Radiation imagery chemistry: process – composition – or product th – Color imaging process – Using identified radiation sensitive composition in the...
Reexamination Certificate
2001-11-15
2003-03-18
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Color imaging process
Using identified radiation sensitive composition in the...
C430S400000
Reexamination Certificate
active
06534253
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of using a single-part photographic bleach-fixing precursor composition for direct replenishment of a photographic bleach-fixing solution in the processing of photographic silver halide materials. In particular, this invention relates to the use of a single-part bleach-fixing precursor composition comprising predominantly ferrous-ligand complexes.
BACKGROUND OF THE INVENTION
The basic process for obtaining color images from exposed color photographic silver halide materials includes several steps of photochemical processing using appropriate photochemical compositions.
Photographic color developing compositions are used to process color photographic materials such as color photographic films and papers to provide the desired dye images early in the photoprocessing method. Such compositions generally contain color developing agents, for example 4-amino-3-methyl-N-(2-methane sulfonamidoethyl)aniline, as reducing agents to react with suitable color forming couplers to form the desired dyes. U.S. Pat. No. 4,892,804 (Vincent et al.) describes conventional color developing compositions that have had considerable commercial success in the photographic industry.
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 in what is known as a “bleaching” step using a bleaching agent, and then dissolving the oxidized silver and undeveloped silver halide with a silver “solvent” or fixing agent in what is known as a “fixing” step.
It has become common for the processing of certain photographic elements, notably color photographic papers, to combine the bleaching and fixing operations into a single “bleach-fixing” operation that can be carried out in one or more processing steps. Bleach-fixing is usually carried out using a composition that includes both a photographic bleaching agent and a photographic fixing agent, as described for example in U.S. Pat. No. 4,033,771 (Borton et al.).
The most common bleaching agents for color photographic processing are complexes of ferric [Fe(III)] ion and various organic chelating ligands (such as aminopolycarboxylic acids), of which there are hundreds of possibilities, all with varying photographic bleaching abilities and biodegradability. Common organic chelating ligands used as part of bleaching agents for photographic color film processing include ethylenediaminetetraacetic acid (EDTA), 1,3-propylenediaminetetraacetic acid (PDTA) and nitrilotriacetic acid (NTA).
Also known are bleaching, bleach-fixing compositions, and processing methods that utilize a ferric complex of one or more of several alkyliminodiacetic acids (such as methyliminodiacetic acid or MIDA) that are known to be more biodegradable than other common organic chelating ligands such as EDTA. Other photographic bleaching agents using similar organic chelating ligands are described in U.S. Pat. No. 5,061,608 (Foster et al.) in which the ferric bleaching agent is advantageously combined with specific aliphatic carboxylic acids to reduce dye stains.
Typical photographic fixing agents include thiosulfates, sulfites, thiocyanates, and mixtures thereof that readily solubilize or “dissolve” silver ion in the processed photographic materials, as described for example in U.S. Pat. No. 5,633,124 (Schmittou et al.).
As pointed out in U.S. Pat. No. 5,055,382 (Long et al.), when photographic materials are processed in bleach-fixing steps, the bleach-fixing composition is generally formulated from two or more “parts”, each “part” or solution typically containing one or more (but not all) of the photochemicals necessary for the processing reactions. For example, one of the “parts” usually contains the conventional ferric bleaching agent, and another of the “parts” usually contains a thiosulfate fixing agent(s) and a sulfite preservative. These “parts” are sometimes provided together in a photochemical processing “kit”. If all of the chemicals are formulated in a single concentrate solution, storage stability is reduced or nonexistent since unwanted chemical interactions among components are inevitable. For example, ferric bleaching agents, sulfite preservatives, and thiosulfate fixing agents are inherently reactive, thereby degrading solution effectiveness and storage stability. Thus, most common bleach-fixing solutions are provided from “two parts”, each part containing at least one essential reactive component.
Throughout the photographic industry, there is a desire to provide “concentrated” photoprocessing chemicals to reduce handling, transportation and storage costs. A number of successes have been achieved, for example by Eastman Kodak Company, to provide concentrated color developing compositions. The effort directed to providing concentrated bleach-fixing compositions, and especially in a single-part format, has encountered numerous hurdles.
However, successful bleach-fixing has been achieved using a single-part concentrated solution containing the precursor ferrous form of the bleaching agent, as described in copending and commonly assigned U.S. Ser. No. 09/723,794 (filed Nov. 28, 2000 by Vincent et al.).
This unique ferrous-ligand composition, however, is most useful in standard Process RA-4 (Color Paper) or Process C-41 (Color Negative Film) processing methods and equipment because there is sufficient aerial oxidation possible due to adequate contact of the composition with air in the replenishing and processing tanks. Thus, sufficient ferrous ion is oxidized to ferric ion in transit to or while in the bleach-fixing tank to provide adequate photographic bleaching.
Other processing methods and machines used in the industry are commonly known as “minilabs” that utilize “low volume thin tank” (LVTT) processing machines. Processing solutions are typically directly supplied to LVTT machines as “replenisher” solutions from enclosed containers (for example, those known as CUBITAINE® containers available from Hedwin Corporation). Some of these types of containers may be collapsible as described for example in U.S. Pat. No. 5,577,614 (Palmeroni, Jr. et al.). Since several processing solutions (and usually multiple parts to make solutions) are supplied to the LVTT machines directly from individual enclosed containers, the difficulty is that the various solutions may not be used at the same rate and residual solution may be left in some containers, creating disposal problems. In addition, multiple solution supply requires multiple pumping systems that increase the cost of processing and likely error in the amount of solution delivered.
It would be highly desirable to deliver fewer solutions, especially a single-part bleach-fixing solution, to LVTT processing machines. Yet, as pointed out above, conventional bleach-fixing solutions contain reactive components that are incompatible for long term storage. Since the unique ferrous bleach-fixing precursor solution described and claimed in U.S. Ser. No. 09/723,794 (noted above) was invented, opportunities have been sought for using it in various processing systems besides the more conventional “open tank” Process RA-4 systems. The desire was to use the ferrous bleach-fixing precursor solution in LVTT processing systems.
However, we encountered a new problem. The problem arises in that the enclosed containers used to supply processing solutions to LVTT machines and the inherent limited process surface area of LVTT machines provides insufficient air to facilitate the required oxidation of ferrous ion to ferric ion for successful bleaching. In addition, merely providing a high agitation of the ferrous solution would not accomplish the desired purpose because excessive aeration may cause sulfurization to occur.
There is a need in the industry to provide a single-part “bleach-fixing” direct replenisher solution to LVTT processing machines. It would be desirable to use the previously invented f
English Daniel R.
Kuykendall Valerie L.
Vincent Sheridan E.
Eastman Kodak Company
Le Hoa Van
Tucker J. Lanny
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