US3806347A - Silver halide photographic materials containing anionic couplers or scavengers - Google Patents

Abstract

A COLOR PHOTOGRAPHIC SILVER HALIDE SENSITIVE MATERIAL PREPARED BY UTILIZING A NOVEL METHOD OF INTRODUCING, FINELY DISPERSED AND FAST-TO-DIFFUSION, COLOR COUPLERS OR SCAVENGERS FOR COLOR-FORMING DEVELOPMENT INTO PROTECTIVE COLLOID BINDERS OF EMULSION LAYER, INTER LAYERS OR OTHER LAYERS CONSTITUTING A MULTI-LAYERED COLOR PHOTOGRAPHIC MATERIAL. THE METHOD COMPRISES A PROCEDURE FOR COMPLEXING SAID COUPLERS OR SCAVENGERS WITH FINELY DIVIDED PARTICLES OF A COACERVATE, WHICH HAS PREVIOUSLY BEEN PREPARED BY REACTING IN AN AQUEOUS MEDIUM AT LEAST ONE OF POLYMERIC ORGANIC HYDROPHILIC CATIONIC COMPOUNDS HAVING CATIONIC NITROGEN-CONTAINING GROUPS IN THEIR MOLECULES WITH AT LEAST ONE OF PHTHALIC ACID DERIVATIVES OF GELATIN POLYVINYL ALCOHOL AND STARCH.

Description

United States Patent Oflice 3,806,347 Patented Apr. 23, 1974 Int. Cl. G03 c1/40, 7/00 US. Cl. 96-100 Claims ABSTRACT OF THE DISCLOSURE A color photographic silver halide sensitive material prepared by utilizing a novel method of introducing, finely dispersed and fast-to-diffusion, color couplers or scavengers for color-forming development into protective colloid binders of emulsion layers, inter layers or other layers constituting a multi-layered color photographic material. The method comprises a procedure for complexing said couplers or scavengers with finely divided particles of a coacervate, which has previously been prepared by reacting in an aqueous medium at least one of polymeric organic hydrophilic cationic compounds having cationic nitrogen-containing groups in their molecules with at least one of phthalic acid derivatives of gelatin polyvinyl alcohol and starch.

BACKGROUND OF THE INVENTION This invention relates to an improvement of the method of introducing anionic color couplers for color-forming development, or scavengers similar in chemical structure to said color couplers, into the protective colloid binders of superposed emulsion layers, inter-layers or other layers of a multi-layered sensitive material. As one of the methods for introducing color couplers, fast-to-dilfusion, into the emulsion layers of a photographic material, there has heretofore been known a method of "Agfa type or Fisher type. The method utilized in the present invention is considered to be an improvement of the method of this type.

The above-mentioned method, which is the base for the method utilized in the present invention, is derived from the invention disclosed in US. Pat. 2,186,849 (1940) assigned to Agfa Ansco Corp., Binghamton, NY. According to said method, long chain hydrocarbons having 11 to 18 carbon atoms are introduced as so-called ballast groups into the molecules of color couplers, and carboxylic acid or sulfonic acid groups are further introduced in order to provide water solubility. Principal drawbacks of said method are such that the color coupler molecules are sparingly soluble in an aqueous medium and the marked increase of viscosity of an aqueous solution of hydrophilic colloid binders such as gelatin, polyvinyl alcohol and the like, when they are admixed in the solution, make the coating operation difficult; the color couplers tends to form micelles to deteriorate the color tone of the resulting color image and the developed silver image tends to be occulded in the formed dye to make the bleaching operation difficult. Among these, the most serious drawback is the extraordinary increase in viscosity of the aqueous binder solutions due to interaction of the color coupler molecules with the binder molecules. The method utilized in the present invention is an improvement which overcomes this drawback. 'Further, there are substances which, like color couplers, couple in color forming developing with the oxidation intermediates of color developing agents, but give dyes which are so unstable as to be immediately decomposed or give leuco dyes which are so stable as not to permit the formation of real dyes. Alternatively, there are also some substances which bring about oxidation-reduction reactions with oxidation intermediates of color developing agent to reduce the intermediate so as not to bring about any coupling. These substances are frequently adopted as scavengers for oxidation intermediates of color developing agents, which diffuse away from one emulsion layer and the scavengers are incorporated into an interlayer between the said two emulsion layers, thereby preventing the color-mixing. These scavengers are similar in chemical structure to the color couplers so they may also be made fast-to-dilfusion by introducing ballast groups and anionic groups and incorporating into inter-layers of a multi-layered color photographic material. In this case also, the improved method utilized in the present invention is effective, like in the viscosity increase of coating solutions of inter-layers due to interaction between the scavengers and the binder molecules.

SUMMARY OF TH-E INVENTION The method utlized in the present invention aims to overcome various drawbacks encountered at the time of introduction of Agfa-type couplers, or scavengers similar in structure thereto, into the layers of a multilayered color photographic material, as mentioned above. The greatest drawback of extraordinary increase in viscosity of binder solutions, and other drawbacks may be overcome to a certain extent by suitable selection of couplers, scavengers or binders. According to the method utilized in the present invention, however, all the above-mentioned drawbacks can be overcome almost completely.

The gist of the method employed in the present invention is to attain the complete dispersion of anionic color couplers, or anionic scavenger similar in structure thereto, and to prevent the viscosity increase due to interaction of the couplers or scavengers with binders; and also to prevent the micelle formation of couplers; in the hinder or occulsion of the developed silver grains in the dyes formed around them, utilizing a dispersion system of the coupler or scavenger, by complexing them with the coacervate particles formed by the interaction of anionic polymers having phthalic acid residue with a cationic polymer in an aqueous medium.

The formation of coacervate particles suitable in size is facilitated by selection of cationic and anionic polymers, and, by means of excess cation groups in the resulting coacervate particles, anionic coupler or scavenger molecules are attracted onto the surface of said coacervate particles to form a complex, thereby firmly adsorbing each molecule onto the particle surface. Since the particle surface is sufiiciently broad, the couplers or scavengers are completely dispersed, so that even when the couplers or scavengers are added in the dispersed form to the coating solutions of emulsion layers or inter-layers and mixed with hydrophilic colloid binders such as gelatin, polyacrylamide and the like, constituting said layers, no agglomeration of said coacervate particles takes place any more. Accordingly, not only the couplers are prevented from agglomeration or micelle formation but also the degree of interaction of couplers or scavengers with binders remains quite low, with the result that the viscosity increase of coating solutions is markedly lowered.

Thus, the present invention provides an improved method of preparing multi-layered color photographic material, in which couplers have been introduced into the emulsion layers or contiguous layers and, if necessary, scavengers have been introduced into also emulsion layers or inter-layers between emulsion layers.

3 DETAILED DESCRIPTION OF THE INVENTION In the present invention, the cationic polymer used in the aforesaid case is a polymeric organic hydrophilic compound having a cationic nitrogen-containing radical including various aliphatic amines, aromatic amines or other organic bases such as pyridine, morpholine, piperazine and guanidine, which may have wholly or partly been quaternarized.

'Iypical examples of such compound are as follows:

(I) Poly(2-vinylpyridine) (II) Poly(4-vinylpyridinium methyl-p-toluenesulfonate) (III) Poly(4-vinylbenzyl-trimethylammonium chloride) (IV) Poly(4-vinylbenzyl-triethanolammonium chloride) (V) Poly(4-vinylbenzyl-methylmorpholium chloride) (VI) Poly(4-vinylbenzyl-dimethylcyclohexylammonium chloride) (VII) Poly(methacryl-dimethylamino-ethanol ester benzyl chloride) (VHI) Acetic acid salt of partially aminoguanidized poly- (vinylethylketone) (IX) Aminoguanidized dialdehyde-starch.

Structural formulas of these compounds are schematically shown below.

CH CHz-CHg 112-15 -436 CH; 01 $11! rn II C QH, I

CH: o-oznr-z w-ona VII l fizfl (VII JLHaO Heal.

(IX) HO OH l l 11TH 1 m 43-Njfi'a (E-NH: ILIH 011 H 11 (The case of gelatin) --CH;CHCHr-CHCH -OH-- HO OH H (The case of polyvinylalcohol) CH-Cfi OH 5H (The case of starch) Accordingly, every one of the above-mentioned 3 kinds of polymers shows an anionic property due to many carboxylic acid groups, and forms a complex with the aforesaid cationic polymer when brought into contact with said polymer in an aqueous medium, not only at an acidic pH but also at a pH within a wide range. Any dibasic acid other than phthalic acid can be used to form similar anionic polymer as well. And the anionic polymer also can form a complex when brought into contact with the aforesaid cationic polymers in an aqueous solvent, but does not always bring about coacervation because of the fact that cationic polymers used in the invention are markedly high in hydrophilic property. That is, even when phase separation takes place, the solution is merely separated into 2 phases, and generally no coacervate in the form of oily drops suitable in size can be formed. In this respect, the phthalic acid derivative is specific. This anionic polymer is made hydrophobic to a suitable extent when ortho-substituted benzene nuclei are arranged in large numbers in the molecular chain, as seen in the formulas shown above. It is therefore considered that the balance of hydrophilic and hydrophobic properties of the complex is suitably controlled to the hydrophobic side, and thus the phthalic acid derivative can bring about phase separation in an aqueous medium to form a dispersion of complex agglomerate in the form of oily droplets suitable in size.

Further, thus formed coacervate particles are also specific and they are extremely rich in number of nitrogen-containing radicals which impart cationic property to the cationic polymer. In the coacervate particles, therefore, large numbers of excess cationic groups have been left without being sufiiciently neutralized with the anionic groups, so that the molecules of anionic couplers, or anionic scavengers similar in structure thereto, can be complexed with said cationic groups, in the coacervate particles as mentioned previously.

Due to formation of the complex, however, the actions of hydrophilic groups in said two polymers are partly lost, with the result that the coacervate becomes considerably unstable. In the case of higher concentration, the coacervation cannot be successfully carried out, like the in the case of the known coacervate prepared from gelatin and gum arabic, and the resulting coacervate tends to agglomerate when an anionic coupler solution is added thereto. However, when the operation is effected in a dilute aqueous solution of a non-ionic Water-soluble polymer such as gelatin, polyvinyl alcohol, polyacrylamide, hydroxyethyl cellulose or hydroxypropyl starch, a coacervate is formed quite easily even in higher concentration of the solution. Moreover, the particle sizes of the coacervate are usually fine enough and are extremely stable. Even if a solution of an anionic coupler or scavenger is added to the dispersion of said coacervate particles to adsorb the molecules thereof onto the surfaces of said coacervate particles, the coacervates are usually sufliciently stable and do not agglomerate at all.

Thus obtained coacervate particles are extremely fine and cannot be confirmed without an optical microscope. Ordinarily, the diameter of coacervate particles are ranging from about 1 to p, and when the particles are cast into a thin layer on film and dried, the film is substantially transparent. Even when these particles are complexed with the anionic couplers used in the present invention and changed into dyes, the particles cannot be confirmed by the naked eyes and appear to have been colored uniformly.

Processes for preparation of the above-mentioned phthalic acid derivatives and the degree of substitution of phthalic acid are mentioned below. A process for preparation of a phthalic acid derivative has been well known from old times according to US. Pat. 2,525,753 (1950) or the like, and is carried out by reacting 100 parts of gelatin with 7 parts of phthalic anhydride. According to the above mentioned process, all the reactive e-amino groups of the gelatin have been substituted substantially completely and, even if the degree of substitution is of such an extent, a phthalic acid derivative suitable for the purpose can be obtained due to the hydrophobic or lipophilic property of the gelatin itself. In the case of polyvinyl alcohol, which is high in itself hydrophilic property, a phthalic acid derivative having a substitution degree of about 50%, is preferable'which is obtained by reacting 100 parts of polyvinyl alcohol with more than 300 parts of phthalic anhydride correspond to the substitution of, in average, one OH group in two vinyl alcohol units with phthalic acid. The derivative can easily be synthesized, like in the case of phthalic acid ester of cellulose, according to an ordinary procedure of reacting polyvinyl alcohol with phthalic anhydride in glacial acetic acid in the presence of anhydrous sodium acetate as a catalyst. In the case of starch also, the similar process as above may be utilized. However, the resulting phthalic acid derivative tends to be colored, so the present inventors prefer a special process which leads to a colorless product of about 33% substitution. As a starting material a glucose polymer relatively low in molecular weight and less in branch such as amylose, soluble starch or dextrin, is preferred in the process and reacting parts of the starting material with about parts of phthalic anhydride at room temperature in a solvent such as formamide or dimethyl sulfoxide in the presence of anhydrous sodium acetate or potassium carbonate as a catalyst, the resulting mono-ester has in average one phthalic acid residue per one glucose unit in the molecule and is free from coloration and has relatively lower viscosity and is in suitable balance of hydrophobic and hydrophilic properties, and thus is preferable for the intended purpose. Further, starch derivatives such as hydroxypropyl-starch and hydroxyethyl-starch, which are easily soluble in cold water, and low in degree of denaturation are also preferable as the starting materials.

It is self-evident that mixed derivatives with other dibasic acids and/or mono-basic acids are also usable for the intended purpose. For example, mixed derivatives with maleic acid or acetic acid are useful. Particularly, the combination use of maleic acid, which itself has crosslinking and hardening or curing actions due to the presence of double bonds, results in such advantages that no hardening agent is required and the resulting coacervate particles are enhanced in stability.

As the couplers or scavengers used in the method of the present invention, anionic couplers or scavengers similar in structure to said couplers which have been used in the conventional Agfa-type color sensitive mate rial, may be used as they are. However, non-diffusing effect can be attained even if the number of carbon atoms of ballast groups, which have been introduced into the coupler molecules in order to attain non-diffusing effect, is made considerably smaller. For example, homologues of couplers, which have not been able to display sufficient non-diffusing property unless a hexadecyl group is introduced therein, can sufficiently exhibit non-diffusing property by introduction of even a decyl group. Further, depending on the molecular structures of couplers, there are some cases where the introduction of 2 octyl groups having 8 carbon atoms is preferable or the introduction of diphenyl group or phenylphenol group is more effective than the introduction of long chain alkyl groups. However, the effects of shapes and molecular weights of said ballast groups vary depending on the structures of other portions of the molecule and on the properties of coacervate particles which form a complex. Accordingly, the number of carbon atoms of said ballast groups cannot be strictly limited, like in the case of the conventional Agfa-type fast-to-ditfusion couplers. However, the number of carbon atoms is in the range which can be easily inferred from the knowledge concerning the known couplers. Thus, in the present invention wellknown couplers which have been prepared so far in large quantities or couplers which can easily be prepared according to the similar method for the known couplers, can advantageously be utilized, It is also attractive that the present invention has extensive accommodations in applications.

The scavengers similar in structure to the couplers are explained in detail below. As mentioned previously, substances, which originally are couplers but give dyes that are immediately decomposed, are ordinarily anionic, but have rarely been known except such specific diphenyl-dihydrazone derivatives as shown below.

ia |1 -CHa 69 IE 1% N H I I I NH NH l Couple I i l l 02H; C 18 Na 0a S (Diphenyl- (Oxidation dihydraxone type intermediate Scavenger) of developing agent) lB 87 H8 1aHa1 -CI-Ia ll ll II r N f N H ITIH Deeompose Na 03 S 02H! 0 1H! S OaNB (Azomethine- (Monohydrazone; magenta dye) without color) As the examples of so-called "white coupler type scavengers, which are similar in structure to the couplers and couple like the couplers but initially give colorless leuco bases that are too stable to permit the formation of real dyes even by further oxidation, there are shown two compounds below.

In addition thereto, hydroquinone, p-aminophenol, resorcinol and many derivatives of phenols have been well known as substances which inactive oxidation intermediates of color developing agents through an oxidation reduction reactions with said intermediates, and most of them are nonionic. In the present invention, anionic compounds prepared by introducing sulfonic acid or carboxylic radicals into the above-mentioned phenol derivatives are used. Examples of the said compounds include 2- dodecyl-hydroquinone-S-sulfonic acid (Na salt), 2,5-dioctyl-hydroquinone-3-sultonic acid, 2,4-dioctylphenol-6- carboxylic acid and 4-decyl-l,3-resorcinol-6-sulfonic acid.

Throughout the specification, the hydrophilic colloid binders for forming main bodies of photographic layers are gelatin, casein, starch, gum arabic, hydroxyethyl cellulose, carboxymethyl-starch, polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinyl pyrrolidone, vinylbined with hardeners, lost their original water-solubility and rather become water repellent are also included as hydrophilic colloid binders, since they retain properties of swelling by absorption of water.

The present invention is illustrated in further detail below with reference to examples, but it is needless to say that the scope of the invention is not limited to the examples.

EXAMPLE 1 To this solution is gradually added at 50 C. in the form of a fine stream a solution of 1.5 g. of poly(methacryldimethylamino ethanol ester benzyl chloride salt) (the previously mentioned Compound VII) in 30 ml. of Water to form a stable suspension containing coacervate particles of less than 1,u in diameter. The suspension is charged with 6 ml. of a 10% formaldehyde solution and then stirred at 50 C. for 1 hour.

Thus prepared coacervate dispersion (about ml.) is thoroughly mixed with 50 ml. of a 4% solution of a magenta color coupler having the formula shown below (this solution is formed by dissolving the coupler in water using a minimum amount of N-NaOH solution).

The resulting mixture is added to 300 ml. of a green color-sensitized silver chloride emulsion prepared by use of 10 g. of silver nitrate and 30 g. of gelatin, whereby an emulsion preferable for forming a green-sensitive emulsion layer of ordinary color paper can be obtained. The mixture is coated on a baryta paper at the coating weight of about 100 g./rn. whereby a monochrome color paper which gives magenta image is obtained. This color paper can be developed in entirely the same manner as in the case of a multi-layered color paper (refer to Example 3).

EXAMPLE 2 The coacervate dispersion (about 100 ml.) prepared in Example 1 is thoroughly mixed with 60 ml. of a 3% solution of a cyan color coupler having the formula shown below (this solution is formed by dissolving the coupler in water using a minimum amount of N-NaOH and a small amount of methanol).

The resulting mixture is added to 300 ml. of a redsensitive silver chloride emulsion prepared by use of 10 g. of silver nitrate and 30 g. of gelatin, whereby an emulsion preferable for forming a red-sensitive emulsion layer of color paper can be obtained. The mixture is coated on a baryta paper, like in Example 1, whereby a cyan color-forming monochrome color paper is obtained.

EXAMP' IJE 3 The coacervate dispersion (about 100 ml.) prepared in Example 1 is thoroughly mixed with 40 ml. of a 10% solution of a yellow color coupler having the general formula shown below (this solution is formed by dissolving the coupler in methanol using minimum amounts of NaOH and water).

The resulting mixture is added to 300 ml. of a silver chloro'bromide emulsion prepared by use of 10 g. of silver nitrate and 35 g. of gelatin. This emulsion is coated at the coating weight about 100 g./m. on the surface of a so-called RC (resin-coated) photographic paper, which has been prepared by coating a thin film of white opaque polyethylene on surface side and a thin film of colorless polyethylene on back side of a base paper, to form a bluesensitive emulsion layer on the photographic paper. Separately, 100 ml. of the coacervate dispersion of Example 1 is mixed with a solution of 1.5 g. of a scavenger having the formula shown below in 50 ml. of methanol, thereby adsorbing the scavenger fast-to-dilfusion onto the coacervate particles, like in the case of the coupler.

I OH

The resulting mixture is coated on the aforesaid emulsion layer at the coating weight of about 60 g./m. and then dried to form an inter-layer. On thus formed inter-layer are further coated in this order about 100 g./m. of the magenta color-forming green-sensitive emulsion layer as in Example 1 and about 60 g./m. of the same inter-layer as mentioned above. Then followed by a coating of about 100 g./m. of the cyan color-forming red-sensitive emulsion. On the other hand, the coacervate dispersion (100 ml.) of Example 1 is charged with a dispersion of 2 g. of a brightening agent having the formula,

S Na

soaNa in 50 ml. of water to adsorb the brightening agent onto the coacervate particles, and then mixed with 300 ml. of a gelatin solution. The resulting mixture is finally coated on the aforesaid multi-layered emulsion layer at the coating weight of about 100 g./m. to form an overlayer. A multi-layered color paper is obtained.

The color paper is preferable for preparing a color print from a color negative. After exposing from a suitable color negative, the color paper is developed (25 C., 4 minutes), stop-fixed (25 C., 4 minutes), water-washed (room temperature, 1 minute), bleach-fixed (25 C., 4 minutes), water-washed (1 minute) and stabilized (25 C., 3 minutes), using the solutions mentioned below, and then dried.

Color-forming developer: G. Hydroxyethyl-ethylaminoaniline sulfate 7.5 Hydroxylamine 4.0 Sodium carbonate (monohydrate) 70.0 Potassium bromide 1.0 Anhydrous sodium sulfite 3.0 Sodium hexametaphosphate 2.0

Water to make 1.0 liter.

Stop-fixer: G. Sodium thiosulfate (pentahydrate) 220 Potassium metabisulfite 15.0 Anhydrous sodium acetate 23.0 Boric acid 9.0 Potassium alum 15 .0 Water to make 1.0 liter.

Bleach-fixer:

Ethylenediamine tetraacetic acid 42.0 Sodium hydroxide 20.0 Ferric chloride (hexahydrate) 26.0 Sodium thiosulfate (pentahydrate) 200.0 Anhydrous sodium sulfite 10.0 Water to make 1.0 liter.

Stabilizer:

Sodium acetate (trihydrate) Potassium alum 30 Formalin (35-40%) 50 Water to make 1.0 liter.

EXAMPLE 4 100 grams of a polyvinyl alcohol having a polymerization degree of about 500 is dispersed in 1 liter of glacial acetic acid in a three-necked flask equipped with a silica tube. To the resulting dispersion are added 250 g. of phthalic anhydride, 100 g. of maleic anhydride and 75 g. of anhydrous sodium acetate, and the resulting mixture is reacted with stirring at C. for 10 hours. Subsequently, the reaction light is poured into 8 liters of acetone quently, the reaction liquid is poured into 8 liters of acetone to deposit a precipitate, which is then recovered by filtration, washed with acetone and dried to obtain 450 g. of a pure white powder. Although the accurate measurement of esterification degree is difl'lcult, it is inferred that about 50% of hydroxyl radicals in the molecules are changed to phthalic monoester and about 10% of hydroxy radicals are changed to maleic monoester.

Thus obtained powder is water-insoluble at an acid pH, but becomes water-soluble when neutralized with alkali. Accordingly, 5 g. of said powder is made weakly alkaline and dissolved in ml. of slightly alkaline water, and the resulting solution is adjusted to pH 6.5. This solution is mixed with 100 ml. of a separately prepared 0.5% solution of polyvinyl alcohol (polymerizaiton degree 1,000, saponification degree 95%). Into the mixture is poured with heating at 50 C. and with vigorous stirring "100 ml. of a separately prepared 5% aqueous solution (room temperature) of poly-2-vinylpyridine (I) acidified with acetic acid (pH 3.0), whereby a dispersion of coacervate particles of 2 to 3p. in particle size are immediately formed. The dispersion is heated at 50 C. for 10 hours to proceed the cross-linking in the coacervate particles by means of maleic acid residue, and harden the particles sufiiciently. The liquid (300 ml. in total amount) is charged with 15 g. of gelatin, and the resulting coacervate dispersion is cooled and stored in a refrigerator and the dispersion can be used any time as occasion demands, because the cross-linking is limited only within the coacervate particles and does not extend into the whole dispersion.

When the operation of Example 3 is repeated, using 100 ml. of the thus prepared coacervate dispersion in place of 100 ml. of the coacervate dispersion used in each of Examples 1, 2 and 3, the similar color paper as in Example 3 can be prepared.

EXAMPLE 5 To 100 ml. of the coacervate dispersion of Example 4 is added 100 ml. of a 2% solution of a cyan color-forming orange coupler having the formula shown below (this solution is formed by dissolving the coupler in a 1:1 mixture of methanol and water using a minimum amount of NaOH) to adsorb the coupler onto the coacervate particles by formation of a complex.

I C nHza III OzH The resulting yellow liquid is diluted with an equal amount (200 ml.) of a gelatin solution, and coated on a transparent film base in a proportion of about 150 g./m. followed by drying, to prepare a color-forming film. This film is not a sensitized material but can be used to give a color image having two colors of cyan and orange suitable for advertisement and the like purposes, in combination with a silver halide sensitized material.

At first the color-forming film thus prepared is dipped in color-forming developer of Example 3 to absorb sufficient amount of the developer in the film. Then in a dark room, a commercially available low sensitive paper or direct positive paper is exposed by reflex-copying to form thereon a latent image of a suitable letter or drawing (assuming as a black letter or line on a white background). The sensitized paper bearing the latent image of said letter or line is immersed into the above-mentioned color-forming developer and superposed in register with the aforesaid color-forming film which has absorbed the developer. The resulting composite is slightly squeezed and then pressed for 3 minutes on a hot plate at 30 C. In the treatment some of the oxidation products of the developer which are formed usually at the exposed area of the sensitized material locally diffuses from the sensitized material to the color-forming film facing thereto, a cyan image is formed at the image area facing exposed area according to the reaction shown below, and unreacted orange coupler remains at the non-image area facing unexposed area of the ordinary sensitized materials.

69 OH T 121125 N H C O NH i If OaNa /N\ l OCH3 CgHs CzHQQH (Cyan color-forming orange coupler) f!) H 0 -11111 @j C o NH 1? OaNa C 2115 C 2H4 0 H ya age) Accordingly, when an ordinary sensitized paper is used, I

a cyan letter or line with an orange background is formed, while when a direct positive paper is used, an orange letter or line with a cyan background is formed. Thus prepared copy can be dried after brief rinse with water, and does not require to such time-taking and troublesome treatments as fixing, bleaching or washing. Moreover, the copy is clear in color and hence is promising as an advertise- 12 ment plate or the like display to be illuminated from the back.

EXAMPLE 6 A mixture comprising 50 g. of a commercially available soluble starch and 68 g. of phthalic anhydride is reacted at slightly elevated temperature below 60 C. for 1 hour in 200 ml. of formamide in the presence of 37.5 g. of anhydrous sodium acetate to obtain a phthalic monoester of starch. Thus obtained monoester is precipitated in 1.2 liters of acetone and then washed with a mixture of methanol and acetone to obtain about 87 g. of said monoester as a white powder (about 70% of the carboxylic acid groups are sodium salts). The degree of substitution thereof is 35% (in average 1.05 phthalic acid residue per unit ofglucose) 3 grams of this monoester and 0.4 g. of gelatin are dissolved in 100 ml. of water, and resulting solution is adjusted to pH 6.5 and heated to 50 C.

Separately, an aqueous solution of aminoguanidized dialdehyde starch is prepared. Since a commercially available aminoguanidized dialdehyde starch is low in degree of aminoguanidation (about 5%), the aqueous solution of said starch is prepared by dispersing a commercially available dialdehyde starch (Sumstar-ISO produced by Miles Laboratories Inc.; oxidation degree about 50 in 300 ml. of water, adding to the resulting dispersion a solution at pH 2 of 45 g. of aminoguanidine hydrochloride in 450 ml. of Water, and then reacting the resulting mixture at room temperature for 20 hours. Thus prepared solution is filtered, and the resultant cake is washed with water and then with methanol, and dried at below 40 C. to obtain an aminoguanidized dialdehyde stach as a white powder in which about 50% of the total aldehyde groups have been aminoguanidized. This derivative of starch is particularly excellent in its property to make a coacervate with an anionic substance. 2.5 grams of this starch is dissolved at an elevated temperature in 100 ml. of water, and the resulting solution is adjusted to pH 6.5 and then cooled to room temperature. Thus prepared aminoguanidized dialdehyde starch solution (total amount 200 ml.) is poured into the previously prepared phthalic monoester solution in gelatin with vigorous stirring at 40 C., whereby coacervate particles are formed. After confirming the formation of coacervate particles with a microscope, the coacervate dispersion is heated at C. for 2 hours to cure the coacervate particles by reacting the aldehyde groups within the coacervate. Subsequently, 10 g. of gelatin is added to the dispersion, and the finished coacervate dispersion thus formed is stored after cooling and gelation.

This coacervate dispersion can also form a complex with an anionic color coupler or scavenger, like in the case of the coacervate dispersion of Example 1 or 4, and the resulting dispersion may be incorporated into photosensitive silver halide emulsion layers or inter-layers to prepare a multi-layered color photographic material identical with or similar to that mentioned in Example 3. Alternatively, the dispersion may be used for preparing nonsensitive color material as mentioned in Example 5.

EXAMPLE 7 This example shows a case of a reversal material which utilizes a so-called silver complex diffusion transfer system to a multi-layered color film. According to this system, a color slide can be obtained by direct camera-exposure.

A scavenger stock solution is prepared by mixing and complexing 500 ml. of the coacervate dispersion obtained in Example 6 with 250 ml. of a 4% solution of 2,5-dioctyl-hydroquinone-3-sulfonic acid (Na salt). On a transparent film base, the first layer of the composite multi-layer color film is applied at the coating weight of about g./m. of a mixture comprising 300 ml. of a red-sensitized high speed silver iodobromide emulsion and ml. of the above-mentioned scavenger stock solution is coated to form a first layer. On this layer the second layer is applied at the coating weight of about 80 g./m.

of a mixture prepared from 160 ml. of the coacervate dispersion of Example 6, in which a cyan coupler has been dispersed beforehand in the form a complex, as in Example 1, and 300 ml. of a reduction-nuclei solution of the composition shown below.

Reduction-nuclei solution:

Gelatin g 20 Polyvinyl alcohol g 20 Vinylmethylether-maleic anhydride copolymer g 10 Colloidal dispersion of cadmium sulfide (1%) ml 15 Water to make 1 liter.

(The solution is adjusted to pH 6.0 by addition of a small amount of NaOH.)

On the second layer the third layer is applied by coating thereon about 60 g./m. of a mixture from 300 ml. of the above-mentioned reduction-nuclei solution with 150 ml. of the aforesaid scavenger stock solution, and on the third layer the fourth layer is applied by coating thereon about 100 g./m. of a mixture comprising a greensensitized high speed silver iodobromide emulsion and the scavenger stock solution. On the fourth layer the fifth layer is further applied by coating thereon about 80 g./ m? of a mixture comprising 300 ml. of the reductionnuclei solution and 160 ml. of the coacervate dispersion complexed with 2 g. of a magenta color-forming yellow coupler of the following structural formula:

This yellow coupler acts as a filter layer, and not only cuts the intrinsic sensitivities to the ultraviolet radiation of the lower two layers, i.e. redand green-sensitive emulsion layers, but also acts as a coupler to form a magenta image. However, unreacted yellow coupler has a property to lose yellow color during the treatment after development. On said fifth layer the sixth layer is applied by coating thereon about 60 g./m. of the same mixture as used for formation of the third layer, and on the sixth layer the seventh layer is applied by coating thereon about 100 g./m. of a mixture comprising 150 ml. of the scavenger stock solution and 300 ml. of a blue-sensitive, unsensitized high speed silver iodobromide solution. On the seventh layer is finally applied the upper-most layer (eighth layer) by coating thereon a mixture comprising 300 ml. of the reduction-nuclei solution and 150 ml. of the coacervate dispersion of Example 6, complexed with 4 g. of the yellow color coupler of Example 3. After drying, a composite multi-layered color film is finally ob tained.

After exposure, the color film is treated at 25 C. for 5 minutes with the following developer.

Water to make 1.0 liter.

Thereafter, the developed film is subjected to the same stop-fixing, bleach-fixing and stabilizing treatments as in Example 3, whereby a transparent positive image for color slide can be obtained immediately.

What is claimed is:

1. A color photographic material comprising silver halide emulsion layers, interlayers, or, overlayer and also comprising anionic color couplers for color-forming development, finely dispersed and made fast-to-diifusion in protective colloid binder of emulsion layers or contiguous layers thereto by a complexing procedure of said couplers with finely-divided particles of the coacervate which is prepared beforehand by reacting at least one of polymeric organic hydrophilic cationic compounds having cationic nitrogen-containing groups in their molecule, with at least one of phthalic acid derivatives of gelatin, polyvinyl alcohol and starch in an aqueous medium.

2. A color photographic material according to claim 1 wherein the coacervate has been prepared in the presence of a non-ionic water-soluble polymer.

3. A color photographic material comprising silver halide emulsion layers, interlayers, or overlayer and also comprising anionic scavengers for color-forming development, finely dispersed and made fast-to-dilfusion in protective colloid binder of interlayers or emulsion layers by a complexing procedure of said scavengers with finelydivided particles of the coacervate which is prepared beforehand by reacting at least one of polymeric organic hydrophilic cationic compounds having cationic nitrogencontaining groups in their molecule, with at least one of phthalic acid derivatives of gelatin, polyvinyl alcohol and starch in an aqueous medium, the anionic scavengers being phenols having a sulfonic acid or carboxylic acid group attached to the phenol molecule.

4. A color photographic material comprising silver halide emulsion layers, interlayers, or overlayer and also comprising either anionic couplers or anionic scarvengers for color-forming development, finely dispersed and made fast-to-difi'usion in protective colloid binders of emulsion layers or interlayers respectively according to their purposes by a complexing procedure of said couplers and scavengers with finely divided particles of the coacervate which is prepared beforehand by reacting at least one of polymeric organic hydrophilic cationic compounds having cationic nitrogen containing groups in their molecule, with at least one of phthalic acid derivatives of gelatin, polyvinylalcohol and starch in an aqueous medium, the anionic scavengers being phenols having a sulfonic acid or carboxylic acid group attached to the phenol molecule.

5. A color photographic material according to claim 4 wherein the coacervate has been prepared in the presence of a non-ionic water soluble polymer.

References Cited UNITED STATES PATENTS 3,271,147 9/1966 Bush 96-1143 3,547,649 12/1970 Franco 96-84 A 3,625,691 12/1971 Ohyama 96-84 A 3,625,694 12/ 1971 Cohen et a1 96-84 A I. TRAVIS BROWN, Primary Examiner US. Cl. X.R.