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

• This invention relates to fog-inhibiting agents and stabilizers for photographic emulsions and to photographic emulsion-s containing them.
• Photographic fog is of two types: local and general. Local fog is formed by exposure of the film or plate at undesired points as by a light leak in the camera. General fog is formed in a number of ways. It may be caused by. the
• emulsion such as conditions of high temperature or humidity or unusually long time of storage.
• the nature of the emulsion may also produce general fog as well as the conditions of development of the emulsion as by development for protracted periods of time or at temperatures above normal.
• We are primarily concerned with fog and sensitivity changes produced in films or plates on development after storage under adverse conlcjitirons of high temperature and humidity or General fog and loss of sensitivity of the emulsion are especially likely to occur when the sensitive material is stored under conditions other than ideal, that is, under conditions of high temperature and humidity as in tropical regions.
• a further object is to provide antifogging agents which stabilize the initial sensitivity of the emulsion.
• a still further object is to provide anti-fogging agents which improve the keeping of the emulsion in tropical regions.
• an anionic palladium complex salt such as alkali metal or alkaline earth metal thiocyanato palladites, nitritopalladites, bromo-nitritopalladates, and ammonlum nitritopalladite.
• potassium thiocyanato palladite mPd(CNS)4; calcium thiocyanato palladite, CaPd(CNS)4; potassium nitrito palladite, K2Pd(NO2)4; barium nitrito palladite, BaPd(NO2)4; potassium bromonitrito palladate, K2PdBr2(NO2)4, or ammonium nitritopalladite, (NH4)2Pd(NO2)4.
• Other similar anionic palladium complexes which have not been satisfactory, particularly because of fog- 5 Claims.
• "(01. 95-7) -2 ging properties or desensitizing action on the photographic emulsion include ammonium and potassium cyano palladites and ammonium thiocyanato palladite.
• the object of our invention is to maintain the sensitivity and fog of silver halide emulsion at or close to initial optimum values under keeping conditions of high temperature and humidity.
• the fog inhibitors which we propose to use are added to the emulsion during the process of manufacture to avoid loss of sensitivity and to inhibit the growth of incubation or keeping fog with passage of time under non-ideal conditions of storage.
• a solution of the compounds of the invention when added in suitable concentration before coating to unsensitized or optically sensitized photographic emulsions does notaiiect appreciably the sensitometric values for sensitivity and fog when measurements are made soon after coating.
• sensitometric measurements are made after appreciable intervals of time under tropical or dry conditions of storage at elevated temperatures, however, the compounds stabilize photographic speed and in certain cases maintain fog at a low level.
• the preparation of silver halide emulsions involves three separate operations, (1) the emulsification and digestion or ripening of the silver halide, (2) the freeing of the emulsion from excess soluble salts usually by washing, (3) the second digestion or after-ripening to obtain increased sensitivity (Mees, The Theory of the Photographic Process, 1942).
• the most useful concentration range of fog inhibitor is from 0.26 to 3.9 gm. of fog inhibitor per kilogram of silver nitrate used in making the emulsion and converted to silver halide. This amount will vary, e. g., depending upon the particular silver halide used.
• the antifoggant and stabilizing action was determined by incubation of the emulsions under simulated tropical conditions and also by incubation in dry heat at F. for various lengths of time from 6 days to 2 months. The results of these ageing tests are tabulated below and are compared with the initial speed, gamma and fog of the emulsion without th stabilizing compounds.
• the tests from which the following tabulation was made used a high-speed orthochromatic negative type of emulsion exposed on an EastmanfI ype sensitometer' and develq oped for five minutes in a developer of the following composition:
• the fog inhibitor is dissolved in water follows:
• Examples of the method oi preparatiomand use of the compounds orthemvehuta are-elven 40
• the compound was added to the emulSiondn'the-" quantity shown in the tabla above and the emiilsion containing the usual 'hardener and 1 sensitizew was coa'ted on a glass*plate driei exposed and developed.
• the emulsion is coated ona suitable supv 1 por-t, glass;-fi1m,- or -other,- and dried inanormal fashion; 7 I
• the compounds maylbe used in a colloid layer-suchasa geiauri' subbin'gor overcoating layer contiguous" tofadJ'acent to, or n contact with the emulsionla'yei'.
• a colloid layer suchasa geiauri' subbin'gor overcoating layer contiguous" tofadJ'acent to, or n contact with the emulsionla'yei'.
• the compounds stabili'z'e'thfe emulsiori'when it is aged over long periods of time especially under non-ideal con-- ditibris'of temperature and humidity.
• theamount of the compound per unit area should be the -same; per kilogram" of silv'er nitifat convertedt silver halide, as would be used 3 ili'tll' saini'llfiit' area of the emulsion if'the com pouriaweredn the emulsiofi'la'yerl v
• the fog' inhibitih'g ,age'rits' whichwe have' de-" scribed" may .bdu'sed iii va ious kinds of hoto graphic emulsions.
• the dispersing agents may be gelatin or other colloid such as collodion, albumen, cellulose derivatives, or synthetic resins.
• an anionic palladium complex salt selected from the group consisting of alkali metal and alkaline earth metal thiocyanato palladites, alkali metal and alkaline earth metal nitritopalladites, alkali metal and alkaline earth metal bromo-nitritopalladates and ammonium nitritopalladite.
• a silver halide emulsion containing an alkali metal thiocyanato palladite 1.
• a silver halide emulsion containing an alkali metal nitritopalladite 3.
• a silver halide emulsion containing ammonium nitritopalladite 4.

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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)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)

Priority Applications (4)

Applications Claiming Priority (1)

Publications (1)

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Family Applications (1)

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Cited By (4)

Citations (2)

• 0
  • BE BE487512D patent/BE487512A/xx unknown
• 1948
  • 1948-03-05 US US13352A patent/US2472631A/en not_active Expired - Lifetime
• 1949
  • 1949-03-02 FR FR982271D patent/FR982271A/fr not_active Expired
  • 1949-03-07 GB GB6142/49A patent/GB657805A/en not_active Expired

Patent Citations (2)

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