CA1261190A - Photographic coupler dispersions - Google Patents

Abstract

PHOTOGRAPHIC COUPLER DISPERSIONS
Abstract of the Disclosure Loss in dark stability of a photographic silver halide element can be reduced by introducing into a dispersion comprising a dye-forming coupler for preparing such an element, a lipophilic anionic surfactant which comprises a sulphate or sulphonate group as the sole hydrophilic group and either a single aliphatic hydrocarbon group having at least 15 carbon atoms or two or more aliphatic hydrocarbon groups which together contain at least 17 carbon atoms. A second, less lipophilic, anionic surfactant can also be used in preparing the coupler dispersion.

Description

PHOT~GRAPHIC COUPLER DISPERSIONS
This invention relates to dispersions of couplers useful in silver halide color photc~raphic materials.
It is well known to incorporate dye-forming couplers into photographic silver halide emulsion layers, or adjacent hydrophilic colloid layers, so that an imagewise distribution of oxidized color developing agent obtained by developing silver halide in the emulsion layer reacts with the coupler to form a dye image. In a color photographic material having red-, green- and blue-sensitive emulsion layers for providing, respectively, cyan9 magenta and yellow dye images, it is necessary, in order to prevent conta-mination of each dye image with one or both of theother dyes, to ensure that the cyan, magenta and yellow couplers cannot diffuse from their positions in or near their respective emulsion layers. A
common me~hod of preventing coupler diffusion com-prises providing the coupler with a water-insoluble "ballast" group and, before mixing the coupler with the relevant coating composition, dispersing the coupler as a uniform mixture with a water-insoluble high-boiling organic solvent, termed a coupler solvent or an "oil-former", in an aqueous gelatin solution. A surface-active agent is used to facili-tate the dispersion process and to help stabilize the dispersion obtained.
A great variety of surface active agents have been made available and many types have been suggested for use in photographic materials. How-ever, relatively hydrophobic surface ative agents have been suggested for this purpose much less frequently than surfactants of other classes.
Instances concerning the preparation of dispersion~
of water-insoluble addenda, such as color couplers 9 ``` ~.~6~

are to be found in U.S. Patents 3,676,141 and 3,912,517. Both of these patents propose use of an anionic ~urfactant containing a sul~onate or sulphate group and a hydrophobie radical o~ 8 to 30 carbon atoms with a non-ionic surface active compound for aiding disper~ion by a conventional high-speed mi~ing process.
Many photographic coupler dispersions contain compounds with phenolic or naphtholic groups of which the acidity i~ enhanced by the presence of electron-withdrawing substituents in the ortho and/or para positions relative to the hydroxyl group.
Well-known compounds of this kind are certain phenolic and naphtholic cyan dye-forming couplers, but couplers ~or producing dyes of other colors are known which contain such acidic groups. It has been found that the dark stability of the dyes formed by color development of photographic materials contain-ing dispersions o~ phenolic or naphtholic compounds with enhanced acidity i~ not as good as is desir-able. The present invention is ba~ed upon the discovery that the adverse e~fect on dye stability o~ the phenolic or naphtholic compound can be mitigated to a ùseful extent by the use of certain lipophilic anionic surfactants in preparing the relevant dispersions. Additional anionic ~urfactants of more conventional type can be used to aid the dispersion process but non-ionic surfactants have been found to reduce the beneficial effect of the lipophilic surfactant and so are excluded.
In accord with the present invention a photographic element is provided comprising a support bearing at least one hydrophilic layer, preferably at least one hydrophilic photographic silver halide emulsion layer and/or at least one hydrophilic layer that is not photosensitive. The hydrophilic layer ~ 3 comprises at least one photographic coupler and an oil-former in the pre6ence of an anionic surfactant.
In this photographic element according to the inven-tion A. at least one of the photographic coupler and oil-former comprise a phenolic or naphtholic moiety having a least one electron-withdrawing group at a position ortho or para to the phenolic hydroxyl group; and B. the anionic surfactant iæ a lipGphilic anionic surfactant that comprises a sulfatP
or sulfonate group as the sole hydrophilic group and comprises either a single aliphatic hydrocarbon group having at least 15 carbon atoms or at least two aliphatic hydrocarbon groups tha~ together contain at least 17 carbon atoms.
The photographic element of the invention contains no non-ionic surfactant.
Another embodiment of the invention com prises a method of making a photographic coupler dispersion by dispersing a mixture containing the coupler and an oil-former in an aqueous hydrophilic colloid solution in the presence of an anionic surfactant, the coupler and/or the oil-former com-prising a phenolic or naphtholic moiety of which the acidity is enhanced by the presence of at least one electron-withdrawing group at a position ortho or para to the phenolic hydroxyl group, wherein there is added at any stage a lipophilic anionic surfactant which comprises a sulphate or sulfonate group as the sole hydrophilic group and either a single aliphatic hydrocarbon group having at least 15 carbon atoms or ~wo or more aliphatic hydrocarbon groups which together contain at least 17 carbon atoms, but where-in no non-ionic 6urfactant is used.

The anionic surfactant defined above is referred to herein as the lipophilic anionic surfact-ant.
The coupler dispersions according to the invention contain in the oily, dispersed~ phase, at least one compound comprising a phenolic or naph-~holic moiety, each such compound having at least one electron-withdrawing substituent in a position ortho or para to the phenolic hydroxyl group which enhances the acidity of that group. As is well known, many substituents have an electron-withdrawing effect and the following are listed as examples:
cyano -COORl nitro -CONRlR 2 halogen -SO2NRlR 2 (especially F, Cl or Br) -SO2R
-CCl3 or -C F2 +1l -SO3M

-OCOR -N=N-R 3 wherein R is an alkyl or aryl group, each of Rl and R 2 iS hydrogen or an alkyl or aryl group, R 3 iS
- an aryl or heterocyclic group and M is a cation, any group R, Rl, R2 and R3 possibly being itself substituted with such substituents as alkyl, alkoxy, aryl, aryloxy a halogen, nitro, and carboxylic acid, ester and amide groups. A suitable substituent for the phenolic or naphtholic moiety has a Hammett p-Substituent Constant greater than zero: See, for instance, the article by Exner in the book "Advances in Linear Free Energy Relationships", edited by Chapman and Shorter, Plenum Pre6s (London) 1972.
The compound comprislng ~he acidic phenolic, or naphtholic, moiety can be the coupler itself, in which case it can be a substituted member of one of ``` .~.~6 the various classes of cyan dye-~orming coupler.
Such coupler3 are described in, for example:
U.K. Patent 562,205 825,311 ~86,211843,497 627,~141,077,873 649,6601,165,563 737,1041,377,233 797,1411,541,075 Alternatively the compound comprising the acidic phenolic or naphtholic moiety can be a coupler giving, on color development, a magenta or yellow dye, coupling taking place preferentially at a pyrazolone or active methylene coupling position rather than at a position para to the hydroxyl group of the phenolic or naphtholic moiety. Couplers of this kind are described in, for instance, U.K. Patent Specification 1,474,128.
Another alternative i8 for the compound comprising the acidic phenolic or naphtholic ~oiety to be a coupler solvent, in which case the coupler itself need not contain such a moiety. Coupler solvents having acidic phenolic or naphtholic moieties are described in, for instance, U.S. Patent 4,207,393 and 4,228,235.
Any coupler æolvents known to be useful in photographic materials are useful as the oil-~ormer in a dispersion of the invention. Useful solvents are inert high-boiling liquids or low-melting solids, well-known examples being dibutyl phthalate and tricresyl phosphate. Numerous other coupler solvents are described in U.K. Patent Specification 541,589.
A coupler dispersion of the invention contains an anionic surfactant which comprises, as the sole hydrophilic group, a group of formula -S03M or -OS03M (where M i9 any convenient cation, ~uch as sodium or potassium cations) and either a single aliphatic hydrocarbon group having at least 15 carbon atoms os two or more aliphatic hydro-carbon groups wh;ch together contain at least 17carbon atoms. The aliphatic hydrocarbon group or groups can contain unsaturation and the surfactant molecule can contain such non-hydrophilic features as ether, amide or sulfonamide linkages and ester groups. Classes of surfactant having at least some members in accordance with these requirements include:
i) alkane sulfonates, ii) alcohol sulphates, iii) ether alcohol sulphates, iv) sulphated polyol esters, v) sulpha~ed alkanolamides, vi) sulphated amides vii) æulphated esters viii) sulfonated esters, 2C ix) al~ylarylsulfonates, x) olefin sulfonates, ~i) sulfopolycarbo~ylic esters, xii) sulfonalkylesters of fatty acids, xiii) sulfoalkylamides of fatty acids, and xiv) petroleum sulfonates.
Pre$erred surfactants from these classes are alkane sulfonates (class i) of formula: R'S03M and alkylphenol sulfonates (class ix) of formula:

~-\ /SO3M
HO ~ -~--R
~0/

wherein R' is a straight chain alkyl or alkenyl group of at least 15 carbon atoms, and dialkyl~ulfo-succinates (class xi) of formula:
CH2COOCmH
MO3S-CHCOOCnH2n+~

wherein m + n is at least 17~ m and n being the same or different. M in the above formula~ is a hydrogen ion, an alkali metal ion or any other useful cation.
Optionally, a mixture of two or more com-pounds can be used. Thus two or more couplers, coupler solvents or lipophilic surfactants can be employed, it being necessary for only one of these compounds to comprise an acidic phenolic or naph-tholic moiety.
The dispersing agent used in a method of the invention can also include a second, and less llpo-philic, anionic surfactant. This can be from the classes (i~ to (xiii) listed above, the reduced lipophilic character being achieved through the presence of fewer carbon atoms in the allphatic hydrocarbon group or groups present or through the presence of more than one hydrophilic group, any additional group belng~ for instance, an hydroxyl, or a carboxylic acid or salt, group. Thus, a second anionic surfactant can contain a single group -S03M
or -OS03M and either a single aliphatic hydrocarbon group having fewer than 15 carbon atoms or two or more aliphatic hydrocarbon group~ which together contain fewer than 17 carbon atoms. Alternatively, a second anionic surfactant can be of some other clasæ
such as a sulphated monoglyceride, a ~ulphated fat or oil having a free carboxyl group, an ~-sulfocar-boxylic acid, an alkyl glyceryl ether sulfonate or anN-acylated-amino acid.

The coupler-coupler solvent solution or mixture is dispersed, with the aid of a surfactant or surfactant mixture, in an aqueous hydrophilic colloid solution. The colloid is preferably gelatin or a simple derivative such as phthalated gelatin.
This dispersion step in a method of the invention can be effected conventionally using any high-speed mixing device. A water-miscible or volatile water-immiscible "auxiliary solvent" can be present, being removed by washing with water from the set dispersion or when volatile, by evaporation under reduced pressure. Auxiliary solvents and their use are described in, for example, U.S. Patent 2,801,171.
In carrying out a method of the invention, the compound comprising a phenolic or naphtholic moiety of enhanced acidity, or mixture of such com-pounds, preferably constitutes at least 5% by weight of the oil phase (i.e. the coupler, water-immiscible solvent and lipophilic anionic surfactant) and the lipophilic anionic surfactant preferably cons~itutes at least 1% by weight of the oil phaseO Relative to the weight of the coupler, the weight of lipophilic surfartant is usually present at a concentration of from 1 to 100~/o by weight, the preferred range being 3 to 20%
A coupler dispersion made by a method of thP
invention is employed conventionally in the manu-facture of incorporated-coupler silver halide color photographic materials, bo~h negative and positive materials. Numerous references to patent specifica-~ions and other publications relating to silver halide photographic materials, including color ma~erials and their processing, are given in Research Disclosure, December 1978, Item 17643 (see especially .~Z~ ~ ~9 _9_ sections ~II, XI, XIV and XI~) published by Kenneth Mason Publications, Ltd., The Old ~arbourmaster's, B North Street, Emsworth, Hampshire PO10 7DD, ENGLAND. Thus, the dispersion is mixed with the appropriate coating composition, usually a gelatino-silver halide photographic emul~ion, prior to coating.
The invention is illustrated by the ~ollow-ing examples.
Example 1 Dispersions of coupler I having the structure:
OH C2~5 lsHll t I~ ~ N~COCHO \ ~D - C~El1-t C ~ ~/

Cl were prepared by di~solving the coupler, 0.60 g, in di-n-butyl phthalate, 0.60g, and mechanically dis-persing the resulting oily solution in 9.4 ml of 6.6% w/v gelatin aolution to which had been added surfactant as in Table 1. The result wa~ an oil-in-water dispersion having an average droplet diameter of less than l ~m.
Photographic coating~ were prepared by combining together, under sa~elight conditions, 1.5 g of coupler dispersion, 1.5 g of 12 l/2 % w/v aqueous gelatin ~olution, 0.20 ml of photographic paper type silver chlorobromide emulsion (approximately 1.0 M in silver halide) and 5.5 ml water. 5% w/v chromic sulphate solution, 0.30 ml, was added immediately prior to coating on photographic film base at a wet thickness of approximately 0.1 mm.

~' ~Z6~

Portions of dried coating were exposed to room light for 5 s and then developed for 210 B in a -phenylene-diamine developer (KODAK-"Ektaprint 2ll, trademark of Eastman Kodak Company, U.S.A.) at 31C, bleach-fixed.for 120 ~ in a bleach-fix solution (KODAK "Ektaprint", trademark of Ea~tman Kodak Company, U.S.A.), washed for 30 minutes in running water, and dried.
The resulting cyan dye density of each sample was measured with a transmission densitometer through a red filter. The ~amples were then incub-ated in an oven at 60C and 70% relative humidity and the dye density measured from time to time. The initial optical density (Di) and the percentage density loss at the various times are recorded in Table 1.

% density 10BS at stated time/days Surfactant added (sodium salt)Di 7 14 28 42 Control:
tri-isopropylnaphthalene sulfonate 0.03 g ~.56 5.8 12 26 37 0.06 g 1.85 6.3 12 26 39 0.12 g 1.9~ 7.3 15 30 43 Invention:
bis (tridecyl) sulfosuccinate 0.04 g 1.37 1.5 5.1 11 18 0.08 g 1.57 0.6 4.0 10 ~8 pentadecylphenolsulfonate 0.06 g 1.26 2.~ 5.5 12 20 0.12 g 1.70 1.2 4.1 11 19 35 .

D~

It will be see~ that the image dyes from dispersions made accordlng to the inven~ion faded at less than half the rate of the dyes from the prior art dispersions (sodium tri-isopropylnaphthalene sulfonate peptized) in this accelerated dsrk keeping test.
Example 2 This example illustrates the use of a com~
bination of hydrophilic and hydrophobic surfactants according to the the invention.
A coupler dispersion was prepared by dis-solving coupler I, S.0 g, in di-n-butyl phthalate,

2.8 g together with 2 - (2 - butoxyethoxy~ ethyl acetate, 0.4 g, and mechanically dispersing the resulting oily solution in 11.5% w/v gelatin 601u-tion, 42 g, containing sodium triisopropylnaphthalene sulfonate, 0.18 g. Portions of 10 g were withdrawn, and 10% w/v solutions of sodium bis (tridecyl~ sulfo-succinate in 1:~ methanol:water were added a~ in Table 2 and mechanically dispersed into the disper-sion.
Photographic coatings were prepared by combining together, under safelight condltions, 1.~ g of coupler dispersion, 1.5 g of 12 1/2~/o w/v aqueous gelatin solution, 0.20 ml of photographic paper type silver chlorobromide emulsion (approximately 1.0 M in silver halide), and 6.0 ml water. 5~/O w/v chromic sulphate solution, 0.30 ml, was added immediately prior to coating on photographic film base at a wet thickness of approximately 0.1 mm.
Portions of dried coating were exposed 3 processed and tested as in Example 1: the results are given in Table 2. A low humidity accelerated keeping ~est was also carried out by placing pro-cessed strips in an oven at 77C with no addedhumidity, and measuring the dye density at intervals as before. These results are given in Table 3.

60C 7070 R~ H. ~esults 5 10% sodium bis (tridecyl) ~/O density loss sulfosuccinate solution at stated time added Di 7 14 2~ days None 1.71 8.2 19 36 1~ 0.1 ml 1.80 6.1 12 26 0.2 1.52 4.6 10 23 0.4 1.08 1.9 6.5 18 0.8 1.95 *3.5 0 9.7 *increase 77C low humidity results 10% sodium bis (tridecyl) % density 106s sulfosuccina~e solution at stated time added Di 3 7 1~ days .

None 1.78 13 30 55 - 0.1 ml 1.79 9.5 23 4 0.~ 1.48 10 22 ~7 0.4 1.~2 6.6 17 43 0.8 1.91 4.7 14 39 Example 3 This example illustrates another combination of hydrophilic and hydrophobic surfactants according to the invention.

1 ~6~ l~V

Coupler dispersions were prepared by dis-solving together 1.0 g of coupler I, 0.6 g of tricresyl phosphate, and 0.10 g of sodium ~is ~tridecyl) sulfosuccinate, and mechanically dispers-S ing the resulting oily solution into 5.0 g of a 12 1/2% w/v aqueous gelatin solution mixed with

3.0 ml wa~er and 10% w¦v aqueous sodium dioctyl sulfosuccinate as stated in Table 4. The dispersion prepared for Example 2 was used for this control.
Coatings were prepared as in Example 2, except that 0.9 ml of dispersion and ~.1 ml of water were added. Testing was as in Example 2, and results are given in Tablas 4 and 5.

60C 70% R. H. results 10% sodium dioctylsulfo- % density loss 20 succinate solution added a~ stated time to coupler dispersion Di 6 14 days (control) None (dispersion as Example 2) 2.62 S.0 13 0.60 ml 1.49 2.0 5.4 0.75 ml 2.17 1.4 4.6 1.0 ml 2.63 1.2 1.9 ~ Z~ 3 77C low humidity results 5 10% sodium dioctylsulfo- % density loss succinate solution added at stated time to coupler dispersion Di 3 6 days (control) None 2.55 5.9 15 0.60 ml l.SO 2.0 6.
0.75 ml 2.18 2.7 7.~
1.0 ml 2.61 1.1 4.6 Example 4 A dispersion of coupler II having the formula:
OH CsHll~t ~ . ! .
~ ONH(CH 2) 40~ C sH 1 l-t was prepared by dissolving 3.5 g of coupler into a 2s mixture of 2.0 g of di-n-butyl phthalate and 8.0 g of 2-(2-butoxyethoxy) ethyl acPtate, and mechanically dispersing the resulting oily solution into 40 g of 9~0V/o w/v gelatin solution to which had been added 0.5 g of sodîum tri iso-propylnaphthalene sulfonate.
The dispersion was then cooled, and when set was cut into small cubes of approximately 0.5 cm edge. The chopped dispersion was washed for S hours in chilled (5C) demineralized water which was maintained at approximately pH 5.5 by addition of a small quantity of propionic acid. The washed dispersion was melted at 40C and to a 5.0 g portion was added 0.2 g of a 70% w/w solution of sodium bis (tridecyl) sulfosucc-inate ("Aerosol TR 70" - trademark - supplied by Cyanamid of Great Britain Limited). I'his solution was mechanically dispersed into the dispersion sample.
Coatings were prepared as in Example ~, except that 1.3 g of dispersion and 4.9 ml of water were used for each coating. Testing was carried out as in Example 2, and the results are shown in Table 6.

Condition A: 60C, 70% R. H.
Condi~ion B: 77C, low humidity Fading 70% sodium bis (tridecyl) % density loss 15 Condition sulfosuccinate added Diafter 7 14 days A - 1~901.6 4.2 A 0.1 g 20100 1.9 B _ 1~882.1 6.4 B 0.1 g 2.150.5 2.3 Example 5 This is a comparative example in which no acidic phenol or naphthol was present.
Dispersions of coupler were prepared by dissolving coupler, 1.5 g, in di-n-butyl phthalate, 0.9 g, and ethyl acetate, 0.9 g, and mechanically dispersing the resultant solution in 15 g of 9.~a/0 w/w gela~in to which had been added 10% sodium tri-isopropyl naphthalene sulfonate, 0.6 ml.
1.0 g portions of dispersion were taken and 0.3 ml of water or of a solution of hydrophobic surfactant added (see Table 7) and the mixture held for 20 minutes at 40C.

Photographic coatings were prepared by combining to~ether, under safelight conditions, the treated portion of coupler dispersion, 1.5 g of 12 1/2% w/v aqueous gelatin solution, 0.25 ml of photographic pPper type silver chlorobromide emulsion (approximately 1.0 M in silver halide) and 5.7 ml water.
5% w/v chromic sulphate soluti~n, 0.30 ml, was added immediately prior to coating on photo graphic film base at a wet thickness of approximately 0.1 mm.
Portions of dried coating were exposed to room light for 5 s and then developed for 21U s at 31C, bleach-fixed for 60 s, washed for 10 minutes in running water, and dried. The processing solutions used were as for Example 1.
The resulting dye density of each sample was measured with a ~ransmission densitometer through an appropriate filter: green for a magenta image, blue for a yellow image. The samples were then incubated in the dark in an oven at 60C and 70% relative humidity for four weeks and the dye densities again measured. The percentage fades which had occurred are listed in Table 7. It will be seen that the presence of the surfactants did not improve the dark - stability.

Image Original % Fade Coupler Addition Hue _ Density (4 we~ks~
s III Water Yellow1.11 0.0 A 1.14 0.6 IY Water Magenta1.63 0.6 A 1.65 1.

V Water Magenta1.80 2.8 ~ 6 9.7 -Notes: Addition : 0.3 ml of water or A : 7% Aerosol TR70 (Sodium bis-tridecyl sulfo-succinate) (Aerosol TR7Q is a trademark for a surfactant manufactured by the American Cyanamid Company, U.S.A.) Couplers III to V had the structures:
Coupler III
Cl\ ~\ C(CH2~30 ~ - CsHll-t (CH 3) 3CCCHCNH
o ~!
i!

~,./

.~ \.
!~ I!

OCH~

Coupler IV
Cl Cl \.~ \./

~ / \

0 NH~ -NHC~HO ~ C4Hg Cl2H2s Coupler V Q Cl . Cl ./
!
/ \
C s~l l -t NHCO~ l-NHCOCH20-~ CsHl l-t Example 6 This Example illustrates the use of the surfactants of the invention when coupler IV was dispersed in the presence of an acidic phenol coupler sOlvent Coupler IV, 1.0 g; n-dodecyl-R-hydroxybenzo-ate, 0.33 g; n-octyl-p-hydroxy-benzoate, 0.33 g; and N,N-diethyl lauramide, 0.33 g) were melted to form an oily solution. This solution was mechanically dispersed into 7.6 g of 10.5% w/w gelatln solution, to which had been added 0.8 g of 10% w/w sodium dioctyl sulfosuccinate aqueous solution and other surfactants as stated in Table 9.
Photographic coatings were prepared by combining together under safelight conditions, 0.8 g of coupler dispersion, 0.25 g of silver chlorobromide photographic paper emulsion (approximately 1.0 M in silver halide, 1.0 g of 12% w/w gelatin aqueous solution3 and 6.6 ml of water. 5% w/v chromic sulphate solution, 0.30 ml, was added immediately prior to coating on photographic film base at a wet thickness of approximately 0.10 mm.

LZ6~

Portions of dried coating were exposed, processed and tested as in Example S: re~ults are given in Table 9. It will be ~een that in this and in the previous Example the presence of the sur~act-ant of the Invention improved the dar~ Rtability ofthe dye in the presence of t~e acidic phenols.

Coating Surfactant Original % Fade in Added Density12 weeks -- 1.24 6.5 A, 0.10 g 1.29 3.1 A, 0.20 g 1.26 2.4 A, 0.30 g 1.72 -1.2 (density increase) Note: surfactant A, 70% sodium bi3 - tridecyl sulfo-succinate ~xample Z
The coupler used in this Example had an acidic phenol leaving group. The results 3how how the dark stability of the image dye wa3 most dimin-i~hed ln areas of low image density, where most acidic phenol remained. The stabilizi~g e~ect of the surfactants of the invention i8 illustrated: the effects varied with the humidity at which the accelerated dark fading was carried out.
A coupler di~persion and coatings were prepared as in Example 5, except that coupler VI was used. The coatings were expoæed to a photographic step wedge and processed as in Example 5. The image densities of the various steps of the image were measured (blue filter). The strips were incubated either for 60 days at 60C, 70% R~ or for 28 days at 77C, low R~. Reæults are given in Table 10 :
coating A had 0.3 ml water added, B had 0.3 ml 7% Aerosol TR70, as in Example 5.

-20- , Coupler VI: (CH3~3CCCHCN~ N~SO 2 (CH 2~ i sCH 3 O
.
.~ \.
1, t !~ ,'!

OH

. . , _ _ _ _ . . _ _ _ .
_ 60 Days 60C 70 % RH 2~ Days 77C, Low RH
CoatingInitial Step % Initial Step~/O
Density Fade Density Fade A 0.35 26 0.39 38 0.67 33 0.71 37 0.97 28 1.~2 34 1.37 20 1.42 23 1.76 11 1~82 1~
1.90 7 1.98 3 B 0.47 13 0.46 11 0.78 15 0.76 9 1.10 18 1.08 8 1.52 18 1.49 6 1.90 17 1.87 4 2.02 14 1.95 2 6~

Example 8 Coatings were prepared and tested as in Example 5, using the acidic phenol cyan coupler VII.
The surfactant additions were different: these and other results are given in Table 10.

.
Surfactant Original (red) /0 Fade Addition Density (4 weeks~
0.3 ml water 1.64 4.3 0.1 ml A 1.24 1.6 O.Z ml A 1.01 3.0 0.1 ml C 1.09 0.9 0.1 ml ~ 1.69 0.6 Note: Surfactant solution.
A, 7% sodium bis-tridecyl sulfosuccinate.
C, 10% Hos~apur SAS 60 (Trademark). (This is a mixture of C13 - Clg sodium alkyl sulfonates).
D, 10% sodium pentadecyl phenol sulfonate.
Coupler VII
O OH
Il . I
C3F7CNH \ ~ CsHll-t il.= i ~HCCHO ~ CsHll~t C4Hs Example 9 3 Mllltilayer coatings were made on a paper support according to the following summary. The numbers in parenthesis are coverages expressed as mg/m2. In the case of the silver halide in the emulsion layers) the coverages relate to the silver present.

-~2-Layer 6 - Gelatin (1076~
Layer 5 - Gelatin (1679), red-sensitive silver çhlorobromide emulsion ~81), cyan coupler (1076) and hydrophobic surfact-ant (301), (See Table II) Layer 4 - Gelatin (1313), UV-absorber (861), dioctylhydroquinone (5~
Layer 3 - Gelatin (1851), green-sensitive silver chlorobromide emulsion (41~), mag~nta coupler IV (522) Layer ~ - Gelatin (753), dioctylhydroquinone (54) Layer 1 - Gelatin (1690), blue-sensitive silver chlorobromide emulsion (403), yellow coupler III (990~, gelatin hardener Support - Electron -bombarded polyethylene coated paper.
The couplers were lncorporated in the layers as dispersions, being mixed with di n-butyl phthalate (one half the coupler weight in the case of the cyan ~nd magenta couplers and one quar~er the coupler ` weight ln the case of the yellow coupler) and dispersed in aqueous gelatin solutions with the aid of sodium ~ri-isopropyl naphthalene sulfonate. The UV sbsorber in layer 4 comprised a mixture of ~4.170 (by weight) of 2 (2-hydroxy-3,5-di-tert-pentylphenyl) benzotriazole, 15% 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)benzotriazole and 0.9~ dioctylhydro-quinone dispersed in 2-(2-butoxyethoxy)ethyl acetate. The gelatin hardener in layer 1 was bis-(vinylsulfonylmethyl)ether and was added in an amount equal to 1.75% of the total weight of the gelatin in ~he multilayer coating.
Four different multilayer coatings were made using two different couplers, each coated with or wi~hout the lipophilic anionic surfactant sodium bis~tridecyl) sulfosuccinate. The couplers were numbers I and VIIT defined by the formula:

q~3~

Cl NHCOCHO ~ CsHll-t .~-\./ /-=-!~ ,1! Cs~ t R
Cl Coupler I : R = CH3 Coupler VIII : R = C2Hs Samples of the four coatings were exposed, processed as described in Example 1 and then used for determining the stability of the cyan dye image under incubation test conditions. In all the tests the loss in red-light reflection density of an ima~e having an initial value of 1.7 was measured as a function of the incubation time. Two different test conditions were used, 77C and 15% relative humidity for the two week tests and 60~C and 70% humidity for 16 week tests.
The results obtained are given in Table 11.

Coupler Lipophilic % densi~y loss after Surfac~ant (weeks incubation):
(mg/m2~ 4 6 8 12 lS 2 I 0 17 32 35 48 ~5 ~8 II 301 10 19 24 3~ 45 25 These show that the lipophilic surfactant reduced the densi~y loss of both cyan image dyes for both incubation test conditions. The stability of the image dyes to light exposure was unimpaired by the presence of the lipophilic surfactant.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variatlons and modifications can be effected within the spirit and scope of the invention.

Claims (11)

WHAT IS CLAIMED IS:

1. In a photographic silver halide element comprising a support bearing at least one hydrophilic layer comprising a photographic coupler dispersion comprising at least one photographic coupler and an oil-former in the presence of an anionic surfactant, the improvement wherein A. at least one of the photographic coupler and oil-former comprises a phenolic or naphtholic moiety having at least one electron-withdrawing group at a position ortho or para to the phenolic hydroxyl group; and B. the anionic surfactant is a lipophilic anionic surfactant which is a compound represented by the formula:

wherein the sum of m plus n is at least 17; m and n are the same or different numbers; and, M is hydrogen or a cation, and containing no non-ionic surfactant.

2. A photographic silver halide element as in claim 1 wherein the lipophilic anionic surfactant is bis(tridecyl)sulfosuccinate.

3. A photographic silver halide element as in claim 1 comprising a second lipophilic anionic surfactant comprising a single aliphatic hydrocarbon group having less than 15 carbon atoms or at least two aliphatic hydrocarbon groups which together contain less than 17 carbon atoms.

4. A photographic silver halide element as in claim 1 wherein the coupler is a phenolic or naphtholic cyan dye-forming coupler.

5. A photographic element as in claim 1 comprising a second anionic surfactant.

6. A photographic silver halide element as in claim 1 comprising a second anionic surfactant which is a compound selected from the group consisting of sulfated monoglycerides, sulfated fats or oils having a free carboxyl group, .alpha.-sulfocarboxylic acids, alkyl glyceryl ether sulfonates, and N-acylated amino acids.

7. A method of making a photographic coupler dispersion by dispersing a mixture containing the coupler and an oil-former in an aqueous hydrophilic colloid solution in the presence of an anionic surfactant, at least one of the coupler and the oil-former comprising a phenolic or naphtholic moiety of which the acidity is enhanced by the presence of at least one electron-withdrawing group at a position ortho or para to the phenolic hydroxyl group, wherein there is added at any stage a lipophilic anionic surfactant which is a compound represented by the formula:

wherein the sum of m plus n is at least 17; m and n are the same or different numbers; and, M is hydrogen or a cation, but wherein no non-ionic surfactant is used.

8. A method according to claim 7 wherein the lipophilic anionic surfactant is added before the dispersion step.

9. A method according to claim 7 wherein the coupler is a phenolic or naphtholic cyan dye-forming coupler.

10. A method according to claim 7 wherein the coupler solvent comprises a phenolic or naphtholic moiety of enhanced acidity.

11. A method according to claim 7 wherein the total lipophilic surfactant constitutes at least 1% by weight of the dispersed substances.