Radiation imagery chemistry: process – composition – or product th – Nonradiation sensitive image processing compositions or... – Fixer
Reexamination Certificate
2003-03-27
2004-04-27
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Nonradiation sensitive image processing compositions or...
Fixer
Reexamination Certificate
active
06727051
ABSTRACT:
FIELD OF THE INVENTION
This invention relates in general to photography. More particularly, it relates to a photographic bleach-fixing composition, and to a method of processing color photographic silver halide elements using that composition.
BACKGROUND OF THE INVENTION
The basic image-forming process of color silver halide photography comprises the exposure of a silver halide color photographic recording material to actinic radiation (such as light) and the manifestation of a useful image by wet chemical processing of the material. The fundamental steps of this wet processing include color development to reduce silver halide to silver and to produce dye images in exposed areas of the material. During or after bleaching to oxidize metallic silver to silver(I), the silver ion is generally removed by dissolving it in a silver solvent, commonly known as a fixing agent.
In some photochemical processes, bleaching and fixing are combined in a bleach-fixing step using a composition that includes both a bleaching agent to oxidize metallic silver and a fixing agent to dissolve the remaining silver ion, 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). Common color paper bleaching is often carried out using EDTA as a chelating ligand.
A wide variety of fixing agents and silver solvents are known, as described for example in U.S. Pat. No. 5,633,124 (Schmittou et al.) and publications noted therein. Thiosulfate salts are generally preferred as fixing agents because they are inexpensive, highly water soluble, non-toxic, non-odorous, and stable over a wide pH range. Thus, fixing is usually accomplished using a thiosulfate fixing agent that diffuses into the element, and forms silver thiosulfate complex that diffuses out of the element. In large photofinishing labs, the elements are usually immersed in a fixing solution for from 4 to 6 minutes. In small minilabs, the fixing time is shorter, that is from 90 to 120 seconds.
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 “part” usually contains the conventional ferric bleaching agent, and another “part” 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 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. Single-part bleach-fixing compositions are also desired for such reasons.
Thus, there is a need for a highly effective photographic bleach-fixing composition that has reduced odor and improved keeping stability.
SUMMARY OF THE INVENTION
This invention provides a photographic bleach-fixing composition that has a pH of from about 2 to about 9 when in aqueous form, and comprises:
at least 0.01 mol/l of a ferric-ligand bleaching agent,
at least 0.05 mol/l of a thiosulfate fixing agent,
at least 0.01 mol/l of sulfite ions, and
at least 0.025 mol/l of a phthalic acid or a salt thereof.
This invention also provides a method for providing a color photographic image comprising contacting a color developed color photographic silver halide material with the photographic bleach-fixing composition described above.
In another embodiment, a method for providing a color photographic image comprises:
A) color developing an imagewise exposed color photographic silver halide material in a predetermined volume of an aqueous color developing composition in a processing chamber, and
B) without removing the predetermined volume of the aqueous color developing composition or the color photographic silver halide material from the processing chamber, adding a predetermined volume of the photographic bleach-fixing composition described above to the processing chamber to provide a combined aqueous color development/bleach/fixing composition, and bleaching and fixing the color photographic silver halide material.
The photographic bleach-fixing composition of this invention has been shown to exhibit acceptable keeping stability and reduced odor without diminishing its photographic processing properties. These advantages are achieved by using a phthalic acid or a salt thereof in the bleach-fixing composition.
DETAILED DESCRIPTION OF THE INVENTION
Photographic bleach-fixing is carried out in one or more steps using one or more photographic bleaching agents that are Fe(III) complexes of carboxylic acids as a first essential component. Preferred carboxylic acid ligands include aminopolycarboxylic acid or polyaminopolycarboxylic acid chelating ligands. At least one of those steps is carried out using the bleach-fixing composition of this invention.
Useful iron-ligand complexes comprise one or more polycarboxylic acid chelating ligands. Particularly useful chelating ligands include conventional polyaminopolycarboxylic acids including ethylenediaminetetraacetic acid and others described in
Research Disclosure
, publication 38957, pages 592-639 (September 1996), U.S. Pat. No. 5,334,491 (Foster et al.), U.S. Pat. No. 5,582,958 (Buchanan et al.), and U.S. Pat. No. 5,753,423 (Buongiorne et al.).
Research Disclosure
is a publication of Kenneth Mason Publications Ltd., Dudley House, 12 North Street, Emsworth, Hampshire PO10 7DQ England. This reference will be referred to hereinafter as “
Research Disclosure
.” There are hundreds of possible chelating ligands that are known in the art, the most common ones being ethylenediaminetetraacetic acid (EDTA), 1,3-propylenediaminetetraacetic acid (PDTA), diethylenetriaminepentaacetic acid (DTPA), cyclohexanediaminetetraacetic acid (CDTA) and hydroxyethyl-ethylenediaminetriacetic acid (HEDTA).
Biodegradable chelating ligands are particularly desirable in order to minimize the impact on the environment from discharged photoprocessing solutions.
One particularly useful biodegradable chelating ligand is ethylenediaminedisuccinic acid (EDDS) as described in U.S. Pat. No. 5,679,501 (Seki et al.) and EP-0 532,001 B (Kuse et al.). All isomers of EDDS are useful, including the [S,S] isomer, and the isomers can be used singly or in mixtures. The [S,S] isomer is most preferred in the iron-EDDS complexes. Other useful disuccinic acid chelating ligands are described in U.S. Pat. No. 5,691,120 (Wilson et al.).
Aminomonosuccinic acids (or salts thereof) are chelating ligands having at least one nitrogen atom to which a succinic acid (or salt) group is attached. These chelating ligands are also useful in iron complexes. U.S. Pat. No. 5,652,085 (Stickland et al.) also provides more details about such chelating ligands, particularly the polyamino monosuccinic acids. Ethylenediamine monosuccinic acid (EDMS) is preferred in this class of chelating ligands.
Other classes of biodegradable aminopolycarb
Feller Therese M.
Haye Shirleyanne E.
Huston Janet M.
Schmittou Eric R.
Eastman Kodak Company
Le Hoa Van
Tucker J. Lanny
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