Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
  • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
  • G03C5/29—Development processes or agents therefor
  • G03C5/31—Regeneration; Replenishers
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
  • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
  • G03C5/29—Development processes or agents therefor
  • G03C5/30—Developers

Definitions

• the invention relates to a process of recycling spent photographic developer compositions wherein the spent developer is collected and reconstituted and can be re-used without detrimental effect on films processed therein.
• Photographic developer compositions are well-known in the art.
• the development of exposed silver halide photographic elements comprises a multiple step process of development, fixing, washing and optionally a stopping step.
• the development step is conventionally undertaken with an aqueous alkaline developer composition containing a developer, also known as a developing agent either singly or with one or more additional developing agents.
• a comprehensive list of developing agents is provided in C. E. K. Mees, The Theory of the Photographic Process , Chapters 14-15, The Macmillan Company (1959, Rev. Ed.)
• the most commonly used developing agent, particularly for processing black-and-white photographic silver halide elements is hydroquinone.
• the hydroquinone or other suitable developing agent serves as a strong silver reducing agent to reduce the silver halide grains containing a latent image to yield the developed photographic image.
• Hydroquinone-based developer compositions typically contain relatively high levels of sulfite-based components. Also, the pH of hydroquinone-based developer compositions is maintained within strict alkaline ranges with alkaline buffers, such as carbonates, phosphates, borates, etc., either alone or in combination with hydroxides. While hydroquinone-based developer compositions have been successfully employed for many years, recently the use of these conventional developer compositions have been imposed with various guidelines and regulations due to the toxicity and environmental hazards associated with the hydroquinone, sulfite, and other components as well as the alkaline nature of the developer.
• alkaline buffers such as carbonates, phosphates, borates, etc.
• U.S. Patent 2,688,549 Another class of developing agents are disclosed in U.S. Patent 2,688,549, which teaches the use of ascorbic acid and sugar-type derivatives thereof as developing agents in photographic developers. Because ascorbic acid and its derivatives are not considered hazardous to the environment, it is desirable to have developer compositions which use these developing agents. Similarly, U.S. Patent 5,098,819 teaches improved photographic developer compositions which are free of hydroquinone and free of alkali metal hydroxides and which utilize ascorbic acid, derivatives and salts thereof as the developing agents.
• developer compositions are highly alkaline with pH of at least 9.5, and they may also contain alkali sulfites as antioxidants in approximate amounts from 10% to 100% of the amount of the developing agent.
• effluents from spent photographic developers have a Chemical Oxygen Demand (COD) of about 70,000 to 100,000 ppm, which exceeds the current limits set by the Environmental Protection Agency and other regulatory agencies.
• the COD value represents the degree to which a solution will compete with biological systems for the supply of oxygen.
• a major obstacle to recycling is being able to reconstitute the developer such that the performance of photographic materials in recycled developer is equivalent or substantially equivalent to the performance of the photographic materials in fresh developer.
• Conventional hydroquinone-based developers are poor recycling prospects because the oxidation products of hydroquinone (formed during development of photographic materials) are developing agents themselves and thus contribute to the complexity of the developer composition. The development activity of these oxidation products makes it difficult, if not impossible, to reconstitute spent hydroquinone-type developer compositions to obtain a developer composition having acceptable performance.
• the degradation (i.e., oxidation) of hydroquinone produces large, dark (almost black in color) polymeric compounds which are difficult to quantitatively analyze and separate. The presence of these degradation products in developer compositions contributes to sludge formation and staining of photographic elements processed therein.
• the present invention is based upon the observation that ascorbic acid-type developing agents produce light-colored oxidation products and the discovery that these products do not affect the performance of the developer composition. It has also been discovered that the presence of these products does not produce undesirable effects (such a staining) to photographic elements processed therein.
• the present invention comprises a recycled black-and-white photographic developer composition made according to the above process.
• the hydroquinone-free black-and-white photographic developer composition comprises: Ingredients Amount (grams) sulfite ion 3 to 30 sequestering agent 1 to 7 bromide ion 1.5 to 10.0 developing agent 20 to 90 secondary developing agent 0.25 to 3.0 antifoggants 0.05 to 0.65 development accelerator 0.01 to 3.0 Water to make 1 Liter
• Non-hydroquinone containing photographic developer compositions are disclosed, for example, in the aforementioned U.S. Patents and in U.S. Patent Application Serial Nos. 07/683,248, filed April 10, 1991 and 07/684,192, filed April 12, 1991, each of which are hereby incorporated by reference in their entirety. All of these references disclose the use of ascorbic acid-type developing agents, which are preferred in the present invention because they produce light-colored oxidation products which do not interfere with development, and thus, can be successfully reused to provide an environmentally sound method of developing photographic materials without detrimental effect on the performance of the photographic materials.
• the developing agent must be one which avoids the combination of disadvantages presented by hydroquinone-type developing agents. In other words, it must be one which either (1) does not interfere with the developer activity or produce undesirable effects on photographic elements processed therein; or (2) is readily removed from the spent developer. Because of the complexity of developer compositions used to process color films, they are not considered to be viable candidates for recycling under the present process.
• Particularly preferred developing agents which can be employed to advantage in the present invention include (1) ascorbic acid and sugar-type derivatives thereof; (2) stereoisomers and diastereoisomers of ascorbic acid, such as for example erythorbic acid, and their sugar-type derivatives; (3) salts and mixtures of (1) and (2); (4) 2-keto gluconic acid and derivatives thereof, and (5) mixtures of (1) through (4).
• Example of such compounds include, DL-ascorbic acids, sorboascorbic acid, ⁇ -lactoascorbic acid, maltoascorbic acid, L-araboascorbic acid, sodium ascorbate, potassium ascorbate, sodium erythorbate and potassium erythorbate, 2-keto gluconates, potassium, sodium, ammonium, and methyl derivatives thereof.
• Most preferred as the developing agents are ascorbic acid, sodium ascorbate, erythorbic acid, and sodium erythorbate.
• the developer composition may contain a multitude of conventional adjuvants which serve various functions such as secondary developing agents, antifogging agents, buffers, sequestering agents, swelling control agents, and development accelerators.
• adjuvants are well known to those of ordinary skill in the art.
• Preferred secondary developing agents are pyrazolidone or metol and derivatives thereof, with 4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone and 1-phenyl-3-pyrazolidone being particularly preferred.
• antifogging agents examples include benzotriazole, phenylmercaptotetrazole, and benzimidazole and derivatives thereof, used alone or in admixture.
• Soluble bromides particularly alkali metal bromides (e.g., potassium bromide, sodium bromide) are the preferred restrainers. It is preferred to have both antifoggant agents and a restrainer in the developer. As discussed hereinbelow, it is particularly preferred for the developer to contain from about 7 to about 10 grams/Liter of an alkali metal bromide, whereby a greater percentage of spent developer can be recycled and reused in accordance with the present process.
• sequestering agents or chelating agents
• sequester trace metal ions e.g., copper and iron ions
• Preferred sequestering agents are sodium salts of EDTA.
• an antioxidant is also present in the developer composition.
• Antioxidants are normally used in developer compositions as preservatives, however, such compounds serve the additional function of an accelerating compound in the preferred developer composition disclosed herein.
• suitable antioxidants include alkali metal sulfites, bisulfites, metabisulfites and carbonyl-bisulfites adducts.
• a preferred antioxidant is sodium bisulfite.
• the pH of the developer is adjusted into the range of about 9.0 to about 11.0 by adding one or more of an alkali metal carbonate, such as sodium or potassium carbonate; an alkali metal bicarbonate, such as sodium or potassium bicarbonate; and, an alkali metal hydroxide.
• an alkali metal carbonate such as sodium or potassium carbonate
• an alkali metal bicarbonate such as sodium or potassium bicarbonate
• an alkali metal hydroxide Preferred are potassium hydroxide and potassium carbonate in a ratio of 2 to 1.
• a development accelerator may be included in the developer composition to increase developer activity to that of conventional development times.
• a development accelerator in the ascorbic acid based developer compositions discussed above renders such compositions equivalent or substantially equivalent in development activity to conventional hydroquinone-based developers for all families of films common to graphic arts, i.e., camera, contact, and photoelectronic (e.g., scanner and imagesetting) films and papers.
• Developer accelerators suitable for use in this invention include quaternary ammonium compounds and aryl hydrazides, such as those disclosed in U.S. 4,937,160.
• the preferred development accelerators are the quaternary ammonium compounds disclosed by Pangratz in U.S. Serial Number 07/801,347, the disclosure of which is hereby incorporated by reference.
• a particularly preferred quaternary ammonium development accelerator is 1-phenethyl-2-picolinium bromide (PPB).
• a suitable non-hydroquinone developer composition may comprise: Ingredients Amount (grams) sulfite 3 to 50 sequestering agent 1 to 7 bromide 1.5 to 10.0 developing agent 20 to 90 secondary developing agent 0.25 to 3.0 antifoggants 0.05 to 0.65 development accelerator 0.01 to 3.0 Water to make 1 Liter
• a typical and preferred developer composition will comprise: Ingredient Amount (grams) Range Preferred Sulfite 10 - 30 15.8 Tri-sodium EDTA 2 - 7 3.5 Potassium bromide 7 - 10 8 Sodium Erythorbate 20 - 60 40 Glucono Delta Lactone 0.1 - 1.0 0.7 4-hydroxymethyl-4-methyl- 1-phenyl-3-pyrazolidone 0.25 - 1 0.5 Benzotriazole 0.15 - 0.35 0.25 Phenylmercaptotetrazole 0.025 - 0.1 0.05 PPB 0 - 0.5 0.3 Water to make 1 Liter
• the process of recycling spent photographic developer in accordance with the present invention comprises the steps of collecting the spent developer and reconstituting the spent developer for reuse.
• the first step in the process is to collect spent developer.
• spent developer as used herein, means a developer composition which has been used to process photographic film or which otherwise has lost some of its development activity as compared to fresh or virgin developer.
• the collection step in the present process may conveniently be practiced by collecting developer purged from a developer tank of a processor (such as during processing and/or during automatic replenishment of the developer) in an off-line tank until a sufficient quantity of spent developer is available for the next step. It is to be understood that the process of the present invention does not require any particular amount of spent developer be collected before the reconstituting step. However, for obvious reasons, it is desirable for the present process to be practiced in batch quantities.
• the collection step includes the separation of liquid developer from any particulate matter present therein. It is not uncommon for spent developer to contain a variety of foreign particulate matter, such as gelatin, conglomerates of silver, hair, dirt, paper clips, etc.
• the separation of liquid developer from particulate matter may be practiced in any conventional manner, such as by decanting or filtration.
• the next step in the present process comprises reconstituting the developer for reuse.
• fresh developer denotes a developer which is newly mixed, and/or which has not been used to develop a significant amount of film, and/or which has not been held at elevated development temperatures, i.e., about 95°F to about 110°F, for any extended period of time.
• the reconstituting step may involve the addition of certain developer components to increase the concentration thereof or the dilution of the spent developer to decrease the concentration of components. More particularly, it is well known that many developer ingredients are wholly or partially consumed during development of photographic elements. Thus, the concentration of such ingredients in spent developer would be lower than the concentration in fresh developer. In the reconstituting step, these ingredients would be added to the spent developer.
• both an addition and dilution will be necessary to reconstitute the spent developer.
• the result of the reconstituting step should be a developer composition that is substantially the same as a fresh developer composition.
• the reconstituted developer composition would also contain the oxidation products of the ascorbic acid-type developing agents.
• the analysis step would comprise an analysis of the spent developer to determine the concentration of the various ingredients which are to be reconstituted and the pH.
• Conventional analytical methods such as titration, spectroscopy and chromatography, may be used to conduct the analysis of the spent developer.
• the spent developer should be analyzed for the concentration of developing agent (both primary and secondary) and antifoggant(s), since these components are usually critical to the performance of a developer.
• the concentration of the bromide ion in the spent developer solution is generally dependent upon the mix of films processed in the developer, i.e., the proportion of the processed films which are totally or partially silver bromide grain films.
• the spent developer may not need to be diluted to the extent that the spent developer would if some of the films processed contained silver bromide.
• Another factor which may influence the concentration of bromide ion in the spent developer includes the amount of developed density, i.e., the proportion of the imaged film which is high density and low density.
• a typical non-hydroquinone developer composition for black-and-white films will contain from 2 to 3 g/L of bromide ion, which can increase to about 8 to 10 g/L in spent developer. Thus, in reconstituting such developers, it may be necessary to dilute the spent developer from about 70% to about 30% of the collected volume to reduce the bromide ion concentration to acceptable levels.
• the recycled developer resulting from the present process would comprise between 30-70% spent developer and 70-30% fresh ingredients.
• the efficiency of the present process is improved substantially by using a developer composition having a bromide concentration of about 7-10 g/L.
• Ascorbic acid-type developer compositions in particular are able to tolerate such high levels of bromide.
• the additional bromide resulting from film through-put represents a much lower percentage increase in bromide as compared to the more conventional developer compositions.
• a lower dilution factor is needed to return the elevated bromide levels to an acceptable starting concentration.
• using the preferred developer composition in the present process results in recycled developer comprising from about 70% to greater than 97% spent developer and only up to about 30% fresh ingredients.
• the pH of the developer should be adjusted using one or more of the well known adjuvants for that purpose.
• the pH should be between 9.0 and 11.0.
• composition of the recycled developer will not (and need not) be identical to the composition of fresh developer. Indeed, as noted previously, ascorbic acid-type developing agents degrade to light-colored oxidation products. The presence of these products does not interfere with the activity of the recycled developer and they do not adversely affect photographic elements processed therein. Therefor, these oxidation products need not be removed from the recycled developer. Similarly, ingredients such as carbonates and hydroxides, which serve only as pH adjusting and buffering agents, may be substituted with equivalent alkali buffering and adjusting agents in the reconstituting step, so long as the recycled developer has the proper pH and buffer capacity.
• Photographic developers that have been recycled according to the present process can be used in the same manner as fresh developer solutions, including as a replenishment solution and to initially charge the processor. They may be used in a variety of processing equipment and techniques well known to those skilled in the art.
• the pH of the solution was adjusted to 10.5 using a hydroxide and carbonate buffer solution, (approximately a 2:1 ratio hydroxide:carbonate).
• the developer solution was placed into the developer tank of a deep tank processor and maintained at 100°F.
• a sample of the spent developer was analyzed to determine the concentration of potassium bromide, erythorbic acid, Dimezone-S, PMT, and benzotriazole.
• the concentration of bromide ion was determined using titration.
• the concentration of erythorbic acid was determined using UV spectroscopy.
• the concentrations of PMT, Dimezone-S and benzotriazole were determined using high performance liquid chromatography (HPLC). Results of the analysis are shown in Table B.
• Example 1 was repeated with the exception that bromide-free developer was used instead of water in the reconstitution step.
• the amounts of developer ingredients and bromide-free developer are indicated in Table D. Sensitometric activity was as reported in Table C, above. TABLE D Ingredient Concentration in Spent Developer Amount Added to 4.4 gal of Spent Developer Potassium bromide 6.8 gm/Liter -- Erythorbic Acid 96% of original level (76.8 gm/L) 3.7 g PMT 67.9% of original level (0.0679 gm/L) 0.032 g 4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone 91.7% of the original level (0.4585 gm/L) 0.042 g Benzotriazole 93% of the original level (0.4650 gm/l) 0.035 g Bromide-free developer to make 10 gallons
• Example 1A The pH of the solution was adjusted to 10.7 using a 2:1 hydroxide:carbonate buffer solution.
• the developer solution was placed into the developer tank of a deep tank processor and maintained at 100°F.
• Various black-and-white graphic arts films were processed and sensitometrically tested, and spent developer collected as in Example 1A.

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• 1993
  • 1993-08-25 EP EP93113548A patent/EP0585792B1/fr not_active Expired - Lifetime
  • 1993-08-25 DE DE1993627079 patent/DE69327079T2/de not_active Expired - Fee Related
  • 1993-09-03 JP JP21960093A patent/JPH06161057A/ja active Pending
  • 1993-09-03 CA CA 2105532 patent/CA2105532A1/fr not_active Abandoned
  • 1993-09-03 AU AU46078/93A patent/AU666213B2/en not_active Ceased

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