US2663637A - Process of producing integral color correction masks - Google Patents

Description

Patented Dec. 22, 1953 UNITED STATES PATENT OFFICE 6 Claims.

This invention relates to colouring processes and more particularly to colouring processes for use in colour photography.

The dyestuffs and pigments used in practice in subtractive processes of colour photography do not possess ideal special absorption curves. In addition to absorbing light in the desired part of the spectrum they also absorb somelight in other parts of the spectrum and in consequence the colour reproduction obtained is never ideal. For example magenta dyestufis formed by colour development absorb the desired complementary coloured green light and in addition always absorb undesirably a certain amount of blue light. It has been proposed (see for example The Journal of the Photographic Society of America, volume 13, 94-96, February 1947) to correct for these deficiencies by the use of an automatic masking method whereby coloured colour formers are used, the light absorption of the coloured colour former being equal or approximately equal to the undesired light absorption of the developed dyestufi. For example the colour former which is used in a photographic layer to form a magenta dyestufi on colour development may itself be coloured yellow so that it absorbs blue light at an intensity equal to the undesired blue absorption of the magenta dyestufi" formed by colour development. Accordingly the unchanged colour former itself forms the coloured mask and the blue absorption of the photographic layer is a constant value (irrespective of the green absorption of the magenta image) which can be compensated for by using a suitable filter when printing.

The coloured colour formers it has been proposed to use in the above process are compounds containing the group -N=NR where R is an aromatic or heterocyclic radical. The

N=NR

group is'split off during the development with an aromatic amino compound and replaced by the phenylimino radical derived from the aromatic amino compound. Apart from the'difiiculties caused by the use of a coloured layer, particularly in multidayer films, the main practical objection to the above automatic masking process lies in the fact that the reaction of coloured colour formers of this kind with the aromatic amino compounds used for development is usually much slower than the reaction of the normal colourless colour formers with the aromatic amino compounds.

We have now discovered a new masking process PROCESS OF PRODUCING INTEGRAL COLOR CORRECTION MASKS Karl Otto Gauguin and Norman Hulton Haddock,

Blackley, Manchester, Imperial Chemical Indu ration of Great Britain No Drawing. Application August 1, 1949, Serial No. 108,045

Claims priority, application Great Britain August 20, 1948 England, assignors to stries Limited, a corpovolved in using this kind of coloured colour former. In our new masking process we use colourless colour formers, the yellow colour former being of a particular kind, and after developing the image with a colour iormingdeveloper, we treat the film with a gelatine hardening agent so that the residual colour former in selected parts of the film is rendered incapable of coupling with a diazonium compound, and subsequently we treat the film with a diazonium compound so that the residual colour former, which is still capable of coupling, is converted into the desired colour masks.

According to our invention we provide an improved process for colour photography which comprises developing with a colour forming develope an exposed multilayer film wherein there is present in at least one of the layers, a yellow colour former which contains in its molecular structure the grouping COCI-I2CO as part of an open chain of atoms, treating the film with a gelatine hardening agent, and subsequently treating the film with a solution of a diazonium compound.

The process of our invention is particularly valuable for use in three colour subtractive processes of colour photography in which there are used multilayer films which contain yellow, magenta and cyan colour formers in three separate layers, and in which the colours are formed by developing the films with alkaline solutions of aromatic amino compounds, such as for example p-diethylaminoaniline. In such processes'to improve the fidelity of colour reproduction, a colour mask is required in the magenta layer, (that is the layer containing the magenta colour former)v to correct for the imperfect colour absorption of the magenta dyestuff, and to a smaller extent in the cyan layer, to correct for the imperfect colour absorption of the cyan dyestuff, but no mask is usually required in the yellow layer. In the process of our invention the film after colour development contains residual colour former which is capable of reacting with a diazonium compound to form a colour mask but after treating he film with a gelatine hardening agent, the yellow colour formers of the kind hereinbefore defined, present in the yellow layer of the film, are unable to react with the diazonium compound and accordingly no mask is formed in the yellow layer. This effect is a general efifect obtained with different kinds of gelatine hardening agents. This efiect is not completely understood but it appears to be associated with the 2,663,637 i v m overall hardening of the yellow layer containing the specified colour former.

As examples of yellow colour formers suitable for use in the process of the present invention, there may be mentioned p-stearoylaminopenzoylacetanilide-p -carboxylic acid, p-methoxybenzoylaceto (2 N octadecyl a N methylamino) -carboxyanilide, p-stearoylaminobenzoylacetamlide-3:5-dicarboxylic acid.

The quantities of colour formers originally introduced into the magneta layer and the cyan layer may, if desired, be so adjusted that after exposure and colour development there is very little or no residual colour former in these layers in the areas of maximum exposure so that little or no colouring matter is formed in these areas of maximum exposure on treating the film with a solution of a diazonium compound and accordingly the overall fog of the masking image is reduced to a minimum. This forms a further feature of our invention. When the quantities of colour former are so adjusted, the treatment of the film with a hardening agent may be carried out before, during or after the bleaching of the silver, and any gelatine hardening agents, for example compounds of aluminum or chromium, can be used. For example there may be used potassium alum or chrome alum or there may be used the hardening agents used for the imagewise tanning of gelatine in the so-called Carbon, Carbro, Collotype, Bromoil or Transfer processes (see for example History of Color Photography by J. S. Friedman, 1947, published by The American Photographic Publishing Company, Boston) Alternatively the fog of the masking image can be controlled by carrying out the hardening treatment simultaneously with the bleaching out of the silver, that is to say by treating the film after exposure and colour development with a tanningbleaching bath. This forms a still further feature of our invention. Examples of such tanningbleaching baths are for example described in History of Color Photography by J. S. Friedman, 1947, pages 466, 467 and Q68.

In this modification of the process all the residual yellow colour former is rendered incapable of coupling but seemingly in the magenta layer and cyan layer only imagewise hardening occurs since on treating the film with a solution of the diazonium compound coupling occurs counter-imagewise in these layers. In this modification of the process therefore it is unnecessary to adjust the quantity of colour formers incorporated in the emulsions in order to ensure that the colour former is substantially used up in the areas of maximum exposure.

The density and gradation of the masking images formed in the process can be controlled by adjusting the concentration and temperature of the solution of diazonium compound used in the process. The relative density and gradation of the masking images in the magenta layer and the cyan layer can be controlled by adjusting the relative concentration and nature of the colour formers used in the two layers. Alternatively the relative densities and gradation of the two masking images can be controlled by using as colour former in the cyan layer a mixture of a colour former of the i-naphthol series with the 4- position unsubstituted, and a colour former of the l-naphthol series with a substituent in the 4-position. This substituent in the 4-positi0n prevents coupling with a diazoniuin compound but does not prevent reaction with the aromatic amino compound used as colour-forming developer and this forms still a further feature of our invention. For example there may be used a mixture of the p- (methyl-octadecyl-amino) -anilide of l-hydroxy- 2-naphthoic acid and of the corresponding 42-5111- phonic acid. The unsulphonated colour former will react either with the colour forming developer or with the diazonium compound but the sulphonated colour former will react only with the colour forming developer and not with the diazonium compound.

The diazonium compounds chosen for use in the formation of the masking images should be such as will react with the residual colour formers to give azo dyestuiis having the light absorption properties required to compensate, as far as possible, for the undesirable light absorption or the dyestuffs formed by the normal colour development with aromatic amino compounds. The solutions of the diazonium compounds may be prepared by diazotising the parent bases or alternatively they may be prepared from any available form of stabilised or passive diazonium compound (see for example The Aromatic Diazo Compounds by K. H. Saunders published by Edward Arnold & Co., London, 1936).

The process of our invention may be used to obtain positive masking images alongside the normal negative images obtained by simple exposure and colour development or alternatively it may be used in association with reversal processes so that negative masking images are obtained alongside the normal positive images and this forms a still further feature of our invention. For example the multilayer film may be first exposed to the light from an object or to the light transmitted by a colour transparency, developed with a black and white developer, the

developed silver re-bleached to silver chloride.

and the latter dissolved out with, for example,

sodium sulphite solution which does not affect.

the residual silver bromide. The film may then be fully exposed to light and subsequently processed by developing with a colour forming developer, bleach-tanning, treating with a diazonium compound and fixing. Alternatively if the quantities of colour formers in the magenta layer and cyan layer have been suitably adjusted, the film may be exposed to the image or to the light transmitted by a colour transparency, developed with a black and white developer, re-exposed and developed with a colour forming developer, tanned, treated with a diazonium compound, bleached and fixed.

The invention is illustrated but not limited by I the following examples in which the parts are by weight.

EXAlVEPLE 1 A multilayer light sensitive photographic film is made up as follows:

A support material is coated with a layer or" red light sensitised emulsion containing 10 grams per litre of the cyan image producing colour coupler described in Example 10 of British specification No. 465,823. Upon this layer there is coated a green light sensitised emulsion containing 10 grams per litre of the magenta image producing colour coupler described in Example 3 of British specification No. 502,665. A layer of colloidal silver is now coated on to act as a filter layer, and finally a layer of unsensitised emulsion containing 10 grams per litre of the sodium salt of p-stearyl-aminobenzoyl acetanilide-p'-carboxylic acid. The film is exposed to access-vi light and developed in the developere'made up: by

the: following recipe. p-diethylaminoaniline hydrochloride The film is rinsed and transferred into a tanning-bleaching bath made up by mixing, equalparts of the following Solutions A and B.

Solution A Parts Potassium ferricyanide 37.5 Potassium bromide 36.25 Potassium dichromate 3-7.5 Acetic acidr". 10.0 Water to 1000 Solution B Parts Potassium alum 50 Water to 10 The film is washed. again, thentreatedwith a 1% solution of the zinc chloride double salt of p-nitrobenzene diazonium chloride, washed and finally fixed with a 20% solution of sodium thiosulphate.

After this treatment the red sensitive layer contains a cyan dyestuff negative image and also a red azo dyestufl positive image which serves as a mask to correct for the undesirable absorption of blue and green light by the cyan dyestuff.

The green sensitive layer contains a magenta EXAMPLE. 2

The material is exposed to light transmitted" by a colour negative or positive transparency and developed in the developer made up by the following recipe:

Grams Sodium sulphite anhydrous 25 Metol 2' Hydroquinone 14 Potassium bromide 2 Potassium thiocyanate 2.5 Sodium hydroxide 2 Potassium carbonate 4011 Sodium. sulphate anhydrous 10 Water.. 1000' After washing, the film is transferred into a bleaching solution made up by the following recipe: 7

Potassium ferricyanide grams- Sodiumchloride .do 50 Water cc 1000 The developed silver is thus bleached tosilver chloride. The film is then treated with a: 20%. solution of sodium sulphite which dissolves the silver chloride, but leaves the residual silver bromide unafiected.

The material is now exposed to the light from a tungsten lamp, developed in the colour developer of Example. 1 and then further processed as described in Example 1. Instead of the di'azo compound used in Example 1, the diazonium compounds derived from l-nitro-fi-methoxy aniline, e-methoxy-fi-nitroaniline, e-aminodiphenylamine, 4-benzoylami'no-6-methoxyani1ine or any other diazonium compounds which couple with colour formers to give the colours needed for masking purposes may be used.

The processed film contains in the red sensitive layer a cyan dyestuff positive image and a red dyestufii negative image, which. serves as a mask to correct the too low transmission of blue and green light by the cyan dyestuff. The green sen sitive' layer contains a magenta. dyestufi positive.

image and a yellow dyestuff negative image, which. serves as a mask to correct for the absorption of blue light by the magenta dyestuff.

The blue sensitive layer contains a yellow dyestuff positive image but no corresponding azo dyestufi negative image. The negative or positive dupe prints so obtained show improved colour fidelity and brightness compared with dupe prints made without colour correction masks.

EIMMPLE 3 A multilayer light sensitive. material is made up as follows:

A support material is coated with a layer of red light sensitive emulsion containing 6 grams per litre of the sulphonated condensation product described in. Example 10 of British'specification No. 465,823 and 2 grams per litre of the corre-- sponding unsulphonated. condensation product.

Upon. this layer is coated a ee light Sensitised emulsion containing 4 grams per litre of the magenta. image producing colour coupler described. in Example 3 of British specification No; 502,665. A colloidal silver layer is now coated on to act as a yellow filter layer and as the top layer an unsensitised emulsion is coated containing 10' grams per litre of the sodium salt of pstearyl. aminobenzoylacetanilide p-carboxylic acid;

The material is exposed to light and developed with the. colour developer used in Example 1. Alter-washing, the film is treated with a harden ing bath. containing 2.5% potassium chrome alum. The film is washed again and trans ferred to a bleaching bath of the following composition:

The film is washed. and soaked. inv a 1% solutionofithe zinc chloride double salt of 2-methtive obtained in Exampl 1.

EXAMPLE 4 A multilayer film is made up as described in Example 3.

After exposure to light the film is developed with the black and white developer used in Example 2, and after washing and reexposure it is developed in the colour forming developer used in Example 1. Then the material is hardened in the hardening solution made up according to the following recipe:

Potassium alum grams 39 Sodium acetate do 60 Water cc 1000 Acetic acid, glacial ce 5 The film is transferred into a 1% solution of the zinc chloride double salt of Z-methoxylnitrobenzene diazonium chloride. It is then bleached, fixed and finally washed.

The transparency obtained is of the reversal type and has features and improvements similar to those of the transparency obtained in Example 2.

EXAMPLE 5 A multilayer light sensitive material is made up as follows:

A support material is coated with a layer of red light sensitized emulsion containin grams per litre of the sodium salt of l-hydroxy--sulphonaphthoyl (2) -octadecylamide. Upon this layer is coated a green light sensitized emulsion containing 1o grams per litre of the 1t3-bis-( 8- cyanoacetyl)-5octadecylamino benzene. A colloidal silver layer is now coated on and as the top layer an unsensitised emulsion is coated containing 19 grams per litre of the sodium salt of p stearylaminobenzoylacetanilide-pcarboxylic acid. The material is exposed to light and developed with the colour developer used in Example l. The film is washed and then treated with the hardening solution used in Example 4.

The film is washed and then transferred to the bleaching bath used in Example 4.

The material is again washed and then immersed in a 9.5% solution of the zinc chloride double salt of 2-nitro-l-methoxy-benzene diazonium chloride, and finally fixed and washed. The colour negative obtained carries a cyan negative image in the layer next to the support, a magenta negative image and a yellow azo dyestuff positive masking image in the next layer, a clear gelatin layer left after bleaching of the colloidal silver, and finally a yellow negative image in the upper layer.

We claim:

1. A process for the production of subtractively colored photographic transparencies with color correction masks from multi-layer film having differently sensitized silver halide emulsion layers containing color formers adapted to form yellow,

magenta, and cyan images in separate layers by coupling with the development product of a primary aromatic amino developing agent and being capable of producing azo dyes by coupling with a diazonium compound, wherein the color former which is adapted to form a yellow image contains in its' molecular structure the group --CO--CH2CO-- as part of an open chain of atomsjwhich comprises exposing the film to light, color developing to said color images by treating said layers with said primary aromatic amino developing agent, treating the film with a gelatin hardening agent selected from the group consisting of chromium and aluminum gelatin hardening compounds to render the residual color former in the yellow image layer incapable of coupling with a diazonium compound, subsequently treating the film with a solution of a dlazonium compound to convert residual color former in the magenta and cyan colored layers into masking images and retaining the color images and masking images in said layers.

2. A process for the production of subtractively colored photographic transparencies as set forth in claim 1 wherein said color former containing in its molecular structur the group as part of an open chain of atoms is selected from the group consisting of p-stearoyl-aminoloenzoylacetanilide-p-carboxylic acid, p-methoxy-benzoyiacetc (2-l i-octadecyl-N-methylamino) 5- carooxyanilide, and p-stearoylaminobenzoylacetani1ide-3 5-dicarboxylic acid.

3. A process for the production of subtractively colored photographic transparencies as set forth in claim 1 wherein the quantities of magenta and cyan color formers in said difierently sensitized silver halide emulsion layers are so adjusted that after exposure and color development there is substantially no residual magenta or cyan color former in the areas of maximum exposure of their respective layers.

4. A process for the production of subtractively colored photographic transparencies as set forth in claim 1 wherein the treatment with the gelatin hardening agent is carried out simultaneously with the bleaching out of the developed silver.

5. A process for the production of subtraetively colored photographic transparencies as set forth in claim 1 wherein the cyan color former is a mixture of a color former of the l-naphthol series with the 4-position unsubstituted and a color former of the l-naphthol series with a substituent in the it-position.

6. A process for the production of subtractively colored photographic transparencies as set forth in claim 1 wherein prior to color developing to said color images, the multi-layer film is first exposed to light, developed with a black and white developer, bleached, and then fully exposed to light.

KARL OTTO GANGUIN. NORMAN HULTON HADDOCK.

References Cited in the file of this patent UNITED STATES PATENTS

Claims (1)

1. A PROCESS FOR THE PRODUCTION OF SUBSTRACTIVELY COLORED PHOTOGRAPHIC TRANSPARENCIES WITH COLOR CORRECTION MASKS FROM MULTI-LAYER FILM HAVING DIFFERENTLY SENSITIZED SILVER HALIDE EMULSION LAYERS CONTAINING COLOR FORMERS ADAPTED TO FORM YELLOW, MAGNETA, AND CYAN IMAGES IN SEPARATE LAYERS BY COUPLING WITH THE DEVELOPMENT PRODUCT OF A PRIMARY AROMATIC AMINO DEVELOPING AGENT AND BEING CAPABLE OF PRODUCING AZO DYES BY COUPLING WITH A DIAZONIUM COMPOUND, WHEREIN THE COLOR FORMER WHICH IS ADAPTED TO FORM A YELLOW IMAGE CONTAINS IN ITS MOLECULAR STRUCTURE THE GROUP -CO-CH2CO- AS PART OF AN OPEN CHAIN OF ATOMS, WHICH COMPRISES EXPOSING THE FILM TO LIGHT, COLOR DEVELOPING TO SAID COLOR IMAGES BY TREATING SAID LAYERS WITH SAID PRIMARY AROMATIC AMINO DEVELOPING AGENT, TREATING THE FILM WITH A GELATIN HARDENING AGENT, SELECTED FROM THE GROUP CONSISTING OF CHROMIUM AND ALUMINUM GELATIN HARDENING COMPOUNDS TO RENDER THE RESIDUAL COLOR FORMER IN THE YELLOW IMAGE LAYER INCAPABLE OF COUPLING WITH A DIAZONIUM COMPOUND, SUBSEQUENTLY TREATING THE FILM WITH A SOLUTION OF A DIAZONIUM COMPOUND TO CONVERT RESIDUAL COLOR FORMER IN THE MAGENTA AND CYAN COLORED LAYERS INTO MASKING IMAGES AND RETAINING THE COLOR IMAGES AND MASKING IMAGES IN SAID LAYERS.