Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/485—Direct positive emulsions
  • G03C1/48515—Direct positive emulsions prefogged
  • G03C1/48523—Direct positive emulsions prefogged characterised by the desensitiser
  • G03C1/4853—Direct positive emulsions prefogged characterised by the desensitiser polymethine dyes

Definitions

• the present invention relates to direct positive material with at least one layer which contains a silver halide emulsion which is veiled on the surface chemically or by exposure and a cyanine dye. New sensitizers and combinations of sensitizing substances are proposed for this type of emulsions known per se.
• the object of the present invention is to provide new, directly positive, veiled silver halide emulsions which, through the use of new sensitizers or mixtures of sensitizers, have improved sensitivity in the long-wave regions of visible light and are therefore suitable for largely overcoming the disadvantages mentioned of direct-positive photographic materials.
• the present invention relates to a direct positive photographic material with at least one layer which contains a silver halide emulsion which has been chemically or by exposure veiled and a cyanine dye, characterized in that the cyanine dye is a y-formylpentamethine cyanine of the formula or in which Y and Y 2 are identical or different and represent the atoms necessary for completing a mono- or polycyclic, heterocyclic ring system, R 1 and R 2 are identical or different and optionally represent substituted alkyl, alkenyl, aryl or aralkyl, R 3 and R 4 are the same or different and represent alkyl, alkenyl, aryl or aralkyl substituted by carboxyl or sulfonyl, X ⁇ is a monovalent anion, M ⁇ is monovalent cation and n is 1 or 2.
• the present invention further relates to the use of the photographic material for the production of direct positive images by imagewise exposure and development of the material and the process for the production of direct positive images.
• Suitable mono- or polycyclic heterocyclic ring systems are in particular those with 1 to 4, preferably fused rings, of which at least one ring is heterocyclic. Ring systems with 5- and / or 6-membered rings are preferred. They can optionally have further substituents (in addition to R 1 , R 2 , R 3 or R 4 ), for example alkyl (C 1 -C 4 ), in particular methyl, aryl, in particular, phenyl or haloalkyl (C 1 -C 4 ), in particular trifluoromethyl.
• the substituents R 1 and R 2 can be alkyl having 1 to 20, in particular having 1 to 4, carbon atoms, furthermore alkenyl having, for example, 2 to 10 carbon atoms; preferred aryl and aralkyl radicals are phenyl, benzyl or phenylethyl.
• Suitable substituents on the alkyl or alkenyl radicals mentioned are, for example, halogen (fluorine, chlorine, bromine), hydroxyl, cyano, alkoxy with 1 to 4 carbon atoms, carbalkoxy with 1 to 4 carbon atoms in the alkoxy radical, carboxyl (COOH or COO) or the sulfo group ( S0 3 H or -SO 3 ⁇ ), where, however, at most one of a l-alkyl- or alkenyl groups containing carbonyl, or sulfo group may be substituted; the same substituents come into consideration as substituents on phenyl or benzyl, furthermore also alkyl, hydroxyalkyl or haloalkyl, each with 1 to 4 carbon atoms, and -NH 2 , -CONH 2 or -SO 2 NH 2 , the latter two also on the nitrogen atom may be substituted with alkyl (C 1 -C 4 ).
• halogen flu
• the substituents R 3 and R 4 which are identical or different from one another, are alkyl or alkenyl, aryl or aralkyl which are substituted by carboxyl or the sulfo group, where alkyl or alkenyl contain, for example, up to 4 carbon atoms and aryl or aralkyl are preferably phenyl, benzyl or phenylethyl are.
• Preferred substituents R 1 to R 4 are methyl, ethyl, n-propyl, n-butyl, isobutyl, allyl, ⁇ -methallyl, ⁇ -methoxyethyl, ⁇ -ethoxyethyl, ⁇ -hydroxyethyl, ⁇ -carboxymethyl, carboxyethyl, carboxypropyl, Carboxybutyl, sulfoethyl, sulfopropyl, sulfobutyl, p-sulfobenzyl, carbomethoxymethyl or ethyl or carbäthoxymethyl or ethyl.
• Other suitable heterocycles correspond to the following formulas:
• heterocycles suitable for the production of cyanine dyes are e.g. from D.M. Sturmer, Syntheses and Properties of Cyanine and Related Dyes in Chemistry of Heterocyclic Compounds, Vol. 30, (1977), edited by A. Weissberger and E.C. Taylor known.
• the anions X e in the compounds of the formula (Ia) are in particular the halides, such as chloride, bromide or iodide, furthermore nitrate, tetrafluoroborate, perchlorate, rhodanide and p-toluenesulfonate, and also hydrogen sulfate.
• halides such as chloride, bromide or iodide, furthermore nitrate, tetrafluoroborate, perchlorate, rhodanide and p-toluenesulfonate, and also hydrogen sulfate.
• the monovalent cations (M ⁇ in the compounds of formula (lb)) are, for example, hydrogen, alkali metals (sodium, potassium), ammonium or substituted ammonium.
• the sensitivity of the direct positive photographic materials according to the invention can be further increased by, besides the ⁇ -formyl mentioned
• pentamethine cyanines also used other conventional sensitizing dyes other than ⁇ -formyl fentamethine cyanines in the photographic materials.
• sensitizing dyes are suitable for the usual mono- or polymethine dyes such as acidic or basic cyanines, hemicyanines, streptocyanines, M erocyanine, oxonols, hemioxonols or styryl example.
• Such sensitizers are described for example by FM Hamer "The Cyanine Dyes and Related Compounds" (1964), Interscience Publishers John Wiley and Sons.
• Substituents on these heterocyclic radicals are alkyl with 1 to 18 carbon atoms, halogen, in particular chlorine and bromine, amino, alkylamino with 1 to 4 carbon atoms, alkoxyalkyl with 1 to 4 carbon atoms in the alkyl and alkoxy part, haloalkyl with 1 to 4 carbon atoms, for example trifluoromethyl , Nitro, aryl, especially phenyl, carboxyalkyl with 1 to 4 carbon atoms in the alkyl part and sulfoalkyl with 1 to 4 carbon atoms in the alkyl part. Specifically, the following may be mentioned C yaninfarbstoffe suitable as additional sensitizing dyes:
• the emulsions which can be used for the invention are the customary photographic emulsions composed of silver chloride, bromide or iodide and mixtures of these halides, the proportions of the various halides being able to vary within wide limits.
• Suitable emulsions are e.g. in U.S. Patent Nos. 3,501,305, 3,501,306, 3,531,288 and 3,501,290.
• vapor-deposited layers of silver halide on suitable supports can also be processed according to the invention into direct positive materials.
• the surface fogging of the silver halide can e.g. by exposure or by chemical means with the usual fogging agents, e.g. with reducing agents such as sodium formaldehyde sulfoxylate, hydrazine, tin (II) salts or thiourea dioxide.
• reducing agents such as sodium formaldehyde sulfoxylate, hydrazine, tin (II) salts or thiourea dioxide.
• reducing agents such as sodium formaldehyde sulfoxylate, hydrazine, tin (II) salts or thiourea dioxide.
• reducing agents such as sodium formaldehyde sulfoxylate, hydrazine, tin (II) salts or thiourea dioxide.
• a metal which is more noble than silver e.g. Rhodium, gold, etc.
• the veiled emulsions provided according to the invention with a ⁇ -formyl pentamethine cyanine and optionally further spectral sensitizing dyes are poured onto a suitable base made of glass, paper or plastic in a thin layer, customary further auxiliaries, such as stabilizers, wetting agents, Hardener, plasticizer, hydrophilic Colloids and dispersiches of polymers can be added to facilitate coating and / or to impart the desired physical properties to the photographic layers.
• the photographic materials can except the arbkupplern or the photosensitive layers, further layers such as protective layers, filter layers, antihalation layers, and further layers with another image active ingredients, such as F or bleachable dyes contained.
• Example 1 A direct positive emulsion, the mode of action of which is based on the principle of bleaching a surface veil, is produced by using a cubic monodisperse silver iodide bromide emulsion in gelatin, the iodide content of which is 1.6 mol% and the mean edge length of the cube-shaped crystals being 31 ⁇ m at a temperature of 60 ° C for 2 hours exposed to chemical fogging.
• As a fogging agent 7 ml of a 0.01% solution of sodium formaldehyde sulfoxylate and 14 ml of a 0.01% solution of carbon tetrachloride (HAuCl 4 ) are used per mole of silver halide present in the emulsion.
• a pH of 8.8 and a pAg of 5.9 are maintained during the concealment.
• the emulsion is then treated with a solution of the ⁇ -formyl pentamethine cyanine of the formula (2), 670 mg of the dye being used per 1 mol of silver halide of the emulsion.
• the emulsion then turns into a thin layer on a polyester base shed even film.
• the layer thickness is measured so that one square meter of the layer contains 2.0 g of silver and 2.9 g of gelatin.
• a sample of the layer is exposed in a sensitometer with ordinary tungsten incandescent light behind a step wedge and developed with a developer of the following composition:
• Example 2 As described in Example 1, direct positive emulsions are prepared with the ⁇ -formyl pentamethine cyanines of the formulas (3), (4), (5) and (6), 600 mg of these dyes being used per mole of silver halide.
• the emulsions obtained are cast on a polyester base to form a thin, uniform film.
• the layer thickness is measured so that a square meter of the layer contains 2.3 g of silver and 3.2 g of gelatin.
• Example 3 shows the effect of an additional conventional sensitizer which brings about an increase or change in sensitivity of the original direct positive emulsion sensitized with a ⁇ -formyl-pentamethine cyanine.
• a direct positive emulsion the mode of action of which is based on the principle of bleaching a surface veil, is produced by using a cubic-monodisperse silver iodide bromide emulsion in gelatin, the iodide content of which Is 1.6 mol% and the average edge length of the cube-shaped crystals is 0.25 ⁇ m at a temperature of 60 ° C. for 100 minutes subject to chemical fogging.
• As a fogging agent 7 ml of a 0.01% solution of sodium formaldehyde sulfoxylate and 14 ml of a 0.01% solution of carbon tetrachloride (HAuCl 4 ) are used per mole of silver halide present in the emulsion.
• a pH of 8.8 and a pAg of 5.9 are maintained during the concealment.
• the emulsion is then divided into two parts and one part is treated with a solution of the cyanine of the formula (6), 734 mg of the dye being used per 1 mol of silver halide of the emulsion (emulsion 1).
• the other part is treated with a solution of 467 mg of the cyanine of the formula (6) and 267 mg of the additional sensitizer of the formula (8) per mole of silver halide (emulsion 2).
• the emulsions are then cast onto polyester substrates to form thin, uniform films.
• the layer thickness is measured so that one square meter of the layer contains 2.1 g of silver and 3.0 g of gelatin.
• the overall sensitivity of the two emulsions is the same.
• the sensitivity S minus blue in emulsion ( 2 ) is increased at the expense of the sensitivity S blue .
• the sensitivity S blue is determined with a Kodak filter 47B and the sensitivity S minus blue with a Kodak filter F 16.
• Example 4 Surface-covered emulsions are prepared as described in Example 3, divided into two parts and 733 mg of the cyanine of the formula (5) per mole of silver halide are added to the first emulsion and 600 mg of the cyanine of the formula (5) and 133 mg of the additional sensitizer of formula (9) per mole of silver halide.
• the emulsions are poured into uniform films on polyester substrates, exposed and developed as described in Example 3.
• Example 5 A surface-veiled emulsion prepared according to Example 1 is treated with a solution of the cyanine of the formula (7), 733 mg of the cyanine (7) being used per 1 mol of silver present in the emulsion. The emulsion is then, as described in Example 1, poured onto a polyester base, dried, then exposed and developed.
• Example 6 A direct positive emulsion, the mode of action of which is based on the principle of bleaching a surface veil, is prepared by using a cubic monodisperse silver bromide iodide emulsion in gelatin, the iodide content of which is 1.6 mol%, and in which the mean edge length of the cube-shaped Crystals is 0.28 ⁇ m, chemically veiled at a temperature of 60 ° C.
• two samples are taken after 30, 60, 90, 120 and 180 minutes from the beginning of the concealment.
• One of these samples is treated with cyanine (2), the other with cyanine (6), in an amount of 733 mg per mole of silver halide.
• the layer contains 2.1 g of silver and 3.0 g of gelatin per m 2 of area.
• the table above shows that an optimal characteristic of the direct positive material is achieved with a certain concealment time.
• the optimal fogging time is about 110 minutes in the case of the emulsion with the cyanine (2), a sensitivity S 50 of 0.3 and a contrast of about 4, and in the case of the emulsion with the cyanine (6) about 90 minutes, with a sensitivity S 50 of 1.25 and a contrast of 5.5.
• the maximum density no longer increases or only increases insignificantly if the concealment time is extended further.

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• Chemical & Material Sciences (AREA)
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• Engineering & Computer Science (AREA)
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• Plural Heterocyclic Compounds (AREA)

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Cited By (2)

• 1980
  • 1980-02-04 EP EP19800810037 patent/EP0015235A2/de not_active Withdrawn
  • 1980-02-08 JP JP1378180A patent/JPS55106451A/ja active Pending

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