Radiation imagery chemistry: process – composition – or product th – Nonradiation sensitive image processing compositions or... – Fixer
Reexamination Certificate
2002-06-05
2003-03-04
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Nonradiation sensitive image processing compositions or...
Fixer
Reexamination Certificate
active
06528242
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to novel concentrated photographic fixer additive and concentrated photographic fixing compositions. It also relates to methods of using these concentrated compositions in photoprocessing. Thus, this invention relates to the photographic industry and to photochemical processing in particular.
BACKGROUND OF THE INVENTION
The conventional image-forming process of silver halide photography includes imagewise exposure of a photographic silver halide recording material to actinic radiation (such as actinic light), and the eventual manifestation of a useable image by wet photochemical processing of that exposed material. A fundamental step of photochemical processing is the treatment of the material with one or more developing agents to reduce silver halide to silver metal. With black-and-white photographic materials, the metallic silver usually comprises the image. With color photographic materials, the useful image consists of one or more images in organic dyes produced from an oxidized developing agent formed wherever silver halide is reduced to metallic silver.
To obtain useful color images, it is usually necessary to remove all of the silver from the photographic element after color development. This is sometimes known as “desilvering”. Removal of silver is generally accomplished by oxidizing the metallic silver, and then dissolving it and undeveloped silver halide with a “solvent” or fixing agent in what is known as a fixing step. Oxidation is achieved with an oxidizing agent, commonly known as a bleaching agent.
Fixing is typically carried out using a fixing composition that includes one or more fixing agents such as thiosulfate salts. Both ammonium and sodium thiosulfate salts are known. Fixing solutions containing ammonium ions are preferred for providing more rapid fixing, but they present environmental concerns. Thus, fixing solutions containing sodium ions, while slower, are also advantageous.
Color photographic silver halide materials often contain various sensitizing dyes that extend the inherent photosensitivity of the photosensitive silver halide emulsions to electromagnetic radiation. One important class of such sensitizing dyes are carbocyanine sensitizing dyes that are commonly included in silver halide emulsion layers in photographic silver halide films, for example in color reversal photographic silver halide films (films normally used to provide positive color images).
Many photographic silver halide elements contain residual sensitizing dyes after photoprocessing. In some cases, the level of retained sensitizing dyes is inconsequential and thus, unobservable. In other instances, however, the high level of retained sensitizing dye results in undesirably high dye stain (or unwanted color) in the elements.
A number of solutions have been proposed for this problem, including the inclusion of water-soluble stilbene optical brighteners in the color developer solution [as described for example, in
Research Disclosure
, 20733, page 268, July, 1981 and U.S. Pat. No. 4,587,195 (Ishikawa et al)], the bleach-fixing solution [as described for example, in JP 1-062642 (published Mar. 9, 1989), JP 1-158443 (published Jun. 21, 1989), and U.S. Pat. No. 5,043,253 (Ishikawa)], or the stabilizing solution used at the end of the photoprocessing [as described for example in U.S. Pat. No. 4,895,786 (Kurematsu et al)].
Concentrated and working strength fixing compositions that solve the residual dye stain problem are described in U.S. Pat. No. 6,013,425 (Craver et al). These compositions contain certain triazinylstilbene compounds as stain reducing agents. While they are quite effective in this regard, keeping them in solution may require the presence of one or more water-soluble stabilizing compounds such as glycols.
The problems with residual sensitizing dyes have also been satisfactorily addressed by incorporating certain stain reducing agents into one or more working strength photographic processing compositions. These compounds are described in copending and commonly assigned U.S. Ser. No. 09/464,551 filed Dec. 16, 1999 by Goswami et al., now U.S. Pat. No. 6,153,365, and U.S. Ser. No. 09/464,961 filed Dec. 16, 1999 by Goswami et al., now U.S. Pat. No. 6,153,364, as colorless or slightly yellow compounds having an extended planar &pgr; system that is devoid of a diaminostilbene fragment or fused triazole nuclei. While these compounds can be incorporated into various photoprocessing compositions, it is preferred to include them in concentrated photographic fixing compositions.
However, when we attempted to incorporate some of these stain reducing agents into concentrated solutions such as concentrated fixing solutions, we found that some of them did not pass our rigorous solubility tests. For example, many of them showed unacceptable solubility even when organic solvents were added, insolubility in solution at low temperature for lengthy times, or insolubility in concentrated fixing composition.
There remains a need in the photographic industry for a way to decrease the dye stains resulting from retained sensitizing dye during photoprocessing using concentrated processing compositions that meet all manufacturing, customer use, and storage stability requirements.
SUMMARY OF THE INVENTION
The problems with known photographic compositions and photoprocessing methods are overcome with the use of the present invention.
In one embodiment, the present invention provides a concentrated aqueous fixer additive composition consisting essentially of:
a) at least 0.01 mol/l of a compound having the structure I
wherein R is carboxy or sulfo, m is an integer of from 0 to 5 and n is an integer of from 2 to 7, and
b) water.
This concentrated fixer additive composition can be used to advantage to prepare the concentrated aqueous fixing composition of this invention, which composition has a pH of 8 or less and consists essentially of:
a) at least 2 mol/l of a photographic fixing agent,
b) at least 0.0001 mol/l of a compound represented by Structure I noted above, and
c) water.
Once the concentrated aqueous fixing composition is prepared, it can be used to prepare an aqueous working strength fixer or replenisher. Thus, this invention further provides a method of making an aqueous working strength fixing composition comprising the steps of:
A) preparing the concentrated aqueous photographic fixing composition noted above by mixing the concentrated fixer additive composition described above with the photographic fixing agent, and
B) diluting the resulting concentrated aqueous photographic fixing composition from about 2 to about 15 times.
This invention further provides a method for providing a color image comprising:
A) bleaching an imagewise exposed and color developed color photographic silver halide element, and
B) prior to or after step A, fixing the photographic element with an aqueous working strength photographic fixing composition prepared from the concentrated fixing composition described above.
Step B of this method can also be carried out by diluting, at least 2 times, the concentrated aqueous photographic fixing composition described above.
The advantages of this invention are several. The concentrated fixer additive composition can be manufactured, provided and stored for considerable time without precipitation of the stain reducing agent, thereby reducing the costs associated with volume and storage. The fixer additive composition volume can be small enough so as not to significantly dilute the concentrate to which it is added. Because there is no need for solvents other than water, there is no additional environmental burden. The resulting working strength fixing composition is also highly stable, and can be used to advantage to reduce stain from retained sensitizing dyes in processing photographic silver halide elements.
Only the specific stain reducing agents represented by Structure I provide the desired stability in the concentrated compositions of this invention. Thus, the compounds of Structure I meet th
Buongiorne Jean M.
Craver Mary E.
Goswami Ramanuj
Eastman Kodak Company
Le Hoa Van
Tucker J. Lanny
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