Radiation imagery chemistry: process – composition – or product th – Nonradiation sensitive image processing compositions or... – Developer
Reexamination Certificate
2001-06-29
2003-01-21
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Nonradiation sensitive image processing compositions or...
Developer
Reexamination Certificate
active
06509143
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to novel photographic processing compositions. In particular, it relates to concentrated photographic color developing compositions that reduce stain resulting from residual sensitizing dyes. This invention is useful in the photographic industry.
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 visible 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 organic dye images produced from an oxidized color 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 using an oxidizing agent, commonly known as a bleaching agent. For some processing methods, these two functions can be performed in the same processing step in what is known as bleach-fixing.
Color photographic silver halide materials often contain various spectral sensitizing dyes that extend the inherent photosensitivity of the photosensitive silver halide emulsions to electromagnetic radiation. One important class of such spectral sensitizing dyes includes carbocyanine sensitizing dyes that are commonly included in silver halide emulsion layers in photographic silver halide films. For example they are often present in color reversal photographic silver halide films (films normally used to provide color positive images).
Many photographic silver halide elements contain residual spectral sensitizing dyes after photoprocessing. In some cases, the level of retained spectral sensitizing dyes is inconsequential and thus, unobservable. In other instances, however, the high level of retained spectral sensitizing dye results in undesirably high dye stain (or unwanted color) in the elements. This dye stain problem is aggravated when the silver halide elements are designed for shorter wet processing times, or when certain silver halide emulsions are used that require higher concentrations of sensitizing dyes.
A number of solutions have been proposed for this problem, including the inclusion of common water-soluble stilbene optical brighteners, such as diaminostilbene compounds, in various photographic processing compositions. For example, such compounds are known to be used in color developer compositions [as described for example, in
Research Disclosure,
20733, page 268, July, 1981 and U.S. Pat. No. 4,587,195 (Ishikawa et al.) and as commonly used in the commercial Process RA-4 color developing compositions available from a number of manufacturers], bleach-fixing compositions [as described for example, in JP Kokai 1-062642 (published Mar. 9, 1989), JP Kokai 1-158443 (published Jun. 21, 1989), and U.S. Pat. No. 5,043,253 (Ishikawa)], or dye stabilizing compositions used at the end of the color photographic 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 U.S. Pat. No. 6,153,365 (Goswami et al.) and U.S. Pat. No. 6,153,364 (Goswami et al.) 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 processing compositions.
A preferred class of solubilized stain reducing agents are used in the concentrated fixing photographic fixing compositions described in U.S. Ser. No. 09/680,385 (filed Oct. 5, 2000 by Buongiorne, Craver, and Goswami).
However, when we attempted to incorporate some of these stain reducing agents into concentrated solutions such as concentrated color developing 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 color developing compositions.
There remains a need in the photographic industry for a way to decrease the dye stains resulting from retained sensitizing dye during color development using concentrated color developing compositions that meet all manufacturing, customer use, and storage stability requirements.
SUMMARY OF THE INVENTION
The problems noted above are overcome using a concentrated aqueous color developing composition having a pH of from about 11 to about 13 and comprising:
a) at least 0.08 mol/l of a color developing agent in free base form, and
b) at least 0.009 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.
In addition, the present invention includes a method for providing a color image comprising color developing an imagewise exposed color silver halide photographic element using the concentrated aqueous color developing composition described above with or without dilution.
The advantages of this invention are several. The compounds that are used as spectral sensitizing dye stain reducing agents are highly soluble in concentrated aqueous color developing compositions. Their inherent fluorescence is relatively less than known compounds so that fluorescence is not a problem when the compound cannot be removed from the photographic material or processing composition.
Only the specific stain reducing agents represented by Structure I provide the desired stability in the concentrated aqueous color developing compositions of this invention. Thus, the compounds of Structure I have low temperature solubility that is determined by placing 100 ml aqueous samples of the compounds in closed containers and holding them individually it at 0° F. (−18° C.), 20° F. (−7° C.), 30° F. (−1° C.), 40° F. (4° C.) and 50° F. (10° C.) for 14 days and then observing the samples 24 hours later for signs of precipitation or other observable changes (for example color, presence of haze, or phase separation).
Working strength color developing compositions can be prepared using the concentrated composition of the present invention by diluting them in an appropriate manner for photoprocessing use. Alternatively, the concentrated composition of this invention can be used “as is”, without dilution.
DETAILED DESCRIPTION OF THE INVENTION
For obtaining color images, photographic processing methods include at the least, a color development step, a bleaching step, a fixing step (or a combined bleach-fixing step), and a rinsing or color stabilizing step. Some of the processing methods will include additional steps, for example a black-and-white developing step and pre-bl
Buongiorne Jean M.
Craver Mary E.
Goswami Ramanuj
Eastman Kodak Company
Le Hoa Van
Tucker J. Lanny
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