Radiation image converting material

Radiation image converting materials such as a radiation image storage panel and a radiographic intensifying screen comprising a support and a phosphor layer provided on the support which comprises a binder and a phosphor dispersed therein are provided with an electrically conductive polymer layer.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a radiation image converting material 
provided with a conductive polymer layer which is improved in the 
antistatic property. More particularly, the invention relates to a 
radiographic intensifying screen, and a radiation image storage panel 
employed in a radiation image recording and reproducing method utilizing a 
stimulable phosphor. 
2. Description of the Prior Art 
In a variety of radiography such as medical radiography for diagnosis and 
industrial radiography for non-destructive inspection, a radiographic 
intensifying screen is generally employed in close contact with one or 
both surfaces of a radiographic film such as an X-ray film for enhancing 
the radiographic speed of the system. 
As a method replacing the radiography, a radiation image recording and 
reproducing method utilizing a stimulable phosphor as described, for 
instance, in U.S. Pat. No. 4,239,968, has been recently paid much 
attention. In this method, a radiation image storage panel comprising a 
stimulable phosphor (i.e., stimulable phosphor sheet) is employed, and the 
method involves the steps of causing the stimulable phosphor of the panel 
to absorb radiation energy having passed through an object or having 
radiated from an object; sequentially exciting the stimulable phosphor 
with an electromagnetic wave such as visible light or infrared rays 
(hereinafter referred to as "stimulating rays") to release the radiation 
energy stored in the phosphor as light emission (stimulated emission); 
photoelectrically detecting the emitted light to obtain electric signals; 
and reproducing the radiation image of the object as a visible image from 
the electric signals. 
In the radiation image recording and reproducing method, a radiation image 
is obtainable with a sufficient amount of information by applying a 
radiation to an object at considerably smaller dose, as compared with the 
conventional radiography. Accordingly, this method is of great value 
especially when the method is used for medical diagnosis. 
The radiation image converting materials such as the radiographic 
intensifying screen employed in the conventional radiography and the 
radiation image storage panel employed in the above-described radiation 
image recording and reproducing method comprise a support and a phosphor 
layer provided thereon. Further, a transparent film is generally provided 
on the free surface of the phosphor layer (a surface not facing the 
support) to keep the phosphor layer from chemical deterioration and 
physical shock. 
In the radiation image storage panel, the phosphor layer comprises a binder 
and stimulable phosphor particles dispersed therein. The stimulable 
phosphor emits light (gives stimulated emission) when excited with an 
electromagnetic wave (stimulating rays) such as visible light or infrared 
rays after having been exposed to a radiation such as X-rays. Accordingly, 
the radiation having passed through an object or radiated from an object 
is absorbed by the phosphor layer of the panel in proportion to the 
applied radiation dose, and a radiation image of the object is produced in 
the panel in the form of a radiation energy-stored image. The radiation 
energy-stored image can be released as stimulated emission by sequentially 
irradiating (scanning) the panel with stimulating rays. The stimulated 
emission is then photoelectrically detected to give electric signals, so 
as to reproduce a visible image from the electric signals. 
The radiation image recording and reproducing method is very advantageous 
for obtaining a visible image as described above, and the radiation image 
storage panel used in the method is desired to have high sensitivity and 
provide an image of high quality (high sharpness, high graininess, etc.), 
as well as a radiographic intensifying screen used in the conventional 
radiography. In performing the radiation image recording and reproducing 
method, the radiation image storage panel is repeatedly used in a cyclic 
procedure comprising the steps of: exposing the panel to a radiation 
(recording radiation image thereon), irradiating the panel with 
stimulating rays (reading out the recorded radiation image therefrom) and 
irradiating the panel with a light for erasure (erasing the remaining 
radiation image therefrom). The panel is transferred from a step to the 
subsequent step in a transfer system in such a manner that the panel is 
sandwiched between transferring members (e.g., rolls and endless belt) of 
the system, and piled on other panels to be stored after one cycle is 
finished. 
As a support material of the radiation image storage panel, desirably 
employed are plastic films such as a polyethylene terephthalate film and 
various papers from the viewpoint of flexibility required in the 
transferring procedure of the panel. 
However, the panel is apt to be electrostatically charged on its surface in 
the repeated use comprising transferring and piling owing to the physical 
contact such as friction between the surface of the panel (surface of the 
phosphor layer or surface of the protective film) and a surface of other 
panel (surface of the support), friction between the edge of the panel and 
a surface of other panel, and a friction between the panel and 
transferring members (e.g., roll and belt). In more detail, the surface 
(front surface) of the panel made of a polymer material tends to be 
negatively charged and other surface (back surface) thereof tends to be 
positively charged. This static electrification causes various problems in 
the practical operation of the radiation image recording and reproducing 
method. 
For example, when the surface of the panel is charged, the panel easily 
adheres to another panel and panes under adhesion panels are transferred 
together in layers from the piling position into the transfer system, 
whereby the subsequent procedure cannot be normally conducted. The 
read-out procedure of the panel is generally carried out by irradiating 
the panel with stimulating rays from the phosphor layer-side surface of 
the panel, and in this procedure, the charged surface of the panel is 
likely to be attached with dust in air, so that the stimulating rays are 
also scattered on the dust attached thereon and the quality of the 
resulting image lowers. Moreover, the resulting image provided by the 
panel suffers noise (static mark) when discharge of the panel takes place. 
For improving the above-mentioned static electrification of the panel, 
there have been proposed various radiation image storage panels provided 
with antistatic functions, for example, a radiation image storage panel 
provided with an antistatic film comprising a conductive inorganic oxide 
on the surface of the protective film as described in U.S. patent 
application Ser. No. 818,239 (corresponding to EP Application No. 
86100417.4) and a radiation image storage panel provided with an 
antistatic layer made of a conductive material and having a specific 
surface resistivity (10.sup.11 ohm) on the surface of the support not 
facing the phosphor layer or between the support and the phosphor layer as 
described in U.S. patent application Ser. No. 918,356 (corresponding to EP 
Application No. 86114224.8). 
In the radiographic intensifying screen, the phosphor layer comprises a 
binder and phosphor particles dispersed. therein. When excited with a 
radiation such as X-rays having passed through an object, the phosphor 
particles emit light of high luminance (spontaneous emission) in 
proportion to the dose of the radiation. Accordingly, the radiographic 
film placed in close contact with the phosphor layer of the screen can be 
exposed sufficiently to form a radiation image of the object, even if the 
radiation is applied to the object at a relatively small dose. 
The conventional radiography is generally conducted by encasing the 
radiographic intensifying screen and a radiographic film in a 
light-blocking cassette in such a manner that the screen and the film are 
arranged in close contact with each other. However, since both of the 
screen and the film are made of plastic material, the screen and the film 
are electrostatically charged due to contact with each other when the film 
is received in or is taken out of the cassette. As a result, discharge 
occasionally takes place, and an image formed on the film likely suffers 
noise (static mark), whereby accuracy of diagnostic examination lowers. 
Recently, a continous radiographic system using no cassette (i.e., 
cassetteless system) has been developed and utilized for enhancing the 
examination efficiency. For example, in a radiographic apparatus for 
angiocardiography, a pair of radiographic intensifying screens fixed at 
the predetermined position, and in the radiographic operation, a number of 
radiographic films having been received in a magazine equipped in the 
apparatus are automatically and continuously transferred one after another 
to be received between the two screens. The used film is then transferred 
and received in a different magazine for used films by a transferring 
device, and at the same time an unused film is set between the screens. 
Thus, the radiographic procedures are continuously carried out at a high 
speed. 
In the above-mentioned cassetteless system, the radiographic film is liable 
to be much more electostatically charged than the case of using the 
cassette, because contact of a film with another film and the contact of 
the film with the transferring members in the transferring procedure take 
place repeatedly, in addition to the contact of the film with the screen. 
As a result, a discharge phenomenon between the film and the screen takes 
place. 
For preventing the occurrence of the static electrification and discharge, 
various technological measures have been proposed and practically utilized 
for the radiographic screen. For example, a method of coating or spraying 
a liquid antistatic agent onto the screen is generally utilized, but this 
method forms merely a coated layer on the surface of the screen. Hence, 
the coated layer tends to gradually separate from the screen as a lapse of 
time, owing to the contact with the radiographic film, etc., and the 
screen is reduced in the antistatic properties. Especially in the high 
speed radiography, there is such a trouble that the antistatic treatment 
(coating of the antistatic agent) should be repeatedly made at an 
appropriate interval because a great number of radiographic operations 
should be repeatedly performed. 
For providing the antistatic properties to the radiographic intensifying 
screen, it is described that a carbon black layer is provided between the 
support and the phosphor layer and an antistatic agent is incorporated 
into its protective film in Japanese Patent Provisional Publication No. 
52(1977)-28284. It is stated that according to this method the resulting 
radiographic intensifying screen can be prevented from electrostatical 
charging owing to the functions of the carbon black layer and the 
protective film. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a radiation image 
storage panel which is improved in the antistatic properties. 
It is another object of the invention to provide a radiation image storage 
panel which is reduced in the occurrence of static mark to give an 
improved image. 
It is a further object of the invention to provide a radiographic 
intensifying screen which is improved in the antistatic properties. 
It is a still further object of the invention to provide a radiographic 
intensifying screen which is reduced in the occurrence of static mark to 
give an improved image. 
The above-mentioned objects can be accomplished by radiation image 
converting material such as a radiation image storage panel and a 
radiographic intensifying screen comprising a support and a phosphor layer 
provided on the support which comprises a binder and a phosphor dispersed 
therein, characterized in that said radiation image converting material is 
provided with a conductive polymer layer. 
The expression "a conductive polymer constituting a conductive polymer 
layer" used herein means a polymer per se showing an electric 
conductivity. 
In the radiation image storage panel, a conductive polymer layer is 
provided on at least one of layers constituting the panel, whereby the 
panel is improved in the antistatic properties on the surface (phosphor 
layer-side surface) of the panel. 
According to the invention, the static electrification occurring on the 
surface of the radiation image storage panel can be effectively prevented. 
In more detail, the provision of a conductive polymer layer enables to 
keep the surface of the resulting panel under electrostatically stable 
condition (i.e., reduced charge condition). The reason is presumed as 
follows: when the surface of the panel is charged with a large quantity of 
electricity, an opposite charge of the same quantity of electricity is 
produced in the conductive polymer layer of the panel, if the conductive 
polymer layer is provided between the layers (e.g., between the support 
and the phosphor layer) of the panel or the surface of the panel, and 
hence the surface of the panel is apparently less charged. Particularly in 
the use of providing the conductive polymer layer on the surface of the 
panel or in the vicinity thereof (e.g., surface of the phosphor layer, or 
between the phosphor layer and a protective film in the case that the 
protective film is provided on the phosphor layer), a high antistatic 
effect can be attained. Accordingly, the phosphor layer-side surface of 
the panel is reduced in the attraction force for other material which is 
caused by the static charge. As a result, it is prevented that two panels 
are introduced into the transfer system in the combined form from the 
piling state to the transferring state in the radiation image recording 
and reproducing apparatus. Further, the panel is effectively kept from 
deposit of dust on the phosphor layer-side surface, and the occurrence of 
noise (static mark) is also prevented on a image provided by the panel, 
whereby an image of high quality is obtained. 
The polymer which constitutes the conductive polymer layer of the panel 
according to the invention is transparent, so that even when the 
conductive polymer layer is provided on the upper side than that of the 
phosphor layer (in the vicinity of the surface of the panel), the 
stimulating rays having been irradiated on the panel are hardly blocked by 
the polymer layer and the stimulating rays are sufficiently transmitted 
through the layer. Hence, the panel provides an image of high quality 
without being lowered in the sensitivity. 
In the radiographic intensifying screen, the conductive polymer layer can 
be also arranged at any position, as well as in the case of the 
above-described radiation image storage panel. By providing the conductive 
polymer layer, the surface of the radiographic intensifying screen 
(opposite side surface of the support) can be improved in the antistatic 
properties. The conductive polymer layer arranged on the surface of the 
phosphor layer or the surface of the support (or between the phosphor 
layer and the support) can keep the surface of the screen in the 
electrostatically stable condition (i.e., reduced charge condition). The 
reason is presumed as follows: when the surface of the screen is charged 
with a large quantity of electricity, an opposite charge of the same 
quantity of electricity is produced in the conductive polymer layer of the 
surface of the screen, and hence the surface of the screen is apparently 
less charged. Particularly in the case of providing the conductive polymer 
layer in the vicinity of the surface of the screen (e.g., surface of the 
phosphor layer or between the phosphor layer and a protective film in the 
case that the protective film is provided on the phosphor layer), a high 
antistatic effect is given. Accordingly, a radiographic film used in close 
contact with the radiographic intensifying screen is hardly given an 
unfavorable effect caused by the static charge, and hence an improve image 
which is almost free from occurrence of noise such as static mark is 
obtained.

DETAILED DESCRIPTION OF THE INVENTION 
Representative examples of the radiation image converting material of the 
present invention are a radiation image storage panel and a radiographic 
intensifying screen. 
First, the radiation image converting material of the invention is 
described in detail with respect to the radiation image storage panel. 
The radiation image storage panel of the invention basically comprises a 
support and a phosphor layer provided on the support which comprises a 
binder and a stimulable phosphor dispersed therein, and the panel is 
further provided with a conductive polymer layer. 
Thus, the radiation image storage panel has at least one conductive polymer 
layer (described hereinafter) arranged in any desired position. 
FIG. 1 shows favorable embodiments of the radiation image storage panel 
according to the invention. 
In each of FIGS. 1-(1) to 1-(4), the panel comprises a support (11), a 
phosphor layer (12), a protective film (13) and a conductive polymer layer 
(14). The conductive polymer layer (14) is arranged between the phosphor 
layer and the protective film in FIG. 1-(1), on the surface of the 
protective film (panel surface) in FIG. 1-(2), between the phosphor layer 
and the support in FIG. 1-(3), or on the surface of the support (surface 
not facing the phosphor layer) in FIG. 1-(4). In FIG. 1-(5), the panel 
further comprises a back layer (15) provided on the surface of the support 
in addition to the above-mentioned layers, and the conductive polymer 
layer (14) is provided on the surface of the back layer. The structure of 
the radiation image storage panel according to the invention is by no 
means restricted to the above-mentioned ones, and any other constituents 
can be utilized in the invention. For example, an additional layer such as 
an intermediate layer can be optionally provided in the panel of the above 
structure. 
The radiation image storage panel according to the invention is described 
in detail hereinafter referring to the embodiment shown in FIG. 1-(1). 
The radiation image storage panel can be prepared, for example, by the 
following process. 
Examples of the support material employable in the radiation image storage 
panel of the invention include plastic films such as films of cellulose 
acetate, polyester, polyethylene terephthalate, polyamide, polyimide, 
triacetate and polycarbonate; metal sheets such as aluminum foil and 
aluminum alloy foil; ordinary papers; baryta paper; resin-coated papers; 
pigment papers containing titanium dioxide or the like; and papers sized 
with polyvinyl alcohol or the like. From the viewpoint of characteristics 
of a radiation image recording material and handling thereof, a plastic 
film is preferably employed as the support material in the invention. The 
plastic film may contain a light-absorbing material such as carbon black, 
or may contain a light-reflecting material such as titanium dioxide. The 
former is appropriate for preparing a high-sharpness type radiation image 
storage panel, while the latter is appropriate for preparing a 
high-sensitivity type radiation image storage panel. 
In the preparation of a known radiation image storage panel, one or more 
additional layers are occasionally provided between the support and the 
phosphor layer, so as to enhance the adhesion between the support and the 
phosphor layer, or to improve the sensitivity of the panel or the quality 
of an image (sharpness and graininess) provided thereby. For instance, a 
subbing layer may be provided by coating a polymer material such as 
gelatin over the surface of the support on the phosphor layer side. 
Otherwise, a light-reflecting layer may be provided by forming a polymer 
material layer containing a light-reflecting material such as titanium 
dioxide. In the invention, one or more of these additional layers may be 
provided on the support. 
As described in U.S. patent application No. 496,278, the phosphor 
layer-side surface of the support (or the surface of a subbing layer or 
light-reflecting layer in the case that such layers are provided on the 
phosphor layer) may be provided with protruded and depressed portions for 
enhancement of the sharpness of the image. 
Subsequently, on the support is provided a phosphor layer. The phosphor 
layer basically comprises a binder and stimulable phosphor particles 
dispersed therein. The stimulable phosphor, as described hereinbefore, 
gives stimulated emission when excited with stimulating rays after 
exposure to a radiation. From the viewpoint of practical use, the 
stimulable phosphor is desired to emit light in the wavelength region of 
300-500 nm when excited with stimulating rays in the wavelength region of 
400-900 nm. 
Examples of the stimulable phosphor employable in the panel of the 
invention include: 
SrS:Ce,Sm, SrS:Eu,Sm, ThO.sub.2 :Er, and La.sub.2 O.sub.2 S:Eu,Sm, as 
described in U.S. Pat. No. 3,859,527; 
ZnS:Cu,Pb, BaO.xAl.sub.2 O.sub.3 :Eu, in which x is a number satisfying the 
condition of 0.8.ltoreq.x.ltoreq.10, and M.sup.2+ O.xSiO.sub.2 :A, in 
which M.sup.2+ is at least one divalent metal selected from the group 
consisting of Mg, Ca, Sr, Zn, Cd and Ba, A is at least one element 
selected from the group consisting of Ce, Tb, Eu, Tm, Pb, Tl, Bi and Mn, 
and x is a number satisfying the condition of 0.5.ltoreq.x.ltoreq.2.5, as 
described in U.S. Pat. No. 4,236,078; 
(Ba.sub.1-x-y,Mg.sub.x,Ca.sub.y)FX:aEu.sup.2+, in which X is at least one 
element selected from the group consisting of Cl and Br, x and y are 
numbers satisfying the conditions of 0&lt;x+y.ltoreq.0.6 and xy=0, and a is a 
number satisfying the condition of 10.sup.-6 
.ltoreq.a.ltoreq.5.times.10.sup.-2, as described in Jpanese Patent 
Provisional Publication No. 55(1980)-12143; 
LnOX:xA, in which Ln is at least one element selected from the group 
consisting of La, Y, Gd and Lu, X is at least one element selected from 
the group consisting of Cl and Br, A is at least one element selected from 
the group consisting of Ce and Tb, and x is a number satisfying the 
condition of 0&lt;x&lt;0.1, as described in U.S. Pat. No. 4,236,078; 
(Ba.sub.1-x,M.sup.II.sub.x)FX:yA, in which M.sup.II is at least one 
divalent metal selected from the group consisting of Mg, Ca, Sr, Zn and 
Cd, X is at least one element selected from the group consisting of Cl, Br 
and I, A is at least one element selected from the group consisting of Eu, 
Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb and Er, and x and y are numbers satisfying 
the conditions of 0.ltoreq.x.ltoreq.0.6 and 0.ltoreq.y.ltoreq.0.2, 
respectively, as described in U.S. Pat. No. 4,239,968; 
M.sup.II FX.xA:yLn, in which M.sup.II is at least one element selected from 
the group consisting of Ba, Ca, Sr, Mg, Zn and Cd; A is at least one 
compound selected from the group consisting of BeO, MgO, CaO, SrO, BaO, 
ZnO, Al.sub.2 O.sub.3, Y.sub.2 O.sub.3, La.sub.2 O.sub.3, In.sub.2 
O.sub.3, SiO.sub.2, TiO.sub.2, ZrO.sub.2, GeO.sub.2, SnO.sub.2, Nb.sub.2 
O.sub.5, Ta.sub.2 O.sub.5 and ThO.sub.2 ; Ln is at least one element 
selected from the group consisting of Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb, 
Er, Sm and Gd; X is at least one element selected from the group 
consisting of Cl, Br and I; and x and y are numbers satisfying the 
conditions of 5.times.10.sup.-5 .ltoreq.x.ltoreq.0.5 and 0&lt;y.ltoreq.0.2, 
respectively, as described in Japanese Patent Provisional Publication No. 
55(1980)-160078; 
(Ba.sub.1-x,M.sup.II.sub.x)F.sub.2.aBaX.sub.2 :yEu,zA, in which M.sup.II is 
at least one element selected from the group consisting of Be, Mg, Ca, Sr, 
Zn and Cd; X is at least one element selected from the group consisting of 
Cl, Br and I; A is at least one element selected from the group consisting 
of Zr and Sc; and a, x, y and z are numbers satisfying the conditions of 
0.5.ltoreq.a.ltoreq.1.25, 0.ltoreq.x.ltoreq.1, 10.sup.-6 
.ltoreq.y.ltoreq.2.times.10.sup.-1, and 0&lt;z.ltoreq.10.sup.-2, 
respectively, as described in Japanese Patent Provisional Publication No. 
56(1981)-116777; 
(Ba.sub.1-x,M.sup.II.sub.x)F.sub.2.aBaX.sub.2 :yEu,zB, in which M.sup.II is 
at least one element selected from the group consisting of Be, Mg, Ca, Sr, 
Zn and Cd; X is at least one element selected from the group consisting of 
Cl, Br and I; and a, x, y and z are numbers satisfying the conditions of 
0.5.ltoreq.a.ltoreq.1.25, 0.ltoreq.x.ltoreq.1, 10.sup.-6 
.ltoreq.y.ltoreq.2.times.10.sup.-1, and 0&lt;z.ltoreq.2.times.10.sup.-1, 
respectively, as described in Japanese Patent Provisional Publication No. 
57(1982)-23673; 
(Ba.sub.1-x,M.sup.II.sub.x)F.sub.2.aBaX.sub.2 :yEu,zA, in which M.sup.II is 
at least one element selected from the group consisting of Be, Mg, Ca, Sr, 
Zn and Cd; X is at least one element selected from the group consisting of 
Cl, Br and I; A is at least one element selected from the group consisting 
of As and Si; and a, x, y and z are numbers satisfying the conditions of 
0.5.ltoreq.a.ltoreq.1.25, 0.ltoreq.x.ltoreq.1, 10.sup.-6 
.ltoreq.y.ltoreq.2.times.10.sup.-1, and 0&lt;z.ltoreq.5.times.10.sup.-1, 
respectively, as described in Japanese Patent Provisional Publication No. 
57(1982)-23675; 
M.sup.III OX:xCe, in which M.sup.III is at least one trivalent metal 
selected from the group consisting of Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, 
Tm, Yb, and Bi; X is at least one element selected from the group 
consisting of Cl and Br; and x is a number satisfying the condition of 
0&lt;x&lt;0.1, as described in Japanese Patent Provisional Publication No. 
58(1983)-69281; 
Ba.sub.1-x M.sub.x/2 L.sub.x/2 FX:yEu.sup.2+, in which M is at least one 
alkali metal selected from the group consisting of Li, Na, K, Rb and Cs; L 
is at least one trivalent metal selected from the group consisting of Sc, 
Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, In and 
Tl; X is at least one halogen selected from the group consisting of Cl, Br 
and I; and x and y are numbers satisfying the conditions of 10.sup.-2 
.ltoreq.x.ltoreq.0.5 and 0&lt;y.ltoreq.0.1, respectively, as described in 
U.S. patent application No. 497,805; 
BaFX.xA:yEu.sup.2+, in which X is at least one halogen selected from the 
group consisting of Cl, Br and I; A is at least one fired product of a 
tetrafluoroboric acid compound; and x and y are numbers satisfying the 
conditions of 10.sup.-6 .ltoreq.x.ltoreq.0.1 and 0&lt;y.ltoreq.0.1, 
respectively, as described in U.S. patent application No. 520,215; 
BaFX.xA:yEu.sup.2+, in which X is at least one halogen selected from the 
group consisting of Cl, Br and I; A is at least one fired product of a 
hexafluoro compound selected from the group consisting of monovalent and 
divalent metal salts of hexafluoro silicic acid, hexafluoro titanic acid 
and hexafluoro zirconic acid; and x and y are numbers satisfying the 
conditions of 10.sup.-6 .ltoreq.x.ltoreq.0.1 and 0&lt;y.ltoreq.0.1, 
respectively, as described in U.S. patent application No. 502,648; 
BaFX.xNaX':aEu.sup.2+, in which each of X and X' is at least one halogen 
selected from the group consisting of Cl, Br and I; and x and a are 
numbers satisfying the conditions of 0&lt;x.ltoreq.2 and 0&lt;a.ltoreq.0.2, 
respectively, as described in Japanese Patent Provisional Publication No. 
59(1984)-56479; 
M.sup.II FX.xNaX':yEu.sup.2+ :zA, in which M.sup.II is at least one 
alkaline earth metal selected from the group consisting of Ba, Sr and Ca; 
each of X and X' is at least one halogen selected from the group 
consisting of Cl, Br and I; A is at least one transition metal selected 
from the group consisting of V, Cr, Mn, Fe, Co and Ni; and x, y and z are 
numbers satisfying the conditions of 0&lt;x.ltoreq.2, 0&lt;y.ltoreq.0.2 and 
0&lt;z.ltoreq.10.sup.-2, respectively, as described in U.S. patent 
application No. 535,928; 
M.sup.II FX.aM.sup.I X'.bM'.sup.II X".sub.2.cM.sup.III 
X'".sub.3.xA:yEu.sup.2+, in which M.sup.II is at least one alkaline earth 
metal selected from the group consisting of Ba, Sr and Ca; M.sup.I is at 
least one alkali metal selected from the group consisting of Li, Na, K, Rb 
and Cs; M'.sup.II is at least one divalent metal selected from the group 
consisting of Be and Mg; M.sup.III is at least one trivalent metal 
selected from the group consisting of Al, Ga, In and Tl; A is metal oxide; 
X is at least one halogen selected from the group consisting of Cl, Br and 
I; each of X', X" and X'" is at least one halogen selected from the group 
consisting of F, Cl, Br and I; a, b and c are numbers satisfying the 
conditions of 0.ltoreq.a.ltoreq.2, O.ltoreq.b.ltoreq.10.sup.-2, 
0.ltoreq.c.ltoreq.10.sup.-2 and a+b+c.gtoreq.10.sup.-6 ; and x and y are 
numbers satisfying the conditions of 0&lt;x.ltoreq.0.5 and 0&lt;y.ltoreq.0.2, 
respectively, as described in U.S. patent application No. 543,326; 
M.sup.II X.sub.2.aM.sup.II X'.sub.2 :xEu.sup.2+, in which M.sup.II is at 
least one alkaline earth metal selected from the group consisting of Ba, 
Sr and Ca; each of X and X' is at least one halogen selected from the 
group consisting of Cl, Br and I, and X=X'; and a and x are numbers 
satisfying the conditions of 0.1.ltoreq.a.ltoreq.10.0 and 0&lt;x.ltoreq.0.2, 
respectively, as described in U.S. patent application No. 660,987; 
M.sup.II FX.aM.sup.I X':xEu.sup.2+, in which M.sup.II is at least one 
alkaline earth metal selected from the group consisting of Ba, Sr and Ca; 
M.sup.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; X' is at least one halogen selected from the group 
consisting of F, Cl, Br and I; and a and x are numbers satisfying the 
conditions of 0.ltoreq.a.ltoreq.4.0 and 0&lt;x.ltoreq.0.2, respectively, as 
described in U.S. patent application No. 668,464; and 
M.sup.I X:Bi, in which M.sup.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 a number satisfying the 
condition of 0&lt;x.ltoreq.0.2, as described in U.S. patent application No. 
846,919. 
The M.sup.II X.sub.2.aM.sup.II X'.sub.2 :xEu.sup.2+ phosphor described in 
the above-mentioned U.S. patent application No. 660,987 may contain the 
following additives in the following amount per 1 mol of M.sup.II 
X.sub.2.aM.sup.II X'.sub.2 : 
bM.sup.I X", in which M.sup.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; and b is a number satisfying 
the condition of 0&lt;b.ltoreq.10.0, as described in U.S. patent application 
No. 699,325; 
bKX".cMgX"'.sub.2.dM.sup.III X"".sub.3, in which M.sup.III is at least one 
trivalent metal selected from the group consisting of Sc, Y, La, Gd and 
Lu; each of X", X"' and X"" is at least one halogen selected from the 
group consisting of F, Cl, Br and I; and b, c and d are numbers satisfying 
the conditions of 0&lt;b.ltoreq.2.0, 0.ltoreq.c.ltoreq.2.0, 
0.ltoreq.d.ltoreq.2.0 and 2.times.10.sup.-5 .ltoreq.b+c+d, as described in 
U.S. patent application No. 723,819; 
yB, in which y is a number satisfying the condition of 2.times.10.sup.-4 
.ltoreq.y.ltoreq.2.times.10.sup.-1, as described in U.S. patent 
application No. 727,974; 
bA, in which A is at least one oxide selected from the group consisting of 
SiO.sub.2 and P.sub.2 O.sub.5 ; and b is a number satisfying the condition 
of 10.sup.-4 .ltoreq.b.ltoreq.2.times.10.sup.-1, as described in U.S. 
patent application No. 727,972; 
bSiO, in which b is a number satisfying the condition of 
0&lt;b.ltoreq.3.times.10.sup.-2, as described in U.S. patent application No. 
797,971; 
bSnX".sub.2, in which X" is at least one halogen selected from the group 
consisting of F, Cl, Br and I; and b is a number satisfying the condition 
of 0&lt;b.ltoreq.10.sup.-3, as described in U.S. patent application No. 
797,971; 
bCsX".cxSnX"'.sub.2, in which each of X" and X"' is at least one halogen 
selected from the group consisting of F, Cl, Br and I; and b and c are 
numbers satisfying the conditions of 0&lt;b.ltoreq.10.0 and 10.sup.-6 
.ltoreq.c.ltoreq.2.times.10.sup.-2, respectively, as described in U.S. 
patent application No. 850,715; and 
bCsX".yLn.sup.3+, in which X" is at least one halogen selected from the 
group consisting of F, Cl, Br and I; Ln is at least one rare earth element 
selected from the group consisting of Sc, Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, 
Ho, Er, Tm, Yb and Lu; and b and y are numbers satisfying the conditions 
of 0&lt;b.ltoreq.10.0 and 10.sup.-6 .ltoreq.y.ltoreq.1.8.times.10.sup.-1, 
respectively, as described in U.S. patent application No. 850,715. 
Among these above-described stimulable phosphors, the divalent europium 
activated alkaline earth metal halide phosphor and rare earth element 
activated rare earth oxyhalide phosphor are particularly preferred, 
because these phosphors show stimulated emission of high luminance. The 
above-described stimulable phosphors are given by no means to restrict the 
stimulable phosphor empolyable in the panel of the invention. Any other 
phosphors can be also employed, provided that the phosphor gives 
stimulated emission when excited with stimulating rays after exposure to a 
radiation. 
Examples of the binder to be contained in the phosphor layer include: 
natural polymers such as proteins (e.g. gelatin), polysaccharides (e.g. 
dextran) and gum arabic; and synthetic polymers such as polyvinyl butyral, 
polyvinyl acetate, nitrocellulose, ethylcellulose, vinylidene 
chloride-vinyl chloride copolymer, polyalkyl (meth) acrylate, vinyl 
chloride-vinyl acetate copolymer, polyurethane, cellulose acetate 
butyrate, polyvinyl alcohol, and linear polyester. Particularly preferred 
are nitrocellulose, linear polyester, polyalkyl (meth)acrylate, a mixture 
of nitrocellulose and linear polyester, and a mixture of nitrocellulose 
and polyalkyl (meth)acrylate. These binders may be crosslinked with a 
crosslinking agent. 
The phosphor layer can be formed on the support, for instance, by the 
following procedure. 
In the first place, the above-described stimulable phosphor and binder are 
added to an appropriate solvent, and then they are mixed to prepare a 
coating dispersion comprising the phosphor particles homogeneously 
dispersed in the binder solution. 
Examples of the solvent employable in the preparation of the coating 
dispersion include lower alcohols such as methanol, ethanol, n-propanol 
and n-butanol; chlorinated hydrocarbons such as methylene chloride and 
ethylene chloride; ketones such as acetone, methyl ethyl ketone and methyl 
isobutyl ketone; esters of lower alcohols with lower aliphatic acids such 
as methyl acetate, ethyl acetate and butyl acetate; ethers such as 
dioxane, ethylene glycol monoethylether and ethylene glycol monomethyl 
ether; and mixtures of the above-mentioned compounds. 
The ratio between the binder and the stimulable phosphor in the coating 
dispersion may be determined according to the characteristics of the aimed 
radiation image storage panel, the nature of the phosphor employed, etc. 
Generally, the ratio therebetween is within the range of from 1:1 to 1:100 
(binder:phosphor, by weight), preferably from 1:8 to 1:40. 
It may be thought that the above-described binder is replaced with a 
conductive polymer to form a phosphor layer. However, the polymer has poor 
bonding strength as compared with the above binders, so that the phosphor 
particles cannot be sufficiently bound with the polymer when the 
conductive polymer is used alone. When the conductive polymer is used in 
combination with the binder polymer for enhancing the bonding strength, 
satisfactory antistatic effect, that is a characteristic requisite of the 
invention, cannot be obtained. Accordingly, it is difficult to use the 
conductive polymer as a binder for the phosphor layer in the known ratio 
between the phosphor and the binder. 
The coating dispersion may contain a dispersing agent to improve the 
dispersibility of the phosphor particles therein, and may contain a 
variety of additives such as a plasticizer for increasing the bonding 
between the binder and the phosphor particles in the phosphor layer. 
Examples of the dispersing agent include phthalic acid, stearic acid, 
caproic acid and a hydrophobic surface active agent. Examples of the 
plasticizer include phosphates such as triphenyl phosphate, tricresyl 
phosphate and diphenyl phosphate; phthalates such as diethyl phthalate and 
dimethoxyethyl phthalate; glycolates such as ethylphthalyl ethyl glycolate 
and butylphthalyl butyl glycolate; and polyesters of polyethylene glycols 
with aliphatic dicarboxylic acids such as polyester of triethylene glycol 
with adipic acid and polyester of diethylene glycol with succinic acid. 
The coating dispersion containing the phosphor particles and the binder 
prepared as described above is applied evenly onto the surface of the 
support to form a layer of the coating dispersion. The coating procedure 
can be carried out by a conventional method such as a method using a 
doctor blade, a roll coater or a knife coater. 
After applying the coating dispersion onto the support, the coating 
dispersion is then heated slowly to dryness so as to complete the 
formation of a stimulable phosphor layer. The thickness of the stimulable 
phosphor layer varies depending upon the characteristics of the aimed 
radiation image storage panel, the nature of the phosphor, the ratio 
between the binder and the phosphor, etc. Generally, the thickness of the 
stimulable phosphor layer is within the range of from 20 .mu.m to 1 mm, 
and preferably from 50 to 500 .mu.m. 
The stimulable phosphor layer can be provided on the support by the methods 
other than that given in the above. For instance, the phosphor layer is 
initially prepared on a sheet (false support) such as a glass plate, metal 
plate or plastic sheet using the aforementioned coating dispersion and 
then thus prepared phosphor layer is superposed on the support by pressing 
or using an adhesive agent. 
On the surface of the stimulable phosphor layer not facing the support, an 
electrically conductive polymer layer is provided. 
The conductive polymer layer is a layer made of a polymer as such having 
electric conductivity, and the polymer has a molecular structure in which 
electrons or positive holes easily move. Accordingly, the structure of the 
conductive polymer layer is different from that of a layer made of a 
conventional conductive material such as a layer of a conductive polymer 
composition (complex material) in which a surfactant or the like is 
dispersed or an antistatic film as described in the aforementioned U.S. 
States patent applications and the corresponding EP applications. However, 
the conductive polymer layer of the panel according to the invention may 
further contain the above-mentioned conventional conductive materials. 
There is no specific limitation on the conductive polymer employable in the 
invention, provided that the polymer has the above-described function. 
Examples of the conductive polymer employable in the invention include 
conductive acrylic resins (e.g., Corcort NR-121; trade name, available 
from Corcort Co., Ltd.) and polymers having a siloxane bond 
(--Si--O--Si--) (e.g., Corcort R; trade name, available from Corcort Co., 
Ltd.). The polymer having a siloxane bond is coated in the form of a 
monomer and the monomer is cured in the course of the coating procedure to 
become a polymer having a three-dimensional network. 
The conductive polymer layer can be prepared by the process comprising the 
steps of dissolving the abovementioned conductive polymer in an 
appropriate solvent to prepare a coating solution, applying the coating 
solution onto the surface of the phosphor layer by the known coating 
method to give a coated layer of the solution, and drying the coated 
layer. Thus, a conductive polymer layer can be formed on the stimulable 
phosphor layer. 
The thickness of the conductive polymer layer varies depending upon the 
position where the polymer layer is to be arranged, the nature of the 
employed polymer, etc. Generally the thickness thereof is in the range of 
0.5 to 20 .mu.m, preferably in the range of 1 to 10 .mu.m. By adjusting 
the thickness of the conductive polymer layer within the above-specified 
range, the surface resistance of the polymer layer can be set to not 
higher than 10.sup.9 ohm. 
On the surface of the conductive polymer layer not facing the phosphor 
layer, a transparent protective film is provided to protect the resulting 
panel from physical and chemical deterioration. 
The protective film can be provided on the conductive polymer layer by 
coating the surface of the conductive polymer layer with a solution of a 
transparent polymer such as a cellulose derivative (e.g. cellulose acetate 
or nitrocellulose), or a synthetic polymer (e.g. polymethyl methacrylate, 
polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, or 
vinyl chloride-vinyl acetate copolymer), and drying the coated solution. 
Alternatively, the transparent film can be provided on the conductive 
polymer layer by beforehand preparing it from a polymer such as 
polyethylene terephthalate, polyethylene, polyvinylidene chloride or 
polyamide, followed by placing and fixing it onto the conductive polymer 
layer with an appropriate adhesive agent. The transparent protective film 
preferably has a thickness within the range of approximately 1 to 30 
.mu.m. 
The above-described process can provide a radiation image storage panel 
shown in FIG. 1-(1). Panels shown in FIGS. 1-(2) to 1-(5) can be also 
prepared in the similar manner. 
In more detail, a radiation image storage panel of FIG. 1-(2) can be 
obtained by forming a protective film on the phosphor layer and then 
providing a conductive polymer layer on the protective film, or initially 
forming a conductive polymer layer on a transparent thin film (protective 
film) and combining the transparent thin film and the phosphor layer 
together. 
A radiation image storage panel of FIG. 1-(3) can be obtained by forming a 
conductive polymer layer on the beforehand prepared phosphor layer and 
combining thus prepared the composite and the independently prepared 
support in such a manner that the conductive polymer layer faces the 
support surface. In the panel shown in FIG. 1-(3), the conductive polymer 
employed for the preparation of a conductive polymer layer can be 
incorporated with other additives such as an adhesive agent, a polymer for 
an undercoating layer, a light-reflecting material and a light-absorbing 
material to form a conductive polymer layer, whereby the resulting 
conductive polymer layer also serves as an adhesive layer, an undercoating 
layer, a light-reflecting layer, and/or a light-absorbing layer. 
A radiation image storage panel of FIG. 1-(4) can be obtained by initially 
forming a conductive polymer layer on one surface of the support and then 
providing a phosphor layer on other surface of the support. 
A radiation image storage panel of FIG. 1-(5) can be obtained by initially 
forming a back layer on one surface of the support, then forming a 
conductive polymer layer on the back layer and providing a phosphor layer 
on the surface of the support not facing the back layer. 
In the radiation image storage panel shown in FIG. 1-(4), the same back 
layer as shown in FIG. 1-(5) may be formed on the conductive polymer 
layer. The back layer can be obtained by combining a plastic film having a 
relatively low friction coefficient as a friction reducing layer with the 
panel using an adhesive agent, as disclosed in Japanese Patent Provisional 
Publication No. 59(1984)-77400. 
It is also possible to provide two or more conductive polymer layers in the 
radiation image storage panel. For example, the panel of FIG. 1-(1) may be 
further provided another conductive polymer layer (second conductive 
polymer layer, which may serve as an undercoating layer), between the 
support and the phosphor layer. Provision of two or more conductive 
polymer layers can further enhance the antistatic property of the 
resulting panel. 
The structure of the radiation image storage panel according to the 
invention is not restricted to the above-mentioned ones, and any other 
structure such as a structure comprising a support, a phosphor layer and a 
conductive polymer layer can also be included in the invention. 
The radiation image storage panel of the invention may be provided with 
covering 16a, 16b made of a conductive polymer at the edge portion of at 
least one side of as shown in FIG. 2. The covering is preferably provided 
on the front end-edge side and on rear end-edge side, the side being based 
on the transferring direction of the panel. The antistatic effect is much 
more enhanced by providing the covering on the edge portion of the panel. 
In more detail, the covering provided on both ends of the panel are 
brought into smooth contact with the transferring members in the 
transferring procedure, so that the static charge which is liable to be 
stored within the panel can be rapidly released to outside of the panel 
through the smooth contact between the covering and the transferring 
members. As a result, the panel provided with the conductive polymer layer 
and the covering can be further improved in the antistatic property. 
The radiation image storage panel of the invention may be colored with a 
colorant to enhance the sharpness of the resulting image, as described in 
U.S. Pat. No. 4,394,581 and U.S. patent application No. 326,642. For the 
same purpose, the panel of the invention may contain a white powder in the 
phosphor layer, as described in U.S. Pat. No. 4,350,893. 
As other representative example of the radiation image converting material 
of the present invention than the above-mentioned radiation image storage 
panel, there can be mentioned a radiographic intensifying screen as 
described hereinbefore. 
The radiographic intensifying screen according to the invention basically 
comprises a support and a phosphor layer and is further provided with at 
least one conductive polymer layer at any desired position. 
FIG. 4 shows favorable embodiments of the radiographic intensifying screen 
of the invention. 
Each of FIGS. 4-(1) to 4-(3) is a sectional view illustrating the 
radiographic intensifying screen comprising a support, a phosphor layer, a 
protective film and a conductive polymer layer. 
In FIG. 4, the screen comprises a support 1, a phosphor layer 2, a 
protective film 3 and a conductive polymer layer 4. The conductive polymer 
layer 4 is provided between the phosphor layer and the protective film in 
FIG. 4-(1), on the surface of the protective film (surface of the screen) 
in FIG. 4-(2), or between the support and the phosphor layer in FIG. 
4-(3). 
The above-mentioned structures are given by no means to restrict the 
structure of the screen of the invention, and any other structure can be 
applied to the invention. For example, the conductive polymer may be 
provided on the surface of the support not facing the phosphor layer, or 
may be provided on one surface of a back layer or the like in the case 
that such layer is arranged on the support. The screen of the invention 
may be provided with two or more conductive polymer layers. For example, 
the screen of FIG. 4-(1) may be further provided with another conductive 
polymer layer (second polymer layer) between the support and the phosphor 
layer. Provision of two or more conductive polymer layers can enhance the 
antistatic properties of the resulting screen. 
The radiographic intensifying screen of the invention is described in 
detail hereinafter referring to the screen shown in FIG. 4-(1). 
The radiographic intensifying screen of the invention can be prepared, for 
instance, by the following process. 
The support material employable for the screen can be selected from the 
same support materials as described in the preparation of the 
aforementioned radiation image storage panel, and preferred is a plastic 
film. The plastic film may contain a light-absorbing material such as 
carbon black or a light-reflecting material such as titanium dioxide. 
The radiographic intensifying screen of the invention may have other 
additional layers such as an adhesive layer, a light-reflecting layer and 
a light-absorbing layer, as well as in the case of the radiation image 
storage panel. Further, the screen may be provided with finely protruded 
and depressed portions on its phosphor layer-side surface for the 
enhancement of sharpness of an image provided by the screen, as described 
in Japanese Patent Provisional Publication No. 58(1983)-182599. 
Subsequently, on the support is provided a phosphor layer. The phosphor 
layer comprises a binder and phosphor particles dispersed therein. 
A variety of phosphors employable for the intensifying screen have been 
known, and any one of them can be used in the invention. Examples of the 
phosphor preferably employable in the invention, which emits light in the 
ultraviolet to visible region (blue region, green region and red region) 
include: 
tungstate phosphors such as CaWO.sub.4, MgWO.sub.4 and CaWO.sub.4 :Pb; 
terbium activated rare earth oxysulfide phosphors such as Y.sub.2 O.sub.2 
S:Tb, Gd.sub.2 O.sub.2 S:Tb, La.sub.2 O.sub.2 S:Tb, (Y,Gd).sub.2 O.sub.2 
S:Tb and (Y,Gd).sub.2 O.sub.2 S:Tb,Tm; 
terbium activated rare earth phosphate phosphors such as YPO.sub.4 :Tb, 
GdPO.sub.4 :Tb and LaPO.sub.4 :Tb; 
terbium activated rare earth oxyhalide phosphors such as LaOBr:Tb, 
LaOBr:Tb,Tm, LaOCl:Tb, LaOCl:Tb,Tm, GdOBr:Tb and GdOCl:Tb; 
thulium activated rare earth oxyhalide phosphors such as LaOBr:Tm and 
LaOCl:Tm; 
barium sulfate phosphors such as BaSO.sub.4 :Pb, BaSO.sub.4 :Eu.sup.2+ and 
(Ba,Sr)SO.sub.4 :Eu.sup.2+ ; 
divalent europium activated alkaline earth metal phosphate phosphors such 
as Ba.sub.3 (PO.sub.4).sub.2 :Eu.sup.2+ and (Ba,Sr).sub.3 (PO.sub.4).sub.2 
:Eu.sup.2+ ; 
divalent europium activated alkaline earth metal fluorohalide phosphors 
such as BaFCl:Eu.sup.2+, BaFBr:Eu.sup.2+, BaFCl:Eu.sup.2+,Tb, 
BaFBr:Eu.sup.2+,Tb, BaF.sub.2.BaCl.sub.2.KCl:Eu.sup.2+, 
BaF.sub.2.BaCl.sub.2.xBaSO.sub.4.KCl:Eu.sup.2+ and 
(Ba,Mg)F.sub.2.BaCl.sub.2.KCl:Eu.sup.2+ ; 
iodide phosphors such as CsI:Na, CsI:Tl, NaI:Tl and KI:Tl; 
sulfide phosphors such as ZnS:Ag, (Zn,Cd)S:Ag, (Zn,Cd)S:Cu and 
(Zn,Cd)S:Cu,Al; 
hafnium phosphate phosphors such as HfP.sub.2 O.sub.7 :Cu; 
europium activated rare earth oxysulfide phosphors such as Y.sub.2 O.sub.2 
:Eu, Gd.sub.2 O.sub.2 S:Eu, La.sub.2 O.sub.2 S:Eu and (Y,Gd).sub.2 O.sub.2 
S:Eu; 
europium activated rare earth oxide phosphors such as Y.sub.2 O.sub.3 :Eu, 
Gd.sub.2 O.sub.3 :Eu, La.sub.2 O.sub.3 :Eu and (Y,Gd).sub.2 O.sub.3 :Eu; 
europium activated rare earth phosphate phosphors such as YPO.sub.4 :Eu, 
GdPO.sub.4 :Eu and LaPO.sub.4 :Eu; and 
europium activated rare earth vanadate phosphors such as YVO.sub.4 :Eu, 
GdVO.sub.4 :Eu, LaVO.sub.4 :Eu and (Y,Gd)VO.sub.4 :Eu. 
The above-described phosphors are given by no means to restrict the 
phosphor employable in the intensifying screen of the invention. Any other 
phosphors can be also employed, provided that the phosphor emits light 
having a wavelength within near ultraviolet to visible region when exposed 
to a radiation such as X-rays. 
As the binder employable for the phosphor layer of the radiographic 
intensifying screen, there can be mentioned those used in the preparation 
of the radiation image storage panel. 
The phosphor layer can be prepared in the similar manner to that in the 
preparation of a stimulable phosphor layer of the radiation image storage 
panel. In more detail, the above-mentioned phosphor and binder are 
dispersed in an appropriate solvent to prepare a coating dispersion; the 
coating dispersion is evenly applied onto the support; and the coated 
layer of the dispersion is dried to form a phosphor layer on the support. 
The solvent can be selected from those used in the preparation of the 
stimulable phosphor layer of the radiation image storage panel. The ratio 
between the binder and the phosphor is generally in the range of 1:1 to 
1:100 (binder:phosphor, by weight) and preferably in the range of 1:8 to 
1:40. The coating dispersion for the phosphor layer may contain various 
additives such as a dispersing agent for improving dispersibility of the 
phosphor particles therein and a plasticizer for enhancing the bonding 
between the phosphor particles and the binder in the phosphor layer. As 
the dispersing agent and plasticizer to be incorporated into the coating 
dispersion, there can be mentioned those described in the preparation of 
the radiation image storage panel. The coating of the dispersion can be 
performed by a known coating method such as a method of using a doctor 
blade, a roll coater and a knife coater, as the in preparation of the 
radiation image storage panel. The thickness of the phosphor layer is 
generally in the range of 20 .mu.m to 1 mm, preferably in the range of 50 
to 500 .mu.m. 
On the surface of the phosphor layer not facing the support is then 
provided a conductive polymer layer. 
A material employable for the conductive polymer layer is a conductive 
polymer, and the conductive polymer has the same meaning as defined in the 
case of the radiation image storage panel. Examples of the conductive 
polymer include the same polymers as used in the preparation of a 
conductive polymer layer of the radiation image storage panel. The 
conductive polymer layer can be prepared in the same manner as described 
in the preparation of the conductive polymer layer of the radiation image 
storage panel. The thickness of the conductive polymer layer is generally 
in the range of 0.1 to 20 .mu.m, preferably in the range of 0.5 to 5.0 
.mu.m. By adjusting the thickness of the conductive polymer layer in the 
abovespecified range, the surface resistivity (resistance) of the layer 
can be set to not higher than 10.sup.9 ohm. The conductive polymer layer 
may further contain a known electrically conductive material such as a 
surfactant. 
On the surface of the conductive polymer layer, a transparent film is 
provided to protect the screen physically and chemically. 
The transparent protective film can be formed on the conductive polymer 
layer using the same material and the same process as described in the 
preparation of a transparent protective film for the radiation image 
storage panel. The thickness of the transparent protective film is 
generally in the range of approx. 1 to 30 .mu.m. 
Thus, a radiographic intensifying screen shown in FIG. 4-(1) can be 
prepared. 
A radiographic intensifying screen of FIG. 4-(2) can be obtained by forming 
a protective film on the phosphor layer and then providing a conductive 
polymer layer on the protective film, or initially forming a conductive 
polymer layer on a transparent thin film (protective film) and combining 
the thin film and the phosphor layer. 
A radiographic intensifying screen of FIG. 4-(3) can be obtained by forming 
a conductive polymer layer on the beforehand prepared phosphor layer and 
combining the resulting composite material and an independently prepared 
support in such a manner that the conductive polymer layer faces the 
support. In this case, the conductive polymer used for the preparation of 
a conductive polymer layer can be incorporated with other additives such 
as an adhesive agent, a polymer for an undercoating layer, a 
light-reflecting material and a light-absorbing material to form a 
conductive polymer layer, whereby the resulting conductive polymer layer 
also serves as an adhesive layer, an undercoating layer, a 
light-reflecting layer or a light-absorbing layer. 
The radiographic intensifying screen consisting of a support, a phosphor 
layer, a transparent protective film and a conductive polymer layer is 
described above, but the transparent protective film is not always 
necessary in the invention. 
The radiographic intensifying screen of the invention may be provided with 
a covering made of a conductive material on the edge portion. In this 
case, the screen can be grounded or electrically connected to an earth by 
way of the covering. The conductive covering serves as a ground lead (a 
kind of a ground member) between the conductive polymer layer and a ground 
conductor (i.e., earth means), and the covering is provided at least one 
part of the edge portion of the screen. 
FIG. 5 is a perspective view illustrating an embodiment of a radiographic 
intensifying screen obtained by providing a conductive covering at the 
edge portion of the screen of FIG. 4-(1). FIG. 5-(A) is a sectional view 
taken along the line I--I of FIG. 5. 
As shown in FIGS. 5 and 5-(A), the sides of the edge portion 51 of the 
screen are provided with several covering 52a made of an electrically 
conductive material (e.g., paste containing metal powder of tin, aluminum 
and silver) in the form of spots. Further, the back surface (support side 
surface) of the edge portion 51 of the screen is provided with a covering 
52b made of an electrically conductive material (e.g., tin, aluminum, 
silver or a paste containing a powder thereof) in the form of a tape which 
is in contact with the spot covering 52a. In the radiographic intensifying 
screen of the invention, the spot covering 52a and the tape covering 52b 
are generically named herein to a conductive covering 52. Through the 
conductive covering, into the conductive polymer layer can be introduced 
the opposite static charge to the static charge generating on the surface 
of the screen from the outside of the screen. 
In the case of setting the screen in a cassette or a high-speed 
radiographic apparatus, the cassette or the apparatus may be preferably 
provided with an earth means 53 made of a silver tape, etc. on the part 
where the cassette or the apparatus is brought into contact with the 
conductive covering 52b, as shown in FIG. 5. 
The conductive covering can be provided by coating the conductive material 
onto the conductive polymer layer or combining the material with the 
conductive polymer layer using an adhesive agent. 
In the radiographic intensifying screen of the invention, the conductive 
covering is required to be provided to be brought into contact with the 
conductive polymer layer. The conductive covering may be provided in such 
a manner that the covering covers whole the edge portion of the screen. 
The conductive covering in the form of a tape may be provided on only the 
earth and the required position of the cassette or the high-speed 
radiographic apparatus without providing on the screen. 
The following examples further illustrate the present invention, but these 
examples are understood to by no means restrict the invention. 
EXAMPLE 1 
To a mixture of a powdery divalent europium activated barium fluorobromide 
(BaFBr:0.001Eu.sup.2+) stimulable phosphor and a linear polyester resin 
were added successively methyl ethyl ketone and nitrocellulose (nitration 
degree: 11.5%), to prepare a dispersion containing the phosphor and the 
binder. Subsequently, tricresyl phosphate, n-butanol and methyl ethyl 
ketone were added to the dispersion. The mixture was sufficiently stirred 
by means of a propeller agitator to obtain a homogeneous coating 
dispersion having a mixing ratio of 1:20 (binder:phosphor, by weight) and 
a viscosity of 25-30 PS (at 25.degree. C.). 
The coating dispersion was applied onto a polyethylene terephthalate sheet 
containing carbon black (support, thickness: 250 .mu.m) placed 
horizontally on a glass plate. The application of the coating dispersion 
was carried out using a doctor blade. The support having a layer of the 
coating dispersion was then placed in an oven and heated at a temperature 
gradually rising from 25.degree. to 100.degree. C. to dry the coated layer 
of the dispersion. Thus, a phosphor layer having a thickness of 250 .mu.m 
was formed on the support. 
Independently, to 50 parts by weight of a conductive acrylic resin (trade 
name: Corcort NR-121, available from Corcort Co., Ltd.) was added methyl 
ethyl ketone, to prepare a coating solution containing the conductive 
acrylic resin. 
The obtained coating solution was applied onto the phosphor layer and dried 
in the same manner as described above, to form a conductive polymer layer 
having a thickness of 2 .mu.m on the phosphor layer. 
On the conductive polymer layer was placed a transparent polyethylene 
terephthalate film (thickness: 10 .mu.m; provided with a polyester 
adhesive layer on one surface) to combine the transparent film and the 
conductive polymer layer with the adhesive layer. 
Thus, a radiation image storage panel consisting essentially of a support, 
a phosphor layer, a conductive polymer layer and a transparent protective 
film, superposed in order, was prepared (see FIG. 1-(1)). 
EXAMPLE 2 
The procedure of Example 1 was repeated except for providing a transparent 
protective film on the phosphor layer and then providing a conductive 
polymer layer on the transparent protective film, to prepare a radiation 
image storage panel consisting essentially of a support, a phosphor layer, 
a transparent protective film and a conductive polymer layer, superposed 
in order (see FIG. 1-(2)). 
EXAMPLE 3 
The procedure of Example 1 was repeated except for forming a phosphor layer 
on a transparent polyethylene terephthalate film, then providing a 
conductive polymer layer on the phosphor layer and combining the polymer 
layer and an adhesive layer (a polyester adhesive layer, thickness: 
approx. 10 .mu.m) having been beforehand provided on the support, to 
prepare a radiation image storage panel consisting essentially of a 
support, a conductive polymer layer, a phosphor layer and a transparent 
protective film, superposed in order (see FIG. 1-(3)). 
EXAMPLE 4 
The procedure of Example 1 was repeated except for forming a conductive 
polymer layer on one surface of the support and then providing 
successively a phosphor layer on the surface of the support not facing the 
polymer layer and a transparent protective film on the phosphor layer, to 
prepare a radiation image storage panel consisting essentially of a 
conductive polymer layer, a support, a phosphor layer and a transparent 
protective film, superposed in order (see FIG. 1-(4)). 
EXAMPLE 5 
The procedure of Example 1 was repeated except for providing a back layer 
on one surface of the support by combining an oriented polypropylene film 
(thickness: 20 .mu.m) and the support through an adhesive layer, then 
providing a conductive polymer layer on the back layer, and providing 
successively a phosphor layer on the surface of the support not facing the 
polymer layer and a transparent protective film on the phosphor layer, to 
prepare a radiation image storage panel consisting essentially of a 
conductive polymer layer, a back layer, a support, a phosphor layer and a 
transparent protective film, superposed in order (see FIG. 1-(5)). 
COMISON EXAMPLE 1 
The procedure of Example 1 was repeated except for not providing a 
conductive polymer layer, to prepare a radiation image storage panel 
consisting essentially of a support, a phosphor layer and a transparent 
protective film, superposed in order. 
The radiation image storage panels obtained in Examples 1 to 5 and 
Comparison Example 1 were evaluated on the transfer property and the 
occurrence of uneveness of images provided by the panels by the following 
tests. 
Transfer property 
The evaluation on the transfer property of the radiation image storage 
panel was done by using a static electricity testing device shown in FIG. 
3. 
FIG. 3 is schematically illustrates a static electricity testing device. 
The device comprises transferring means 31, 31' and an electric potential 
measuring means (static charge gauge) 32. Each of the transferring means 
31, 31' comprises rolls 33a, 33b made of urethane rubber, an endless belt 
34 supported by the rolls and an assisting roll 35 made of phenol resin. 
The electric potential measuring means 32 comprises a detector 36, a 
voltage indicator 37 connected to the detector and a recorder 38. 
The evaluation was carried out by introducing the radiation image storage 
panel into the transferring means 31, 31', subjecting the panel to the 
repeated transferring procedures of 100 times in the right and left 
directions (directions indicated by arrows in FIG. 3), then bringing the 
surface of the panel (protective film-side surface) into contact with the 
detector 36 to measure the electric potential (KV) on the surface of the 
panel. 
The results are set forth in Table 1. 
Occurrence of uneveness of image 
A radiation image storage panel having been exposed to X-rays was 
introduced into the static electricity testing device (placed in a dark 
room), and the panel was subjected to the repeated transferring procedures 
of 10 times in the same manner as described above. Then, the panel was 
subjected to a radiation image recording and reproducing method. The 
evaluation of the occurrence of uneveness of the resulting image was done 
by observing occurrence of a noise (i.e., static mark caused by static 
discharge). This test was conducted in an atmosphere of a temperature of 
10.degree. C. and a relative humidity of 20%, and the radiation image 
recording and reproducing method was carried out using a radiation image 
reading apparatus (FCR101, produced by Fuji Photo Film Co., Ltd.). 
The results are also set forth in Table 1. 
TABLE 1 
______________________________________ 
Surface Potential 
Occurrence of 
(KV) Static Mark 
______________________________________ 
Example 1 -0.5 not observed 
Example 2 -0.2 not observed 
Example 3 -0.6 not observed 
Example 4 -1.0 not observed 
Example 5 -l.0 not observed 
Com. Example 1 
-7.0 observed 
(many static marks) 
______________________________________ 
As is evident from the results set forth in Table 1, each of the radiation 
image storage panels provided with a conductive polymer layer according to 
the invention (Examples 1 to 5) had a small potential difference on the 
surface, and nostatic mark was observed on the image formed by the panels 
of the invention. Accordingly, the panels of the invention were remarkably 
improved in the antistatic property. On the other hand, the radiation 
image storage panel provided with no conductive polymer layer (Comparison 
Example 1) had a large potential difference on the surface, and a great 
number of static marks were observed on the image provided by the panel. 
Thus, the panel for comparison had electricity with a large quantity of 
static charge. 
EXAMPLE 6 
To a mixture of a powdery terbium activated gadolinium oxysulfide (Gd.sub.2 
O.sub.2 S:Tb) phosphor and 80 parts by weight of a linear polyester resin 
(trade name: Vylon #500, available from Toyobo Co., Ltd.) were added 
successively methyl ethyl ketone, 15 parts by weight of nitrocellulose 
(nitration degree: 11.5%) and 5 parts by weight of isocyanate (trade name: 
Smidule N-75, available from Sumitomo Bayer Urethane Co., Ltd.). The 
mixture was sufficiently stirred by means of a propeller agitator to 
obtain a homogeneous coating dispersion having a mixing ratio of 1:16 
(binder:phosphor, by weight) and a viscosity of 25-30 PS (at 25.degree. 
C.). 
The coating dispersion was applied onto a polyethylene terephthalate sheet 
containing carbon black (support, thickness: 250 .mu.m) placed 
horizontally on a glass plate. The application of the coating dispersion 
was carried out using a doctor blade. The support having a layer of the 
coating dispersion was then placed in an oven and heated at a temperature 
gradually rising from 25.degree. to 100.degree. C. to dry the coated layer 
of the dispersion. Thus, a phosphor layer having a thickness of 150 .mu.m 
was formed on the support. 
Independently, to 50 parts by weight of a conductive acrylic resin (trade 
name: Corcort NR-121, available from Corcort Co., Ltd) was added methyl 
ethyl ketone, to prepare a coating solution containing the conductive 
acrylic resin. 
The obtained coating solution was applied onto the phosphor layer and dried 
in the same manner as described above, to form a conductive polymer layer 
having a thickness of 2 .mu.m on the phosphor layer. 
On the conductive polymer layer was placed a transparent polyethylene 
terephthalate film (thickness: 12 .mu.m; provided with a polyester 
adhesive layer on one surface) to combine the transparent film and the 
conductive polymer layer with the adhesive layer. 
Thus, a radiographic intensifying screen consisting essentially of a 
support, a phosphor layer and a transparent protective film, superposed in 
order, was prepared (see FIG. 4-(1)). 
COMISON EXAMPLE 2 
A commercially available radiographic intensifying screen not provided with 
a conductive polymer layer (trade name: G-8, available from Fuji Medical 
Co. Ltd.) was obtained for comparison. 
The radiographic intensifying screens of Example 6 and Comparison Example 2 
were evaluated on the quantity of electricity (quantity of static charge) 
on the surface and the antistatic property according to the following 
tests using a transferring apparatus for testing shown in FIG. 6. The 
transferring apparatus for testing is a model of a radiographic apparatus 
for angiocardiography which will be described hereinbelow. 
FIG. 6 is a schematic sectional view illustrating the transferring 
apparatus for testing. 
Quantity of electricity on the surface 
To a portion of the protective film-side surface of the radiographic 
intensifying screen was attached a tin foil, to measure the quantity of 
static charge on the surface of the screen. 
In the transferring apparatus for testing shown in FIG. 6, radiographic 
intensifying screens 61a and 61b, each provided with a tin foil 65, are 
fixed in the apparatus in such a manner that those screens face to each 
other at a certain space, and a radiographic film 62 (trade name: NEW 
RXO-G, available from Fuji Photo Film Co., Ltd.) is moved into a position 
between the screens at a constant speed (180 m/min, same speed as that of 
a commercially available radiographic apparatus for angiocardiography) by 
means of rollers 63a, 63b. The tin foil 65 is connected to an electrometer 
64 (trade name: TR-8651, produced by Takeda Riken Co., Ltd.). 
On the surface of the radiographic film 62 is induced a static charge in 
proportion to the static charge electrified on the surface of the screen 
61a. For example, when a negative charge is electrified on the surface of 
the screen 31a, a positive charge is induced on the surface of the film 
62. By beforehand insulating the rollers 63a, 63b, the same quantity of 
static charge as that of the positive charge is introduced into the film 
62 via the tin foil 65 from the electrometer 64 provided on the surface of 
the screen. On the electrometer 64 is recorded the change of the quantity 
of electricity with time (i.e., the same quantity and opposite charge to 
that flowing out from the electrometer, corresponding to the quantity of 
the static charge on the screen surface). 
The results are set forth in Table 2, in which the quantity of electricity 
is expressed by the maximum value (Q MAX(C)) in the obtained values. 
Antistatic Property 
The evaluation on the antistatic properties of the screen was done by 
observing occurrence of noise (static mark) on the radiographic film 
caused by the static charge induced on the film. The expression "noise on 
the film" used herein means an exposed portion of the film after the 
developing procedure followed by the the transferring procedure using the 
above-mentioned transferring apparatus for testing. The results of the 
evaluation are classified into the following: 
A: no static mark is observed; 
B: almost no static mark is observed; 
C: some static marks are observed; and 
D: a great number of static marks are observed. 
The results are also set forth in Table 2. 
TABLE 2 
______________________________________ 
Quantity of Electricity 
Occurrence of 
(Q MAX (C)) Static Mark 
______________________________________ 
Example 6 0.3 .times. 10.sup.-9 
B 
Com. Example 2 
2.2 .times. 10.sup.-9 
D 
______________________________________ 
As is evident from the results set forth in Table 2, a radiographic 
intensifying screen having a conductive polymer layer according to the 
invention (Example 6) was reduced in the quantity of electricity (static 
charge) to approx. 1/7 of that in the commercially available radiographic 
intensifying screen provided with no conductive polymer layer (Comparison 
Example 2), and further the screen of the invention gave less occurrence 
of static mark on the radiographic film as compared with the screen for 
comparison. 
EXAMPLE 7 
The procedure of Example 6 was repeated except for providing a transparent 
protective film on the phosphor layer and then providing a conductive 
polymer layer on the transparent protective film, to prepare a 
radiographic intensifying screen consisting essentially of a support, a 
phosphor layer, a transparent protective film and a conductive polymer 
layer, superposed in order (see FIG. 4-(2)). 
EXAMPLE 8 
The procedure of Example 6 was repeated except for providing a conductive 
polymer layer on the support and then providing successively a phosphor 
layer on the conductive polymer layer and a transparent protective film on 
the phosphor layer, to prepare a radiographic intensifying screen 
consisting essentially of a support, a conductive polymer layer, a 
phosphor layer and a transparent protective film, superposed in order (see 
FIG. 4-(3)). 
The radiographic intensifying screens obtained in Examples 6 to 8 and 
Comparison Example 2 were evaluated on the electric voltage given on the 
surface thereof and the antistatic properties according to the following 
tests using a cassette shown in FIG. 7. 
FIG. 7 is a perspective view illustrating a cassette encasing a pair of 
radiographic intensifying screens and a radiographic film therein. 
The cassette comprises a case 71 and a lid 72, and radiographic 
intensifying screens 73a, 73b are arranged in the cassette in such a 
manner that the screen 73a is in close contact with the lid 72 (upper 
portion) and the screen 73b is in close contact with the case 71 (lower 
portion). A radiographic film 74 is encased in the cassette in such a 
manner that the film is sandwiched between the screen 73a and the screen 
73b. 
Electric voltage on the surface of the screen 
A pair of radiographic intensifying screens were arranged in the cassette 
in the same manner as described above, and then a commercially available 
radiographic film having been subjected to an antistatic treatment was 
repeatedly moved between the screens at 30 times to rub the surfaces of 
the film with the surface of each screen. Subsequently, another commercial 
radiographic film (trade name: NEW RXO-G, available from Fuji Photo Film 
Co., Ltd.) was stored in the cassette for 5 minutes in such a manner that 
the film was sandwiched in the screens, and then the film was taken out of 
the cassette. After the film was taken out of the cassette, the surfaces 
of both screens were measured on the electric voltage (V). The measurement 
of the electric voltage was made by means of a voltage indicator 
(electrostatic voltmeter, produced by Treck Co., Ltd.) in such a manner 
that the probe of the voltmeter was arranged at a distance of 2.2 mm from 
the surface of the screen and horizontally to the surface thereof. 
The results are set forth in Table 3. 
Antistatic property 
The evaluation on the antistatic properties of the screen was done by 
observing occurrence of static mark on the radiographic film after 
completion of the developing procedure in the same manner as described 
hereinbefore. 
The results are also set forth in Table 3. 
TABLE 3 
______________________________________ 
Electric Voltage (V) 
Occurrence of 
Upper Screen 
Lower Screen 
Static Mark 
______________________________________ 
Example 6 
-147 -157 B 
Example 7 
0 0 A 
Example 8 
-780 -809 C 
Com. -1,000 -1,000 D 
Example 2 
______________________________________ 
As is evident from the results set forth in Table 3, each of the 
radiographic intensifying screens having a conductive polymer layer 
according to the invention (Examples 6 to 8) showed an extremely lower 
voltage than that of the commercial radiographic intensifying screen 
provided with no conductive polymer layer (Comparison Example 2), and 
further the screens of the invention gave less occurrence of static mark 
on the radiographic film as compared with the screen for comparison. 
EXAMPLE 9 
The procedure of Example 6 was repeated except for providing a conductive 
covering made of a silver paste and a covering made of a silver tape on 
the edge portion of the screen, and grounding the screen by way of the 
tape, to prepare a radiographic intensifying screen consisting essentially 
of a support, a phosphor layer, a conductive polymer layer and a 
transparent protective film, superposed in order, and further provided 
with conductive covering (see FIG. 5-(A)). 
COMISON EXAMPLE 3 
A radiographic intensifying screen obtained by coating an antistatic agent 
(trade name: Fuji AS Cleaner, available from Fuji Photo Film Co., Ltd.) 
onto the surface of the protective film of the radiographic intensifying 
screen in Comparison Example 2 was prepared. 
The radiographic intensifying screens prepared in Example 9 and Comparison 
Example 3 were evaluated on the electric voltage on their surfaces and the 
antistatic property using the above-mentioned cassette in the same manner 
as described above. 
The results on the evaluations are set forth in Table 4. 
TABLE 4 
______________________________________ 
Electric Voltage (V) 
Occurrence of 
Upper Screen 
Lower Screen 
Static Mark 
______________________________________ 
Example 9 
-10 0 A 
Com. -93 -164 B 
Example 3 
______________________________________ 
As is evident from the results set forth in Table 4, the radiographic 
intensifying screen having a conductive polymer layer and further provided 
with a conductive covering according to the invention (Example 9) showed 
an extremely lower voltage than that of the commercially available 
radiographic intensifying screen coated with an antistatic agent 
(Comparison Example 3), and further the screen of the invention gave less 
occurrence of static mark on the radiographic film as compared with the 
screen for comparison. 
The radiographic intensifying screens obtained in Example 6 and 9 were 
further evaluated on the electric voltage electrified on the surface 
thereof and the antistatic property according to the following tests using 
a radiographic apparatus for angiocardiography. 
Electric voltage on the surface of the screen 
A pair of radiographic intensifying screens were fixed in a radiographic 
apparatus for angiocardiography (Siemens-AOT, produced by Siemens Co., 
Ltd.) at a predetermined position, and then a commercially available 
radiographic film (trade name: NEW RXO-G, available from Fuji Photo Film 
Co., Ltd.) was moved continuously and automatically between the screens, 
to measure the electric voltage (V) on the surfaces of both screens (upper 
screen and lower screen) in the same manner as described before. 
The results are set forth in Table 5. 
Antistatic property 
The evaluation on the antistatic property of the screen was done by 
observing occurrence of static mark on the radiographic film in the same 
manner as described above. 
The results are also set forth in Table 5. 
TABLE 5 
______________________________________ 
Electric Voltage (V) 
Occurrence of 
Upper Screen 
Lower Screen 
Static Mark 
______________________________________ 
Example 6 
-28 -11 A 
Example 9 
-270 +30 B 
______________________________________ 
As is evident from the results set forth in Table 5, each of the 
radiographic intensifying screen having a conductive polymer layer and 
provided with a conductive covering according to the invention (Example 9) 
and the radiographic intensifying screen having a conductive polymer layer 
but not provided with a conductive covering also according to the 
invention (Example 6) showed an extremely low voltage. Further, occurrence 
of static mark was never or hardly observed in the radiographic film with 
respect to the screens of the invention.