US2304940A - Color photography - Google Patents

Description

Patented Dec. 15, 1942 UNITED STATES PATENT OFFICE COLOR PHOTOGRAPHY Leopold D. Mannes, Rochester, N. Y., and Leopold Godowsky, Jr., Westport, Conn., assignors to l Eastman Kodak Company, Rochester, N. Y., a v corporation of New Jersey Application January 19, 1940, Serial No. 314,689

In Great Britain January 23, 1939 14 Claims.

vtype which is Widely used commercially involves the coupling of a color forming compound with' a primary aromatic amino developing agent to form a colored image. The coupling compounds used in this process are those having a reactive methylene group or a reactive' phenolic group which couples with the oxidation product of the primary aromatic amino developing agent on photographic development. Suggestions have been made for incorporating these coupling compounds either in the developing solution or in the sensitive layer before exposure.

When the coupling compounds are incorporated in the developing solution, it is desirable that they be as soluble `as possible in the developing solution so that upon photographic development they will penetrate the gelatin or other colloidal material of the sensitive layer and thereby permit the formation of a dye image in any exposed portion of the layer. However, when the coupling compounds are to be incorporated in the sensitive layer prior to exposure, they should be insoluble in order that they do not wander out of the layer during coating of a multi-layer material or during photographic development. Methods have been proposed for keeping the coupler, compounds in the photographic layer, most of these involving the use of large molecules of coupler to prevent diffusion.

In U. S. Patent 1,055,155, March 4, 1913, Fischer describes a multi-color process using coupling compounds incorporated in the photographic layers. However, it has since been found that the coupling compounds known to Fischer could not be kept in the respective layers of a multi-layer material by merely mixing them with the gelatin of the emulsion'. All of the compounds disclosed by Fischer diiuse from the layer and no color separation can be obtained in Fischers process.

We have discovered a method for incorporating coloring materials such as coupling compounds in a photographic layer or layers so that they do not diffuse from the layer or layers but may be made to react with the oxidation product of an aromatic amino developing agent to form a colored image or colored images on photographic development. Our method does not in- A volve the use of large coupler molecules, since the couplers which we propose to use, if merely mixed with a gelatine-silver halide emulsion, would dilluse from the emulsion when used in a multilayer coating.

Our method consists in surrounding or mixing the coloringv material, such as a coupling compound, with a water-insoluble but water permeable cellulosic binder and then dispersing this l material in a colloidal material such as gelatin. For example if the coupler is mixed with a cellulose ester such as cellulose'nitrate and this mixture is then dispersed in gelatin, there is little or no tendency for the coupler to diffuse from the cellulosic material into the gelatin. This is true even when the coupler is quite alkali-soluble and couplers can, therefore, be employed which have hitherto been regarded as unsuitable for incorporation in photographic layers veither because of the readiness of their diffusion or because of the readiness of dilusion of dyes formed from them on photographic development. The coupling compounds with the cellulosie binder can best be suspended in the gelatin or other Water permeable material by means of an organic solvent which is immiscible with water and, therefore, it is possible to use couplers which are extremely insoluble in aqueous alkaline solution and Whose very insolubility in aqueous solutions hitherto made it diilicult to incorporate them in materials such as gelatin. In some cases the use of a water-miscible solvent, such as alcohol, induces crystallization or wandering of the coupler, and for this reason it is frequently desirable to use water-immiscible solvents in dissolving the coupler. Y

In the accompanying drawing the gures represent enlarged sections of photographic nlm made according to various modifications of our invention.

According to the present invention, there is provided a photographic element having a plurality of differentially color sensitive photographic emulsions on a single support. at least one such photographic emulsion containing a' coupling compound dispersed in a water-insoluble but water-permeable material. The elemeni-l may have a plurality of layers of diierentially color-sensitive emulsions on a single support, one at least of which layers consists of a dispersion of a water-insoluble but water-permeable binder containing a coupling compound in a gelatine-silver halide emulsion.

In the preferred modification of our invention, the photographic element may have an emulsion consisting of silver halide in gelatin, the gelatin having distributed therein finely dispersed particles of water-insoluble. water-permeable binder containing the coupling compound. A plurality of layers may be coated in this way each containing in the water-insoluble, water-permeable. cellulosic binder a coupling compound corresponding in a suitable manner to the sensitivity of the layer. For example, for the usual three-layer photographic element` a red sensitive photographic emulsion would be chosen containing a blue-green coupling compound, a green-sensitive emulsion containing a magenta coupling compound and a blue-sensitive emulsion containing a yellow coupling compound.

In another modification of our invention the cellulosic particles themselves may contain the silver halide as well as the coupling compound. In this modification of our invention particles of cellulosic binder may be prepared each containing the appropriate coupling compound and properly sensitized silver halide grains and these may be separately dispersed in a plain gelatin layer s that a single layer element is obtained in which three differently colored images may be formed. Obviously the color sensitizer, where one is employed, is included with the silver halide in any case.

' The water-insoluble, water-permeable cellulosic binder used to surround the particles of coupler may be a cellulose ester, such as cellulose nitrate or cellulose acetate, or a mixed organic ester of cellulose. such as cellulose acetate phthalate. Cellulose ethers may also be used. Collodion solutions, well known in the photographic art. may also be employed.

We have found that the cellulosic binders, a1- though they prevent the diffusion of the coupler into adjacent water soluble layers, that is into the gelatin, are suillciently accessible to the developing and other processing baths to enable the usual methods of color processing to be applied. By our method, therefore, known coupler compounds may be incorporated in photographic layers and the layers may be processed in the ordinary way. If desired, the color processing baths may contain ingredients such as organic solvents or wetting agents to facilitate the penetration into the water soluble binder.

We have found that different coloring materials and coupler compounds are respectively more suitable for use with diierent cellulosic binders and that with some combinations of coupling compound and cellulosic binder there is diillculty in obtaining satisfactory dye densities. This, we believe to be due to the diiculty of penetration of some of the cellulosic binders by the processing solutions. We have found that the structure or character of the cellulosic particles may be altered by incorporating in the cellulosic solution before dispersion substances which we shall call porosity modifiers. These materials change the porosity or consistency of the cellulosic material in the final state which it attains in the dried coating and enable better penetration of the photographic processing baths without inducing diffusion of the coupler. The following materials have been found suitable for this purpose:

Etherls Ethylene glycol monobenzyl ether Diethylene glycol monobutyl ether Diethylene glycol monobutyl ether monoacetate Diethylene glycol monoethyl ether Diethylene glycol diethyl ether Ethylene glycol monophenyl ether.

phthalate eaters Dimethyl phthalate Dibutyl phthalate Benzyl phthalate -Ethoxyethyl phthalate Alcohols Heptadecanol N-hexanol Octyl alcohol Miscellaneous esters Benzyl benzoate Triphenyl phosphate Tricresyl phosphate Ethyl palmitate Methyl abietate -Ethoxyethyl sebacate -Ethoxyethyl maleate -Ethoxyethyl adipate Ethylene glycol dilaurate Miscellaneows compounds p-Toluenesulfonanilide Tripropionin Trivalerin Monoacetin Triacetin These modifiers may be used in amounts ranglng from` 5% to 50% of the amount of cellulosic material.

Porosity may be effectively decreased by hardening with chromium salts, particularly where cellulose acetate is used as the water-insoluble, water-permeable binder.

I'he following examples which are illustrative only, indicate various methods of forming sensitive photographic layers for color photography according to our invention.

Example 1 An emulsion is m-ade by preparing a solution of the following ingredients:

r N-butyi acetate cc 1ooo This solution is mixed with the following:

Gardinal (fatty alcohol sulfate) g-- 2 1/z Water *n cc-- 1250 'I'he whole mixture is heated on a steam bath at C. with constant stirring to evaporate all of the butyl acetate and some lof the water. At the end of the evaporation process the volume has been reduced to about 300 cc. 'I'his dispersion of cellulose nitrate particles containing the coupler is added to 1000 cc. 'of a red-sensitive gelatino-silver halide emulsion. The resulting emulsion is coated on a suitable support. A yellow lter layer is then coated on the emulsion, consisting of tartrazine in gelatin.

'I'he top layer consists of a green-sensitive silver halide gelatin emulsion to which has been added a cellulose nitrate dispersion made as described in the preceding paragraph, but using as the coupler a mixture yielding an orange-red dye upon development. Suitable .couplers for this purpose are n-propyl-pbenzoyl acetamino benzene sulfonate and 2-cyanoacetylnaphthalenesulfon-N-methyl anilide. These couplers are used in the amount of 5 grams each and producing an orange red dye upon development in a couplingy developer. 'I'his emulsion is coated as the top layer to produce a two-layer sensitive material.

In place of the tartrazine iilter dye, the film may contain a yellow dye throughout the emulsions which is removable during processing either by virtue of its solubility or its susceptibility to a chemical action of one of the processing baths.

Example 2 A three-layer sensitive film is made as follows: The bottom layer consists of a red-sensitive gelatine-silver. halide emulsion to which has been added a dispersion of cellulose nitrate containing, as a bluegreen coupler, 5phenoxy acetamino-l-naphthol, made as described in Example 1. The middle layer is a green-sensitive gelatino-silver halide emulsion with a cellulose nitrate dispersion containing as a magenta coupler 2cyanoacetylnaphthalene-sulfon-N-methylanilide. Over the green sensitive layer is coated a thin intermediate layer containing a yellow illter material which is removed during processing, such as colloidal silver in gelatin. The top layer is unsensitized silver halide emulsion containing Y as a yellow coupler w-benzoylacet-o-chloranilide and cellulose nitrate dispersion made as in Example 1.

The amount of coupler used in these dispersions may vary over wide limits. It is found necessary to adjust the coupler concentration in each particular case depending upon the dye density to be produced the thickness of the layers and other factors. In general the coupler concentrations may range from about 21/9 grams kto about grams of coupler per liter of emulsion. The cellulose nitrate and other ingredients of the emulsion may also be Variedover a wide range, depending upon properties of the particular combination being used.

Example 3 A high speed photographic multi-layer material is made by coating three gelatino-silver halide emulsion sensitive respectively to the red, green and blue regions of the spectrum on a single support, each emulsion containing nely dispersed particles of collodion or another cellulose derivative containing no silver halide but merely the coupling compound required for that layer. For the red' sensitive layer the coupling compound (l-naphthol-Z-carboxylic-a-naphthylide) may be used, for the green-sensitive layer the coupling compound 2-cyanoacety1l naphthalene sulfon-N-methyl anilide may be used and for the blue sensitive layer the coupling compound benzoyl acct-2,5-dichloroanilide may be used. 'I'hese couplers produce respectively bluegreen, magenta and yellow images upon photographic development.

The processing of this iilm may be carried out either to produce a negative image by immediate immersion in a color-forming developer or it may be developed initially in an ordinary MQ developer or a positive image may be formed by exposing the :film to white light after the ordinary rst development and then developing the residual halide in a color forming developer. In either case the coupling compound remains within the cellulose particle into which, however, the oxidized coupling developer penetrates freely in those localities where it has been oxidized by developing the sensitive silver halide grains. A dye image is thus built up in those cellulose particles most nearly adjacent to the exposed silver halide grains.

Example 4 A sensitive photographic layer containing a coupler together with silver halide in a cellulosic binder the whole being dispersed in gelatin was made as follows:

cc. of a commercial collodion emulsion were diluted with 20 cc. of N-butyl acetate and this solution was then added to 100 cc. of a 0.1% solution of a higher fatty alcohol sulfate in water. This latter compound which is sold under the trade name Gardinolis a well known dispersing agent. To this solution there was added 0.25 gram of 5-phenoxyacetamino'-l-naphthol and the mixture was then run through a small homogenizer and was recirculated for five minutes. Subsequently it was vacuum distilled to remove solvents employed in the preparation of the collodion emulsion and the butyl acetate which was added as noted above. Prior to the removal of the solvent by vacuum, small amounts of N-octyl alcohol were added to prevent foaming. After the volatile solvents were removed. the suspension of iine particles in the Gardinol solution was added to cc. of a 6% gelatin solution and these were coated on a support. The particles of cellulosic binder thus produced were below 1 m/l in diameter. Upon exposure of this layer and development in an aromatic amino developing agent, a blue-green image was produced.

- Example 5 A collodion silver halide emulsion is made in the usual manner and divided into three parts A, B and C. To A and B are added respectively suitable quantities of non-water-soluble red and green sensitizers, for example, pinacyanol or the neothiazolocarbocyanine derived' from. 2,4-dimethyl thiazole ethiodide for the red, and erythrosin for the green. To A, B and C, respectively, are added suitable quantities of coupling compounds which, with a developer such as diethyl-p-phenylene-diamine, will yield blue-green, magenta and yellow dye images. Suitable compounds are 5,7-dibromo-8-hydroxyquinoline for blue-green, p-phenylbenzoyl acetonitrile for the magenta and -naphthoyl acetone for the yellow. At this stage there are three batches of collodion, silver halide emulsion differentially light-sensitive and capable of forming differently colored images. Sensitizers and couplers are contained in true solution in the organic solvents used for the collodion.

An aqueous gelatin solution is then prepared and maintained at a pH low enough to prevent dissolving the coupling components. To this gelatin are added in substantially equal quantities minutedried particles of the three collodionemulsions which have been spray dried or otherwise dispersed. These particles will be about the size of ordinary negative emulsion grains but each will contain a number of exceedingly ne silver halide particles suspended in the collodion and in intimate contact with the sensitizing dye and coupling compound.

After suitable mixture of the dispersed particles, the gelatin carrier containing them is coated as a single layer ona photographic support. On exposure and development in a single developer such as diethyl-p-phenylenediamine this layer forms three differently colored images.

Example 6 The following example illustrates the dispersion of an originally colored material in a cellulosic compound, in a gelatino-silver halide emulsion.

A solution is prepared containing 20 grams of cellulose nitrate, 10 grams of ethylene glycol monobenzyl ester, 10 grams of benzene azo cresol and 750 cc. of butyl acetate. This solution is emulsifled, for example, by homogenization with 1000 cc. of a 0.2% aqueous solution of a higher fatty alcohol sulfate. The emulsion is heated with stirring to expel the butyl acetate and the remaining iine suspension of dyed cellulose nltrate particles are added to 1000 cc. of a gelatine.

silver halide emulsion containing 6.5% gelatin.

Numerous coupler compounds are suitable for use in our invention where the photographic layer is designed to be developed with an aromatic amino developing agent. As stated above, couplers may be used which would not be suitable for incorporating in a. gelatin emulsion without the use of some special means to prevent diffusion. The couplers which we may use have a molecular size and shape such that, although capable of diffusing through gelatin, they are readily rendered non-diiusing by physically combining them with a dispersed cellulosic material.

The following couplers are suitable for use in our invention. It 1s to be understood that this list is not intended to be exhaustive, but merely to typify compounds which may be used.

Couplers producing cyan images 2,2 dihydroxy-5,5 -dibromostilbene p,p'Di-(2 hydroxybenzamido) diphenylmethane Sebacic acid di-(2-hydroxyanilide) 1-naphthol-5-sulfo-cyclohexylamine 1-naphthol-Z-carboxylic-a-naphthalide diamylnaphthalenesulfonamido-1naphthol 5diphenylethersulionamidol-naphthol 5-phenoxyacetamino-1-napl1thol 5-amyldiphenylethersulfonamidol-naphthol 2,4 dichlorc-4- lp-nitrobenzoyl--hydroxyethylamino] -l-naphthol Couplers producing magenta images 1,4-phenylene bis-3(l-phenyl-5-pyrazolone) 2cyanoacetylnaphthalenesulfon N methylanilide 2-cyanoacetylcoumarone 5-sulfon-N-methylanilide 2-cyanoacetylcoumarone-5-sulfondimethylamide 2-cyanoacetyl-5benzoylaminocoumarone 2cyanoacetyl--naphthofuran Cyanoacet--naphthalide Couplers producing yellow images N -phenyl-N- (p-acetoacetaminophenyl) urea p.p'Diacetoacetaminodiphenylmethane Benzoylacet2,5-dichloranilide N,N' -di- (w-benzoylacetyl) -p -phenylenediamine N,Ndi(p-benzoylacetaminophenyl) naphthaiene-1,5-disulfonamide p,p'-Di(acetoacetaminmdiphenyl 4 .4 -di acetoacetamino) 3,3'dimethyldiphenyl Our invention will now be described with particular reference to the accompanying drawing. As shown in Fig. 1, a support I0 of any suitable material such as cellulose nitrate or cellulose acetate, synthetic resin, or paper, is coated with a plain gelatin layer II .and a plain gelatin layer I2 each containing dispersed particles oi' a suitable water permeable but water insoluble cellulosic binder. Emulsion layer I2 contains the cellulosic particles I3 containing coupler A and silver halide. Gelatin layer II contains dispersed particles Il of cellulosic material containing coupler B and silver halide. It is to be understood that the silver halide is dispersed in the cellulosic particle and that the coupler is dissolved in it, and that the drawing is not intended to indicate that the silver halide and the coupler occupy concentric portions in the cellulosic particle.

As shown in Fig. 2, the support I0 is coated with gelatino silver halide emulsion layers I5, I6 and I1 sensitive respectively to the red, green and blue regions of the spectrum. Emulsion layer I'I contains cellulosic particles I8 containing coupler A', emulsion layer I6 contains cellulosic particles I9 containing coupler B' and emulsion layer I5 has dispersed therein cellulosic particles 20 containing coupler C'. 'I'he blue, green and red sensitive silver halide particles in the respective emulsion layers are represented by numerals 2|, 22 and 23.

Fig. 3 shows a support I Il containing a gelatin layer I I containing differentially sensitized particles of cellulosic binder. 2l is a particle of cellulosic binder containing coupler A' and silver halide grains, 25 is a particle of cellulosic binder containing coupler B' and silver halide grains sensitized to another region of the spectrum and 26 is a particle of cellulosic binder containing couplers C' and silver halidel grains sensitized to a third region of the spectrum.

The method of preparing, exposing and developing these various types of photographic element will be understood from referring to the specific examples above.

Our invention is susceptible of numerous var iations not herein speciiically described and it is to be understood that our invention is limited only by the scope of the appended claims.

We claim:

l. A light-sensitive layer for producing a colored image, comprising a gelatino-silver halide emulsion containing ilnely divided particles of a water-insoluble but water-permeable cellulose ester containing a color former in physical mixture therewith, dispersed in the gelatin.

2. A light-sensitive layer for producing a colored image, comprising an emulsion of silver halide in a water-soluble, water-permeable colloidal medium, said emulsion containing finely divided particles of a water-insoluble but waterpermeable cellulose ester containing a color former in physical mixture therewith, dispersed in the water-soluble, waterpermeable colloidal medium.

3. A light-sensitive element for producing a colored image, comprising a layer of a waterpermeable silver halide-colloidal medium having dispersed therein finely-divided particles of a water-insoluble but water-permeable cellulose ester containing a color-former in physical mixture therewith.

4. The method of producing a color-forming photographic layer, which comprises mixing a water-insoluble but water permeable cellulose compound in an organic solvent with a colorforming compound capable oi reacting with a primary aromatic amino developing agent on :giotcgraphic development, dispersing the mixture of cellulose compound and color-forming compound in a gelatino-silver halideemulsion, and coating said dispersion on a support.

5.. The method of producing a color-forming photographic layer, which comprises mixing a water-insoluble but water permeable cellulose nitrate with a color-formingl compound capable of reacting with a primary aromatic amino.. developing agent on photographic development, dispersing the mixture of cellulose nitrate and color-forming compound in a gelatino-silver halide emulsion, and coating said dispersion on a support.

6. The method of producing a color-forming photographic layer, which comprises mixing a water-insoluble but water-permeable cellulose acetate with a color-forming compound capable of reacting with a primary aromatic amino developing agent on photographic development, dispersing the mixture of cellulose acetate and color-forming compound in a gelatine-silver halide emulsion, and coating saiddispersion on a support.

'1. The method of producing a color-forming photographic layer, which' comprises mixing with a water-insoluble but water-permeable cellulose compound a porosity modifier for the material and a color-forming compound capable 'of reacting with a primary aromatic am'ino developing agent on photographic development, dispersing the mixture of cellulose compound and colorforming compound in a gelatino-silver halide emulsion, and coating said dispersion on a support.

8. The method of producing a color-forming photographic layer, which comprises mixing with a water-insoluble hut water-permeable cellulose nitrate a porosity modier for the cellulose nitrate and a color-forming compound capable of reacting with' a primary aromatic amino developing agent on photographic development, dispersing the mixture of cellulose nitrate and colorforming compound in a. gelatino-silver halide emulsion, and coating said dispersion on a .sup- DOrt.

9. The method of producing a color-forming photographic layer, which comprises mixing with a water-insoluble but water-permeable cellulose acetate a porosity modifier for the cellulose acetate and a color-forming compound capable of reacting with a primary aromatic amino developing agent on photographic development, dispersing the mixture of cellulose acetate'and colortorming compound in a. gelatino-silvei' halide graphic development, and a porosity modier for the cellulose compound which increases the per-7 meability of the cellulose compound to developing solutions when incorporated in a gelatin emulsion layer, and dispersing the cellulose compound containing the color-forming compound and porosity modifier in a gelatin layer.

11. In the method of producingv a sensitive photographic element capable of being developed to form a colored image, the steps which comprise dissolving in a water-insoluble but waterpermeable cellulose nitrate a color-forming compound capable of reacting with a primary aromatic amino developing agent on photographic development, and a porosity modier for the cellulose nitrate which increases the permeability of the cellulose nitrate to developing solutions when incorporated in a gelatin emulsion layer, and dispersing the cellulose nitrate containing the colorforming compound and porosity modifier in a gelatin layer.

12. A photographic element for producing multi-'color photographic images, comprising gelatin having dispersed therein a water-insoluble but .water permeable cellulose compound containing in separate particles different color formers in physical mixture therewith and differentlysensitized silver halides.

13. A photographic element for producing multi-color photographic images, comprising a gelatin layer having dispersed therein a waterinsoluble but water-permeable cellulose ester containing in separate particles diierent colorformers infphysical mixture therewith and differently-sensitized silver halides.

14. The method of incorporating a coupling compoundin` a light-sensitive gelatine-silver halide emulsion, which comprises dissolving it in a water-immiscible solvent and a water-insoluble but water-permeable cellulose ester, and dispersing the cellulose ester containing thecoupling compound, in the gelatino-silver halide emulsion.

LEOPOLD D. MANNES. LEOPOLD GODOWSKY. JR.

1 l cERTIFIcATE oF conBEcTioN. A. pap-,nt no. 2,5olh9ho. y December 15, 1.|.2

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