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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F8/00—Chemical modification by after-treatment
  • C08F8/34—Introducing sulfur atoms or sulfur-containing groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F2800/00—Copolymer characterised by the proportions of the comonomers expressed
  • C08F2800/20—Copolymer characterised by the proportions of the comonomers expressed as weight or mass percentages

Definitions

• the present invention is directed to the production of silver halide emulsions for photographic purposes and more particularly to an improved method for the flocculation step ofthe silver halide in the making of the photographic composition.
• flocculating agents are, for instance, sulfates of the alkali or alkaline earth metals which, added in large amount to the photo graphic emulsions, eliminate the protective action of the gelatine for silver halide, both in the acid and in the alkaline pH range, by removing water from the gelatine micelles.
• flocculating agents are for instance gelatine derivatives, i.e. gelatines which have, for instance, been benzylated on an amino group.
• the emulsions prepared with these derivatives are flocculatable, as for instance, in case of the use of anionic soaps as flocculating agents only in acid pH ranges, about 3.5,
• the invention is intended and adapted to overcome the difliculties and disadvantages inherent in the production of photographic compositions of the silver halide type, it being among the objects thereof to provide a process in which the use of large quantities of sulfates is avoided and in particular wherein such use of sulfates may be eliminated.
• the method of producing photographic silver halide emulsions is characterized by the fact that for the flocculation, copolymers of vinyl pyridine sulfonic acid or vinyl pyridine disulfonic acid with a monomeric substance such as acrylic acid, styrene sulfonic acid or the like are used.
• the new flocculating agents are copolymers of vinyl pyridine sulfonic acid or vinyl pyridine disulfonic acid with any monomeric substance capable of polymerizing.
• the decisive factor in connection with these products is the introduction of the sulfonic acid radical or the disulfonic acid radical onto-vinyl pyridine since it has been found that only thereby does flocculation in the alkayine pH range become possible;
• the monomers which are copolymerized are as follows:
• Acrylic acid -Acrylic acid-I-acrylate Acrylic acid-i-acrylonitrile Acrylic acid+styrene sulfonic acid Methacrylic acid Acrylic acid ester Methacrylic acid ester Methylchloracrylic acid ester Acrylonitrile Methacrylonitrile Acrylamide Styrene sulfonic acid Divinyl benzene sulfonic acid
• This invention is specific examples of the operation of this invention:
• Example 1 A mixture of 3 ml. of 4-vinyl pyridine in 27 ml. of acrylic acid is introduced into a solution of 0.15 gram of K S O in 60 cc. of water at 50 C. and polymerized in the customary manner.
• the anhydrous copolymer is thereupon sulfated with concentrated sulfuric acid and 100 mg. of cadmium chloride at 120 C. forabout one hour. Thereupon, it is neutralized to a pH of 8 with sodium hydroxide solution and the sodium sulfate is removed by crystallization;
• Solution H a solution of Solution H are introduced into I, whereupon the emulsion is cooled to 30 C. and brought to a pH of 8.5 by means of 25% sulfuric acid.
• the flocculation is eflected by the addition of 70 cc. of the 2% solution of the above described copolymer.
• the supernatant solution can now be poured off and the product washed with water as many times as desired.
• the flocculate is thereupon dispersed in a solution of 35 grams of gelatine in 600 cc. of water and aged until optimum sensitivity is obtained.
• Example 2 A mixture of 28.5 grams of styrene and 1.5 grams of vinyl pyridine is introduced at 60 C. into a solution of 60 cc. of water, 0.3 gram of lauryl sulfate, 0.03 gram of sodium phosphate and 0.5 gram of K S O and polymerized by further heating.
• the dry copolymer is then sulfated with concentrated sulfuric acid and mg. of cadmium chloride for 1 hour at C., and then dissolved in water. Thereupon it is brought to a pH of 8, by means of sodium hydroxide solution.
• the resultant sodium sulfate is preferably allowed to crystallize out of the concentrated solution which is then diluted so that there is present an approximately 2% solution of the copolymer.
• the fiocculating agent thus obtained can be used in the following boiling emulsion.
• Example 3 The copolymer of styrene sulfonic acid and vinyl pyridine sulfonic acid described in Example 2 can also be used .in the following ammonia emulsion, in which within a pH range of 11-12, the flocculation is supported by sodium sulfate and there is produced a readily washable flocculate.
• Process for the production of photographic silver halide emulsions which comprises providing a gelatine emulsion of silver halide, in Water, mixing said emulsion with the sulfonated copolymer of vinyl pyridine and a polymerizable monomer selected from the class consisting of acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile, styrene sulfonic acid, divinyl benzene sulfonic acid, and acrylamide, and flocculating said emulsion in alkaline medium to form a silver halide flocculate, separating said fiocculate from the reaction mixture, and then dispersing said fiocculate in a gelatine solution.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Separation Of Suspended Particles By Flocculating Agents (AREA)

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ID=7221953

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Citations (6)

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• 0
  • BE BE600141D patent/BE600141A/xx unknown
• 1960
  • 1960-03-15 DE DEK40170A patent/DE1140813B/de active Pending
• 1961
  • 1961-02-07 GB GB4510/61A patent/GB911886A/en not_active Expired
  • 1961-02-08 US US87787A patent/US3178294A/en not_active Expired - Lifetime

Patent Citations (6)

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