Radiation imagery chemistry: process – composition – or product th – Stripping process or element – Element
Reexamination Certificate
2001-03-26
2002-11-05
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Stripping process or element
Element
C430S262000, C430S527000, C430S531000, C430S536000, C430S619000, C430S534000
Reexamination Certificate
active
06475697
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a photothermographic dry imaging material which exhibits high image quality as well as excellent storage stability, and excellent re-usability of resources, and specifically to a silver salt black-and-white photothermographic dry imaging material which exhibits excellent layer adhesion as well as excellent adhesive properties of its photosensitive layer and its backing layer after heat development, excellent silver image storage stability, and easy separation of an emulsion layer from a support.
BACKGROUND OF THE INVENTION
Heretofore, in the medical and printing plate making fields, effluent resulting from wet type processing for image forming materials became 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, demanded have been techniques, regarding photothermographic materials, for use in photographic techniques in which efficient exposure can be performed utilizing laser imagers and image setters, and can form clear black-and-white images at high resolution.
As described, for example, in U.S. Pat. Nos. 3,152,904 and 3,487,075, as well as in D. Morgan, “Dry Silver Photographic Materials”, (Handbook of Imaging Materials, Marcel Dekker, Inc., page 48, 1991), photothermographic dry imaging materials (heat developable photosensitive materials), comprising a support having thereon organic silver salts, photosensitive silver halide grains, and reducing agents, have been known. Since such photothermographic dry imaging materials do not at all use a solution basically comprised of processing chemicals, it is possible to provide customers with a system which is simple, and does not pollute the environment.
Incidentally, these photothermographic dry imaging materials comprise a support having thereon a photosensitive layer, which forms images by thermally developing, commonly at 80 to 140° C., organic silver salts as the supply source of silver ions, utilizing incorporated reducing agents and photosensitive silver grains as the light sensor, and a backing layer comprising dyes to absorb the laser beam. It is required that these layers firmly adhere onto said support not only before thermal development, but also after the same. Silver halide photosensitive photographic materials commonly comprise a support having thereon a sublayer, to allow a photosensitive layer, a backing layer or an intermediate layer to adhere to said support. In heat developable photosensitive materials, a sublayer is effectively provided to assure said adhesion. However, when the sublayer of heat developable materials is designed, consideration specific to thermal development, which is different from photosensitive materials which are developed utilizing conventional developers, is required.
For instance, since photothermographic dry imaging materials comprise organic silver salts, photosensitive silver halide grains, and reducing agents, fogging tends to result during storage prior to heat development as well as during heat development. Specifically, since said photosensitive layer deteriorates when exposed to water, it has been considered that in order to maintain the storage stability prior to development, also said sublayer is comprised of water insoluble materials. Furthermore, being different from photosensitive materials which employ gelatin as the major binder and are prepared by coating water based coating compositions, coating is carried out employing organic solvent based emulsion layer or backing layer coating compositions comprised in which hydrophobic binders are dissolved. Therefore, it is necessary to result in adhesive properties by proving a sublayer compatible with these layers. Furthermore, since heat development is carried out at a relatively high temperature, commonly being from 80 to 140° C., adhesion after heat development is required. In heat developable photosensitive materials as previously described, it is required that said sublayer exhibits high adhesive properties as well as hydrophobicity. On the other hand, when heat developable photosensitive materials are disposed of, in the same manner as photosensitive materials which are developed employing conventional developers, it is required that the emulsion layer be separated from the support so that silver and supports, which are valuable resources, are recovered to make it possible to effectively reutilize said recourses.
However, from the storage stability and adhesive properties of heat developable photosensitive materials, water insoluble subbing materials are required, while for separating the emulsion layer from the support, water-soluble subbing materials are required to ease processing. It has been very difficult to satisfy both requirements.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a photothermographic dry imaging material which exhibits high image quality, minimizes fogging, which occurs after extended storage of said photothermographic dry imaging material, and exhibits excellent adhesive properties of a backing layer with its support before and after heat development, and in addition exhibit easy separation of the emulsion layer from the support, and further, a method to separate the emulsion layer from the support.
The invention and its embodiment are descrbed.
1. A photothermographic dry imaging material comprising a support, a photosensitive layer containing at least an organic silver salt, photosensitive silver halide, a reducing agent and a binder, and a subbing layer containing a water-soluble polymer having a hydroxy group, provided on the support.
2. The photothermographic dry imaging material of item 1, wherein the water-soluble polymer is polyvinyl alcohol or a polymer comprising vinylalcohol unit.
3. The photothermographic dry imaging material of item 1, wherein the water-soluble polymer is ethylenically copolymerized polyvinyl alcohol.
4. The photothermographic dry imaging material of item 1, wherein the subbing layer comprises butyral resin.
5. The photothermographic dry imaging material of item 4, wherein the water-soluble polymer having a hydroxy group is polyvinyl alcohol.
6. The photothermographic dry imaging material of item 4, wherein the water-soluble polymer having a hydroxy group is ethylenically copolymerized polyvinyl alcohol.
7. The photothermographic dry imaging material of item 1, comprising a subbing layer containing a water-soluble polymer having a hydroxy group on both sides of the support.
8. The photothermographic dry imaging material of item 1, wherein the subbing layer is composed of two or more sublayers and the sublayer farthest from the support contains a water-soluble polymer having a hydroxy group.
9. The photothermographic dry imaging material of item 8, wherein a sublayer contacting to the support comprises polymer latex.
10. The photothermographic dry imaging material of item 1, wherein the subbing layer is composed of two or more sublayers, and at least one of the sublayers is electrically conductive.
11. The photothermographic dry imaging material of item 1, wherein the binder comprises a butyral resin.
12. The photothermographic dry imaging material of item 5, wherein the subbing layer on at least one side of the support is composed of two or more sublayer, and the sublayer farthest from the support contains the water-soluble polymer and an aqueous butyral resin.
13. The photothermographic dry imaging material of item 12, wherein a sublayer contacting to the support comprises polymer latex.
14. The photothermographic dry imaging material of item 5, wherein the subbing layer containing butyral resin is formed by coating composition containing liquid in which butyral resin is dispersed.
15. The photothermographic dry imaging material of item 4, wherein the butyral resin is particles having number average diameter of 50 to 1000 nm.
16. The photothermographic dry imaging material of item 15, wherein the butyral resin is contained i
Arimoto Tadashi
Kurachi Yasuo
Nakajima Akihisa
Sasaki Takayuki
Ueda Eiichi
Frishauf Holtz Goodman & Chick P.C.
Konica Corporation
Schilling Richard L.
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