Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2001-04-13
2002-07-23
Chea, Thorl (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S523000, C430S531000, C430S618000, C430S622000, C430S623000, C430S630000, C430S631000, C430S635000
Reexamination Certificate
active
06423487
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a thermally processed image recording material. In particular, the present invention relates to a thermally processed image recording material for scanners, image setters and so forth, which is particularly suitable for photographic art. More precisely, the present invention relates to a thermally processed image recording material that is free from “wrinkles (swelling)” and “cracks (cracking)” on the surface of the thermally processed image recording material, shows superior adhesion between images and support, and is suitable for color photographic art.
RELATED ART
As one of light exposure methods for photographic materials, there is known the so-called scanner type image-forming method, in which an original is scanned and light exposure is performed on a silver halide photographic material based on the obtained image signals to form a negative or positive image corresponding to an image of the original.
Further, there are desired photosensitive materials for scanners having ultrahigh contrast characteristics for cases in which images are directly printed on printing plates without reversing process after the signals are output from scanners onto films or for light sources of scanners having a soft beam profile.
There are known many photosensitive materials having a photosensitive layer on a support, with which image formation is attained by imagewise light exposure. These materials include those utilizing a technique of forming images by heat development as systems that can contribute to the environmental protection and simplify image-forming means.
In recent years, reduction of amount of waste processing solutions is strongly desired in the field of photographic art from the standpoints of environmental protection and space savings. Therefore, development of techniques relating to thermally processed image recording materials for photographic art is required, which materials enable efficient exposure by a laser scanner or laser image setter and formation of clear black images having high resolution and sharpness. Such thermally processed image recording materials can provide users with simpler and non-polluting heat development processing systems that eliminate the use of solution-type processing chemicals.
Methods for forming images by heat development are described in, for example, U.S. Pat. Nos. 3,152,904 and 3,457,075 and D. Klosterboer, “Thermally Processed Silver Systems A”, Imaging Processes and Materials, Neblette, 8th ed. compiled by J. Sturge, V. Walworth and A. Shepp, Chapter 9, p.279, (1989). Such thermally processed image recording materials comprise a reducible non-photosensitive silver source (e.g., silver salt of an organic acid), a photocatalyst (e.g., silver halide) in a catalytically active amount and a reducing agent for silver, which are usually dispersed in an organic binder matrix. While the photosensitive materials are stable at an ordinary temperature, when they are heated to a high temperature (e.g., 80° C. or higher) after light exposure, silver is produced through an oxidation-reduction reaction between the reducible silver source (which functions as an oxidizing agent) and the reducing agent. The oxidation-reduction reaction is accelerated by catalytic action of a latent image generated upon exposure. The silver produced from the reaction of the reducible silver salt in the exposed areas shows black color and provides contrast with respect to the non-exposed areas, and thus images are formed.
In many of conventionally known photothermographic materials, image-forming layers are formed by coating a coating solution using an organic solvent such as toluene, methyl ethyl ketone (MEK) and methanol as a solvent. However, not only use of an organic solvent as a solvent adversely affect human bodies during the production process, but also it is disadvantageous in view of cost because it requires process steps for recovery of the solvent and so forth.
Accordingly, methods of forming an image-forming layer by coating a coating solution using water as a solvent have been proposed. For example, Japanese Patent Laid-open Publication (Kokai, hereinafter referred to as JP-A) 49-52626, JP-A-53-116144 and so forth disclose image-forming layers utilizing gelatin as a binder, and JP-A-50-151138 discloses an image-forming layer utilizing polyvinyl alcohol as a binder. Furthermore, JP-A-60-61747 discloses an image-forming layer utilizing gelatin and polyvinyl alcohol in combination. As another example, JP-A-58-28737 discloses an image-forming layer utilizing a water-soluble polyvinyl acetal as a binder. If these binders are used, image-forming layers can be formed by using a coating solution comprising an aqueous solvent, and therefore considerable merits can be obtained with respect to environment and cost.
However, when a polymer such as gelatin, polyvinyl alcohol or water-soluble polyacetal is used as a binder, there is caused a problem that dehydration shrinkage of the binder and thermal expansion of the support simultaneously occur and thus wrinkles are generated on the film. Therefore, there can be obtained only films unsuitable for color printing, in which films are stacked in their use.
As methods for preventing the generation of wrinkles during heat development, techniques utilizing polymer latex as the binder are disclosed in JP-A-11-84573, JP-A-11-295845, Japanese Patent Application Nos. 11-91359, 11-143058, 11-187243 and so forth. These methods are superior methods for preventing the generation of wrinkles.
Coating solutions containing polymer latex as a binder are forcibly dried by heating after coating. However, coating solutions utilizing polymer latex, which is an aqueous dispersion of hydrophilic polymer, as a binder essentially involve a serious problem that they are likely to form films at surfaces of coated layers in the drying process after the coating and thus drying of internal portion becomes difficult to advance. If the drying temperature is elevated or volume of drying air is increased in order to advance the drying, “swelling” or “cracking” may be caused in the films. To prevent the “swelling” or “cracking”, coating must be performed with a reduced drying speed by lowering the drying temperature or decreasing the drying air volume. Therefore, in this field, it is an extremely important object to increase the speed to increase productivity and reduce energy cost.
Accordingly, an object of the present invention is to provide a thermally processed image recording material that can prevent the film formation at the surface, hence causes no “swelling” or “cracking”, during the drying by heating after coating of coating solution and shows superior adhesion between images and support.
DISCLOSURE OF THE INVENTION
The inventors of the present invention assiduously studied in order to achieve the aforementioned object. As a result; they found that the film formation phenomenon could be inhibited and hence superior thermally processed image recording materials that showed desired effects could be provided by thickening and gelling coating solutions through dry heating, and thus accomplished the present invention.
That is, the present invention provides a thermally processed image recording material having, on a support, an image-forming layer containing at least (a) a silver salt of an organic acid, (b) a reducing agent and (c) a photosensitive silver halide and at least one protective layer provided on the image-forming layer and comprising polymer latex as binders of the image-forming layer and the protective layer, wherein at least one of the image-forming layer and the protective layer contains a viscosity enhancer that increases viscosity of its aqueous solution when the solution is heated and temperature of the solution exceeds a certain transition temperature, and the viscosity enhancer is a polymer selected from the group consisting of polymers containing a (meth)acrylamide derivative represented by the following formula (1) or (2) in an amount of 50 weight % or more as constituent units:
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Chea Thorl
Fuji Photo Film Co. , Ltd.
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