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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
  • B01F23/40—Mixing liquids with liquids; Emulsifying
  • B01F23/49—Mixing systems, i.e. flow charts or diagrams
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
  • B01F23/50—Mixing liquids with solids
  • B01F23/59—Mixing systems, i.e. flow charts or diagrams
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F35/00—Accessories for mixers; Auxiliary operations or auxiliary devices; Parts or details of general application
  • B01F35/20—Measuring; Control or regulation
  • B01F35/22—Control or regulation
  • B01F35/2201—Control or regulation characterised by the type of control technique used
  • B01F35/2209—Controlling the mixing process as a whole, i.e. involving a complete monitoring and controlling of the mixing process during the whole mixing cycle
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F2101/00—Mixing characterised by the nature of the mixed materials or by the application field
  • B01F2101/56—Mixing photosensitive chemicals or photographic base materials

Definitions

• the present invention relates to a new system for producing a photographic dispersion.
• photographic dispersion relates to dispersions utilized for producing both photographic dispersions and for
• the system comprises producing a photographic dispersion with a constant mixing ratio and estimate of excess aqueous solution, implemented in a control algorithm, by using a load cell as a main sensor element 10 and turbine-type disperser for performing mixing and under the conditions of: reactor of oily solution pressurized under controlled pressure and nitrogen atmosphere and constant dispersion flow rate.
• the system comprises the following equipments: 15 a pressurized reactor, load cells, an open reactor, flowmeters, turbine-type pump, check valves and computer.
• the term "computer” (1) herein means a process digital computer or controller, which may be a programmable logical controller.
• dispenser means a 20 compound resulting from mixing the aqueous solution and the oily solution at a determined mixing ratio and constant pressure.
• turbine refers a turbine-type pump.
• 25 dispersion consists basically in mixing two solutions, an aqueous solution and an oily solution.
• the aqueous solution which has gelatin as a main element is prepared at a temperature between 70 and 80 degrees Celsius.
• the oily solution which has as its main element, a solvent having a viscosity close to that of oil, is prepared at a temperature between 100 and 141 degrees Celsius. Because both solutions have different viscosities and chemical characteristics, they are not easily miscible with each other.
• an injector or "eductor" In order to achieve dispersion, it is usually employed an injector or "eductor". In this case, the aqueous solution is injected at the inlet of the injector at a constant pressure of 1.24 kPa, through a positive displacement pump.
• the oily solution is sucked through the suction inlet of the injector.
• a check valve is utilized at the suction inlet in order to control the flow rate of oily solution, thus maintaining the mixing ratio constant.
• mixing of the two solutions takes place in the injector chamber.
• the thus obtained dispersion is homogenized and cooled to between 30 and 40 degrees Celsius.
• An essential condition for producing the dispersion is that the aqueous solution should not be depleted before the oily solution due to the characteristics of rapid crystallization.
• the conventional process for producing dispersions was carried out in two open reactors, a positive displacement pump, a check valve and an injector. Said process was characterized by high losses of product for being a discontinuous or batchwise process.
• the absence of an inert atmosphere of nitrogen within the reactor of oily solution entrained constant risks of product loss because of the oxidation of this solution in contact with air.
• Mixing ratio was not constant throughout mixing of both solutions because the valve controlling the flow rate of oily solution was manually adjusted to a constant opening at the beginning of the batch. Because a controller of mixing ratio and end of oily solution was not utilized, changes in the product characteristics such as viscosity, specific gravity and volume may dangerously affect the condition of the oily solution ending before the aqueous
• the new system (as depicted in figure 1) which is the object of this invention, comprises a pressurized
• Utilizing a turbine provides for advantages that a process utilizing injector could hardly offer, such
• the inside of the closed reactor is subjected to pressurized inert atmosphere of nitrogen gas.
• the algorithm takes into account the initial mass of the reactors, that is, the total mass of product 15 prior to starting mixing, see equation (1) .
• the mass present in the reactors is constantly monitored and is supplied to the algorithm for the calculation of the estimate of the excess of aqueous solution, see equation (2) . If the estimate is within the desired range, the 20 mixing ratio will be as well. Is it is not, the flow rate of oily solution will be increased or reduced by actuation of the check valve VC-1. Control of the flow of the dispersion is effected through check valve VC-2. Control algorithm:
• Mck instantaneous mass of oily solution at instant t k, [kg];
• valve VC-1 In order to prevent initial perturbations from occurring, the computes positions valve VC-1 with an initial opening AB and starts execution of the algorithm, fifteen seconds after starting mixing. Such time proved to be empirically suitable for the implemented plant.

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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)
• Dispersion Chemistry (AREA)
• Accessories For Mixers (AREA)
• Colloid Chemistry (AREA)

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Publications (1)

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• 1992
  • 1992-05-21 EP EP92910929A patent/EP0595821A1/de not_active Withdrawn
  • 1992-05-21 AU AU17815/92A patent/AU1781592A/en not_active Abandoned
  • 1992-05-21 JP JP4509734A patent/JPH06510371A/ja active Pending
  • 1992-05-21 WO PCT/BR1992/000006 patent/WO1993023791A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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