PHOTOGRAPHIC TANNING DEVELOPER FORMULATION

Abstract: An alkaline aqueous tanning developing solution for photographic image development comprising at least one hydroxylamine derivative, preferably also containing at least one water miscible polyhydroxy aliphatic organic solvent.

Description: PHOTOGRAPHIC TANNING DEVELOPER FORMULATION Field of the Invention This invention relates to photographic processing wherein a tanning developer solution is utilized to prepare hardened imagewise exposed silver halide gelatin emulsion layers. Background Art It is well known in the art to utilize developing agents to insolubilize colloidal materials, such as gelatin, in a silver halide emulsion. Typically, in the employment of this hardening reaction, a tanning developer is utilized to develop an exposed silver halide colloidal emulsion, after which the unexposed areas may be washed away utilizing warm water, to thereby provide a photographic image or resist of the hardened or tanned colloidal material. During processing, the oxidation products of the developing solution which are formed in the exposed regions of the image diffuse through the gelatin layers containing same, hardening the colloidal gelatin itself. Such photographic emulsion layers typically may contain colorants, e.g., pigments, carbon black, etc., which may impart color to the thus formed images. Literature examples of such photographic elements include those described in U.S. Patent Nos. 3,364,024; 2,837,430; 4,283,479; 4,299,909; 4,233,392; 4,233,393; 4,254,210; and G.B. Patent 2,026,186A. Tanning developing solutions typically used for such photographic elements are simple aqueous solutions which contain therein a high content of sulfate salts, wherein the tanning developing agents themselves are incorporated within the gelatin layers of the 'silver halide emulsion-containing article. In silver halide systems, antioxidants are commonly utilized during development, e.g., sulfites. In a tanning developer system, the developing solution is, however, typically devoid of such common antioxidants, or contain a reduced level thereof, due to their harmful effect on the tanning process, as is described in C. E. K. Mees and T. H. James, The Theory Of The Photographic Process, 3rd Edition, the McMillan Co., 1966, at page 304. As a result, the image processing step is susceptible to air oxidation, which can display itself through the non-imagewise hardening of the gelatin layers when the photographic element is exposed to air while wet with the developing solution. To attempt to combat this problem, the literature has "reported the use of materials such as ascorbic acid as an antioxidant, as described in GB Patent 560,371 and U.S. Patent No. 2,415,666, and ascorbic acid borates as described in U.S. Patent No. 2,967,772. Conversely, U.S. Patent No. 3,293,035 discloses the use of primary amines and monohydroxy aromatic compounds, themselves not being developing agents, to improve selective tanning only in image areas, while U.S. Patent No. 2,404,724 details the use of urea as a softening agent for gelatin coatings. Nitrile compounds are further cited as stabilizing agents for graphic arts developing solutions; e.g., U.S. Patent No. 3,772,022. Hydroxyiamine derivatives have been taught to supplement the stability of color developing solutions, as for example in U.S. Patent " Nos. 3,746,544; 4,155,763; 4,055,426; and 4,170,478. Alkanolamines and their derivatives are taught to be well known as pH regulators in the area of graphic arts developers, see for example, U.S. Patent No. 3,984,243. Furthermore, in the area of dye-forming developers, the use of hydroxy1amines together with alkanolamines has taught to enhance the stability of such developing solutions, see for example GB Patent Nos. 2,060,921A and 2,075,496A and WO 81/02797. Present developers, however, do not provide adequate protection from the oxidation effects of air. displayed by non-imagewise hardening. Also, known developers have a narrow temperature latitude in which they function, i.e., either only at high temperatures or low temperatures. Low temperature developers are generally slow, requiring extended residence time: in the developing solution, thereby increasing susceptibility to oxidation from the air. High temperature developers accellerate image development and the effects of oxidation. The oxidation manifests itself as non-imagewise hardening, which affects final image quality, e.g., half-dot retention is very narrow because the 90 percent dots are clogged and the 5 percent dots too large. I have now discovered a tanning . developer solution capable of eliminating the above-mentioned problems of air oxidation which unexpectedly allows image processing at a wider latitude of temperatures, especially at room as well as at elevated temperatures, a concept not heretofore available. Summary of the Invention In accordance with my invention, the tanning developing solution thereof comprises an alkaline aqueous solution containing hydroxylamine derivatives, preferably together with water miscible polyhydroxy aliphatic organic solvents, which allows for the elimination of non-imagewise tanning of the gelatin. If desired, the developing solution may also contain one or more silver image developing agents, preferably a polyhydroxy benzene derivative with at least two hydroxy groups together with one or more electron withdrawing groups and good leaving groups for nucleophilic addition. Such compounds are usually poor silver image developing agents and are active gelatin cross linkers, but in superadditivity with more active silver image developing agents, as hereafter discussed, the combination thereof allows a more facile imagewise development and tanning at a significantly wider temperature range without attendant background non-image¬ wise tanning. Detailed Description The aqueous tanning developer solution of my invention can be typically rendered alkaline to a pH range of from about 8 to about 12 utilizing conventional alkyl metal salts, e.g., carbonates, bicarbonates, hydroxides, etc., or by using organic bases, e.g., amines, alkanolamines, etc., and contains derivatives of hydroxylamines as stabilizers against non-imagewise gelatin hardening. Hydroxylamine derivatives suitable for the invention have the following general structure: R- ^ -R- j -N-O-R- j .HX wherein R,, R_ and R-. represent hydrogen; alkyl, e.g., methyl, ethyl, propyl, isopropyl, octyl, decyl, dodecyl, etc. including substituted alkyl, e.g., alkyl substituted by aryl, e.g., phenyl; hydroxy1; carboxyl; sulfo; amino; substituted amino; NHOH; substituted aryl, e.g., aryl substituted by halogen; alkyl, alkoxyl," hydroxy, carboxyl, sulfo, alkoxy carbonyl and substituted amino; carbonyl and substituted carbonyl; amino and substituted amino; or a heterocyclic ring and its derivatives. X can typically be a counter anion such as a sulfate, phosphate, carbonate, oxalate, acetate, triflate, tosylate, .halide and the like. The following table lists illustrative representatives. Table 1 Derivatives of Hydroxylamine Compound No. *1 *2 -3 1 H H H 2 CH 3 CH 2 H 3 CH 3 H CH 3 4 PhCH 2 PhCH 2 H 5 NH 2 C0 H H 6 CH 3 C0 H H 7 HCO H H 8 PhCO H H Other hydroxylamine derivatives which are useful herein are described in U.S. Patent Nos. 3,287,125; 3,287,124; 4,055,426; and Beilstein Organische Chemie, 4th ed., Vol. 2, page 90; Vol. 2, page 187; Vol. 9, page 31? Vol. 10, page 98; Vol. 3, page 95; Vol. 4, page 70; Vol. 12, page 376; and Vol. 4, page 218. Examples of other suitable hydroxylamine derivatives include N-alpha-sulfopropylhyroxylamine, N-alpha-carboxypropylhydroxylamine; alpha-hydroxyl- amine-beta-phenylpropionic acid, N-m-sulphophenyl- hydroxylamine. The hydroxylamine derivatives should be contained in concentrations of between 0.001 to about 10.0 grams per liter of developing solution, and preferably in amounts between about 0.01 to about 5.0 grams per liter of solution. At increasing concentrations, the image may become increasingly inhibited from satisfactory development, while decreasing concentrations reduce the desired effect on oxidation from the air. The hydroxylamine derivatives can also be included within the photographic film itself, e.g., as an oil dispersion, to reduce oxidation from the air. They can be in the silver halide layer or in reactive association therewith. The developing solution of my invention preferably also contains at least one water-miscible polyhydroxy solvent which is stable in the sense that it is not reactive with other components in the solution. Such solvents should not be excessively volatile at - temperatures at which the developing solutions are used during processing.' They should be present in an amount from between about 5 to about 700 grams per liter of solution, and preferably between from about 100 to about 300 grams per liter. Increasing concentrations may tend to precipitate inorganic salts in the developer or make their dissolution difficult. Reduced concentrations will not provide the desired oxidation prevention. Suitable solvents include alkanols, e.g., isopropanol, and polyhdroxy organic solvents, e.g., ethylene glycol, triethylene glycol, etc. In addition, the developing solution may also contain silver image developing agents, and if so, preferably these. are polyhydroxybenzene derivatives having at least two hydroxy groups and at least one electron withdrawing and good leaving groups for nucleophilic addition. Such groups are well known in organic chemistry, and include, for example, halides, cyans, nitro, esters, e.g., acetate, tosylates, benzoates, phenyl and substituted phenyl groups. Examples of these polyhydroxybenzene deriva¬ tives include the following: 1. 2,3-dichloro-5,6-dicyano-l,4-hydroquinone 2. 2,3,5,6-tetrachloro-l,4-hydroquinone 3. 3,4,5,6-tetrabromo-l,2-hydroquinone 4. 2,3,5,6-tetracyano-l,4-hydroquinone 5. 2,5-dichloro-3,6-dihydroxy-l,4-hydroquinone 6. 2 ,3-dichloro-l ,4-dihydroxynaphthalene 7. 2-chloro-l,4-hydroquinone These electron poor developing agents, e.g., the polyhydroxybenzene derivatives, may be present in amounts between from about 0.5 to about 15 grams per liter of developer solution, and more preferably between from about 1 to about 5 grams per liter. Such compounds are typically poor silver image developing agents and active gelatin crosslinkers, but in superadditivity with more active silver image developing agents, the combination thereof provides a more facile imagewise development and tanning at a wider temperature latitude without attendant background non-imagewise tanning from air oxidation. These more active silver image developing agents include any of those known in the literature, for example, hydroquinone, catechol, pyrogallol and their derivatives having electron rich substituents. Superadditivity effects can be still further enhanced by including a third developing agent such as phenidone, aminophenol, metol, amidol or their derivatives. The developing agents may all be incorporated within the photographic element, within the developing solution, or a part in each. Preferably, the more active silver image developing agents are incorporated within the light-sensitive photographic element while the agents containing electron withdrawing groups are contained within the developing solution. This optimizes air oxidation protection, since the more active developers are adversely affected by air to a greater extent. When utilized in the presence of other more active silver imaging developing agents, the preferred ratios, by weight, are between about 20:1 and 1:1, and preferably are about 2:1, electron poor to electron rich respectively. When a third developing agent is utilized, the preferred weight ratios are 10:1:0.1, and most preferred 2:1:0.5, electron poor to electron rich developing agents. Furthermore, the developer solution may also contain other components known to be useful as photo- graphic developers, as described in L. F. A. Mason, "Photographic Processing Chemistry", Focal Press, London, 1966. Examples therein include inorganic salts to reduce the gelatin swelling, sulfates, phosphates, borates, surfactants; development accelerators such as polyoxy- alkylene derivatives, as described in U.S. Patent No. 1,269,312; and gelatin softening agents such as urea, as described in U.S. Patent No. 2,404,774. The invention will now be more specifically described by the following non-limiting examples, wherein all parts are by weight unless otherwise specified. A tanning silver halide photographic element was first prepared for use in testing the developers of my invention by applying on a conventionally subbed polyester base the following light-sensitive layers: a) the first layer of a light-sensitive unhardened gelatin layer containing_ a silver iodo-bromide emulsion (containing 94 mole percent silver bromide) with a grain size between 0.34 and 1.6 microns. Also contained therein was a pigment dispersion consisting of 4 percent by weight gelatin, 11 percent by weight Colanyl Red FGR and 9 percent by weight Flexonil Blue AN, as a water pigment dispersion available from American Hoechst. The emulsion was chemically and optically sensitized at the coverage of 0.5 grams per square meter with a silver to gelatin ratio of 0.3 and hydroquinone and phenidone thus obtaining a gelatin/- hydroquinone/phenidone ratio of 1:0.07:0.01. b) Over this layer was applied an unhardened gelatin protective layer containing gelatin at a coverage of 1 gram per square meter and 2,5-diisooctyl hydroquinone in a dispersion with tricresylphosphate at a coverage of 0.96 grams per square meter. A reference photographic element was exposed to a sensitometric wedge (0 3 logE) for 2x10 seconds with a 1.29 N fullstop D fullstop filter, and to alphabetic letters by contact exposure in a vacuum frame of a photographic enlarger, manually developed in the developer solution, and dip washed with warm water for 30 seconds at 90 F. The developer sequence was for 30 seconds at 90°F, 2 minutes at 72°F and 5 minutes at 68°F. Each test photographic element was then exposed and developed in a similar manner to a reference sample including an additional step, that being the exposure thereof to air for 30 seconds while wet with developer solution and prior to the dip wash step. The images were then wiped clean with a wet soft tissue to remove residual pigmentation. The minimum and maximum densities of the wedge image were measured and the background non-imagewise hardening was monitored and noted relative to various developer solutions. In each of the following test solutions, the final pH thereof was adjusted to 10.1 with sodium bicarbonate. In each of the following examples, the components were added to the distilled water and mixed to provide a developer solution. Example 1 Developer- formulations were prepared to illustrate the effect of hydroxylamine derivatives therein. The test results are as follows: Developer Ref. - Test Developers Components 1 2 3 4 Distilled water 1000 ml Sodium carbonate 20 g Sodium sulfate 120 g Hydroxylamine No. 1 / 0. 1 g / / Hydroxylamine No. 2 / / i g / Hydroxylamine No. 3 / / / i g Reference photo-element (no air exposure) : Dmin 0.01 0.01 0.02 0.01 Dmax 1.25 1.25 1.20 1.20 Non-imagewise hardening None Test photo-element (with exposure to air) : Dmin 0.40 0.01 0.02 0.01 Dmax 1.25 1.25 1.20 1.20 Non-imagewise hardening Yes No No No Example 2 Developer formulations were prepared to illustrate the effect of polyhyroxy solvents contained therein. The test results are as follows: Developer Component Ref. Test Developers No. 1 5 6 Distilled water 1000 ml Sodium carbonate 20 g Sodium sulfate 120 g Ethylene glycol / 100 g / Triethylene glyc.ol / / 100 g Test photo-element (with exposure to air) : Non-imagewise hardening Yes Partial Partial Example 3 Developer formulations were prepared to illustrate the joint effect of hydroxylamine derivatives and polyhydroxy solvents contained therein. The results of such tests were as follows: Ref. Test Developers Developer Components No. 1 7 8 9 10 Distilled water 1000 ml Sodium carbonate 20 g Sodium sulfate 120 g Hydroxylamine No. 2 / 0.5 / / / Hydroxylamine No. 3 / / 1.5 / / Hydroxylamine No. 5 / / / 1.0 / Hydroxylamine No. 8 / / / / 1.0 Ethylene glycol / 100 c 3 Test photo-element (with exposure to air ) : Non-imagewise hardening Yes No No No No Example 4 Developer formulations were prepared utilizing hydroxylamine derivatives together with other components. Results thereof are as follows: Developer Component No. 1 11 12 13 14 Distilled water 1000 ml 800 800 800 800 Sodium carbonate 20 g Sodium sulfate 120 g 120 180 240 120 Hydroxylamine No. 2 / 2.0 EDTA / / / / 2.0 Ethylene glycol / 200 ml Test photo element (with exposure to air): Non-imagewise hardening Yes None None Partial None Example 5 Developer formulations were prepared utilizing hydroxylamine derivatives in conjunction with other photographic developing agents. The results thereof are as follows: Ref. Test Developers No. 15 16 17 Distilled water 1000 ml 800 700 Sodium carbonate 20 g Sodium sulfate 120 g Hydroxylamine No. 5 / 0.5 0.5 Tetrachloro-1,4-hydroquinone 3 g 3 g 3 g Phenidone / / 0.5 g Ethylene glycol \ / 200 300 Test photographic element (with exposure to air): Non-imagewise hardening Yes No No Example 6 Developer solutions were prepared for testing with the photographic tanning element noted above which illustrates the suitability of my invention for processing over a wide temperature range. The general formula for the developer solution is as follows: General Formula Amount Distilled water (1000-Z)i ml Sodium carbonate 20 g - Sodium sulfate 120 g Hydroxylamine No. 5 X g Developing agent y g Ethylene glycol z g The test photographic element was exposed to air as discussed above and processed at two separate temperatures. Imagewise and non-imagewise tanning was then observed. The results are as follows: Results 5 min. (68°F) 30 sec. (95°F) Hydroxyl¬ Non- Non- amine Glycol Dev. . Agent No. Imagewise imagewise Imagewise imagewise (x g) (z ml) (y g) 0.0 0.0 0.0 None Yes Yes Yes 0.0 0.0 2 (2 g) Yes Partial Yes Partial 0.0 0.0 3 (2 g) yes Partial Yes Partial 0.0 0.0 7 (2 g) Yes Partial Yes Partial 0.0 0.0 Hydroquinone (2 g) Yes Yes Yes Yes 0.5 200 2 (3 g) . Yes None Yes None 0.5 200 3 (3 g) Yes None Yes None 0.5 200 7 (3 g) Yes None Yes None 0.5 0.0 2 (3 g) Yes Partial Yes Partial 0.0 200 g 2 (3 g) Yes Partial Yes Partial

Claims: WHAT IS CLAIMED IS: 1. A tanning developer composition comprising an aqueous alkaline solution containing therein at least one hydroxylamine derivative. 2. The developer composition of claim 1 wherein said solution additionally includes at least one polyhydroxy water-miscible solvent. 3. The developer composition of claim 1 further comprising an agent capable 'of developing photographic images in an exposed silver halide emulsion. 4. The developer solution of claim 3 wherein said agent comprises a polyhydroxybenzene compound having at least two hydroxy groups and at least one electron withdrawing group, and at least one good leaving group for nucleophilic .addition. 5. A photographic element comprising a substrate having a silver halide layer thereon, the improvement being that said layer contains at least one hydroxylamine derivative therein.

Inventors: SABONGI GEBRAN J, SABONGI, GEBRAN, J.
Applicants: MINNESOTA MINING & MFG, MINNESOTA MINING AND MANUFACTURING COMPANY
Application year: 1985
Main classification: G03C1
IPC codes: G03C1, G03C5