JP2001174594A - Manufacturing method for radiological image conversion panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a radiological image conversion panel having superior graininess and uniformity on the surface and providing a high picture quality and to provide a manufacturing method suited for manufacturing the radiological image conversion panel used for a neutron image formation method in particular. SOLUTION: This method for manufacturing the radiological image conversion panel comprises a phosphor layer coating liquid preparation process dispersing and dissolving phosphor layer components comprising, at least, phosphor and binder and preparing the phosphor layer coating liquid, and a phosphor layer forming process forming the phosphor layer comprising the phosphor layer coating liquid on the surface of a support body. This manufacturing method for the radiological image conversion panel is characterized by that the phosphor layer components are dispersed and dissolved after adding a solvent thereto by such a quantity as setting viscosity, which is obtained by the phosphor layer coating liquid preparation process after the dispersion and dissolution, to 1-10 Pa.s.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a radiation image conversion panel used in a radiation image conversion method using a stimulable phosphor.

[0002]

2. Description of the Related Art As an alternative to the conventional radiographic method, there has been known a radiation image conversion method using a stimulable phosphor as described in, for example, JP-A-55-12145. This method uses a radiation image conversion panel (also referred to as a stimulable phosphor sheet) containing a stimulable phosphor, and emits radiation transmitted through a subject or emitted from a subject to the stimulable phosphor. The radiation energy accumulated in the stimulable phosphor is absorbed by the phosphor, followed by exciting the stimulable phosphor with electromagnetic waves (excitation light) such as visible light and infrared light in a time series manner. Is emitted as fluorescence (stimulated emission light), the fluorescence is photoelectrically read to obtain an electric signal, and a radiation image of a subject or a subject is reproduced as a visible image based on the obtained electric signal. . On the other hand, the read-out radiation image conversion panel is prepared for the next photographing after the remaining image is deleted. That is, the radiation image conversion panel is used repeatedly in this manner.

According to this radiographic image conversion method, a radiographic image with a large amount of information can be obtained with a much smaller exposure dose than the radiographic method using a combination of a conventional radiographic film and an intensifying screen. There is an advantage that it can be obtained. Furthermore, in contrast to the conventional radiographic method, which consumes radiographic film for each photographing, the radiographic image conversion method uses the radiographic image conversion panel repeatedly, which is advantageous in terms of resource conservation and economic efficiency. It is.

The radiation image conversion panel used in the radiation image conversion method contains, as a basic structure, a support and a stimulable phosphor provided on the surface thereof (hereinafter, may be simply referred to as “phosphor”). And a phosphor layer.
The phosphor layer generally comprises a phosphor and a binder that contains and supports the phosphor in a dispersed state. The stimulable phosphor is X
When irradiated with excitation light after absorbing radiation such as radiation, it has the property of stimulating luminescence, so radiation transmitted through a subject or emitted from a subject is proportional to the amount of radiation. Absorbed by the phosphor layer of the image conversion panel, a radiation image of the subject or the subject is formed on the panel as a radiation energy accumulation image. This accumulated image can be emitted as stimulated emission light by irradiating the excitation light, and the accumulated image of radiation energy is imaged by photoelectrically reading the stimulated emission light and converting it into an electric signal. It is possible to do.

In general, a phosphor layer is prepared by dispersing and dissolving a phosphor layer coating solution by adding an appropriate solvent to a phosphor layer constituent component comprising at least a phosphor and a binder. It is formed by coating and drying on the surface. The phosphor layer coating solution is desired to have a predetermined viscosity in order to obtain properties suitable for coating, but the types of the phosphor layer constituent components and the solvent to be used, and the production lot of the material,
The viscosity of the prepared phosphor layer coating liquid varies from time to time depending on the storage period and the state. Therefore, in actual production, a solvent is added to the constituents of the phosphor layer, the viscosity is measured at the stage of dispersion and dissolution, and the solvent is further added according to the measured value, or the solvent is evaporated to obtain the viscosity. At present, adjustment is performed to prepare a phosphor layer coating solution to be provided for coating.

However, when the phosphor layer is formed from the phosphor layer coating solution obtained by adjusting the viscosity later, the graininess and uniformity of the surface of the radiation image conversion panel are reduced. The reduction in graininess and uniformity affects image quality. In particular, this tendency is remarkable when an inorganic powder is contained as a constituent material of the phosphor layer for various purposes in the phosphor layer coating solution.

Further, Japanese Patent Application Laid-Open No. 61-28899,
In the neutron image forming method disclosed in JP-A-8-29901 and the like, neutrons are absorbed as a phosphor layer constituent component in a stimulable phosphor sheet (radiation image conversion panel) to emit secondary radiation. Contains substances. Thus, neutrons are absorbed together with the phosphor,
By including a substance that emits secondary radiation, the radiation image conversion panel is irradiated with neutrons to accumulate and accumulate the energy of the secondary radiation in the phosphor, and is in the excitation wavelength region of the accumulative phosphor. Since stimulated emission is performed by two-dimensional scanning with the excitation light, an image signal indicating a neutron image can be obtained by photoelectrically detecting the stimulated emission light.

In the production of the radiation image conversion panel used in the neutron image forming method, the problem caused by the viscosity adjustment becomes extremely remarkable. That is, neutrons are absorbed and 2
After adding a solvent, dispersing and dissolving the substance to the phosphor layer component composed of the substance that emits the next radiation, the phosphor and the binder, and further adjusting the viscosity, the phosphor layer coating solution was prepared. In some cases, the granularity and uniformity of the surface of the radiation image conversion panel obtained by the method are greatly reduced, and the image quality is also reduced.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing a radiation image conversion panel which can provide high quality images with good surface granularity and uniformity. An object of the present invention is to provide a manufacturing method suitable for manufacturing a radiation image conversion panel used for a forming method.

[0010]

The above object is achieved by the present invention described below. That is, the present invention provides: <1> a phosphor layer coating solution preparation step of preparing a phosphor layer coating solution by dispersing and dissolving at least a phosphor layer constituent component comprising a phosphor and a binder in a solvent; A phosphor layer forming step of forming a phosphor layer composed of the phosphor layer coating solution, the method for manufacturing a radiation image conversion panel, wherein the phosphor layer coating solution preparation step, after dispersing and dissolving The viscosity of the obtained phosphor layer coating solution is 1 to 10P
A method for producing a radiation image conversion panel, comprising a step of adding a solvent in an amount of a · s to a component of a phosphor layer and then dispersing and dissolving the solvent.

<2> The method for manufacturing a radiation image conversion panel according to <1>, further comprising an inorganic powder other than the phosphor as a constituent of the phosphor layer.

<3> The inorganic powder absorbs neutrons and
<2> is a substance that emits secondary radiation
4. The method for manufacturing a radiation image storage panel according to item 1.

<4> The constituents of the phosphor layer are dispersed and dissolved in a solvent using a small amount of material in advance, and the relationship between the amount of the solvent and the viscosity of the resulting phosphor layer coating solution is determined. The viscosity of the phosphor layer coating liquid obtained after dispersion and dissolution, which is determined according to the relationship, is 1 to 10 Pa ·
s is added to the phosphor layer constituent components in the phosphor layer coating solution preparation step.
A method for producing a radiation image storage panel according to any one of 1> to <3>.

In the present invention, since the amount of the solvent to be added at the time of preparing the phosphor layer coating solution is adjusted in advance so as to have a viscosity suitable for coating, it is not necessary to adjust the viscosity later. There is no problem caused by the viscosity adjustment. Therefore, it is possible to provide a method for manufacturing a radiation image conversion panel that can provide a high-quality image with good surface granularity and uniformity, and is particularly suitable for manufacturing a radiation image conversion panel used in a neutron image forming method. ing.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail for each step. A: Phosphor Layer Coating Solution Preparation Step [Composition of Phosphor Layer Coating Solution] (1) Phosphor Layer Constituents a) Binder The binder used in the present invention is not particularly limited. Are natural polymers such as proteins such as gelatin, polysaccharides such as dextran, or gum arabic; and polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethyl cellulose, vinylidene chloride-vinyl chloride copolymer, polyalkyl (meth) Examples of the binder include synthetic polymers such as acrylate, vinyl chloride / vinyl acetate copolymer, polyurethane, cellulose acetate butyrate, polyvinyl alcohol, linear polyester, and epoxy resin. Particularly preferred among such binders are nitrocellulose, linear polyesters, polyalkyl (meth) acrylates, polyurethanes, mixtures of nitrocellulose and linear polyester, and nitrocellulose and polyalkyl (meth).
It is a mixture with acrylate.

B) Phosphor The phosphor used in the present invention is a phosphor that emits stimulated light when irradiated with radiation and then with excitation light as described above, but from a practical point of view. Wavelength 400-9
300 to 500 n by excitation light in the range of 00 nm
It is desirable that the phosphor exhibit a photostimulated emission in the wavelength range of m. As examples of the phosphor preferably used in the radiation image conversion panel, a divalent europium-activated alkaline earth metal halide-based phosphor and a cerium-activated rare earth oxyhalide phosphor are particularly preferable because they exhibit high-luminance stimulated emission. However, in the present invention, the phosphor is not limited to these phosphors, and may be any phosphor that emits stimulated light when irradiated with radiation and then with excitation light.

C) Inorganic Powder The inorganic powder to be added to the phosphor layer coating solution preferably does not absorb photostimulated light. In order to suppress the spread of the excitation light and improve the sharpness, a colorant powder having absorption in the wavelength region of the excitation light may be added.

In order to manufacture a radiation conversion panel used in a neutron image forming method, a substance that absorbs neutrons as inorganic powder and emits secondary radiation (hereinafter, may be referred to as a “neutron converter”). ) Is added to the phosphor layer coating solution. Specifically as an element which emits secondary radiation by absorbing ^{neutrons, 6 Li, 10 B, Gd} , Cd, I
n, Sm, Eu, although Dy and Rh and the like, among them ⁶ Li, ¹⁰ B, and Gd are preferably used.

⁶ Li absorbs neutrons and absorbs 2.05 MeV
Releasing of α particles and 2.74MeV of 3H particles, ¹⁰
B absorbs neutrons and emits 1.47 MeV α particles and 0.83 MeV ⁷ Li particles. Gd absorbs neutrons and emits internal conversion electrons of 0.074 and 0.034 MeV and gamma rays of 0.3, 0.4 and 1.2 MeV. Examples of the inorganic powder containing the element include lithium fluoride, lithium carbonate, gadolinium oxide, indium hydroxide, and dysprosium oxide.

D) Other components The phosphor layer coating solution contains an epoxy resin for preventing yellowing, an isocyanate as a cross-linking agent, and a dispersion for improving the dispersibility of the phosphor in the phosphor layer coating solution. Various additives such as a plasticizer and a plasticizer for improving the bonding force between the binder and the phosphor in the phosphor layer after formation may be mixed.

(2) Solvent The solvent for preparing the coating solution for the phosphor layer is not particularly limited. For example, aromatic solvents such as toluene and xylene;
Ketones such as methyl ethyl ketone and methyl isobutyl ketone; esters such as methyl acetate, ethyl acetate and butyl acetate; ethers such as dioxane, ethylene glycol monoethyl ether and ethylene glycol monomethyl ether; and mixtures thereof.

[Preparation of phosphor layer coating solution] Dispersion and dissolution A phosphor layer component comprising the binder, the phosphor, and optionally the inorganic powder (including a neutron converter) and other components, is used for preparing a coating solution. Is dispersed and dissolved in the above solvent to prepare a phosphor layer coating solution for the radiation image conversion panel. However, the order of addition is not particularly limited, and even if a solvent for coating solution preparation is added to the phosphor layer component, the phosphor layer component is added to the solvent for coating solution preparation. Even or
After adding a solvent for coating liquid preparation to a part of the phosphor layer constituents, there is no problem even if the remaining phosphor layer constituents are added. The term “addition to” is a concept encompassing all of these addition orders.

Among these addition orders, it is preferable to dissolve the binder in a solvent in advance and then add and disperse the phosphor, from the viewpoint of the dispersion efficiency of the phosphor. Also,
As for inorganic powders and other components added as necessary, those that are soluble in the solvent are dissolved before the addition of the phosphor, and those that are insoluble in the solvent are added and dispersed together with or before or after the phosphor. It is desirable.

The mixing ratio of the binder to the phosphor in the phosphor layer coating solution (binder: phosphor) varies depending on the desired characteristics of the radiation image conversion panel, the type of the phosphor, and the like. It is selected from the range of 1: 1 to 1: 100 (weight ratio), and particularly preferably selected from the range of 1: 8 to 1:40 (weight ratio).

When the neutron converter is added as an inorganic powder to the phosphor layer coating solution, the amount of the neutron converter depends on the type of the neutron converter to be added and the desired panel characteristics. It is desirable to make the molar ratio of the element that absorbs and emits secondary radiation and the stimulable fluorescent substance (phosphor) about 1:10 to 10: 1, and particularly 2: 1 to 1: It is more desirable to be about 2.

When the solvent is added to the constituents of the phosphor layer, it is desirable to stir the solution. As for the stirring conditions, there is no problem as long as the entire solution moves and the added phosphor layer constituent components are distributed over the whole, and the size of the stirring container, the size and type of the stirring blade, the phosphor layer coating solution May be set as appropriate depending on the composition of the composition.

After the addition of the phosphor layer constituents, it is preferable to carry out a dispersion treatment so that the phosphor is completely dispersed. The dispersion treatment is performed by continuing the stirring under the same conditions or under the same conditions as when the phosphor was added. The stirring conditions were as follows: at a higher rotation speed than at the time of adding the phosphor, 30
It is preferable to carry out for more than minutes.

In the present invention, the amount of the solvent to be added to the phosphor layer coating solution is such that the viscosity of the phosphor layer coating solution obtained after dispersion and dissolution is 1 to 10 Pa · s. That is, rather than post-adjusting the viscosity after the solvent is added to the phosphor layer components, the solvent and the phosphor layer components are mixed, and the phosphor layer having an appropriate viscosity is already dispersed and dissolved. The point of the present invention lies in that the amount of the solvent is controlled so that the coating solution is prepared.

The viscosity of the phosphor layer coating solution obtained after dissolution is essential to be in the range of 1 to 10 Pa · s, but is preferably in the range of 1.5 to 6 Pa · s. More preferably, it is in the range of 4 Pa · s.
If the viscosity is too low, doctoring (meaning that the viscosity of the solution is too low and the amount of the applied solution does not adhere to the object to be coated) or the like occurs during application of the phosphor layer coating solution, which is not preferable. On the other hand, if the viscosity is too high, the coating suitability of the phosphor layer coating solution is undesirably reduced.

In the present invention, the viscosity of the phosphor layer coating solution was measured in an environment of 22 ± 3 ° C. The method for measuring the viscosity of the phosphor layer coating solution in the present invention is not particularly limited and can be performed by a conventionally known method. For example, the viscosity is measured by a B-type viscometer at a rotation speed of 20 rpm.

As a specific addition amount of the solvent in the phosphor layer coating solution, it is generally appropriate to add the solvent so that the concentration of the binder is in the range of 5 to 50% by weight. More preferably, it is in the range of 10 to 30% by weight. However, in the present invention, the amount of the solvent to be added is appropriately adjusted depending on the desired viscosity as described above.

In actual production, regarding the amount of the solvent to be added to the phosphor layer constituents, the phosphor layer constituents are dispersed and dissolved in a solvent using a small amount of material in advance.
It is desirable to determine the relationship between the amount of the solvent and the viscosity of the obtained phosphor layer coating solution. That is, a so-called beaker test is performed in advance, and thereby, the amount of the solvent,
The viscosity of the obtained phosphor layer coating liquid is graphed to show the relationship, and the amount of the solvent, which is determined according to the relationship, and the phosphor layer coating liquid obtained after dispersion and dissolution has a desired viscosity, is used in actual production. The present invention can be embodied by adding to the constituents of the phosphor layer.

Of course, there is no problem even if the amount of the solvent is theoretically determined from the constituent components of the phosphor layer and the specific contents of the solvent. However, by performing the beaker test in advance as described above, it is possible to correct a subtle deviation in viscosity caused by a change in material due to a production lot or the like.

B: Production Method of Radiation Image Conversion Panel The phosphor layer coating solution prepared as described above is uniformly applied to the surface of the support to form the phosphor layer of the radiation image conversion panel ( Phosphor layer forming step).

The support can be arbitrarily selected from those conventionally known as materials for a support of a radiation image storage panel. Among the examples of such materials, a film of a plastic substance such as cellulose acetate, polyester, polyethylene terephthalate, polyethylene naphthalate, polyamide, polyimide, triacetate, and polycarbonate is preferable.

In a known radiation image conversion panel, the phosphor is used to strengthen the bond between the support and the phosphor layer or to improve the sensitivity or image quality (sharpness, granularity) of the radiation image conversion panel. A polymer material such as gelatin is applied to the surface of the support on which the layer is provided to provide an adhesion-imparting layer, or a light-reflective layer made of a light-reflective material such as titanium dioxide, or a light-absorbing material such as carbon black It is known to provide a light absorbing layer or the like made of a conductive material.

The support used in the present invention can also be provided with these various layers, and the structure thereof can be arbitrarily selected according to the desired purpose and use of the radiation image storage panel. Further, JP-A-58-2
As described in Japanese Patent Publication No. 20000, the surface of the support on the stimulable phosphor layer side (adhered to the surface of the support on the stimulable phosphor layer side) is used for the purpose of improving the sharpness of the obtained image. In the case where a property imparting layer, a light reflecting layer, a light absorbing layer, or the like is provided, the surface thereof is meanwhile, fine irregularities may be formed.

After forming a coating on the surface of the support as described above, the coating is dried to complete the formation of the phosphor layer on the surface of the support. The thickness of the phosphor layer varies depending on the characteristics of the intended radiation image conversion panel, the kind of the phosphor, the mixing ratio between the binder and the phosphor, and is usually 20 μm to 1 m.
m. However, this layer thickness is preferably 50 to 500 μm.

The application of the phosphor layer coating solution can be performed by using a usual coating means, for example, a doctor blade, a roll coater, a knife coater or the like. There are no particular restrictions on the drying conditions after coating film formation,
There is no problem as long as the conditions of temperature and time allow the solvent in the coating film to be sufficiently dried.

The phosphor layer does not necessarily need to be formed by directly applying a coating solution on the support as described above.
For example, separately, a phosphor layer is formed by applying a coating solution on a sheet (temporary support) such as a glass plate, a metal plate, and a plastic sheet and drying the coating solution, and then pressing the phosphor layer on the support, Alternatively, the support and the phosphor layer may be joined using an adhesive or the like.

Generally, a protective layer is provided on the phosphor layer in order to physically and chemically protect the phosphor layer. Examples of the material of the protective layer include a polyurethane resin, a polyacryl resin, a cellulose derivative, polymethyl methacrylate, a polyester resin, an epoxy resin, and a fluorine-based resin soluble in an organic solvent. The protective layer is a protective layer forming material coating solution containing the polymer,
The phosphor layer is uniformly applied to the surface of the phosphor layer using a doctor blade or the like, and dried to form a coating. of course,
This protective layer may be formed simultaneously with the formation of the phosphor layer by simultaneous multilayer coating.

The protective layer may be formed of a plastic sheet made of polyethylene terephthalate, polyethylene naphthalate, polyethylene, polyvinylidene chloride, or polyamide; or a protective film forming sheet such as a transparent glass plate. It can also be formed by a method such as bonding to the surface of the body layer using a suitable adhesive.

The radiation image conversion panel may be provided with an edge-adhering layer on at least one end (side surface) of the radiation image conversion panel in order to improve the transport resistance, particularly the shock resistance and the contamination resistance. .

The coating agent for forming the border layer is not particularly limited. For example, a linear polyester or a linear polyester and a vinyl chloride / vinyl acetate copolymer described in JP-A-62-3700 can be used. And an organic solvent-soluble fluororesin described in JP-A-4-2998. Also, Japanese Patent Laid-Open No. 7-14
No. 0300, which includes a silicone-based polymer and a polyisocyanate in detail. A radiation image storage panel having an edge-adhered layer formed with such a coating material has extremely high transport resistance, particularly impact resistance. It is preferable because it can achieve contamination resistance.

The radiation image conversion panel is formed as described above. For the purpose of improving the sharpness of the obtained image, at least one of the above layers may be colored with a coloring agent that absorbs excitation light and does not absorb stimulated emission light. See JP-A-59-23400).

The above-mentioned radiation image conversion panel manufactured by the manufacturing method of the present invention is subjected to a conventionally known radiation image conversion method at a medical site or the like. For radiation image conversion panels that include a neutron converter in the phosphor layer,
As a neutron image forming method, Japanese Patent Application Laid-Open Nos. 61-28899, 8-29901, and the like describe in detail how to use the method.

[0047]

The present invention will be described more specifically below with reference to examples and comparative examples. However, the present invention is not limited by the following examples. Various operations were performed at room temperature (25 ° C.) unless otherwise specified. <Example 1> Formation of undercoat layer A component having the following composition was added to methyl ethyl ketone (MEK) 176.
In addition to 5 g, the mixture was dispersed and mixed to prepare a coating liquid for forming an undercoat layer.

(Composition of Undercoat Layer Forming Coating Solution): Binder: Soft Acrylic Resin (Chris Coat P-1018GS [20 wt% solution], manufactured by Dainippon Ink and Chemicals, Inc.) 1750 g: conductive agent: potassium titanate whisker (Denthol BK200 manufactured by Otsuka Chemical Co., Ltd.) 36 g: curing agent: aliphatic polyisocyanate (Sumitomo Bayern Co., Ltd., Desmodur Z4470 [70% methoxy) Propyl acetate / xylene (1/1) solution] 20 g

The obtained coating solution for forming an undercoat layer was coated to a thickness of 200
μm polyethylene terephthalate (support) surface,
After uniform coating, the coating film was dried to form an undercoat layer on the surface of the support (thickness of the undercoat layer: 12 μm).

Preparation of Coating Solution for Phosphor Layer A component having the following composition was added to methyl ethyl ketone (MEK) 293.
g, and dispersed and mixed with a propeller mixer for 1 hour to prepare a phosphor layer coating solution. The viscosity of the obtained phosphor layer coating solution was 1.3 Pa · s (22 ° C.).

(Composition of phosphor layer coating solution): Phosphor: BaFBr _0.85 I _0.15 : Eu 2 ⁺ ... 1000 g: Neutron converter: Gadolinium oxide... 767 g: Binder: polyurethane (Dainippon) 7.4 g: 13% MEK solution of Pandex T-5265 manufactured by Ink Chemical Industry Co., Ltd .: Yellowing inhibitor: bisphenol A type epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd., Epicoat) 1001)... 15.3 g: Colorant: Gunzei (SM-1 manufactured by Daiichi Kasei Kogyo Co., Ltd.)... 3 g

Formation of Phosphor Layer The above-mentioned phosphor layer coating solution was uniformly applied to the surface of the undercoat layer of the support on which the undercoat layer was formed to form a phosphor layer having a thickness of 140 μm. The surface of the formed phosphor layer was extremely smooth visually.

Formation of Protective Layer Further, an unsaturated polyester resin solution (Toyobo Co., Ltd., Pylon 30SS) was applied and dried to form a 9 μm thick polyethylene provided with an adhesive layer (adhesive application weight 2 g / m ² ). A terephthalate film (hereinafter referred to as “PET film”) and a support provided with the undercoat layer and the phosphor layer are overlapped so that the phosphor layer of the support and the adhesive layer of the PET film are in contact with each other. To form a protective layer. The radiation image conversion panel according to Example 1 was manufactured as described above.

Evaluation of Radiation Image Conversion Panel The following evaluation test was performed on the obtained radiation image conversion panel. The results are summarized in Table 1 below.

A) Emission amount variation evaluation test The obtained radiation image conversion panel was irradiated with 10R of X-rays having a tube voltage of 80 kVp at 100 μm pixels and then irradiated with He-N.
Irradiation with e-laser light (wavelength: 632.8 nm) to excite, stimulated emission light emitted from the phosphor layer is received by a photodetector (photomultiplier tube with spectral sensitivity S-5), and stimulated emission is performed. The amount was measured. At this time, as shown in FIG. 1, the profile data averaged for y = 1 cm (that is, for 100 pixels) in the direction perpendicular to the coating direction of the phosphor layer of the radiation image conversion panel (the coating width direction) is represented by a length. x = 10 cm. The obtained profile data had a shape as shown in FIG. In addition, the wavy unevenness in FIG.
It shows the surface unevenness of the phosphor layer in the comparative example,
In Example 1, it cannot be observed visually.

From the obtained profile data, an average value b, a maximum value max, and a minimum value min of the amount of stimulated emission are obtained.
The absolute light emission amount variation a (max-min) is obtained, and then the ratio (a / b × 100) of this to the average value b of the stimulated light emission amount.
%) Was obtained, and the obtained value was used as the evaluation of the light emission amount variation.

B) Graininess evaluation test The obtained radiation image conversion panel was irradiated with X-rays using a tungsten bulb (tube voltage 80 kVp) (100 m).
R), He-Ne laser light (wavelength = 632.8 nm)
And stimulated emission light generated from the radiation image conversion panel was received by a photodetector (photomultiplier tube having a spectral sensitivity of S-5). The received light was converted into an electric signal to obtain an image.
The value of the graininess (RMS ² ) of the obtained 100 mRσ image was measured. The value of the graininess (RMS ² ) of 100 mR well reflects the structural mottle.

Example 2 A radiation image conversion was performed in the same manner as in Example 1 except that the amount of methyl ethyl ketone (MEK) added in the step of “preparing the coating solution for the phosphor layer” was 223 g. Panels were manufactured. In addition, the viscosity of the phosphor layer coating solution in the present embodiment 2 is 8P
a · s (22 ° C.). When the phosphor layer surface was observed at the stage when the phosphor layer was formed, it was extremely smooth visually as in Example 1. Next, an evaluation test was performed on the obtained radiation image conversion panel in the same manner as in Example 1. The results are summarized in Table 1 below.

Comparative Example 1 A radiation image conversion was performed in the same manner as in Example 1 except that the amount of methyl ethyl ketone (MEK) added in the step of “preparing the phosphor layer coating solution” was 213 g. Panels were manufactured. Note that the viscosity of the phosphor layer coating solution in Comparative Example 1 was 1
1.1 Pa · s (22 ° C.). When the phosphor layer surface was observed at the stage when the phosphor layer was formed, fine irregularities were confirmed visually, and the coating was microscopically applied as shown in FIG. Unevenness was confirmed. Next, an evaluation test was performed on the obtained radiation image conversion panel in the same manner as in Example 1. The results are summarized in Table 1 below.

Comparative Example 2 A radiation image conversion was performed in the same manner as in Example 1 except that the amount of methyl ethyl ketone (MEK) added in the step of “preparing the coating solution for the phosphor layer” was 173 g. Panels were manufactured. The viscosity of the phosphor layer coating solution in Comparative Example 2 was 18
When the phosphor layer surface was observed at the stage when the phosphor layer was formed, fine irregularities were visually confirmed, and microscopically, coating unevenness as shown in FIG. 1 was observed. confirmed. Next, an evaluation test was performed on the obtained radiation image conversion panel in the same manner as in Example 1. The results are summarized in Table 1 below.

Comparative Example 3 To the phosphor layer coating solution having a viscosity of 18 Pa · s (22 ° C.) obtained in the same manner as in Comparative Example 2, 80 g of methyl ethyl ketone (MEK) was further added to adjust the viscosity afterwards. Then, a phosphor layer coating solution in Comparative Example 3 was prepared. The viscosity of the phosphor layer coating solution is 8 Pa
S (22 ° C.)

A radiation image conversion panel was manufactured in the same manner as in Example 1 except that the phosphor layer coating solution in Comparative Example 3 was used as the phosphor layer coating solution. In addition, when the phosphor layer surface was observed at the stage when the phosphor layer was formed, fine irregularities were visually confirmed, and coating unevenness as shown in FIG. 1 was confirmed microscopically. Next, an evaluation test was performed on the obtained radiation image conversion panel in the same manner as in Example 1. The results are summarized in Table 1 below.

[0063]

[Table 1]

As can be seen from Table 1, the radiation image conversion panels according to Examples 1 and 2 manufactured by the manufacturing method of the present invention had little variation in the amount of emitted light and good granularity. That is, when a phosphor layer is formed using a phosphor layer coating solution having an inappropriate viscosity (Comparative Examples 1 and 2),
It can be seen that the variation in the light emission amount is large, the granularity is also reduced, and the viscosity of the phosphor layer coating solution is not improved even after the post-adjustment by adding a solvent (Comparative Example 3).

Example 3 (Actual Production Test) Regarding the addition amount of methyl ethyl ketone (MEK) in the step of “Preparation of a phosphor layer coating solution” in Example 1,
2 and 233 g in addition to the amounts added in Comparative Examples 1-2
And 253 g of a phosphor layer coating solution was prepared (beaker test). Table 2 below summarizes the viscosities of the obtained phosphor layer coating solutions and the viscosities of the phosphor layer coating solutions of Examples 1 and 2 and Comparative Examples 1 and 2.

[0066]

[Table 2]

Further, from Table 2, the relationship between the amount of the solvent (MEK) and the viscosity of the obtained phosphor layer coating solution is shown in FIG.
The graph was made as shown in FIG. From the graph of FIG. 3, it is understood that the appropriate amount of the solvent (MEK) is in the range of 220 to 300 g. In this example, the amount of the solvent (MEK) added was 250 g, and a phosphor layer coating solution was prepared on a 30-fold scale.

In Example 1, the addition amount of methyl ethyl ketone (MEK) in the step of “Preparation of coating solution for phosphor layer” was changed to 7,500 g (250 g × 30), and all other components were changed to 30-fold amount. In the same manner as in Example 1, a phosphor layer coating solution was prepared. The viscosity of the obtained phosphor layer coating solution was 3 Pa · s.

A radiation image conversion panel was manufactured in the same manner as in Example 1 except that the phosphor layer coating solution in Example 3 was used as the phosphor layer coating solution. In addition, when the phosphor layer surface was observed at the stage when the phosphor layer was formed, it was extremely smooth visually as in Example 1.
Next, an evaluation test was performed on the obtained radiation image conversion panel in the same manner as in Example 1. As a result, the variation in the amount of emitted light was less than 3%, and the granularity was 3.5 × 10 ⁻⁵ , which was extremely good.

[0070]

As described above, according to the present invention, it is possible to provide a method of manufacturing a radiation image conversion panel which can provide high quality images with good surface granularity and uniformity. Is particularly suitable for producing a radiation image conversion panel used in a neutron image forming method.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a microscopic state of a phosphor layer surface in an example.

FIG. 2 is a graph showing profile data of the amount of stimulated emission in an example.

FIG. 3 shows a solvent (M) in the beaker test of Example 3.
6 is a graph showing the relationship between the amount of EK) and the viscosity of the obtained phosphor layer coating solution.

Continued on the front page F-term (reference) 2G083 AA03 BB01 CC02 DD06 DD20 EE02 4J038 BA021 BA161 BA181 BA221 CD041 CD061 CD081 CE021 CE071 CF021 CF041 CG141 DB001 DD001 DG001 EA011 HA116 HA216 HA276 JC38 KA06 KA20 KA20

Claims (4)

[Claims] 1. A phosphor layer coating solution preparing step of preparing a phosphor layer coating solution by dispersing and dissolving a phosphor layer constituent component comprising at least a phosphor and a binder in a solvent; A phosphor layer forming step of forming a phosphor layer composed of a phosphor layer coating solution, the method comprising the steps of: A method for producing a radiation image conversion panel, comprising a step of adding a solvent in an amount such that the viscosity of a body layer coating liquid is 1 to 10 Pa · s to a constituent of a phosphor layer and then dispersing and dissolving the same. 2. The method of manufacturing a radiation image storage panel according to claim 1, wherein the phosphor layer further comprises an inorganic powder other than the phosphor. 3. The method of manufacturing a radiation image conversion panel according to claim 2, wherein the inorganic powder is a substance that absorbs neutrons and emits secondary radiation. 4. A phosphor layer constituent component is dispersed and dissolved in a solvent using a small amount of a material, and the relationship between the amount of the solvent and the viscosity of the obtained phosphor layer coating solution is determined in advance. In the phosphor layer coating solution preparation step, the amount of the solvent, which is determined according to the relationship and the viscosity of the phosphor layer coating solution obtained after dispersion and dissolution is 1 to 10 Pa · s, The method for producing a radiation image storage panel according to claim 1, wherein the radiation image storage panel is added.