 minutes, and then the production of the aluminate phosphorescent powder activated by Eu and Dy was completed.

The main chemical reactions involved in the above manufacturing process are as follows. _{Dy 2 O 3 + 6HNO 3 =} 2Dy (NO 2) 3 + 3H 2 O Eu 2 O 3 + 6HNO 3 = 2Eu (NO 3) 3 + 3H 2 O 4NH 4 HCO 3 + Al (NO 3) 3 · 9H 2 O = NH ₄ AlO (OH) HCO ₃ + 3CO ₂ ↑ + 3NH ₄
NO ₃ + 10H ₂ O Sr (NO ₃ ) ₂ + (NH ₄ ) ₂ CO ₃ = SrCO ₃ + 2NH ₄ NO ₃ 2Dy ³⁺ + 3CO ₃ ^2- = Dy ₂ (CO ₃ ) ₃ 2Eu ³⁺ + 3CO ₃ ^2- = Eu ₂ (CO ₃ ) ₃ 2NH ₄ AlO (OH) HCO ₃ = Al ₂ O ₃ + 2NH ₃ + 2CO ₂ ↑ + 3H ₂ O (oxidation stage in microwave oven) Dy ₂ (CO ₃ ) ₃ + 3Al ₂ O ₃ = Dy ₂ (Al ₂ O ₄ ) ₃ 3CO ₂ ↑ (reduction step in microwave oven) Eu ₂ (CO ₃ ) ₃ + 2Al ₂ O ₃ + C = 2EuAl ₂ O ₄ + 3CO ₂ ↑ + CO (Reduction stage in microwave oven)

Through the above-described production process, a fine-grain phosphorescent powder having a high luminous intensity, a long luminous time, excellent water resistance, and a narrow particle size distribution was obtained. The performance of the phosphorescent powder of the present invention is as disclosed in FIGS. 1, 2, and 3. The performance of the phosphorescent phosphor powder was evaluated by the following test method.

Surface Luminance Measurement As shown in FIG. 5, irradiation is performed for 10 minutes or more using a fluorescent lamp (FL30SEX-N) from a position about 20 cm above the sample, and then the irradiation is stopped. One minute after the irradiation was stopped, the change in luminance was measured and recorded using a color luminance meter (photoelectric colorimeter). The sample was prepared by pressing the powder with a press molding machine (about 40
Using t), a plate formed about 4 cm in diameter and about 3 mm in thickness was used. Measuring instrument / test conditions: color luminance meter BM-7, viewing angle: 2
°, measuring distance: 40 cm. Light source, irradiation illuminance: FL30SEX-N.

Particle size distribution measurement LA-920 manufactured by Horiba Seisakusho Co., Ltd. was used, and water was used as a dispersion medium and sodium hexametaphosphate was used as a dispersant by a wet flow cell measurement method.

[0024]

The present invention has the following effects because it has the above-described structure, and has extremely high industrial utility value. 1. Since the precursor of the phosphorescent phosphor powder is irradiated with microwaves to cause a solid-phase reaction, the reaction time is shortened, and energy is saved and the environment is not polluted. 2. Since the solid-phase reaction is performed by heating with microwaves using a particle thinner, the produced phosphorescent fluorescent powder can reach the particle diameter of the particles in the range of 2 μm to 5 μm without pulverization, and As shown in FIG. 2, the distribution range of the particle size is narrow, and pulverization is not required, so that a product having a particle shape with few protrusions can be manufactured, and the product yield is high. 3. Comparing FIG. 3 with FIG. 4, the relative luminous intensity of the fluorescent phosphorescent powder according to the present invention (FIG. 3) is 130% higher than that of the phosphorescent fluorescent powder synthesized by a high-temperature solid-state reaction (FIG. 4), which is high. It can be seen that it has brightness. In addition, since the phosphorescent phosphor powder according to the present invention is in the form of fine particles and does not need to be pulverized, the pulverization does not damage the luminescent crystal and does not reduce the luminous ability by absorbing activation energy. 4. The afterglow time reaches 10 mcd / m ² 600 minutes.

[Brief description of the drawings]

FIG. 1 is a luminescence spectrum diagram of a phosphorescent phosphorescent aluminate activated by Eu and Dy prepared in an example of the present invention.

FIG. 2 is a particle size distribution diagram of a phosphorescent phosphorescent aluminate activated by Eu and Dy prepared in an example of the present invention.

FIG. 3 shows that the aluminate phosphorescent powder activated by Eu and Dy prepared in the example of the present invention has a D ₅₀ = 3 μm.
FIG. 14 is a graph showing the afterglow characteristic at the time of m.

FIG. 4 is a comparative example having the same component configuration,
Obtained by thermal solid-state reaction under conditions of 1300 ° C or higher, Eu, Dy
= ₅₀ of the aluminate phosphorescent fluorescent powder activated by
FIG. 10 is a graph showing the afterglow characteristics at 10 μm.

FIG. 5 is a diagram showing an outline of surface luminance measurement.

Continued on the front page (72) Inventor Chen Ping, No. 50, Ashizhuang District, Wuxi City, Jiangsu People's Republic of China Room 302 Room (72) Inventor Satoshi Sakae 60-1 Yusang, Wuxi City, Jiangsu Province, People's Republic of China F-term (Reference) 4H001 CA02 CF01 XA13 XA38 YA63 YA66

Claims (6)

[Claims] 1. An Al (N) comprising Al, Sr, Eu and Dy as constituents.
O _{3) 3} · 9H ₂ and O constituents Al raw material, the raw material of Sr (NO _{3) 2} the component Sr, and a raw material component Eu a Eu ₂ O _3, Dy ₂ O ₃ constituent components Dy A method for producing a particulate phosphorescent fluorescent powder as a raw material of the particulate phosphorescent phosphor powder, characterized in that the blending ratio of each raw material is adjusted to the following range expressed by a molar ratio. Production method: Sr (NO ₃ ) ₂ : Al (NO ₃ ) ₃ .9H ₂ O = 1: 1.5 to 4 Eu ₂ O ₃ : Dy ₂ O ₃ = 1: 1.5 to ₃ Sr (NO ₃ ) ₂ : Eu ₂ O ₃ = 1: 0.001 to 0.02 2. Eu ₂ O _{3 as} a raw material of the constituent components Eu and Dy
And Dy ₂ O ₃ and mixed nitrate solution [Eu (NO ₃ ) ₃ , Dy (NO
₃ ) ₃ ] and Sr (N
O _{3) 2} and _{Al (NO 3) 3 · 9H} 2 O-and by mixing a second solution obtained by mixing the resulting saturated ammonium solution was added dropwise a particulate fine agent to said ammonium saturated solution The method according to claim 1, further comprising a step of forming a precipitate by stirring while stirring, and then aging, and then filtering, washing and heating and drying the precipitate to obtain a precursor of the phosphorescent fluorescent powder. A method for producing a particulate phosphorescent phosphor powder. 3. The fine phosphorescent powder according to claim 2, wherein the particle thinning agent is at least one selected from the group consisting of sucrose, glucose, starch and cellulose ether. Production method. 4. The particulate phosphorescent fluorescence according to claim 2, wherein the amount of the particle thinner added is 0.5% by weight to 10% by weight based on the total weight of the precursor. Powder manufacturing method. 5. After the addition of the particle thinning agent, the precursor of the phosphorescent phosphor powder produced by the coprecipitation method is irradiated with microwaves to cause a solid phase reaction on the precursor of the phosphorescent phosphor powder. The method according to claim 2, further comprising a step of directly synthesizing and obtaining a finely particulate luminous phosphor powder. 6. A luminescent phosphor powder obtained by the production method according to claim 5, wherein the luminescent phosphor powder has an average particle diameter in a range of 2 μm to 5 μm.