Eastman-kodak Company

Jong-Shinn Wey

Anthony D Gingello

Herbert S Wilgus

Ming-Jye Lin

James M Hamlin

James P Terwilliger

Thomas E Whiteley

A process and apparatus for precipitating a silver halide emulsion is disclosed. The process is comprised of the steps of adding silver ions to a dispersing medium containing halide ions within a reaction vessel to initiate growth of silver halide grains within the dispersing medium, monitoring the temperature of the dispersing medium to establish the equilibrium solubility product constant of silver and halide ions within the dispersing medium; concurrently, using a reference electrode and a first indicator electrode, monitoring the halide ion activity within the dispersing medium; and adjusting the level of dissolved halide ion in the reaction vessel to maintain a stoichiometric excess of halide ions, based on the equilibrium solubility product constant. In the process the potential difference between a silver ion specific electrode in contact with the dispersing medium within the reaction vessel and at least one of the first indicator electrode and the reference electrode is concurrently monitored to allow the level of dissolved silver ion to be determined independently of the equilibrium solubility product constant, and the level of dissolved silver ion in the dispersing medium is adjusted based on the potential difference to maintain a selected profile of dissolved silver ion during silver halide grain growth. The apparatus contains the elements necessary for the practice of the process.

Process for independently monitoring the presence of and controlling

A process is disclosed of producing photographically useful radiation sensitive silver halide emulsions the grains of which are of a predetermined size distribution, including selection of maximum and minimum grain diameters and selection of the distribution of grains of maximum, minimum, and intervening diameters. This is achieved by modifying a double jet precipitation to introduce during the run stable silver halide grains capable of acting as host grains for the deposition of additional silver and halide ions. The degree to which the host grains initially introduced are grown determines the maximum grain diameter of the emulsion. The minimum diameter of the grains in the emulsion produced can be determined by the diameter of the stable silver halide grains introduced at the end of the run. The rate at which the stable host grains are introduced during the run controls the distribution of intervening grain sizes. The silver halide emulsion produced in various forms can be comprised of silver halide grains differing in diameter such that (a) the relative frequency of grain size occurrences is relatively invariant over much of the range of grain sizes present; (b) the maximum relative frequency of grain sizes occurs near the minimum grain diameter of the emulsion; (c) the maximum relative frequency of grain sizes occurs near the maximum grain diameter; or (d) maximum relative frequencies of grain sizes occur near both the maximum and minimum grain sizes.

Processes for the preparation of silver halide emulsions of controlled

Tabular grain silver halide emulsions are disclosed containing chloride and bromide in at least annular grain regions. The tabular grains having a thickness of less than 0.5 micron, preferably less than 0.3 micron, a diameter of at least 0.6 micron, and an average aspect ratio of at least 5:1, account for at least 35 percent of the total projected area of the total silver halide grain population. The average molar ratio of chloride to bromide in at least the annular grain regions ranges up to 2:3. The tabular grains containing chloride and bromide in at least annular grain regions are formed by maintaining a molar ratio of chloride and bromide ions of from 1.6:1 to 258:1 and the total concentration of halide ions in the reaction vessel in the range of from 0.10 to 0.90 N during introduction of silver, chloride, and bromide salts into a reaction vessel, thereby favoring the coprecipitation of chloride and bromide in a tabular crystal habit.

Silver chlorobromide emulsions and processes for their preparation

A double-jet precipitation process is disclosed for preparing radiation-sensitive photo- graphic emulsions containing tabular silver chloride grains which are substantially internally free of bromide and iodide. In forming the emulsions chloride and silver salt solutions are concurrently run into a dispersing medium while controlling both pH and pAg. Tabular grains having an average aspect ratio of greater than 8:1 are obtained.

Double-jet precipitation processes and products thereof

A process is disclosed for the continuous formation of radiation-sensitive silver halide emulsions. In the course of reacting a silver salt with a halide salt in the presence of a peptizer to form a radiation-sensitive silver halide emulsion a portion of the emulsion is withdrawn continuously from the reaction chamber while silver halide grain formation is occurring. The silver halide grains are formed in the presence of a sulfur-containing silver halide ripening agent, while the total halide ion concentration is concurrently controlled and maintained at less than 0.01 molar.

Growing community of inventors

Penfield, NY, United States of America

Jong-Shinn Wey