Radiation imagery chemistry: process – composition – or product th – Regenerating image processing composition – Bleach-fix
Reexamination Certificate
1997-01-03
2002-09-17
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Regenerating image processing composition
Bleach-fix
C430S430000
Reexamination Certificate
active
06451519
ABSTRACT:
FIELD OF THE INVENTION
This invention relates in general to color photography and in particular to methods and compositions useful in the processing of color reversal photographic elements. More particularly, this invention relates to a bleach regenerator composition, and its use in the processing of the noted elements.
BACKGROUND OF THE INVENTION
Multicolor, multilayer photographic elements are well known in the art. Such materials generally have three different selectively sensitized silver halide emulsion layers coated on one side of a single support. Each layer has components useful for forming a particular color in an image. Typically, they utilize color forming couplers that form yellow, magenta and cyan dyes in the sensitized layers during processing.
After color development, it is necessary to remove the silver image that is formed coincident with the dye image. This can be done by oxidizing the silver using a suitable oxidizing agent, commonly referred to as a bleaching agent, followed by dissolving the silver halide so formed using what is known as a fixing agent.
A commercially important process intended for use with color reversal photographic elements that contain color couplers in the emulsion layers, or layers contiguous thereto, uses the following sequence of processing steps: first developing, washing, reversal bath, color developing, bleaching, fixing, washing and stabilizing.
In the past, in continuous processing methods, including processing of reversal color materials, the various processing solutions have been discarded after use. However, more recently, used processing solutions have been collected and reused, at least in part because of the environmental problems the waste solutions create, as well as the high costs in collection and discard of the solutions. Thus, used solutions have been reused by adding them to the processing baths as “replenishers” to the various solutions. Considerable efforts are being carried out in the industry to find ways to regenerate the components of the waste solutions so they can be reused as replenishers, further reducing waste streams. For example, a bleach replenishing composition is added to the bleach tank to keep the necessary components at the appropriate levels. This bleach replenisher can be composed of, in part, bleach composition overflow.
As environmental needs increase in various countries, the industry is striving to find ways to further reduce photoprocessing effluent from the various processing baths. Thus, efforts have been made to regenerate the bleaching solution overflow and to supply the regenerated replenisher solution to the bleach tank as the replenishment solution. One known bleach regenerator solution for reversal color processes is sold by Tetenal of Germany (sold as Tetenal Bleachbath E6/E6AR BL-RCY), which has a pH of about 7, and contains a relatively high bromide ion concentration (approximately 190-210 g/l).
There is also a desire in the industry to use a more concentrated bleach regenerator so more bleaching solution overflow can be utilized to make the bleach replenisher, thereby reducing effluent even further. The commercial product available from Tetenal, however, has limited shelf life stability at its “neutral” pH. It was considered that its pH might be lowered to increase stability, but when this was done, its solubility was decreased and precipitation resulted after several days. Another problem with the commercial Tetenal regenerator solution is that when acid is added to it to lower its pH to the level needed for converting it to a regenerated replenisher, the bleaching capacity of the resultant bleach tank solution is degraded.
There is a need therefore for a more stable bleach regenerator composition that can be used in highly concentrated form to provide a regenerated bleach replenisher at lower pH.
SUMMARY OF THE INVENTION
The problems noted above have been overcome using a method for processing a reversal color silver halide photographic element comprising:
A) bleaching an imagewise exposed, color developed reversal color silver halide photographic element in a bleaching tank with a bleaching composition comprising a complex of ferric ethylenediaminetetraacetic acid as the bleaching agent,
B) supplying a bleach replenisher to the bleaching tank to result in an overflow of used bleaching composition from the bleaching tank,
C) mixing at least 50% of the overflow, in at least a 1:1 volume ratio, with a bleach regenerator composition to obtain a regenerated bleach replenisher,
the bleach regenerator composition having a pH of from about 6.0 to about 6.5, and comprising a total bromide ion concentration of at least about 210 g/l, and complex of ferric ion and ethylenediaminetetraacetic acid, the ferric ion being present in an amount of at least about 50 g/l,
D) adjusting the pH of the regenerated bleach replenisher prepared in step C to from about 5.4 to about 5.6, and
E) replenishing the bleaching composition of step A in the bleaching tank with the pH adjusted regenerated bleach replenisher prepared in step D, using a bleach replenishment rate of less than or equal to about 215 ml/m
2
.
This invention also provides a bleach regenerator composition having a pH of from about 6.0 to about 6.5, and comprising a total bromide concentration of at least about 210 g/l, and a complex of ferric ion and ethylenediaminetetraacetic acid, the ferric ion being present in an amount of at least about 50 g/l.
Further, a pH adjusted regenerated bleach replenisher composition comprises a ferric complex of ethylenediaminetetraacetic acid and having a pH of from about 5.4 to about 5.6,
the regenerated bleaching replenisher composition provided by mixing:
overflow from a ferric ethylenediaminetetraacetic acid bleaching solution with
the pH adjusted bleach regenerator composition described above,
in at least a 1:1 volume ratio to form a regenerated bleach replenisher,
followed by adjusting the pH of the regenerated bleach replenisher to from about 5.4 to about 5.6.
The present invention effectively provides a bleach regenerator composition and bleach replenisher for processing reversal color silver halide photographic materials. The bleach regenerator composition is more stable and stays in solution even at lower pH for extended periods of time. The composition is highly concentrated, for example, in the ferric ion concentration, so that more bleach overflow can be used to form the bleach replenisher.
These advantages are achieved by using a bleach regenerator at considerably lower pH, that is, 6.0-6.5, and thus stability is improved. However, in order to maximize the concentration of the components, the level of bromide salt and hydrobromic acid have been adjusted to provide a reformulated and improved composition.
DETAILED DESCRIPTION OF THE INVENTION
A wide variety of reversal color photographic elements can be used in the practice of the present invention. A detailed description of such materials is found, for example, in
Research Disclosure,
publication 36544, pages 501-541 (September, 1994).
Research Disclosure
is a publication of Kenneth Mason Publications Ltd., Dudley House, 12 North Street, Emsworth, Hampshire PO10 7DQ England (also available from Emsworth Design Inc., 121 West 19th Street, New York, N.Y. 10011). This reference will be referred to hereinafter as
“Research Disclosure”.
More details about such elements are provided herein below.
Reversal color photographic elements utilized in the practice of this invention are typically comprised of a support having on one side thereof a plurality of photosensitive silver halide emulsion layers. The photosensitive layers can contain any of the conventional silver halides as the photosensitive material, for example, silver chloride, silver bromide, silver bromoiodide, silver chlorobromide, silver chloroiodide, silver chlorobromoiodide, and mixtures thereof. Useful support materials include cellulose acetate film, polyvinylacetal film, polycarbonate film, polystyrene film, polyethylene terephthalate film, and the like. The silver halide i
Buongiorne Jean Marie
Craver Mary Ellen
Haight Michael John
Le Hoa Van
Tucker J. Lanny
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