US3366482A - Process for the preparation of silver halide emulsions by the flocculation method - Google Patents

Process for the preparation of silver halide emulsions by the flocculation method Download PDF

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Publication number
US3366482A
US3366482A US621117A US62111767A US3366482A US 3366482 A US3366482 A US 3366482A US 621117 A US621117 A US 621117A US 62111767 A US62111767 A US 62111767A US 3366482 A US3366482 A US 3366482A
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emulsion
silver halide
flocculating
gelatine
value
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US621117A
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Schaller Heinrich
Anderau Walter
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BASF Schweiz AG
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Ciba AG
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D239/00—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings
    • C07D239/02—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings
    • C07D239/24—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members
    • C07D239/28—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, directly attached to ring carbon atoms
    • C07D239/46—Two or more oxygen, sulphur or nitrogen atoms
    • C07D239/48—Two nitrogen atoms
    • 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

  • the flocculating agents are colorless compounds that contain at least one six-membered heterocyclic ring made up of 3 to 4 carbon atoms, at the most one halogen atom being bound to a carbon atom of said heterocyclic ring, at least one aromatic radical, and at least one acidic group imparting solubility in Water to the compound.
  • Thesix-membered heterocyclic ring which may be substituted by at the most one halogen atom, e.g. bromine, but more especially chlorine, may also contain other substituents, under the conditions of this flocculating process, no gelatine derivatives are formed together with the flocculating agents.
  • Photographic silver halide emulsions of all kinds, especially color emulsions, may be prepared by this process.
  • the present invention relates to a process for the preparation of photographic silver halide emulsions in which the extraneous soluble salts are removed by flocculation of the silver halide.
  • a water-soluble silver salt generally silver nitrate
  • Water-soluble halides in an aqueous gelatine solution.
  • the gelatine/silver halide emulsion thus formed contains water-soluble salts which are by-prodnets of the double decomposition reaction, and these salts have to be removed.
  • the conventional method of removing the salts consists in solidifying the emulsion by cooling, comminuting it, and then washing out the salts with cold water.
  • the flocculation method oflers 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, such as, for example, sodium sulfate.
  • an inorganic salt such as, for example, sodium sulfate.
  • a large amount of the inorganic salt is required, and the precipitate has to be removed by washing out.
  • 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 liquid. It has also been proposed to use the salts of heavy metals as flocculating agents.
  • gelatine derivatives can only be flocculated at a low pH value, for example, at a pH value of about 3.5.
  • highly sensitive ammonia emulsions such as are used in the preparation of X-ray films, this unavoidable depression of the pH value to about 3.5 brings about a loss in sensitivity of the emulsion.
  • the present invention is based on the observation that certain heterocyclic compounds are very suitable as flocculating agents. Accordingly, the present invention provides a process for the preparation of photographic silver halide emulsions by the flocculation method, which com-prises flocculating the emulsion at a pH of 3 to 7, and using as a flocculating agent a colorless compound containing (a) At least one six-membered heterocyclic ring made up of 3 to 4 carbon atoms, at the most one halogen atom being bound to a carbon atom of said heterocyclic ring;
  • the acidic group imparting solubility in Water present in a flocculating agent according to the invention may be, for example, a carboxylic acid group or a sulfato group, but is preferably a sulfonic acid group.
  • the said flocculating agent must also contain at least one six-membered heterocyclic ring that contains as ring members either 3 carbon atoms and 3 nitrogen atoms or 4 carbon atoms and 2 nitrogen atoms. This six-membered heterocyclic ring may be substituted by at the most one halogen atom and/ or other substituents. Examples of suitable heterocyclic rings are the pyridazine and pyrimidine rings. Compounds that contain at least one 1:3:5-triazine radical are particularly suitable.
  • the compound to be used as a flocculating agent in the process of the present invention must contain at least one aromatic radical, advantageously an aromatic radical of the benzene or naphthalene series.
  • the aromatic radical advantageously contains at least one substituent, for example, the group imparting solubility in Water, and is advantageously bound to the heterocyclic ring either directly or through a bridge, for example, a sulfur or oxygen atom, or preferably a nitrogen atom.
  • a 1:3:5-triazine compound may be substituted in, for example, each of the 2 and 4 positions by an aromatic radical of the kind defined.
  • the 6 position may have as a substituent a halogen atom, for example, bromine, but more especially chlorine.
  • the benzene or naphthalene radical may contain another substituent, for example, -a further sulfonic acid group, a carboxylic acid group, an alkyl group such as a methyl or ethyl group, an alkoxy group such as a methoxy or ethoxy group, a halogen atom such as chlorine, fluorine or bromine, or a .group of more complex structure, for example, a trifluoromethyl group or a sulfonic acid amide group.
  • substituent for example, -a further sulfonic acid group, a carboxylic acid group, an alkyl group such as a methyl or ethyl group, an alkoxy group such as a methoxy or ethoxy group, a halogen atom such as chlorine, fluorine or bromine, or a .group of more complex structure, for example, a trifluoromethyl group or a sulfonic acid amide group.
  • the efificacy of the flocculating agent is enhanced by increasing the size of the molecule.
  • Efiicacy is further increased by the incorporation of naphthalene radicals, such radicals advantageously being 1- or 2- amino-naphthalene-mono-, dior tri-sulfonic acids, which thus produce, for example, compounds of the formula R:NH
  • a process which comprises condensing a condensation product of equimolecular proportions of cyanuric chloride and an aromatic amino-sulfonic acid, especially an aminonaphthalene disulfonic acid, with an aliphatic or aromatic diamine in a molar ratio of 1:1 results in the formation of a fiocculating agent that contains a free amino group. It has been observed that such amino compounds are highly effective at pH values around and 6.
  • Theseamino compounds may also be further condensed with a suitable reactive halogen compound, for example, with a condensation product of equimolecular proportions of cyanuric chloride and an aromatic sulfonic acid already mentioned.
  • a suitable reactive halogen compound for example, with a condensation product of equimolecular proportions of cyanuric chloride and an aromatic sulfonic acid already mentioned.
  • flocculating agents that correspond to the formula in which R and R each represents a naphthalene radical containing at least one sulfonic acid group, and Z represents a bridge member.
  • Symmetrical compounds of the kind defined may also be prepared by condensing cyanuric chloride with aminonaphthalene sulfonic acids and diamines in a molar ratio of 2:2: 1, respectively.
  • n represents an integer of a value not greater than 5, 1 :4-diaminobenzene, 1 23-diaminobenzene-4-sulfonic acid, 1 I 3-diaminobenzene-4- or -5-ca rboxylic acid, 4:4-diaminodiphenyl, 4 4-diaminodiphenyl-2 Z'2'-diSlllfOniC acid, 4:4-diaminodiphenyl-3 :3'-dicarboxylic acid, 3 13'-dicarboxymethoxy-4:4'-diaminodiphenyl and. l Z5-diaminobenzene-3 :7-disulfonie acid.
  • Some of the flocculating agents in accordance with the invention may be prepared by conventional methods.
  • the following are a number of triazine compounds in accordance with the invention.
  • the triazine radical of the formula HOaIS (I31 NHL HNCH:-CH2-NHQ 1103's ('31 (J1 SOaH NHAHNCHa-CHr-NH NH I SOsH HOaS (23) B0 8 1130-?
  • the flocculating agents of the invention do not chemically react with gelatine forming gelatine derivatives and do not cause hardening of the gelatine when used in the small amounts required, even when flocculation is carried out with halogen triazine compounds which are reactive.
  • flocculation is advantageously brought about by adding an aqueous solution of the flocculating agent to the emulsion, and then adjusting the pH value of the emulsion to the requisite value.
  • the silver halide precipitates along with the gelatine or other colloid in the form of fine granules and settles out very quickly.
  • the precipitate contains only a very small amount of water so that it is generally not necessary to wash it out further. Should it appear necessary, however, the precipitate may be washed out once or several times with cold water; if necessary, the pH can be adjusted to a suitable value.
  • the pH value for flocculation is in the range of from 3 to 7, preferably 3 to 5, and the requisite amount of flocculating agent, for example, to 200% (calculated on the dry weight of the gelatine or other colloid) in the form of a dilute aqueous solution, depend not only on the flocculating agent itself, but also on the gelatine or other colloid concentration of the emulsion, the salt content, and other factors.
  • the temperature at which flocculation is carried out has no great influence; it is advantageously within the range of to C., and it should always be such that no substantial amounts of gelatine or of another colloid react with the flocculating agent, in so far as the latter contains reactive groups.
  • Photographic silver halide emulsions of all kinds may be prepared by the process of the invention, especially color materials that contain either dyestufi components for color development or image dyestuffs for the silver dyestufi bleaching process.
  • EXAMPLE 1 A solution of grams of silver nitrate in 600 milliliters of water is added in a period of 15 minutes at 50 C. to solution of 8 grams of gelatine, 44 grams of potassium bromide and 1 gram of potassium iodide in 600 milliliters of water. The mixture is allowed to mature for 10 minutes at 50 C. and is then cooled to 40 C. 30 milliliters of a aqueous solution of the compound of Formula 20 is then added, and the pH of the emulsion is adjusted to 4.5 to 5.0 by the addition of citric acid.
  • the nature of the acid used has no influence on the flocculation process; acetic acid, hydrochloric acid, sulfuric acid or any other acid with a sulflcient degree of acidity can also be used.
  • the silver halide precipitates at once along with the gelatine in the form of finely divided granules and settles out very quickly.
  • the supernatant salt solution is decanted oif.
  • a solution of 120 grams of gelatine in 1400 milliliters of water and having a temperature of 40 C. is added to the granules, and the pH value is adjusted to 7.0 by the addition of aqueous sodium hydroxide solution.
  • the silver halide is redispersed by stirring for to 20 minutes at 40 C., and the emulsion is allowed to mature to optimum sensitivity in a known manner at 50 to 55 C.
  • Solutions of the compounds listed in the following Table I may also be used to bring about flocculation of silver halide/ gelatine emulsions by the above method instead of a solution of the compound of Formula 20.
  • the amounts required, concentrations and pH values are also listed. All compounds yield emulsions having the same photographic properties.
  • the compound of the Formula 20 can be prepared as follows:
  • the secondary condensation product can be obtained by salting out (that is, by the addition of 25 parts of sodium chloride per 100 parts by volume of the reaction mixture).
  • the product is the compound shown by the Formula 20.
  • This product may then be further condensed at 40 C. with the primary condensation product described above to process the compound of the Formula 28.
  • the compounds of the Formulae 23 to 26 may be prepared by the above method when, instead of trichlorotn'azine, equivalent proportions of 2-methoXy-4:6-dichloro-l :3 :S-triazine, 3-methoxy-4z5 -trichloropyridazine, 224:6 trichloropyrimidine or 4:5:6 trichloropyrimidine are used.
  • EXAMPLE 2 A solution of 50 grams of silver nitrate in 450 milliliters of water is added during a period of 20 minutes at a temperature of 65 C. to a solution of 5 grams of gelatine, 42 grams of potassium bromide and 2.2 grams of potassium iodide in 450 milliliters of Water. The mixture is allowed to mature for 15 minutes at 65 C. and is then cooled to 45 C. 20 milliliters of a 5% aqueous solution of the compound of the Formula 18 are added and the pH value is adjusted to 4.5 with citric acid. The silver halide along with the gelatine flocculates at once in the form of fine granules and settles out rapidly.
  • the silver halide is redispersed in a solution of grams of gelatine in milliliters of water having a pH value of 7.2, and the emulsion is then allowed to mature to its optimum sensitivity in the conventional manner.
  • a process for the manufacture of a photographic silver halide emulsion by the flocculating method which comprises flocculating the emulsion at a pH of 3 to 7, starting the emulsion to flocculate immediately after the first addition of flocculating agent, using as the flocculating agent a colorless compound containing (a) at least one six-membered heterocyclic ring made up of 3 to 4 carbon atoms, at the most one halogen atom being bound to a carbon atom of said heterocyclic ring,
  • a process according to claim 1 for the manufacture of a photographic silver halide emulsion by the flocculating method which comprises flocculating the emulsion at a pH of 3 to 7, starting the emulsion to flocculate immediately after the first addition of flocculating agent, using 11 12 as the fiocculating agent a colorless compound containing 6.
  • a process according to claim 1 for the manufacture (a) at least one triazine radical, at the most one haloof a photographic silver halide emulsion by the flocculatgen atom being bound to a carbon atom of said triing method, which comprises flocculating the emulsion at azine radical.
  • a process according to claim 1 for the manufacture azme radlcal of a photographic silver halide emulsion by the flocculat- (b) at least one aromailc f and ing method which comprises flocculating the emulsion at (c) at least one sulfonlc acid group and the ad usta PH of 3 to 5 using as the fiocculafing agent the ment of the pH to a value of 3 to 7.
  • a process according to claim 1 for the manufacture C1 of a photographic silver halide emulsion by the flocculating method which comprises flocculating the emulsion at Hogs pH of 3 to 7 using as the flocculating agent a colorless N N compound of the formula H, O
  • a process according to claim 1 for the manufacture 9.
  • R and R' each represents a naphthalene radical UNITED STATES PATENTS containing at least one sulfonic acid group, the emulsion 3,138,461 6/1964 Ryan 96-94 starting to flocculate immediately on the addition of the 3,288,775 11/1966 Anderau et al 961l1 u i g ag t and the adjustment of the pH to a value of 3 to 7.
  • J. TRAVIS BROWN Acting Primary Examiner.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Colloid Chemistry (AREA)
  • Separation Of Suspended Particles By Flocculating Agents (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Silver Salt Photography Or Processing Solution Therefor (AREA)
  • Plural Heterocyclic Compounds (AREA)
US621117A 1962-09-13 1967-03-07 Process for the preparation of silver halide emulsions by the flocculation method Expired - Lifetime US3366482A (en)

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CH1085062A CH420851A (de) 1962-09-13 1962-09-13 Verfahren zur Herstellung photographischer Silberhalogenidemulsionen nach der Ausflockungsmethode

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BE (1) BE637343A (en))
CH (1) CH420851A (en))
DE (1) DE1238330C2 (en))
ES (1) ES291610A1 (en))
GB (1) GB1041085A (en))
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3455694A (en) * 1965-06-15 1969-07-15 Ciba Ltd Process for the preparation of photographic silver halide emulsions by the flocculation method
US3522053A (en) * 1965-02-06 1970-07-28 Fuji Photo Film Co Ltd Process for the preparation of photographic emulsions
US3615789A (en) * 1966-06-28 1971-10-26 Ciba Ltd Process for the manufacture of enriched colloidal silver

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3138461A (en) * 1960-06-10 1964-06-23 Polaroid Corp Process for preparing silver halide emulsions containing gelatin derivatives
US3288775A (en) * 1961-04-07 1966-11-29 Ciba Ltd Method of hardening gelatin by reacting with conjugated heterocyclic compounds containing halogen atoms and water-solubilizing acid groups

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE484325A (en)) * 1947-08-13
BE600141A (en)) * 1960-03-15
FR1279110A (fr) * 1960-03-15 1961-12-15 Koepff & Sohne G M B H Procédé de préparation d'émulsions d'halogénures d'argent, notamment pour la photographie et émulsions conformes à celles obtenues

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3138461A (en) * 1960-06-10 1964-06-23 Polaroid Corp Process for preparing silver halide emulsions containing gelatin derivatives
US3288775A (en) * 1961-04-07 1966-11-29 Ciba Ltd Method of hardening gelatin by reacting with conjugated heterocyclic compounds containing halogen atoms and water-solubilizing acid groups

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3522053A (en) * 1965-02-06 1970-07-28 Fuji Photo Film Co Ltd Process for the preparation of photographic emulsions
US3455694A (en) * 1965-06-15 1969-07-15 Ciba Ltd Process for the preparation of photographic silver halide emulsions by the flocculation method
US3615789A (en) * 1966-06-28 1971-10-26 Ciba Ltd Process for the manufacture of enriched colloidal silver

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Publication number Publication date
DE1238330C2 (de) 1974-04-18
BE637343A (en))
NL297840A (en))
ES291610A1 (es) 1964-02-16
CH420851A (de) 1966-09-15
NL142245B (nl) 1974-05-15
AT239054B (de) 1965-03-10
GB1041085A (en) 1966-09-01
DE1238330B (de) 1967-04-06

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