N,N Disubstituted p-phenylenediamine phosphates to form a color developer working solution, a color developer concentrate containing such a phosphate and a method of using said working solution for color development of color film

An N,N, disubstituted p-phenylenediamine salt of a phosphoric acid selected from the group consisting of ortho-phosphoric acid, pyrophosphoric acid and polyphosphoric acid. Such a phosphate is incorporated as a color developing agent in a liquid packaged developer concentrate which subsequently is mixed with other materials contained in a multi-package receptacle and the mixture is diluted with water to form a color developer working solution (bath) for developing a colored film. The developer concentrate has the advantage that the color developing agent therein does not tend to deteriorate upon standing, as do present-day widely used commercial N,N, disubstituted p-phenylenediamine color developing agents in developer liquid concentrates, e.g. 4-amino-N-ethyl, N-beta methanesulfonamidoethyul-m-toluidene sesqui-sulfate monohydrate and 4-amino-N-ethyl, N-beta methanesulfonamidoethyl-m-toluidene hydrochloride; nor do the new phosphate color developing agents require the presence in the developer liquid concentrate of an anti-oxidant such as a sulfite or ascorbic acid, as do the present-day commercial color developing agents, although the presence of such anti-oxidants with the new color developing agents is not harmful and, indeed, is of some slight assistance. The new color developer liquid concentrate may contain conventional photographic adjuvants and is characterized by its ability to incorporate large percentages of the color developing agent without rendering the concentrate physically unmanageable for packaging and admixture with other materials to form a working color developer solution whereby the volume and weight of a kit employing such a concentrate is reduced thereby lowering production, storage and shipping costs. The new color developing agent, because of the minimal deterioration upon standing, provides true color values upon developing, which values are as good as those obtainable with freshly prepared presently used color developing agents that are not of the phosphate type. The invention also embraces the use of the new color developing agent for color developing of colored film.