METHOD OF PREPARING COUPLER DISPERSIONS

Abstract: A method of making fine particle photographic coupler dispersions which comprises forming a dispersion of photographic coupler, coupler solvent and auxiliary coupler solvent in an aqueous gelatin medium containing at least about 1 % by weight of an anionic surfactant having a hydrophobicity of 2-10 log P(OH) and washing the dispersion with water for a time sufficient to remove at least one-fourth of the surfactant.

Description: METHOD OF PREPARING COUPLER DISPERSIONS BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a method of preparing coupler dispersions for photographic use and more particularly, to a method of preparing extremely fine size coupler dispersions. Description of Related Art Copending Application Serial No. 631,607 entitled "Color Photographic Element", filed December 21, 1990 by a number of the same applicants as this application and assigned to the same assignee as this application discloses a particular color photographic element wherein the image-dye forming couplers of certain layers are in a dispersion having a mean particle size of less than 0.14 microns. One of the advantages at least partially attributable to utilizing coupler dispersions of reduced particle size is that photographic elements employing such coupler dispersions exhibit reduced granularity. U.S. Patent 4,385,110 issued May 24, 1983, teaches that in order to make the particle size of an emulsion dispersion finer, it is usually necessary to use an emulsifying agent in a large amount. The use of an emulsifying agent in a large amount is liable to cause coating troubles due to foaming of the emulsion, such as the formation of pin holes, unevenness in the coated film thickness, and to deteriorate the film quality of the coated photographic element of a light-sensitive material. In the manufacture of dispersions for use in photographic light-sensitive elements, such as coupler dispersions, the photographic coupler is dissolved in a permanent coupler solvent with the addition of an auxiliary coupler solvent that assists in the dissolution of the coupler in the permanent coupler solvent. This solution is mixed under high shearing action with an aqueous hydrophilic colloid, generally gelatin, containing a surfactant at elevated temperatures in order to break the organic phase into sub-micron droplets dispersed in the continuous aqueous phase. The auxiliary coupler solvent is then removed from the aqueous dispersion. Two techniques are employed for removing the auxiliary coupler solvent and these techniques depend upon the characteristic of the auxiliary coupler solvent. When the auxiliary coupler solvent is of low volatility, it is generally removed by evaporative techniques. When the auxiliary coupler solvent is less volatile, but at least partially water soluble, it is removed by washing by any suitable technique such as noodling coupled with washing as disclosed in U.S. Patents 2,322,027; 2,801,170; 2,801,171; 2,949,360; and 3,396,027. Another suitable technique to employ is a membrane wherein the dispersion is contacted across the membrane as disclosed in copending U.S. Application 516,955 filed April 30, 1990, which application is assigned to the same assignee as this application. There is a need for a simplified method of making photographic coupler dispersions wherein the particle size of the coupler dispersion is reduced from those techniques presently employed in the art. SUMMARY OF THE __NVENTION The invention provides a method of making fine particle photographic coupler dispersions by forming a dispersion of a photographic coupler together with a coupler solvent and an auxiliary coupler solvent in an aqueous hydrophilic colloid medium containing at least about 1% by weight of an anionic surfactant having a hydrophobicity of from 2 to 10 log P(OH) and washing the dispersion with water for a time sufficient to remove at least one-fourth of the surfactant. By "fine particle" is meant a dispersion in which the average size of the oil phase droplet is less than 0.25 μm, preferably less than 0.2 μm and most preferably less than 0.15 μm as measured by sedimentation field flow fractionation (SFFF) . DESCRIPTION OF THE PREFERRED EMBODIMENT In a preferred embodiment, an oil phase comprising the coupler, the coupler solvent and the auxiliary coupler solvent are mixed together and heated in order to dissolve the coupler in the combination of solvents. An aqueous phase comprising a hydrophilic colloid, water and at least 1% by weight, preferably from 1 to 5 percent by weight of an anionic surfactant having a hydrophobicity of from 2 to 10 log P(OH) is prepared. The two components, that is, the oil phase and the aqueous phase are next intimately mixed together using a mixing device such as a colloid mill or homogenizer to achieve a particle size of the oil phase in the aqueous phase as desired. Finally, the dispersion is washed with water by any suitable technique in order to reduce the amount of the surfactant to at least one-fourth of the quantity of surfactant originally added. The washing step can be conducted by dialysis, such as that described in U.S. Patent Application 516,955 filed April 30, 1990 (which is incorporated herein by reference) or the dispersion can be chilled, extruded into noodles and then washed with water together with agitation. In either technique, the washing is conducted until at least one quarter of the surfactant has been removed. The rate that the surfactant can be washed from the dispersion is dependent upon the hydrophobicity of the particular surfactant. Generally the higher the hydrophobicity of the surfactant the longer the washout rate must be in order to provide the fine particle characteristics of the dispersion necessary for satisfactory use in the preparation of a light-sensitive silver halide element. Any suitable anionic surfactant may be employed wherein the hydrophobicity as measured Log P(OH) is from about 2 to 10. It is preferred that the hydrophobicity of the surfactant range from about 2.5 to about 7 and most preferably from about 4 to about 6.7 in order to provide most satisfactory results. It has been found experimentally that the advantages of improved dispersion stability to droplet growth and crystallization, lower dispersion viscosity and improved coatability with the avoidance of streaking and repellencies are due to the combination of the use of an excess amount of surfactants together with the washing procedure to reduce the amount of surfactant in the dispersion. When evaporation techniques are employed together with an excess quantity of surfactant, the viscosity of the resulting dispersion increases so dramatically as to render it useless in the preparation of light-sensitive layers for photographic elements, and this is true regardless of the hydrophobicity of the surfactants employed. The process in accordance with this invention is applicable for the formation of dispersions containing all types of couplers such as those set forth in UK Patent No. 478,984, Yager et al U.S. Patent No. 3,113,864, Vittum et al U.S. Patent Nos. 3,002,836, 2,271,238 and 2,362,598, Schwan et al U.S. Patent No. 2,950,970, Carroll et al U.S. Patent No. 2,592,243, Porter et al U.S. Patent Nos. 2,343,703, 2,376,380 and 2,369,489, Spath U.K. Patent No. 886,723 and U.S. Patent No. 2,899,306, Tuite U.S. Patent No. 3,152,896 and Mannes et al U.S. Patent Nos. 2,115,394, 2,252,718 and 2,108,602, ad Pilato U.S. Patent No. 3,547,650. In this form the developer contains a color-developing agent (e.g., a primary aromatic amine) which in its oxidized form is capable of reacting with the coupler (coupling) to form the image dye. The dye-forming couplers can be incorporated in different amounts to achieve different photographic effects. For example, U.K. Patent No. 923,045 and Kumai et al U.S. Patent No. 3,843,369 teach limiting the concentration of coupler in relation to the silver coverage to less than normally employed amounts in faster and intermediate speed emulsion layers. The dye-forming couplers are commonly chosen to form subtractive primary (i.e., yellow, magenta and cyan) image dyes and are nondiffusible, colorless couplers, such as two and four equivalent couplers of the open chain ketomethylene, pyrazolone, pyrazolotriazole, pyrazolobenzimidazole, phenol and naphthol type hydrophobically ballasted for incorporation in high- boiling organic (coupler) solvents. Such couplers are illustrated by Salminen et al U.S. Patent Nos. 2,423,730, 2,772,162, 2,895,826, 2,407,207, 3,737,316 and 2,367,531, Loria et al U.S. Patent Nos. 2,772,161, 2,600,788, 3,006,759, 3,214,437 and 3,253,924, McCrossen et al U.S. Patent No. 2,875,057, Bush et al U.S. Patent No. 2,908,573, Gledhill et al U.S. Patent No. 3,034,892, Weissberger et al U.S. Patent Nos. 2,474,293, 2,407,210, 3,062,653, 3,265,506 and 3,384,657, Porter et al U.S. Patent No. 2,343,703, Greenhalgh et al U.S. Patent No. 3,127,269, Feniak et al U.S. Patent Nos. 2,865,748, 2,933,391 and 2,865,751, Bailey et al U.S. Patent No. 3,725,067, Beavers et al U.S. Patent No. 3,758,308, Lau . U.S. Patent No. 3,779,763, Fernandez U.S. Patent No. 3,785,829, U.K. Patent No."969,921, U.S. Patent No. 1,241,069, U.K. Patent No. 1,011,940, Vanden Eynde et al U.S. Patent No. 3,762,921, Beavers U.S. Patent No. 2,983,608, Loria U.S. Patent Nos. 3,311,476, 3,408,194, 3,458,315, 3,447,928, 3,476,563. Cressman et al U.S. Patent No. 3,419,390, Young U.S. Patent No. 3,419,391, Lestina U.S. Patent No. 3,519,429, U.K. Patent No. 975,928, U.K. Patent No. 1,111,554, Jaeken U.S. Patent No. 3,222,176 and Canadian Patent No. 726,651, Schulte et al U.K. Patent No. 1,248,924 and Whitmore et al U.S. Patent No. 3,227,550. Development inhibitor-releasing (DIR) couplers are illustrated by Whitmore et al U.S. Patent No. 3,148,062, Barr et al U.S. Patent No. 3,227,554, Barr U.S. Patent No. 3,733,201, Sawdey U.S. Patent No. 3,617,291, Groet et al U.S. Patent No. 3,703,375, Abbott et al U.S. Patent No. 3,615,506, Weissberger et al U.S. Patent No. 3,265,506, Seymour U.S. Patent No. 3,620,745, Marx et al U.S. Patent No. 3,632,345, Mader et al U.S. Patent No. 3,869,291, U.K. Patent No. 1,201,110, Oishi et al U.S. Patent No. 3,462,485, Verbrugghe U.K. Patent No. 1,236,767, Fujiwhara et al U.S. Patent No. 3,770,436 and Matsuo et al U.S. Patent No. 3,808,945. Dye-forming couplers and nondye-forming compounds which upon coupling release a variety of photographically useful groups are described in Lau U.S. Patent No. 4,248,962. DIR compounds which do not form dye upon reaction with oxidized color-developing agents can be employed, as illustrated by Fujiwhara et al German OLS No. 2,529,350 and U.S. Patent Nos. 3,928,041, 3,958,993 and 3,961,959, Odenwalder et al German OLS No. 2,448,063, Tanaka et al German OLS No. 2,610,546, Kikuchi et al U.S. Patent No. 4,049,455 and Credner et al U.S. Patent No. 4 " ,052,213. DIR compounds which oxidatively cleave can be employed, as illustrated by Porter et al U.S. Patent No. 3,379,529, Green et al U.S. Patent No. 3,043,690, Barr U.S. Patent - No. 3,364,022, Duennebier et al U.S. Patent No. 3,297,445 and Rees et al U.S. Patent No. 3,287,129. Particular couplers which may be used according to the invention are those disclosed in U.S. Patent Nos. 2,322,027; and the following: (1) l-hydroxy-2-[o-(2' ,4*-di-tert amylphenoxy) -n- butyl]-naphthamide (U.S. Patent 2,474.293) (2) l-hydroxy-4-phenylazo - 4' - (p-tert butyl- phenoxy)-2-naphthanilide (U.S. Patent 2,521.908} (3) 2- (2,4-di-tert amylphenoxyacetamino)-4, 6 - dichloro-5-methyl phenol (Graham U.S. Patent 2,725,291) (4) 2 - (α-Di-tert eunylphenoxy-n-butyrylamino) - 4, 6-dichloro-5-methyl phenol (5) 6 - {{α - {4- [α- (2,4-di-tert amyl- phenoxy)butylamido]phenoxy}-acetamido} } - 2 ,4-dichloro-3-methyl phenol (6) 2 - [3'-(2",4"-di__mylphenoxy)-acetamido_ - benzamido-4-chloro-5-methyl phenol (7) l-(2',4',6 , -trichlorophenyl)-3-[3" - (2" ' ,4" '-di-tert a ylphenoxy-acetamido)- benzamido[ - 5-pyrazolone (U.S. Patent 2,600,788) (8) l-(2',4 , ,6*, -trichlorophenyl) - 3 - [3"-(2" ' ,4" '-di-tert-amylphenoxy- acetamido-benzamido] - 4 - (p-methoxy- phenylazo) -5-pyrazolone (9) N- (4-benzoylacetaminobenzenesulfonyl) - N - (γ-phenylpropyl)-p-toluidined (U.S. Patent 2,298,443) (10) α-o-methoxybenzoyl-α-chloro - 4 - [α-(2,4-di-tertaιπylphenox )-n-butylamido)- acetanilide (McCrossen U.S. Patent 2,728,658) (11) α-{3 - [α - (2,4-di-tert amylphenoxy) acetamido]-benzoyl}2-methoxy-anilide (12) 3-benzoylacetamino-4-methoxy - 2' ,4'-di-tert airylphenoxyacetani1ide (13) 4-benzoylacetamino- - methoxy-2 • ,4' -di-tert a ylphenoxyacetanilide The terms "coupler solvents" and "auxiliary coupler solvents" are terms widely used in the photographic industry and are understood by those working in this environment. Coupler solvents are substantially water insoluble, of low molecular weight and have a boiling point above about 175°C at atmospheric pressure and a high solvent action for the coupler and dyes formed therefrom, and are permeable to photographic developer oxidization products. Auxiliary coupler solvents enhance the coupler solubility and have a water solubility within the range of from about 2.5 to 100 parts of solvent per 100 parts of water. Suitable coupler solvents include alkyl esters of phthalic acid in which the alkyl radical preferably contains less than 12 carbon atoms, for example, ethylphthalate, ethylphthalate, propylphthalate and n- butylphthalate, di-n-butylphthalate, n-amylphthalate, isoamylphthalate dioctylphthalate, didecylphthalate didodecylphthalate, 1,4-cyclohexylene dimethylene bis(2- ethyl hexanoate) , 2 , -di-tert-amyl phenol, esters of phosphoric acid, for example, triphenylphosphate, tri-o- cresylphosphate and diphenylmono-p-tert.butylphenyl phosphate, and alkyl amides or acetanilides, for example, N,n-butylacetanilide and N-methyl-p-methyl acetanilide. The coupler solvents disclosed in U.S. Patent No. 3,936,303 (incorporated herein by reference) are suitable for use in this invention. The coupler solvents preferably have a water solubility of less than about 0.1 part of solvent in 100 parts of water and are generally employed in amounts less than 2 parts of coupler solvent per part of coupler by weight. Suitable auxiliary coupler solvents include esters of aliphatic alcohols with acetic or propionic acid, for example, ethylacetate, isopropyl acetate, ethylpropionate, beta-ethoxyethyl acetate, 2-(2-butoxy-β- ethoxy) thyl acetate, cyclohexanone, triethyl phosphate and the like. The coupler solvents and auxiliary coupler solvents set forth in U.S. Patent No. 2,949,360, which is incorporated herein by reference are suitable in the practice of this invention. Any suitable anionic surfactant having a hydrophobicity between the limits set forth above may be employed in the quantity set forth such as, for example, alkali metal salts of alkarylene sulfonic ' acid such as the sodium salt of isobutylnaphthalene sulfonic acid, a particularly useful one of which is a mixture of monomers, dimers, trimers, and tetramers of the sodium salt of isopropylnaphthalene sulfonic acid, sold by DuPont Company under the trade designation ALKANOL XC; alkali metal salts of alkyl sulfates such as for example, sodium octyl sulfate, sodium decyl sulfate, sodium dodecyl sulfate, sodium tetradecyl sulfate, the corresponding potassium salts, and the like; alkaryl sulfonate salts, such as, sodium and potassium dodecyl benzene sulfonate; alkyl sulfosuccinates such as, for example, sodium bis(2-ethylhexyl)succinic sulfonate; a particularly suitable one of which is sold under the trade designation AEROSOL OT by American Cyanamid, diethylpentyl sodium sulfosuccinate and the like. Any suitable hydrophilic colloid such as, those disclosed in Research Disclosure, Issue Number 308, December 1989 in paragraph IX, A, may be used in accordance with this invention. The method of this invention can also be employed in the manufacture of other photographically useful chemicals such as, U.V. absorbers and oxidized developer scavengers including those set forth in Research Disclosure, Issue 308, Dec. 1989, Paragraph 8C and Paragraph 71, respectively. The invention will be further illustrated by the following examples in which parts and percentages are by weight unless otherwise specified. Example 1 An oil phase component is prepared by heating to about 120°C about 40 grams of the coupler having the following formula: CNH N C 5 H n -t Coupler I about 40 grams of coupler solvent, di-n-butyl- phthalate and about 80 grams of auxiliary coupler solvent 2-(2- butoxyethoxy)ethylacetate to dissolve the coupler. An aqueous phase component is prepared by heating at 50°C about 80 grams of gelatin, about 1.0% of the sodium salt of isobutylnaphthalene sulfonic acid sold by Dupont under the trade designation Alkanol XC and about 664 grams of distilled water to dissolve the gelatin. The two phases are then combined and passed through a colloid mill five times to form fine oil particles. The dispersion is then chill set, noodled and washed 8 hours to remove auxiliary coupler solvent and surfactant. The dispersion is then remelted, stirred and chill set. The resulting dispersion has an average particle size of 0.12 μm, as measured by sedimentation field flow fractionation (SFFF) described in Research & Development (pp 78-82, September, 1986), incorporated herein by reference. This dispersion is then incorporated into the red sensitive layers of a light sensitive photographic element as described in Example 1 of co-appending application U.S.Serial No. 631,607, filed December 2, 1990, incorporated herein by refernce, which exhibits reduced granularity without any adverse effects on coating quality. Example 2 The procedure of Example 1 is repeated with the exception that 20 grams of tricresylphosphate are employed as the coupler solvent in the oil phase and 684 grams of distilled water are employed in the aqueous phase. All of the remaining quantities and conditions remain the same. This dispersion having an average particle size of 0.12 μm (SFFF) is employed in a light sensitive element in accordance with Example 1 and provides reduced granularity. Example 3 Example 1 is once again repeated with the exception that the oil phase is heated to about 100°C to dissolve the coupler. About 27.5 grams of a coupler having the formula: and about 55 grams of the coupler solvent of Example 2 and about 55 grams of the same auxiliary coupler solvent as employed in Example 1 are used. The aqueous phase is made up of 80 grams of gelatin, 150 grams of the same surfactant as in Example 1 and 632 grams of distilled water. The average particle size of the dispersion is about 0.13 μm as measured by (SFFF) . The dispersion is incorporated into a light sensitive element in accordance with USSN 631,607 which demonstrates reduced granularity. Example 4 The general procedure of Example 1 is repeated with the exception that the oil phase is heated to about 50°C in order to dissolve the coupler which is 40 grams of about 20 grams of tricresylphosphate in about 120 grams of 2-(2-butoxyethoxy)ethylacetate. The aqueous phase contains about 80 grams of gelatin, about 120 grams of the surfactant of Example 1 and about 620 grams of distilled water. This dispersion having an average particle size of 0.10 μm is incorporated into the green sensitive layers of a light sensitive element as described in Example 1 of copending application USSN 631,607 which exhibits reduced granularity without any adverse effects on coating quality. Exa ple 5 Once again the general procedure of Example 1 is followed with the exception that 40 grams of a coupler having the following formula: 20 grams of tricresylphosphate and 120 grams of 2-(2- butoxyethoxy)ethylacetate are heated to about 80°C in order to dissolve the coupler in the coupler solvent and auxiliary coupler solvent. The aqueous phase contains about 80 grams of gelatin, about 100 grams of the surfactant of Example 1, about 20 grams of polyvinylpyrrolidone having an average molecular weight of about 40,000 and 620 grams of distilled water. The remaining conditions of Example 1 are the same. This coupler having an average particle size of 0.02 μm is incorporated in green sensitive layer 7 as described in USSN 631,607 and exhibits improved granularity. Example 6 The procedure of Example 1 is generally repeated with the exception that 70.0g of coupler is disolved in about 23.3 grams of di-n-butylphthalate and about 140 grams of 2-(2-butoxyethoxy)ethylacetate are heated to about 80°C to dissolve the coupler in the solvents. The aqueous phase is composed of 70 grams of gelatin, about 120 grams of the surfactant of Example 1, and 607 grams of distilled water. This dispersion is incorporated into the blue sensitive layers of the light sensitive element described in Example 1 of USSN 631,607 which exhibits reduced granularity. Comparison of Separation bv Evaporation With Washing Method in Accordance With the Invention. Example 7 _ * A series of washed and evaporated dispersions were prepared according to the following formulation: Coupler 1 (Example 1) 6.0% Coupler Solvent -Di-n-butylphthlate 6.0% Oil Phase Auxiliary Coupler Solvent 12.0% Gelatin 6.0% sodium, salt of isopropylnaphthalene 0.6% or 1.2% Aqueous Phase sulfonic acid Distilled Water 69.4% or 68.8% The two phases were combined and passed through a colloid mill five times to form small oil particles. In the case of the evaporated dispersions, ethyl acetate was employed as the auxiliary solvent and was removed by evaporation. In the case of the washed dispersions, 2- (2-butoxyethoxy) ethyl acetate was used as the auxiliary solvent and was removed by washing. The dispersions were held without stirring for 24 hours at 45°C and then examined microscopically to determine the degree of coupler crystallization. Dispersion viscosities were also measured using a Brookfield Model HBT-DV II viscometer. Particle size was determined by the light scattering method described in UK Patent 2071841B. The results are summarized in the following table: Surfactant Level Auxiliary Solvent Dispersion Viscosity (cps) Degree of Removal Method Particle Size (μm) at 1500 sec" 1 Crystallization The results demonstrate that fine particle dispersions are obtained only when the high level of surfactant is employed. However, in the case of evaporated dispersions, the dispersion viscosity is much too high and severe crystallization is observed. The washed dispersions made at the high surfactant level exhibit small particle sizes with reasonable viscosities and an acceptable position for dispersion crystallization due to the partial removal of surfactant during washing. Example 8 A series of dispersions were prepared as described in the previous example except that sodium bis (2-ethylhexyl) succinic sulfonate, sold under the trade designation Aerosol-OT was employed as the dispersion surfactant. These dispersions were also characterized in terms of particle size and viscosity. They were also examined microscopically for crystallization following an 8 hour, 45°C hold. Results are summarized below: Surfactant Level Auxiliary Solvent Dispersion Particle Viscosity (cps) al Degree of Removal Method Size Qun) 1500 sec 1 Crystallization These results also show that small particle sizes are obtained at the high surfactant levels. With the evaporated dispersions, very high viscosity and heavy crystallization is observed. Only the combination of high surfactant level followed by washing produces fine particles with reasonable viscosity and an acceptable position for crystallization. Example 9 A number of different anionic surfactants having varying hydrophobicities were used to prepare dispersions by the procedure conducted in Example 1. The conditions and ingredients were the same, however, the surfactant was altered in each case, the quantity of each being in equal molar amounts as the surfactant of Example 1. The concentration of surfactant was monitored in order to determine the time of removal and the particle size of the dispersions was measured by SFFF. The results establish that fine particle dispersions can be prepared by this method with a variety of surfactants. They also demonstrate that one-quarter of the surfactant can be removed in a reasonable time. The compositions of the surfactants employed and set forth in Table 1 are as follows: (1) sodium salt of isopropylnaphthalene sulfonic acid Alkanol XC (Dupont) (2) sodium decyl sulfate (3) sodium dodecyl sulfate ( 4 ) Aerosol-MA (American Cyanamid) (5 ) Di-ethylpentyl sodium sulfosuccinate (6 ) Aerosol-OT (American Cyanamid) (9) Sodium Dodecylbenzene Sulfonate ♦ average of four runs each having a different isomer ratio.

Claims: Claims : I. A method of making fine particle photographic coupler dispersions which comprises forming a dispersion of photographic coupler, coupler solvent and auxiliary coupler solvent in an aqueous gelatin medium containing at least about 1% by weight of an anionic surfactant having a hydrophobicity of 2-10 log P(OH) and washing the dispersion with water for a time sufficient to remove at least one-fourth of the surfactant. 2. The method of claim 1 wherein the hydrophobicity of the surfactant is from 2.5 to 7. 3. The method of claim 1 wherein the hydrophobicity of the surfactant is from 4 to 6.7. 4. The method of claim 1 wherein the surfactant is present in the amount of 1 to 5 percent by weight. 5. The method of claim 1 wherein the surfactant is an alkaline metal salt of an alkarylene sulfonic acid. 6. The method of claim 1 wherein the surfactant is an alkaline metal salt of an alkyl sulfosuccinate. 7. The method of claim 5 wherein the surfactant is the sodium salt of isopropylnaphthalene sulfonic acid. 8. The method of claim 5 wherein the surfactant is the sodium salt of dodecylbenzene sulfonic acid. 9. The method of claim 1 wherein the surfactant is sodium decyl sulfate. 10. The method of claim 1 wherein the surfactant is sodium decyl sulfate. II. The method of claim 1 wherein the surfactant is sodium dodecyl sulfate. 12. The method of claim 6 wherein the surfactant is sodium bis(2-ethythexyl) succinic sulfonate. 13. The method of claim 6 wherein the surfactant is diethylpentyl sodium sulfosuccinate. 14. The method of claim 6 wherein the surfactant is dimethylpentyl sodium sulfosuccinate. 15. The method of claim 1 where the surfactant has the formula 16. The method of claim 1 wherein the surfactant has the formula

Inventors: SAWYER JOHN F, ZENGERLE PAUL L, SAWYER, JOHN, F., ZENGERLE, PAUL, L.
Applicants: EASTMAN KODAK CO, EASTMAN KODAK COMPANY
Application year: 1992
Main classification: G03C1
IPC codes: G03C1, G03C7