Radiation imagery chemistry: process – composition – or product th – Post imaging processing – With structural limitation
Reexamination Certificate
2002-04-29
2003-08-12
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Post imaging processing
With structural limitation
C430S429000, C430S458000
Reexamination Certificate
active
06605419
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method and material for photographic processing.
BACKGROUND OF THE INVENTION
The basic image-forming process of photography comprises the exposure of a silver halide photographic recording material, such as a color film, to electromagnetic radiation, and the chemical processing of the exposed material to provide a useful image. Chemical processing involves two fundamental steps. The first is treatment of the exposed silver halide material with a developing agent wherein some or all of the silver ion is reduced to metallic silver, and in the case of color materials, a dye image is formed (because of a color developing agent).
For color materials, a second fundamental step is the removal of silver metal by one or more steps of bleaching and fixing so that only a dye image remains in the processed material. During bleaching, the developed silver is oxidized to a silver salt by a suitable bleaching agent. The oxidized silver is then dissolved and removed from the material using a fixing agent or silver solvent in a fixing step. In the case of a film that is to be scanned, however, the bleach stage may be omitted. In the case of black-and-white materials, the fixing step is only to remove silver halide.
Additional photoprocessing steps may be needed including rinsing or dye stabilization that require even more photoprocessing chemicals. In the case of color reversal materials, additional photoprocessing steps include black-and-white development, a reversal step, pre-bleaching or conditioning step and one or more rinsing steps.
All of these photoprocessing steps require preparation of the photoprocessing compositions (whether in aqueous or solid form), large or small photoprocessing tanks or reservoirs to hold the compositions, and disposal or regeneration of the “spent” compositions once a predetermined amount of exposed material has been processed. All of these operations require considerable manufacturing effort, shipping and handling of chemicals and aqueous solutions, replenishment of the solutions, and disposal of solutions into the environment.
These characteristics of conventional photoprocessing are labor intensive, tedious, costly and potentially harmful to the environment (although much work has been accomplished in the industry to make the compositions more environmentally “friendly”). Recent digital technologies in the photographic industry offer advantages in that they can enable the user to manipulate the images after photochemical processing by scanning to create a digital representation of the image. One of these advantages is the ability to readjust the exposure by automatic tone scaling to correct for either over or underexposure. Other uses of digitization are to crop, enlarge or otherwise modify the image, or to send the image to other users electronically for various purposes. The growing awareness of digitization of photographic images provides almost limitless possibilities for image manipulation for various purposes in a number of industries.
Our copending UK Patent application No 0014422.0 describes a method of providing an image in an imagewise exposed photographic silver halide material comprising at least one silver halide emulsion layer which method comprises developing the silver halide and fixing the remaining silver halide by contacting it with a molten composition comprising a silver halide complexing agent which is present in sufficient amount to render the silver halide substantially clear. The method is carried out under substantially dry conditions that is without water having to be provided in addition to the fixing agent and unlike conventional fixing there is no requirement for the silver halide complex formed to be removed from the emulsion layer.
PROBLEM TO BE SOLVED BY THE INVENTION
There is a continuing need to reduce the number of stages in the overall photographic development process. The present invention provides a process which enables the wash stage that conventionally follows the fixing stage to be eliminated by contacting the photographic material with a solid complexing agent for the silver halide to transfer complexing agent to the photographic material and, by the application of heat, causing the complexing agent react with the silver halide.
SUMMARY OF THE INVENTION
The present invention comprises a method of providing an image in an imagewise exposed photographic silver halide material comprising at least one silver halide emulsion layer, the method comprising developing the silver halide and fixing the remaining silver halide by (i) contacting the photographic material with a composition comprising a solid complexing agent for the silver halide in the presence of a sufficient amount of water to transfer complexing agent to the surface of the emulsion layer and (ii) applying heat to cause the complexing agent to react with the silver halide to render it substantially clear.
ADVANTAGEOUS EFFECT OF THE INVENTION
The invention provides a process in which the wash stage that conventionally follows the fixing stage can be eliminated and replaces the conventional liquid fixing bath with a solid composition containing complexing agent.
The heat applied to effect the reaction between the complexing agent and the silver halide may also be employed to effect drying of the photographic material.
DETAILED DESCRIPTION OF THE INVENTION
The term fixing in the present specification is intended to include clearing. The transfer of the composition containing the complexing agent to the photographic material may be effected by a wiping action, that is, by a sliding contact between the two.
The term wiping is intended to include rubbing.
Water is present to facilitate the transfer and it is preferred that the surface of the solid complexing agent-containing composition is smooth. It is preferred that large amounts of water are not present and conveniently the photographic material after leaving the preceding bath (which will usually be awash) will be contacted by a squeegee or similar means to remove excess free water.
Preferably, the silver halide photographic material and the transferred silver halide complexing agent composition are heated to a temperature in the range from 40 to 170° C., more preferably from 70 to 150° C. Preferably the silver halide complexing agent-containing composition has melting point within the given temperature ranges.
It is convenient to heat the photographic material and transferred complexing agent to a temperature above the melting point of the complexing agent-containing composition.
It is not essential however to melt the complexing agent composition. For example imidazole having a melting point of 89 to 91 degrees C is effective in the present invention when heated to 82 degrees C.
If the complexing agent composition is heated to a temperature which is below its melting point, it is preferred that the temperature is not lower than about 20 degrees Centigrade below the melting point, more preferably not lower than 10 degrees below the melting point of the complexing agent containing composition.
The silver complexing agent may be a heterocyclic amine.
Preferably, the heterocyclic amine is a substituted or unsubstituted imidazole, pyrazole or triazole.
Particularly preferred silver complexing agents include imidazole and alkyl substituted imidazoles e.g. 2-methyl imidazole, 4-methyl imidazole, and 1,2-dimethyl imidazole.
Examples of other suitable heterocyclic amine silver complexing agents include benzimidazole; 1,2,4-triazole and substituted 1,2,4-triazoles e.g. 4-amino-1,2,4-triazole, 3-amino-1,2,4-triazole and 1,2,4-triazole-3-thiol; pyrazole; and 1-(hydroxyethyl)-tetrahydrotriazine-4-thiol.
The silver complexing agents may be used with a compound which co-melts with the complexing agent to provide a molten mixture in the desired temperature range. Examples of compounds which may be suitable as co-melters for the organic complexing agents listed above include amides such as benzamide (m.pt. 129° C.), p-toluamide (m.pt. 162° C.), anthranilamide (m.pt. 113° C.
Eastman Kodak Company
Le Hoa Van
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