Note: Descriptions are shown in the official language in which they were submitted.
~s~s a.~;
Case 8-13817/TEL 233/+
Negative photographic silver dye bleach material.
It is known that photographic silver dye bleach materials contain
image dyes which are bleached imagewise, in the presence of silver,
by strongly acidic solutions which contain a silver-complexing agent.
This reductive bleaching can be accelerated by bleaching catalysts.
The reducing action of silver on the image dyes can be used for
converting photographically produced silver images into colour images.
In doing so, the silver image normally produced by the exposure of
the material is negative, i.e. a counter-image of the original. The
dye bleaching subsequent to the development then causes a positive
colour image obtained from the negative silver image, which colour
image corresponds to the original. Such positive silver dye bleach
materials are therefore used primarily for producing positive colour
images (colour prints) from (positive) colour slides. If a colour
negative is used as original instead of a colour slide, then a
negative colour image is obtained.
In order to obtain a positive colour image also from a colour negative
with a silver dye bleach material, it is necessary to use a negative
material in which a positive silver ima~e i9 producect by ttevelop-
ment after exposure. The posi~ive silver image t~len leads, ater
processing, to the formation of a colour image which is a counter-
image of the original (colour negative) and is therefore a positive
colour image. Using a negative silver dye bleach material, a
(positive) colour slide as original would consequently lead to the
formation of a negative colour image.
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5 ~ 5
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Suitable processes for producing a positive silver image are based
e.g. on the silver complex diffusion process described in DE
1 572 206 (published 1967) or in GB 656 131 (published 1951), or on
the bromide ion diffusion process known e.g. from DE 859 711
(published 1952). If the silver complex diffusion process is
chosen, then a developing solution which contains the silver
complexing agents is used for developing the negative silver image.
The undeveloped unexposed silver halide areas dissolve in the
developer to form silver complexes which diffuse imagewise into a
receiving layercontaining development nuclei. Silver is deposited OlltO
these nuclei by physical development from the developing solution which
contains the silver complex toform a positive image. For bromide ion
diffusion, the photographic material must contain, in one and the
same layer, development nuclei, a substantial amount of a weakly
light-sensitive silver chloride emulsion, and a small amount of a
highly sensitive silver bromide emulsion. After exposure, bro~ide ions
are released imagewise during the development of the silver bromide
and, in turn, inhibit the development of the silver chloride. In this
process, there are formed simultaneously a weak negative image from
the silver bromide emulsion and a strongly opaque, and therefore
ultimately substantially positive, image from the silver chloride
emulsion.
The use of these processes for obtaining silver reversal images
with silver dye bleach materials is already known from US 2 673 800
(Meeussen et al, 3/1954). The material disclosed therein contains
development nuclei in the dyestuff lsyer. The unexposet and
unreducible salts in ~he light-sensitive siLver halide emulsion in the
superposed layer diffuse as silver complexes into the layer containing
develoFment nuclei and form a positive silver image which i8
converted into a negative colour image by dye bleaching. However, in
this process it is difficult to control the reactions which take
place during development, viz. the development of the exposed and the-
resolution of the unexposed silver halide crystals, the diffusion of
:
1:25~5~L~
the silver complexes formed into the lower layer and the physical
development of the diffused complexes in the dyestuff layer, in such
a manner that colour images with good white and adequate maximum
density are formed. The bro~ide ion diffusion process is used in
accordance with DE 20 53 751 (published 1972) to obtain the positive
silver image necessary for the dye bleaching. In this process, it is
proposed to use an interlayer containing fine-grained silver chloride
to separate the layers provided for the individual colours. Incorrect
colours in a multi-coloured material can be avoided by trapping
bromide ions which diffuse in an unwanteddirection. This process,
however, rules out any use of bromide or other conventional additives
used as antifogging agents, e.g. benztriazole, in the developer
solution. In practice, this requirement can be met only with the
greatest difficulty.
Further, a positive silver image can also be produced in silver dye
bleach materials by iodide ion diffusion, e.g. as described in
EP 44813 (published January 1982). In this process, a masked core-shell
emulsion is used for producing the positive silver image. ~evelopment
is effected chemically, i.e. the developing solution contains no
silver complexing agents. The composition of ehis developing solution
therefore differs from that of solutions used for self-masking
positive silver dye bleach materials, as these latter solutions
contain e.~. silver complexing agents. This is, of course, a
considerable drawback as regards achieving uniformity in the processing
of positive and negative silver dye bleach materials.
Accordingly, it is the object of the present invention to provide a
negative silver dye bleach material, which can be processed in
developing solutions which contain silver complexing agents.
This object is accomplished by using a photographic material which,
- ~L2~;~53~
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by means of iodide ion diffusion, permits development in solutions
which contain silver complexing agents and results in the fonmation
of high-quality images which are couneer-images of the original.
~ccordingly, the invention provides a negative photographic silver
dye bleach material, which contains on a support~
(a) at least one layer containing a bleachable image dye, a low-
sensitive silver halide emulsion (of low sensitivity), and colloidal
nuclei onto which silver deposition may occur, and
(b) at least one layer containing a highly sensitive iodide-containing
silver halide emulsion (of high sensitivity).
A further object of the invention is the use of the photographic
material for producing photographic images.
Still further objects of the invention are a process for producing
photographic ima~es with the aid of the said photographic material,
the images produced with said material, and the composition for
developing said material.
Suitable supports for the photographic material of the invention may
be made of transparent or pigmented cellulose triacetate or poly-
ester. If felt paper is used as support, it may be coated on both
sides with a layer of varnish or polyethylene.
The image dyes must be bleachable under the conditions oE conventional
processing baths for the silver dye bleach process. Suitable dyes are
described e.g. in US 3 454 402 (Anterau et al, 7/1969), US 3 443 952
(Andersau et al, 5/1969), US 3 804 630 (LoefEel et al, 4/1974),
US 3 931 142 (Lenoir et al, L/1976) and US 4 051 123 (Piller et al,
9/1977)-
~ 25~S~
The customary photographic silver halide emulsions may be used forthe photographic material of this i~vention. Suitable silver halides
are silver chloride, silver ~romide or silver iodide7 as well as
mixtures of these halides. The concentrations of the diEferent
halides may vary within wide limits. The low-sensitive silver
halide emu]sions should essentially be free from iodide or should
have an iodide content of less than 1, preferably 0.9 (inclusive)
mole percent. Higher concentrations of iodide are generally not
suitable, as they may hamper the control of the development
necessary for the process of the invention through the presence of
diffusing iodide ions. silver chloride, silver bromide or silver
chlorobromide are therefore suitable Eor the low-sensitive
silver halide emulsions. The highly sensitive silver halide emulsions
used in the process of the invention contain more than 1 (inclusive)
mole percent of silver iodide in addition to silver chloride and/or
silver bromide. It is preferred to use 1 to 10 mole percent of
silver iodide.
It is preferred to use gelatin as protective colloid for the silver
halides. However, other water-soluble protective colloids such as
polyvinyl alcohol or polyvinyl pyrrolidinone are also suitable.
A portion of the gelatin may also be replaced by dispersions of
water- insoluble high molecular compounds. It is customary to use
e.g. dispersion polymers of a,~-unsaturated compounds such as
acrylic acid esters, vinyl esters, vinyl ethers, vinyl chloride,
vinylidene chloride, as well as those of otler mixtures ~Ind
copolymers.
The nuclei present in the lowly sensitive silver halide emulsion
layers and onto which deposition of metallic silver occurs, are
colloidal hydrosols or sulfides of heavy metals and noble metals.
For example, silver and nickel sulEide or hydrosois of gold, silver
and palladium may be used. The nuclei are incorporated in very small
amounts, e.g. 0.1 to 100 mg/m , in the layer.
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For controlling the development kinetics, the low-sensitive layer
may contain developing retarders. In principle, all known developing
retarders which satisfy this condition are suitable. However,
those compounds which can be stored in a diffusion-resistant form
in the photographic layers are preferably suitable. These are
primarily compounds containing ballast groups, which are sparingly
soluble or virtually insolub]e in water.
Examples of suitable compounds of this type are S-mercaptotetrazoles
which are substituted in the l-position by aryl groups, preferably
by polynuclear aryl groups such as naphthyl or diphenyl, or aryl groups
which may also be substituted preferably by long chain ~C13-C18)-
alkyl, especially phenyl, or also by aralkyl or alkyl, each
containing preferably at least 3, most preferably 3 to 18, carbon
atoms.
Examples of particularly suitable developing retarders are 5-
mercaptotetrazoles which are substituted in the l-position by one
of the following groups: n-propyl, i-propyl, n-butyl, i-butyl,
t-butyl, i-amyl, i-octyl, t-octyl, nonyl, decyl, lauryl, myristyl,
palmityl, stearyl, di-t-butyl-phenyl, octylphenyl, dodecylphenyl,
naphthyl, ~- or ~-naphthyl or diphenyl. It is also possible to
use mercaptotetrazoleswhich do not contain trueballast groups and
which are not diffusion-resistant. However, in this case, it must
be ensured that the developing retarder does not diffuse in an
unwanted direction into an adjacënt lnyer and, ~or exan~ple, retard
the developin~ of the ~mul~iolls wllich supply iodide ions. This
can be prevented, Eor example, by inserting an interlayer. Under
this condition, it is also possible, for example, to use
mercaptotetrazoles which are substituted in the l-position by the
following groups: phenyl, phenyl substituted by hydroxyl, halogen
(chlorine or bromine) or lower alkyl (C2-C3), methyl or ethyl
benæoate, methyl or ethyl. In general, however, the use of dif-
=~
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fusion-resistant developing r~tarders is to be preferred because the
layer assembly, especially the assembly of materials having a
multiplicity of colour layers and emulsion layers, is thereby
substantially simplified. The developing retarders may be used in
amounts of 0.2 to 10 millimoles, preferably of 0.5 to 2 millimoles,
per mole of silver in the emulsion.
The low-sensitive layer is preferably directly adjacent to the
highly sensitive layer. Both layers form a pair, of which the
highly sensitive layer is usually positioned above the low-sensitive
layer in the direction of incident light. This arrangement brings
about the high sensitivit7 of the photographic material. It is
therefore possibLe to produce a highly sensitive blac~ and white
negative e.g. by incorporating a black bleachable dye into the low-
sensitive layer, and in doing so to recover the silver employed as
silver halide almost completely from the processing solutions.
However, the two layers may also be separated from each other by
an interlayer in which preferably a bleaching inhibitor is stored in a
diffusion-resistant form.Such bleaching inhibitors are described e.g.
in DE- 1 547 725 (published 1970).
Image dye and colour sensitivity of the iodide-containing silver
halide emulsion of a pair of layers are usually so adjusted that
the emulsion reaches the greatest degree of sensitivity precisely
in that area of the spectrum in which the assigned image dye has its
adsorption maximum. For example, a yellow dye will be assign~d to a
blue-sensitive emulsion.
The photographic material of this invention may contain several such
pairs of layers; It is preferred to use a material which contains
three pairs of layers: on a support a first pair containing a cyan
dye, then a second pair containing a magenta dye, and finally a third
pair containing a yellow dye. The photographic material thus covers
the entire rangeof the spectrum. So-called false colour negative
material, with which special effects can be
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obtained, is produced by selecting other combinations of the sensi-
tivity maximum of the (highly sensitive) silver halide emulsion
and of the absorption maximum of the image dye.
Barrier layers may also be present between the individual pairs of
layers. These barrier layers contain a diffusion-resistant substance
which absorbs iodide ions so as to prevent undesirable interactions
between the pairs of layers.
Further, the photographic material of the invention may also
contain additional interlayers which, in addition to gelatin, may
also contain further additives such as bleaching inhibitors, light
stabilisers, fluorescent whitening agents, filter dyes or plasti-
cisers.
Processing of the exposed and developed silver dye bleach materials
is carried out in conventional manner and comprises silver developing,
dye bleaching, silver bleaching and Eixing, and subsequent washing
which may also be carried out between the individual steps.
The dye bleaching and the silver bleaching, and optionally also
the fixing, can be combined in a single treatment step.
For silver developing, it is possible to use baths of conventional
composition, for example baths which contain hydroquinone as the
developer substance, or additionally l-phenyl-3-pyrazolidone.
The developing solutions must ~Idclition~Lly cont~lin tt~e silver
complexing agetlt which is necess.lry for lnitiating the spontaneous
development in the low-sensitive layer. 5uitable complexing
agents are e.g. the alkali meta] salts, such as the sodium and
potassium salts or ammonium salts, of thiosulfuric acid, and also
salts of thiocyanic acid. However, sodium thiosulfate is preferred.
One litreof developmentbath willcontain e.g. fromO.3 to 60 millimoles
5~
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of sodium thiosulfate, but the optimum amount can vary within the
indicated limits depending on the n~ture of the material, the
temperature of the development bath and of the desired duration of
action. It is also possible to incorporate developer compounds or
developer precursors into the emulsion layers, while at the same
time ensuring by appropriate buffering that these substances remain
inactive in the dry layer during storage. In this case, solely an
activator bath having a high pH value and which may contain no
developer compounds is required for initiating the development.
If the dye bleaching is carried out as a separate treatmen~ step,
the dye bleach baths used preferably contain a dye bleach catalyst
in addition to a strong acid, a water-soluble iodide and an anti-
oxidant for the iodide. Combined dye bleach and silver bleach baths
as a rule also contain a water-soluble oxidising agent in addition
to the specified components. Suitable dye bleach catalysts are pri-
marily diazine compounds, for example derivatives of pyrazine,
quinoxaline or phenazine, which are described for example in DE
2 OlO 280 (published 1970).
Strong acids will be understood as meaning in this context acids which
impart a pH value of at most 2 to the dye bleach bath or combined dye
bleach and silver bleach bath. Thus, for example, it is possible
possible to use hydrochloric acid, phosphoric acid and especially
sulfuric acid, p-toluenesulfonic acid or sulfamic acid.
An alkali metal iodide, for example potassium iodid~ or sodium
iodide, can be uset as water-soluble iodide.
Suitable oxidising agents are nitroso compounts, for example
p-nitrosodimethylaniline, and nitro compounds, for example aromatic
nitro compounds and preferably aromatic mono- or di-nitrobenzene-
sulfonic acids, for example m-nitrobenzenesulfonic acid.
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The antioxidants used are advancageously reductones or water-soluble
mercapto compounds, as well as tertiary water-soluble phosphines.
These la~ter compounds are also effective bleaching catalysts as
described in DE-2 651 969 (published 1977). Suitable reductones are,
in particular> acireductones which have a 3-carbonyl-ene-1,2-diol
grouping, such as reduction, triose-reductone or, preferably,
ascorbic acid.
Possible mercapto compounds are those of the formula HSA(B) , in
which A is an aliphatic, cycloaliphatic, araliphatic, aromatic or
heterocyclic bridge member, B is a water-solubilising radical and
m is an integer of at most 4 (DE-2 258 076, published 1973 and
DE-2 423 814, published 1974).
The thiolactones disclosed in DE-3 045 059 (published 1981) are also
suitable antioxidants.
The fixing bath can be formulated in known and conventional manner.
A suitable fixing agent is e.g. sodium thiosulfate or, advantageously,
ammonium thiosulfate, optionally together with additives such as
sodium bisulfite, sodium metabisulfite and/or ammonium bisulfite, and
optionally a chelating agent such as ethylenediaminetetraacetic
acid.
All treatment baths can contain further conventional additives, for
example hardeners, wetting agents, fluorescent whitening agents
or UV stabilisers.
Exposure of the yhotograpbic material of this invention results in
the formation of a latent image only in the highly sensitive iodide-
containing silver halide omulsion layer. This latent image is con-
verted by the subsequent development into a negative silver image.
In the first layer, which contains the low-sensitive iodide-free
silver halide emulsion and development nuclei, a spontaneous physical
development on the development nuclei is induced under the reducing
~s~
conditions prevailing in ~he developer and through the combined action
with the silver halide complexing agent. Simultaneously, however, iodide
ions are set free imagewise in the superimposed second layer
in tlle course of the development of the silver iodide containing
emulsion to form the negative silver image. These released iodide ions
then diffuse into the adjacent first layer and there inhibit depo
sition of silver onto the nuclei. Thus, controlled by the diffusing
iodide ions, a positive silver image is formed in this dyestuff layer,
since at unexposed areas where in the second layer no iodide ions
are set free, the physical development proceeds until complete density
is attained, whereas physical development is suppressed at areas of
strongest exposure by the released iodide ions. To delay the physical
development in the nuclei containing layer until sufficient iodide
ions have diffused thereinto from the adjacent layer, the crystal size
as well as the content of silver chloride and silver bromide of the
lowly sensitive emulsion in this first layer may be varied. In
addition, the rate of development can be controlled by retarding
additives, e.g. phenylmercaptotetrazole. By these measures it is
possible to adjust the development kinetics of both layers in such a
manner that a positive silver image is formed which, in the dye
bleaching, produces a colour image with good white, the desired
contrast, and high maximum density.
In the further process steps, the silver image is converted in
known manner in the dyestuff layer into a coloured counter-image.
Both the negative silver image of the second layer which contains
silver iodide and the positive si]ver ima~e oE ~h~ ~irst dyes~uEE
layer dlsappear during processillg, so ~hat, finally, otlly ~he colour
image produced by colour bleaching remains.
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Example 1: The following layers are coated in succession on a white-
. . _
opaque paper support coated with polyethylene:
(13 a gelatin layer (coating weight 2 g/m ) which contains 200 mg/m
of the magenta dye of the formula
S03H H03S
! . . 1
OH HO--~ ~-
N=N--~ ~-NHCO-~-NHCONH--~ ~--CONH--~ ~--N=N~
NH2 SO3H ~103S H2N
(I)
10 mg/m of colloidal silver, a low-sensitive monodisperse silver
bromide emulsion (250 mg of silver per m ; edge length of the cryst-
als 0.2 ~m) and, as developmént retarder, 0.2 mg/m2 of phenyl-
mercaptotetrazole,
(2) a silver iodobromide gelatin emulsion green-sensitised with a
symmetrical oxacarbocyanine (95 mole % of silver bromide, 5 mole % of
silver iodide; 0.2 g of silver/m ), and
(3) a gelatin protective layer (1.5 g/m ~.
The material is exposed with green light throu&h a step wedge nnd
processed at 30C as rolLowtl
1. Silver developing bath 1 1/2 mi.nutes
ethylenediamine tetraacetic acid,
tetrasodium ~salt 2 g/l
potass:ium carbonate 30 g/l
potassium metabisulfite 10 g/l
125~5~
- 1.3 -
sodium suliite, anhydrous 30 g/l
l.-phellyl-3-pyrazolidone 0.4 g/l
hydroquinone 6 g/l
benztriazole 0.6 g/l
potassium bromide 2.0 g/l
sodium thiosulfate, anhydrous 1 g/l
2. Washing 30 seconds
3. Bleaching bath 2 minutes
sulfuric acid 40 g/l
sodium m-nitrobenzenesulfonate 8 g/l
sodium bis(~-cyanoethyl)sulfo-
ethylphosphine 3 g/l
potassium iodide 6 g/l
2,3,6-trimethylquinoxaline 1.3 g/l
4. Washing 30 seconds
5. Fixing solution 2 minutes
ammonium thiosulfate 200 g/l
potassium metabisulfite 25 g/l
potassium hydroxide (85 %) 10 g/l
6. Washing 2 minutes
The magenta image obtnined is a counter-.image of the e~posurc wetlge.
Example 2: The following layers are applied to a white-opaque paper
support coated with polyethylene:
(1) A dyestuff layer containing per m :
..:
., , ~ . ,
lZ~
- 14 -
1 g of gelatin, 0.3 g of the dye of the formula
~ '=N\ ~ ;=N j ~ rI)
0.6 g of silver in the form of a lowly sensitive silver bromide emulsion
in which the edge length of the crystals is about 0.2 pm, and 0.2 mg
of red colloidal gold;
(2) a gelatin layer containing 1 g/m of gelatin and 0,5 g/m2 of finelydispersed 2,5-bis-(5-n-hexyloxycarbony1-2-methylpent-2-yl)-1,4-benzo-
quinone as bleaching inhibitor;
(3) a highly sensitive silver bromoiodide layer containing 2.5 g/m2
of gelatin, O.S g/m of silver and 5 mole % of iodide; and
(4) a gelatin protective layer containing 1 g/m of gelatin and 85
mg/m of l-amino-3-hydroxy-5-methylmorpholinium-triazine-tetra-
fluoroborate as hardener.
The material is exposed in an sensitometer and processed as described
in Example 1. The image obtained is a counter-image of the exposure
wedge, i.e. a negative blnck dye image Witll a maxlm~m density oE
2.0, a minimum density oE O.l.S flnd n contr~st oE 1.5 (measured between
20 % and 80 ~ of the maximum density).
Example 3: The following layers are coated on a transparent polyester
support:
1;;~5~5~
(1) a dyestuff layer containing 2.5 g/m of gelatin, 0.13 g/m of the
ye].low dye of the formula
(:[II) /OC?I.
N=N~ NIIC0-~ OC~3 O~tl
3 ~./ \.~'
~ 03K
200 mg/m of silver in the form of a low -sensitive, cubic-monodis-
perse silver bromide emulsion in which the edge length of the crystals
is 0.2 ~m, and 0.14 mg/m of red, colloidal gold;
2 2
(2) a gelati.n interlayer containing 1 g/m of gelatin and 0.5 g/m
of finely ~dispersed 2,5-bis-(5-n-hexyloxycarbonyl-2-methylpent-2-yl)-
1,4-benzoquinone as bleaching inhibitor; and
(3) a silver bromoiodide layer containing S mole % of iodide and
2 g/m2 of gelatin, 0.25 g/m2 of silver (as silver halide with an
iodide content of 5 mole %) and 1 g/m of the above bleaching
inhibitor;
(4) a gelatin protective layer according to Example 2.
The material is exposed in a sellsi~ome~r und pro.essed as deseribed
in Example l, to give a negative yellow dye image with a maximum
density of 0.8, a minimum density of 0.1 and a contrast of 0.5
(measured between 20 % and 80 % of the maximum density).
~2~
-- 16 -
1.xample 4: The following layers are coated on a transparent polyester
support:
(1) a dyestuff layer which contains 1.8 g/m of gelatin7 0.135 g/m2
of the cyan clye of the formula
~C~3 ~3~ /S03K
co i~ \il/ ~N/i~
1 !H ~ 1H ~
3 S03K ,_.
\
(IV) S2CH3
0.3 g/m of silver in the form of a low-sensitive, cubic-monodispersed
silver bromide emulsion in which the edge length of the crystals is
0.2 ~um, and 1 mg~m2 of colloidal silver sulfide;
(2) a silver bromoiodide layer which correspollds to layer(3)in
Example 3 and wherein the iodide ions are uniformly distributed in
the crystal, and
(3) a gelatin protective layer corresporldin~ to layer~4)ill ~xanlpl~ 2.
The materlal is exposed in a sells:itolmeter and processed as described
in Example 1, to give a negative cyan dye image with a maximum
density of 0.5, a minimum density of 0.02 and a contrast of 0.5.
Example 5: If a silver bromoiodide emulsion which contains the iodide
;.ons in the interior of the crystals is used in the material of
Example 4, then a contrast of 2~0 is obtained.
