The present invention relates to method of photographic color paper
processing using low replenishment of the color developing solution. Replenishment
is carried out using a chloride ion-free, single-part, homogeneous photographic
color developing concentrate.
BACKGROUND OF THE INVENTION
The basic processes for obtaining useful color images from exposed
color photographic silver halide materials include several steps of photochemical
processing such as color development, silver bleaching, silver halide fixing (or
combined bleaching and fixing) and water washing or dye image stabilizing using
appropriate photochemical compositions.
Photographic color developing compositions are used to process color
photographic materials such as color photographic papers to provide the desired
dye images early in the photoprocessing method. Such compositions generally contain
color developing agents, for example 4-amino-3-methyl-N-(2-methane sulfonamidoethyl)aniline,
as reducing agents to react with suitable color forming couplers to form the desired
dyes. US-A-4,892,804 (Vincent et al) describes conventional color developing compositions
that have found considerable commercial success in the photographic industry. Other
known color developing compositions are described in US-A-4,876, 174 (Ishikawa
et al), US-A-5,354,646 (Kobayashi et al) and US-A-5,660,974 (Marrese et al).
It is common practice to add a "replenishing" solution to the color
developing composition in the processing machine in order to replace photochemicals
that are depleted during reaction or carried away by the processed materials. Such
replenishment insures uniform development and maximum stability of the color developing
Color developing compositions are commonly supplied in three or more
"parts" (or solutions) that are mixed immediately before use. Multiple parts are
often required in order to separate and preserve the chemical activity and solubility
of components that may otherwise deteriorate or react with each other when they
are stored together for long periods of time under alkaline conditions. For example,
one part might include a color developing agent, and another part might contain
agents to preserve the alkalinity of the mixed color developing composition. Still
another part may include an optical brightener. Upon combination of all parts and
water, a homogeneous color developing composition can usually be obtained for the
working strength solution in the processing machine.
There has been a desire in the industry to reduce the number of parts
used to prepare color developing compositions, including replenishing solutions.
A wide range of compositions are described in the art or commercially available
as "ready to use" solutions, concentrates or dry formulations. Liquid concentrates
have only to be diluted with water to provide a working strength solution. Dry
formulations need only be dissolved in water. For example, EP-A-0 793,141 (Chugai
Photo) describes a two-part color developing composition that can be supplied in
either solid or liquid form.
It is generally known that the concentrations of various photochemicals
used in a photographic processing bath must lie within certain narrow limits in
order to provide optimal performance. The most important solvent for such photoprocessing
is water. Most inorganic salts can be readily dissolved in water while the organic
photochemicals in such processing baths usually have suitable solubility in water
at the desired operating concentrations.
However, water is both an asset and a major problem of ready-to-use
and some concentrated photographic compositions because of its presence in high
quantity. As a result, the costs of manufacturing, transport and storage of such
compositions are steadily growing. Normally, the user of photochemical compositions
has water available in which individual photochemicals could be mixed or diluted,
but this is usually not practical for a number of reasons. The exact composition
of the photochemicals is not readily determined by a common user and manufacturers
are not likely to readily provide their formulations for such a purpose. Moreover,
even if the formulations are known, mixing mistakes may result in poor photoprocessing
For these reasons, there is a trend in the photographic industry to
provide photoprocessing compositions (including color developing compositions)
in concentrated form so that the manufacturer and user need not pay for use, transport
or storage of large volumes of water, and to enable use of smaller containers.
Moreover, there has been a desire in the industry to provide compositions that
can be used right out of their containers without the need for mixing various components
(thereby reducing mixing errors) in what are known as "automatic replenishing"
The industry has investigated the use of both concentrates and solid
mixtures (including powders and tablets). In most cases, concentrates are convenient
to use but may have high packaging costs compared to powders. Powders permit high
concentration, but not every photochemical composition can be dried into a stable
powder. In addition, powders present problems with dust, separate packaging needs
and more troublesome metering or mixing procedures. Not all dry formulations are
readily dissolved in water.
Another concentrated form known in the art is a chemical paste or
slurry, as described for example in EP-A-0 204,372 (Chemco) and EP-A-0 800,111
(Fuji Photo). These formulations have other disadvantages, namely lack of homogeneity
and slow dissolution rate of solid components.
The casual observer might consider that all of the conventional "parts"
used to provide color developing compositions might be readily combined to form
a single-part homogeneous composition. This is not as easy as one may think. Interactions
among and deterioration of photochemicals are magnified in concentrated form, and
the resulting action on processed photographic materials may provide poor images.
Some color developing compositions are commercially available in
single-part formulations that overcome some of the noted problems, but because
of the presence of precipitates (such as in slurries) or multiple solvent phases,
they require vigorous agitation or mixing before use. Such compositions are generally
limited to small volumes. In addition, the presence of the precipitates or "sludge"
may be unattractive to users, and some users may not have suitable equipment for
proper agitation of multi-phase compositions.
Additional small volume, ready to use color developing compositions
are described in US-A-5,273,865 (Loiacono et al). These compositions are said to
be free of bromides, hydroxylamines and benzyl alcohol, to include a polyol compound
having 4 to 8 hydroxy groups, and to be useful for rapid access processing of photographic
elements having high silver bromide emulsions only.
An advance in the art is provided with a homogeneous, single-part
color developer concentrate described in EP Application 99 202525.4. This concentrate
avoids many of the problems evident with previous concentrates or multi-part color
developing compositions because of its homogeneity and ease of use.
A continuing need in the photographic industry is to reduce the replenishment
rate of photographic processing solutions so less solution is needed, and less
volume is discharged to the environment. "Replenishment" refers to the process
of adding or restoring the activity of a processing solution that has become too
"seasoned" from use. When the conventional multi-part color developing compositions
are replenished by a similar composition at a lower rate, usually the resulting
images are undesirable for one reason or another.
Because many commercial single-part color developing compositions
are not homogeneous, they are not readily useful for replenishment without sufficient
mixing or agitation to achieve desired homogeneity.
Thus, there is a continuing need in the industry to use single-part
color developing composition that is homogeneous, concentrated and stable, but
that can be replenished at a lower rate. Such compositions would reduce the cost
of shipping and storage of diluted solutions, avoid the need for mixing multiple
parts or agitation of multi-phase compositions, offer the user a more attractive
product, and reduce the discharge of waste to the environment. The present invention
is directed to meeting this long felt need.
SUMMARY OF THE INVENTION
This invention provides an advance in the art with a homogeneous,
single-part, chloride ion-free color developing concentrate having a pH of from
7 to 13, and comprising:
a) at least 0.06 mol/l of a color developing agent in free base form,
b) at least 0.05 mol/l of an antioxidant for the color developing agent,
d) a photographically inactive water-miscible or water-soluble hydroxy-containing,
straight-chain organic solvent for the color developing agent in free base form,
the organic solvent having a molecular weight of from 50 to 200 and being present
in the concentrate at a concentration such that the weight ratio of water to the
solvent is from 15:85 to 50:50, and
e) a buffering agent that is miscible in the organic solvent,
the color developing concentrate characterized as being free of chloride ions.
This invention also provides a photographic processing chemical kit
a) the homogeneous, single-part, chloride ion-free color developing concentrate
described above, and
b) one or more of the following compositions:
a photographic bleaching composition,
a photographic bleach/fixing composition,
a photographic fixing composition, and
a photographic stabilizing or final rinsing composition.
Further, this invention includes a method for providing an image in
a photographic silver halide color paper comprising contacting the color paper
with, upon dilution at least four times, the homogeneous, single-part, chloride
ion-free color developing concentrate described above. This color developing step
can be followed by desilvering the developed color paper, as well as any other
useful photoprocessing steps known in the art.
Still further, the invention provides a method for providing an image
in a photographic color paper comprising contacting the color paper with a color
developing composition, the color developing composition being prepared by diluting
the homogeneous, single-part, chloride ion-free color developing concentrate described
above at least four times, the color developing composition being replenished at
a rate of from 50 to 150 ml/m2 of processed color paper, using the same
color developing concentrate at the same dilution rate.
The single-part color developing concentrate of this invention offers
a number of advantages over the photochemical compositions currently available
or known. Besides the advantages of minimal water, resulting in considerable savings
in manufacturing, shipping and storage costs, it is a homogeneous composition,
meaning that it is free of precipitates, slurries or multiple solvent phases. It
does not require vigorous agitation prior to use, and can be immediately and readily
metered into a photographic processing tank or bath with minimal instruction or
possibility of mistake. Importantly, it provides a single-part composition so the
mixing of multiple parts, whether liquid or solid, is avoided.
In addition, the concentrate can be diluted and used as the replenisher
for the color developing compositions at generally low rates, i.e. from 50 to 150
ml/m2 of processed color paper. This cannot be readily accomplished
with known color developing compositions, whether they are single-part or multi-part.
For example, when conventional color developing compositions are replenished at
lower rates, certain sensitometric properties are adversely affected. One such
property is the blue shoulder density. In the present invention, the blue shoulder
density and photographic speed were both unexpectedly improved at low replenishment
rates. These results are achieved with the present invention, it is believed, because
of a combination of features in the composition, including the absence of chloride
ions in the replenishing stream. Generally, the only chloride ions in the seasoned
color developing composition are those that leach out of the processed color paper
or are introduced as contaminants.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graphical plot of blue shoulder density versus replenishment rate
for the experiments described in Example 2 below.
FIG. 2 is a graphical plot of photographic speed versus replenishment rate
for the experiments described in Example 2 below.
DETAILED DESCRIPTION OF THE INVENTION
The homogeneous, single-part, chloride ion-free color developing
concentrate of this invention is prepared using a critical sequence of steps and
the following components.
In the first step, an aqueous solution of a suitable color developing
agent is prepared. This color developing agent is generally in the form of a sulfate
salt. Other components of the solution can include an antioxidant for the color
developing agent, a suitable number of alkali metal ions (in an at least stoichiometric
proportion to the sulfate ions) provided by an alkali metal base, and a photographically
inactive water-miscible or water-soluble hydroxy-containing organic solvent. This
solvent is present in the final concentrate at a concentration such that the weight
ratio of water to the organic solvent is from 15:85 to 50:50, and preferably from
25:75 to 50:50.
In this environment, especially at high alkalinity, alkali metal ions
and sulfate ions form a sulfate salt that is precipitated in the presence of the
hydroxy-containing organic solvent. The precipitated sulfate salt can then be
readily removed using any suitable liquid/solid phase separation technique (including
filtration, centrifugation or decantation). If the antioxidant is a liquid organic
compound, two phases may be formed and the precipitate may be removed by discarding
the aqueous phase.
The color developing concentrates of this invention include one or
more color developing agents that are well known in the art that, in oxidized form,
will react with dye forming color couplers in the processed materials. Such color
developing agents include, but are not limited to, aminophenols, p-phenylenediamines
(especially N,N-dialkyl-p-phenylenediamines) and others which are well
known in the art, such as EP 0 434 097A1 (published June 26, 1991) and EP 0 530
921A1 (published March 10, 1993). It may be useful for the color developing agents
to have one or more water-solubilizing groups as are known in the art. Further
details of such materials are provided in Research Disclosure, publication
38957, pages 592-639 (September 1996). Research Disclosure is a publication
of Kenneth Mason Publications Ltd., Dudley House, 12 North Street, Emsworth, Hampshire
PO10 7DQ England. This reference will be referred to hereinafter as "Research
Preferred color developing agents include, but are not limited to,
N,N-diethyl p-phenylenediamine sulfate (KODAK Color Developing Agent CD-2),
4-amino-3-methyl-N-(2-methane sulfonamidoethyl)aniline sulfate, 4-(N-ethyl-N-β-hydroxyethylamino)-2-methylaniline
sulfate (KODAK Color Developing Agent CD-4), p-hydroxyethylethylaminoaniline
sulfate, 4-(N-ethyl-N-2-methanesulfonylaminoethyl)-2-methylphenylenediamine sesquisulfate
(KODAK Color Developing Agent CD-3), 4-(N-ethyl-N-2-methanesulfonylaminoethyl)-2-methylphenylenediamine
sesquisulfate, and others readily apparent to one skilled in the art.
In order to protect the color developing agents from oxidation, one
or more antioxidants are generally included in the color developing compositions.
Either inorganic or organic antioxidants can be used. Many classes of useful antioxidants
are known, including but not limited to, sulfites (such as sodium sulfite, potassium
sulfite, sodium bisulfite and potassium metabisulfite), hydroxylamine (and derivatives
thereof), hydrazines, hydrazides, amino acids, ascorbic acid (and derivatives thereof),
hydroxamic acids, aminoketones, mono- and polysaccharides, mono- and polyamines,
quaternary ammonium salts, nitroxy radicals, alcohols, and oximes. Also useful
as antioxidants are 1,4-cyclohexadiones as described in copending and commonly
assigned U.S. Serial No. 09/123,976 (filed July 29, 1998 by Qiao and McGarry).
Mixtures of compounds from the same or different classes of antioxidants can also
be used if desired.
Especially useful antioxidants are hydroxylamine derivatives as described
for example, in US-A-US-A-4,892,804, US-A-4,876,174, US-A-5,354,646, and US-A-5,660,974,
all noted above, and US-A-5,646,327 (Burns et al). Many of these antioxidants are
mono- and dialkylhydroxylamines having one or more substituents on one or both
alkyl groups. Particularly useful alkyl substituents include sulfo, carboxy, amino,
sulfonamido, carbonamido, hydroxy and other solubilizing substituents.
More preferably, the noted hydroxylamine derivatives can be mono-
or dialkylhydroxylamines having one or more hydroxy substituents on the one or
more alkyl groups. Representative compounds of this type are described for example
in US-A-5,709,982 (Marrese et al), as having the structure I:
wherein R is hydrogen, a substituted or unsubstituted alkyl group of 1 to 10 carbon
atoms, a substituted or unsubstituted hydroxyalkyl group of 1 to 10 carbon atoms,
a substituted or unsubstituted cycloalkyl group of 5 to 10 carbon atoms, or a
substituted or unsubstituted aryl group having 6 to 10 carbon atoms in the aromatic
X1 is -CR2(OH)CHR1- and X2 is -CHR1CR2(OH)-
wherein R1 and R2 are independently hydrogen, hydroxy, a
substituted or unsubstituted alkyl group or 1 or 2 carbon atoms, a substituted
or unsubstituted hydroxyalkyl group of 1 or 2 carbon atoms, or R1 and
R2 together represent the carbon atoms necessary to complete a substituted
or unsubstituted 5- to 8-membered saturated or unsaturated carbocyclic ring structure.
Y is a substituted or unsubstituted alkylene group having at least 4 carbon
atoms, and has an even number of carbon atoms, or Y is a substituted or unsubstituted
divalent aliphatic group having an even total number of carbon and oxygen atoms
in the chain, provided that the aliphatic group has a least 4 atoms in the chain.
Also in Structure I, m, n and p are independently 0 or 1. Preferably,
each of m and n is 1, and p is 0.
Specific di-substituted hydroxylamine antioxidants include, but are
not limited to: N,N-bis(2,3-dihydroxypropyl)hydroxylamine, N,N-bis(2-methyl-2,3-dihydroxypropyl)hydroxylamine
and N,N-bis(1-hydroxymethyl-2-hydroxy-3-phenylpropyl)hydroxylamine. The first
compound is preferred.
Many of the noted antioxidants (organic or inorganic) are either
commercially available or prepared using starting materials and procedures described
in the references noted above in describing hydroxylamines.
Buffering agents are generally present in the color developing compositions
of this invention to provide or maintain desired alkaline pH of from 7 to 13, and
preferably from 8 to 12. These buffering agents must be soluble in the organic
solvent described herein and have a pKa of from 9 to 13. Such useful buffering
agents include, but are not limited to, carbonates, borates, tetraborates, glycine
salts, triethanolamine, diethanolamine, phosphates and hydroxybenzoates. Alkali
metal carbonates (such as sodium carbonate, sodium bicarbonate and potassium carbonate)
are preferred. Mixtures of buffering agents can be used if desired.
In addition to buffering agents, pH can also be raised or lowered
to a desired value using one or more acids or bases. It may be particularly desirable
to raise the pH by adding a base, such as a hydroxide (for example sodium hydroxide
or potassium hydroxide).
An essential component of the color developing concentrates of this
invention is a photographically inactive, water-miscible or water-soluble, straight-chain
organic solvent that is capable of dissolving color developing agents in their
free base forms. Such organic solvents can be used singly or in combination, and
preferably each has a molecular weight of at least 50, and preferably at least
100, and generally 200 or less and preferably 150 or less. Such preferred solvents
generally have from 2 to 10 carbon atoms (preferably from 2 to 6 carbon atoms,
and more preferably from 4 to 6 carbon atoms), and can additionally contain at
least two nitrogen or oxygen atoms, or at least one of each heteroatom. The organic
solvents are substituted with at least one hydroxy functional group, and preferably
at least two of such groups. They are straight-chain molecules, not cyclic molecules.
By "photographically inactive" is meant that the organic solvents
provide no substantial positive or negative effect upon the color developing function
of the concentrate.
Useful organic solvents include, but are not limited to, polyols
including glycols (such as ethylene glycol, diethylene glycol and triethylene glycol),
polyhydroxyamines (including polyalcoholamines), and alcohols (such as ethanol
and benzyl alcohol). Glycols are preferred with ethylene glycol, diethylene glycol
and triethylene glycol being most preferred. Of the alcohols, ethanol and benzyl
alcohol are most preferred. The most preferred organic solvent is diethylene glycol.
The amounts of water and organic solvent in the concentrate are carefully
controlled to achieve all of the desired results and to insure a single phase homogeneous
concentrate. If there is too much water, phase separation may occur. If there is
too much organic solvent, the buffering agent and other salts will precipitate.
The color developing concentrates of this invention can also include
one or more of a variety of other addenda that are commonly used in color developing
compositions, including alkali metal halides other than chlorides (such as potassium
bromide, sodium bromide and sodium iodide), metal sequestering compositions (such
as polycarboxylic or aminopolycarboxylic acids or polyphosphonates with or without
lithium, magnesium or other small cations), auxiliary co-developing agents (such
as phenidone type compounds particularly for black and white developing compositions),
antifoggants, alkanolamines, development accelerators, optical brighteners (such
as triazinylstilbene compounds), wetting agents, fragrances, stain reducing agents,
surfactants, defoaming agents, and water-soluble or water-dispersible color couplers,
as would be readily understood by one skilled in the art [see for example,
Research Disclosure, noted above]. The amounts of such additives are well
known in the art also. Representative color developing concentrates of this invention
are described below in Example 1.
It is essential that the concentrate of this invention include substantially
no chloride ions which means a concentration of chloride ions of less than 0.02
mol/l. The working strength color developing composition prepared from this concentrate
initially also contains substantially no chloride ions, but as it becomes seasoned
with use, chloride ions leach out of the processed color paper. In addition, low
amounts of chloride ions may be present as contaminants with other photoprocessing
chemicals in the composition. No chloride ions are purposely added to the concentrate
or the working strength composition. Replenishment of the color developing composition
using the concentrate (with or without dilution), however, keeps the working strength
chloride ion concentration relatively low.
The following TABLE I shows the general and preferred amounts of
essential components of the color developing concentrates of this invention. The
preferred ranges are listed in parentheses ( ). During color development, the actual
concentrations can vary depending upon extracted chemicals in the composition,
replenishment rates, water losses due to evaporation and carryover from any preceding
processing bath and carryover to the next processing bath.
The color developing concentrates of this invention have utility to
provide color development in an imagewise exposed photographic silver halide color
paper comprising a support and one or more silver halide emulsion layers containing
an imagewise distribution of developable silver halide emulsion grains. In particular,
the invention can be used to process color photographic papers of all types of
emulsions including so-called "high chloride" and "low chloride" type emulsions,
and so-called tabular grain emulsions as well.
The present invention is particularly useful to process high chloride
(greater than 70 mole % chloride and preferably greater than 90 mole % chloride,
based on total silver) emulsions in color photographic papers. Such color photographic
papers can have any useful amount of silver coated in the one or more emulsions
layers, and in some embodiments, low silver (that is, up to 0.8 g silver/m2)
elements are processed with the present invention. The layers of the color papers
can have any useful binder material or vehicle as it known in the art, including
various gelatins and other colloidal materials.
Color development of an imagewise exposed photographic silver halide
element is carried out by contacting the imagewise exposed color paper with a color
developing composition prepared according to this invention under suitable time
and temperature conditions, in suitable processing equipment, to produce the desired
developed image (i.e. color print). Additional processing steps can then be carried
out using conventional procedures, including but not limited to, one or more development
stop, bleaching, fixing, bleach/fixing, washing (or rinsing), stabilizing and drying
steps, in any particular desired order as would be known in the art. Useful processing
steps, conditions and materials useful therefor are well known for the various
processing protocols including the conventional Process RA-4 (see for example,
Research Disclosure, noted above). Digital scanning to modify or correct
the color image in any fashion can also be carried out in conjunction with the
method of the present invention.
The color papers processed in the practice of this invention can be
single or multilayer color elements. Multilayer color papers typically contain
dye image-forming units sensitive to each of the three primary regions of the visible
spectrum. Each unit can be comprised of a single emulsion layer or multiple emulsion
layers sensitive to a given region of the spectrum. The layers of the color paper
can be arranged in any of the various orders known in the art. In an alternative
format, the emulsions sensitive to each of the three primary regions of the spectrum
can be disposed as a single segmented layer. The color papers can also contain
other conventional layers such as filter layers, interlayers, subbing layers, overcoats
and other layers readily apparent to one skilled in the art.
Considerably more details of the element structure and components,
and suitable methods of processing various types of color papers are described
in Research Disclosure, noted above. Included within such teachings in the
art is the use of various classes of cyan, yellow and magenta color couplers that
can be used with the present invention (including pyrazolone and pyrazolotriazole
type magenta dye forming couplers). In addition, the present invention can be used
to process color photographic papers having pigmented resin-coated paper supports
which are prepared with the usual internal and external sizing agents (including
alkylketene dimers and higher fatty acids), strengthening agents and other known
paper additives and coatings.
The color developing concentrate of this invention can also be used
in what are known as redox amplification processes, as described for example, in
US-A-5,723,268 (Fyson) and US-A-5,702,873 (Twist).
Processing according to the present invention can be carried out
using conventional deep tanks holding processing solutions. Alternatively, it can
be carried out using what is known in the art as "low volume thin tank" processing
systems, or LVTT, which have either a rack and tank or automatic tray design.
Such processing methods and equipment are described, for example, in US-A-5,436,118
(Carli et al) and publications noted therein.
Color development is generally followed by bleaching and fixing steps
(or a combined bleach/fixing step) using a suitable silver bleaching and fixing
agents. Numerous bleaching agents are known in the art, including hydrogen peroxide
and other peracid compounds, persulfates, periodates and ferric ion salts or complexes
with polycarboxylic acid chelating ligands. Particularly useful chelating ligands
include conventional polyaminopolycarboxylic acids including ethylenediaminetetraacetic
acid and others described in Research Disclosure, noted above, US-A-5,582,958
(Buchanan et al) and US-A-5,753,423 (Buongiorne et al). Biodegradable chelating
ligands are also desirable because the impact on the environment is reduced. Useful
biodegradable chelating ligands include, but are not limited to, iminodiacetic
acid or an alkyliminodiacetic acid (such as methyliminodiacetic acid), ethylenediaminedisuccinic
acid and similar compounds as described in EP-A-0 532,003, and ethylenediamine
monosuccinic acid and similar compounds as described in US-A-5,691,120 (Wilson
et al). Conventional fixing agents, such a thiosulfate and thiocyanates, can be
used in the invention.
The processing time and temperature used for each processing step
of the present invention are generally those conventionally used in the art, but
even shorter "rapid processing" may be used in practicing the present invention.
For example, color development is generally carried out at a temperature of from
20 to 60 °C (preferably from 35 to 55 °C). The overall color development time
can be up to 4 minutes, and preferably from 75 to 450 seconds. Shorter overall
color development times are desired for processing color photographic papers in
the industry especially in what are known as minilabs. Such color development
times may be as short as 5 seconds and as high as 60 seconds. Overall processing
time (including color development, bleach-fixing and any rinsing steps) of color
papers using the present invention can be as long as 120 seconds, and as short
as 30 seconds, and preferably from 45 to 90 seconds.
The color developing concentrate of this invention can be formulated
into a working strength solution or replenisher by suitable dilution of up to 12
times. Generally, the dilution rate is from 4 to 10 times, using water as a common
diluent. Dilution can occur during or prior to processing.
Replenishment of the color developing composition is accomplished
by adding a diluted form of the concentrate to the working strength solution. Dilution
of the concentrate to form the replenishing solution is generally at the same rate
as that used to provide the working strength solution. The rate of replenishment
is generally from 50 to 150 ml/m2, and preferably from 70 to 120 ml/m2,
of processed color paper.
In one embodiment of this invention, the color developing concentrate
is one chemical formulation in a photographic processing chemical kit that can
include one or more other photographic processing compositions (dry or liquid)
including, but not limited to, a photographic bleaching composition, a photographic
bleach/fixing composition, a photographic fixing composition, and a photographic
stabilizing or rinsing composition. Such additional compositions can be formulated
in concentrated or working strength solutions, or provided in dry form (for example,
as a powder or tablet). Other processing compositions that can be included in such
kits for either black and white or color photographic processing are reversal compositions,
conditioning compositions, prebleach compositions, acidic stop compositions, and
others readily apparent to one skilled in the photographic art. The processing
kits can also include various processing equipment, metering devices, processing
instructions, silver recovery devices and other conventional materials as would
be readily apparent to one skilled in the art.
The following examples are provided to illustrate the practice of
this invention and not to limit it in any way. Unless otherwise indicated, percentages
are by weight.
Example 1: Color Paper Color Developing Concentrate
A color developing concentrate of this invention (about 100 ml) was
formulated in the following manner:
A solution of sodium hydroxide (50% solution, 4 g) was added to a
solution of 4-(N-ethyl-N-2-methanesulfonylaminoethyl)-2-methylphenylenediamine
sesquisulfate (CD-3, 6.8 g) and diethylhydroxylamine (5.4 g) in water (6 g). Because
diethylhydroxylamine is an organic liquid, two phases resulted. With stirring,
diethylene glycol (50 g) was then added, and a precipitate of sodium sulfate was
observed. This precipitate was filtered out of the solution, washed with 20 g of
diethylene glycol and discarded.
The following components were then added to the single-phase formulation:
Triethanolamine (85% solution)3 g Substituted triazinylstilbene optical brightener1.17 g DEQUEST 2066 diethylenetriaminepentaphosphonic acid, sodium
salt (Solutia Co.)5.2 g Potassium bromide0.025 g Potassium carbonate (47% solution)46 g pH12.1-12.45
After addition of these components, the mixture was stirred until
a homogeneous solution was obtained, filtered to remove a slight haze, and packaged
as a color developing concentrate. This concentrate was essentially free of all
sulfate and chloride ions.
Example 2: Preparation of Working Strength Color Developing Composition
and Processing of Color Paper
A color developing composition useful for photoprocessing was prepared
by diluting the concentrate described in Example 1 ten times with water. The use
of this composition was compared to the use of commercially available EKTACOLOR
Prime Color Developer, and the effects of replenishment rates were evaluated.
Each color developing composition was used for color development
in a commercially available Noritsu minilab processor during the processing of
imagewise exposed samples of commercially available KODAK EKTACOLOR EDGE 7 Color
Paper using the following processing protocol and conditions to obtain acceptable
Bleach/fixing in all tests was carried out using commercially available
EKTACOLOR RA Bleach Fix NR.
Typical replenishment rates for the color developing compositions
are 10-15 ml/ft2 (108-162 ml/m2) of processed conventional
color paper. The samples of color papers were used in the experiments to show the
effects of changing replenishment rate beyond the conventional range, and to show
that the present invention is less susceptible to variations. The color paper samples
were processed until the color developing composition had become "seasoned" at
a replenishment rate of 15 ml/ft2 (162 ml/m2). Both color
developing compositions were used to process the color paper samples at 3 and 4
tank turnovers to establish a baseline performance for the Blue shoulder density.
Blue shoulder density is the sensitometric parameter that is most sensitive to
reductions in replenishment rate.
Then, each color developing composition was replenished at a reduced
rate of 7 ml/ft2 (about 76 ml/m2). The color paper samples
were processed until the compositions had become "seasoned". Sensitometric check
strips for the color paper were also processed at 3 and 4 tank turnovers.
Analysis of the blue shoulder densities in the resulting color paper
images clearly indicated that a reduction of replenishment rate from 15 ml/ft2
(162 ml/m2) to 7 ml/ft2 (76 ml/m2) more adversely
affects the performance of the conventional color developing composition (Control)
than that of the composition of this invention (Invention). The data in the following
TABLE III clearly indicate that the blue shoulder density is substantially less
susceptible to reduction at lowered replenishment rates in the practice of the
present invention. The presented data is the change in blue shoulder density (ΔBlue
shoulder density) observed from the two replenishment rates. The closer the numbers
in TABLE III to zero, the more effective the color developing composition is at
lowered replenishment rates.
COLOR PAPER CONTROL INVENTION EKTACOLOR EDGE 7-0.50-0.35
In addition, FIGS. 1 and 2 show the increase in blue shoulder density
and photographic speed, respectively, achieved with the practice of the present
invention compared to the use of the Control color developing composition for processing
the color paper samples using various replenishment rates. In both FIGS. 1 and
2, curve 1 represents data from practice of the Invention, and curve 2 represents
data from use of the Control color developing composition.
A homogeneous, single-part, color developing concentrate having a pH of from
7 to 13 and comprising:
a) at least 0.06 mol/l of a color developing agent in free base form,
b) at least 0.05 mol/l of an antioxidant for the color developing agent,
d) a water-miscible or water-soluble hydroxy-substituted, straight-chain organic
solvent that has a molecular weight of from 50 to 200, and is present in the concentrate
at a concentration such that the weight ratio of water to said solvent is from
15:85 to 50:50, and
e) a buffering agent that is soluble in said organic solvent,
the color developing concentrate characterized as being free of chloride ions..
The color developing concentrate of claim 1 wherein the color developing agent
is present in an amount of from 0.06 to 0.3 mol/l, the antioxidant is present in
an amount of from 0.05 to 1 mol/l, and the weight ratio of water to the organic
solvent is from 25:75 to 40:60.
The color developing concentrate of claim 1 or 2 wherein the antioxidant is
a hydroxylamine derivative having a solubilizing group.
The color developing concentrate of claims 1 to 3 wherein the organic solvent
is an aliphatic compound having a molecular weight of from 100 to 200, and has
from 2 to 10 carbon atoms.
The color developing concentrate of claims 1 to 4 wherein the organic solvent
is an alcohol or glycol.
The color developing concentrate of claims 1 to 5 wherein the organic solvent
is ethylene glycol, diethylene glycol, triethylene glycol, ethanol or benzyl alcohol.
A method for providing an image in a photographic silver halide color paper
comprising contacting an imagewise exposed photographic silver halide color paper
with, upon dilution at least four times, the homogeneous, single-part color developing
concentrate of claims 1 to 6.
The method of claim 7 that is carried out for from 45 to 90 seconds.
The method of claim 7 or 8 wherein the homogeneous, single-part concentrate
is diluted with water to provide a replenishing solution that is used at a replenishment
rate of from 50 to 150 ml/m2 of processed color paper.
A photographic processing chemical kit comprising:
a) the single-part color developing concentrate of claims 1 to 6, and
b) one or more of the following compositions:
a photographic bleaching composition,
a photographic bleach/fixing composition,
a photographic fixing composition, or
a photographic stabilizing or final rinsing composition.