HK1023821A - Homogeneous single-part photographic color developing concentrate and method of making - Google Patents

Description

Homogeneous single-package photographic color developing concentrates and their preparation

The present invention relates to a single-package homogeneous photographic color developing concentrate and a method for producing the same. These concentrates and methods are useful in the photographic field to provide color photographic images.

The basic process for obtaining useful color images from exposed color photographic silver halide materials involves several photochemical processing steps such as color development, silver bleaching, silver halide fixation and water washing, or dye image stabilization with a suitable photochemical composition.

In early photographic processing methods, photographic color developing compositions were used to process color photographic materials, such as color film and photographic paper, to produce the desired dye images. These compositions typically contain a color developer such as 4-amino-3-methyl-N- (2-methanesulfonamidoethyl) aniline, which acts as a reducing agent to react with a suitable coupler to form the desired dye. US-A-4892804 describes A commonly used colour developing composition which has achieved considerable commercial success in the photographic industry. Other known developer compositions are described in US-A-4876174, US-A-5354646 and US-A-5660974.

It is common practice to add a "make-up" solution to the color developing composition placed in the processing machine to replace the photochemicals that have been consumed during the reaction or carried away by the processing material. This compensation ensures uniformity of development and maximum stability of the color developer.

Color developing compositions are typically supplied in three or more "portion" packages (or solutions) which are mixed just prior to use. Multiple portion packaging is often required to separate the components and to maintain the chemical activity and solubility of the components, otherwise the properties deteriorate or react with each other when they are stored together with each other under alkaline conditions for extended periods of time. For example, a portion of the package may contain a color developer; another package may contain an agent that maintains the alkalinity of the mixed color developing composition; still another package may contain an optical brightener. When all packages are mixed with water, a uniform color developing composition is generally obtained for use as a working strength solution in a processing machine.

In industrial processes, it is desirable to reduce the number of packaging parts used to formulate color developing compositions, particularly to formulate compensation solutions. Numerous compositions are reported in the art, or are commercially available in the form of "ready-to-use" solutions, concentrates or dry preparations. The liquid concentrate need only be diluted with water to provide a working strength solution and the dry formulation need only be dissolved in water. For example, EP-A-0793141 describes ｃA two-part packaged color developing composition which can be supplied in solid or liquid form.

It is generally known that the concentration of various photochemicals used in photographic processing baths must be limited to a narrow range to produce optimum performance. The most severe solvent for such photographic processing is water. Most inorganic salts are readily soluble in water, while organic chemicals in the processing bath generally have the appropriate solubility in water at the desired operating concentrations.

However, water is beneficial because it is present in large quantities, but a major problem with formulating ready-to-use photographic compositions and concentrated photographic compositions is that of its large presence. As a result, the manufacturing, shipping and storage costs of such compositions have always increased. Typically, users of photochemical compositions always have access to water to mix or dilute the photochemicals, but this is impractical for a number of reasons. The exact composition of the photochemicals is not readily determinable by the general user, and manufacturers are not willing to provide their formulations for this purpose. Furthermore, even if such formulations are known, errors in mixing can lead to poor processing results.

For these reasons, the photofinishing industry has a tendency to provide photofinishing compositions (including color developing compositions) in a concentrated state, so that manufacturers and users do not have to spend money on using, transporting, and storing large amounts of water, and can employ small containers. Furthermore, there is a need in the industry to provide a composition that can be used up exactly in its container, without the need to mix the components (thus reducing the mixing error), such as is used in so-called "auto-compensating" film processing machines.

The industry has investigated the problem of using both concentrated solutions and solid mixtures (including powders and tablets). In most cases, the concentrate is convenient to use, but is expensive to package compared to powder. The powder can be obtained in high concentration. Not every photochemical composition can dry to a stable powder. Furthermore, the powders have the problems of dusting, the need for separate packaging and the cumbersome metering or mixing operations. And not all dry formulations are readily soluble in water.

Another concentrated form known in the art is ｃA chemical paste or chemical slurry, as described in EP-A-0204372 and EP-A-0800111. These formulations have other disadvantages, namely lack of homogeneity and slow dissolution of the solid components.

An unaesthetic bystander may believe that all of the commonly used "ingredients" used to make color-developing compositions can be readily mixed to form a single-package homogeneous composition. However, the phenomenon of mutual reaction and deterioration of the photochemical products is increased in the concentrated state, and the influence on the processed photographic material is disappointed by the deterioration of the image.

Certain color developing compositions are brought to the market in single-serve packaged formulations that overcome the major problems described above, but they require vigorous stirring or mixing prior to use due to the presence of precipitates (e.g., in a slurry) or due to multiple solvent phases. Such compositions are generally limited to small volumes. Furthermore, the presence of a precipitate or "mud-like deposit" may be unattractive to the user. Some users may not have the proper equipment to properly agitate the multi-phase composition.

Another small volume, ready-to-use color developing composition is described in US-A-5273865. These compositions are said to be free of bromides, hydroxylamines and benzyl alcohols, contain 4-8 hydroxyl polyol compounds, and are only suitable for rapid processing of photographic elements containing large amounts of silver bromide emulsion.

In the photographic industry, there is a continuing need for uniform, concentrated and stable single-package color developing compositions. Such compositions would reduce the cost of transporting and storing dilute solutions, eliminate the need to mix multiple components or agitate the multi-phase ingredients, and give the user a more attractive product. The present invention is directed to meeting this long-standing unresolved need.

The invention provides a single-package color developing concentrate advanced in the technical field, which is characterized in that the concentrate is uniform, has a pH value of 7-13, and comprises:

a) at least 0.06 mol/l of color developer in free base state,

b) at least 0.05 mol/l of an antioxidant for color developers,

c) the amount of water is controlled by the amount of water,

d) an organic solvent for a color developer in a free base state which is an inactive, water-miscible or water-soluble, hydroxyl group-containing linear organic solvent in a photographic process, having a molecular weight of 50 to 200, in a concentration such that the weight ratio of water to the solvent is from 15: 85 to 50: 50, and

e) a buffer miscible with the organic solvent.

The present invention also provides a chemical set for photographic processing, comprising:

a) the above-mentioned single-package color developing concentrate, and

b) one or more of the following compositions:

a composition for the bleaching of the surface of a photographic material,

a photographic bleaching/fixing composition comprising a mixture of a cationic polymer and a cationic polymer,

photographic fixing composition, and

a photo-stabilizing composition or a final rinse composition.

In addition, the present invention includes a method of forming an image in a photographic color silver halide element comprising contacting the above-described one-pack color developing concentrate at least four times diluted with a photographic color silver halide element. This color development step in the photographic processing method may be followed by desilvering the developed color silver halide elements, as well as any other useful photographic processing step known in the art.

Further, a method for producing the above homogeneous one-pack color developing concentrate, comprising:

A) mixing water, a color developer in the form of a sulfate salt, an antioxidant for the color developer, an alkali metal base providing alkali metal ions in a ratio to sulfate ions in the form of sulfate salts of at least a stoichiometric ratio, and a non-reactive, water-miscible or water-soluble, hydroxyl-containing, linear organic solvent in a photographic process, said solvent having a molecular weight of from 50 to 200, in a concentrate in a concentration such that the weight ratio of water to the solvent is from 15: 85 to 50: 50, to form a water-insoluble alkali metal sulfate in solution, and

B) the water-insoluble alkali metal sulfate is removed from the solution.

The one-package color developing concentrate and method of making the same have a number of advantages over currently available or known photochemical compositions. The concentrate contains minimal water and can be manufactured, transported and stored at a greatly reduced cost. Furthermore, it is a homogeneous composition, which means that it does not contain precipitates, sludge or multiple solvent phases. Thus, it is essentially a single phase composition for manufacture and storage and use. Without the need for vigorous agitation prior to use, can be metered into a photographic processing tank or bath immediately and conveniently, with little need for instructions, and with minimal chance of error. For example, the concentrate can be used in "self-compensating" film processing machines, where the processing composition is diluted and used as needed. Importantly, it provides a one-pack composition, thus eliminating the need to mix multiple components (liquid or solid).

The concentrates of the present invention and the resulting working strength color developing compositions have a much less odor than many conventional multi-pack color developing compositions. Furthermore, it is undesirable to have the chemical stability and pH of all of the chemicals required for color development (e.g., antioxidants and color developers) lost when formulated into a one-package composition, since it is known in the art that several such chemicals interact deleteriously with each other and are therefore typically divided into multiple packages for shipping and storage.

The uniformity described above has been successfully addressed because the presence of high concentrations of sulfate is known to be detrimental to the stability of the composition. Sulfate is likely to cause precipitation when trying to reduce water and add all of the desired photochemicals to a single package solution. Therefore, when the source of the problem is determined, a method for removing sulfate ions is found by adopting the advanced mixing sequence in the technical field. Sulfate ions are removed in the first step of the formulation process to produce a substantially clear solution that is ready to be formulated into a working strength solution or used as a compensation solution.

Sulfate ions are removed early in the formulation of the composition by precipitating them in the presence of an alkali metal base and a partially water-soluble or water-miscible, hydroxyl-containing, linear organic solvent. For its effectiveness and solubility, the solvent has a critical molecular weight of 50-200. The sulfate precipitate is easily removed before other photochemicals are added to the solution. Preferably, the resulting color developing concentrate is substantially free of sulfate ions (which means less than 0.005 moles/liter of sulfate ions).

The homogeneous, one-pack color developing concentrate of the present invention is prepared using the following strict sequence:

the first step is to make an aqueous solution of a suitable color developer. The color developer is usually present in the form of a sulfate. Other components of this solution may include an antioxidant for the color developer, a suitable number of alkali metal ions (at least in stoichiometric proportion to sulfate ions) provided by the alkali metal base, and an inactive water-miscible or water-soluble hydroxyl-containing organic solvent in the photographic process. The concentration of the solvent in the final concentrate is such that the weight ratio of water to organic solvent is from 15: 85 to 50: 50.

In this environment, especially at high alkalinity, alkali metal ions form with sulfate salts which precipitate in the presence of hydroxyl-containing organic solvents. The precipitated sulfate may then be conveniently removed by any suitable liquid/solid phase separation method, including filtration, centrifugation or decantation. If the antioxidant is a liquid organic compound, two phases may form and the precipitate is removed by discarding the aqueous phase.

The color developing concentrates of the present invention comprise one or more color developers known in the art in an oxidized state that will react with the dye-forming couplers in the material being processed. Such colour developers include, but are not limited to, aminophenols, p-phenylenediamines (especially N, N-dialkyl-p-phenylenediamines) and other compounds known in the art, for example as described in EP 0434097a1 and EP 0530921a 1. It is advantageous for the color developer to have one or more solubilizing groups as are well known in the art. More detailed materials of this class are reported in Research findings "Research Disclosure," publication No. 38957, 592-639 (1996, 9 months). This reference is hereinafter referred to as "research findings".

Preferred color developers include, but are not limited to, N-diethyl-p-phenylenediamine sulfate (Kodak color developer CD-2), 4-amino-3-methyl-N- (2-methanesulfonamidoethyl) aniline sulfate, 4- (N-ethyl-N-. beta. -hydroxyethylamino) -2-methylaniline sulfate (Kodok color developer CD-4), p-hydroxyethylethylaminoaniline sulfate, 4- (N-ethyl-N-2-methanesulfonamidoethyl) -2-methylphenylenediamine sesquisulfate (Kodok color developer CD-3), 4- (N-ethyl-N-2-methanesulfonamidoethyl) 2-methylphenylenediamine sesquisulfate, and those well known to those skilled in the art.

To protect the color developer from oxidation, one or more antioxidants are typically included in the present color developing compositions. Both inorganic and organic antioxidants can be used. A wide variety of useful antioxidants are known and include, but are not limited to, sulfites (e.g., sodium sulfite, potassium sulfite, sodium bisulfite, 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, nitroxide radicals, alcohols and oximes. 1, 4-cyclohexanediones are also suitable as antioxidants. Mixtures of antioxidant compounds of the same or different classes may also be used if desired.

Particularly suitable antioxidants are hydroxylamine derivatives as described, for example, in U.S. Pat. No. 4, 4,892,804, U.S. Pat. No. 3, 4,876,174, U.S. Pat. No. 3, 5,354,646, U.S. Pat. No. 3, 5,660,974 and U.S. Pat. No. 3, 5,646,327. Many of these antioxidants are monoalkyl and dialkyl hydroxylamines having one or more substituents on one or both of their alkyl groups. Particularly suitable alkyl substituents include sulfo, carboxyl, amino, sulfonamido, carboxamido, hydroxyl, and other solubilizing substituents.

More preferred classes of said hydroxylamine derivatives may be monoalkyl hydroxylamines or dialkyl hydroxylamines having one or more hydroxyl substituents on one or more of their alkyl groups, representative compounds of this class being described, for example, in US-A-5709982, having the structure I:wherein R is hydrogen, substituted with 1 to 10 carbon atomsOr an unsubstituted alkyl group, a substituted or unsubstituted hydroxyalkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 5 to 10 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 10 carbon atoms in the aromatic nucleus thereof.

X₁is-CR₂(OH)CHR₁-and X₂is-CHR₁CR₂(OH) -, wherein R₁And R₂Independently hydrogen, hydroxy, substituted or unsubstituted alkyl of 1 to 2 carbon atoms, substituted or unsubstituted hydroxyalkyl of 1 or 2 carbon atoms, or R₁And R₂Together represent the carbon atoms necessary to form a substituted or unsubstituted 5-to 8-membered saturated or unsaturated carbocyclic ring structure.

Y is a substituted or unsubstituted alkylene group containing at least 4 carbon atoms. Or Y is a substituted or unsubstituted divalent aliphatic radical having an even number of total in-chain carbon and oxygen atoms, provided that the aliphatic radical contains at least 4 carbon atoms in the chain.

Further, in structure I, m, n, and p are independently 0 or 1. Preferably, m and n are each 1 and p is 0.

Particular disubstituted 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 these antioxidants (organic or inorganic) are commercially available or are prepared using the materials and methods described in the references mentioned in the description of hydroxylamine.

Buffering agents are typically present in the color developing compositions of the present invention to produce or maintain the desired alkaline pH of 7 to 13, preferably 8 to 12. These buffers must be soluble in the organic solvents described herein and have pKa values of 9 to 13. Such useful buffers include, but are not limited to, carbonates, borates, tetraborates, glycinates, triethanolamine, diethanolamine, phosphates and hydroxybenzoates. Alkali metal carbonates (such as sodium carbonate, sodium bicarbonate and potassium carbonate) are preferred. Mixtures of buffers may be used if desired.

In addition to buffers, the use of one or more acids or bases can also raise or lower the pH to a desired value. It is particularly desirable to raise the pH by adding a base such as a hydroxide or potassium hydroxide.

An essential component of the color developing concentrate of the present invention is a linear organic solvent which is inactive, water-miscible or water-soluble in the photographic process and which dissolves the color developer in its free base state. These organic solvents may be used alone or in combination, and each preferably has a molecular weight of at least 50, preferably at least 100, usually 200 or less, preferably 150 or less, per molecule. Such preferred solvents typically contain 2 to 10 carbon atoms (preferably 2 to 6 carbon atoms, more preferably 4 to 6 carbon atoms) and may also contain at least two nitrogen or oxygen atoms, or at least one of each heteroatom. These organic solvents are substituted with at least one hydroxyl functional group, preferably at least two such groups. They are linear molecules, not cyclic molecules.

By "non-reactive in the photographic process" is meant that the organic solvent has substantially no positive or negative effect on the color development properties of the concentrate.

Useful organic solvents include, but are not limited to, glycols (e.g., ethylene glycol, diethylene glycol, and triethylene glycol), polyhydroxyamines (including polyalkanolamines), and alcohols (e.g., ethanol and benzyl alcohol). Glycols are preferred, with ethylene glycol, diethylene glycol and triethylene glycol being most preferred. Among alcohols, ethanol and benzyl alcohol are most preferred. The most preferred organic solvent is diethylene glycol.

The amount of water and organic solvent in the concentrate is carefully controlled to achieve the desired results and to ensure that a single phase homogeneous concentrate is obtained. If too much water is present, phase separation occurs. If too much organic solvent is present, buffers and other salts will precipitate.

The color developing concentrates of the present invention may also contain one or more other additives commonly used in color developing compositions, including alkali metal halides (such as potassium chloride, potassium bromide, sodium bromide, and sodium iodide), metal chelate compositions (such as polycarboxylic or aminopolycarboxylic acids or polyphosphonates with or without lithium, magnesium, or other minority cations), auxiliary developers (such as Phenidone-type compounds, particularly for black and white developing compositions), anti-fog agents, development accelerators, fluorescent whitening agents (such as triazinylstilbene compounds), wetting agents, fragrances, stain removers, surfactants, defoamers, and water-soluble or water-dispersible color formers, as will be readily understood by those skilled in the art [ see, for example, Research Disclosure ]. The amounts of such additives are also well known in the art. Representative color developing concentrates of the present invention are described in example 1 below.

Table I below shows the typical amounts and preferred amounts of the essential components of the color developing concentrates according to the invention, the preferred amounts being in parentheses. During color development, the true concentration will vary depending on the extracted chemicals in the composition, the make-up ratio, the water loss due to evaporation, and the concentrate carried over from the previous processing bath and into the next processing bath.

TABLE I

Composition of	Concentration of the concentrate
		Color developing agent	0.06-0.3mol/l(0.1-0.2mol/l)
Antioxidant agent	0.05-1mol/l(0.1-0.6mol/l)
		Water to organic solvent (weight ratio)	25∶75-50∶50(30∶70-40∶60)
Buffering agent	0.1-2mol/l(0.5-1.8mol/l)

The color developing concentrate of the present invention is used for color developing a color photographic silver halide element which has been imagewise exposed and which comprises a support and one or more silver halide emulsion layers containing developable silver halide emulsion particles. A wide variety of photographic elements (including color negative and color reversal films and photographic paper, color electrograms and prints) containing various types of emulsions can be processed using the present invention, and the types of such elements are well known in the art (see "findings"). In particular, the present invention is useful for processing color papers of all types of emulsions (such emulsions include so-called "high chloride" and "low chloride" type emulsions and so-called lamellar grain emulsions, the color developing solutions can also be used for processing color reversal films and color negatives.

The invention is particularly suitable for processing high chloride emulsions (more than 70 mol% chloride, especially more than 90 mol% chloride, based on the total silver) in colour photographic paper. Such color papers may contain any suitable amount of silver coated on one or more of the emulsion layers. In some embodiments, the invention is used to process low silver (i.e., less than 0.8 grams silver/meter)²) And (3) a component. The layers of the photographic element may contain any useful binder or carrier known in the art, including various gelatins and other colloidal substances.

Color development of imagewise exposed photographic silver halide elements by contacting them with a color developing composition made according to the present invention under suitable time and temperature conditions in suitable processing equipment to produce the desired photographic image. Other processing steps may then be carried out in a general manner, including, but not limited to, one or more development stop, bleaching, fixing, bleach/fixing, washing (rinsing), stabilizing and drying steps, arranged in a particularly desired sequence as is known in the art. Suitable processing steps, conditions and materials used are well known in various processing methods, including the usual processing method C-41 for processing color negative films, the processing method RA-4 for processing color photographic paper, and the processing method E-6 for processing color reversal films (see, for example, "findings").

The photographic element processed in the practice of the present invention may be a single layer color element or a multi-layer color element. Multilayer color elements typically comprise dye image-forming cells that are sensitive to each of the three main regions of the visible spectrum. Each unit may consist of a single emulsion layer or multiple emulsion layers sensitive to a given region of the spectrum. The layers of the element may be arranged in various orders as is known in the art. In another form, the emulsions sensitive to each of the three main regions of the spectrum may be disposed as a single, separate layer. The device may also comprise other conventional layers such as filter layers, intermediate layers, primer layers, top layers and others known to those skilled in the art. The magnetic back layer may be coated on the back of a conventional support.

The structure and composition of the components, as well as suitable methods of processing the various types of components, have been described in considerable detail in "research findings". Included in this description of the art are the applications for the various types of cyan, yellow and magenta couplers that may be used with the present invention, including pyrazolone and pyrazolotriazole magenta couplers. Furthermore, the present invention can be used to process color paper for a support of colored resin-coated paper, which is made of a conventional inner and outer sizing agent (including alkyl ketene dimer and higher fatty acid), a reinforcing agent, and other known paper additives and paints.

The colour developing concentrates according to the invention can also be used in the so-called redox amplification process described in US-A-5723268 and US-A-5702873.

Processing according to the present invention may be carried out using deep tanks that typically contain processing solutions. Alternatively, it may be performed using a processing system known in the art as a "small volume shallow tank" (or LVTT) having a rack and a tank, or having an automated tray apparatus. Such processing methods and apparatus are described, for example, in US-A-5436118 and the publications mentioned herein.

Color development is followed by a step of bleaching/fixing with a suitable silver bleach. Numerous bleaching agents are known in the art, including hydrogen peroxide and other peracid compounds, persulfates, periodates, and iron ion salts or complexes with polycarboxylic chelating ligands. Particularly useful chelating ligands include the usual polyaminopolycarboxylic acids (including those described in ethylenediaminetetraacetic acid and "findings", US-A-5582958 and US-A-5753423). Biodegradable chelating ligands are also desirable because of their reduced environmental impact. Suitable biodegradable chelating ligands include, but are not limited to, iminodiacetic acid or alkyl iminodiacetic acid (e.g. methyl iminodiacetic acid), ethylenediamine disuccinic acid and similar compounds as those described in EP-A-0532003, and ethylenediamine monosuccinic acid and similar compounds as those described in US-A-5691120.

The processing time and processing temperature for each processing step of the present invention are those commonly employed in the art. For example, color development is generally carried out at a temperature of 20 to 60 ℃. The total color development time can reach 40 minutes, and preferably 75-450 seconds. If color photographic paper is processed, the total time required for color development is somewhat shorter.

The color developing concentrates of the present invention can be formulated into working strength solutions or compensation solutions by appropriate dilution up to 12-fold. Usually, the dilution factor is 4-10 times, and water is used as a universal diluent. Dilution may be performed during or prior to processing.

In one embodiment of the present invention, the color developing concentrate is a chemical formulation in the form of a photo processing chemical kit that may include one or more other photofinishing compositions (dry or liquid) including, but not limited to, photobleaching compositions, photobleaching/fixing compositions, photofixing compositions, and photostabilizing or rinsing compositions. These additional compositions may be formulated as concentrates or working strength solutions, or provided in dry form (e.g., powder or tablets). Other processing compositions that may be included in such color photographic processing kits are reversal compositions, conditioning compositions, pre-bleaching compositions, acid-stopping compositions, and other compositions well known to those skilled in the photographic arts. The processing kit may also include various processing equipment, metering equipment, processing instructions, silver recovery equipment, and other common materials known to those skilled in the art.

The following examples are intended to illustrate the practice of the invention, but are not intended to limit the invention. Unless otherwise indicated, percentages refer to weight percent.

Example 1

Example 1: concentrated solution for color development of color photographic paper

A homogeneous color developing concentrate (about 100ml) of the present invention was prepared as follows.

Sodium hydroxide solution (50% solution, 4g) was added to a solution of 4- (N-ethyl-N-2-methanesulfonamidoethyl) -2-methylphenylenediamine sesquisulfate (CD-3, 6.8g) and diethylhydroxylamine (5.4g) in water (6 g). Because diethylhydroxylamine is an organic liquid, two phases will form. Diethylene glycol (50g) was then added with stirring and precipitation of sodium sulfate was observed. The precipitate was filtered off from the solution, washed with 20g of diethylene glycol and discarded.

The following components were then added to this single phase formulation.

TABLE II

Triethanolamine (85% solution)	3g
		Substituted triazinylstilbene optical brighteners	1.17g
Magnesium chloride (6H)2O)	0.16g
		Polystyrene sulfonate (VERSA TL-73, 30%, from National Starch)	1.7g
1-hydroxyethylidene-1, 1-diphosphonic acid (60% w/w solution, DEQUEST 2010) or DEQUEST 2066 sodium salt of diethylenetriamine phosphonite (Solutia Co.)	0.86g or 4ml
		Potassium chloride	1.1g
Potassium bromide	0.03g
		Potassium carbonate	52.6g
Lithium chloride	1.55g

After the addition of these components was complete, the mixture was stirred until a homogeneous solution was obtained. Filtering to remove slight turbid matter, and packaging with color developing concentrated solution. The concentrate is substantially free of sulfate ions.

Examples 2 and 3: color developing concentrated solution for color photographic paper

Example 1 was weighed except that diethylene glycol was replaced with ethylene glycol (example 2) or dipropylene glycol (example 3). In both cases, a homogeneous, one-pack color developing concentrate was obtained.

Example 4: preferred color developing concentrate for color photographic paper

This concentrate was prepared as in example 1, except that N, N' -bis (2, 3-dihydroxypropyl) hydroxylamine (50% solution, 5.4g) was used in place of diethylhydroxylamine. The resulting concentrate (about 100ml) was homogeneous and was not cloudy and free of sulfate ions.

Example 5: preparation of process-concentration color developing composition and processing of color photographic paper

The concentrate described in example 1 was diluted with 10 times of water to prepare a color developing composition for photographic processing.

This composition was then used to color develop an imagewise exposed sample of commercially available Kodak Ektacon Edge 5 color photographic paper using the following processing methods and conditions to obtain an acceptable color image:

color development at 38 ℃ for 45 seconds

Bleaching/fixing at 35 ℃ for 45 seconds

Washing (water) at 35 ℃ for 90 seconds

Bleaching/fixing was performed with a commercially available Ektacolor RA Bleach Fix nox NR.

Example 6: color developing concentrated solution for color negative film

A homogeneous color developing concentrate for processing a color negative was prepared as follows:

sodium hydroxide solution (50% solution, 2.5g) was added to a solution of kodak color developer CD-4(4.5g) and N, N' -bis (2, 3-dihydroxypropyl) hydroxylamine (1.0g, 50% solution) in water (3 g). Two phases are produced. Diethylene glycol (50g) was then added with stirring and precipitation of sodium sulfate was observed. The precipitate was filtered from the solution, washed with 20g of diethylene glycol and discarded.

The following components were then added to this single phase formulation:

TABLE III

Sodium metabisulfite	3.25g
		Diethylenetriamine pentaacetic acid pentasodium salt (40% solution)	8.25g
Potassium iodide	0.01g
		Potassium bromide	1.13g
Potassium carbonate (47% solution)	69.5g

After the addition of these components was complete, the mixture was stirred until a homogeneous solution was obtained. Filtering to remove light turbid substances, and packaging according to the color development concentrated solution. The concentrate is substantially free of sulfate ions.

Claims (15)

1. A one-pack color developing concentrate characterized in that it is homogeneous, has a pH of 7 to 13, and comprises:

a) at least 0.06 mol/l of color developer in free base state,

b) at least 0.05 mol/l of an antioxidant for a color developer,

c) the amount of water is controlled by the amount of water,

d) a water-miscible or water-soluble, hydroxy-substituted, linear organic solvent having a molecular weight of from 50 to 200, in a concentration such that the weight ratio of water to solvent is from 15: 85 to 50: 50, and

e) a buffer dissolved in an organic solvent.

2. The color developing concentrate according to claim 1, wherein the amount of the color developer is 0.06 to 0.3 mol/l, the amount of the antioxidant is 0.05 to 1 mol/l, and the weight ratio of water to the organic solvent is 30: 70 to 40: 60.

3. The color developing concentrate according to claim 1 or 2, wherein the antioxidant is represented by the following structure I:wherein R is hydrogen, alkyl, hydroxyalkyl, cycloalkyl or aryl, R₁And R₂Independently is hydrogen, hydroxy, alkyl or hydroxyalkyl, or R₁And R₂Together represent the carbon atoms necessary to form a 5-to 8-membered carbocyclic ring structure, X₁is-CR₂(OH)CHR₁-，X₂is-CHR₁CR₂(OH) -, and m, n and p are independently 0 or 1.

4. The color developing concentrate according to any one of claims 1 to 3, wherein the organic solvent is an aliphatic compound having a molecular weight of 100 to 200 and containing 2 to 10 carbon atoms.

5. The color developing concentrate according to any of claims 1-4, wherein the organic solvent is ethylene glycol, diethylene glycol, triethylene glycol, ethanol or benzyl alcohol.

6. The color developing concentrate according to any of claims 1 to 5 wherein the buffer is a carbonate.

7. The color developing concentrate according to any of claims 1 to 6, further comprising one or more of the following components:

e) the ions of the chloride are used as the ions,

f) the bromide ions are selected so as to be capable of,

g) a metal ion chelating composition for use in a metal ion chelating composition,

h) a triazine stilbene fluorescent whitening agent,

i) a polyalkanolamine, or

j) A fragrance.

8. A photographic processing chemical kit, comprising:

a) a one-pack color developing concentrate according to any one of claims 1 to 7, and

b) one or more of the following compositions:

a composition for the bleaching of the surface of a photographic material,

a photographic bleaching/fixing composition comprising a mixture of a cationic polymer and a cationic polymer,

a photographic fixing composition comprising a mixture of a photosensitive resin,

photographic stabilizing or final rinse compositions.

9. A process for forming an image in a photographic silver halide element comprising contacting a photographic silver halide material with a one-pack color developing concentrate of any one of claims 1 to 7 diluted at least 4 times.

10. A photographic processing method comprising the steps of:

A) color developing the imagewise exposed photographic color silver halide element with at least 4-fold dilution of a one-pack color developing concentrate according to any one of claims 1 to 7,

B) desilvering the color developed photographic color silver halide element.

11. A method of formulating a homogeneous, ready-to-use, sulfate-free, one-package color developing composition comprising the steps of:

A) mixing water, a colour developer in the form of a sulphate, an antioxidant for the colour developer, alkali metal ions in at least stoichiometric proportion to the sulphate, and a water-miscible or water-soluble, linear organic solvent having a molecular weight of 50-200 and a concentration such that the weight ratio of water to the solvent is from 15: 85 to 50: 50, thereby forming an alkali metal sulphate in solution, and

B) the alkali metal sulfate is removed from the solution.

12. The process of claim 11 wherein the alkali metal ion is provided as part of an alkali metal hydroxide.

13. The method of claim 11 or 12, further comprising the steps of:

C) adding to the solution one or more of the following components:

a buffering agent, a water-soluble polymer,

the ions of the chloride are used as the ions,

the bromide ions are selected so as to be capable of,

a metal ion chelating composition for use in a metal ion chelating composition,

a triazine stilbene fluorescent whitening agent,

a polyalkanolamine, or

A fragrance.

14. A process according to any one of claims 11 to 13 wherein the antioxidant is represented by structure I:wherein R is hydrogen, alkyl, hydroxyalkyl, cycloalkyl or aryl, R₁And R₂Independently is hydrogen, hydroxy, alkyl or hydroxyalkyl, or R₁And R₂Together represent the carbon atoms necessary to form a 5-to 8-membered carbocyclic ring structure, X₁is-CR₂(OH)CHR₁-，X₂is-CHR₁CH (OH) -, and m, n and p are independently 0 or 1.

15. A one-pack color developing concentrate characterized in that it is homogeneous, substantially free of sulfate ions, has a pH of 7 to 13, and comprises:

a) at least 0.06 mol/l of color developer in free base state,

b) at least 0.05 mol/l of an antioxidant for a color developer,

c) the amount of water is controlled by the amount of water,

d) a water-miscible or water-soluble, hydroxy-substituted, linear organic solvent having a molecular weight of from 50 to 200, in a concentration such that the weight ratio of water to the solvent is from 15: 85 to 50: 50, and

e) a buffer dissolved in an organic solvent.