JP2004075890A - Process for preparing solid fine particle dispersion of inorganic phosphor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a fine phosphor for practical use by inhibiting damages caused by dispersing this. <P>SOLUTION: In a process for preparing a solid fine particle dispersion of the inorganic phosphor, a step for dispersing the inorganic phosphor synthesized through a liquid-phase method, etc. is performed by applying a mechanical energy E, defined by the equation: E=tV<SP>2</SP>[wherein V is peripheral speed (m/s); and t is dispersing time (s)], of ≤2.5×10<SP>5</SP>m<SP>2</SP>/s, preferably ≤9.0×10<SP>4</SP>m<SP>2</SP>/s, more preferably ≤4.1×10<SP>4</SP>m<SP>2</SP>/s, using e.g. a bead mill. <P>COPYRIGHT: (C)2004,JPO

Description

【００２５】
表１より、固相法による前駆体合成、液相法による前駆体合成それぞれの場合において、機械的エネルギーＥが大きくなるような微粒子分散条件でビーズミル分散を行った場合、粗分散物に対して発光強度の低下が著しく、すなわち発光効率が低下することを示している。これに対して分散条件を変更して機械的エネルギーＥを２．５×１０^５［ｍ^２／ｓ］以下に下げた場合、発光強度の低下は減少し、発光効率の低下を抑制でき、更に機械的エネルギーＥを４．１×１０^４［ｍ^２／ｓ］以下に下げた場合はその傾向が顕著に現れた。また、その中でも前駆体を液相法で合成した無機蛍光体を含有する試料Ｇ−２２、Ｇ−２３は、機械的エネルギーＥが小さいにも関わらず微粒子分散物の平均粒径も小さく、更に発光強度の低下が減少する効果がより顕著である。これは、液相法で前駆体を合成した場合は１次粒径が元々小さいために比較的低い焼成温度で無機蛍光体を作製することが可能で、それによって焼成時の凝集を抑制でき、結果的に小さい機械的エネルギーで発光強度の低下を起こすことなく平均粒径の小さい固体微粒子分散物を得られることを示している。
【００２６】
実施例２
実施例１の無機蛍光体固体微粒子分散物試料Ｇ−２３の製造方法において、蛍光体含有スラリーを下記の処方に代えた以外はＧ−２３と同様にして固体微粒子分散物試料Ｇ−２４を製造した。
―蛍光体含有スラリー処方―
無機蛍光体　　　　　　　１０重量部
エマルゲン４２０　　　　　２重量部
Ｊｏｎｃｒｙｌ１７０　　　２重量部
水　　　　　　　　　　　８６重量部
《固体微粒子分散物試料の評価》
得られたＧ−２４を実施例１と同様に平均粒径及び発光強度を測定した結果、平均粒径は０．１６μｍ、Ｇ−１０の発光強度を１００％とした時の相対発光強度は６６０％であった。
この結果より、界面活性剤存在下で分散処理を行うと、固体分散物の微粒化画図られ、かつ、分散物の発光強度低下の抑制効果が顕著であることがわかる。
【００２７】
【発明の効果】
本発明によれば、分散によるダメージを制限し、実用に耐えうる微小蛍光体を得ることができる。[0001]
[Industrial applications]
The present invention relates to a method for producing a micro phosphor.
[0002]
[Prior art]
Inorganic phosphors have excellent luminous efficiency and durability, and many of them do not have a body color, and are suitable for full-color reproduction and the like. Therefore, it has been used for applications such as fluorescent lamps and cathode ray tubes.
Organic phosphors, on the other hand, have the advantage of being excellent in solubility, storage stability after dispersion, and easy to handle. However, since it has a body color, it is not suitable for full-color reproduction. Therefore, if there is a fine and easy-to-handle inorganic phosphor, it is considered that its use will be expanded and the expression of hard copy will also be expanded. However, it is difficult to produce a fine phosphor and it has not been put to practical use so far.
Japanese Patent Application Laid-Open No. 2000-256591 discloses a method of dispersing a phosphor, but the dispersion is performed for 4 hours using small-diameter beads, and the crushing energy is too large, and the luminous intensity of the phosphor in the first place is reduced. Lost, not practical.
Also, Japanese Patent Application Laid-Open No. 2001-172620 describes a method for manufacturing a microphosphor, but has low luminance and is not practical.
[0003]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to limit the damage caused by dispersion and to obtain a fine phosphor that can be used practically.
[0004]
[Means for Solving the Problems]
The above object of the present invention is
(1) An inorganic fluorescent material, wherein the step of dispersing an inorganic phosphor is performed by applying a mechanical energy E having a mechanical energy E represented by the following formula of 2.5 × 10 ⁵ m ² / s or less. Method for producing solid body fine particle dispersion.
E = tV ²
(Where V represents the peripheral speed (m / s) and t represents the dispersion time (s))
(2) The inorganic material according to the above (1), wherein at least a part of the step of producing the solid fine particle dispersion is performed in the presence of one kind selected from a surfactant and a polymer dispersant. Method for producing phosphor solid fine particle dispersion.
(3) The method for producing an inorganic phosphor solid fine particle dispersion according to the above (1) or (2), wherein the dispersion step is performed using a bead mill.
(4) The method according to any one of the above (1) to (3), wherein the inorganic phosphor is synthesized by a liquid phase method.
Achieved by
[0005]
Hereinafter, the present invention will be described in detail.
The solid fine particle dispersion of the inorganic phosphor of the present invention is produced by applying a specific mechanical energy. The mechanical energy E added by the following formula at that time is 2.5 × 10 ⁵ m ² / s or less, preferably 9.0 × 10 ⁴ m ² / s or less, more preferably 4.1 × 10 ⁵ m ² / s. ⁴ m ² / s or less.
E = tV ² (V represents peripheral speed (m / s), and t represents dispersion time (s).)
Here, the value of mechanical energy refers to the total energy applied to the phosphor. When an energy exceeding 2.5 × 10 ⁵ m ² / s is applied, the emission intensity sharply decreases. Further, when the deterioration is severe, the phenomenon that the band gap changes and the emission color changes is observed. On the other hand, if it is less than 6000 m ² / s, it becomes impossible to obtain a fine phosphor, which is not preferable.
In the method for producing a dispersion of solid fine inorganic phosphor particles of the present invention, as a disperser used in the dispersing step, various conventionally known dispersers can be used. More specifically, a medium medium such as a high-speed stirring type inverer type disperser, a bead mill, a colloid mill, a roller mill, a ball mill, a vibrating ball mill, an attritor mill, a planetary ball mill, and a sand mill is moved in the apparatus, and the collision (crush) and Examples include those that are atomized by both shearing forces, and dry dispersers such as a cutter mill and a hammer mill.
[0006]
Specific examples of these dispersing machines include a pearl mill, an agitator mill (Ashizawa), a Glen mill, a tornado (Asada Steel), a visco mill (IMEX), a mighty mill, an RS mill, an SG mill (Inoue), an Ebara milder (EBARA) ), A fine flow mill (Taipei Yoki Kiko), a bead mill manufactured by Getzman Co., Ltd., and the like. Among the above dispersing means, it is preferable to use a wet media type disperser using a medium medium, and it is more preferable to use a wet media type disperser capable of continuous dispersion processing.
The term "continuously dispersible" as used herein means that at least the inorganic phosphor and the dispersing medium are dispersed in the disperser while being supplied to the disperser without interruption at a constant volume ratio per time, and at the same time, are produced in the disperser. Refers to a form in which the dispersed material is discharged from the disperser without being interrupted while being extruded into the supplied material.
[0007]
In the method for producing an inorganic phosphor of the present invention, when a wet-type media type disperser using a medium is used as a dispersion treatment step, the dispersion chamber container (vessel) can be appropriately selected from a vertical type and a horizontal type. It is. Furthermore, a mode in which a plurality of continuous wet-type media dispersers are connected in series can be applied.
When using a wet media type disperser, the peripheral speed is preferably 3 to 20 m / s, and more preferably 8 to 18 m / s. The temperature of the dispersion at this time is not particularly limited, but is preferably in the range of 20 to 50 ° C.
The particle size of the media used is preferably 0.2 mm or more and 2 mm or less, more preferably 0.3 mm or more and 1 mm or less. If it is less than 0.2 mm, it is difficult to handle and it is difficult to collect the media when inspecting the dispersing machine. There is a danger of breaking if the screw is tightened. If it exceeds 2 mm, the handling becomes easy, but the dispersing time is greatly increased and the productivity is lowered.
[0008]
The larger the specific gravity and hardness of the media used, the larger the impact force and the greater the shearing force, and it is expected that the dispersion efficiency and the dispersion speed are improved. Is preferred. Specifically, the specific gravity is preferably from 2.5 to 10, and more preferably from 3.5 to 6. As the material of the medium to be used, various kinds of media such as glass, zirconia, alumina, silica, titania and the like can be used, and zirconia beads are particularly preferable from the viewpoint of specific gravity and hardness. Further, at this time, it is preferable that the material of the inner wall of the media type disperser vessel is also zirconia. When a phosphor is harder than a metal and a metallic one is used, the dispersion progress is poor, and the container and the beads are shaved, resulting in severe mixing of impurities and severe liquid contamination.
The filling amount of the media in the vessel of the wet media type disperser is preferably in the range of 50 to 90% by volume, and more preferably in the range of 60 to 80% by volume. When the filling amount of the medium is less than 50% by volume, the dispersion of the inorganic phosphor becomes insufficient, and when the filling amount exceeds 90% by volume, the distribution of the medium in the vessel becomes uneven, and the dispersion progresses locally. Not preferred.
[0009]
In the present invention, when the dispersion treatment is performed by a wet method, water, various organic solvents, or a mixture thereof can be used as a dispersion medium. A slurry is prepared by suspending the inorganic phosphor in these dispersion media and subjected to a wet dispersion treatment. At this time, the concentration of the inorganic phosphor can be arbitrarily adjusted depending on the subsequent use of the inorganic phosphor solid dispersion, but is preferably in the range of 5 to 30% by weight, and more preferably in the range of 10 to 25% by weight. More preferably, it is.
In the method for producing an inorganic phosphor of the present invention, it is preferable to use a surfactant or a polymer dispersant as necessary in the dispersion treatment.
Examples of the surfactant include anionic surfactants such as alkyl sulfates, alkyl ester sulfates, dialkyl sulfosuccinates, alkyl naphthalene sulfonates, alkyl phosphates, polyoxyalkylene alkyl ether phosphates, and fatty acid salts. Agents, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyalkylene alkyl phenyl ethers, acetylene glycols, nonionic surfactants such as polyoxyethylene / polyoxypropylene block copolymers, glycerin esters, Activators such as sorbitan esters, polyoxyethylene fatty acid amides and amine oxides, and cationic surfactants such as alkylamine salts and quaternary ammonium salts can be used.
[0010]
As the polymer dispersant, a water-soluble resin is used. As the water-soluble resin preferably used, for example, styrene-acrylic acid-alkyl acrylate copolymer, styrene-acrylic acid copolymer, styrene-maleic acid Copolymer, styrene-maleic acid-alkyl acrylate copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-alkyl acrylate copolymer, styrene-maleic acid half-ester copolymer, vinyl naphthalene -Acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer and the like.
[0011]
Next, the inorganic phosphor used in the present invention will be described.
As the inorganic phosphor of the present invention, inorganic phosphors manufactured by various methods such as a conventionally known solid phase method and liquid phase method can be used. It is advantageous to use inorganic phosphor particles having a narrow particle diameter, and it is preferable to use an inorganic phosphor produced by a liquid phase method such as a sol-gel method, a coprecipitation method, or a reaction crystallization method.
The sol-gel method refers to, for example, a metal alkoxide (for example, Si (OCH ₃ ) ₄ or the like) or a metal complex (for example, Eu ³⁺ (CH ₃ ) including an element (metal) used for a mother nucleus or an activator or a co-activator. ₃ COCH ＝ C (O—) CH ₃ ) ₃ ) or a double alkoxide made by adding a simple metal to an organic solvent solution thereof (for example, Mg made by adding metal magnesium to a 2-butanol solution of Al (OBu) ₃ ) [Al (OBu) ₃ ] ₂ ), a metal halide, and a metal salt of an organic acid are mixed in a reaction vessel in a required amount, and the mixture is thermally or chemically hydrolyzed or polycondensed to synthesize.
The average particle size and the variation coefficient of the particle size distribution of the obtained inorganic phosphor are determined by various conditions such as raw materials, mixing conditions, and reaction temperature.
As the element (metal) used for the mother nucleus, the activator or the co-activator, various elements (metals) can be appropriately used. For example, when the element (metal) used for the activator or the co-activator is activated, Can be used as a raw material.
[0012]
As the organic solvent for dissolving the reaction raw materials, it is possible to use a mixed solvent containing alcohols such as ethanol and propanol, and if necessary, other polar solvents, but use ethanol from the viewpoint of the environment. Is preferred.
When a plurality of reaction raw materials are used, the order of adding the raw materials may be simultaneous or different, and an appropriate sequence can be assembled depending on the activity. In some cases, a double alkoxide may be formed.
The reaction temperature, pH, addition speed, stirring speed, and the like can be appropriately controlled as needed. In addition, even if ultrasonic waves are applied during or after the reaction, mechanical energy is applied, or a surfactant, a polymer, or the like is added for controlling the particle size, no groove is formed.
At the time of hydrolysis, it is preferable to use a base or an acid as a catalyst (reaction initiator), and it is more preferable to use a base from the viewpoint of hydrolysis rate. As the type of the base, a common base such as NaOH and ammonia can be used as long as the reaction can be started, but ammonia is preferably used from the viewpoint of easy removal. The method of mixing the reaction initiator may be previously added to the mother liquor, may be added at the same time as the raw material, or may be added to the raw material, but is added to the mother liquor first to enhance uniformity. Is preferred.
After the hydrolysis and the polycondensation reaction are completed and a sol is generated, aging or concentration may be performed as necessary. Further, it is preferable to wash the sol after collecting it by a method such as filtration, evaporation to dryness, or centrifugation. Further, after that, drying and baking are not necessarily performed. The drying temperature is not particularly limited, but is preferably a temperature around the temperature at which the solvent used evaporates or more, and specifically, preferably in the range of 50 to 300 ° C. The firing temperature is not particularly limited, but generally, a range of 600 to 1500 ° C. can be preferably used. When the drying temperature is high, firing may be performed simultaneously with drying. The firing may be performed under any conditions such as a reducing atmosphere, an oxidizing atmosphere, and the presence of a sulfide, and may be appropriately selected. Further, if necessary, a reduction treatment or an oxidation treatment may be performed after the firing. Further, depending on the composition of the inorganic phosphor, the reaction conditions, and the like, it may not be necessary to perform firing, and in such a case, the firing step may be omitted.
[0013]
The coprecipitation method is a method in which one or more kinds of reaction raw materials containing a mother nucleus or an activator or an element (metal) used for a coactivator are dissolved in a solvent mainly composed of water, and one kind or a plurality of kinds are optionally used. Prepare various types of raw material solutions, add an organic compound that dissolves itself in the solvent and reacts with the raw materials to form and precipitate a hardly soluble or insoluble substance, such as oxalic acid or tartaric acid, as a precipitant, and if necessary, an alkali. This is a method of using a flux such as a metal borate to generate a precipitate in which the raw material is coprecipitated. After the precipitate is formed, the desired phosphor particles can be obtained through steps such as filtration, drying and baking.
The reaction crystallization method is a method of dissolving various metal salts such as metal nitrates, metal halides, etc. containing elements (metals) used as a mother nucleus or an activator or a co-activator in a solvent mainly composed of water. And then depositing a hardly soluble salt chemically.
The average particle size and the variation coefficient of the particle size distribution of the obtained inorganic phosphor are determined by various conditions such as raw materials, mixing conditions, pH, and reaction temperature.
As the element (metal) used for the mother nucleus, the activator or the co-activator, various elements (metals) can be appropriately used. For example, when the element (metal) used for the activator or the co-activator is activated, Can be used as a raw material.
When using a plurality of reaction raw materials, the order of adding the raw materials may be simultaneous or different, and an appropriate sequence can be assembled depending on the activity.
[0014]
The reaction temperature, pH, addition speed, stirring speed, and the like can be appropriately controlled as needed. Further, ultrasonic waves may be applied during or after the reaction, mechanical energy may be applied, or a surfactant, a polymer, or the like may be added for controlling the particle size.
It is preferable to use a base or an acid as a reaction initiator when depositing a hardly soluble salt, and it is more preferable to use an acid from the viewpoint of uniformly depositing each ion. Any acid can be used as long as it can initiate the reaction, and common acids such as nitric acid and hydrochloric acid can be used. However, from the viewpoint of easy removal, nitric acid is preferably used. The method of mixing the reaction initiator may be added to the mother liquor first, may be added at the same time as the raw material, or may be added to the raw material, but at least a small amount is added to the mother liquor first to enhance uniformity. The preferred method is preferred.
After the reaction is completed to form a hardly soluble salt, aging or concentration may be performed as necessary. Further, after collecting by filtration, evaporation to dryness, centrifugation or the like, washing is preferably performed. After that, drying and baking are carried out, although not necessarily required. The drying temperature is not particularly limited, but is preferably a temperature around the temperature at which the solvent used evaporates or more, and specifically, preferably in the range of 50 to 300 ° C. The firing temperature is not particularly limited, but generally, a range of 600 to 1600 ° C. can be preferably used. When the drying temperature is high, firing may be performed simultaneously with drying. The calcination may be performed under any conditions such as a reducing atmosphere, an oxidizing atmosphere, or in the presence of a sulfide, and may be appropriately selected. Furthermore, if necessary, a reduction treatment or an oxidation treatment may be performed after the firing. Further, depending on the composition of the inorganic phosphor, the reaction conditions, and the like, it may not be necessary to perform firing, and in such a case, the firing step may be omitted.
[0015]
The sol-gel method, the coprecipitation method, and the reaction crystallization method may use a method suitable for each composition. In some cases, these methods may be used in combination for one composition.
The inorganic phosphor is preferably subjected to surface treatment by adsorption, coating, or the like for various purposes. The point at which the surface treatment is performed depends on the purpose, and the effect becomes more marked when properly selected. For example, if the surface of the phosphor is coated with an oxide containing at least one element selected from Si, Ti, Al, Zr, Zn, In, and Sn at any time before the dispersion process, A decrease in the crystallinity of the phosphor can be suppressed, and a decrease in emission luminance and emission intensity can be suppressed by preventing excitation energy from being captured by surface defects of the phosphor. Further, when the surface of the phosphor is coated with a metal oxide, an organic polymer compound, or the like at any time after the dispersion treatment step, characteristics such as weather resistance are improved, and an inorganic phosphor excellent in durability is obtained. Can be. Further, various pigments may be coated for the purpose of correcting the emission color. The thickness, coverage, and the like of the coating layer when performing these surface treatments can be appropriately controlled as appropriate.
The composition of the inorganic phosphor used in the present invention is not particularly limited, and phosphors having various known compositions can be used. However, metal oxides represented by Y ₂ O ₃ , Zn ₂ SiO _{4 and the} like can be used. , Sr ₅ (PO ₄ ) ₃ Cl, and other phosphates, and sulfides, such as ZnS, SrS, and CaS, as crystal nuclei, and these nuclei include Ce, Pr, Nd, Pm, and Sm. , Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb, and rare earth metal ions such as Ag, Al, Mn, and Sb are preferably combined as activators or coactivators.
[0016]
Preferred examples of the crystal base include, for example, YO ₃ , Y ₂ O ₃ , Y ₂ O ₂ S, Y ₂ SiO ₃ , YAlO ₃ , Y ₃ Al ₅ O ₁₂ , (Y, Gd) ₃ Al ₅ O ₁₂ , SnO ₂ , Zn ₂ SiO ₄ , Sr ₄ Al ₁₄ O ₂₅ , CeMgAl ₁₁ O ₁₉ , BaAl ₁₂ O ₁₉ , BaAl ₂ Si ₂ O ₈ , BaMgAl ₁₀ O ₁₇ , BaMgAl ₁₄ O ₂₃ , Ba ₂ Mg ₂ Al ₁₂ O _{22 , Ba 2 Mg 4 Al 8 O} 18, Ba 3 Mg 5 Al 18 O 35, (Ba, Sr, Mg) O · aAl 2 O 3, (Ba, Sr) (Mg, Mn) Al 10 O 17, (Ba _{, Sr, Ca) (Mg,} Zn, Mn) Al 10 O 17, (Y, Gd) BO 3, GdMgB 5 O 10, Sr 2 P 2 O 7, (La, Ce) _{O 4, Ca 5 (PO 4} ) 3 Cl, Ca 10 (PO 4) 6 (F, Cl) 2, (Sr, Ca, Ba, Mg) 10 (PO 4) 6 Cl 2, ZnS, (Zn, Cd ) S, CaS, SrS, SrGa ₂ S _{4 and the} like.
The crystal mother nucleus and the activator or co-activator are not limited in the composition of the elements, and can be partially replaced with elements of the same family. However, it is preferable to use an inorganic oxide phosphor, or an inorganic halide phosphor. .
Phosphors that emit visible light by absorbing ultraviolet to blue regions can be obtained by appropriately combining a crystal base and an activator or co-activator.
In the following, inorganic phosphors preferably used in the present invention are shown, but the phosphor used in the present invention is not limited to these compounds.
[0017]
[Blue-emitting inorganic fluorescent compound]
_{(BL-1) Sr 4 Al} 14 O 25: Eu 2+
(BL-2) BaAl ₂ Si ₂ O ₈ : Eu ²⁺
(BL-3) BaMgAl ₁₀ O ₁₇ : Eu ²⁺
(BL-4) BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Tb ³⁺ , Sm ²⁺
(BL-5) BaMgAl ₁₄ O ₂₃ : Eu ²⁺
_{(BL-6) Ba 2 Mg} 2 Al 12 O 22: Eu 2+
_{(BL-7) Ba 2 Mg} 4 Al 8 O 18: Eu 2+
_{(BL-8) Ba 3 Mg} 5 Al 18 O 35: Eu 2+
(BL-9) (Ba, Sr) (Mg, Mn) Al 10 O 17: Eu 2+
(BL-10) (Ba, Sr, Ca) (Mg, Zn, Mn) Al 10 O 17: Eu 2+
_{(BL-11) Sr 2 P} 2 O 7: Sn 4+
(BL-12) (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺
_{(BL-13) SrGa 2 S} 4: Ce 3+
_{(BL-14) CaGa 2 S} 4: Ce 3+
_{(BL-15) Sr 2 P} 2 O 7: Eu 2+
_{(BL-16) Sr 5 (} PO 4) 3 Cl: Eu 2+
[0018]
[Green-emitting inorganic fluorescent compound]
_{(GF-1) Y 3 Al} 5 O 12: Tb 3+
_{(GF-2) Sr 4 Al} 14 O 25: Eu 2+
(GF-3) (Ba, Mg) Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺
_{(GF-4) Ba 2 SiO} 4: Eu 2+
(GF-5) (Ba, Mg) ₂ SiO ₄ : Eu ²⁺
(GF-6) Ca ₂ Y ₈ (SiO ₄ ) ₆ O ₂ : Tb ³⁺
(GF-7) Y ₂ SiO ₅ : Ce ³⁺ , Tb ³⁺
_{(GF-8) La 3 Ga} 5 SiO 14: Tb 3+
(GF-9) (Sr, Ba) Al ₂ Si ₂ O ₈ : Eu ²⁺
_{(GF-10) (Ba,} Ca, Mg) 5 (PO 4) 3 Cl: Eu 2+
^{_{(GF-11) SrGa 2 S}} 4: Eu 2+, Tb 3+, Sm 2+
_{(GF-12) Sr 2 Si} 3 O 8 -2SrCl 2: Eu 2+
_{(GF-13) Zr 2 SiO} 4 -MgAl 11 O 19: Ce 3+, Tb 3+
_{(GF-14) Sr 2 P} 2 O 7 -Sr 2 B 2 O 5: Eu 2+
[0019]
[Red-emitting inorganic fluorescent compound]
_{(RL-1) Y 2 O} 2 S: Eu 3+
_{(RL-2) YAlO 3:} Eu 3+
_{(RL-3) YVO 4:} Eu 3+
(RL-4) (Y, Gd) ₃ Al ₅ O ₁₂ : Ce ³⁺
(RL-5) (Ba, Mg) Al ₁₆ O ₂₇ : Eu ³⁺
(RL-6) (Ba, Mg) ₂ SiO ₄ : Eu ³⁺
_{(RL-7) Ca 2 Y} 8 (SiO 4) 6 O 2: Eu 3+
(RL-8) LiY ₉ (SiO ₄ ) ₆ O ₂ : Eu ³⁺
_{(RL-9) (Ba,} Ca, Mg) 5 (PO 4) 3 Cl: Eu 3+
(RL-10) CaS: Eu ³⁺
_{(RL-11) (Sr,} Mg) 3 (PO 4) 2: Sn 2+
[0020]
The particle size of the inorganic phosphor dispersed in the present invention is not limited, but the smaller the average particle size, the more advantageous in performing the subsequent dispersion treatment. Specifically, the average particle size is preferably 2.0 μm or less, more preferably 1.0 μm or less, and even more preferably 0.8 μm or less. Here, the particle size of the inorganic phosphor means a sphere-converted particle size. The sphere-equivalent particle size is a particle size represented by the particle size of a sphere, assuming a sphere having the same volume as the particle volume.
Further, for the same reason as described above, it is advantageous that the particle size distribution is narrow. Specifically, the variation coefficient of the particle size distribution is preferably 100% or less, and more preferably 70% or less. Is more preferred. Here, the variation coefficient of the particle size distribution (the width of the particle distribution) is a value defined by the following equation.
Area of particle size distribution (coefficient of variation) [%]
= (Standard deviation of particle size distribution / average value of particle size) x 100
The dispersion medium of the inorganic phosphor solid fine particle dispersion of the present invention may be any of water, or various organic solvents, or a mixture thereof, depending on the subsequent use of the inorganic phosphor solid fine particle dispersion. It can be selected as appropriate. Various surfactants, a polymer dispersant for improving dispersion stability, a binder, and the like can be appropriately added to the inorganic phosphor solid fine particle dispersion of the present invention, if necessary.
The particle size and particle size distribution of the inorganic phosphor solid fine particle dispersion of the present invention are not particularly limited, and can be appropriately controlled according to the subsequent use, but the particle size is small in many applications. In many cases, a narrower particle size distribution is advantageous. Specifically, the average particle size is preferably 0.8 μm or less, and more preferably 0.5 μm or less. Further, the coefficient of variation of the particle size distribution is preferably 70% or less, more preferably 50% or less.
[0021]
The inorganic phosphor solid fine particle dispersion obtained by the present invention can be applied to various uses. For example, various methods such as mixing a liquid fluorescent material by mixing with a liquid material such as another solution or a solid dispersion, or applying an inorganic phosphor solid fine particle dispersion or a mixture containing the same to a substrate, and the like. Can be used.
The use of the inorganic phosphor solid fine particle dispersion obtained by the present invention is not particularly limited, and for example, various images such as a plasma display, a field emission display, an electroluminescence device, an active light emitting type liquid crystal device, and a cathode ray tube (CRT). Inorganic fluorescent layers of display devices, inks for inkjet printers, inks for laser printers, other inks suitable for printing styles such as offset printing and transfer ribbons, toners for electrophotography, coloring materials used for various paints and writing instruments, and more. Can be used in various places such as colorants for electronic recording media, silver halide photographic materials, intensifying screens and the like.
In particular, when used in the above various inks and various color materials, the inorganic phosphor solid fine particles obtained by the present invention in a solution or solid dispersion containing a colorant such as a dye or a pigment mainly for the purpose of color correction and the like. The dispersion can be mixed. Alternatively, a fluorescent material containing an inorganic phosphor as a main component without using a coloring agent can be used.
[0022]
【Example】
Example 1
<< Preparation of Green Phosphor Zn ₂ SiO ₄ : Mn (8 mol%) (Sample G-1) >>
In an aqueous medium, zinc oxide (ZnO), silica gel (SiO ₂ ) and manganese carbonate (MnCO ₃ ) are mixed and reacted at the following ratio.
156.2 g of ZnO
9.2 g of MnCO ₃
60.1 g of SiO ₂
The resulting reaction is shaken in acetone for about 4 hours. After the acetone is dried, it is sieved, put in a crucible made of alumina with a lid, and the crucible itself is placed in an oven, and calcined at 1300 ° C. for 4 hours in a neutral atmosphere under nitrogen reflux to obtain a G- 1 was obtained.
<< Preparation of Green Phosphor Zn ₂ SiO ₄ : Mn (8 mol%) (Sample G-2) >>
352.3 g of Zn (OCOCH ₃ ) ₂
Mn (OCOCH ₃ ) ₂ 1.042 g
Si (OCH ₂ CH ₃ ) ₄ 208.3 g
Tetraethoxysilane is dissolved in ethanol and added dropwise to a mixed solvent of water: ethanol = 1: 1 adjusted to pH 10 with ammonia. An aqueous solution of manganese acetate is also added dropwise at the same time. After the addition is completed, the solution is concentrated 15 times under reduced pressure, and an aqueous solution of zinc acetate is added. After aging at 60 ° C. for 10 hours, the suspension in which the gel was formed was poured into ethanol, and the precipitate was filtered (5C filter paper).
After washing with ethanol, it was dried at 90 ° C. overnight and calcined to obtain G-2. In addition, baking was performed like G-1.
[0023]
(Production of phosphor-containing slurry and solid fine particle dispersion)
Using the inorganic phosphors G-1 and G-2 produced above, respective phosphor-containing slurries were prepared according to the following formulation.
-Phosphor-containing slurry formulation-
Inorganic phosphor 10 parts by weight Water 90 parts by weight The obtained phosphor-containing slurry was pre-dispersed with a dissolver to prepare coarse dispersion samples G-10 and G-20, and further using a bead mill disperser (manufactured by Getzman). The dispersion was performed under the dispersion conditions and mechanical energy E conditions shown in Table 1 to obtain solid fine particle dispersion samples G-11 to G-13 and G-21 to G-23. At this time, zirconia beads having an average particle diameter of 0.3 mm were used, and the filling rate of the beads was 70%.
<< Evaluation of solid fine particle dispersion sample >>
The average particle size and the emission intensity of the obtained solid phosphor fine particle dispersion were measured, and the respective particle sizes and the relative emission intensity (%) when the emission intensity of the coarse dispersion sample G-10 was taken as 100%. The results are shown in Table 1. The particle size was measured by Malvern, and the emission intensity was measured by a fluorometer (manufactured by JASCO Corporation).
[0024]
[Table 1]

[0025]
From Table 1, in each case of the precursor synthesis by the solid phase method and the precursor synthesis by the liquid phase method, when the beads mill dispersion was performed under the fine particle dispersion conditions that increase the mechanical energy E, This indicates that the emission intensity is significantly reduced, that is, the emission efficiency is reduced. On the other hand, when the dispersion condition is changed and the mechanical energy E is reduced to 2.5 × 10 ⁵ [m ² / s] or less, the decrease in luminous intensity decreases, and the decrease in luminous efficiency can be suppressed. When the mechanical energy E was reduced to 4.1 × 10 ⁴ [m ² / s] or less, the tendency was remarkable. Among them, Samples G-22 and G-23 containing an inorganic phosphor synthesized by a liquid phase method of a precursor also have a small average particle diameter of the fine particle dispersion despite the small mechanical energy E, and furthermore, The effect of reducing the decrease in emission intensity is more remarkable. This is because when the precursor is synthesized by a liquid phase method, the primary particle size is originally small, so that it is possible to produce an inorganic phosphor at a relatively low firing temperature, thereby suppressing aggregation during firing, As a result, it is shown that a solid fine particle dispersion having a small average particle diameter can be obtained with a small mechanical energy without lowering the emission intensity.
[0026]
Example 2
In the method for producing the inorganic phosphor solid fine particle dispersion sample G-23 of Example 1, a solid fine particle dispersion sample G-24 was produced in the same manner as G-23 except that the phosphor-containing slurry was changed to the following formulation. did.
-Phosphor-containing slurry formulation-
Inorganic phosphor 10 parts by weight Emulgen 420 2 parts by weight Joncryl 170 2 parts by weight Water 86 parts by weight << Evaluation of solid fine particle dispersion sample >>
The average particle size and emission intensity of the obtained G-24 were measured in the same manner as in Example 1. As a result, the average particle size was 0.16 μm, and the relative emission intensity when the emission intensity of G-10 was 100% was 660. %Met.
From this result, it can be seen that when the dispersion treatment is performed in the presence of the surfactant, the solid dispersion is atomized and the effect of suppressing the decrease in the emission intensity of the dispersion is remarkable.
[0027]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the damage by dispersion | distribution can be limited and the micro fluorescent substance which can endure practical use can be obtained.

Claims (4)

The inorganic phosphor solid fine particles, wherein the inorganic phosphor is dispersed by applying a mechanical energy E having a mechanical energy E represented by the following formula of 2.5 × 10 ⁵ m ² / s or less. A method for producing a dispersion.
E = tV ²
(Where V represents the peripheral speed (m / s) and t represents the dispersion time (s)) 2. The inorganic phosphor solid fine particles according to claim 1, wherein at least a part of the step of producing the solid fine particle dispersion is performed in the presence of one kind selected from a surfactant and a polymer dispersant. A method for producing a dispersion. The method according to claim 1 or 2, wherein the dispersing step is performed using a bead mill. The method according to any one of claims 1 to 3, wherein the inorganic phosphor is synthesized by a liquid phase method.