US2322001A - Method of producing dye images - Google Patents

Description

I Patented June 15, 1943 3 2,322,001 ore or raooocnso DYE IMAGES George Ehreniried, Rochester, N. Y, assignor to Eastman Kodak Company, Rochester, N. Y., a

corporation of New Jersey No Drawing. Application October lo, 194.

Serial No. 369,622

6 Claims.

This invention relates to a method for producing colored photographic images and particularly to a method of forming colored images in image in which a dyed gelatin layer containing a silver image is treated with a solution of a strong reducing agent such as sodium hydrosulilte or stannous chloride. The reducing bleach bath destroys the dye in the layer selectively in the region of the silver image, giving'a positive dye image from a. negative silver image. The destruction of a dye to form a photographic image in this process appears to depend upon the catalytic action of the silver image which results in the destruction of thedye in that portion of the film when treated with a suitable reducing bleach bath.

I; have found that in many cases the imageiorming dyes used in thisprocess may be more (Ci. sis-s) Chechak 'U. S. patent application Serial No.

readily bleached if a silver salt image is used ln' 7 place of a metallic silver image and the bleaching bath is allowed to reduce this silver salt to metallic silver in the same operation as the destruction of the dye. The silver salt image may be produced, for example, by rehalogenizing a developed and fixed'silver image. I

It is, therefore, an objeetto provide a novel method of forming a colored photographic image in a photographic layer. A-iurther object is to provide a novel method for destroying a dye uniformly dispersed in a photographic layer under the influence of a silver salt image.

These objects are preferably accomplished according to my invention by developing the emuls'ion layer containing the uniformly dispersed.

image-forming dye, fixing, washin and than rehalogenizing the silver image thus formed and treating the layer with a suitable reducing bleach bath. I

The photographic element treated according to my invention may comprise a single emulsion of poly-azo dyes as disclosed in Christensen U. S.

; Patent 1,517,049, though not necessarily the same dyes.

If a three-layer photographic element is used for the production of natural color images, the three emulsion layers preferably contain dyes coupling with 2 mols of R-salt.

each of which is'r'oughly complementary in color to the effective sensitivity of the emulsion layer. The red sensitive layer may be colored blue-green with one of the following dyes.

Eaample 1.Pontamine Fast Green 581. (Du Pont) Example 2.--A blue dye of less suitable color, bfit of satisfactory bleaching properties, made by tetrazotizing 4,4"-diamino-2,2'-dimethyl, 5,5'-dimethoxy triphenylmethane and coupling it with two mols of chromotropic acid.

Example 3.--Indigo.

The green-sensitive magenta with one of the following dyes, some of which are described in Seymour, Young, and

333,808, iiled May 7, 1940.

Example 4.-Monosol Carmine LS (Color Index Example 5.-A dye made by tetrazotizing 4,4 diamino-Zi,3'-dimethoxy diphenyl methane and Example 6.The dye made by tetrazotizing 1 mol of 4,4'-diamino triphenyl methane and coupling with 2 mols of N-lauroyl H-acid.

Example 7.-The dyes made by tetrazotizing 1 1 mol of 4,4'-diamino-3,3', 6,6'.-tetramethyl triphenyl methane and coupling-with 2 mols of N-he'ptoyl H-acicl or one of the following compounds:

Example 8.-N-lauroyl H-acid. Example 9.--N-henzoyl H mid. Example, 1il.--l-naphthol-3fi-disullonicacida-p-naphthalene sulfonate.

Example Z1.--N(naphthalene B sulfonyl) H- acid.

Eroingrle l2.-hl(-henzamido henzoyl) H-acid.

Example 23.--Ciu'omotropio acid.

Example 1%.Thfi dye made by tetrazotlzing 4,4'-diam.ino 2,2-dimetl1yl-5,5-dimethoxy trl= phenylmethane and coupling with .2 mols of 1-naphthol-8-para-tolyl sulionatedfi-disulionlc acid.

Example i5.---'lhe dye made by tetrazotizlng U. S. patent anplications 333,8t6 and 33$,hil7, tiled May r, was.

Example i l-The dye made by tetrazotizing Pool-amine l'liaao Yellow 2G1 and coupling with layer may be colored Example 19.--The dye made by tetrazotizing 4A-cliamino3,3-dimethyl-d' -"nethoxy triphenylmethane-3"-sulfonic acid and coupling with 2 mols of haphthionic acid.

Example 20.--The dye made by diaaotizing 2- naphthyla1nine-4, li-disulfonlc acid, coupling with meta-toluidine and treating the product with phosgene.

Example 21 .The dye made by tetrazotizing benzicline and coupling with 2 mols of phenol p-sulfonlc acid.

Example 22.-The dye made by tetrazotizing d,e'-diarnino stilbene disulionic acid, coupling with 2 mols of phenol and forming the di-npropyl ether of the product.

Example 23.--The dye made by tetrazotizing e-,ddiarnino stilbene disulfonic acid, coupling with 2 mole of phenol and forming the dibutyl ether of the product.

Example 2.-The dye made by tetrazotizing i,'diamino stilbene .disulfonic acid, coupling with 2 mole of 2,6-dimethyl phenol and forming the di-n-propyl ether of the product.

The layers need not be colored complementary to their sensitivity, however, but may be colored alternatively with a dye that transmits the color for which the layer is mainly sensitive.

This film is exposed in a camera or under a suitable color positive or negative. For example, it may be exposed to a natural color transparency by a single exposure to tungsten light through suitable correcting filters or by three simultaneous or successive exposures to light transmitted by red, green and blue filters in a suitable ratio of times or intensities. It is then developed in an ordinary black and white developer, washed,

and fixed. The silver image is then reconverted to a sliver halide such as silver chloride and the dyes are bleached by treatment in a sodium stannite or sodium hydrosulfite bleach bath. This reduces the silver halide image to metallic silver, and during the same operation, destroys the dye in the region of the silver image so formed. The film is then again washed and the silver image is reconverted to silver halide in the same solution previously used for this purpose or in any other suitable bath. The film is then fixed in hypo to remove the silver halide and is washed and dried leaving pure dye images in the layers,

A specific method of treating a three-layer photographic element according to my invention will now be described.

A multi-layer element having coated on a suitable support a red-sensitive layer containing Pontamine Fast Green BBL, a green sensitive layer containing the dye made by tetrazotizin 4.4 diamino 2,2,5,5' tetramethyl triphenyl methane and coupling with 2 moles of N-heptoyl "H-acid and a blue-sensitive layer containing the dipropyl ether of Brilliant Yellow (Color Index No. 364) is exposed to a natural color transparency by a single exposure to tungsten light through suitable correcting filters. The element is then developed for about eight minutes at 68 F in a tank of the following developer:

lvionomethyl-p-aminophenol The print is now placed for two minutes in a stop bath consisting of: acetic acid, 28%, 505 cc; water, '4 liters.

The film is then thoroughly fixed in acid hypo of the following composition:

Water (about 125 F.) c.c.. 50D Hypo "grams" 2'40 Sodium sulr'ite ...do 15 Acetic acid (28%) c.c 48 Boric acid crystals grams 7.5 Potassium alum ..do 15 Water to "liter-.. 1

The element is again washed and may then be hardened in a 1 to 20 formalin solution, although this hardening step may be omitted if the emulsions have been suitably hardened before coatmg.

The silver images produced by the development are bleached to silver chloride by treatment for about ten minutes in the following solution:

Cupric chloride grams- Hydrochloric acid concentrated c.c 25 Water to liter 1 The film is then washed for about 5 minutes in several changes of distilled water. The dyes are then bleached by treatment for about five minutes in a sodium stannite solution made in the following manner:

Stannous chloridegrams 8 Water (distilled) c.c 1G0 Sodium hydroxide (10% solution) do 100 The element is again washed first inplairr water for about 30 seconds and then for 5 minutes in a solution of 20 0.0. concentrated hydrochloric in 1 liter of water. The silver images are then bleached in the same copper chloride bath previously used. This reconverts to silver chloride the silver formed in the bleaching bath by reduction with the sodium stannite solution, to silver chloride. The film is then again washed and is then fixed in an acid hypo bath of the same composition as that previously used. It is then washed and dried,

In place-of the copper chloride bleach bath used to bleach the silver images to silver chloride, baths of the following composition may be used:

A. Quinone, hydrochloric acid and ethyl alcohol.

B. Ferric chloride and hydrochloric acid.

0. Ammonium persulphate and hydrochloric acid.

In some cases it is desirable to add an organic solvent to the sodium stannite bleach bath to reduce highlight stain. One volume of tertiary butyl alcohol to about 10 volumes of the bleadh bath appears to be a satisfactory solvent for this purpose.

With certain dyes, Pontamine Fast Green 58L for example, a 2% solution of sodium hydrosulfite can be used to bleach the dyes in the presence of the silver chloride image.

A photographic element containing the dyes reierred to above may be processed according to the method of the present invention to form coloreduccessfully bleached by these aflected the dye in the remaining claims.

I claim:

1. The method of forming a colored image in a photographic layer containing a bleachable azo dye uniformly dispersed therein and a rehalogenized silver image, which comprises bleaching the dye in the region of said image with an alkaline stannous chloride bleach bath.

2. The method -'of forming a colored image in a photographic layer containing a bleachable azo dye uniformly dispersed therein and a rehalogenized silver image, which comprises bleaching the dye in the region of said image with a sodium hydrosulflte bleach bath.

3. The method of forming a colored image in a photographic layer containing a bleachable azo dye and unexposed silver halide uniformly dispersed therein, which comprises exposing and developing said layer, removing the unexposed silver halide without affecting the silver image formed by development, reconverting the silver image to silver halide, and bleaching the dye inthe presence of. said image with alkaline stannous chloride to form a colorless dye compound and leave unportions of the layer.

4. The method of forming a colored image in a photographic layer containing a bleachable azo dye and unexposed silver halide uniformly dispersed therein, which comprises exposing and developing said layer, removing the unexposed silver halide without ailecting the silver image forined by development, reconverting the silver.

image to silver halide, and bleaching the dye in the presence of said image with sodium hydrosulflte to form a colorless dye compound and leave unaffected the dye in the remaining portions of the layer.

5. The method of forming a colored image in a photographic layer containing a bleachable azo dye and unexposed silver halide uniformly dispersed therein, which comprises exposing and developing said layer, removing the silver halide without aiiecting the silver image formed by development, reconverting the silver image to silver halide. and bleaching the dye in the presence of said image with a stannit oi alkali-metal to form a colorless dye compound and leave unafiected the dye in the remaining portions of the layer.

6. The method of forming a colored image in a photographic layer containing a bleachable aao dye and unexposed silver halide uniformly dispersed therein, which comprises exposing and developing said layer, removing the undeveloped silver halide without aflecting the silver image formed by development, reconverting the silver image'to silver halide, and bleaching the dye in an alkaline, reducing bleach bath comprising an alkali metal salt of an acid selected from the group consisting oi stannous acid and hydrosulfurous acid and free of silver halide developing agent in the presence of said image to form a colorless dye compound and leave unaffected the dye in the remaining portions of the layer.

GEORGE