Note: Descriptions are shown in the official language in which they were submitted.
1 15532~
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This invention relates to a photosensitive
photographic material containing at least one silver
halide emulsion layer, to a process for its production
and to its use for the production of photographic
images. More particularly, the invention relates to
a photographic material containing an emulsion of
narrow grain size distribution.
It is known that emulsions of narrow grain size
distribution, particularly so-called monodisperse
emulsions, can be produced and used for example for
direct-positive photographic materials, but al~o ~or
other photographic materials.
Emulsions such as these having a narrow grain
size distribution are generally produced by the
so-called "double jet process". In this process,
the silver halide grains are produced by simultaneously
running an aqueous solution oi a water-soluble silver
salt~ for example silver nitrate~ and a water-soluble
halide, ~or example an alkali metal halide, such as
potassium bromide, into a vigorously stirred, aqueous
solution of a silver halide peptising agent, preferably
gelatin, a gelatin derivative or any other protein-
based peptising agent. Suitable processes of this
type are described in British Patent No. 1,027,146
and in an Article by E. Moisar and S. Wagner in
"Berichte der Bunsengesellschaft fur physikalische
Chemie", 67 (1963), pages 356 to 359.
- A characteristic of the double jet process is
that large excesses of halide have to be avoided to
prevent so-called Ostwald ripening which would result
in a hetero-disperse grain size distribution~ For
the same reason, other silver halide solvents can
be added in only limited quantities.
One of the problems of the double jet process
for the production of emulsions of narrow grain size
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distribution is that both the pH-value and also the
pAg-value have to be kept strictly constant in order
to prevent, on the one hand, undesirable Ostwald
ripening and, on the other hand, the formation of
nuclei which would again result in a hetero-
disperse grain size distribution. For this reason,
extreme care has to be taken to ensure that the
silver salt and the halide, which are introduced
simultaneously, are run in at the same volumetric
rate and in the same concentration. Above all, care
has to be taken to ensure that no local over-
concentrations occur at the points of entry. Thus,
the double jet process imposes stringent
requirements in terms of process engineering which
are not always easy to satisfy, particularly in the
case of relatively large batches. In particular,
it is extremely difficult to produce by this process
silver halide emul~ions having a narrow grain size
distributlon for relatively high iodide contents.
If excessive concentrations of iodide are introduced,
new nuclei are generally formed and the emulsion
generally becomes heterodisperse.
Although it is known from German Offenlegungs-
schrift No. 2,043,392 and US-Patent No. 4,026,668 that
the precipitation conditions prevailing in the
double jet process, particularly the concentrations,
and the pH and pAg-values can be controlled in the
required manner, one disadvantage common to these
methods and apparatus is that they are complicated
and expensive.
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It is also known to blend emulsions of different
grain size in the presence of a silver halide sol-
vent. One condition for such methods is that the
silver halide crystals used have different solubili-
ties. This can be effected by a different grain size
and/or different halide composition. Such methods are
known from US PS 2146938, 3206313,3317322, German
Auslegeschrift 1207791 and the articles of D. Markocki
and W. Romer in "Korpuskular Photographie IV,
(1963) pages 149 seq and of Ondreichik in "Zhurnal
Nauchnoi Prikladuei Fotografi Kinematografi 5,
No. 2 (1960) pages 81-83.
The more soluble silver halide emulsions used
in such processes are generally fine grain emulsions
with an average grain size, which is smaller than
the average grain size of the less soluble emulsion;
particularly useful are the so-called Lippmann emulsions
which generally have an average grain size of less
than 0.1~.
One advantage of thls method is that the
formation of new silver halide nuclei is almost
completely avoided. In addition, there is no need
whatever to take any special precautions in terms of
apparatus for avoiding overconcentrations or to use con-
trol systems for the pH or pAg-value since the more
soluble emulsion is in itself an optimally equimolar
source of silver halide.
One disadvantage of the process described by
Markocki and Romer is that the less soluble emulsions
have to be produced by subjecting part of the Lippmann
emulsion used, to Ostwald ripening with a high
concentration of bromide ions in order in this way
to obtain relatively large sllver halide grains. An
emulsion having a heterodisperse grain size
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distribution is of course formed in this way. By
contrast, for producing emulsions of narrow grain size
d$stributlon, lt is of advantage for the prepared less
soluble emulsion also to be present in a narrow grain
size distribution, i.e. homodisperse. Another serious
disadvantage of the process described by Markocki and
Romer lies in the fact that it is virtually unuseable
for relatively large emulsion batches. This is
because Markocki and Romer's process is carried out
by adding the Lippmann emulsion either continuously
or batchwise to the core emulsion. Where the Lippmann
emulsion is added continuously, the fine-grained
component has to be added with extremely vigorous
stirring to prevent the formation of heterodisperse
emulsions. In the case of relatively large batches,
this is virtually impossible. Where the Lippmann
emulsion is added batchwise, the individual additions
have to be separated by, ln some cases considerable,
lntervals ln order to avoid the formation of
heterodisperse systems. Accordingly, this variant
is also unsuitable for practical application.
Furthermore, in the known blending processes only
small amounts of iodide are used both in the more
and the less soluble starting emulsion. Therefore,
only emulsions with small amounts of iodide
are obtained.
One object of the present invention is to provide
an improved photographic material containing at
least one photosensitive silver halide emulsion layer
which is simple to produce in comparison with known
methods and which may even have a relatively high
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iodide content. Another object of the invention is,
in particular, to provide a simple process for
producing silver halide emulsions of narrow grain
size distribution.
A photosensitive photographic material which
comprises a support bearing at least one silver halide
emulsion layer with silver halide grains of narrow
grain size distribution has now been found in which
the silver halide emulsion is obtained by
a) treating a starting silver halide emulsion of
narrow grain size distribution with a water-soluble
iodide, preferably an alkali or ammonium iodide,
with at least partial conversion of the silver
halide emulsion, and
b) digesting the emulsion obtained with a silver
halide solvent, optionally with addition of
further silver halide emulsion which is more soluble
than the converted starting emulsion the more
soluble silver halide grains growing onto the
converted silver halide grains.
Furthermore it has been found that
this material is suitable for the production
of photographic images.
In the context of the invention, an emulsion of
narrow grain s$ze distribution is an emulsion in which
at least 75% of the silver halide grains show a
maximum deviation of 50% from the mean grain diameter.
In one preferred embodiment, the silver halide
emulsions are monodisperse, monodisperse emulsions
in the context of the invention being emulsions ln
1,
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1 15S325
which at least 95% of the silver halide grains
show a maximum deviation of 40% from the mean
grain diameter.
The emulsion to be treated with the water-
soluble iodide may consist completely or predominantly
of silver chloride and/or particularly of silver
bromide; but this emulsion may also comprise silver
iodide in optionally considerable amounts. The
final emulsion obtained in accordance with the
invention may contain any amount of silver iodide.
In one embodiment of the invention, a
Lippmann emulsion of narrow grain size distribution
consisting predominantly of silver bromide is added
all at once or gradually to a solution of a protective
colloid, particularly gelatin, and a certain
quantity of iodide ions, for example ln the form of
alkali iodide, a Llppmann emulslon belng understood
to be an emulslon of which the silver halide grains
have a maximum diameter of 0. 1 ~. This Lippmann
emulsion may be produced by the usual processes and,
in particularly, by the double jet process.
A silver halide solvent is then added. In this
variant, the Lippmann emulsion serves as its own pre-
precipitate. A corresponding proportion of the
Lippmann emulsion is converted by the iodide ions
initially introduced, the non converted grains
growing onto the converted grains.
It is also possible additionally t~ add part
of the silver halide solvent to the- initially
introduced solution of the dispersant and the iodide
ions. It is preferred to add at most 10 mole %
of t~e silver halide solvent, based on the quantity
of silver halide used. This procedure is particularly
AG 1598
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--8--
advisable in cases where it is intended to add
relatively little iodide.
The mean grain diameter of the silver halide
grains thus obtalned preferably lies between 0.4
and 1.5 ~ and is controlled by the choice of the
dissolution/crystallisation conditions for the
Lippmann emulsion and, in particular, by the
temperature applied and by the quantity of silver
halide solvent added.
In a second, preferred embodiment of the
invention, a separate pre-precipitate is used. To
this end, an emulsion of narrow grain size distribution,
consisting of silver bromide or silver chloride or
mixtures thereof, is initially prepared. Silver iodide
may be present too.
Pre-precipitates such as these are obtained
ln known manner ln a narrow grain size distribution,
for example by the single or double jet process, optionally
pAg-controlled.
According to the invention, this pre-precipitate
is at least partly converted by the addition of iodide
ions before or after physical ripening. The quantity
of iodide added may be varied within wide limits
without any undesirable hetero-dispersity occurring
either in the pre-precipitate or in the emulsion
ultimately obtained. The emulsion obtained is called
the less soluble emulsion. This less soluble emulsion
may comprise 10-100 mole %, preferably 15-75 mole %
of silver iodide.
i
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g
A more soluble, generally a fine grain emulsion,
preferably a ~lppmann emulsion, is added to the less
soluble emulsion. The more soluble emulsion generally
consists of silver chloride or silver bromide or
mixtures thereof and may comprise up to 10 mole %
preferahly up to 6 mole % silver iodide.
Furthermore, a silver halide solvent in a suitable
amount is added. This amount depends inter alia on the
type of the solvent used and the temperature of the
blending process. Suitable amounts comprise 0.05-2 molar
solutions.
The whole is then digested until the more soluble
silver halide crystals have grown onto the converted,
less soluble silver halide crystals to form an emulsion
of narrow grain size distribution.
The molar ratio between the silver introduced with
the more soluble emulslon and the silver added in the
form of the converted emulsion is preferably between
0.3:1 and 30:1, preferably between 1:1 and 15:1.
Before blending the more and the less soluble
emulsions, preferably at least one of these emulsions
is freed from salt and/or concentrated, e.g. by
flocculation. The emulsions can be mixed in coagulated
form and redispersed together. Thus, very high
silver halide concentrations are possible without
the known impairing effects of high salt concentrations.
The silver halide concentrations may be between 0.2
and 2 mol of silver-halide per kg of emulsion.
AG 15~8
1 155325
The more soluble silver halide may be added at different
stages and more than once, but the addition can be made continuous-
ly too.
In one preferred embodiment, the conversion and blending
steps are made alternating more than once. Thus the position of
iodide in the finished grains can be controlled. In this embodi-
ment the more soluble emulsions used may have differing halide
composition.
The blending procedure may be effected preferably between
40-60C, and at a pAg of 6,5 to 11,8. The time necessary for
blending is generally between 5 and 90 minutes.
Particularly preferred silver halide solventsare:
halides, preferably alkali or ammonium halides, most preferably
bromides or chlorides; ammonia, thiocyanates, preferably alkali and
ammonium thiocyanates, sulphites, preferably alkali or ammonium
sulphites; thiosulphate; organic amines; thioethers,imidazole and
derivatives of imidazole. In a preferred embodiment of the inven-
tion organic thioethers are used. Suitable thioethers are e.g.,
described in United States Patent Nos. 3,271,157, 3,507,657,
3,531,289 and 3,574,628. Particularly suitable thioethers are
disclosed in the German Offenlgenungsschrift 2,624,862. Particu-
larly suitable thioethers are:
HO~CH2)2-S-(cH2)2 S (CH2)2
HOOC-(CH2)3-S-(CH2 3-COOH
CH3 S (CH2)2 2
C2H5-S-(CH2)2 -S-(CH2)2-NH-CO)CH2)2COOH
C2H5-S- (CH2) 2-S- (CH2) 2-NH-CO-NH2
.- -- 10 --
1 155325
- 1 1 -
The emulsions obtained in accordance with the
invention preferably may have any silver iodide con-
tent, but preferably from 3 to 15 mole %.
For removing the water soluble salts, the silver
halide emulsions produced in accordance with the
invention may either be chilled, converted into noodle
form and rinsed with water in known manner or may
even be coagulated with a coagulating agent and
subsequently washed, as known for example from German
Offenlegungsschrift No. 2,614,862.
Suitable protective colloids and binders for
the silver halide emulsion layer are the usual
hydrophilic film-forming materials, for example
proteins, particularly gelatin, alginic acid or
derivatives thereof, such as esters, amides or salts,
cellulose derivatives, such as carboxy methyl
cellulose and cellulose sulphates, starch or
derlvatives thereof or hydrophilic synthetic binders,
such as polyvinyl alcohol, partially hydrolysed
polyvinylacetate, polyvinyl pyrrolidone and others.
The layers may also contain in admixture with the
hydrophilic binders other synthetic binders in
dissolved or dispersed form, such as homopolymers or
copolymers of acrylic or methacrylic acid or their
derivatives, such as esters, amides or nitriles, also
vinyl polymers, such as vinyl esters or.vinyl ethers.
The emulsions according to the invention may be
applied to the usual support.layers, for example to
substrates of cellulose esters, such as cellulose
acetate or cellulose acetobutyrate, also polyesters,
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p~rticularly polyethylene terephthalate, or
polycarbonates, particularly based on bis-phenylol
propane. Other suitable substrates are paper
substrates which may contain water-impermeable
polyoleiin layers, ior example oi polyethylene or
polypropylene, and glass or metal substrates.
The emulsions may also be chemically sensitised,
~or example by the addition during chemical ripening
oi sulphur-containing compounds, ~or example allyl
10 isothiocyanate, allyl thiourea and sodium thiosulphate.
Other suitable chemical sensitisers are reducing
agents, ior example the tin compounds described in
Belgian Patents Nos. 493,464 or $68,687, also
polyamines, such as diethylene triamine or aminomethyl
15 sulphinic acid derivatives , ~or e~ample according to
~elgian Patent No. 547,32;.
Other suitable chemical sensitisers are noble
metals and noble metal compound~, suah as gold,
platinum~ palladium~ iridium, ruthenium or rhodium.
20 This method o~ chemical sensitisation is described
in the article by R. ~oslowsky in Z. Wiss. Phot.
46, 65 - 72 (1951).
It is also possible to sensitise the emulsions
with polyalkylene oxide derivatives, for example wit~
25 polyethylene o~ide having a molecular weight oi irom
1000 to 20,000, with condensation products o~ alkylene
oxides and aliphatic alcohols, glycols, cyclic
dehydration products o~ he~itols, with alkyl-substituted
phenols, aliphatic carbo~ylic acids, aliphatic amines,
30 aliphatic diamines and amides. ~he condensation
products have a molecular weight oi at least 700 and
)
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-13-
preferably o~ more than 1000. To obtain special
effects, these sensitisers may o~ course be used in
combination with one another, as described in Belgian
Patent No. 537,278 and British Patent No. 727,982.
The emulsions may also be optically sensitised,
for example with the usual polymethine dyes, such as
neutrocyanines, basic or acid carbocyanines, rhoda-
cyanines, hemicyanines, styryl dyes, o~onols and the
like. Sensitisers such as these are described in
F.M. Hamer's work entitled "The Cyanine Dyes and
Related Compounds", l964, Interscience Publishers,
John Wiley and Sons.
The emulsions may contain the usual stabilisers
such as, for example, homopolar or salt-like
compounds o~ mercury with aromatic or heterocyclic
rings, such as mercapto triazoles, simple mercury
salts, sulphoniummercury double salts and other mercury
compounds. Other suitable stabilisers are azaindenes,
preierably tetra- or penta-azaindenes, particularly
those substituted by hydroxyl or amino groups.
Compounds such as these are described in the article
by Birr in Z.Wiss.Phot. 47 (1952), 2 - 58. Other
suitable stabilisers are inter alia heterocyclic
mercapto compounds, ~or example phenyl mercapto
tetrazole, quaternary benzthiazole derivati~es and
benzotriazole.
The emulsions may be hardened in the usual way,
for example with formaldehyde or halogen-substituted
aldehydes containing a carboxyl group, such as
mucobromic acid, diketones, methane sulphonic acid
esters and dialdehydesO
The photographic layers may also be hardened
with hardeners of the epoxy, heterocyclic ethylene
imine or acryloyl type. Example~ of hardeners such
as these are described ~or example in German
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-14-
Offenlegungsschrift No. 2,263,602 or in British
Patent No. 1,266,655. It is also possible to harden
the layers by the process described in German
Of~enlegungsschrift No. 2,218,009 in order to obtain
colour photographic materials which are suitable for
processing at high temperatures.
It is also possible to harden the photographic
layers or the colour photographic multilayer materials
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. 71 02 716 and German Offenlegung-
sschrift No. 2,332,317. Examples of hardeners such
as these are diazine derivatives containing alkyl or
aryl sulphonyl groups, derivatives of hydrogenated
diazines or triazines, such as for example 1,3,5-
hexahydrotriazine, fluorine-substituted diazine
derivatives such as, for example, fluoropyrimidine,
esters of 2-substituted 1,2-dihydroquinoline or
1,2-dihydroi~oquinoline-N-carboxylic acids. Other
suitable hardeners are vinyl sulphonic acid
hardeners, carbodiimide or carbamoyl hardeners, as
described ~or example in German Offenlegungsschrifts
Nos. 2,263,602; 2,225,230 and 1,808,685; French
Patent No. 1,491,807; German Patent No. 872,153 and
East German Patent No. 7218. Other ~uitable
hardeners are described, for example, in British
Patent No. 1,268,550.
The present invention may be used for the
production oi both black-and-white photographic
images and colour photographic imagesO Colour
photographic images may be obtained for example on
the known principle of chromogenic development in the
presence of colour couplers which react with the
oxidation product of dye-giving ~-phenylene diamine
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-15-
developer~ to form dyes
~ he colour couplers may be added ior example to
the colour developer on the principle of the so-called
~eveloping-in ~rocess. In a preierred embodiment,
the photographic material itself contains the usual
colour couplers which are generally incorporated into
the silver halide layers. Thus, the red-sensitive
layer may contain for example a non-difiusing colour
coupler for producing the cyan component colour image,
generally a phenol or a-naphthol couplerO The
green-sensitive layer may contain for example at least
one non-diffusing colour coupler for producing the
magenta component colour image, 5-pyrazolone or
imidazolone colour couplers normally being used.
The blue-sensitive layer may contain for e~ample a
non-diffusing colour coupler for producing the
yellow component colour image, generally a colour
coupler containing an open-chain ketomethylene group.
Colour couplers of this type are known in large
numbers and are desoribed in a large number of Patent
Specifioations. In this connection, reference is
made for example to the article entitled "Farbkuppler
(Colour Couplers)" by W. Pelz in "Mitteilungen aus
den Forschungslaboratorien der Agfa, Leverkusen/Munchen"
Vol. III (1961) and to Eo Venkataraman in "The
Chemistry of Synthetic Dyes", Vol 4, 341-387, Aoademic
Press, 1971.
Other suitable non-diffusing colour couplers
are 2-equivalent couplers. 2-Equivalent couplers
contain a removable substituent in the coupling
position, so that, in contrast to the usual 4-
equivalent couplers, they only require two
equivalents of silver halide for dye formation.
Suitable 2-equivalent couplers include for example
the known DIR-couplers, in which the removable
radical is liberated as a diffusing development
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1 155325
-16-
inhibitor after reaction with colour developer oxidation products.
In addition, the so-called white couplers may be used for improving the
properties of the photographic material.
The non-diffusing colour cou~lers and dye-giving oamFounds are
added to the photosensitive silver halide emulsions or other casting
solutions by standard methods. In the case of water-soluble or aLkali-
soluble con~xnuxls, they may be added to the emulsions in the form of
aqueous solutions, to which water-miscible organic solvents, such as
ethanol, acetone or dimethyl formamide may be added. ~here the non-
diffusing colour couplers and dye-giving compounds are water-insoluble
or alkali-insoluble compounds, they may be emulsified in known manner,
for example by directly mixing a solution of these compounds in a lcw-
boiling organic solvent with the silver halide emulsion or initially
with an aqueous gelatin solution, after which the organic solvent is
removed in the usual way. m e resulting gelatin emulsion of the
particular co~Found is then mixed with the silver halide emLlsion.
So-called coupler solvents or oil formers may additionally be used for
emLlsifying hydrophobic compounds of the type in question. Coupler
solvents or oil formers are gener~7ly relatively high boiling
organic compounds which include the non-diffusing colour couplers and
development-inhibitor-releasing ccnçx~Dnds to be emulsified in the
silver halide emulsions in the form of oily droplets. In this
connection, reference is made for example to US Patents No. 2,322,027;
2,533,514; 3,689,271; 3,764,336 and 3,765,897.
Photographic material according to the invention may be developed
with the usual colour developer substances, for example
N,N-dimethyl-E~phenylene diamine,
4-amino-3-methyl-N-ethyl-N-methoxyethyl aniline,
2-amino-5-diethylamino toluene,
N-butyl-N-G~sulphobutyl-E~phenylene diamine,
2-amino-5-(N-ethyl-N-B-methane sulphonamidoethyl-amino)-toluene.
N-ethyl-N-~-hydroxyethyl-P-phenylene diamine,
N,N-bis-(B-hydroxyethyl)-E~phenylene diamine, I
2-amino-5-(N-ethyl-N-B-hydroxyethylamino)-toluene.
Other suitable colour developers are described for example in
J.Amer.Chem.Soc. 73, 3100 (1951).
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The emulsions produced in acoordance with the invention may
be used in a variety of ways. They may be used for thie production of
photographic negative materials and also for the prcduction of photo-
~raphic material with unfogged, dlrect-positive silver halide emul-
sions, l.e. those which have a realtlvely high inner grain sensitivity
without surface fogging and which are developed under fogging oondltions.
The emulsions according to the invention maybe used in known manner for instant colour picture
processes and dye transfer processes. In these
proce99e9, the dyes for the component colour images
diffuse into an image receiving layer, where they
are firmly anchored, or the colour couplers diffuse
into the image-receiving layer where, after dye
giving development in the usual way, they are reacted
15 to form the image dye. Dge transfer processes and
couplers used in them are also described in US
Patents Nos. 2,983,606; 3,087,817; 3,185,567;
3,227,550; 3,227,551; 3,227,552; 3,227,554;
3,253,915; 3,415,644; 3,415,645 and 3,415,646.
The emulsions ac¢ording to the invention may
also be used for dye transier processes in which the
particular layer contains a non-difiusing compound
which is a dye or a dye precursor and which, during
development in the presence Or the alkali processing
25 masg~ giveg Oir dyes preferably containing acid
groups which dirruse under the action of photographic
developer oxidation products formed in imagewise
distribution.
A variety o$ chemical compounds is available
30 for thi~ purpose~ Non-diffusing dye providing compounds
according to US Patent No. 3,628,952 for e~ample are
particularly suitable~ These compounds prov~de
diffusing dyes on reaction with oxidation products
of black and white or colour developers. Another
suitable class of compounds is described in ~erman
Patent No. 1,095,115. The compound~ in question, on
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reaction with oxidised colour developer, give difiusing
dyes which are generally azomethine dyes Another
suitable dye provlding syst3m is described in US Patents
Nos. 3,443,939 and 3,443,940. In this system, difiusing
dyes are provided by a ring closing reaction under
the action of oxidised developer substances.
Accordingly, the photographic materials according
to the invention are particularly suitable ior the
production oi photographic images by imagewise
exposure, development and iurther processing in the
usual way.
The materials according to the invention are
distinguished by the iact that they contain at least
one silver halide emulsion oi narrow grain size
distribution for any iodide content and, in particular,
ior relatively high iodide contents. In one preierred
embodiment~ the emulsions produced in a¢cordance
with the invention show high inhibitability and are
thereiore particularly suitable ior producing high
inter-image eiie¢tsO The inter-image eiiect is
normally used ior improving the sensitometric
properties oi photographic materials and is described
ior example in the corresponding article by C.R. Barr
in "Photographic Science and Engineering" 13 (1969),
Pages 74 et seq.
EXAMPLE 1
A Lippmann emulsion was initially prepared by
W. Markocki's process (Korpuluskar Photographie, IV
(1963), page 165), except that no cadmium nitrate
was used. The grains oi the Lippmann emulsion had a
mean grain diameter oi 0007 lu. 1500g oi the resulting
Lippmann emulsion, together with silver halide in a
quantity corresponding to 340 g oi silver nitrate,
were added over a period oi 10 minutes at 45C to a
solution oi 22.5 g oi potassium iodide and 120 g oi a
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gelatin containing inhibitors and ripeners in 5 litres
of distilled water. After the Lippmann emulsion had
been converted by the iodide ions initially
introduced, 375 ml of a 14.7 molar ammonia solution
were added. After digestion for 30 minutes at 45C,
the emulsion was cooled in known manner and adjusted
with dilute sulphuric acid to pH 5Ø The emulsion
was then coagulated in known manner, washed and
finally redispersed in known manner at pH 6.5 by the
addition of water and gelatin of the above-mentioned
type. The emulsion was then chemically sensitised
in the usual way with a gold thiocyanate complex ~alt.
For after-ripening, the emulsion was digested at a
temperature of 53C, after which phenol was added as
preservative in the usual way.
The emulsion obtained had a narrow grain size
distribution, its mean grain diameter amounting to
0,58 ,u. Figure 1 shows the so-¢alled cumulative size distri-
bution curve of these emulsions. Each point on
the ordinate of this cur~e indicates how many % of
the crystals are larger than the associated abscissa
value.
For determining the sensitometric properties,
a sample of the emulsion was poured onto a suitable
support, 20 ml (per kg of the emulsion samples) of
a 1 % aqueous solution of 4-hydroxy-6-methyl-1,3,3a,7-
tetraazaindene, 35 ml/kg of a 7.5 % aqueous solution
of saponin and 35 ml of a 2 % aqueous solution of
mucochloric acid being added to the emulsion sample
before casting. The photographic material obtained
was egposed imagewise through a grey wedge in the
usual way and developed ~or 7 minutes at 20C in the
following developer:
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Developer
ethylene diamine tetraacetic acid 1.5 g
sodium hexamethaphosphate 1 g
sodium sulphite, sicc. 60 g
S borax 15 g
potassium bromide 3 g
hydroquinone 6 g
l-phenyl-3-pyrazolidone 0.7 g
made up with water to 1 litre.
The ~alues set out in Table 1 were obtained.
EXAMPLE 2
The emulsion was produced in the same way as
described in Example 1, except that only 750 g of the
Lippmann emulsion were added to the solution o~
15 potassium iodide and gelatin in 5 litres o~ distilled
water. The emulsion obtained was ~urther processed
in the same way as described in Example 1. Figure 2
shows the cumulative size distribution curve of the emulsion
obtained which had a mean grain diameter o~ o.65 y.
20 The sensitometric values a~ter exposure and processing
in accordanoe with Ex~mple 1 are shown in Table 1.
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Table l
,_
Example ~ E S D Ag-coating
No. max (g of ~gN03/
m2
1.92 27.7 o.lo 3.75 7.2
2 1.65 31.3 o.o6 3.70 7.4
~ = gradation
E = sensitivity; an increase of 3.o units represents
a doubling of sensitivity
S = fogging
DmaX = maximum densityO
EXAMPLE 3
A) An emulsion according to Example l was melted
in known manner, followed by the addition of 180 g
per mole oi silver halide of a sensitiser
correspondlng to the formula
e H5C~ c-c~ c~ ~ C2 5 4
C2H5 C2 5
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The following components were also added:
1.) 50 g of a cyan colour coupler corresponding
to the formula
OH
~ CoNH-(cH2)4-o ~ C12~25
per mole of qilver expressed as silver nitrate
2.) 1,5 g oi 4-hydroxy-6-methyl-1,3,3a,7-tetra-
azaindene per mole oi silver expressed as
silver nitrate and a wetting agent.
The emulsion was cast onto a support of
cellulose acetate (silver coating, expressed as
silver nitrate : 3.7 g/m2).
Aiter drying and exposure behind a step wedge
and a suitable iilter in a sensitometer, the material
was developed ior 3,25 minutes at 38C in the following
developer:
Developer
i
potassium sulphite 5 g
potassium bromide 104 g
potassium carbonate 35 g
ethylene diamine tetraacetic acid 1~5 g
disodium salt oi l-hydroxyethane-l,l-diphosphonic acid 2 g
AG 1598
1 155325
~odlum metabisulphite 0.28 g
sodium bicarbonate 1.55 g
4-amino-3-methyl-N-ethyl-N-(~-hydroxyethyl)-aniline 4,7 g
hydroxylamine sulphate 2.4 g
made up with water to l litre.
Aiter development, the material was further
processed in the usual way.
B) An emulsion was melted and ~urther processed
in the same way as in A). 4 g per mole of silver
(e~pressed as silver nitrate) of a DIR-coupler
corresponding to the formula were additionally added:
. ~q~
H3C-(CH2)15-0 ~ ~ ,N
S03H
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Further treatment and development were carried
out in the same way as described in A).
Figure 3 shows the density curves obtained. It
can be seen that the emulsion had a pronounced
reaction to the stabiliser released by the DIR-coupler.
~ he sensitometric data are shown in Table 2.
~able 2
Material E ~ S
10 A without DIR-
coupler 34.0 1.70 0.14
B with DIR-
coupler 28.9 0.84 0.14
~ = gradation
1598.
1 1~5325
Example 4
A silver chlorobromide emulsion with 52 moles % of
bromide with an average grain size of 0.35/u was prepared
as described by Glafkides, Photographic Chemistry,
Fountain Press, 1956, pp 341 seqq. An aqueous 10~ solution
of Kl, equirnolar to 12 mole % of the silver halide, was
added. After digestion the emulsion was cooled,
flocculated and washed.
After redispersion the emulsion contained
1,1 moles of silver halide per kg; the ratio
gelatine/silver nitrate was 0.3. To 1 kg of this
emulsion were added: 500 ml of water, 35 g of NH4Br
and 500 ml of a 7~ methione-solution. At 65C 1,1
moles of a AgBr-Lippmann emulsion were added.This mixture
was maintained at a temperature of 65C for 15 minutes.
The emulsion was then cooled and freed from the soluble
salts. After redisperslon the emulslon contained
6 moles ~ of AgJ. The emulslon was rlpened at 54C,
then conventlonal adjurants were added, then the
emulsion was coated on a suitable support and exposed
and developed a~ described in Example 1. The sensitometric
results showed that an emulsion of medium speed had been
obtained.
Example 5
An ammouiacal silver bromiodide emulsion was prepared
as described by Glafkides (cf.Example 4). An aqueous
10% solution of Kl, equimolar to 19 mole % of the
emulsion, was added. The silver halide grains obtained
had a narrow grain size distribution and an average
grain size of 0.55 ~.
The emulsion was flocculated and washed. After
redispersion the emulsion contained 1,1 moleS of silver
halide per kg of emulsion.
AG 1598
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The ratio gelatine/silver nitrate was 0,35.
To 1 kg of this emulslon were added: 500 ml water,
30 g of NH4Br and 350 ml of a 7% aqueous solution of
imidazole. At 65 C 2,2 mole of a silver bromoicdide
Lippmann-emulsion (Br:I=96:4) were added. Then 2,2 moles
of a AgBr Lippmann-emulsion were added. The emulsion
which was obtained contained 6 mole % of silver iodide.
The emulsion was then cooled and freed from the
soluble salts. After redispersion the emulsion had a
gelatine/silver nitrate ratio of 1,0. The emulsion was
sulphur- and gold-sensitized as generally known. Then
conventional adjuvants were added and the emulsion was
coated on a suitable support and exposed and developed
as described in Example 1. The sensitometric results
showed that a high speed emulsion with a high contrast
had been obtained.
Example 6
A silver bromoiodide emulsion of a narrow grain size
distribution with 6 moles % o silver iodide and an
average grain size of 0.18 ~ was produced by the double-
jet process. An aqueous solution of KI, equimolar to
42 mole % of the silver halide, was added. After digestion
the emulsion was flocculated, and washed. After re-
dispersion the emulsion contained 1,4 moles o silver
halide per kg. To 1 kg of the redispersed emulsion were
added: 500 ml of water, 75 g of NH4BR and 1500 ml
of a 7% methionine solution. Then 9,8 moles of a AgBr
Lippmann-emulsion were added. The emulsion was digested
45 minutes at 65C, cooled, flocculated and redispersed.
AG 1598
115~325
After redisperslon the gelatine/silver nitEate ratio was
0,7. The emulsion was digested and further processed
as described in Example 5. The sensitometric results
showed that an emulsion of medium speed had been obtained
with an average grain size of 0,45 ~.
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