Note: Descriptions are shown in the official language in which they were submitted.
~51~33~
This invention relates to a process ~or preparing
metal salts over comparatively shor~ periods o~ time and,
more particularly, to a process for preparing photosensitive
silver salts. ~he photosensitive silver salts are
preferably produced in the presence o~ a binder in such
a way that a silver salt emulsion is formed. The
invention also relates to photographic materials and to
a process for the production of photographic images.
It is already known that photosensitive silver
halide emulsions can be formed by precipi-tating -the
appropriate silver salts in a binder. In particular, it
is known that silver halide emulsions can be formed by
precipitating silver halide in a binder, preferably
gelatin. The silver halide may be precipit~ted by
adding an aqueous solution o~ a silver salt to a halide
solution in gelatin. The size of the silver h~lide grains
obtained is controlled inter alia by the temperature of
the solution, the addition time and the e~cess o~ halide
Conversely, it is also known that an aqueous solution of
a halide can be added to an aqueous solution of a silver
salt.
It is also known that aqueous solutions of a silver
salt and a halide can be simultaneously introduced into
a receiving medium by the so-called double jet process.
Suitable processes of this type are-described, for
example,in British Patent No. 1,027,146 and in the
article by E. Moisar and S.Wagner in "Berichte der
Bunsengesellschaft fur physikalishce Chemie", 67 (1963),
pages 356 to 359.
In addition to the possibilities mentioned above of
varying the input rate, the grain size and grain
distribution of the silver halide grains of th0 emulsion
obtained are determined above all by so called Ostwa]d
ripening. Ostwald ripening is understood to be the
~5 dissolution of more soluble silver halide grains and
A-G 16~0
~i~
'~
33~
their subsequent precipitation on less soluble silver
halide grains under the e~feqt of silver halide solvents.
In other known processes for the productio~ of silver
halide emulsions, emulsions differing in grain size
are mixed, dissolved and allowed to crystallise in the
presence of silver halide solvents. In processes such
as these, the silver halide crystals used for
dissolution and crystallisation have to show different
solubilityO Processes of this type are known for
example from US Patents No. 2,146,938; 3,206,313 and
3,317,322; from German Auslegeschrift No. 1,~07,791 and
from the article by D. Markoc~i and W, Romer in
"Korpuluskar Photographie", IV (1963), pages 11~9 et seq.
However, the known processes -for producing photo-
sensitive silver salts, particularly silver halides, are
attended by several disadvantages. In the precipitation
of silver halides for e~ample 9 the number of silver
halide nuclei ~or~ed at the beginning of precipi-tation
is greater than the number of silver halide crystals which
it is intended to produce with a predetermined quantity
of starting materials. In general, excessively small
and, hence, e~cessively insensitive silYer halide
crystals would be obtained if, for a predetermined
quantity of starting materials, all of the silver halid~
nuclei formed were to be allowed to continue to grow.
rrhere are indeed various known processes by which the
number of silver halide nuclei initially formed during
precipitation can be subsequently reduced, cf. for
example German Offenlegungsschrift No. 2,107,118 and
British Patent No. 1,170,648, according to which a
silver halide emulsion is precipitated, a small portion
of the precipitate thus formed is separated off and
dispersed in a gelatin solution and more silver halide
is subsequently allowed to grow on this portion by dual
addition until the crystals have the required size.
A-~ 1630
339
-- 4 --
One disadvantage common to the known processes liss in
the fact that more silver halide nuclei (per mole of
silver) than required are initially formed so that spscial
measures have subsequently to be taken to reduce the
number of silver halide nuclei to the necessary extentO
In addition, the known processes for forming photosensi~
tive silver salts are relatively time-consumingO According--
ly, various processes have already been proposed with a
view to reducing the precipitation time by gradually in-
creasing the rate of added solution, cfo for exampleGerman Offenlegungsschrift NosO 1 804 2~9 and 2 107 1180
However, these known processes are attended by the dis-
advantage that the rate of added solu-tion can only be
controlled with considerable difficulty or by means of an
15 elaborate control mechanism, cfo for e~ample US Patent .
No~ 3 821 0020
It is also known that many difficulties arise in the
production of silver halide grains having a narrow grain
size distribution, iOeO substantially the same mean grain
size9 Thus there is the danger that the silver halide
grains initially precipitated agglomerate or that fresh
nuclei will be formed.
Accordingly, one of the objects of the present in-
vention is to provide an improved process for the pro-
duction of metal salts, particularly photosensi-tive silver
salts and specifically silver halides, which avoids the
disadvantages of known processesO More particularly, the
object of the invention is to provide a process in which
short precipitation timss may be maintained9 in which it
is possible to work in concentrated solutions, in which
there is little, if any, formation of fresh nuclsi and in
which, where silver halide solvents are used, the demand
for them is minimalO
~n improved process for forming metal salts which ars
sparingly soluble~ especially in water, particularly
for forming photosensitive silver salts and, specifically,
A-G 1630
1~35
-- 5 --
silver halides has now been ~ound, in which at least one
solution A containing at least one cation of the metal
salt is mixed in a reaction vessel (RG) with at least one
solution B containing at least one anion of the metal
5 salt by running at least one of these solutions into the
reaction vessel using solutions A and Bo In one embodi-
ment of the invention, A and/or B are aqueous solutionsO
According -to the invention, this addition is made
throughout the entire precipitation process or for at
10 least part of the process ~o that the concentration of
the ion to be precipitated, in the inflowing solution,
continuously changesO In a preferred embodiment I the
solution contained in supply vessel VB1, which is a
solution, in a concentration c1 of at least one of the
15 cations or anions to be precipitated, flows from supply
vessel VB1 to another supply vessel VB2o VB2 contains
a solution of the ion flowing in, in a concentration C1,
from VB1, but in an initial concentration c20 It is onl~
from VB2, that the solution flows into the reaction vessel
20 RGo The concentration c1 is different from the con-
centration c20 Either c1 or c2 may assume the value zero.
The initial concentration is the concentration before
the beginning o~ the trans~er from VB1 to VB2o
This method of introduction from a first supply vessel
25 into a second supply vessel and - optionally through
furhter stages - into the reaction vessel is re~erred to
hereinafter as cascadingO
In one embodiment of the invention, on of the solutions
(A or B) is introduced through this cascade~ whilst the
~o other solution is added (cfo Figure 1) or initially intro-
duced in known manr~er, iOeO without cascading, through
the inlst Z0 In another embodiment, both solutions (A and
B) are each added through a cascade (cfo Figure 2)o
In another embodiment II, solutions contained in at
35 least two supply vessels~ which solutions are solutions of
dilfering concentrations cl1 and c12, of either the anions
(solution B) or of the cations (solution A~ of ~he salt to
A~G 1630
83
-- 6 --
be precipitated, flow, for at least a certain length of
time, at flow rates v'1 and v'2, into a regulating de-
vice R, in which the ratio o~ v'1 to v'2 is con-tinuously
varied, and they then flow out o~ this regulating device,
optionally via additional mixers or metering devices, with
a total rate flow of v'g, the concentration c' o~ which
continuously changes into the reaction vessel in which the
precipitation o~ the sparingly soluble salt takes place
by reaction with the other solution (A or B)o The con-
centration c'1 is di~ferent from the concentration c'2;either c'1 or c'2 may assume the value zeroO The "flow
rate" is the quantity o~ the solution flowing per unit
timeO
In such an embodiment the addition of the one solution
(A or B) takes place in this manner, whereas the vther
solution (B or A) is added via a customary inlet Z or is
initially placed in the reaction vesselO It is, however,
possible for both solutions to be added separately from
each other in this mannerO
~mbodiment II is illustrated by means of Figure 5
~ithout any limitation being implied by this:
In the vessels VB'1 and VB'2 of Figure 5 solutions of
differing concentrations are present. The outlet pipes
unit in a regulating device R, which allows continuous
increasing or decreasing, linear or exponential mixing,
by means of the si~plest control melchanisms~ A metering
device can be situated beneath the regulati~g deviceO
To allow improved mixing of the solutions static mixers
can be incorporated prior to or following the metering
deviceO If one wishes9 ~or example to provide a li~ear
increase in the concentration of the solution intro-
duced, the solution introduced will ~irst o~ all consist
entirel~ of the solution in vessel VB'1 having the low
cor,centration~ The regulating device ensures that an
ever-increasing amount of the concentrated solution VB'2
A-G 1630
839
-- 7 --
~lows in so that the material input is increased without
considerably changing the amount of liquid flowing in per
unit timeO A change in the flow rate, constituting an
additional parameter for the control of the reaction, can
be achieved in a relatively simple mannerO If, by intro-
ducing two reactants, a sparingly soluble salt is to be
precipitated, this device can be applied both ~or the
anions and for the cation side, it being appropriate to
regulate the two mixing taps synchronously by means of a
control elementO
In a particularly preferred embod,ment of the in~ention
the concentration of the inflowing solution increases
continuously for a-t least part o~ the processO In
particular this is effected in that first of all nuclei
of the salt to be precipitated are produced according to
a known method by mixing corresponding starting solutions
and following the nuclei formation - in the growth phase -
the concentration of the inflowing solution is increasedO
This method allows the diffusion paths o~ the precipitation
components to the already existing grain to remain as
constant as possible; therefore formation of fresh
nuclei scarcely takes place and the in~lowing precipitation
component is essentially used for the crystal growth.
Towards the end of the gr~wth phase, on the other hand,
it may be appropriate to continuously decrease the
concentration. In a preferred embodiment o~ the invention
the metal salt to be formed is a silver halide~ solution A
is an aqueous solution of a silver salt which is more
soluble in water than the salt to be formed and solution B
is a solution of a halide which is readily soluble in
water~
The present invention also relates to photographic
materials comprising a support layer and, applied thereto,
at least one photosensitive silver halide emulsion layar
3~ containing a salt produced in accordance with the invention
and, optionally, ~urther layers~
A-G 1 630
' ~ ,;
~5~339
In addition, materials such as these are suitable
~or the production o~ photographic images by image-
wise e~posure and developmentO
In one preferred embodiment of the invention
caqc~ding is carried out by arranging two supply vesselsone above the other ~o that the content of the upRer
supply vessel flows ~t a substa~tially constant rate into
the lower suppl~ vessel whilst the conte~t of the lower
supply vessel simultaneously runs into the reacti.on
vessel at a substantially constant rate.
According to the invention, therefore it is readily
possible both according to embodiment I (cascade) as well
as according to embodiment II to produce single salts
which only contain cations of one type (for example Ag+)
and anions of one type (~or example Br')0 I~ according to
embodiment I the concentration c1 of the solution in the
supply vessel VB1 is higher than the concentration c2 o~
the solution in the vessel V~2, a constant addition rate
is obtained for an increasing input o~ materialO I~ the
~0 ratio o~ the two concentrations to one another is re-
versed, the input of material is steadily reduced as a
function of time 9 although a substantially constant
addition rate is again obtainedO ~ither the concentration
C1 or the concentration c2 may assume the value zeroO
In cases such as these, there~ore, the particular ion
to be precipitated is not contained either in VB1 or VB2,
although the solvent, for example water, is present
therein~
The metal salts produced in accordance ~ith the
invention may be, however, not only single salts, but
also double salts or mixtures of single saltsO For ex-
ample~ it is possible to produce silver halides con-
taining not only a single halide, ~or example chloride
or bromide, but also several halides, in which case the
halides may also contain silver iodide9 par~icularly in
proportions o~ up to 10 mole percent~
A-G 1630
1339
According to the invention9 it is also possible to
produce emulsions havi~g a layered grain structure.
Emulsions of this type are described for example in
US Patents Nos. 3,206,31> and 3,317,322, in German
Offenlegungsschrif-t No. 2,224,837, in German Auslegeschrift
No. 1,169,290 and in German Offenlegungsschrift No.
2,~08,239.
In addition, it is possible to produce converted
emulsions, for e~ample of the type described in US Patent
No. 2,592,250
According to the invention, halide miYtures may be
produced for example by using not only one, but at least
two halides (optionally accommodated in different supply
vessels) in the halide suppl~ vessels.
Instead of silver halides, it is of course
also possible to precipitate silver pseudo halides, ~par-
ticularly silver thiocyanate.
For producing silver halide mi~tures, it is possible
for egample to use a cascade comprising the supply
vessels VBl and VB2 for adding the halide. In this case,
all of the halides to be precipitated may be
accommodated in all of the supply vessels, with the proviso
that the concentration of at least one halide in the
supply vessels assumes a different value.
In another embodiment, however, it is also possible
for example for one halide (hereinafter referred to as
Xl) to be present in VBl only and, before the beginning
of the transfer from YBl to VB2, for at least one other
halide (h~reinafter referred to as X23 to be present
in VB2 onlyO
In this case, X~ and X2 are present in a concentration
of O in VB2 and VBl, respectively, before the beginning
of the -transfer from VBl to VB2.
In either case, at least one of the cations or anions
~5 to be precipitated may of course be additionally
introduced beforehand into the reaction vessel.
A-G 1630
~5~39
~ 10 -
I~ this way, it is possi~le very simply and without
any need ~or a complicated control mechanism to ensure
that the volume ~lowing in per unit o~ -time remains the
same and, a~ the sa~e time, to in~luenca the quantity
a~d/or type of anions or cations to be precipit~ted,
which is ad~ed by varying the concentration.
Regulation Gf the i~put o~ material in this way is
extremely desirable for the pr~duction o~ certain emulsions.
A procedure such as this is particularly suitable for
10 monodisperse emulsions. Since the silver halide to be
precipitated is intendad to grow on an equal number of
nuclei , the input of material is also continuously
increased in a pre~erred embodiment of the invention
because th~ surface of the cr~stals also increas~s.
The increase in the input of material is obtained in the
cascade inflow by the fact that the concentration c1 is
greater than the concentration c2O
The process according to the invention is dis-
tinguished by the fact that it may readily be auto-
mated because the flow rate can be kept the same whilstthe input of material may be varied within wide limits.
If desired, however, the flow rate may also be varied
by means of suitable devicesO No di~ficulties are in-
volved in maintaining even extreme precipitation con-
ditions in regard to temperature, pH-value and pAgo
It is surprisingly possible by virtue of the process
according to the invention to shorten considerably the
precipitation times and to use more concentrated batches
than in conventional processesO In addition, the formation
of fresh nuclei can be suppressed and an increased yield
of silver obtainedO The addition of a solution via the
inlet Z can be controlled according to a known method 7
for example as a func-tion of the pAg valueO
A-G 1~30
,
339
Accordingly, it is in principle possible to
precipitate metal salts o~ virtually any type by the
process according to the invention. Thus,in addition
to the metal saltswhi~h have already been mentioned,
other metal salts which may be precipitated by the
process according to the invention include barium sulphate,
bismuth sulphate, calcium carbonate, calcium sulphate,
lead carbonate, lead iodide and lead sulphate.
It is possible by the process according to the
invention to precipitate both metal salts having a narrow
grain size distribution and also metal salts having a
relatively wide grain distribution. In particular, it is
possible by the process according to the invention to
produc0 both homodisperse and also heterodisperse
silver halide emulsions.
Homodisperse emulsions are emulsions having a narrow
grain size distribution, e.~. emulsions where at least
95~ of the silver halide grains have a diame-ter which
deviates by no more than 40 % and praferably by no more
than 30 ~0 from the mean grain diameter. The silver halide
grains may have any of the known forms, for example
cubio, octahedral or even a mixed tetrahedral/decahedral
form.
Heterodisperse emulsions are, in particular,
emulsions where at least lO % and preferably at least
20 % of the silver halide grains have a diameter which
deviates by at least 40 ~0 from the mean grain diameter.
The silver halide grains of emulsions such as these
generally have an irregular ~orm.
The absolute value of the mean grain size of the
metal salts produced in accorda~ce with the invention,
particularly the silver halide emulsions produced in
accordance with t~ invention, may vary within wide limits.
For example, it is possible to produce boGh fine-grained
;5 silver halide emulsions having a mean diameter of less
A-G 1630
839
12 -
than 0.5 ~, preferably less than 0.3 ~, and also coarse-
gr~ined emulsions having mean grain diameter of ~rom
0.5 to 4 ~.
In cases where it is intended to produce photo-
scnsitive silver salt emulsions, for example silver halide
emulsions, suitable protective colloids and binders
are the usual hydrophilic film-~orming substances,
for example proteins, particularly gelatin, alginic
acid or derivatives thereof, such as esters, amides
or salts, cellulose derivatives, such as carbo~ymethyl
cellulose and cellulose sulphates, starch or starch
derivatives or hydrophilic synthetic binders, such as
polyvinyl alcohol, partially hydrolysed polyvinyl acetate
and polyvinyl pyrrolidone. The layers may also contain,
in admi~ture with the hydrophilic binders, other synthetic
binders in dissolved or dispersed form, such as homopolymers
or copolymers of acrylic or methacrylic acid or derivatives
thereof, such as esters, amides or nitriles, and vinyl
polymers such as vinyl esters of vinyl ethers.
According to the invention, it is in principle
possible to produce emulsions for a variety of di~ferent
photographic materials such as, for e~ample, negativa
emulsions of high surface sensitivity, negative emulsions
of high internal sensitivity, direct-positive emulsions
having fogged or unfogged surfaces, print-out emulsions,
reversal emulsions, emulsions for black-and-white materials
and for colour materials~ emulsions having a defined grain
distribution and halide topography, particularly emulsions
having a defined halide and, above all, iodide gradient.
The silver halide emulsions produced in accordance
with the invention may consist of pure silver halides
and also of mi~tures of different silver halides. For
example, the silver halide grains of the emulsions
may consist of silver chloride, silver bromide, silver
iodide, silver chloride bromide, silver chloride iodide,
A-G 1630
~5~33
-- ~3 --
silYer bromide iodide and silver chloride bromide iodide.
To remove th0 water-soluble salts, the silver
halide emulsions produced in accordance with the invention
may be , noodled and rinsed in known or may e~en
be coagulated with a coagulant and subsequently washed~
as known for example from German Offenlegungsschrift
No. 2,61~,862.
Silver halide emulsions produced in accordance
with the invention are also suitable for the silver dye
bleaching process and, in particular, for the so-called
instant-picture colour process or dye transfer process.
In these processes, the dyes for the component colour
images diffuse into an image receiving layer where they
are firmly anchored or the colour couplers dif~use into
the image receiving layer where they are reacted to
form the image dye after colour development in the usual
way. In this case, the photosensitive material generally
contains t~ree photosensitive emulsion layers with each
of which a dye-producing system is associated. In this
conte~t, a dye-producing system is understood to be a dye
or dye precursor which is incorporated in non-~iffusing
form in the particular layer and which, on development
in the presence of the alkaline processing fluid, splits
off diffuisng dyes preferably containing acid groups
under the action of oxida-tion products of photographic
developers which are formed in image-wise distribution.
A variety of chemical compounds is available for this
purpose. The non-diffusing dye-producing compounds
according to US Patent No, 3,628,952 ~or example are
particularly suitable. Compounds of this type release
diffusible dyes on reaction with oxidation products of
black-and-white or ~olour developers~ Anot~er suitable
elass of compounds is described in ~erman Patent No
1,095,115. On reaction with oxidised colour developer,
the compounds mentioned in this German Patent give
A-G 1630
39
_ ~L, _
dif~usible dyes which generally belong to the cl~ss of
azomethine dyes. Another suitable dye-producing system
is described in US Pate~ts Nos. 3,443,g39 and 3,443,940~
In this system, diffusible dyes are released through ring
5 closure under the influence of oxidised developer substances.
Dye transfer processes and associated couplers which
may be meployed in accordance with the present invention
are also described in US Patents Nos. 2,9~3,606; 3,087,
817; 3,185,567; 3,227,550; 3,227,551, 3,227,552, ~,227,55~;
3s253f9l5; 3,415,644; 3,415,645 and 3,415,646,
The photosensitive materials which may be used for
instant-picture colour processes such as these generally
have the following structure:
A blue-sensl~ive silver halide emulsion layer;
15 a layer containing a system releasing a yellow dye;
a separating layer;
a green-sensitive silver halide emulsion layer;
a layer containing a system yielding a magenta dye;
a separating layer;
20 a red-sensi-tised silver halide emulsion layer;
a layer containing a system releasing a cyan dye.
Suitable apparatus for carrying out the process
according to the invention are illustrated diagrammatically
in Figures l and 2 of the accompanying drawings. In these
25 Figures, VBl is the ~irst supply vessel7 VB2 the second
supply vessel and RG the reaction vessel. As can be seen
from the drawings~ VBl is con~ected to VB2 by a ~eed pipe
and VB2 is connected to RG by another feed pipe.
Suitable stirrers may be provi~e~ in the supply vessels
and in the reaction vessel.
The apparatus illustrated -diagra~matically in Figure
l is used when only one of the solutions A or B is
introduced into the reaction vessel by cascading, whilst
the other solution is introduced th~ough the inlet ~
The apparatus illustrated in Figure 2 is used when both
A-G 1630
~5:~B39
- 15 -
solution A and solution B are introduced using the cas-
cading principleO Further supply vessels may o~ course
be connected as requiredO Accordingly this also) of course,
applies to a device according to embodiment II, in par-
ticular according to Figure 50
According to the invention, silver halides may be
precipitated in the reaction vessel in the presence of
suitable silver halide solvents. Examples of suitable
silver halide solvents are halides, pre~erably alkali
10 metal and ammonium halides, particularly bromides and
chlorides; ammonia, thiocyanates,. particularly alkali
metal or ammonium thiocyanate; sulphites, particularly
alkali metal and ammonium sulphites; thiosulphate; organic
amines; thioethers and imidazole derivatives. In one
15 preferred embodiment., it is possible to use organic
thioethers of the type described for example in US
Patents Nos. 3,271,157; 3,507,657; 3,531,289 and
3,574,628. The silver halide solvents may be introduced
into the reaction vessel through the supply vessels or
20 may be present in the reaction vessel from the outset,
~ ilver halide emulsions produced in accordance with
the invention may be further processed in known manner.
Silver halide emulsions produced in accordance with the
invention may be chemically sensitised, for example by
25 the addition during chemical ripening o~ sulphur
containing compounds, for example allyl isothiocyanate,
allyl thiourea and sodium thiosulphate
Other suitable chemical sensitisers are reducing
agents, for example the tin compounds described in
30 Belgian Patents Nos. 493,464 and 568,687, also polyamines,
such as diethylene triamine, or aminomethyl sulphinic
acid derivatives, for e~ample corresponding to Belgian
Patent No. 547,323.
Other suitable chemical sensitisers are noble metals
~5 and noble metal compounds, such as gold~ platinu~,
palladium, iridium, ruthenium or rhodium. This method of
chemical sensitisation is described in the article by
A-G 16~0
~53l839
-- 16 _
R. Koslowsky, in Z. Wi9s, Phot. 46, 65 72 (1951)-
The emulsions may also be sensitised with poly~
alkylene oxide derivatives, Eor example with polyethylene
oxide having a molecular weight oE from 1000 to 20,000,
and also with condensation products of al~ylene oxides
and aliphatic alcohols, glycols, cyclic dehydration
products of hexitols with alkyl-substituted phenols,
aliphatic carboxylic acids, aliphatic amines, aliphatic
diamines and amides. The condensation products have
a molecular weight oE at least 700 and preferably oE more
than 1000. To obtain special eEEectsg these sensitisers
may of course be used in combination with one another,
as described in Belgian Patent No. 537,278 and in
British Patent No. 727,982.
The emulsions may also be optically sensitised, for
example with the usual polymethine dyes, such as neutro-
cyanines, basic or acid carbocyanines, rhodacyanines,
hemicyanines, styryl dyes and oxonols. Sensitisers
of this type are described for example in F~Mo Hamer~s
book entitled "The Cyanine Dyes and Related Compounds",
1964, Interscience Publishers, John Wiley and Svns.
The emulsions may contain the usual stabilisers such
as, for e~ample, homeopolar or salt-like compounds o~
mercury with aromatic or heterocyclic rings, such as
mercapto triazoles, single mercury salts, sulphonium-
mercury double salts and other mercury compounds. Other
suitable stabilisers are azaindenes, preferably tetra~
or penta azaindenes, particularly those substituted by
hydroxyl or amino groups. Compo~nds such as these
are described in the article by Birr in ~. Wiss. Phot. 4?
(1952), 2 - 58. Other suitable stabilisers include,
inter alia, heterocyclic mercapto compounds, Eor example
phenyl mercaptotetrazole, quaternary benzthiaz~le
derviatives and benzotriazole~
The emulsions may be hardened in the usual way, Eor
A-G 1630
~ Sl B39
- 17 ~
example with ~ormaldehyde or halogen-substituted aldehydes
containing a oarbo~yl group, such as mucobromic acid,
diketones, methane sulphonic acid esters and dialdehydes.
In addition, the photographic layers may be hardened with
epoxy, heterocyclic ethylene imine or acryloyl hardeners.
E~amples of hardeners such as these may be ~ound for
example in German O~fenlegungsschrift No. 2,2639602 or
in British Patent No, 1,266,655. The layers may also
be hardened by the process according to German
10 Offenlegungsschrift No. 2,218,009, gi~ing colour
photographic materials which are suitable for processing
at high temperat~res.
The photographic layers or the colour photographic
multi-layer materials may als~o be hardened with diazine,
triazine or 1,2-dihydroquinoline hardeners, as described
in British Patents Nos. 1,193,290; 1,251,091; 1,306,544
and 1,266,655; French Patent No. 7,102,716 and German
Offenlegungsschrift No. 2,332,317. Examples o~ hardeners
such as these are diazine deriuatives containing alkyl
or aryl sulphonyl groups, derivatives o-~ hydrogenated
diazines or triazines such as, for example, 1,3,5~hexa-
hydrotriazine, ~luorine-subs-tituted diazine derviatives
such as, for example, fluoropyrimidine, esters o~ di-
substituted 1,2-dihydroquinoline or 1,2-dihydroisoquin-
oline-N-carboxylic acids. Other suitable hardeners are
vinyl sulphonic acid hardeners, carbodiimide or carbamoyl
hardeners of the type described, ~or example in German
Offenlegungsschrif-ts Nos. 2,263,602; 2,225,230 and 1,8089685;
Fre~ch Patent No. 1,491,807; German Patent No. 872,153
and East German Patent No. 7218. Other suitable hardeners
are described, for e~ample, in British Patent No. 19268~550.
~ he present invention may be used both ~or the
production o~ black-and-white photographic images and also
~or the production of coloured photographic images.
Coloured photographic image3 may be produced for example
A-G 1630
339
- 18 -
according to the known principle of chromogenic developmen~
in the presence of colour couplexs which react with the
oxidation product of dye-producing p-phenylene diamine
developers to form dyes.
The colour couplers may for example be added to the
colour developer on the principle of the so-called
single development process~ In a preferred embodiment,
the photographic material itself contains the usual
colourcouplers which are ~enerally incorporated in the
silver halide layers. Thus J the red-sensitive layer may
contain for example a non-diffusing colour coupler for
producing the cyan component colour image, ~enerally a
coupler of the phenol or ~-naphthol ~ype. The green
sensitive layer may contain for example a~ least one non-
diffusing colour coupler for producing the magenta com-
ponent colour image, nQrmally a colour coupler of the
5pyrazolone or imidazolone type, The blue-sensitive
layer may contain for example a non-diffusing colour
coupler for producing the yellow component colour image,
2D generally a colour coupler containing an open-chain
ketomethylene group. Large numbe~ of colour couplers of
this type are known and are described in a numberof
patents. Reference is made here for example -to the
article entitled "Farbkuppler (Colour Couplers)" by W.
Pelz in "Mitteilungen aus den Forschungslaboratorien der
Agfa, Leverkusen/Munich", Vol. III (1961) and to
K. ~enkataraman~s work entitle "The Chemistry of Synthetic
Dyes", Vol. 4, 341 - 387, Academic Press, 1971.
Other suitable non-diffusing colour couplers are
2-equivalent couplers. 2-equivalent couplers contain a
releasa~le substituent in the coupling position so that,
in contrast to the usual 4~equivalent couplers 9 they
only require two equivalents of silver halide for dye
formation. Suitable 2~equivalent couplers include, for
example, the known DI~ couplers in which the releasable
A-G 1630
B39
- 19
radical is released as a diffusing ~evelopment inhibitor
a~ter reaction with colour developer o~idation products.
In addition, so-~alled white couplers may be used for
improving the properties of the photographic material.
The non-diffusing colour couplers and dye-producing
compounds are added to the photosensitive silver halide
emulsions or to other casting solutionsby the usual
methods. Where the compounds in question are soluble in
water or alkalis, they may be added to the emulsions
in the form of aqueous solutions, to which o~ water-
miscible organic solvents, such as ethonol, acetoneor dimethyl formamide may be added, Where the non-
diffusing colour couplers and dye-producing compounds
are insoluble in water and alkalis 9 they may be
emulsified in known manner, for e~ample by mi2ing a solution
f these compounds in a low-boiling organic solvent either
directly with the silver halide emulsion or first with an
aqueous gelatin solutionand subsequently removing the
organic solvent in the usual way. The resulting emulsion
of the particular compound in gelatin is subsequently
20 mi~ed with the silver halide emulsion. So-called coupler
sol~ents or oil formers may additionally be used for
incorporating hydrophobic compounds of the type in
question by emulsification. Coupler solvents or oil
formers are generally relatively high boiling organic
compounds which c~tain the non-diffusing colour couplers
and development-inhibitor releasing compound to ~e
emulsified in the silver halide emulsions in the form of
oily droplets. In this connection9 reference is made
for example to US Patents Nos. 2,322,027; 2,533,514;
3,~89,271; 3,764,336 and 3~765,897.
The emulsions produced in accordance with the
in~ention may be applied to the usual support layers, for
example supports of cellulose esters, such as cellulose
acetate or cellulose acetobutyrate, also polyesters,
particularly polyethylene terephthalate 7 or polycarbonates,
A-G 1630
~1839
-- 20 --
particularly polycarbonates based on bis-phenylol propane.
Other suitable supports are papers ~pports, which may
contain water-impermeable polyolefi~ layers ~or example
of polyethylene o~ polypropylene, and also
support o~ glass or metal.
For black-and-white development, it is possible to
use the known black-and-white developer compounds, such
as for e~ample hydroxy benzenes and ~-pyrazolido~es.
For producing dye images~ it is possible to use the usual
colour developer substances, for example N,N dimethyl-~-
phenylene diamine, 4-amino-3-methyl-N-ethyl-N-metho.Yy-
ethyl aniline, 2-amino-5-diethyl amino toluene, N-butyl-
N-~ -sulphobutyl-P~phenylene diamine, 2-amino-5-(N-ethyl-
N-~-methanesulphonamidoethylamino)- toluene, N-ethyl-
N-~-hydro~yl ethyl-P-phenylene diamine, N,N-bis-(~-
hydro~y ethyl)-p-phenylene diamine, 2-amino-5-(N-ethyl-
N-~-hydro~y ethyl amino)-toluene. Other colour
developers are described, for e~ample, in J. Amer. Chem.
Soc. 73, 3100 (1951).
In the production of silver halide emulsions
according to the cascade process the ~ater-soluble silver
salts are present in the supply vessel VB1 in a concen-
tration c1 of generally from 0~01 mole per litre to 16~8
moles per litre and,more particularly~from 001 mole per
litre to 7 moles per litreO The concentration in the
supply vessel VB2 is generally from 0001 mole per litre
to 16~8 moles per litre and,more particularly7from 001
mole per litre to 7 moles per litre~
In the production of silver halide emulsion accord-
3 ing to the cascade process the water-soluble halides are
present in the supply vessel VB1 in a concentration c
o~ generally from 0001 mole per litre to 7 moles per
litre and, more particularly, from 001 mole per litre
to 5 moles per litre, the concentration in the supply
A-G 1630
l839
- 21
vessel VB~ amounting generally to between 0001 mole per
litre and 7 moles ~er litre and, more particularly, to
between 001 mole per litre and 5 moles per litre.
Corresponding values are also preferred for the described
embodiment II~
The optimal addition rate is goYerned inter alia
by the batch volume, the required crystal habit, the
required mean grain diameter and the required grain size
distribution.
1 0 EXAMPIES
The following abbreviations with the meanings
indicated are used in the following Examples 1 9:
VBAl = first supply vessel for solution A
VBA2 = second supply vessel for solution A
VBBl = first supply vessel for solution B
VBB2 = second supply vessel -~or solution B
vAl = out-~lowing volume from VBAl (ml/min.)
vA2 = outflowing volume ~rom VBA2 (ml/min.)
vBl = outflowing volume from VBBl (ml/min.)
vB2 = outflowing volume from VBB2 (ml~/min.)
cAl = concentration of silver salt in VBAl (moles per litre 3
cA2 = initial concentration o~ silver salt in VBA2
(moles per litre)
cBl = concentration of halide in VBBl (moles per litre)5 cB2 = initial concentration o~ halide in VBB2
~moles per litre)
Z = inlet according to Figure l.
In the examples 1 - 9 the process is conducted
according to embodiment I (cascade)0
A-G 1630
- ~.5~839
-- 22 --
A silver bromide emulsion was prepar~d by the double
jet process, i.e. by simultaneously introducing
a water-soluble halide and a water-soluble silver salt
into the reaction vessel. The water-soluble sllver salt
was introduced by means of a cascade arrangement formed
by positioning VBAl and VBA2 one behind the other~ The
simultaneous addition of the halide solution was not
made by means of a cascade arrangement, but instead
10 through the inlet Z at pAg = 8 (cf. Figure 1)~ The
following st~rting values were adjusted;
VAl = 150 ml/min.
vA2 = 200 ml/min.
cAl = 0.2 mole o~ AgN03 per litre
cA2 = 0.04 mole of AgN03 per litre
The halide solution added had a concentration of
0.63 mole per litre. The precipitation process in
the reaction vessel was carried out in the following
steps:
20 1. With the transfer from VBAl to VBA2 interrrupted,
silver nitrate from VBA2 and the potassium bromide
solution were introduced simult~neously by the double
jet process into a gelatin solutionaccommodated in
the reaction vessel.
25 2. After 5 minutes, the transfer from VBAl to VBA2 was
started, whilst at the same time a stirrer in VBA2
provided for rapid and uniform mixingO
3. A~ter another 40 minutes, the transfer from VBAl to
VBA2 was interrupted. Silver nitrate from VBA2 and
30 the potassium bromide solutio~ were introduced for
25 minutes in-to the receiving solution.
The silver bromide crystals obtained were cubic
and had a mean edge length of 0.25 ~ with a deviation of
8.5 %. Accordingly, a monodisperse silver halide
35 emulsion was obtained.
A-G 1630
- 23 -
For comparison, silver bromide emulsions o~ the
same type were produced in accordance with German
Offenlegungsschrift No. 2,107,118 under otherwise the
same conditions, It, was ~ound that, in the known process,
considerably more time was required for the individual
phases of the precipitation process. In the known
process, about 100 to 120 minutes are required for the
seed forming phase, in which the silver halide crystals
grow to a ma~imum size of around 0.1 ,u, another 110 to
140 minutes being required for the remaining precipitation
phase up to an edge length of 0.25 ,u. By contrast, a
total of only 70 minutes was required in the process
according to the invention.
EXA~ LE ~
A pure silver iodide emulsion was precipitated by
the double jet process using an apparatus of the kind
shown in Figure 1. As in Example 1, the silver nitrate
was added through a cascade according to Figure 1, the
following values being maintained:
vAl = 20 ml/min.
vA~ = 35 ml/min.
cAl = 4.25 moles of AgN03 per litre
cA2 = 0.3 mole of AgN03 per litre
4000 ml of a gelatin solution containing 0.6 g/mole
of AgN03 of a thioether corresponding to the following
formula:
2H5 S--C 2H4--S--C 2H4~ C O--NH
were introduced initially into the reaction ves~el. The
iodide was added in the form of a 4-molar KI-solution
through the inlet Z. The iodide addition was controlled
through the silver potential EAg = -120 mV. Precipitation
was carried out in the following steps:
1, With the transfer from VB~l to VBA2 interrupted,
silver nitrate solution from VBA2 and the KI-solution
A-G 16~0
~LS~3~
- 24 -
were initially run i~to the reaction vessel for 6 minutes.
2. The transfer from VBAl to VBA~ was then started,
a stirrer in VBA2 provided ior rapid and unifor~ mi~ing.
3. After 40 minutes, the trans~er from VBAl to VBA2 was
interrupted again, after which the precipitation oi silver
iodide was continued ~or 34 minutes by the simultaneous
addition of KI and AgN03 from VBA2.
Silver iodide crystals having an edge length of
o.6 ~ were obtained. The emulsion obtained was a
monodisperse emulsion in which the mean deviation from
the mean grain diameter is 7.35 /0.
In this case, -too, the process according to the
invention saved a considerable amount of time in relation
to the process for producing silver halide emulsions
15 kno~ from German Offenlegungsschrift No. 2,107,118~
Whereas, according to the invention, precipitation took
a total o~ 80 minu-tes, a period of at least 170 minutes
was required for precipitation by the known processes.
EXAMPLE ~
This E~ample shows that the halide may also be
added through a cascade of the type shown in Figure 1,
In addition, the crystals precipitated in accordance with
this Example are characterised by an outwardly
decreasing silver iodide concentration gradient. To
25 this e~d, 7500 ml of a 0.002-molar NH~Br-solution,
7500 ml of a 0.14-molar NaCl soluti~n and 104 g of
the thioether described in E~ample 1 were initially
introauced into the reaction vessel~ Silver nitra-te was
introduced through the inlet Z in the form of a 0~5-
3o molar aqueous silver nitrate solution. The addition of
silver nitrate was controlled through the pAg value,
a pAg-value corresponding to a silver potential EAg
of -~0 to -40 mV being maintained.
The ~ollowing test conditions were ad~usted for the
cascading of the halide:
A-G 1630
839
- 25 -
vBl = 555 ml/min.
~B2 = 490 ml/min.
cBl = 1.04 mole of NH4Br per litre (no iodide in
VBBl)
cB2 = 0.18 mole of KI per litre (no bromide in
B2)
Precipitation was carried out in the following steps:
1. With the transfer from VBBl to VBB2 interrupted, the
KI solution was run into the reaction vessel ~rom
VBB2 together with the silver nitrate solution. This
addition lasted 3 minutes.
2. After 3 minutes, the trans-~er ~rom VBBl to YBB2 was
started, a stirrer in VBB2 providing ~or rapid mixi~g.
Precipitation was continued ~or 6 minute~ with this
arrangement.
3. Thereafter the trans~er from VBBl to VBB2 was
interrupted again and precipitation was continued
for another minute.
4. The emulsion was then digested for 20 minutes
at 70C.
5. Thereafter more silver bromide was precipitated for
20 minutes by the double jet process using a 0.5
molar AgN03 solution and a 0.5 molar bromide solu-tion, but
without a cascade.
A relatively ~niform emulsion con-taining rounded
crystals with a mean grain diameter of 0.4 ,u was
obtained.
EXAMPLE 4
A silver chloride emulsion was prepared in two
cascading steps by the double jet process as illustrated
in Figure 1. In each case, the cascade was set up for
the addi~ion of the silver nitrate solution. The halide
was added through the inlet Z. Before the begin~ing o~
precipitation, ~200 ml o~ a gelatin solution containing
o.6 g/mole of ~gN03 of the thioether defined in E~ample
5 were introduced into the reaction vess~l~ In the first
three process steps, the double jet addition was made with a
A-G 1630
39
0,74-molar NaCl solution and, in the ~ollowing process
steps, with a'l!l3-molar NaCl solution. For the first
three process steps, the cascade was set up on the
basis of the following val~es:
vAl = 38 ml/min.
VA2 = 67 mltmin.
cAl = 1,1 mole of AgN03 per litre
cA2 = 0.12 mole of AgN03 per litre
Precipitation was carried out in the following steps:
1 With the trans~er ~rom VBAl to VBA2 p
silver nitrate from VBA2 was initially run into the reaction
vessel from 2 minutes together with the sodium chloride
solution at a temperature oE 70C and at a pAg-va,lue of
80 mV.
2. Thereafter the transfer from VB~l to VBA2 was
started and precipitation was continued for 26 minutes wi-th
this arrangement.
3. The transfer from VBAl to VBA2 was then interrupted
and precipitation is continued ~or another 17 minutes
~y the addition of halide and of silver nitrate from
VBA2'
Precipitation was then continued with the following
solutions using a second cascade arrangement setup on
the basis of the following values:
vAl = 150 ml/min.
vA2 = 188 ml/min.
c~l = 1.46 mole o~ AgN03 per litre
cA2 ~ 0.29 mole o~ AgN03 per litre
The following process steps were carried out with
this cascade:
4 With the transfer from VBAl to VBA2 p
silver nitrate from YBA2 and the 1.13-molar sodiwm
chloride solution were introduced into the reaction vessel
for 2 minutes.
A~G 1630
339
- 27 -
5. The transfer from VBAl to VBA2 was then started and
more sil~er halide was precipita-ted for 30 minutes by
introduction Oe the mixture formed in VBA2 and the halide
solution into the reactinn vessel.
6. The transfer from VBAl to VBA2 was then interrupted
again and silver halide precipitated for another 8 minutes
by addition o-f the mixture accommodated in VBA2 and the
1.13-molar sodium chloride solution.
A cubic, monodisperse silver chloride emulsion
having a mean edge length of 2.2 ~ and a deviation from
the mean grain diameter of 7.3 /0 was obtained. Had the
process known ~rom German Offenlegungsschrift No. 2,107,
118 been used, a total time of around 145 minutes would
have been required for producing these sil~er chloride
crystals.
EXAMP~E 5
A silver bromide emulsion was prepared in the
presence of a thioether by the double Jet process
according to Figure 1. To this end, 6 g of the following
thioether were imtially introduced into the reaction
vessel:
C2H5-S-C2H4-S-C2~14_N~I ~ C2 4
Under pAg control, potassium bromide was introduced
in the form of a 2-molar KBr solutinn through the inlet
Z at a pAg-value of 9. The silver nitrate was added
through a cascade operating on the basis of the following
data:
vAl = 56 ml/min.
vA2 = 94 ml/min.
cAl = 2.26 moles of AgN03 per litre
cA2 = 0 63 mole of AgN03 per litre.
Precipitation was carried out in the followingsteps:
ith the transfer from VBAl to VBA2 interrupted, silver
nitrate solution from VBAl and KBr were run
simultaneously run into the reaction vessel for 2
minutes.
A-G 1630
,
'
` ~L5~i~33
-- 28 --
2. The transLer from VBAl to VBA2 ~as then started. A
stirrer provided for rapid mixing in VBA2.
3. After 18 minutes, the -transfer from VBAl to VBA2 was
again interr~pted. Silver bromide was precipitate~
for 12 minutes by running in the bromide solution
and the silver nitrate solution from VBA2.
A monodisperse, octahedral silver bromide emulsion
having a mean edge length of 0.8 ~ and a mean deviation
from the grain diameter of 6.0 % was obtained. Had the
10 process known from German Offenlegungsschrift No 2,107,118
been used, this emulsion would have taken 85 minutes to
produce~
EXA~LE 6
The test arrangement used was the same as in E~ample
15 5, except that, instead of the thioether, 135 g of imidazole
were initially introduced at pH 6. The silver nitrate
was again added through the cascade and the halide
through the inlet Z. Precipitation was carried out in
the following steps:
20 1 With the transfer from VBAl to VBA2 i p
silver bromide was precipitated for 3 minutes at a
pAg-value of 8.8.
2. The tran~er from VBAl to VBA2 was then started and
precipitation continued for 40 minutes in the reaction
vessel at a pAg-value of 6.8.
3. The transfer from VBAl to VBA2 was then interrupted
again. Precipitation was then continued for 7
minutes by addition of the solution from VBA2 and
the halide solution.
A monodisperse, octahedral emulsion having an edge
length of 1.4 ~ and a mean deviation from the grain
diame-ter of 7.3 ~0 was obtained. Had the process known
from German Offenlegungsschrift No. 2,107~118 been used,
a total of 205 minutes would have been required to produce
35 a corresponding emulsion.
A-G 1630
. , ~ . , .
5~3
- 29 --
A silver bromide emulsion was prepared by the double
jet process according to Figure 1. Under pAg control,
potassium bromide was added in the form of a 2-molar KBr
solution through the inlet Z at a pAg value of 9. The
silver nitrate was added through a cascade operating on
the basi~ of the following data:
vAl = 14 ml/min,
vA2 = 60 ml/min.
cAl = 5.9 moles of AgN03 per litre
cA2 = 0~1 mole of AgN03 per litre.
Precipitation was carried out in the following steps:
1. With the transfer from VBAl to VBA2 interrupted,
silver nitrate solutIo~from VBA2 and KBr were
simultaneously run into the reaction vessel for
3 minutes.
2. The transfer from VBAl to VBA2 was then started. A
stirrer provided for rapid mixing in VBA2. At the
same time, more silver bromide was precipitated by
addition from VBB2 and by introduction of the KBr
solution into the reaction vessel.
3. After 40 minutes, the transfer from VBAl to VBA2
was interrupted again. Silver bromide was
precipitated for another 7 minutes by addition of
the bromide solution and the silver nitrate solution
from VBA2.
A monodisperse, octahedral silver bromide emulsion
having a mean edge length of 0.8 u and a mean deviation
from the grain diameter of 6.0 /0 was obtained. Had the
process known from German Offenlegungsschrift No. 2,107,
118 been used, this emulsion would have taken 125 minutes
to produce.
A-G 1630
339
-- 30 --
~YAMPLE 8
An emulsion obtained in accordance with E~ample 3
was ~locculated by the addition of polystyrene sulphonic
acid and reduction of the pH with mineral acid to 3.0,
decanted and washed in order to dissolve out the e~cess
water-soluble salts. After redispersion at pH 7.0, the
necessary quantity of gelatin was added, sodium thio-
sulphate and gold chloride were introduced and the
emulsion ripened to maximum sensitivity at a temperature
of from 50C to 60C, a pH value of from 5.5 to 6j5 and
a pAg value of from 8.6 to 9.2.
The emulsion was made ready for casting by adding
20 ml/kg of a 1 ~ methanolic solution of 4-hydroxy-6-
methyl-1,3,3a,7-tetra-azaidene, 10 ml/kg of 10 ~0 formalin
solution and 10 ml/kg of a 5 /0 aqueous saponin solution
as wetting agent. The emulsion was cast onto a cellulose
acetate support, the film sample was exposed behind a
grey wedge and developed for 7 minutes and 16 minutes
in a developer of the following composition:
Sodium sulphite sicc. 70.0 g
Borax 7.0 g
hydroquinone - 305 g
p-monomethylaminophenolsulphate~.5 g
Sodium citrate 7.0 g
Potassium bromide 0.4 g
made up with water to 1 litre.
The gradiation curves shownin Figure 3 were obtained
after sensitometric evaluation (curve a after development
for 7 minutes, curve b after development for 16 minutes).
A-G 16~0
.S~839
- 31 -
EXA~PLE 9
An emulsion was p~epared in the same way as in
Exampl~ 3, e~cept that precipitation step 5.) was
replaced by the following procedure:
A~ter digestion for 20 mi~utes at 70C, as in 4.),
more silver bromide was precipitated ~or 20 minutes by
the double jet process using a 0.5 molar AgN03
solution and a 0,5 molar bromide solution, a cascade
arrangement being provided on the halide side. 5 minutes
after the beginning of the addition, 1.8 litres o~ water
in which 0.5 g of KI was dissolved were run into the
bromide solution over a period of 15 minutes.
A relatively uniform emulsion containing rounded
crystals with a mean grain diameter of 0.4 ~ was obtained.
The emulsion was further processed in the same way
as in E~ample 8.
The gradation curves shown in Figure 4 were obtained
(curve a a~ter development for 7 minutes, curve b after
development for 16 minutes).
E~amples 8 and 9 show how emulsions having very
different properties may readily be obtained in
accordance with the invention.
:~XAMPI.l~ 1 0
A silver bromide chloride emulsion was precipitated
according to Figure 50 A solution with 800 ml of a gelatirle
solution with 200 mg of the thioether per mole of AgN03,
as described in Example 3, are initially introduced into
the reaction vesselO
Two supply vessels according to Figure 5 are used
both for the halide and for the silver nitrate side:
VB1B1 and VB'B2 for the halide solution and VB'A1 and VB'~2
for the silver nitrate solutionO
The following solutions are filled into the vessels:
A-G 1630
339
- 32 -
VB~A1 = 0,376 mole AgN03/
VB'A2 = 6,68 mole AgN03/l
VB'B1 = O,41 mole KBr/1
0,26 mole NaCl/l
VB'B2 = 5,12 mole KBr/l
3,25 mole NaCl/l
The solution initially introduced into the reaction
vessel and reaction solutions have a temperature of 70Co
The solutions from VB'A1 and VB'A2 flow into a
regulating device according to Figure 50
The solutions from VB'B1 and VB'B2 flow into another
regulating device according to Figure 50
From these regulating devices
a) the total flow rate V'gA, containing AgN03
b) the total flow rate V'gB, containing the halides
flow into the reaction vesselO
The two regulating devices in which the solutions from
the two supply vessels on each side unite are controlled
simultaneously and synchronously such that exponentially
over a period of 50 minutes the inlet opening of the
solution having a low concentration is decreased from
100 % to 0 % and, contrary to this, the inflow amount of
the concentrated solution is increased from 0 % to 100 %0
Silver bromide chloride crystals are obtained having
an average diameter of 0,8/u with an average deviation
of 7 %0
A-G 1630
