JP6112531B2 - Red phosphorescent phosphor and method for producing the same - Google Patents

Description

  The present invention relates to a long afterglow material that emits red light by ultraviolet excitation and continues to emit light after excitation, and a manufacturing method for manufacturing the long afterglow material.

Phosphorescent materials that can emit light even after light excitation (phosphorescent phosphors) are expected to be used as materials for building a safe and secure society because they function as guidance signs and lighting even during disasters and power outages. Yes. Up to now, aluminate SrAl ₂ O ₄ : Eu, Dy (see Patent Document 1) showing green light emission is known as a phosphorescent material showing long afterglow, and is applied to a guidance display board at the time of disaster. ing. Further, Sr _1.995 MgSi ₂ O ₇ : Eu _0.005 and Dy _0.025 Cl _0.025 are known as blue phosphorescent materials (see Patent Document 2).

On the other hand, as red phosphorescent materials, the following materials 1 and 2 are known as those having a relatively long afterglow time.
1. Y ₂ O ₂ S: Ti _x , Mg _y , Gd _a (see Patent Document 3),
2. CaS: Mainly composed of compounds represented by Eu and Tm, containing 10 ^X mol% Eu and 10 ^Y mol% Tm with respect to Ca, and -3≤X≤-1, -3≤Y ≦ 0 and 0 ≦ YX ≦ 2 (see Patent Document 4).
However, these 1 and 2 red phosphorescent materials all have low emission intensity, and are sulfur oxides, and thus have a great problem in long-term stability such as stability against ultraviolet rays and heat and weather resistance.

In addition to the red phosphorescent material having such a long-term stability problem, a metal oxide red phosphorescent material that is stable against ultraviolet rays and heat is also known.
1. (Zn _1-x Mg _x ) O · n (Ga _1-y Cr _y ) ₂ O ₃ (x, y and n in the composition formula are values satisfying the following conditions, respectively.
0 ≦ x ≦ 1.0, 1 × 10-5 ≦ y ≦ 1 × 10 ⁻¹ , 0.95 ≦ n ≦ 1.05) (see Patent Document 5)
2. A red phosphorescent phosphor comprising a sintered body of a compound mainly composed of germanate having a Ge-O bond activated by a transition element and a rare earth element and having afterglow characteristics for red (see Patent Document 6)
3. Ca _1-X Sr _X TiO ₃ : Pr red phosphorescent material (see Non-Patent Document 1).
However, since the afterglow time is short, practical application is difficult.

JP 07-011250 JP-A-9-94833 WO2007 / 145167 JP-A-9-59615 JP 10-259375 A JP2001-26777

P.T.Diallo et al. Phys.Status SolidsiA 1997,160.255.

  Therefore, the present invention aims to provide a phosphorescent phosphor that eliminates the above-described drawbacks, has a long phosphorescence red phosphorescence characteristic, is chemically stable and has excellent weather resistance, and a method for producing the phosphorescent phosphor. .

In order to eliminate the drawbacks of the conventional red phosphorescent material, the present inventors have conducted intensive studies on an oxide-based phosphor. As a result, the composition formula A _a B _b O _c [where A is Ca, Sr , Ba, Mg is at least one element selected from B, B is at least one element selected from Ti, Zr, Sn, Mn, Mo, Ru, and a, b, c are the following numerical ranges, respectively. It is. 0.8 ≦ a ≦ 5, 1.0 ≦ b ≦ 4, 2.5 ≦ c ≦ (a + 2b)], and at least one element selected from Pr and La, Eu, Dy, and Sm. It was found that the red phosphorescent phosphor contained contained that it emitted red light for a long time even after the light excitation was stopped, and the present invention relating to the red phosphorescent phosphor could be completed.

  In addition, metal organic compounds containing those metal elements are mixed in a solution, or solid raw materials are uniformly mixed with nano-size raw materials using a planetary ball mill, and these raw materials are subjected to a preliminary firing step of less than 500 ° C., 500 ° C. It has been found that it is effective to produce a red phosphor with long-time phosphorescence by using a firing process of less than 1500 ° C. or more and a high-temperature firing process of 1500 ° C. or more twice. The present invention relating to a method for producing a phosphor could be completed.

In order to achieve the above object, the following invention is specifically provided.
(1) Composition formula A _a B _b O _c [wherein A is at least one element selected from Ca, Sr, Ba and Mg, and B is at least one element selected from Ti, Zr and Sn. And a, b, and c are the following numerical ranges, respectively. 0.8 ≦ a <1, b = 1, c = 3 ], and a red phosphorescent phosphor obtained by co-substituting at least one element selected from Pr and La, Eu, Dy, and Sm.
(2 ) The red phosphor as described in (1 ) above, wherein the Pr content is 0 mol% <Pr <0.01 mol%, and the total content Ln of La, Eu, Dy, Sm is 0 mol% <Ln <10.0 mol% Phosphor.
( 3 ) A red luminous product containing the red luminous phosphor according to (1) or (2 ) above.
( 4 ) The method for producing a red phosphorescent phosphor according to (1) or (2) above, wherein a raw material containing a metal element selected so as to have a ratio represented by the above composition formula is obtained by a planetary ball mill. A method for producing a red phosphor, comprising a step of forming nanoparticles or a step of forming a solution using a solvent.
( 5 ) The method for producing a red phosphor as described in ( 4 ) above, wherein a metal organic compound is used as a raw material containing a metal element.
( 6 ) Described in ( 4 ) or ( 5 ) above, comprising a preliminary firing step of less than 500 ° C, a firing step of 500 ° C or more and less than 1500 ° C, and at least two firing steps of 1500 ° C or more Manufacturing method of red phosphorescent phosphor.
( 7 ) The manufacturing method of the red luminous phosphor as described in said ( 6 ) made into a red luminous product in the last baking process of 1500 degreeC or more.

  The red phosphor of the present invention has long afterglow red phosphorescence characteristics, is chemically stable and has excellent weather resistance.

FIG. 1 is a graph showing the effect of co-substitution of Dy, Eu, La, Sm, and Lu on afterglow luminance. FIG. 2 is a graph showing the effect of La co-substitution concentration on afterglow luminance. FIG. 3 is a graph showing afterglow characteristics of Pr0.2 mol% + La 2 mol% co-doped red phosphorescent phosphors produced by different firing processes (after firing at 400 ° C. and 1500 ° C.). FIG. 4 is a graph showing afterglow characteristics of Pr0.2 mol% + La 2 mol% co-doped red phosphorescent phosphors produced by different firing processes (after firing at 400 ° C. and then fired at 1300 ° C.).

The present invention relates to a composition formula A _a B _b O _c [wherein A is at least one element selected from Ca, Sr, Ba, Mg, and B is Ti, Zr, Sn, Mn, Mo, Ru. A, b, and c are each in the following numerical range. 0.8 ≦ a ≦ 5, 1.0 ≦ b ≦ 4, 2.5 ≦ c ≦ (a + 2b)], and at least one element selected from Pr and La, Eu, Dy, Sm It is the red luminous fluorescent substance to contain and its manufacturing method.

  Regarding the Pr content, the range of 0 mol% <Pr <0.01 mol% is suitable from the viewpoint of afterglow luminance (more preferably 0.001 mol% <Pr <0.005 mol%). In addition, the total content Ln of La, Eu, Dy, and Sm that are the second doping metals is suitably in the range of 0 mol% <Ln <10.0 mol% from the viewpoint of afterglow luminance (more preferably, 0.01%). mol% <Ln <6.0 mol%).

Further, the A site of the composition formula A _a B _b O _c is based on the Ca and B sites, but the Ti element, but Sr, Ba and Mg having different ionic radii are used as the A site and Zr, Sn, and B are used as the B site. By using Mn, Mo, and Ru, the electronic structure including the band gap of the base material can be changed, so that the light absorption efficiency can be increased. For this reason, the afterglow brightness and the afterglow time can be adjusted by controlling the elemental composition of the A and B sites.

  In order to produce this red phosphorescent material, it is preferable to use a compound that dissolves in a solvent containing a metal element, such as a metal organic compound or nitrate, and for the precursor metal organic compound raw material used in the process of the invention, a metal organic Acid salts, β-diketonates, metal alkoxides, and the like can be used. Specific examples include metal acetate, metal 2-ethylhexanoate, metal acetylacetonate, metal naphthenate, and the like. Any metal organic compound that can be dissolved in a solvent can be used without particular limitation. The solvent is preferably methanol, ethanol, propanol, butanol, hexanol, heptanol, ethyl acetate, butyl acetate, toluene, xylene, benzene, acetylacetonate, ethylene glycol, water or the like. In addition, solid materials such as metal oleates, metal stearates, oxides and carbonates that contain metals that cannot be dissolved in solvents can be used, but in this case, they are mixed uniformly by a planetary ball mill. In addition, it is preferable to use a raw material that may contain a nanoparticulated solvent.

In the case of wet mixing using a solvent, the mixed raw materials are dried to remove the solvent. In addition, when an organic metal compound containing metal or nitrate is used as a raw material, the step of removing the solvent and organic components at a temperature of less than 500 ° C, 500 ° C to less than 1500 ° C (preferably 700 ° C to 1300 ° C) ), A baking process using a multi-stage temperature, wherein a baking process of 1500 ° C. or higher (preferably 1500 ° C. or higher and 1800 ° C. or lower) is performed at least twice. In such a multi-stage temperature range, the metal composition is represented by a metal composition formula of A _a B _b O _c : 0.8 ≦ a ≦ 5, 1.0 ≦ b ≦ 4, 2.5 ≦ c ≦ (a + 2b), and A Is based on an oxide using at least one element selected from Ca, Sr, Ba, Mg, and B, each of which is selected from Ti, Zr, Sn, Mn, Mo, and Ru. From Pr and further La, Eu, Dy, and Sm A red phosphorescent phosphor containing at least one selected element can be produced. Such multi-stage baking is desirable for obtaining long afterglow characteristics because it prevents composition shift and impurity phase generation due to decomposition and evaporation. Note that grinding, mixing, and tableting (pressure molding) of the sintered body between each firing are more desirable in preventing composition shift and impurity phase generation, but grinding and tableting between each firing ( Even if multi-stage firing is performed without performing pressure molding, it is effective in obtaining long residual characteristics.

  Of the two or more firing steps at 1500 ° C. or higher, the red phosphorescent phosphor produced in the final firing step can be a sintered molded body (phosphorescent product) having an appropriate shape. Further, after the final firing step, the phosphorescent sintered compact can be appropriately pulverized to obtain a fine powdery red phosphorescent phosphor (red phosphorescent material). The fine red phosphorescent phosphor is applied to various object surfaces together with solid binders and liquid media, or mixed with plastics, rubber, vinyl chloride, synthetic resin or glass, etc. Or a fluorescent film.

  Hereinafter, the features of the present invention will be described in more detail based on examples. In addition, the following description is for making an understanding of this invention easy, and is not restrict | limited to this. That is, modifications, embodiments, and other examples based on the technical idea of the present invention are included in the present invention.

  Fig. 1 shows a sample in which Pr and Dy, Eu, La, Sm, and Lu are co-substituted with 2 mol% of a metal element, and each sample is irradiated with ultraviolet light having a main emission wavelength of 365 nm for 2 minutes to stop irradiation. Afterglow characteristics were measured, and the measurement method was to irradiate each phosphor sample with a lamp, and the afterglow characteristics of the phosphorescent material after the lamp was turned off (elapsed time after the lamp was turned off and at that time) (Correlation with the light emission intensity of each of the phosphorescent materials) is obtained by measuring the afterglow luminance with time using a luminance meter.

As is apparent from FIG. 1, it can be seen that the phosphorescent material co-substituted with La has extremely remarkable afterglow characteristics as compared with the non-co-substituted Ca _0.998 TiO ₃ : Pr _0.002 phosphorescent material. In addition, phosphorescent materials co-substituted with Eu, Sm, and Dy also have excellent afterglow characteristics compared to Ca _0.998 TiO ₃ : Pr _0.002 of the comparative example, and the desired afterglow can be achieved by using these materials. Time and afterglow intensity can be adjusted.
In addition, as shown in FIG. 2, by changing the amount of substitution of La in Example 2, a red phosphorescent phosphor having better afterglow characteristics can be obtained.

Fig. 3 shows a sample in which 0.2 mol% of Pr and 2 mol% of La are co-substituted, calcined at 400 ° C, calcined directly at 1500 ° C without calcining at 1300 ° C, and again calcined twice at 1500 ° C. It is the afterglow characteristic of the sample performed repeatedly. As can be seen from the figure, even if the metal composition is the same, if the firing process is different, the afterglow characteristics are higher than those of Ca _0.998 TiO ₃ : Pr _0.002 and Ca _0.978 TiO ₃ : Pr _0.002 La _0.02 prepared in Example 1. It turns out that it is inferior.

  Fig. 4 shows a fired red phosphor stored in a raw material with a metal composition in which 0.2 mol% of Pr and 2 mol% of La are co-substituted, fired at 400 ° C, fired at 1300 ° C, and then not fired at 1500 ° C. Afterglow characteristics. When firing at 1500 ° C. is not performed, the afterglow characteristic is found to have no co-substitution effect.

Example 1
Ca _0.978 TiO ₃ : Pr _0.002 Ln _0.02 Ln 2-ethylhexanoic acid containing a metal element that forms a metal oxide containing a metal that is one of Dy, Eu, La, Sm, and Lu And the solvent and organic components were removed in the atmosphere at 400 ° C. for 6 hours. Next, firing was performed at 1300 ° C. for 2 hours in the atmosphere. After firing, the mixture was pulverized and mixed uniformly in a mortar. This powder was tableted and fired at 1500 ° C. for 2 hours in air. Similarly, after firing, the powder was pulverized again and mixed uniformly in a mortar, and this powder was tableted. The molded body was fired in the atmosphere at 1500 ° C. for 2 hours. After the obtained sintered body was excited with 365 nm light for 2 minutes and the afterglow luminance was measured, as shown in FIG. 1, when La was co-substituted, the afterglow intensity after 10 minutes was 5.2 mcd. / m ² is shown. Next, when Eu, Sm, and Dy were co-substituted, when not added, a phosphorescent material having higher afterglow intensity was obtained compared to Ca _0.998 TiO ₃ : Pr _0.002 .

(Example 2)
2-ethylhexanoic acid containing a metal element forming Ca _0.958 TiO ₃ : Pr _0.002 La _0.04 was mixed so as to have a predetermined metal composition, and the solvent and organic components were removed in the atmosphere at 400 ° C. for 6 hours. Next, firing was performed at 1300 ° C. for 2 hours in the atmosphere. After firing, the mixture was pulverized and mixed uniformly in a mortar. This powder was tableted and fired at 1500 ° C. for 2 hours in air. Similarly, after firing, the powder was pulverized again and mixed uniformly in a mortar, and this powder was tableted. The molded body was fired at 1500 ° C. for 2 hours in the air. After the obtained sintered body was excited with 365 nm light for 2 minutes, the afterglow intensity after 10 minutes showed 9.8 mcd / m ² as shown in FIG.

(Comparative Example 1)
The firing process for forming Ca _0.978 TiO ₃ : Pr _0.002 La _0.02 in Example 1 did not include a firing process at 1300 ° C., and after firing at 1500 ° C. or more, the afterglow characteristics were significantly reduced (see FIG. "reference). Furthermore, afterglow characteristics were improved by two or three firings (see “one firing” and “two firings” in FIG. 3), but the afterglow brightness was red produced by the process of Example 1. Low afterglow characteristics of phosphorescent phosphors.

(Comparative Example 2)
In the firing process of forming Ca _0.978 TiO ₃ : Pr _0.002 La _0.02 in Example 1, after firing at 1300 ° C. once and without the firing process at 1500 ° C., the afterglow characteristics are significantly reduced, and the effect of co-substitution Was not seen (see FIG. 4).

The red phosphorescent phosphor of the present invention has extremely high brightness, long persistence, excellent weather resistance, and is chemically stable, so the conventional Y ₂ O ₂ S: Eu red phosphorescent phosphor Compared to the body, it can be used for a wide range of purposes. For example, it can be applied to the surface of various articles, mixed with plastics, rubber, vinyl chloride, synthetic resin or glass, etc., as a molded body or fluorescent film, road signs, visual indications, ornaments, leisure goods, It can be used for watches, office automation equipment, educational equipment, safety signs and building materials. Further, when this phosphorescent fired phosphor is used as a fluorescent film of a fluorescent lamp, it can be used as a fluorescent lamp with excellent afterglow.

Claims (3)

Red afterglow by irradiating an oxide material with compositional formula Ca _a TiO ₃ : Pr _y La _x (where a = 1− ( x + y ), 0.02 ≦ x ≦ 0.06 , 0.001 ≦ y ≦ 0.005 ) with ultraviolet rays. a material exhibiting, after irradiation for 2 minutes with UV light having a wavelength of 365 nm, a red phosphorescent phosphor red afterglow intensity after 10 minutes of at ^{5.2mcd / m 2 ~9.8mcd / m 2} . Composition formula A _a B _b O _c [wherein A is at least one element selected from Ca, Sr, Ba, Mg, and B is at least one element selected from Ti, Zr, Sn, a, b, and c are the following numerical ranges, respectively. 0.8 ≦ a <1, b = 1, c = 3], and an ultraviolet ray is applied to an oxide material in which Pr and at least one element selected from La, Eu, Dy, and Sm are co-substituted. Is a method for producing a red phosphorescent phosphor exhibiting red afterglow,
Preparing a raw material containing a metal element of the oxide material;
A first firing step of firing the raw material at a temperature of less than 500 ° C .;
A second baking step of baking at a temperature of 500 ° C. or higher and lower than 1500 ° C. after the first baking step;
A third baking step in which baking at 1500 ° C. or higher is repeated at least twice after the second baking step;
A method for producing a red phosphorescent phosphor.   3. The method for producing a red phosphor according to claim 2, wherein the step of preparing the raw material includes a step of forming the raw material into nanoparticles, or a step of forming a solution using a solvent.

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