IMPROVED DEVELOPER SYSTEMS FOR HYDRAZINE CONTAINING FILMS

Abstract: An improved system for rapid access processing of photographic silver halide elements comprises a hydrazine-containing silver halide element in combination with a developer solution comprising at least one ascorbic acid developing agent selected from the goup consisting of ascorbic acid, derivatives thereof, and their salts. This system has a long shelf-life, is more environmentally friendly and produces excellent sensitometry and images with much lower pepper and better dot quality. A process of image formation using the system is also provided.

Description: IΣΣ EL % IMPROVED DEVELOPER SYSTEMS FOR HYDRAZINE CONTAINING FILMS 5 BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the field of photographic 10 silver halide systems and more specifically to the processing of photographic silver halide elements. Still more specifically, this invention relates to rapid access photographic elements containing hydrazine compounds and to processing solutions related thereto. 15 2. Description of the Prior Art Photographic silver halide elements have long been used to record images and are often preferred because they have excellent image reproduction characteristics and high speed. In the field of lithography, a host of 20 varied silver halide elements have been described for this method of reproduction, most of which have the high contrast and density needed to produce the good half-tone dots necessary for this reproduction method. However, most of these elements require a so-called 25 "induction period" during development, which means that there is an initial lag period during which processing is relatively slow prior to infectious development when the high contrast and density are achieved. In an on-going effort to reduce the induction 30 period and thereby make a rapid access system, it has been observed that rapid access can be achieved, for example, by the addition of hydrazines and derivatives thereof to either the silver halide emulsion or to the developing solutions. It has been preferable to add the hydrazine compounds to the emulsion, however, since the processing thereof can be better controlled. Research Disclosure 23510 (November 1983) presents a summary of the extensive literature on this subject. Although the use of hydrazine compounds reduced the induction period, these systems resulted in a loss of image quality such as lower dot quality, or the image may have a spotted appearance, or so-called "pepper". This is extremely undesirable and there have been numerous attempts in the prior art to reduce the propensity of the rapid access lithographic systems to produce pepper. The developing solutions for elements containing hydrazine compounds typically contain conventional silver halide developing agents such as hydroquinone or derivatives of hydroquinone. It is sometimes necessary to add a super-additive developing agent such as phenidone or metol, for example. These developing solutions are necessarily kept at a fairly high pH which is deleterious to the life expectancy of the solution itself and to the processing equipment. Additionally, these prior art developing solutions tend to be environmentally hazardous and will produce sludge in the developing tanks. Ruger, U.S. Patent 4,937,160 teaches a novel group of hydrazides which can be used in a manner similar to the prior art hydrazines but with the advantage of somewhat lower processing pH. Silver halide elements containing these novel hydrazides, however, also suffer from the other disadvantages noted above, such as the appearance of "pepper" and the relative toxicity of the developer solutions. The use of ascorbic acid or any of its derivatives as developing agents for silver halide elements, is known in the prior art. For example, James, J. Amer. Che . Soc, Jan. 1944 (Communication No. 951 from the Kodak Research Laboratories) states that ascorbic and iso-ascorbic acid can be used as developing agents for silver halide elements. Similarly, James, U.S. Patent 2,688,549, teaches the use of a developer solution comprising 3-pyrazolidone and ascorbic acid or its sugar analogs. However, these prior art developing solutions were very slow and found little or no commercial success. Recently, because ascorbic acid and its derivatives are environmentally safer than hydroquinone, there have been attempts to enhance conventional developing solutions by substituting ascorbic acid or erythorbic acid together with salts thereof for hydroquinone. For example, U.S. Appln. Ser. No. 07/472,803, filed Jan. 31, 1990, discloses a hydroquinone-free and alkali metal hydroxide-free developer solution wherein the developing agent consists of a salt of ascorbic or erythorbic acid either alone or in combination with ascorbic or erythorbic acid. In addition to the environmental advantage of removing hydroquinone from the developer solution, these developing agents are also environmentally advantageous because they tend to reduce the sludge commonly found in the developing tanks. However, a shortcoming of the aforementioned ascorbate- containing developer solutions is that they cannot be used with hydrazine containing films to achieve satisfactory speed, contrast and image quality. The prior art ascorbate developer solutions are much lower in pH (e.g. 9.7-10) and are not formulated specifically for the rapid access processing of hydrazine films. SUMMARY OF THE INVENTION It is an object of this invention to provide an improved system for rapid access processing of photographic silver halide elements comprising, in combination: a) a photographic silver halide element of the type containing a hydrazine compound; and b) a developer solution comprising at least one ascorbic acid developing agent selected from the group consisting of ascorbic acid, derivatives thereof, and salts of' either. It is another object of the invention to provide an improved process of image formation comprising the step of developing an imagewise exposed photographic element of the type containing a hydrazine compound in a developer solution comprising at least one ascorbic acid developing agent selected from the group consisting of ascorbic acid, derivatives thereof, and salts of either. In is still another object of the invention to provide an improved rapid access developer solution for hydrazine containing films comprising an ascorbate developing agent, at least one alkanol amine and having a pH in the . range 10.65 to about 12.0. These and other objects of the invention will become apparent upon a further reading of the specification and the appended claims. DETAILS OF THE INVENTION The developing agents that are useful within the metes.and bounds of this invention include ascorbic acid r its derivatives, such as L- or D-ascorbic acid as well as erythorbic acid (also known as iso-erythorbic acid) and the alkali salts of either, for example. These developing agents are effective when used alone or in combination with known hydroquinone developing agents. In the preferred embodiment, a mixture of sodium L-ascorbate and L-ascorbic acid or sodium erythorbate is the developing agent and no hydroquinone is present in the developer solution. The preferred embodiment also contains a small amount of a super- additive developer, such as l-phenyl-3-pyrazolidone or derivatives thereof, among others. In addition to the above mentioned developing agents, the developer solutions of the present invention contain at least one alkanol amine in amounts suitable to effect the desired development rates. The alkanol amines suitable for use in the present developer solutions include those commonly employed by the prior art in the so-called w lith processing field," such as 1- piperidinethanol; 3-piperidino-l,2-propanediol; 1- methyl-2-piperidenemethanol; 1-(2-hydroxyethyl)- piperazine; 1,4-bis-(2-hydroxyethyl)-piperazine; diethanolamino ethanol; 3-(diethylamino)-1,2- propanediol; and N-butyl diethanol amine, among others. These compounds may be present in the developer solution in amounts of 5 to 50 grams per liter, and preferably in an amount of 20 grams per liter, of developer solution. Other developer adjuvants preferred for the developing solutions according to this invention include antioxidants (e.g. alkali metal sulfites) , sequestering agents (e.g. ethylene diamine tetraacetic acid, sodium salt), development accelerators (e.g. polyalkylene oxides) and the like. Buffers and pH adjusting compounds may also be mentioned here. Antifoggants and restrainers (KBr, Benzotriaizole PMT, etc.) may also be employed as is well known in the art. Silver halide emulsions useful within the ambit of this invention include any of the commonly available silver halides such as silver bromide, silver chloride, silver iodide or mixtures of two or more of these halide salts. These emulsions may be precipitated by any of the conventional and well-know techniques such as splash or balanced double jet, for example. After precipitation of the grains in a small amount of gelatin, the grains are conventionally dispersed in a bulking amount of gelatin and then brought to their optimum sensitivity with gold and sulfur salts, as is well-known to those of normal skill in the art. Sensitizing dyes, antifoggants, dispersing agents, coating aids and hardeners may also be added if desired. Specifically, these emulsions will contain one of the prior art and known hydrazine compounds such as those previously described, with one of the hydrazides of the aforementioned Rϋger, U.S. Patent 4,937,160 preferably being used in accordance with the teachings of that patent. A most preferred silver halide emulsion will contain 98% bromide and 2% iodide, and will contain 80 g of gelatin per mole of silver halide present. This emulsion will be sensitized with sodium thiosulfate and green sensitizing dye and will contain 250 mg of 2-(4- Benzyloxyρhenyl)-l-Pyridinium acetyl-Hydrazine Bromide (BOP-HMP) per 1.5 moles of silver halide present. After full sensitization, standard antifoggants, coating aids, etc. are added and the emulsion coated on a 4 mil dimensionally stable, polyethylene terephthalate film support to about 4.4 g/m 2 coating weight. Other useful supports such as cellulosic supports (e.g. cellulose acetate, etc.) and other common supports for the coating of silver halide elements which are well-known in the prior art may be used. A typical and preferred developer solution of this invention will contain the following ingredients in the ranges shown. Ingre ient Sodium Erythorbate Trisodium ethylenediamine- tetraacetic acid (Na 3 EDTA) Sodium Sulfite (Anhyr.) Potassium Bromide 45% KOH Soln. (aq.) Dimezone S (4-Hydromethyl-4- methyl-l-phenyl-3-Pyrazoli- done) Benzotriazole Glucono delta Lactone l-Phenyl-5-Mercaptotetrazole Potassium Carbonate 2-Mercaptobenzothiazole 3-(Diethylamino)-1,2- Propanediol N-butyl diethanol amine Water to Adjust pH to at least 11. This invention will now be illustrated by the following examples of which Example 2, using N-butyl diethanol amine is considered to be the best mode. EXAMPLE 1 A standard control developer commonly used for the development of hydrazine containing films was prepared as follows: Amount (g/liter of Ingredient ork ng strength) Na 3 EDTA 3.87 Sodium Bisulfite 62 Hydroquinone 25 Metol (N-Methyl-p-aminophenol sulfate) 1.5 KBr (Potassium Bromide) 3.0 3-(Diethylamino)-l,2-propanediol (DEAPD) 24.23 Benzotriazole 0.50 l-Phenyl-5-mercaptotetrazole (PMT) 0.05 Glucono Delta Lactone 1.0 45% Aq. KOH (Potassium Hydroxide Solution) 105.6 Potassium Carbonate (anhy.) 53 Water to 1 liter Another developer solution representative of this invention was prepared as follows: Amount (g/liter of Ingredient working strength) Na 3 EDT 4 Sodium Sulfite 15 Sodium-L-Ascorbate 60 L-Ascorbic Acid 17 PMT 0.05 GDL 1.0 45% Aq. KOH 105 Potassium Carbonate 53 DEAPD 25 Dimezone S in Acetone 0.5 gm/25 ml KBr 5.0 5-Methyl Benzotriazole 0.5 Water to 1 liter The pH of both the control and developer of this invention were kept the same, e.g., 11.0 plus or minus 0.05 units. A film was prepared from an emulsion which comprised 98 mol % bromide and 2 mol % iodide dispersed in 80 gm of gelatin per mole of silver halide. This emulsion was brought to its optimum sensitivity by digestion with sodium thiosulfate (sulfur salt) and Green Sensitizing Dye for 40 minutes at a temperature of 130°F. After digestion, antifoggants, stabilizers, coating/wetting aids and hardeners were added as well- known to those of normal skill in the art along with 250 mg/1.5 mole of silver halide of a hydrazide such as that taught in the aforementioned Rϋger patent (BOP-HMP) . The emulsion was then coated to 4.4 g/m 2 on a 4 mil biaxially oriented and heat-set polyethylene terephthalate film support having well-known resin and gel sub layers applied thereto. A thin layer of gelatin (e.g., 10 mg/dm 2 ) was applied over the emulsion layer to act as a protective antiabrasion layer, as is well- known. Two samples of this film were taken and given an exposure (D. S. America Camera, halftone & continuous tone wedge targets, through a Beta GNE-MR Screen, 20 second exposure) and then developed 45 seconds at 95°F in a tray containing one of the above developers. Each developed sample was then fixed, washed and dried in the usual manner and the image analyzed for dot quality, speed, pepper, top density and contrast. The film developed in the developer of this invention had substantially equivalent speed, fog, contrast and density and had good dot quality as compared to the control. However, the film developed in the developer of this invention had essentially no pepper as compared to that developed in the control developer. EXAMPLE 2 The following ingredients were blended to make a stock solution representing the developer of this invention: These ingredients were thoroughly mixed, diluted to 4,000 ml and the pH adjusted to 11.05. The following alkanol amines were tested at concentrations of 5,10,20 and 40 gm/liter for their efficacy in this developer solution: 1-piperidinethanol 3-piperidino-l,2-propandiol l-methyl-2-piperidenemethanol l-methyl-3-piperidenemethanol 1-(2-hydroxyethyl)-piperazine 1,4-bis-(2-hydroxyethyl)-piperazine Diethylamino ethanol 3-(Diethylamino)-1-2-propanediol N-butyl diethanol amine All of the above developing solutions were tested with the film of Example 1 and gave excellent results as far as speed, contrast, dot quality and pepper. Additionally, the presence of the alkanol amine increased the developer activity as compared to the control developer. N-butyl diethanol amine is the preferred alkanol amine, not because of any superior results as compared to the other alkanol amines of this invention, but because it is less toxic and has a less objectionable odor. EXAMPLE 3 To the standard control developer of Example 1, an addition of 5.0 gm/1 of sodium L-ascorbate was added and film prepared, exposed, developed for 60 seconds, fixed, washed and dried as in Example 1. A reading of the pepper- level on this film was made by examination with a 50X magnifier and compared to similarly treated film in the standard control developer. A very significant reduction in the size and frequency of the pepper spots was observed for the ascorbate-containing developer, without appreciable effect on sensitometry or deterioration in dot quality. Similar advantageous effects were observed when sodium D-isoascorbate, sodium erythorbate and dehydroascorbic acid were substituted for the sodium L-ascorbate. EXAMPLE 4 In order to test a developer solution made according to this invention under machine processing conditions, the following solution was prepared: These ingredients were thoroughly mixed and the solution diluted to 1 liter. The pH was adjusted to 11.4. Samples of this solution were placed in a desk-top. Convenience Processor® (E. I. du Pont de Nemours and Co., Wilmington, DE) and multiple strips of the same film described in Example 1 were processed through this machine over a period of several days. The developer functioned well and the sensitometric properties of the film were excellent. The pepper was low compared to controls " processed in an identical processor using a conventional, rapid access, hydroquinone-containing developer. In addition, the life of the developer of this invention was considerably longer than the control developer. For example, a sample of standard, hydroquinone developer, left opened so that aerial oxidation could occur, darkened visibly and lost activity after a short period of time. Under the same conditions, the developer of this invention was much clearer and retained most of its activity.

Claims: What is claimed is: 1. An improved system for rapid access processing of photographic silver halide elements comprising, in combination: a) a photographic silver halide element of the type containing a hydrazine compound; and b) a developer solution comprising at least one ascorbic acid developing agent selected from the group consisting of ascorbic acid, derivatives thereof, and salts of either. 2. The system of Claim 1, wherein said at least one ascorbic acid developing agent is sodium ascorbate. 3. The system of Claim 1, wherein said at least one ascorbic acid developing agent is a mixture of L- ascorbic acid and sodium ascorbate. 4. The system of Claim 1, wherein said developer solution further comprises a hydroquinone developing agent. 5. The system of Claim 1, wherein said photographic silver halide element comprises a gelatino, silver halide emulsion coated on a support. 6. The system of Claim 5, wherein said emulsion comprises 98 mol % Br and 2 mol % I and wherein said hydrazine compound is 2-(4-benzyl-oxyphenyl)-1- pyridinium acetyl)-Hydrazine Bromide. 7. The system of Claim 1, wherein said developer solution further comprises 5 to 50 gm/liter of an alkanol amine and has a pH in the range 10.7 to about 12.0 8. The system of Claim 1, wherein said developer solution comprises: Ingredient Amount Sodium Erythorbate 10-150 gm Trisodium Ethylenediamine- 1.0-10.0 gm tetraacetic acid (Na3ED A) Sodium Sulfite (Anhyr.) 10-150 gm Potassium Bromide 1.0-10.0 gm 45% KOH Soln. (aq.) 10-50 gm Dimezone S (4-Hydromethyl-4-Methyl- 0.01-1.5 gm l-Phenyl-3-Pyrazolidone) Benzotriazole 0.1-1.5 gm Glucono Delta Lactone 0.5-2.5 gm l-Phenyl-5-Mercaptotetrazole 0.01-0.20 gm Potassium Carbonate 10-100 gm 2-Mercaptobenzothiazole 0.01-20 gm 3-(Diethylamino)-1,2-Propanediol 5-50 gm 1-Piperidine ethanol 5-50 gm Water to 1 liter 9. A process of image formation comprising the step of developing an imagewise exposed photographic element of the type containing a hydrazine compound in a developer solution comprising at least one ascorbic acid developing agent selected from the group consisting of ascorbic acid, derivatives thereof, and salts of either. 10. The process of Claim 9, wherein said photographic element comprises a gelatino silver halide emulsion coated on a support and wherein said hydrazine compound is 2-(4-benzyl-oxyphenyl)-1-pyridinium acetyl- Hydrazine Bromide. 11. The process of Claim 9, wherein said at least one ascorbic acid developing agent is sodium ascorbate. 12. The process of Claim 9, wherein said developing agent is a mixture of sodium ascorbate and L- ascorbic acid. 13. The process of Claim 9, wherein said developer composition further comprises a hydroquinone developing agent. 14. The process of Claim 9, wherein said developer solution further comprises 5 to 50 gm/liter of an alkanol amine and has a pH in the range 10.7 to about 12.0. 15. An improved rapid access developer solution for hydrazine-containing films comprising at least one alkanol amine; at least one ascorbic acid developing agent selected from the group consisting of ascorbic acid, derivatives thereof, and salts -of either; and wherein said developing solution has a pH in the " range of 10.7 to about 12.0. 16. The developer solution of Claim 15, wherein said at least one ascorbic acid developing agent is sodium ascorbate. 17. The developer solution of Claim 15, wherein said at least one ascorbic acid developing agent is a mixture of L-ascorbic acid and sodium ascorbate. 18. The developer solution of Claim 15, further comprising a hydroquinone developing agent. 19. The developer solution of Claim 15, wherein said hydrazine-containing film comprises a gelatino, silver halide emulsion coated on a support. 20. The developer solution of Claim 19, wherein said emulsion comprises 98 mol % Br and 2 mol % I and wherein said hydrazine compound is 2-(4-benzyl- oxyphenyl)-1-pyridinium acteyl)-Hydrazine Bromide. 21. The developer solution of Claim 15, wherein said at least one alkanol amine comprises 5 to 50 gm/liter of N-butyl diethanol amine and said developer solution has a pH of about 11.0. 22. The developer solution of Claim 15, comprising: Ingredient Amount Sodium Erythorbate 10-150 gm Trisodium Ethylenediamine- 1.0-10.0 gm tetraacetic acid ( a 3 EDTA) Sodium Sulfite (Anhyr.) 10-150 gm Potassium Bromide 1.0-10.0 gm 45% KOH Soln. (aq.) 10-50 gm Dimezone S (4-Hydromethyl-4-Methyl- 0.01-1.5 gm 1-Pheny1-3-Pyrazolidone) Benzotriazole 0.1-1.5 gm Glucono Delta Lactone 0.5-2.5 gm l-Phenyl-5-Mercaptotetrazole 0.01-0.20 gm Potassium Carbonate 10-100 gm 2-Mercaptobenzothiazole 0.01-20 gm 3-(Diethylamino)-1,2-Propanediol 5-50 gm N-butyl ethanol amine 5-50 gm Water to 1 liter

Inventors: PANGRATZ WILLIAM ROBERT, PANGRATZ, WILLIAM, ROBERT
Applicants: DU PONT, E.I. DU PONT DE NEMOURS AND COMPANY
Application year: 1992
Main classification: G03C1
IPC codes: G03C1, G03C5