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
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
  • G03C1/42—Developers or their precursors
• • 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

Definitions

• a layer of a direct positive emulsion which is a fogged gelatino silver halide emulsion containing at least 95 mole percent of silver chloride and a desensitising agent effective to sensitise the Herschel effect to produce direct positive characteristics.
• a layer of a water permeable colloid and a developing agent for the emulsion is deposited and dried in less than 50 seconds.
• a thin waterpermeable layer may be placed between the emulsion and developer layers.
• This invention relates to photographic materials and processes and more particularly to photographic materials which are adapted to be processed to yield positive images directly.
• photographic emulsions which, on exposure and development, yield a positive image directly may be made by including in a silver chloride emulsion (which may contain a small proportion of silver bromide or silver iodide, e.g. up to mol percent) a small proportion of a desensitising compound and fogging the emulsion by light or by chemical means.
• a silver chloride emulsion which may contain a small proportion of silver bromide or silver iodide, e.g. up to mol percent
• a desensitising compound e.g. up to mol percent
• a known process of producing photographic prints is to employ as the print material a material which carries a layer of photographic silver halide emulsion which contains a photographic developing agent, imagewise expose the material, treat it with an alkali bath in order to activate the development (a so-called activator .bath) thereby producing a silver image in the material, and then treat the material with a bath (a so-called stabiliser bath) containing a substance which, by complexing with the residual silver halide in the material inhibits its lightsensitivity, thus stabilising the photograhic print thus obtained.
• a bath a so-called stabiliser bath
• the print obtained is necessarily a negative record of the original document and if a positive record is required it is necessary to make a print from an intermediate negative record first obtained.
• a phtographic material which comprises, on -a support, a layer of a direct positive photographic emulsion which is a fogged gelatino silver halide emulsion of which at least mol percent of the silver halide is silver chloride, and which contains a desensitising agent effective to sensitise the Herschel effect to produce direct positive characteristics, and a separate layer of a water-permeable colloid containing a developing agent for the photographic emulsion.
• the layers may be located in either order on the support and may be contiguous or separated by a thin waterpermeable colloid layer.
• the support may be paper or film as conventionally used for photographic materials.
• the first layer applied to the support should be substantially dried before the second layer is applied.
• the provision of a simple thin layer of water-permeable colloid between the emulsion layer and the developer-containing layer assists in avoiding risk of migration of developer and the technique of drying down the layers as rapidly as possible is also advantageous in this respect.
• the photographic emulsion layer may be formulated in any manner known per se for direct positive emulsions relying on the Herschel effect and is preferably an emulsion prepared as described in any of British patent specifications Nos. 871,938, 873,937, 875,887, 905,237 and 907,367. It will for preference usually be a fine-grained gelatino silver chloride emulsion fogged by treatment with formaldehyde and containing the desensitiser in a proportion of about 1 to 10 grams per gram mol of silver present. It is found generally preferable to apply the emulsion to film or paper base at a silver coating weight of 0.8 to 2.0 grams silver per square metre and a gelatin coating weight of 1 to 10 grams per square metre.
• the developer-containing layer is preferably a gelatin layer and the developer used is preferably hydroquinone. It is preferably laid down, optionally after the application of a thin gelatin layer to the emulsion surface, at a gelatin coating weight of 1.0 to 1.5 grams per square metre and a hydroquinone coating weight of 0.3 to 0.8 gram per square metre.
• Example 4.4 litres of a washed photographic emulsion containing 188 grams of silver chloride and adjusted to pH 10 was treated with 12 ml. of a 4% by Weight aqueous solution of formaldehyde. The emulsion was heated at 52 C. for 35 minutes and was then neutralised by the addition of citric acid and cooled. There was then added the compound l(2-pyridyl)2(4-pyridyl)ethylene bisbenzyl bromide at the rate of 3.3 grams per gram mol of silver present. The pH of the emulsion was adjusted to 6.0 and the emulsion was coated on paper base and dried in 70 to 100 seconds. The silver coating weight was 1.3 to 1.5 grams per square metre.
• the material thus prepared was then imagewise exposed with light not containing ultra-violet or blue Wavelengths. It was then processed by activation and stabilisation by passing it through a roller system applying to it, in succession, thin layers of an aqueous activator solution containing 60 grams per litre of sodium hydroxide and 50 grams per litre of sodium sulphite (cryst.), and an aqueous stabiliser solution containing, per litre, 280 grams of ammonium thiocyanate, 5 grams of sodium sulphite (anhydrous), 32 grams of sodium metabisulphite, 5 grams of 1- phenyl-S-mercaptotetrazole and 200 mol of industrial ethyl alcohol.
• an aqueous activator solution containing 60 grams per litre of sodium hydroxide and 50 grams per litre of sodium sulphite (cryst.)
• an aqueous stabiliser solution containing, per litre, 280 grams of ammonium thiocyanate, 5 grams of sodium
• the material also provides excellent prints by conventional processing using a fiXing bath.
• a process for the production of a photographic material which comprises applying to a support a first layer of a direct positive photographic emulsion which is a fogged gelatino silver halide emulsion of which at least 95 mol percent of the silver halide is silver chloride and which contains a desensitizing agent efiective to sensitise the Herschel efiect to produce direct positive characteristics,
• drying the first layer applying to the dried first layer a second layer of an aqueous solution of water-permeable colloid and a developing agent for the photographic emulsion and drying the said second layer in less than 50 seconds.
• the first layer is a fine-grained gelatino silver chloride emulsion fogged by treatment with formaldehyde and containing a sensitiser for the Herschel elfect in a proportion of 1 to 10 g. per gram mol of silver halide present.

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• Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• General Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)
• Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)

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Publications (1)

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Cited By (4)

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Citations (3)

Family Cites Families (2)

• 1963
  • 1963-08-28 GB GB34090/63A patent/GB1012860A/en not_active Expired
• 1964
  • 1964-07-30 US US386391A patent/US3372031A/en not_active Expired - Lifetime
  • 1964-08-11 NL NL6409231A patent/NL6409231A/xx unknown
  • 1964-08-20 BE BE652103A patent/BE652103A/xx unknown
  • 1964-08-26 CH CH1116464A patent/CH425461A/fr unknown
  • 1964-08-26 FR FR986303A patent/FR1405108A/fr not_active Expired
  • 1964-08-27 DE DEI26461A patent/DE1296000B/de active Pending

Patent Citations (3)

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