US3523794A - Developers containing silver halide solvents - Google Patents

Description

United States Patent 3,523,794 DEVELOPERS CONTAINING SILVER HALIDE SOLVENTS Vincent J. Miceli, Conklin, N.Y., assignor to GAF Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed July 3, 1967, Ser. No. 650,631

Int. Cl. G03c 5/30, 5/50, 7/00 U.S. Cl. 596-59 2 Claims ABSTRACT OF THE DISCLOSURE First developers for reversal process color development containing high concentration of an alkali metal bromide.

This invention relates to photographic developers and particularly to an improved first developer for reversal color processing.

It is known that sulfites are usually added to photographic developing solutions for the purpose of preventing oxidation of the developing agent. In addition it has been observed that the sulfites also have a slight solvent effect on the silver halides and as the development progresses they actually dissolve a small quantity of each silver halide grain thereby minimizing the tendency for clump formation which would increase graininess. This solvent action has been recognized as essential in reversal processes for acceleration of development and the like. In fact, it has been found that a silver halide solvent, in addition to sulfites is necessary otherwise the development will be so slow that the reversal highlights are not cleaned out and are heavy or dense in the final image.

With the advent of the use of silver halide solvents many problems arose as to the properties of said solvents in satisfying the requirements in negative developers. To be suitable for use the solvent should accomplish the primary purpose of cleaning out the reversal highlights without disolving the unexposed silver halide and without the development of fog in the unexposed area of the film. This means that in the ordinary negative development the silver halide should be completely reduced in the fully exposed areas and the silver halide solvent helps to accomplish this purpose. These solvents should not produce an unusually great amount of latent image growth, that is, they should not develop silver halide to any great extent in the regions surrounding the exposed portions.

Still another characteristic which a silver halide solvent should possess is its ability to promote resolving power and definition and in a color process it should improve the color saturation and brightness of the final image.

Still other eifects which the silver halide solvent should produce are an increase in penetration of the developing agent which is important in the development of multilayer materials, a reduction in grain size, an improvement in resolution at the edges of the image and an increase in the effective reversal speed of the material.

Thus it is an object of the invention to provide a novel silver halide solvent for photographic developers.

Another object of the invention is the provision of a novel silver halide solvent which eifectively restrain fog formation without loss of development speed.

A still further object of this invention is the provision of a novel first developing solution suitable for use in reversal color processing and which provides an increase in effective reversal speed of the material.

I have discovered that these and other objects of the invention can be readily accomplished by incorporating into photographic developing solutions high concentrations of an alkali metal bromide. 1

While the mechanism of acceleration is not completely understood it is believed that such large amounts of alkali metal bromide in the developing solution increase the solubility of silver halide in the developing solution and thus promotes the physical development of the halide. It also reduces the quantity of silver halide remaining to be developed and consequently increases the effective reversal speed of the material. This acceleration is accomplish without excessive fog formation which is accompanied with the use of most silver halide solvents.

The developing solution which has been found effective for use in reversal color processing is as follows:

Ethylenediamine tetra-acetic acid grams 0-2.0 Alkali metal sulfite do 5-100 Metol do 1-5 Hydroquinone do 2-10 Alkali metal bromide do 10-50 Alkali metal carbonate do 10100 Alkali metal iodide milligrams 0-50 Water to make 1.0 liter.

Thus, it may be observed that the amount of sodium bromide employed in the developing solution of the invention is many times the amount of sodium bromide normally employed in conventional developers for reversal color processes.

The following example will serve to illustrate the practice of the invention:

EXAMPLE A reversal color film commercially available under the name GAF Anscochrome film was used for this example. This multilayer color reversal film containing formers is prepared according to the methods described in U.S. Pats. 2,179,228, 2,179,239, 2,186,849 and 2,220,187, and consists of an integral tripack emulsion coated on the usual clear cellulose acetate or nitrate film base. Each of the emulsions is sensitized to one of the primary colors of light namely, blue, green, and red. The top layer is blue sensitive. A filter layer, yellow in color and blue absorbing, lies under the top layer. Below this filter lies a green sensitive emulsion layer and below this is a red sensitive emulsion layer. Each of the three silver halide ernu1- sion layers contains dye forming compounds which unite during the development of the silver image in an aromatic amino developing agent to form a dye with the oxidation product of the developing agent. The fihn was imagewise exposed and then developed for 23 minutes at 68 F. with a developer of the following compositions:

Water to make 1.0 liter.

The film was washed for five minutes, hardened in an aqueous solution containing an inorganic hardener, e.g., alum, chrome alum, washed, given a second exposure and then developed with N,N -diethyl-p-phenylenediamine color developer. This film is subsequently washed, bleached if necessary, washed and then fixed, washed and dried.

The finished transparency had excellent pictorial qualities and the image was superior to conventionally processed films by showing higher maximum densities in all layers, thus giving the impression of deeper colors including black. This improvement was made possible by reducing the amount of fog produced during the first negative development thus leaving more silver halide available in the unexposed areas available for color formation during the second, color-forming development.

Various modifications of the invention will occur to persons skilled in the art therefore it is not intended that 3 the invention be limited in the patent granted except as necessitated by the appended claims.

What is claimed is:

1. In the process of developing a color film of the reversal type which includes the steps of imagewise exposing a film, developing it with a first developing bath for silver halide, re-exposing to light, color developing the same, the improvement comprising employing as the first developing bath an aqueous developing solution comprising:

Ethylenediamine tetra-acetic acid grams 0-2.0

Alkali metal sulfite d0 5-100 Metol do 1-5 Hydroquinone d0 2-10 Alkali metal bromide do 10-50 Alkali metal carbonate do 10-100 Alkali metal iodide milligrams 0-50 Water to make 1.0 liter.

2. A photographic developer solution according to claim 1 which comprises:

4 Ethylenediamine tetra-acetic acid grams 0.8 Sodium sulfite do 20.0 Metol do 3.0 Hydroquinone do 6.0 Sodium bromide do 20.0 Sodium carbonate do 45.0 Potassium iodide milligrams 5.0 Water to make 1.0 liter.

References Cited UNITED STATES PATENTS 2,979,406 4/ 1961 Taylor et a1 9666 NORMAN G. TORCHIN, Primary Examiner E. C. KIMLIN, Assistant Examiner US. Cl. X. R. 9650, 55, 66

Disclaimer 3,523,794.Vincent J. Miceli, Conklin, N.Y. DEVELOPERS CONTAINING SILVER HALIDE SOLVENTS. Patent dated Aug. 11, 1970. Disclaimer filed Sept. 30, 1982, by the assignee, Eastman Kodak Co.

Hereby enters this disclaimer to all claims of said patent. [Official Gazette October 4, 1983.]