Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D235/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, condensed with other rings
  • C07D235/02—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, condensed with other rings condensed with carbocyclic rings or ring systems
• • 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
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
  • Y10S430/141—Direct positive material

Definitions

• a direct positive photographic element comprising a fog silver halide emulsion containing as a deep sensitizer 1,3 substituted-2,3-dihydro-2 oxocycloheptimidazolium salts.
• This invention relates to a direct positive light-sensitive silver halide photographic material which comprises a support and, coated thereon, a light-sensitive silver halide emulsion layer containing fogged silver halide crystals, said layer having a desensitizer incorporated therein, said desensitizer being a compound represented by the general formula wherein R is alkyl, substituted or unsubstituted aryl, or substituted or unsubstituted aralkyl radical; R is substituted or unsubstituted aryl radical or substituted or unsubstituted aralkyl radical; R is hydrogen, halogen, alkyl or phenyl radical; and X is an anion. It is the principal object of the invention to provide a direct positive, light-sensitive silver halide photographic material having high reversal sensitivity and high contrast and being free from any staining of photographic surface.
• a direct positive, light-sensitive silver halide photographic material of the kind specified which comprises a fogged silver halide emulsion, can directly yield a positive image through a single exposure and single development by utilization of Herschel effect, solarization, dye reversal (spectrally sensitized reversal), etc.
• an appropriate desensitizer into the fogged silver halide emulsion before coating.
• desensitizers for direct positive light-sensitive silver halide photographic materals, which compounds include, for example, phenosafranine, malachite green, pinacryptol yellow, pinacryptol green, etc.
• phenosafranine which is a substance having red color usually causes reddish coloration of the photographic materials, sometimes wtih decrease in contrast.
• Marachite green and pinacryptol green both of which are green compounds, will decrease whiteness of the background of photographic pictures.
• pinacryptol green sometimes has an adverse effect against stability of a fogged emulsion.
• Pinacryptol yellow which is a generally preferred known desensitizer because of its raising no problem in contrast of photographic images, will cause yellowish coloration to decrease whiteness of the surface ice of photographic materials.
• all the known desensitizers are not satisfactory because of their undesired influence on the photographic properties.
• a direct positive, light-sensitive silver halide photographic material which comprises a light-sensitive silver halide emulsion layer containing fogged silver halide crystals and having a compound of the above general formula, as a desensitizer, incorporated therein.
• the compounds defined above are available at relatively low costs. Almost all of these are colorless substances, but a few have a very sight color insufiicient to cause coloration.
• the compounds can meet the following requirements:
• a compound of the above general formula can be prepared according to the method described in Chemical & Pharmaceutical Bulletin vol. 13, No. 7, pages 819-820, that is by the reaction of a troponeimine derivative of the formula NHRI M.P. 182 C.
• 1,3-dibenzyl-6hromo-2,3-dihydro-2-0Xocycl0heptimidazolium chloride sensitizer will be within the range of 0.005 to 0.5 g. per 100 g. of silver nitrate, the amount of which is calculated from the silver halide contained in the emulsion. However, this is not so a strict range and it is possible, with out any adverse effect, to use an amount slightly outside of said range. Usually it is preferred to dissolve the desensitizer in water, or a water-miscible organic solvent (e.g. a lower alcohol or acetone) or the mixture of both to have a solution which is then added to the emulsion containing fogged silver halide crystals.
• a water-miscible organic solvent e.g. a lower alcohol or acetone
• Suitable additives or adjuvants e.g. stabilizer, coating aid, film hardener, matting agent, etc.
• suitable additives or adjuvants e.g. stabilizer, coating aid, film hardener, matting agent, etc.
• the thus prepared emulsion is coated on a suitable support in the manner known per se and then dried, thereby to obtain a direct positive, lightsensitive silver halide photographic material, which is entirelyfree from any staining or coloration of photographic surfaces and which can yield a Very clear positive image with high contrast and with high whiteness of the reversed portion.
• EXAMPLE 1 One kilogram of a pure silver chloride emulsion containing the equivalent to 40 g. of silver nitrate was buffered to pH 8.0 by the addition of 30 m1. of 6% aqueous sodium metaborate solution. This emulsion was added further with 7 ml. of 3% formalin and heated at 50 C. for 60 minutes. The thus fogged emulsion was buffered to pH 6.0 with 10% aqueous citric acid solution and then divided to ten portions, each of which was added with the compound indicated in Table 1. The respective portions were coated on photographic papers and then dried.
• the sheets according to the present invention were more excellent in the reversal sensitivity and contrast than the control sheets.
• the sheets of the invention were entirely safe from coloration, whereas the control sheet loaded with pinacryptol yellow or safranine suffered from yellowish or reddish coloration.
• EXAMPLE 2 One kilogram of a silver chloroiodide emulsion containing the equivalent to 40 g. of silver nitrate was buffered to pH 7.5 by the addition of 25 cc. of 5% aqueous sodium carbonate solution. 10 ml. of 3% formalin was also added thereto and the resulted emulsion was heated at 55 C. for 40 minutes. The fogged emulsion was divided to ten portions, each of which was added with the compound indicated in Table 2. The respective portions were coated on photographic papers and then dried. The thus prepared ten direct positive, light-sensitive photographic sheets were subjected to imagewise exposure to White light and then treated with a developing solution. The sensitometric results obtained are set forth below:
• the sheets according to the present invention were more excellent in the reversal sensitivity and contrast than the control sheets and further they were entirely safe from any coloration.
• a direct positive, light-sensitive silver halide photographic material which comprises a support and, coated thereon, a light-sensitive silver halide photographic emulsion layer containing fogged silver halide crystals and a desensitizing amount of a compound of the general formula wherein R is alkyl, substituted or unsubstituted aryl or substituted or unsubstituted aralkyl; R is substituted or unsubstituted aryl or substituted or unsubstituted aralkyl; R is hydrogen, halogen, alkyl or phenyl; and X- is an anion.

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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)
• Indole Compounds (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Applications Claiming Priority (1)

Publications (1)

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Citations (2)

• 1967
  • 1967-03-13 US US622437A patent/US3506451A/en not_active Expired - Lifetime
  • 1967-03-16 DE DE19671572185 patent/DE1572185A1/de active Pending
  • 1967-03-17 BE BE695697D patent/BE695697A/xx unknown
  • 1967-03-17 GB GB02583/67A patent/GB1173983A/en not_active Expired
  • 1967-03-17 FR FR99365A patent/FR1514857A/fr not_active Expired

Patent Citations (2)

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