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
  • C08F20/62—Monocarboxylic acids having ten or more carbon atoms; Derivatives thereof
• • 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
  • C08F26/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen
  • C08F26/06—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen by a heterocyclic ring containing nitrogen

Definitions

• Photographic silver halide emulsions are prepared by the flocculation method which consists in precipitating the gelatine silver halide emulsion With a flocculating agent, separating it from the supernatant salt solution and then again dispersing it in a gelatine solution.
• the flocculating agent is added at a pH .of 3 to 5 to the gelatine silver halide emulsions and consists of a linear additive copolymer prepared mainly from N-vinylethylene urea, N-vinyloxazolidone or N-vinylpyrrolidone and a water soluble salt of acrylic or methacrylic acid. to 70 mol percent of the vinyl compound and 30 to 85 mol percent of the acrylic or methacrylic acid salt are'used in the copolymer preparation.
• the present invention provides a process for the manufacture of photographic silver halide emulsions in which the extraneous soluble salts are removed by flocculation of the silver halide.
• a water-soluble silver salt usually silver nitrate
• a Water-soluble halide in an aqueous gelatine solution.
• the gelatine/ silver halide emulsion thus formed contains Water-soluble salts which are byproducts of the double decomposition, and these salts have to be removed.
• the usual method of removing the said salts consists in solidifying the emulsion by cooling, comminuting it, and then washing out the salts with cold water.
• Another method known as the flocculation method, consists in precipitating the silver halide emulsion, separating it from the supernatant salt solution, and then again dispersing it in a gelatine solution or in some other suitable layer colloid.
• the flocculation method otters a number of advantages; in particular, it makes possible the preparation of concentrated silver halide emulsions.
• Various methods of flocculating silver halide emulsions have been proposed, for example, flocculation with an inorganic salt, for example, sodium sulfate.
• an inorganic salt for example, sodium sulfate.
• a large amount of inorganic salt is required, and has to be removed by washing the precipitate.
• Organic solvents can also be used for bringing about flocculation but this method is expensive and the precipitates obtained are highly voluminous and still contain a large amount of Water.
• the present invention provides a process for the preparation of photographic silver halide emulsions by the flocculation method. wherein there are used as flocculating agents water-soluble, linear additive copolymers which consist mainly of polymer units of (l) 15 to mol percent of a ring saturated 2-oxo-N- vinyl heterocyclic compound, and
• Suitable 2-oxo-N-vinyl heterocyclic compounds are hetero cyclics of an aliphatic character having a sixor advantageously five-membered saturated ring.
• One of the ring members is a nitrogen atom carrying a vinyl group in a-position to this a carbonyl group.
• the other atoms forming the ring are carbon, nitrogen or oxygen, and the carbon and nitrogen atoms may also carry a lower alkyl radical.
• N-vinyl heretocyclic compounds there may be mentioned pyrrolidone, piperidone, pyrazolidone, ethylene, urea, trimethylene urea and oxazolidone compounds.
• N-vinyl-oxazolidone but above all the compounds of the Formula 1, that is to say, N-vinyl-N:N'-ethylene urea and especially N-vinylpyrrolidone.
• copolymers are used that contain 15 to 70 mol percent, advantageously .25 to 50 mol percent of the vinyl heterocyclic compound.
• comonomeric compounds there are used 30 to 85 mol percent, advantageously 50 to 75 mol percent, of a Water-soluble salt of acrylic acid or methacrylic acid, for example, a calcium, ammonium or an alkali metal salt such as a sodium or potassium salt, especially sodium acrylate.
• the copolymers are made up primarily of structural units of the aboye-mentioned composition (1) and (2); however, they may also contain a small amount, for example, up to 10% of the copolymer, of other kinds of polymer units, for example, vinyl esters of aliphatic alcohols.
• copolymers of the kind used in the present invention is known.
• polymerization is carried out in an aqueous medium at 40 to C. and with the aid of a water-soluble, freeradical forming catalyst that is not harmful to photographic properties, for example, potassium persulfate.
• the compounds of the composition given above can be used as flocculating agents in the. customary manner. These materials can be exceedingly effective and depending on their constitution, small amounts produce very good flocculation at pH values between 3 and S, preferably 4.0 and 4.5, at a moderately raised temperature.
• flocculation is advantageously brought about by adding an aqueous solution of the flocculating agent to the emulsion, and then adjusting the emulsion to the requisite pH value. It is also possible first to adjust the pH value and then add the flocculating agent. In general, only a small amount of flocculating agent is required. The amount used also depends on the gelatine content,
• the salt concentration and the pH value The amount required for a specific case can easily be determined by preliminary tests.
• the silver halide precipitates along with the gelatine in the form of fine granules and settles very quickly.
• the precipitates contain only a very small amount of water so that a further washing is generally not necessary. Should it appear necessary, however, the precipitates can be washed once or several times with cold water, the pH being adjusted to a suitable value, if necessary.
• the most suitable pH value for flocculation and the requisite amount of flocculating agent depend not only on the flocculating agent itself, but also on the gelatine content of the emulsion, the salt content, and other factors.
• the temperature at which flocculation is carried out has no great influence; in general, it is advantageously between 30 and 50 C.
• Photographic silver halide emulsions of all kinds can be prepared by the process of the invention, especially color materials that contain either dyestuff components for color development or image dyestuffs for the silver dyestufl bleaching process.
• the flocculating agents to be used in the process of the present invention have an important advantage in that the small amount of flocculating agent present in the coagulate has a stabilizing influence on the emulsion so that emulsions of maximum sensitivity and free from turbidity can be obtained. Moreover, the small amount of fiocculating agent acts as a plasticizer, which means that elastic layers of high break resistance, for example, as required for positive cinema film, can be obtained.
• the pH By adjusting the pH to a value between 6.5 and 7.5, the coagulates can easily be redispersed in water or gelatine solution at a temperature between 35 and 50 C. Other colloids can also be used for redispersion.
• Example A solution of 50 grams of silver nitrate in 450 milliliters of water is added to a solution of grams of gelatine, 42 grams of potassium bromide and 2.2 grams of potassium iodide in 450 milliliters of water at 65 C. in the course of 20 minutes.
• the mixture is allowed to mature for minutes at 65 C., and then cooled to 35 C.
• 20 milliliters of a 10% aqueous solution of a copolymer comprising 25 mol percent of N-vinylpyrrolidone and 75 mol percent of sodium acrylate are then added, and the pH value is adjusted to 4.0 by the addition of l N sulfuric acid.
• the silver halide precipitates along with the gelatine and the polymer and settles out very quickly.
• the supernatant clear liquid is decanted and the granular precipitate washed with 1 liter of cold water to which sulfuric acid has been added in an amount sufficient to adjust the pH value to 4.0.
• a solution of 70 grams of gelatine in 800 milliliters of water is then added and the pH value adjusted to 7.0 by the addition of 0.1 N sodium hydroxide solution.
• the whole is stirred for 10 to minutes at 40 C. until the silver halide is redispersed, and then allowed to mature to its optimum sensitivity in the customary manner.
• An emulsion is obtained which exhibits a moderate to high degree of sensitivity, depending on the kind of gelatine used.
• a process for the manufacture of a photographic silver halide emulsion by the flocculation method which comprises adding to the gelatine silver halide emulsion at a pH of 3 to 5 as a flocculating agent a linear additive copolymer which consists mainly of polymer units of (1) 15 to 70 mol percent of N-vinylethylene urea, and
• a process for the manufacture of a photographic silver halide emulsion by the flocculation method which comprises adding to the gelatine silver halide emulsion at a pH of 3 to 5 as a flocculating agent a linear additive copolymer which consists mainly of polymer units of (1) to 70 mol percent of N-vinylpyr-rolidone, and (2) 30 to 85 percent of a water-soluble salt of an acid of the formula wherein n is a whole number of at the most 2.
• a process for the manufacture of a photographic silver halide emulsion by the flocculation method which comprises adding to the gelatine silver halide emulsion at a pH of 3 to 5 as a flocculating agent a linear additive copolymer which consists of polymer units of mol percent of N-vinylethylene urea and 75 mol percent of sodium acrylate.
• a process for the manufacture of a photographic silver halide emulsion by the flocculation method which comprises adding to the gelatine silver halide emulsion at a pH of 3 to 5 as a flocculating agent a lineary additive copolymer which consists of polymer units of 25 mol percent of N-vinyloxazolidone and 75 mol percent of sodium acrylate.
• a process for the manufacture of a photographic silver halide emulsion by the flocculation method which comprises adding to the gelatine silver halide emulsion at a pH of 3 to 5 as a flocculating agent a linear additive copolymer which consists of polymer units of 25 mol percent of N-vinylpyrrolidone and 75 mol percent of sodium acrylate.
• a process for the manufacture of a photographic silver halide emulsion by the flocculation method which comprises adding to the gelatine silver halide emulsion at a pH of 3 to 5 as a flocculating agent a linear additive copolymer which consists of polymer units of 50 mol percent of N-vinylpyrrolidone and 50 mol percent of sodium acrylate.
• a process for the manufacture of a photographic silver halide emulsion by the flocculation method which comprises adding to the gelatine silver halide emulsion at a pH of 3 to 5 as a flocculating agent a linear additive copolymer which consists of polymer units of 66 mol percent of N-vinylpyrrolidone and 34 mol percent of sodium acrylate.
• a process for the manufacture of a photographic silver halide emulsion by the flocculation method which comprises adding to the gelatine silver halide emulsion at a pH of 3 to 5 as a flocculating agent a linear additive copolymer which consists of polymer units of mol percent of N-vinylpyrrolidone and 30 mol percent of calcium acrylate.
• a process for the manufacture of a photographic silver halide emulsion by the flocculation method which comprises adding to the gelatine silver halide emulsion at a pH of 3 to 5 as a flocculating agent a linear additive copolymer which consists of polymer units of '25 mol percent of N-vinylpyrrolidone, 70 mole percent of sodium acrylate and 5 mol percent of vinyl acetate.
• a process for the manufacture of a photographic silver halide emulsion by the flocculation method which comprises adding to the gelatine silver halide emulsion at a pH of 3 to 5 as a flocculating agent a linear additive copolymer which consists of polymer units of 66 mol percent of N-vinylpyrrolidone and 34 mol percent of sodium methacrylate.
• a process for the manufacture of a photographic silver halide emulsion by the flocculation method which comprises adding to the gelatine silver halide emulsion at a pH of 3 to 5 as a flocculating agent a linear additive copolymer which consists of polymer units of -15 mol percent of N-vinylpyrrol-idone and mol percent of ammonium methacrylate.
• a process for the manufacture of a photograhpic silver halide emulsion by the flocculation method which comprises adding to the gelatine silver halide emulsion at a pH of 3 to 5 as a flocculating agent a linear additive copolymer which consists of polymer units of 40 mol percent of N-vinylpyrrolidone and 60 mol percent of potassium methacrylate.

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

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  • NL NL301289D patent/NL301289A/xx unknown
• 1962
  • 1962-12-04 CH CH1420062A patent/CH441994A/de unknown
• 1963
  • 1963-12-03 DE DEC31574A patent/DE1212839B/de active Pending
  • 1963-12-03 AT AT966063A patent/AT245928B/de active
  • 1963-12-03 US US327837A patent/US3360373A/en not_active Expired - Lifetime
  • 1963-12-03 BE BE640736A patent/BE640736A/xx unknown
  • 1963-12-03 ES ES0294129A patent/ES294129A1/es not_active Expired
  • 1963-12-04 GB GB47976/63A patent/GB1005404A/en not_active Expired

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