JP2008189761A - Method for producing particulate fluorescent material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently producing a nano-size fluorescent material emitting fluorescent light in high luminance by ultraviolet rays. <P>SOLUTION: The method for producing a particulate fluorescent material expressed by formula YVO<SB>4</SB>:A (A is a rear earth metal except for yttrium) and emitting fluorescent light by ultraviolet excitation comprises a step to form a solution 1 by adding a complex-forming compound to an yttrium compound and a compound of a rare earth metal other than yttrium in the presence of water, a step to form a solution or dispersion 2 by dissolving or dispersing a vanadium compound in water, and a step to mix and react the solution 1 with the solution or dispersion 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for efficiently producing a nano-sized phosphor that emits fluorescent light with high brightness by ultraviolet rays.

  2. Description of the Related Art Conventionally, various inorganic phosphors that emit fluorescence when irradiated with light energy such as ultraviolet rays have been used in the fields of art / decoration and security. Usually, phosphor powder is processed into paint or ink, and the object is painted or silk-screen printed. Specifically, in the art / decoration field, artists, craft painting engineers, etc. on the walls and ceilings of theme parks, hotels, underpasses, trains, etc. draw decorative paintings etc. with the phosphor-containing paint, By irradiating ultraviolet rays with a black light or the like, a vivid fluorescent coloring image emerges. In the security field, silk screen printing is performed as a special usage.

Recently, due to dramatic progress in ink jet printing technology, many colorful and high-definition indoor and outdoor advertising signs and electrical signs have become popular. In the art / decorative painting and security fields as well, there are growing expectations for high-definition and durable invisible printing products using such inkjet printing technology.
However, due to the structure of the apparatus, such an application requires ultrafine inorganic phosphor particles of 1000 nm or less, and in some cases, 100 nm or less. Until now, inorganic phosphors suitable for such applications have been known. It was not done. In general, inorganic phosphors are made by a dry method (powder metallurgy), that is, by mixing raw inorganic compound powders, firing at several hundred to several hundreds of degrees C, and then physically pulverizing. However, in such a dry method, it is difficult to pulverize to a particle size below a certain level, and even if it can be finely pulverized, the emission luminance of the phosphor is remarkably lowered. I could not do it.
On the other hand, as a method for producing a rare earth phosphate phosphor, a rare earth element such as Y and P, Ce, and Tb are dissolved, and an aqueous solution of the phosphor material is formed into droplets and introduced into a pyrolysis reactor together with a carrier gas to 800. A method of heating at ˜1900 ° C. (Patent Document 1) and a method of heating an alkaline earth metal compound in the presence of an organic solvent (Patent Document 2) are proposed.

JP 2002-155276 A JP 2006-213822 A

  However, in the method disclosed in Patent Document 1 in which an inorganic compound as a raw material is reacted in a gas phase, when the fine phosphor is industrially produced, the production facility must be large-scale, and the production cost There are problems such as becoming excessive. In addition, in the method disclosed in Patent Document 2 in which an inorganic compound as a raw material is reacted in a liquid phase, an organic solvent is used, so there is a concern about the removal of the organic solvent and the environment.

As a result of intensive studies on the prior art, the present inventors have found that a fine phosphor with high emission luminance can be produced by reacting the raw material for forming the phosphor in water, thereby completing the present invention. It has been made.
That is, the present invention is a method for producing a fine phosphor represented by the formula YVO ₄ : A (A represents a rare earth metal other than yttrium) that emits fluorescence when excited by ultraviolet rays.
(1) forming a solution 1 by dissolving an yttrium compound and a compound of a rare earth metal other than yttrium with a complex-forming compound in the presence of water;
(2) a step of dissolving or dispersing a vanadium compound in water to form a solution or dispersion 2; and
(3) mixing and reacting the solution 1 and the solution or dispersion 2;
It is related with the manufacturing method of the fine particle fluorescent substance characterized by comprising.

  According to the present invention, a high-luminance phosphor can be efficiently produced by reacting a raw material inorganic compound in water without using a special apparatus. The phosphor produced according to the present invention is a fine particle having a uniform particle size of 1000 nm or less, and emits fluorescence when excited by ultraviolet light.

Hereinafter, the present invention will be described in detail.
Preferable examples of the yttrium compound used in the present invention include yttrium hydroxides and chelates (for example, chelating agents include aminocarboxylic acid chelating agents and phosphonic acid chelating agents. ), Oxyacid salts (eg nitrates, sulfates, phosphates, borates, silicates, vanadates, etc.), organic acid salts (eg carboxylates, sulfonates, phenol salts, sulfinates) 1,3-diketone type compound salts, thiophenol salts, oxime salts, aromatic sulfonamide salts, primary and secondary nitro compound salts, etc.), halides (for example, halogens include fluorine and , Chlorine, bromine, etc.), alkoxide (for example, linear or branched alkoxy group having 1 to 15 carbon atoms, such as methoxy group, ethoxy group, pro Poxy group, butoxy group and the like are preferably mentioned) and the like can be preferably used. Typical examples of these include nitrates, sulfates, phosphates, borates, silicates, carbonates, carboxylates (for example, carboxylic acids such as oxalic acid, acetic acid, benzoic acid, etc.), halides ( For example, as halogen, fluorine, chlorine, bromine and the like, alkoxide (for example, a linear or branched alkoxy group having 1 to 15 carbon atoms, for example, methoxy group, ethoxy group, propoxy group, butoxy group) And the like can be preferably mentioned). Among these, nitrates, carboxylates, and alkoxides can be particularly preferably used. Typical examples of these include yttrium nitrate, yttrium oxalate, and yttrium isopropoxide.

  Specifically, as the rare earth metal element other than yttrium, Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu are preferable. Examples of rare earth compounds include rare earth metal elements themselves, hydrides and halides thereof (eg, halogens include fluorine, chlorine, bromine, etc.), hydroxides, sulfides, oxyacid salts (eg, Nitrates, sulfates, phosphates, borates, silicates, vanadates, etc.), organic acid salts (eg carboxylates, sulfonates, phenol salts, sulfinates, 1,3-diketone compounds) Salts, thiophenol salts, oxime salts, aromatic sulfonamide salts, primary and secondary nitro compound salts, etc.), alkoxides (for example, linear or branched alkenyl having 1 to 15 carbon atoms). Preferable examples include a ruxoxy group such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Representative examples include europium oxalate, erbium nitrate, samarium acetate, cerium nitrate, and the like, and among these, a compound of Eu can be used particularly preferably.

  Preferable examples of the vanadium compound used in the present invention include vanadium hydroxides and chelates (for example, chelating agents include aminocarboxylic acid chelating agents and phosphonic acid chelating agents). ), Oxides, oxyacid salts (e.g. nitrates, sulfates, phosphates, borates, silicates, vanadates, etc.), organic acid salts (e.g. carboxylates, sulfonates, phenol salts, Sulfinates, salts of 1,3-diketone compounds, thiophenol salts, oxime salts, salts of aromatic sulfonamides, salts of primary and secondary nitro compounds, etc., halides (for example, as halogens) Fluorine, chlorine, bromine, etc.), alkoxide (for example, straight or branched alkoxy group having 1 to 15 carbon atoms such as methoxy group, ethoxy group, Roxy group, butoxy group and the like are preferably mentioned) and the like can be preferably used. Typical examples of these include nitrate, sulfate, phosphate, borate, silicate, vanadate, carbonate, carboxylate (for example, oxalic acid, acetic acid, benzoic acid, etc.) , Halides (for example, halogen such as fluorine, chlorine, bromine, etc.), alkoxides (for example, linear or branched alkoxy groups having 1 to 15 carbon atoms, such as methoxy groups, ethoxy groups, propoxys) Group, butoxy group and the like can be preferably mentioned). Among these, nitrates, vanadates, carboxylates, and alkoxides can be particularly preferably used. Typical examples of these include triisopropoxy vanadium oxide and potassium vanadate.

An auxiliary activator B may be further added to the phosphor represented by the formula YVO ₄ : A (A is a rare earth metal element other than yttrium). In this case, the formula YVO ₄ : A, B (A is a rare earth metal element other than yttrium, and B is an element belonging to Groups 13 to 17 of the periodic table of elements (long period type) (hereinafter simply referred to as It is referred to as “P block element”))). However, specific examples of the P block element include, for example, Al, Zn, Ga, Ge, Cd, In, Sn, Sb, Hg, Tl, Pb, Bi, and Po. Among these, Bi, Ga, and Ge can be suitably used, and Bi is particularly preferable. When these P block elements are used in the phosphor synthesis reaction, hydrides, halides (for example, halogens such as fluorine, chlorine, bromine, etc.), hydroxides, sulfides, oxyacid salts (for example, nitrates) Sulfates, phosphates, borates, silicates, vanadates, etc.), organic acid salts (eg carboxylates, sulfonates, phenol salts, sulfinates, 1,3-diketone type compounds) Salts, thiophenol salts, oxime salts, salts of aromatic sulfonamides, salts of primary and secondary nitro compounds, etc.), alkoxides (for example, alkoxy groups having 1 to 15 carbon atoms, linear or branched) P block element compounds such as, for example, methoxy group, ethoxy group, propoxy group, butoxy group and the like are preferably used.

  A complex-forming compound is a substance that forms a complex with yttrium, a rare earth metal element, and a P block element, and contains two or more kinds of atoms coordinated to metal ions, such as oxygen, nitrogen, and sulfur, and a chelate ring. A compound to be formed, which has an OO coordination, an NN coordination, an SS coordination, an OH coordination, an SN coordination, an OS coordination, and a plurality of them. It is a conformational compound. Specific examples include oxalic acid, acetylacetone, citric acid, ethylene glycol, ethylenediamine, 1,10-phenanthroline, dithiol, ethylenediaminetetraacetic acid (EDTA), thiooxin 3-mercapto-p-cresol, and derivatives thereof. In the present invention, citric acid, oxalic acid, ethylene glycol and the like are particularly preferably used, but are not particularly limited thereto. Addition of this complex-forming compound is effective in controlling mixed crystal precipitation and particle growth, and improves the dispersion stability of the produced fine particle phosphor.

The fluorescent substance of the present invention contains a rare earth metal element that is a luminescence center (activator) in the crystal of yttrium oxide, and an auxiliary activator that assists the light emission of an optional activator, so that ultraviolet rays and the like are contained. It emits light by the excitation source. The particle size of the fine phosphor is based on the particle size distribution measured by the dynamic light scattering method.
Although not limited by theory, according to observations of experiments, in the present invention, the yttrium compound, the activator raw material compound, and the auxiliary activator raw material compound are dissolved or dispersed in water and complex. By forming a mixed crystal in the presence of the forming compound and further adding a vanadium compound, a fine phosphor is considered to be synthesized.
Therefore, it is necessary that the yttrium compound, the activator raw material compound (component A compound), and the auxiliary activator raw material compound (P block element compound) be sufficiently dissolved or stably dispersed in water. .

In Solution 1, the yttrium compound is generally in the range of 0.0001 to 0.6 parts by mass, preferably 0.001 to 0.5 parts by mass with respect to 1 part by volume of water. For example, 0.0001 to 0.6 g, preferably 0.001 to 0.5 g is appropriate for 1 ml of water.
By using within this range, an aqueous dispersion of a fine phosphor having a particle diameter of preferably 1000 nm or less, for example, 5 to 1000 nm can be obtained.
When the added amount is less than 0.0001 part by mass, the production efficiency of the fine phosphor tends to be lowered. On the other hand, when the amount is more than 0.6 parts by mass, the fine phosphor is aggregated and it is difficult to obtain a desired uniform dispersion of the fine phosphor.

Similarly, the amount of the rare earth metal compound other than yttrium is based on solubility or dispersibility in water, but in order to produce a fine phosphor with high emission luminance with high production efficiency, with respect to 1 mol of the yttrium compound, It is preferably 40 mol% or less, preferably within the range of 0.005 to 30 mol%.
The amount of the complex-forming compound is 0.0001 to 0.7 parts by mass, preferably 0.001 to 0.6 parts by mass with respect to 1 ml of water. In order to form a complex, yttrium elements and rare earth metals other than yttrium are used. It is necessary to add them in consideration of the addition amounts of elements and bismuth elements. Further, since the complex-forming compound contributes to the dispersion stability of the particles, if the addition amount is small, it does not function as a dispersant, which is not preferable.
In the solution or dispersion 2, the amount of the vanadium compound is suitably 0.0001 to 0.6 g, preferably 0.001 to 0.5 g, per 1 ml of water.
The amount of the P-block element (B) compound is based on solubility or dispersibility in water, but in order to produce a fine phosphor with high emission luminance with high production efficiency, 60 mol per 1 mol of the yttrium compound. It is preferable to keep it in the range of mol% or less, preferably 0.005 to 50 mol%. The compound of the P block element (B) can be added to the solution 1 or the solution or dispersion 2 at any time.
In addition, in the case of using a plurality of yttrium compounds, rare earth metal compounds other than yttrium, vanadium compounds, and optionally P-block element compounds, the mixing ratio may be appropriately changed depending on the composition, particle size, etc. of the obtained fine phosphor. Is possible.
In the method of the present invention, it is preferable to adjust the pH in the step 3 of mixing the solution 1 and the solution or dispersion 2, and the production of the phosphor can be promoted. The pH is, for example, about 4 to 11, preferably 6 to 10. When the pH is lower than 4, polyvanadate is easily generated, and when the pH is higher than 11, a hydroxide is generated, so that it is difficult to generate a target phosphor.

The reaction in the present invention can be carried out at atmospheric pressure or at a pressure higher than the boiling point of water. When the reaction is performed at atmospheric pressure, it is not necessary to make the production facility excessive, and it becomes possible to produce the fine phosphor more easily and efficiently.
If heating temperature is under atmospheric pressure, it is preferable to carry out in the range of 20 to 100 degreeC, for example. When the heating temperature is lower than 20 ° C., the reaction of the fine phosphor tends to be remarkably slow, and the production efficiency tends to decrease. The reaction time under atmospheric pressure is, for example, 1 minute to 72 hours, and preferably 10 minutes to 10 hours is sufficient.
Moreover, it can also react under high temperature about 100-400 degreeC under pressure. In this case, there is an advantage that the solubility of the raw material is increased and the reaction time can be shortened.

In the present invention, an organic dispersant such as a surfactant, an inorganic dispersant, a polymer dispersant, or an ion (for example, acetate ion) that contributes to dispersion stability is added to improve dispersion stability during the reaction. May be added. Moreover, it is also possible to add additives, such as antioxidant and a reducing agent, as needed.
Moreover, in the case of reaction, it is also possible to react in nitrogen gas or argon gas atmosphere. It is possible to prevent oxygen from being mixed into the reaction system, and to prevent deterioration in phosphor performance such as reduction in fluorescence intensity of the phosphor and coloring of the product.
The present invention is preferably carried out while stirring water using a stirrer. By using such a stirrer, the reaction system can be made uniform, the reaction efficiency can be increased, and stable production of fine phosphors becomes possible.

<Characteristics of fine phosphor>
The fine phosphor produced according to the present invention has an average particle size of 1000 nm or less (the lower limit is, for example, about 5 nm), which is much smaller than conventional phosphors. Accordingly, the fine phosphor can be used for a wide range of applications such as coating and ink jet printer ink. In applications where higher dispersion stability or transparency under visible light is required, a fine phosphor of 100 nm or less can be used.
In addition, the above-mentioned fine phosphor emits fluorescence when irradiated with ultraviolet rays, but it is excited even in the near ultraviolet rays in the wavelength region of 300 to 400 nm, so that it can be made to emit fluorescence even with a light source such as a black light or an ultraviolet LED. It is. For this reason, it is suitable for the prevention of counterfeiting in the art / decoration field, various securities, and branded goods, which are desirable to emit near ultraviolet rays.
Furthermore, as a matter of course, the phosphor of the present invention is not limited to the above-mentioned use, but is used in the field of flat panels and displays such as lighting such as fluorescent lamps and LEDs, PDP, liquid crystal, and FED. Is also possible.

EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further in detail, the scope of the present invention is not limited at all by these Examples.
For the particle size distribution, Malvern HPPS manufactured by Malvern was used. This measuring machine is an apparatus for measuring a particle size distribution by a dynamic light scattering method.

<Example 1>
A cooling tube, a thermometer, and a stirring device were attached to a 200 ml three-necked flask as a reflux device, and the flask was placed in a water bath. In the flask, 40.0 ml of water, yttrium nitrate hexahydrate 1.00 g (2.6 mmol), europium nitrate hexahydrate 0.09 g (0.2 mmol), trisodium citrate dihydrate 0.62 g And stirred at 60 ° C. for 2 hours to prepare Solution 1.
Separately, 40.0 ml of water adjusted to pH 12.5 with sodium hydroxide is weighed, and 0.55 g (3.0 mmol) of sodium orthovanadate is added and dissolved therein to prepare Solution 2, The solution was added dropwise to the three-necked flask containing the solution 1.
After completion of dropping, the mixture was stirred at 60 ° C. for 3 hours. The pH immediately after the dropping was 8.5. Then, it cooled to room temperature and obtained the slightly yellowish cloudy water dispersion liquid. When the fine particle substance in the obtained dispersion liquid was measured by Malvern HPPS (manufactured by Malvern), it was uniform particles having an average particle diameter of 48 nm (see FIG. 1).
When this dispersion was irradiated with an ultraviolet lamp having a main wavelength of 302 nm, red fluorescence was confirmed. Further, when the emission wavelength was confirmed with PL-250 (manufactured by JASCO Corporation), the peak of the emission wavelength was confirmed at 615 nm. Further, as a result of qualitative analysis of the fine particles with an X-ray diffractometer (XRD-6100, manufactured by Shimadzu Corporation), it was consistent with the diffraction data of yttrium vanadate. Moreover, when it confirmed with the ICP emission-spectral-analysis apparatus (ICPS-7510, Shimadzu Corporation make), it has confirmed that it was a substance which consists of an element of vanadium, yttrium, and europium.

<Example 2>
A cooling tube, a thermometer, and a stirring device were attached to a 200 ml three-necked flask as a reflux device, and the flask was placed in a water bath. 40.0 ml of water, 0.10 g (0.3 mmol) of yttrium nitrate hexahydrate and 0.05 g (0.1 mmol) of terbium nitrate hexahydrate were added to the flask, and the mixture was stirred at 80 ° C. for 1 hour. The acid 0.19g was added and it stirred at 80 degreeC for 2 hours, and prepared the solution 1.
Separately, 40.0 ml of water adjusted to pH 12.5 with sodium hydroxide was weighed into a 100 ml beaker, and 0.55 g (3.0 mmol) of sodium orthovanadate was added and dissolved therein to prepare Solution 2. . The obtained solution 2 was dropped into a three-necked flask containing the solution 1.
After completion of dropping, the mixture was stirred at 80 ° C. for 3 hours. The pH immediately after the dropwise addition was 8.2. Then, it cooled to room temperature and obtained the slightly yellowish cloudy water dispersion liquid. When the fine particle substance in the obtained dispersion liquid was measured with Malvern HPPS (manufactured by Malvern), it was uniform particles having an average particle diameter of 38 nm (see FIG. 2).
When this dispersion was irradiated with an ultraviolet lamp having a main wavelength of 302 nm, green fluorescence was confirmed. Moreover, when the emission wavelength was confirmed with PL-250 (made by JASCO Corporation), the peak of the emission wavelength was confirmed at 544 nm. Further, as a result of qualitative analysis of the fine particles with an X-ray diffractometer (XRD-6100, manufactured by Shimadzu Corporation), it was consistent with the diffraction data of yttrium vanadate. Moreover, when it confirmed with the ICP emission-spectral-analysis apparatus (ICPS-7510, Shimadzu Corporation make), it has confirmed that it was a substance which consists of elements of vanadium, yttrium, and terbium.

<Example 3>
A cooling tube, a thermometer, and a stirring device were attached to a 200 ml three-necked flask as a reflux device, and the flask was placed in a water bath. After adding 40.0 ml of water, 1.00 g (2.6 mmol) of yttrium nitrate hexahydrate and 0.09 g (0.2 mmol) of europium nitrate hexahydrate to the flask, and stirring at 70 ° C. for 1 hour, 0.62 g of trisodium citrate dihydrate was added, and after 30 minutes, 0.48 g (1.2 mmol) of bismuth citrate was added, followed by stirring at 70 ° C. for 2 hours to prepare Solution 1.
Separately, 40.0 ml of water adjusted to pH 12.5 with sodium hydroxide was weighed into a 100 ml beaker, and sodium orthovanadate 0.55 g (3.0 mmol) was added thereto to prepare solution 2, Solution 2 was added dropwise to the three-necked flask containing Solution 1. After completion of dropping, the mixture was stirred at 70 ° C. for 3 hours. The pH immediately after the addition was 7.5. Then, it cooled to room temperature and continued stirring at room temperature for 72 hours, and the slightly yellowish cloudy water dispersion liquid was obtained. When the fine particle substance in the obtained dispersion liquid was measured by Malvern HPPS (made by Malvern), it was a uniform particle | grain with an average particle diameter of 55 nm (refer FIG. 3).
When this dispersion was irradiated with an ultraviolet lamp having a main wavelength of 365 nm, red fluorescence was confirmed. Further, when the emission wavelength was confirmed with PL-250 (manufactured by JASCO Corporation), the peak of the emission wavelength was confirmed at 615 nm. Further, as a result of qualitative analysis of the fine particles with an X-ray diffractometer (XRD-6100, manufactured by Shimadzu Corporation), it was consistent with the diffraction data of yttrium vanadate. Moreover, when it confirmed with the ICP emission-spectral-analysis apparatus (ICPS-7510, Shimadzu Corporation make), it has confirmed that it was a substance which consists of elements of vanadium, yttrium, europium, and bismuth.

  ADVANTAGE OF THE INVENTION According to this invention, the nanosize fluorescent substance which fluoresces with high brightness | luminance by an ultraviolet-ray can be manufactured efficiently.

FIG. 3 is a diagram showing measurement data of the particle size distribution of the fine phosphor obtained in Example 1. 6 is a graph showing measurement data of a particle size distribution of a fine phosphor obtained in Example 2. FIG. It is a figure which shows the measurement data of the particle size distribution of the fine fluorescent substance obtained in Example 3.

Claims (9)

A method for producing a fine phosphor expressed by the formula YVO ₄ : A (A represents a rare earth metal other than yttrium) that emits fluorescence by ultraviolet excitation,
(1) forming a solution 1 by dissolving an yttrium compound and a compound of a rare earth metal other than yttrium with a complex-forming compound in the presence of water;
(2) a step of dissolving or dispersing a vanadium compound in water to form a solution or dispersion 2; and
(3) mixing and reacting the solution 1 and the solution or dispersion 2;
A method for producing a fine phosphor, comprising:   The rare earth metal other than yttrium is selected from the group consisting of Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. The method described in 1.   The method according to claim 1, wherein an average particle diameter of the phosphor is 5 to 1000 nm. The phosphor is represented by the formula YVO ₄ : A, B (A represents a rare earth metal other than yttrium, and B represents an element belonging to Groups 13 to 17 of the periodic table (long period type)). The method of claim 1 as indicated.   The yttrium compound, the vanadium compound, a compound of a rare earth metal other than yttrium, and / or a compound of an element belonging to Group 13 to Group 17 of the periodic table (long period type) is a hydroxide, chelate, inorganic 2. The method of claim 1 selected from the group consisting of acid salts, organic acid salts, oxyacid salts, halides and alkoxides.   The method according to claim 4, wherein B is a periodic table (long-period type) Group 15 element.   The method of claim 1, wherein A is europium.   The method of claim 1, wherein the complexing compound is selected from the group consisting of citric acid, oxalic acid, and ethylene glycol.   The method of claim 8, wherein the complexing compound is citric acid.

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