Stabilized ascorbic acid developing compositions and methods of use

Abstract: A black-and-white photographic developing composition has improved stability and is more compatible with the environment when discarded. The composition includes one or more ascorbic acid developing agents and a preservative (such as a sulfite) and is essentially free of hydroquinone and similar developing agents. It comprises an α-ketocarboxylic acid stabilizing agent at a molar ratio to the ascorbic acid developing agent of from 0.05:1 to 2.5:1, and at a molar ratio to the preservative of from 0.05:1 to 6.25:1.

Description: This invention relates in general to photography and in particular to improved black-and-white developing compositions. More particularly, it relates to improved and stabilized ascorbic acid developing compositions and to methods for their use in processing photographic silver halide materials. Photographic black-and-white developing compositions containing a silver halide black-and-white developing agent are well known in the photographic art for reducing silver halide grains containing a latent image to yield a developed photographic image. Many useful developing agents are known in the art, with hydroquinone and similar dihydroxybenzene compounds and ascorbic acid (and derivatives) being some of the most common. Such compositions generally contain other components such as sulfites, buffers, antifoggants, halides and hardeners. Dihydroxybenzenes (such as hydroquinone) are the most common black-and-white developing agents and are quite active to provide development in various black-and-white photographic elements with or without booster and nucleating compounds. However, they are disadvantageous from several technical and environmental considerations. For example, hydroquinone compositions are not completely stable in air, being prone to aerial oxidation. The by-products from instability are often insoluble, black and tarry materials that contaminate the processing solutions and equipment. The oxidation of hydroquinones also leads to higher pH that in turn leads to increased developer activity. Images can be produced faster so the processing time must be reduced. The net effect is less control of the process, and less desirable sensitometric properties in the processed materials. In addition, hydroquinones have become an increasing concern from the point of view of potential toxicity and environmental pollution. Another class of black-and-white developing agents are known in many publications as ascorbic acid and its various derivatives, for example as described in US-A-5,236,816 (Purol et al). While these types of developing agents are considerably more suitable to the environment, a major concern with ascorbic acid type developing agents is their stability to aerial oxidation. It is well known to improve stability of hydroquinone developing agents by means of various additives, as described in US-A-4,756,997 (Marchesano), for processing high contrast graphic arts films. There is a need however for more stable ascorbic acid developing compositions for processing a wide variety of photographic silver halide materials that require a black-and-white developing step. An improved black-and-white photographic developing composition comprises: a) an ascorbic acid developing agent, and a preservative, the developing composition characterized as further comprising a stabilizing amount of a α-ketocarboxylic acid, wherein the molar ratio of the α-ketocarboxylic acid to the ascorbic acid developing agent is from 0.05:1 to 2.5:1, the molar ratio of the α-ketocarboxylic acid to the preservative is from 0.05:1 to 6.25:1, and the composition is essentially free of dihydroxybenzene compounds. This invention also provides a method of providing an image comprising contacting an imagewise exposed photographic silver halide material with the black-and-white photographic developing composition described above for at least 10 seconds. This invention also provides a photoprocessing kit comprising the black-and-white developing composition described above, and one or more additional photochemical processing compositions. The present invention provides a highly stabilized black-and-white developing composition by the use of the α-ketocarboxylic acid as a stabilizing agent, and the specific molar ratios of the α-ketocarboxylic acid to the ascorbic acid developing agent and preservative. This composition is essentially free of dihydroxybenzene compounds, and is preferably also essentially free of alkanolamines. In addition, the activity of the developing compositions of this invention can be suitably maintained using a replenisher composition that has essentially the same components, concentrations and pH. In effect, the replenisher composition is equally stable as the working composition. Because the compositions of this invention have increased stability, they can be used as lower replenishment rates during photoprocessing. This would lead to lower effluent volumes and costs. In addition, a certain amount of α-ketocarboxylic acid from the developing step can be carried over into a later processing bath, such as a photographic fixing bath. This "carry-over" α-ketocarboxylic acid may be helpful to reduce sulfur dioxide emissions as described in US-A-5,629,138 (Faranda et al), and to reduce image dye stain. The improved stability (that is, reduced aerial oxidation) would generally reduce composition color change. The developing compositions are also "cleaner working" because they require less preservatives (such as sulfites) that create sludge or dirt in the processing bath. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graphical representation of the stability data obtained for Example 1 below. FIG. 2 is a graphical representation of the stability data obtained for Examples 2-5 below. FIG. 3 is a graphical representation of the stability data obtained for Example 9 below. The present invention is useful for black-and-white development in any photographic silver halide material requiring at least one black-and-white development step. Such types of silver halide materials include, but are not limited to, particularly, radiographic films, aerial films, black-and-white motion picture films, duplicating and copy films, graphic arts films, positive- and negative-working microfilms and amateur and professional continuous tone black-and-white films. The general composition of such materials is well known in the art but specific features that render them particularly adaptable to the present invention are described below in more detail. In addition, the black-and-white developing composition of this invention can be used in the "first" (black-and-white) development of color reversal photographic silver halide materials (details described below). The black-and-white developing compositions of this invention contain one or more ascorbic acid developing agents. An "ascorbic acid" developing agent means ascorbic acid and derivatives thereof. Ascorbic acid developing agents are described in a considerable number of publications in photographic processes, including US-A-5,236,816 (noted above) and references cited therein. Useful ascorbic acid developing agents include ascorbic acid and the analogues, isomers and derivatives thereof. Such compounds include, but are not limited to, D- or L-ascorbic acid, sugar-type derivatives thereof (such as sorboascorbic acid, γ-lactoascorbic acid, 6-desoxy-L-ascorbic acid, L-rhamnoascorbic acid, imino-6-desoxy-L-ascorbic acid, glucoascorbic acid, fucoascorbic acid, glucoheptoascorbic acid, maltoascorbic acid, L-arabosascorbic acid), sodium ascorbate, potassium ascorbate, isoascorbic acid (or L-erythroascorbic acid), and salts thereof (such as alkali metal, ammonium or others known in the art), endiol type ascorbic acid, an enaminol type ascorbic acid, a thioenol type ascorbic acid, and an enamin-thiol type ascorbic acid, as described for example in US-A-5,498,511 (Yamashita et al), EP-A-0 585,792 (published March 9, 1994), EP-A-0 573 700 (published December 15, 1993), EP-A-0 588 408 (published March 23, 1994), WO 95/00881 (published January 5, 1995), US-A-5,089,819 and US-A-5,278,035 (both of Knapp), US-A-5,384,232 (Bishop et al), US-A-5,376,510 (Parker et al), Japanese Kokai 7-56286 (published March 3, 1995), US-A-2,688,549 (James et al), US-A-5,236,816 (noted above) and Research Disclosure, publication 37152, March 1995. D-, L-, or D,L-ascorbic acid (and alkali metal salts thereof) or isoascorbic acid (or alkali metal salts thereof) are preferred. Sodium ascorbate and sodium isoascorbate are most preferred. Mixtures of these developing agents can be used if desired. The black-and-white developing composition can also include one or more auxiliary co-developing agents that are also well known (for example, Mason, Photographic Processing Chemistry , Focal Press, London, 1975). Any auxiliary developing agent can be used, but the 3-pyrazolidone developing agents are preferred (also known as "phenidone" type developing agents). Such compounds are described, for example, in US-A-5,236,816 (noted above). The most commonly used compounds of this class are 1-phenyl-3-pyrazolidone, 1-phenyl-4,4-diniethyl-3-pyrazolidone, 4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone, 5-phenyl-3-pyrazolidone, 1- p -aminophenyl-4,4-dimethyl-3-pyrazolidone, 1- p -tolyl-4,4-dimethyl-3-pyrazolidone, 1- p -tolyl-4-hydroxymethyl-4-methyl-3-pyrazolidone, and 1-phenyl-4,4-dihydroxymethyl-3-pyrazolidone. Other useful auxiliary co-developing agents comprise one or more solubilizing groups, such as sulfo, carboxy or hydroxy groups attached to aliphatic chains or aromatic rings, and preferably attached to the hydroxymethyl function of a pyrazolidone, as described for example, in US-A-5,837,434 (Roussilhe et al). A most preferred auxiliary co-developing agent is 4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone. Less preferred auxiliary co-developing agents include aminophenols such as p -aminophenol, o -aminophenol, N-methylaminophenol, 2,4-diaminophenol hydrochloride, N-(4-hydroxyphenyl)glycine, p -benzylaminophenol hydrochloride, 2,4-diamino-6-methylphenol, 2,4-diaminoresorcinol and N-(β-hydroxyethyl)- p -aminophenol. A mixture of different types of auxiliary developing agents can also be used if desired. An organic or inorganic antifoggant is also preferably present in the black-and-white developing composition, either singly or in admixture. Useful inorganic antifoggants include various halide salts, including bromides. Such compounds control the gross fog appearance in the processed elements. Suitable organic antifoggants include, but are not limited to, benzimidazoles, benzotriazoles, mercaptotetrazoles, indazoles and mercaptothiadiazoles. Representative antifoggants include 5-nitroindazole, 5- p -nitrobenzoylaminoimidazole, 1-methyl-5 -nitroindazole, 6-nitroindazole, 3-methyl-5-nitroindazole, 5-nitrobenzimidazole, 2-isopropyl-5-nitrobenzimidazole, 5-nitrobenzotriazole, sodium 4-(2-mercapto-1,3,4-thiadiazol-2-yl-thio)butanesulfonate, 5-amino-1,3,4-thiadiazol-2-thiol, 5-methylbenzotriazole, benzotriazole and 1-phenyl-5-mercaptotetrazole. Benzotriazole is most preferred. The developing composition also includes one or more preservatives or antioxidants. Various organic preservatives, such as hydroxylamine and alkyl- or aryl- derivatives thereof, can be used, and inorganic preservatives such as sulfites can be used Sulfites are preferred. A "sulfite" preservative is used herein to mean any sulfur compound that is capable of forming or providing sulfite ions in aqueous alkaline solution. Examples include, but are not limited to, alkali metal sulfites, alkali metal bisulfites, alkali metal metabisulfites, amine sulfur dioxide complexes, sulfurous acid and carbonyl-bisulfite adducts. Mixtures of these materials can also be used. Examples of preferred sulfites include sodium sulfite, potassium sulfite, lithium sulfite, sodium bisulfite, potassium bisulfite, sodium metabisulfite, potassium metabisulfite, and lithium metabisulfite. The carbonyl-bisulfite adducts that are useful include alkali metal or amine bisulfite adducts of aldehydes and bisulfite adducts of ketones. Examples of these compounds include sodium formaldehyde bisulfite, sodium acetaldehyde bisulfite, succinaldehyde bis-sodium bisulfite, sodium acetone bisulfite, β-methyl glutaraldehyde bis-sodium bisulfite, sodium butanone bisulfite, and 2,4-pentandione bis-sodium bisulfite. Various known buffers, such as borates, carbonates and phosphates, or combinations of any of these can be included in the compositions to maintain the desired pH when in aqueous form. The pH can be adjusted with a suitable base (such as a hydroxide) or acid. The pH of the developing composition (in aqueous form) is generally from 7 to 12, and more preferably from 8 to 11. Optionally, the black-and-white developing composition contains one or more sequestering agents that typically function to form stable complexes with free metal ions or trace impurities (such as silver, calcium, iron and copper ions) in solution that may be introduced into the developing composition in a number of ways. The sequestering agents, individually or in admixture, are present in conventional amounts. Many useful sequestering agents are known in the art, but particularly useful classes of compounds include, but are not limited to, multimeric carboxylic acids, polyphosphonic adds and polyaminophosphonic acids, and any combinations of these classes of materials as described in US-A-5,389,502 (Fitterman et al), aminopolycarboxylic acids and polyphosphate ligands. Representative sequestering agents include ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, 1,3-propylenediaminetetraacetic acid, 1,3-diamino-2-propanoltetraacetic acid, ethylenediaminodisuccinic acid, ethylenediaminomonosuccinic acid, 4,5-dihydroxy-1,3-benzenedisulfonic acid, disodium salt (TIRON™), N,N'-1,2-ethanediylbis{N-[(2-hydroxyphenyl)-methyl]} glycine ("HBED"), N-{2-[bis(carboxymethyl)-amino]ethyl}-N-(2-hydroxyethyl)glycine ("HEDTA"), N-{2-[bis(carboxymethyl)ammo]ethyl}-N-(2-hydroxyethyl)glycine, trisodium salt (available as VERSENOL™ from Acros Organics, Sigma Chemical or Callaway Chemical), and 1-hydroxyethylidenediphosphonic acid (available as DEQUEST TM 2010 from Solutia Co.). The black-and-white developing composition can contain other additives including various development restrainers, development accelerators, swelling control agents, dissolving aids, surface active agents, colloid dispersing aids, restrainers (such as sodium or potassium bromide), and sludge control agents (such as 2-mercaptobenzothiazole, 1,2,4-triazole-3-thiol, 2-benzoxazolethiol and 1-phenyl-5-mercaptoetrazole), each in conventional amounts. Examples of such optional components are described in US-A-5,236,816 (noted above), US-A-5,474,879 (Fitterman et al), US-A-5,837,434 (Roussilhe et al), Japanese Kokai 7-56286 and EP-A-0 585 792. The compositions of this invention can also include one or more photographic fixing agents (described below) to provide what is known in the art as "monobaths". The developing compositions of this invention are essentially free of dihydroxybenzene compounds (such as hydroquinone). By "essentially free" is meant that such compounds are not purposely added and may be inadvertently present in an amount of less than 0.0001 mol/l. The developing composition preferably includes one or more α-ketocarboxylic acids having an aliphatic group as the stabilizing agents. Representative stabilizing agents include, but are not limited to, pyruvic acid, oxalacetic acid, glyoxylic acid, mesoxalic acid, 2-ketobutyric acid and 2-ketoglutaric acid. Pyruvic acid is preferred. Mixtures of these stabilizing agents can be used if desired. These stabilizing agents can also be provided as ammonium, alkali metal or alkaline earth metal salts, such as sodium salts. The essential (and some optional) components described above are present in the aqueous developing compositions in the general and preferred amounts listed in Table I, all minimum and maximum amounts being approximate. If formulated in dry form, the compositions would have the essential components in amounts readily apparent to one skilled in the art suitable to provide the desired liquid concentrations. Preferably the α-ketocarboxylic acid is present in an amount of at least 0.01 mol/l, the ascorbic acid developing agent is present in an amount of at least 0.01 mol/l and the preservative is a sulfite that is present in an amount of at least 0.01 mol/l or the molar ratio of the α-ketocarboxylic acid to the ascorbic acid developing agent is from 0.125:1 to 1:1, and the molar ratio of the α-ketocarboxylic acid to the preservative is from 0.08:1 to 4:1 or the composition further comprises at least 0.0001 mol/l of a 3-pyrazolidone co-developing agent. Developing Composition General Amount Preferred Amount Ascorbic add developing agent 0.01 to 0.6 mol/l 0.05 to 0.3 mol/l Auxiliary Co-developing agent 0.0001 to 0.08 mol/l 0.01 to 0.04 mol/l Antifoggant 0.0001 to 0.01 mol/l 0.0005 to 0.002 mol/l Preservative (e.g. sulfite ions) 0.01 to 1 mol/l 0.05 to 0.5 mol/l Buffer 0.001 to 1 mol/l 0.3 to 0.8 mol/l α-Ketocarboxylic acid stabilizing agent 0.01 to 0.5 mol/l 0.05 to 0.25 mol/l Within the noted general and preferred ranges, the molar ratio of the stabilizing agent to developing agent is from 0.05:1 to 2.5:1, and preferably from 0.125:1 to 1:1. In addition, the molar ratio of stabilizing agent to sulfite preservative is from 0.05:1 to 6.25:1, and preferably from 0.08:1 to 4:1. In most processing methods in which the developing composition of this invention is used, its use is generally followed by a fixing step using a photographic fixing composition containing a photographic fixing agent. While sulfite ion sometimes acts as a fixing agent, the fixing agents generally used are thiosulfates (including sodium thiosulfate, ammonium thiosulfate, potassium thiosulfate and others readily known in the art), cysteine (and similar thiol containing compounds), mercapto-substituted compounds (such as those described by Haist, Modern Photographic Processing , John Wiley & Sons, N.Y., 1979), thiocyanates (such as sodium thiocyanate, potassium thiocyanate, ammonium thiocyanate and others readily known in the art), amines or halides. Mixtures of one or more of these classes of photographic fixing agents can be used if desired. Thiosulfates and thiocyanates are preferred. In a some embodiments, a mixture of a thiocyanate (such as sodium thiocyanate) and a thiosulfate (such as sodium thiosulfate) is used In such mixtures, the molar ratio of a thiosulfate to a thiocyanate is from 1:1 to 1: 10, and preferably from 1:1 to 1:2. The sodium salts of the fixing agents are preferred for environmental advantages. The fixing composition can also include various addenda commonly employed therein, such as buffers, fixing accelerators, sequestering agents, swelling control agents, and stabilizing agents, each in conventional amounts. In its aqueous form, the fixing composition generally has a pH of at least 4, preferably at least 4.5, and generally less than 6, and preferably less than 5.5. The developing and fixing compositions useful in the practice of this invention can be provided in dry or aqueous form, and can be prepared by dissolving or dispersing the components in water and adjusting the pH to the desired value. The compositions can also be provided in concentrated form, and diluted to working strength just before use, or during use. The components of the compositions can also be provided in a kit of two or more parts to be combined and diluted with water to the desired strength and placed in the processing equipment. The compositions can be used as their own replenishers, or another similar solutions can be used as the replenishers. Processing can be carried out in any suitable processor or processing container for a given type of photographic element (for example, sheets, strips or rolls). The photographic material is generally bathed in the processing compositions for a suitable period of time. In processing black-and-white photographic materials, development and fixing are preferably, but not essentially, followed by a suitable washing step to remove silver salts dissolved by fixing and excess fixing agents, and to reduce swelling in the element. The wash solution can be water, but preferably the wash solution is acidic, and more preferably, the pH is 7 or less, and preferably from 4.5 to 7, as provided by a suitable chemical acid or buffer. After washing, the processed elements may be dried for suitable times and temperatures, but in some instances the black-and-white images may be viewed in a wet condition. For example, exposure and processing of radiographic films can be undertaken in any convenient conventional manner. The exposure and processing techniques of US-A-5,021,327 and 5,576,156 (both noted above), are typical for processing radiographic films. Other processing compositions (both developing and fixing compositions) are described in US-A-5,738,979 (Fitterman et al), US-A-5,866,309 (Fitterman et al), US-A-5,871,890 (Fitterman et al), US-A-5,935,770 (Fitterman et al), US-A-5,942,378 (Fitterman et al). Such processing can be carried out in any suitable processing equipment including but not limited to, a Kodak X-OMAT TM RA 480 processor that can utilize Kodak Rapid Access processing chemistry. Other "rapid access processors" are described for example in US-A-3,545,971 (Barnes et al) and EP-A-0 248,390 (Akio et al). The compositions of this invention can be used in both what are known as "slow access" and "rapid access" processing methods and equipment. For example, black-and-white motion picture films, industrial radiographic films and professional films and papers are generally developed over a longer period of time (for example, for at least 1 minute and up to 12 minutes). Total processing including other steps (for example fixing and washing) would be even longer. "Rapid-access" methods are generally used to process medical radiographic X-ray films, graphic arts films and microfilms and development may be at least 10 seconds and up to 60 seconds (preferably from 10 to 30 seconds). The total processing time (for example including fixing and washing) is as short as possible, but generally from 20 to 120 seconds. An example of a "rapid access" system is that commercially available as the KODAK RP X-OMAT™ processing system that also includes a conventional photographic fixing composition. For either type of processing method, the development temperature can be any temperature within a wide range as known by one skilled in the art, for example from 15 to 50°C. The black-and-white photographic silver halide elements processed using the present invention are generally composed of a conventional flexible, transparent film support (polyester, cellulose acetate or polycarbonate) that has applied to each side one or more photographic silver halide emulsion layers. For radiographic films, it is conventional to use blue-tinted support materials to contribute to the blue-black image tone sought in fully processed films. Polyethylene terephthalate and polyethylene naphthalate are preferred film supports. In general, such elements, emulsions, and layer compositions are described in many publications, including Research Disclosure, publication 36544, September 1994. Research Disclosure is a publication of Kenneth Mason Publications, Ltd., Dudley House, 12 North Street, Emsworth, Hampshire PO10 7DQ England. The support can take the form of any conventional element support. Useful supports can be chosen from among those described in Research Disclosure, September 1996, Item 38957 XV. Supports and Research Disclosure, Vol. 184, August 1979, Item 13431, XII. Film Supports. They can be transparent or translucent polymeric film supports, or opaque cellulosic papers. The support is preferably a transparent film support In its simplest possible form the film support consists of a material chosen to allow direct adhesion of the hydrophilic silver halide emulsion layers or other hydrophilic layers. More commonly, the support is itself hydrophobic and subbing layers are coated thereon to facilitate adhesion of the hydrophilic silver halide emulsion layers. The photographic materials include one or more silver halide emulsion layers that comprise one or more types of silver halide grains responsive to suitable electromagnetic radiation. Such emulsions include silver halide grains composed of, for example, silver bromide, silver iodobromide, silver chlorobromide, silver iodochlorobromide, and silver chloroiodobromide, or any combinations thereof. The silver halide grains in each silver halide emulsion unit (or silver halide emulsion layers) can be the same or different, or mixtures of different types of grains. The silver halide grains can have any desired morphology (for example, cubic, tabular, octahedral), or mixtures of grains of various morphologies. In some embodiments, at least 50% (and preferably at least 70%) of the silver halide grain projected area is provided by tabular grains having an average aspect ratio greater than 8, and preferably greater than 12. Imaging contrast can be raised by the incorporation of one or more contrast enhancing dopants. Rhodium, cadmium, lead and bismuth are all well known to increase contrast by restraining toe development. Rhodium is most commonly employed to increase contrast and is specifically preferred. A variety of other dopants are known individually and in combination, to improve contrast as well as other common properties, such as speed and reciprocity characteristics. Dopants capable providing "shallow electron trapping" sites commonly referred to as SET dopants are specifically contemplated SET dopants are described in Research Disclosure, Vol. 367, Nov. 1994, Item 36736. Iridium dopants are very commonly employed to decrease reciprocity failure. A summary of conventional dopants to improve speed, reciprocity and other imaging characteristics is provided by Research Disclosure, Item 36544, cited above, Section I. Emulsion grains and their preparation, subsection D. Grain modifying conditions and adjustments, paragraphs (3), (4) and (5). Low COV emulsions can be selected from among those prepared by conventional batch double-jet precipitation techniques. A general summary of silver halide emulsions and their preparation is provided by Research Disclosure, Item 36544, cited above, Section I. Emulsion grains and their preparation. After precipitation and before chemical sensitization the emulsions can be washed by any convenient conventional technique using techniques disclosed by Research Disclosure, Item 36544, cited above, Section III. Emulsion washing. The emulsions can be chemically sensitized by any convenient conventional technique as illustrated by Research Disclosure, Item 36544, Section IV. Chemical sensitization. Sulfur and gold sensitization is specifically contemplated. Instability which increases minimum density in negative-type emulsion coatings (i.e., fog) can be protected against by incorporation of stabilizers, antifoggants, antikinking agents, latent-image stabilizers and similar addenda in the emulsion and contiguous layers prior to coating. Such addenda are illustrated by Research Disclosure, Item 36544, Section VII. Antifoggants and stabilizers, and Item 18431, Section II. Emulsion Stabilizers, Antifoggants and Antikinking Agents. The silver halide emulsion and other layers forming the layers on the support contain conventional hydrophilic colloid vehicles (peptizers and binders) that are typically gelatin or a gelatin derivative (identified herein as "gelatino-vehicles"). Conventional gelatino-vehicles and related layer features are disclosed in Research Disclosure, Item 36544, Section II. Vehicles, vehicle extenders, vehicle-like addenda and vehicle related addenda. The emulsions themselves can contain peptizers of the type set out in Section II noted above, paragraph A. Gelatin and hydrophilic colloid peptizers. The hydrophilic colloid peptizers are also useful as binders and hence are commonly present in much higher concentrations than required to perform the peptizing function alone. The gelatino-vehicle extends also to materials that are not themselves useful as peptizers. The preferred gelatino-vehicles include alkali-treated gelatin, acid-treated gelatin or gelatin derivatives (such as acetylated gelatin and phthalated gelatin). Depending upon the use of the materials, the binder-containing layers can be hardened or unhardened. Some photographic materials can include a surface overcoat on each side of the support that are typically provided for physical protection of the emulsion layers. In addition to vehicle features discussed above the overcoats can contain various addenda to modify the physical properties of the overcoats. Such addenda are illustrated by Research Disclosure, Item 36544, Section IX. Coating physical property modifying addenda, A. Coating aids, B. Plasticizers and lubricants, C. Antistats, and D. Matting agents. Interlayers that are typically thin hydrophilic colloid layers can be used to provide a separation between the emulsion layers and the surface overcoats. It is quite common to locate some emulsion compatible types of surface overcoat addenda, such as anti-matte particles, in the interlayers. Examples of black-and-white papers and films that can be processed using the present invention include, but are not limited to, KODAK TRI-X-PAN Black and White Film, KODAK PLUS X-PAN Black and White Film, KODAK TMAX 100 and 400 speed Black and White Films, KODAK POLYMAX II RC Black and White Papers, KODAK KODABROME II RC F Black and White Paper, KODAK PMAX Art RC V Black and White Paper, KODAK POLYCONTRAST III RC Black and White Paper, KODAK PANALURE Select RC Black and White Paper, KODAK POLYMAX FINE ART Black and White Papers, KODAK AZO Black and White Papers, ILFORD MULTIGRADE IV RC and FB Black and White Papers, ILFORD ILFOBROME GALARIE Black and White Papers, and AGFA MULTICONTRAST CLASSIC, PREMIUM Black and White Papers, various KODAK T-MAT Radiographic Films, various KODAK INSIGHT Radiographic Films, KODAK X-OMAT Duplicating Film, various KODAK EKTASCAN Radiographic Films, KODAK CFT, CFL, CFS and CFE Radiographic Films, KODAK EKTASPEED and EKTASPEED PLUS Dental Films and KODAK ULTRASPEED Dental Film. The black-and-white developing composition can also be used in the first development step to provide color positive images using color reversal photographic silver halide materials. Such materials are usually processed using the following sequence of processing steps: first (or black-and-white) development, washing, reversal re-exposure, color development, bleaching, fixing, washing and/or stabilizing. Another useful process has the same steps, but stabilizing is carried out between color development and bleaching. Such conventional steps are described, for example, in US-A-4,921,779 (Cullinan et al), US-A-4,975,356 (Cullinan et al), US-A-5,037,725 (Cullinan et al), US-A-5,523,195 (Darmon et al) and US-A-5,552,264 (Cullinan et al) for the processing of color reversal films (using the conventional Process E-6). Other details are provided in Research Disclosure, publication 38957 (noted above), and references noted therein. Color reversal films used in the practice of this invention are comprised of a support having thereon a plurality of photosensitive silver halide emulsion layers that can contain any conventional silver halide (or mixture thereof). Such films generally have silver halide emulsions having at least 1 mol % iodide based on total silver. Useful supports are well known and include polyester films, polycarbonate films and cellulose acetate films. The silver halide layers include conventional binder materials, and other conventional addenda. Some specific commercially available color reversal photographic films that can be processed using this invention include EKTACHROME and KODACHROME Color Reversal Films (Eastman Kodak Company), FUJICHROME Color Reversal Films (Fuji Photo Film Co., Ltd.), AGFACHROME Color Reversal Films (AGFA), KONICACHROME Color Reversal Films (Konica) and SCOTCHCHROME Color Reversal Films (Imation). Photographic reversal compositions are also known in the art, including for example US-A-3,617,282 (Bard et al) and US-A-5,736,302 (Buongiorne et al). The color development is generally accomplished with a color developing composition containing the chemical components conventionally used for that purpose, including color developing agents, buffering agents, metal ion sequestering agents, optical brighteners, halides, antioxidants, sulfites and other compounds readily apparent to one skilled in the art. Examples and amounts of such components are well known in the art, including for example US-A-5,037,725 (Cullinan et al) and US-A-5,552,264 (Cullinan et al). Another useful composition for color reversal processing is a composition that provides dye image stabilization. If in liquid form, this composition generally includes a dye stabilization compound (such as an alkali metal formaldehyde bisulfite, hexamethylenetetramine and various formaldehyde releasing compounds), buffering agents, bleach-accelerating compounds, secondary amines, preservatives, and metal sequestering agents. All of these compounds are well known in the art, including US-A-4,839,262 (Schwartz), US-A-4,921,779 (Cullinan et al), US-A-5,037,725 (Cullinan et al), US-A-5,523,195 (Darmon et al) and US-A-5,552,264 (Cullinan et al). A final rinse composition generally has a pH of from 5 to 9 (in liquid form), and can include one or more surfactants (anionic, nonionic or both), biocides and buffering agents as is well known in the art. See for example, US-A-3,545,970 (Giorgianni et al), US-A-5,534,396 (McGuckin et al), US-A-5,645,980 (McGuckin et al), US-A-5,667,948 (McGuckin et al) and US-A-5,716,765 (McGuckin et al). Advantageously, the black-and-white developing composition of this invention can be included as part of a processing kit that includes one or more additional photographic processing compositions needed for providing the desired images. For example, additional photoprocessing compositions include photographic fixing compositions for processing black-and-white photographic materials, or photographic color developing, bleaching, fixing and reversal compositions for processing color reversal photographic materials. The kit may also include washing solutions, instructions, fluid or composition metering devices, or any other conventional components of a photographic processing kit. All of the components can be suitably packaged in dry or liquid form in glass or plastic bottles, fluid-impermeable packets or vials. The following examples are provided for illustrative purposes and are not to be considered limiting in any manner. Example 1: The four photographic black-and-white developing compositions described in TABLE I below (amounts in mol/l), with and without a stabilizing agent, were allowed to stand for one week at room temperature in an open container. Each solution was monitored daily for stability and discoloration. TABLE II and FIG. 1 show comparisons of the absorbance of the solutions at 410 nm. The pH of each solution was observed to decrease by 0.01-0.02 during the standing time. In FIG. 1, the Control A-C data are represented by Curves A-C, respectively, and the Invention data are represented by Curve D. COMPONENT Control A Invention Control B Control C DTPA, 40% 0.0034 0.0034 0.0034 0.0034 Potassium sulfite, 45% 0.32 0.32 0.32 0.32 Potassium carbonate, 47% 0.72 0.72 0.72 0.72 Ascorbic acid 0.2 0.2 0.2 0.2 HMMP 0.012 0.012 0.012 0.012 Sodium pyruvate 0 0.1 0 0 Glycine 0 0 0.2 0 Alanine 0 0 0 0.2 Benzotriazole 0.0017 0.0017 0.0017 0.0017 Potassium bromide 0.034 0.034 0.034 0.034 pH 10.3 10.3 10.3 10.3 DTPA = diethylenetriaminepentaacetic acid HMMP = 4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone Time (days) Absorbance @ 410nm Control A Invention Control B Control C 0 0.08 0.09 0.09 0.09 2 0.168 0.113 0.166 0.195 4 0.451 0.157 0.360 0.439 7 0.998 0.227 0.705 0.835 The results indicate that Control A (containing no stabilizing agent) and Controls B and C (containing common amino acid stabilizing agents glycine and alanine) failed to provide the composition stability that sodium pyruvate did for the present invention. Thus, sodium pyruvate was the most effective stabilizing agent for retarding discoloration (retarding aerial oxidation) of the ascorbic acid developing compositions. Examples 2-5: In these examples, we evaluated the effect of different levels of the preferred stabilizing agent sodium pyruvate on the stability and discoloration of ascorbic acid developing compositions. The five photographic black-and-white developing compositions shown in TABLE III were allowed to stand for one week at room temperature in an opened container. The amounts are shown as mol/l concentrations. The solutions were monitored visually and spectrophotometrically for discoloration. FIG. 2 shows the comparisons of the absorbances of the solutions at 410 nm. The data for Control D are represented by Curve A and the data for Examples 2-5 are represented by Curves B-E, respectively. COMPONENT Control D Invention Invention Invention Invention DTPA, 40% 0.0034 0.0034 0.0034 0.0034 0.0034 Potassium sulfite, 45% 0.32 0.32 0.32 0.32 0.32 Potassium carbonate, 47% 0.72 0.72 0.72 0.72 0.72 Ascorbic acid 0.2 0.2 0.2 0.2 0.2 HMMP 0.012 0.012 0.012 0.012 0.012 Sodium pyruvate 0 0.025 0.05 0.1 0.164 Diethanolamine 0.074 0.074 0.074 0.074 0.074 Benzotriazole 0.0017 0.0017 0.0017 0.0017 0.0017 Potassium bromide 0.034 0.034 0.034 0.034 0.034 pH 10.3 10.3 10.3 10.3 10.3 The results in FIG. 2 show that even low levels of sodium pyruvate improved the discoloration of ascorbic acid developing compositions. In all cases, the decrease in pH was comparable to or slightly better than the Control D composition. Examples 6-8: In these examples, we evaluated the effect of the amount of sulfite in black-and-white developing compositions containing a pyruvate stabilizing agent (the concentrations are shown in mol/l). As shown in TABLE IV below, compositions containing 0 to 0.32 mol/l of sulfite at a 0.1 mol/l of sodium pyruvate were monitored in replication under accelerated oxidation conditions at ambient temperature. The percentages of ascorbic acid developing agent remaining after four days are shown in TABLE V below. COMPONENT Control E Control F Example 6 Example 7 Example 8 DTPA, 40% 0.0034 0.0034 0.0034 0.0034 0.0034 Potassium sulfite, 45% 0.32 0 0.08 0.16 0.32 Potassium carbonate, 47% 0.72 0.72 0.72 0.72 0.72 Ascorbic acid 0.2 0.2 0.2 0.2 0.2 HMMP 0.012 0.012 0.012 0.012 0.012 Sodium pyruvate 0 0.1 0.1 0.1 0.1 Diethanolamine 0.074 0.074 0.074 0.074 0.074 Benzotriazole 0.0017 0.0017 0.0017 0.0017 0.0017 Potassium bromide 0.034 0.034 0.034 0.034 0.034 pH 10.3 10.3 10.3 10.3 10.3 Composition Ascorbic acid (%) Initial day Day 2 Day 4 Control E 100 90 70.1 Control F 100 85.8 71 Example 3 100 85.8 73.4 Example 4 100 90.1 75.8 Example 5 100 89.7 75.4 The data in TABLE V show that after four days, Control F composition containing 0.1 mol/l of sodium pyruvate alone (no sulfite) had 71% ascorbic acid remaining compared to 70% with the Control composition containing 0.2 mol/l sulfite (but no sodium pyruvate). TABLE V also shows that a combination of sulfite and sodium pyruvate (Examples 3-5) in molar ratios of 0.8:1 to 3.16:1 (sulfite: pyruvate) improved the stability of ascorbic acid over the use of sulfite or sodium pyruvate alone. These results occurred with very little loss in HMMP and only a small drop in pH after the four days of keeping. Example 9: In this example, we evaluated the effect of another α-ketocarboxylic acid stabilizing agent, oxalacetic acid, in ascorbic acid black-and-white developing compositions. The compositions shown in TABLE VI below (Invention containing 0.2 mol/l of oxalacetic acid) were aerated at 325 ml/min at ambient temperature. All concentrations are in mol/l. The compositions were monitored visually and spectrophotometrically for discoloration. FIG. 4 compares the absorbance of the two compositions at 410nm. The data for Control G are represented by Curve A, and the data for the Invention are represented by Curve B. COMPONENT Control G Invention DTPA, 40% 0.0034 0.0034 Potassium sulfite, 45% 0.32 0.32 Potassium carbonate, 47% 0.72 0.72 Ascorbic acid 0.2 0.2 HMMP 0.012 0.012 Oxalacetic acid 0 0.2 Benzotriazole 0.0017 0.0017 Potassium bromide 0.034 0.034 pH 10.3 10.3 The results in FIG. 4 show that oxalacetic acid also improved the stability and discoloration of the ascorbic acid developing composition with little or no loss in HMMP and a small drop in pH over the life of the experiment. Example 10: The developing composition of Example 1 above was used to process imagewise exposed samples of commercially available KODAK POLYMAX II and Ilford MULTIGRADE IV Black and White Papers in the following manner. The paper samples were developed using 300 ml of the Example 1 developing composition for 1 minute at 21°C, fixed using 400 ml of commercially available KODAK RAPID Fixer (1:3), diluted 1:1, for 2 minutes at ambient temperature, washed with tap water for 5 minutes and dried in the air at room temperature. The desired black-and-white images were obtained in all of the samples.

Claims: A black-and-white photographic developing composition that comprises: a) an ascorbic acid developing agent, and a preservative, the developing composition characterized as further comprising a stabilizing amount of a α-ketocarboxylic acid, wherein the molar ratio of the α-ketocarboxylic acid to the ascorbic acid developing agent is from 0.05:1 to 2.5:1, the molar ratio of the α-ketocarboxylic acid to the preservative is from 0.05:1 to 6.25:1, and the composition is essentially free of dihydroxybenzene compounds. The composition of claim 1 wherein the α-ketocarboxylic acid is present in an amount of at least 0.01 mol/l, the ascorbic acid developing agent is present in an amount of at least 0.01 mol/l and the preservative is a sulfite that is present in an amount of at least 0.01 mol/l.. The composition of claim 1 or 2 wherein the molar ratio of the α-ketocarboxylic acid to the ascorbic acid developing agent is from 0.125:1 to 1:1, and the molar ratio of the α-ketocarboxylic acid to the preservative is from 0.08:1 to 4:1. The composition of any of claims 1 to 3 further comprising at least 0.0001 mol/l of a 3-pyrazolidone co-developing agent. The composition of any of claims 1 to 4 that is essentially free of alkanolamines. A method of providing an image comprising contacting an imagewise exposed silver halide photographic material with the black-and-white photographic developing composition of any of Claims 1 to 5 for at least 10 seconds. The method of claim 6 wherein the contacting is carried out for from 10 to 60 seconds. The method of claim 6 or 7 wherein the photographic material is a color reversal photographic material. The method of claim 6 or 7 wherein the photographic material is a black-and-white photographic film or paper. A photographic processing kit comprising: a black-and-white photographic developing composition as claimed in any of claims 1 to 5, and one or more additional photographic processing compositions.

Inventors: HAYE SHIRLEYANNE ELIZABETH, HUSTON JANET MARIE, MCGUCKIN HUGH GERALD, ROUSSILHE JACQUES, HAYE, SHIRLEYANNE ELIZABETH, HUSTON, JANET MARIE, MCGUCKIN, HUGH GERALD, ROUSSILHE, JACQUES
Applicants: EASTMAN KODAK CO, EASTMAN KODAK COMPANY
Application year: 2001
Main classification: G03C5
IPC codes: G03C5