US2454001A

US2454001A - Control of contrast with aromatic diamine color developers

Info

Publication number: US2454001A
Application number: US627329A
Authority: US
Inventors: Fritz W H Mueller
Original assignee: General Aniline and Film Corp
Current assignee: GAF Chemicals Corp
Priority date: 1945-11-08
Filing date: 1945-11-08
Publication date: 1948-11-16
Anticipated expiration: 1965-11-16

Description

Nov. 16, 1948. F. w. H. MUELLER 2,454,001

7 CONTROL OF CONTRAST WITH AROMATIC DIAMINE COLOR DEVELOPERS Filed NOV. 8, 1945 COL-0R POSFHVE FlLM R 7. t V} Z m D LOG ExPosuRE' 3.0 COLOR NEGATIVE. Fn..M

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LOG EXPOSURE M INVENTOR FRITZ W.H. MUELLER 8Y3 Q M ATToR NEY Patented Nov. 16, 1948 CONTROL OF CONTRAST WITH ,AROMATIC DIAMIN E COLOR DEVELOPERS Fritz W. H. Mueller, Binghamton,

N. Y., assignor to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware Application November 8, 1945, Serial No. 627,329

4 Claims.

This invention relates to color photography, and more particularly to a development of color images by means of aromatic diamine developing agents in the presence of protein decomposition products in order to control the contrast of color images obtained upon coupler development.

In color photography, it is well-known that dye images are formed by a coupling reaction of an oxidized primary aromatic amine developing agent with a suitable organic compound having an active methylene or reactive ethenol group. As development proceeds, the corresponding azomethine or indophenol dyes are formed in situ with the silver image. Speed and gradation control are readily accomplished in the usual dye coupling process, but difficulties are encountered in controlling the contrast or gamma of the color image to obtain the proper color balance. Color developers which are-used in subtractive color processes are Well-known in the prior art, and comprise reducing agents which, when acting upon exposed silver-halide, produce oxidation products which in turn yield insoluble dye images with suitable color couplers. Such color couplers may be either incorporated as non-difiusing color components in the individual layers of a, multicolor subtractive process or may be added to the color developer in difiusible form.

It is known that natural proteins of very high molecular weight and protein decomposition products of medium to high molecular weight within the range of the molecular weights of lysalbinic acid, gelatose and the like, have been added to ordinary black and white developers, 1. e., developers containing mono-amines alone, or in combination With hydroquinone or other adjuvants in order to yield softer silver images of finer grain. Developing agents of the monoamine type, whether alone or in combination with other adjuvants and in the presence of protein decomposition products as described in United States Patent 2,164,687, do not control the contrast or gamma of the color images produced in multi-color subtractive processes. In other words, fine grain developers do not exert a selective influence on the gamma of the characteristic curve representing the dependence of developed color density upon the logarithm of exposure in the individual layer of the multi-layer subtractive color film.

I have discovered that the addition of a relatively small quantity of a protein decomposition product of medium to high molecular weight, as described in U. S. 2,164,687 to color developers of the aromatic diamine type gives an improvement in color balance 'of the dye image by selective adjustment of the gradation of the characteristic curves of the magenta and even more of the cyan layer. This discovery is of special value in subtractive multi-layer film where the various layers are developed simultaneously by a, single color developer solution. It appears that the rate of penetration of the color developer, and the rate of coupling of the color coupler varies, and that the color balance is not distorted if the gamma of the characteristic curves in the three individual layers is approximately the same. In other words, if one of the layers shows an excessive contrast, the color balance is inferior and color falsification results in the final picture.

The photographic multi-layer materials, which may be processed with the developers of the present invention, are color-reversible film, colornegative film, color-positive film, color-reversible printing material coated on a white opaque film base or color-positive printing material coated on paper. A color-reversible film, as prepared according to United States Patent 2,186,849, consists of an integral tripack emulsion coated on the usual clear cellulose acetate or nitrate film base. Each of the three emulsion layers contains a color-former and is sensitized to one of the primary colors of light. The top layer is blue-sensitive and contains a color-former for the yellow dye image. A filter layer, yellow in color and blue absorbing, lies underneath the top layer. Below this filter layer lies the green-sensitive emulsion layer containing a color-former for the magenta dye image. The bottom layer is a redsensitive emulsion layer containing a color-former for the cyan dye image. The color-negative film is made up in the same manner as the colorreversible film, with the exception that it may contain a layer of clear gelatin between the redsensitive layer and the green-sensitive layer. The color-reversible opaque materia1 is prepared in the same manner as the color-reversible film, with the exception that the base consists of an opaque white film. The color paper is made up in the same manner as the color-reversible film, with the exception that the emulsions are coated on a baryta-coated paper base. When the silver-halide latent image is developed with a primary aromatic amino developer, the oxidation product of the developing agent reacts-with the color-formers to give a colored dye image.

As examples of suitable aromatic diamine developing agents which may be employed with the protein decomposition products, there may be mentioned p-phen'ylenediamine, p-aminoethylanor primary amino group in the phenyl nucleus which enables the oxidation product of the developer to couple with the color-former to form a dye image in the emulsion adjacent to the individual particles of the silver image. The silver image may be removed by bleaching in the well-known manner to leave the color image in the emulsion- A suitable developing solution is prepared as follows:

p-Diethylamino aniline hydrochloride "grams" 2.5 Sodium sulfite (anhydrous) do 1.0 Sodium carbonate (monohydrate) do 67.5 Potassium bromide do 2.0 Water to make liter 1 The concentration of protein decomposition products such as sodium lysalbinate, peptone, gelatose and similarprotein degradation products may range from to grams per liter of developer solution. A concentration approaching grams per liter has the tendency of not only reducing the contrast of the cyan image, but may lead to stain and reduction of the maximum density of the dye image. The optimum concentration resulting in optimal color balance can be readily ascertained for the various types of color film and papers and for the various species of diamine developing agents by a few routine experiments.

The present invention is illustrated by the ac companying drawing in which Figures 1 to 2represent typical characteristic curves of the color densities in the individual layers obtained on color positive and color negative films as described be,-

low by way of examples and the films treated in the manner set forth.

In Figures 1 to 2, wherein the ordinates represent densities and the abscissa represent the log of exposure, A, B, and C (which represent yellow, magenta and cyan, respectively) are the density curves for color positive and color negative films, respectively, which have been exposed and developed in an aromatic diamine developing agent in the ordinary manner, and A, B, and C, are the density curves for the same type of film exposed under the same conditions and 'treated with a diamine developing agent in the presence of a protein decomposition product in accordance with the present invention.

The following examples will serve to specifically describe the invention as applied to color positive and color negative films. These examples should not be construed as limiting or' restricting the present invention, but should be considered merely as illustrative.

Example I minutes in a color developer as above described.

Th n t ur a an? 9 a ll strated in Figure 1, were obtained by reading the color densities in the individual yellow, magenta and cyan layers, by employing the proper filters in a photoelectric densitometer in a known manner. From this figure, it will be observed that the cyan layer, C, has too steep a gradation to obtain a good color balance.

By adding 5 grams of sodium lysalbinate to a liter of the same color developer and developing a similarly exposed color positive film, the contrast of the cyan layer, C, was noticeably reduced as shown by the dotted line C, whereas the curves A (yellow) and B (magenta) were altered very slightly as shown by dotted lines A and B, respectively.

Example II A multi-color subtractive negative film was developed with a color developer as hereinbefore described without the presence of a protein decomposition product. The density curves obtained were plotted as A, B, and C shown in Figure 2,. From these curves, it will be observed that their shape is quite irregular and substantially altered,

By adding 5 grams of sodium lysalbinate to a liter of the same color developer and developing a similarly exposed color negative film, the shape of these curves, A, B, and C, are more uniform, particularly in the high densities, as shown by the dotted lines A, B, and C.

Example III Similar results as obtained in Examples I and II were procured when peptone and gelatose were substituted for sodium lysalbinate in equal amounts.

While I have herein disclosed the preferred embodiments of my invention, I do not desire to limit myself solely to the specific examples, since it will be readily apparent to those skilled in the art that precise ratios of protein decomposition products and the aromatic diamine developing agent may be varied and other materials having equivalent chemical or physical properties may be employed without departing from the spirit and scope thereof. As for example, instead of employing the protein decomposition products specifically disclosed herein, polypeptides either synthetically prepared or obtained by controlled protein hydrolysis in the known manner may be employed with satisfactory results. Accordingly, therefore, only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. The process of preventing the formation of excessively contrasty dye images in the individual layers of a multi-layer color film containing silver-halide emulsions and color formers which comprises exposing the film and developing simultaneously all layers with a solution of an aromatic diamine developing agent containing a primary amino group and 5 to 15 grams per liter of said solution of a protein decomposi tion product of medium to high molecular weight substantially within the range of the molecular weights of lysalbinic acid and gelatose, the molecules of thesaid protein decomposition products being built up of at least five amino acids.

2. The process of preventing the formation of execssively contrasty dye images in the individual layers of a multi-layer color film containing silver-halide emulsions and color'formers which comprises exposing the film and developing simultaneously all layers with a solution of an. sweetie d st ld elqnin e t c lil e a primary amino group and 5 to 15 grams per liter of said solution of sodium lysalbinate.

3. The process of preventing the formation or excessively contrasty dye images in the individual layers of a multi-layer color film containing silver-halide emulsions and color formers which comprises exposing the film and developing simultaneously all layers with a solution of an aromatic diamine developing agent containing a primary amino gI'OllP and 5 to 15 grams per liter of said solution of gelatose.

4. The process of preventing the formation of excessively contrasty dye images in the individual layers of a multi-layer color film containing silver-halide emulsions and color formers which comprises exposing the film and developing simultaneously all layers with a solution of an aromatic diamine developing agent containing a primary amino group and 5 to 15 grams per liter of said solution of peptone.

FRITZ W. H. MUELLER.

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

UNITED STATES PATENTS OTHER REFERENCES Henney, Handbook of Photography, Mc- Graw-Hill Book Company, Inc., 1939, pages 335 and 337 cited.

Riegel, Industrial Chemistry, Reinhold Publishing Corporation, 1937, page 620 cited.