US2442930A

US2442930A - Process for developing multilayer film containing color formers

Info

Publication number: US2442930A
Application number: US556324A
Authority: US
Inventors: Jr Herbert W Morreall
Original assignee: General Aniline and Film Corp
Current assignee: GAF Chemicals Corp
Priority date: 1944-09-29
Filing date: 1944-09-29
Publication date: 1948-06-08
Anticipated expiration: 1965-06-08

Description

J1me 1948- H. w. MORREALL, JR 2,442,930

PROCESS FOR DEVELOPING MULTILAYER FILM CONTAINING COLOR FORMERS Filed Sept. 29, 1944 4 J'z'l'l/er fiaZz'de 1 7/??? /ayer emulsion layers 3 c'onzfaz'mn g l/rea ('om vozmd INVENTOR flerberz MMorraaZZJz ATTORN Patented June 8, 1943 PROCESS FOR DEVELOPING MULTILAYER FILM CONTAINING COLOR ,FORMIERS.

Herbert W. Morreall, In, Binghamton, N. Y., as-

signor to General Aniline & FilmOorporation, New York, N. Y., a corporation of'Dclaware Applicationseptemher 29, 1944, Serial No. 555,324;

3 Claims.

The present invention relates to improvements in multilayer color films and to the processof development thereof, and relates in particular to multilayer. color filmv adapted for reversal development.

Multilayer colorfilms containing color formers in the respective layers and adapted to be developed by the reversal process, generally 'consistof a suitable backing orsupportupon which isanumber of layers, the first, for example, being a. gelatino silver halide emulsion sensitized to red light and containing a nondiffusing color coupling component capable of being developed inasuitable color developer-tea cyan colored image; the. second being a .gelatino silver halide emulsionsen-sitized togreen light and containing a, nondiffusingcolor coupling component capable of being developed in a suitable color developer to'a magentalimage; andthe third being agelatino silver halide emulsion sensitized to blue. light and containing a color coupling component capable of being developed with a suitable color developer to-a yellow image. Suitable nondifiusing color. coupling components are disclosed inU. S. Patents-2,179,238, 2,186,733, 2,224,329 and'-2,178,612. Generally, also, betweenthe second and third layers is interposed a suitable yellowfilter layer the color of which is. destroyed in the silver bleachingbath. Other kinds of color films containingcolorl formers in the respective layers, are also known.

Inthe reversal process of producing colored photographs, which is referredto vherein to illustrate'theinvention, the multilayer color, film having the color l formers contained within the respective layers, after initial exposureto light from the subject to be photographed, is first developed with a noncolor' forming developer to produce a silver'negative, then the film is removed irom the developer and re-exposecl to whitelight, and thereafter. the film is developed to develop the color formers. Finally thereduced-silver is'removed fromthe film by a suitable silver solvent. In this process. difficulty heretofore has been encountered in obtaining adequate negative development of. the lowermost layers in the film. For example, in atypical multicolor tri-pack filminwhich thecyan layer is the lowermost layer, the development of color film as above described tends toresult in a decrease in effective sensitivity orphotographic speedof the film, and also results in excessive green highlights in the filmondeveloping of the coloredimage. Attempts to overcome this dinic-ulty by extending thetime of the first develop- 2. ment havenot produced satisfactory. results because this causes overdevelopment and reduction in contrast in the image in .the uppe'rmostlayers.

It'is an object of the .present invention to. provide an improved multilayer color film containing-the colorformers Withintheseveral. layers having an increased photographic speed;

Another object of the invention is .to provide an improved multilayer reversalxcolor. film containing the color formers within-the several layers which results in an increase. of speed of thecolor film and reduction of the green highlights in the reversal development.

Another object is to reduce the time. required for developing multilayer. color. film containing the color formers Within several layers.

Another object is the provision of; acleveloping process for multilayer color .film Wherebythedcvelopmentmay be carried out at temperatures below normal roomtemperature, or at normal room temperature ina shorter, time.

In accordance with the present invention, I have found that the development. of. an exposed multilayer color film in the presence of a com:- pound of the general formula:

NH: wherein X represents hydrogen, a saturated or unsaturated aliphatic hydrocarbon-radical, or the cyanide radical, overcomes the difiiculties heretofore experienced and-results in an increase in speed of the multicolor film. In particular in the reversal development process the lowermost layer in atri-pack film, which is the cyan layer, is benefited by reduction of the green highlights. The green highlights are believe d to be caused by incomplete development of the image inthe lower layer in the first or negative development so that undeveloped silver remains and reacts in the color forming development to produce color in those parts of the layer wherethere should be no color. When the film is viewed through White lightthe cyan layer allows green to pass through and thus produces a green highlight. Similar beneficial results are obtained in developing multilayer color negative films in the presence of said compounds according to the present invention, particularly when the urea compound is incorporated in the emulsion.

In particular I prefer to employ the Nellydrocarbon substituted ureas corresponding to the above formula in whichX represents asaturat'ed or unsaturated aliphatic hydrocarbon group, as

3 for example the 'allyl or the methyl group, such compounds being represented by the followin formula:

NHZ NHQ where Z represents an aliphatic hydrocarbon radical, as for example, methylor allyl-. In general, urea itself is more active than the substituted compounds in the above formula, and larger quantities of the substituted compounds are required to produce the beneficial effects of urea. For simplicity of expression in the following description of the invention the term urea compound will be employed to generically designate the substances included in the above formula.

The urea compound referred to herein may be present in the various gelatin emulsion layers of the film, or may be added to the developing solution employed in the first or negative development with satisfactory results. It is believed that the urea compound acts as a swelling agent upon the gelatin emulsion to allow faster and better penetration of the developer, and this is accomplished without unduepermanent softening or other undesirable results. When added to the developer solution it accelerates the development of all layers and particularly that of the lowermost layer and has little if any deleterious effect on the stability of the solution. Also the maximum color density, the gradation or contrast of the developer film and the eifect upon the grain size of the final dye image is not substantially adversely affected. Furthermore it has no permanent softening effect on the emulsion, for it is washed out by the subsequent treatment in the development of the film so that the film resumes substantially its original hardness.

In employing a urea compound in the gelatin emulsion a concentration of about one to ten grams per kilogram of emulsion may be employed. Optimum effects with urea generally are obtained with a concentration of about 4 to 6 grams per kilogram of wet emulsion, or about 4 to 6 percent of the dry emulsion. Such emulsions it will be understood, contain suitable color sensitizers and color formers, the urea being added to the emulsions preferably after the washing operation and just prior to the coating of the emulsion layers on the support.

The quantity or concentration of urea compound in the developer solution required for obtaining results depends, among other things, upon the initial hardness of the gelatin in the emulsion layers and upon the temperature at which the development takes place. For the development at room temperature, I have found that a concentration of about 65-75 grams urea per liter of developer solution is suflicient although in developing unusually hard gelatin layers I may use 100, 125 or 150 grams urea per liter, and for softer emulsions I may use as low a concentration as 25 grams of urea per liter. Corresponding quantities of the other urea compounds above referred to may be employed. Too high a concentration of urea is to be avoided for it has a tendency to produce softening and reticulation of the emulsion. Urea has very little effect on the pH value.

The advantages pointed out above in particular are secured where the first development of the multilayer color film is carried out with amidol, which is a preferred developer. Alkali in a developer is known to have a softening action on the gelatin, but alkali rapidly deteriorates amidol developer. Thus in the use of amidol as a developer, it is necessary to avoid a high PH value in the solution, and this may be accomplished by the addition of the urea compounds to the developer solution which accelerates the effect of the developer without unduly increasing the pH value of the solution. However, it will be understood that the beneficial effects of the present invention are not limited to the use of amidol as the developer, as other developers known in the art may be employed.

If desired the beneficial effect of urea may be availed of by carrying out the development at lower than room temperature or by carrying out the development at room temperatures for shorter periods of time.

The invention will be explained in greater detail in connection with the following examples and accompanying drawing which are cited to illustrate the invention, and wherein:

Figure 1 illustrates a preferred embodiment of color film incorporating the invention and Figure 2 illustrates by representative graphs the speed increase in the layers of a multilayer color film.

Referring to Figure 1 wherein is shown one embodiment of color film, the numeral 1 represents a suitable support, such as a cellulose ester film which carries a suitable emulsion layer 2 sensitized to red light by a suitable sensitizer and containing a suitable complementary color former such as 3,5-di(phenylamino) phenol which is capable of being. developed in a suitable color developer such as p-diethylamino aniline to produce a cyan image. The emulsion layer 3 superposed on layer 2 is sensitized to green light by a suitable sensitizer and contains a suitable complementary color former, such as p-(oxynaphthoylamino) 1 phenyl-3-methyl -5- pyrazolone capable of being developed to a magenta image. Interposed between

layers

3 and 5 may be a yellow filter layer 4, such as a gelatin layer colored with Benzo Fast Yellow RL, C. I. 349A or any other suitable yellow coloring matter. If desired, this filter layer may be omitted. Layer 5 is sensitive to blue light and contains a suitable complementary color former, such as terephthaloylbiacetic acid anilide capable of being developed to a yellow image. The emulsions may be prepared, for example, as described in U. S. Patent 2,179,238, and about 4 to 6 grams urea per kilogram of emulsion are added after the washing operation just prior to applying the emulsion layers to the support.

Example I.Tri-pack color film An exposed tri-pack color film is developed in a developer solution composed, for example, of 5 grams amidol, grams sodium sulfite crystals and 2 grams potassium bromide in a liter of water to which is added grams of urea, the film being developed in this solution for about 20 minutes. The development is then arrested and the film exposed to white light, and thereafter the film is developed in a color forming developer solution containing, for example, diethyl-pphenylenediamine, which produces positive silver images simultaneouslywith the formation of colored dye images. All the silver then is bleached to metallic silver, and the metallic silver from each layer is removed with Farmers solution leaving pure dye images in natural color. The positive produced in this way shows an absence of undue green highlights and results in a clearer image as compared to the film developed without urea.

Other known developers may be used with a suitable quantity of a urea compound, as for example, a metolhydroquinone developer containing metal 4 grams, sodium sulfite 40 grams, hydroquinone 4 grams, sodium carbonate 40 grams,

, potassium bromide 2 grams and potassium thiosulfate 2 grams in a liter of solution; or a glycine developer containing glycine 7.5 grams, sodium carbonate 50 grams, potassium bromide 2 grams and potassium thiosulfate 2 grams per liter.

Example 1TI.-Multilayer color negative film The exposed multilayer film with color formers in the several layers is developed for approximately 15 minutes at a temperature of about 68 F. in a developing bath containing per liter the following concentrations: 2 grams sodium sulfite, 3 grams p-diethylamine aniline hydrochloride, 25 grams sodium carbonate, and 2 grams potassium bromide, to which about 50 grams urea per liter has been added. After developing with this solution for about 15 minutes, the film is removed and washed for about 10 minutes, and then bleached for about 5 minutes in a solution of potassium ierricyanide. It is then washed for about 5 minutes and placed in a fixing bath of 10% sodium thiosulfate for about 5 minutes, again washed and then dried. The urea accelerates the development of the lowermost layers. The development of the upper layers is also accelerated so that the time of development is reduced.

Referring to Fig. 2, there are illustrated typical curves showing efiects of developing a multilayer color film in developer solution containing urea. Curve A shows a typical curve when the development is carried out without the presence of urea, curve B is typical of the effect produced in the first layer, which is the yellow layer and curve C typifies the efiect produced in the lowermost or cyan layer. These curves illustrate the marked increase in speed in the cyan layer as compared to the relatively lesser speed increase in the outermost layer. It will be understood that the effect on the intermediate layer in a three layer film will be generally intermediate curves B and C.

I claim:

1. The process which comprises subjecting exposed multilayer silver halide emulsion color film 6 sensitized to light of the primary colors respectively and containing within the respective layers color formers complementary to the color for which the layer is sensitized to a solution containing amidol and a compound of the following general formula:

NHX

wherein X represents a member selected from the group consisting of hydrogen, methyl, allyl and the cyanide radical in a concentration of about 25 to 150 grams per liter.

2. The process which comprises subjecting exposed multilayer silver halide emulsion color film sensitized to light of the primary colors respectively and containing within the respective layers color formers complementary to the color for which the layer is sensitized to a solution containing amidol and urea in a concentration of about 25 to 150 grams per liter.

3. The process which comprises subjecting exposed multilayer silver halide emulsion color film sensitized to light of the primary colors respectively and containing within the respective layers color formers complementary to the color for which the layer is sensitized, to a solution containing amidol and about to grams urea per liter.

HERBERT W. MORREAIL, JR.

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

UNITED STATES PATENTS Number Name Date 1,763,990 Sheppard et al. June 17, 1930 2,112,023 Hosking et al. Mar. 22, 1938 2,179,234 Schneider Nov. '7, 1939 2,191,037 Marines et a1 Feb. 20, 1940 2,304,025 Schneider et a1 Dec. 1, 1942 2,341,485 Swan Feb. 8, 1944 2,363,493 Baldsiefen Nov. 28, 1944 2,404,774 Dersch et al July 30, 1946 2,410,644 Fierke et al Nov. 5, 1946 FOREIGN PATENTS Number Country Date 512,060 Great Britain Aug. 29, 1939