Radiation imagery chemistry: process – composition – or product th – Color imaging process – Using identified radiation sensitive composition in the...
Reexamination Certificate
2001-10-30
2003-06-17
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Color imaging process
Using identified radiation sensitive composition in the...
Reexamination Certificate
active
06579669
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to processing methods for silver halide photographic elements, and more particularly to a method of reducing the corrosion characteristics of the photographic effluent waste generated by the processing method and processor.
BACKGROUND OF THE INVENTION
Color photographic processing typically includes the processing steps of development, bleaching, fixing, washing, and stabilizing. For color negative materials these steps are practiced using a color developer that generates the dye image and, as a side product, metallic silver, a bleach containing a heavy metal bleaching agent that converts any metallic silver into silver ion, and a fixing solution containing a fixing agent that forms soluble silver ion complexes which are removed in the fixing and subsequent washing or stabilizing steps. Finally, the photographic element may be processed in a stabilization step that renders the material stable for storage and includes agents, such as surfactants, that allow water to sheet off the surface without streaking.
With the move toward digital or, hybrid technologies, it is becoming increasingly undesirable in the photofinishing trade to manage photographic chemistries and their associated effluents, including managing effluents to on-site drains and local sewer systems. It is becoming more desirable to develop convenient and cost-effective mechanisms to collect photographic effluents in containers for shipment off site. Photoprocessing effluent that is characterized as corrosive (as defined by US waste management regulations) cannot be managed on-site for disposal. Further, waste mixtures that are corrosive may not be transported off site without adhering to stringent US regulatory requirements that may include special labeling and handling procedures. In addition, licensed haulers must be used to manage corrosive wastes off site, presenting an additional cost burden to the photofinisher. Therefore, it is advantageous in handling, transporting, and disposing of photographic effluents and their containers for the effluents not to be corrosive (as defined by US waste management regulations).
The corrosion characteristic of concern for the safe collection and transportation of photographic waste effluent is the corrosion of UNS G10200 low carbon steel in contact with the waste effluent. This corrosion test protocol is EPA method 1110A. According to the U.S. Resource Conservation and Recovery Act (RCRA), a chemical waste is considered corrosive and, therefore, hazardous, if its low carbon steel corrosion rate is greater than 6.35 mm/yr, when tested by EPA method 1110A. RCRA also specifies that the waste solution would be corrosive if its pH is less than 2.0 or greater than 12.5.
Waste photographic processing solutions may consist of individual used solutions or mixtures of two or more of the following used processing solutions collected in containers: developers, conditioners, bleaches, bleach accelerators or pre-bleaches, fixers, bleach-fixers, stabilizers, rinses, and low-flow washes. Some used processing solutions themselves are quite corrosive, such as photographic bleaches and bleach-fixers which contain oxidizing agents. Photographic developers are highly alkaline solutions and may have toxic characteristics that may make them hazardous. Therefore, photographic bleach waste and photographic developer waste cannot be conveniently or cost effectively transported in their own containers because they are corrosive or may have toxic characteristics.
SUMMARY OF THE INVENTION
This invention provides a method of rendering a used photographic processing solution less corrosive to low carbon steel comprising:
taking at least a used photographic processing solution containing a color developing agent and a used photographic processing solution containing a bleaching agent;
delivering the used photographic processing solutions to a collection vessel to form a used photographic processing composition; and
adjusting the pH of the used photographic processing composition to 6.5 to 11. In one embodiment the pH is adjusted by manipulating the proportions of the used processing solutions. In another embodiment the pH is adjusted by treating the used photographic processing composition with a chemical acid or base.
This invention further provides a method of photographic processing and management of photographic processing solutions comprising:
A) color developing an imagewise exposed color photographic silver halide material with an aqueous color developing composition comprising a color developing agent,
B) without removing said color photographic silver halide material from said aqueous color developing composition, contacting said color photographic silver halide material with a photographic fixing composition comprising a photographic fixing agent, thereby forming a combined color development/fixing processing composition,
C) without removing said color photographic silver halide material from said combined color development/fixing processing composition, contacting said color photographic silver halide material with a photographic bleaching composition, thereby forming a combined color development/fixing/bleaching processing composition, and
D) delivering the combined color development/fixing/bleaching processing composition to a collection vessel to form a used photographic processing composition. In one embodiment the combined color development/fixing/bleaching processing composition has a pH of 6.5 to 11. In another embodiment the combined color development/fixing/bleaching processing composition or the used photographic processing composition is treated with a chemical acid or base to adjust the pH to 6.5 to 11.
This invention provides a way to render used bleach solution and other used photographic processing solutions safe and convenient to handle as photographic waste. The photographic effluent generated by the processor, because it is non-corrosive according to this invention, may be suitable for sewering on-site after any necessary silver recovery operations have been performed. In a preferred embodiment of the invention the effluent is collected in or near the processor and transported off site for recovery of silver and disposal as a non-hazardous waste, thus reducing transportation costs and paperwork requirements to the waste generator.
DETAILED DESCRIPTION OF THE INVENTION
It has been found by the inventors herein that used photographic processing compositions, consisting of a mixture of used photographic bleach or bleach-fixer solution and used photographic color developer solution, are non-corrosive according to the RCRA regulations if the mixture pH has a value of 6.5 or higher, more preferably a value of 7.0 or higher, and most preferably a pH of 7.5 or higher. The used processing composition pH should not be higher than about 9 if it contains ammonium salts to avoid the release of ammonia vapor from the composition. Preferably the pH should be less than about 8.5 to avoid ammonia vapor release and most preferably, the pH should be less than about 8 if ammonium salts are present. The mixture of used photographic color developer solution and used photographic bleach or bleach-fixer solution may also contain used photographic fixer solutions, and used photographic wash or rinse solutions from the photographic process. The pH of such mixtures should also be greater than about 6.5 in order for the mixture not to be corrosive.
In one embodiment of the current invention a used photographic processing solution containing a color developing agent and a used photographic processing solution containing a bleaching agent are delivered to a collection vessel forming a used photographic processing composition within the vessel. The solutions may be delivered separately to the collection vessel or they may be combined prior to delivery to the collection vessel and the invention is intended to include both of these methods. They may be delivered sequentially or simultaneously. The used photographic processing composition is adjust
Salsedo Cynthia A.
Schmittou Eric R.
Le Hoa Van
Meeks Roberts Sarah
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