JPH09255950A - Preparation of light-storing luminescent pigment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for preparing a chemically stable light-storing luminescent metal oxide pigment free of any radioactive substances, which process is simplified as compared with conventional processes while enabling a high-purity light-storing luminescent pigment to be obtd. with control of the particle size of the pigment. SOLUTION: In preparation of a light-storing luminescent pigment comprising matrix crystals in the form of metal oxide crystals, an activator and a coactivator, and a light-storing luminescent pigment comprising matrix crystals in the form of metal oxide crystals, an activator, a coactivator and other additive element; a gel powder obtd. using an alkoxide deriv. of a constituent metal element and an org. or inorg. acid salt by a sol-gel method is fired in a reducing atmosphere to prepare a light-storing luminescent pigment.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a phosphorescent fluorescent pigment.

[0002]

2. Description of the Related Art A phosphorescent fluorescent pigment that is widely used in the market at present is a zinc sulfide-based phosphor to which a radioactive substance for enhancing the phosphorescent performance is added. These substances not only have the drawbacks of being chemically unstable and poor in light resistance, but also have drawbacks such as a strict management system for production because they contain radioactive substances, and the amount used is limited.

As a method for solving these problems, recently, Japanese Patent Laid-Open No. 7-11250, USP 5,376,303, etc. have been chemically doped without containing harmful substances by doping a plurality of rare earth elements into a metal oxide crystal. It was reported that a stable phosphorescent fluorescent pigment was obtained.

In general, these phosphorescent fluorescent pigments are produced by a solid-phase reaction in which an oxide, a halide or a carbonate of a constituent element of a mother crystal, an activator or a coactivator is mixed and fired.

In the solid-phase reaction method, the characteristics of the phosphorescent fluorescent pigment are greatly influenced by a slight amount of impurities, and therefore a purification step for sufficiently purifying the raw material is important.

After the refining, these refining raw materials are mixed in a blender or a ball mill, and then fired in a reducing atmosphere. For example, when the mother crystal is aluminate, it is approximately 130
A high temperature of 0 ° C or higher is required.

After firing, the sintered product is a crusher,
It is crushed into powder by a ball mill. Luminescent fluorescent pigments have different luminescent properties and subsequent coating properties depending on the particle size, so after crushing, classification is performed for the purpose of removing coarse particles and fine particles.

Further, in the solid-phase reaction method, a flux such as an alkali or alkaline earth metal halide or boric acid is often added during sintering for the purpose of promoting crystal growth. The objective phosphorescent fluorescent pigment is obtained through a washing, drying process after classification for the purpose of removing the flux and impurities.

[0009]

The above solid-phase reaction method requires a refining step before firing, and it is necessary to add a fluxing agent removed in the washing step after firing to the system. In order to obtain a crystalline form, high-temperature firing is required, complicated particle size obtained after firing and pulverization requires a classification step, and a washing step is required. Becomes

The present invention provides a production method capable of reducing the number of complicated production steps required for a solid-phase reaction, and further obtaining an intended phosphorescent fluorescent pigment having a high crystal purity and a uniform particle size. The purpose is to provide.

[0011]

The method for producing a phosphorescent fluorescent pigment of the present invention for solving the above-mentioned problems is a phosphorescent fluorescent pigment comprising a mother crystal which is a metal oxide crystal, an activator, and a co-activator. ,
And a phosphorescent pigment consisting of a mother crystal which is a metal oxide-based crystal and an activator, a co-activator, and other additive elements, wherein an alkoxide derivative of a metal element constituting the phosphorescent fluorescent pigment, an organic acid salt, The present invention is characterized in that a phosphorescent fluorescent pigment is produced by a sol-gel method using an inorganic acid salt, an oxide, or a chloride.

Further, the method for producing a phosphorescent fluorescent pigment of the present invention is characterized in that the mother crystal is a metal oxide type crystal composed of at least two or more constituent elements of the group consisting of Al, Sr, Ca and Ba. It is a thing.

Further, the method for producing a phosphorescent fluorescent pigment of the present invention is characterized in that the activator is Eu.

Further, in the method for producing a phosphorescent fluorescent pigment of the present invention, the co-activator is La, Ce, Pr, Nd, Sm, Gd, D.
It is characterized by comprising at least one or more constituent elements of the group consisting of y, Ho, Er, Tm, Y and Lu.

Further, the method for producing a phosphorescent fluorescent pigment of the present invention is characterized in that the additional element is at least one constituent element of the group consisting of B, Cu and P.

Further, the method for producing a phosphorescent fluorescent pigment of the present invention is characterized by producing a phosphorescent fluorescent pigment by firing a gel powder obtained by the sol-gel method in a reducing atmosphere.

Next, the method for producing the phosphorescent fluorescent pigment by the sol-gel method of the present invention will be described.

In the first step, the alkoxide derivative of a metal element constituting the mother crystal, the organic acid salt, or the inorganic acid salt is dissolved in a polar organic solvent to form a uniform solution. Generally used organic solvents are alcohols, but it is also possible to use glycol solvents, non-polar solvents such as benzene, amine solvents and the like.

In the second step, water is added to the reaction system to carry out hydrolysis and polycondensation to obtain a sol solution from a uniform solution. At this time, the reaction rate can be controlled by changing the pH of the reaction system and the concentration of water.

In the third step, a gel solution is obtained from the sol solution. The gel solution can be obtained naturally after a lapse of time after the formation of the sol solution, or by concentrating the reaction system and controlling the pH.

In the fourth step, the gel solution obtained is aged for a suitable time and then dried to obtain a gel powder.

In the subsequent fifth step, the gel powder is fired in a reducing atmosphere to obtain a mother crystal.

In the present invention, a mother crystal powder of a phosphorescent fluorescent pigment is obtained by the above-mentioned process, but an activator of the phosphorescent fluorescent pigment,
Co-activator, and alkoxide derivative of other additive element,
The organic acid salt, the inorganic acid salt, or the oxide can be added during any of the first to fifth steps.

Further, the firing of the gel powder needs to be carried out in a reducing atmosphere because it is necessary to reduce Eu of the activator which is a luminescent species from trivalent to divalent.

(Function) In the method for producing a phosphorescent fluorescent pigment by the sol-gel method of the present invention, a dehydrated raw material is used to obtain a homogeneous solution → sol solution → gel solution → gel powder by the sol-gel reaction and reduction. It is a method of obtaining a phosphorescent fluorescent pigment by firing in an atmosphere.

In comparison with the conventional solid-phase reaction method, in the manufacturing process, the purification of the raw material is simplified, the firing temperature is reduced, the crushing process is omitted, and the classification process is omitted. The phosphorescent fluorescent pigment does not contain impurities, and the desired crystal form of the mother crystal with high purity can be obtained under low temperature firing conditions. Further, since the particle size can be controlled by selecting the sol-gel reaction condition, it is possible to obtain a phosphorescent fluorescent pigment having a particle size suitable for the conditions of the subsequent coating process.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a part of the present invention will be described with reference to the drawings with reference to a comparative example of a conventional method for producing a phosphorescent fluorescent pigment by a solid phase method.

Example 1 Aluminum tri (2-butoxide) 0.02 mol (4.927 g) and strontium di (2-propoxide) 0.01 mol (2.05)
8 g) was added to 40 ml and 20 ml of 2-ethoxyethanol, and the mixture was stirred for 1 hour and then mixed. The mixed solution was refluxed at 130 ° C. for 17 hours, then returned to room temperature and 5.40.
Hydrolysis was carried out by adding 6 g of water. After stirring for 30 min, 0.00328 g of activator Eu ₂ O ₃ and co-activator Dy ₂
A solution prepared by dissolving 0.00325 g of O ₃ in 2 g of nitric acid was added, and after stirring, the resulting gel solution was aged at 60 ° C. for 24 hours. The gel solution was then dried at 150 ° C. to obtain a very brittle mass of gel powder. After the lumps were crushed into powder in a mortar, they were calcined in a reducing atmosphere at 1000 ° C. for 2 hours, and then further calcined in a reducing atmosphere at 1300 ° C. for 2 hours.

TG-DT of the gel powder obtained in Example 1
A measurement result is shown in FIG. It is considered that the endothermic peak around 120 ° C is due to the evaporation of the solvent and the exothermic peak around 320-350 ° C is due to the combustion of organic substances. Then, an exothermic peak that seems to be crystallization appears near 900 ° C.

Next, FIG. 2 shows changes in XRD spectrum of the gel powder obtained in Example 1 at various firing temperatures. 400
At 600 ° C and 600 ° C, peaks of strontium nitrate and strontium carbonate, which are considered to be produced by reaction of strontium, which is a constituent element of the mother crystal, with nitric acid or carbon dioxide in the air are confirmed, but at 800 ° C, it becomes amorphous. At 1000 ° C., it was confirmed that the SrAl ₂ O ₄ crystal existed as a single phase. This indicates that the exothermic peak near 900 ° C. in FIG. 1 is due to crystallization of SrAl ₂ O ₄ .

Further, when the powder obtained after the main calcination in Example 1 was observed with an electron microscope, the particle size was about 0.4 μm.
From this, it was found that the powder had a uniform diameter of about 0.8 μm and had a smooth surface and a nearly spherical shape.

(Comparative Example 1) α-aluminum oxide 0.0
1 mol (1.020 g) and strontium carbonate 0.01
Mol (1.476 g), as well as the activator Eu ₂ O ₃ (0.0
0328 g) and co-activator Dy ₂ O ₃ (0.00325 g)
Were mixed in a mortar and calcined in a reducing atmosphere at 1300 ° C. for 2 hours, and then the calcined product was pulverized and mixed in a ball mill,
After that, main firing was further performed in a reducing atmosphere at 1300 ° C. for 2 hours.

FIG. 3 shows changes in the XRD spectrum at each temperature in the above solid-phase reaction. Only at 400 ° C. and 800 ° C., only the peaks of aluminum oxide and strontium carbonate as raw materials were confirmed. 1000 unlike the first embodiment
No SrAl ₂ O ₄ crystal was confirmed at 0 ° C., but it was confirmed that even at 1300 ° C., the SrAl ₂ O ₄ crystal was present as the main phase, but the SrAl ₄ O ₇ crystal was also present as the second phase.

Further, when the powder obtained after the main calcination by the solid-phase reaction was observed with an electron microscope, a large difference was observed in the respective particle diameters (about 0.1 μm to 2 μm) unlike Example 1.
m) The shape was found to be an angular powder.

Example 2 Up to the hydrolysis step, the same procedure as in Example 1 was carried out. After adding water, the mixture was stirred at room temperature for 30 min, and the obtained gel solution was aged at 60 ° C. for 24 hours. The gel solution was then dried at 150 ° C. to obtain a very brittle mass of gel powder. The activating agent Eu ₂ O ₃ 0.0032 was added to this mass.
8g and 0.00325g of co-activator Dy ₂ O ₃ were added, mixed in a mortar and disintegrated into powder, and calcined at 1000 ° C for 2 hours in a reducing atmosphere, and then in a reducing atmosphere for 130
Main firing was performed at 0 ° C. for 2 hours.

In the XRD spectrum of the obtained powder, it was confirmed that SrAl ₂ O ₄ crystals existed as a single phase as in Example 1.

Further observation of the powder obtained by an electron microscope revealed that the powder had a particle size of about 0.4 μm to 0.8 μm and had a smooth surface and a nearly spherical shape as in Example 1. I understood.

(Example 3) The same procedure as in Example 2 was carried out up to the gel powder step. The obtained lump of gel powder was pulverized in a mortar and calcinated at 1000 ° C. for 2 hours in a reducing atmosphere. After calcination, 0.00328 g of the activator Eu ₂ O _{3 and} 0.00325 g of the co-activator Dy ₂ O ₃ were added and mixed in a mortar to give a powder. Calcination is performed, and then in a reducing atmosphere at 1300 ° C. for 2
Main firing was performed for an hour.

Excitation of the powder obtained after the main calcination in Example 3,
Also, the fluorescence spectrum is shown in FIG. As a result, 22
510 nm with a wide excitation band from 0 nm to 420 nm
It can be seen that there is an emission peak with λmax in the vicinity.

FIG. 5 shows the emission spectra of the powder obtained after the main calcination in Example 3 and Comparative Example 1 when excited at 370 nm, and FIG. 6 shows the emission spectra after the main calcination in Example 3 and Comparative Example 1. The change in afterglow intensity when the obtained powder is excited at 370 nm is shown. As a result, both of the powders show the characteristics of the phosphorescent fluorescent pigment, but the powder obtained by the sol-gel method of Example 3 has a higher emission intensity than the powder obtained by the solid-phase reaction of Comparative Example 1. It is clear that both the afterglow characteristics are excellent.

Example 4 Up to the gel powder process, the same procedure as in Example 2 was performed. The obtained lump of gel powder was pulverized in a mortar and calcinated at 1000 ° C. for 2 hours in a reducing atmosphere. After calcination, 0.0164 g of the activator Eu ₂ O _{3 and} 0.00325 g of the co-activator Dy ₂ O ₃ were added and mixed in a mortar to give a powder. Firing was performed, and then main firing was further performed at 1300 ° C. for 2 hours in a reducing atmosphere.

FIG. 7 shows changes in afterglow intensity when the powder obtained after the main calcination in Example 4 and Example 3 was excited at 370 nm. It is clear that both powders show the characteristics of the phosphorescent fluorescent pigment and the afterglow characteristics change depending on the concentration of the activator and co-activator. It was also found that the phosphorescent fluorescent pigment obtained in Example 4 was higher in initial brightness than the phosphorescent fluorescent pigment obtained in Example 3.

(Example 5) 0.02 mol (4.927 g) of aluminum tri (2-butoxide) was added to 40 ml of butanol, and the solution was stirred for 2 hours, and 0.01 mol (2 mol of strontium acetate.1 / 2H ₂ O) was added to the solution. 0.147 g) was added to 7.2 g of water to obtain a uniform solution. Hydrolysis was performed by adding 20 g of 28% aqueous ammonia solution. After stirring for 30 minutes, Eu ₂ O ₃ 0.0032
A solution of 8 g and 0.00325 g of Dy ₂ O ₃ dissolved in 2 g of nitric acid was added, and the gel solution obtained after stirring was heated at 60 ° C. for 24 hours.
Aged for hours. The gel solution was then dried at 150 ° C. to obtain a very brittle mass of gel powder. After crushing the mass into powder in a mortar, calcination is performed at 1000 ° C for 2 hours, and then 130
Main firing was performed at 0 ° C.

The shape, particle size and afterglow characteristics of the obtained powder were the same as in Example 1.

Example 6 Aluminum tri (2-butoxide) 0.04 mol (9.854 g) and strontium di (2-propoxide) 0.01 mol (2.05)
8 g) was added to 80 ml and 20 ml of 2-ethoxyethanol, respectively, and the mixture was stirred for 5 hours and then mixed. The mixed solution was refluxed at 130 ° C. for 17 hours, then returned to room temperature and 9.01.
Hydrolysis was carried out by adding g of water. The gel solution was aged at 60 ° C. for 24 hours. The gel solution was then dried at 150 ° C. to obtain a very brittle mass of gel powder. The lump of the obtained gel powder is crushed into powder in a mortar and 1000
Calcination was performed at 2 ° C. for 2 hours. After calcination, activator Eu ₂ O ₃
0.0164 g and 0.0065 g of co-activator Dy ₂ O ₃ were added and mixed in a mortar to give a powder, and then 10 in a reducing atmosphere.
Pre-baking was performed at 00 ° C. for 2 hours, and then main baking was further performed at 1300 ° C. for 2 hours in a reducing atmosphere.

When the XRD spectrum change at each firing temperature of the gel powder obtained in Example 6 was examined, it became amorphous at 900 ° C. and SrAl ₂ O ₄ and SrAl ₄ O ₇ crystals coexist at 1000 ° C. The thing was recognized. Further, at a high temperature of 1100 ° C. or higher, it was confirmed that the SrAl ₂ O ₄ crystal peak disappeared and the SrAl ₄ O ₇ crystal existed as a single phase.

The emission spectra of the powders obtained after the main calcination in Example 4 and Example 6 when excited at 370 nm were compared, and the powder of Example 4 had a maximum emission at 508 nm and the powder of Example 6 had a maximum emission at 498 nm. A peak was shown, and a difference in emission spectrum was observed depending on the crystal type of the mother crystal.

FIG. 8 shows the afterglow characteristics of the powders obtained after the main calcination of Examples 4 and 6 after being irradiated with a 1600 Lux fluorescent lamp for 20 minutes. From FIG. 8, the afterglow characteristics greatly differ depending on the crystal type of the mother crystal, and the SrAl ₂ obtained in Example 4 was obtained.
The phosphorescent fluorescent pigment composed of O ₄ mother crystal has high initial brightness,
On the other hand, it can be seen that the phosphorescent fluorescent pigment composed of the SrAl ₄ O ₇ mother crystal obtained in Example 6 has excellent afterglow characteristics.

As described above, according to the present invention, it is possible to obtain the phosphorescent fluorescent pigments having different characteristics with high purity, and by individually manufacturing and mixing these, the phosphorescent fluorescent pigments can be adjusted according to the required characteristics. It will be possible.

(Comparative Example 2) α-aluminum oxide 0.0
2 mol (2.040 g) and strontium carbonate 0.01
Mol (1.476 g), as well as the activator Eu ₂ O ₃ (0.0
164 g) and the co-activator Dy ₂ O ₃ (0.0065 g) were mixed in a mortar and calcined in a reducing atmosphere at 1300 ° C. for 2 hours, and then the calcined product was crushed and mixed in a ball mill, and then further mixed. Main firing was performed at 1300 ° C. for 2 hours in a reducing atmosphere.

When the change in XRD spectrum at each firing temperature of the above solid-phase reaction was examined, unlike Example 6, it was 900 ° C.
Also in this case, peaks of aluminum oxide, strontium carbonate, and Sr ₃ Al ₂ O ₆ as raw materials were confirmed. Also, in Example 6, SrAl ₄ O ₇ was obtained as a single phase.
Target SrAl at 0 ℃ and 1300 ℃
_{The 4} O ₇ crystal did not exist as the main phase, and it was recognized that many other crystals such as aluminum oxide, Sr ₃ Al ₂ O ₆ and SrAl ₂ O ₄ were mixed.

When the emission spectra of the powders obtained after the main calcination of Comparative Example 1 and Comparative Example 2 were excited at 370 nm, the emission spectra of both powders were different because the mother crystal was not a single crystal phase. I couldn't do it.

Although the examples and comparative examples have been described above, the method for producing the phosphorescent fluorescent pigment according to the present invention is not limited to the constituent elements of the mother crystal of the phosphorescent fluorescent pigment, the crystal type or the activator, and the co-activator. , And the kind and concentration of the additive are not limited at all.

[0054]

EFFECTS OF THE INVENTION The method for producing a phosphorescent fluorescent pigment of the present invention is simpler than the conventional method for producing a phosphorescent fluorescent pigment by a solid-phase reaction. The steps can be omitted and the classification step can be omitted.

Further, the phosphorescent fluorescent pigment obtained by the sol-gel method of the present invention does not contain impurities, and the desired crystal form of the mother crystal with high purity can be obtained under low temperature firing conditions.

By the sol-gel method of the present invention, it is possible to obtain high-purity phosphorescent fluorescent pigments having different properties, and by individually manufacturing and mixing these, it is possible to adjust the phosphorescent fluorescent pigment according to the required properties. It is possible.

Further, in the method for producing the phosphorescent fluorescent pigment of the present invention, the particle size can be controlled by selecting the sol-gel reaction condition. Therefore, the phosphorescent property of the particle size suitable for the subsequent coating process conditions and the like. It is possible to obtain a fluorescent pigment.

[Brief description of drawings]

FIG. 1 is the TG-of the gel powder obtained in Example 1 of the present invention.
It is a DTA measurement result.

FIG. 2 is an XRD spectrum change at each temperature of the gel powder obtained in Example 1 of the present invention.

FIG. 3 is an XRD spectrum change at each temperature when the conventional solid-phase reaction shown in Comparative Example 1 is used.

FIG. 4 is an excitation and emission spectrum of the powder obtained after the main calcination in Example 3 of the present invention.

FIG. 5 is an emission spectrum of the powder obtained after the main calcination in Example 3 of the present invention and Comparative Example 1 when excited at 370 nm.

FIG. 6 is a change in afterglow intensity when the powder obtained after main firing in Example 3 of the present invention and Comparative Example 1 is excited at 370 nm.

FIG. 7 shows changes in afterglow intensity when the powder obtained after the main calcination in Example 3 and Example 4 of the present invention was excited at 370 nm.

FIG. 8 is the afterglow characteristics of the powder obtained after the main calcination in Example 4 and Example 6 of the present invention after irradiation with a 1600 Lux fluorescent lamp for 20 minutes.

Claims (6)

[Claims] 1. A mother crystal which is a metal oxide crystal, a phosphorescent fluorescent pigment comprising an activator and a co-activator, and a mother crystal which is a metal oxide crystal, an activator and a co-activator. In a luminous fluorescent pigment comprising an agent, and other additive elements, a sol using an alkoxide derivative of a constituent metal element of the luminous fluorescent pigment, an organic acid salt, an inorganic acid salt, an oxide, or a chloride.
A method for producing a phosphorescent fluorescent pigment for producing a phosphorescent fluorescent pigment by a gel method. 2. The phosphorescent fluorescent pigment according to claim 1, wherein the mother crystal is a metal oxide crystal composed of at least two or more constituent elements of the group consisting of Al, Sr, Ca, and Ba. Production method. 3. The method for producing a phosphorescent fluorescent pigment according to claim 1, wherein the activator is Eu. 4. The co-activator is La, Ce, Pr, Nd, S.
The method for producing a phosphorescent fluorescent pigment according to claim 1, which comprises at least one or more constituent elements of the group consisting of m, Gd, Dy, Ho, Er, Tm, Y, and Lu. 5. The method for producing a phosphorescent fluorescent pigment according to claim 1, wherein the other additive element is at least one constituent element of the group consisting of B, Cu and P. 6. The method for producing a phosphorescent fluorescent pigment according to claim 1, wherein the phosphorescent pigment is manufactured by firing the gel powder obtained by the sol-gel method in a reducing atmosphere.