JP2003270398A - Radiogram conversion panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve brightness of a radiogram conversion panel by taking out accelerated phosphorescence emission more efficiently in order to convert the accelerated phosphorescence emission into light having a longer wavelength. <P>SOLUTION: This radiogram conversion panel is characterized by being formed by laminating a stimulable phosphor layer containing a stimulable phosphor dispersed in a polymer resin and a protective layer on a support in this order, and including a light emitting agent for showing emission having a wavelength not shorter than an accelerated phosphorescence main emission peak wavelength and shorter than an excitation peak wavelength by the accelerated phosphorescence emission in one of the support, the stimulable phosphor layer and the protective layer. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a radiation image conversion panel using a stimulable phosphor, and more particularly to a radiation image conversion panel having excellent brightness.

[0002]

2. Description of the Related Art Radiation images such as X-ray images are widely used in the fields of disease diagnosis and the like. This X-ray image can be obtained by irradiating the phosphor layer (fluorescent screen) with X-rays that have passed through the subject to generate visible light, which is the same as when taking a normal photo. Then, a so-called radiographic method is widely used in which a silver halide photographic light-sensitive material (hereinafter, also simply referred to as a light-sensitive material) is irradiated and then developed to obtain a visible silver image.

However, in recent years, a new method of directly taking out an image from a phosphor layer has been proposed instead of an image forming method using a light-sensitive material having a silver halide salt.

As this method, the radiation that has passed through the subject is absorbed by the phosphor, and then the phosphor is excited by, for example, light or thermal energy, so that the radiation energy accumulated by the phosphor is absorbed. Then, there is a method of detecting this fluorescence and imaging it.

Specifically, for example, US Pat. No. 3,85
A radiation image conversion method using a stimulable phosphor as described in JP-A No. 9,527 and JP-A No. 55-12144 is known.

This method uses a radiation image conversion panel containing a stimulable phosphor, and the radiation transmitted through the object is applied to the stimulable phosphor layer of the radiation image conversion panel to apply the radiation to each part of the object. Accumulates radiation energy corresponding to the radiation transmission density, and then accumulates in the stimulable phosphor by time-sequentially exciting the stimulable phosphor with electromagnetic waves (excitation light) such as visible light and infrared rays. The emitted radiation energy is emitted as stimulated emission, and the signal due to the intensity of this light is photoelectrically converted to obtain an electric signal, and this signal is recorded, such as a recording material such as a silver halide photographic light-sensitive material, a CRT, etc. Is reproduced as a visible image on the display device.

According to the above-mentioned method of reproducing a radiographic image, a radiographic image having a large amount of information can be obtained with a much smaller exposure dose as compared with the conventional radiographic method using a combination of a radiographic film and an intensifying screen. It has the advantage of being able to.

As described above, the photostimulable phosphor is a phosphor that exhibits stimulated emission when irradiated with excitation light after being irradiated with radiation, but in practice, the excitation is in the wavelength range of 600 to 800 nm. A phosphor that emits stimulated emission in the wavelength range of 300 to 500 nm by light is generally used.

A radiation image conversion panel using these stimulable phosphors releases radiation energy by scanning excitation light after storing radiation image information. Therefore, radiation images can be stored again after scanning. It can be used repeatedly. In other words, in the conventional radiographic method, the radiographic film is consumed for each photographing, whereas in the radiographic image conversion method, the radiographic image conversion panel is repeatedly used. It is advantageous.

The radiation image conversion system using the radiation image conversion panel is a very advantageous image forming method as described above, but the radiation image conversion panel used in this method is naturally high in sensitivity and has a high image quality (sharpness, sharpness, It is desired to provide an image with good graininess).

As a technique for improving the sensitivity of the radiation image conversion panel, a light reflection layer is provided on the support by coating a support with a coating solution in which a white pigment is dispersed / contained in a suitable binder. It is known to provide a stimulable phosphor layer on it. A radiation image conversion panel provided with a light reflecting layer containing this white pigment is disclosed in JP-A-56-12600, and titanium dioxide, lead white, zinc sulfide, aluminum oxide, and Magnesium oxide is exemplified.

[0012]

By the way, since the above-mentioned white pigment has a remarkably low reflectance in the near ultraviolet region,
Depending on the photostimulable phosphor used, the light reflection properties of this light reflection layer cannot be said to be sufficiently high, and therefore the improvement of the sensitivity of the radiation image conversion panel is not always achieved by providing the light reflection layer made of this white pigment. I could not say that it was a satisfactory level.

Japanese Examined Patent Publication (Kokoku) No. 3-7280 solves such a problem and provides a radiation image conversion panel having a light reflection layer made of a white pigment having excellent light reflection characteristics, with a support. A technique using an alkaline earth metal fluoride halide represented by a specific composition formula as a white pigment in a light reflection layer provided between the photostimulable phosphor layer and the light reflection layer is described. It is said to have improved characteristics, sensitivity, and sharpness.

However, this light reflecting layer is provided below the stimulable phosphor layer, and the reflection of the stimulable fluorescence hardly reaches the surface of the radiation image conversion panel (reading side of the stimulable fluorescence), so that the brightness is not improved. The problem of being sufficient is clarified, and there is a demand for urgent development of improvement measures.

The present invention has been made in view of the above circumstances, and an object thereof is to convert stimulated emission into light of a longer wavelength, so that the stimulated emission is more efficiently extracted and the brightness of the radiation image conversion panel is increased. To improve.

[0016]

The above object of the present invention can be achieved by the following.

1. On a support, a stimulable phosphor layer containing a stimulable phosphor dispersed in a polymer resin and a protective layer are laminated in this order, the support, the stimulable phosphor layer,
And a luminescent agent which emits light having a stimulated main emission peak wavelength or more and less than an excitation peak wavelength by stimulated emission in any one of the protective layers.

2. An undercoat layer, a stimulable phosphor layer containing a stimulable phosphor dispersed in a polymer resin, and a protective layer are laminated in this order on a support, and the support, the undercoat layer, and the A radiation image conversion panel, characterized in that either the stimulable phosphor layer or the protective layer contains a luminescent agent that emits light of a stimulated main emission peak wavelength or more and less than an excitation peak wavelength by stimulated emission.

3. 3. The radiation image conversion panel as described in 1 or 2 above, wherein the support is polyethylene terephthalate having bubbles.

4. The radiation image conversion panel according to any one of the above 1 to 3, wherein the stimulable phosphor layer contains a stimulable phosphor represented by the following general formula (1).

General Formula (1) BaFI: Eu ^{2+ The} present invention is described in detail below.

According to the present invention, any one of the support, the stimulable phosphor layer, the protective layer and, in some cases, the undercoat layer of the radiation image conversion panel can be provided with "excited main emission peak wavelength or more and excitation peak wavelength due to stimulated emission. It is intended to realize the improvement of the brightness of the obtained radiation image conversion panel by containing the “luminescent agent exhibiting less than the luminescence”.

First, a luminescent agent (also simply referred to as a luminescent agent) that emits light having a stimulated emission peak wavelength longer than the stimulated emission peak wavelength and shorter than the excitation peak wavelength will be described.

This luminescent agent may be contained in any one of the support, the stimulable phosphor layer, the protective layer, and the undercoat layer which constitute the radiation image conversion panel.

As the luminescent agent used in the present invention, one having a property of absorbing blue light and emitting blue-violet light having a longer wavelength than that is used.

The expression "indicates emission above the peak wavelength of the main stimulus emission peak and below the excitation peak wavelength" is used especially when the emission of the luminescent agent is in the near-ultraviolet region to visible region (wavelength region longer than 320 nm). It means that it is carried out between the peak wavelength of the stimulated emission spectrum of the stimulable phosphor and the peak wavelength of the stimulated excitation spectrum.
It absorbs light of 80 nm, and the visible part (400-450n
It means to emit light in m).

A large number of these luminescent agents have been developed for paper and fibers, and structurally, most of them are diaminostilbene type which occupies most of cellulose fiber (direct dye type), imidazole type, coumarin type, Examples include naphthalimide type. For example, C.I. I. Fluorescent
Brighttener (fluorescent brightener) 162 (C ₁₄ H ₁₁ NO ₃ ) is a naphthalimide type,
It is processed in the same manner as the disperse dye.

Examples of commercially available products include the following, but the present invention is not limited thereto.

Whitex (Sumitomo Chemical), Kayaph
or (Nippon Kayaku), Mikephor (Mitsui BAS
F), Hakkol (Showa Kagaku), Illuminar
(Showa Kako), Kaycoll (Nippon Soda), Nikk
abright (Nippon Kagaku), Blankophor
(Bayer), Uvitex (Ciba), Host
alux (Clariant) and the like.

The introduction of the luminescent agent into the respective constituents such as the support, the stimulable phosphor layer, the protective layer or the undercoat layer can be achieved by directly adding it to each constituent material. For example, in the case of polyethylene terephthalate as a support, it may be added to a melted PET resin to form a stretched film, and in the case of an undercoat layer or a phosphor layer, it may be added to a layer coating solution and coated and dried. Good. When the protective layer is a film, it can be produced by the same method as for the support, and when it is a coating type, it can be added by undercoating or the same method as for the phosphor layer.

With respect to the support, it is also possible to select from the commercially available products that are previously formed by containing the luminescent agent. Examples of the PET film containing a luminescent agent that can be used in the present invention include E60L series (bubble-containing type) and E20 series (titanium oxide-containing type) manufactured by Toray Industries, Inc.

By adding the above-mentioned luminescent agent, stimulated luminescence is converted into light of longer wavelength, so that luminescence can be taken out more efficiently and the brightness can be improved.

Next, the stimulable phosphor layer (particularly the coating type phosphor layer) will be described. The coating type phosphor layer is mainly composed of phosphor particles and a polymer resin, and is formed by coating on a support using a coater.

As the photostimulable phosphor that can be used in the coating type phosphor layer, a phosphor that exhibits stimulated emission in the wavelength range of 300 to 500 nm by excitation light in the wavelength range of 400 to 900 nm is generally used. Is used for.

Examples of the phosphors that can be preferably used in the coating type phosphor layer according to the present invention will be given below, but the present invention is not limited thereto.

(1) (Ba _1-X , M (II) _X ) FX: yA described in JP-A-55-12145 (wherein
M (II) is at least one of Mg, Ca, Sr, Zn and Cd, X is at least one of Cl, Br and I, A is Eu, Tb, Ce, Tm, Dy, Pr, H
at least one of o, Nd, Yb, and Er, and 0 ≦ x ≦ 0.6, and y is 0 ≦ y ≦ 0.2). An earth metal fluorohalide phosphor; the phosphor may contain the following additives.

A) X ', BeX ", M (III) X'" ₃ , described in JP-A-56-74175, wherein:
X ', X ", and X'" are at least one of Cl, Br, and I, respectively, and M (III) is a trivalent metal. B) Be described in JP-A-55-160078.
O, MgO, CaO, SrO, BaO, ZnO, Al ₂
O ₃ , Y ₂ O ₃ , La ₂ O ₃ , In ₂ O ₃ , SiO ₂ , Ti
O ₂ , ZrO ₂ , GeO ₂ , SnO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅
And metal oxides such as ThO ₂ c) Z described in JP-A-56-116777.
r, Sc d) Be described in JP-A-57-23673, As) described in JP-A-57-23675,
Sif) M. described in JP-A-58-206678
L, in the formula, M is at least one alkali metal selected from the group consisting of Li, Na, K, Rb, and Cs, and L is Sc, Y, La, Ce, Pr, Nd, Pm, S.
m, Gd, Tb, Dy, Ho, Er, Tm, Yb, L
g) at least one trivalent metal selected from the group consisting of u, Al, Ga, In, and Tl) A baked product of a tetrafluoroboric acid compound described in JP-A-59-27980; 59-2728
Hexafluorosilicic acid, hexafluorotitanic acid and hexafluorozirconic acid salts of monovalent or divalent metals described in No. 9; JP-A-59-564
NaX 'described in No. 79, wherein X'is Cl,
At least one of Br and I h) V and C described in JP-A-59-56480
Transition metals such as r, Mn, Fe, Co and Ni; M (I) X 'described in JP-A-59-75200.
M '(II) X " ₂ , M (III) X'" ₃ , A, in the formula, M
(I) is at least one alkali metal selected from the group consisting of Li, Na, K, Rb, and Cs, and M ′
(II) represents at least one divalent metal selected from the group consisting of Be and Mg, and M (III) represents Al, Ga, I
n is at least one trivalent metal selected from the group consisting of Tl, A is a metal oxide, X ', X ",
And X '"are at least one halogen selected from the group consisting of F, Cl, Br and I i) M described in JP-A-60-101173
(I) X ′, in which M (I) is at least one alkali metal selected from the group consisting of Rb and Cs,
X'is at least one halogen selected from the group consisting of F, Cl, Br and I. j) M (I) described in JP-A No. 61-23679.
I) ′ X ′ ₂ · M (II) ′ X ″ ₂ , where M (II) ′ is B
at least one alkaline earth metal selected from the group consisting of a, Sr and Ca; X ′ and X ″ are at least one halogen selected from the group consisting of Cl, Br and I, and X ′. ≠ X ″; Furthermore,
LnX ″ described in JP-A-61-264084
₃ , where Ln is Sc, Y, La, Ce, Pr, Nd,
Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Y
It is at least one rare earth element selected from the group consisting of b and Lu; X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I.

(2) M (II) X ₂ .aM (II) X ' ₂ : xEu ^{2+ described in} JP-A-60-84381 (wherein M (II) is Ba, Sr and Ca) At least one alkaline earth metal selected from the group consisting of; X and X'wherein at least one halogen selected from the group consisting of Cl, Br and I, and X ≠ X '; and a Is 0.1 ≦ a ≦ 10.0, and x is 0 <x ≦ 0.2), and the divalent europium-activated alkaline earth metal halide phosphor is represented by the composition formula; The following additives may be included.

A) M (I) X 'described in JP-A-60-166379, wherein M (I) is Rb and Cs.
Is at least one alkali metal selected from the group consisting of; X'is at least one halogen selected from the group consisting of F, Cl, Br and I. b) Described in JP-A-60-221483. K
X ″, MgX ″ ″ ₂ , M (III) X ″ ″ ₃ , where M (II
I) is at least one trivalent metal selected from the group consisting of Sc, Y, La, Gd and Lu; X ″, X ′ ″
And X "" are both at least one halogen selected from the group consisting of F, Cl, Br and I. c) B described in JP-A-60-228592,
Si described in JP-A-60-228593
O _2, P ₂ O ₅ oxide such, LiX listed in JP 61-120882 ", NaX", in the formulas, X "at least selected from the group consisting of F, Cl, Br and I D) a kind of halogen Si described in JP-A-61-120883
O: Sn described in JP-A-61-120885
X ″ ₂ , where X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I. e) Cs described in JP-A-61-235486
X ″, SnX ″ ″ ₂ , where X ″ and X ″ ″ are at least one halogen selected from the group consisting of F, Cl, Br and I; and JP-A-61-2354.
CsX ″, Ln ³⁺ , in the formula, X ″
Is at least one halogen selected from the group consisting of F, Cl, Br and I; Ln is Sc, Y, Ce, P
r, Nd, Sm, Gd, Tb, Dy, Ho, Er, T
It is at least one rare earth element selected from the group consisting of m, Yb, and Lu.

(3) LnOX: xA described in JP-A-55-12144 (wherein Ln is La, Y, G
at least one of d and Lu; X is Cl, Br,
And at least one of I; A is at least one of Ce and Tb; and x is 0 <x <0.1), which is a rare earth element-activated rare earth oxyhalide phosphor.

(4) M (II) OX: xCe described in JP-A-58-69281 (wherein M (II) is P
r, Nd, Pm, Sm, Eu, Tb, Dy, Ho, E
at least one metal oxide selected from the group consisting of r, Tm, Yb, and Bi; X is Cl, Br, and I
At least one of the above; x is 0 <x <0.1), and a cerium-activated trivalent metal oxyhalide phosphor represented by a composition formula.

(5) M (I) X: xBi described in JP-A-62-25189 (wherein M (I) is at least one alkali metal selected from the group consisting of Rb and Cs). X is at least one halogen selected from the group consisting of Cl, Br and I; and x is 0
<A bismuth-activated alkali metal halide phosphor represented by a composition formula of <x ≦ 0.2).

(6) M (II) ₅ (PO ₄ ) ₃ X: xEu ²⁺ described in JP-A-60-141783 (wherein
M (II) is at least one alkaline earth metal selected from the group consisting of Ca, Sr and Ba; X is F, C
a divalent europium-activated alkaline earth metal haloline represented by the composition formula: at least one halogen selected from the group consisting of 1, Br and I; x is a numerical value in the range of 0 <x ≦ 0.2. Phosphate phosphor.

(7) M (II) ₂ BO ₃ X: xEu ²⁺ described in JP-A-60-157099 (where M (I
I) is at least one alkaline earth metal selected from the group consisting of Ca, Sr and Ba; X is Cl, Br
And at least one halogen selected from the group consisting of I and I; x is a numerical value in the range of 0 <x ≦ 0.2), a divalent europium-activated alkaline earth metal haloborate fluorescent compound represented by the composition formula body.

(8) M (II) ₂ (PO ₄ ) ₃ X: xEu ²⁺ described in JP-A-60-157100 (wherein
M (II) is at least one alkaline earth metal selected from the group consisting of Ca, Sr and Ba; X is Cl,
A divalent europium-activated alkaline earth metal halophosphate represented by the composition formula: at least one halogen selected from the group consisting of Br and I; x is a numerical value in the range of 0 <x ≦ 0.2. Phosphor.

(9) M (II) HX: xEu ²⁺ described in JP-A-60-217354 (wherein M (II) is at least one selected from the group consisting of Ca, Sr and Ba) Is an alkaline earth metal; X is Cl, Br and I
A divalent europium-activated alkaline earth metal hydrohalide phosphor represented by the composition formula: at least one halogen selected from the group consisting of: x is a numerical value in the range of 0 <x ≦ 0.2. .

(10) LnX ₃ .aLn'X ' ₃ : xCe ³⁺ described in JP-A-61-21173 (wherein Ln and Ln' are Y, La, Gd and Lu, respectively).
At least one rare earth element selected from the group consisting of; X and X'each being at least one halogen selected from the group consisting of F, Cl, Br and I, and X ≠ X '; and a is 0.1 <a ≦ 1
A cerium-activated rare earth compound halide phosphor represented by the composition formula: 0.0 is a numerical value in the range of 0.0, and x is a numerical value in the range of 0 <x ≦ 0.2.

[0048] (11) LnX ₃ · aM that are described in ^{JP-A-61-21182 (I) X'3: xCe 3+} ,
(In the formula, Ln is at least one rare earth element selected from the group consisting of Y, La, Gd, and Lu; M (I)
Is at least one alkali metal selected from the group consisting of Li, Na, K, Cs and Rb; X and X'are at least one halogen selected from the group consisting of Cl, Br and I; and a Is 0 <a ≦ 1
A cerium-activated rare earth compound halide phosphor having a compositional formula of 0.0 and a value of 0 <x ≦ 0.2.

(12) LnPO ₄ .aLnX ₃ : xCe ³⁺ , described in JP-A-6140390 (wherein
Ln is at least one rare earth element selected from the group consisting of Y, La, Gd and Lu; X is F, Cl, B
at least one halogen selected from the group consisting of r and I; and a is a numerical value in the range of 0.1 ≦ a ≦ 10.0 and x is a numerical value in the range of 0 <x ≦ 0.2. )
A cerium-activated rare earth halophosphate phosphor represented by the following composition formula.

(13) CsX: aRbX ': xEu ²⁺ , which is described in JP-A-61-2336888 (wherein
X and X ′ are at least one halogen selected from the group consisting of Cl, Br and I respectively; and a is a numerical value in the range of 0 <a ≦ 10.0 and x is 0 <x ≦.
A divalent europium-activated cesium-rubidium halide phosphor represented by the composition formula (a numerical value in the range of 0.2).

(14) M (II) X ₂ · aM (I) X ′: xE described in JP-A-61-2336890.
u ²⁺ , (wherein M (II) is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca; M (I) is selected from the group consisting of Li, Rb and Cs At least one alkali metal; X and X '
Each is at least one halogen selected from the group consisting of Cl, Br and I; and a is 0.1 ≦ a
A divalent europium-activated composite halide phosphor represented by the composition formula: ≦ 20.0, where x is 0 <x ≦ 0.2.

Among the above stimulable phosphors, it is preferable that the stimulable phosphor particles contain iodine.
Divalent europium-activated alkaline earth metal fluoride halide phosphor containing iodine, divalent europium-activated alkaline earth metal halide phosphor containing iodine, rare earth element activated rare earth oxyhalide system containing iodine Phosphors and bismuth-activated alkali metal halide phosphors containing iodine are preferable because they exhibit stimulated luminescence with high brightness, and stimulable phosphors are particularly preferred as stimulable phosphors represented by the general formula (1). BaFI: Eu ²⁺ which is a phosphor
It is preferably a compound.

In the present invention, examples of the binder used in the phosphor layer include proteins such as gelatin, polysaccharides such as dextran, and natural polymer substances such as gum arabic; and polyvinyl butyral and 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, and linear polyester. Is preferably a resin whose main component is a thermoplastic elastomer, and examples of the thermoplastic elastomer include, for example, the above-mentioned polystyrene-based thermoplastic elastomer, polyolefin-based thermoplastic elastomer, polyurethane-based thermoplastic elastomer, polyester-based thermoplastic elastomer, and polyamide-based thermoplastic elastomer. Thermoplastic elastomer, polybutadiene-based thermoplastic elastomer, ethylene vinyl acetate-based thermoplastic elastomer, polyvinyl chloride-based thermoplastic elastomer, natural rubber-based thermoplastic elastomer, fluororubber-based thermoplastic elastomer Plastic elastomers, polyisoprene thermoplastic elastomer, a chlorinated polyethylene-based thermoplastic elastomer, a styrene - butadiene rubber and silicone rubber type thermoplastic elastomers, and the like. Among them, the polyurethane-based thermoplastic elastomer and the polyester-based thermoplastic elastomer have good dispersibility because they have a strong binding force with the phosphor, and also have excellent ductility, and have good flexibility to the radiation image conversion panel. It is preferable because Incidentally, these binders may be crosslinked with a crosslinking agent.

The mixing ratio of the binder and the stimulable phosphor in the coating solution varies depending on the set value of the haze ratio of the intended radiation image conversion panel, but is preferably 1 to 20 parts by mass with respect to the phosphor, and Is more preferably 2 to 10 parts by mass.

The organic solvent used for preparing the coating liquid for the stimulable phosphor layer is, for example, methanol, ethanol,
Lower alcohols such as isopropanol and n-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, ketones such as cyclohexanone, esters of lower fatty acids and lower alcohols such as methyl acetate, ethyl acetate and n-butyl acetate, dioxane, ethylene glycol monoethyl Examples thereof include ethers, ethers such as ethylene glycol monomethyl ether, aromatic compounds such as triols and xylols, halogenated hydrocarbons such as methylene chloride and ethylene chloride, 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 are 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. And a glycolic acid ester such as; and a polyester of triethylene glycol and adipic acid, a polyester of polyethylene glycol and an aliphatic dibasic acid such as a polyester of diethylene glycol and succinic acid, and the like. Further, a dispersant such as stearic acid, phthalic acid, caproic acid, or a lipophilic surfactant is mixed in the coating liquid for the stimulable phosphor layer for the purpose of improving the dispersibility of the stimulable phosphor particles. Good.

Preparation of the stimulable phosphor layer coating solution is carried out, for example, by
Ball mill, bead mill, sand mill, attritor,
It is carried out using a dispersing device such as a three-roll mill, a high-speed impeller disperser, a Kady mill, or an ultrasonic disperser.

A coating film is formed by uniformly coating the coating liquid prepared as described above on the surface of the support described later. As a coating method that can be used, an ordinary coating means such as a doctor blade, a roll coater, a knife coater, a comma coater, or a lip coater can be used.

The coating film formed by the above means is then heated and dried to complete the formation of the stimulable phosphor layer on the support. The film thickness of the stimulable phosphor layer varies depending on the characteristics of the intended radiation image conversion panel, the type of the stimulable phosphor, the mixing ratio of the binder and the phosphor, etc., but is usually 1
0 to 1000 μm, more preferably 10 to 500
μm.

As the protective layer provided on the radiation image conversion panel of the present invention, a polyester film and a polymethacrylate having an excitation light absorption layer having a haze ratio of 5% or more and less than 60% as measured by the method described in ASTM D-1003. A film, a nitrocellulose film, a cellulose acetate film or the like can be used, but a stretched film such as a polyethylene terephthalate film or a polyethylene naphthalate film is preferable as the protective layer in terms of transparency and strength, and further, these From the viewpoint of moisture resistance, a polyethylene terephthalate film or a vapor-deposited film obtained by vapor-depositing a thin film of a metal oxide, silicon nitride or the like on a polyethylene terephthalate film is more preferable.

The haze ratio of the film used in the protective layer (hereinafter, also referred to as a protective film) can be easily adjusted by selecting the haze ratio of the resin film used, and a resin film having an arbitrary haze ratio is industrially available. Can be easily obtained. As a protective film for a radiation image conversion panel, one having a very high optical transparency is supposed. As such a highly transparent protective film material, various plastic films having a haze value in the range of 2 to 3% are commercially available. A preferable haze ratio for obtaining the effect of the present invention is 5% or more and less than 60%, and more preferably 10% or more and less than 50%. When the haze ratio is less than 5%, the effect of eliminating image unevenness and linear noise is low, and when it is 60% or more, the effect of improving sharpness is impaired, which is not preferable.

The protective film can be made to have an optimum moisture-proof property by laminating a plurality of resin films or vapor-deposited films obtained by vapor-depositing a metal oxide on the resin film, if necessary, and the moisture absorption of the photostimulable phosphor can be achieved. Considering prevention of deterioration, the water vapor permeability is preferably at least 5.0 g / m ² · day or less. The method for laminating the resin film is not particularly limited, and any known method may be used.

Further, by providing the excitation light absorption layer between the laminated resin films, the excitation light absorption layer is protected from physical impact and chemical alteration, and stable plate performance can be maintained for a long time, which is preferable. The excitation light absorption layer may be provided at a plurality of positions, or the adhesive layer for laminating may contain a coloring material to form the excitation light absorption layer.

The protective film may be adhered to the stimulable phosphor layer via an adhesive layer, but the structure is provided so as to cover the phosphor surface (hereinafter, also referred to as sealing or sealing structure). Is more preferable. In sealing the phosphor plate, any known method may be used, but the outermost resin layer on the side in contact with the phosphor sheet of the moisture-proof protective film is a resin film having heat-sealing property, and it is moisture-proof. This is one of the preferable modes in that the property protection film can be fused and the work of sealing the phosphor sheet can be made efficient. Furthermore, the moisture-proof protective film is arranged on the upper and lower sides of the phosphor sheet, and the peripheral edge thereof is an area outside the peripheral edge of the phosphor sheet, and the upper and lower moisture-proof protective films are heated and fused by an impulse sealer or the like. The sealing structure is preferable because moisture can be prevented from entering from the outer peripheral portion of the phosphor sheet. or,
Furthermore, the moisture-proof protective film on the side of the support is a laminated moisture-proof film formed by laminating one or more aluminum films, whereby moisture ingress can be reduced more reliably, and this sealing method is work-friendly. Is also easy and preferable. In the method of heat fusion with the impulse sealer, heat fusion in a reduced pressure environment is more preferable in terms of preventing displacement of the phosphor sheet in the moisture-proof protective film and eliminating moisture in the atmosphere.

The resin layer, which is the outermost layer having the heat-fusible property, on the side of the moisture-proof protective film that comes into contact with the phosphor surface and the phosphor surface may or may not be adhered. The term "non-adhesive" as used herein means that, even if the phosphor surface is microscopically in point contact with the moisture-proof protective film, the phosphor surface and the moisture-proof protective film are almost discontinuous optically and mechanically. It is a state that can be treated as a body. Further, the above-mentioned resin film having heat-fusible property is a resin film that can be fused by a commonly used impulse sealer, and includes, for example, ethylene vinyl acetate copolymer (EVA), polypropylene (PP) film, polyethylene ( PE) film and the like can be mentioned, but the present invention is not limited thereto.

As the support used in the radiation image conversion panel of the present invention, various polymer materials are used. In particular, a material that can be processed into a flexible sheet or web for handling as an information recording material is preferable, and from this point, a cellulose acetate film, a polyester film, a polyethylene terephthalate film, a polyethylene naphthalate film, a polyamide film, a polyimide. Plastic films such as films, triacetate films and polycarbonate films are preferred.

The layer thickness of these supports varies depending on the material of the support used and the like, but is generally 80 to 1000 μm.
m, more preferably 80 to 80 from the viewpoint of handling.
It is 500 μm. 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.

From the viewpoint of improving the brightness of the radiation image conversion panel by raising the reflectivity of the support, polyethylene terephthalate containing bubbles is preferably used as the support according to the present invention.

Polyethylene terephthalate containing the above-mentioned bubbles is disclosed in JP-A-3-76727 and JP-A-6-2.
By the method described in No. 26894, it is possible to produce a support in which bubbles are contained in polyethylene terephthalate to enhance the reflectivity for stimulated fluorescence and the brightness of the radiation image conversion panel is improved. As a commercially available product, E60 manufactured by Toray Industries, Inc.
There is polyethylene terephthalate containing bubbles such as L.

The thickness of the polyethylene terephthalate support containing the bubbles is generally 80 to 1000 μm.
m, and preferably 50 to 50 from the viewpoint of handling.
It is 0 μm.

The surface of these supports may be a smooth surface, or may be a matte surface for the purpose of improving the adhesion to the reflective layer, the light absorbing layer and the stimulable phosphor layer.

Further, these supports may be provided with an undercoat layer on the surface on which the stimulable phosphor layer is provided for the purpose of improving the adhesion with the stimulable phosphor layer.

The undercoat layer mainly contains a polymer resin which can be crosslinked with a crosslinking agent and a crosslinking agent.

The polymer resin contained 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. Coalesce, vinyl chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivative (nitrocellulose etc.),
Examples thereof include styrene-butadiene copolymers, various synthetic rubber resins, phenol resins, epoxy resins, urea resins, melamine resins, phenoxy resins, silicone resins, acrylic resins, urea formamide resins and the like. Among them, polyurethane, polyester, vinyl chloride copolymer, polyvinyl butyral, nitrocellulose and the like can be mentioned, and their average glass transition temperature (Tg) is 25 ° C.
It is preferable that the above is more preferable, and Tg of 25 to 200 ° C.
It is preferable to have

The crosslinking agent contained in the undercoat layer is not particularly limited, and examples thereof include polyfunctional isocyanate and its derivative, melamine and its derivative, amino resin and its derivative, and the like. It is particularly preferable to use a polyfunctional isocyanate compound, and examples thereof include Coronate HX and Coronate 3041 manufactured by Nippon Polyurethane Co., Ltd.

The undercoat layer can be formed on the support by the following method, for example. First, the above-mentioned polymer resin and cross-linking agent are added to an appropriate solvent, for example, the solvent used in the preparation of the phosphor layer coating solution, and this is mixed sufficiently to prepare an undercoat layer coating solution.

The amount of the crosslinking agent used varies depending on the characteristics of the intended radiation image conversion panel, the type of material used for the phosphor layer and the support, the type of polymer resin used for the undercoat layer, etc. Considering the maintenance of the adhesive strength with respect to the support, it is preferably added at a ratio of 50% by mass or less, and particularly preferably 15 to 50% by mass with respect to the polymer resin.

The thickness of the undercoat layer varies depending on the characteristics of the intended radiation image conversion panel, the types of materials used for the phosphor layer and the support, the types of polymer resin and crosslinking agent used for the undercoat layer, and the like. Generally, it is preferably 3 to 50 μm, and particularly preferably 5 to 40 μm.

After coating the undercoat layer on the support and before coating the stimulable phosphor layer, in order to further complete the reaction between the polymer resin contained in the undercoat layer and the crosslinking agent, 40 ~ 15
It is preferable to perform heat treatment at 0 ° C. for 2 to 100 hours.
The heat treatment method is not particularly limited, and any method may be used as long as the prepared sheet-shaped, roll-shaped, etc. undercoat layer coated sample can be completely stored, and the temperature and humidity can be controlled. Is also good. The heat treatment condition is 40 to 15
It may be 2 to 100 hours at 0 ° C, preferably 55 to
100 ° C., 5 to 50 hours.

After the undercoat layer is formed on the support, a protective sheet is inserted between the laminated samples when the heat treatment is carried out in a roll-laminated form or a sheet-laminated form. After removing the protective sheet after the heat treatment, it is preferable to apply the phosphor layer. By adopting this method,
It is preferable since blocking between the undercoat layer and the back surface of the support during the heat treatment can be effectively prevented.

The protective sheet that can be used in the present invention is not particularly limited in the material to be used, it can prevent adhesion or fusion, and the adhesion between the protective sheet and the undercoat layer or the back surface of the support is extremely weak. It is sufficient that various resin films used as the above-mentioned protective film are appropriately selected and used. Further, it is preferable that a release agent is applied to the protective sheet in order to facilitate peeling after the heat treatment.

In the present invention, the above-mentioned cross-linking agent can be used in other layers without being limited to the undercoat layer.

In the present invention, the polymer resin and the cross-linking agent are added to a suitable solvent, for example, the solvent used in the preparation of the coating liquid for the stimulable phosphor layer, and this is mixed sufficiently to prepare a coating liquid.

The amount of the crosslinking agent used varies 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 for the undercoat layer, etc. Considering the maintenance of the adhesive strength of the stimulable phosphor layer to the support, 50% by mass relative to the polymer resin
It is preferable to add it in the following ratio, particularly 15 to 50
It is preferably mass%.

In the present invention, it is preferable to perform the compression process at the stage when the phosphor sheet is obtained. The compression treatment means that a stimulable phosphor layer coating liquid is applied on a support or a support provided with an undercoat layer, and dried under desired conditions to form a stimulable phosphor layer to form a fluorescent substance. After forming a body sheet, for example, usually a diameter of 1-100
cm nip roller having a high smoothness and a heatable roller facing the nip roller are subjected to temperature and pressure treatment. By performing this compression treatment, the first effect is that the filling rate of the stimulable phosphor in the stimulable phosphor layer can be improved, and high emission brightness and sharpness can be achieved. As an effect of the above, by setting the pressurization and heating conditions to specific conditions, it is possible to obtain high uniformity of the phosphor sheet during the compression treatment.

The compression method using a calendar roll is not particularly limited, but it is described in, for example, “Handbook of Resin Processing Technology (Polymer Society of Japan): Nikkan Kogyo Shimbun, June 12, 1965”. It can be applied with reference to the method described.

FIG. 1 shows an example of an embodiment of compression processing. In FIG. 1, first, from the supply roll 6, the conveyance direction D
After coating the stimulable phosphor layer coating liquid with the coater 4 on the support 7 fed in the direction of, the solution is introduced into the drying zone 8,
Hot air is blown from the nozzles arranged above and below to dry. Next, the dried support 7 (or the phosphor sheet) coated with the stimulable phosphor layer is subjected to a calendar roll 9-1.
Compression processing is performed using the combinations of 9-3 and wound on the winding roll 10. As the constitution of the calender rolls, it is preferable that the calender rolls 9-1 and 9-3 are heat rolls, and the calender roll 9-2 is a compliant roll made of resin.

The calender roll is not particularly limited in its structure or kind of resin, but for example, a high-rigidity base body using an iron material as an inner core and its outer peripheral surface are made of, for example, an outer cylinder made of a hard resin. Examples of the roller coated with are: Ellagras (manufactured by Kinyo Metal Co., Ltd.), Mirrortex roll (manufactured by Yamauchi Rubber Co., Ltd.) and the like.

In the present invention, the compression treatment by the calender roll is performed in a linear force of 500 N / cm to 5 kN / cm.
(50 to 500 kg / cm) is preferable, and particularly preferably, the linear force is 1 to 4 kN / cm. By performing the compression condition in the range defined above, the filling rate and smoothness of the stimulable phosphor layer are improved, and as a result, the image unevenness of the stimulable phosphor is reduced, and good sharpness is obtained. Can be obtained. In particular, under the above conditions, the compressibility of the phosphor layer in the vicinity of the support is increased, which makes
The effect can be exhibited in the method of irradiating the stimulable phosphor layer with X-rays from the support side of the radiation image conversion panel.

Under the above conditions, the linear pressure is 500 N /
Sufficient compressibility and smoothness cannot be obtained at a temperature of less than 10 cm or less than the Tg of the polymer resin, and stimulable phosphor particles are destroyed at a temperature of 5 kN / cm or more and the softening point of the support or more. ,
It is not preferable because it may deform the support.

[0092]

EXAMPLES The present invention will be specifically described with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1 << Preparation of Radiation Image Conversion Panel >> (Preparation of Phosphor) In order to synthesize a europium-activated barium fluoroiodide stimulable phosphor precursor, a BaI ₂ aqueous solution (3.6 mol / L) was prepared. ) 2780 ml and EuI ₃ aqueous solution (0.15 mol / L) 27 ml were placed in the reactor. The reaction mother liquor in this reactor was kept warm at 83 ° C. with stirring. Next, ammonium fluoride aqueous solution (8 mol / L)
322 ml was poured into the reaction mother liquor using a roller pump to form a precipitate. Keep warm and stir 2 after injection
The precipitate was aged for a period of time. Next, the precipitate was separated by filtration, washed with ethanol, and then dried in vacuum to obtain europium-activated barium fluoroiodide crystals. In order to prevent changes in particle shape due to sintering during firing, and changes in particle size distribution due to fusion between particles, 0.2% by mass of ultrafine alumina powder was added, and the surface of the crystal was thoroughly stirred with a mixer. Ultra fine particles of alumina were uniformly adhered to the surface. This was filled in a quartz boat and fired in a hydrogen atmosphere in a tube furnace at 850 ° C. for 2 hours, and then classified to prepare a europium-activated barium fluoroiodide phosphor having an average particle size of 4 μm. . (Preparation of Phosphor Layer Coating Solution)
g and polyester resin (Toyobo, Byron 63SS
16.7 g of a solid content concentration of 30%) was added to a mixed solvent of methyl ethyl ketone-toluene (1: 1), dispersed by a propeller mixer, and the viscosity was adjusted to 25 to 30 Pa · s to prepare a phosphor layer coating solution. did. (Preparation of Coating Liquid for Undercoat Layer) 100 parts by mass of a polymer resin (polyester resin Tg: 50 ° C.) was mixed with 3 parts by mass of Coronate HX (manufactured by Nippon Polyurethane Co.) as a cross-linking agent, and this mixture was mixed with methyl ethyl ketone: toluene. Of 1:
1 was added to a mixed solvent and dispersed by a propeller mixer to prepare an undercoat layer coating solution having a viscosity of 500 mPa · s. (Preparation of Phosphor Sheet) <Coating of Undercoat Layer> After coating the above-prepared undercoat layer coating solution on a polyethylene terephthalate support having a thickness of 250 μm using a knife coater so that the dry film thickness becomes 30 μm. Then, it was dried to prepare an undercoat layer-coated sample. <Heat treatment> The above-prepared undercoat layer-coated sample was
Heat treatment was performed at 10 ° C. for 10 hours. <Coating of Phosphor Layer> On the undercoat layer of the heat-treated sample, using the prepared phosphor layer coating solution, a coating width of 1000 mm and a film thickness of 230 using a doctor blade was used.
After coating so as to have a thickness of μm, the phosphor layer was formed by drying at 100 ° C. for 15 minutes.

Then, after the phosphor layer was dried, a compression process was performed using a roll group having the structure shown in FIG.

The compression part has a three-roll type in-line configuration, and two heat rolls 9-1 and 9-3 and one compliant roll 9-2 form two nips, and the phosphor layer forming surface is formed. It was adjusted so that the compliant roll would come into contact with it.

The heat rolls 9-1 and 9-3 have a diameter of 30.
A compliant roll 9-2 having a diameter of 250 mmφ, a hardness of Shore D75 °, a crown amount of 0 μm, and JIS-B-06 is used.
The center line average surface roughness Ra defined by 01 is 0.4 μm.
The polyester mirror tex roll (made by Yamauchi Rubber) of was used. In addition, the compression treatment is performed at a heat roll temperature of 7
The temperature was set to 0 ° C. and the linear pressure was adjusted to 1 kN / cm. (Preparation of Moisture-Proof Protective Film) As the protective film on the phosphor layer coated surface side of the phosphor sheet 1 prepared above, one having the following constitution (A) was used.

Structure (A) NY15 /// VMPET12 /// VMPET12 /
// PET12 /// CPP20 NY: Nylon PET: Polyethylene terephthalate CPP: Casting polypropylene VMPET: Alumina-deposited PET (commercially available product: manufactured by Toyo Metallizing Co., Ltd.) μm).

The above-mentioned "///" means a dry lamination adhesive layer, and the thickness of the adhesive layer is 3.0 μm. The used adhesive for dry lamination is
A two-component reactive urethane adhesive was used.

The protective film on the back surface side of the support of the phosphor sheet 1 is CPP 30 μm / aluminum film 9 μm /
A dry laminated film having a constitution of polyethylene terephthalate (PET) 188 μm was used. In this case, the thickness of the adhesive layer was 1.5 μm, and a two-component reaction type urethane adhesive was used.

Further, as shown in Table 1, the luminescent agent a (C.
I. Fluorescent Brightener2
Phosphor sheets 2 to 7 were obtained in the same manner except that 4) was added.

[0101]

[Chemical 1]

The method of adding a luminescent agent will be described below. 1. Method of Addition to Support A stretched film was formed by adding 0.5 μm titanium oxide and the above luminescent agent to a molten polyethylene terephthalate resin. 2. Addition method to the undercoat layer After adding and mixing the above luminescent agent to the coating solution for the undercoat layer, coating / coating
It was dried. 3. Addition method to phosphor layer Add the above-mentioned luminescent agent to the phosphor layer coating solution and disperse it with a disper.
The mixture was dispersed for 0 minutes, and applied and dried. (Production of Radiation Image Conversion Panel) Each of the produced phosphor sheets 1 to 7 is cut into a square having a side of 20 cm, and the impulse-sealer is applied to the peripheral edge portion under reduced pressure using the produced moisture-proof protective film. Fused and sealed using
Radiation image conversion panels 1 to 7 were produced. The distance from the fusion portion to the peripheral edge of the phosphor sheet was 1 mm. The heater of the impulse sealer used for fusing has a width of 3 mm. (Evaluation) Luminance (sensitivity) measurement For each radiation image conversion panel, the luminance was measured according to the method described below. The results are shown in Table 1 below.

The luminance was measured by irradiating each radiation image conversion panel with X-rays with a tube voltage of 80 kVp from the back surface side of the phosphor sheet support, and then operating the panel with He-Ne laser light (633 nm) to excite it. Then, the photostimulable luminescence emitted from the phosphor layer is received by a photodetector (photoelectron image multiplier with spectral sensitivity S-5), its intensity is measured, and this is defined as brightness. The brightness of 1 is 100,
Displayed as a relative value.

[0104]

[Table 1]

As is clear from the order of support / subbing layer / phosphor layer, the above "//" means that the radiation image conversion panel of the present invention containing a luminescent agent does not contain the radiation image conversion panel. On the other hand, it can be seen that the brightness is expected to be improved and the radiation characteristics are excellent.

In addition, when the luminescent agent is contained, the best brightness can be obtained when it is added to all the constituent layers in equal amounts, added to the phosphor layer, or added to the support in a large amount. It became clear that it could be done.

Example 2 The luminescent agent used is shown in Table 2 as luminescent agent b (CI Flu).
radiographic image conversion panel 8 in the same manner as in Example 1 except that the radiation image conversion panel 8 is changed to a transparent brightener 85).
Was manufactured and the luminance was evaluated in the same manner. The results are shown in Table 2 below.

[0108]

[Chemical 2]

[0109]

[Table 2]

As can be seen from Table 2, even if other luminescent agents are used, it is expected that the brightness of the non-containing radiation image conversion panel can be improved and the radiation characteristics are excellent.

[0111]

The radiation image conversion panel of the present invention is remarkably excellent in that the brightness can be improved by incorporating a luminescent agent having the luminescence specified in the present invention into any of the constituent materials. Produce an effect.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of an embodiment of a compression process according to the present invention.

[Explanation of symbols]

4 coater 6 supply rolls 7 Support 8 drying zones 9-1 to 9-3 Calendar roll 10 winding roll

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09K 11/61 CPF C09K 11/61 CPF G01T 1/00 G01T 1/00 B

Claims (4)

[Claims] 1. A stimulable phosphor layer containing a stimulable phosphor dispersed in a polymer resin and a protective layer are laminated in this order on a support. A radiation image conversion panel, characterized in that either the phosphor layer or the protective layer contains a luminescent agent that emits light having a stimulated main emission peak wavelength or more and less than an excitation peak wavelength by stimulated emission. 2. An undercoat layer, a stimulable phosphor layer containing a stimulable phosphor dispersed in a polymer resin, and a protective layer, which are laminated in this order on a support. Subbing layer,
A radiation image conversion panel comprising a stimulable phosphor layer and / or a protective layer, which contains a luminescent agent which emits light having a stimulated emission peak wavelength longer than an excitation peak wavelength by stimulated emission. 3. The radiation image conversion panel according to claim 1, wherein the support is polyethylene terephthalate having bubbles. 4. The radiation image according to claim 1, wherein the stimulable phosphor layer contains a stimulable phosphor represented by the following general formula (1). Conversion panel. General formula (1) BaFI: Eu ²⁺