Radiation imagery chemistry: process – composition – or product th – Nonradiation sensitive image processing compositions or... – Process of preparing composition from plural preformed...
Reexamination Certificate
1999-01-15
2001-03-06
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Nonradiation sensitive image processing compositions or...
Process of preparing composition from plural preformed...
Reexamination Certificate
active
06197484
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a homogeneous, single part, slurry-form color photographicdeveloper composition for use in color photographic processing, a process for developingcolor photographic positive emulsions with the slurry-form developer, and a process for making the slurry.
BACKGROUND OF THE INVENTION
Exposed photographic color silver halide positive emulsions are generally processed through the steps of color development, desilvering, washing, and stabilization, which usually uses the following processing solutions: color developer, bleaching solution, bleach-fixer, fixer, wash water, and stabilizing solution. These processing solutions are either prepared from solid chemicals, multi-part liquid concentrates, or diluted, single part ready to use solutions. Liquid concentrates however, lack compactness, may leak during transportation, handling, and storage; and may suffer from stability problems, especially in the case of a single part color developer. Solid chemicals can meet the requirement of compactness, and improved stability, and may take the form of a powder, tablet, or granule. Powders, however, frequently suffer from problems of dusting and caking. Although tableting and granulation have been proposed to eliminate these problems, these products frequently suffer from loss of ease of dissolution due to tablet or granule hardness resulting from the tableting and granulation process. Despite the advantage of compactness and stability, solid chemicals are often cumbersome to handle, and often require a lengthy dissolution step. Furthermore, single part solid color developers require special multi-layer granulation or coating processing or specialized layered packaging to isolate reactive materials such as alkali and p-phenylenediamine derivatives in order to retain stability which adds to the product's complexity and cost.
Various liquid, slurry, and paste-form single and multiple part photographic processing compositions have also been proposed. For example, Kleinschmidt in DE 3106775 discloses a single part liquid developer concentrate for color negative film comprising ethylene or higher glycols and a p-phenylenediamine derivative packaged in a sealed container to maintain its stability. JP 234389/1996 discloses a single part liquid developer concentrate for color emulsions containing diethylene glycol. The liquid concentrates of Kleinschmidt and JP 234389/1996 however suffer from the combined drawbacks of lack of stability requiring an air-tight, sealed container; and the need to use a significantly larger volume of liquid concentrate in comparison to a compact slurry to make the same amount working tank color developer or developer replenisher solution.
Dillon, et. al. in World Patent Application No. WO 8102934 discloses a homogeneous photographic processing concentrate comprising a discontinuous solid phase distributed in a continuous liquid phase, the solid phase comprising fine solid particles interlaced in the form of a stable three-dimensional reticulated structure imparting shear-rate thining, and the liquid phase containing benzyl alcohol and triethanolamine and being present in an amount smaller than the necessary amount to form a solution of the solid phase, but sufficient to impart flowability to the product. However a disadvantage of Dillon's disclosed composition however is the incompatiblility of the required benzyl alcohol with presently available color print emulsions.
Opladen in U.S. Pat. No. 3,607,277 discloses a fixer and bleach composition for processing color photographic materials in the form of a viscous paste having a viscosity between 300 and 2000 c.p.s. which serves to replace the respective liquid processing solutions. Conventional processing ingredients are combined with thickening agents which include polysaccharides, polyvinyl pyrrolidone, polyvinyl alcohol, and other water soluble polymers. Henn in U.S. Pat. No. 2,735,774 discloses a fixer concentrate having fixer components suspended in a water-soluble colloidal gel of alginate. Henn in U.S. Pat. No. 2,784,086 discloses a single part black and white developer concentrate comprising fine powdery hydroquinone and alkaline agents in a concentration of 0.5 to 10% in water and suspended as a concentrate paste in a colloidal gel of a compound selected from alginic acid, alginic acid salts, and alginic acid esters. Doesborgh in EP Patent Application 204372 discloses a two part black and white photographic developer concentrate in the form of a paste containing hydroquinone and either a water-soluble polymer or an organic water miscible solvent such as ethylene glycol or polyvinylpyrrolidone as a crystal growth inhibitor. Opladen, Henn, and Doesborgh do not however disclose a stable, single part color developer in the form of a homogenous slurry concentrate.
Hashimoto et. al., in European Patent Application EP 800111 discloses a low viscosity, pourable slurry-form, single-part, color photographic developer containing between 0.1 to 10% of a water soluble polymer and between 50 to 200% water based on the weight of the solid ingredients. It is reported that the slurry is easily transferred and readily dispersible. Furthermore, Hashimoto's slurry contains high quantities of alkali sufficient to solubilize p-phenylenediamine free base in a high water content medium and to make a developer replenisher of pH 12.0 or greater on dilution and dissolution of the slurry.
A heterogenous single part color developer concentrate is available from Trebla Chemical Company, as discussed at the IS&T's Tenth International Symposium on Photofinishing Technology (February, 1998; New Orleans, La.). This product is comprised of three distinct layers or phases: an aqueous lower phase containing inorganic salts, an upper phase containing the p-phenylenediamine developing agent dissolved in an organic solvent, and a middle phase consisting of an optical brightening agent suspended between the two layers. However, such heterogenous products are disadvantageous since the quality of the development process may decline due to an uneven dosage of color developer ingredients if only a portion of the container's contents are used or if any residue is allowed to remain in the container upon dispensing and mixing the product.
SUMMARY OF THE INVENTION
In accordance with the invention, a stable, homogenous, slurry-form, single-part color photographic composition (“slurry”) is provided which is used to form either a working strength rapid access color print developer working tank solution or developer replenisher solution upon dilution and dissolution. As used herein, the inventive slurry is defined as a homogeneous, two-phase blend containing a discontinuous solid phase distributed in a continuous liquid phase, the solid phase comprising fine solid particles, and the liquid phase being present in an amount smaller than the necessary amount to form a true solution of the solid phase, but sufficient to impart flowability to the slurry. Importantly, the inventive slurry has sufficient stability to remain flowable by not hardening or caking with time, and to remain homogeneous by avoiding p-phenylenediamine oxidation and free base precipitation. Flowability in this context is defined as the ability for the slurry to be decanted or pumped from its container. The term homogeneous slurry is defined as a uniform appearing product which withstands phase separation for a minimum of 24 hours at 20-25° C. after preparation, and which can be easily redispersed and made homogeneous with mild agitation if settling later occurs.
The art has desired a slurry which provides a pH of under 12.0 after dilution to working or replenisher strength. Unfortunately, the p-phenylenediamine derivative tends to become more or less converted to insoluble derivatives which precipitate under such mild alkaline conditions. The inventive slurry avoids such precipitation problems.
Another feature of the present invention is the reduced water content, under about 50% w/w, which serves to enhance the slurry's st
Duan Hailing
Kim Hongzoon
Philipose Mani
Burns Doane Swecker & Mathis L.L.P.
Fuji Hunt Photographic Chemicals Inc.
Le Hoa Van
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