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
  • G03C1/34—Fog-inhibitors; Stabilisers; Agents inhibiting latent image regression
  • G03C1/346—Organic derivatives of bivalent sulfur, selenium or tellurium

Definitions

• R1 and: R2 are: either, hydrogen or alkyl; aryl or aralkyimolecular:groupsbut are not both hydrogen.
• This formula. is. shown in, the keto form; but all tau'tomeric; forms. are included in the scope of:th,ei invention.
• dithiourazoles may be prepared by treating the corresponding substituted hydra-Z0. dithiocarbonamide with hydrochloric acid or caustic. soda. solution as described in fBerichteder Deutschen Chemischen Gesel'lschaiit, 192 2,-vo1. l, page/35,2 (55th year).
• Gelatino silver chloride emulsions containing a dithioura-zole compound are capable of producing. a higher. maximum: black after hot glazing than does such; an emulsion. containing, one of the compounds previously proposed for this 40 purposetor example, a, monomercapto triazolel.
• the dithiourazolev compound may be incorporated in the emulsion as an addition,conveni'entls in the form. of a solution of the free substance or one of its salts, during. or subsequent to. the
• preparationof the emulsion preparationof the emulsion.
• Other methods of bringing the compound inoperative contact with the emulsion may be used such as including it in the subcoat, supercoat, backing layer; a filter layer, or in the wrapping material.
• the dithiourazole compounds do not cause so great a reduction in speed as that which results from the use of some of the other compounds hitherto proposed. This is particularly the case with certain substituted dithiourazoles such as the l or 4 phenyl dithiourazole where the quantity required for use as an improver has a practically negligible effect on speed and contrast.
• certain other dithiourazole compounds when used in the free state, may cause a slight alteration in the photographic properties of the emulsion.
• the addition should preferably be made after the final digestion period rather than at an earlier stage of emulsion manufacture. If stabilization against fog is the improvement required, then obviously the dithiourazole compound must be in operative contact with the emulsion during keeping and before development.
• dithiourazole compounds in the photographic material, and should he wish to use a dithiourazole compound which in its free state would have an adverse effeet on the emulsion, this may be accomplished without this adverse effect by using it in the form of a metal salt which is substantially water insoluble but decomposable by treatment of the photographic element in a processing bath subsequent to development.
• the silver salt of a dithiourazole compound is most useful when added to the emulsion or to a layer in contact with the emulsion.
• Other metal salts may be used, including thallous, ferric, and copper salts.
• the metal salt it is advisable for the metal salt to be in a fine state of subdivision in the layer in which it is incorporated.
• a convenient method of achievin this is to deposit the metal salt in situ in the colloidal medium in which it is dispersed, by the double decomposition of a water soluble metal salt and a water soluble salt of the dithiourazole compound in gelatine solution.
• the quantity of the dithiourazole compound or its soluble salt employed varies with the purpose for which it is used, and with the method adopted for bringing it into operative contact with the emulsion.
• the quantity of the dithiourazole compound or its soluble salt employed varies with the purpose for which it is used, and with the method adopted for bringing it into operative contact with the emulsion.
• from 1 cc. to 40 cc. of /1000 solution per litre of emulsion is suitable if the improvement required is stabilization, particularly of a fast negative emulsion, and it is advisable to select a compound for use which has little or no detrimental effect on the properties of the emulsion such, for example, as an aryl substituted dithiourazole.
• the quantity suitable for a litre of emulsion is from 1 cc. to '70 cc. of /1000 solution.
• the solution may be in water or in a water miscible organic solvent which does not have a detrimental efiect on the emulsion. If the additions are made to colloids which are to be coated adjacent to the emulsion layer, then higher quantities are preferable, approximately twice the quantity that would be used for a similar quantity of emulsion being required. These quantities are not given to limit the invention but merely as an indication of the order of the quantity of the compound to be used to give the best results.
• Example 1 Three separate l-lb. quantities of a negative gelatino silver iodo bromide emulsion having a silver content equivalent to 20 gms. silver nitrate per l-lb. of emulsion were taken and panchromatized. To one part was added the normal coating additions and it was coated on to glass plates (material A). The second quantity was coated after 13 cc. of /1000 spirit solution of 4-. phenyl 3.5 dithiourazole had been added (material B). The third quantity was coated after 13 cc. of /1000 spirit solution of 1 phenyl 3.5 dithiourazole had been similarly added (material C).
• Example 3 l /z-lbs. of gelatino silver chloride emulsion were coated in the normal manner on to paper (material A). To another l /2-lbs. of the same emulsion were added 12 cc. of 1000 spirit solution of 4 phenyl 3.5 dithiourazole and the emulsion Condition. of'incu- Maximum Material density after Pgfig 3 552 hot glazing ment p 1. 55 Slight yellow stain.
• Example 4 This was performed to show the effect of varying the quantity of the improver. To l -lbs. quantities of a gelatino silver chloride emulsion were added various quantities of 4 phenyl 3.5 dithiourazole, and the emulsions were coated on to paper and tested as in Example 2, with the following results:
• Example 5 This was performed to compare the effect of a substituted dithiourazole in the emulsion with its efiect when included in a supercoat, and with the effect of a much larger quantity of its silver salt in the emulsion.
• Material A was a standard Gaslight emulsion coated on to paper and coated with a standard gelatine supercoat.
• Material B was as material A, but with cc. of 4 phenyl dithiourazole added per l /z-lbs. of emulsion.
• Material C was as material A, but with 70 cc. of 4 phenyl dithiourazole per litre of supercoat.
• Material D was as material A, but with an addition to the emulsion of the silver salt of 4 phenyl dithiourazole. This was prepared by adding the chemical equivalent of silver nitrate to 60 cc. of a l gelatine solution of 0.3 gm. of the sodium salt of l phenyl 3.5 dithiourazole.
• R1 and R2 are constituents selected from the following groups: hydrogen, alkyl, aryl and aralkyl, but are not both hydrogen.
• a photographic material as claimed in claim 4 in which the said substance is present in the proportion of between 1 cc. and 70 cc. of /1000 solution of. the substance per litre of gelatino silver halide emulsion.
• a photographic material which includes a gelatino silver halide emulsion and a substance having the following formula 40 wherein R1 and R2 are constituents selected from the following groups: hydrogen, alkyl, aryl and aralkyl but are not both hydrogen.
• a photographic material which includes a gelatino silver halide emulsion and 4 phenyl 3.5 dithiourazole.
• a photographic material which includes a support and a plurality of layers coated thereon, at least one of these layers comprising a gelatino silver halide emulsion, and at least one of these layers containing 4 phenyl 3.5 dithiourazole.
• a photographic material which includes a gelatino silver halide emulsion layer in which is incorporated a compound selected from the group consisting of substituted dithiourazoles and the metal salts of substituted dithiourazoles wherein the substituted dithiourazole has the. formula:
• R1 and R2 are constituents selected from the following group: hydrogen, alkyl, aryl and aralkyl, but are not both hydrogen, and wherein the metal salts of substituted dithiourazole in accordance with said formulas are selected from the group consisting of silver, thallium, ferric iron and copper.

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

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Cited By (4)

Citations (6)

• 0
  • BE BE474822D patent/BE474822A/xx unknown
• 1946
  • 1946-07-25 GB GB22202/46A patent/GB614701A/en not_active Expired
• 1947
  • 1947-07-15 US US761159A patent/US2534599A/en not_active Expired - Lifetime
  • 1947-07-25 FR FR950146D patent/FR950146A/fr not_active Expired

Patent Citations (6)

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