Methods of preparation of precipitated coupler dispersions with increased photographic activity

Base and auxiliary solvent solubilized precipitated dispersions of couplers and other photographic materials usually produce very small particle dispersions, and usually such dispersions are extremely highly reactive because of the smallness of the particle size. However, some relatively more hydrophobic couplers, even though they produce small particles when a dispersion is formed by the precipitation technique, lead to extremely unreactive dispersions. The method of this invention constitutes a single step precipitation technique where a permanent high boiling water insoluble coupler solvent is incorporated into the precipitated particles to produce photographically highly active coupler dispersions. The invention is performed by providing a first flow of a crude emulsion of a high boiling water insoluble permanent coupler solvent in aqueous surfactant solution and a second flow comprising a basic solution of the coupler in a water miscible volatile auxiliary solvent and mixing the said first and second streams either simultaneously or immediately following thereof, neutralizing said streams with an acid solution. Such immediate neutralization protects any hydrolizable surfactants that may be utilized in the crude emulsion stream. In a preferred method, the first and the second stream may be brought together immediately prior to neutralization or directly into a mixer with addition of acid directly into the mixer to neutralize the dispersion to form a dispersion of fine particles.

FIELD OF THE INVENTION 
This invention relates to the formation of dispersions of photographic 
materials by precipitation from solution. It particularly relates to the 
formation of coupler dispersions by shift of pH. It particularly relates 
to precipitation in the presence of a coarse dispersion of a permanent 
solvent, which gets loaded into the precipitated coupler dispersion and 
results in a high activity photographic coupler dispersion. 
PRIOR ART 
It has been known in the photographic arts to precipitate photographic 
materials, such as couplers, from solvent solution. The precipitation of 
such materials can generally be accomplished by a shift in the content of 
a water miscible solvent and/or a shift in pH. The precipitation by a 
shift in the content of water miscible solvent is normally accomplished by 
the addition of an excess of water to a solvent solution. The excess of 
water, in which the photographic component is insoluble, will cause 
precipitation of the photographic component as small particles. In 
precipitation by pH shift, a photographic component is dissolved in a 
solvent that is either acidic or basic. The pH is then shifted such that 
acidic solutions are made basic or basic solutions are made acidic in 
order to precipitate particles of the photographic component which is 
insoluble at that pH. 
United Kingdom Patent No. 1,193,349 Townsley et al discloses a process 
wherein an organic solvent, aqueous alkali solution of a color coupler is 
mixed with an aqueous acid medium to precipitate the color coupler. It is 
set forth that the materials can either be utilized immediately, or 
gelatin can be added to the dispersion and chilled and remelted for use at 
a later date. 
In an article in Research Disclosure, December, 1977, entitled "Process for 
Preparing Stable Aqueous Dispersions of Certain Hydrophobic Materials", 
pages 75-80, by William J. Priest, it is disclosed that color couplers can 
be formed by precipitation of small particles from solutions of the 
couplers in organic auxiliary solvents. 
Such precipitated dispersion particle formation processes have been 
successful in forming laboratory quantities of photographic materials. It 
is not believed that such dispersion particle formation of photographic 
materials has been successfully scaled up for commercial utilization. One 
difficulty with scaling up for commercial utilization is that the large 
quantities required do not successfully lend themselves to the batch 
techniques utilized in laboratory formation. A continuous technique would 
be desirable. Certain surfactants are potent in the formulation of such 
dispersions, but contain chemical linkages that are hydrolyzed by base in 
the high pH solution of the coupler. This causes problems with scaling up, 
in both batch and continuous processes where considerable loss of the 
surfactant by hydrolysis is encountered. This problem is particularly 
severe in commercial or large volume production where, because of the 
large volumes involved, the time of wait before neutralization of the 
micellar solution is very long (greater than 1/2 to 2 hours). The micellar 
solution is the basic coupler solution mixed with the aqueous surfactant 
solution, at highly alkaline pH, prior to neutralizing with acid. When the 
surfactant hydrolyzes, the particles from lack of enough stabilizer form 
larger particles that are, in many cases, less reactive and therefore 
undesirable. Time required in equipment preparation in pilot scale or full 
scale manufacturing may make it necessary for such solutions to sit for 
periods of time up to several hours. It is necessary to adJust the pH of 
the basic coupler containing solution to slightly acid (about pH 6) to 
effect the formation of the dispersion. The addition of the neutralizing 
acid to large volumes of material cannot be performed rapidly enough to 
prevent formation of large particulate dispersions. If the micellar 
solution remains at high pH for a long enough time, such hydrolyzable 
surfactants undergo extensive hydrolysis and cause the formation of large 
particles, due to lack of stabilizing surfactant, prior to neutralization 
with acid. Therefore, the particle sizes will not be uniform from batch to 
batch, as they will vary depending on how long the micellar solution was 
formed prior to utilization or neutralization. It will be necessary to 
discard large quantities of coupler dispersion that will not meet 
manufacturing specifications. It has been proposed in copending 
co-assigned U.S. Ser. No. 297,005 filed Jan. 17, 1989 that uniform small 
particle size coupler dispersions may be made by the process in which the 
particles are simultaneously formed and neutralized. While the process 
allows the formation of uniform, stable particles, it has been found that 
some of the coupler materials unexpectedly form particles that are not as 
photographically active as would be desirable. It had been assumed that 
small particles would unfailingly be more active than large particles. 
Therefore, there remains a need for a process that will allow the 
formation of such continuously precipitated dispersions of coupler 
materials that have adequate photographic activity. 
In conventional photographic systems it has been the practice to mill 
polymer and/or gelatin, surfactant and couplers with a mixture of 
solvents. The solvents consist of a permanent non water soluble solvent 
normally having a high boiling temperature and sometimes a water miscible 
auxiliary solvent that is usually removed during film formation or removed 
by washing off from chilled gel noodles, or is distilled off. The coupler 
dissolved in the permanent solvent remains dispersed as a stable colloid 
in gelatin which is used in forming photographic products. Typical of such 
systems for polymeric couplers are those disclosed in U.S. Pat. No. 
3,912,517-Van Poucke et al. The dispersion of couplers and solvents is 
also discussed at pages 348-351 of The Theory of Photographic Process, 
Fourth Edition, edited by T. H. James, MacMillan, New York, Copyright 
1977. 
While the above processes for making photographic materials have been 
successful, there is a continuing need for preparing them in a continuous 
mode for efficient process control in the production of very large volume 
products, such as photographic paper and motion picture print films. 
THE INVENTION 
Generally the invention is performed by providing a first flow of water, 
water immiscible activating permanent solvent, and surfactant agitated by 
a mixer to form an unstable coarse or crude dispersion of the permanent 
solvent in water, a second flow comprising water miscible solvent, base, 
and photographic material, bringing together said first and second flows 
and then either simultaneously or immediately following mixing, 
neutralizing said streams to precipitate particles . The precipitated 
particles containing activating permanent solvent are generally more 
active than precipitated particles from systems where the particles do not 
contain the activating permanent solvent. During and probably up to some 
time after the precipitation process, the permanent solvent forms the 
coarse droplets that carried by the water miscible auxiliary solvent, 
which is also miscible with the permanent solvent, into the precipitated 
coupler particles, to produce solvent swollen particles of the size of 
about 100 nm in diameter. The formed dispersions are stable, do not 
contain gelatin, and can be washed by dialysis or by diafiltration to 
remove the water miscible auxiliary solvent to produce a photographic 
dispersion containing the particles of permanent solvent and coupler for 
further processing to produce photographic coatings at a later time. 
The invention is practiced in a semicontinuous mode by bringing a first 
flow of coupler solution in basic aqueous auxiliary solvent solution into 
a vessel containing a crude dispersion of the permanent solvent in an 
aqueous surfactant solution, and immediately neutralizing it with an acid 
solution, with vigorous agitation. The reaction vessel is fitted with a 
temperature sensor and a pH sensor which senses the pH and drives the acid 
pump such that for a constant rate of delivery of the basic coupler 
solution, the correct amount of acid is always pumped in by a processor 
controlled pump to maintain a constant pH of 6.0.+-.0.2 in the reactor. In 
a continuous mode this invention can be practiced by having a third flow 
of the surfactant containing crude dispersion of the permanent solvent 
flow into the reactor at a pre-set rate. The dispersion is then dialyzed 
to remove the auxiliary solvent and processed for photographic use when 
necessary. 
In preferred methods, for large scale preparation, the first stream of 
coupler solution in basic aqueous auxiliary solvent and the second stream 
of the crude dispersion of the permanent solvent in aqueous surfactant may 
be brought together immediately prior to a centrifugal mixer with addition 
of acid directly into the mixer. In the alternative, the first and second 
flow, as well as the acid flow, may all be added simultaneously in the 
centrifugal mixer. The streams will have a residence time of about 1 to 
about 30 seconds in the mixer. When leaving the mixer, they may be 
diafiltered on line to remove the auxiliary solvent and immediately be 
processed for utilization in photographic materials. When the process is 
stopped. the mixer may be shut off with minimum waste of material, as it 
is only necessary to discard the material in the mixer and pipelines 
immediately adjacent to it when the process is reactivated after a lengthy 
shutdown. 
In all the described procedures of practicing this invention the surfactant 
containing crude dispersion of the permanent solvent is in contact with 
the high pH environment of the coupler solution for a minimum period of 
time. Since pH neutralization is very rapid, the surfactant experiences a 
high pH environment for very short times. There are many surfactants that 
are excellent stabilizers for precipitated dispersions. However, some of 
them contain a chemical linkage such as an ester linkage that gets easily 
hydrolyzed by the base, causing the loss of the stabilizing ability of the 
surfactant. Utilization of the process of mixing with immediate 
neutralization by acid virtually eliminates the chance of hydrolysis of 
such hydrolyzable surfactants, which leads to cost savings in the need to 
use less surfactant. 
The process of the invention produces particles of coupler that ar present 
in water without gelatin. The gelatin free suspensions of the invention 
are stable in storage and may be stored at room temperature rather than 
chilled as are gelatin suspensions.

MODES OF PERFORMING THE INVENTION 
The invention provides numerous advantages over prior processes of forming 
dispersions of photographic components. The invention provides continuous 
or semicontinuous methods of forming highly photographically active 
dispersions of couplers. Even though procedures for the preparation of 
precipitated dispersions have been well known, the method of incorporating 
coupler solvents into them in a single step during their formulation was 
unknown. Many precipitated coupler dispersions such as formed by the 
above-referenced U.S. Ser. No. 297,005 - Bagchi et al filed Jan. 17, 1989. 
and hereby incorporated by reference do not have high photographic 
activity. It was discovered incorporation of permanent coupler solvents 
during precipitation in a manner of this invention produced coupler 
dispersion of desirable and high photographic activity. Methods have been 
discovered in which permanent coupler solvents can be incorporated in 
precipitated dispersion during its formation in a single step. Such 
permanent solvent containing dispersions have been found to be much more 
active than the precipitated dispersions that did not contain any 
permanent coupler solvent. The activity of such dispersions are more than 
adequate for formation of photographic products. Since these permanent 
solvent containing precipitated dispersions do not contain gelatin, they 
can be held at room temperature until photographic coatings are made. This 
is a cost saving advantage over conventional milled dispersions that 
contain gelatin, which need to be refrigerated. 
FIGS. 1 and 2 describe respectively the continuous and the semicontinuous 
equipment to prepare such dispersions as those of this invention for small 
laboratory size preparation The practice of the invention requires 
neutralization to be complete within not more than about two minutes from 
the time the basic auxiliary solvent coupler solution and the crude 
dispersion of permanent solvent and surfactant Join. For obtaining small 
particle size it is preferred that neutralization be complete within much 
less than about one minute. The device of FIG. 1 was designed for 
continuous pH-controlled precipitation of dispersions of this invention. 
Container 92 is provided with a crude dispersion of the permanent coupler 
solvent, prepared by simple agitation in aqueous surfactant solution 94. 
The agitator 93 is used to form the crude dispersion. Container 96 is 
provided with an acid solution. Container 100 contains a basic coupler 
solution in the auxiliary solvent 102. Container 104 provides a mixing and 
reacting chamber where the dispersion formation takes place. Container 106 
is a collector for the formed coupler dispersion 158. In operation the 
surfactant solution 94 is metered by pump 108 through line 110 into the 
reaction vessel 104. At the same time the basic coupler solution is 
metered by pump 112 through line 114 into the reactor 104 at a constant 
predetermined rate. The solutions are agitated by stirrer 116, and acid 98 
is metered by pump 118 through line 121 into the reactor 104 to neutralize 
the solution. The pumping by metering pump 118 is regulated by controller 
120. Controller 120 is provided with a pH sensor 122 that senses the pH of 
the dispersion 124 in reactor 104 and controls the amount and the rate of 
the addition of acid 98 added by pump 118 to neutralize the content of the 
reaction chamber. The drive for stirrer 116 is 126. The recorder 130 
constantly records the pH of the solution to provide a history of the 
dispersion 124. Metering pump 132 withdraws the dispersion solution from 
reactor 104 and delivers it to the container 106 using pump 132 and line 
150 where it may exit from the outlet 134. In a typical precipitation 
there is a basic coupler solution 102 of solvent, sodium hydroxide 
solution, and the coupler. The surfactant is in water, and the 
neutralizing acid is an aqueous solution of acetic or propionic acid. The 
reaction chamber has a capacity of about 800 ml. The coupler solution tank 
100, has a capacity of about 2500 ml. The surfactant solution tank 92, has 
a capacity of about 5000 ml. The acid solution tank has a capacity of 
about 2500 ml and the dispersion collection tank has a capacity of about 
10,000 ml. The temperature is controlled by placing the four containers 
92, 96, 104, and 100 in a bath 136 of water 138 whose temperature can be 
regulated to its temperature up to 100.degree. C. Usually precipitation is 
carried out at 25.degree. C. The temperature of the bath 138 is controlled 
by a steam and cold water mixer (not shown). The temperature probe 140 is 
to sense the temperature of the reactor. This is necessary for correct pH 
reading. The neutralization of the basic coupler solution in the reaction 
chamber 104 by the proportionally controlled pump 118 which pumps in acid 
solution 98 results in control of pH throughout the run to .+-.0.2 of the 
set pH value which is usually about 6.0. In the continuous mode similar 
volumes as pilot scale equipment (to be described next) have been made, 
except that the flow rates being about 20-30 times smaller than the pilot 
scale equipment of FIGS. 3 and 4, the preparation takes about 20-30 times 
longer. 
FIG. 2 schematically illustrates a semicontinuous system for forming 
dispersions of coupler materials. Identical items are labeled the same as 
in FIG. 1. Because of reduced scale, the sizes of acid kettle 96 and the 
coupler settle 100 are smaller (about 800 ml each). In the system of FIG. 
2, the reactor 104 is initially provided with a crude aqueous surfactant 
dispersion of a permanent coupler solvent. Into this is pumped a basic 
solution of coupler and solvent 102 through pipe 114. pH sensor 122 that 
works through controller 120 to activate pump 118 and neutralize the 
dispersion to a pH of about 6 by pumping acetic acid 98 through metering 
pump 118 and line 121 to the reactor 104. Reactor 104 must be removed, 
dumped, and refilled with the aqueous surfactant solution in order to 
start a subsequent run. However, the systems of FIGS. 1 and 2 do provide 
fast control of pH in order to produce photographically useful 
dispersions. Dispersions may be formulated and optimized using the 
semicontinuous process using this equipment before scale up for continuous 
running in continuous pilot scale equipment such as that of FIGS. 3 and 4. 
The schematic of FIG. 3 illustrates apparatus 10 for performing the process 
of the invention in a pilot scale continuously. The apparatus is provided 
with high purity water delivery line 12. Tank 14 contains a crude emulsion 
of the permanent solvent in aqueous surfactant. Jacket 15 on tank 14 
regulates the temperature of the tank. Surfactant enters the tank through 
line 16. Line 9 provides the permanent solvent and agitator 13 produces a 
crude dispersion of the permanent solvent in water in tank 14. Line 16 is 
also used to feed the surfactant. Tank 18 contains the basic coupler 
solution 19. Jacket 17 controls the temperature of materials in tank 18. 
In tank 18 the coupler enters through manhole 20, a base material such as 
aqueous sodium hydroxide solution entering through line 22, and solvent 
such as n-propanol entering through line 24. The solution is maintained 
under agitation by the mixer 26. Tank 81 contains acid solution 25 such as 
propionic acid entering through line 30. The tank 81 is provided with a 
heat jacket 28 to control the temperature, although with the acids 
normally used, it is not necessary. In operation, the acid is fed from 
tank 81 through line 32 to mixer 34 via the metering pump 86 and flow 
meter 88. A pH sensor 40 senses the acidity of the dispersion as it leaves 
mixer 34 and allows the operator to adJust the acid pump 86 to maintain 
the proper pH in the dispersion exiting the mixer 34. The photographic 
component 19 passes through line 42, metering pump 36, flow meter 38, and 
Joins the surfactant solution in line 44 at the T fitting 46. The 
particles are formed in mixer 34 and exit through pipe 48 into the 
ultrafiltration tank 82. In tank 82 the dispersion 51 is held while it is 
washed by ultrafiltration membrane 54 to remove the solvent and salt from 
solution and adjust the material to the proper water content for makeup as 
a photographic component. The source of high purity water is purifier 56. 
Agitator 13 agitates the surfactant solution in tank 14. Agitator 27 
agitates the acid solution in tank 81. The impurities are removed during 
the ultrafiltration process through permeate (filtrate) stream 58. 
The apparatus 80 schematically illustrated in FIG. 4 is similar to that 
illustrated in FIG. 3 except that the acid solution in pipe 32, the crude 
emulsion of a permanent solvent in aqueous surfactant solution in pipe 44, 
and the basic coupler solution in an auxiliary in pipe 42 are directly led 
to mixing device 34. Corresponding items in FIG. 3 and FIG. 4 have the 
same numbers. In this system all mixing takes place in the mixer 34 rather 
than Joining of the surfactant solution and the photographic component in 
the T connection immediately prior to the mixer as in the FIG. 3 process. 
The surfactants of the invention may be any surfactant that will aid in 
formation of stable dispersions of particles. Typical of such surfactants 
are those that have a hydrophobic portion to anchor the surfactant to the 
particle and a hydrophilic part that acts to keep the particles separated 
either by steric repulsion (see, for example, P. Bagchi. J. Colloid and 
Interface Science. Vol. 47, page 86, and 110, 1974, Vol. 41, page 380, 
1972, and Vol. 50, page 115, 1975) or by charge repulsion. Many classes of 
surfactants can be utilized to perform this invention. There can, in 
general, be clarified in the following classes: 
Class I: Surfactants with single, double, or triple C.sub.5 to C.sub.25 
hydrocarbon chain terminated with one or more charged head groups. 
Additional polymeric or oligomeric steric stabilizers could be used with 
such surfactants. 
Examples of this class of surfactants are as follows: 
__________________________________________________________________________ 
I-1 CH.sub.3(CH.sub.2).sub.11SO.sub.4.sup.- Na.sup.+ 
(Sodium Dodecyl Sulfate) 
I-2 
##STR1## (Sodium Dodecyl Benzene Sulfonate) 
I-3 
##STR2## (Aerosol OT Cyanamid) 
I-4 
##STR3## (Aerosol 22 Cyanamid) 
I-5 
##STR4## where R = CH(CH.sub.3)C.sub.4 H.sub.9 
(Aerosol MA Cyanamid) 
I-6 " 
##STR5## 
I-7 " 
##STR6## 
I-8 " R = CH.sub.2CH(CH.sub.2 CH.sub.3)C.sub 
.3 H.sub.7 
I-9 
##STR7## R = (CH.sub.2).sub.n CH.sub.3 (n = 2, 
3 & 5) 
I-10 
" 
##STR8## 
I-11 
##STR9## (Alkanol-XC Dupont) 
__________________________________________________________________________ 
Use of additional polymeric or oligomeric steric stabilizers with in 
addition to such surfactants can provide additional colloidal stability of 
such dispersions and can be added if necessary. Polymeric materials for 
such use are water soluble, homo- , or co-polymers such as polyvinyl 
pyrrolidone, dextran, and derivatized dextrans polyvinyl alcohol and 
poly(vinyl pyrrolidone-co-vinyl alcohol) of various ratios. Other types of 
oligomeric co-stabilizers that can be used are block oligomeric compounds 
comprising hydrophobic polyoxypropylene blocks A and hydrophilic 
polyoxyethylene blocks B joined in the manner of A-B-A, B-A-B, A-B, 
(A-B).sub.n .tbd.G.tbd.(B-A), or (B-A).sub.n .tbd.G.tbd.(A-B), where G is 
a connective organic moiety and n is between 1 and 3. Examples of such 
surfactants are shown in Table A. 
TABLE A 
__________________________________________________________________________ 
Examples of Block Oligomeric Costabilizers For Use Along With Surfactants 
of Class I 
Name Molecular 
ID (Manufacturer) 
Best Known Structure Weight Range 
__________________________________________________________________________ 
P-1 
Pluronic .TM. Polyols (BASF) 
##STR10## 1,100 to 14,000 
P-2 
R Polyols (BASF) 
##STR11## 
1,900 to 9,000 
P-3 
Plurodot .TM. 
Liquid Polyethers Based on 3,200 to 7,500 
Polyols (BASF) 
Alkoxylated Triols 
P-4 
Tetronic .TM. Polyols (BASF) 
##STR12## 3,200 to 27,000 
__________________________________________________________________________ 
Class II - Surfactants comprising between 6 to 22 carbon atom hydrophobic 
tail with one or more attached hydrophilic chains comprising at least 4 
oxyethylene and/or glycidyl ether groups that may or may not be terminated 
with a negative charge such as a sulfate group. 
Examples of such surfactants are as follows: 
__________________________________________________________________________ 
II-1 
##STR13## Olin 10G (Dixie) 
II-2 
n-C.sub.12H.sub.25O(CH.sub.2CH.sub.2O).sub.12SO.sub.3.sup.- Na.sup.+ 
Polystep B-23 
(Stepan) 
II-3 
##STR14## Triton TX-102 (Rohm & Haas) 
II-4 
n-C.sub.12 H.sub.25O(CH.sub.2CH.sub.2O).sub.23OH 
Tricol LAL-23 
(Emery) 
II-5 
##STR15## Avanel S-150 (PPG) 
II-6 
##STR16## Aerosol A102 (Cyanamid) 
II-7 
##STR17## (Aerosol A103 (Cyanamid) 
__________________________________________________________________________ 
Class III - Sugar surfactants, comprising between one and three 6 to 22 
carbon atom hydrophobic tails with one or more attached hydrophilic mono, 
di, tri or oligosaccharidic chains that may or may not be terminated by a 
negatively charged group such as a sulfate group. 
Examples of such surfactants are as follows: 
##STR18## 
The invention may be practiced with any hydrophobic photographic component 
that can be solubilized by base and solvent. Typical of such materials are 
colored dye-forming couplers, development inhibitor release couplers, 
development inhibitors, filter dyes, UV-absorbing dyes, development 
boosters, development moderators, and dyes. Suitable for the process of 
the invention are the following compounds which have been utilized to form 
precipitated dispersions: 
##STR19## 
All of the above compounds are amenable to the described process of the 
invention. Many of the precipitated dispersions of the above list are 
photographically very active and some are substantially more active 
compared to their conventional milled dispersions. However, some of the 
examples of the above list such as, for example, compounds C-3 and C-4, 
are extremely inactive as precipitated dispersions. These are the 
compounds that need to have permanent solvent incorporated in them to 
produce photographically active dispersions that can be used in viable 
photographic systems. The couplers that are typically suitable for the 
process are those that are without many polar or ionizable groups, as such 
couplers are less reactive unless in the presence of an activating 
solvent. 
The mixing chamber, where neutralization takes place, may be of suitable 
size that has a short residence time and provides high fluid shear without 
excessive mechanical shear that would cause excessive heating of the 
particles. In a high fluid shear mixer, the mixing takes place in the 
turbulence created by the velocity of fluid streams impinging on each 
other. Typical of mixers suitable for the invention are centrifugal 
mixers, such as the "Turbon" centrifugal mixer available from Scott 
Turbon, Inc. of Van Nuys, Calif. It is preferred that the centrifugal 
mixer be such that in the flow rate for a given process the residence time 
in the mixer will be of the order of 1-30 seconds. Preferred residence 
time is 10 seconds to prevent particle growth and size variation. Mixing 
residence time should be greater than 1 second for adequate mixing. 
The volatile water miscible solvents suitable for dissolving the 
photographic component may be any suitable solvent that may be utilized in 
the system in which precipitation takes place by solvent shift and/or pH 
shift. Typical of such materials are the solvents acetone, methyl alcohol, 
ethyl alcohol, isopropyl alcohol, tetrahydrofuran, dimethylformamide, 
dioxane, N-methyl-2-pyrrolidone, acetonitrile, ethylene glycol, ethylene 
glycol monobutyl ether, diacetone alcohol, ethyl acetate and 
cyclohexanone. A preferred solvent is n-propanol because n-propanol 
provides a very stable supersaturated basic coupler solution that is used 
for this precipitation process. 
The activating permanent water immiscible high boiling coupler solvents are 
compounds as shown below. These are chosen for their compatibility and 
activity in general with large number of couplers and for their 
competitive price advantages. 
__________________________________________________________________________ 
S-1 
##STR20## 
S-2 
##STR21## 
S-3 
##STR22## Mixture of tricresyl phosphates 
S-4 
##STR23## Di-n-Butyl phthalate 
S-5 
##STR24## N-n-amylphthalimide 
S-6 
##STR25## Bis(2-Methoxyethyl)phthalate 
S-7 
##STR26## Ethyl N,N-di-n-butyl-carbamate 
S-8 
##STR27## Diethyl phthalate 
S-9 
##STR28## n-Butyl 2-methoxybenzoate 
S-10 
##STR29## Bis(2-n-Butoxyethyl)phthalate 
S-11 
##STR30## Diethyl benzylmalonate 
S-12 
##STR31## Guaiacol acetate 
S-13 
##STR32## Tri-m-cresyl phosphate 
S-14 
##STR33## Ethyl phenylacetate 
S-15 
##STR34## Phorone 
S-16 
BuO CO(CH.sub.2) .sub.8COOBu 
Di-n-butyl sebacate 
S-17 
##STR35## N,N-Diethyl lauramide 
S-18 
##STR36## Dioctyl phthalate (Octoil) 
S-19 
##STR37## Cresyl diphenyl phosphate 
S-20 
##STR38## Butyl cyclohexyl phthalate 
S-21 
##STR39## Tetrahydrofurfuryl adipate 
S-22 
##STR40## Guaiacol n-caproate 
S-23 
##STR41## Bis(tetrahydrofurfuryl)phthalate 
S-24 
##STR42## N,N,N',N'-tetraethyl phthalamide 
S-25 
##STR43## N-n-Amylsuccinimide 
S-26 
##STR44## Triethyl citrate 
S-27 
##STR45## 2,4-Di-n-amylphenol 
S-28 
##STR46## 1,4-Cyclohexylenedimethylene 
bis(2-ethylhexanoate) 
__________________________________________________________________________ 
The acid and base may be any materials that will cause a pH shift and not 
significantly decompose the photographic components. The acid and base 
utilized in the invention are typically sodium hydroxide as the base and 
propionic acid or acetic acid as the acid, as these materials do not 
significantly degrade the photographic components and are low in cost. 
The process of this invention leads to gelatin free, fine particle 
colloidal dispersions of photographic materials that are stable from 
precipitation at least for six weeks at room temperature. This is a cost 
saving feature as conventional milled dispersions need to be stored under 
refrigerated conditions. Under refrigerated conditions dispersions 
prepared by the method of this invention photographically useful lives 
anywhere up to two months. 
DESCRIPTION OF MEASUREMENTS 
All particle sizes of the precipitated dispersions were made by photon 
correlation spectroscopy (PCS) as described by B. Chu, Laser Light 
Scattering, Academic Press, 1974, New York. Unless otherwise mentioned, 
all photographic development we carried out by the standard C-41 color 
development process as described in the British Journal of Photography 
Annual of 1988, pages 196-198. Solution reactivity rates of the 
dispersions were determined using an automated dispersion reactivity 
analysis (ADRA) method. A sample of the dispersion is mixed with a 
carbonate buffer and a solution containing CD-4 developer. 
##STR47## 
Potassium sulfite is added as a competitor. The carbonate buffer raises the 
pH of this reaction mixture to a value close to the normal processing pH 
(10.0). An activator solution containing the oxidant potassium 
ferricyanide is then added. The oxidant generates oxidized developer which 
reacts with the dispersed coupler to form image dye and with sulfite to 
form side products. After the addition of a clarifier (solution of Triton 
X-100), the dye density is read using a flow spectrometer system. The 
concentration of dye is derived from the optical density and a known 
extinction coefficient. 
A kinetic analysis is carried out by treating the coupling reaction as a 
homogeneous single phase reaction. It is also assumed that the coupling 
reaction and the sulfonation reaction (sulfite with oxidized developer) 
may be represented as second order reactions. Furthermore, the 
concentrations of reagents are such that the oxidant and coupler are in 
excess of the developer. Under these conditions, the following expression 
is obtained for the rate constant of the coupling reaction: 
k=k'1n[a/(a-x)]1n[b/(b-c+x)] 
where k' is the sulfonation rate constant, a is the concentration of 
coupler, b is the concentration of sulfite, c is the concentration of 
developer, and x is the concentration of the dye. The rate constant k is 
taken as a measure of dispersion reactivity. From an independently 
determined or known value of k' and with this knowledge of all of the 
other parameters, the rate constant k (called the automated dispersion 
reactivity analysis, ADRA, rate) is computed. 
MONOCHROME COATING FORMAT FOR PHOTOGRAPHIC EVALUATIONS 
The monochrome bilayer coating format used for the photographic evaluations 
of the coupler dispersions was as follows: 
Layer 1 (TOP): 2.691 g/m.sup.2 of gelatin overcoat. 0.113 g/m.sup.2 of 
bis(vinylsulfonyl)methane hardener. 
Layer 2 (BOTTOM): Indicated amounts of image, development inhibitor 
releasing (DIR) or colored couplers, with or without indicated amounts of 
permanent coupler solvent. 1.614 g/m.sup.2 of silver in a 
green-sensitized, medium speed, three-dimensional, 320 nm diameter AgBr(I) 
12 mole percent Iodine crystal. 3.767 g/m.sup.2 of gelatin. 
Support: Clear ester subbed with a thin polymer layer for the adhesion of 
the gelatin coatings. 
Coatings were made in slide hopper coating and drying machine in two 
passes. 
EXAMPLES 
The following examples are intended to be illustrative and not exhaustive 
of the invention. Parts and percentages are by weight unless otherwise 
specified. 
EXAMPLE 1 
(Control) Preparation of Precipitated Magenta Image Coupler Dispersion of 
Compound C-7 
This example utilizes a process and apparatus generally as schematically 
illustrated in FIG. 3. The coupler solution, surfactant solution, and acid 
solution are prepared as follows: 
______________________________________ 
Coupler solution: 
Coupler C-7 1550 g 
4% NaOH 2475 g 
n-propanol 2880 g 
6905 g 
Flow rate: 342 g/min 
______________________________________ 
Above ingredients were mixed together and heated to 50.degree. C. to 
dissolve the coupler and then cooled to 30.degree. C. before use. 
______________________________________ 
Surfactant 
High purity water 
51600 g 
solution: Alkanol-XC (10%) 
1930 g 
Polyvinyl Pyrrolidone 
780 g 
(molecular weight 
about 40,000) 
54310 g 
Flow rate: 2686 g/min 
Acid solution: 
Acetic acid 214 g 
High purity water 
1214 g 
1428 g 
Flow rate: Approximately 53 g/min 
(adjusted to control the 
pH of the dispersion 
between 5.4 to 5.6). 
______________________________________ 
The description of the apparatus setup for this example is as follows: 
Temperature controlled, open top vessels 
Gear pumps with variable speed drives 
A high fluid shear centrifugal mixer operated with a typical residence time 
of about 2 sec. 
A SWAGE-LOC "T" fitting where surfactant and coupler streams join 
Residence time in pipe between T fitting and mixer &lt;1 sec. 
In line pH probe used to monitor pH in the pipe exiting the mixer 
Positive displacement pump for recirculation in batch ultrafiltration 
Ultrafiltration membrane OSMONICS 20K PS 3' by 4" spiral wound permeator 
PROCESS DESCRIPTION 
The three solutions are continuously mixed in the high speed mixing device 
in which the ionized and dissolved coupler is reprotonated causing 
precipitation. The presence of the surfactant stabilizes the small 
particle size dispersion. The salt byproduct of the acid/base reaction is 
sodium propionate. Ultrafiltration is used for constant-volume washing 
with distilled water to remove the salt and the solvent (n-propanol) from 
the crude dispersion. The recirculation rate is approximately 20 gal/min. 
with 50 psi back pressure which gives a permeate rate of about 1 gal/min. 
The washed dispersion is also concentrated by ultrafiltration to the 
desired final coupler concentration of about 10-15 weight percent. The 
time to perform the ultrafiltration and produce the final coupler 
concentration is about 1 hour. Average particle size is about 66 
nanometers as measured by Photon Correlation Spectroscopy. 
EXAMPLE 2 
(Control) Preparation of Precipitated Magenta DIR Coupler Dispersion of 
Compound C-3 (COMISON) 
This example utilizes a process and apparatus generally as schematically 
illustrated in FIG. 3. The coupler solution, surfactant solution, and acid 
solution are prepared as follows: 
______________________________________ 
Coupler solution: 
Coupler C-3 1000 g 
20% NaOH solution 
250 g 
n-propanol 2000 g 
3250 g 
Flow rate: 275 g/min 
______________________________________ 
Above ingredients were mixed together and heated to 50.degree. C. to 
dissolve the coupler and then cooled to 30.degree. C. before use. 
______________________________________ 
Surfactant 
High purity water 
35000 g 
solution: Aerosol A103 (33%) 
750 g 
solution 
(American Cyanamid) 
35750 g 
Flow rate: 3028 g/min 
Acid solution: 
Propionic acid 150 g 
High purity water 
850 g 
1000 g 
Flow rate: Approximately 55 g/min 
(adjusted to control the 
pH of the dispersion 
between 5.9 to 6.1). 
______________________________________ 
The description of the apparatus setup and the process for this example is 
similar to that in Example 1. Average particle size of the dispersion as 
measured by Photon Correlation Spectroscopy was 39 nm. The solution ADRA 
rectivity rate of the dispersion was 1390 l/(mole sec). 
EXAMPLE 3 
(Control) Preparation of Precipitated Yellow Colored Magenta Coupler 
Dispersion of Compound C-4(Comparison) 
This example utilizes a process and apparatus generally as schematically 
illustrated in FIG. 3. The coupler solution, surfactant solution, and acid 
solution was prepared as follows: 
______________________________________ 
Coupler solution: 
Coupler C-4 2000 g 
20% NaOH 500 g 
n-propanol 4000 g 
6500 g 
Flow rate: 474 g/min 
______________________________________ 
Above ingredients were mixed together and heated to 60.degree. C. to 
dissolve the coupler and then cooled to 30.degree. C. before use. 
______________________________________ 
Surfactant 
High purity water 
40000 g 
solution: Aerosol A102 (33%) 
1500 g 
(American Cyanamid) 
41500 g 
Flow rate: 3028 g/min 
Acid solution: 
Acetic acid 300 g 
High purity water 
1700 g 
2000 g 
Flow rate: Approximately 75 g/min 
(adjusted to control the 
pH of the dispersion 
between 5.9 to 6.1). 
______________________________________ 
The description of the apparatus setup and the process for this example is 
similar to that in Example 1. Average particle size of the dispersion as 
measured by Photon Correlation Spectroscopy was 13 nm. The solution ADRA 
reactivity rate of the dispersion was 18500 l/(mole sec). 
EXAMPLE 4 
Single Step Preparation of Precipitated Magenta DIR Coupler Dispersion of 
Compound C-3 with Incorporated Coupler Solvent (Invention) 
This example utilizes the process of this invention and the apparatus 
schematically illustrated in FIG. 2. The coupler solution, the crude 
coupler solvent/aqueous surfactant emulsion, and the acid solution are 
prepared as follows: 
______________________________________ 
Coupler solution: 
Coupler C-3 20 g 
20% NaOH 5 g 
n-propanol 50 g 
75 g 
Flow rate: 17.5 g/min 
______________________________________ 
Above ingredients were mixed together and heated to 60.degree. C. to 
dissolve the coupler and then cooled to 30.degree. C. before use. 
______________________________________ 
Crude Coupler Solvent/Aqueous Surfactant Emulsion 
______________________________________ 
Distilled water 500 g 
Coupler Solvent S-13 
40 g (2X compared to coupler) 
Aerosol A103 (33%) 
15 g 
555 g 
______________________________________ 
A crude emulsion of the above ingredients was prepared by placing the 
mixture in vessel 104 of FIG. 2 and agitating it with mixer 116. 
Acid solution: 15% propionic acid, placed in vessel 96 of FIG. 2 
The precipitation was started by setting the pH controller at pH 6.0 and 
starting the coupler solution pump 112. As the basic coupler solution 
entered the reaction vessel 104, the pH of the mixture increased. This was 
sensed by the pH probe which then caused the activation of the acid pump 
118 to pump in acid into the stirred reaction chamber 104 to lower the pH 
and cause precipitation of the coupler in the form of a fine particle 
stable dispersion. In the presence of the water miscible auxiliary solvent 
n-propanol the water immiscible high boiling permanent solvent, tricresyl 
phosphate, was solubilized and transported into the formed coupler 
dispersion particles to produce a permanent solvent loaded coupler 
dispersion. The dispersion was dialyzed against distilled water for 24 
hours to remove the formed salts and the auxiliary solvents. The average 
particle diameter of the dispersion particle as measured by Photon 
Correlation Spectroscopy was 114 nm, and the ADRA reactivity rate was 
determined to be 3760 l/(mole sec.). It is to be noted that compared to 
the comparison in Example 2, the particle size of this solvent loaded 
coupler dispersion of the invention has about three times the particle 
size, but its reaction rate with color developer to form image dye is 
about three times larger. In other words, this single step incorporation 
of the coupler solvent during precipitation increased its coupling 
propensity drastically. The coupler content of this dispersion was 
analyzed by high pressure liquid chromotography and was found to be around 
2%. Such dilute dispersion could be diafiltered and concentrated, but was 
held as such for further processing to form a photographic coating. 
EXAMPLE 5 
Single Step Preparation of Yellow Coated Magenta Coupler Dispersion of 
Compound C-4 With Incorporated Coupler Solvent (Invention) 
This example utilizes the process of this invention and the apparatus 
schematically illustrated in FIG. 2. The coupler solution, the crude 
coupler solvent/aqueous surfactant emulsion, and the acid solutions were 
prepared as follows: 
______________________________________ 
Coupler solution: 
Coupler C-4 20 g 
20% NaOH 5 g 
n-propanol 50 g 
75 g 
Flow rate: 17.5 g/min 
______________________________________ 
Above ingredients were mixed together and heated to 50.degree. C. to 
dissolve the coupler and then cooled to 30.degree. C. before use. 
______________________________________ 
Crude Coupler Solvent/Aqueous Surfactant Emulsion 
______________________________________ 
Distilled water 500 g 
Coupler Solvent S-13 
40 g (2X compared to coupler) 
Aerosol A102 (33%) 
15 g 
555 g 
______________________________________ 
A crude emulsion of the above ingredients was prepared by placing the 
mixture in vessel 104 of FIG. 2 and agitating it with mixer 116. 
Acid solution: 15% propionic acid, placed in vessel 96 of FIG. 2. 
The precipitation was started by setting the pH controller at pH 6.0 and 
starting the coupler solution pump 112. As the basic coupler solution 
entered the reaction vessel 104, the pH of the mixture increased. This was 
sensed by the pH probe which then caused the activation of the acid pump 
118 to pump in acid into the stirred reaction chamber 104 to lower the pH 
to cause precipitation of the coupler into a fine particle stable 
dispersion. In the presence of the water miscible auxiliary solvent 
n-propanol the water immiscible high boiling permanent solvent, tricresyl 
phosphate, was solubilized and transported into the formed coupler 
dispersion particles to produce a permanent solvent loaded coupler 
dispersion. The dispersion was dialyzed against distilled water for 24 
hours to remove the formed salts and the auxiliary solvents. The average 
particle diameter of the dispersion particle as measured by Photon 
Correlation Spectroscopy was 109 nm, and the ADRA reactivity rate was 
determined to be 52200 l/(mole sec). It is to be noted that compared to 
the comparison in Example 3, the particle size of this solvent loaded 
coupler dispersion of the invention has about eight times the particle 
size, but its reaction rate with color developer to form image dye is 
about three times larger. In other words, this single step incorporation 
of the coupler solvent during precipitation increased its coupling 
propensity drastically. The coupler content of this dispersion was 
analyzed by high pressure liquid chromotography and was found to be around 
2%. Such dilute dispersion could be diafiltered and concentrated, but was 
held as such for further processing to form a photographic coating. 
EXAMPLE 6 
Photographic Evaluation of the Single Step permanent Coupler Solvent 
Incorporated Precipitated Dispersion of the DIR Coupler C-3 of This 
Invention (Example 4) Against Its Comparison (Example 2) 
The comparison dispersion of Example 2 and the dispersion of the invention 
Example 4 were evaluated in a coating format as described earlier with the 
precipitated image coupler dispersion of coupler C-7 of Example 1. The 
description of the various coatings are indicated in Table B. The coating 
melts were prepared just prior to coating in order to minimize coupler 
solvent transport to the image coupler dispersion. The coatings were given 
a stepwise exposure with green light and then processed by the C41 
processing as described in British Journal of Photography Annual of 1988, 
page 196 to 198. The formed magenta images were then read in green light 
which gave the sensitometric curves shown in FIGS. 5A and 5B. The 
sensitometric results of coatings 1 through 5 are also listed in Table B. 
TABLE B 
__________________________________________________________________________ 
Summary of Results of Coatings 1 Through 5 of Example 6 
Average 
Solution 
Particle 
ADRA 
Diameter 
Reactivity 
of DIR 
Rate of DIR 
D.sub.max of 
Contrast 
Image Coupler 
DIR Coupler 
Coupler 
Dispersion 
Green 
of Green 
Ctg. # 
Laydown (g/m.sup.2) 
Laydown (g/m.sup.2) 
Dispersion 
l/(mole sec) 
Image 
Image 
Comments 
__________________________________________________________________________ 
#1 Precipitated 
None -- -- 2.52 1.57 Precipitated 
Control 
no permanent control cou- 
solvent dis- pler disper- 
persion of sion of Cplr. 
Example 2 C-7 is very 
active by 
Coverage itself w/o 
0.646 g/m.sup.2 any incorp. 
cplr. solvent. 
#2 Same as in 
Precipitated 
39 nm 
1390 2.49 1.57 DIR coupler 
Control 
Coating #1 
no permanent is precipi- 
solvent dis- tated no 
persion of solvent 
Coupler 3 of dispersion. 
Example 1 DIR coupler 
had no effect 
Coverage on D.sub.max and 
0.0323 g/m.sup.2 contrast of 
negative 
image indi- 
cating very 
poor reactiv- 
ity of DIR 
coupler 
dispersion. 
#3 Same as in 
Precipitated 
39 nm 
1390 2.44 1.57 DIR coupler 
Control 
Coating #1 
no permanent is precipi- 
solvent dis- tated no 
persion of solvent 
Coupler 3 of dispersion. 
Example 2 DIR coupler 
at 2X level 
Coverage compared to 
0.646 g/m.sup.2 Coating #2 
had no effect 
on D.sub.max and 
contrast of 
negative 
image indi- 
cating very 
poor reactiv- 
ity of DIR 
coupler 
dispersion. 
#4 Same as in 
Precipitated 
114 nm 
3760 1.99 1.00 DIR coupler 
Inven- 
Coating #1 
2X permanent is precipi- 
tion solvent S-13 tated 2X 
dispersion of solvent S-13 
Coupler C-3 containing 
of Example 4 dispersion. 
Coupler in 
Coverage dispersion 
0.0323 g/m.sup.2 of invention 
is active 
indicated by 
increased 
ADRA rate and 
decrease of 
D.sub.max and 
contrast of 
magenta image. 
#5 Same as in 
Precipitated 
114 nm 
3760 1.57 0.65 DIR coupler 
Inven- 
Coating #1 
2X permanent is precipi- 
tion solvent S-13 tated 2X 
dispersion of solvent S-13 
Coupler C-3 containing 
of Example 4 dispersion. 
Coupler in 
Coverage dispersion 
0.0646 g/m.sup.2 of invention 
is active 
indicated by 
increased 
ADRA rate and 
decrease of 
D.sub.max and 
contrast of 
magenta image. 
__________________________________________________________________________ 
FIG. 5A is a sensitometric curve for control coatings 1, 2, and 3. 
______________________________________ 
Coating 1 Ag .fwdarw. 1.614 g/m.sup.2 
of Example 6 
No solvent precipitated image coupler 
C-7 (Dispersion of Example 1) 
C-7 .fwdarw. 0.646 g/m.sup.2 
Coating 2 Ag .fwdarw. 1.614 g/m.sup.2 
of Example 6 
No solvent precipitated image coupler 
C-7 (Dispersion of Example 1) 
C-7 .fwdarw. 0.646 g/m.sup.2 
No solvent precipitated DIR coupler 
C-3 (Dispersion of Example 2) 
C-3 .fwdarw. 0.0323 g/m.sup.2 
Coating 3 Ag .fwdarw. 1.614 g/m.sup.2 
of Example 6 
No solvent precipitated image coupler 
C-7 (Dispersion of Example 1) 
C-7 .fwdarw. 0.646 g/m.sup.2 
No solvent precipitated DIR coupler 
C-3 (Dispersion of Example 2) 
C-3 .fwdarw. 0.0646 g/m.sup.2 
______________________________________ 
FIG. 5B is a sensitometric curve for control coatings 1 and 2, and coating 
3 (invention). 
______________________________________ 
Coating 1 Ag .fwdarw. 1.614 g/m.sup.2 
of Example 6 
No solvent precipitated image coupler 
C-7 (Dispersion of Examp1e 1) 
C-7 .fwdarw. 0.646 g/m.sup.2 
Coating 4 Ag .fwdarw. 1.614 g/m.sup.2 
of Example 6 
No solvent precipitated image coupler 
C-7 (Dispersion of Example 1) 
C-7 .fwdarw. 0.646 g/m.sup.2 
2 .times. S-13 solvent incorporated 
precipitated DIR coupler C-3 
(Dispersion of Example 4) 
C-3 .fwdarw. 0.0323 g/m.sup.2 
Coating 5 Ag .fwdarw. 1.614 g/m.sup.2 
of Example 6 
No solvent precipitated image coupler 
C-7 (Dispersion of Example 1) 
C-7 .fwdarw. 0.646 g/m.sup.2 
2 .times. S-13 solvent incorporated 
precipitated DIR coupler C-3 
(Dispersion of Example 4) 
C-3 .fwdarw. 0.0646 g/m.sup.2 
______________________________________ 
FIG. 5A shows that when a precipitated dispersion of coupler C-7 containing 
no permanent coupler solvent, is coated with a similar precipitated no 
permanent solvent dispersion of DIR coupler C-3 at levels 0 (coating #1), 
0.0323 g/m.sup.2 (coating #2) and 0.0646 g/m.sup.2 the sensitometric 
curves are virtually identical with no change in the contrast of this 
image. This indicates that even though the no solvent precipitated 
dispersion of the image coupler of C-7 was very active, the similar no 
solvent precipitated dispersion of the DIR coupler of C-3 was extremely 
inactive compared to the similar experiment performed with the 
precipitated DIR coupler dispersion containing a permanent solvent. 
According to the method of this invention, the results in FIG. 5B and 
Table B show that with increased laydown of the DIR coupler, the contrast 
and the D.sub.max of the recorded image decreased progressively. This 
clearly demonstrates that the permanent solvent containing precipitated 
dispersion of the invention is definitely much more active than that of 
the comparison where no permanent solvent was incorporated into the 
precipitated dispersion of C-3. It is also to be noted in Table B that in 
spite of the larger particle size of the permanent solvent containing DIR 
dispersion of C-3, it has about three times larger ADRA reactivity rate 
compared to that of the no solvent containing precipitated dispersion, 
indicating again that the incorporation of the permanent solvent into the 
dispersion particles of C-3 in the manner of this invention caused them to 
be highly reactive. 
EXAMPLE 7 
Photographic Evaluation of the Single Step Permanent Coupler Solvent 
Incorporated Precipitated Dispersion of the Yellow Colored Magenta Coupler 
C-4 (Example 5) Against its Comparison Where No Coupler Solvent was 
Incorporated (Example 3) 
Yellow colored magenta coupler C-4 is a color correction coupler that is 
usually incorporated in the magenta layer of color negative products along 
with the image coupler and a DIR coupler. 
The comparison dispersion of coupler C-4 of Example 3 and the permanent 
solvent incorporated precipitated dispersion of Example 5 were evaluated 
in a coating format described earlier. The description of the two coatings 
are shown in Table C. The yellow colored magenta coupler dispersion of C-4 
was coated at 0.646 g/m.sup.2 with the indicated green sensitized emulsion 
to evaluate their comparative reactivities. The coatings were given a 
stepwise exposure with green light and then processed by the C-41 
processing as described in British Journal of Photography Annual of 1988, 
pages 196 to 198 for two minutes. The formed magenta images were then read 
using green and blue lights which gave the sensitometric results of 
coatings 1 and 2 as listed in Table C and shown in FIGS. 6A and 6B 
respectively. 
FIG. 6A is a sensitometric curve for coating 1 (control) of Example 7. 
EQU Ag.fwdarw.1.614 g/m.sup.2 
EQU No solvent precipitated yellow colored magenta coupler (Dispersion of 
Example 3) 
EQU C-4.fwdarw.0.646 g/m.sup.2 
FIG. 6B is a sensitometric curve for coating 2 (invention) of Example 7. 
EQU Ag.fwdarw.1.614 g/m.sup.2 
EQU 2.times.S-13 permanent solvent containing precipitated yellow colored 
magenta coupler (Dispersion of Example 5) 
EQU C-7.fwdarw.0.646 g/m.sup.2 
In the images of FIGS. 6A and 6B, it is seen with the yellow colored 
magenta coupler that as exposure is increased magenta dye is formed 
imagewise and yellow dye is at the same time consumed imagewise. It is 
also seen that the coupler solvent incorporated precipitated dispersion of 
this invention (FIG. 6B) showed greater D.sub.max, higher contrast, and 
larger ADRA reactivity (Table C) compared to the no solvent precipitated 
control of FIG. 6A, indicating the usefulness and efficacy of this 
invention. 
TABLE C 
__________________________________________________________________________ 
Summary of Results of Coatings 1 and 2 of Example 7 
Solution ADRA 
Average Particle 
Reactivity of 
Diameter of 
the Precip- 
Dmax 
Contrast 
Laydown of 
the Precipitated 
itated Disper- 
of of 
Coating 
Coupler Dispersion of 
sion of C-4 
Green 
Green 
No. C-4 g/m.sup.2 
C-4 (nm) l/(mole sec) 
Image 
Image 
Comments 
__________________________________________________________________________ 
1 Precipitated no 
13 nm 18500 0.90 
0.28 Precipitated 
(Control) 
permanent sol- dispersions 
vent dispersion of coupler C-4 
of coupler C-4 with no coupler 
coverage of solvent shows 
Example 3 very poor 
0.646 g/m.sup.2 activity as 
reflected in 
its low ADRA 
reactivity, 
low Dmax and 
low contrast. 
2 Precipitated 
109 nm 52200 1.44 
1.09 Precipitated 
(Invention) 
permanent coupler permanent 
2X solvent S-13 coupler sol- 
dispersion of vent incor- 
coupler C-4 of porated coupler 
Example 5 dispersion of 
coverage coupler C-4 
.alpha.0.646 g/m.sup.2 shows very 
good activity 
as reflected in 
high ADRA 
reactivity, 
high Dmax and 
high contrast. 
__________________________________________________________________________ 
EXAMPLE 8 
Co-precipitated Permanent Solvent Containing Dispersion of Image Coupler 
C-7, DIR Coupler C-3, and Yellow Colored Magenta Coupler C-4 
In this example a coupler solvent incorporated precipitated codispersion of 
the image coupler C-7 (79.90%), the DIR Coupler C-3 (3.5%), and the yellow 
colored magenta Coupler C-4 (16.5%) were prepared by the method of this 
invention containing 1 X permanent solvent S-13 (at a weight equal to 
total couplers present) in the continuous apparatus schematically 
illustrated in FIG. 1. The coupler solution, the crude coupler 
solvent/aqueous surfactant emulsion, and the acid solutions were prepared 
as follows: 
______________________________________ 
Coupler solution: 
Coupler C-7 48.0 g 
Coupler C-3 2.1 g 
Coupler C-4 9.9 g 
n-propanol 240.0 g 
20% NaOH solution 
15 g 
315.0 g 
Flow rate: 17.5 g/min 
______________________________________ 
Above ingredients were mixed together and heated to 50.degree. C. to 
dissolve the coupler and then cooled to 30.degree. C. before use. 
______________________________________ 
Crude Coupler Solvent/Aqueous Surfactant Emulsion 
______________________________________ 
Sodium dodecyl sulfate 30 g 
Polyvinyl pyrrilidone 60 g 
Permanent Coupler Solvent S-13 
60 g 
Distilled water 2400 g 
2550 g 
______________________________________ 
A crude emulsion of the above ingredients was prepared by simple agitation 
in a vessel and 500 ml placed in vessel 104 of the continuous equipment 
shown in FIG. 1 and the rest in vessel 92 which was stirred with stirrer 
93 to maintain the crude emulsion. Stirrer 116 was started. 
Acid solution: 15% propionic acid solution was placed in vessel 96. 
To start the continuous precipitation, the coupler solution pump 112 was 
started at a constant flow rate of 17.5 g/min. As the coupler solution 
entered the reaction chamber 104, the pH of the reaction chamber 
increased. This was sensed by the pH electrodes and signal sent to the 
controller. The controller then produced a proportional signal compared to 
the set pH of 6.0 to the acid pump 118, which pumped acid into the 
reaction chamber to neutralize the base and induce precipitation of the 
coupler. The precipitated coupler in the presence of the water miscible 
auxiliary solvent prepared absorbed the permanent solvent from the crude 
emulsion of S-13, the permanent solvent and then the permanent solvent 
loaded precipitated codispersion was formed. The formed dispersion was 
pumped out of the reaction vessel 104 via line 114 by the pump 132 set at 
20 g/min. The line 116 maintained a constant head in the reaction vessel 
at a volume of about 500 ml, such that pump 132 being on during the run, 
the formed dispersion was only pumped into the reservoir 158 when the 
dispersion volume in the reaction vessel was greater than 500 ml. At the 
end of the precipitation, the dispersion in vessel 158 was dialyzed 
against distilled water to remove the salt and the auxiliary solvent 
propanol. The codispersion had a particle diameter of 195 nm as measured 
by PCS. 
The dispersion was prepared to demonstrate that a permanent coupler solvent 
containing co dispersion of all of the couplers in a photographic layer 
can be prepared by the method of this invention. 
The invention has been described in detail with particular reference to 
preferred embodiments thereof, but it will be understated that variations 
and modifications can be effected within the spirit and scope of the 
invention.