USRE23357E - Processes for producing same - Google Patents

Description

Reisaued Apr. 17, 1 951 COLOR. PHOTOGRAPHIC MATERIAL AND PROCESSES FOR PRODUCING sAME,

Bela Gaspar, Beverly Hills, Calif.

No Drawing Original No. 2,470,769, dated May 24, 1949, Serial No. 537,967, May 29, 1944. Application for reissue May 18, 1950, Serial No. 162,828. In Great Britain August 28, 1939 24 Claims. (Cl. 956) Matter enclosed in heavy brackets appears in the original patent but forms no partfofi this reissue specification; matterprinted in italics indicates the additions made by reissue.

1 This application is a continuation in part of my application S. N. 354,442, filed August 27, 1940, now abandoned, and relates to improved photographic light-sensitive materials in which V at least one of the light-sensitive emulsions, used j in the form of superposed layers of a multilayer material or in the form of difierently sensitized an diflerently colored emulsion particles distributed within the same layer, is dyed with an azo dye and to improvements in or relating to the process of producing the same. The superposed layers or emulsion particles, in each instance, form discrete portions within a coating or layer of the photographic material.

The invention has for its purpose the provision of improved material which can be produced in a very simple and reliable manner and in which the dye used for coloring the light-sensitive emulsion has only a negligible tendency to bleed or to diffuse during the manufacture, the storage or the processing of the material.

It is already known to use water-insoluble dyes for coloring the light-sensitive emulsions or layers, the insoluble dyes being introduced as such or produced within the colloid from their com-' ponents, by dye synthesis, or from their soluble derivatives, by decomposition. It is obvious that the coloring of the colloid by means of a soluble dye is much simpler than the incorporation of insoluble dyes, it only being necessary to add the dye solution to the colloidal solution 01' emulsion. n the other hand, it is a well-known fact that most of the water soluble azo dyes have a strong tendency to diffuse and that owing to this property it becomes necessary to precipitate the soluble dye within the colloid by a precipitating agent. There are only a restricted number of soluble dyes available which can be used-Without precipitating agent, such as, for example, the dyes referred to and used according to my prior British Patent Specification No. 445,806.

' According to the present invention light-sensitive silver halide emulsions used in the form of superposed layers in a multilayer material or in the form of differently sensitized and differently colored particles are dyed by a water or alkalisoluble polymeric azo dye derived from a diazotized aromatic amino compound which is capable of coupling with itself, the dye molecule being OH NH 2 formed by such coupling and containing a chain wherein a plurality of azo groups are positioned in alternating relationship with radicals of said aromatic compound. It has been found that from low-molecular aromatic components, there can be obtained by coupling of the diazotized aromatic amino compound with itself, dyes which have a high molecular weight and which, on the one hand, are water-soluble but, on the other hand, have only a negligible tendency to bleed or diffuse. Such dyes may readily be employed in the light-sensitive silver halide emulsions or in dyed filter layers adjacent to a light-sensitive silver halide emulsion layer. Layers dyed according to the invention are particularly useful for carrying out the process of producing dye images Example 1.--N-(p-aminobenzoyll-H acid (so-' dium salt) is dissolved in water and diazotized by acidifying the solution with acetic acid and adding sodium nitrite solution. The diazonium salt'solution is kept at low temperature for about an hour.- Thereafter, sodium carbonate is added to render the solution alkaline and the solution is heated, thereafter, to about 60 C. A'ma-f genta dye is formed which is salted out 'by' com mon salt. The v dye maybe represented by the following formula, omitting any terminal groups which may bepresent-which discloses ,the char acter of the units going-to make up the polymeric dye substance: Y Y

scan SOgH or by the formula:

on NB nos 3 in which the portion enclosed by the may be considered an 9.20 dye unit. The letter n in both formulae represents an integer greater than one indicating the (main characteristic. wherein a plurality of aZo groups are alternating with radicals of the aromatic compound. If the high molecular weight polymeric dye as shown in Formula B is reduced it can readily beseen'howgit will break down to form a product of low molecular weight which can be represented H NH EN 00- NH,

110, son

and whose similarity to the units which went to make up the polymeric dye,-Formula A, is readily apparent.

For coloring emulsions the dye is dissolved in water and the solution is added to the light-sensitive emulsion to diffusely distribute the ,dye throughout the light-sensitive emulsion. For producing filter layers the dye solution is mixed with a gelatin solution which is coated to form a filter layer-on a light-sensitive layer. For coloring light-sensitive emulsions aboutl-2 grams of the dye are used per sq; m. emulsion layer toobtain .a difi usely dyed layer. Differently colored layers in which one or more layers are dyed by means of the dyes defined above may be coated in superposition on a common support.

Example 2.- p amino benzoylamino) phenol-2-sulphonic-acid is diazotized in known manner and to the diazo solution is added 4% ammonia solution and 5% pyridine. After coupling, the solution is acidified with dilute hydroch 1o ricacid, and the resulting yellow dye is salted out and filtered. The dye has a good solubility and shows no diffusion in gelatine. About 0.3 to

1.0g. dye can be used per squaremeter coating.

The azo dyes in the above description are large molecules containing several azodye units; these azo-dye units alternating with heteronuclear bonds which linksaid azosdye'units together. The following general formula, omitting anyterminal groups which may be present, represents the character of the dyes:

where An and Ar: stand for aromatic hetero,- clic. r alip a r dic ap ble of r n azo roups. -.-.-N ..=N- stan s for a a li ka and B for a heteronuclear bond connecting two y un ts.

and where "n represents an integer greater than one. The letter a. means one,'in the case of the dyes disclosed above. However, I have found that other values for a are also possible, as will be described in greater detail. The expression heteronuclear bond means a chemical linkage interrupting the system of conjugation, and, therefore, practically excluding any essential influence of a dye unit (or groups within such a dye unit) on the color characteristics of any one of the other azo-dye units beyond the bridge B. The expression azo-dye unit" means that part of the molecule limited by two heteronuclear bonds (or by one bond if it is a terminal group) and which determines the spectral qualities of the dye. If

a dye of the indicated formula (where a equals,

is formed. The size of this reduction product depends only on the size of the single components and is independent of the value for n; in the original dye. The reduction product of a nondiifusing high molecular dye of the indicated formula is, therefore, easily removable from a photographic colloid by washing.

It has been found the polymeric dyes prepared in other ways than described above have the same advantages and serve as well for coloration of photographic. colloids; particularly silver halide emulsions'containing gelatine, or other watersoluble or water-permeable colloids, such as methyl cellulose or cellulose glycolic acid, polymeric vinyl derivatives, and other colloids used for multilayer color photographic materials wherebyin each differently sensitized silver halide layer a differently colored dye is incorporated.

The dyes, according to the invention, are'represented by the same general formula given above; the new dyes may contain identical or unidentical dye units, and every single dye unit itself may contain one or more azo groups. The number of units, n, is determined or undetermined. In order to clarify the objects of the invention, a detailed description and further definitions are given as follows:

1. The dye unit Any low molecular weight azo dye which is capable of being linked to other (identical or .unidentical) azo dyes by a heteronuclear bond is a dye unit according to the definition of the present true disazo dye a becomes two, and in a trisazodye:a" assumes the valueof three. A polymeric pol'yazo dye (a l and n 1 in the general formula) upon reduction gives n(a-1) molecules of the formula,

NHz-Arr-NHz and n-1 molecules of the formula NHzArz-B 'Ar1,NI-I2 I exclusive of the terminal molecules all of which are easily removable from the photographic colloid, independently of the polymeric grade n of the original dye.

2. The combination of dye units The dye units, linked together by a heteronuclear bond are, in the simplest case, identical.- However, they may be different as well. These difierent dye units linked together can be of iden tical or different coloration; one azo-dye unit may be a monoazo dye and the next azo-dye unit may bea polyazo dye. It is, therefore, possible to combine different yellow, magenta, orblue-green azodye units to form yellow, magenta, red, cyan, violet, green or black dyes.

a. The heteronuclear bond The dye units contained in the polymeric dye a e @14 y a Qarboa to carbon linkage or by any bridge formed by substituted carbon atoms or hetero-atoms, such as, for example,ArO-, O-, S, SO2, CO, NHCO--, alkylene, arylene, -O-alkylene-O-, OaryleneO-, E, NH--CONH,

Ar-CO--, SO2NH, -NH-X-NH-, and NHY-NH wherein X is the divalent radical of a dibasic organic acid and Y. is a bivalent hydrocarbon residue. Any redical is suitable provided that it interrupts the conjugation of the chain, and that it does not increase the molecular weight or decrease the solubility of the resulting reduction project to such an extent that it will prevent the removal or dissolution of the product from the photographic layer.

4. substituents within the dye units The dye units may contain one or more solubilizing groups such as, for example, sulphonic or carboxylic acid groups which make them water soluble either in the free acid form or in the form of salts; or they might contain group which facilitate their solubility in organic solvents, or both in water and organic solvents, or in a mixture of water and organic solvents. Such groups are hydroxyalkyl groups, polyhydroxyalkyl groups, hydroxy-amino-alkyl, quaternary amino groups, and many other substituents. According to the invention the solubility properties of the dyes are selected only with respect to the most suitable solvent for a chosen photographic colloid since they have, in spite of their great solubility, no tendency toward diffusion, and, furthermore, after reduction they form low molecular Weight reduction products which can be easily removed from a photographic colloid by washing, or which go into solution already during the reduction of the polymeric azo dye. Up to now it has been considered necessary to use dyes which contained only a minimum number of solubilizing groups; or to increase the molecular weight of soluble dyes byattaching substituents such as long chain fatty acid derivaties, or other high molecular weight substituents which reduce the solubility of the dyes or which prevent the easy or complete removal of the reduction products, thereby affecting the whites of the resulting photographic dye images. Another disadvantage of such methods consists in too low a tinctorial power of the dyes weighted by high molecular substituents so that to reach the necessary dye densities, a too large quantity of dye has to be used.

5. The polymeric grade n It depends on the methods of synthesis chosen if the polymeric grade n is determined or undetermined.

The coupling of a polydiazo compound with a coupling compound having two or more coupling positions yields a polymeric azo dye where n is large but not determined. Another method to synthesize polymeric dyes of large but undetermined molecular size consists in connecting monoazo, disazo, trisazo, or polyazo dyes, which have reactive groups in the terminal groups, with a bivalent reagent to link the single dyes into a polymeric azo dye of a larger molecule.

The synthesis of dyes having a determined molecular size can be performed; i. e., by coupling a diazo or tetrazo compound with a coupling compound which contains an amino group careaching a suitable size of molecule.

equal or similar 'coupling compound. This operation is repeated as'often as necessary to obtain a polymeric azo dye of sufliciently large molecular weight. After each operation a diffusion test is made and a non-diifusing dye results after The number of dye units required to reach a dye stable to diffusion varies with the chemical properties of the coupling compound and also with the properties of the photographic colloids used, and can be easily determined by simple diffusion tests for each dye. The diffusion test may be carried out, for example, in the following manner, i. e., a quantity of colorless 5 to 10 per cent gelatine or other photographic colloid solution is coated on a base such as celluloid film or glass plate and dried. A second coating is placed on top of this clear coating, using the same concentration of colloid to which a solution of the dye has been added in suiflcient quantity to reach the desired dye density. After drying, the material is soaked in water, and the upper layer is removed with a sharp instrument, and the lower clear layer examined for evidence of diffusion. In most cases the material is carried through a sequence of photographic processing baths such as the depable of further diazotation andby diazotizing t the resulting amino-azo dye and coupling with an veloper, fixing bath, dye bleach, etc., and after final washing the dyed layer is removed and the lower clear layer examined for evidence of diffusion.

The polymeric grade n required to render the dye stable towards diffusion is inversely proportional to the number a of azo groups within one azo-dye unit. I have found that the product a n must be greater than two in order to prevent diffusion of the dyes in the processing baths. However, a higher polymeric degree than the minimum degree is preferable and does not adversely affect the solubility and tinctorial power of the dye nor the molecular size of the reduction products of the dye.

The above mentioned general methods are illustrated by the following specific examples. There are, of course, many forms of the invention other than described in these specific examples.

Example 3.9.3 grams of aniline are diazotized and coupled in known manner with 22 grams of l [4 amino phenyl] 5 pyrazolone 3 carbonic acid (Beilstein, Handbuch der Organischen Chemie, 4th ed., supplementary vol. XXV, page 568) in sodium carbonate solution. After completion of the coupling the resulting dye is salted out, filtered off, washed and dissolved in water 6.9 grams of sodium nitrite are added to the dye solution which is then poured into 35 ml. of hydrochloric acid (D=l.19) diluted with ice water. After stirring at a temperature below 6 C. for 1 hour the resulting diazo compound is stirred into a solution of 22 grams of sodium carbonate and 22 grams of 1-[4-amino-phenyl]-5-pyrazolone-3- carbonic acid in 1 liter of water which contains 10% pyridine, and the mixture is kept at a temperature of 8 C. After stirring for an hour, the solution is heated, acidified with hydrochloric acid, and the dye is precipitated, filtered and washed with dilute hydrochloric acid. The dye is again diazotized and coupled'with the same quantity of l [4-amino-phenyl] -5 -pyrazo1one-3- carbonic acid, as described above, and the resulting dye is precipitated, with dilute hydrochloric "'acid. The-dye, when tested for diffusion, shows with most gelatines only a slight diffusion When two further diazotizations and couplings are performed in the same way as described above no ease? I difiusion occurs with the resulting dye. The dye bonate. Hereby y fl azo dye is obtained; is believed to have the following formula: the monoazo dye units of which are connected by coon 7 COOH r =N J=N C N=N- -o \N-C -N=N- o NONH, ownf lm \O(OH) where m stands for either two *or four. Am ethylene bridge.

In the above example the aniline can be replaced with 12.'7 grams of chloro-aniline or 17.3 grams of metanilic acid. Furthermore in any or in all of the couplings the 1-[4-amino-phenyl] -5 pyrazolone-3-carbonic. acid can be replaced by other 'azo couplers, for instance, by S-(p-aminobenzoylamino) phenol-2-sulphonic acid.

Example 4.15 grams of acetyl-p-phenylendie-mine are diazotized and coupled in known manner in sodium carbonate solution with 22 grams of l-[4-amino-phenyl]-5-pyrazolone-3- carbonic acid. The dye is salted out, filtered off, dissolved in water and boiled with a 5% potassium hydroxide solution in order to split off the acetyl group. Thereafter the dye is salted out,

Example 6.34.4 grams of benzidine-2,2-disulfonic acid are tetrazotized and coupled with 53.4 grams of 1.1-[2.2-disulpho-diphenylene- (4.4) l-bis-(5-pyrazolone-3-carbonic acid) (Bellstein, l. c.) in a cold aqueous solution of 10% pyridine. The yellow dye is precipitated with dilute hydrochloric acid solution, filtered off, and washed with alcohol. The dye, neutralized with 16.4 grams of sodium carbonate, forms a yellow solution in water which is ready for addition to a photographic colloid. For color photographic or filter purposes 0.3 to 1 gram of the dye is used per square meter. The photographic layers dyed with this dye are entirely free of diffusion. The probable structure of the dye is COOH 03H SOK filtered 011, and dissolved in a sodium carbonate solution. Phosgene gas is introduced under cooling and stirring, whereby a polymeric azo dye is formed in which the dye units COOH The same dye is obtained by tet'razotizing 24.2 grams of diamino-diphenylurea. and coupling the same in a 20% pyridine solution with 26.8 grams of. carbonyl-bis-l- (4-amino-phenyl) -5-pyrazolone-3-carbonic acid.

Example 5.Instead of reacting the monoazo dye described in the foregoing example with phosgene, other acid chlorides derived from polyvalent acids, such as succinyl chloride, can be used: 33.9 grams of the monoazo dye described in Example 4 are dissolved in anhydrous pyridine, and 15.5 grams of succinyl chloride are'stirred in small portions into the cooled solution. Half an hour after the addition of the chloride is completed, the temperature is raised to 50 C. and kept at this temperature for 1 hour. The dye is finally precipitated by adding, under cooling, dilute hydrochloric acid. After filtering ofi the dye is dissolved in sodium carbonate solution and purified by reprecipitation with acid. A polymeric yellow a'zo dye results in which the monoazo dye units are linked together with groups. A further variation consists in treating the monoazo dye of the Example 4 with 18.8 grams of ethylene bromide at 90 C. under reflux in dioxane in the presence of calcium car- OH NH;

so. slow no. 80m Ho-s [soar no.

chloric acid solution in known manner.

The isomer dye having the sulphonic'acid groups attached in the 3,3'-position (instead of the 2,2- position) of the diphenylene radicals has a simi'-' lar shade.

Example 7.-a. 34.4 grams of benzidine-2,2' disulphonic acid are tetrazotized in dilute hydro- To this tetrazo solution, a solution containing 31.9 grams of H-acid, 8.3 grams of sodium acetate and 6 ml. of acetic acid is added slowly while stirring. The temperature is kept at 5 C. for 2 hours. A bluishred monoazo dye forms. Thereafter about ml. of pyridine are added whereby the bluish-red monoazo dye transforms into a blue-green polymeric dye. After 1 hour the solution is acidified with an excess of hydrochloric acid, and the polymeric blue-green azo dye precipitatesin amorphous form. The liquid is decanted and the precipitate washed with 5% sodium chloride solution. For purification, the dye is dissolved in aqueous sodium carbonate solution, salted out, filtered and Washed'with 5% sodium chloride'sO lution.

b. A dye similar to that described in Example 79. is obtained by the following procedure: 34.4 grams of benzidin'e-2,2-disulphonic acid are tetrazotized in hydrochloric acid solution. To this terraazo solution, a solution containing 63.8 grams of H-acid, 16.6 grams of sodium acetate, and 12 ml. of acetic acid is added in the same way as in Example 72.. After standing for two hours, to this solution which contains a magenta disazo dye, a tetraazo solution prepared with 34.4 grams of benzidine-disulphonic acid and 160. ml. of pyridine is added whereby a blue-green dye is' formed which is isolated and purified as in Example 7a. p

The probable formula of the dye formed in Example a is I 'and the probable formula 01" the dye formed in Example b is:

OH NH;

Ems a dog: H035 aniline-2* sulfonic acid with l-amino-napbthale'ne-7esulfonic acid, diazotizing the resulting The dyes are well soluble in water and their 10 monoazo dye and coupling it with 1-amino-2- gelatine coatings are free of diffusion into adjacent gelatine layers.

Instead of the tetrazotized benzidine -2,2-di- :sulphonic acid in the foregoing examples, a number of other tetrazo compounds may be used with equal success, such as for example; tetrazotized diaminodiphenylsulphone, diaminodiphenylsulphone-sulfonic acid, diaminodiphenylsulphone-disulphonic acid, dianisidine, diaminodiphenylmethane, diaminodibenzyl, diaminobenzophenone, diaminodiphenyl-sulphide, or diaminodiphenyl ether. The aforementioned compounds might contain further substituents such as alkoxy, alkyl, oxyalkyl groups or halogens.

Example 8.-33.1 grams of 3,3-diamino-4,4'- dimethoxy-diphenylmethane chlorohydrate are tetrazotized in known manner and coupled in 5% pyridine solutionwith 107.6 grams of p-amino-benzoyl-H-acid. The diamino disazo dye is precipitated with hydrochloric acid and sodium chloride, filtered off, dissolved in water and tetrazotized in acid solution with 13.8 grams of sodium nitrite and coupled with 107.6 grams of "dyes in each step by dissolving and reprecipitating them. The final product is a magenta hexazo dye which is believed to have the following formula:

NH 0H Bo s The dye has a good solubility in water and is added to a gelatine silver bromide emulsion in a quantity of 0.5 to 1 gram per squaremeter. It

doesv not diffuse into adjacent gelatine layers.

In the above example in place of 3,3-diamino- 4,4-dimethoxy-diphenylmethane many other diamino aryl compounds such as p-diaminodi- ,phenyl ether, 2, 2'-dichlorobenzidine, or diaminodiphenylurea can be used. The p-aminobenzoyl- ,I-I-acid can be substituted in one, two, or all coupling steps with aminoanisolsulfo-H-acid or aminobenzoyl-K-acid. Furthermore, the last coupling can be made with a coupling compound, which is free of diazotizable amino groups, such as p-toluenesulfo-H-acid or dichlorobenzyl-K- acid.

Example 9.'-.-A trisazo dye is made in known manner by couplingdiazotized 4-oxalylaminomethoxynaphthalene 6 sulphonic acid. This dye is then diazotized and coupled in pyridine and ammonia with 2-amino-5-naphthol-7-sulfonic acid. The making of similar trisazo dyes is described in the U. S. Patent No. 1,602,991. The resulting trisazo dye is dissolved, and the oxalyl group is split off with cold 5% sodium hydroxide solution. Thereafter, the dye is salted out, filtered oil, dissolved in a sodium carbonate pyridine 20 solution and treated with phosgene gas. A blue- SOaH 01H formed by a plurality of identical low molecular weight members Ar N= N, wherein Ar stands for a group which has both a coupling position 'and at least one salt-forming substituent and comprises an aromatic radical capable of carrying an azo group, n stands for an integer greater OCH;

than one, said members ArN=N being linked together by the azo group of one member being oofattached to the coupling position of the next member.

2. A photographic material comprising two superposed colloid layers, at least one of the layers being a light sensitive silver halide emuls ion layer comprising a high molecular weight "dye-which is soluble in a substance selected from the group consisting of water and aqueous alkali and which includes the following general structure (ArN=N)n formed by a plurality of identical low molecular 'weight'members Ar-N=N, wherein Ar stands for a group which has bothacoupling position and at least one salt forming substituent and cam comprises an aromatic radical capable of carry ing an .azo group, n stands tor an integer greater than one, said members Ar N=N being linked together by the azo group of one member being attached to the coupling position of the next member. I I

3. A photographic material comprising a lightsensitive silver halide emulsion and a high inolecular weight dye in the presence of said silver halide which dye is soluble in a substance-selected from the group of substances consisting of water and aqueous amau and includes the following general structure formed by a'pluralit'y of identical low molecular weight members AI'N=N, wherein Ar stands for a group which has both a coupling position and at least one salt-forming substituent and "comprises an aromatic radical capable of carrying an azo group, "n stands for an integer greater than one, said members Ar N='N being linked together by the azo group of one member being attached to the coupling position of the next member.

4. A photographic material having a layer comprising a light-sensitive silver halide emulsion and a high'molecular weight dye which is soluble in a substance selected from the group of substances consisting of Water and aqueous alkali and which includes the following general structure formed by a plurality of identical low molecular weight members ArN=N, wherein Ar stands for a group which has :both a coupling position and at least one salt-forming 'substituent and comprises an aromatic radical capable of carrying an azo group ,n stands for an integer greater than one, said members ArN=N being linked together by the azo group of one member being attached to the coupling position of the next member.

, 5. A process for producing a coloredphotographic material comprising at least two superposed colloid layers, at least one of said layers being a light sensitive silver halide layer and at least one of said layers being a colored colloid layer, which comprises coloring the colloid used for the production of said colored colloid layer with a soluble high molecular weight dye which includes the following general structure (--AI--N=N)n formed by a plurality of identical low molecular weight members Ar--N=N, wherein Ar stands tor, a group which has both a coupling position and at least one salt-forming substituent and comprises an aromatic radical capable of carrying an azo group, n stands for aninteger greater than one, said members ArN=N beinglinked together by the azo group of one member being attached to the coupling position of the next formed by a plurality of identical low molecular weight members Ar-N=N, wherein Ar stands for a group which has both a coupling position and at least one salt-forming substituent and comprises an aromatic radical capable of carrying an azo group, "n stands for an integer greater than one, said members ArN=N being linked together by the azo group of one member being attached to the coupling position of the next member. s

- 7. A process for producing a colored photographic image in a photographic material comprising a plurality of colloid layers, at least one of said layers containing a silver image and at least one of said layers being diffusely dyed with a soluble high'molecular weight dye which includes the following general structure (Ar--N N)n formed by a plurality of identical low molecular weight members Ar--N=N, wherein Ar stands for a group Whichhas both a coupling position and at least one salt-forming substituent and comprises an aromatic radical capable of carrying an azo group, n stands for an integer greater than one, said members ArN=N being linked together by the azo group of one member being attached to the coupling position of the next member which comprises treating said material to locally destroy by reducion said dye in the presence of said silver image and washing said material.

8. A process for producing a colored image in colored photographic colloid layer containing a silver image, said layer being diffusely dyed with a soluble high molecular weight dye which includes the following general structure formed by a. plurality of identical low molecular Weight members ArN =N, wherein Ar stands for a group which has both a coupling position and 1 at least one salt-forming substituent and comprises an aromatic radical capable of carrying an azo group, n stands for an integer greater than one, said members Ar -N N being linked together by the azo group of one member being attached to the coupling position "of the next member which comprises treating said material to locally destroy by reduction said dye in the presence of said silver image and washing said material.

9. A process for producing a colored image in a colored photographic colloid layer containing a silver image, said layer being diffusely dyed with a soluble high molecular weight dye which includes the following general structure:

formed by a plurality of identical low molecular weight members A'r- N -N, whereinA'r stands for a group which has both a coupling position and at least one salt -forming substituent and comprises an aromatic radical capable of carrying an azo group "n stands for aninteger greater than one, said members Ar N=N being linked together by the azo group of one member being attached to the coupling position of the next member, which comprises treating said material to locally destroy by reduction said dye in the presence ofsaid silver image and removing the dye reduction products "from said layer by washing.

10. A photographic material comprising at least two superposed colloid layers, at least one of the layers being a light sensitive silver halide emuh 13 Bionlayer and at least one layer comprising a soluble high molecular weight dye which carries at least one solubilizin group and includes the following general structure:

formed by a plurality of low molecular weight members -B (-A11N=N-) aA12 wherein An and Arzstand for a. group comprising a-radical selected from the class consisting of aromatic, heterocyclic and aliphatic radicals, B stands for a heteronuclear bond, n stands for an integer greater than one and a stands for an integer from one to four and the product of a and n is greater than two.

11. A photographic material comprising at least two superposed colloid layers, at least one of the layers being a light sensitive silver halide emulsion layer and at least one layer comprising a soluble high molecular weight dye which carries at least one solubilizing group and includes the following general structure:

formed by a plurality of low molecular weight members wherein AI'l and Alz stand for a group comprising a radical selected from the class consisting of aromatic, heterocyclic and aliphatic radicals capable of carrying an azo group, B stands for a heteronuclear bond, n stands for an integer greater than one and 2. stands for an integer from one to four and the product of a and n is greater than two.

12. A photographic material comprising at least two superposed colloid layers, at least one of the layers being a light sensitive silver halide emulsion layer and at least one layer comprising a soluble high molecular weight dye which carries at least one solubilizing group and includes the following general structure:

formed by a plurality of identical low molecular weight members wherein AI'l and Arz stand for a group comprising a radical selected from the class consisting of aromatic, heterocyclic and aliphatic radicals, B stands for a heteronuclear bond, n stands for an integer greater than one and a stands for an integer from one to four and the product of a and n is greater than two.

13. A photographic material comprising at least two superposed colloid layers, at least one of the layers being a light sensitive silver halide emulsion layer and at least one layer comprising a soluble high molecular weight dye which carries at least one solubilizing group and includes the following general structure:

formed by a plurality of diiierently colored low molecular weight members wherein An and Ari stand for a roup comprising a radical selected from the class consisting of aromatic, heterocyclic and aliphatic radicals, B stands for a heteronuclear bond, n stands for an integer greater thanone and astands for an integer from one tofour; and the product of *a andformed by a plurality of identical low molecular weight members wherein An and Arc stand for a group comprising a radical selected from the class consisting of aromatic, heterocyclic and aliphatic radicals capable of carrying an 2.20 group, B stands for a heteronuclear bond, 11 stands for an integer greater than one and a stands for an integer from one to four and the product of a and n is greater than two.

15. A photographic material comprising at least two superposed colloid layers, at least one: of the layers being a light sensitive silver halide emulsion layer and at least one layer comprising: a soluble high molecular Weight dye which carries" at least one solubilizing group and includes the:

following general structure:

[-B(A1'1-N=N) aAIZ-Jn formed by a plurality ofdifierently colored low' molecular weight members 13 (Al1 N=N) aAI'Z wherein Al'l and An stand for a group compris-- ing a radical selected from the class consisting of aromatic, heterocyclic and aliphatic radicalscapable of carrying an azo group, B stands for a. heteronuclear bond, n stands for an integer greater than one and a stands for an integerfrom one to four and the product of a and n is greater than two.

16. A photographic material comprising at least two superposed colloid layers, at least one: of the layers being a light sensitive silver halide. emulsion layer and at least one layer comprising: a soluble high molecular weight azo dye formed? by a chain which contains at least four ,low' molecular weight members, each carrying at least; one azo group and at least one heteronuclear bond. linking together said members, the number oft said heteronuclear bonds multiplied by the humber of azo groups conjugated with each other giving a product which is greater than two.

17. A photographic material comprising at least two superposed colloid layers, at least one of the layers being a light sensitive silver halide emulsion layer and at least one layer comprising a soluble high molecular weight dye which carries at least one solubilizing group and includes the following general structure:

[B(AI'1N=N)aAI'2-]n formed by a plurality of low molecular weight members -13 Ari--N=N) aAI'2-- wherein An and Ara stand for a group comprising a radical selected from the class consisting of aromatic, heterocyclic and aliphatic radicals capable of carrying an azo group, B stands for a heteronuclear bond which in at least one low molecular weight member of the series. comprises the group -CO-NH-, "n stands for an integer 18 greater than one and 'a-" stands for an integer: from one to four and the product of a and "11 is greater than two.

18. A photographic material comprising at least two superposed colloid layers, at least one of the layers being a light sensitive silver halide emulsion layer and at least one layer comprising a soluble high molecular weight dye which carries at least one solubilizing' group and includes the following general structure:

formed by a plurality of low molecular weight members B(A1:1N=N)aAr2 whereinAn and Arz. standior a group comprisins a radical selectedv from the class consisting of aromatic heterocyclic and. aliphatic; radicals capable of. carrying an azo-group, B stands for a heteronuclear bond which in at least one low molecular Weightmember of the series comprises the group SO2NH, n stands for an integer greater. thanv one and 2. stands for an integer from one to four and the product of a and n is greater than two.

19;. A photographic material comprising at least two superposed colloid. layers, at least one of the, layers being a lightsensi-tivesilver. halide, emulsion layer and atleast one layer comprising a soluble high molecular weight dye which carries at least one solubilizing group and includes the following general structure:

formed by a plurality oflow molecular weight members, 7

B(-Ar1-N=N) aAr2 wherein An and Ar2= stand for agroup comprising' a radical selectedfrom the class consisting of aromatic, heterocyclic and aliphatic radicals capable of carrying an azo group; B stands for a heteronuclear bond which in at least one low molecular weight member of the series comprises the group -NHXNH- wherein X is the divalent radical of a dibasic organic acid, n stands for an integer greater than on'e and a stands for an integer from" one to' four and the product of a and n is greater than two.

20. A photographic material including'a support and a coating on said support, said coating comprising a plurality of discrete portions, at least one of said discrete portionscontaining a light sensitive silver halide emulsion and at least one of said discrete portions containing a soluble mm-difiusing high molecular weight dye which carries at least one solubilizinggroup and includes the following general structure formed by a plurality of low? molecular weight. members B(Ar1N=N )aArz wherein ATI and Arz stand for a group comprising a radical selected from the'class consisting: of aromatic, heterocyclic and aliphatic radicals capable of carryingan-azo group; B stamis for a heteronuclear bond, ni stands for an integer greater than one. and.a stands-for aninteger from: one to four and the product of. a and n is greater than two.

21. Avphotographic materiallcomprising a light sensitive silver halide emulsion and-ahighmolecular weight dyeinthepresence of said silver 1241-- new lide when dye carries at least one solubilieing group and includes the following general struc ture aAT2]n formed by a plurality of low molecular weigh members wherein Ari andiArz stand for a group comprising a radical selected from the class consisting of aromatic, heterocyclicand aliphaticradical'scapable of carrying an azogroup, 3 stands for a hetieronuclear bond, n stands for an integer greater than one. and- "a stands, for an integer from one to four and the product of a and n is greater than two. H

22'. Arphotographie material comprising a light sensitive silver halide emulsion and a high melee-=- ular weight dye in the presence of said silver ha lide which dye carries at least one SOZ'LLbiZiaing group and includes the following general struc-- ture formed by" a plurality of low molecular weight members wherein AM. and A12 standfor a group comprising a radical selected from the class: consisting of aromatic, heterocyclic and aliphatic radicals capable of carrying; an azo group;.B' stands tor a; heteronuclear bond which in at least one lourmolecular weight member of the series comprises: the group --C' ONH-, n stands for an: integer greater than one and a standsjoranintege-r from one to four and: the product of a and "n. is greater than; two.

23-; A photographicmaterial comprisinaalight sensitive; silver halidee'mulsion and a high melee-'- ular weight dye: in the pres'ence of said si'luer ha--' lide' dye carries: at" least one solubilizinggroup and includes: the ,tollowing general. struc ture formed by a plurality of low molecularweig'ht members wherein-Ariana A'rz stands-for a group compris ing a radical selected from the classconsistin'g of aromatic, heterocyclic' and aliphatic radicals c'apableoi-carrying in ace group; nuanceora heteronucleanbond which in at least one lowmo lecular weight member of the series comprises the group'SOzNH, stands'for an integer greater than one and a standsfor an integer from one to fouran-dth'e' product of a. and" is greater than two.

24'. A photographic material comprisinga light sensitive silver halide" emulsion and a" mo; lecular weight dye in the presence of said silver halide which dye carries at least one solubilizing group and'includes the following general structure. 1 V

17 of aromatic, heterocyclic and aliphatic radicals capable of carrying an azo group, B stands for a heteronuclear bond which in at least one low molecular weight member of the series comprises i the group -NH-XNH- wherein X is the divalent radical of a dibasic organic acid, n

stands for an integer greater than one and a stands for an integer from one to four and the product of a and "n is greater than two.

BELA GASPAR.

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

Gaspar Oct. 31, 1939 Number Number Name Date Gaspar Apr. 28, 1942 Chechak June 16, 1942 Seymour June 16, 1942 Carroll et a1. Sept. 8, 1942 Carroll et a1 Sept. 8, 1942 .Woodward Feb. 2 1944 Allen et a1 Apr. 11, 1944 FOREIGN PATENTS Country Date Great Britain Apr. 30, 1925 France Dec. 28, 1937 Great Britain Nov. 30, 1938 Switzerland Aug. 1,1939 Great Britain Nov. 12, 1941 Great Britain Nov. 10, 1942 Great Britain Feb. 25, 1943 Great Britain Feb. 25, 1943