EP0050260B1 - Photographic material, process for its production and method for the production of photographic pictures - Google Patents

Description

The invention relates to a photographic material with a latent image stabilizer, a method for producing this material and a method for producing photographic images.

It is known that the latent image nuclei of exposed silver halide emulsions are not stable during storage. This phenomenon is described, for example, in "The Theory of the Photographic Process", 4th edition, Macmillan Publishing Co., New York, 1977, pages 167 ff.

The fading of the latent image is usually noticeable in that an exposed material that was stored before development is less sensitive than a material that was not stored after exposure. The reasons for the regression of the latent image have not yet been fully clarified, but it is believed that they are caused by substances in the emulsion, e.g. B. impurities or additives, which oxidize part of the silver that makes up the latent image. The regression of the latent image is extremely troublesome in practice, not only for the recording materials, which are usually stored in the exposed state for a long time before development, but also for copying materials if the latter are not developed immediately after exposure. Especially when processing roll copy materials, these are often only developed a few days after exposure.

It is known to add so-called latent image stabilizers to photographic silver halide emulsions to stabilize the latent image nuclei. Latent image stabilizers are described, for example, in German Offenlegungsschrift 2,827,937 and in British Patents 1,343,904, 1,412,294, 1,378,354, 1,386,630, 1453388 and in U.S. Patents 3,386,831 and 3,881,939.

An object of the invention is to achieve improved latent image stabilization.

worin bedeuten

It has now been found:

in what mean

The compounds to be used according to the invention are so-called Schiff bases. It is already known to add such compounds to photographic recording materials as masked developer substances. However, concentrations of the same order of magnitude as that of the silver halide used are naturally to be used. It is known from US-A-3,342,599 to use Schiff bases in an amount of preferably 0.5 to 2.5 moles per mole of silver halide as a development precursor in photographic recording materials. There is, however, absolutely no indication that the present invention as the compounds to be used at a concentration of up to 10- ² mol per mol of silver halide Latent image stabilizer act. It also follows from column 2, line 10, of US Pat. No. 3,342,599 that the compounds indicated only hydrolyze and are active at a pH above 9. Such a pH value does not exist in the usual time between exposure and development in conventional photographic recording materials. However, this period is exactly the one in which the added latent image stabilizers are intended to prevent the decline in the latent image. Thus, the compounds to be used according to the invention should have been expected to be ineffective as a latent image stabilizer. However, as is evident from the examples of the present application, this is not the case. From US Pat. Nos. 3,227,552, 3,227,550 and 3,243,294 it is also known to use Schiff bases as developers for the production of directly positive images. Again, there is no indication that the compounds to be used according to the invention can act as latent image stabilizers in the stated concentrations. From US Pat. No. 2,507,114 it is known to use Schiff bases which are substituted with a carboxyl or sulfonic acid group in photographic materials as developer. In this patent there is also no reference to the use according to the invention.

The compounds of the formula (1) listed in the following table (1) have proven to be particularly suitable.

The Schiff bases to be used in the manner according to the invention can be prepared by known methods by condensation of the corresponding aromatic aldehydes and p-phenylenediamine derivatives in the presence of an inert solvent. The oxidation-sensitive free p-phenylenediamines can be prepared by preparing the free base from the corresponding salt by adding sodium acetate to the reaction solution during the reaction.

The preparation of some compounds is described in detail below, the others are obtained in an analogous manner.

Establishing connection 2

53.2 g (0.25 mol) of 4-N, N-diethylamino-2-toluidine hydrochloride, 34 g of sodium acetate x 3H ₂ 0 and 25.3 ml of benzaldehyde are refluxed in 300 ml of toluene with stirring on a water separator, until the water separation is finished. After cooling, the precipitated salt is filtered off and the reaction solution is treated several times with bleaching earth and activated carbon. The solvent is then distilled off in vacuo and the residue is dissolved in ether. The ethereal solution is washed neutral with sodium hydrogen carbonate and water, treated with bleaching earth and aluminum oxide, dried and the ether is distilled off. Yield: 38 g of a dark brown oil.

Establishing connection 11

131.1 g of 4-N, N-diethylaminoaniline sulfate, 136.1 g of sodium acetate x 3 H ₂ O and 61 g of 2-hydroxybenzaldehyde are refluxed in 500 ml of benzene with stirring on a water separator until the water separation has ended . After cooling, the reaction product is filtered off and recrystallized twice from acetone. Yield: 94.3 g, melting point: 102-103 ° C.

The compounds to be used according to the invention are outstandingly suitable for increasing the stability of the latent image nuclei in light-sensitive photographic materials with at least one silver halide emulsion layer. The stability of the latent image nuclei is prolonged while preserving all the usual photographic properties, which of course are largely determined by the structure of the silver halide emulsion, even when the materials are stored: time at normal temperature or at elevated temperature in the heating cabinet is achieved excellently.

The compounds to be used according to the invention are added to the photographic material, in particular after the emulsion has been physically ripened. The derivatives are preferably added in dissolved form to the light-sensitive silver halide emulsion during or after chemical ripening or the finished casting solution. Lower aliphatic alcohols, tetrahydrofuran, acetone or mixtures thereof are particularly suitable as solvents. The concentration of the compounds in the photographic materials can vary within wide limits. It depends on the desired effect, the type of reproduction process and the structure of the photographic material.

Amounts of at most 10 to ² mol, in particular at most 10 to ³ mol, per mol of silver halide have proven to be suitable. Particularly preferred concentrations between 10 mg and 1000 mg per mole of silver are Halo _a enid.

The compounds to be used according to the invention can be used in conventional light-sensitive materials for stabilizing the latent image nuclei, which are suitable for the production of black and white images, for. B. Black and white recording or copying materials or reversal materials. Furthermore, color couplers can be contained in the material without affecting the stabilization.

These materials are primarily developable silver halide materials with common silver halide emulsions that give a negative image on development, including the reversal materials where the first development after fogging is followed by a second development.

The usual hydrophilic film-forming agents are suitable as protective colloid or binder for the silver halide emulsion layer, e.g. B. proteins, especially gelatin, alginic acid or their derivatives such as esters, amides or salts, cellulose derivatives such as carboxymethyl cellulose and cellulose sulfates, starch or their derivatives or hydrophilic synthetic binders such as polyvinyl alcohol, partially saponified polyvinyl acetate, polyvinyl pyrrolidone and others. In a mixture with the hydrophilic binders, the layers can also contain other synthetic binders in dissolved or dispersed form, such as homopolymers or copolymers of acrylic or methacrylic acid or their derivatives, such as esters, amides or nitriles, and also vinyl polymers, such as vinyl esters or vinyl ethers.

The usual substrates can be used for the materials according to the invention, e.g. B. carriers made of cellulose esters such as cellulose acetate or cellulose acetobutyrate, further polyester, in particular polyethylene terephthalate or polycarbonates, in particular based on bisphenylol propane. Also suitable are paper supports, which are optionally impermeable polyolefin layers, e.g. B. of polyethylene or polypropylene, can also contain supports made of glass or metal.

The usual silver halide emulsions are suitable for the present invention. As silver halide, these can contain silver chloride, silver bromide or mixtures thereof, possibly with a low content of silver iodide up to 10 Mo ¹ _- ofo.

The emulsions can also be chemically sensitized, e.g. B. by adding sulfur-containing compounds during chemical ripening, for example allyl isothiocyanate, allyl thiourea and sodium thiosulfate or by adding selenium compounds. Reducing agents, e.g. B. the tin compounds described in Belgian patents 493464 or 568 687, also polyamines such as diethylenetriamine or aminomethylsulfinic acid derivatives, e.g. B. according to Belgian patent 547 323 used. Precious metals or noble metal compounds such as gold, platinum, palladium, iridium, ruthenium or rhodium are also suitable as chemical sensitizers. It is also possible to sensitize the emulsions with polyalkylene oxide derivatives, e.g. B. with polyethylene oxide having a molecular weight between 1000 and 20,000, also with condensation products of alkylene oxides and alcohols, aliphatic carboxylic acids, aliphatic amines, aliphatic diamines and amides.

The emulsions can also be optically sensitized, e.g. B. with the usual polymethine dyes such as neutrocyanines, basic or acidic carbocyanines, rhodacyanines, hemicyanines, styryl dyes, oxonols and the like. Such sensitizers are described in the work of F. M. Hamer, "The Cyanine Dyes and related Compounds" (1964).

The materials can contain in combination with the further stabilizers to be used according to the invention, e.g. B. azaindenes, preferably tetra- or pentaazaindenes, especially those which are substituted with hydroxyl or amino groups. Such connections are described in the article by Birr, Z. wiss. Phot. 47, 2-58 (1952). Other suitable stabilizers are u. a. heterocyclic mercapto compounds, e.g. B. phenyl mercaptotetrazole, quaternary benzothiazole derivatives, benzotriazole and the like.

The layers of the photographic material can be hardened in the usual manner, for example with formaldehyde or halogen-substituted aldehydes which contain a carboxyl group, such as mucobromic acid, diketones, methanesulfonic acid esters, dialdehydes and the like. Furthermore, the photographic layers can be hardened with hardeners of the epoxy type, the heterocyclic ethylene imine or the acryloyl type. Furthermore, it is also possible to harden the layers in accordance with the process of German laid-open specification 2218009 in order to obtain photographic materials which are suitable for high-temperature processing. It is also possible to harden the photographic layers or the color photographic multilayer materials with hardeners of the diazine, triazine or 1,2-dihydroquinoline series. Examples of such hardeners are alkyl or arylsulfonyl group-containing diazine derivatives, derivatives of hydrogenated diazines or triazines, such as. B. 1,3,5-hexahydrotriazine, fluorine-substituted diazine derivatives, such as. B. fluoropyrimidine, esters of 2-substituted 1,2-dihydroquinoline or 1,2-dihydroisoquinoline-N-carboxylic acids. Also useful are vinyl sulfonic acid hardeners, carbodiimide or carbamoyl hardeners, such as. B. in German laid-open publications 2 263 602, 2 225 230 and 1 808 685, French patent 1 491 807, German patent 872 153 and DD-A-7218. Other useful hardeners are described, for example, in British Patent 1,268,550.

The present invention can be applied to both black and white and color photographic images. Colored photographic images can e.g. B. according to the known principle of chromogenic development in the presence of color couplers, which react with the oxidation product of coloring p-phenylenediamine developers to form dyes.

The color couplers can be added to the color developer, for example, according to the principle of the so-called development process. In a preferred embodiment, the photographic material itself contains the usual color couplers, which are usually incorporated into the silver halide layers. For example, the red-sensitive layer can contain a non-diffusing color coupler for producing the blue-green partial color image, generally a coupler of the phenol or α-naphthol type. The green-sensitive layer can contain, for example, at least one non-diffusing color coupler for producing the purple partial color image, color couplers of the 5-pyrazolone or imidazolone type usually being used. The blue-sensitive layer can contain, for example, a non-diffusing color coupler for generating the yellow partial color image, usually a color coupler with an open-chain ketomethylene grouping.

Color couplers of this type are known in large numbers and are described in a large number of patents. Examples include the publication "Color coupler" by W. Pelz in "Messages from the research laboratories of Agfa, Leverkusen / Munich", Volume 111 (1961), and K. Venkataraman in "The Chemistry of Synthetic Dyes", Vol. 4, 341 to 387, Academic Press, 1971.

The non-diffusing color couplers and coloring compounds are added to the light-sensitive silver halide emulsions or other casting solutions by customary known methods. If the compounds are soluble in water or alkali, they can be added to the emulsions in the form of aqueous solutions, optionally with the addition of water-miscible organic solvents such as ethanol, acetone or dimethylformamide. Insofar as the non-diffusing color couplers and coloring compounds are water- or alkali-insoluble compounds, they can be emulsified in a known manner, e.g. by a solution of these compounds in a low-boiling organic solvent directly with the silver halide emulsion or initially with an aqueous gelatin solution is mixed, after which the organic solvent is removed in a conventional manner. A gelatin emulsate of the respective compound thus obtained is then mixed with the silver halide emulsion. If necessary, so-called coupler solvents or oil formers are additionally used to emulsify such hydrophobic compounds; these are generally higher-boiling organic compounds which include the compounds in the form of oily droplets which release non-diffusing color couplers and development inhibitors to be emulsified in the silver halide emulsions. In this connection, reference is made, for example, to US Pat. Nos. 2,322,027; 2,533,514; 3,689,271; 3,764,336 and 3,765,897.

• N,N-Dimethyl-p-phenylendiamin,
• 4-Amino-3-methyl-N-ethyl-N-methoxyethylanilin,
• 2-Amino-5-diethylaminotoluol,
• N-Butyl-N-ω-sulfobutyl-p-phenylendiamin,
• 2-Amino-5-(N-ethyl-N-ß-methansulfonamidethyl-amino)-toluol,
• N-Ethyl-N-ß-hydroxyethyl-p-phenylendiamin,
• N,N-Bis-(ß-hydroxyethyl)-p-phenylendiamin,
• 2-Amino-5-(N-ethyl-N-ß-hydroxyethylamino)-toluol.

Weitere brauchbare Farbentwickler sind beispielsweise beschrieben in J. Amer. Chem. Soc. 73, 3100 (1951).The photographic materials can be processed with conventional black and white developers, e.g. As hydroquinone, pyrocatechol, p-methylaminophenol and 1-phenyl-3-pyrazolidone and with color developer substances, in particular of the p-phenylenediamine type, are developed, e.g. B. with

• N, N-dimethyl-p-phenylenediamine,
• 4-amino-3-methyl-N-ethyl-N-methoxyethylaniline,
• 2-amino-5-diethylaminotoluene,
• N-butyl-N-ω-sulfobutyl-p-phenylenediamine,
• 2-amino-5- (N-ethyl-N-ß-methanesulfonamidethyl-amino) -toluene,
• N-ethyl-N-β-hydroxyethyl-p-phenylenediamine,
• N, N-bis (ß-hydroxyethyl) -p-phenylenediamine,
• 2-amino-5- (N-ethyl-N-β-hydroxyethylamino) toluene.

Other useful color developers are described, for example, in J. Amer. Chem. Soc. 73, 3100 (1951).

It is particularly advantageous about the compounds to be used according to the invention that the stabilization of the latent image nuclei is not linked to the simultaneous use of certain hardening agents for the gelatin.

example 1

A highly sensitive silver bromide iodide emulsion with 6 mol% silver iodide is prepared in the usual way, flocculated and freed from the soluble salts. It is then redispersed, mixed with gelatin and ripened with sulfur and gold compounds in a known manner. The emulsion had a silver nitrate / gelatin ratio of 1: 1 and contained 95 g of silver per kg, calculated as silver nitrate.

• 200 mg 4-Hydroxy-6-methyl-1,3,3a,7-tetraazainden in Form einer 1%igen wäßrig-alkalischen Lösung;
  
  sowie ein erfindungsgemäß zu verwendender Stabilisator in Form einer 1%igen alkoholischen Lösung in den aus Tabelle (2) ersichtlichen Mengen.

The emulsion is divided into 11 equal parts before pouring. Before the sprue, these parts are added per kg:

• 200 mg of 4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene in the form of a 1% aqueous alkaline solution;
  
  and a stabilizer to be used according to the invention in the form of a 1% alcoholic solution in the amounts shown in table (2).

mit Wasser auf 1 I auffüllen.The emulsions were then poured onto a cellulose acetate support in such a way that the silver coating, calculated as silver nitrate, was 5.5 g per m ² . The samples were dried in the customary manner, exposed in a sensitometer behind a gray-scale wedge and, after the treatments shown in Table 2, were developed at 20 ° C. for 7 or 16 minutes in a developer I of the following composition:

Make up to 1 liter with water.

The results of the sensitometric evaluation are shown in Table 2 below.

The evaluation of the sensitivity in Table 2 is carried out relative to the test drawn as a type. Differences in sensitivity are thus indicated. An increase of this value by three units means a doubling of the sensitivity. The sensitivity itself is determined at a density of 0.2 over fog.

Example 2

Color photographic materials for reverse processing are produced by successively applying the layers listed below to a cellulose triacetate support provided with an adhesive layer.

I. Control sample

• 1. A red-sensitized silver halide emulsion containing 70 g of gelatin, 60 g of silver (thereof 96% in the form of the bromide and 4% in the form of the iodide) and 55 g of the cyan coupler of the following formula per kg
  
  The silver coating is 1.0 g per m ² , calculated as silver nitrate.
• 2. A 2% aqueous gelatin solution containing 4 g of the polymeric white coupler of the following formula described in DE-A-2 304 319 per kg
  
• 3. A green-sensitized silver halide emulsion containing 70 g of gelatin, 60 g of silver (thereof 96% in the form of the bromide and 4% in the form of the iodide) and 60 g of the purple coupler of the following formula per kg
  
  The silver coating is 0.9 g per m ² , calculated as silver nitrate.
• 4. A silver dispersion containing 1.8 g of silver, calculated as silver nitrate, and 12 g of gelatin per liter. The color density of the yellow filter layer, measured behind a blue filter, is 0.6; the silver coating is 0.2 g / m ² , calculated as silver nitrate.
• 5. An unsensitized silver halide emulsion containing 70 g of gelatin, 60 g of silver (thereof 95% in the form of the bromide and 5% in the form of the iodide) and 140 g of the following yellow coupler per kg
  
  The amount of silver applied is 1.5 g per m ² , calculated as silver nitrate.
• 6. A 1% gelatin solution with a wet application of 60 g per m ^2.
• 7. A 1% aqueous solution of the hardener of the following formula with a wet application of 60 g per _m 2 _:
  

Il. Sample according to the invention with compound 1

The sample is prepared as described for sample I, except that 100 mg / kg of compound 1, dissolved in methanol, are added to the yellow layer (layer 5).

Each of samples I and II is exposed behind a gray gradient wedge, stored for 8 weeks at room temperature and then subjected to the following reverse processing at 30 ° C:

Baths of the following composition are used:

Developer II

mit Wasser auf 1000 ml auffüllen und auf pH 10,0 einstellen.

Make up to 1000 ml with water and adjust to pH 10.0.

Stop bath

mit Wasser auf 1000 ml auffüllen und auf pH 4,1 einstellen.

Make up to 1000 ml with water and adjust to pH 4.1.

Developer III

mit Wasser auf 1000 ml auffüllen und auf pH 12,0 einstellen.

Make up to 1000 ml with water and adjust to pH 12.0.

Bleach bath

mit Wasser auf 1000 ml auffüllen, mit Essigsäure auf pH 5 einstellen.

make up to 1000 ml with water, adjust to pH 5 with acetic acid.

Fixer

mit Wasser auf 1000 ml auffüllen und auf pH 5,0 einstellen.

Make up to 1000 ml with water and adjust to pH 5.0.

The sensitometric evaluation in Table 3 shows that the photographic material which contains the compound 1 (sample 11) has significantly lower sensitivity decreases in the latent image in the brass than the comparative sample. Analogous results are obtained with compounds 9, 10 and 11.

An increase of the specified values by 3 units corresponds to a doubling of the sensitivity.

Claims (8)

1. Light-sensitive photographic material containing at least one light-sensitive silver halide emulsion layer and optionally other layers, characterised in that it contains in at least one layer a compound of the formula (I)

wherein

R^I denotes H, OH or halogen;

R² and R³, which may be the same or different, denote H, an optionally substituted alkyl group having 1 -4 C atoms or acyl; and

R⁴ denotes H or alkyl having 1 to 4 C atoms,

in a quantity of at the most 10-² mol per mol of silver halide.

2. Material according to Claim 1, characterised in that

R¹ denotes H or OH;

R² denotes an optionally substituted alkyl group having 1 to 3 C atoms or acetyl;

R³ denotes an optionally substituted alkyl group having 1 to 3 C atoms or H; and

R4 denotes H or methyl.

3. Material according to Claim 1, characterised in that

R¹ denotes H or OH;

R² and R³, which may be the same or different, denote ethyl or hydroxyethyl, and

R⁴ denotes H.

4. Material according to Claim 1, characterised in that it contains the compound of the formula (I) in a quantity of 10 mg to 1000 mg per mol of silver halide.

5. Material according to Claim 1, characterised in that it contains at least one of the following compounds:

6. Process for the preparation of light-sensitive photographic materials containing silver halide by precipitation of the silver halide, ripening and application to a layer support, characterised in that a compound of the formula (1) according to Claim 1 is added to the silver halide emulsion before its application.

7. Process according to Claim 6, characterised in that the addition is carried out before chemical ripening.

8. Process for the production of photographic images by image-wise exposure and development of the material according to Claim 1.