Surfactants and hydrophilic colloid compositions and materials containing them

FIELD OF INVENTION
The invention relates to surfactants and their use as dispersing aids in the preparation of hydrophilic colloid compositions having hydrophobic particles dispersed therein. Such compositions may be used in the preparation of multilayer photographic materials.
BACKGROUND OF THE INVENTION
A wide variety of surfactants have been described for use in the preparation of photographic materials.
JP56-19042 describes various diester sulfoitaconates as dispersing aids for photographic additives. The two ester linked hydrophobic groups include a number of substituted or unsubstituted alkyl or aryl groups.
U.S. Pat. No. 3,948,663 describes photographic materials containing certain sulfosuccinate surface active agents and refers to their possible use as dispersing aids and coating aids. A specific example of such a surface active agent is sodium dioctyl sulfosuccinate which is commercially available as Aerosol.TM.OT.
W093/03420 describes 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. Artionic surfactants of diverse structures may be employed and included among several named surfactants is diphenylbutyl sodium sulfosuccinate.
A shortcoming of the use of surfactants described in JP56-19042 and U.S. Pat. No. 3,948,663 is the very low surface tension values exhibited by the compounds at concentrations above their critical micelle concentration (CMC). In the simultaneous multilayer coating of hydrophilic colloid layers, it is essential that the surface tension of the top layer is lower than that of any of the underlying layers if it is to remain spread during the coating operation. If one of the underlying layers has a lower surface tension than the top layer it drives the top layer in from the edges towards the centre of the coating. This is often termed "edge retraction". The larger the surface tension imbalance, the more disruptive is the effect. Large differences can cause retraction of the whole coating pack and general layer inversions. The surface tension of underlying layers in the multilayer coating of photographic materials is often dominated by the surfactant dispersing aid that is used to stabilize the emulsified hydrophobic particles therein e.g. colour couplers and their associated solvents.
When such prior art surfactants are used as dispersing aids for emulsified materials that are incorporated in underlying hydrophilic colloid layers during simultaneous multilayer coating, a constraint is put on the choice of surfactant or surfactant concentration required for the overlying layers i.e. coating latitude is relatively narrow.
Another shortcoming of the use of the surfactants described in JP56-19042 and U.S. Pat. No. 3,948,663 as dispersing aids for photographic couplers in hydrophilic colloid compositions is that the photographic properties of such compositions e.g. the liquid dispersion reactivity, can be less than desired.
A further shortcoming of the use of the surfactants described in JP56-19042 and U.S. Pat. No. 3,948,663 as dispersing aids in photographic materials is that they can contribute to foaming during photographic processing, especially in seasoned developers where surfactants have leached out from the material and have built up in concentration.
Problem to be Solved by the Invention
The invention overcomes the coating latitude problem associated with the prior art dipersing aids.
Limitations in the photographic properties of dispersions of photographic couplers in hydrophilic colloids can be overcome.
The invention can reduce the foaming which can occur during the processing of photographic materials containing the prior art dispersing aids.
SUMMARY OF THE INVENTION
The invention provides compounds having the structure ##STR2## wherein R is H or methyl provided that when each n=1, each R is methyl;
M is a cation; and,
n is an integer from 1 to 6.
The invention also provides a composition comprising a hydrophilic colloid having hydrophobic particles dispersed therein with the aid of a surfactant having the structure I.
A multilayer photographic material comprises a support bearing a plurality of hydrophilic colloid layers including at least one-light-sensitive silver halide emulsion layer wherein at least one of the underlying layers of the material contains hydrophobic particles dispersed therein with the aid of a surfactant having the structure I.
A method of preparing a multilayer photographic material comprises
(a) simultaneously coating on a support a plurality of aqueous hydrophilic colloid layers including at least one light-sensitive silver halide emulsion layer wherein at least one of the underlying layers contains hydrophobic particles dispersed therein with the aid of a surfactant having the structure I, and
(b) drying the coated layers.
Advantageous Effect of the Invention
By providing aqueous hydrophilic colloid melts with high surface tension minima, the invention enables increased coating latitude.
Improved photographic performance can be achieved with dispersions of a photographic coupler in a hydrophilic colloid. The nature of the improvement depends on the type of coupler dispersion. For example, with a microprecipitated dispersion, the benefits include decreased droplet size, increased liquid dispersion reactivity, and increased Dmax in coated product. With a homogenized dispersion, the benefits include increased liquid dispersion reactivity, and increased shoulder density and contrast in coated product.
Another advantage is reduced foam formation during photographic processing, especially in seasoned developer.

DETAILED DESCRIPTION OF THE INVENTION
In structure I, the cation M is a positively charged atom or group of atoms preferably chosen from alkali metal cations e.g. Na.sup.+, or ammonium.
Preferred compounds include those wherein each n is from 2 to 4, and each R is H. In a particularly preferred compound, each n is 3, and each R is H.
The compounds may be water soluble or water dispersible.
The compounds may be prepared by the esterification of maleic acid with a phenylalkanol wherein the alkanol has from 3 to 8 carbon atoms. A specific method which can be used in respect of all the compounds is given below in Example 1.
Compositions comprising a hydrophilic colloid having hydrophobic particles dispersed therein may be formed by a process comprising dispersing a hydrophobic material into an aqueous solution of a hydrophilic colloid in the presence of the surface active agent.
For homogenized dispersions, the surface active agent is used preferably in an amount from 0.4 to 1.2, more preferably from 0.6 to 0.9 weight percent based on the weight of the aqueous dispersion.
For microprecipitated dispersions, the surface active agent is used preferably in an amount that provides a molar ratio of surface active agent: hydrophobic material e.g. photographic coupler which is from 1:4 to 2:1.
Regardless of the particular method of preparation, dispersions can be made in accordance with the invention which avoid the coating latitude problems associated with the prior art by using less than about 1 weight percent of the surfactant and without requiring a washing step to remove at least one fourth of the surfactant.
The invention is particularly useful in the preparation of photographic compositions and materials.
In the following discussion of suitable materials for use in the compositions and materials of this invention, reference will be made to Research Disclosure, December, 1989, Item 308119, published by Kenneth Mason Publications, Ltd., Dudley Annex, 12a North Street, Emsworth, Hampshire, P010 7DQ, UK. This publication will be identified hereafter by the term Research Disclosure.
A number of hydrophobic photographic additives used in light sensitive photographic materials are oil-soluble and are used by dissolving them in a substantially water-insoluble, high boiling point solvent which is then dispersed in an aqueous hydrophilic colloid solution with the assistance of a dispersing aid. Such oil-soluble additives include image forming dye couplers, dye stabilizers, antioxidants and ultra-violet radiation absorbing agents. A typical solvent used to dissolve the additive is aromatic e.g. di-n-butyl phthalate.
Gelatin is the preferred hydrophilic colloid, but other hydrophilic colloids can be used alone or in combination with gelatin.
Suitable methods of preparing photographic dispersions are described in Research Disclosure, Sections XIV A and XIV B. For example, homogenised oil in aqueous gelatin dispersions of photographic couplers can be prepared by dissolving the coupler in a coupler solvent and mechanically dispersing the resulting solution in an aqueous gelatin solution (see U.S. Pat. No. 2,322,027).
Alternatively, microprecipitated dispersions of photographic couplers prepared by solvent and/or pH shift techniques are becoming more widely used (see references: U.K. Patent No. 1,193,349; Research Disclosure 16468, Dec. 1977 pp 75-80; U.S. Ser. No. 288,922 (1988) by K. Chari; U.S. Pat. Nos. 4,970,139 and 5,089,380 by P. Bagchi; U.S. Pat. No. 5,008,179 by K. Chari, W. A. Bowman and B. Thomas; U.S. Pat. No. 5,104,776 by P. Bagchi and S. J. Sargeant) and offer benefits in decreased droplet size and often increased reactivity relative to conventional oil-in-water homogenised dispersions.
Multilayer photographic materials according to the invention comprise one or more underlying layers formed from such compositions.
Preferred multilayer photographic materials include color materials of the type described in Research Disclosure, Sections VII A to VII K.
Methods of preparing multilayer photographic materials by simultaneously coating the layers are known. Particular methods are described in Research Disclosure, Sections XV A and XV B. Such methods include extrusion coating and curtain coating.
The hydrophobic material dispersed in the hydrophilic colloid may be a photographic coupler.
Couplers which form cyan dyes upon reaction with oxidized color-developing agents are described in such representative patents and publications as U.S. Pat. Nos. 2,772,162; 2,895,826; 3,002,836; 3,034,892; 2,747,293; 2,423,730; 2,367,531; 3,041,236; and 4,333,999; and Research Disclosure, Section VII D.
Couplers which form magenta dyes upon reaction with oxidized color developing agents are described in such representative patents and publications as: U.S. Pat. Nos. 2,600,788; 2,369,489; 2,343,703; 2,311,082; 3,152,896; 3,519,429; 3,062,653; and 2,908,573; and Research Disclosure, Section VII D.
Couplers which form yellow dyes upon reaction with oxidized and color developing agents are described in such representative patents and publications as: U.S. Pat. Nos. 2,875,057; 2,407,210; 3,265,506; 2,298,443; 3,048,194; and 3,447,928; and Research Disclosures, Section VII D.
Couplers which form colorless products upon reaction with oxidized color developing agents are described in such representative patents as: UK Patent No. 861,138; U.S. Pat. Nos. 3,632,345; 3,928,041; 3,958,993; and 3,961,959.
The couplers can be dissolved in a solvent and then dispersed in a hydrophilic colloid. Examples of solvents usable for this process include organic solvents having a high boiling point, such as alkyl esters of phthalic acid (for example, dibutyl phthalate, dioctyl phthalate, and the like), phosphoric acid esters (for example, diphenyl phosphate, triphenyl phosphate, tricresyl phosphate, dioctyl butyl phosphate, and the like) citric acid esters (for example, tributyl acetyl citrate, and the like) benzoic acid esters (for example, octyl benzoate, and the like), alkylamides (for example, diethyl laurylamides, and the like), esters of fatty acids (for example dibutoxyethyl succinate, dioctyl azelate, and the like), trimesic acid esters (for example, tributyl trimesate, and the like), or the like; and organic solvents having a boiling point of from about 30.degree. to about 150.degree. C., such as lower alkyl acetates (for example, ethyl acetate, butyl acetate, and the like), ethyl propionate, secondary butyl alcohol, methyl isobutyl ketone, b-ethoxyethyl acetate, methyl cellosolve acetate, or the like. Mixtures of organic solvents having a high boiling point and organic solvents having a low boiling point can also be used.
As the binder or the protective colloid for the photographic emulsion layers or intermediate layers of the photographic light-sensitive material of the present invention, gelatin is advantageously used, but other hydrophilic colloids can be used alone or together with gelatin.
As gelatin in the present invention, not only lime-processed gelatin, but also acid-processed gelatin may be employed. The methods for preparation of gelatin are described in greater detail in Ather Veis, The Macromolecular Chemistry of Gelatin, Academic Press (1964).
As the above-described hydrophilic colloids other than gelatin, it is possible to use proteins such as gelatin derivatives, graft polymers of gelatin and other polymers, albumin, casein, and the like; saccharides such as cellulose derivatives such as hydroxyethyl cellulose, cellulose sulfate, and the like, sodium alginate, starch derivatives, and the like; and various synthetic hydrophilic high molecular weight substances such as homopolymers or copolymers, for example, polyvinyl alcohol, polyvinyl alcohol semiacetal, poly-N-vinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinyl imidazole, polyvinylpyrazole, and the like.
In the photographic emulsion layers or other hydrophilic colloid layers of the photographic light-sensitive material of the present invention can be incorporated various surface active agents as coating aids or for other various purposes, for example, prevention of charging, improvement of slipping properties, acceleration of emulsification and dispersion, prevention of adhesion and improvement of photographic characteristics (for example, development acceleration, high contrast, and sensitization), and the like
Surface active agents which can be used are nonionic surface active agents, for example, saponin (steroid-based), alkyene oxide derivatives (for example, polyethylene glycol, a polyethylene glycol/polypropylene glycol condensate, polyethylene glycol alkyl ethers or polyethylene glycol alkylaryl ethers, polyethylene glycol esters, polyethylene glycol sorbitan esters, polyalkylene glycol alkylamines or polyalkylene glycol alkylamides, and silicone/polyethylene oxide adducts, and the like), glycidol derivatives (for example, alkenylsuccinic acid polyglyceride and alkylphenol polyglyceride, and the like), fatty acid esters of polyhydric alcohols and alkyl esters of sugar, and the like; anionic surface active agents containing an acidic group, such as a carboxy group, a sulfo group, a phospho group, a sulfuric acid esters group, and a phosphoric acid ester group, for example, alkylcarboxylic acid salts, alkylsulfonic acid salts, alkylbenzenesulfonic acid salts, alkylnaphthalenesulfonic acid salts, alkylsulfuric acid esters, alkylphosphoric acid esters, N-acyl-N-alkyltaurines, sulfosuccinic acid esters, sulfoalkylpolyoxyethylene alkylphenyl ethers, and polyoxyethylene alkylphosphoric acid esters; amphoteric surface active agents, such as amino acids, aminoalkylsulfonic acids, aminoalkylsulfuric acid or aminoalkylphosphoric acid esters, alkylbetaines, and amine oxides; and cationic surface active agents, for example, alkylamine salts, aliphatic or aromatic quaternary ammonium salts, heterocyclic quaternary ammonium salts (for example, pyridinium and imidazolium) and aliphatic or heterocyclic phosphonium or sulfonium salts.
In the photographic emulsion layer of the photographic light-sensitive material used in the present invention, any of silver bromide, silver iodobromide, silver iodochlorobromide, silver chlorobromide and silver chloride may be used as the silver halide.
The light-sensitive silver halide contained in the photographic material can be processed following exposure to form a visible image by associating the silver halide with an aqueous alkaline medium in the presence of a developing agent contained in the medium or the material. Suitable types of photographic processing are described in Research Disclosure, Section XIX A to XIX J. Suitable developing agents are described in Research Disclosures, Section XX A to XX B.
The following Examples further illustrate the invention.
A number of compounds referred to in the Examples are as follows: ##STR3##
EXAMPLE 1
Synthesis of sodium di(4-phenylbut-1-yl) sulfosuccinate
All sodium sulfosuccinate surfactants were prepared following the general method outlined below: A solution of maleic anhydride (32.6 g,0.33 mol), 4-phenyl-1-butanol (100.0 g, 0.66 mol) and concentrated sulfuric acid (1.5 cm.sup.3) was suspended in toluene(750 cm.sup.3) and refluxed for 16 hours in a flask equipped with a Dean and Stark trap. On cooling, the toluene solution was reduced to 1/4 volume at reduced pressure on a rotary evaporator and washed with saturated sodium hydrogen carbonate (2.times.200 cm.sup.3) and then with water (2.times.200 cm.sup.3). The organic layer was dried over magnesium sulfate and the solvent removed at reduced pressure (15 mmHg, 50.degree. C.) to give an intermediate diester as a clear oil (119.5 g, 95%).
A solution of sodium metabisulfite (65.7 g, 0.34 mol) in water (400 cm.sup.3) was added to a solution of this diester (119.5 g, 0.31 mol) in ethanol (400 cm.sup.3) and the mixture brought to reflux over 15 minutes. Sodium sulfite (36.0 g, 0.28 mol) was then added portionwise to the mixture over 40 minutes and the reaction then allowed to reflux overnight for convenience. The reaction mixture was evaporated to dryness (15 mm Hg, 50.degree. C.) and then extracted into ethyl acetate (1.5 L, hot) and filtered. The ethyl acetate solution was concentrated and allowed to cool to give the product as a white crystalline solid (139.8 g, step yield 93%, overall yield 87%).
Spectroscopic and 1 Hnmr data was consistent with the proposed product, sodium di (4-phenylbut-1-yl) sulfosuccinate.
EXAMPLE 2
Tables IA and IB compare the surface tension data of the compounds of the invention with commercial examples of dialkyl sulfosuccinate, Aerosol.TM.MA (sodium dihexyl sulfosuccinate) , Aerosol.TM.OT (sodium diisooctyl sulfosuccinate) and Aerosol.TM.AY (sodium dipentyl sulfosuccinate). The method used for surface tension measurements is as follows.
The measurement of surface tension of an aqueous solution containing surfactant was measured over a concentration range including the critical micelle concentration using the Wilhelmy technique (Padday, J. F., 2nd Int. Congress of Surface Activity, I, 1, 1957) with a platinum blade. Comparative dynamic surface tension measurements were also determined by the same technique using an overflowing circular weir (ibid.). The average surface age of the solutions in the overflowing weir has been estimated to be of the order of 0.1 seconds.
TABLE IA______________________________________Surface Tension (mN/m) of Solutions inWater at 25.degree. C.CompoundsTested Concentration wt % in Water CMCInvention 0.25% 0.5% 1.0% wt %______________________________________n = 2, R = Me 44.9 40.3 39.0 0.64n = 2, R = H 37.6 37.6 37.9 0.23n = 3, R = H 42.1 41.7 40.2 0.10n = 4, R = H -- -- 37.5 --______________________________________
TABLE IB______________________________________Surface Tension (mN/m) of Solutions inWater at 25.degree. C. (Trade Literature)CompoundsTested Concentration wt % in Water CMCComparisons 0.25% 0.5% 1.0% wt %______________________________________Aerosol OT 27.5 26.0 26.0 .about.0.07Aerosol MA 38.2 30.8 27.8 0.6-0.7Aerosol AY 41.6 35.2 29.2 0.9-1.2______________________________________
Tables IA and IB show clearly that once the concentrations of the surfactants approach or go beyond their CMC where surface tension values tend to plateau, the compounds of this invention exhibit much higher values of surface tension than the corresponding dialkyl equivalents. Equivalents denote compounds of similar CMC. On comparing equivalent compounds at such concentrations, the materials of this invention show surface tension values that are 10-14 mN/m higher.
Tables IIA and IIB show similar data to Tables IA and IB, but the measurements were conducted in solutions containing 7% deionised Type IV bone gelatin in water at 40.degree. C. to simulate a coating melt.
TABLE IIA______________________________________Surface Tension (mN/m) of Solutions in 7%Deionised Type IV Bone Gelatin Water at40.degree. C. (Compounds of This Invention)Compounds Wt % Concentration in 7%Tested Deionised Gelatin solution CMCInvention 0.03% 0.10% 0.30% wt %______________________________________n = 2, R = Me 49.4 44.9 41.8 .about.0.3n = 2, R = H 49.5 44.2 43.3 .about.0.1n = 3, R = H 43.2 42.8 42.8 .about.0.03n = 4, R = H 42.1 41.7 40.7 .about.0.01______________________________________
In the following Table, the comparison compounds are sulfosuccinates having the formula ##STR4##
TABLE IIB______________________________________Surface Tension (mN/m) of Solutions in 7%Deionised Type IV Bone Gelatin Water at40.degree. C. (Comparison Compounds)Compounds Wt % Concentration in 7%Tested Deionised Gelatin solution CMCComparisons 0.03% 0.10% 0.30% wt %______________________________________Aerosol OT 29.2 28.9 28.7 .about.0.01Aerosol MA 41.9 36.3 31.4 .about.0.1R.sup.1 = n-hexyl 37.0 32.0 30.0 .about.0.1R.sup.1 = n-pentyl 46.0 39.9 34.4 .about.1.3______________________________________
Tables IIA and IIB also show clearly that once the concentrations of the surfactants approach or go beyond their CMC in aqueous gelatin solution, the compounds of this invention still exhibit much higher values of surface tension than the corresponding dialkyl equivalents. On comparing equivalent compounds at such concentrations, the materials of this invention again show surface tension values that are 10-14 mN/m higher.
In general therefore, the materials of this invention offer the advantage of relatively high surface tension minima coupled with reasonably low CMCs (up to 0.3 weight % in 7% gelatin in water) in situations where low values are undesirable, e.g. in underlying layers during simultaneous multilayer coating.
EXAMPLE 3
Increased Coating Latitude Using Materials of Invention as Dispersing Aid in Underlying Layers During Simultaneous Multilayer Coating
To show that the compounds of this invention permit a wider coating latitude when used as dispersing aids in the underlying layer of a simultaneous two layer coating, the following format was coated at 15 m/min at 40.degree. C. with a range of different surfactants:
______________________________________TOP LAYER 10% type IV regular bone gelatincoated at containing 0.3 wt % surfactant and10.8 ml/m.sup.2 a blue dye marker.(1 ml/ft.sup.2)BOTTOM LAYER coupler dispersion (coupler Icoated at or II) diluted to 4% gelatin by59 ml/m.sup.2 weight with water containing a(5.5 ml/ft.sup.2) red dye marker.12.7 cm (5 ins) wide polyethylene terephthalatefilm base (suitably subbed to give good adhesionto gelatin)______________________________________
Bottom layer
A dispersion of a colour coupler was made according to the following recipes:
2 kg Dispersion of Coupler I
258 g of coupler I was dissolved in a mixture of 65 g di-n-butyl phthalate and 65 g of solvent III at 145.degree. C. to make Solution A. 176 g of gelatin was dissolved in 1354 g of water containing 17.6 g of dispersing aid (surfactant under test) and 31 g of propionic acid/sodium proprionate preservative to make Solution B. After heating Solution B to 80.degree. C., solution A was added to Solution B and the whole mixture was immediately homogenised for 5 minutes at 10,000 rpm with a Kinematica Polytron homogeniser fitted a 35 mm diameter head.
1.7 kg Dispersion of Coupler II
149 g of coupler II was dissolved in a mixture of 58.5 g di-n-butyl phthalate, 22.3 g of solvent III, 79.1 g. of stabiliser IV and 14.9 g of scavenger V at 145.degree. C. to make Solution C. 149 g of gelatin was dissolved in 1180 g of water containing 16.4 g of dispersing aid (surfactant under test) and 32.7 g of propionic acid/sodium propionate preservative to make Solution D. After heating Solution D to 80.degree. C., solution C was added to Solution D and the whole mixture was immediately homogenised for 5 minutes at 10,000 rpm with a Kinematica Polytron homogeniser fitted with a 35 mm diameter head.
The coupler dispersion, which contained approximately 9% gelatin by weight, was then diluted at 40.degree. C. to a gelatin content of 4 wt % with water which contained a red dye marker. The resulting mixture was used for the bottom layer of a two layer hopper coating as illustrated above.
Thus a range of bottom layer coating melts were made which differed in the dispersion component, the major difference being the dispersing aid (surfactant) used. The main objective was to compare four diarylalkyl sulfosuccinate dispersing aids of this invention with two commercial dialkyl sulfosuccinate dispersing aids and the commercial surfactant Alkanol.TM.XC (sodium triisopropyl naphthalene sulphonate). Two types of coupler, I and II, were used for making the coupler dispersions. It should be noted for each coupler used that the comparisons of surfactants were between compounds of similar hydrophilic-lipophilic balance, i.e. of similar CMC.
Top Layer
Four different surfactants were selected for the top layer coating aid to produce a range of characteristic values of minimum surface tension, 25.5-37.2 mN/m. A working concentration of 0.3% was chosen to ensure that the surfactants were being used well beyond their CMC in order that the surface tensions of their respective solutions under dynamic conditions were very similar to those under static conditions and therefore essentially at a characteristic plateau value. The method used for estimating a dynamic value of surface tension is described Example 2. The materials chosen are listed in the following table together with representative surface tension data.
TABLE III______________________________________Surface Tension DataSurfactant (0.3 wt %Concentration in 7%by wt Type IV Bone Dynamic Surface Static SurfaceGelatin in Water + Tension TensionBlue Dye mN/m mN/m______________________________________Aerosol OT (AOT) 25.5 25.5Triton X-100 (TX100) 30.5 30.2Texofor FN15 (TFN15) 34.7 34.4SDS 37.3 37.2______________________________________ Triton .TM. X100 is toctylphenyl polyethyleneoxide (9.5 moles). Texofor .TM. FN15 is nonylphenyl polyethyleneoxide (15 moles). SDS is sodium dodecyl sulphate.
A complete 4.times.7 matrix of two layer coatings were made, coating the four types of top layer over the seven types of bottom layer. The dried coatings were then examined to determine whether the top layer had coated successfully over the underlying Layer. The coating was deemed successful (OK) if the blue top layer had remained satisfactorily spread over the full width of the coating, and deemed unsuccessful if the bottom layer had caused the top layer to retract from either the edges or if there was multi-cratering in the middle of the coating due to the bottom layer pushing through to the surface. With the red dye in the lower layer and the blue dye in the upper layer, it was extremely clear when the coating was unsuccessful. Table IV summarises the coating results taken from representative strips:
TABLE IV______________________________________Coating Results - Different Surfactantsin Top LayerDispersingAid used: Top Layer Surfactant(in bottom AOT TX100 TFN15 SDSlayer Surface Surface Surface Surfacedispersion Tension Tension Tension Tensioncomponent) 25.5 mN/m 30.5 mN/m 34.7 mN/m 37.3 mN/m______________________________________n = 2, OK OK OK OKR = Me(usingcoupler I)n = 2, OK OK Slight SlightR = H fine edge(using multiple retractioncoupler I) cratering 1-2 cratersn = 3, OK OK OK OKR = H(usingcoupler II)n = 4, OK OK OK OKR = H(usingcoupler II)Aerosol MA OK Slight Severe Total(using edge retraction retractioncoupler I) retraction of both of top 40 .times. 8 mm layers and layer into large multiple fine crater cratering stripesAerosol OT OK Severe Severe Total(using retraction retraction retractioncoupler II) of both of both of top layers and layers and layer and multiple multiple >50% large large retraction cratering cratering of bottom layerAlkanol XC OK OK 3-4 mm of Severe(using edge retractioncoupler II) retraction of both plus layers and longitudi- large nal break- cratering through and cratering______________________________________
The above results from the two layer coatings clearly show that there is a large increase in coating latitude when the surfactants of this invention are used as the dispersing aids for dispersions in underlying layers during multi-layer coating relative to the comparison compounds. As previously explained and demonstrated here, this means the use of the dispersing aids of this invention puts less constraint upon the choice of surfactant coating aid required in the top layer for good coating. Logically therefore, there should also be less constraint upon the concentration of a coating aid required to give good coating. This aspect is demonstrated in Table V where Aerosol.TM.OT was used as the coating aid in the top layer over a range of concentrations, using the same coating conditions as before.
TABLE V______________________________________Coating Results - Different Concentrationsof Coating Aid AOT in Top LayerDispersingAid used: Top Layer Surfactant(in bottom AOT AOT AOT AOTlayer Concent- Concent- Concent- Concent-dispersion ration ration ration rationcomponent) 0.02% 0.03% 0.05% 0.07%______________________________________Inventionn = 2, R = H OK OK OK OK(usingcoupler I)n = 3, R = H OK OK OK OK(usingcouplerII)ComparisonCompoundsAerosol MA Retraction Retraction OK OK(using from edges from edgescoupler I) and and longitud- longitid- inal unal break- break- through of through of bottom bottom layer layerAerosol OT Retraction Edge Slight Very(using of both retraction edge slightcoupler layers and and retract- edgeII) multiple multiple ion of retract- cratering longtid- top layer ion of inal top coating layer breaks______________________________________
EXAMPLE 4
Photographic Benefits with Microprecipitated Dispersions
Increased dispersion reactivity
Microprecipitated dispersions of photographic couplers, prepared by solvent and/or pH shift techniques are becoming more widely used and offer benefits in decreased droplet size and often increased reactivity relative to conventional oil-in-water homogenised dispersions. When microprecipitated dispersions are prepared using the compounds of this invention, these benefits are increased.
The microprecipitated dispersions were made according to the following method:
The coupler (20 g) was dissolved in a mixture of propan-1-ol (40 g) and 20% sodium hydroxide solution (5 g) at 60.degree. C. and poured into a solution of surfactant (weight equimolar with coupler) and polyvinylpyrrolidone (10 g) in water(600 g). The resulting micellar solution was reduced to pH 6.0 by the dropwise addition of 15% propanoic acid, to form the crude microprecipitated dispersion which was then dialysed through Amicon hollow fibre ultrafiltration cartridges and concentrated to a fifth of its volume.
The liquid dispersion reactivity measurements were made according to the following method. Particle size was measured by photon correlation spectroscopy.
The method used is similar to that described by Bagchi in U.S. Pat. Nos.: 4,970,139; 5,089,380 and 5,104,776. A sample of the dispersion was mixed with a developer solution which contained sodium sulphite, CD-3 developer and EDTA. This was mixed with an activator solution which contained the oxidant sodium persulfate, and a buffer of sodium carbonate and sodium bicarbonate, which brought the pH of the final solution to 10.1 (close to that of processing solutions). The concentrations of oxidant and coupler are much greater than that of the developer. The effect of this is that the oxidant generates oxidised developer which then reacts with the coupler (or with the competing sulfite) to form image dye and side products. The optical density of the dye was then read spectrophotometrically so that for a known dye extinction coefficient, the concentration of the dye could be derived.
If the coupling reaction is treated as a homogeneous, single phase reaction the kinetics of the coupling reaction can be calculated. The coupling reaction and the competing reaction of sulphite with oxidised developer are both assumed to be second order. Remembering that coupler and oxidant concentrations are greater than that of developer, the following expression is derived for the rate constant of the coupling reaction, k.sub.1 which is used as a measure of liquid dispersion reactivity:
k.sub.1 =k.sub.2 ln[a/(a-x)]/ln[b/(b-c+x)]
where k.sub.2 is the sulfonation rate constant (previously calculated), a is the coupler concentration, b is the sulfite concentration, c is the developer concentration and x is the concentration of dye.
TABLE VI______________________________________Microprecipitated dispersions of CouplerVI data.SURFACTANT Liquid Mean(dispersing Dispersion Particleaid) Reactivity Diameter (nm) Comment______________________________________SDS 9545 20.3 comparisonSDBS 5200 25.8 "Aerosol OT 4500 66.0 "Aerosol MA 4575 21.6 "Aerosol AY 4220 20.9 "TPE-STC 1730 19.2 "TPME-STC 203 20.9 "n = 4, R = H 15100 13.0 inventionn = 3, R = H 14425 8.9 "n = 2, R = H 10130 18.5 "n = 1, R = Me 7555 17.8 "n = 1, R = H 4155 20.3 comparison______________________________________
The above results show clearly that the compounds of this invention:
(i) Increase liquid dispersion reactivity as hydrophobic chain length increases. (Note: phenyl propyl is minimum chain length to give increased reactivity thus demonstrating why shorter chains such as phenylethyl lie outside the invention);
(ii) Enhance liquid dispersion reactivity relative to the aliphatic (i.e. non-phenyl ending) sulfosuccinates;
(iii) Boost liquid dispersion reactivity relative to other commonly available anionic dispersing aids, such as sodium dodecyl sulphate (SDS) and sodium dodecylbenzene sulphonate (SDBS);
(iv) Increase liquid dispersion reactivity relative to the tri-chain phenyl-ended sulphonates, such as TPE-STC (tri-2-phenylethyl sulfotricarballylate) and TPME-STC (tri-2-phenyl-2-methylethyl sulfotricarballylate) (U.S. Pat. No. 4,988,610), thus demonstrating that the 2 hydrophobic chain geometry of the materials of this invention is critical to their performance;
(v) Decrease particle size, especially with the longer hydrophobic chain examples of the invention, relative to other anionic surfactants, such as SDS, SDBS, aliphatic sulfosuccinates and phenyl-ended sulfotricarballylates.
Increased Dmax
When coatings are made of the most reactive microprecipitated dispersions, the examples of the invention show the highest Dmax.
Monochrome coatings of the microprecipitated dispersions were made according to the procedures outlined.
A monochrome bilayer format was used for the photographic evaluation of the coupler dispersions:
______________________________________Layer 2 Gelatin 1.614 g/m.sup.2 Alkanol XC 21.5 mg/m.sup.2 BVSME 64.0 mg/m.sup.2Layer 1 Gelatin 1.614 g/m.sup.2 Coupler VI 0.836 mmoles/m.sup.2 Silver (as chloride 239.0 mg/m.sup.2 emulsion)Support Resin-coated paper______________________________________
The two layers were coated simultaneously.
The coatings were exposed to white light for 0.1s through a 21 step 0.15 logE increment tablet and processed in standard RA-4 chemistry. Reflection Dmax of each coating was measured using an X-Rite model 414 reflection densitometer. The results were as follows:
TABLE VII______________________________________Coatings of Coupler VI microprecipitateddispersions.SURFACTANT Dmax Comment______________________________________SDS 2.99 comparisonSDBS 2.73 comparisonn = 3, R = H 3.39 inventionn = 2, R = H 3.19 inventionn = 1, R = H 2.71 comparison______________________________________
Table VII shows:
(i) Dmax increases with increasing hydrophobic chain length for the materials of the invention;
(ii) Higher Dmax are obtained with the longer chain length compounds of this invention than for the commonly available anionic dispersing aids such as SDS and SDBS;
(iii) The advantages of higher Dmax are not seen with the short phenyl-ended sulfosuccinates which are outside the scope of this invention.
Photographic Benefits with Homogenised Oil-in-Aqueous Gelatin Dispersions of Colour Couplers
Increased contrast and shoulder density
Traditionally colour couplers are dissolved in a high-boiling, water-insoluble solvent and mechanically dispersed in an aqueous gelatin solution containing surfactant to facilitate dispersion. Mean droplet sizes are usually significantly larger (typically, 0.2 .mu.m) than those produced by microprecipitation techniques (typically, 0.02 .mu.m).
The homogenised dispersions were made according to the following technique:
A dispersion was made of the following general formula:
______________________________________Coupler VI 11.7%di-n-butylphthalate 3.9%gel 9.5%water & surfactant 74.8%______________________________________
Coupler VI was dissolved in di-n-butyl phthalate and heated at 140.degree. C. until the coupler had completely dissolved. Gelatin was dissolved in water and heated to 70.degree. C. Surfactant was added to the gelatin solution at a rate of 0.1 mole equivalent to coupler. The coupler solution was then added to the gelatin solution and homogenised for 3 minutes using a Kinematica Polytron set at 10,000 rpm and then passed (twice) through a Microfluidics Microfluidiser (model no. 110E) which was run at 68.95 MPa (10,000 psi) pressure and a water bath temperature of 75.degree. C.
The coatings were made as described above and were exposed to white light for 0.1s through a 21 step 0.15 logE increment tablet and processed in standard RA-4 chemistry. The contrast, Dmax, Dmin and shoulder densities were measured using an X-Rite model 414 reflection densitometer and are shown in Table VIII
In the following Table, the comparison surfactant types are as follows:
TABLE VIII______________________________________Type A - SulfonateType B - SulfosuccinateType C - Sulfoitaconate having the formula ##STR5##Type D - Sulfoglutaconate having the formula ##STR6##Measurements of coated dispersions ofcoupler VI made with different surfactants. Contrast Shoulder Dmax DminSurfactant .+-.0.06 .+-.0.03 .+-.0.02 .+-.0.003 Comment______________________________________Type A 3.45 1.91 2.32 0.111 compSDBSType BA-OT 3.56 1.94 2.42 0.110 compn = 4, R = H 3.72 1.99 2.40 0.112 invn = 3, R = H 3.77 2.01 2.51 0.113 invn = 2, R = H 3.80 2.00 2.52 invn = 1, R = Me 3.73 2.00 2.44 0.113 invn = 1, R = H 3.28 1.87 2.23 0.109 compn = 0, R = H 3.39 1.89 2.36 0.112 compType Cn = 0 3.63 1.95 2.35 0.114 compn = 1 3.63 1.95 2.47 0.110 compn = 2 3.59 1.93 2.40 0.112 compn = 3 3.34 1.86 2.30 0.115 compType Dn = 0 3.46 1.92 2.31 0.114 compn = 3 3.56 1.95 2.39 0.109 comp______________________________________
For homogenised dispersions of coupler VI, the materials of the invention clearly show:
(i) Increased contrast and increased shoulder density relative to aliphatic, non phenyl-ended sulfosuccinates such as Aerosol OT; conventional anionic surfactants such as SDBS .omega.-arylalkyl phenyl-ended sulfoitaconates and sulfoglutaconates; and the shorter chain phenyl-ended sulfosuccinates which are outside the scope of this invention;
(ii) The shorter chain phenyl-ended sulfosuccinates which are outside the scope of this invention also show significantly lower Dmax emphasising the importance of chain length for the materials of this invention;
(iii) No significant Dmin penalty.
In summary, the phenyl-ended sulfosuccinate dispersing aids of this invention show advantages over a wide variety of chemically similar materials when used in the photographic context described.
Increased liquid dispersion reactivity
Dispersions of couplers I and II were made according to the procedures shown in Example 3. The liquid dispersion measurements were made as described above and are presented in Table IX.
TABLE IX______________________________________Liquid dispersion data for homogeniseddispersions of couplers I and II. Liquid dispersion reactivity rate constantsSurfactant Coupler I Coupler II Comments______________________________________Aerosol OT 1820 12600 comparisonAlkanol XC 3920 10230 comparison (.+-.390)n = 2, R = H 4690 19100 invention (.+-.140)n = 3, R = H 4400 15800 invention______________________________________
Table IX clearly shows Chat for coupler I and coupler II dispersions, the materials of the invention boost liquid dispersion reactivity relative to aliphatic, non-phenyl ended sulfosuccinates, such as Aerosol.TM.OT, and a conventional anionic surfactant, such as Alkanol.TM.XC.
EXAMPLE 5
Low Foaming in Developer
Foaming can cause serious problems during photographic processing especially in seasoned developers where surfactants have leached out from the photographic product and built up in concentration. These foams can cause solution overflow, solution loss, uneven development and solution carry over into successive processing tanks.
To demonstrate that one of the preferred materials of this invention showed a lower propensity to foaming, tests were conducted with a simulated seasoned developer based on colour developer ECP-2b using the Ross-Miles foam test.
The test was first devised by Ross and Miles (Ross, J. and G D Miles, Am. Soc. for Testing Materials, Method D1173-53, Philadelphia, Pa. 1953; Oil and Soap 18, 99, 1941). This test involves placing some solution in both a lower and upper reservoir; the solution passes out of the upper reservoir through a specific orifice (2.9 mm i.d.), drops freely through a specified distance (initially 90 cm), then splashes into the lower reservoir. The foam so formed is measured immediately after the upper reservoir is empty, then again 5 minutes later. Foam stability is then assessed as the percentage of the height remaining after 5 minutes relative to the initial height of the foam. Obviously the lower the percentage the lower the foam stability.
To simulate seasoned developer, solutions of ECP-2b were made up at 37.degree.-38.degree. C. such that each solution contained 0.006 wt % gelatin and 0.002 wt % surfactant. Each surfactant was tested independently in this format.
In the following Table, Foam Stability is defined as Foam (5 min)/Foam (0 min).times.100%.
TABLE X______________________________________Ross-Miles Foam Tests Foam Foam FoamSurfactant (0 min) (5 min) stability______________________________________ComparisonsControl (none) 21 mm 1 mm 5Aerosol OT 60 mm 59 mm 98Alkanol XC 57 mm 53 mm 93Olin 10G 35 mm 31 mm 89FT248 38 mm 29 mm 76Inventionn = 3, R = H 37 mm 15 mm 41______________________________________ Olin .TM. 10G is nonylphenyl decaglycidol FT248 is tetraethylammonium perfluorooctane sulphonate.
Table X demonstrates that one of the preferred materials of this invention(n=3, R=1) produces significantly less foam in the simulated seasoned developer than the corresponding aliphatic sulfosuccinate, Aerosol.TM.OT, and significantly less foam than examples of other surfactants that may be found in photographic products, e g Alkanol.TM.XC Olin 10G and FT248

Number	Name	Date
2949360	Julian	Aug 1960
3948663	Shiba	Apr 1976
4988610	Pitt et al.	Jan 1991
5135844	Bagchi et al.	Aug 1992
5380628	Sawyer et al.	Jan 1995

Number	Date	Country
0560457	Sep 1993	EPX
9303420	Feb 1993	WOX

Surfactants and hydrophilic colloid compositions and materials containing them

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