JP2003231877A - Oxygen-introduced rare earth-activated alkaline earth metal fluorohalide photostimulable phosphor, method for producing the same and radiation image conversion panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for stably producing an oxygen-introduced rare earth-activated alkaline earth metal fluorohalide photostimulable phosphor and to provide a radiation image conversion panel with high luminance using the phosphor. <P>SOLUTION: The method for producing the oxygen-introduced rare earth- activated alkaline earth metal fluorohalide photostimulable phosphor comprises the following at least three steps. Step 1 of removing a solvent from a solution at ≥3.3 mol/L barium concentration and thereby affording a photostimulable phosphor precursor, step 2 of adding and mixing alumina fine particles having 2-50 nm particle diameter in an amount of 0.15-0.30 mass% based on the photostimulable phosphor precursor therewith and step 3 of heating the resultant mixture of the precursor with the alumina fine particles to ≥600°C. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an oxygen-introduced rare earth activated alkaline earth metal fluorohalide stimulable phosphor, a method for producing the stimulable phosphor, and a radiation image using the stimulable phosphor. It is about the conversion panel.

[0002]

2. Description of the Related Art A radiation image recording / reproducing method using a stimulable phosphor described in JP-A-55-12145 is known as an effective diagnostic means in place of conventional radiography.

This method uses a radiation image conversion panel containing a stimulable phosphor (also called a stimulable phosphor sheet).
The stimulable phosphor absorbs the radiation transmitted through the subject or emitted from the subject, and is stimulated in a time series with electromagnetic waves such as visible light and ultraviolet rays (called excitation light). A fluorescent substance to excite the stored radiation energy as fluorescence (called stimulated emission light), which is read photoelectrically and converted into an electrical signal,
The radiographic image of the subject or the subject is reproduced as a visible image based on the obtained electric signal. After the reading, the conversion panel erases the remaining image, and the panel is ready for the next shooting.

As the use of a radiation image conversion method utilizing a stimulable phosphor progresses, it becomes necessary to further improve the image quality of the obtained radiation image, for example, the sharpness and the graininess. Came. Among the means for improving the image quality of a radiation image, it is effective to make the stimulable phosphor fine particles and the finely divided stimulable phosphor particles have the same particle size, that is, to narrow the particle size distribution. .

JP-A-9-291278 and 7-233.
The method for producing a stimulable phosphor from a liquid phase disclosed in, for example, No. 369 is a method for obtaining a fine-particle stimulable phosphor precursor by adjusting the concentration of a phosphor raw material solution. It is effective as a method for producing a stimulable phosphor powder having a uniform distribution.

The alkaline earth metal fluoroiodide stimulable phosphor produced in the liquid phase as described above is advantageous in terms of graininess. However, when a precursor crystal is obtained in the liquid phase, Have a problem like. That is, as disclosed in JP-A-9-291278, ammonium fluoride is dissolved in water,
A method of adding a barium iodide solution while stirring this solution is effective, but this method requires an excess of barium iodide with respect to the inorganic fluoride, and the yield is low. As described above, the liquid phase synthesis of barium fluoride iodide has a problem that the yield is low and the productivity is poor. Decreasing the barium iodide concentration in the mother liquor to increase the yield causes enlargement of the particles, which is not preferable in terms of image quality characteristics.

In order to solve the above-mentioned problems, the inventors of the present invention have conducted studies and found that the barium concentration in the reaction mother liquor is 3. As described in Japanese Patent Application No. 2000-143178.
We have developed a manufacturing method to obtain a stimulable phosphor precursor by removing the solvent from a solution of 3 mol / L or more, and made it possible to achieve both particle size distribution and yield.

The stimulable phosphor precursor obtained by this method obtains the stimulable luminescent property only by firing at high temperature, and the stimulable phosphor is produced from the precursor. At this time, there is a case where an increase in particle diameter due to firing, so-called sintering, may occur, which is a big problem for making fine particles. A technique is known in which a metal oxide particle, for example, a sintering inhibitor such as silica or alumina is added to a precursor before firing in order to prevent sintering. It has been clarified that the conventionally known addition method of the sintering inhibitor can prevent the increase of the particle size, but may cause the decrease of the brightness.

[0009]

An object of the present invention is to stably obtain an oxygen-introduced rare earth-activated alkaline earth metal fluorohalide stimulable phosphor, and a high-intensity radiation image using them. It is to provide a conversion panel.

[0010]

The above object has been achieved by the constitution of the present invention described below.

1. A method for producing an oxygen-introduced rare earth-activated alkaline earth metal fluorohalide stimulable phosphor represented by the general formula (1), which comprises at least the following three steps: Method for producing an earth metal fluorohalide stimulable phosphor.

Step 1: A step of forming a precursor of the stimulable phosphor by a liquid phase method, in which the solvent is removed from the solution having a barium concentration of 3.3 mol / L or more in the reaction mother liquor to stimulate the stimulable phosphor. Of obtaining a stimulable phosphor precursor, Step 2: After Step 1, with respect to the stimulable phosphor precursor,
Alumina fine particles with a particle size of 2 to 50 nm are added in an amount of 0.15 to 0.3
Step of adding and mixing 0 mass% Step 3: After Step 2, heating the mixture of the stimulable phosphor precursor and alumina fine particles to 600 ° C. or higher.

(2) Oxygen-introduced rare earth activated alkaline earth metal fluorohalide according to (1), characterized in that the mass after removal of the solvent in step 1 is 0.97 or less with respect to the mass before removal. A method for producing a stimulable phosphor.

(3) In order to remove the reaction solvent in step 1, a means for heating the reaction mother liquor and removing other solvent is also used in combination, and oxygen introduction according to (1) or (2). A method for producing a rare earth activated alkaline earth metal fluoride halide stimulable phosphor.

(4) An oxygen-introduced rare earth-activated alkaline earth metal fluorohalide stimulable phosphor obtained by the method according to any one of (1) to (3) above.

(5) A radiation image conversion panel comprising a phosphor layer containing the oxygen-introduced rare earth activated alkaline earth metal fluorohalide stimulable phosphor described in (4) above.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Representative embodiments of the method for producing a rare earth activated alkaline earth metal fluorohalide stimulable phosphor by the liquid phase method of the present invention will be described in detail below.

For the production of the photostimulable phosphor precursor by the liquid phase method, the precursor production method described in JP-A-10-140148 and the precursor production apparatus described in JP-A-10-14777 are preferably used. it can. Here, the stimulable phosphor precursor refers to a state in which the substance of the general formula (1) has not been subjected to a high temperature of 600 ° C. or higher, and the stimulable phosphor precursor has a stimulable luminescent property and an instantaneous luminescent property. Hardly shows.

The details of the method for producing the stimulable phosphor will be described below. <Step 1: A step of forming a precursor of a stimulable phosphor by a liquid phase method, wherein the barium concentration in the reaction mother liquor is 3.3 m.
Step of Obtaining Stimulable Phosphor Precursor by Removing Solvent from Solution of ol / L or More> First, a raw material compound other than a fluorine compound is dissolved in an aqueous medium. That is, B
aI ₂ and Ln halide, and optionally M ₂
Halide, and further a halide of M ₁ placed in an aqueous medium, thoroughly mixing, dissolving, to prepare an aqueous solution in which they are dissolved. However, the BaI ₂ concentration is 3.
The amount ratio of the BaI ₂ concentration and the aqueous solvent is adjusted so that the amount becomes 3 mol / L or more, preferably 3.5 mol / L or more. At this time, if the barium concentration is low, a precursor having a desired composition cannot be obtained, or even if it is obtained, the particles are enlarged.
Therefore, it is necessary to properly select the barium concentration, and as a result of studies by the present inventors, it was found that fine precursor particles can be formed at 3.3 mol / L or more. In particular, the upper limit is preferably 5.0 mol / L or less. At this time, if desired, a small amount of acid, ammonia, alcohol, water-soluble polymer, water-insoluble metal oxide fine particle powder or the like may be added. It is also a preferred embodiment to add an appropriate amount of a lower alcohol (methanol, ethanol, etc.) within a range in which the solubility of BaI ₂ is not significantly reduced. This aqueous solution (reaction mother liquor) is maintained at 50 ° C.

Next, an aqueous solution of inorganic fluoride (ammonium fluoride, alkali metal fluoride, etc.) is injected into the stirred and maintained aqueous solution at 50 ° C. using a pipe with a pump or the like. This injection is preferably carried out in the areas where the stirring is particularly vigorous. By injecting this inorganic fluoride aqueous solution into the reaction mother liquor, the rare earth activated alkaline earth metal fluorohalide phosphor precursor crystals corresponding to the above general formula (1) are precipitated.

Next, the solvent is removed from the reaction solution. The time of removing the solvent is not particularly limited. It may be any time from the start of the addition of the inorganic fluoride solution to the solid-liquid separation. Most preferred is a mode in which the removal is started immediately after the addition of the inorganic fluoride solution is completed.

The amount of the solvent removed is preferably 2% or more in terms of mass ratio before and after the removal. Below this, the crystal may not have the desired composition. Therefore, the removal amount is preferably 2% or more, more preferably 5% or more. Even if it is removed too much, the handling solution may be inconvenient, such as the viscosity of the reaction solution rising excessively. Therefore, the amount of solvent removed is preferably 50% or less in terms of mass ratio before and after removal.

The time required for removing the solvent not only greatly affects the productivity, but also the shape and particle size distribution of the particles are influenced by the method for removing the solvent, and therefore the method for removing must be appropriately selected. Generally, in removing the solvent, a method of heating the solution and evaporating the solvent is selected. This method is also useful in the present invention. By removing the solvent,
A precursor of the intended composition can be obtained.

Further, in order to improve productivity and to keep the particle shape appropriate, it is preferable to use other solvent removing methods in combination. The method of removing the solvent used in combination is not particularly limited. It is also possible to select a method using a separation membrane such as a reverse osmosis membrane. In the present invention, it is preferable to select the following removal method from the viewpoint of productivity.

1. Aeration of dry gas The reaction vessel is hermetically sealed, and at least two or more holes are provided to allow the gas to pass, and the dry gas is aerated from there. The type of gas can be arbitrarily selected. From the perspective of safety
Air and nitrogen are preferred. The solvent is entrained in the gas and removed depending on the saturated vapor amount of the gas to be aerated. In addition to the method of ventilating the voids of the reaction container, a method of ejecting gas as bubbles in the liquid phase and absorbing the solvent in the bubbles is also effective.

2. Decompression As is well known, decompression reduces the vapor pressure of a solvent. The solvent can be removed efficiently by lowering the vapor pressure. The degree of reduced pressure can be appropriately selected depending on the type of solvent. 86,450 Pa when the solvent is water
The following are preferred.

3. The solvent can be removed efficiently by increasing the liquid film evaporation area. As in the present invention, when a reaction vessel having a constant volume is heated and stirred to carry out the reaction, the heating method is to immerse the heating means in a liquid or to attach the heating means to the outside of the vessel. Is common. According to this method, the heat transfer area is limited to the portion where the liquid and the heating means are in contact with each other, and the heat transfer area is reduced as the solvent is removed, so that the time required for solvent removal is prolonged. In order to prevent this, it is effective to use a pump or a stirrer to spray on the wall surface of the reaction vessel to increase the heat transfer area.

In this way, the liquid is sprinkled on the wall surface of the reaction vessel,
The method of forming a liquid film is known as a "wetting wall."
As a method for forming a wet wall, other than the method using a pump,
Examples thereof include methods using a stirrer described in JP-A-6-335627 and JP-A-11-235522.

These methods may be used alone or in combination. A combination of a method of forming a liquid film and a method of reducing the pressure in the container, a combination of a method of forming a liquid film and a method of aerating a dry gas are effective. The former is particularly preferable, and the method described in JP-A-6-335627 is preferably used.

<Step 2: After Step 1, 0.15 to 0.30% by mass of alumina fine particles having a particle size of 2 to 50 nm are added to and mixed with the stimulable phosphor precursor>
The phosphor precursor crystal is separated from the solution by filtration, centrifugation, etc., thoroughly washed with methanol etc., and dried.

Alumina fine powder having a particle size of 2 to 50 nm was added to the phosphor precursor crystals obtained by drying in an amount of 0.15 to 0.30.
Mass% is added and mixed, and alumina fine powder is uniformly adhered to the crystal surface.

The fine alumina powder has an average particle diameter of 2 to 50 n.
needs to be m. Sintering inhibitors having an average particle size of 2 nm or less are industrially difficult to obtain, and the average particle size is 5
When it exceeds 0 nm, the surface of the phosphor particles cannot be effectively covered and it is difficult to make the phosphor particles uniformly exist in the phosphor layer, which is not preferable.

A known mixing method can be used to mix the alumina fine powder having a particle size of 2 to 50 nm with the phosphor particles having an average particle size of several μm to several tens of μm, for example, a turbula shaker. Using a mixing device such as a mixer (for example, manufactured by Shinmaru Enterprises Co., Ltd.), a mixing method of gradually adding phosphor particles to the total amount of alumina fine powder can be mentioned. Is preferable from the viewpoint of uniform coating.

<Step 3: After Step 2, the step of heating the mixture of the stimulable phosphor precursor and alumina fine particles to 600 ° C. or higher> Next, the crystal of the phosphor precursor is put into a quartz port,
It is filled in a heat-resistant container such as an alumina crucible or a quartz crucible and placed in the core of an electric furnace to perform firing while avoiding sintering. As the electric furnace, a moving bed type electric furnace such as a rotary kiln can also be preferably used.

The firing temperature of the mixture of the stimulable phosphor precursor and alumina fine particles needs to be heated to 600 ° C. or higher, and the range of 600 to 1300 ° C. is suitable, and 700 to 1000 ° C. Is preferred. Although the firing time varies depending on the filling amount of the phosphor raw material mixture, the firing temperature, the temperature at which the material is taken out of the furnace, etc., it is generally 0.5.
~ 12 hours is suitable.

The production of the stimulable phosphor from the phosphor precursor is preferably carried out by the following two firing methods.

Firing Method 1 While exposing the stimulable phosphor precursor to an atmosphere containing oxygen at least 100 ppm or more, at most, a volume ratio of oxygen which is smaller than the volume ratio of the reducing component to the entire atmosphere, 60
Heating above 0 ° C .; and after said step 600
The atmosphere was returned to a weak reducing atmosphere containing no oxygen of 1000 ppm or more (preferably 100 ppm or more) while maintaining the temperature of ℃ or more, and after holding for at least 30 minutes, 1
The firing method has a step of cooling to 100 ° C. or lower while maintaining a weakly reducing atmosphere containing no oxygen of 00 ppm or more.

Firing Method 2 A step of heating the stimulable phosphor precursor to 600 ° C. or higher while exposing it to 100 ppm or higher of an oxygen-free weak reducing atmosphere; after the step, while maintaining the temperature of 600 ° C. or higher. Introducing oxygen into the atmosphere at a volume ratio of at least 100 ppm or more, at most less than the volume ratio of the reducing component to the entire atmosphere, and holding it for at least 1 minute;
After the above step, the atmosphere is returned to a weak reducing atmosphere containing no oxygen of 1000 ppm or more (preferably 100 ppm or more) while keeping the temperature at 600 ° C. or more and kept for at least 30 minutes, and then 1000 ppm or more (preferably 100 ppm or more). Is a firing method having a step of cooling to 100 ° C. or lower while maintaining a weak reducing atmosphere containing no oxygen.

Further, during firing, the amount of oxygen in the stimulable phosphor can be controlled by setting the atmosphere in which a small amount of oxygen is introduced in the firing furnace. It is also possible to perform firing by the method described in JP-A-2000-8034.

The introduction of oxygen will be described in more detail. It is preferable to produce a stimulable phosphor from the precursor crystal powder filled in the furnace core by the following two firing methods. (Details of Firing Method 1) After filling the core with the stimulable phosphor precursor, the atmosphere in the core is changed from the atmosphere to an atmosphere containing oxygen at a volume ratio smaller than the volume ratio of the reducing component to the entire atmosphere. Replace. Prior to this atmosphere replacement, the atmosphere inside the furnace core may be discharged to create a vacuum. A rotary pump or the like can be used for vacuum suction. When the furnace core is evacuated, there is an advantage that the efficiency of atmosphere replacement becomes high. In the case of so-called displacement replacement, which replaces the atmosphere without passing through a vacuum,
At least three times the volume of the furnace core should be injected.

The "atmosphere containing oxygen in a volume ratio smaller than the volume ratio of the reducing component to the entire atmosphere" referred to in the present invention means a mixed gas containing at least two types of components, a reducing component and oxygen. Considering safety in handling the mixed gas, it is preferable that the mixed atmosphere contains more inert components than the above two components. Here, the inactive component is nitrogen, argon, etc., and the reducing component is hydrogen, etc. A mixed gas of nitrogen, hydrogen and oxygen can be preferably used in terms of availability and cost. The preferable mixture ratio of nitrogen, hydrogen and oxygen is 91: 5: 4, and if the hydrogen concentration exceeds 5%, it is not preferable in terms of safety when the mixed gas leaks. A more preferable mixing ratio is 3% hydrogen concentration and 2% oxygen concentration.

After replacing the inside of the furnace core of the electric furnace with the above mixed atmosphere, heating is performed at 600 ° C. or higher. Thus 600 ℃
Heating above is preferable because good light emission characteristics can be obtained. From the start of heating to the removal of the stimulable phosphor, the mixed atmosphere in the furnace core is preferably allowed to flow at a flow rate of at least 0.1 liter / min or more.
As a result, the atmosphere in the furnace core is replaced, so that reaction products other than the stimulable phosphor produced in the furnace core can be discharged. In particular, when iodine is contained in the reaction product, it is possible to prevent yellowing of the stimulable phosphor due to iodine and deterioration of the stimulable phosphor due to the yellowing.

The mixed atmosphere in the furnace core is preferably 1.0
Circulate at a flow rate of up to 5.0 liters / min. The rate of temperature rise varies depending on the material of the furnace core tube, the filling amount of the precursor crystals, the specifications of the electric furnace, and the like, but is 1 to 50 ° C / m.
in is preferred.

After reaching 600 ° C. or higher, the atmosphere is changed to 10
After returning to a weak reducing atmosphere that does not contain oxygen of 00 ppm or more (preferably 100 ppm or more), at least 30
Hold for minutes. As a result, it is possible to prevent deterioration of the photostimulated luminescent properties of the photostimulable phosphor. The temperature at this time is
Preferably 600 to 1300 ° C, more preferably 700
~ 1000 ° C. By setting the temperature above 600 ° C,
Good stimulated emission characteristics can be obtained, and at 700 ° C. or higher, it is possible to obtain further stimulated emission characteristics which are practically preferable for diagnosis of radiographic images. Further, if the temperature is 1300 ° C. or lower, it is possible to prevent the particle size from becoming large by sintering, and particularly if the temperature is 1000 ° C. or lower, a stimulable phosphor having a particle size practically preferable for diagnosis of radiation images can be obtained. it can. More preferably, it is around 820 ° C. Here, replacement of the atmosphere is performed by purge replacement, and as the newly introduced weak reducing atmosphere, a mixed gas having a hydrogen concentration of 5% or less, an oxygen concentration of less than the hydrogen concentration, and a remaining component of nitrogen is preferable. More preferably,
It is a mixed gas in which the hydrogen concentration is 0.1% or more and 3% or less, the oxygen concentration is 40% or more and 80% or less with respect to the hydrogen concentration, and the remaining component is nitrogen. Especially, 1% hydrogen and 0.6 oxygen
%, And the remaining component is a mixed gas of nitrogen. When the hydrogen concentration is 0.1% or more, a reducing power can be obtained, and the emission characteristics can be improved. When the hydrogen concentration is 5% or less, it is preferable in terms of handling. Further, the stimulable phosphor crystal itself is reduced. It can be prevented from being done. Further, the oxygen concentration has a peak at about 60% of the hydrogen concentration, and the stimulated emission intensity can be remarkably improved.

In order to expel the oxygen introduced during the temperature rise and remaining in the furnace core to less than 1000 ppm (preferably less than 100 ppm), the flow rate of new weak reducing gas may be temporarily increased. Although the efficiency of substitution changes depending on the amount of oxygen introduced at the beginning, when an atmosphere containing 1% oxygen is taken as an example, when the capacity of the core is 10 times or more the volume of new weak reducing gas is introduced. Oxygen is expelled to less than 1000 ppm (preferably less than 100 ppm). From this time, a weak reducing atmosphere containing no oxygen of 1000 ppm or more (preferably 100 ppm or more) at 600 ° C. or higher is maintained for at least 30 minutes or longer, preferably 30 minutes to 12 hours.

By setting the time to 30 minutes or more, a stimulable phosphor exhibiting good stimulated emission characteristics can be obtained. or,
By setting the time to 12 hours or less, it is possible to prevent deterioration of the stimulated emission characteristics due to heating.

Cooling is carried out in the same manner as in the case of raising the temperature, but the atmosphere is 1000 ppm or more (preferably 100 ppm).
A weakly reducing atmosphere containing no oxygen (ppm or more) is maintained. The desired stimulable phosphor is obtained by the above firing. Further, as the firing method, the following one may be adopted. (Details of Firing Method 2) The atmosphere in the furnace core before heating is replaced in the same manner as in Firing Method 1. However, the atmosphere to be replaced is 1000 ppm or more (preferably 100 ppm
A weak reducing atmosphere containing no oxygen) is used. The weak reducing atmosphere is preferably a mixed gas having a hydrogen concentration of 5% or less and the remaining component being nitrogen. The hydrogen concentration is
When the content is 0.1% or more, a reducing power can be obtained, and the emission characteristics can be improved. When the content is 5% or less, it is preferable in handling, and the crystal itself of the stimulable phosphor is reduced. Can be prevented.

After replacing the inside of the furnace core of the electric furnace with the above mixed atmosphere, heating is performed at 600 ° C. or higher. Thus 600 ℃
Heating above is preferable because good light emission characteristics can be obtained. From the start of heating to the removal of the stimulable phosphor, the mixed atmosphere in the furnace core is preferably allowed to flow at a flow rate of at least 0.1 liter / min or more.
As a result, the atmosphere in the furnace core is replaced, so that reaction products other than the stimulable phosphor produced in the furnace core can be discharged. In particular, when iodine is contained in the reaction product, it is possible to prevent yellowing of the stimulable phosphor due to iodine and deterioration of the stimulable phosphor due to the yellowing. Furthermore, it is preferably 1.0 to 5.0 liters / min. The rate of temperature rise varies depending on the material of the furnace core, the amount of precursor crystals filled, the specifications of the electric furnace, etc., but is 1 to 50 ° C./mi.
n is preferred.

After reaching 600 ° C. or higher, oxygen is introduced into the atmosphere in a volume ratio smaller than the volume ratio of the reducing component to the entire atmosphere and kept for at least 1 minute. The temperature at this time is preferably 600 to 1300 ° C, more preferably 700 to 1000 ° C. By setting the temperature to 600 ° C. or higher, good stimulated emission characteristics can be obtained, and at 700 ° C. or higher, the stimulated emission characteristics which are more preferable for practical use in diagnosis of radiation images can be obtained. Further, if the temperature is 1300 ° C. or lower, it is possible to prevent the particle size from becoming large by sintering, and particularly if the temperature is 1000 ° C. or lower, a stimulable phosphor having a particle size practically preferable for diagnosis of radiation images can be obtained. it can. More preferably, 8
It is around 20 ° C. Here, replacement of the atmosphere is performed by purge replacement, and as the newly introduced weak reducing atmosphere, a mixed gas having a hydrogen concentration of 5% or less, an oxygen concentration of less than the hydrogen concentration, and a remaining component of nitrogen is preferable. More preferably, it is a mixed gas in which the hydrogen concentration is 0.1% or more and 3% or less, the oxygen concentration is 40% or more and 80% or less with respect to the hydrogen concentration, and the remaining component is nitrogen. In particular, hydrogen is 1%,
Oxygen is 0.6%, and the remaining component is a mixed gas of nitrogen. When the hydrogen concentration is 0.1% or more, a reducing power can be obtained, and the emission characteristics can be improved. When the hydrogen concentration is 5% or less, it is preferable in terms of handling. Further, the stimulable phosphor crystal itself is reduced. It can be prevented from being done. Further, the oxygen concentration has a peak at about 60% of the hydrogen concentration, and the stimulated emission intensity can be remarkably improved.

Further, oxygen may be mixed in the atmosphere during the temperature rise. In this case, the mixture ratio of the atmosphere can be controlled by operating the flow rate ratio of the hydrogen / nitrogen mixed gas and the oxygen gas. Further, as an alternative to oxygen, the atmosphere can be introduced as it is.
Further, the flow rate ratio of the oxygen / nitrogen mixed gas and the hydrogen / nitrogen mixed gas can be adjusted and used.

It is preferable to introduce a new atmosphere having a volume three times or more the capacity of the furnace core until the desired mixing ratio of nitrogen, hydrogen and oxygen is substituted. At least 1 from this time
A mixed atmosphere of nitrogen, hydrogen and oxygen is maintained at 600 ° C. or higher for at least 600 minutes and preferably for 1 minute to 1 hour.

After the above operation, the inside of the furnace core is replaced with a weak reducing atmosphere again. 1000ppm of oxygen remaining in the core
In order to expel the gas to less than 100 ppm (preferably less than 100 ppm), it is preferable to use the same weak reducing gas as that used at the time of heating. The flow rate of the weak reducing gas may be temporarily increased in order to increase the efficiency of replacement. 1000 pp when a new weak reducing gas with a volume 10 times the capacity of the furnace core is introduced
Oxygen is expelled to less than m (preferably less than 100 ppm). From this time, at least 30 minutes or more, preferably 30 minutes to 12 hours at 600 ° C. or more at 1000 p
A weak reducing atmosphere containing no oxygen of pm or more (preferably 100 ppm or more) is maintained.

By setting the time to 30 minutes or more, a stimulable phosphor exhibiting good stimulable luminescence characteristics can be obtained. or,
By setting the time to 12 hours or less, it is possible to prevent deterioration of the stimulated emission characteristics due to heating.

In the present invention, cooling is performed in the same manner as in the case of raising the temperature. In the present invention, the surface of the stimulable phosphor thus obtained is preferably further treated with metal oxide fine particles. The metal oxide fine particles that can be used are not particularly limited, but examples thereof include silica, alumina, and titanium oxide. These metal oxide fine particles have 1
Only one kind may be used, or two or more kinds may be used.

The average particle size of the metal oxide fine particles is 2 to 50.
It is preferably nm. The metal oxide fine particles having an average particle diameter of less than 2 nm are industrially difficult to obtain, and when the average particle diameter exceeds 50 nm, the surface of the phosphor particles cannot be effectively covered, and the fluorescent particles are not fluorescent. It is not preferable because it is difficult to make the particles uniformly exist in the body layer.

Specific examples of the metal oxide fine particles according to the present invention include dry process metal oxide fine particles such as silica, alumina and titanium dioxide obtained by flame hydrolysis or arc method, and sodium silicate. Examples thereof include wet process metal oxide fine particles obtained by decomposing various salts with an acid, and those obtained by various production methods such as those obtained by hydrolyzing an organogel.

To mix an appropriate amount of metal oxide fine particles with phosphor particles having an average particle diameter of several μm to several tens of μm, a known mixing method can be used. For example, a turbula shaker mixer ( For example, using a mixing device such as Shinmaru Enterprises Co., Ltd., a mixing method of gradually adding phosphor particles to the total amount of metal oxide fine particles, or 0.5 to 10.0 mass% Examples of the method include a method in which the phosphor particles are stirred in the metal oxide fine particle dispersion liquid, followed by filtration and drying. These methods are preferable from the viewpoint of uniform coating on the phosphor particles.

In addition, in order to add the metal oxide fine particles at the time of preparing the phosphor coating liquid, it is necessary to mix them with a binder and a solvent in advance, disperse them in a slurry form with a bead mill, and then add them. It is preferable because the state of distribution can be made uniform. Addition amount of metal oxide fine particles is 0.01 to 10
It is preferably mass%, more preferably 0.05 to 5 mass%, further preferably 0.1 to 2 mass%. If it exceeds 10% by mass, the sensitivity is lowered, and if it is less than 0.01% by mass, the effect of the present invention cannot be sufficiently exhibited.

In the present invention, it is preferable to use a silane coupling agent together when the surface of the phosphor particles is treated with the metal oxide fine particles. The combined use of a silane coupling agent is preferable because it can prevent the luminance of the phosphor particles from decreasing.

The silane coupling agent that can be used in the present invention is not particularly limited, but a compound represented by the following general formula (2) is preferable.

[0061]

[Chemical 1]

In the formula, R represents an aliphatic or aromatic hydrocarbon group, which may have an unsaturated group (for example, a vinyl group), R ₂ OR ₃ —, R ₂ COOR ₃ —, R ₂ NHR ₃
- (R ₂ represents an alkyl group or an aryl group, R ₃ represents an alkylene group or an arylene group), may be substituted with other substituents.

X ₁ , X ₂ and X ₃ are each an aliphatic or aromatic hydrocarbon, an acyl group, an amide group, an alkoxy group,
It represents an alkylcarbonyloxy group, an epoxy group, a mercapto group or a halogen atom. However, at least one of X ₁ , X ₂ , and X ₃ is a group other than hydrocarbon. Also, X ₁ ,
Each of X ₂ and X ₃ is preferably a group that undergoes hydrolysis.

Specific examples of the silane coupling agent represented by the general formula (2) include, for example, methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxysilane, vinyltrichlorosilane, vinyltriethoxysilane and γ-. Chloropropyltrimethoxysilane, γ
-Chloropropylmethyldichlorosilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N -(Β-aminoethyl)-
γ-Aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-methacryloxypropyltri Methoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ- Anilinopropyltrimethoxysilane, vinyltrimethoxysilane,
Examples thereof include N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane / hydrochloride and an aminosilane compound. Particularly, vinyl-based, mercapto-based, glycidoxy-based, and methacryloxy-based are preferable,
In particular, the silane coupling agent preferably has a mercapto group.

As a method for surface-treating the phosphor particle surface with the above-mentioned silane coupling agent, a known method can be used. For example, a Henschel mixer is used to stir and mix the phosphor particles while silane coupling is performed. A dry method of dropping or spraying the agent, a slurry method of removing the residual solvent by drying the phosphor by precipitating and filtering the phosphor after the dripping of the silane coupling agent while stirring the phosphor in the form of slurry and filtering the phosphor after completion of the dropping, A method of dispersing a phosphor in a solvent, adding a silane coupling agent to this, stirring and then evaporating the solvent to form an adhesion layer, or adding a silane coupling agent to a coating dispersion for a stimulable phosphor. The method of doing is mentioned.

The silane coupling agent may be attached to the surface of the phosphor particles at the same time when the fine particles of the group oxide are coated.

The surface-treated phosphor particles may be classified. The particle size distribution of the phosphor particles according to the present invention is excellent due to the effect of the liquid phase method, but classification can prevent the inclusion of unexpectedly coarse particles and impurity particles brought from a process.

The stimulable phosphor particles (crystals) according to the present invention preferably have an average particle size of 1 to 10 μm and are monodisperse, and have an average particle size of 1 to 5 μm and a distribution of average particle sizes. (%) Is more preferably 20% or less, particularly preferably having an average particle size of 1 to 3 μm and an average particle size distribution of 15% or less. The average particle size in the present invention means particles (crystals)
200 particles were randomly selected from the electron micrograph and the average was obtained by the volume particle diameter in terms of sphere.

Using the stimulable phosphor particles obtained as described above, the radiation image conversion panel of the present invention containing the stimulable phosphor can be obtained by the method described below.

As the support used in the radiation image storage panel of the present invention, various polymer materials, glass, metals and the like are used. In particular, those which can be processed into a flexible sheet or web for handling as an information recording material are preferable, and in this respect, cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, Plastic films such as polycarbonate film, aluminum, iron, copper,
A metal sheet such as chromium or a metal sheet having a coating layer of the metal oxide is preferable.

The layer thickness of these supports varies depending on the material of the support used and the like, but is generally 80 μm to 10 μm.
It is 00 μm, and more preferably 80 μm to 500 μm from the viewpoint of handling.

The surface of these supports may be a smooth surface, or may be a matte surface for the purpose of improving the adhesiveness with the stimulable phosphor layer. Furthermore, these supports are provided with an undercoat layer on the surface on which the stimulable phosphor layer is provided for the purpose of improving the adhesiveness with the stimulable phosphor layer.
It preferably contains a polymer resin that can be crosslinked with a crosslinking agent and a crosslinking agent.

The polymer resin that can be used in the undercoat layer is not particularly limited, but examples thereof include polyurethane, polyester, vinyl chloride copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer. Polymer,
Vinyl chloride-acrylonitrile copolymer, butadiene-
Acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivative (nitrocellulose etc.), styrene-butadiene copolymer, various synthetic rubber resins, phenol resin, epoxy resin, urea resin, melamine resin, phenoxy resin, silicone resin , Acrylic resin, urea formamide resin and the like. Among them, polyurethane, polyester, vinyl chloride copolymer, polyvinyl butyral, nitrocellulose and the like can be mentioned. In the invention according to claim 2, the average glass transition temperature (Tg) of the polymer resin used in the undercoat layer is ) Is 25
One of the characteristics is that the temperature is ℃ or more, preferably 25
Is to use a polymer resin having a Tg of ˜200 ° C.

The cross-linking agent that can be used in the undercoat layer according to the present invention is not particularly limited, and examples thereof include polyfunctional isocyanates and their derivatives, melamine and its derivatives,
Amino resins and their derivatives can be mentioned,
It is preferable to use a polyfunctional isocyanate compound as the crosslinking agent, and examples thereof include Coronate HX and Coronate 3041 manufactured by Nippon Polyurethane Company.

The subbing layer can be formed on the support by the following method, for example. First, the above-mentioned polymer resin and a cross-linking agent are added to a suitable solvent, for example, the solvent used in the preparation of the stimulable fluorescent layer coating solution described below, and this is mixed sufficiently to prepare an undercoat layer coating solution. . The amount of crosslinking agent used is
Depending on the characteristics of the intended radiation image conversion panel, the type of material used for the stimulable phosphor layer and the support, the type of polymer resin used in the undercoat layer, etc. In consideration of maintaining the adhesive strength, it is preferable to add the polymer resin in a ratio of 50% by mass or less, and particularly preferably 15 to 50% by mass.

The thickness of the undercoat layer is the desired characteristics of the radiation image conversion panel, the types of materials used for the stimulable phosphor layer and the support, the types of polymer resins and crosslinking agents used for the undercoat layer, and the like. It is preferably 3 to 50 μm, and particularly preferably 5 to 40 μm, although it depends on the above.
The undercoat layer preferably contains a polymer resin that can be crosslinked with a crosslinking agent and a crosslinking agent.

The polymer resin that can be used in the undercoat layer is not particularly limited, but examples thereof include polyurethane, polyester, vinyl chloride copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer. Polymer,
Vinyl chloride-acrylonitrile copolymer, butadiene-
Acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivative (nitrocellulose etc.), styrene-butadiene copolymer, various synthetic rubber resins, phenol resin, epoxy resin, urea resin, melamine resin, phenoxy resin, silicone resin , Acrylic resin, urea formamide resin and the like. Among them, polyurethane, polyester, vinyl chloride copolymer, polyvinyl butyral, nitrocellulose and the like can be mentioned, and the average glass transition temperature (Tg) of the polymer resin used in the undercoat layer is 25 ° C. or higher. Is preferable, and more preferably, a polymer resin having a Tg of 25 to 200 ° C. is used.

The cross-linking agent that can be used in the undercoat layer is not particularly limited, and examples thereof include polyfunctional isocyanates and their derivatives, melamine and its derivatives, amino resins and their derivatives, and the like. It is preferable to use a polyfunctional isocyanate compound as
Examples thereof include Coronate HX and Coronate 3041 manufactured by Nippon Polyurethane Company.

The subbing layer can be formed on the support by the following method, for example. First, the above-mentioned polymer resin and a cross-linking agent are added to a suitable solvent, for example, the solvent used in the preparation of the stimulable fluorescent layer coating solution described below, and this is mixed sufficiently to prepare an undercoat layer coating solution. . The amount of crosslinking agent used is
Depending on the characteristics of the intended radiation image conversion panel, the type of material used for the stimulable phosphor layer and the support, the type of polymer resin used in the undercoat layer, etc. In consideration of maintaining the adhesive strength, it is preferable to add the polymer resin in a ratio of 50% by mass or less, and particularly preferably 15 to 50% by mass.

The film thickness of the undercoat layer is the desired characteristics of the radiation image conversion panel, the type of material used for the stimulable phosphor layer and the support, the type of polymer resin and crosslinker used for the undercoat layer, etc. It is preferably 3 to 50 μm, and particularly preferably 5 to 40 μm, although it depends on the above.

Examples of the binder used in the stimulable phosphor layer are proteins such as gelatin, polysaccharides such as dextran, or natural polymer substances such as gum arabic; and polyvinyl butyral and polyvinyl acetate.
Represented by synthetic polymer substances such as nitrocellulose, ethyl cellulose, vinylidene chloride / vinyl chloride copolymer, polyalkyl (meth) acrylate, vinyl chloride / vinyl acetate copolymer, polyurethane, cellulose acetate butyrate, polyvinyl alcohol, linear polyester, etc. The binders mentioned can be mentioned.
Particularly preferred among such binders are nitrocellulose, linear polyesters, polyalkyl (meth) acrylates, mixtures of nitrocellulose and linear polyesters, mixtures of nitrocellulose and polyalkyl (meth) acrylates and It is a mixture of polyurethane and polyvinyl butyral. Note that these binders may be crosslinked with a crosslinking agent.

The stimulable phosphor layer can be formed on the undercoat layer by the following method, for example. First, an iodine-containing stimulable phosphor, a compound such as a phosphite ester for preventing yellowing and a binder are added to a suitable solvent, and these are sufficiently mixed to obtain a phosphor particle and a binder solution in a binder solution. A coating solution in which particles of the compound are uniformly dispersed is prepared.

Examples of the binder include proteins such as gelatin, polysaccharides such as dextran or gum arabic, polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethyl cellulose, vinylden chloride.
A film-forming binder which is usually used for layer constitution, such as vinyl chloride copolymer, polymethylmethacrylate, vinyl chloride / vinyl acetate copolymer, polyurethane, cellulose acetate butyrate, polyvinyl alcohol, etc. is used. Generally, the binder is used in the range of 0.01 to 1 part by mass with respect to 1 part by mass of the stimulable phosphor. However, in terms of sensitivity and sharpness of the obtained radiation image conversion panel, it is preferable that the amount of the binder is small, and the range of 0.03 to 0.2 parts by mass is more preferable from the viewpoint of easy coating.

The mixing ratio of the binder and the stimulable phosphor in the coating liquid (however, when all the binder is an epoxy group-containing compound, it is equal to the ratio of the compound and the phosphor),
Target radiation image conversion panel characteristics, phosphor type,
Depending on the amount of epoxy group-containing compound added, etc.,
In general, examples of the solvent for preparing the binding coating solution include lower alcohols such as methanol, enothal, 1-propanol, 2-propanol and n-butanol; chlorine atom-containing hydrocarbons such as methylene chloride and ethylene chloride; acetone, methyl ethyl ketone. , Ketones such as methyl isobutyl ketone; esters of lower fatty acids such as methyl acetate, ethyl acetate, butyl acetate and lower alcohols; dioxane, ethylene glycol ethyl ether,
Mention may be made of ethers such as ethylene glycol monomethyl ether; toluene; and mixtures thereof.

The coating liquid contains a dispersant for improving the dispersibility of the phosphor in the coating liquid, and a binder between the binder and the phosphor in the stimulable phosphor layer after formation. Various additives such as a plasticizer for improving the binding strength may be mixed. Examples of dispersants used for such purpose include phthalic acid, stearic acid, caproic acid, lipophilic surfactants and the like. Examples of plasticizers include phosphoric acid esters such as triphenyl phosphate, tricresyl phosphate, diphenyl phosphate; phthalic acid esters such as diethyl phthalate and dimethoxyethyl phthalate; ethyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, etc. Glycolic acid ester of
Examples thereof include polyesters of triethylene glycol and adipic acid, polyesters of polyethylene glycol such as polyesters of diethylene glycol and succinic acid, and aliphatic dibasic acids.

The coating solution prepared as described above is then uniformly applied to the surface of the undercoat layer to form a coating film of the coating solution. This coating operation can be performed by using an ordinary coating means such as a doctor blade, a roll coater or a knife coater.

Next, the formed coating film is gradually heated and dried to complete the formation of the stimulable phosphor layer on the undercoat layer. The layer thickness of the stimulable phosphor layer varies depending on the characteristics of the intended radiation image conversion panel, the type of stimulable phosphor, the mixing ratio of the binder and the phosphor, etc.
It is preferably selected from the range of 1000 μm, and 10 μm
More preferably, it is selected from the range of m to 500 μm.

The coating liquid for the stimulable phosphor layer is prepared by using a dispersing device such as a ball mill, a sand mill, an attritor, a three roll mill, a high speed impeller disperser, a Kady mill and an ultrasonic disperser. The prepared coating solution is applied onto a support using a coating solution such as a doctor blade, a roll coater or a knife coater and dried to form a stimulable phosphor layer. The coating liquid may be applied onto the protective layer and dried, and then the stimulable phosphor layer and the support may be bonded to each other.

The film thickness of the stimulable phosphor layer of the radiation image conversion panel of the present invention depends on the desired characteristics of the radiation image conversion panel, the type of stimulable phosphor, the binder and the stimulable phosphor. Although it depends on the mixing ratio and the like, it is preferably selected from the range of 10 μm to 1000 μm, more preferably 10 μm to 500 μm.

The examples of the stimulable phosphor such as europium-activated barium fluoroiodide have been mainly described above. The europium-activated barium fluorobromide and other stimulable phosphors represented by the general formula (1) are described above. Regarding the production of the body, the above may be referred to.

[0091]

EXAMPLES The present invention will be illustrated below with reference to examples.

<Synthesis of Photostimulable Phosphor Precursor><Production of Precursor PC1 (Nonconcentration Method)> In order to synthesize a photostimulable phosphor precursor of europium-activated barium fluoroiodide, a BaI ₂ aqueous solution is prepared. (4.2 mol / liter) 23
80 ml and EuI ₃ (0.2 mol / liter) 27 m
1 was placed in the reactor. The reaction mother liquor in this reactor was kept warm at 83 ° C. with stirring. Ammonium fluoride aqueous solution (1
(3 mol / liter) 200 ml was poured into the reaction mother liquor with a roller pump at an addition time of 30 minutes to form a precipitate. After completion of the injection, heat retention and stirring were continued for 120 minutes to ripen the precipitate. Next, the precipitate was filtered off, washed with methanol, and dried in vacuum. The yield obtained by measuring the mass of the recovered precursor and comparing it with the input amount of BaI ₂ was 23%. Crystals of europium-activated barium fluoroiodide having an average particle size of 2.5 μm were obtained.
A laser diffraction / scattering particle size analyzer (LMS-30 manufactured by Seishin Enterprise Co., Ltd.) was used to measure the average particle size.

<Production of Precursor PC2 (Concentration Method)> In order to synthesize a europium-activated barium fluoroiodide stimulable phosphor precursor, a pressure-resistant container having two holes was filled with BaI ₂
2500 ml of an aqueous solution (4 mol / liter) and EuI ₃
26.5 ml of an aqueous solution (0.2 mol / liter) was placed in the reactor. Further, 992 g of potassium iodide was added to the aqueous solution. While stirring the reaction mother liquor in this reactor, 83
It was kept warm at ℃. Aqueous ammonium fluoride solution (10 mol /
600 liters) was poured into the reaction mother liquor using a roller pump to form a precipitate.

After completion of the injection, dry air was aerated at a rate of 10 L / min for 20 minutes. The mass ratio before and after aeration was 0.95. Stirred at that temperature for 90 minutes. The precipitate was filtered and washed with 2000 ml of ethanol. The yield obtained by measuring the mass of the recovered precursor and comparing it with the input amount of BaI ₂ was 62%. The average particle size is 3.
1 μm europium activated barium fluoroiodide crystals were obtained.

Example 1 0.2% by mass of fine particle powder of alumina (alumina C, particle size 13 nm, manufactured by Nippon Aerosil Co., Ltd.) was used with respect to the precursor PC2.
After the addition, the mixture was thoroughly stirred with a mixer to deposit fine alumina powder on the surface of the precursor crystal.

Next, the mixture of the precursor crystal and the alumina fine particle powder was charged into a quartz core tube of a batch type rotary kiln having a core volume of 10 liters, and was filled with 99% nitrogen / 1.
20% hydrogen mixed gas at a flow rate of 10 l / min
The atmosphere was replaced by circulating for minutes. After sufficiently replacing the atmosphere in the furnace core, the flow rate of the mixed gas of 99% nitrogen / 1% hydrogen was reduced to 2 liters / min, and while rotating the furnace core tube at a speed of 2 rpm, 10 ° C./min. At a heating rate of 82
Heated to 0 ° C.

After the sample temperature reached 820 ° C., while maintaining the temperature at 820 ° C., 98.4% nitrogen / 1% hydrogen / 0.
2% mixed gas of 6% oxygen at a flow rate of 10 l / min
The atmosphere was replaced by flowing for 0 minutes. Then 98.4%
The flow rate of the mixed gas of nitrogen / 1% hydrogen / 0.6% oxygen was reduced to 2 liters / min and the temperature was maintained for 20 minutes.

Next, the atmosphere was replaced by flowing a 99% nitrogen / 1% hydrogen mixed gas at a flow rate of 10 l / min for 20 minutes. After sufficiently replacing the atmosphere in the furnace core,
The flow rate of the mixed gas of 99% nitrogen / 1% hydrogen is 2 liters /
It was reduced to min and held for 60 minutes. Then, while maintaining the flow rate of 99% nitrogen / 1% hydrogen mixed gas at 2 liters / min, the atmosphere was returned to the atmosphere after cooling to 25 ° C. at a temperature lowering rate of 10 ° C./min to activate the oxygen-doped europium generated. The barium fluoroiodide phosphor particles were taken out. The obtained powder is classified by a sieve, and the average particle size is 2.5.
μm phosphor particles were obtained.

Next, an example of producing a radiation image conversion panel will be described. As the phosphor layer forming material, the oxygen-doped
427 g of europium-activated barium fluoroiodide phosphor,
Polyurethane resin (Sumitomo Bayer Urethane Co., Desmolac 4125) 15.8 g and bisphenol A type epoxy resin 2.0 g were added to a methyl ethyl ketone-toluene (1: 1) mixed solvent, dispersed by a propeller mixer, and a viscosity was 2.5. A coating solution of ˜3.0 Pa · s was prepared. After applying this coating solution on a polyethylene terephthalate film with an undercoat layer using a doctor blade,
It was dried at 100 ° C. for 15 minutes to form a phosphor layer having a thickness of 230 μm.

Preparation of Example 2 and Comparative Examples 1 to 10 A stimulable phosphor of Example 2 was prepared in the same manner as in Example 1 except that the amount of alumina fine particle powder shown in Table 1 was changed. Further, as Comparative Examples 1 to 8, each stimulable phosphor was produced in the same manner as in Example 1 except that the precursors shown in Table 1 were used and the amount of alumina ultrafine powder shown in the table was added. Further, instead of the alumina ultrafine powder, silica fine powder (manufactured by Nippon Aerosil Co., Ltd., A-300, 13 nm) was changed, and the addition amount was the same as in Example 1 except that the amount described in Table 1 was used. Thus, stimulable phosphors of Comparative Examples 9 and 10 were obtained. Using each of the obtained stimulable phosphors, each radiation image conversion panel was produced in the same manner as in Example 1.

<Evaluation of Radiation Image Conversion Panel> For each radiation image conversion panel, the amount of stimulated emission (luminance) was measured according to the method described below. The results are shown in Table 1 (stimulated luminescence amount). The luminance was measured by irradiating each radiation image conversion panel with X-ray of a tube voltage of 80 kVp and 200 mR, and then irradiating the panel with He-Ne laser light (633 nm).
Excitation is performed by scanning at 4.0 J / m ² , and stimulated emission emitted from the phosphor layer is received by a photodetector (photoelectron image multiplier with spectral sensitivity S-5) through an optical filter (B-410). The stimulated luminescence amount was measured. The stimulated emission is 1.00 in Example 1.
It was shown as a relative value. It is preferable that this value is large.

[0102]

[Table 1]

As is clear from the obtained results, the stimulable fluorescent substance obtained by adding fine particles of alumina to the precursor obtained by the concentration method in a specific range and baking the precursor. It can be seen that the body has excellent emission luminance, and the radiation image conversion panel manufactured using the body has excellent performance.

[0104]

EFFECT OF THE INVENTION Fine particles of alumina are added to the precursor obtained by the concentration method, and the addition amount is added within a specific range,
The stimulable phosphor obtained by firing had excellent emission brightness, and a radiation image conversion panel having excellent performance could be obtained.

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Claims (5)

[Claims] 1. A method for producing an oxygen-introduced rare earth-activated alkaline earth metal fluorohalide stimulable phosphor represented by the following general formula (1), which comprises at least the following three steps. Oxygen-introduced rare earth activated alkaline earth metal fluorohalide stimulable phosphor. General formula (1) Ba _1-x (M ₂ ) _x FBr _y I _1-y : aM ₁ , bLn, cO [wherein at least M ₁ is selected from the group consisting of Li, Na, K, Rb, and Cs. one alkali metal, M _2: be, Mg, at least one alkaline earth metal selected from the group consisting of Sr and Ca, Ln: Ce, Pr, Sm, Eu, Gd, Tb, Tm, D
at least one rare earth element selected from the group consisting of y, Ho, Nd, Er and Yb, x, y, a, b and c
Are 0 ≦ x ≦ 0.3, 0 <y ≦ 0.3, 0 ≦ a, respectively.
≦ 0.05,0 <b ≦ 0.2,0 <c ≦ 0.1] Step 1: a step of forming a precursor of a stimulable phosphor by a liquid phase method, wherein the barium concentration in the reaction mother liquor is Is 3.3mo
a step of obtaining a stimulable phosphor precursor by removing the solvent from a solution of 1 / L or more, step 2: after step 1, with respect to the stimulable phosphor precursor,
Alumina fine particles with a particle size of 2 to 50 nm are added in an amount of 0.15 to 0.3
Step of adding and mixing 0 mass% Step 3: After Step 2, heating the mixture of the stimulable phosphor precursor and alumina fine particles to 600 ° C. or higher. 2. The oxygen-introduced rare earth-activated alkaline earth metal fluorohalide as claimed in claim 1, wherein the mass after the removal of the solvent in the step 1 is 0.97 or less with respect to the mass before the removal. Method for producing exhaustible phosphor. 3. The oxygen-introduced rare earth-activated alkali according to claim 1 or 2, wherein a means for heating the reaction mother liquor and removing another solvent is used in combination to remove the reaction solvent in step 1. Method for producing an earth metal fluorohalide stimulable phosphor. 4. An oxygen-introduced rare earth-activated alkaline earth metal fluorohalide stimulable phosphor obtained by the method according to claim 1. 5. A radiation image storage panel comprising the oxygen-introduced rare earth activated alkaline earth metal fluorohalide stimulable phosphor according to claim 4 in a phosphor layer.