Radiation imagery chemistry: process – composition – or product th – Thermographic process – Heat applied after imaging
Reexamination Certificate
2002-03-06
2003-03-18
Chea, Thorl (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Thermographic process
Heat applied after imaging
C430S531000, C430S619000, C430S620000, C430S945000
Reexamination Certificate
active
06534251
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a silver salt photothermographic dry image forming material and an image recording method thereof.
BACKGROUND OF THE INVENTION
Heretofore, in the medical diagnosis and printing plate making fields, effluent resulting from wet type processing for image forming materials has become problematic in terms of workability, and in recent years, from the viewpoint of environmental protection as well as space saving, a decrease in processing effluent has been highly demanded.
Accordingly, it has been requested to develop a technology, employing photothermographic materials, for use in photographic techniques in which efficient exposure can be performed utilizing laser imagers and image setters, and can form clear, high resolution black-and-white images.
Silver salt photothermographic dry imaging materials (hereinafter, also referred to simply as photosensitive materials), which are comprised of organic silver salts, photosensitive silver halides and reducing agents on a support, as a technique to meet said demand, are disclosed, for example, in U.S. Pat. Nos. 3,152,904 and 3,487,075 by D. Morgan and B. Shely, and “Dry Silver Photographic Materials” (Handbook of Imaging Materials, Marcel Dekker Inc., page 48, 1991) edited by D. H. Klosterboer. Since no solution-form processing chemicals are used in the silver salt photothermographic dry imaging material, users can be provided with a system which is simpler and not deteriorating environment.
These silver salt photothermographic dry imaging materials are characterized in that photosensitive silver halide grains provided in the photosensitive layer are utilized as a light sensor, and organic silver salts are utilized as the silver ion supplying source, so that images are formed by conducting heat development commonly at 80 to 140° C., employing incorporated reducing agents, without the requirement of fixing the image.
However, since the silver salt photothermographic dry imaging material is comprised of organic silver salts, photosensitive silver halide grains and reducing agents, fogging tends to result during storage prior to the heat development. Further, problems occur in which image quality, such as silver image tone, is varied easily by formation of metal silver due to heat and light, when images are stored for a long period of time, because the whole or a part of silver halides, organic silver salts and reducing agents, etc. remain together even after the heat development, due to that the photosensitive material is subjected to only heat development generally at 80 to 250° C. without being fixed after exposure.
Techniques to over come these problems are disclosed in documents such as JP-A 6-208192 (hereinafter, JP-A refers to an unexamined and published Japanese Patent Application), 8-267934, U.S. Pat. No. 5,714,311, and the references cited therein. However, even though these disclosed techniques exhibit some desirable effects, they are not sufficient to satisfy market demand.
On the other hand, further enhancement of image quality has been demanded as a so-called everlasting matter to be solved in silver salt photothermographic dry imaging materials. Specifically, in the field of medical diagnostic imaging, higher image quality which enables more accurate diagnosis has been demanded.
Accordingly, the invention has been applied in view of the foregoing problems, and the object of the invention is to provide a silver salt photothermographic dry imaging material, which exhibits enhanced sensitivity, minimized fogging and superior raw stock stability as well as superior silver image lasting quality after heat development, and an image recording method using the same.
SUMMARY OF THE INVENTION
The object of the invention has been achieved by the following embodiments.
(1) A silver salt photothermographic dry imaging material comprising a support having thereon a photosensitive layer comprising silver aliphatic carboxylate grains and photosensitive silver halide grains, a reducing agent for silver ions, a binder and a cross-linking agent, wherein the. photothermographic material has a silver coverage of 1.0 to 1.7 g/m
2
; the photosensitive silver halide grains have a mean grain size of 0.03 to 0.055 &mgr;m and a degree of grain size dispersity of not more than 30%; after the dry imaging material has been subjected to photothermographic processing at a temperature of 100 to 200° C. for 5 to 50 seconds, the photosensitive layer exhibits a thermal transition temperature of 46 to 200° C.
(2) A silver salt photothermographic dry imaging material comprising a support having thereon a photosensitive layer comprising silver aliphatic carboxylate grains and photosensitive silver halide grains, a reducing agent for silver ions, a binder and a cross-linking agent, wherein the photothermographic material has a silver coverage of 1.0 to 1.7 g/m
2
; the silver aliphatic carboxylate grains have a mean equivalent circle diameter of 0.05 to 0.8 &mgr;m and a mean grain thickness of 0.005 to 0.07 &mgr;m; and the photosensitive layer, after being subjected to photothermographic processing at a temperature of 100 to 200° C. for 5 to 50 seconds, exhibits a thermal transition temperature of 46 to 200° C.
(3) The silver salt photothermographic dry imaging material of item 1, wherein the silver aliphatic carboxylate grains are formed in the presence of a compound capable of functioning as a crystal growth retarder or a dispersant for the silver aliphatic carboxylate grains.
(4) The silver salt photothermographic dry imaging material of item 1, wherein the binder exhibits a glass transition temperature (Tg) of 70 to 105° C.
(5) The silver salt photothermographic dry imaging material of item 3, wherein the compound capable of functioning as a crystal growth retarder or a dispersant is an alcohol having not more than 10 carbon atoms.
(6) The silver salt photothermographic dry imaging material of item 3, wherein the compound capable of functioning as a crystal growth retarder or a dispersant is a branched aliphatic carboxilic acid or an unsaturated aliphatic carboxilic acid.
(7) The silver salt photothermographic dry imaging material of item 3, wherein the compound capable of functioning as a crystal growth retarder or a dispersant is gelatin or polyvinyl alcohol.
(8) The silver salt photothermographic dry imaging material of item 1, wherein a silver saving agent is incorporated in the photosensitive layer or a non-photosensitive layer.
(9) The silver salt photothermographic dry imaging material of item 1, wherein the photosensitive layer comprises at least two layers.
(10) The silver salt photothermographic dry imaging material of item 1, wherein the photothermographic material, after subjected to thermal development, has a hue angle h
ab
of 180°<h
ab
<270°.
(11) An image recording method of the silver salt photothermographic dry imaging material of item 1, which comprises the steps of:
(a) exposing the photothermographic material with a laser light scanning exposure apparatus, in which a scanning laser light is a longitudinal multiple mode;
(b) bringing the laser exposed photothermographic material into proximity with a heat source;
(c) thermally developing the laser exposed photothermographic material; and
(d) removing the thermally developed photothermographic material from the heat source.
DETAILED DESCRIPTION OF THE INVENTION
The invention will now be detailed below.
The photosensitive silver halide grains (also referred to simply as silver halide grains) in the invention will now be explained. The photosensitive silver halide grains in the invention means the silver halide grains, which essentially are capable of absorbing light as an intrinsic characteristic of a silver halide crystal or artificially capable of absorbing visible light or infrared light by physicochemical methods and are treated and prepared so as to cause physicochemical change in the interior and/or at the surface of said silver halide crystal can occur when the crystal absorbs any light within the wavelengths region from ultra
Maeda Keiko
Shima Tetsuo
Bierman, Muserlian and Lucas
Chea Thorl
Konica Corporation
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