Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B23/00—Methine or polymethine dyes, e.g. cyanine dyes
  • C09B23/10—The polymethine chain containing an even number of >CH- groups
  • C09B23/105—The polymethine chain containing an even number of >CH- groups two >CH- groups
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B23/00—Methine or polymethine dyes, e.g. cyanine dyes
  • C09B23/14—Styryl dyes
• • 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

• a direct-positive photographic silver halide emulsion for use in a solarization technique comprising a lightsensitive silver halide which has been fogged by light or chemical means and includes a spectrally sensitizing methine dye of the 2-phenylindole type in combination with a desensitizing nitrostyryl or nitrobenzylidene dye is described.
• the combination provides improved stability on storage, lower minimum densities, and increased total speed.
• This invention relates to light-sensitive direct-positive emulsions, more particularly to direct-positive emulsions, which possess an improved light-sensitivity in the visible spectrum.
• Solarization is a reversal phenomenon, which is produced by overexposure of a silver halide emulsion layer. It is supposed that said overexposure results in the destruction of previously formed developing centers.
• the preparation of a solarized emulsion for the production of direct positives consists in producing a uniform latent image corresponding to the critical exposure. This can be realized by overall exposing the light-sensitive emulsion to actinic light or by appropriate overall chemically fogging it with reducing substances.
• a latent image can be reversed by a second exposure to red or infrared light.
• the sensitive layer is first fogged uniformly to its maximum density with blueviolet light and is imagewise exposed e.g. behind a positive transparency, with light of a wavelength greater than 600 nm., preferably at low intensity and for a long time. If the photographic material is treated with a so-called desensitizing dye," the Herschel effect may be obtained with light of a shorter wavelength such as yellow light.
• spectral sensitizers known for spectrally sensitizing silver halide emulsions of the negative type cannot be used since in said positive emulsions they show disadvantages as for example, discoloration of the white areas, a general flattening of the gradation curve and/or rise in density in the exposed parts immediately after exposure or on storage.
• spectrally sensitizing dyes an important class of which is formed by the methine dyes of the Z-phenyl-indole series. Dyes of that type are e.g. described in the United Kingdom Pat. Specifications Nos. 825,965 filed Mar. I9, 1957 and 970,601 filed Apr. 9, 1963 both by Agfa AG. Said dyes are but very weak spectrally sensitizing agents for common silver halide emulsions of the negative type.
• a direct-positive photographic silver halide emulsion for use in the solarization technique comprises light-sensitive silver halide, which has been fogged by light or chemical means and which includes a spectrally sensitizing methine dye of the 2-phenylindole type in combination with a desensitizing nitrostyryl or nitrobenzylidene dye.
• the advantage resulting from that combination compared with the results obtained by the use of the 2-phenylindole dyes alone consists in an improved stability on storage, lower minimum densities i.e. brighter whites in the exposed areas of the developed material and especially an increased total speed.
• Methine dyes of the Z-phenylindole class which have proved to be very suitable for use according to the present invention can be represented by the following general formula:
• R and R an alkyl group including substituted alkyl of the type generally known in cyanine dye chemistry such as methyl, ethyl, n-propyl, n-butyl, n-amyl, isopropyl, isobutyl, B- hydroxyethyl, fl-acetoxyethyl, sulfoethyl, sulfopropyl, sulfobutyl, sulfatapropyl or sulfatobutyl, an unsaturated aliphatic group e.g. allyl, an aralkyl group e.g.
• benzyl a substituted benzyl group such as carboxybenzyl, an aryl group e.g. phenyl, a substituted aryl group such as carboxyphenyl, a cycloalkyl group such as cyclohexyl and cyclopentyl or a substituted alkyl group such as the group -ACOO-B-SO OH wherein each of A and B represents a hydrocarbon group as described in the United Kingdom Pat Specification No.
• A represents a methylene group, an ethylene group, a propylene group or a butylene group
• B represents an alkyl group, an amino group, a substituted amino group and also a hydrogen atom if V is a single bond
• each of W and V represents a carbonyl group, a sulfonyl group or a single bond, but at least one of them representing a sulfonyl group, as described in the United Kingdom Pat. Specification No. 904,332 filed July 5, 1957 by Gevaert PhotoProducten N.V.;
• Ph a phenyl group including substituted phenyl e.g. an alkylaryl-, alkoxyor halogen substituted phenyl group, said substituents preferably standing in the p-position,
• Z the necessary atoms to form a fused benzene nucleus, which may be substituted e.g. by halogen, an alkyl, or an alkoxy group,
• X represents an anion e.g. Cl, Br, I, C10,, Ch SO and H .,C- Q -SO but X is not present if R itself thiazole, 4-(p-bromophenyl)-thiazole, 4,5-dimethylthiazole,
• fisulfobenzothiazole 4-phenylbenzothiazole, S-phenylbenzothiazole, 4-methoxybenzothiazole, S-methoxybenzothiazole, 6-methoxybenzothiazole, 5- iodobenzothiazole, 6-iodobenzothiazole, 4-ethoxybenzothiazole, S-ethoxybenzothiazole, 4,5,6,7-
• benzoxazole 5- chlorobenzoxazole S-methylbenzoxazole, S-phenylbenzoxazole, -methylbenzoxazole, 5,6-dimethylbenzoxazole, 4,6- dimethylbenzoxazole, S-methoxybenzoxazole, 6-methoxybenzoxazole, S-hydroxybenzoxazole, -hydroxybenzoxazole, those of the naphthoxazole series, e.g. naphtho[2, l -d]oxazole, naphtho[l,2-d]oxazole, those of the selenazole series e.g.
• benzimidazole 5,6-dichlorobenzimidazole, chlorobenzimidazole, 5,6-dibromobenzimidazole, 5chloro-6- eminobenzimidazole, 5-chloro-6bromobenzimidazole, 5-
• fluoro-6 cyanobenzimidazole S-acetylbenzimidazole, 5- chloro-6-fluorobenzimidazole, S-carboxy-benzimidazole, 7- carboxybenzimidazole, 5-carbethoxybenzimidazole, 7-carbethboxybenzimidazole, S-sulphamylbenzimidazole, or S'N- ethylsulphamylbenzimidazole.
• the dyestuffs according to the above general formula can be prepared according to the method described in the United Kingdom Pat. Specification No. 970,601 filed Apr. 9, 1963 by Agfa AG.
• Suitable nitrobenzylidene and nitro-styryl dyes can be represented by the following general formulas:
• cyclic ketomethylene nucleus such as one of those of the pyrazolone series e.g., 3-methyl l-phenylS-pyrazolone, l-phenyl-S- pyrazolone, l-(2-benzothiazolyl-3-methyl-5-pyrazolone, those of the isoxazolone series e.g., 3-phenyl-5-isoxazolone, or 3- methyl-S-isoxazonlone, those of the oxindole series e.g. lalkyl-2,3-dihydro-2-oxindoles, those of the 2,4,6-triketohexanhydropyrimidine series e.g.
• a cyclic ketomethylene nucleus such as one of those of the pyrazolone series e.g., 3-methyl l-phenylS-pyrazolone, l-phenyl-S- pyrazolone, l-(2-benzothiazolyl-3
• barbituric acid or 2-thiobarbituric acid as well as their derivatives such as those substituted in the l-position by an alkyl group such as a methyl group, an ethyl group, an l-n-propyl group, and a l-n-heptyl group, or those substituted in the land 3-position by an alkyl group, or those substituted in the lor 3-positi0n by a B-methoxy-ethyl group, or those substituted in the 1- and 3-position by an aryl group such as a phenyl group, or those substituted in the land 3-position by a substituted phenyl group such as a pchlorophenyl group, or a p-ethoxycarbonylphenyl group, or those substituted only in the l-position by a phenyl-, pchlorophenyl-, or p-ethoxycarbonylphenyl group, further the mixed alkyl-alkyl
• rhodanine and aliphatically substituted rhodanines e.g., 3- ethyl-rhodanine, or 3-allyl-rhodanine, those of the imida7o[l,2-a]pyridone series, those 'of the 5,7-dioxo-6,7- dihydro-5-thiazole[3,2-a1pyrimidine series e.g. 5,7-dioxo-3- phenyl-6,7-dihydro-S-thiazole[3,2-a]pyrimidine series e.g.
• 3-ethyl-2-thio-2,5- thiazolidinedione series i.e. the 2-thio-2,5-thiazoledione series e.g. 3-ethyl- 2-thio-2,5-thiazolidinedione, of the 2,4- thiazolidinedione series e.g. 2,4thiazolidinedione, 3-ethyl-2,4- thiazolidinedione, 3-phenyl-2,4-thiazolidinedione, 3-anaphthyl-2,4-thiazolidinedione, those of the thiazolidone series e.g.
• 2,4-imidazolinedione 3-ethyl-2,4- imidazolinedione, 3-phenyl-2,4-imidazolinedione, 3-anaphthyl-2,4-imidazolinedione, l,3-diethyl-2,4- imidazolinedione, l-ethyl-3-phenyl-2,4-imidazolinedione, lethyl-3-a-naphthyl-2,4-imidazolinedione, l,3-diphenyl-2,4- imidazolinedione, those of the 2-thio-2,4-imidazolinedione (i.e., Z-thiohydantoin) series e.g., 2-thio-2,4- imidazolinedione, 3-ethyl-2-thio-2,4-imidazolinedione, 3- phenyl-2-thio-2,4-imidazolinedione, 3-
• 'm represents 1, 2, or 3 O CH wherein m represents 1, 2, or 3 Hz) m C II O n represents a positive; integer l or 2.
• Desensitizing methine dyes containing an aromatic nitro group can be prepared by the condensation of a nitro-substituted aromatic compound containing an aldehyde group on the aromatic nucleus or such group linked thereto by a methine chain with a suitable heterocyclic compound having an active methyl or methylene group.
• the dyes may be added to the emulsion in the form of a solution.
• Suitable solvents are e.g. alcohols such as methanol or ethanol.
• the desensitizing dye is used in a ratio of 0.15 to 3.5 moles per mole of the spectrally sensitizing dye, whereas the latter is normally added in an amount of 0.02 to 1 millimole per mole of silver halide.
• the direct-positive emulsions can be prepared according to known methods.
• the silver halide composition is not critical, the silver halide may consist of silver chloride, silver bromide, silver iodide, or mixtures thereof. Preferred are emulsions that contain at least 50 percent by weight of silver bromide.
• the term direct-positive emulsions" comprises fogged emulsions, which are developable without fogging exposure after the imagewise exposure.
• the fogging of the emulsions can be accomplished by an overall exposure to light before the imagewise exposure or can be obtained by a chemical treatment.
• a reducing agent such as hydrazine, hydroxylamine, formaldehyde, stannous chloride, and sodium thiosulph'ate.
• alkaline substances e.g. sodium hydroxide or potassium hydroxide, which substances preferably are applied during the precipitation of the silver halide and the first ripening.
• the direct-positive emulsions may contain in addition to the light-sensitive silver halide salts minor amounts or traces of precious metal compounds such as gold, platina, palladium, iridium, ruthenium compounds, which compounds are known emulsion ingredients, as well as wetting agents, development accelerators, and optical brightening agents.
• precious metal compounds such as gold, platina, palladium, iridium, ruthenium compounds, which compounds are known emulsion ingredients, as well as wetting agents, development accelerators, and optical brightening agents.
• the exposure of the coated emulsion layers resulting from said portions proceeded through a continuous grey wedge with constant 0.2.
• Two types of exposure were applied, one by means of a fluorescent light source F 15 T 8 Daylight contained in the Blu-Ray Radiograph Duplicating Printer marketed by Blu-Ray Reproduction Engineering Corporation, Essex, Connecticut U.S.A., the other by means of incandescent bulbs of a total energy of 375 Watt through a light-diffusing glass.
• One group of the same emulsion strips was exposed and processed after normal storage at room temperature, whereas another group was exposed and processed under the same conditions after a preliminary treatment for 36 h. in an atmosphere of 34 percent of relative humidity at a temperature of 57 C.
• the developer applied was a common developer on the /R5 basis of hydroquinone and N-methyl-p-aminophenol- -NN -CC0Re, CSH hemisulphate.
• ll L ll I I The total speed is expressed in percent with respect to 7 reference emulsions, the total speed of which is arbitrarily 5 R6 R6 given the value 100. The total speed is denoted in the table by the letter S.
• the density in the exposed areas is a measure of g g g l the brightness of the whites and is denoted in the table by 7 a 7 D,(minimum density).
• I 62 0. 13 100 0.05 100 0. 04 100 A 1 62 0.08 100 0. 03 100 0. 04 100 1+1 31+31 0. 08 182 145 0. 03 400 251 0. 03 332 200 I 62 0.09 100 .t 0.04 100 0.03 100 .4 B 2 62 0.08 100 0.03 100 0. 03 t 100 1+2 3l+31 0. 06 138 138 0. 01 316 240 0. 01 288 263 I 62 0.09 100 0. 04 100 0.03 100 C 3 62 0. 09 100 0.03 100 0.03 100 1+3 31+31 0.07 126 120 0. 01 251 191 0. 01 101 166 I 62 0.11 100 0. 05 100 0. 03 100 D 6 62 0.11 100 0. 04 100 0. 03 100 1+6 31+31 0. 09 100 110 0.
• a direct-positive photographic element comprising a fogged silver halide emulsion containing at least one nitrostyryl or nitrobenzylidene dye having a formula selected from the group wherein each of R R-,, and R represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group, NO -CN, an aromatic homocyclic monovalent such as phenyl or naphthyl or a monovalent heterocyclic group with aromatic character such as furyl, thienyl, pyrrolyl, indolyl, or
• Ph is a phenyl group
• Y represents the necessary atoms to complete a heterocyclic nucleus of the types used in the production of cyanine dyes
• X is an anion
• said nitrostyryl or nitrobenzylidene due and said Z-phenylindolemethine dye being present in said silver halide emulsion in amounts sufiicient and in select ratios to provide a superadditively increased total speed for white light.
• a process for the production of a direct-positive photographic material comprising adding to a direct-positive photo- 1 1 graphic silver halide emulsi dn a desensitizing methine dye containing an aromatic nitro-substituted nucleus attached to the methine chain or group and a methine dye of the 2-phenylindole class, and coating said emulsion as a layer.
• a direct-positive photographic element comprising a fogged silver halide emulsion containing said 2-phenyl-indole-methine dye in an amount of 0.02 to l millimole per mole of silver halide and a nitrostyryl or nitrobenzylidene dyein a ratio of 0.15 to 3.5 moles per mole of the said methine dye.
• a direct-positive photographic element wherein the said methine dye is used in a silver halide emulsion layer in an amount of 100 to 250 mg. per mole of silver halide.
• a direct-positive photographic element comprising as fogged silver halide emulsion containing a methine due of one of the formulas selected from the group consisting of:
• nitrostyryl dye of one of the formulas selected from the group consisting of:

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)
• Plural Heterocyclic Compounds (AREA)

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Cited By (9)

• 1966
  • 1966-05-09 GB GB20343/66A patent/GB1155404A/en not_active Expired
• 1967
  • 1967-05-02 US US635358A patent/US3615610A/en not_active Expired - Lifetime
  • 1967-05-09 BE BE698178D patent/BE698178A/xx unknown
  • 1967-05-09 DE DE1547643A patent/DE1547643C3/de not_active Expired
  • 1967-05-09 NL NL6706468A patent/NL6706468A/xx unknown

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