US2525532A - Simultaneously developing and fixing photographic images - Google Patents

Description

Patented Oct. 10, 1950 SIMULTANEOUSLY DEVELOPING AND FDiING PHOTOGRAPHIC IMAGES .9 Roman P. Dreywood, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application October 18, 1946, Serial No. 704,305

4 Claims.

This invention relates to the simultaneous development and fixing of photographic images.

There have been numerous suggestions for the simultaneous development and fixing of exposed photographic emulsions. These have involved a combination of the usual development and fixing steps followed by washing and drying in the customary manner. My invention permits simultaneous development and fixing of photographic images without the necessity for a long water wash and therefore permits rapid processing of the exposed emulsion.

In Yackel U. S. application, Ser, No. 594,589, filed May 18, 1945, now abandoned, a rapid processing method is described in which an exposed silver halide emulsion is developed in the usual way and then treated with a stabilizing agent such as potassium thiocy-anate, ammonium thiosulfate, thiourea, etc., followed immediately by drying. This method involves separate developing and stabilizing baths whereas the present method permits the use of a single bath.

The compounds which I use in the developing solution to permit a stabilizing or fixing action [are certain mercapto pyridines and mercapto pyrimidines. The following compounds are useful for this purpose according to my invention.

B-amino 4-hydroxy-2- 4-amino-6-hydroxy-2- 4-amino-6-hydroxy-2- I mercaptopyrimidme mercaptopyridme metcaptopyrimidine The following formula is suitable for use as a combined developing and fixing bath accord- Water to 500 cc.

The exposed photographic emulsion is immersed in this solution for 90 seconds after which it is washed in a acetic acid solution stop bath for seconds, the excess liquid is removed from the surface of the print by squeegeeing or in other suitable manner and the print is dried.

.It will be apparent that my method may be used for processing either positive emulsions such as are used on photographic paper or negative film emulsions. Positive emulsions such as used on photographic papers are generally hardened and no further hardening treatment is required. However, in the case of certain negative film emulsions, the emulsion must be hardened before processing according to my invention. This can be done with a formaldehyde hardening bath before or during development or in any other suitable Way.

It will be apparent from the foregoing description of my invention that all or a major part of the silver remains in the emulsion after my processing treatment. This diifers from the customary combined developing and fixing processes in which the residual silver halide is removed from the emulsion.

I claim:

1. A process for simultaneously developing and fixing photographic images which comprises exposing a silver halide emulsion layer, treating said exposed layer in a solution containing a silver halide developing agent and a mercapto compound selected from the group consisting of 4 amino 6 hydroxy 2 mercaptopyridine, 4 amino 6 hydroxy 2 mercaptopyrimidine and 6 amino 4 hydroxy 2 mercaptopyrimidine, stopping the developing action with a dilute acid solution and drying the developed emulsion without further washing.

2. A process for simultaneously developing and fixing photographic images which comprises exposing a silver halide emulsion layer, treating said exposed layer in a solution containing a silver halide developing agent and 4-amino-6- hydroxy-2-meroapto pyridine, stopping the developing action with a dilute acid solution and drying the developed emulsion without further washing.

3. A process for simultaneously developing and fixing photographic images which comprises exposing a silver halide emulsion layer, treating said exposed layer in a solution containing a silver halide developing agent and G-aminolhydroxy-Z-mercapto pyrimidine, stopping the developing action with a dilute acid solution and drying the developed emulsion without further washing.

4. A process for simultaneously developing and fixing photographic images which comprises exposing a silver halide emulsion layer, treating said exposed layer in a solution containing a silver halide developing agent and 4-amino-6- hydroxy-2-mercapto pyrimidine, stopping the developing action with a dilute acid Solution and drying the developed emulsion without further washing.

ROMAN P. DREYWOOD.

REFERENCES CITED The following references are of record in the 10 file of this patent:

UNITED STATES PATENTS Number Name Date 2,230,976 Ham Feb. 4, 1941 2,304,962 Sheppard Dec. 15, 1942 4 Number Name Date 2,384,897 Dersch Sept. 18, 1945 2,453,346 Russell Nov. 9, 1948 OTHER REFERENCES Piper: More About Fixing, Brit. Journ. of Phot., v01. 61, pages 458 and 159 cited. (Copy in S. L.)

I-Ienney and Dudley: Handbook of Photography, McGraw-Hill Book Company Inc., 1939, page 378 cited. (Copy in Div. 7.)

Beilstein: Handbuch der Organischen Chemie, 4th edition, 1936, volume 2%, page 476 cited. (Copy in Div. 6.)