US 3721563 A
Description (OCR text may contain errors)
United States Patent 1191 Fisch et al.
[ ]March 20, 1973 PHOTOGRAPHIC DEVELOPER CONCENTRATE  Inventors: Richard S. Fisch; Norman Newman;
Joel L. Bexell, all of St. Paul, Minn.
 Assignee: Minnesota Mining and Manufacturing Co., St. Paul, Minn.
 Filed: Sept. 24, 1971  Appl.No.: 183,674
 US. Cl. ..96/66.l, 96/55, 96/56,
96/66, 96/66.4 [51 Int. Cl ..G03c 5/30, G03c 7/00  Field of Search ..96/66, 66.1, 66.4, 55, 56
 References Cited UNITED STATES PATENTS Vittum ..96/56' James, Kinetics of Development by p-Phenylenediamine in Neutral and Moderately Alkaline Solns, Journal of Photography, Vol. 6, 1958, pp. 49-57.
Primary Examiner-J. Travis Brown Assistant Examiner-Mary F. Kelley Att0rneyKinney, Alexander, Sell, Steldt & Delahunt [5 7] ABSTRACT A phase-stable acidic photographic color developing solution which includes, in aqueous solution, a pphenylenediamine developing agent andascorbic acid.
8 Claims, No Drawings- PHOTOGRAPHIC DEVELOPER CONCENTRATE This invention relates to photographic color developer concentrate kits, and more particularly to an acidic photographic color developer concentrate useful as an element in such kits.
Chemicals which are utilized to develop exposed silver halide materials are generally sold in the trade in concentrated form so that, by simple dilution with water, the ultimate user may obtain a photographic color developer working solution.
To avoid the tendency of certain ingredients of photographic developer concentrates to react with one another, it is often desirable to provide various of these ingredients in separate packages. For example, a concentrated acidic aqueous solution of a photographic developing agent may be placed in one package of a kit, and a concentrated aqueous alkaline solution may be included in a second package thereof. The photographic color developer working solution may then be prepared simply by combining the packaged ingredients and diluting the same with water.
Kit packages which contain a concentrated developing agent further ordinarily contain fairly large quantities of sulfite (as, for example, sodium sulfite) as a stabilizer for the developing agent. Dutch Pat. application No. 6,814,905 teaches that the storage stability of an aqueous p-phenylenediamine developing agent-sulfite concentrate may be improved if the molar ratio of sulfite to the developing agent is no greater than 1.5/1.0. 0n the other hand, it is reported desirable to use sufficient sulfite in the concentrated developer solution to at least stabilize the developing agent against air oxidation (e.g., a minimum sulfite/developing agent molar ratio of about 0.05/1 to about 1.0/1.0, and preferably 0.15/1 to 0.5/1
It has been found that aqueous acidic p-phenylenediamine developing agent solution concentrates which contain a stabilizing quantity of sulfite unfortunately are not phase-stable; that is, phase separation occurs upon storage which may lead to formation of a precipitate. During preparation of the working developer solution, excessively long periods of time are required to completely dissolve the contents of the package containing the developer concentrate in the working solution. Shaking or mixing of the packaged concentrated developer merely causes the solution to become turbid. It is desirable, of course, that one be able to quickly prepare a working developer solution simply by opening the packaged chemical concentrates and diluting them with water. The necessity of physically dispersing (mixing) a precipitate during preparation of a working developer to cause dissolution of the precipitate is undesirable, since this may cause aerial oxidation of the developing agent. Moreover, the extensive mixing required to effect dissolution of a precipitate is time consuming and inconvenient, and desirably should be avoided.
It is an object of the present invention to provide an aqueous, acidic developing agent solution in concentrated form which is phase-stable upon storage.
It is another object of the invention to provide a phase-stable acidic photographic developing solution in concentrated form which can be rapidly and completely dissolved to form a photographic developer working solution, or a replenisher solution therefor.
Briefly, the invention relates to a phase-stable acidic photographic developing solution concentrate which comprises, in aqueous solution, a p-phenylenediamine developing agent and ascorbic acid in an amount sufficient to provide a mole ratio of ascorbic acid to said developing agent of from about 0.005/1 to about 0.3/1. In another embodiment, the invention relates to a method for the production of a photographic silver halide developer solution which comprises combining, in aqueous solution, an aqueous alkaline solution concentrate (e.g., another kit package which contains an alkaline ingredient such as potassium hydroxide, buffering ingredients such as borates, carbonates, etc.) and an acidic, phase-stable aqueous solution concentrate which includes a p-phenylenediamine developing agent and ascorbic acid, the mole ratio of ascorbic acid to the developing agent being from about 0.005/1 to about 0.3/1, as described above. By phase-stable is meant that no phase separation can be visually detected in the solution when viewed under normal indoor lighting conditions.
As will be understood by those skilled in the art, the
aqueous alkaline solution so described rendersthe resulting working developer solution alkaline, and so permits silver halide development to occur. As is known in the art, the color development of silver halide materials involves reduction of silver halide to silver, accompanied by concurrent oxidation of a p-phenylenediamine developing agent. The oxidation product of the developing agent then couplesff i.e., condenses, with a color coupler which may be contained within the photographic element to form a colored dye. By developer solution as used herein, reference is made to both developer solutions and replenisher solutions which are used to replenish depleted developer solutions.
Although ascorbic acid is known to be an oxidation inhibitor, it is surprising that ascorbic acid may be employed in the acidic aqueous photographic developing solution concentrates of the invention without causing phase-separation, as described above with reference to sulfite. Although those developer concentrate solutions of the invention which contain no sulfite may develop a slightly colored appearance upon storage, it has been found that this phenomena does not have a significant affect on the utility of the developer. In its preferred embodiment, the developer concentrate solutions of the present invention additionally contain a very small compatible (i.e., not causing phase-separation) quantity of a water-soluble sulfite salt to prevent the solution from becoming colored upon storage. The mole ratio of sulfite salt to p-phenylenediamine developing agent should not be greater than about 0.08 to 1, and preferably is from about 0.02 to l to about 0.065 to 1. By sulfite salt is meant compounds such as alkali metal sulfites and bisulfites; i.e., compounds which will liberate sulfite ions when dissolved in water. Sodium sulfite is preferred.
The concentration of p-phenylenediamine developing agent in the developer solution concentrate of the invention will normally fall within the range of from about 0.5 to 1.0 molesper liter, (e.g., up to the solubility limit of the developer) although greater and lesser amounts may also be employed. As mentioned, the developer solutions of the invention are acidic, and ordinarily display a pH of less than about 5. When diluted 50 fold with water, the resulting solution preferably exhibits a pH of from about 1.2 to about 4.5.
The developing agents which are especially useful in the solutions of the present invention are the p-phenylenediamine color developing agents well known in the art, especially those which form non-diffusing dyes with phenolic and reactive methylene photographic couplers. The p-phenylenediamine developing agents of the invention include p-phenylenediamine and the N,N-dialkyl-p-phenylenediamines and their salts such as the sulfate, hydrochloride etc. salts. Examples of suitable developing agents include N,N-diethyl-p-phenylenediamine monohydrochloride, 2-amino-3- diethylaminotoluene monohydrochloride, 4-amino-N- ethyl-N-(B-methanesulfonamidoethyl)-m-toluidine sesquisulfate monohydrate, 4-amino-3-methyl-N-ethyl- N-(B-hydroxyethyD-aniline sulfate, 4-amino-3-(fl methylsulfonamidoethyl)-N,N-diethylaniline hydrochloride, 4-amino-N,N-diethyl-3-(N'-methyl-flmethylsulfonamido)-aniline hydrochloride. Other useful color developing agents are disclosed in U.S. Pat. Nos. 2,552,241 and 2,566,271, and in J.A.C.S., 73, 3100-3123 (1951). Especially effective are those pphenylenediamine developing agents which contain at least one alkylsulfonamidoalkyl substituent attached to an amino nitrogen, or to a carbon atom of the phenyl ring.
The developing agent concentrates of the present invention may also contain various other additives known to the art, such as antifoggants (e.g., benzotriazole), development restrainers (e.g., bromide ion), auxiliary black and white developing agents (e.g., 3- pyrazolidone silver halide developers such as 4,4- dimethyl-B 1-phenyl-3-pyrazolidone), benzyl alcohol (as a dispersion), and the like. in one preferred embodiment, however, the developing solution concentrate of the invention includes in aqueous solution only the developing agent, sulfite, and ascorbic acid (plus a pH regulator, if desired).
The aqueous alkaline solution concentrate with which the solution concentrate of the present invention is combined and diluted with a predetermined amount of water to form a working developer solution may contain an alkaline material such as potassium hydroxide and various other components such as additional sulfite, accelerators, complexing agents and buffers (such as citric acid-citrate, boric acid-borate, carbonate, etc.).
Developer kits which include the developer solution concentrate of the present invention will normally be sold in unitary kit form, each kit containing two or more packages. The various packages will be chosen by size and shape to accommodate the various ingredients and concentrations of ingredients for each package, and will be further chosen so as to result in a total package of minimum size and weight to minimize shipping and storage costs. Accordingly, it may be desirable in some instances to place a given chemical composition (e.g., a sulfite salt) in more than one package to conservespace. a
The invention may be more easily understood by reference to the following illustrative, non-limiting example. v
A three-package developer kit was prepared, the composition of each of the packages being as follows:
Ascorbic acid A second photographic developer kit. was also prepared, packages A and B being identical to packages A and B above, but package C having the following composition Sodium sulfite Developing agent (4-arnino- N-ethyl-N-(fl-methanesulfonamidoethyl)-mtoluidine sesquisulfate) Water to about 13 cc.
The C and C packages both were stored at room temperature for about 8 months. At the end of this period, two phases had formed in package C (which contained no ascorbic acid). A very turbid solution resulted when this package was violently shaken. Package C (which contained ascorbic acid), in contrast, was clear and showed no evidence of phaseseparation. Thereafter, both of the C packages were diluted with water 1:100 by volume. The solution resulting from package C (which contained ascorbic acid) was much less highly colored than was the solution obtained from package C.
Working developer solutions were preparedfrom each of the kits described above by dissolving the contents thereof in water to a volume of 1 liter. Although the contents of package C which contained ascorbic acid were rapidly dissolved, the contents of the package C (without ascorbic acid) were dissolved much more slowly.
Two identical samples of photographic color paper containing a plurality of silver halide layers having couplers dispersed therein by the solvent dispersion technique '(see, e.g., U.S. Pat. Nos. 2,332,027 and 2,801,170) were identically exposed toa light image. One of the papers was developed in the developer solution resulting from use of the developer concentrateof the present invention (employing package C), and the other paper was developed in the other solutionJNo sensitometric differences were noted after development.
What is claimed is: v
1. A phase-stable acidic photographic developing solution concentrate comprising, in aqueous solution, a p-phenylenediamine developing agent, and ascorbic acid in an amount sufficient to provide'a mole ratio of l ascorbic acid to said developing agent of from 0005-03 to l.
2. The concentrate of claim 1 which additionally includes a compatible quantity of a water-soluble sulfite salt.
3. The concentrate of claim 2 wherein the molar ratio of said sulfite salt to said developing agent is not greater than 0.08 to 1.
4. The concentrate of claim 1 wherein said developing agent is a N,N-dialkyl p-phenylenediamine silver halide de-veloping agent.
5. The concentrate of claim 4 wherein said developing agent is 4-amino-N-ethyl-N-(B-methanesulfonamidoethyl)-mtoluidine, or a salt thereof.
6. An acidic aqueous solution concentrate having a pH of not greater than 5.0 and comprising a p-phenylenediamine developing agent, a water-soluble sulfite salt, and ascorbic acid, the molar ratio of sulfite to developing agent being not greater than 0.08 to l and the molar ratio of ascorbic acid to developing agent being from 0.0050.3 to l.
7. The concentrate of claim 6 wherein sald develop-