US3912517A

US3912517A - Method of incorporating photographic ingredients into hydrophilic colloids

Info

Publication number: US3912517A
Application number: US450322A
Authority: US
Inventors: Poucke Raphael Karel Van; Vugt Jaak Pieter Van
Original assignee: Agfa Gevaert NV
Current assignee: Agfa Gevaert NV
Priority date: 1973-03-19
Filing date: 1974-03-12
Publication date: 1975-10-14
Anticipated expiration: 1992-10-14
Also published as: BE812173R; CA1020387A; DE2412428A1; CH578193A5; FR2237220B2; JPS49128725A; GB1460894A; FR2237220A2

Abstract

A method is described of incorporating a substantially waterinsoluble photographic ingredient into a photographic hydrophilic colloid layer by the steps of dissolving said ingredient in an organic solvent having a solubility in water of at most 25 % by weight at 20*C, admixing the organic solution thus obtained with water in the presence of a surface active agent but in the absence of a hydrophilic colloid, removing the said organic solvent forming thereby a dispersion of the said ingredient in water and incorporating the dispersion thus formed in the said hydrophilic colloid coating composition, characterized in that the said organic solution of photographic ingredient is admixed with water in the presence of an anionic surface active agent comprising in its molecule a hydrophobic hydrocarbon group of at least 8 C-atoms and a hydrophilic -SO3M or -OSO3M group wherein M is hydrogen, an alkali metal atom, ammonium or organic ammonium and a non-ionic surface active hydroxy compound so that the HLBindex of the combination of surface active compounds is comprised between about 8 and about 18. Improved stability of the dispersion of ingredient in hydrophilic colloid is obtained and the hydrophilic colloid layer has better coating characteristics.

Description

United States Patent [191 Van Poucke et al.

[451 Oct. 14, 1975 METHOD OF INCORPORATING PHOTOGRAPHIC INGREDIENTS INTO HYDROPHILIC COLLOIDS [75] Inventors: Raphael Karel Van Poucke,

Berchem; Jaak Pieter Van Vugt, Antwerp, both of Belgium [73] Assignee: Agfa-Gevaert, a naamloze vennootschap, Mortsel, Belgium [22] Filed: Mar. 12, 1974 [21] Appl. No.: 450,322

[30] Foreign Application Priority Data Mar. 19, i973 United Kingdom 13017/73 [52] US. Cl. 96/100; 96/9; 96/84;

[51] Int. Cl. G03C l/40 [58] Field of Search 96/100, 120, 130, 9, 114.5

[56] References Cited UNITED STATES PATENTS 3,658,546 4 1972 Van Doorselaer et al 96/120 3,676,141 7 1972 Hara et al. 96/100 Primary ExaminerJ. Travis Brown Attorney, Agent, or Firm-William J. Daniel ABSTRACT A method is described of incorporating a substantially water-insoluble photographic ingredient into a photographic hydrophilic colloid layer by the steps of dissolving said ingredient in an organic solvent having a solubility in water of at most 25 by weight at 20C, admixing the organic solution thus obtained with water in the presence of a surface active agent but in the absence of a hydrophilic colloid, removing the said organic solvent forming thereby a dispersion of the said ingredient in water and incorporating the dispersion thus formed in the said hydrophilic colloid coating composition, characterized in that the said organic solution of photographic ingredient is admixed with water in the presence of an anionic surface active agent comprising in its molecule a hydrophobic hydrocarbon group of at least 8 C-atoms and a hydrophilic SO M or -OSO M group wherein M is hydrogen, an alkali metal atom, ammonium or organic ammonium and a non-ionic surface active hydroxy compound so that the l-lLB-index of the combination of surface active compounds is comprised between about 8 and about 18. Improved stability of the dispersion of ingredient in hydrophilic colloid is obtained and the hydrophilic colloid layer has better coating character- 1stics.

11' Claims, No Drawings METHOD OF INCORPORATING PHOTOGRAPHIC INGREDIENTS INTO HYDROPHILIC COLLOIDS The present invention is concerned with a method of incorporating photographic ingredients into hydrophilic colloid compositions, more especially with a method of making stable dispersions in water of such ingredients from which they can be homogeneously distributed into hydrophilic colloid coating compositions for forming one of the water-permeable layers of a photographic silver halide element. The method of the present invention is an improvement of the method of the British Pat. Specification 1,297,947 filed Mar. 20, 1969 by Gevaert-Agfa N.V. corresponding to US. pat. No. 3,658,546.

According to the British Pat. Specification No. 1,297,947 as mentioned above a photographic ingredient having a solubility in water at C of not more than 3 7r by weight, is incorporated into a hydrophilic colloid coating composition for forming a waterpermeable colloid layer of a light-sensitive silver halide element, by a method which comprises dissolving said ingredient in a mainly water-immiscible organic solvent, admixing the solution thus obtained with water in the presence of a surface active agent but in the absence of a hydrophilic colloid, removing the said organic solvent forming thereby a dispersion of the said ingredient in water and incorporating the dispersion thus formed in the said hydrophilic colloid coating composition, wherein the said mainly water-immiscible solvent has a solubility in water of not more than by weight at 20C. The dispersion of ingredient in water formed need not be added directly to the hydrophilic colloid coating composition of the layer into which the said component should be present e.g. a light-sensitive silver halide emulsion layer. It is possible to create stocks of the dispersion of the photographic ingredients in water and to take part of the preformed dispersion for addition to the hydrophilic colloid coating composition whenever needed.

The method of the British Patent Specification has several advantages over the dispersion techniques according to which the organic solution of the photographic ingredient is dispersed into an aqueous hydrophilic colloid medium, in particular aqueous gelatin, from which the solvent is removed and which can be admixed afterwards with a lightsensitive silver halide emulsion. For example, removal-of the solvent from the dispersion in water is much easier to effect than removal from the gelatin composition. The dispersion of the photographic ingredients in water remains liquid and can be stored at room temperature whereas the gelatin compositions, even gelatin compositions comprising as low as 1 7c of gelatin, should be stored at temperatures below room temperature whereby they become solid and should be remelted at the stage of addition to the hydrophilic colloid coating composition. The dispersions of photographic ingredients in water can comprise markedly higher concentrations of ingredient than the preformed gelatin dispersions. Moreover, when preformed dispersions in gelatin are made an extra amount of gelatin is added to the hydrophilic colloid coating composition which increases the coating thickness or in the case of colour couplers conversely decreases the dye density which can be obtained for a given coating thickness. In addition thereto, phenolic compounds should be added to the preformed gelatin dispersions in order to protect the gelatin against degeneration.

Notwithstanding the method according to the British Patent Specification has important advantages. sometimes it also poses difficulties depending on the particular photographic ingredient involved and the dispersing agent used, which is usually an anionic surfactant. For example, the stability of the dispersions of the photographic ingredients is not always sufficient either during storing of the aqueous dispersions or after addition to the hydrophilic colloid coating composition. Also the dimensions of the dispersed particles are sometimes not sufficiently small which may give rise to undesirable turbidity of the coated layers. In other instances, the dispersing agent causes undesirable foaming or poses difficulties on coating the hydrophilic colloid coating composition e.g. as regards uniformity of coating thickness.

It has now been found that the method according to the British Patent Specification can be improved so that the above difficulties are reduced or eliminated by dispersing the organic solution of the photographic ingredient into the water in the presence of a dispersing system having an HLB index comprised between about 8 and about 18. This can be realized successfully by the use of an anionic surface active agent, especially a surface active agent comprising in its molecular structure a hydrophobic hydrocarbon group of at least 8 C- atoms, preferably from about 8 to about 24 C-atoms and a hydrophilic SO M or OSO M group wherein M is hydrogen, an alkali metal atom, ammonium or organic ammonium, together with a non-ionic surface active agent, especially a non-ionic surface active hydroxy compound.

Non-ionic surface active agents cannot be used alone in the method of the British specification because it is not possible to form dispersions in water of sufficiently small particle size and because they give rise to repellency spotsin the coated layers.

Thus, the present invention provides a method of incorporating a photographic ingredient having a solubility in water at 20C of not more than 3 72 by weight into a hydrophilic colloid coating composition for forming a water-permeable colloid layer of a light-sensitive silver halide element, which comprises in accordance with the British Patent Specification the steps of dissolving said ingredient in an organic solvent having a solubility in water of at most 25 by weight at 20C, admixing the organic solution thus obtained with water in the presence of a surface active agent, removing the said organic solvent forming thereby a dispersion of the said ingredient in water, and incorporating the dispersion thus formed in the said hydrophilic colloid coating composition with the modification that the said organic solution of photographic ingredient is admixed with water in the presence of an anionic surface active agent comprising in its molecule a hydrophobic hydrocarbon group of at least 8 C-atoms and a hydrophilic -SO M or OSO;;M group wherein M is hydrogen, an alkali metal atom, ammonium or organic ammonium and a non-ionic surface active hydroxy compound so that the HLB index of this combination of surface active agents is comprised between about 8 and about 18.

The method of the present invention is useful for incorporating photographic ingredients having a solubility in water at 20C of at most 3 by weight and thus is particularly concerned with photographic ingredients that comprise a ballasting hydrophobic group of at least 8 C-atoms and that do not contain strongly watersolubilizing groups such as carboxy and sulpho groups. These ingredients are for example photographic couplers as used in colour photography which upon colour development couple with the oxidation products of aromatic primary amino colour developing agents, maskforming compounds as used in colour photography which oxidatively couple with a colour coupler in an oxidizing bleaching bath as described for example in UK. Pat. No. 880.862 filed Dec. 31, 1956 and 975,932 filed Nov. 13, 1959 both by Gevaert Photo-Producten N.V., dyes which include spectrally sensitizing dyes and light-screening dyes e.g. antihalation and filter dyes, emulsion stabilizing agents and anti-oxidation agents, developing agents including tanning developing agents and developing agent precursor compounds and other photographically active ingredients.

As referred to above, the anionic surface active agents of use according to the present invention comprise a hydrophobic hydrocarbon group of at least 8 C- atoms, preferably from about 8 to about 24 C-atoms, and a hydrophilic -SO;,M or OSO M group wherein M is hydrogen, an alkali metal atom, ammonium or organic ammonium. These anionic surface active agents are well known in the art and include the following non-limitative groups of compounds 1. sulphates and sulphonates and other sulphoderivatives of branched-chain or straight-chain aliphatic primary or secondary alcohols having at least 8 C-atoms and ethoxylated derivatives thereof which can be represented by the formula wherein m stands for O to 30, preferably to 12 R stands for a straight-chain or branched-chain aliphatic hydrocarbon group having at least 8 C- atoms e.g. dodecyl, tetradecyl, isotetradecyl, hexadecyl, isohexadecyl, or an alkylphenyl group wherein the alkyl group has at least C-atoms Z represents 80 M, 080 M, OCOXSO M or Y-A'SO M wherein M stands for hydrogen, an alkali metal atom such as lithium, sodium and potassium, ammonium or organic ammonium e.g. diethanol ammonium, diethyl ammonium, morpholinium etc.,

X stands for alkylene, aralkylene or arylene,

Y stands for oxygen or sulphur, and

A is alkylene, substituted alkylene e.g. alkylene substituted by hydroxyl, or aralkylene.

2. sulphated monoglycerides which can be represented by the formula CH OOCR,

CH OH CH OSO M wherein M has the same significance as above and R,

represents a branched-chain or straight-chain aliphatic group as defined for R derived from a carboxylic acid e.g. capric, lauric, myristic, palmitic, stearic, behenic and oleic acid.

3. sulphated monoethanol amides and ethoxylated derivatives thereof which can be represented by the formula wherein R,, m and M have the same significance as above.

4. Compounds of the formula wherein R and M have the same significance as above, and R is hydrogen or C C, alkyl 5. Half-esters or dicsters of sulphosuccinic acid which can be represented by the formula and Representative examples of specific anionic surface active agents are I'lCuHzg-CON H-CH CH OSO Na 8. CH OOC(CH CH CH=OH CH OSO5Na (sodium isotetradecyl sulphate) (R'=dimethyl butyl and R"=dimethyl hexyl) (sodium isohexadecyl sulphate) CH CH CH CH CH CH OSO Na CH3 (sodium isooctadecyl sulphate) H C CH OSO Na CH, CH/

(sodium hydroabietyl sulphate) 17. sodium isohexadecyl sulphonate 18. sodium isooctadecyl sulphonate l9. sodium hydroabietyl sulphonate SO Na 2 l. isohexadecyl-OCO- SO Na 23. isotetradecyl-O-(CH -SO Na 24. isohexadecyl-O-(CH -SO Na 25. n-C H O(CH CH )t-CH CH 0SO Na wherein x+ 8-12 (ocH,cH2),oco Q O Nu wherein x+y 8-12 wherein x+y 8-12 wherein x+y 812 Non-ionic surface active hydroxy compounds for use in accordance with the present invention are well known in the art.

They include ethoxylated alcohols and phenols e.g. the reaction product of an alcohol or phenol with more than one mole, preferably 3 to 50 moles of ethylene oxide. Suitable alcohols which may be ethoxylated are C -C aliphatic alcohols, oleyl alcohols, oxo alcohols, the so-called Ziegler alcohols, ether alcohols, secondary alcohols, alkyl phenols, alkylated-B-naphthol, complex phenols derived from condensatin of a simple phenol with an aldehyde or ketone e.g. phenol with an alkyl cyclohexanone, etc.

Other non-ionic surface active compounds are esters from branched-chain or straight-chain fatty acids comprising at least 12 C-atoms e.g. lauric acid, myristic acid, palmitic acid, stearic acid and oleic acid, and polyhydroxy compounds e.g. ethylene glycol, propylene glycol, glycerol, diethylene glycol, polyethylene glycol, pentaerythritol, hexitol anhydrides e.g. sorbitan, isosorbitol, mannitan and isomannitol, polyoxyethylene derivatives of hexitolanhydrides, etc.

Preferred non-ionic surface active agents for use according to the present invention are ethoxylated alkyl phenols having from 3 to 50 recurring ethylene oxide units e.g. ethoxylated phenols carrying one or more C -C linear or branched alkyl substituents such as isooctyl phenol, nonylphenol and isononylphenol and esters of hexitol anhydrides or polyethylene oxide derivatives thereof obtained by esterification of 1 or 2 hydroxy] groups of the hexitolanhydride with branched-chain or straight-chain C, C fatty acids, e.g. sorbitan monostearate, sorbitan monolaurate and polyoxyethylene sorbitan monostearate.

In the preparation of the dispersions of the photographic ingredients in water in accordance with the invention usually a minimum of water is used in order to obtain dispersions as concentrated as possible which is particularly suitable for storing purposes. This minimum varies of course with each individual component and can be determined by trial. The amount of mainly water-immiscible solvent used is dependent on the solubility of the particular compound therein; it can vary within very wide limits but is also preferably restricted to a minimum. 7

The dispersion into water of the organic solution of the ingredient may be assisted by the use of high speed stirrers, homogenizers (single or double stage homogenizers), colloid mills and ultrasonic wave generators.

The anionic as well as the non-ionic surface active agents employed in making the dispersions in water according to the present invention may be present in the water into which the organic solution of the photographic ingredient is dispersed. However, according to a preferred embodiment of the present invention, the non-ionic surface active agent is used at the stage of dissolving the photographic ingredient in the sparingly water-soluble organic solvent whereas the anionic surface active agent is used at the stage of dispersing the organic solution in the water.

The amount of dispersing agents or wetting agents used in making the dispersions in water of photographic ingredients according to the method of the present invention, may vary within very wide limits; it is generally comprised between 1 and 20 by weight relative to the weight of ingredient to be dispersed. The ratio of anionic to non-ionic surface active agent is such that a HLB-index comprised between about 8 and about 18'is obtained.

The organic solvents from which the photographic ingredients are dispersed in water have a solubility in water of at most 25 by weight at room-temperature (20C). Solvents having a solubility in water comprised between 2 and by weight at room-temperature are preferred. Moreover, said solvents preferably are lowboiling solvents i.e. solvents having a boiling point of at most 130C and a sufficiently high vapour pressure so that they can still be removed readily from the aqueous dispersion by applying a vacuum of 500 to 10 mm Hg at a temperature of 25 to 80C.

Examples of suitable mainly water-immiscible solvents for use according to the present invention are methylene chloride, ethyl formate, n-butyl formate, ethyl acetate, n-propyl acetate, isopropyl acetate, butyl acetate, methyl propionate, ethyl propionate, diethyl carbonate, carbon tetrachloride, sym.tetrachloroethane, 1,1,2-trichloroethane, 1,2-dichloropropane, chloroform, n-butyl alcohol, diethyl ketone, methyl npropyl ketone, diisopropyl ether, cyclohexane, methyl cyclohexane, benzene, toluene and nitromethane.

In addition to the low-boiling water-immiscible organic solvent referred to above it is also possible to use a socalled oil-former which is a water-immiscible organic crystalloidal solvent having a boiling point above 175C e.g. tricresyl phosphate, tributyl phthalate,'dibu tyl phthalate, diisooctyl phthalate, tributyl citrate, dibutyl sebacate, N,N'-dimethyl palmitamide, etc. and which is left in the dispersion after removal of the waterimmiscible low-boiling organic solvent referred to hereinbefore. These so-called oil-formers are well known in the art for use in dispersing photographic ingredients e.g. colour couplers in photographic hydrophilic colloid coating compositions.

Further. it is possible, in order to facilitate dissolving of the photographic ingredient, to use in conjunction with the low-boiling mainly water-immiscible organic solvent a solvent which is miscible with water in all proportions. Of course, such water-miscible solvent should be completely miscible with the, said organic mainly water-immiscible solvent.

The water-miscible solvents are readily removed from the aqueous dispersion together with the waterimmiscible solvents, unless they have too low a vapourpressure to be removed with the water-immiscible solvents, in which case they are left in the dispersion of component in waterfrom which they are incorporated into the hydrophilic colloid composition for forming a layer of a photographic material. The water-miscible solvents left in this hydrophilic colloid composition can be removed therefrom unless this is deemed unnecessary because they will have no disadvantageous effect on the physical or photographic properties by washing the chilled and thereby gelled colloid composition.

Examples of water-miscible solvents that are suitable for use in conjunction with the substantially waterimmiscible solvents are methanol, ethanol, isopropyl alcohol, dimethyl sulphoxide, tetrahydrofuran, N-methyl-2-pyrrolidone, dioxan, dimethyl formamide, dimethoxyethane, formamide, ethylene glycol, acetonitrile, acetone, butyrolactone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diacetone alcohol and tetrahydrothiophene-l,1-dioxide.

The removal of the sparingly'water-miscible solvent from the aqueous dispersion may be achieved for instance by evaporation, if necessary, e.g. for accelerating the removal, by applying reduced pressure and/or moderate heating.

After removal of the sparingly water-miscible solvent from the aqueous dispersion, the said dispersion can be incorporated directly into the colloid coating composition of the layer into which the photographic ingredient is intended to be present. However, it is also possible to create stocks of the concentrated dispersions of the ingredient in water and to use parts of these stocks whenever required.

The hydrophilic colloid coating composition into which the aqueous dispersion of photographic ingredient is incorporated usually comprises gelatin as hydrophilic colloid although other hydrophilic colloidal materials or mixtures of them can be used too e.g. colloidal albumin, zein, casein, a cellulose derivative such as carboxymethyl cellulose, a synthetic hydrophilic colloid such as polyvinyl alcohol, poly-N-vinyl pyrrolidone, etc.

The said colloid coating compositions for forming a layer of a photographic material may of course contain in additioni to the colloid carrier all sorts of other ingredients e.g. light-sensitive silver halide and other silver halide emulsion ingredients.

The amount of stored dispersion to be added to the colloid coating composition of the photographic layer is such that the ingredient is present in the resulting layer in the desired concentration. This amount is naturally dependent on the concentration of said ingredient in said dispersion. In accordance with the present invention it was found possible in some instances to make stable dispersions of ingredients in water comprising up to 30 of said ingredient.

The following examples illustrate the present inventron.

EXAMPLE I A solution of g of the cyan-forming colour coupler with structural formula and 1 g of SPAN (trade name of the Atlas Chemical Industries lnc., Wilmington, Del., USA for sorbitan monolaurate) in 30 ml of ethyl acetate, was dispersed by means of ultrasonic emulsifator based on the Pohlman whistle principle in 100 ml of water heated to 55C and comprising 2.4 ml of a 10 aqueous solution of TERGlTOL 4 (trade name of Union Carbide and Carbon, New York, N.Y., USA for sodium isotetradecyl sulphate).

The HLB-value of the combination of surface active agents used was 14.

The ethyl acetate was removed in a thin-film evaporator under reduce pressure of 400 mm Hg at 55C leaving a stable dispersion of the colour coupler in water.

The dispersion of colour coupler in water was admixed by gentle stirring with a conventional gelatino red-sensitized silver halide emulsion ready for coating so as to disperse the colour coupler homogeneously throughout the emulsion.

Example 2 Example 1 was repeated with the only difference that now 0.9 g of SPAN 20 (trade name) and 3.5 ml of the 10 aqueous solution of TERGITOL 4 (trade name) was used.

The HLB-value of the combination of surface active agents used was 17.

EXAMPLE 3 10 g of the colour coupler of example 1 were dissolved in 30 ml of ethyl acetate comprising 1 g of HOS- TAPAL W (trade name of Farbwerke Hoechst, Frankfurt, W.GErmany for a polyoxyethylene ether of nonylphenol.)

The solution was dispersed by means of a high pressure homogenizer in 100 ml of water heated .to 55C and comprising 2 ml of a 10 7( aqueous solution of the sodium salt of oleyl methyl taurine.

The HLB-value of the combination of surface active agents was 8.

The ethyl acetate was removed in a thin-film evaporator under reduced pressure of 400 mm Hg at 55C. A stable dispersion of colour coupler in water was obtained.

10 The dispersion was admixed by gentle stirring with a conventional gelatino red-sensitized silver halide emulsion ready for coating so as to disperse the colour coupler homogeneously throughout the emulsion.

EXAMPLE 4 10 g of the colour coupler of example 1 were dissolved in 30 ml of ethyl acetate comprising 0.9 g of SPAN 20 (trade name) and 10 g of tricresyl phosphate. The solution was dispersed by means of a high pressure homogenizer in 100 ml -of water heated to 55C and comprising 10 ml of a 5 aqueous solution of sodium isohexadecyl sulphate.

The HLB value of the combination of surface active agents was 18.

The ethyl acetate was removed under reduced pressure at 55C and a stable dispersion of colour coupler in water was formed.

The stable dispersion was homogeneously mixed with a red sensitized gelatino silver halide emulsion ready for coating.

EXAMPLE 5 10 g of the cyan-forming colour coupler with formula EXAMPLE 6 10 g of the yellow-forming colour coupler with formula 2)is a S m --NHCOCH,CO

and 0.8 g of SPAN 20 (trade name) were dissolved in 30 ml of ethyl acetate.

The solution was dispersed in ml of water comprising 8 ml of a 5 aqueous solution of sodium isohexadecyl sulphate.

The HLB value of the combination of surface active agents was 18.

After removal of the ethyl acetate under reduced pressure at 55C, the stable dispersion obtained was mixed homogeneously with a blue-sensitive gelatino silver halide emulsion ready for coating.

EXAMPLE 7 10 g of the cyan-forming colour coupler with formula Chemical Industries Inc., Wilmington, Del., USA for a polyethylene sorbitan monostearate) were dissolved in 30 ml of ethyl acetate.

The solution was dispersed at 55C in 100 ml of water comprising 4ml of a 20 aqueous solution of MER- SOLAT H (trade name of Farbenfabriken Bayer A.G., Leverkusen, W.Germany for an alkane sulphonate made by sulphochlorination and subsequent saponification of a mixture of saturated branched-chain as well as straight-chain hydrocarbons averaging 14 C-atoms obtained by hydrogenation of the so-called Kogasins, which are the hydrocarbon mixtures distilling in the range of 230-320C formed according to the Fisher- Tropsch hydrocarbon synthesis).

The HLB value of the combination of surface active agents was 13.

The ethyl acetate was removed at 55 C under reduced pressure leaving a stable dispersion of colour coupler in water.

The stable aqueous dispersion was mixed by gentle stirring with a conventional red-sensitized silver halide emulsion. I

EXAMPLE 8 g of magenta-forming colour coupler with structural formula 10 g of tricresyl phosphate and 0.8 g of SPAN (trade name) were dissolved in ml of ethyl acetate.-

The solution was dispersed by means of an Ultrasonic Emulsator based on the Pohlman whistle principle in 100 ml of water comprising 3.75 ml of a 10 aqueous solution of sodium .isotetradecyl sulphate.

The HLB value of the combination of surface active agents was 18. l

After removal of the ethyl acetate at 50C under reduced pressure the stable aqueous dispersion. was mixed by gentle stirring with a conventional redsensitized silver halide emulsion.

The aqueous dispersions of colour couplers prepared as described in the above examples showed high stability and could be stored for weeks. The stability of the dispersions was markedly better than that of dispersions prepared according to the method of the British patent specification wherein an anionic surface active compound was used alone.

We claim 1. In a method of incorporating a photographic ingredient having a solubility in water at 20C of not more than 3 by weight into a hydrophilic colloid coating composition for forming a water-permeable colloid layer of a light-sensitive silver halide element, which comprises the steps of dissolving said ingredient in an organic solvent having a solubility in water of at most 25 by weight at 20C, admixing the organic solution thus obtained with water in the presence of a surface active agent but in the absence of a hydrophilic colloid, removing said organic solvent forming thereby a dispersion of said ingredient in water and incorporating the dispersion thus formed in said hydrophilic colloid coating composition, the improvement which comprises admixing. said organic solution of photographic ingredient with water in the presence of an anionic surface active agent comprising in its molecule a hydrophobic hydrocarbon group of at least 8 C-atoms and a hydrophilic -SO M or OSO ,M group wherein M is hydrogen, an alkali metal atom, ammonium or organic ammonium and a non-ionic surface active hydroxy compound in said proportions that the combined HBL- index of said surface active compounds is comprised between about 8 and about l8.

2. Method according to claim 1 wherein said anionic surface active agent is used at the stage of dispersing said organic solution in water and the non-ionic surface active agent is used at the stage of dissolving said ingredient in said organic solvent.

3. Method according to claim 1, wherein said 'organic solvent has a boiling point of at most C.

4. Method according to claim 3, wherein the organic solvent is ethyl acetate.

5. Method according to claim 3, wherein the organic solution comprises in addition to said organic solvent a water-immiscible organic crystalloidal solvent having a boiling point above C.

6. Method according to claim 5, wherein the highboiling solvent is dibutyl phthalate or tricresyl phosphate.

7. Method according to claim 1,

wherein the non-ionic surface active agent is anethoxylated phenol carrying one or more linear or branched-chain C -C alkyl groups and comprising from 3 to 50 recurring ethylene oxide units.

8. Method according to claim 1, wherein the nonionic surface active agent is an ester of a hexitolanhydride or polyoxyethylene ether thereof obtained by esterification of l or 2 hydroxyl groups of the hexitol anhydride with branched-chain or straight-chain C, C fatty acids 9. Method according to claim 1, wherein the hydrophilic colloid is gelatin.

10. Method according to claim 9, wherein the hydrophilic colloid coating composition is a gelatino silver halide emulsion.

1 1. Method according to claim 10 wherein the photographic ingredient is a photographic colour coupler or

Claims

1. IN A METHOD OF INCORPORATING A PHOTOGRAPHIC INGREDIENT HAVING A SOLUBILITY IN WATER AT 20*C OF NOT MORE THAN 3% BY WEIGHT INTO A HYDROPHILIC COLLOID COATING COMPOSITION FOR FORMING A WATER-PERMEABLE COLLOID LAYER OF A LIGHT-SENSITIVE SILVER HALIDE ELEMENT, WHICH COMPRISES THE STEPS OF DISSOLVING SAID INGREDIENT IN AN ORGANIC SOLVENT HAVING A SOLUBILITY IN WATER OF AT MOST 25% BY WEIGHT AT 20*C, ADMIXING THE ORGANIC SOLUTION THUS OBTAINED WITH WATER IN THE PRESENCE OF A SURFACE ACTIVE AGENT BUT IN THE ABSENCE OF A HYDROPHILIC COLLOID, REMOVING SAID ORGANIC SOLVENT FORMING THEREBY A DISPERSION OF SAID INGREDIENT IN WATER AND INCORPORATING THE DISPERSION THUS FORMED IN SAID HYDROPHILIC COLLOID COATING COMPOSITION, THE IMPROVEMENT WHICH COMPRISES ADMIXING SAID ORGANIC SOLUTION OF PHOTOGRAPHIC INGREDIENT WITH WATER IN THE PRESENCE OF AN ANIONIC SURFACE ACTIVE AGENT COMPRISING IN ITS MOLECULE A HYDROPHOBIC HYDROCARBON GROUP OF AT LEAST 8 C-ATOMS AND A HYDROPHILIC -SO3M OR -OSO3, GROUP WHEREIN M IS HYDROGEN, AN ALKALI METAL ATOM, AMMONIUM OR ORGANIC AMMONIUM AND A NON-IONIC SURFACE CTIVE HYDROXY COMPOUND IN SAID PROPORTIONS THAT THE COMBINED HBL-INDEX OF SAID SURFACE ACTIVE COMPOUNDS IS COMPRISES BETWEEN ABOUT 8 AND ABOUT 18.

3. Method according to claim 1, wherein said organic solvent has a boiling point of at most 130*C.

4. Method according to claim 3, wherein the organic solvent is ethyl acetate.

5. Method according to claim 3, wherein the organic solution comprises in addition to said organic solvent a water-immiscible organic crystalloidal solvent having a boiling point above 175*C.

6. Method according to claim 5, wherein the high-boiling solvent is dibutyl phthalate or tricresyl phosphate.

7. Method according to claim 1, wherein the non-ionic surface active agent is anethoxylated phenol carrying one or more linear or branched-chain C6-C14 alkyl groups and comprising from 3 to 50 recurring ethylene oxide units.

8. Method according to claim 1, wherein the non-ionic surface active agent is an ester of a hexitolanhydride or polyoxyethylene ether thereof obtained by esterification of 1 or 2 hydroxyl groups of the hexitol anhydride with branched-chain or straight-chain C12-C18 fatty acids.

9. Method according to claim 1, wherein the hydrophilic colloid is gelatin.

11. Method according to claim 10 wherein the photographic ingredient is a photographic colour coupler or mask-forming compound.