Radiation imagery chemistry: process – composition – or product th – Nonradiation sensitive image processing compositions or... – Developer
Reexamination Certificate
2001-09-21
2004-08-03
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Nonradiation sensitive image processing compositions or...
Developer
C430S486000, C430S493000
Reexamination Certificate
active
06770429
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
The present invention relates to a single-part, single-phase, liquid color developer concentrate for use in color photographic development and a method for processing image-wise exposed photographic color silver halide emulsions using the color developer concentrate.
B. Description of the Related Art
Exposed photographic color silver halide emulsions are generally processed through the steps of color development, desilvering, washing and stabilization, usually using the following processing solutions: color developer, bleaching solution, fixer (or a combined bleach-fixing solution), wash water and/or stabilizing solution. These processing solutions are available as diluted, single-part, ready-to-use solutions, or are prepared either from solid chemicals or sets of multiple liquid concentrates, which must be mixed and diluted prior to use.
For the developer processing step, sets of multiple liquid concentrates have been used to prepare the color developer replenisher and working strength developer. These sets of multiple liquid concentrates have been required in order to separate individual components necessary to form the color developer composition to avoid unwanted chemical reactions between these components, wherein the chemical reactions cause deterioration of the developer concentrate during long term storage. The sets of multiple liquid concentrates have found wide-reaching commercial success within the photographic processing industry. However, mixing and diluting multiple concentrates to form a single developer processing solution requires a specific addition order of the concentrates and dilution water. Improper addition order may cause severe precipitation of the active ingredients, compromising the performance of the solution and causing mechanical malfunction of the processor.
Therefore, there is a need in the color photographic processing industry to combine the multiple liquid concentrates into a single-part concentrate in order to simplify the preparation of working solutions and replenisher solutions, minimize the chance of mixing error, and reduce packaging waste. At the same time, the long-term stability of the liquid concentrate compositions must be maintained.
For color photographic processing, one or more p-phenylenediamine or a derivative or salt thereof (hereinafter “p-phenylenediamine”) is required in the color developing composition to function as a color developing agent. To stabilize the p-phenylenediamine, preservatives of hydroxylamine or a derivative thereof (hereinafter “hydroxylamine”) are required. However, p-phenylenediamine and hydroxylamine react in liquid form in aqueous solutions. Further, p-phenylenediamine is not very soluble at the high pH levels required for color photographic processing. Thus, incorporation of these chemicals into a single aqueous solution that is stable and simple to manufacture has not heretofore been possible.
It is recognized that these disadvantageous chemical reactions are unique to the color photographic processing industry. Black and white photographic processing single-part concentrate solutions are known, such as, for example, U.S. Pat. No. 5,376,510 to Parker et al. and U.S. Pat. No. 4,987,060 to Marchesano, as well as many commercially available products and compositions. However, since color developing compositions are different from black and white developing compositions, there is still a need in the industry to produce a single-part liquid color developer concentrate useful in forming color developer replenishers and color working strength developers. Thus, numerous investigations have been made in the industry directed toward developing single-part color developer concentrates.
Papai (U.S. Pat. No. 5,891,609) teaches a heterogeneous, single-part color developer concentrate having distinct layers or phases: an aqueous lower phase, an upper phase containing p-phenylenediamine developing agent dissolved in an organic solvent of single ring heterocyclic amide, and an optional middle phase consisting of solid particles suspended between the other two layers. Such a heterogeneous product is disadvantageous because use of only a portion of the contents of the container can result in an uneven dosage of the active ingredients, thus affecting the consistency of the developer performance. Additionally, residue remaining in the developer concentrate container upon dispensing and mixing the product can result in an uneven dosage of the active ingredients. Thus, a single-phase developer concentrate is desirable.
Tappe et al (U.S. Pat. No. 6,251,573) teach a single-part color developer concentrate which comprises at least two phases. While being free of any residue or precipitation, it still retains the disadvantages of being non-homogeneous with the concomitant lack of uniformity when using only a portion of the concentrate when dosing for replenishment.
Kim et al (U.S. Pat. No. 5,914,221) teach a single-part color photographic processing composition in slurry form, with a water content of less than 50% (w/w). While providing a substantial advantage in product uniformity and high compactness, further conveniences in use and manufacturing simplification are desirable.
Hashimoto et al (EP 800111) teaches a low viscosity, pourable, slurry-form, single-part color photographic developer containing 0.1 to 10% of a water soluble polymer and 50 to 250% water based on the weight of the solid ingredients. It is taught that the slurry is easily transferred and readily dispersible. However, the slurry requires high quantities of alkali compounds in order to solubilize the p-phenylenediamine developing agent in the high water content medium and to make a developer replenisher having a pH 12.0 or greater on dilution and dissolution.
Darmon et al (U.S. Pat. Nos. 6,017,687 and 6,077,651) teaches the use of a p-phenylenediamine developing agent in free-base form. The developing agent is dissolved in an organic solvent dominated medium to form a highly compact, single-part, single-phase, liquid developer concentrate having a weight ratio of water to organic solvent of 15:85 to 50:50. However, to obtain the single-phase, liquid developer concentrate, additional manufacturing steps of in-process filtration and washing are necessary for elimination of inorganic salts formed during the dissolution of the developing agent. These inorganic salts have a low solubility in the organic solvent and thus form a precipitate which must be removed during manufacture of the developer concentrate. In addition, the high level of organic solvent in the developer concentrate may have a deleterious effect on the sensitometric performance of some color photographic emulsions, resulting in undesirable image quality. Further, the high level of organic solvents in the concentrate creates an undesirable environmental impact.
Darmon et al (U.S. Pat. No. 6,228,567) requires the use of the p-phenylenediamine color developing agent in free base form only, including the additional manufacturing steps of precipitating and washing to remove inorganic salts form the commercially available salts of color developing agents.
As seen from the review of the state of the art, use of high levels of organic solvent enables dissolution of p-phenylenediamine, but hinders dissolution of various salts necessary or desirable for use in a developer concentrate. Further, high levels of organic solvent can have a deleterious effect on the sensitometric performance of some color photographic emulsions, resulting in undesirable image quality. Again, the additional manufacturing steps of precipitation and washing to remove inorganic salts from the commercially available salts of color developing agents contribute to the difficulty in producing a single-part, single-phase color developer concentrate.
Thus, there is a continuing need in the industry to provide a homogeneous single-part color developer concentrate that is stable, simple to dilute and mix, easy to manufacture, does not compromise photographic performance, and which h
Burns Doane Swecker & Mathis L.L.P.
Fuji Hunt Photographic Chemicals Inc.
Le Hoa Van
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