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
  • G03C1/04—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with macromolecular additives; with layer-forming substances
  • G03C1/053—Polymers obtained by reactions involving only carbon-to-carbon unsaturated bonds, e.g. vinyl polymers
• • 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
  • C08F20/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof
  • C08F20/02—Monocarboxylic acids having less than ten carbon atoms, Derivatives thereof
  • C08F20/52—Amides or imides
  • C08F20/54—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide
  • C08F20/56—Acrylamide; Methacrylamide
• • 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

Definitions

• the invention relates to the production of photographic silver halide emulsions.
• silver halide emulsions are prepared by combining aqueous solutions of silver nitrate and awatersoluble halide in the presence of a protective colloid whereby silver halide is precipitated.
• the purpose of the protective colloid during the precipitation is to prevent the agglomeration of the silver halide grains, to iniluence the grain distribution and to control the growth of the grain and also the formation of sensitivity centres during the physical and chemical ripening.
• gelatin has proved particularly suitable in practice as a protective colloid. It largely satisfies the photographic technical requirements which are demanded of a protective colloid.
• it does however have certain disadvantages, since it is a natural product, so that it is subject to certain fluctuations as regards quality and consequently shows changing photographic properties, which in certain circumstances cannot be detected during the processing operations, even with highly developed testing methods.
• it has the disadvantage that it is attacked by bacteria and is subject to a chemical degradation by hydrolysis during the manufacture and storage of the emulsions.
• copolymers of acrylamide, acrylic or methacrylic acids and acrylonitrile or methyl and vinyl ketones are used as dispersing agents for silver halide during the preparation of photographic emulsions.
• German patent specification No. 1,040,- 370 highly polymeric substances with a predominant proportion of acid and nitrile groups, more especially copolymers of acrylic acid and acrylonitrile, are recommended as binders for photographic layers. If necessary, these polymers can comprise a small proportion of acrylamide or vinyl alcohol units.
• the protective colloid properties which are necessary photographically such as for example control of the grain size during the precipitation and physical ripening and prevention of the agglomeration of the silver halide grains.
• Other plastics are only capable of limited use because they produce insoluble deposits with the aqueous solution of the silver nitrate.
• saturated alcohols is to be understood alcohols which are devoid of nonbenzenoid unsaturation, i.e., and aliphatic, cycloaliphatic, araliphatic alcohols.
• alcohols used for acrylic or methacrylic acid are:
• vinyl esters of a saturated aliphatic carboxylic acid with 1 to 20 carbons there are mentioned: vinyl acetate, vinyl propionate, vinyl butyrate and vinyl stearatec;
• olefinically unsaturated organic compounds containing acid groups are more especially those olefinically'unsaturated compounds which contain carboxylic, sulphonic or preparing the ester of phosphoric acid groups, such as acrylic acid, methacrylic acid, sorbic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, as well as their semi-esters with the above cited alcohols, vinyl sulphonic acid, styrene sulphonic acid, vinyl phosphonic acid and others.
• the protective colloids used according to the invention are prepared by known polymerization methods, and preferably by polymerization in Water in the presence of watersoluble radical formers.
• the aqueous .polymer solutions thus obtained can be directly used as a protective colloid solution.
• the silver halide emulsions prepared in the presence of the protective colloidsaccording to the invention do not have the disadvantages referred to above. They have important advantages over the silver halide emulsions prepared with known protective colloids.
• the aqueous solutions or emulsions of the copolymers according to the invention are stable at all pH values which are to be considered practically and do not produce with aqueous silver nitrate solutions any deposit which could disturb the processing.
• the copolymers are excellent film formers which can for example be cross-linked with formaldehyde and yield elastic films.
• the silver halide emulsions prepared with the protective colloids according to the invention can be quickly and quantitatively coagulated at pH values from 3 to 4, freed from the excess salts by a washing process, and thereafter the coagulate can easily be redispersed again by raising and lowering the pH value.
• the absolute concentration of the silver halide and also the ratio between protective colloid and silver halide can be varied within wide limits, and very highly sensitive silver halide emulsions are obtained with an extremely fine grain.
• the photographic materials prepared with the aid of the silver halide emulsions according to the invention are non-fogging and are distinguished by particularly good keeping qualities, even under unfavorable atmosphcric conditions.
• the aqueous solutions or emulsions of the protective colloid according to the invention are supplied and the aqueous solutions of the silver salt and Water-soluble halide are sibly with the addition of other photographic auxiliaries.
• the further processing step takes place in accordance with known processes.
• Example I 695 parts of water are placed in a stirrer-type vessel and 72.5 parts of methacrylamide, 25 parts of a a ueous solution of acrylamide, 22.5 parts of methyl acrylate and 2.5 parts of methacrylic acid are introduced 7 ,and homogeneously mixed while passing nitrogen over the mixture. The mixture is then heated to 75- C. and polymerized by adding 0.3 part of potassium persulphate. After 8 hours, the viscosity has risen considerably and a substantially 12% polymer solution is obtained.
• the emulsion is cast by known methods on to a layer support.
• Example 2 As described in Example 1, 620 parts of water are provided and'40 parts of methacrylamide, 310 parts of a 10% aqueous solution of acrylamide, 25 parts of vinyl acetate and Sparts of a 50% aqueous solution of acrylic acid are introduced and polymerization carried out as described therein. A substantially 10% aqueous polymer 3 solution is obtained.
• Example 3 As described in Example 1, 716 parts of water are provided and 78 parts of methacrylamide, 15 parts of ethyl acrylate, 3 parts of vinyl propionate and 8 parts 'of a 50% aqueous solution of acrylic acid are introduced and polme'rization takes place as described therein. A substantially 12% aqueous polymer solution is obtained.
• Example 4 are now simultaneously poured within 5 minutes at C. into a solution of 50 parts of the copolymer solution in 300 parts of water.
• the emulsion is thereafter subjected to a physical ripening for 30 minutes, and after adding parts of gelatin with a powerful ripening action, chemical ripening takes place at the same temperature over a period lasting 30 minutes.
• the emulsion is then cooled, provided with the necessary casting additives, such as optical sensitizer, wetting agent and hardening agent and cast.
• the gelatin can also be replaced by another'carrier colloid to which has been added the necessary quantity of chemical sensitizers.
• Example 5 As described in Example 1, 716 parts of water are provided and 79.5 parts of methacrylamide, 165 parts of ethyl acrylate and 8 parts of a 50% aqueous solution of acrylic acid are introduced and polymerization is peracid are added, the silver halide coagulating and settling very quickly. The precipitate is freed from the supernatant salt solution, washed several times with slightly acidified water, again redispersed with dilute sodium hyocyanate, thiosinamine, and sodium thiosulphateu After completing the ripening, the emulsion is cast by known 1 methods on to a supporting layer.
• the filmforming copolymer is a copolymer formed from approximately 72.5 parts of methacrylamide, 2.5 parts of acry1- amide, 22.5 parts of methyl acrylate, and 2.5 parts of methacrylic acid, all parts being by weight.

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• Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Engineering & Computer Science (AREA)
• General Physics & Mathematics (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Medicinal Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Colloid Chemistry (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)

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• 0
  • BE BE586983D patent/BE586983A/xx unknown
• 1959
  • 1959-01-27 DE DEA31211A patent/DE1202132B/de active Pending
• 1960
  • 1960-01-25 CH CH78160A patent/CH389399A/de unknown
  • 1960-01-26 GB GB2861/60A patent/GB902891A/en not_active Expired
  • 1960-01-26 US US4625A patent/US3167430A/en not_active Expired - Lifetime
  • 1960-01-27 FR FR816777A patent/FR1248730A/fr not_active Expired

Patent Citations (3)

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