DE2130031A1 - Silver halide emulsion layers - of photographic materials stabilised against fog development with 1, 3-dicarboxy-benzimidazolin - Google Patents

Abstract

Silver halide emulsion layers of light sensitive photographic material contain an ester of 1,3-dicarboxy-benzimidazoline-2-thione as stabiliser. The stabiliser prevents development of fog in the silver halide emulsion layer, even when it is stored under conditions of high temp. and humidity. The sensitivity of the silver halide emulsion layer is unaffected. The stabiliser pref has the formula (I): (where R' is C1-6 alkyl R2 is H, C1-6 alkyl, C1-6 alkoxy, halogen, uryloxy, nitro, carboxy, carbamoyl sulpho or sulphamoyl; n is 1 or 2). The stabiliser may be present in the silver halide emulsion layer, or in the barytes layer of a paper impregnated with barytes.

Description

Improved Photographic Material The invention relates to a An improved photographic material in which, by containing benzimidazoline-2-thione-N, N'-dicarboxylic acid esters the formation of annoying yellow haze is prevented.

In the processing of photographic materials, in particular with machine processing, it often happens that thiosulfate from the fixer is carried over into the developer. In other cases, such as rapid, stabilizing or fix development, will be a silver halide solvent, in most cases Thiosulfate or potassium thiocyanate added to the developer or stabilizing bath.

Used in the development of photographic materials such developers containing silver halide solvents are formed depending on the The type and age of the photo paper is more or less yellow to brown Veil.

In the presence of some stabilizers, e.g. 1-phenyl-5-mercaptotetrazole, this veil can also be colored blue to blue-violet. In photographic This veil consists of finely divided paper deposited in the baryage Silver.

This yellow haze is caused in barytaised photographic papers by that during the pouring silver salts from the emulsion into the bar days where they are held by the barite adsorptively. When storing the finished Papers, these silver salts are reduced to silver - a process that is going on before especially in the first few months of storage. Now included by the developer When processing the papers, silver halide solvents such as thiosulphates become so the dissolved silver salts are reduced on the silver nuclei of the barytage, and it comes for yellow haze and staining. They also play a role in staining Properties of the raw materials play a major role.

After storage, the yellow haze is particularly pronounced. Place the papers that were exposed to humidity, e.g. 3. at the edges of papers and on the top sheet of a pack.

The yellow haze occurs above all when using unwatered chlorine or C ## o: rbron ## ijberemulsionen, because the chlorides present in excess Soluble sorbent complex salts can form # The yellow haze also emerges when are used to make the emulsion or barytage gelatinesortew, which contain compounds which dissolve silver halide, and if also nucleating ones Degradation products of the gelatine are present. Such types of gelatin also cause a yellow haze in photographic films. Also, tend to be very scarce Emulsions with steep gradation, especially when developing the silver image steeply working developers with a higher content of potassium bromide are used, to yellow veil.

It is known that photographic silver halide emulsions have a tendency to fog by adding acyl, alkoxycarbonyl - and aroxycarbonyl derivatives heterocyclic mercaptans for emulsion or barytag or by adding bis-thiadiazole derivatives to suppress the barytage.

However, these compounds have the disadvantage that they are in their The most effective concentrations generally reduce the sensitivity of the emulsions or adversely affect the gradation, thereby impairing their applicability will. Monothiocarbonic acid or monothiocarboxylic acid esters are also mostly relative inconsistent and must therefore be stored in a cool place. Your solutions must be prior to use must always be added fresh.

The invention is based on the object of a method for suppression of the annoying yellow haze in photographic material.

A process has now been found for avoiding yellow haze in photographic materials, benzimidazoline-2-thione-N, N'-dicarboxylic acid esters being added to any layer, for example the baryage or silver halide emulsion layer. Compounds of the following formula are particularly useful: where: R1 = straight-chain or branched alkyl with up to 6 carbon atoms, R2 = hydrogen, halogen, preferably fluorine, chlorine or bromine, alkyl with up to 6 carbon atoms, trifluoromethyl, alkoxy with up to 6 carbon atoms, Aroxy, especially phenoxy, nitro, carboxy, carbamoyl, sulfo or sulfamoyl, n = 1 or 2.

The compounds listed in the following table have proven to be particularly suitable: Table: link No. R1 R2 1 -C2H5 H 2 -C2H5 5.6 - C1 3 -C2H5 5 - OCH3 4 -CH2-CU2-CH3 5 - Cl 5 -CH (CH3) 2 5.6 - Cl 6 -CH2-CH2-CH3 5,6 - Cl 7 -C2H5 5 - C1 8 -C2H5 5 - N02 The compounds to be used in the manner according to the invention are prepared by reacting the underlying benzimidazoline-2-thiones with pyrocarbonic acid esters, preferably in diluents.

Preparation of compound 1: 150 g (1 mol) of 2-mercaptobenzimidazole, 500 ml of ethanol and 405 g (2.5 mol) of diethyl pyrocarbonate are gradually increased heated to 500C and held at this temperature until the solution. The other day if you add 1.3 liters of petroleum ether, cool it down to -200C for a long time, it sucks Crystals off and wash them with frozen petroleum ether.

The crude product (187 g of melting point 30-420C) is used for purification in a Mixture of 470 ml of ethanol and 1.4 l of petroleum ether dissolved lukewarm, one clears with Charcoal, cools to OQC with stirring and isolates the precipitated benzimidazoline-2-thione-N, N # -dicarboxylic acid diethyl ester. The product is now completely pure and melts at 65.5 - 660C.

Preparation of compound 2: 21.9 g (0.1 mol) of 2-mercapto-5,6-dichlorobenzimidazole, 40 ml of ethanol, 48.6 g (0.3 mol) of pyrocarbonic acid diethyl ester and 0.5 ml (0.001 mol) 2N sodium methylate solution are stirred together overnight. The sandy reaction product is filtered off with suction (33.7 g of melting point 109-1130C) and recrystallized from ethanol. Man receives 25.5 g of pure compound with a melting point of 113-114 ° C.

Preparation of Compound 3: One from 72.0 g (0.4 mol) of 2-mercapto-5-methoxy-benzimidazole and 388.8 g (2.4 mol) of pyrocarbonic acid diethyl ester existing suspension is on 90 ° C heated bath temperature. A vigorous exothermic reaction sets in after about 2 hours one, and at that moment the bathroom is removed. When the reaction has subsided is, it is heated for 1.5 hours with a 900C warm bath. Then add 400 ml Add ethanol, inoculate, crystallization can be completed at -200C, sucks and washes with frozen ethanol. It will be through this 94.4 g of crude 5-methoxy-benzimidazoline-2-thione-N, N'-dicarboxylic acid diethyl ester vom M.p. 76.5-770C. For cleaning, dissolve in 4 times the amount of hot ethanol, clears with coal and falls with 4 times the volume of hot petrol. The product then melts at 77.5 - 78 ° C.

Preparation of compound 4: 9.23 g (0.05 mol) of 2-mercapto-5-chloro'-benzimidazole, 20 ml of n-propanol, 0.1 g of the sodium salt of carbonic acid mono-n-propyl ester and 28.5 g (0.15 Mol) pyrocarbonic acid di-n-propyl ester are stirred together, with evolution of CO 2 a solution will soon emerge. The next day add 70 ml petroleum ether and cool to -200C, inoculates and after some time sucks off the boiled out product (3.4 g of m.p. 56-57 # c). After recrystallizing from petroleum ether (freezing) it melts the product sharp at 570C.

Preparation of compound 5: 10.95 g (0.05 mol) of 2-mercapto-5,6-dichlorobenzimidazole, 20 ml isopropanol, 0.1 g Na salt of carbonic acid mono-isopropyl ester and 28.5 g (0.15 mol) diisopropyl pyrocarbonate are stirred together. The suspension converts under the evolution of C02. The other day the product is used after cooling Sucked off to -200C and recrystallized from isopropanol. One receives 12.0 g of Mp 127.5-128 ° C.

Preparation of compound 6: 10.95 g (o, os mol) 2-mercapto-5,6-dichlorobenzimidazole, 20 ml of n-propanol, 0.1 g of the sodium salt of carbonic acid mono-n-propyl ester and 28.5 g (0.15 mol) of di-n-propyl pyrocarbonate are stirred together, the initial suspension converts with evolution of COg. At the other Day one sucks off at 0 C and crystallizes the crude product (14.8 g of melting point 80 - 80.50C) from acetonitrile. The compound now melts at 80.5 - 81 ° C.

Preparation of compound 7: 46.1 g (0.25 mol) of 2-mercapto-5-chlorobenzimidazole, 135 ml of ethanol, 97.2 g (0.6 mol) of diethyl pyrocarbonate and 1.25 ml of 2N sodium methylate solution are stirred together. The suspension is transformed with the evolution of CO 2. The next day, the product is suctioned off and purified by recrystallization Ethanol. 40.3 g of melting point 88.5-890C are obtained.

Preparation of compound 8: 58.5 g (0.3 mol) of 2-mercapto-5-nitro-benzimidazole and 243 g (1.5 mol) of diethyl pyrocarbonate are placed in an oil bath at 100.degree warmed to solution (2 hours). When receiving, a pulp is created that one with O0C, sucks off and washes with alcohol. The crude 5-nitro-benzimidazoline-2-thione-N 'N' -dicarboxylic acid diethyl ester from the melting point around 135 ° C is used for purification recrystallized twice from 5 times the amount of toluene. The product then melts at 138-138.50C.

These compounds to be used in the manner according to the invention are presumably not adsorbed by the halide silver grains of the emulsion, but are in the gelatin phase between the halosilver grains. In the alkaline The carboxy group is split off and the compound reacts with the developer soluble silver salts, which prevents the formation of yellow haze.

The compounds to be used in the present invention can be any Layer, but preferably added to the barytag or light-sensitive layer will. It will depend on the type of photographic material and substance in which layer the optimal effectiveness is achieved. However, this can go through a few simple experiments can be determined without difficulty.

The same applies to the concentration to be used. The ones to be added Amounts depend on which layer the compounds are incorporated into. Even this can be determined by simple experiments. When used in the emulsion layer the compounds are preferably used in amounts of from about 2 to 500 mg / mole of silver halide 20 to 200 mg added. For the baryta layer, concentrations from 0.01 to 2.0 g / kg BaS04, preferably 0.1 to 1.0 g / kg BaS04, are suitable.

It is advantageous to use the compounds according to the invention in the form of solutions to add. Suitable solvents are, for example, lower alcohols and tetrahydrofuran or acetone.

The compounds can be any of the baryta suspension Time of their production, e.g. in the kneader or mixer or before application, can be added.

The compounds of the present invention are added to the photosensitive silver halide emulsions added after chemical ripening.

The compounds of the invention can be used in any silver halide emulsions be applied. The silver halide used is silver chloride, silver bromide or mixtures of which, possibly with a low content of silver iodide up to 10 mol, are suitable. The silver halides can be in the usual hydrophilic compounds be dispersed, for example carboxymethyl cellulose, alkyl cellulose, hydroxyethyl cellulose, Starch or its derivatives, carrageenates, polyvinyl alcohol, polyvinylpyrrolidone, Alginic acid and its salts, esters or amides, preferably gelatin.

The emulsions and barytag suspensions used can all be customary Supplements included.

The emulsions can be chemically sensitized in the usual way, for example with salts of noble metals such as rhutenium, rhodium, palladium, iridium or platinum. The emulsions can also be sensitized with gold salts, such as described in the article by R Koslowsky, Z.Wiss.

Phot. 46, 65-72 (1951).

The emulsions can also be chemically sensitized, for example by Addition of sulfur-containing compounds during chemical ripening, for example Allyl isothiocyanate, allyl thiourea, sodium thiosulfate and the like. As a chemical Sensitizers can also be reducing agents, e.g. those in the Belgian Patent specifications 493,464 or 568,687 described tin compounds, also polyamines such as diethylenetriamine, or aminomethylsulfinic acid derivatives, e.g. according to the Belgian U.S. Patent 547,323 can be used.

It is also possible to use the emulsions with polyalkylene oxide derivatives to sensitize, e.g. with polyethylene oxide with a molecular weight between 1000 and 20000, also with condensation products of alkylene oxides and aliphatic Alcohols, glycols, cyclic dehydration products of hexitols, with alkyl-substituted ones Phenolic, aliphatic carboxylic acids, aliphatic amines, aliphatic diamines and amides. The condensation products have a molecular weight of at least 700, preferably more than 1000. To achieve special effects you can of course use these sensitizers in combination, as in Belgian patent 537 278 and British patent 727 982 described.

The emulsions can also be optically sensitized, e.g. with the common polymethine dyes, such as neutrocyanines, basic or acidic carbpcyanines, Rhodacyanines, hemicyanines, styryl dyes, oxonols and the like.

Such sensitizers are in the work of F.M. Hamer "The Cyanine Dyes and related Compounds ", (1964).

The emulsions can be hardened in the usual way, for example with formaldehyde or halogen-substituted aldehydes that contain a carboxyl group, such as mucobromic acid, diketones, methanesulfonic acid esters, dialdehydes and the like.

The halide silver emulsions of the present invention can additionally contain others Contain stabilizers, preferably tetra- or penta-azaindenes, in particular those substituted with hydroxyl or amino groups. Such connections are in the article by Birr in the magazine for scientific photography, Volume 47, 1952, pages 2 to 28. It can also heterocyclic mercapto compounds, such as mercaptotetrazoles or mercury compounds may be included as stabilizers.

The compounds according to the invention can also be used in emulsions containing color couplers or developers.

In the processing of the photographic improved according to the invention Materials, the usual developer combinations can be used. The procedure does not depend on specific developer substances. Are useful, for example Hydroquinone-type, catechol-type, p-methylaminophenol developers, compounds the phenidone series, phenylenediamine developers, etc.

Example 1: An unwatered gelatin silver chlorobromide emulsion (20 mol% AgBr), which contains 0.18 mol of halogen silver per liter, is after the addition of 20 ml of a 10% strength aqueous saponin solution and 2 ml of a 30% strength aqueous formalin solution applied in a known manner to a substrate made of baryta-coated paper and dried. The silver application is 1.5 - 1.6 g / m2.

The above emulsion is divided into several parts before pouring divided. The compounds according to the invention are added to these parts in the form of a 1 % solution in acetone added. The amounts added are from the below indicated table.

The samples became fresh and after 48 hours of heating in the oven at 600C and 40% relative humidity in a developer with the following composition: 6 g hydroquinone 0.2 g 1-phenyl-3-pyrazolidone 40 g sodium sulfite sicc.

40 g sodium carbonate sicc.

3 g potassium bromide 3 g sodium thiosulphate crystall.

Make up to 1 1 with water for 2, 4 and 6 minutes at a developer temperature of 300C. The yellow haze of the various materials was measured with a densitometer behind a blue filter and the following results were obtained: Yellow veil Concentration freshness test, heating cabinet test Connection tration development time development time No. mg / l 2 4 6 2 4 6 min. Control sample - 0.16 0.32 0.63 0.32 0.57 0.71 1 30 0.07 0.12 0.20 0.07 0.13 0.20 2 30 0.05 0.13 0.19 0.08 0.15 0.21 Control sample - 0.15 0.32 0.48 0.25 0.40 0.62 3 30 o, Q6 0.22 0.39 0.11 0.28 0.48 -Control- sample - 0.10 0.19 0.30 0.27 0.55 0.66 4 30 0.10 0.16 0.21 0.10 0.18 0.22 5 30 0.11 0.16 0.24 0.11 0.17 0.26 6 30 0.09 0.15 0.21 0.10 0.17 0.22 Similar results are obtained when the materials are developed in a developer of the following composition: 1.3 g p-methylaminophenol sulfate 3 g hydroquinone 13 g sodium sulfite sicc.

15 g sodium carbonate sicc.

1 g potassium bromide 10 g sodium thiosulphate crystall.

Make up to 1 liter with water Yellow veil Concentration freshness test, heating cabinet test Connection development time development time No. mg / l 2 4 6 2 4 6 min. Control sample - 0.12 0.20 0.35 - 0.64 0.87 0.85 1 30 0.10 0.13 0.13 0.12 0.12 0.12 continuation Yellow veil Concentration freshness test, heating cabinet test Connection development time development time No. mg / l 2 4 6 2 4 6 min. 2 30 0.10 0.12 0.14 0.12 0.16 0.15 5 30 0.09 0.10 0.13 0.11 0.13 0.15 While the samples do not show a yellow haze even after they have been stored in a heating cabinet, a faint yellow haze is visible in the fresh control samples and a strong brown yellow haze is visible after a development time of 1 minute after storage in a heating cabinet. If you remove the emulsion layer from the baryage, you can see that the baryage of the control sample is colored brown and that of the test is colorless.

Example 2: A barite suspension is produced from: 15 kg barite white (BaS04 content 80%) 1.5 kg gelatin, 0.5%, dissolved in water 100 ml of a 20 own aqueous sodium hexametaphosphate solution 300 ml of a 10 own aqueous chromium alum solution and 200 ml of whole milk The Barytage suspension described above is before application divided into several parts. Connections 1, 2, 5 or 6 in Form of a 1 own solution in acetone and in amounts of 0.15 g / kg Baryage suspension added. A paper raw material is barytized three times in a known manner. Afterward the baryta-coated paper is coated with the emulsion described in Example 1.

The test is carried out as described in Example 1.

While the samples after the heating cabinet storage after a development period show no yellow haze after 1 minute, there is a dark brown, spotty yellow haze visible.

Claims (12)

Patent claims: Process for avoiding yellow haze when processing Photographic materials, characterized in that in the manufacture of these Materials of one of the layers Benzimidazoline-2-thione-N, N1 -dicarboxylic acid ester can be added. 2) method according to claim 1, characterized in that compounds of the following formula are added: where: R1 ~ straight-chain or branched alkyl with up to 6 carbon atoms, 2 = hydrogen, halogen, alkyl with up to 6 carbon atoms, trifluoromethyl alkoxy with up to 6 carbon atoms, aroxy, nitro, carboxy, carbamoyl, Sulfo or sulfamoyl, n = 1 or 2, 3) Method according to claim 1, characterized in that in the manufacture of the photographic materials, the compounds of the light-sensitive emulsion layer can be added. 4) Method according to claim 2, characterized in that the substances can be added in amounts of 2 to 500 mg / mole of silver halide. 5) method-according to claim 1, characterized in that the Preparation of the photographic materials the compounds of the baryta layer can be added. 6) Method according to claim 5, characterized in that the substances in amounts of 0.01 to 2 glkg of barium sulfate are added. 7) Photographic light-sensitive material having at least one light-sensitive layer, characterized by a content of a benzimidazoline-2-thione-N, N'-dicarboxylic acid ester. 8) Material according to claim 7, characterized by a content of a compound of the following formula: where: R1 = straight-chain or branched alkyl with up to 6 carbon atoms, R2 = hydrogen, halogen, alkyl with up to 6 carbon atoms, trifluoromethyl, alkoxy with up to 6 carbon atoms, aroxy, nitro, carboxy, carbamoyl , Sulfo or sulfamoyl, n = 1 or 2. 9) Photosensitive material according to claim 7, characterized in that that the compounds are contained in the photosensitive layer. 10) Photosensitive material according to claim 9, characterized in that that the compounds in amounts of 2 to 500 mg / mol of silver halide in the light-sensitive Layer are included. 11) material according to claim 7, characterized in that the connections are contained in the barite layer. 12) Material according to claim 11, characterized in that the connections are contained in amounts of 0.01 to 2 g / kg of barium sulfate.