JP2979984B2 - Afterglow phosphor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an afterglow phosphor, and more particularly, to a europium-activated aluminate afterglow phosphor that can be used as a phosphorescent phosphor.

[0002]

2. Description of the Related Art Some fluorescent materials have afterglow in a dark place for a relatively long time when illuminated with sunlight or artificial lighting, and this phenomenon can be repeated many times. Called phosphor. In recent years, as social life has become more sophisticated and complex, interest in disaster prevention has further increased, and in particular, the use of phosphorescent phosphors that glow in dark places in the field of disaster prevention has been expanding. Recently, the phosphorescent phosphor has been mixed into plastics and processed into plates, sheets, and the like, so that the applications thereof have been expanding in various fields.

[0003] Conventionally, ZnS: Cu has been used as a phosphorescent phosphor.
Phosphors have been used but have not always been satisfactory. This is because this phosphor has the following essential disadvantages. One is that the phosphorescence brightness (the brightness of the afterglow) is not so high that it can be confirmed for several tens of hours. The other problem is that there is a problem that photodecomposition is caused by ultraviolet rays, colloidal zinc metal is deposited on the phosphor crystal surface, the appearance is changed to black, and the phosphorescent luminance is significantly reduced.
Such deterioration is particularly likely to occur under high-temperature and high-humidity conditions. Usually, to improve this defect, the surface of the ZnS: Cu phosphor is subjected to a light-resistant treatment, but it is difficult to completely prevent it. Therefore, the ZnS: Cu phosphor must be avoided from being used in places exposed to direct sunlight, such as outdoors.

On the other hand, SrAl ₂ activated by Eu or the like is used.
Phosphors based on O ₄ have been reported and attracted attention at the Phosphorescent Society of Japan.
Day). Although the composition is not completely elucidated, the base of the phosphor is a phosphor for a fluorescent lamp disclosed in U.S. Pat. No. 2,392,814, U.S. Pat. No. 3,294,699, and U.S. Pat. No. 4,216,408. By doing so, the above-mentioned disadvantages inherent in the ZnS: Cu phosphor are covered.

[0005] Divalent Eu shows a broad spectrum emission due to indirect transition, and is affected by the preparation conditions and the structure of the host crystal.
Depending on whether it is borate or aluminum gallate,
It is generally known that light is emitted in a wide range from the ultraviolet region to yellow.

The present inventor has conducted research for improving the characteristics of a phosphor using a strontium aluminate phosphor matrix, and has newly developed a phosphor containing Eu as an activator and Dy and Nb as coactivators. Developed and applied for a patent. (Japanese Patent Application Hei 6-440
No. 30) This was able to greatly improve the phosphorescence luminance as compared with the zinc sulfide phosphor. Further, as a result of repeated studies on the co-activator, phosphorescent light was introduced by introducing Dy as the first co-activator and several other rare earth elements as the second co-activator into the phosphor. We applied for a patent because we discovered that the brightness was improved and the phosphorescence characteristics were diversified. (Japanese Patent Application No. 6-10
No. 3729) In addition, when the phosphor matrix was tested, it was found that by adding boric acid to the Sr aluminate phosphor, the reactivity in the firing step was improved, and as a result, the phosphorescent luminance could be further improved, and a patent application was filed. did.
(Japanese Patent Application No. 6-147912) Also, it has been found that by simultaneously containing boric acid and phosphoric acid in a divalent aluminate phosphor, an afterglow phosphor excellent in heat resistance and water resistance can be obtained. Patent filed. (Japanese Patent Application No. 6-23460)
6)

[0007]

These aluminate phosphors show a bright long afterglow in the green or blue region,
It is sufficiently practicable for applications requiring only brightness for the afterglow of the phosphorescent phosphor. However, for example, when the phosphorescent material is used for applications such as decoration, afterglow of various colors is required. Also, new applications can be developed with the advent of such afterglow phosphors. In particular, there is great expectation for the appearance of an afterglow phosphor having afterglow in a white region.

The present invention has been made in view of such circumstances, and an object of the present invention is to develop an afterglow phosphor having an afterglow color not found in conventional aluminate-based afterglow phosphors. It is in.

[0009]

In order to solve the above-mentioned problems, the present inventor has repeated extensive tests on the composition of a divalent aluminate-based afterglow phosphor having excellent afterglow performance. Succeeded in changing the color tone by combining activators and coactivators.

That is, the afterglow phosphor of the present invention is an aluminate phosphor activated with divalent europium, the chemical composition of which is represented by the general formula (Ca1-pqr, EupNdqMnr) O. n
(Al1-mBm) 2O3.kP2O6 where 0.0001≤p≤0.5 0.00005≤q≤0.5 0.01 ≤r≤0.7 0.0001≤p + q + r≤0.75 0.0001 ≦ m ≦ 0.5 0.5 ≦ n ≦ 3.0 0 ≦ k ≦ 0.2 1 ≦ r / p ≦ 20

The afterglow phosphor of the present invention can be used as a raw material, for example, a metal oxide such as CaO, Al ₂ O ₃ , Eu ₂ O ₃ , Nd ₂ O ₃ , Mn ₃ O ₄ or a material such as CaCO ₃ . A compound that easily becomes an oxide by firing at a high temperature is selected. Such compounds include nitrates, oxalates and hydroxides in addition to carbonates. Raw material purity is 99.9
% Or more is required, and preferably 99.99% or more.

An activator to be introduced into the afterglow phosphor of the present invention,
The co-activator greatly affects the fluorescent color and phosphorescence luminance, and the concentration range is important for practical use. Therefore, the activator and the coactivator are respectively adjusted to the following ranges.

The concentration p of Eu of the activator to be introduced into the afterglow phosphor of the present invention is 0.0001 mol or more and 0.1 mol or more.
Adjust to 5 mol or less. This is because if it is less than this range, the light absorption is deteriorated, and as a result, the phosphorescence luminance is lowered. Conversely, if it is more than this range, concentration quenching occurs and the phosphorescence luminance is reduced. Therefore, a more preferable range of p is a range of 0.001 or more and 0.06 or less.

Regarding the Nd concentration q of the first co-activator,
It is adjusted to a range of 0.00005 or more and 0.5 or less. The reason for this is that if it is less than this range, the effect on afterglow will be small, and its practicality as a phosphorescent phosphor will be poor. Conversely, if it exceeds this range, concentration quenching will occur and the phosphorescent brightness will be reduced. Therefore, a more preferable range of q is 0.0005 or more and 0.03 or less, and in this range, the phosphorescent luminance is further increased.

Regarding the Mn concentration r of the second co-activator,
It is adjusted in the range of 0.00005 or more and 0.7 or less. The reason is that if the amount is less than this range, the influence on the color tone change becomes small, and if the amount is more than this range, density quenching occurs and the phosphorescent luminance decreases. Therefore, a more preferable range of r is a range of 0.01 or more and 0.30 or less. The value of r / p is important for the color tone. That is, when the Eu content of the activator is relatively large, the value of r needs to be increased accordingly, and the value of r / p is preferably adjusted to 1 or more and 20 or less.

In the afterglow phosphor of the present invention, a flux containing boron is effective. For example, when boric acid is used, boron is contained in the phosphor composition simultaneously with the effect as a flux, and aluminum having an aluminate structure is used. Is substituted with boron to improve the crystallinity of the aluminate and stabilize the emission center and the capture center, which is presumed to be effective in improving the afterglow time and phosphorescence luminance. Also, by introducing boron as a flux, particle growth is promoted, which can significantly improve phosphorescence luminance. Boric acid or a borate of an alkaline earth element can be used as the boron compound. In particular, boric acid is preferable, and the amount of boron substituting aluminum is 0.0001 or more,
The following range is preferred, and 0.005 is more preferred.
In the range of 0.25 or less, 0.05 or less is most preferable.
It is around 5.

Heat resistance is obtained by adding a phosphoric acid compound to a boron compound as a flux or a raw material for a composition and firing the mixture.
Water resistance is improved. As the phosphoric acid compound, phosphoric acid, phosphoric anhydride, ammonium phosphate, alkaline earth element phosphate, and the like can be preferably used. The concentration k of the phosphate compound is preferably in the range of 0.001 or more and 0.2 or less.
The range of 1 or more and 0.1 or less is more preferable, and 0.03
Above, the range of 0.05 or less is most preferable.

The raw material obtained by mixing these fluxes is fired at a temperature of 1200 ° C. or more and 1600 ° C. or less in a reducing atmosphere, and the fired product is pulverized and sieved to obtain the afterglow phosphor of the present invention. In addition, the mixing ratio of the raw materials can be determined by mixing theoretical amounts for obtaining a desired composition.

[0019]

The obtained afterglow phosphor emits light by excitation in a wide range from the visible region to the ultraviolet region, and also emits light by being excited by a black light or a germicidal lamp. Therefore, it may be applicable to fluorescent mercury lamps and low-pressure mercury vapor discharge lamps. here,
Hereinafter, a test according to the use of the phosphorescent phosphor is performed according to JIS K5120.

FIG. 1 shows the emission spectra of the afterglow phosphor of Example 5 immediately after the excitation was stopped and after 20 minutes.
In the figure, the curve (a) is a curve immediately after the stop of the excitation, and the curve (b) is a relative spectral energy distribution curve of the afterglow 20 minutes after the stop of the excitation. This phosphor emits light having peaks at 440 nm and 550 nm, and the respective peaks are Eu ²⁺ , M 2
Due to emission of n ²⁺ . The blue-violet emission of Eu ²⁺ at 440 nm is a light emission in which Eu ²⁺ is directly excited by the excitation light source D65, and the emission at 550 nm resonates the energy excited by Eu ²⁺ to Mn ²⁺ . It is because of that. In addition, Eu ²⁺
Afterglow is given to the light emission of. Curve immediately after excitation is stopped (a)
In this case, the emission at 550 nm is strong, but after 20 minutes, the emission at 550 nm becomes weak as shown by the curve (b). There is almost no afterglow of Mn ²⁺ emission, and the presence of Nd relates only to Eu ²⁺ emission.

The afterglow color tone depends on the activation amount p of Eu and M
Depending on the ratio of the activation amount r of n, the color tone greatly changes when the value of r / p is in the range of 1 to 20. Each emission chromaticity is plotted on the CIE chromaticity coordinates immediately after the excitation is stopped in FIG. 2 and 20 minutes after the excitation is stopped in FIG. In the figures, ○ indicates the examples of the present invention, numerical values indicate the numbers of the examples, and ● indicates the chromaticity points of the afterglow phosphors emitting blue and green light of the comparative examples.

The afterglow color shown in FIG. 3 is stable as described above, and covers a color tone in the range from blue to yellow-green, and includes a white area just in between. As described above, the afterglow phosphor of the present invention can produce a color tone that cannot be realized by the conventional aluminate-based afterglow phosphor. In particular, the afterglow in the white region can be used, and there is great value in decorative applications.

Here, the measurement of afterglow is described in JIS Z 91.
00 (method of measuring phosphorescent luminance of phosphorescent safety signboard) was referred to. That is, for phosphorus light intensity, after storage in a state where the test piece was obtained by the method described above was cut off external light more than 3 hours in the dark at illuminance of 200 lux light of conventional light source D ₆₅ to the test piece 4 The phosphorescent luminance 20 minutes after the irradiation is stopped is measured as a relative value with the phosphorescent luminance of the reference phosphor as 100%. Regarding the measurement of the emission spectrum and chromaticity of the afterglow, the obtained afterglow is measured for the spectrum distribution by a spectrophotometer, and the chromaticity of the CIE color system is calculated.

The measurement sample was prepared as follows. Add 0.5 g of acrylic resin varnish to 1 g of the phosphor sample, knead the sample carefully, taking care not to grind it, apply the sample to an aluminum plate so that the thickness becomes 100 mg / cm ² or more, and dry it. A test piece was used. This test piece is used for measurement of fluorescent color, phosphorescent luminance, and light resistance.

[0025]

【Example】

Example 1 CaCO ₃ 95.09 g 0.95 mol Eu ₂ O ₃ 0.88 g 0.0025 mol Nd ₂ O ₃ 2.52 g 0.0075 mol MnCO ₃ 3.45 g 0.03 mol Al ₂ O ₃ 101.96 g 1. 00mol H ₃ BO ₃ 2.47g 0.04mol The above-mentioned substance was put into a ceramic pot as a phosphor raw material, alumina balls were put as a mixing medium, the lid was closed, and the mixture was mixed with a roller for 2 hours. Raw material flour). Next, the raw raw powder is placed in an alumina crucible and fired at 1400 ° C. for 5 hours in a reducing atmosphere to obtain a fired phosphor. Next, the calcined product is pulverized and passed through a 200-mesh sieve to _obtain the (Ca _0.950 Eu _0.005 Nd _0.015 Mn _0.03 ) O of the present invention.
-Obtain 1.02 (Al _{0.98 0} B _0.020 ) ₂ O ₃ phosphor.

Example 2 CaCO ₃ 97.09 g 0.97 mol Eu ₂ O ₃ 0.88 g 0.0025 mol Nd ₂ O ₃ 2.52 g 0.0075 mol MnCO ₃ 1.15 g 0.01 mol Al ₂ O ₃ 96 g 1.00 mol H ₃ BO ₃ 2.47 g 0.04 mol As the phosphor raw material, in the same manner as in Example 1 except that the above substances were selected, the (Ca _0.970 Eu _0.005 Nd _0.015 Mn
_0.01 ) O · 1.02 (Al _0.980 B _0.020 ) ₂ O ₃ phosphor is obtained.

Example 3 CaCO ₃ 93.08 g 0.93 mol Eu ₂ O ₃ 0.88 g 0.0025 mol Nd ₂ O ₃ 2.52 g 0.0075 mol MnCO ₃ 5.75 g 0.05 mol Al ₂ O ₃ 101. 96 g 1.00 mol H ₃ BO ₃ 2.47 g 0.04 mol The same procedure as in Example 1 was carried out except that the above-mentioned substance was selected as the phosphor raw material, to thereby obtain the (Ca _0.930 Eu _0.005 Nd _0.015 Mn
_0.05 ) _O.1.02 (Al _0.980 B _0.020 ) ₂ O ₃ phosphor is obtained.

Example 4 97.08 g CaCO ₃ 0.90 mol Eu ₂ O ₃ 0.88 g 0.0025 mol Nd ₂ O ₃ 2.52 g 0.0075 mol MnCO ₃ 9.20 g 0.08 mol Al ₂ O ₃ 101. 96 g 1.00 mol H ₃ BO ₃ 2.47 g 0.04 mol In the same manner as in Example 1 except that the above-mentioned substance was selected as a phosphor raw material, (Ca _0.900 Eu _0.005 Nd _0.015 Mn
_{0.08) O · 1.02 (Al 0.980} B 0.020) obtaining ₂ O ₃ phosphor.

Example 5 CaCO ₃ 88.08 g 0.88 mol Eu ₂ O ₃ 0.88 g 0.0025 mol Nd ₂ O ₃ 2.52 g 0.0075 mol MnCO ₃ 11.49 g 0.10 mol Al ₂ O ₃ 101. 96 g 1.00 mol H ₃ BO ₃ 2.47 g 0.04 mol The same procedure as in Example 1 was carried out except that the above-mentioned substances were selected as the phosphor raw material, to thereby obtain the (Ca _0.880 Eu _0.005 Nd _0.015 Mn
_0.10 ) O · 1.02 (Al _0.980 B _0.020 ) ₂ O ₃ phosphor is obtained.

Example 6 CaCO ₃ 83.07 g 0.83 mol Eu ₂ O ₃ 0.88 g 0.0025 mol Nd ₂ O ₃ 2.52 g 0.0075 mol MnCO ₃ 17.24 g 0.15 mol Al ₂ O ₃ 96 g 1.00 mol H ₃ BO ₃ 2.47 g 0.04 mol The same procedure as in Example 1 was carried out except that the above-mentioned substances were selected as the phosphor raw materials, to _{thereby obtain} the (Ca _0.830 Eu _0.005 Nd _0.015 Mn
_0.15 ) O · 1.02 (Al _0.980 B _0.020 ) ₂ O ₃ phosphor is obtained.

Example 7 CaCO ₃ 78.70 g 0.78 mol Eu ₂ O ₃ 0.88 g 0.0025 mol Nd ₂ O ₃ 2.52 g 0.0075 mol MnCO ₃ 22.99 g 0.20 mol Al ₂ O ₃ 96 g 1.00 mol H ₃ BO ₃ 2.47 g 0.04 mol The same procedure as in Example 1 was carried out except that the above-mentioned substance was selected as the phosphor raw material, to _{thereby obtain} the (Ca _0.780 Eu _0.005 Nd _0.015 Mn
_0.20 ) O · 1.02 (Al _0.980 B _0.020 ) ₂ O ₃ phosphor is obtained.

Example 8 95.09 g of CaCO ₃ 0.95 mol Eu ₂ O ₃ 0.88 g 0.0025 mol Nd ₂ O ₃ 2.52 g 0.0075 mol MnCO ₃ 1.15 g 0.01 mol Al ₂ O ₃ 96 g 1.00 mol H ₃ BO ₃ 2.47 g 0.04 mol (NH ₄ ) ₂ HPO ₄ 2.64 g 0.02 mol The present invention is carried out in the same manner as in Example 1 except that the above-mentioned substance is selected as a phosphor raw material. (Ca _0.950 Eu _0.005 Nd _0.015 Mn
_{0.03) O · 1.02 (Al 0.980} B 0.020) obtaining ₂ O ₃ · 0.01P ₂ O ₆ phosphor.

[Comparative Example B] 98.09 g of CaCO ₃ 0.98 mol 0.88 g of Eu ₂ O ₃ 0.0025 mol Nd ₂ O ₃ 2.52 g 0.0075 mol Al ₂ O ₃ 101.96 g 1.00 mol H ₃ BO ₃ 2.47 g 0.04 mol In the same manner as in Example 1 except that the above substances were selected as the phosphor raw material, (Ca _0.985 Eu _0.005 Nd _0.015 ) O.
1.02 (Al _0.980 B _0.020 ) ₂ O ₃ phosphor is obtained.

[Comparative Example G] An aluminate phosphor having a green afterglow color was prepared in the same manner as described above, and (Sr _{0.9 52} Eu
_0.03 Dy _0.015 Tm _0.003 ) O · 1.02 (Al _0.980 B _0.020 ) ₂ O ₃ phosphor is obtained.

Table 1 summarizes the emission chromaticity and relative emission luminance of these afterglow phosphors immediately after the excitation was stopped and 20 minutes after the excitation was stopped.

[0036]

[Table 1]

[0037]

Since the present invention is configured as described above, it has the following effects.

The afterglow color of the afterglow phosphor of the present invention is stable as described above, and covers a color tone ranging from blue to yellow-green, and includes a white region just in the middle. The afterglow phosphor of the present invention can produce a color tone that cannot be realized with the conventional aluminate-based afterglow phosphor as described above,
In particular, the afterglow in the white region can be used, and there is great value in decorative applications.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relative spectral energy distribution curve of afterglow immediately after the excitation of the afterglow phosphor of the present invention is stopped and 20 minutes after the excitation is stopped.

FIG. 2 is a diagram showing phosphorescence chromaticity immediately after the excitation of the afterglow phosphors of the present invention and a comparative example is stopped.

FIG. 3 shows excitation stop 2 of afterglow phosphors of the present invention and a comparative example.
The figure which shows the phosphorescence chromaticity after 0 minute.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C09K 11/00-11/89

Claims (1)

(57) [Claims] An aluminate phosphor activated with divalent europium has a chemical composition represented by the general formula (Ca1-pqr, EupNdqMnr) On.
(Al1-mBm) 2O3.kP2O6 where 0.0001≤p≤0.5 0.00005≤q≤0.5 0.01 ≤r≤0.7 0.0001≤p + q + r≤0.75 0.0001 ≦ m ≦ 0.5 0.5 ≦ n ≦ 3.0 0 ≦ k ≦ 0.2 1 ≦ r / p ≦ 20 An afterglow phosphor characterized by the following formula: