Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2000-05-11
2001-12-25
Chea, Thorl (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S617000, C430S635000, C430S945000
Reexamination Certificate
active
06333147
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thermally processed image forming material and in particular to a photothermographic material.
RELATED ART
In recent years, a strong need for reducing the waste of processing solution has arisen in medical field from the viewpoints of environmental preservation and space saving. Thus desired is a technology related to a photothermographic material for medical diagnosis and graphic art use allowing efficient light exposure with a laser image setter or laser imager, and capable of providing a clear black image with a high resolution and sharpness. Such photothermographic material can provide the customer with a thermally-developing and processing without solution-base processing chemicals, allowing easy handling and no impact on the environment.
While a similar need has been occurring in the field of general image forming materials, images used in the medical diagnosis field specifically require a high image quality such as excellent sharpness and graininess for fine depiction, and prefer a blue-black tone for facilitating diagnoses. Although various hard copy system using pigment or dye, exemplified as an inkjet printer and electronic photograph system, are prevailing as a general image forming system, none of which is satisfactory as an output system for medical diagnosis images.
Other type of thermally processed image recording system using an organic silver salt and an agent for silver ion is known, for example, in U.S. Pat. Nos. 3,152,904 and 3,457,075 and “Thermally Processed Silver Systems” by D. Klosterboer, Imaging Processes and Materials, Neblette's 8th ed., edited by Sturge, V. Walworth and A. Shepp, chap.9, p.279, (1989). The photothermographic material generally has a photosensitive layer comprising a catalytic amount of photocatalyst (e.g., silver halide), reducing agent, reducible silver salt (e.g., organic silver salt), and an optional color toner for controlling color tone of silver image, all of which being dispersed in a binder matrix. The photothermographic material produces black silver image when heated, after light exposure, to a high temperature (e.g, 80° C. or above) through redox reaction between the silver halide or reducible silver salt and the reducing agent. Since the redox reaction is promoted by a catalytic action of a latent image on silver halide, which is generated by the light exposure, that the monotone silver image is formed in the exposed area. Such heat-assisted image forming system is disclosed in numbers of literatures typified by U.S. Pat. No. 2,910,377 and JP-B-43-4924 (the code “JP-B” as used herein means an “examined Japanese patent publication”), and can achieve a quality and tone satisfiable for medical diagnosis use.
A thermographic recording layer of such thermographic material and a non-recordable layer stacked thereon, or a photosensitive layer (photothermographic layer) of such photothermographic material and a non-photosensitive surface protective layer stacked thereon can be formed by simultaneous multi-layer coating. This method is strongly desired also from the viewpoint of cost reduction.
The simultaneous multi-layer coating has, however, been suffering from causing non-uniform coating due to streaks when effected in particular at a high speed (for example, 100 m/min or above), which has remained in further improvement.
SUMMARY OF THE INVENTION
In view of the problems in the prior art, an object of the present invention is to provide a thermally processed image forming material, for example a thermographic material and a photothermographic material, with an improved property of the coated surface, in particular coating streaks. More specifically, it is an object of the present invention to provide a photothermographic material for medical diagnoses with an improved coating streaks at the time of high-speed simultaneous multi-layer coating without degrading a maximum density.
The present inventors found after extensive investigations for solving the above problems that such generation of the coating streaks could be ascribable to a shock occurred around the interface during the simultaneous multi-layer coating due to the dicarboxylic acid contained in the non-recordable layer or non-photosensitive layer, and that the generation of the coating streaks could be successfully suppressed by controlling pH of the coating liquid, which led us to provide the present invention.
According to the present invention, provided is a thermally processed image forming material having on one side of a support at least one image recording layer containing at least one kind of non-photosensitive organic silver salt, a reducing agent for silver ion, nd a binder, characterized by having at least one non-recordable layer formed by coating and drying a coating liquid containing a dicarboxylic acid and having a pH of 3.5 or above.
In the present invention, water content of the total solvent in the coating liquid for forming the non-recordable layer is preferably 50 wt % or more, more preferably 80 wt % or more, still more preferably 95 to 100 wt %. The dicarboxylic acid is preferably selected from the group consisting of phthalic acids, maleic acids and naphthalenedicarboxylic acids, and more preferably selected from the group consisting of phthalic acid, 4-methylphthalic acid, 4-t-butylphthalic acid, 3-methylphthalic acid, 4,5-dimethylphthalic acid, 4-isopropylphthalic acid, 4-nitrophthalic acid, tetrachlorophthalic anhydride, maleic acid, and 2,3-naphthalenedicaroboxylic acid. The dicarboxylic acid is preferably contained in an amount of 1 to 2000 mg/m
2
, more preferably 30 to 1000 mg/m
2
in the non-recordable layer, particularly in a surface protective layer. PH of the coating liquid is preferably 3.5 to 5.0 and more preferably 3.5 to 4.5. In the present invention, the image recording layer and the non-recordable layer are formed by simultaneous multi-layer coating. According to one embodiment of the present invention, the material is a photothermographic material further containing at least one kind of photosensitive silver halide.
It was made possible by the present invention to provide a thermally processed image forming material, a coating streak defect of which being improved even when it is produced by simultaneous coating.
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments and actualization of the present invention will be detailed hereinafter
The thermally processed image forming material of the present invention has on one side of a support at least one image recording layer containing at least one kind of non-photosensitive organic silver salt, a reducing agent for silver ion, and a binder, characterized by having at least one non-recordable layer formed by coating and drying a coating liquid containing dicarboxylic acids and having a pH of 3.5 or above. Using the coating liquid with such pH value affords an excellent effect such that suppressing the generation of the coating streaks.
The thermally processed image forming material of the present invention has on one side of a support at least one image recording layer containing at least one kind of non-photosensitive organic silver salt, a reducing agent for silver ion, and binder. The thermally image forming material of the present invention involves a thermographic material which image recording layer is a thermographic layer and a photothermographic material which image forming layer is photothermographic layer further containing a photosensitive silver halide.
The dicarboxylic acid available for the present invention may be any compound having two carboxylic groups, and among which preferably are phthalic acids, maleic acids and naphthalenedicarboxylic acids, all of which being used as a color (toning agent). Examples of the dicarboxylic acid used in the present invention include phthalic acid, 4-methylphthalic acid, 4-t-butylphthalic acid, 3-methylphthalic acid, 4,5-dimethylphthalic acid, 4-isopropylphthalic acid, 4-nitrophthalic acid, tetrachlorophthalic anhydride, maleic acid, and 2,3-naphthalenedicarob
Birch & Stewart Kolasch & Birch, LLP
Chea Thorl
Fuji Photo Film Co. , Ltd.
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