Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Structurally defined
Reexamination Certificate
2000-06-13
2001-08-28
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Structurally defined
C430S403000, C430S404000
Reexamination Certificate
active
06280913
ABSTRACT:
FIELD OF THE INVENTION
This invention pertains to photographic elements, and in particular to photographic elements incorporating photographically useful compounds stabilized using ion exchange polymers, a method of activating the photographically useful compound, a method of processing said photographic element, a sheet which optionally contains a photographically useful compound stabilized using ion exchange polymers, and methods of processing a photographic element in the presence of said sheet.
BACKGROUND OF THE INVENTION
It is well known in the art that the introduction of photographically useful compounds, such as photographic couplers, development inhibitors, base, base precursors, fixing agents, i.e., ligand capable of binding silver, silver stabilizing agents and the like, into photographic elements can lead to premature reaction of the photographically useful compound with the other components of the photographic element.
One embodiment of this invention relates to photographic processing and, in particular to a method of fixing employing a fixer sheet that can be laminated to a photographic material to be processed. In conventional photographic processing it is usual to form an image by developing an imagewise exposed silver halide photographic material and then removing the unexposed (and undeveloped) silver halide with a fixer solution. The fixer solution contains a silver halide solvent, typically an alkali metal or ammonium thiosulphate, which forms soluble complexes with the silver halide which then pass into the solution thus leaving the photographic material substantially free of silver halide. The silver salt diffusion transfer process is also well known and provides a black-and-white image by placing an imagewise exposed silver halide material in face-to-face contact with a receiving layer in the presence of a silver halide solvent, a silver halide developing agent and silver precipitating nuclei. In the initial developing phase, a silver image is developed in the silver halide material while, in a second phase, undeveloped silver halide is transported as a soluble complex with the silver halide solvent to the receiving layer where metallic silver is deposited adjacent to the silver precipitating nuclei having been formed by reduction of the solubilised silver halide by developing agent.
In a variation of the above processes it is known to process photographic materials by placing them in face-to-face contact with a receiver sheet in the presence of a developing agent and a silver halide solvent. A recent example of such a process is described in U.S. Pat. No. 4,775,614 in which receiver sheets comprise a water-absorbing polymer layer, silver precipitating nuclei and a silver halide solvent. U.S. Pat. No. 3,179,517 describes a method of fixing black-and-white materials by lamination to a receptor element wherein, inter alia, zinc sulphide is used as a silver ion precipitating agent. The precipitation reaction in this case being a conversion reaction (metathesis). In this reaction the silver halide is converted to silver sulphide and the zinc sulphide to zinc halide.
U.S. Pat. No. 4,480,025 describes the bleaching and fixing of a developed color silver halide photographic material by using a bleach-fix sheet comprising a water-supplying layer, a bleaching agent, a silver halide solvent and a dye mordant. The particular use exemplified is to bleach and fix a color diffusion transfer material so that the retained image is usable. This system operates at an acid pH and contains an oxidizing agent to achieve the bleaching of silver.
Applying the concept of fixing by lamination to a camera speed film material, presents special problems. Due to the practice of using high silver halide levels coupled with partial development of the grains (a technique employed to achieve the best granularity) there are high levels of silver halide to remove. This leads to incomplete removal of silver halide when using previously suggested systems. U.S. Pat. No. 5,478,703 overcomes this deficiency by providing a method of fixing a developed photographic silver halide material comprising at least 2 silver halide layers sensitized to different regions of the spectrum, comprising placing the material in face-to-face contact with a fixer sheet in the presence of a processing solution and a silver halide solvent which forms a solubilised silver halide species from the undeveloped areas of the material, wherein the fixer sheet contains reducing means capable of forming metallic silver therein from the solubilised silver halide. The provision of a means of fixing a photographic film or other material which avoids the need for a separate fixing bath with its associated difficulties of silver recovery or disposal when exhausted is useful. The process can also operate with lower levels of silver halide solvent than conventional fixing baths, and can result in less escape of fixing agent into the environment. The fixer sheet can also conveniently be sent away for recovery and recycling of the silver. An important further advantage of the invention over conventional fixing baths is that it allows products of photographic color processing to be trapped in the receiver sheet and therefore not discharged into the environment. This is particularly valuable for smaller scale photofinishing operations where full-scale pollution control equipment to treat their effluent would be too costly and inconvenient. The silver halide solvent, such as sodium thiosulphate, which is necessary for the process, may be coated in whole or part in the fixing sheet.
Other variations of photographic processing using dry photographic processing elements have been described in the art. In one technique a single processing element is brought into contact with the photosensitive film to carry out photographic development. U.S. Pat. No. 5,440,366 to Reiss and Cocco teaches a photographic processing system and method wherein individual dry photographic processing elements are sequentially wrapped onto a single processing spool.
While there has been interest in carrying out photographic processing of exposed photosensitive film with dry processing elements, the systems and methods described in the prior art have not been entirely satisfactory insofar as providing the desired results. Accordingly, there is a continuing need for novel and improved systems and methods for forming images in exposed photosensitive films using dry photographic processing materials.
Silver halide photothermographic imaging materials, especially “dry silver” compositions, processed with heat and without liquid development have been known in the art for many years. Such materials are a mixture of light insensitive silver salt of an organic acid (e.g., silver behenate), a minor amount of catalytic light sensitive silver halide, and a reducing agent for the silver source. The light sensitive silver halide is in catalytic proximity to the light insensitive silver salt such that the latent image formed by the irradiation of the silver halide serves as a catalyst nucleus for the oxidation-reduction reaction of the organic silver salt with the reducing agent when heated above 80° C. Such media are described in U.S. Pat. Nos. 3,457,075; 3,839,049; and 4,260,677. Toning agents can be incorporated to improve the color of the silver image of photothermographic emulsions as described in U.S. Pat. Nos. 3,846,136; 3,994,732 and 4,021,249. Various methods to produce dye images and multicolor images with photographic color couplers and leuco dyes are well known in the art as represented by U.S. Pat. Nos. 4,022,617; 3,531,286; 3,180,731; 3,761,270; 4,460,681; 4,883,747 and Research Disclosure 29963.
A common problem that exists with these photothermographic systems is the instability of the image following processing. The photoactive silver halide still present in the developed image may continue to catalyze print-out of metallic silver even during room light handling. Thus, there exists a need for stabilization of the unreacted silver halide with the addition of sep
Irving Lyn M.
Irving Mark E.
Noonan John M.
Eastman Kodak Company
Le Hoa Van
Rice Edith A.
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