Note: Descriptions are shown in the official language in which they were submitted.
--1--
PHOTOGRAPHIC PROCESSING CONCENTRATES
BACKGROUND OF THE INVENTION
. _ _
Field of the Inv tion
This invention relates in general to photo-
5 graphy and in particular to photographic processing
compositions such as developing compositions, fixing
compositions, bleaching compositions, bleach-fixing
compositions, stabilizing compositions, and the llke.
More specifically, this invention relates to photogra~
10 phic processing compositions in a highly concentrated
form which is advantageous for packaging, transporting
and storage and is adapted to be readily diluted with
water or other liquid medium to form a workingsolution.
Descri~tion of the Prior Art
The processing of photo~raphic elements 5 ~
such as elements comprising one or more silver halide
emulsion layers, is typically carried out with aqueous
processing solutions comprising one or more processing
agents. In the form in which they are employed, these
solutions are relatively dilute and thus it is not
generally feasible, from an economic standpoint~ to
package, transport and store processing solutions of
working strength since this would involve the packag-
ing, transporting and storage of large amounts ofwater.
Heretofore, there have been two distihctly different
approaches taken to the problem of packaging photogra-
phic processing compositions in a form that is suitable
for transporting and storage. One approach involves
the preparation of dry powder mixes which must be dis-
solved in water and then diluted to the proper volumebefore use. The other approach involves the prepara-
tion of liquid concentrates, that is~ concentrated
solutions which merely have to be diluted with water
to obtain a working strength solution. Examples of
such packaged processing formulations are described
in numerous patents and publications, for example,
the dry powder developer mixes of U. S. patents
2,843,484 and 2,846,308~ the black-and-white developer t~
liquid concentrates of U. S. patents 3~467,521,
~.
-2-
3~532,49~, 3,854,948 and 4,046,571, and the color
developer liquid concentrates of U. S. patents
3~574,619, 3S647,461~ 3,814,606, and published British
patent application No. 2,016,723.
Each of the prior art procedures possesses
both advantages and disadvantages. For example~ khe
use of dry powder mixes avoids the expense involved in
shipping and storing of water and enables the prepara-
tion of compact light~weight packages that require
little storage space. However, dry powder mixes are
highly disadvantageous in that they are difficult to
handle, create a hazard as a result of the generatlon
of dust, require highly accurate weighing and dispens
ing techniques which are difficult to control, and
often require difficult and time-consuming procedures
to bring about dissolution in water during preparation
of the working strength solution. On the other hand,
liquid concentrates are very convenient to use and much
less hazardous, since they eliminate the dust problem,
and they can be very readily diluted to working strength
without the need for laborious mixing procedures.
However, even though these solutions are concentrated3
they still contain a considerable amount of water, and
it is very expensive to have to transport and store
this water. Thus, for example, typical liquid concen-
trates used in photographic processing are of a concen-
tration such that as much as about two-thirds of the
total weight is water. Moreover, there is a severe
problem involved with liquid concentrates in that,
with many photographic processing compositions, there
is a tendency for chemlcal interactions to take place
between certain of the components, and this frequently
prevents the compounding of all of the components in a
single liquid concentrate, and necessitates the separa-
tion of the components lnto two or more parts which aresubsequently combined to form the working solution.
Often~ as many as three or four different parts are
required, and this greatly complicates the packaging
operation and adds to the expense of manufacture~
transport, and storage. For example, black-and-white
developers of the hydroquinone/pyrazolidone type are
typically packaged as a two-part liquid concentrate
system3 as described in United States patents 3,532,498
and 3,854,948. However, with developers of this type
which contain an aldehydic hardening agent, as is
typical in machine processing of X-ray films, it is
the usual practice to package as a three-part liquid
concentrate system as illustrated, for example, by
10 U. S. patent 4,046,571. Color developers containing
primary aromatic amino color developing agents are
typically packaged as a liquid concentrate system com-
prising at least two parts, and sometimes three or four
parts, as illustrated, for example, by UO S. patents
3,647,461 and 3,814,606.
It is known to formulate photographic process-
ing agents in tablet form. Such tablets are described,
for example, in Canadian patent 831,928. This has many
advantages but is not, in general, a feasible commer-
cial alternative to the use of dry powder mixes orliquid concentrates. In particular, the preparation
of tablets is a complex and expensive procedure, and
many photographic processing compositions are of a
nature such that they are not amenable to tablet forma-
tion. Moreover, tablets usually require the use oflarge amounts of binding agents, and these agents can
make dissolution of the tablet quite difficult and/or
cause adverse sensitometric ef~ects in processing.
One approach to the problem of promoting prompt dis-
solution of photographic processing tablets is to
incorporate effervescing agents therein. However, use
of these materials is generally not very effective and
introduces additional costs and complexity in the
manufacturing operationO
Proposals have been made in the past to for-
mulate photographic processing concentrates as paste~
like compositions For example, British patent
No. 4689 -- A. Do 1894 describes black-and-white
developer concentrates having the consistency of a
-4~
paste or cream, Italian patent No. 427,967 describes
black-and-white developer concentrates which are pre-
pared in paste ~orm, U. S. patent 2,735~774 describes
fixer concentrates of paste-like consistency~ and U. SO
5 patent 2g784,0~6 describes black-and-white developer
concentrates that are formulated in the form of a
smooth gel. However, prior art processing concentrates
of paste-like consistency have typically depended on
the use of suspending, thickening, binding or gelling
agents to maintain solid constituents in a uniform
suspension, and have lacked the properties necessary
to meet high quality performance specifications. Thus,
for example, they have suffered from such problems as
poor flow characteristics which render them very dif-
~icult to handle, lack of chemical stability, atendency to separate, cake or crystallize, and poor
solubility characteristics, such that they have been
difficult to dissolve. Use of the suspending, thicken-
ing, binding or gelling agents adds substantially to
the cost and complexity of the manufacturing operation
and can create problems of microbiological growth
formation and the formation of scums and residues in
processing operations. Moreover, there are very few3
if any~ agents that will function effectively under
conditions of high pH and/or high salt concentration.
In some instances, paste like processing concentrates
have been prepared without the use of suspending,
thickening, binding or gelling agents, but these compo-
sitions have exhibited similar disadvantageous
characteristics~
It is toward the objective of providing
photographic processing concentrates of paste-like
consistency in a form that overcomes the problems of
prior art pastes and provides many of the advantages
of dry powder mixes, while~ at the same time, provid-
ing many of the advantages of liquid concentrates3
that the present invention is directed.
SUMMARY OF THE INVENTION
~ . . _
In accordance with this invention, photogra-
phic processing compositions are packaged, transported,
and stored in the form of a stable paste that is adap-
ted to be readily dissolved in water or other liquidmedium to form a working processing solution. The
paste is comprised of a discontinuous solid phase,
comprising ~inely~divided solid particles associated
in a stable three-dimensional network, distributed
throughout a continuous liquid phase; with the liquid
phase being present in an amount which is much less
than the amount that would be needed to form a solution
of the solid phase, and is just sufficient to impart a
paste-like consistency. One or more photographic pro-
cessing agents is present in either or both of theliquid and solid phases. The three-dimensional network
formed by the association of the finely-divided solid
particles provides a high degree of stability to the
concentrate, while still permitting it to be readily
dissolved in a liquid medium. It also imparts shear-
thinning characteristics which greatly facilitate dis-
pensing of the concentrate.
The continuous liquid phase can consist o~ a
single liquid or of two or more miscible liquids. It
can be comprised of water, or of one or
more organic liquids, or it can be a mixed aqueous-
organic system. The solid phase typically comprises
one or more of the ingredients of the processing com~
position which are normally solid materials. While
30 liquid or solid ingredients which are not necessary
components of the working processing solution can be
incorporated in the paste when needed, it is frequently
the case that the paste can be prepared solely ~rom the
necessary components of the processing solution, with-
35 out the need to delete any ingredients that would beused in the prior art system of liquid concentrates
nor to add any additional ingredients. In other words,
formulation of the stable paste is achieved by appro-
priate selection of the relative proportions of the
~ L 5 ~
ingredients, appropriate control of the particle sizes
Or the ingredients, and appropriate control of the pro-
cedures whereby they are combinecl.
Most surprisingly, it has been found that in
5 using the paste form o~ concentrate which is described
herein, problems of chemical interaction between in-
gredients, which cornplicate the use of liquid concen-
trates, are frequently much less severe. Thus, in many
instances, all of the necessary ingredients can be
combined together to form a single paste, or the number
of separate parts which is needed in Q system can be
reduced, for example, from three to two or from four to
three. Typically, the paste will have excellent shelf-
life properties, and will be capable of being readily
diluted with water or other liquid medium to form a
working strength solution that performs in a manner
indistinguishable from a working strength solution
prepared from liquid concentrates. Also, the pastes
described herein are readily adaptable to use in auto-
20 matic or semi-automatic procedures for delivery to the
processing system, and thus are ~ust as convenient to
use as liquid concentrates and much more convenient
than dry powder mixes.
The photographic processing concentrates des-
cribed herein are stable, non-separating, non-caking,
non-crystallizing and readily dissolvable in a liquid
medium to form a working processing solution. Con-
sidering the complexity and inherent sensitivity to
deterioration of modern day photographic processing
30 compositions, particularly such highly complex compo-
sitions as color developers and X-ray developers, it
was unexpected and surprising to find that a processing
concentrate could be formulated in paste form -- to
thereby obtain important advantages in regard to packag-
35 ing, transport and storage resulting from its excellentstability and low bulk -- and yet could be easily con-
verted from the paste form to a working solution that
will perform equally as well as a working solution
prepared from liquid concentrates. It was even more
-7- Pl~ 5~
unexpected and surprising to find that preparation
of processing concentrates in paste form can greatly
simplify packaging by enabling all components to be
incorporated together, or at least reducing the number
of component parts into which they must be separated.
DESC~IPTION OF THE PREFERRED E~BODIMENTS
With photographic processing compositions
in which all processing agents are normally solid
materials, it is ordinarily feasible to prepare the
paste of the present invention by combining these
solid materials in finely-divided form in the correct
proportion and appropriate order with the appropriate
amount of water, or other liquid medium, and thoroughly
blending them together, taking due care to ensure that
the finely-divided solid particles are associated in a
stable three-dimensional network, as hereinafter des-
cribed in full detail. Similarily, with processing
compositions in which some of the processing agents are
normally solid materials and others are normally liquid
materials, it is ordinarily feasible to prepare the
paste of the present invention by combining the solid
materials, the liquid materials and water, all in the
appropriate proportions, and thoroughly blending them
together. In instances where several of the processing
agents are liquids, little or no water may be required.
In some instances, it may be advantageous in forming
the paste to utilize either liquid or solid iner~
materials which do not have any processing function,
i.e ~ which are not processing agents, but which pro-
3 mote the desired formation of the paste. Thus, eitheror both of the solid phase and the liquid phase can be
composed solely of active agents~ and the use of inert
materials is optional, depending on the characteristics
of the active agents and the properties desired in the
concentrate. Most preferably, the paste-like concen~
trates of this invention are prepared without the use
of any suspending, thickening, binding or gelling
agents, as these agents typically exhibit many charac-
teristics which render their use undesirable in
photographic processing compositions.
The term "photographic processing agent" is
used herein to refer to a material used to develop or
otherwise process a photographic element, for example,
ko develop, fix, bleach, harden, stabilize, and the
like. Thus, the processing solutions prepared ~rom
the pastes described herein can be any of the solutions
used in processing photographic materials such as, for
example, black-and-white developing solutions, color
developing solutions, fixing bathsg bleaching baths,
stabilizing baths, stop baths, nucleating baths, mono-
baths, bleach-fixes, prehardeners, activators, condi-
tioning baths, toners, neutralizers, and the like.
Developing agents of both organic and inor-
15 ganic types are well known in the photographic art.Useful classes of organic developing agents include
hydroquinones, catechols, aminophenols, pyrazolidones,
phenylenediamines, tetrahydroquinolines, bis(pyridone)
amines, cycloalkenones, pyrimidines, reductones and
coumarins. Useful inorganic developing agents include
compounds of a metal, having at least two distinct
valence states~ which are capable of reducing ionic
sil~er to metallic silver. Such metals include iron,
titanium, vanadium, and chromium ~nd the metal com-
25 pounds employed are typically complexes with organiccompounds such as polycarboxylic acids or aminopoly-
carboxylic acids.
A particularly important class of black-and-
white developing a~ents are the dihydroxybenzenes such
30 as~ for example~
hydroquinone,
chlorohydroquinone,
bromohydroquinone,
isopropylhydroquinone,
toluhydroquinone,
methylhydroquinoneg
2,3-dichlorohydroquinoneg
2,5-dimethylhydroquinone,
2,3-dibromohydroquinoneg
1,4-dihydroxy 2-acetophenone-2,5-dimethylhy-
droquinone,
2,5-diethylhydroquinone~
2,5-di-p-phenethylhydroquinone,
2,5-dibenzoylaminohydroquinone,
2,5-diacetaminohydroquinsne,
and the like.
A further particularly important class of
black-and-white developing agents are the 3-pyrazoli-
dones. Useful compounds of this class include those
substituted in the l-position by a monocyclic aryl
group of the benzene series, including phenyl and sub-
stituted phenyl such as p-tolyl, p-chlorophenyl, etc.
A typical compound of this type is l-phenyl-3-pyra-
zolidone. In addition to this substitutlon in thel-position, the pyrazolidone nucleus can be substitu-
ted in the 4-position~ particularly by lower alkyl and
substituted lower alkyl groups such as methyl and
hydroxymethyl. Representative compounds of this class
are 1-phenyl-4-methyl-3-pyrazolidoneg l^phenyl 4-
hydroxymethyl-3-pyrazolidone, 1-phenyl-4,4-dimethyl-3-
pyrazolidone, and l-phenyl-4,4-di(hydroxymethyl)-3-
pyrazolidone.
Color developers typically contain primary
aromatic amino color developing agents. These color
developing agents are well known and widely used in a
variety of color photographic processes. They include
aminophenols and p-phenylenediamines
Examples of aminophenol developing agents
include o aminophenol, p-aminophenol, 5-amino-2-hydroxy-
toluene, 2-amino-3-hydroxy-toluene, 2-hydroxy-3-amino-
1,4-dimethylbenzene, and the like.
Particularly useful primary arsmatic amino
color developing agents are the p-phenylenedia~ines
and especially the N-N-dialkyl-p-phenylenediamines in
which the alkyl groups or the aromatic nucleus can be
substituted or unsubstituted. Examples of useful
p-phenylenediamine color developing agents include:
--10 -
N-N-diethyl-p-phenylenediamine monohydro
chloride,
4-N,N-diethyl-2-methylphenylenediamine
monohydrochloride,
4-(N-ethyl-N-2-methanesulfonylaminoethyl)-
2-methylphenylenediamine sesquisulfate
monohydrate,
4-(N-ethyl-N-2-hydroxyethyl 3 -2-methylpheny-
lenediamine sulfate,
4-N~N-diethyl-2,2'-methanesulfonylamino-
ethylphenylenediamine hydrochloride,
and the like.
An especially preferred class of p~phenylene-
di~mine developing agents are those containing at least
one alkylsulfonamidoalkyl substituent attached to the
aromatic nucleus or to an amino nitrogen. Other es-
pecially preferred classes of p-phenylenediamines are
the 3-alkyl-N-alkyl-N-alkoxyalkyl-p-phenylenediamines
and the 3-alkoxy-N-alkyl-N-alkoxyalkyl-p-phenylene-
diamines. These developing agents are descrlbed in
United States Patents 3,656,950 and 3,65~,525 and can
be represented by the formula:
CH3 - CH2 - N ~ (CH2)n
I~J
NH2
wherein n is an integer having a value o~ from 2 to 4,
R is an alkyl group of from 1 to 4 carbon atoms, and
Rl is an alkyl group of from 1 to 4 carbon atoms or
an alkoxy group of from 1 to 4 carbon atoms. Illustra-
tive examples of these developing agents inclu~e the
following compounds:
N-ethyl-N-methoxybutyl-3-methyl-p-pheny-
lenediamine,
N-ethyl-N-ethoxyethyl-3-methyl-p-pheny-
lenediamine,
5 ~ ~ i6 8
N-ethyl-N methoxyethyl 3-n-propyl-p-pheny-
lenediamine,
N-ethyl-N-methoxyethyl-3-methoxy-p-pheny-
lenediamine,
N-ethyl-N-butoxyethyl 3-methyl-p-phenylene-
diamine,
and the like.
In addition to the primary aromatic amino
color developing agent~ color developer compositions
typically contain a variety o~ other agents such as
alkalies to control pH, bromides, iodides, benzyl
alcohol, anti-oxidants, solubilizing agentsg sequester-
ing agents~ brightening agents, and so forth.
In the production of color photographic
images, it is necessary to remove the silver image
which is formed coincident with the dye imagel This
can be done by oxidizing the silver by means o~ a suit-
able oxidizing agent, commonly referred to as a bleach
ing agent, in the presence of halide ion followed by
dissolving the silver halide so formed in a silver
halide solvent, commonly referred to as a fixing agent.
Alternatively, the bleaching agent and fixing agent can
be combined in a bleach-fixing solution and the silver
removed in one step by use of such solution. A variety
of bleaching agents are known for use in photographic
processing~ for example, ferricyanide bleaching agents,
persul~ate bleaching agents, dichromate bleaching
agents~ permanganate bleaching agents, ferric chloride
and water-soluble quinones.
A particularly important group of photogra-
phic bleaching agents are the aminopolycarboxylic acid
bleaching agents. They are typically utilized in the
form of water-soluble salts, such as ammonium or alkali
metal salts, of a ferric aminopolycarboxylic acid com-
plex. A typical example is the ammonium salt of ferric
ethylenediaminetetraacetic acid (NH4FeEDTA), which is
also known as ammoni~ ethylenedinitrilotetraacetato
ferrate (III)~ Many other aminopolycarboxylic acids in
addition to ethylenediamine tetraacetic acid are also
-12-
useful such as, for example:
nitrilotriacetic acid~
diethylenetriamine pentaacetic acid,
ortho-diamine cyclohexane tetraacetic acidg
ethylene glycol bis(aminoethyl) ether)
tetraacetic acid,
diaminopropanol tetraacetic acid~
N-(2-hydroxyethyl)ethylenediamitle triacetic
acid 3
ethyliminodipropionic acid,
and the like.
The aminopolyacetic acids are preferred, as they are
readily available and provide particularly good
bleaching action~
Fixing agents used in photographic processing
include thioureas, thiocyanates, thiosulfates, mercapto-
containing compounds such as mercapto acetic acid,
quaternary ammonium salts, polyamines such as tetra-
ethylene pent~nine, and the like. In bleach-fix com-
20 positions, it is common to employ thiosulfates as fixing
agents, typically ammonium thiosulfate or alkali metal
thiosulfates such as sodium thiosulfate and potassium
thiosulfate.
Bleach and bleach-fix compositions can con-
25 tain a wide variety Qf addenda known to the art to be
useful in such formulations, including amines, sulfites,
mercaptotriazoles~ alkali metal bromides, alkali metal
iodides, and the like~
Agents for hardening of gelatin or other
30 hydrophilic colloids employed in photographic elements
are often used in processing. For example, they can be
incorporated in fixing baths, or in developing baths or
utilized in the form of prehardener solutions. In
hardening fix baths~ it is common to utilize an alumi~
35 num or zirconium salt as the hardening agent. In
developers and prehardeners~ any of a very wide variety
of hardening agents can be employed. Such hardening
agents include aldehydes such as formaldehyde~ dialde-
hydes such as succinaldehyde and glutaraldehyde,
-13~
~- diketones~ sulfonate estersg active halogen
compounds, and the like.
In color reversal processing of photographic
elements~ it is common to utilize nucleating agents to
take the place of reversal re-exposure. Nucleating
agents can be incorporated in a color developing solu-
tion or in a separate bath which is used between first
development and color development. Useful classes of
nucleat~ng agents include alkali metal borohydrides,
ionic boron ~ydrides containing two or more boron atoms
per molecule, amine boranes, polyamine boranes,
phosphine boranes, arsine boranes, stibine boranes
borazines, chelated stannous salts, and the like.
A final step in many color photo~raphic pro-
cesses involves treatment of the element with a sta-
bilizing bath, which serves to stabilize the dye images.
Such baths frequently include a wetting agent, for
example, a polyoxyalkylene compound, and an aliphatic
aldehyde, for example, ~ormaldehyde, paraformaldehyde,
acetaldehyde, aldol, crotonaldehyde, and the like.
While certain common photographic processing
agents that can be used in the paste formulations of
this invention have been described in some detail above,
it should be understood that the present invention is
not limited to these particular processing agents, but
is broadly applicable to any of the wide diversity of
compositions used in the processing of photographic
elements.
Processing of black-and-white photographic
elements is generally quite simple, involving only the
steps of developing and fixing. Color processing can
involve a two-step process, such as a process employ-
ing the steps of color developing and bleach~fixing,
or more complicated processes such as a process employ-
ing a prehardener, a neutralizer, a first developerg acolor developer, a bleach, a fix and a stabilizer.
The present invention can be advantageously utilized
with simple processés or with those employing a
compiicated series of steps. It is usefu~ in black-
; ~ 5
-14-
and-white processing (including X-ray processing and
processing of lithographic films), in the processing
of photographic elements designed for reversal color
processing, in the processing of negative color ele-
ments~ and in the processing of color print materials.It can be employed with photographic elements which are
processed in color developers containing couplers or
with photographic elements which contain the coupler
in the silver halide emulsion layers or in layers con-
tiguous thereto. The photosensitive layers present inthe photographic elements processed according to the
method o~ this in~ention can contain any of the conven-
tional silver halides as the photosensitive material,
for example, silver chloride, silver bromide, silver
bromoiodide, silver chlorobromide, silver chloroiodide,
silver chlorobromoiodide, and mixtures thereof. These
la~ers can contain conventional addenda and be coated
on any of the photographic supports, such as, for
example~ cellulose nitrate film, cellulose acetate
film~ polyvinyl acetal film, polycarbonate film, poly-
styrene film, polyethylene terephthalate film, paper,
polymer-coated paper, and the like.
The solid material used in preparing the
paste-like concentrates of this invention is typically
comprised of one or more normally solid processing
agents, e.g., such solid processing agents as the salts
of p-phenylenediamines which are commonly used as color
developing agents. However, where the desired process-
ing composition does not require any processing agents
which are normally SOlidg or requires an insufficient
proportion o~ such agents to render the formation of
a paste feasible, inert particulate components which
do not perform a processing function, but are added
solely to facilitate formation of the paste, can be
35 utilizedO Useful materials for this purpose include
a wide ~ariety of finely-divided inert solid materials
such as silicon dioxide, sodium sulfate, and diatoma-
ceous earth.
Formation of the paste-like photographic
15-
processing concentrates of this invention requires the
use of solid particles in vcry finely-divided form.
Because the solid particles are very finely-divided,
they provide a very large surface area per unit of
weight. The amount of surface area is an important
factor in determining the physical characteristics of
the paste-like concentrateg especially its rheological
properties. The desired small particle size and high
surface area can be achieved by grinding which takes
10 place during blending of the materials in forming the
concentrate, or by grinding individual ingredients
prior to blending. The actual particle size employed
can vary widely, depending on the particular processing
formulation involved. Xowever3 the photographic pro-
cessing concentrates of this invention are typicallycharacterized by the presence of particles of very
small size. Generally speaking, it is desirable that
the finely-divided solid particles have a size below
about 100 microns, preferably below about 25 microns,
and most preferably below about 3 microns.
The liquid phase of the paste-like concen-
trates of this invention can take a variety of forms.
In appropriate situations, e.g., those where the pro-
cessing formulation does not employ any processing
agents which are liquids, water can be used as the sole
liquid ingredient forming the liquid phase. In other
instancesJ one or more l~quid processing agents, or a
combination of water plus one or more liquid processing
agents can be utilized. Inerk organic liquids, i.e~,
those which do r,ot have a processing function, can be
added in order to promote formation of the paste,
if desired.
The photographic processing concentrates
described herein are made up of a discontinuous solid
35 phase that is distributed throughout a continuous
liquid phase. Thus, the two phases are in intimate
association with one another and interact to provide
the properties exhibited by the paste. The liquld
phase must not be present in either too great or too
-16 -
small an amount in relation to the solid phase or the
resulting product will not have the desired paste-like
consistency. The actual ratio of liquid to solid in
the concentrate can vary widely, depending on the par-
5 ticular processing formulation involved, and suchfactors as particle size. Generally speaking, it is
desirable khat the liquid phase be present in an amount
of from about 0.05 to about o.8 parts per part of solid
phase by weight, and more pre~erably in an amount of
10 from about 0.1 to about o.6 parts per part of solid
phase by weight.
The photographic processing concentrates of
this invention are characterized by a very low ratio
of liquid to solid in comparison to prior art photogra-
15 phic processing concentrates. A typical example of acolor developer liquid concentrate of the prior art is
that described in Example 1 of U. S. patent 3,~47,461.
This developer concentrate contains 2 grams of sodium
sulfite and 6.4 grams of 4-amino-N-ethyl-N-(~-methane-
20 sulfonamidoethyl)-m-toluidine sesquisulfate monohydrate
dissolved in 11 grams of water. This is a weight ratio
of liquid to solid of 1.3 to 1. In comparison, the same
formulation prepared in the form of a paste-like con
centrate in accordance with this invention would typi-
25 cally have a ratio of liquid to so:lid of about o.6 to 1.A typical example of a black-and-white developer liquid
concentrate of the prior art is that described in
Example 1 of U. S. patent 3~467,521. This developer
concentrate contains 312 grams of potassium sulfite3
30 15 grams of potassium hydroxide, 90 grams of potassium
carbonate~ 45 grams of hydroquinone, 1.5 grams of 1-
phenyl-3-pyrazolidone, 10 grams of potassium bromide
and 8 grams of ethylenediaminetetraacetic acid dissolved
in sufficient distilled water to give a volume of 1
35 liter. This is a weight ratio of liquid to solid of
approximately 1 to 1. In comparison, the same for~u-
lation prepared in the form of a paste-like concentrate
in accordance with this invention would typically have a
ratio of liquid to solid of about 0.25 to 1. A typical
-17~
example of a prior art developer paste is that des-
cribed in Example 1 of U S. patent 2,784,o86. This
developer paste is prepared by adding 24.0 grams of
sodium sulfite, 45.0 grams of sodium carbonate3 1.6
grams of monomethyl p-aminophenol sulfate, 4.8 grams
of hydroquinone~ 1.0 grams of potassium bromide and
2.0 grams of sodium tetraphosphate to 90 milliliters
of a 2% solution of the sodium derivative of algin.
This is a weight ratio of liquid to solid o~ approxi~
mately 1 1 to 1. In comparison, a comparable devel-
oper prepared in the form of a paste-like concentrate
in accordance with this invention would omit the algin
derivative and would typically have a ratio of liquid
to solid of about 0.25 to 1.
Photographic processing agents present in
the paste-like concentrates of this invention can be
present in either or both phases. Frequently, a
processing agent which is a solid material will be
distributed between the solid and liquid phases, with
the amount present in each being determined, ln part,
by its solubility characteristics. For example, the
p-phenylenediamines that are used in color developers
will typically be distributed between both phases with
a major proportion, e~g., 90~, being in the liquid
phase, and a minor proportion~ e.g., 10%, being in the
solid phase.
Typically, the photographic processing con-
centrates of this invention are prepared in the form
of a stiff paste, but the degree of fluidity of these
compositions can be varied to a very considerable ex-
tent, as desired, so that pastes with either a pourable
or non-pourable consistency are within the contemplated
scope of this inventionO Thickening or suspending
agents are not usually needed in the processing concen-
trates of this invention, but their use is optional,and they can be employed3 if desired. Generally
speaking, the paste-llke concentrates are readily dis-
solved in water, even with the use of only very simple
stirring equipment such as a hand-held paddle. Improved
-18-
results, however, are usually obtained when they are
dissolved with the aid of mechanical stirring devices
that provide much higher mixing speeds than can be
achieved by hand. While the concentrates disclosed
herein can be characterized as being stable, non-
separating, non-caking~ non-crystallizing and readily
dissolvable in a liquid medium to form a working
processing solution, such terms are, of course, rela-
tive terms, and it is intended by use of these terms
only to indicate that the concentrate possesses these
characteristics to a degree sufficient to be useful
for its intended purpose.
It should be noted that processing concentra-
tes prepared in the paste form described herein are
not intended to be used, as such, in processing photo-
graphic materials, but only after being dissolved in
the appropriate amount of water or other liquid medium
to form a working strength solutionO Thus, the ob-
jectives and purposes of this invention are clearly
different than in the case of prior art inventions
where photographic processing compositions have been
converted to forms other than true solutions with the
intention that they be used in such form in the pro-
cessing of phokographic elements, for example, the
~5 processing compositions in the form of a foam as
described in U. S. patent 2,860,977, the solid fusible
processing compositions of U. S. patents 3,347,675 and
3,438,776, and the viscous processing composi`tions of
U. S. patent 3,392,019. The concentrates of this
invention are designed to facilitate packaging, trans-
port and storage, a~d this involves dlstinctly differ-
ent considerations and problems than were involved in
the aforesaid prior art inventions that were seeking
to simplify processing operations per se.
It should also be noted that the paste-like
concentrates of this invention are characterized by a
very low ratio of liquid to solid. It is this feature
that provides the desired low bulk characteristics that
provide substantial cost savings in packaging,
\~
- 1~
transport and storage. In this regard, the concentra-
tes of this invention are clearly distinct from photo-
graphic processing concentrates of the prior art~ which
have utilized relatively large proportions of w~ter,
5 but have had high viscosity in spite of the high water
content because of the presence of large amounts of
colloidal thickening, binding, gelling, or suspending
agents.
The paste-like photographic processi~g con-
1~ centrates of this invention are characterized by the
presence of ~inely-divided solid particles associated
in a stable three-dimensional network. A variety of
mechanisms can result, separately or in combination,
in the creation of such a networkO For example, with
certain processing formulations, the finely-divided
solid particles are present in the form of aggregates
or clusters of particles, and such systems can, there-
fore, be described as flocculated. In such a floccu-
lated suspension, particles associate, through
20 electrical forces, to other particles, and it is this
attraction into a network which imparts stability.
With other formulations, network formation is dependent
upon morphological association; for example, particles
of needle-like structure are generated in blending and
25 grinding of the ingredients, and such particles asso-
ciate in a stable three-dimensional network as a con-
sequence of their shape. In still other formulations,
certain of the components are present in the form of
intermolecular association products which create a
stable three-dimensional network through physical and
chemical interaction, but readily dissociate when the
paste is diluted with water.
The term "stable" is used herein in reference
to the three-dimensional network in the sense of being
descriptive of its capability of functioning to maintain
the desired even distribution o~ materials throughout
the paste-like concentrate during a shelf life of
adequate duration to meet the requirements o~ the
photographic art
~L
- 20-
The presence in a photographic processing
concentrate of the stable three-dimensional network
described herein is evidenced by a yield point and
by rheological behaviour that can be characterized
as shear-thinning orpseudoplastic~ The network results
from the association of finely-divided particulates
through mechanisms such as those outlined above. The
dimensions of the network are perhaps best characteri-
zed by the ~;stances over which a disruption of one
point has an effect at another point. These dimensions
are dependent on the materials and methods of formula-
tion and can range from a few tens of microns up to
many centimeters.
A processing concentrate in the form of a
flocculated colloidal suspension is illustrated by a
p-phenylenediamine color developer formulation contain-
ing both benzyl alcohol and triethanolamine. Color
developers containing these two ingredients are des-
cribed in U0 S. patent 4,170,478. In this systemg
two immiscible solvents, benzyl alcohol and water, are
made miscible by the addition of a third solvent,
triethanolamine~ which is completely miscible with
both of the other solvents. Thus, benzyl alcohol and
water are immiscible in any quantity of benzyl alcohol
greater than one gram in twenty-five milliliters of
water, and of more than one milliliter of water in ten
grams of benzyl alcohol. The addition of triethanola-
mine increases the solubility of benzyl alcohol in water
and vice versa. In this system, flocculation is
dependent upon maintaining a low water concentration.
This can be explained, in part, by the fact that with a
low concentration of water~ there is a low ionic
strength, since salts present in the formulation will
not ionize to a high degree in an organic medium.
Under these conditions, flocculation is favored. The
result of flocculation is the association of the finely-
divided particles in a stable three-dimensional network
that is characteristic of the paste-like concentrates
of this invention~
-21~
The photographic processing concentrates of
this invention exhibit good stability characteristics
from the standpoint of both chemical and physical
stability~ For example, they are resistant to aerial
oxidation and to deleterious changes resulting from
chemical reactions between components thereofO They
are also highly advantageous in that they are non-
separating, non-caking, and non crystallizing. These
advantageous characteristics are believed to be impar-
ted to the concentrate by the presence of the aforesaidstable three-dimensional network. Thus, for example~
association of the finely-divided particles in a stable
three-dimensional network maintains larger particles in
suspension, and avoids settling or stratification~
Numerous factors relating to the characteris-
tics of the starting materials and the manner in which
they are combined to form a paste-like concentrate are
believed to interact together to influence the formation
of the stable network of associated particles. Such
factors include the following:
(1) The order in which the ingredients
are combined to form the paste.
(2~ The temperature during formation of the
paste.
(3) The type of mixing equipment used in
forming the paste and the parameters of mixing such as
the degree to which shearing takes place.
(4) The particle size.
(5) The effects of additives which a~e not
processing agents, such as dispersing agents or
thickenersO
(6) The effect of p~ and the chemical en-
vironment during paste for~ation.
-22-
(7) The effect of the ratio of aqueous
to or~anic liquids when both are present.
(~) The effect of the liquid to solid
ratio.
Various exothermic and gas~evolving phenomena
can take place during mixing to form the paste. These
may be explainable in terms of acid-base reactions or
other exothermic chemical reactions. An increase in
temperature occurs during mixing, in part as a result
of chemical reactions, but primarily as a result of
the grinding action of the mixer. Care must be taken
to prevent the temperature from rising to too high a
level~ as this can result in depletion of essential
components of the formulation.
Characteristic features of paste-like photo-
graphic processing concentrates comprising finely-
divided solid particles associated in a stable three-
dimensional network include their shear-thinning
properties and high sedimentation volumes. (A shear-
thinning material is one which has a high viscosity
under low shear conditions, and a low viscosity under
high shear conditions). The shear-thinning properties
possessed by these concentrates are especially signi-
ficant in that they greatly facilitate dispensing of
the concentrates from the containers in which they are
packaged. The particular viscosity and degree of shear-
~hinning exhibited varies greatly among the very wide
range of different processing compositions coming with-
in the scope of the present inventionO For example,
typical concentrates have an apparent viscosity in the
range of from about 250 to about 1300 centipoises at a
hear rate of 800 reciprocal seconds. At a shear rate
of 4500 reciprocal seconds, an apparent viscosity in
the range of from about 100 to about 50p centipoises is
typical. These values re~er to viscosity measurements
made in a HERCULES HI-SHEAR VISCOMETER (rotational
concentric cylinder type) at ambient temperature. The
- _,3_
rotor or inner cylinder (radius 1.95 cm., height 5.0
cm.) is rotated at a constant angular acceleration of
approximately 5.~9 rad/sec2 to a maximum angular
velocity o~ 115 rad/sec. This rotation imparts an
5 increasing rate of shear (maximum 4549 sec 1) to the
sample which is contained in the annulus between the
inner and outer cylinders (annulus width 0.5 cm.).
The torque which is transmitted through the sample to
the outer cylinder is measured and used in calculation
10 of apparent viscosity as a function of rate of shear;
The stable three-dimensional network formed
by association of finely-divided solid particles also
imparts a high sedimentation volume to the concentrate.
Unlike a stable suspension of solid particles, in which
15 the particles act independently, in the concentrates des-
cribed herein, particles exist in a state of association.
As a consequence, the sedimentation volume is large,
whereas the sediment from a stable suspension tends to
pack closely, i.e., to approximate closest packing be-
20 havior, so as to exhibit a considerably smaller sedimen-
tation volume for particles o~ the same dimensions.
Brownian motion can be observed in a stable suspension,
but not in a flocculated system~
The flocculated suspensions have been ~ound to
25 exhibit pronounced thixotropic behavior. In particular,
they tend to become quite fluid when agitated~ butreturn
to a sti~f paste form when at rest. In being mixed~
they are subJect to extreme shearing which prevents ex-
tensive association and in consequence, are ~ree-flowing,
30 while upon standing they become quite viscous and"paste-
like." In terms of flocculation, it is apparent that
standing for a sufficîent time allows further associa-
tion of particles into a network. Given enough time,
the system will proceed to its point of equilibrium,
35 i.e., optimal degree of association. The optimum condi-
tion is dependent upon the particular formulation invol-
ved, that is, the particular ingredients and their
proportions. Once in its equilibrium state, the
material will not readlly dissolve in water. With
24-
the application of shearing energy, the network asso-
ciations, that is, interparticle attractions, are
broken, the viscosity decreases, and the material can
be readily dissolved in waterO
The paste-like photographic processing con-
centrates of this invention are especially advantageous
in the packaging of color developing compositions
comprising primary aromatic amino color developing
agents. Typically, color developers are packaged and
sold in liquid concentrate form, with the chemical
formulation for a given process being divided into the
least possible number of concentrated parts that will
provide good shelf life. Often, the color developer
formulation will contain numerous lngredients~ some-
times as many as fifteen or more, and it will benecessary to separate it into three or four parts in
order to package it in the form of liquid concentrates.
Formation of stable paste-like concentrates, in accor-
dance with the teachings herein, will often permit
packaging of complex color developers containing as
many as fifteen or more ingredients in the form o~ a
single paste or, perhaps, two different pastes. It
was particularly surprising to ~Lnd that problems of
chemical interaction between components of complex
color developer formulations which complicate the use
of liquid concentrates, and necessitate packaging of
as many as four separate liquid concentrates, are
frequently much less severe with the paste-like
concentrates of this invention.
The primary aromatic amino color developing
agents are solid materials which will distribute
themselves between the liquid and solid phases of the
concentrate. In these concentrates, the liquid phase
will typically be comprised of water and at least one
organic liquid, since organic liquids, eOg., benzyl
alcohol, are necessary components of many currently
used photographic color developing compositions.
The starting ingredients for forming the
paste-like concentrates can be liquids, powders, or
A~ 6~
slurries. Typically, the slurries are saturated
solutions with excess solut~s present as undissolved
solids. The ingredients are blended in a high shear
mixing vessel and can be conveyed to this vessel by any
of several methods. Liquids and slurries are usually
pumped, while powders are handled with a screw conveyor
or other powder transport system~ Agitated storage
tanks can be used with the slurries in order to keep
the solids in suspension. For uniformity and proper
consistency, it is necessary to thoroughly disperse
the solids and homogenize the product. This is best
accomplished with hydraulic and mechanical shear pro-
vided by high speed agitators.
Once the paste has been mixed to the desired
consistency, the next step is to convey it to the
package-filling apparatus. If mixing is done directly
above the filling process, the concentrate can be con-
veyed by gravity through a vibrated chute. Alterna-
tivelya the concentrate can be conveyed by pumping,
typically by pumps of the positive-displacement type.
Package filling can be carried out with the use of an
auger system or a piston system~ Packages of a wide
variety of types can be utilized and inexpensive pack-
aging materials, for example, thermoplastics such as
polyethylene, can be employed.
Dispensing of the paste and combining it with
water or other liquid medium to form a working process-
ing solution can be carried out by any suitable method.
There are two basic approaches which are feasible.
The first of these is to dispense and dissolve the
entire contents at one time, i.e., a batch-dispensing
approach. In this instance, it is not necessary that
the paste be entirely homogeneous, since all of the
contents of the package are utilized to form a single
batch of processing æolution. The second approach is
to dispense a portion of the contents o~ the package
intermlttently as needed. In this case, the paste must
be completely homogeneous, since each portion dispensed
must be like every other to give a consistent working
-26- ~5~
solution.
Photographic processing chemicals must be
dissolved in water or other liquid medium in very
precise amounts in order to prepare working processing
5 solutions. Thus, to be commercially useful, a photo-
graphic concentrate must not only possess features
facilitating packaging, transport and storage, but must
be capable of being dispensed in such a way as to
ensure the necessary precision in the preparation of
10 working processing solutions. It is particularly
advantageous for the photographic processing concentrate
to be "volumetrically dispensable." By the term
"volumetrically dispensable," as used herein, is meant
a composition which has flow properties such that it
15 can be dispensed from a package in a metered amount on
a volumetric basisg and which has a high degree of uni-
formity such that each unit volume dispensed contains
essentially the same amount of active agents on a
weight basis. With such a concentrate, it is possible
20 to combine a predetermined volume of concentrate with
a predetermined volume of liquid, e.g., 100 cubic cen-
timeters of concentrate combined with one liter of
water, and consistently obtain the same weight of
active agents in the resulting working solution.
The dilution ratio employed with the process-
ing concentrate, that is, the amount of water or other
liquid used to convert the paste to a working processing
solution, will vary greatly depending on the nature of
the photographic element being processed, the processing
30 procedure, and the particular processing formulation
involved. In general, the dilution ratio will be in
the range from about 1 part of paste to about 8 parts
by weight of liquid to about 1 part o~ paste to about
100 parts by weight of liquidO
The term "a photographic processing concen-
trate" is used herein to refer to a composition
comprising one or more processing agents~ such as
developing agents, bleaching agents, ~ixing agents,
!,`' i~,
~6~
-27-
etc. It can be, but is not necessarily, a composition
that is complete in the sense that it merely needs to
be combined with water, or other liquid medium, to ~orm
a working strength processing solutionO In some in-
5 stances, it will be intended to be combined withanother photographic processing concentrate, as well
as water or other liquid medium, to form a working
strength processing solution, and this other processing
concentrate can be a paste, a powder, or a liquidO
10 For exQmple, a photographic developing solution might
comprise ~ive active agents, namely, a developing
agent, an alkali, an anti~oggant, an anti-oxidant and
a sequestering agent. In utilizing concentrates in
accordance with this invention, it may be advantageous
15 to ~orm a ~irst paste containing the developing agent
and anti-oxidant, and a second paste containing the
alkali, the anti~oggant and the sequestering agent,
and then to combine the first and second pastes
together, along with an appropriate quantity o~ water,
20 to form a working strength developing solution. In
another instance, a photographic processing composition
might require several di~erent solid processing agents
and one liquid processing agent, and the paste-like
concentrate could include only water and the several
25 solid processing agents, while the working strength
solution would be prepared by combining the liquid
processing agent and the paste, along with an
appropriate quantity o~ water.
While the photographic processing concentrates
-28- ~ 5~
described herein have been referred to throughout the
specification as "pastes," and this term is aptly des-
criptive of their characteristics, they could also be
re~erred to by a variety of other terms, such as, for
5 example~ the terms "semi solid~" or "semi fluid" or
"plastic."
The term "a photographic processing solution,
as used herein, is intended to include working solu-
tions~ replenisher solutions, starter solutions, and
lO so forth.
The paste-like photographic processing concen-
trates of this invention can be evaluated by the prepara-
tion of rheograms, that is, plots of shear rate versus
shear stress. In such plots, the viscosity is inversely
15 proportional to the slope of the curve. For a strictly
pseudoplastic or shear-thinning fluid, the values of
shear stress obtained during an ascending series of
shear rates correspond to those obtained in a descending
series of shear rates. In other words, the curve for a
20 descending series retraces the curve for an ascending
series. The occurrence of thixotropic loops in a rheo-
gram provides rheological evidence that the composition
is a structured fluid, that is, one comprising a three-
dimensional network~ Thus, with a thixotropic pseudo-
25 plastic fluid, the rheogram exhibits what can be termeda thixotropic loop or hysteresis loop in that the des-
cending series does not retrace the curve for the
ascending series.
A thixotropic fluid is one which exhibits a
30 time-sensitive viscosity. In other words, the viscosity
decreases with increasing shear duration. When a
thixotropic fluid is sheared at a constant shear rate,
the viscosity decreases with time until some equilibrium
value is reached. This is interpreted by rheologists as
35 the breakdown of a structure present in the fluid.
When an ascending series of shear rates is imposed on a
thixotropic pseudoplastic fluid, and immediately followed
by a descending seriesg the curve is not retraced
A hysteresis loop is produced,with the curve of the des-
40 cending series displaced toward the shear rate axis~
~ . _ .
-29-
This loop is also known as a thixotropic loop and is due
to the breakdown of structur~ with time.
The photographic processing concentrates of
this invention comprise finely~divided soiid particles
5 associated in a stable three~dimensional network which
imparts shear-thinning characteristics to the concen-
trate. Thus, they can be characterized as thixotropic
pseudoplastic fluids.
As previously pointed out, a key feature of
10 the present invention is the low ratio of liquid to
solid, which characterizes the paste-like concentrates.
Such low ratio is rendered feasible by proper compound-
ing of the ingredients of the formulation to achieve a
stable three-dimensional network of associated particles.
15 In prior art attempts to prepare paste-like photographic
processing concentrates, commercial success was not
achieved because the concentrates prepared without the
use of thickening~ gelling, binding or suspending agents
would harden to a hard unusable mass in a relatively
20 short time, e.g., a few days, or would separate into
two or more phases. On the other hand, when thickening,
gelling, binding or suspending agents were employed to
alleviate these problems, other difficulties were en-
countered, such as poor flow characteristics~ crystalli-
25 zation, and limited solubility characteristics. Thepresent invention is predicated on the discovery that
thickening, gelling, binding or suspending agents are
not necessary in pr~cessing concentrates of paste-like
consistency, and that the desired shelf stability can
30 be achieved by careful control of the parameters of the
manufacturing process, including, in particular, such
important parameters as the particle size, the order in
which the ingredients are combined, the degree of mixing
and the ratio of liquid to solid components.
The invention is further illustrated by the
following examples o~ its practice.
Exalæ~
A photographic processing concentrate intended
to be diluted with water to form a color developing
40 solution for developing negative-positive color film
. .
-30-
was prepared in the following manner:
780 milliliters Or a 47$ by weight aqueous
solution of potassium carbonate and 240 grams of pow-
dered potassium sulfite were added to a one-gallon
5 stainless steel Waring Blender, equipped with a cooling
jacket, and blended for two minutes at low speed. 516
grams of 4-(N ethyl-N-2-methanesulfonylaminoethyl)-2-
methylphenylenediamine sesquisulfate monohydrate in the
form of a finely-divided powder was then added slowly
10 while stirring with a spatula. 502 grams of powdered
potassium carbonate was then added, and the mixture
was blended for three minutes at high speed.
The product obtained was a pourable paste
having a weight ratio of liquid to solid of 0.16 to 1
15 which exhibited shear-thinning characteristics. It was
diluted with water in a ratio of 50 grams of water to
one gram of paste and dissolved readily to produce a
working color developing solutionc
Example 2
A photographic processing concentrate intended
to be diluted with water to form a hardening developer
for processing X-ray film was prepared as a two-part
paste formulation in the following manner:
To prepare the first part, 787.5 grams of
25 potassium hydroxide (45% aqueous solution), 1545.69
grams of potassium sulfite, 157.5 grams of sodium bicar-
bonate; 21 grams of boric acid, 35 grams of ethylene-
diaminetetraacetic acid, 1.26 gr~ms of 5-methylbenzotri-
azole, 5.25 grams o~ 5-nitroindazole, 630 grams of
30 hydroquinone and 175 grams of water were thoroughly
blended together. The product obtained was a pourable
paste which had a weight ratio of liquid to solid of
0.22 to 1 and exhibited shear-thinning characteristics.
To prepare the second part, 100 grams of
35 glycerol and 150 grams of water were added to a one-
quart Osterizer Blender and blended at slow speed.
31.5 grams of powdered 1-phenyl-3-pyrazolidone was added
and blending was continued for about 2 minutes. 31701
grams of powdered glutaraldehyde bis bisulfite was added
_ _ .
-31-
slowly, using a spatula to work it into the mixture as
- necessary, and blending was continued for about 3 ~.in-
utes. The product obtained was a pourable paste which
had a weight ratio of liquid to solid of 0.7 to 1 and
exhibited shear-thinning characteristics.
To prepare a working developing solution, 5.6
grams of the first paste and 1.0 grams of the second
paste were combined with 30 grams of waterS Both pastes
dissolved readily to thereby produce a developing solu
tion suitable for the processing of X-ray film.
Example 3
A photographic processing concentrate inten-
ded to be diluted with water to form a color developing
solution for developlng color prints was prepared from
the following ingredients:
Components ~
1. Benzyl alcohol 493 milliliters
t 2. l-Hydroxyethylidene-l,l-
¦ . diphosphonic acid (60% by
weight aqueous solution) 40 milliliters
3. Potassium carbonate (anhydr~us) 1600 grams
4. Potassium sul~ite (anhydrous) 100 grams
5. Potassium bromide 16.7 grams
6. Hydroxylamine sulfate 170 grams
7. 4-(N-ethyl-N-2-methanesulfonyl
aminoethyl)-2~methylphenylene-
diamine sesqulsulfate
monohydrate 215 grams
8. Lithium sul~ate 89 grams
These ingredients were added in the order
specified to a one-gallon stainless steel Waring Blender
equipped with a cooling jacket. Mixing was carried out
.,~...... .
. :,.
86
-32-
at a high speed for times of 30 seconds for addition of
ingredient 2, 15 seconds for addition of ingredient 3,
2 minutes for addition of ingredient 4, 1 minute for
addition of ingredient 5, 2 minutes for addition of in-
5 gredient 6, 3 minutes for addition of ingredient 7, and1 minute for addition of ingredient 8.
The product obtained was a pourable paste
having a weight ratio of liquid to solld of 0.3 to 1
which exhibited shear-thinning characteristics. It was
10 diluted with water in a ratio of 18 grams of water to
one gram of paste and dissolved readily to produce a
working color developing solution.
Example 4
A photographic processing concentrate intended
15 to be diluted with water to form a color developing so-
lution for developing color prints was prepared from
the following ingredients:
Com~onent Wei~ht (grams
1. Triethanolamine 960.0
20 2. Benzyl alcohol 1071.0
3. Sulfonated fatty acid surfactant 2.0
4. Potassium hydroxide (45~ by weight
aqueous solution) 291.2
5. Potassium hydroxide (85~ solid)370.0
25 6. l-Hydroxyethylidene~ diphosphonic
acid (60~ by weight aqueous
solution) 92.8
7. Potassium bromide 11.2
8. Potassium sulfite 40.0
-33- ~ 5
Component Weight (grams~
9. Amino-substituted ctilbene
brightening agent 240~0
10. Lithium sulfate 224.0
5 11. Hydroxylamine sulfate 504.0
12. 4-(N ethyl-~r-2-methanesulfonyl~
aminoethyl)-2-methylphenylene-
diamine sesquisulfate
monohydrate 544.0
10 13. Potassium carbonate 2000.0
Components 1 to 5 were added to a 6-literVME-6
mixer manufactured by Fryma-Maschinen AG, and blended
while cooling to a temperature of 17C. The mixer was
then started and components 6 to 13 were added through
15 the addition port, allowing about ~; to 5 minutes between
addltions for thorough mixing. Aft;er addition of the
first five components, the dissolver (a rotating disk
with a saw tooth type configuration) was started, and
allowed to run throughout the mixing procedure. The
20 colloid mill (two rotating conical disks) was started
after all components had been added, and allowed to
run ~or one hour.
The product obtained was apourable paste hav-
ing a weight ratio of liquid to solid of 0.61 to lwhich
25 exhibited shear-thinning characteristics. It was dilu
ted with water in a ratio of 11.75 grams of water to
one gram of paste, and dissolved readily to produce a
working color developing solution.
The paste described above was analyzed by a
30technique involving high speed centrifugation to separ-
ate the continuous liquid phase and the discontinuous
solid phase, ~ollowed by analysis of the separated
phases. The continuous liquid phase was analyzed by
ultraviolet spectroscopy~ gas chromatography, Karl
-3~-
Fischer titration and total alkalinity titrimetry. The
discontinuous solid phase wac analyzed by ultraviolet
spectroscopy, gas chromatography, Karl Fischer titration,
total alkalinity titrimetry, and gravimetric sulfate
5 analysis, It was found that about 85~ of the triethanol-
amine, about 95~ of the benzyl alcohol, and about 90% of
the 4-(N-ethyl-N-2-methanesulfonylaminoethyl)-2-methyl-
phenylenediamine sesquisulfate monohydrate were present
in the continuous liquid phase. Potassiurn carbonate was
10 found to be the major constituent of the discontinuous
solid phase, with greater t~an 95% of the total potass-
ium carbonate being found in this phase. Water,
including water that was formed in situg constituted
about 4~ of the paste by weighk. Particle sizes of
15 solid materials in the paste were in the range from
about 0.5 to about 3 microns.
Example 5
A photographic processing concentrate intended
to be diluted with water to form a black-and-white de-
20 veloping solution was prepared with the use of a mortarand pestle from the following ingredients:
~ Weight (gramS 2
1. Potassium sulfite, anhydrous220.3
20 Sodium bicarbonate 22.4
25 3. Boric acid 3.0
4. Ethylenediaminetetraacetic acid 5.4
5. 5-Methylbenzotriazole 0.2
6. 1-Phenyl-3-pyrazolidone 4.5
7. Hydroquinone 89.7
30 8~ Potassium hydroxide
(45% aqueous solution)138.4
9. Water 25.0
Component 1 was ground for four minutes and
set aside. Components 6 and 7 were each ground for
-~5-
three minutes and were also set aside. Components 1 to
7 were then combined in the mortar and ground ~or two
minutes. Component 8 was added slowly with mixing.
Component 9 was then added slowly with mixing. The com-
5 position was mixed for three minutes after the finaladdition~
Within five hours, the material had set to a
stiff paste. No separation, caking, or crystallization
was evident even after two days. Rheograms of both
freshly-prepared and two-hour old composition had dis-
tinct thixotropic loopsO
Example_6
A photographic processing concentrate intended
to be diluted with water to form a color developing solu-
tion was prepared with the use of a mortar and pestlefrom the following ingredients:
Compone Weight (~rams
1. Triethanolamine 94.4
2. Benzyl alcohol 93.6
20 3 Potassium hydroxide, anhydrous25.6
4. l-Hydroxyethylidene-191-diphosphonic
acid (60% by weight aqueous
solution) 8.1
5. Sulronated fatty acid surfactant0.2
25 6. Potassium bromide o.g8
7. Potassium sulfite 3.5
8. Amino-substituted stilbene brightening
agent 2100
-36-
Component Weight (~rams~
9. Lithium sul~ate 19~6
lOo Hydroxylamine sulfate 44.1
11. 4-(N-ethyl-N-2-methanesulfonyl-
aminoethyl)-2~methylphenylene-
diamine sesquisulfate monohydrate 47.6
12. Potassium carbonate 175.0
Components 3~ 10, 11, and 12 were ground separ-
ately and set aside. Components 1 to 5 were added to
the mortar in numerical order with mixing~ Components
6 to 9 were combined together and then added slowly with
mixing. Then components 10, 11, and 12 were slowly
added in order with mixing. When all additions were com-
plete~ the composition was mixed for ~ive minutes. The
total time of mixing was about thi;rty-three minutes.
Within twenty-nine hours, the material had set to
a stiff paste. A~ter several days, there were no signs
o~ separation, crystallization~ or caking. Rheograms
for freshly-prepared and four-hour old samples had sig-
nificant thixotropic loops.
Example_7
A photographic processing concentrate intendedto be diluted with water to form a fixing solution was
prepared with the use of a mortar and pestle from the
following ingredients:
Component Weigh
1. Ammonium thiosul~ate (80~ aqueous
solution) 423,7
2~ Sodium thiosulfate 9o.o
30 3. Sodium sulfite 16.2
-~7-
Component ~Jei~ht (grams
4. Sodium metabisulfite 19.0
5. Sodium acetate 45.0
6. Acetic acid 22.8
5 7. Sodium glyconate 8.1
8. Aluminum sulfate 57.8
Gomponents 2 and 5 were ground separately and
set aside. All components were added together, slowly,
in order, and with mixing. When all additions were com-
plete, the composition was mixed for two more minutes.
Within two and one-half hours, the composition
had set to a smooth, stiff paste. No signs of separa-
tion, caking, or crystallization were apparent even
after four days. Rheograms of fresh and two-hour old
sampleshad thixotropic loops. The rheogram of the two-
hour old sample had a very distinct loopO
For purposes of comparison with the above
examples, a paste-like photographic processing concen-
trate was made according to the formula and procedure
of British patent No. 4689 -- A. D. 1894. The concen-
trate was prepared in a mortar and pestle from the
following ingredients:
1. ~ydroquinone 168 grams
2. Potassium metabisulfite168 grams
25 3. Potassium bromide 84 grams
4. Water 108 grams
Component 1 was ground in the mortar for eight
m~nute.s. Components 2 and 3 were ground together for
five minutes and then were comblned with component 1
30 and ground for five more minutes. Component 4 was
added slowly with mixing; and when all additions were
~ ~6
-~8-
complete, the composition was mixed for three minutes.
Within one day of preparation~ the material
had separated into a fluid upper layer and a dense
sediment and was not useful for preparation of a working
photographic processing solution
For purposes of further comparison with the
above examplesg a paste-like photographic proc~ssing
concentrate was made according to the formula and pro-
cedure of Æxample 5 of U. S~ patent 2,735,774. The
concentrate was prepared in a mortar and pestle from
the following ingredients:
1. Sodiu~ acetate 30 grams
2. Boric acid 15 grams
3. Sodium citrate 3 grams
15 4. Ammonium alum 10 grams
5O Sodium bisulfite 10 grams
6. Ammonium thiosulfate (76% aqueous
solution) 100 milliliters
7. Sodium thiosulfate, anhydrous150 grams
Components 1 to 5 were ground together in the
mortar for five minutes. Component 6 was added slowly
with mixing. Component 7 was ground separately before
adding it to the mixture. When all additions were com-
plete, the composition was mixed for five minutes.
Within 30 minutes, this compositlon had notice-
ably stratified, leaving a dense sediment at the bottom
of the jar. After three and one-half days, a clear
liquid layer had formed at the top of the sample. In
addition, rheograms for both freshly prepared and two
hour old composition showed no evidence of thixotropy.
The paste-like concentrates of this invention
provide many important advantages in the photographîc
art. For example, they result in a major reduction in
the costs for transport and storage of packaged chemicals,
as compared to liquid concentrates. This is because of
the much lower content of water that is required as com-
pared to liquid concentrates, which results in much less
---" 9 ~68~3
bulk and weight~ and thus much lower costs. Many pro-
cessing chemicals are not surficiently soluble in water
to ~orm highly concentrated solutions, so liquid concen-
trates often require a substantial water content. With
5 the paste-like concentrates of this invention3 a given
quantity of processing solution can often be made from
a package which has half or less than half of the weight
and volume of a corresponding package of liquid
concentrate.
A further advantage of paste concentrates, as
compared to liquid concentrates, is that they tend to be
more chemically stable and to require less separation of
ingredients and, accordingly~ fewer separate parts in
the total package~ Keeping properties are generally
15 significantly better with pa.stes because o~ such fea-
tures as reduced susceptibility to oxidation, reduced
susceptibility to deterioration caused by temperature
changes, and reduced tendency for crystalllzation to
occur.
Formation of working solutions ~rom the paste
concentrates o~ this invention is relatively simple, as
ccmpared to the difficult and time~consuming dissolution
procedures required with dry powder formulations. More-
over, the paste concentrates are c~enable to use with
25 processing compositions in wh~ch some of the necessary
ingredients are normally liquid, and some are normally
solid,-whereas dry powder formulations are useful only
with compositions in which all necessary ingredients
are normally solid. Paste formulations also e~ectively
30 avoid the problems of caking and dusting that plague the
use of dry powder formulations.
As will be evident from the disclosure and
examples herein, the paste-like photographic processing
concentrates of this invention combine many of the
35 advantages of liquid concentrates with many of the ad-
vantages of dry powder formulations to solve longstand-
ing problems in the art of packaging photographic
processing agents. They dissolve easily and speedily
to form working processing solutions3 for example
~o~
replenisher solutions, and can be adapted for use in
systems in which replenisher solution is held in a
storage tank or for direct use in continuous replenish-
ment of processing machines.
The invention has been described in detail
with particular reference to preferred embodiments there-
of, but it will be understood that variations and modi-
fications can be effected within the spirit and scope
of the invention.
