Radiation imagery chemistry: process – composition – or product th – Color imaging process
Reexamination Certificate
2003-10-27
2004-12-07
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Color imaging process
C430S393000, C430S401000, C430S430000
Reexamination Certificate
active
06828084
ABSTRACT:
FIELD OF THE INVENTION
This invention relates in general to photography. More particularly, it relates to a photographic bleaching composition, and to a method of processing photographic color materials 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.
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.
Throughout the photographic industry, there is a desire to provide photographic processing solutions that are safe and easy to use, photographically effective, and environmentally acceptable. One desirable property is that the solutions are not objectionable due to unpleasant odors. Despite the considerable useful photographic bleaching solutions and processing methods known in the art, there is a continuing need for a highly effective photographic bleaching composition that has reduced odor.
SUMMARY OF THE INVENTION
This invention provides a photographic bleaching 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 0.01 mol/l of a rehalogenating agent, and
at least 0.01 mol/l of a phthalic acid or a salt thereof.
In preferred embodiments, the present invention provides an aqueous bleaching composition having a pH of from about 3.5 to about 7 and comprising:
from about 0.01 to about 2 mol/l of a ferric-ligand complex bleaching agent,
from about 0.01 to about 1 mol/l of bromide ions, and
from about 0.01 to about 1 mol/l of sodium hydrogen phthalate, potassium hydrogen phthalate, or a mixture thereof.
In addition, a method of this invention for providing a color photographic image comprises contacting a color developed color photographic silver halide material with the photographic bleaching composition of this invention that is described above.
In addition, a method for providing a color photographic image comprises:
A) color developing an imagewise exposed color photographic silver halide material using a color developing composition,
B) contacting the color photographic silver halide material with an acidic stop solution comprising at least 0.01 mol/l of a phthalic acid or a salt thereof, and
C) bleaching the color photographic silver halide material with a photographic bleaching composition having a pH of from about 2 to about 9 when in aqueous form and comprising:
at least 0.01 mol/l of a ferric-ligand bleaching agent,
at least 0.01 mol/l of a rehalogenating agent, and
at least 0.01 mol/l of a phthalic acid or a salt thereof.
The photographic bleaching 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 bleaching composition. The bleaching composition can be used in a variety of photographic processing methods, and in some embodiments, it is advantageously used after use of an odorless acidic stop solution that also includes a phthalic acid or salt thereof.
DETAILED DESCRIPTION OF THE INVENTION
Photographic bleaching 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 bleaching 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), N-(2-carboxyphenyl)ethylenediamine-N,N′,N″-triacetic acid, and hydroxyethylethylenediaminetriacetic acid (HEDTA). PDTA is the most useful chelating ligand in the practice of the present invention. The most preferred ligands include EDTA, EDDS (defined below), and PDTA.
Biodegradable chelating ligands are also useful 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 001B1 (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 of 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 aminopolycarboxylic acid or polyaminopolycarboxylic acid chelating ligands that can be used to form biodegradable iron complexes include iminodiacetic acid and its derivatives (or salts thereof), including alkyliminodiacetic acids that have a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms (such as methyl, ethyl, n-propyl, isopropyl, and 1-butyl) as described in EP 0 532 003A1 (Kuse et al.). Particularly useful alkyliminodiacetic acids are methyliminodiacetic acid (MIDA) and ethyliminodiacetic acid (EIDA), and MIDA is the most preferred.
All chelating ligands useful in this invention can be present in the free acid form or as alkali metal (for example, sodium and potassium) or ammonium salts, or as mixtures thereof.
Still other biodegradable chelating ligands can be represented by the following Structure I:
wherein p and q are independently 1, 2 and 3, and preferably each is 1. The linking group X may be any divalent group that does not bind ferric ion and does not cause the resulting ligand to be water-insoluble. Preferably, X is a substituted or unsubstituted alkylene group, substituted or unsubstituted arylene group, substituted or unsubsti
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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