Radiation imagery chemistry: process – composition – or product th – Thermographic process – Heat applied after imaging
Reexamination Certificate
2002-11-13
2004-06-15
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Thermographic process
Heat applied after imaging
C430S512000, C430S517000, C430S522000, C430S617000, C430S619000
Reexamination Certificate
active
06749999
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a photothermographic material exhibiting superior image storability and sharpness as well as little residual color after development and an image formation method utilizing the same.
RELATED ART
Photothermographic materials have been proposed since old days and described in, for example, U.S. Pat. Nos. 3,152,904 3,457,075 and B. Shely, “Thermally Processed Silver Systems” in Imaging Processes and Materials, Neblette, 8th Ed., Ed. by Sturge, V. Walworth and A. Shepp, page 2, 1969.
Photothermographic materials generally have a photosensitive layer containing a catalytic amount of photocatalyst (e.g., silver halide), a reducing agent, a reducible silver salt (e.g., silver salt of an organic acid) and a toning agent for controlling silver color tone, which are dispersed in a binder matrix. After being exposed imagewise, photothermographic materials are heated at an elevated temperature (e.g., 80° C. or higher) and thereby an oxidation/reduction reaction is caused between the silver halide or the reducible silver salt (functioning as an oxidizing agent) and the reducing agent to form a black silver image. The oxidation/reduction reaction is promoted by the catalytic action of a latent image of silver halide produced by the exposure. Therefore, the black silver image is formed in the exposed area.
Heat development does not require processing solutions as used in the wet development processing and has an advantage of easy and quick processing. However, the heat development suffers from unsolved problems that never occur with the wet development.
One of the problems is the problem concerning image storability. That is, since image formation systems based on heat development utilizing a silver salt of an organic acid do not require a fixation process, image storability after development, especially degradation of print out by irradiation with light, constitutes a serious problem. As means for improving the print out, methods of using AgI formed by conversion of a silver salt of an organic acid are disclosed in U.S. Pat. No. 6,143,488 and EP922,995. However, the methods of converting a silver salt of an organic acid with iodine as disclosed in those references cannot provide satisfactory sensitivity and thus cannot constitute actually usable systems.
In addition, photosensitive materials utilizing AgI are also described in International Patent Publications WO97/48014, WO97/48015, U.S. Pat. No. 6,165,705, Japanese Patent Laid-open Publication (Kokai, referred to as JP-A hereinafter) No. 8-297345, Japanese Patent No. 2,785,129 and so forth. However, any of these cannot achieve sensitivity and fog of sufficient levels, and they cannot be practically used as photosensitive materials for exposure with lasers. In general, it is essential to incorporate a dye into silver halide photosensitive materials for preventing halation or irradiation in order to improve image sharpness. Such a dye must function upon exposing imagewise, but must not impart any color to the formed images after it functions. Therefore, a dye used in photothermographic materials is required to have an optical function of absorbing light at a wavelength used for exposure of silver halide emulsion as well as a property that it is unlikely to be detected in the meaning of luminosity factor or a function of being removed from the photographic light-sensitive materials or being decolorized by development.
A photothermographic material for exposure with blue laser is disclosed in JP-A-2000-305213. However, satisfactory design is not disclosed against reduction of sharpness due to scattering of laser light, and the photosensitive material disclosed in this reference shows poor sharpness.
In order to improve image storability of photothermographic materials, various means for improving developing agents, additives, binders and so forth have been examined. However, any photothermographic material showing satisfactory image storability comparable to that of photosensitive materials of wet development type has not been developed so far. Further, while such functions as described above are required for dyes used in photothermographic materials, dyes having such functions, especially such dyes absorbing blue lights, have not been proposed yet thus far.
SUMMARY OF THE INVENTION
The present invention was accomplished in view of the aforementioned various problems, and its object is to provide a photothermographic material that exhibits high image storability and can form an image of superior sharpness and little residual color. Another object of the present invention is to provide an image formation method that can form an image of high image storability, superior sharpness and little residual color.
In order to achieve the aforementioned objects, the photothermographic material of the present invention is a photothermographic material comprising a support, a photosensitive layer containing a silver halide having a silver iodide content of 10 mol % or more and a reducing agent and a non-photosensitive layer provided on the support, wherein at least one of the photosensitive layer and the non-photosensitive layer contains a dye showing an absorption maximum in a wavelength range of 350 nm to 430 nm.
As preferred embodiments of the present invention, there are provided the aforementioned photothermographic material, wherein the silver iodide content of the silver halide is 40% or more; the aforementioned photothermographic material, which further contains a decolorizing agent in at least one of the photosensitive layer and the non-photosensitive layer; and the aforementioned photothermographic material, wherein the dye is in a state of solid microparticle dispersion or in an aggregated state.
As preferred embodiments of the present invention, there are also provided the aforementioned photothermographic material, wherein the dye has a polymethine chromophore; the aforementioned photothermographic material, wherein the dye is a polymethine dye of intramolecular cyclization type that is cyclized by an action of a base and thereby decolorized; and the aforementioned photothermographic material, wherein the dye is a polymethine dye having a polymethine group and a group that can form a nucleophilic moiety by an action of a base at a position where the group can form a 5- to 7-membered ring through a reaction with the polymethine group.
As a preferred embodiment of the present invention, there is further provided the aforementioned photothermographic material, wherein the dye is represented by the following formula (1) or (2).
In the formulas, R
1
represents a hydrogen atom, an aliphatic group, an aromatic group, —NR
21
R
26
, —OR
21
or —SR
21
, where R
21
and R
26
each independently represent a hydrogen atom, an aliphatic group or an aromatic group, or R
21
and R
26
bond to each other to form a nitrogen-containing heterocyclic ring. R
2
represents a hydrogen atom, an aliphatic group or an aromatic group, and R
1
and R
2
may bond to each other to form a 5- or 6-membered ring. L
1
and L
2
each independently represent a substituted or unsubstituted methine, and substituents of the methine may bond to each other to form an unsaturated aliphatic ring or unsaturated heterocyclic ring. Z
1
represents a group required to complete a 5- or 6-membered nitrogen-containing heterocyclic ring, an aromatic ring may condense to the nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring and a condensed ring thereof may have a substituent. A represents an acidic nucleus, and B represents an aromatic group, an unsaturated heterocyclic ring group or a group of the following formula (3). n and m each represent 1, 2 or 3.
In the formula (3), L
3
represents a substituted or unsubstituted methine, and it may bond to L
2
to form an unsaturated aliphatic ring or an unsaturated heterocyclic ring. R
3
represents an aliphatic group or an aromatic group. Z
2
represents a group required to complete a 5- or 6-membered nitrogen-containing heterocyclic ring, an aromatic ring may con
Inoue Rikio
Suzuki Ryo
Yabuki Yoshiharu
Yamane Katsutoshi
Fuji Photo Film Co. , Ltd.
Schilling Richard L.
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