US3153594A - Process for preparing photographic emulsions - Google Patents

Process for preparing photographic emulsions Download PDF

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Publication number
US3153594A
US3153594A US825417A US82541759A US3153594A US 3153594 A US3153594 A US 3153594A US 825417 A US825417 A US 825417A US 82541759 A US82541759 A US 82541759A US 3153594 A US3153594 A US 3153594A
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Prior art keywords
emulsion
gelatin
emulsions
redispersion
silver halide
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US825417A
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Oberth Adolf Eduard
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EIDP Inc
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EI Du Pont de Nemours and Co
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Priority to BE592432D priority Critical patent/BE592432A/xx
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Priority to US825417A priority patent/US3153594A/en
Priority to DEP25276A priority patent/DE1151730B/de
Priority to FR832255A priority patent/FR1269344A/fr
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    • 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
    • C08F118/00—Homopolymers 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 an acyloxy radical of a saturated carboxylic acid, of carbonic acid or of a haloformic acid
    • C08F118/02—Esters of monocarboxylic acids
    • C08F118/04—Vinyl esters
    • C08F118/08—Vinyl acetate
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets

Definitions

  • This invention relates to a novel process for preparing photographic silver halide emulsions. More particularly, it relates to a process for concentrating a photographic silver halide emulsion by coagulating it following the digestion (or second ripening) step.
  • An object of this invention is to provide a process for preparing coagulated, washed photographic silver halide emulsions of high solids content and enhanced sensitometric properties. Another object is to provide such a process which utilizes the conventional apparatus of photographic manufacturers. A further object is to provide such a process which utilizes available chemicals and gives uniform, dependable results. Still further objects will be apparent from the following detailed description of the invention.
  • the process of this invention comprises (a) redispersing a washed coagulum of a gelatino-silver halide emulsion in an aqueous solution so that not more than about 25% by weight of gelatin, based on the silver halide, is present in the redispersion, (b) adding a chemical sensitizing agent and digesting the redispersion at a temperature of at least 90 F., (c) coagulating the redispersion, (d) removing the supernatant liquid and (e) redispersing the recoagulated dispersion in an aqueous solution containing a water-permeable colloid of high molecular weight and possessing protective cololid properties. If desired, in carrying out the process after removal of the supernatant liquid in step (d) the coagulum is washed with water.
  • the coagulum used in step (a) can be made in any of the conventional manners by admixing with a precipitated and ripened gelatino-silver halide emulsion a coagulating agent, e.g., acetone, dimethyl sulfate, an anion soap or a water-soluble, acid-soluble polymer of high molecular Weight (e.g., 5,000 to 50,000 or more) containing a plurality of acid groups, e.g., carboxylic acid groups, sulfate groups or phosphate groups, or the alkali metal or ammonium salts of such groups.
  • a coagulating agent e.g., acetone, dimethyl sulfate
  • an anion soap or a water-soluble, acid-soluble polymer of high molecular Weight e.g., 5,000 to 50,000 or more
  • acid groups e.g., carboxylic acid groups, sulfate groups or phosphate groups, or the alkali
  • coagulating agents can be used in recoagulation step (c).
  • recoagulation can be attained by adding an acid which does not have an adverse eifect on photographic emulsions, e.g., acetic, to reduce the pH below 6.0.
  • any of the conventional adjuvants for photographic emulsions can be added to the redispersion.
  • Suitable such adjuvants include optical sensitizers, halides for controlling pAg, stabilizers and anti-fogging compounds, acids or alkalies for pH adjustment, etc.
  • the recoagulated dispersion can be 3,153,504 Patented Got. 20, E964- "ice stored for any reasonable length of time.
  • the desired binder which can be gelatin or any other compatible water-permeable organic colloid binding agent, by raising the pH above 6.0 and stirring at about the desired coating temperature.
  • the emulsion is diluted with water to Whatever concentration required for the type and thickness of the coating to be made.
  • any of the conventional adjuvants added to emulsions after digestion can be admixed with the redispersion and the redispersion coated onto any suitable support.
  • Example I A high-speed gelatino-silver iodobromide emulsion containing 3 moles of silver halide (1.7 mole percent Agl and 98.3 mole percent AgBr) and 40 g. gelatin was precipitated and ripened in a conventional manner. An aqueous solution of a mixture of sulfated alcohols, predominantly sodium dodecyl sulfate, was then added to give a gelatin/ sulfate ratio of 1:069. The emulsion was stirred and ml. of acetic acid added to form a coagulum containing the suspended silver halide grains. Supernatant liquid was decanted and the coagulum washed twice with solutions containing 5000 ml. H 0, 50 g. NaCl, and 10 ml. acetic acid.
  • C-pigskin gelatin (relatively active, with tendency to cause fog).
  • the three emulsions were redispersed in the gelatin solution as described above by adjusting the pH between 6.4 and 6.8 and stirring vigorously.
  • the emulsions were coated and dried in the usual manner on cellulose triacetate photographic film base to give coating Weights of of approximately milligrams of silver halide per square decimeter.
  • Example II A cine positive silver iodobromide emulsion containing 10 g. of gelatin and approximately 3.6% silver iodide and 96.4% silver bromide based on the total weight of silver halides was made by precipitating the silver halides in a 0.59% aqueous gelatin solution in an amount to give a ratio of gelatin to silver halide of about 1:9. The emulsion was ripened at 120 F. for 17 minutes.
  • Example Ill Two and a quarter moles of silver halide grains were formed and the gelatin emulsion ripened as described in Example I. It was then coagulated by addition of acid and the partial acetal of polyvinyl alcohol and o-sulfobenzaldehyde (consisting of 5 grams of sulfonate sulfur per 100 grams of polymer) and washed as described in Example I of Moede, U.S. Patent 2,772,165. The re sultant coagulate was redispersed in a solution of 45 g. of a very inert gelatin in 2600 g. of distilled E 0 by adjusting the pH up to 6.3 and vigorously stirring at 95 F. for 15 minutes.
  • Gold, sulfur, and reduction sensitizers were added in the conventional manner, and the emulsion was digested for 40 minutes at 140 F. After cooling to 95 F., one-third of the emulsion (containing 0.75 mole of silver halide) was separated and labeled A. The remainder of the emulsion was recoagulated by adding ml. of a 50% (weight to volume) solution of NH NO 50 ml. of the 8.8% solution of the partial acetal of polyvinyl alcohol and sodium o-sulfobenzaldehyde described in Example II, and suificient glacial acetic acid to lower the pH to 3.6.
  • the emulsion was cooled in running cold tap water to improve coagulation, the supernatant liquid was removed, and the emulsion was washed for 10 mintues with high shear stirring in 300 ml. of cold, slightly acidified tap water.
  • the emulsion was redispersed by adding 250 g. of distilled Water, adjusting the pH up to 6.3, and stirring. It was then divided in 2 equal portions, each containing 0.75 mole of silver halide and labeled B and C.
  • Portions A and B were bulked up with aqueous solutions containing g. of the same gelatin that was present during digestion.
  • Portion C was bulked up with an aqueous solution containing 125 g. of a relatively more active gelatin.
  • control emulsion (A) with the more expensive gelatin (very inert) is less stable on aging than emulsion C which contained a cheaper gelatin but which employed the second coagulation wash step.
  • Example IV An emulsion which had been ripened, coagulated, washed, redispersed, chemically sensitized, and digested in the manner described in Example ill contained 3 moles I of silver halide. At the end of digestion the emulsion was cooled to 100 F. and coagulated by addition of dilute acetic acid to pH 4.5. After removing the supernatant liquid, one-twentieth of the coagulate (containing 0.15 mole of silver halide) was removed. This portion was redispersed by adding it to an aqueous solution containing 25 g. of gelatin, adjusting pH to 6.2, and stirring at 100 F. The usual post-digestive adjuvants were added and the emulsion was skim coated on cellulose triacetate film base and dried in the usual manner. The usual thin gelatin abrasion coating was applied over the photographic emulsion layer.
  • the remainder of the coagulate (containing 2.85 moles of silver halide) was easily redispersed by stirring it slowly for 3 minutes at 130 F. in a concentrated aqueous gelatin solution containing 450 g. of gelatin. After addition of the usual post-digestive adjuvants, the emulsion was calculated to contain 50% total solids. Satisfactory extrusion coating and drying of the emulsion was carried out by the process described in Haley, Ser. No. 695,341, filed November 8, 1957, U.S. Patent 3,082,144, March 19, 1963. The coating was made on polyester photographic film base of the type described in Alles et al., 2,627,088, issued February 3, 1953, and Alles, US.
  • Example V1 An emulsion containing 3 moles of silver halide was made, coagulated, and washed as described in Example HI. It was redispersed by stirring in an aqueous solution containing 60 g. of gelatin, the pH of the stirring mixture being adjusted to 6.5. After normal chemical sensitization, the emulsion was digested at 140 F. for 45 minutes and cooled to 100 F. Two portions were removed containing 0.45 mole of silver halide each and the two portions coagulated by the addition of sufficient dilute acetic acid to reduce the pH to 4.5.
  • the emulsions were redispersed at pH 6.4 by vigorously stirring in aqueous solutions containing about 70 g. of bulk gelatin, different types of gelatin being used for the two emulsions. In one case, a high viscosity, high gel-strength gelatin was added during the redispersion while in the other case a low viscosity, low gel-strength gelatin was used.
  • the emulsions were lXtfi Mg Speed* Fog coated on cellulose triacetate film base by the well known gl y 40 technique of air-knife coating.
  • ge a 111 we 0g ge o ontrast Example V speed g Thirty moles of silver halide grains were formed in an emulsion, ripened, coagulated, and washed as described fii g l i nvtiscosity, high gel 110 0 in Example ill. The washed emulsion coagulate was then 50 gg g 3 2- 80 red spersed 111 an aqueous solution containing 600 g. f Strength 100 gelatin by adjusting the pH up to 6.6 and stirring vigorously for 15 minutes at 95 F. Chemical sensitizers were added in the conventional manner, and the emulsion was digested for 45 minutes at 140 F. After digestion, the emulsion was cooled to 100 F., treated with dilute acetic acid to lower the pH to 4.5, and allowed to settle for 15 minutes while cooling to 70 F.
  • the supernatant liquid was removed by siphoning and a portion of the digested and coagulated emulsion containing 1.5 moles of silver halide were removed. This portion was redispersed in an aqueous solution containing 250 g. of gelatin by raising the pH to 6.2 with dilute NaOH and gently stirring. The usual post-digestive adjuvants were added and the emulsion was coated in the usual manner on cellulose triacetate photographic film base.
  • Example 1 The remainder of the digested and coagulated emul sion was stored under refrigeration using an ethanol solution of thymol as a preservative. After 6 days, and again after 51 days, portions of the stored emulsion coagulate (both containing 1.5 moles of silver halide) were redispersed and coated as described in the paragraph above. Film strips of the dried coatings were exposed, processed, and evaluated as described in Example 1. The sensitometric results given below demonstrate one of the unique Example Vll An emulsion was prepared as described in Example III except that digestion was extended to 45 minutes at 140 F.
  • Example VIII An emulsion was ripened, coagulated, and washed as in Example III. Two portions of the washed emulsion coagulate were split off, each containing 3 moles of silver halide, and redispersed by raising the pH to 6.3 and stirring in aqueous gelatin solutions containing 50 g. of gelatin in (A) 2100 g. of distilled water and (B) 4800 g. of distilled water. Both emulsions Were sensitized identically with conventional chemical sensitizers, digested for 40 minutes at 140 F., and cooled to 100. The usual post-digestive adjuvants were added and the emulsions were coated, dried, and evaluated as in Example VI to give the following results:
  • the useful acids to lower the pH for coagulation are the strong mineral acids, e.g., nitric, sulfuric, and hydrochloride acids.
  • Other acids, such as acetic acid may be used as long as they are photographioally inert and have reasonably high dissociation constants in order to avoid the use of excessive amounts of acid.
  • Acid alone is satisfactory as a coagulating agent for the second coagulation of certain emulsions such as described in Example IV, in which much of the coagulating agent remained in the emulsion from the first coagulation step.
  • other coagulating agents in addition to the acid, e.g., polymers and coplymers which are both water-soluble and acid-soluble such as acetals of polyvinyl alcohol and o-sulfo-benzaldehyde, carrageenin (a natural polysulfate of polygalactau), the copolymer of methylvinyl ether and maleic anhydride described in Example V of Moede, US.
  • anion soaps such as discussed at pages 519-522 of the book Kolloid-Chernischemaschinen der Textilveredlung by Dr. E. Valko, 1937, salts such as Na SO and NH NO and combinations of various coagulating agents.
  • the emulsions precipitated, in accordance with the invention may be silver chloride, silver bromide, silver chlorobromide, silver iodobromide, or composed of mixed silver halides which can be made in the usual manner from soluble halides and soluble silver salts.
  • the emul- 8 sions may be optically sensitized by incorporation of the conventional optical sensitizing dyes.
  • hydrophilic organic colloids such as hydrophilic synthetic polymers may be employed as a binder in these emulsions, being added during the redispersion step which follows the second coagulation. Since some gelatin is already present, a mixed binder system results.
  • Suitable hydrophilic synthetic polymers for use in such a mixed binder system include any of various hydrolysis grades of polyvinyl alcohol, polyvinyl acetals, carboxylated polyvinyl acetals, polyvinyl pyrrolidone, etc.
  • emulsions may be coated on any suitable support to make the desired photographic element.
  • suitable supports include cellulose acetate, other cellulose esters such as cellulose triacetate, cellulose acetate butyrate, cellulose nitrate, cellulose propionate; super polymers, e.g., polyethylene terephthalate, nylon, polyvinyl chloride, poly (vinyl chloride or vinyl acetate) and vinylidene copolymers with vinyl acetate, acrylonitrile, etc.; metal sheets or foils, e.g., aluminum and zinc; and paper including resin-coated and bartya-coated paper; as well as glass plates.
  • the primary advantage of this invention is that it affords a simple, reliable means of preparing a photographic emulsion when it is desired that said emulsion have a high solids content. This is particularly important for extrusion coating and is, to a lesser extent, advantageous in air knife coating.
  • Another advantage resides in the fact that emulsions prepared according to this invention are not so dependent upon the quality of the gelatin as has been the case heretofore. Only very small quantities of gelatin are present throughout the ripening and digestion phases of emulsion manufacture and the bulk gelatin, which makes up the great majority of the total gelatin present, is added to the emulsion just before coating and therefore contributes relatively little to the sensitometric properties of the coating.
  • gelatin for bulking purposes.
  • gelatin for bulking purposes.
  • this invention it is possible to bulk the emulsion with various hydrophlic synthetic polymers in place of gelatin where these other polymers might have had a detrimental effect had they been present during ripening or digestion.
  • Still another advantage of a coagulation washing which follows digestion is the removal of excessive reagent employed during the digestion reaction, thus extending the range of applicable compounds, as well as the removal of harmful materials formed during the process of sensitization.
  • the process of this invention also leads to improved aging stability without affecting fresh sensitometric results.
  • This invention is of general application for sensitizing and providing a means of separating chemical sensitization from the other steps of emulsion preparation, thus avoiding many compromises which must be made in conventional systems. Chemical sensitization in the absence of large quantities of binder allows the use of chemicals which, in the presence of the binder, might lose most of their activity.
  • Yet another advantage is the convenience in being able to store emulsions, after digestion, in the form of concentrated emulsion coagulates which, by the process of this invention, have been shown to be stable over long periods of time. Still further advantages will be apparent from the above description of the invention.
  • a process for preparing photographic emulsions which comprises, in order, the steps of (a) redispersing a washed coag llum of a precipitated and ripened gelatinosilver halide emulsion in an aqueous solution so that not more than 25% by weight of gelatin, based on the silver halide, is present in the final redispersion resulting from this step (a), (b) adding a photographic emulsion chemical sensitizing agent and digesting the redispersion at a temperature of at least 90 F., (c) coagulating the redispersion, (d) removing the supernatant liquid and (e) redispersing the recoagulated redispersion in an aqueous solution containing a water-permeable colloid of high molecular weight and possessing protective colloid properties.
  • a process as defined in claim 1 wherein the coagulum is a complex of a gelatin emulsion and a sodium salt of a sulphated monohydric alcohol of 10 to 18 carbon atoms.
  • coagulum is a complex of a gelatin emulsion with a water-soluble, acid-soluble organic polymer of high molecular Weight containing recurring groups taken from the class consisting of oxyacid groups and their alkali metal and ammonium salts.
  • coagulum is a complex of gelatin and a water-soluble, acidsoluble, sodium o-sulfobenzaldehyde polyvinyl acetal containing a plurality of intralinear CH CHOH groups and being both soluble in water and 1% nitric acid to the extent of at least 1% by weight.
  • step (d) A process as defined in claim 1 in which, following the removal of supernatant liquid in step (d), the coagulum is Washed with water.
  • step (e) is gelatin.

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  • Engineering & Computer Science (AREA)
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US825417A 1959-07-07 1959-07-07 Process for preparing photographic emulsions Expired - Lifetime US3153594A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BE592432D BE592432A (de) 1959-07-07
US825417A US3153594A (en) 1959-07-07 1959-07-07 Process for preparing photographic emulsions
DEP25276A DE1151730B (de) 1959-07-07 1960-07-01 Verfahren zur Herstellung photographischer Silberhalogenidemulsionen nach dem Ausflockungsverfahren
FR832255A FR1269344A (fr) 1959-07-07 1960-07-06 Préparation d'émulsions photographiques

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3250620A (en) * 1962-01-18 1966-05-10 Eastman Kodak Co Silver halide emulsions having chill-setting properties
US5013641A (en) * 1989-12-19 1991-05-07 Eastman Kodak Company Formation of tabular silver halide emulsions utilizing high pH digestion

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1623499A (en) * 1925-06-16 1927-04-05 A corpora
US2401051A (en) * 1939-09-26 1946-05-28 Photo Positive Corp Photographic emulsions and methods
US2618556A (en) * 1947-11-19 1952-11-18 Eastman Kodak Co Process for preparing photographic emulsions
US2728662A (en) * 1947-08-13 1955-12-27 Eastman Kodak Co Method of preparing photographic emulsions
US2772165A (en) * 1953-05-11 1956-11-27 Du Pont Method of making a silver halide emulsion
US2787545A (en) * 1955-01-17 1957-04-02 Eastman Kodak Co Method of preparing photographic emulsions by coagulating with gelatin graft polymers
US2982652A (en) * 1957-06-18 1961-05-02 Gevaert Photo Prod Nv Preparation of photographic emulsions
US3002741A (en) * 1961-01-30 1961-10-03 Akutowicz Frank Hydraulic damper
US3046134A (en) * 1958-12-12 1962-07-24 Eastman Kodak Co Sensitization of photographic silver halide emulsions with polymeric compounds containing a plurality of sulfur atoms
US3067035A (en) * 1959-04-01 1962-12-04 Du Pont Gelatin-anion soap complex dispersion in polyvinyl alcohol photographic emulsions

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE561484A (de) * 1956-06-19

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1623499A (en) * 1925-06-16 1927-04-05 A corpora
US2401051A (en) * 1939-09-26 1946-05-28 Photo Positive Corp Photographic emulsions and methods
US2728662A (en) * 1947-08-13 1955-12-27 Eastman Kodak Co Method of preparing photographic emulsions
US2618556A (en) * 1947-11-19 1952-11-18 Eastman Kodak Co Process for preparing photographic emulsions
US2772165A (en) * 1953-05-11 1956-11-27 Du Pont Method of making a silver halide emulsion
US2787545A (en) * 1955-01-17 1957-04-02 Eastman Kodak Co Method of preparing photographic emulsions by coagulating with gelatin graft polymers
US2982652A (en) * 1957-06-18 1961-05-02 Gevaert Photo Prod Nv Preparation of photographic emulsions
US3046134A (en) * 1958-12-12 1962-07-24 Eastman Kodak Co Sensitization of photographic silver halide emulsions with polymeric compounds containing a plurality of sulfur atoms
US3067035A (en) * 1959-04-01 1962-12-04 Du Pont Gelatin-anion soap complex dispersion in polyvinyl alcohol photographic emulsions
US3002741A (en) * 1961-01-30 1961-10-03 Akutowicz Frank Hydraulic damper

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3250620A (en) * 1962-01-18 1966-05-10 Eastman Kodak Co Silver halide emulsions having chill-setting properties
US5013641A (en) * 1989-12-19 1991-05-07 Eastman Kodak Company Formation of tabular silver halide emulsions utilizing high pH digestion

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BE592432A (de)

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