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
• • 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
  • G03C1/04—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with macromolecular additives; with layer-forming substances
  • G03C1/047—Proteins, e.g. gelatine derivatives; Hydrolysis or extraction products of proteins

Definitions

• This invention relates to the prevention of coagulation in photographic emulsions containing gelatin derivatives by incorporating a small amount of an organic amide in the emulsion.
• divalent salts such as salts of lead, zinc, manganese, cadmium, etc.
• divalent salts such as cadmium chloride
• the addition of divalent salts to photographic emulsions is described in U.S. Patent No. 2,839,405 and Glafkides Photographic Chemistry, vol. I, p. 318.
• the addition of divalent salts to silver halide emulsions which contain gelatin derivatives has been found to cause a certain amount of coagulation or formation of insoluble particles. Thus this affects uniform coating operations and is usually undesirable in the making of photographic products.
• a silver halide photographic emulsion in whose preparation a gelatin derivative acid coagulation wash procedure was used, contains an organic amide such as dimethyl formamide or the like, that divalent salt antifoggants may be added to this emulsion or the pH thereof may be appreciably lowered and the emulsion thus treated will show no coagulation or formation of settled particles therein.
• a support such as film base or paper base coatings of good uniformity are obtained.
• My invention is applicable to various silver halide 3,359,110 Patented Dec. 19, 1967 emulsions whether the silver halide is silver chloride, silver bromoiodide, or some other type of silver halide grain, the grains having been prepared and washed by a gelatin derivative acid coagulation Wash procedure. This may involve either the preparation of the silver halide grains initially in the gelatin derivative as the peptizer for the silver halide or the grains may have been prepared in some other peptizer such as gelatin and the gelatin derivative was mixed therewith prior to the acid coagulation by which the grains were separated from the liquid portion of the silver halide dispersion.
• the silver halide dispersion is first prepared, dispersed in a gelatin derivative such as an acid anhydride or acid chloride derivative of gelatin.
• a gelatin derivative such as an acid anhydride or acid chloride derivative of gelatin.
• a coagulum is formed which is separated from the aqueous liquid containing the water soluble salts. If desired, the coagulum may be then washed in cold water.
• the photographic emulsion is formed by redispersing the coagulum in an aqueous solution of a vehicle, at a suitable pH, which vehicle may be gelatin, 2.
• gelatin derivative, a synthetic resin vehicle such as polyvinyl alcohol or for hydrolyzed cellulose ester.
• organic amide is then added to the emulsion which amide inhibits any coagulation effect which might be experienced in further treatments of the emulsion especially as might result by the addition of cadmium chloride or such other divalent salt or in lowering the pH of the emulsion for some purpose.
• Example 1 A silver halide emulsion was prepared following the procedure described in Example 5 of U.S. Patent No. 2,614,928. The total gelatin present was 75 grams per mole of silver halide and the weight of the emulsion was divided into equal parts. To one part of the emulsion, 15 cc. of dimethyl formamide was added. There was then added to each portion 2 /2 grams of cadmium chloride. The portion to which the dimethyl formamide had been added was stable upon standing whereas that to which the cadmium chloride had been added without the previous addition of dimethyl formamide appeared grainy and non-uniform in nature.
• Example 2 An emulsion was prepared in the same manner as in the preceding example except that the alkali metal salt used in preparing the silver halide was a mixture of sodium chloride and potassium bromide in a 65:33 chloro-. bromide ratio instead of potassium bromide and potassium iodide.
• the washed silver halide emulsion thus prepared was divided into equal parts. To one part was added 15 cc. of dimethyl formamide while to the other portion no addition was made prior to lowering the pH to 4 which was done with both portions of the emulsion.
• the emulsion to which the dimethyl formamide had been added was found to be stable and upon standing retained its normal appearance. That which had been acidified without the previous addition of dimethyl formamide showed grain and non-uniformity after a short time of standing.
• Example 3 A fine grain silver chlorobromide emulsion was prepared as described in the preceding example but using a ratio of 80 mole percent chloride and 20 mole percent bromide and the gelatin derivative used as the peptizer was a maleic anhydride derivative of gelatin as described in Example 6 of U.S. Patent No. 2,614,928. The emulsion was divided into several portions each of which contained .05 mole of silver halide, and about 2 grams of the gelatin derivative. Various amides were added to the various portions except for number 1 in the amounts shown in the appended table. Each portion was poured into a separate 50 ml. graduated cylinder and 1 ml. of a 1.84 M cadmium chloride solution was added to each portion. The various graduated cylinders were placed in a constant temperature bath at 41 C. and held for three hours. The table indicates the results in each case.
• Example 4 A photographic emulsion was prepared as described in Example 1 except that the gelatin derivative employed was a m-carboxy benzene sulfonyl derivative of gelatin. The emulsion was put through the same procedure as described in the preceding example and the following re- An additional advantage for the use of organic amide in acid coagulated gelatin derivative washed emulsions resides in the stabilizing of those emulsions against coagulation when those emulsions are mixed with acid resins such as alkyl acrylate-acrylic acid copolymers, e.g. a butyl acrylate-acrylic acid copolymer.
• acid resins such as alkyl acrylate-acrylic acid copolymers, e.g. a butyl acrylate-acrylic acid copolymer.
• Examples of acid polymeric latices as well as water-soluble acid polymer solutions which tend to coagulate silver halide emulsions containing gelatin derivatives are cellulose ether esters of the type described in U.S. Patent No. 2,725,293; acrylateacrylic acid copolymers of the type described in U.S. Patent No. 3,062,674; carboxylated polyvinyl acetals of the type described in U.S. Patent No. 3,003,879; dibasic acid esters of polyvinyl alcohol as described in U.S. Patent No. 3,000,741.
• a silver halide photographic emulsion in accordance with claim 1 containing a divalent salt 11.
• a silver halide photographic emulsion in accordance with claim 1 containing a cadmium salt is provided.
• a silver halide photographic emulsion in accordance with claim 1 containing cadmium chloride 13.
• a silver halide photographic emulsion in accordance with claim 7 containing a cadmium salt 14.
• a silver halide photographic emulsion in accordance with claim 8 containing a cadmium salt 16.

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Citations (5)

• 1964
  • 1964-04-13 US US359418A patent/US3359110A/en not_active Expired - Lifetime
• 1965
  • 1965-03-09 BE BE662343A patent/BE662343A/xx unknown
  • 1965-04-09 GB GB15128/65A patent/GB1089322A/en not_active Expired
  • 1965-04-12 DE DE19651472825 patent/DE1472825A1/de active Pending

Patent Citations (5)

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