EP0007593B1 - Colour-photographic developing process - Google Patents

Description

The invention relates to a color photographic development process in which a color photographic material containing a hydrophobic cyan coupler and a hydrophilic yellow coupler is developed with a mixture of a hydrophobic and a hydrophilic color developer.

It is known to produce color photographic images by chromogenic development, i.e. by developing imagewise exposed silver halide emulsion layers in the presence of suitable color couplers by means of suitable color-forming developer substances - so-called color developers - the oxidation product of the developer substances resulting in accordance with the silver image reacting with the color coupler to form a dye image. Aromatic compounds containing primary amino groups, in particular those of the p-phenylenediamine type, are usually used as color developers.

In practice, a number of demands are placed on the color couplers and on the dyes obtained therefrom by chromogenic development. The coupling speed of the color couplers with the oxidation product of the color developer should be as high as possible. The color couplers and the dyes obtained from them must be sufficiently stable to light, elevated temperature and moisture.

This applies in particular to color photographic copying materials, such as photographic color papers, since the color images produced therefrom are often exposed to the end user for a relatively long time under the influence of light and, if appropriate, increased temperature and room humidity.

It has been found that, as a rule, the blue-green dyes produced by chromogenic development show poor resistance to the action of light if the underlying blue-green couplers belong to the class of naphthol derivatives. In contrast, dyes from cyan couplers based on phenol are sufficiently lightfast. However, it has been found that the dyes formed from these couplers are generally particularly susceptible to tropical conditions if the couplers are water- or alkali-soluble and, consequently, without the use of hydrophobic coupler solvents, so-called oil formers, in the casting solutions for the red-sensitive silver halide emulsion layer or in adjacent, non-light-sensitive binder layer have been incorporated. When storing under tropical conditions, a more or less pronounced decrease in the original maximum cyan color density is then often observed. In this regard, the cyan dyes behave somewhat more favorably if the hydrophobic oil formers mentioned are used to incorporate the underlying color couplers.

As is known, in particular the hydrophobic couplers from organic solutions are expediently incorporated into the casting solution for the photographic layers in the presence of high-boiling solvents which are immiscible or only miscible with water. This gives an emulsifier of fine droplets of a solution of the coupler in the oily coupler solvent, in which the coupler is distributed, as it were, protected by an oily shell in the hydrophilic binder.

In order to achieve the highest possible color density from a hydrophobic cyan coupler emulsified in this way during development, it is essential to use a color developer compound which, at least in the oxidized form, can easily penetrate into the hydrophobic oil droplets. Hydrophobic color developer compounds are particularly suitable for this. However, in order to achieve sufficient color density in the other color coupler-containing layers when using hydrophobic color developer compounds, the corresponding color couplers should also be emulsified in hydrophobic form. The hydrophobic or in hydrophobic emulsified form yellow couplers now often have the disadvantage that the dye formation during development proceeds more slowly than with a hydrophilic yellow coupler with a hydrophilic developer substance, especially when the yellow developing layer is at the bottom of the layer package. In this regard, they are superior to hydrophilic yellow couplers, which, however, do not give the desired high color density with the hydrophobic color developer substances and often form dyes whose light fastness is unsatisfactory.

The use of color couplers emulsified in hydrophobic form in addition to water- or alkali-soluble color couplers in the same material, possibly even in the same layer, is known per se (for example DE-A-1 962 606, DE-B-1 547 816, GB- A-1 107 453, US-A-3 515 557). This is used, for example, to adapt the reactivity of different color couplers to one another. As stated above, the color developer substance used for the development of such materials does not lead equally to the desired high maximum color density in hydrophobic and hydrophilic color couplers.

The use of a mixture of two different color developer substances is also known (DE-C-954311). With such a developer combination, an increase in sensitivity, i.e. a higher utilization of the latent image can be achieved. However, it was not to be expected that the disadvantages described, such as, in particular, inadequate stability of the image dyes produced against light or tropical conditions, would be eliminated.

The invention has for its object a process for the chromogenic development of a color photographic material with at least three silver halide emulsion layers different Specify spectral sensitivity and color couplers assigned to them, at least one color coupler being hydrophobic and at least one further color coupler being hydrophilic, in which sufficiently high color densities are achieved both from hydrophobic and from hydrophilic color couplers. In particular, both a blue-green partial color image with good tropical resistance and a yellow partial color image with good lightfastness are to be obtained simultaneously in the chromogenic development.

The solution to the problem is that a developer composition is used for the chromogenic development of the material described, which contains both a hydrophobic and a hydrophilic color developer compound. Sufficiently high color densities are achieved both from the hydrophobic color couplers and from the hydrophilic color couplers. It has also been found that this method can simultaneously obtain both a blue-green partial color image with good tropical resistance and a yellow partial color image with good light fastness if the color photographic material is both a cyan coupler emulsified with a hydrophobic oil former and a hydrophilic one without the use of an oil former contains incorporated yellow coupler. A hydrophobic yellow coupler emulsified using a comparatively hydrophilic oil former also acts in the same way as a hydrophilic yellow coupler.

The color developer preparation used for development accordingly contains at least a first (hydrophilic) and a second (hydrophobic) color developer compound. The difference in hydrophilicity results in a different distribution of the color developer oxidation products in the two-phase system consisting of hydrophilic binder and hydrophobic oil former. The hydrophobic color developer compound (in oxidized form) penetrates the oil droplets of the coupler solvent much more easily and therefore reacts preferentially with the hydrophobic coupler, while the hydrophilic color developer compound remaining mainly in the aqueous phase mainly reacts with the hydrophilic coupler.

worin bedeuten

• R¹ Wasserstoff oder Methyl ;
• R² Alkyl, vorzugsweise mit 1 - 4 Kohlenstoffatomen ;
• R³ Alkyl, vorzugsweise mit 1 - 4 Kohlenstoffatomen, gegebenenfalls substituiert, beispielsweise'durch Alkoxy wie Methoxy, Ethoxy, Hydroxyl, Carboxyl, Sulfo oder Methylsulfonylamido.

Hydrophilic and hydrophobic color developer compounds according to the invention correspond to the general formula

in what mean

• R ^{1 is} hydrogen or methyl;
• R ^{2 is} alkyl, preferably having 1 to 4 carbon atoms;
• R ³ alkyl, preferably with 1-4 carbon atoms, optionally substituted, for example by alkoxy such as methoxy, ethoxy, hydroxyl, carboxyl, sulfo or methylsulfonylamido.

In the case of the first (hydrophilic) color developer compound, R ³ preferably denotes sulfoalkyl, carboxyalkyl or hydroxyalkyl and in the case of the second (hydrophobic) color developer compound R ³ preferably denotes alkoxyalkyl, alkyl or methylsufonamidoalkyl.

The characteristics "hydrophobic and" hydrophilic in the characterization of the color developer compounds are not to be understood in the absolute, but only in the relative sense, since there are naturally transitions between the extremes.

• Sulfoalkyl, Carboxyalkyl, Hydroxyalkyl, Alkoxyalkyl, Alkyl, Methylsulfonamidoalkyl,
• so nimmt bei jeweils unveränderter Bedeutung für R¹ und R² die Fähigkeit der entsprechenden Farbentwicklerverbindungen, im oxidierten Zustand mit hydrophilen Kupplern zu reagieren, mit fortlaufender Reihe ab, und sie Fähigkeit, mit hydrophob emulgierten Kupplern zu reagieren, mit fortlaufender Reihe zu. Zu den hydrophilen Kupplern zählen auch an sich hydrophobe Kuppler, die in hydrophilen Ölbildnern gelöst sind und so in der Schicht dispergiert werden. Für die Relation hydrophob-hydrophil bei der Charakterisierung der Farbentwicklerverbindungen im Sinne der Erfindung kommt es daher ausschließlich darauf an, daß zwei Farbentwicklerverbindungen verwendet werden, die in dem zweiphasigen System zu einer unterschiedlichen Verteilung der Entwickleroxidationsprodukte führen. So kann beispielsweise eine hydrophile Farbentwicklerverbindung, bei der R³ eine Sulfoalkylgruppe ist, mit einer hydrophoben Farbentwicklerverbindung kombiniert werden, bei der R³ eine Alkoxyalkylgruppe ist. Andererseits ist auch die Kombination R³ = Methylsulfonylamidoalkyl (hydrophob) und R³ = Hydroxyalkyl (hydrophil) denkbar. Naturgemäß wird ein umso günstigeres Ergebnis erreicht werden können, je hydrophiler die eine und je hydrophober die andere der beiden Farbentwickierverbindungen ist. Das Mengenverhältnis zwischen hydrophiler und hydrophoben Farbentwicklerverbindung kann innerhalb weiter Grenzen entsprechend den jeweiligen Erfordernissen variiert werden, z.B. zwischen 1:6 und 6:1 (Gewichtsteile). Je nach der Schichtanordnung, dem Reaktivitätsunterschied der Kuppler und der Differenz in der Hydrophilie der Farbentwicklerverbindungen kann der Fachmann das günstigste Mengenverhältnis durch einfachen Routinetest ermitteln.

For example, if the substituents R ^{3 are arranged} in the following row:

• Sulfoalkyl, carboxyalkyl, hydroxyalkyl, alkoxyalkyl, alkyl, methylsulfonamidoalkyl,
• thus, with the meaning of R ¹ and R ² unchanged in each case, the ability of the corresponding color developer compounds to react in the oxidized state with hydrophilic couplers decreases with an ongoing series, and their ability to react with hydrophobically emulsified couplers with an ongoing series. The hydrophilic couplers also include hydrophobic couplers per se, which are dissolved in hydrophilic oil formers and are thus dispersed in the layer. For the relation hydrophobic-hydrophilic in the characterization of the color developer compounds in the sense of the invention it is therefore only important that two color developer compounds are used which lead to a different distribution of the developer oxidation products in the two-phase system. For example, a hydrophilic color developer compound in which R ^{3 is} a sulfoalkyl group can be combined with a hydrophobic color developer compound in which R ^{3 is} an alkoxyalkyl group. On the other hand, the combination R ³ = methylsulfonylamidoalkyl (hydrophobic) and R ³ = hydroxyalkyl (hydrophilic) is also conceivable. Naturally, the more hydrophilic the one and the more hydrophobic the other of the two color developing compounds, the more favorable a result can be achieved. The quantitative ratio between hydrophilic and hydrophobic color developer compound can be varied within wide limits according to the respective requirements, for example between 1: 6 and 6: 1 (parts by weight). Depending on the layer arrangement, the reactivity difference of the couplers and the difference in the hydrophilicity of the color developer compounds, the person skilled in the art can do the cheapest Determine the quantity ratio using a simple routine test.

Oil formers for the purposes of the present invention are the known coupler solvents which are insoluble or only slightly soluble in water, which are sometimes referred to in the literature as crystalloid solvents and have been described, for example, in US Pat. Nos. 2,304,940 and 2,322,027. The oil formers can be hydrophobic or hydrophilic; at least in the neutral or acidic medium, they form their own second phase in addition to the hydrophilic binder phase. Hydrophilic oil formers are known from US Pat. Nos. 3,689,271, 3,764,336 and 3,765,897. These are high-boiling organic low-molecular compounds which can penetrate semipermeable membranes and which generally boil above 175 ° C. At room temperature, i.e. at 20 ° C, they are generally liquid or they melt at relatively low temperatures, i.e. at temperatures below 100 ° C. They are referred to as oil formers because they generally form oily or liquid solutions when mixed with couplers.

Coupler solvents are e.g. those compounds which have one or more polar groups or atoms, for example hydroxyl, carboxylic acid, amide or keto groups or halogen atoms. The dissolving effect on the couplers should be as high as possible, and of course the solvents should be inert towards the silver halide emulsion into which they are incorporated. Of course, if possible, they should also be colorless, stable to light, heat and moisture and should also be inert to the various development and treatment baths in which the color photographic material is developed. In addition, their volatility should be as low as possible. Occasionally, it turns out to be advantageous to use a mixture of two or more different oil formers to produce the coupler emulsate. This is particularly the case when the compounds are of higher melting point, since the mutual melting point depression promotes the formation of oily droplets.

• Ethylbenzylmalonat_; Phthalsäuredialkylester, wie z.B. Dimethylphthalat, Diethylphthalat, Dipropylphthalat, Dibutylphthalat, Di-n-amylphthalat und Diisoamylphthalat, Dibenzylphthalat, Butyl-o-methoxybenzoat, n-Hexylbenzoat, 1,3-Diacetoxybenzol, Phosphorsäuretriarylester, wie z.B. Triphenylphosphat, Trikresylphosphat, Tri-p-tert.-butylphosphat und Tri-o-phenyl-phenylphosphat, N-Butylacetanilid, Acetylmethyl-p-toluidin, Benzoylpiperidin, N-n-Amylphthalimid, N-n-Amylsuccinimid, Ethyl-N-phenylcarbamat, N,N-Dimethy-p-toluolsulfonamid, N,N-Dibutyl-p-toluolsulfonamid, N,N-Di-n-butylharnstoff, N,N'-Diethyl-N,N'-diphenylharnstoff, Benzophenon, 2,4-Dichlorbenzophenon, Acetophenon, Cyclohexanon, p-sek.-Amylbenzophenon, Methylisobutylketon, 1-Phenyl-1-hydroxy-n-heptan, Dibenzylessigsäure, Phenylethylessigsäure, β-Phenylpropionsäure, Undecylensäure, Octadecenylbernsteinsäure, Monobenzylsuccinat, p-sek.-Amylbenzoesäure, Mono-n-amylphthalat.

The high-boiling crystalloid solvents listed below have proven to be particularly suitable high-boiling coupler solvents, ie oil formers:

• Ethylbenzylmalonate _; Dialkyl phthalates, such as, for example, dimethyl phthalate, diethyl phthalate, dipropyl phthalate, dibutyl phthalate, di-n-amyl phthalate and diisoamyl phthalate, dibenzyl phthalate, butyl-o-methoxybenzoate, n-hexyl benzoate, 1,3-diacetoxybenzene, phosphoric acid triaryyl phosphate, such as triaryl phosphate, such as triarylesphosphate, tert-butyl phosphate and tri-o-phenyl-phenyl phosphate, N-butylacetanilide, acetylmethyl-p-toluidine, benzoylpiperidine, Nn-amylphthalimide, Nn-amylsuccinimide, ethyl-N-phenylcarbamate, N, N-dimethy-p-toluenesulfone , N-dibutyl-p-toluenesulfonamide, N, N-di-n-butylurea, N, N'-diethyl-N, N'-diphenylurea, benzophenone, 2,4-dichlorobenzophenone, acetophenone, cyclohexanone, p-sec. Amylbenzophenone, methyl isobutyl ketone, 1-phenyl-1-hydroxy-n-heptane, dibenzylacetic acid, phenylethylacetic acid, β-phenylpropionic acid, undecylenic acid, octadecenylsuccinic acid, monobenzyl succinate, p-sec.-amylbenzoic acid, mono-n-amine.

Oil formers which are used particularly frequently and which have also proven to be outstandingly suitable in the sense of the present invention are, for example, phosphoric acid triaryl esters, in particular tricresyl phosphate, and phthalic acid dialkyl esters, such as di-n-butyl phthalate. In addition, the list contains a whole series of compounds which, owing to the different functional groups, behave differently in terms of their affinity for the couplers to be dissolved and for the reagents of the various photographic treatment baths, in particular the developer oxidation product.

• A Trikresylphosphat,
• B Dibutylphthalat,
• c
  
• D
  
• E

As already mentioned, hydrophilic oil formers are in principle also suitable for the storage of hydrophobic color couplers. According to the invention, however, this is used at most in the case of purple and yellow couplers; Only hydrophobic oil formers are used for the storage of cyan couplers. An example of a number of oil formers of increasing hydrophilicity is given below:

• A tricresyl phosphate,
• B dibutyl phthalate,
• c
  
• D
  
• E

Since the distribution equilibrium of the color developer oxidation products also depends on the hydrophilicity of the oil former used, it is also possible to influence the coupling ability of the color couplers dissolved therein.

The photographic material to be developed according to the method of the invention contains at least three silver halide emulsion layers with different spectral sensitivity on a conventional layer support, which can be transparent but is preferably opaque. A non-diffusing color coupler is assigned to each of these three layers in order to produce a partial color image, the color of which is generally complementary to the color of the light, for which the assigned silver halide emulsion layer is predominantly sensitive. For example, the blue-sensitive silver halide emulsion layer is assigned a yellow coupler, the green-sensitive silver halide emulsion layer is a magenta coupler, and the red-sensitive silver halide emulsion layer is a cyan coupler.

“Associated” is understood to mean that the mutual arrangement of the silver halide emulsion layer and the color coupler is of such a type that an interaction between them is possible which allows an imagewise correspondence between the silver image formed and the imagewise distribution of the image dye produced in the chromogenic development Color couplers are embedded in the light-sensitive silver halide emulsion layer itself, but can also be contained in a non-light-sensitive neighboring layer, since the developer oxidation products generated during color development should only react with the assigned color coupler and should not diffuse into unassigned color coupler-containing layers if possible Photosensitive silver halide emulsion layers still contain separating layers, which may consist of pure binder or may contain substances distributed in a binder that can react with color developer oxidation products to form colorless substances. In a known manner, these can be white coupler compounds or non-diffusing hydroquinone derivatives.

The preferred hydrophilic binder in the process of the present invention is gelatin, but it can also be replaced in whole or in part by other natural or synthetic binders. In the two-phase system mentioned, the hydrophilic binder represents the hydrophilic phase.

The usual known color couplers come into question as color couplers. Teal couplers are, for example, derivatives of phenol which, in the 4-position, can react with oxidized color developers to give cyan indochinone dyes. Pyrazolone derivatives should be mentioned in particular as purple couplers, and derivatives of benzoylacetanilide or pivaloylacetanilide are generally used as yellow couplers. In this context, reference should be made to the publication "Color Coupler by W. Pelz in" Messages from the Research Laboratories of Agfa _" , Leverkusen / Munich, BD. 111, p. 111 (1961) and to the article by K. Venkataramon in" The Chemistry of Synthetic Dyes », Vol. 4, pp. 341-387 (197).

Hydrophobic color couplers are those that generally cannot be incorporated into the casting solutions for the photographic layers from aqueous alkaline solutions. Groups which render water or alkali soluble, in particular sulfo or carboxyl groups, are generally absent from the hydrophobic color couplers. Conversely, the hydrophilic color couplers normally contain at least one sulfo or carboxyl group which makes them soluble in aqueous alkali. Because of this latter property, the hydrophilic color couplers are sometimes referred to as "soluble couplers," in contrast to "insoluble or hydrophobic couplers.

According to the invention in its broadest aspect, the color photographic material to be developed contains at least one hydrophobic color coupler emulsified in droplets of a more or less hydrophobic oil former, and at least one hydrophilic color coupler, which may have been added to the layer in the form of an aqueous alkaline solution or in the form of a Emulsions in a hydrophilic oil former. Hydrophobic and hydrophilic color couplers can be contained in the same layer or in different layers. In the first case, both couplers can contribute to the generation of the same partial color image.

In a preferred embodiment of the invention, the cyan coupler is hydrophobic and the yellow coupler is hydrophilic. The magenta coupler can optionally be hydrophobic or hydrophilic or even be a combination of a hydrophilic magenta coupler with a magenta coupler emulsified in hydrophobic form.

example 1

A color photographic material with three gelatin-silver halide emulsion layers applied to an opaque substrate contains the coupler for producing the yellow image in the blue-sensitive underlayer, the coupler 2 for producing the purple image in the green-sensitized middle layer and the coupler 3 for producing the blue-green in the red-sensitized top layer Picture. Coupler and coupler3 are emulsified using the hydrophilic oil former E. The formulas of the couplers are given at the end of the examples.

The material is exposed behind a silver gray wedge and processed as follows: developer, 35 ° C, 2 min.

1 liter contains:

It is then treated with a bleach-fixing bath of a known type, washed and dried.

Example 2

The material of Example 1 is in the following developer at 35 ° C and 2 min. processed: 1 liter contains:

Example 3

The material is as described in Example 1. In contrast to this, coupler 3 is dissolved in dibutyl phthalate (hydrophobic) and this solution is dispersed in the top layer. The same procedure is followed with Kuppier4 (instead of Coupler 1) in the lower layer. The development is carried out as in Example 1.

Example 4

The material of Example 3 is processed as indicated in Example 2.

Example 5

• In 1 Liter sind enthalten :
  

The material is as described in Example 1. In contrast to this, coupler 3 is dissolved in dibutyl phthalate and this solution is dispersed in the top layer. Otherwise, the material has the structure described in Example 1. Development takes place with the following developer at 35 ° C and 2 min. :

• 1 liter contains:
  

Further processing as indicated in Example 1.

The wedge images obtained according to Examples 1 to 5 are evaluated as follows:

The maximum densities of the individual colors are determined. In addition, samples are kept for 7 days at 60 ° C. and 80% relative atmospheric humidity, after which the loss of color density at the initial density 1 is determined. Finally, samples for 5.10 ⁶ lux.h are exposed to daylight, after which the loss of color density at the initial density 1 is determined.

The result of these measurements is summarized in Table 1. It shows that the combination of a layer package with hydrophilic and hydrophobically incorporated couplers with a developer composition containing two developer substances, one of which preferably couples with hydrophilically incorporated and the other preferably with hydrophobically incorporated couplers, leads to an optimal solution.

Example 6

• In 1 Liter sind enthalten :
  

A color photographic material with the coupler 1 for producing the yellow image in the lower layer, with the coupler 2 dissolved in dibutyl phthalate and dispersed in the middle layer and with the coupler 3 dissolved in dibutyl phthalate and dispersed in the top layer is in the following developer 2 min. developed at 35 ° C:

• 1 liter contains:
  

It is then treated with a bleach-fixing bath of a known type, washed and dried.

Example 7

The material of Example 6 is developed in the following developer:

Weitere Verarbeitung wie unter Beispiel 6 angegeben.1 liter contains:

Further processing as indicated in Example 6.

Example 8

• 1 Liter enthält :
  

The material of Example 6 is developed in the following developer:

• 1 liter contains:
  

Further processing as indicated in examples.

The wedge images obtained according to Examples 6 to 8 are evaluated in the same way as the wedge images of Examples 1 to 5. The result of these measurements is summarized in Table 2. The table shows that an optimal result is obtained if a color photographic material with both hydrophilically and hydrophobically incorporated couplers is processed with a developer composition which contains two developer substances, one of which preferably reacts with hydrophilically incorporated couplers and the other preferably with hydrophobic embedded couplers reacted.

Examples of the individual coupler types are:

Claims (5)

1. Process for the chromogenic development of a colour photographic material having at least three silver halide emulsion layers of differing spectral sensitivities and non-diffusible colour couplers associated therewith, at least one of which colour couplers is hydrophobic and has been incorporated by means of a hydrophobic oil former in the appropriate layer containing a hydrophilic binder and at least one other of which colour couplers is hydrophilic and has been incorporated in the layer containing a hydrophilic binder without the aid of an oil former or is hydrophobic and has been incorporated in the layer containing a hydrophilic binder by means of a comparatively hydrophilic oil former, characterised in that chromogenic development is carried out using a developer composition containing a first and a second colour developer compound, both of which correspond to the formula

in which

R' denotes hydrogen or methyl

R² denotes alkyl and

R³ denotes sulphoalkyl, carboxyalkyl or hydroxyalkyl in the case of the first colour developer compound and alkoxyalkyl, alkyl or methylsulphonamidoalkyl in the case of the second colour developer compound.

2. Process according to claim 1, characterised in that at least one cyan coupler is hydrophobic and has been incorporated in the layer by means of a comparatively hydrophobic oil former and in that at least one yellow coupler is hydrophilic and has been incorporated in the layer without the aid of an oil former.

3. Process according to claim 1, characterised in that at least one cyan coupler is hydrophobic and has been incorporated in the layer with the aid of a comparatively hydrophobic oil former and in that at least one yellow coupler is hydrophobic and has been incorporated in the layer with the aid of a comparatively hydrophilic oil former.

4. Process according to claim 2 or 3, characterised in that a hydrophobic cyan coupler based on phenol is used.

5. Process according to claim 1, characterised in that the compound used as the first colour developer compound is N-butyl-N-w-sulphobutyl-p-phenylenediamine or 2-amino-5-(N-isopropyl-N-w-sulf- phobutylamino)-toluene and the compound used as the second colour developer compound is 2-amino-5-(N-ethyl-N-methylsulphonamido-ethylamino)-toluene.