US2625477A - Bleaching silver images with p-sulfophenyl quinones or p-nitroso phenols - Google Patents

Description

Patented Jan. 13, 1953 BLEACHING SILVER IMAGES WITH p-SULFO- PHENYL QUINONES OR p-NITROSO PI- IE- NOLS George W. Sawdey, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application November 1, 1951, Serial No. 254,440

8 Claims. 1

This application relates to color photography and particularly to the removal of silver images in color photography.

In photographic color processes, such as those in which a colored image is formed bydevelopment with a primary aromatic amino developing agent in the presence of a coupler compound, the silver images formed in the development are generally present in the emulsion layer after the dye images are formed. These silver images are generally removed by converting them to a silver salt which is soluble or which is removed by hypo.-' A bath of this type containing potassium ferricyanide and potassium bromide is disclosed in Mannes, Godowsky, and Wilder U. S. Patent 2,252,718, granted August 19, 1941. A similar bath containing 50 grams of potassium ferricyanide and 20 grams of sodium chloride per liter of water to which has been added 1 to 5 grams of potassium chromate or potassium dichromate to retard the corrosive action of the bath on iron and iron alloys, has also been used.

The ferricyanide and halide bleach baths are not entirely satisfactory in that certain optical sensitizing dyes in the emulsion layer are not destroyed by them and these may cause stain in the emulsion layer. A further disadvantage is that any ferricyanide remaining in the element may be converted to iron oxide and produce a brown stain and there is also the objectionable corrosive action on stainless steel or iron alloys unless a chromate or dichromate is used in the bath.

A bleach bath containing quinone, acid and an organic solvent has also been used to convert silver images to silver salt in the presence of a developed dye image. A bath of this type is disclosed in Mannes and Godowsky U. S. Patent 2,113,329, page 2, column 2, lines 16 to 21. This bath cannot be used in the final stages of a color process because it destroys the dyes as Well as converts the silver to a silver salt.

In addition to the bleaching agents described above, sodium quinone sulfonate has been sugested as a reducer for silver by Lumiere and Seyewetz (British Journal of Photography, 1910, 57 page 625). However, acid solutions of sodium quinone sulfonate lose their bleaching activity rapidly and after about six hours are for all practical purposes useless as bleaches.

It is, therefore, an object of the present invention to provide novel bleaching agents for bleaching silver images in the presence of color-developed dye images in a photographic emulsion layer. A further object is to provide a novel halogen substituents such as chlorine, bromine or iodine; alkoxy substituents such as methoxy, ethoxy and propoxy; acetamido groups, etc.

P-sulfophenylquinone ture:

p-Nitrosophenol is commonly regarded as existing in acid solution as the monoxime of benzoquinone according to the scheme The bleaching agents of my invention are'usedin strong acid solution, that is, in a solution of pH from about 1 to about 3.5.

The bleach baths employed according to my invention may be used in any process in.which silver images are present in a photographic layer together with dye images. The dye images may be those formed by color development as described in Mannes, Godowsky, and Wilder U. S. Patent 2,252,718; Mannes and Godowsky U. S. Patents 2,113,329 and 2,304,940; or Jelley and Vittum U. S. Patent 2,322,027. These dyes are of the azomethine, indoaniline or indophenol type. The dyes may also be azo dyes such as those used in the silver dye bleach process of color photography. After all of the steps of color processing, the photographic layer or element is treated with the bleach bath of my invention followed by hypo to remove the silver salts formed by the bleach bath.

The emulsion layers containing the silver and dye images treated according to my invention may be coated on supports of glass or of cellulose ester, synthetic resin, paper or other suitable material.

has the following struc- The following examples illustrate baths which may be used according to my invention.

Water to 500 cc.

The pH of this solution isiapproximately lfii which I have found to be optimal fo'rthe use-:01

p-sulfophenylquinone, particularly when it is used with emulsions coated onpaper.

Example :2 Grams-v Cupric chloride 10..

p-Sulfophenylquinone Potassium bromide 5 Sodium bisulfate Water to 500 cc.

Both'fof these "bleachibaths eflectfcomplete con version 70f. silver to silver saltin'acolorrpaper or film in approximately. 10 minutes-.5

Example 3 Grams 1 p Nitrosophenol sodium-salt. 4 Potassium1 bromide- Sodiumhisulfate 15 Tlie-pI-I ofthissolution-isapproximately 1.0. In the majority of-multii-layer color materials, com--- plete' *silverbleaching-is accomplished in- 5 to 10 minutes? The l: le'ach bath's of 'my--inventi'on- 'havemany The bleach bath may be fo"r--- or ,violently. and therefore good...control. of, the

bleaching actionmay be.obtained,lparticularly at the start of bleaching.

It will Y be understood that the examples included herein are illustrative only and that my inventionis to .be taken as limitedonly by thescope of.theappendednlaims...

I claim:

1..- The. method of v removing, only the silver imagesfrom aphotographic :layer containing. sil.

ver and dye images. which comprises. treating said layer containing said; silver and dye images with.

an acid solution of a bleaching agent selected from the class consisting of p-sulfophenylquinone and benzoquinone monoxime and their derivatives substituted in the aromatic ring with a group selectedirom.the.,class consisting .of. alkyl, halogen, alkloxy and acetamido -groups,- followed by fixing.

2. The method of removing only the silver images from a photographic layer containing sil- .vervand color-developed dye images which oomprises treating'said layer containing said silver and dye images with an acid solution of p-sulfophenylquinone; followed by fixing.

3..The. .'method. ,.of removing only the silver images fromza photographic layer containing silver and color-developed dye images which comprisestreating said layer containing said silver and'dye images with an acid solution of hemequinonexmonoxime, followed by fixing.

4. The method of removing only the silver images .froma photographic layer containingsilverand color=developeddye images which com.-v prises treating said layer containing said silver and dye images with an acid solution of p-sulfophenylquinone, potassium bromide and sodium bis'ulfate,.followed by fixing.

5; The method of removing only the silver images from a photographic layer containing sil-. ver andcolor-developed dye images which comprises treating said layer containing said silver.

and dye images with an ,acid solution of p nitrosophenol sodium salt, potassium bromide andso? dium bisulfate, followed by fixing.

SJ'AI bleach bath for conversion to silver salt of only. the. silver images in a photographic layercontaining both silver. anddye images, comprising.

an acid solution of potassium-bromide, sodium bisulfate;and.a bleaching. agent selected from..the class consisting. of p'-sulfophenylquinone, .benz0'-" quinone monoxime and their derivatives substituted inthe aromatic. ring with a group selected from the class consisting of alkyl; halogen, alkoxy and acetamido groups.

7. A'ble'ach' bath-"for conversion to silversalt of only the silver images in a photographic layercontaining both silver and dye images; comprising an acid solution-of potassium bromide, sodium;

bisulfate; and p -sulfophenylquinone.

8. A bleach bathfor conversion to silver salt of only the-silver images in a photographic layer containing both silver and dye images; comprising anacid solution of potassium bromide, sodium bisulfate, and benzoquinonemonoxime sodium salt.

GEORGE W. SAWDEYi No:references;cited.1

Claims (1)

1. THE METHOD OF REMOVING ONLY THE SILVER IMAGES FROM A PHOTOGRAPHIC LAYER CONTAINING SILVER AND DYE IMAGES, WHICH COMPRISES TREATING SAID LAYER CONTAINING SAID SILVER AND DYE IMAGES WITH AN ACID SOLUTION OF A BLEACHING AGENT SELECTED FROM THE CLASS CONSISTING OF P-SULFOPHENYLQUINONE AND BENZOQUINONE MONOXIME AND THEIR DERIVATIVES SUBSTITUTED IN THE AROMATIC RING WITH A GROUP SELECTED FROM THE CLASS CONSISTING OF ALKYL, HALOGEN, ALKOXY AND ACETAMIDO GROUPS, FOLLOWED BY FIXING.