EP0222271A2 - Heat-developing process and colour-photographic recording material therefor - Google Patents

Abstract

worin bedeuten:
R¹, R² Alkyl, Cycloalkyl, Aralkyl, Aryl oder Acyl; und
Z einen Rest zur Vervollständigung eines ge­sättigten heterocyclischen Ringes mit 5 bis 11 Ringgliedern. Compounds of the formula I are suitable as thermal development and diffusion promoting agents for the heat development process. With the compounds mentioned, higher color transfer densities can be achieved and / or the development time can be shortened.

in which mean:
R1, R2 alkyl, cycloalkyl, aralkyl, aryl or acyl; and
Z is a radical to complete a saturated heterocyclic ring with 5 to 11 ring members.

Description

The invention relates to a heat development process in which an imagewise exposed color photographic recording material which contains a binder layer with silver halide and at least one coloring compound on a common layer support in contact with an image receiving layer which is an integral part of the recording material or can be arranged on a separate layer support is subjected to the development of a heat treatment, at least one so-called thermal development and diffusion promoting agent being present.

It is known to produce colored images by heat treatment using suitable color photographic recording materials. Particularly suitable as color-imparting compounds are those which can be embedded in the layer of a photographic recording material in a non-diffusing form and which, as a result of the development, can release a diffusible dye (color releaser).

The particular suitability of such color releasers is based on the fact that the imagewise released dyes can be transferred to special image-receiving layers with the formation of a brilliant color image which is not overlaid with disruptive image silver or silver halide and accordingly does not require any aftertreatment. Combining the heat development process with the color diffusion process thus results in an advantageous rapid process for producing colored images. A suitable recording material for this is described, for example, in DE-A-32 15 485.

According to this publication, a recording material having a layer containing a combination of silver halide, silver benzotriazole, a color releasing agent and guanidine trichloroacetate (base donor) is exposed imagewise and then subjected to a heat treatment in contact with an image-receiving sheet, whereby the image-released dye is transferred to the image-receiving sheet . For the production of multi-colored images, several such combinations must be present, the silver halide in each of these combinations being sensitive to a different spectral range of the light and, according to its spectral sensitivity, containing a color releaser which releases a dye of a different color, usually a color that is complementary is the color of the light for which the silver halide in question has a predominant sensitivity. Such assignments can be arranged one above the other in different layers.

It is known to carry out the heat development process in the presence of suitable compounds, so-called melt-formers or "thermal solvents", as described, for example, in RESEARCH DISCLOSURE publications 15 027 (October 1976), 15 108 (November 1976), 17 029 (June 1978) or in DE-A-33 39 810, EP-AO 119 615 and EP-A-O 122 512. The compounds mentioned are generally solid under normal conditions, but are in molten form at the higher temperature of the heat treatment and, owing to their dipolar nature, form a medium which promotes the development processes. Most of the thermal solvents mentioned are compounds with a protic character. Although using the thermal solvents mentioned, the heat treatment is dry, i.e. can be carried out without moistening the recording materials or the image-receiving sheets, and in this case considerable results are achieved, it is desirable to further improve the process and in this way to shorten the required treatment time and / or to achieve higher color transfer densities.

worin bedeuten:
R¹, R² Alkyl, Cycloalkyl, Aralkyl, Aryl oder Acyl; und
Z einen Rest zur Vervollständigung eines ge­sättigten heterocyclischen Ringes mit 5 bis 11 Ringgliedern.The invention relates to a heat development process for producing colored images, in which an imagewise exposed color photographic recording material with at least one on a layer support arranged binder layer, which contains light-sensitive silver halide, optionally in combination with a substantially non-light-sensitive silver salt, and at least one non-diffusing coloring compound, which as a result of the development is able to release a diffusible dye, is developed by heat treatment in the presence of a thermal development and diffusion promoting agent , wherein the dye released imagewise from the non-diffusing coloring compound is transferred into an image-receiving layer which can be colored by diffusible dyes, characterized in that the thermal development and diffusion promoting agent corresponds to the following formula I:

in which mean:
R1, R2 alkyl, cycloalkyl, aralkyl, aryl or acyl; and
Z is a radical to complete a saturated heterocyclic ring with 5 to 11 ring members.

Another object of the invention is a color photographic recording material which is suitable for the heat development process and contains at least one thermal development and diffusion promoting agent of the type specified in at least one of its layers.

R1 and R2 can be the same or different. Together they have at least 2 carbon atoms and together not more than 20 carbon atoms, preferably not more than 8 carbon atoms.

An alkyl group represented by R 1 or R 2 can be unbranched or branched and optionally substituted and preferably contain 1 to 4 carbon atoms. Examples include methyl, ethyl, propyl, isopropyl, n-butyl, s-butyl, methoxymethyl, cyclohexylmethyl, hydroxyethyl. A cycloalkyl group represented by R¹ or R² is, for example, cyclohexyl. An aralkyl group represented by R1 and R2 is, for example, benzyl. An aryl group represented by R 1 and R 2 is, for example, phenyl, tolyl, methoxyphenyl, N-methyl-N-acetylamino-phenyl.

An acyl group represented by R 1 or R 2 can be derived from aliphatic or aromatic carboxylic or sulfonic acids or also from carbamic or sulfamic acids. Acetyl and methylsulfonyl are examples of this.

The radical represented by Z to complete a heterocyclic ring is in particular an alkylene group which contains at least 2 carbon atoms and preferably not more than 10 carbon atoms, the ring formed with the urea grouping preferably containing 5 to 7 ring members. Such an alkylene group can be unbranched or branched and optionally substituted by hydroxyl, cycloalkyl, aryl or heterocyclic groups.

worin bedeuten
R³, R⁴, R⁵ und R⁶ unabhängig voneinander Wasserstoff oder Alkyl mit bis zu 6 C-Atomen, bevorzugt Methyl oder Ethyl;
l und m 0, 1 oder 2, wobei jedoch l und m nicht gleichzeitig 0 sein können.Preferably Z is an alkylene group of the structure

in what mean
R³, R⁴, R⁵ and R⁶ independently of one another are hydrogen or alkyl having up to 6 C atoms, preferably methyl or ethyl;
l and m 0, 1 or 2, but l and m cannot be 0 at the same time.

The thermal development and diffusion promotion agents according to the invention (the acronym TEDM will be used for this below) act under the Be Conditions of heat development apparently as a solvating medium for the reactions taking place such as development of the silver halide or the organic silver salt under the influence of a reducing agent, release of the diffusible dyes from the coloring compounds and diffusion of the dyes into an image-receiving layer. Appropriate variation of the substituents R¹ to R⁶, in particular the substituents R¹ and R², allows the solvent properties of the TEDM according to the invention to be influenced in a targeted manner in the direction of a more hydrophilic or hydrophobic character.

Suitable examples of the thermal development and diffusion promoting agents (TDEM) according to the invention are listed below:

Particularly preferred examples of the TEDM according to the invention, such as the compounds 1 and 15, are, for example, in the literature under the chem. Acronym DMPU (= dimethyl-propylene-urea) or DMEU (= dimethyl-ethylene-urea) described cyclic N, N'-dialkyl-ureas.

For example, DMPU has recently proven itself as a solvent equivalent to HMPTA (= hexamethylphosphoric acid triamide) in organic chemistry. In addition, there is a very great advantage in the physiological harmlessness of cyclic ureas (for DMPU, for example, documented in Nachr. Chem. Techn. Lab. 33 (1985), No. 5, 396).

The accessibility of the cyclic ureas and their precursors is known. Some references are mentioned below.

Boon, Chem. Soc. 1947, 307, 315; US-A-2 422 400 (1944); Marstell, Frost, J. Amer. Chem. Soc. 72 [1950], 1032; U.S.-A-2,847,418 (1955); Hall, Schneider, J. Amer. Chem. Soc. 80 [1958], 6409, 6412; Kirkewool, Wright, J. Amer. Chem. Soc. 76 [1954] 1836, 1839); US-A-2,398,284 [1943]; US-A-2 373 136.

The TEDM of the aprotic type used according to the invention are preferably liquid under normal conditions (in this respect they differ from the thermal solvents known to date (= "thermal solvents"), which are solid at normal temperature) and can usually be directly undiluted or as aqueous because of their good water solubility Solutions are added to the casting solutions for the light-sensitive or non-light-sensitive layers. Water-insoluble TEDM can be introduced in dispersed form. Such disper gates can be disgate of the pure substances or also disgate of solutions of the pure substances in a high-boiling organic solvent (= oil former).

The amount used can be varied within a wide range; This depends, among other things, on whether the compounds are introduced distributed over several or all layers of the recording material according to the invention, or whether they are used in a concentrated manner only in a specific layer. The amount to be used per square meter also depends, of course, on the amount of binder used. The skilled worker can easily determine the appropriate concentration using simple routine tests. The concentration used can be between 2 and 100% by weight, based on the binder, but preferably in the range between 20 and 50% by weight. However, overdosing on TEDM usually leads to high color fog (Dmin).

A color photographic recording material suitable for carrying out the heat development process according to the invention contains, on a dimensionally stable support, at least one binder layer in which a light-sensitive silver halide, optionally in combination with an essentially non-light-sensitive silver salt and a non-diffusing coloring compound, which contains a diffusible dye due to heat development can deliver, and the color photographic recording material further contains in one of its layers one or more of the thermal development and diffusion promoting agents (TEDM) according to the invention.

An essential component of the heat-developable recording material of the present invention is the silver halide, which consists of silver chloride, silver bromide, silver iodide or mixtures thereof and can have a particle size between 0.01 and 2.0 μm, preferably between 0.1 and 1.0 μm. It can be in the form of an unsensitized silver halide or it can also be chemically and / or spectrally sensitized by suitable additives.

The amount of light-sensitive silver halide in the respective layer can be between 0.01 and 2.0 g per m 2, the actual amount of silver halide used due to its catalytic function (as exposed silver halide) in some embodiments mainly in the lower part of the range given emotional.

The essentially non-light-sensitive silver salt can be, for example, a silver salt which is comparatively stable to light, e.g. trade an organic silver salt. Suitable examples include the silver salts of aliphatic or aromatic carboxylic acids and the silver salts of nitrogen-containing heterocycles; also silver salts of organic mercapto compounds.

Preferred examples of silver salts of aliphatic carboxylic acids are silver behenate, silver stearate, silver oleate, silver laurate, silver caprate, silver myristate, Sil berpalmitate, silver maleate, silver fumarate, silver tartrate, silver furoate, silver linolate, silver adipate, silver sebacate, silver succinate, silver acetate or silver butyrate. The carboxylic acids on which these silver salts are based can be substituted, for example, by halogen atoms, hydroxyl groups or thioether groups.

Examples of silver salts of aromatic carboxylic acids and other compounds containing carboxyl groups include silver benzoate, silver 3,5-dihydroxybenzoate, silver o-methylbenzoate, silver m-methylbenzoate, silver p-methylbenzoate, silver 2,4-dichlorobenzoate, silver acetamidobenzoate, silver gallate , Silver tannate, silver phthalate, silver terephthalate, silver salicylate, silver phenylacetate, silver pyromellitate, silver salts of 3-carboxymethyl-4-methyl-4-thiazolin-2-thione or similar heterocyclic compounds. Ferene silver salts of organic mercaptans, e.g. the silver salts of 3-mercapto-4-phenyl-1,2,4-triazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptooxadiazole, mercaptotriazine, thioglycolic acid, furthermore the silver salts of dithiocarboxylic acids, e.g. the silver salt of dithioacetic acid.

The silver salts of compounds having an imino group are also suitable. Preferred examples include the silver salts of benzotriazole and its derivatives, for example silver salts of alkyl and / or halogen-substituted benzotriazoles, such as the silver salts of methylbenzotriazole, 5-chlorobenzotriazole, as well as the silver salts of 1,2,4-triazole, 1-H-tetrazole, carbazole, saccharin and silver salts of imidazole and its derivatives.

The application amount of essentially non-photosensitive silver salt according to the present invention in the respective layer is between 0.05 and 5 g per m². The substantially non-light-sensitive silver salt and the light-sensitive silver halide can be present side by side as separate particles or in a combined form, which can be produced, for example, by treating a substantially non-light-sensitive silver salt in the presence of halide ions, the surface of which Particles of the essentially non-photosensitive silver salt are formed by double conversion (conversion) of photosensitive centers from photosensitive silver halide. For this purpose, reference is made to US-A-3 457 075.

The essentially non-light-sensitive silver salt serves as a reservoir for metal ions, which are reduced to elemental silver when heat is developed in the presence of a reducing agent under the catalytic influence of the imagewise exposed silver halide and thereby serve as an oxidizing agent (for the reducing agent present).

Another essential constituent of the recording material according to the invention is a non-diffusing coloring compound which, as a result of a redox reaction taking place during development, is able to release a diffusible dye and which is referred to below as a color releasing agent.

The dye releasers used according to the invention can be a variety of connection types, all of which are distinguished by a link which is redox-dependent in terms of their bond strength and which links a dye residue to a carrier residue containing a ballast residue.

In this context, a summary of the subject area in Angew. Chem. Int. Ed. Engl. 22 (1983), 191-209, in which the most important of the known systems are described.

Redox-active color releasers of the formula have proven to be particularly advantageous
BALLAST - REDOX - DYE,
in what mean
BALLAST a ballast remnant
REDOX is a redox-active group, i.e. a group that can be oxidized or reduced under the conditions of alkaline development and, depending on whether it is in the oxidized or in the reduced state, is subject to different degrees to an elimination reaction, a nucleophilic displacement reaction, a hydrolysis or another cleavage reaction with the result that the rest of DYE is split off, and
DYE the rest of a diffusible dye, for example a yellow, purple or cyan dye, or the rest of a dye precursor.

Such residues are to be regarded as ballast residues which make it possible to store the color releasers according to the invention in a diffusion-resistant manner in the hydrophilic colloids usually used in photographic materials. Organic radicals which generally contain straight-chain or branched aliphatic groups with general 8 to 20 C atoms and optionally also carbocyclic or heterocyclic optionally aromatic groups are preferably suitable for this purpose. With the rest of the molecule, these radicals are either directly or indirectly, for example connected via one of the following groups: -NHCO-, -NHSO₂-, -NR-, where R is hydrogen or alkyl, -O- or -S-. In addition, the ballast residue also contain water-solubilizing groups, such as sulfo groups or carboxyl groups, which may also be in anionic form. Since the diffusion properties depend on the molecular size of the total compound used, it is sufficient in certain cases, for example if the total molecule used is large enough, to use shorter-chain residues as ballast residues.

Redox-active carrier residues of the BALLAST-REDOX structure and corresponding color releasers are known in a wide variety of embodiments. A detailed description can be omitted here with regard to the overview article in the app. Chem. Int. Ed. Engl. 22 (1983) 191-209.

For the sake of explanation only, a few examples of redox-active carrier residues are listed below, from which a dye residue is split off in accordance with an image-related oxidation or reduction:

The groups enclosed in brackets are functional groups of the dye residue and are separated together with this from the remaining part of the carrier residue. The functional group can are a substituent which can have a direct influence on the absorption and, if appropriate, complex formation properties of the released dye. On the other hand, the functional group can also be separated from the chromophore of the dye by an intermediate link or a link. Finally, the functional group together with the intermediate member may also be of importance for the diffusion and pickling behavior of the released dye. Suitable intermediate members are, for example, alkylene or arylene groups.

In principle, the residues of dyes of all classes of dyes are suitable as dye residues insofar as they are sufficiently diffusible to diffuse from the light-sensitive layer of the light-sensitive material into an image-receiving layer. For this purpose, the dye residues can be provided with one or more alkali-solubilizing groups. Suitable alkali-solubilizing groups include carboxyl groups, sulfo groups, sulfonamide groups and aromatic hydroxyl groups. Such alkali-solubilizing groups can already be pre-formed in the dye releasers or can only result from the cleavage of the dye residue from the carrier residue containing ballast groups. Suitable dyes include: azo dyes, azomethine dyes, anthraquinone dyes, phthalocyanine dyes, indigoid dyes, triphenylmethane dyes, including those dyes that are complexed or complexable with metal ions.

The residues of dye precursors are to be understood as the residues of those compounds which, in the course of photographic processing, in particular under the conditions of heat development, either by oxidation, by coupling, by complex formation or by exposure of an auxochromic group in a chromophoric system, for example by saponification, can be converted into dyes. Dye precursors in this sense can be leuco dyes, couplers or dyes that are converted into other dyes during processing. Unless a distinction is made between dye residues and the residues of dye precursors, the latter should also be understood below as dye residues.

Suitable color releasing agents are described, for example, in:
US-A-3 227 550, US-A-3 443 939, USA-A-3 443 940,
DE-A- 19 30 215, DE-A- 22 42 762, DE-A- 24 02 900,
DE-A- 24 06 664, DE-A- 25 05 248, DE-A- 25 43 902,
DE-A- 26 13 005, DE-A- 26 45 656, DE-A- 28 09 716,
DE-A-28 23 159, BE-A-861 241, EP-A- 0 004 399,
EP-A- 0 004 400, DE-A- 30 08 588, DE-A- 30 14 669,
GB-A-80 12 242.

In some embodiments of the heat development method according to the invention, the color releasers can be used as oxidizable or couplable color releasers, in other than reducible color releasers. Depending on whether the dye is released from the oxidized or from the reduced form of the color releasing agent, negative or positive illumination is obtained from the original when conventional negative-working silver halide emulsions are used. You can therefore create positive or negative images by selecting suitable color releasing systems.

Oxidizable color releasers which are particularly suitable for the heat-developable recording materials according to the invention are, for example, in DE-A-22 42 762, DE-A-25 05 248, DE-A-26 13 005, DE-A-26 45 656 and GB-A-80 12 242.

If the paint releaser can be oxidized, then it is itself a reducing agent which, directly or indirectly, with the participation of electron transfer agents (electron transfer agent, ETA) through the imagewise exposed silver halide or through the essentially non-photosensitive silver salt under the catalytic action of the imagewise exposed Silver halide is oxidized. This creates a pictorial differentiation in terms of the ability to release the diffusible dye. If, on the other hand, the paint releaser is reducible, then it is expediently used in combination with a reducing agent present in a limited amount, a so-called ten electron donor compound or an electron donor precursor compound, which in this case is contained in the same binder layer in addition to the color releaser, the light-sensitive silver halide and optionally the substantially non-light-sensitive silver salt. The use of electron transfer agents can also prove to be advantageous in the case of the use of reducible color releasers in combination with electron donor compounds.

worin bedeuten
R¹ Alkyl oder Aryl;
R² Alkyl, Aryl oder eine Gruppierung, die zusammen mit R³ einen ankondensierten Ring vervollständigt;
R³ Wasserstoff, Alkyl, Aryl, Hydroxyl, Halogen wie Chlor oder Brom, Amino, Alkylamino, Dialkylamino einschließlich cyclischer Aminogruppen (wie Pipe­ridino, Morpholino), Acylamino, Alkylthio, Alkoxy, Aroxy, Sulfo, oder eine Gruppierung, die zusammen mit R² einen ankondensierten Ring vervollständigt;
R⁴ Alkyl;
R⁵ Alkyl oder vorzugsweise Wasserstoff;
und wobei mindestens einer der Reste R¹ bis R⁴ einen Ballastrest enthält.A recording material according to the invention, which contains reducible color releasers of the following formula, is suitable, for example, for producing positive color images of positive originals (original) when using negative working silver halide emulsions:

in what mean
R1 alkyl or aryl;
R² is alkyl, aryl or a group which together with R³ completes a fused ring;
R³ is hydrogen, alkyl, aryl, hydroxyl, halogen such as chlorine or bromine, amino, alkylamino, dialkylamino including cyclic amino groups (such as piperidino, morpholino), acylamino, alkylthio, alkoxy, aroxy, sulfo, or a group which together with R² fused one Ring completed;
R⁴ alkyl;
R⁵ alkyl or preferably hydrogen;
and wherein at least one of the radicals R¹ to R⁴ contains a ballast radical.

Such reducible dye releasers and others which are also suitable in the context of the present invention are described, for example, in DE-A-28 09 716, EP-A-0 004 399, DE-A-30 08 588, DE-A-30 14 669.

The electron donor compound used in combination with a reducible color releasing agent also serves as a reducing agent for the silver halide, the essentially non-photosensitive silver salt and the color releasing agent. The fact that the essentially non-light-sensitive silver salt and the color releaser compete with each other to a certain extent in the oxidation of the electron donor compound, but the latter is in any case superior to the latter in the presence of exposed silver halide, the existing silver halide becomes determinant for that in accordance with a previous imagewise exposure Image areas, within which the color releaser is converted into its reduced form by the electron donor compound.

The electron donor compound, which is present in a limited amount, under the conditions of development, in the present case when the imagewise exposed color photographic material is heated in accordance with the extent of the exposure under the catalytic effect of the latent image nuclei produced by exposure in the silver halide by the essentially non-light-sensitive silver salt and that photosensitive silver halide oxidizes and is therefore no longer available for reaction with the color releaser. This creates an image-like distribution of unused electron donor compound.

Derivatives of hydroquinone, benzisoxazolone, p-aminophenol or ascorbic acid (e.g. ascorbyl palmitate) which have not or only little diffusing have been described as electron donor compounds (DE-A-28 09 716).

Further examples of electron donor compounds are known from DE-A-29 47 425, DE-A-30 06 268, DE-A-31 30 842, DE-A-31 44 037, DE-A-32 17 877, EP-A- 0 124 915 and Research Disclosure 24 305 (July 1984). It has been shown that the electron donor compounds mentioned also meet the requirements placed on them under the conditions of heat development and are therefore also suitable as electron donor compounds in the context of the present invention.

Particularly suitable are those electron donor compounds which are formed from the corresponding electron donor precursor compounds only under the conditions of heat development in the layer, i.e. Electron donor compounds that are only in a masked form in the recording material before development, in which they are practically ineffective. Under the conditions of heat development, the electron donor compounds, which are initially ineffective, are then converted into their effective form, for example by hydrolytically cleaving certain protective groups. In the present case, the electron donor precursor compounds mentioned are also understood as electron donor compounds.

The above-mentioned essential constituents of the recording material used in the process according to the invention, namely the light-sensitive silver halide, the possibly non-light-sensitive reducible silver salt and the color releaser, optionally in combination with an electron donor compound, are dispersed next to one another in a binder. These can be hydrophobic as well as hydrophilic binders, but the latter are preferred and gelatin is preferably used, but it can also be replaced in whole or in part by other natural or synthetic binders. For example, polyurethanes, optionally in a mixture with gelatin, have proven to be suitable binders, as described, for example, in German patent application P 35 30 156.2.

For the production of monochrome color images, the light-sensitive binder layer contains one or more color releasers associated with the light-sensitive silver halide and optionally the non-light-sensitive silver salt, from which dyes of a specific color are released. The overall resulting color can be obtained by mixing several dyes. In this way, it is also possible to produce black and white images by precisely coordinating the mixing of several color separators of different colors. To produce multicolored color images, the color photographic recording material used in the method according to the invention contains several, ie generally three, assignments of color releasers and silver halide sensitized in different ways, preferably the absorption range of the dye released from the color releaser and the range of the spectral sensitivity of the assigned Silver halide essentially coincides. The different assignments of color releaser and assigned silver halide can be accommodated in different binder layers of the color photographic recording material, preferably between these different binder layers there are separating layers made of a water-permeable binder, for example gelatin, which essentially have the function of separating the different assignments from one another and to counteract color distortion in this way. In such a case, this includes use in the method according to the invention The color photographic recording material includes, for example, a light-sensitive binder layer in which the silver halide contained therein is predominantly red-sensitive due to spectral sensitization, a further light-sensitive binder layer in which the silver halide contained therein is predominantly green-sensitive due to spectral sensitization, and a third light-sensitive binder layer in which the contained therein Silver halide is predominantly blue-sensitive due to its inherent sensitivity or due to spectral sensitization. The electron donor compounds also contained in the three light-sensitive layers may be the same or different.

Each of the above-mentioned assignments of light-sensitive silver halide, essentially non-light-sensitive silver salt (if present) and color releasers can also be used in the form of a so-called complex coacervate.

A complex coacervate is understood to mean a form of dispersion in which a mixture of the essential constituents is enclosed in a common covering made of a hardened binder. Such dispersions are also called packet emulsions. They are obtained through complex coacervation.

The term "complex coacervation" means the occurrence of two phases when mixing an aqueous solution of a polycationic colloid and a polyanionic colloid, a concentrated colloid phase (hereinafter referred to as a complex coacervate) and a dilute colloid phase (hereinafter referred to as an equilibrium solution) ) are formed due to an electrical interaction. The complex coacervate is separated from the equilibrium solution in the form of droplets and appears as a white turbidity. When complex coacervation is performed in the presence of a solid such as silver halide or fine oil droplets, it is generally believed that the complex coacervate includes the solid or the droplets inside colloidal particles. As a result, a dispersion of coacervate particles is obtained, in which the solid (in the present case the light-sensitive silver halide and optionally the essentially non-light-sensitive silver salt) and oily droplets of a solution of the organic constituents (in the present case the color releasing agent and optionally further auxiliaries) are included are. It is then hardened with a hardening agent so that the original shape of the particles is not destroyed in the following steps for producing the photographic recording material, such as producing the casting solution and coating. The dispersion is expediently cooled to a temperature of 25 ° C. or below, preferably 10 ° C. or below, before curing, whereby a good quality packet emulsion is obtained.

Methods for producing a packet emulsion in which a color-forming substance is incorporated by complex coacervation are described, for example, in US Pat. Nos. 3,276,869 and 3,396,026.

The use of packet emulsions makes it possible to combine several emulsion components of different spectral sensitivity, including the relevant color releasers, in a single binder layer, without losing the spectral assignment and thereby causing color falsification. This is possible because the degree of exposure of a particular silver halide particle becomes almost exclusively decisive for the degree of dye release from the color releaser which is in the same coacervate particle (package) as the silver halide. The use of packet emulsions thus enables the accommodation of a blue-sensitive, a green-sensitive and a red-sensitive silver halide emulsion with any additional, essentially non-light-sensitive silver salt and spectrally assigned color separators in the same binder layer, without fear of serious color falsification.

In addition to the constituents already mentioned, the color photographic recording material used in the method according to the invention can contain further constituents and auxiliary substances which are used, for example, for carrying out the heat treatment and the process taking place here Color transfer are beneficial. These further constituents or auxiliary substances can be contained in a light-sensitive layer or in a non-sensitive layer.

Such auxiliary substances are, for example, auxiliary developers. These auxiliary developers generally have developing properties for exposed silver halide; In the present case, they primarily have a beneficial effect on the reactions taking place between the exposed silver salt (= silver salt in the presence of exposed silver halide) and the reducing agent, the reducing agent being identical to the latter when using oxidizable color releasers, or in the case the use of reducible paint releasers in turn reacts with the paint releasers. Since these reactions consist mainly of electron transfer, the auxiliary developers are also referred to as electron transfer agents (ETA). Examples of suitable auxiliary developers include hydroquinone, pyrocatechol, pyrogallol, hydroxylamine, ascorbic acid, 1-phenyl-3-pyrazolinone and their derivatives. Since the auxiliary developers have a catalytic function, it is not necessary for them to be present in stoichiometric amounts. In general, it is sufficient if they are present in the layer in amounts of up to 1/2 mol per mol of color releaser. Familiarization with the The layer can be made, for example, from solutions in water-soluble solvents or in the form of aqueous dispersions obtained using oil formers.

Other auxiliaries are, for example, basic substances or compounds which are able to provide basic substances under the influence of the heat treatment. Sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, sodium acetate and organic bases, in particular amines such as trialkylamines, hydroxyalkylamines, piperidine, morpholine, dialkylaniline, p-toluidine, 2-picoline, guanidine and their salts, in particular salts with aliphatic carboxylic acids, are to be mentioned here, for example. By providing the basic substances, a suitable medium is created during the heat treatment in the light-sensitive layer and the adjacent layers in order to ensure the release of the diffusible dyes from the dye releasers and their transfer to the image-receiving sheet.

Other auxiliaries are, for example, compounds which are able to release water under the action of heat. In particular, inorganic salts containing water of crystallization come into question, for example Na₂SO₄.10H₂O, NH₄Fe (SO₂) ₂.12H₂O and also compounds of the sodium benzotriazolate type which crystallize as a complex with various amounts of water (up to 24 mol H₂O) and which are described in US Pat -4 418 139 are described.

The water released during heating favors the development and diffusion processes required for image formation.

According to the present invention, further essential auxiliary substances are the previously described TEDM. However, these compounds do not necessarily have to be present in the same layer which also contains the light-sensitive silver halide and the color splitter. Rather, it is sufficient if any binder layer which is in contact with the photosensitive layers during the heat treatment contains the TEDM mentioned in the required amount. When heated, the TEDM forms a suitable solubilizing medium that is conducive to the development and color diffusion processes in the layers that are involved in the development and color diffusion processes. The TEDM according to the invention can thus be contained in a light-sensitive layer which contains silver halide and a coloring compound, or in a non-light-sensitive binder layer or in several of the layers mentioned. It can also be contained in an image-receiving layer which is located on the same support as the light-sensitive layers and, together with them, forms part of an integral recording material. Furthermore, the TEDM can also be contained in an image-receiving layer of a separate image-receiving material, provided contact is only made with the light-sensitive layers of the heat-developable photographic recording material during the heat treatment.

Finally, the TEDM according to the invention can also be contained in dispersed form in an auxiliary sheet which is brought into contact with the light-sensitive recording material and is subjected to a heat treatment together with it. A corresponding method is described for example in German patent application P 35 23 361.3.

The TEDM according to the invention can also be used in combination with one or more of the so-called thermal solvents of the prior art, such as those described in DE-A-33 39 810, EP-A-0 119, without going beyond the scope of the invention 615 and EP-A-0 122 512.

The development of the imagewise exposed color photographic recording material according to the invention comprises the partial steps of silver halide development, generation of an imagewise distribution of diffusible dyes and diffusion transfer of this imagewise distribution into the image receiving layer. It is initiated by subjecting the exposed recording material to a heat treatment in which the photosensitive binder layer is brought to an elevated temperature, for example in the range from 80 to 250 ° C., for a period of about 0.5 to 300 s. As a result, suitable conditions for the development processes, including dye diffusion, are created in the recording material without the need to supply a liquid medium, for example in the form of a developer bath. During development, the Color-releasing, imagewise diffusible dyes are released and transferred to an image-receiving layer, which is either an integral part of the color photographic recording material according to the invention or is in contact with it at least during the development time. Image-wise silver development, dye release and color transfer take place synchronously in a one-step development process.

In addition, the color image formation with the color photographic recording material according to the invention can also be carried out in a two-step development process, silver halide development and dye release taking place in a first step, followed in a second step by color image transfer from the light-sensitive part to an image receiving part brought into contact with it, e.g. by heating to a temperature between 50 and 150 ° C., preferably to 70 to 90 ° C., in which case diffusion aids (solvents) can still be applied externally before the photosensitive part and the image receiving part are laminated.

The image-receiving layer can accordingly be arranged on the same layer support as the light-sensitive element (single sheet material) or on a separate layer support (two-sheet material). It consists essentially of a binding agent, the mordant for the determination of the non-diffusing color cleavage released diffusible dyes contains. Long-chain quaternary ammonium or phosphonium compounds are preferably used as mordants for anionic dyes, for example those as described in US Pat. Nos. 3,271,147 and 3,271,148.

Furthermore, certain metal salts and their hydroxides, which form poorly soluble compounds with the acid dyes, can also be used. Polymeric mordants should also be mentioned here, such as those described in DE-A-23 15 304, DE-A-26 31 521 or DE-A-29 41 818. The dye mordants are dispersed in the mordant layer in one of the usual hydrophilic binders, e.g. in gelatin, polyvinylpyrrolidone, completely or partially hydrolyzed cellulose esters. Of course, some binders can also act as mordants, e.g. Polymers of nitrogen-containing, optionally quaternary bases, such as, for example, of N-methyl-4-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, as described, for example, in US Pat. No. 2,484,430. Further usable binding agents are, for example, guanylhydrazone derivatives of alkyl vinyl ketone polymers, such as describe, for example, in US Pat. No. 2,882,156 or guanylhydrazone derivatives of acylstyrene polymers, as described, for example, in DE-A-20 09 498. In general, however, other binders, for example Add gelatin.

Provided that the image-receiving layer also after completion Development in layer contact with the light-sensitive element, there is usually an alkali-permeable, pigment-containing light-reflecting image layer between them, which serves as an optical separation between negative and positive and serves as an aesthetically pleasing background for the positive color image. If the image-receiving layer is arranged between the support and the photosensitive element and is separated from the latter by a pre-formed light-reflecting layer, either the support must be transparent so that the color transfer image produced can be viewed through it, or the photosensitive element together with the light-reflecting layer of the image-receiving layer are removed to expose the latter. However, the image-receiving layer can also be present as the uppermost layer in an integral color photographic recording material, in which case the exposure is expediently carried out through the transparent layer support.

example 1 Preparation of the silver salt emulsions Emulsion 1

34.0 g of AgNO₃, dissolved in 400 ml of 45 ° C warm water, were within 2 min to a 45 ° C warm solution of 4.0 g of gelatin in 2000 ml of water, which contained 26.0 g of benzotriazole (BTA), metered in with stirring. The mixture was then stirred for 5 minutes. With 5% Na₂CO₃ solution pH 5.0 was adjusted. The mixture was flocculated by adding 40 ml of a 10% polystyrene sulfonic acid solution, cooling to 25 ° C. and adding 10% sulfuric acid (up to pH 3.0 to 3.5) and then washing three times with 1000 ml of water each time. The flocculate was heated to 45 ° C, adjusted to pH 6.0 with 5% Na₂CO₃ solution, mixed with 10 ml of 1% aqueous phenol solution and brought to a final weight of 870 g by adding water.

Emulsion 2

102.0 g of AgNO₃ dissolved in 600 ml of water were metered in over 10 minutes to a 50 ° C. solution of 120.0 g of gelatin, 271.1 g of KBr and 4.98 g of KI in 6000 ml of H₂O. The mixture was then stirred at 50 ° C. for 20 minutes and then cooled to 35 ° C., 120 ml of a 10% strength polystyrene sulfonic acid solution were added dropwise and the mixture was then cooled to 20 ° C. The mixture was flocculated by adding 10% strength sulfuric acid (up to pH 3.0 to 3.5) and washed three times with 700 ml of water each time. The mixture was then heated to 40 ° C. and adjusted to pH 6.0 with 10% sodium hydroxide solution. Final weight 3510 g.

For spectral sensitization (green sensitization) parts of emulsion 2 (raw emulsion) were melted at 40 ° C, 4 x 10⁻⁴ mol green sensitizer (in methanolic solution or slurry) per mol Ag and digested in a closed vessel for about 70 min.

The following spectral sensitizer was used.

Green sensitizer:

Example 2 Manufacture of the Dispergate Dispersant 1 (paint releasing agent M-1)

50.0 g of color releasing agent M-1 was dissolved in 25 g of diethyl laurylamide and 150 ml of ethyl acetate and, in the presence of 2.6 g of sodium dodecylbenzenesulfonate, finely dispersed in 330 g of 10% aqueous gelatin solution; The auxiliary solvent was then removed in a vacuum apparatus using relaxed steam: Yield: 834 g of dispersant 1.

Dispersant 2 (auxiliary developer precursor compound)

62 g of auxiliary developer precursor compound were dissolved in 120 g of diethyl laurylamide and 150 ml of ethyl acetate and dispersed in 612 g of 10% aqueous gelatin solution in the presence of 3.5 g of sodium dodecylbenzenesulfonate; the auxiliary solvent was then removed as for dispersate 1. Yield: 997 g of dispersant 2.

The following connections were used:

Paint splitter M-1

Auxiliary developer forerunner

Example 3 Image receiving part A

• 1. Eine Beizschicht mit 2 g Polyurethanbeize aus 4,4'-­Diphenylmethandiisocyanat und N-Ethyldiethanolamin, quaterniert mit Epichlorhydrin gemäß DE-A-26 31 521, Beispiel 1, und 2 g Gelatine.
• 2. Eine Schicht aus 0,6 g Gelatine und 0,6 g Natrium­alginat, der ein Härtungsmittel zugesetzt war.

The image-receiving part of a photographic recording material for the color diffusion transfer process was produced in that the following layers were successively applied to barite paper as a layer support. The quantities given relate to 1 m².

• 1. A pickling layer with 2 g of polyurethane pickle from 4,4'-diphenylmethane diisocyanate and N-ethyldiethanolamine, quaternized with epichlorohydrin according to DE-A-26 31 521, Example 1, and 2 g of gelatin.
• 2. A layer of 0.6 g gelatin and 0.6 g sodium alginate to which a hardening agent was added.

Example 4

The photosensitive parts of non-inventive (comparison) and color photographic recording materials according to the invention for the color diffusion transfer process were produced as follows:

Sample 1 (according to the invention)

x = 9 bis 10
Triton X 100
Hersteller: Rohm + Haas Company, Philadelphia91.2 g of emulsion 1 are melted at 40 ° C. and mixed with 8.0 ml of 4% aqueous solution of Triton® 100 X.

x = 9 to 10
Triton X 100
Manufacturer: Rohm + Haas Company, Philadelphia

Then 34.4 g of dispersant 1 (color releasing agent M-1) and 13.4 g of dispersant 2 (auxiliary developer precursor compound) and 32.2 g of 20% gelatin, and 64.0 g of emulsion 2, green-sensitized, were added in succession and melted in succession . 6.4 g of guanidine trichloroacetate, dissolved in 60 ml of water, and 3.2 g of compound 15, dissolved in 7.2 g of water, were finally added. The solution was applied with a wet layer thickness of 50 μm to a layer support made of polyethylene terephthalate and covered with a 1% strength aqueous gelatin solution containing a hardening agent (wet layer thickness 60 μm) and dried.

Sample 2 (according to the invention)

Preparation as sample 1, but using 3.2 g of compound 1

Sample 3 comparison (not according to the invention)

Preparation as sample 1, but replacing compound 1 with 3.2 g of water.

Sample 4 comparison (not according to the invention)

V: = "thermal solvent" aus DE-A-33 39 810
(Typ Sulfamid, dipolar aprotisch)Preparation as sample 1, but with the replacement of compound 1 by 3.2 g of comparison compound V

V: = "thermal solvent" from DE-A-33 39 810
(Type sulfamide, dipolar aprotic)

Example 5

The samples prepared according to Example 4 were exposed for 5 s with a room lamp through a transparent yellow filter with a density of 1.25 at 1000 lux. The samples were then heated to 110 ° C for development (the development time is shown in the table below). The samples were then swollen in water for 10 s and laminated together with the image-receiving sheet (from Example 3) which had been swollen in water for 30-60 s and heated on a regulated heating bench at 75 ° C. for 2 min, then separated and then immediately dried. Sharp, brilliant color transfers were obtained on the image-receiving sheets; the Dmin and Dmax values are shown in Table 1.

Table 1 shows very clearly the strong action of the compounds according to the invention as development-accelerating substances.

The comparison of samples 1 and 2 with sample 4 shows a clearly improved Dmin / Dmax relation and thus a significantly higher photographic activity in relation to Dmax development (this corresponds to a significant increase in the relative photographic sensitivity) without Dmin increasing excessively .

The compounds of the dipolar aprotic type used according to the invention are thus clearly superior to the thermal solvents of the prior art by improved photographic properties.

Claims (8)

1. Heat development process for the production of colored images, in which an imagewise exposed color photographic recording material with at least one binder layer arranged on a support contains the light-sensitive silver halide, optionally in combination with a substantially non-light-sensitive silver salt, and at least one non-diffusing color-providing compound, which as As a result of the development, a diffusible dye can be released, is developed by heat treatment in the presence of a thermal development and diffusion promoting agent, the dye released imagewise from the non-diffusing color-imparting compound being transferred into an image-receiving layer which can be colored by diffusible dyes, characterized in that the thermal development - and diffusion aid corresponds to the following formula I:

in which mean:
R1, R2 alkyl, cycloalkyl, aralkyl, aryl or acyl; and
Z is a radical to complete a saturated heterocyclic ring with 5 to 11 ring members. 2. The method according to claim 1, characterized in that in the general formula Z is an alkylene group having at least 2 carbon atoms. 3. The method according to claim 1, characterized in that in the general formula Z represents an optionally branched alkylene group which forms a 5- to 7-membered ring with the urea grouping. 4. The process according to claim 1, characterized in that Z represents an alkylene group of the structure

stands in what mean
R³, R⁴, R⁵, R⁶ (independently of one another) are hydrogen or alkyl having up to 6 C atoms;
l and m 0, 1 or 2, but l and m cannot be 0 at the same time. 5. The method according to claim 1, characterized in that the thermal development and diffusion promoting agent is contained in the color photographic recording material and / or in a separate image receiving material which is in contact with the color photographic recording material during the heat treatment. 6. Color photographic recording material which can be developed by heat treatment and has at least one binder layer arranged on a support which contains light-sensitive silver halide, if appropriate in combination with an essentially non-light-sensitive silver salt, at least one non-diffusing coloring compound which, as a result of the development by heat treatment, can release a diffusible dye. and contains at least one thermal development and diffusion promotion agent, characterized in that the thermishce development and diffusion promotion agent corresponds to the following formula I:

in which mean:
R1, R2 alkyl, cycloalkyl, aralkyl, aryl or acyl; and
Z is an alkylene group with at least 2 carbon atoms. 7. Recording material according to claim 6, characterized in that it contains as a thermal development and diffusion promoting agent a compound of the formula given in claim 6, in which Z is an alkylene group of the structure

stands in what mean
R³, R⁴, R⁵ and R⁶ independently of one another are hydrogen or alkyl having up to 6 C atoms;
l and m 0, 1 or 2, but l and m cannot be 0 at the same time. 8. Recording material according to claim 6, characterized in that it contains N, N'-dimethylethylene urea or N, N'-dimethylpropyleneurea in at least one of its layers.