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
  • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
  • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
  • G03C5/50—Reversal development; Contact processes
• • 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
  • G03C1/48538—Direct positive emulsions non-prefogged, i.e. fogged after imagewise exposure
  • G03C1/48546—Direct positive emulsions non-prefogged, i.e. fogged after imagewise exposure characterised by the nucleating/fogging agent
  • G03C1/48561—Direct positive emulsions non-prefogged, i.e. fogged after imagewise exposure characterised by the nucleating/fogging agent hydrazine compounds

Definitions

• Thisinvention relates to photography and particularly to a method of making direct positive photographs.
• the internal latent image emulsion is exposed and placed directly in a silver halide developing solution containing a hydrazine compound of the general formula in which at least two Rs are hydrogen atoms and when less than four Rs are hydrogen atoms, the remaining Rs are aryl, aralkyl, acyl, or carboxylic acid amide groups.
• the hydrazine compound does not contain more than one aralkyl, acyl, or carboxylic acid amide group, although it may contain either one or two aryl groups.
• the photographic emulsion used in the process of my invention is a gelatino-silver halide emulsion such as a silver bromide emulsion, a silver bromoiodide emulsion or a silver chloroiodide emulsion. It need not contain optical sensitizing dyes although certain sensitizing dyes may be added to it for the purpose of optical sensitizing or for promoting reversal.
• the emulsion should be undigested or if digested, the digestion should be carried out without the use of sulfur sensitizers. as Burtons emulsion, described in Wall, Photographic Emulsions, 1929, pages 52 and. 53. Burtons emulsion is made as follows:
• Silver nitrate g 100 Water cc 500 Ammonia-to form clear solution.
• An internal latent image emulsion that is, one which forms the latent image mostly inside the silver halide grains, as described on pages 296 and 297 of Mees The Theory of the Photographic Process, 19%2, is especially useful for the process of my invention.
• Most of the internal latent image emulsions are silver promo-iodide emulsions of high iodide content, preferably containing at least l0%20% of iodide.
• Burtons emulsion is an emulsion of this type, having a silver iodide content of approximately of the content of silver halide. It is not absolutely essential, however, for the emulsion to contain silver iodide.
• An internal latent image emulsion made as described in Davey and Knott U. S. application Serial No. 82,914, filed March 22, 1949, may also be used according to my invention.
• This emulsion is prepared by first forming in the absence of ammonia and in one or more stages silver salt grains consisting at least partly of a silver salt which is more soluble in water than silver bromide, subsequently convertin the grains to silver bromide or silver bromoiodide and if the silver iodide content of the emulsion is less than 6% calculated on the total silver halide, treating such grains with an iodine compound to bring the silver iodide up to at least 6%, ripening preferably in the absence of ammonia and then either washing out some of the soluble salts or washing out the Whole of the soluble salts, followed by the addition of soluble salts such as soluble chloride or bromide.
• An example of an emulsion made in this way is as follows:
• An internal latent image type of silver halide emulsion may be defined as one which, when a test portion is exposed to a light intensity scale for a fixed time between A and 1 second, and developed for 4 minutes at 20 C. in the ordinary, surface developer (Example I), exhibits a maximum density not greater than /5 the maximum density obtained when the same emulsion is equally exposed and developed for 3 minutes at C. in an internal type developer (Example II).
• the maximum density obtained with the surface developer is not greater than lie the maximum density obtained when the same emulsion is developed in the internal type developer.
• an internal latent image emulsion when developed in an internal type developer (Example II) exhibits a maximum density at least 5, and preferably at least 10, times the maximum density obtained when the same emulsion is exposed in the same way and developed in a surface developer (Example I).
• My process is carried out by exposing the internal latent image emulsion layer to an object or image and then placin the exposed emulsion layer directly in a silver halide developing solution containing one or more of the hydrazine compounds.
• Developing agents suitable for use in the process of my invention include the usual phenolic or aminophenol type developing agents, such as N methyl p aminophenol sulfate, p benzohydroquinone, catechol, Z-methyl hydroquinone, 2-chlorohydroquinone, p-aminophenol, and. pyrogallol.
• the developing solution should have a pH of from 10 to 13, depending upon the degree of activity of the particular hydrazine compound which it contains, although the preferred range with most hydrazine compounds is from pH 11 to pH 12.
• An ordinary, surface-type developer that is, one which develops an image only on the surface of the grains of an internal latent imageemulsion, is the following:
• Example I p-Hydroxyphenylglycine g Sodium carbonate (crystals) g 100 Water .to liter 1 Development time, 4 min. at C.
• An internal type developer that is, one which develops an image inside the grains of an internal latent image emulsion, is the following:
• Example II Hydroquinone g 15 Monomethyl-p-aminophenol su1fate -g 15 Sodium sulfite (anhydrous) r g 50 Potassium bromide -g 10 Sodiumhydroxide g Sodium thiosulfate (crystals) g 20 Water to liter 1 Development time, 3 min. at 20 C.
• the maximum density was increased by adding 5- methyl benzotriazole to the developer, for example, with phenyl hydrazine or p- [5- (methylsulfonamido) ethyl] phenyl hydrazine.
• the method of obtaining a direct positive image in a silver halide emulsion layer which comprises exposing to light rays to which the emulsion is sensitive, a silver halide emulsion layer a test portion of which upon exposure to a light intensity scale for a fixed time between M and 1 second and development for 3 minutes at 20 C.
• Grams Hydroquinone 15 Monomethyl-p-aminophenol sulfate l5
• Potassium bromide 10 Sodium hydroxide 25
• Sodium thiosulfate 20 Water to 1 liter gives a maximum density at least 5 times the maximum density obtained when the equally exposed silver halide emulsion is developed for 4 minutes at 20 C.
• the method of obtaining a direct positive image in a silver halide emulsion layer which comprises exposing to light rays to which the emulsion is sensitive, a silver halide emulsion layer a test portion of which upon exposure to a light intensity scale for a fixed time between /100 and 1 second and development for 3 minutes at 20 C. in the following internal type developer (II):
• the method of obtaining a direct positive image in a silver halide emulsion layer which comprises exposing to light rays to which the emulsion is sensitive, a silver halide emulsion layer a test portion of which upon exposure to a light intensity scale for a fixed time between /100 and 1 second and develoment for 3 minutes at 20 C.

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• Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Priority Applications (5)

Applications Claiming Priority (1)

Publications (1)

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Family Applications (1)

Country Status (5)

Cited By (22)

Families Citing this family (4)

• 0
  • BE BE502879D patent/BE502879A/xx unknown
• 1950
  • 1950-04-29 US US159150A patent/US2563785A/en not_active Expired - Lifetime
• 1951
  • 1951-04-28 FR FR1087759D patent/FR1087759A/fr not_active Expired
  • 1951-04-29 DE DEE3674A patent/DE877548C/de not_active Expired
  • 1951-04-30 GB GB10145/51A patent/GB702162A/en not_active Expired

Non-Patent Citations (1)

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