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
  • G03C1/08—Sensitivity-increasing substances
  • G03C1/09—Noble metals or mercury; Salts or compounds thereof; Sulfur, selenium or tellurium, or compounds thereof, e.g. for chemical sensitising

Definitions

• Claim. (Cl. 95--7) formation of silver sulfide on the surface of the silver halide crystal or results inv the formation of small amounts of silver from the reduction of silver halide, which effect may be in addition to the former etfect sometimes known as sulfur sensitizing.
• the present invention is con cerned primarily with chemical sensitization apparently of the latter type.
• One object of our invention is to provide chemically sensitized silver halide emulsions of enhanced sensitivity.
• Another object is to provide photographic emulsions having sensitivity enhanced by a combination of sulfur, gold and polyarnine sensitizing agents; A further object is to provide the methods of augmenting emulsion sensitivity utilizing the novel combination of sensitizing agents. Another object is to provide photographic elements in which the novel emulsions are useful. Further objects triethylene tetramine or tetra'ethylene pen-tamine, tetrap'ropyl-ene pen-tarni-ne, and the like. The compounds have the general structure Where n is a positive integer from one to five, preferably 7 allyl isothiocyanate, thiocarb'anilide, sodium thiosulfate,
• the objects of our invention are accomplished by incorporating into silver halide emulsions a mixture of (A) a polyamine compound such as spertnine which has the formula i or a pol'yarnine compound such as diethylene triamine,
• Example 3 In a positive type of silver bromoiodide emulsion were incorporated 20 milligrams of allyl thiourea per mol of silver halide and 2 milligrams of potassium chloroaurate per mol of silver halide and the emulsion was digested for 61 minutes at 62 C. A sample of the emulsion was coated onto film base.
• emulsions F, G and H were exposed in the 1b sensitometer anddeveloped for 3 minutes in the developer of Example 2.
• the characteristics of emulsions F, G and H are shown in the table following.
• Example 4 A portion of the finished emulsion I was treated with 0.050 gram of TET per mol of silver halide and held for 30 minutes at 40 C. and then coated on a film. (L) A portion of the finished emulsion I was treated with 0.100 gram of TET per mol of silver halide and held for 30 minutes at 40 C. and then coated on a film. After exposure of the emulsion coatings in an Eastman Type IB Sensitometer, the samples were developed 5 minutes in a developer of the following composition:
• the exposed and processed emulsion coatings containing the polyamine sensitiers were found to have increased in speed as shown in the table following (samples I, J, K and L).
• Example 5 Toa medium grain size gelatino-silver bromoiodide emulsion was added a sulfur sensitizer such as described above, and a gold salt sensitizing agent such as described above. The emulsion was then digested to optimum sensitivity and a portion coated on film.
• Example 2 The emulsion samples M, N and 0 were exposed and developed (4 minutes) as in Example 2 and the characteristics of the coatings are tabulated in the table following (samples M, N and 0).
• Example 6 A fine-grained negative type gelatino-silver bro moiodide emulsion was sensitized with a sulfur sensitizcr such as described above and a gold salt sensitizing agent such as described above. The emulsion was then digested to optimum sensitivity and a sample coated on film.
• Emulsion samples R, S and T were treated the same as emulsion sample Q except using 0.02, 0.04 and 0.06 gram of TET per mol of silver halide respectively.
• Example 2 The emulsion samples PT prepared above were exposed and developed (4 minutes) as in Example 2 and the sensitometric characteristics of the coatings are tabulated in the table following (samples P-T).
• the quantity of the three sensitizing agents in the silver halide emulsions is not especially critical and can vary somewhat from the optimum amounts indicated in the above examples. For example, from about /5 to 5 times as much polyamine sensitizer can be used.
• a useful procedure to employ in sensitizing the emulsions with the three sensitizing agents involves final digestion of the emulsions at a pH below neutrality of the order of 6.0.
• Emulsion 1A can be regulated to pH 6.0, the polyamine compound then added followed by digestion. Quite unexpectedly we are thus able to suppress fog which might be expected to arise through extended digestion.
• emulsions are suitable to use in forming single as well as multilayer film useful in color photography which customarily include on a support two 6 or more emulsion layers sensitized to difierent regions silver halide sensitized with a sulfur sensitizing agent, a of the visible spectrum and may or may not contain cougold salt sensitizing agent and triethylene tetramine.
• Such color films carry at least one emulsion layer containing the mentioned combination of sensitizing agents.

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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)
• Coloring (AREA)

Priority Applications (4)

Applications Claiming Priority (1)

Publications (1)

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Cited By (6)

Citations (5)

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• 1952
  • 1952-11-08 US US319616A patent/US2743182A/en not_active Expired - Lifetime
• 1953
  • 1953-11-05 FR FR64174D patent/FR64174E/fr not_active Expired
  • 1953-11-06 GB GB30700/53A patent/GB734474A/en not_active Expired
  • 1953-11-08 DE DEE8090A patent/DE972720C/de not_active Expired

Patent Citations (5)

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