JPH08151573A - Fluorescent substance having afterglow property - Google Patents

Abstract

PURPOSE: To obtain a fluorescent substance with afterglow property having various luminous color tones other than blue and green, especially white luminous color tone. CONSTITUTION: This fluorescent substance having afterglow property is an aluminate fluorescent substance activated by divalent europium and is expressed by the chemical composition formula, (Ca1-p-q-r , Eup Ndq Mnr )O.n(Al1-m Bm )2 O3 -.kP2 O6 (0.0001<=p<=0.5, 0.00005<=q<=0.5, 0.00005<=r<=0.7, 0.0001<=p+q+r<=0.75, 0.0001<=m<=0.5, 0.5<=n<=3.0, 0<=k<=0.2 and 1<=r/p<=20).

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 phosphors have afterglow for a relatively long time in a dark place when they are irradiated 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 more complicated, interest in disaster prevention has increased, and in particular, the use of phosphorescent phosphors that glow in the dark is expanding in the field of disaster prevention. In addition, recently, the phosphorescent phosphor is mixed with plastic and processed into a plate, a sheet, and the like, so that its use is expanding in various fields.

Conventionally, ZnS: Cu has been used as a phosphorescent phosphor.
Phosphors have been used but have not always been fully satisfactory. This is because this phosphor has the following essential drawbacks. One is that the phosphorescence brightness (brightness of afterglow) is not high enough to be confirmed for several tens of hours. The other is that there is a problem that photolysis is caused by ultraviolet rays and colloidal zinc metal is deposited on the surface of the phosphor crystal to change its appearance to black and phosphorescence brightness is significantly reduced.
Such deterioration is particularly likely to occur under conditions of high temperature and high humidity, and the surface of the ZnS: Cu phosphor is usually light-proofed to improve this drawback, but it is difficult to completely prevent it. Therefore, it is necessary to avoid using the ZnS: Cu phosphor in a place exposed to direct sunlight, such as outdoors.

On the other hand, SrAl ₂ activated with Eu or the like
A phosphor based on O ₄ was reported and attracted attention at the Society of Phosphor Sciences (The 248th Symposium on Phosphor Society of Japan, November 1993)
Day). Although its composition has not been completely clarified, the base material of this phosphor is the phosphor for fluorescent lamps disclosed in US Pat. No. 2,392,814, US Pat. No. 3,294,699, and US Pat. No. 4,216,408. By doing so, it is said that the drawbacks inherent to the ZnS: Cu phosphor described above are covered.

Divalent Eu emits a broad spectrum of light by indirect transition and is influenced by the preparation conditions and the structure of the host crystal. For example, the host crystal is aluminate, gallate,
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 the yellow.

The present inventor has conducted research aiming at improving the characteristics of the phosphor using a strontium aluminate phosphor matrix, and newly developed a phosphor using Eu as an activator and Dy, Nb as a co-activator. Developed and filed a patent. (Japanese Patent Application No. 6-440
No. 30), which was able to greatly improve the phosphorescence luminance as compared with the zinc sulfide phosphor. Further, as a result of repeated research on the coactivator, by introducing Dy as the first coactivator and several other rare earth elements as the second coactivator into the phosphor, We discovered that the brightness was improved and the phosphorescence characteristics were diversified, and we applied for a patent. (Japanese Patent Application No. 6-10
Furthermore, when the phosphor base was tested, it was found that the incorporation of boric acid into the Sr aluminate phosphor improves the reactivity in the firing step, and as a result, the phosphorescence brightness can be further improved. did.
(Japanese Patent Application No. 6-147912) Further, it was found that by incorporating boric acid and phosphoric acid into a divalent aluminate phosphor at the same time, an afterglow phosphor having excellent heat resistance and water resistance can be obtained. I applied for a patent. (Japanese Patent Application No. 6-23460
6)

[0007]

These aluminate phosphors have a long bright afterglow in the green or blue region.
It is sufficiently practical for applications requiring only brightness for the afterglow of the phosphorescent phosphor. However, for example, when the phosphorescent phosphor is used for applications such as decoration, afterglow of various color tones is required. In addition, the emergence of such an afterglow phosphor allows the development of new applications. In particular, there are great expectations for the appearance of an afterglow phosphor having an afterglow in a white region.

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

[0009]

In order to solve the above-mentioned problems, the present inventor repeated enormous tests on the composition of a divalent aluminate-based afterglow phosphor having excellent afterglow performance. We succeeded in changing the color tone by combining the activator and co-activator.

That is, the afterglow phosphor of the present invention is an aluminate phosphor activated with divalent europium, and its chemical composition is represented by the general formula (Ca _1-pqr , Eu _p Nd _q Mn _r ). O ・ n (Al
_1-m B _m ) ₂ O ₃ · kP ₂ O ₆ where 0.0001 ≦ p ≦ 0.5 0.00005 ≦ q ≦ 0.5 0.00005 ≦ 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 is used as a raw material, for example, metal oxide such as CaO, Al ₂ O ₃ , Eu ₂ O ₃ , Nd ₂ O ₃ , Mn ₃ O ₄ or CaCO ₃ . A compound is selected that easily becomes an oxide when fired at a high temperature. Such compounds include nitrates, oxalates, hydroxides, etc. in addition to carbonates. Raw material purity is 99.9
% Or more is necessary, and preferably 99.99% or more.

An activator introduced into the afterglow phosphor of the present invention,
The co-activator has a great influence on the fluorescent color and the phosphorescence brightness, and its concentration range is important for practical use. Therefore, the activator and co-activator are adjusted within the ranges shown below.

The concentration p of Eu of the activator introduced into the afterglow phosphor of the present invention is 0.0001 mol or more,
Adjust to a range of 5 mol or less. This is because if it is less than this range, the light absorption becomes poor, and as a result, the phosphorescence brightness becomes low, and conversely, if it exceeds the range, density quenching occurs and the phosphorescence brightness decreases. Therefore, the more preferable range of p is 0.001 or more and 0.06 or less.

Regarding the Nd concentration q of the first coactivator,
Adjust within the range of 0.00005 to 0.5. This is because if it is less than this range, the effect on the afterglow becomes small, and the practicality as a phosphorescent phosphor becomes poor, and conversely, if it exceeds the range, concentration quenching occurs and phosphorescence brightness decreases. Therefore, the more preferable range of q is 0.0005 or more and 0.03 or less, and the phosphorescence luminance is further increased in this range.

Regarding the Mn concentration r of the second coactivator,
Adjust within the range of 0.00005 to 0.7. This is because if it is less than this range, the effect on the color tone change is small, and conversely, if it is more than this range, density quenching occurs and phosphorescence brightness is reduced. Therefore, a more preferable range of r is 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 amount of the activator is relatively large, the value of r needs to be increased accordingly, so that 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 at the same time as the flux, and aluminum having an aluminate structure is used. It can be presumed that by substituting boron with boron to improve the crystallinity of the aluminate and stabilize the luminescence center and the trap center, it is effective in improving the afterglow time and phosphorescence brightness. In addition, the introduction of boron as a flux promotes particle growth, which can significantly improve phosphorescence brightness. 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 m of boron substituting for aluminum is 0.0001 or more and 0.5
The following range is preferable, and 0.005 is more preferable.
Above, in the range of 0.25 or less, the most preferable is 0.0
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 composition, and baking the resulting mixture.
Water resistance is improved. As the phosphoric acid compound, phosphoric acid, anhydrous phosphoric acid, ammonium phosphate, phosphates of alkaline earth elements and the like can be preferably used. The phosphoric acid compound concentration k is preferably 0.001 or more and 0.2 or less, and 0.0
The range of 1 or more and 0.1 or less is more preferable, and 0.03
Above all, the range of 0.05 or less is most preferable.

The afterglow phosphor of the present invention is obtained by firing a raw material obtained by mixing these fluxes at a temperature of 1200 ° C. or higher and 1600 ° C. or lower in a reducing atmosphere, and pulverizing and sieving the fired product. The mixing ratio of the raw materials can be determined by mixing theoretical amounts for obtaining the desired composition.

[0019]

The resulting afterglow phosphor is excited to emit light in a wide range from visible to ultraviolet, and is also excited to emit light by black light and germicidal lamp. Therefore, it may be applicable to fluorescent mercury lamps and low-pressure mercury vapor discharge lamps. here,
Below, a test according to the application of the phosphorescent phosphor is performed according to JIS K 5120.

FIG. 1 shows emission spectra of the afterglow phosphor of Example 5 of the present invention immediately after the excitation was stopped and after 20 minutes.
In the figure, the curve (a) is the relative spectrum energy distribution curve of the afterglow 20 minutes after the excitation is stopped, and the curve (b) is the curve of the afterglow relative spectrum energy distribution. This phosphor emits light having peaks at 440 nm and 550 nm, and the respective peaks are Eu ²⁺ , M
Due to n ²⁺ emission. The blue-violet emission of Eu ²⁺ at 440 nm is the emission of Eu ²⁺ directly excited by the excitation light source D65, and the emission of 550 nm resonantly transfers the energy excited by Eu ²⁺ to Mn ²⁺ . This is due to the fact. Also, due to the Nd of the first coactivator, Eu ²⁺
Afterglow is given to the light emission of. Curve (a) immediately after the excitation is stopped
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 the emission of Mn ²⁺ , and the presence of Nd is related only to the emission of Eu ²⁺ .

Further, this afterglow color tone is the activation amount p and M of Eu.
Depending on the ratio of the activation amount r of n, the color tone changes greatly in the range of r / p value of 1 to 20. The emission chromaticity of each is plotted in the chromaticity coordinates of CIE immediately after the excitation is stopped in FIG. 2 and 20 minutes after the excitation is stopped in FIG. In the figure, ◯ indicates the example of the present invention, numerical values indicate the number of the example, and ● indicates the chromaticity points of the blue and green luminescent afterglow phosphors of the comparative example.

The afterglow color in FIG. 3 is stable as described above, covers the color tone in the range from blue to yellow-green, and also includes the white region just in the middle. 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, white afterglow can be used, which is of great value for decorative applications.

Regarding the measurement of afterglow, JIS Z 91
00 (a method for measuring the phosphorescence brightness of a luminous safety signboard) was referred to. That is, regarding the phosphorescence brightness, after the test piece obtained by the above-mentioned method was stored in a dark place for 3 hours or more in a state where external light was blocked, the test piece was exposed to light of a common light source D ₆₅ at an illuminance of 200 lux for 4 hours. Irradiation is carried out for a minute, and the phosphorescence brightness 20 minutes after the irradiation is stopped is measured as a relative value with the phosphorescence brightness of the reference phosphor being 100%. Regarding the measurement of the emission spectrum and chromaticity of the afterglow, the spectral distribution of the obtained afterglow is obtained 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 phosphor sample, knead it carefully so as not to grind the sample, coat the sample on an aluminum plate to a thickness of 100 mg / cm ² or more, and dry it. The test piece was used. This test piece is used to measure fluorescent color, phosphorescence brightness, and light resistance.

[0025]

【Example】

[Example _{1] CaCO 3 95.09g 0.95mol Eu 2} O 3 0.88g 0.0025mol Nd 2 0 3 2.52g 0.0075mol MnCO 3 3.45g 0.03mol Al 2 O 3 101.96g 1. 00 mol H ₃ BO ₃ 2.47 g 0.04 mol As a phosphor raw material, the above substances are put into a ceramic pot, alumina balls are put as a mixed medium, the lid is closed, and the mixture is mixed with a roller for 2 hours. Raw raw powder). Next, the raw raw material powder is placed in an alumina crucible and fired at 1400 ° C. for 5 hours in a reducing atmosphere to obtain a phosphor fired product. Next, the calcined product was crushed and passed through a 200-mesh sieve to _obtain (Ca _0.950 Eu _0.005 Nd _0.015 Mn _0.03 ) O of the present invention.
_{· 1.02 (Al 0.98 0 B 0.020} ) obtaining 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 0 ₃ 2.52 g 0.0075 mol MnCO ₃ 1.15 g 0.01 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 substance was selected as the phosphor raw material, (Ca _0.970 Eu _0.005 Nd _0.015 Mn of the present invention was used).
_0.01 ) O · 1.02 (Al _0.980 B _0.020 ) ₂ O ₃ phosphor is obtained.

Example 3 CaCO ₃ 93.08g 0.93mol Eu ₂ O ₃ 0.88g 0.0025mol Nd ₂ 0 ₃ 2.52g 0.0075mol MnCO ₃ 5.75g 0.05mol 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 _0.930 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 CaCO ₃ 97.08 g 0.90 mol Eu ₂ O ₃ 0.88 g 0.0025 mol Nd ₂ 0 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 substance was selected as the phosphor raw material, (Ca _0.900 Eu _0.005 Nd _0.015 Mn
_0.08 ) _O.1.02 (Al _0.980 B _0.020 ) ₂ O ₃ phosphor is obtained.

Example 5 CaCO ₃ 88.08 g 0.88 mol Eu ₂ O ₃ 0.88 g 0.0025 mol Nd ₂ 0 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 In the same manner as in Example 1 except that the above substance was selected as a phosphor raw material, (Ca _0.880 Eu _0.005 Nd _0.015 Mn of the present invention was used).
_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 0 ₃ 2.52 g 0.0075 mol MnCO ₃ 17.24 g 0.15 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 substance was selected as the phosphor raw material, (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 0 ₃ 2.52 g 0.0075 mol MnCO ₃ 22.99 g 0.20 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 substance was selected as the phosphor raw material, (Ca _0.780 Eu _0.005 Nd _0.015 Mn of the present invention was used).
_{A 0.20} ) _O.1.02 (Al _0.980 B _0.020 ) ₂ O ₃ phosphor is obtained.

Example 8 CaCO ₃ 95.09g 0.95mol Eu ₂ O ₃ 0.88g 0.0025mol Nd ₂ 0 ₃ 2.52g 0.0075mol MnCO ₃ 1.15g 0.01mol Al ₂ O ₃ 101. 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 In the same manner as in Example 1 except that the above substance was 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 ) ₂ O ₃ .0.01 P ₂ O ₆ phosphor is obtained.

Comparative Example B CaCO ₃ 98.09 g 0.98 mol Eu ₂ O ₃ 0.88 g 0.0025 mol Nd ₂ 0 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 (Ca _0.985 Eu _0.005 Nd _0.015 ) O · of the comparative example was prepared in the same manner as in Example 1 except that the above substances were selected as the phosphor raw material.
A 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 produced 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.

The emission chromaticity and relative emission luminance of these afterglow phosphors immediately after the stop of excitation and 20 minutes after the stop of excitation are summarized in Table 1.

[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, covers a color tone in the range from blue to yellow green, and includes a white region in the middle thereof. The afterglow phosphor of the present invention can thus provide a color tone that cannot be realized by the conventional aluminate-based afterglow phosphor,
In particular, white afterglow can be used, which is of great value for decorative applications.

[Brief description of drawings]

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

FIG. 2 is a graph showing phosphorescence chromaticities of the afterglow phosphors of the present invention and comparative examples immediately after the excitation is stopped.

FIG. 3 Excitation stop 2 of the afterglow phosphors of the present invention and comparative examples
The figure which shows the phosphorescence chromaticity after 0 minutes.

Claims (1)

[Claims] 1. Aluminate phosphor activated with divalent europium has a chemical composition represented by the general formula (Ca _1-pqr , Eu _p Nd _q Mn _r ) On (Al).
_1-m B _m ) ₂ O ₃ · kP ₂ O ₆ where 0.0001 ≦ p ≦ 0.5 0.00005 ≦ q ≦ 0.5 0.00005 ≦ 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 and an afterglow phosphor.