US3628959A - Process for the preparation of photographic emulsion - Google Patents

Process for the preparation of photographic emulsion Download PDF

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Publication number
US3628959A
US3628959A US768021A US3628959DA US3628959A US 3628959 A US3628959 A US 3628959A US 768021 A US768021 A US 768021A US 3628959D A US3628959D A US 3628959DA US 3628959 A US3628959 A US 3628959A
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solution
halogen
gelatin
silver nitrate
component
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US768021A
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Horst Theilemann
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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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
    • B01F27/80—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis
    • B01F27/91—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis with propellers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
    • B01F27/05—Stirrers
    • B01F27/11—Stirrers characterised by the configuration of the stirrers
    • B01F27/15—Stirrers with tubes for guiding the material

Definitions

  • PROCESS FOR THE PREPARATION OF PHOTOGRAPHIC EMULSION This invention relates to a process for the preparation of photographic emulsions and apparatus for carrying out such processes.
  • Photographic emulsions are generally prepared by adding gelatin to halogen salts dissolved in water and heating the mixture, after swelling of the gelatin, to the temperature necessary to achieve the desired film sensitivity. An aqueous silver nitrate solution is then heated to a suitable temperature and used for the subsequent silver halide precipitation process.
  • the silver nitrate solution is permitted to flow into the halogen-salt solution, accompanied by continuous stirring to produce the light-sensitive silver bromide.
  • the speed of rotation of the stirrer is restricted because above a certain speed, foaming occurs which is considered undesirable.
  • gelatin which serves as the protective colloid during the precipitation, decomposes in the undissolved state to a greater extent the higher the temperature and the longer complete precipitation takes. This results in an inferior light quantum utilization.
  • sensitizers having maximum efficiency.
  • Sensitizers are generally complicated organic compounds which require specialists for their production and the more efficient compounds are frequently more expensive.
  • the efficiency of the sensitizers is reduced to a greater or lesser extent by impurities, in particular by traces of metals. Optimum adsorption by the agglomerates is not however achieved due to the reduced surface area.
  • the object of the present invention is therefore not only to improve the above-described known process so as to prepare more sensitive emulsions, but also to improve the fineness of grain and the resolution in the films and to ensure improved utilization of the silver supplied to the gelatinsalt solution.
  • the amount of silver which must be used may thus be reduced and an adequate density obtained, resulting in a lowering of manufacturing costs, quite apart from the increase in the efficiency of the sensitizing dyes.
  • the washing procedure may be shortened with a saving of water.
  • a process for the preparation of aqueous gelatino silver halide photographic emulsions in which an aqueous halogen salt solution is heated to the temperature required to produce a desired emulsion sensitivity, dry gelatin or water swollen gelatin at ambient temperature is added to the heated solution and a solution of silver nitrate is then added to the halogen-salt solution whilst the said halogen-salt solution is in motion whereby finely divided silver halide is precipitated to form the emulsion, the halogen salt in the solution from which the silver halide precipitates being at least in part potassium bromide.
  • apparatus adapted for use in processes according to the invention which apparatus comprises at least one container for halogen-salt solution, means associated with the said container for moving a portion of halogen-salt solution therein at relatively high speed either whilst remaining within the said container or whilst travelling along a passage connected thereto, and inlet means'for adding silver nitrate solution to the said portion of halogen-salt solution whilst the said portion is moving at relatively high speed whereby finely divided silver halide is precipitated therefrom.
  • Bacterial attack on the emulsions has previously been inhibited by the use of agents which at least retard the decomposition of the gelatin.
  • agents which at least retard the decomposition of the gelatin have, for example, been bactericides e.g. a phenol, which have been added to the emulsions.
  • a bactericide or other such agent is incorporated into the gelatin, swollen gelatin, halogen-salt solution and/or silver nitrate solution.
  • bactericide is added to the silver nitrate solution, a submicroscopic silver separation may take place depending on the degree of action. During the precipitation process this extremely finely dispersed silver then forms nuclei of crystallization, which favor individual grain formation and the trapped nuclei act as sensitivity centers. These agents should however, be limited to those which at least do not increase the tendency to fog formation.
  • lactose as a fog rate reducing agent in conjunction with increased emulsion density is known I (DBP 1,153,990). It has not hitherto been known, however, that the reduction of the silver during the precipitation process is necessary in order to obtain fine-grain emulsions and for increasing the sensitivity.
  • a further improvement in the sensitivity of the emulsion can be achieved without increasing the grain size when using potassium iodide in addition to potassium bromide as halide salt if the potassium iodide is not dissolved along with the potassium bromide in the halogen-salt solution.
  • a concentrated potassium iodide solution is prepared and mixed with the solution of silver nitrate and then with the relatively small portion of the remaining salt solution which is moving at a relatively high speed.
  • silver iodide is initially fonned in high concentration.
  • the concentrated potassium iodide solution may also be mixed with a concentrated potassium bromide solution and this concentrated solution introduced into the relatively small portion of the halogen salt solution which is moving at a relatively high speed.
  • the apparatus according to the invention is adapted for car-- rying out the process according to the invention.
  • the apparatus may for example be a modification of conventional apparatus and consist of a tank and a rotator such as a stirrer, propeller, turbine or the like which may be inserted into the tank to agitate the solution in said tank.
  • This known apparatus is modified according to the present invention to provide a means arranged in the working area of the rotator to increase the speed of movement of the solution which is moved by the rotator. This is achieved by the relationship between the position of the mouth of the inlet feeding in the silver nitrate solution and the means for increasing the speed of movement. It is recommended that a nozzle be used or a constriction of the flow of liquid be caused by the rotator.
  • This nozzle may, for example be in the shape of a Venturi nozzle or may consist of a plate, body or the like covering the rotator on at least one side and having an orifice therein. It is also possible for exampie to provide a plurality of means for increasing the speed of movement of the liquid moved by the rotators.
  • the apparatus may also be constructed in some other way, provided that the part of the liquid to be moved is moved at a considerably higher speed than the rest of the liquid.
  • the apparatus may therefore consist of a plurality of containers for the salt solutions. These containers may be pressurized and connected by a least one pipe and furthermore there should be provided a container for the silver nitrate solution, the con tainer being connected via in each case at least one pipe with the other pipes.
  • An emulsion prepared according to the process of the invention and having the same sensitivity as a conventionally prepared emulsion has a grain size about 75 percent of normal. This process makes it possible to produce highly sensitive films of previously unobtainable fine-grain form.
  • the containers, tanks, etc. have previously been provided with dished bases, the deepest point of which was on the axis of the container or the like.
  • a stirrer introduced in the center of the solution has the disadvantage that for maximum immersion the total volume of liquid is given a rotary movement. This rotation is to be avoided, for example, by laterally displacing the stirrer. This necessitates a reduction in the depth of immersion of the stirrer in the solution and necessarily a reduc tion of the speed of rotation of the stirrer to avoid foaming.
  • Stainless steel vessels e.g. chromium nickel steel vessels
  • they have been used in conventional processes and they have the advantage of good thermal conductivity but suffer from the disadvantage of being more or less strongly corroded during the emulsion process. This leads to a contamination of the emulsion by traces of metals. These contaminants reduce the stability, the sensitivity and the spectral response.
  • the inner surface of each tank, container or the like be constructed of a corrosion-resistant material such as enamel, gold, wood, plastic, platinum, porcelain or the like to overcome this disadvantage. The necessity for polishing the chemically corroded tank is then eliminated and the emulsion can no longer acquire metal contaminants in this way.
  • Emulsions prepared under these conditions require considerably shorter washing times and therefore save water.
  • a stirrer introduced into the center of the solution to provide maximum penetration into the liquid suffers from the disadvantage of making the total volume of liquid move in a pronounced rotary fashion, result ing in a uniform circulation. Lateral displacement and sloping of the stirrer provides a better stirring action.
  • the danger of foaming is increased, however, because of the necessarily reduced depth of immersion of the stirrer. This also applies to containers or the like having a flat base. If as is further proposed according to the invention it is ensured that the deepest point of the base is arranged eccentrically with respect to the feed opening, considerably better conditions are obtained and working may commence using smaller starting volumes.
  • Component A 25 ml. of H,0 5 ml. ol'a l0% bactericide solution e.g phenol or the like 30 g. of gelatin swelling for 30 minutes at 20 C.
  • Component 8 1,500 ml. of H,0 400 g. of KBr 10 g. of Kl heating to 50' C.
  • Component C 1,500 ml. of H,0 400 g. of KBr 10 g. of Kl heating to 50' C.
  • Component D 500 ml. ofdry gelatin Component A is added to suitably agitated component B. Component C is then immediately permitted to run into the mixture, uniformly and over 4 minutes. Component D is then stirred in.
  • EXAMPLE 2 For an emulsion with increased density (factor 1) Component A 50 g. of dry gelatin L500 ml. of H,0 400 g. of KE-r IS g. of Kl heating to 50 C. Component C.
  • Component A 500 g. of dry gelatin Component A is added to suitably agitated component B.
  • Component C is then immediately permitted to run into the mixture over minutes.
  • Component D is then stirred in.
  • the emulsions of examples 1 and 2 save 50 percent of the silver of normal emulsions.
  • the densities of these emulsions are the same as those of emulsions prepared according to con ventional processes. This is due merely to the careful treatment of the gelatin.
  • Component A 25 ml. of l-l,0 3 ml. ofa bactericide solution, e.g. phenol or the like 30 g. of gelatin.
  • Component B [,500 ml. oft-[,0 400 g. of AgNO 17 g. of Kl heating to 55 C.
  • Component C [,500 ml. oft-[,0 400 g. of AgNO 17 g. of Kl heating to 55 C.
  • Component D 50 ml. ola 5% bactericide solution e.g. phenol
  • Component E 500 g. of dry gelatin.
  • component B When the desired temperatures are reached, component B is suitably agitated and component A added. Simultaneously, component D is added to component C which is then permitted to flow uniformly into component B over 3 minutes.
  • component B When the desired temperatures are reached, component B is suitably agitated and component A added. Simultaneously, component D is added to component C which is then permitted to flow uniformly into component B over 3 minutes.
  • These emulsions contain separate grains only. The grain is finer and the sensitivity is considerably greater than that of equally sensitive commercial films. Their spectral response is improved and their stability increased.
  • Component B 1,400 ml. of H,o
  • the highly sensitive emulsion prepared according to example 5 has the same advantage as the emulsions prepared according to examples 3 and 4.
  • the density of the emulsions of commercial, high-sensitivity films falls with increase in sensitivity.
  • the silver content which is already fairly high, has previously been increased further without providing the most advantageous density.
  • the density of the emulsion prepared according to example 5 is considerably better than that of the above-mentioned commercial films. Due to the finer grain and the improved density, it is possible to provide films with an even higher sensitivity than before.
  • EXAMPLE 6 For an emulsion with an even further increased sensitivity without increased grain Component A 25 ml. of H,0 5 ml. of a l0% bactericide solution 30 g. otgelatin to swell for 30mins. at 20 C. Component 8 1.400 ml. of H,0 50 ml. of a 10% bactericide solution,
  • component B is suitably agitated in the vicinity of the rotator, component A is added to component B and immediately thereafter component B, and component C are allowed to flow into the mixture i.e. component B over 60 secs. and component C over 6 mins. Component D is then stirred in.
  • Component A 25 ml. of H,0 5 ml. ofa IOl: bactericide solution. e.g. phenol or the like 30 g. of gelatin to swell for 30 mins. at 20 C.
  • Component B nun-e "Ann L400 ml. of H4) 50 ml. ofa I: baictericide solution 330 g. of KBI'.
  • component B is suitably agitated in the vicinity of the rotator, component A added to component B and immediately following components B, and C are allowed to flow into the mixture i.e. component 8, over 60 secs. and component C over 6 mins.
  • FIG. 1 is a vertical section through an open boiler having an eccentrically offset base with an outlet therein; a rotator with an associated additional member to provide a considerably increased localized agitation and a feed pipe for the silver nitrate solution, which terminates in the center of the additional member,
  • FIG. 2 is a vertical section through a. boiler with an eccentrically arranged, cylindrical base and a multistage rotator, together with a feed pipe for the silver nitrate solution,
  • FIG. 3 is a vertical section through a venturi tube with two feed pipes connected for delivery of the silver nitrate solution
  • FIG. 4 is a vertical section through a feed device comprising a rotator and a nozzle
  • FIG. 5 is a vertical section through two containers which can be pressurized alternately and which are connected by a pipe which is connected to a third container by a further pipe; the container may be filled with a silver nitrate solution, and
  • FIG. 6 is a vertical section of a further embodiment of apparatus according to the invention with an annular pipe.
  • the boiler I which is open at the top and is shown in FIG. 1 has a base asymmetrically the lowest portion 3 of which is ar ranged asymmetrically with respect to the filling inlet 8.
  • the inner surface 1' consists of a corrosion-resistant material, such as enamel, glass, wood, a synthetic resin, porcelain or the like.
  • rotator 5 Above the lowest portion .3 of the boiler, rotator 5 is provided constructed as a stirrer, and driven by a shaft 6.
  • a plate 8 hav ing an orifice 7 is nonrotatably mounted and supported, for example in relation to the inner wall of the boiler as indicated at 8.
  • a discharge valve 9 is provided, which however need not be used since the boiler can also be emptied by tilting.
  • a feed pipe 11 from a container terminates in the area of the orifice 7 of the plate 8.
  • the required halogen salt solution is prepared in the boiler I or the latter filled therewith, the liquid level is shown at 12.
  • the rota tor 5 is rotated, the locking valve 13 opened and the silver nitrate solution stored in the container 10 is fed to the area in the boiler i at which a relatively small portion of halogen salt solution is moving at a relatively high speed.
  • Intensive mixing of the halogen salt solution with the silver nitrate solution to precipitate the silver takes place.
  • the liquid level 14 of the silver nitrate solution indicates that the quantities of the two solutions are not equal as with ID percent silver nitrate solution, but for example l:5.
  • the silver nitrate solution is con tinuously fed into the liquid in boiler 1, an extremely intensive mixing taking place, until the whole of the silver nitrate solution is in boiler 1.
  • the boiler 15 in FIG. 2 is likewise so constructed that its lowest portion 3' is arranged asymmetrically with respect to the filling aperture.
  • the boiler has a well 16 in which are situated two coaxial and separated rotators 17 and 18 constructed as turbines, each of which is provided with av plate 8 having an orifice 7.
  • these plates are interconnected by a hollow cylinder 19, and are nonrotatably secured as is the plate 8 in FIG. 1.
  • the feed pipe 11 terminates in the vicinity of the opening 7 of the lower plate 8 and leads from a container HI (not shown).
  • a venturi nozzle 21 (FIG. 3) may be used in place of the plate 8 provided with the orifice. Feed pipes 11 and Ill terminate in the vicinity of the narrowest cross section of this venturi nozzle or after it.
  • FIG. 4 Another possibility of supplying the silver nitrate solution is shown in FIG. 4.
  • a turbine 25 in a recess 24 in a nozzle body 22 is provided with a bottleneck 23; both feed pipes 11 and 11' for the silver nitrate solution terminate in the vicinity of the bottleneck 23, although they may terminate at other positions.
  • the arrangement shown diagrammatically in FIG. 5 consists of two boilers 26 and 27 which are interconnected by a pipe 28.
  • the feed pipe 11 which is connected to a container 10' which can be indated by a valve 13 terminates at .29.
  • the closed containers 26 and 27 are then connected by alternately operable valves 30 and 31 to a compressed air source 32.
  • the initial quantity of a prepared halogen salt solution is used to fill the boiler 26, for example through a funnel 33, behind which a locking valve 34 is arranged, A corresponding device 34' is associated with the boiler 27, It is recommended that at least one of the two boilers 26 and 27 be provided with an outlet 35 which may be closed by the valve 36. Valves 37 and 38 may also be provided.
  • valve 30 and valve 34 If compressed air is introduced into the boiler 26 with valve 30 and valve 34 closed, the halogen-salt solution in the boiler 26 flows into the boiler 27, when the valves 37 and 38 are open, silver nitrate being added to this halogen-salt solution when the valve 13 is open.
  • the valve 34 must be open to enable the satisfactory transfer of the halogen-salt solution into the boiler 27. It must be ensured that silver nitrate solution is added when transferring the solution from boiler 26 into boiler 27 or from boiler 27 into boiler 26. Valves 30 and 34 are closed and valves 31 and 34 are opened. The halogen-salt solution mixed with some silver nitrate solution and present in the boiler 27 then is forced through the pipe 28 into the boiler 26, more silver nitrate being added.
  • the two boilers 26 and 27 must be of such a volume that they can each contain the combined halogen-salt and silver nitrate solutions.
  • the emulsion can be discharged for further processing by opening the valve 36.
  • the valves used with this embodiment of the invention may for example be automatically controlled and be arranged to operate in the sequence required to operate the process according to the invention.
  • FIG. 6 shows a boiler 39 which is partially filled with a halogensalt solution.
  • the boiler containing the silver nitrate solution is shown at 40.
  • a pump 41 is connected to the boiler 39 by a suction pipe 42 and a pressure pipe 43.
  • a pipe 44 serves to supply the silver nitrate solution and it is connected by a pipe 45 to the suction pipe 42. It is further connected by a pipe 46 to the suction side of the pump 41 and by a pipe 47 to the pressure pipe 43. In each case, connection is such as to permit the silver nitrate solution to flow into the boiler. Due to the high speed of the liquid in the pipes 42 and 43, a satisfactory mixing of the halogen-salt and silver nitrate solutions is effected. The mixing speed may be increased by providing one or more constrictions.
  • a process for the preparation of an aqueous gelatino silver halide photographic emulsion which comprises heating an aqueous halogen-salt solution to the temperature required to produce a desired emulsion sensitivity, adding dry gelatin or water-swollen gelatin at ambient temperature to the heated solution, moving a relatively small portion of the total halogen-salt solution at a relatively high speed, and adding a solution of silver nitrate to said relatively small portion of the halogen-salt solution while the halogen-salt solution is in motion, whereby finely divided silver halide is precipitated to form the emulsion, the halogen salt in the solution from which the silver halide precipitates being at least in part potassium bromide.
  • a process as claimed in claim 1 in which a concentrated solution of potassium iodide is added to the said portion of the halogen-salt solution simultaneously with the addition of the silver nitrate solution.
  • a process as claimed in claim 1 in which a maximum difparts by weight of gelatin, 400 parts by weight of potassium bromide, l0 to l7 parts by weight of potassium iodide and 500 parts by weight of silver nitrate.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Colloid Chemistry (AREA)
  • Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
US768021A 1967-10-23 1968-10-16 Process for the preparation of photographic emulsion Expired - Lifetime US3628959A (en)

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Application Number Priority Date Filing Date Title
DE19671597643 DE1597643C (de) 1967-10-23 1967-10-23 Verfahren zum Herstellen einer photographischen Silberhalogenidemulsion und Vorrichtung zur Ausübung dieses Ver fahrens

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3850643A (en) * 1971-07-28 1974-11-26 Eastman Kodak Co Process for making coupler dispersions
US4147551A (en) * 1972-08-14 1979-04-03 E. I. Du Pont De Nemours And Company Process for photographic emulsion precipitation in a recycle stream
US4171224A (en) * 1976-09-14 1979-10-16 Agfa-Gevaert N.V. Method and apparatus suitable for the preparation of AgX-emulsions
US4251627A (en) * 1978-05-30 1981-02-17 E. I. Du Pont De Nemours And Company Jet mixing in preparation of monodisperse silver halide emulsions
US5466570A (en) * 1995-02-21 1995-11-14 Eastman Kodak Company Sonic micro reaction zones in silver halide emulsion precipitation process
US20020101783A1 (en) * 2000-12-15 2002-08-01 Hasberg Dirk J. Apparatus for manufacturing photographic emulsions

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2618556A (en) * 1947-11-19 1952-11-18 Eastman Kodak Co Process for preparing photographic emulsions
US3425835A (en) * 1964-03-30 1969-02-04 Eastman Kodak Co Method for dispersing non-aqueous solution in aqueous gelatin solutions using an aspirating agitator

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2618556A (en) * 1947-11-19 1952-11-18 Eastman Kodak Co Process for preparing photographic emulsions
US3425835A (en) * 1964-03-30 1969-02-04 Eastman Kodak Co Method for dispersing non-aqueous solution in aqueous gelatin solutions using an aspirating agitator

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Making and Coating Photographic Emulsions by Relikman et al. Focal Press Limited 1964 pp. 17 22 and 228 236. *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3850643A (en) * 1971-07-28 1974-11-26 Eastman Kodak Co Process for making coupler dispersions
US4147551A (en) * 1972-08-14 1979-04-03 E. I. Du Pont De Nemours And Company Process for photographic emulsion precipitation in a recycle stream
US4171224A (en) * 1976-09-14 1979-10-16 Agfa-Gevaert N.V. Method and apparatus suitable for the preparation of AgX-emulsions
US4251627A (en) * 1978-05-30 1981-02-17 E. I. Du Pont De Nemours And Company Jet mixing in preparation of monodisperse silver halide emulsions
US5466570A (en) * 1995-02-21 1995-11-14 Eastman Kodak Company Sonic micro reaction zones in silver halide emulsion precipitation process
US20020101783A1 (en) * 2000-12-15 2002-08-01 Hasberg Dirk J. Apparatus for manufacturing photographic emulsions
US6443611B1 (en) * 2000-12-15 2002-09-03 Eastman Kodak Company Apparatus for manufacturing photographic emulsions

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FR1585737A (enrdf_load_stackoverflow) 1970-01-30

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