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
  • G03C1/015—Apparatus or processes for the preparation of emulsions

Definitions

• One object of my invention is to provide a method for preparing washed silver halide emulsions in which the silver halide may be coagulated without the necessity of altering the pH thereof. Another object of my invention is to provide a method for washing fine grained emulsions in which the tendency to form grain clumps is diminished. Another object of my invention is to provide a method for preparing washed silver halide emulsions in which change of the pH of the mass is not necessary to obtain coagulation of the emulsion. A further object of my invention is to provide a method of purifying a gelatin emulsion in which the salts of certain metals have been found to be quite useful.
• gelatin derivatives which I have found to be useful as peptizers for dispersing silver halide for preparing washed emulsions in accordance with my invention are the aromatic sulfonyl chloride derivatives of gelatin, the
• gelatin the carcarboxylic acid chloride boxylic anhydride derivatives of gelatin, the aromatic isocyanate derivatives of gelatin and the l,4-diketone derivatives of gelatin.
• the preparation of these gelatin derivatives is known in the prior art as disclosed, for example, in U. S. Patent No. 2,614,929 of Yutzy and Russell, October 21, 1952.
• the reaction products of any of the with. gelatin may be employed for that purpose.
• the salts which I have foundto be useful for coagulating dispersions of silver halide in gelatin derivatives are the watersoluble salts of cadmium; zinc, aluminum, iron,
• v the metal salt which gives maximum coagulation will vary depending upon; the particular salt. employed, the temperature of the dispersion and the pH of the emulsion at the time of coagulation. For instance, in thecase of a dispersion-of silver halide in a gelatin derivative having a temperature of 30 C. and a pH of the-amount of cadmiumchloride which will give optimum result's'has been: foundto. be approximately 15.5 grams per mol of silver .halide.
• the liquid portion thereof is removed from the settled portion such as by decantation.
• the silver halide may then be redispersed by adding water to the particle mass, preferably with the use of a slightly elevated temperature and if desired, a washing withwater having a temperature of 10 C. may be employed prior to redispersion. If desired, the dispersion may be recoagulated by again adding salt and decanting off the mother liquor. Upon redispersion it is desirable to 'addthereto a solution of a carrier for the silver halide such as gelatin or far-hydrolyzed cellulose acetate to form a photographic emulsion of the desired silver halide concentration.
• a carrier for the silver halide such as gelatin or far-hydrolyzed cellulose acetate
• Example 1 potassium chloride and 2.6 grams of potassium iodide in 3000 cc. of distilled water at 60 C. This wasaccomplished by-adding thesilver nitrate solution to the second.
• a dispersion of silver halide was preparedby mixinga solution of 400 grams of silver nitrate in 3600 cc. .of distilled water at 30 C. with a solution of 59 grams of benzene sulfonyl chloride gelatin derivative, 142 grams of potassium chloride and 57 grams of potassium bromide dissolved in 3400 cc. of distilled water at 30 C.
• the silver nitrate solution was added to the alkali halide gelatin solution over a period of approximately 2 minutes .with good stirring.
• the dispersion thus formed was heated to 40 C. and the mass was found to have a pH of 5.95.
• a dispersion of silver halide in gelatin derivative was prepared by mixing a solution of 400 grams of 'silver nitrate in 4100 cc. of distilled water at 72 C. with a solution 'of 59 grams of n-heptyl succinic anhydride gela- 1 tin derivative, 330 grams of potassium bromide and 6 grams of potassium iodide in 3400 cc. of distilled water at 70 C.
• the silver nitrate solution was added to the second solution over a period of approximately 5 /2 minutes with good stirring, the temperature having beenmaintained at 70 C.
• the dispersion was then stirred for 20 minutes at 70 C. and cooled at 40 C.
• Example 4 A dispersion of silver halide was prepared in substantially the same manner as described in Example 3 but 59 grams of a hexahydrophthalic anhydride derivative of gelatin was employed instead of the n-heptyl succinic anhydride gelatin derivative. The coagulation was induced by the use of lanthanum nitrate rather than cadmium chloride. The emulsion finally obtained was coated onto a cellulose acetate film support and Was exposed and developed as in the preceding example. The emulsion was found to have the following characteristics:
• the salts which may be employed for coagulating silver halide dispersions in accordance with my invention may be any of the water soluble salts of the metal referred to. This would include the nitrates or chlorides of all of the metals listed although in many cases other salts would be useful providing the negative ion of the salt does not have any adverse eifect photographically or otherwise on the silver halide dispersion.
• a process of preparing a washed silver halide dispersion the steps which comprise preparing a dispersion of silver halide in an aqueous solution of a gelatin derivative selected from the group consisting of the aromatic sulfonyl chloride derivatives of gelatin, the carboxylic acid chloride derivatives of gelatin, the carboxylic acid anhydride derivatives of gelatin and the aromatic isocyanate derivatives of gelatin, coagulating that dispersion while at a pH of 4.5- by adding thereto 1/2-20 grams, per mole of silver halide, of a water soluble salt selected from the water soluble salts of cadmium, zinc, aluminum, iron, nickel, chromium and lanthanum whereby silver halide-gelatin granules form and separating those granules from the liquid portion of the mass.
• a gelatin derivative selected from the group consisting of the aromatic sulfonyl chloride derivatives of gelatin, the carboxylic acid chloride derivatives of
• a method of preparing a washed silver halide dispersion the steps which comprise forming a dispersion of silver halide in an aqueous solution of a benzene sulfonyl chloride gelatin derivative, coagulaing that dispersion while at a pH of 4.5l0 by adding thereto an aqueous solution of 1/2-20 grams per mole of silver halide of a salt selected from the water soluble salts of cadmium, zinc, aluminum, iron, nickel, chromium and lanthanum whereby silver halide-gelatin granules are formed and separating the thus formed granules from the liquid portion of the mass.
• a method of preparing washed silver halide dispersions the step which comprises forming a dispersion of silver halide in an aqueous solution of hexa hydro phthalic anhydride-gelatin derivative, coagulating that dispersion while at a pH of 4.5-10 with 1/2-20 grams of lanthanum nitrate per mole of silver halide whereby silver halide-gelatin granules are formed and separating those granules from the liquid portion of the mass.
• a method of preparing washed silver halide dispersions the steps which comprise forming a dispersion of silver halide in an aqueous solution of a N-heptyl succinyl anhydride derivative of gelatin, coagulating that dispersion while at a pH of 4.5-10 by adding thereto an aqueous solution of 1/2-20 grams of cadmium chloride per mole of silver halide whereby silver halide-gelatin granules are formed and separating those granules from the liquid portion of the mass.
• a method of preparing washed silver halide dispersions the steps which comprise forming a dispersion of silver halide in an aqueous solution of a benzene sulfonyl chloride derivative of gelatin, coagulating the silver halide dispersion while at a pH greater than 4.5 and not more than 10 by adding thereto an aqueous solution of 1/2-20 grams of cadmium chloride per mole of silver halide whereby silver halide-gelatin granules are formed and separating those granules from the liquid portion of the mass.
• a method of preparing a washed silver halide dispersion the steps which comprise forming a dispersion of a silver halide in an aqueous solution of a gelatin derivative selected from the group consisting of the aromatic sulfonyl chloride derivatives of gelatin, the carboxylic acid chloride derivatives of gelatin, the carboxylic acid anhydride derivatives of gelatin and the aromatic isocyanate derivatives of gelatin, coagulating the silver halide dispersion while at a pH of 4.5-10 by adding thereto an aqueous solution of 1/2-20 grams of cadimum chloride per mole of silver halide whereby silver halide-gelatin granules are formed and separating those granules from the liquid portion of the mass.
• a gelatin derivative selected from the group consisting of the aromatic sulfonyl chloride derivatives of gelatin, the carboxylic acid chloride derivatives of gelatin, the carboxylic acid anhydride derivatives of gelatin and the aromatic
• a gelatin derivative selected from the group consisting of the aromatic sulfonyl chloride derivatives of gelatin, the carboxylic acid chloride derivatives of gelatin, the carboxylic acid anhydride derivatives of gelatin and the aromatic isocyanate derivatives of gelatin, having a pH of 4.5-10 coagulating that dispersion without adjustment of the pH thereof by adding thereto 1/ 2-20 grams per mole of silver halide of a water soluble cadmium salt whereby silver halide-gelatin granules form and separating those granules from the liquid portion of the mass.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Colloid Chemistry (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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Cited By (7)

Citations (2)

• 0
  • BE BE535054D patent/BE535054A/xx unknown
• 1954
  • 1954-01-25 US US406061A patent/US2768079A/en not_active Expired - Lifetime
• 1955
  • 1955-01-21 FR FR1121979D patent/FR1121979A/fr not_active Expired
  • 1955-01-21 GB GB1942/55A patent/GB764446A/en not_active Expired

Patent Citations (3)

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