Eastman-kodak Company

Michael G Antoniades

Xin Wen

Joe E Maskasky

Roger L Lok

Thomas B Brust

Joseph C Deaton

Ramesh Jagannathan

Donald L Black

Jeffrey L Hall

Richard L Daubendiek

Jerzy A Budz

Allen K Tsaur

Yun C Chang

Gary L House

Benjamin T Chen

David E Fenton

John E Keevert

Lyn M Eshelman

Jess B Hendricks, Iii

Sharon G Johnston

Paul J Madigan

Sucheta Tandon

Heinz E Stapelfeldt

Sherrill A Puckett

Donald Robert Irwin

Debra L Hartsell

Douglas E Singer

Katrin I Parsiegla

Harold G Judd

David A Dumont

Mark Jay Herman

A mixer for preparing silver halide grains for photographic use has upper and lower impellers housed in a draft tube. The bottom impeller has flat blades for micromixing silver and halide reactants introduced into the bottom of the draft tube. The upper impeller has pitched blades for macromixing the bulk fluid. The impellers are spaced apart at least the distance of their diameters so that the upper and lower impellers operate independently of one another so that micromixing is independent of macromixing. A flow disrupter structurally associated with the draft tube and positioned above the top impeller prevents vortexing of the fluid during mixing. Baffles may be provided in the draft tube to discourage vortexing.

Scalable impeller apparatus for preparing silver halide grains

A process for preparing an ultrathin high bromide &lcub;111&rcub; tabular grain silver halide emulsion in a reaction vessel comprising the steps of (a) forming in the presence of a dispersing medium a population of silver halide grain nuclei containing twin planes, and (b) growing the silver halide grain nuclei containing twin planes to form high bromide &lcub;111&rcub; tabular silver halide grains by the addition of silver and halide ions, WHEREIN the majority of the silver added during growth step (b) is added at a pBr of less than 2.6 and in the presence of a triaminopyrimidine grain growth modifier containing mutually independent 4, 5 and 6 ring position amino substituents, the 4 and 6 ring position substituents being hydroamino substituents. High bromide ultrathin &lcub;111&rcub; tabular grain emulsions prepared by the process of the invention provide thinner tabular grains than that obtained in the absence of the triaminopyrimidine grain growth modifier. Additionally, the double jet process of the invention is highly controllable and commercially scalable.

Process for the preparation of high bromide ultrathin tabular grain emulsions

A process is disclosed of preparing a high bromide tabular grain emulsion comprising (1) in a grain nucleation step creating in a dispersing medium tabular grain nuclei containing parallel twin planes and (2) in a grain growth step subsequently growing the grain nuclei into tabular grains by running into the dispersing medium high bromide silver halide grains having a maximum equivalent circular diameter of less than 40 nm, wherein (a) the high bromide grains are formed prior to the grain nucleation step and then held in the presence of a grain growth restrainer adsorbed to the grain surfaces to inhibit grain ripening and (b) during the growth step the restrainer is desorbed from the high bromide grains and silver and halide ions forming the high bromide grains are released by ripening into the dispersing medium in the growth step.

Process for the preparation of high bromide tabular grain emulsions

A radiation-sensitive spectrally sensitized tabular grain emulsion is disclosed which exhibits improved speed and contrast. The tabular grains have {111} major faces, contain greater than 70 mole percent bromide and up to 10 mole percent iodide, based on silver, account for greater than 90 percent of total grain projected area, and have an average equivalent circular diameter of at least 3.5 .mu.m. The tabular grains have latent image forming chemical sensitization sites on their surfaces including epitaxially deposited silver halide protrusions of a face centered cubic rock salt crystal lattice structure forming epitaxial junctions with the tabular grains. The protrusions are restricted to those portions of the tabular grains located nearest peripheral edges of and accounting for less than 10 percent of the {111} major faces of the tabular grains, accounting for less than 5 percent of total silver forming the tabular grains and protrusions, containing a silver chloride concentration at least 10 mole percent higher than that of the tabular grains, and contain at least 1 mole percent iodide, based on silver in the protrusions.

Epitaxially sensitized tabular grain emulsions exhibiting enhanced speed

The invention provides a method of measuring to control silver halide grain formation during nucleation and ripening comprising

Method for optimizing tabular grain population of silver halide

Silver halide emulsions are disclosed in which at least 50 percent of total grain projected area is accounted for by tabular grains (1) bounded by {100} major faces having adjacent edge ratios of less than 10, (2) each having an aspect ratio of at least 2, and (3) internally at their nucleation site containing iodide and at least 50 mole percent chloride. The emulsions are prepared by a process comprised of the steps of (a) introducing silver and halide salts into a dispersing medium so that nucleation of the tabular grains occurs in the presence of iodide with chloride accounting for at least 50 mole percent of the halide present in the dispersing medium and the pCl of the dispersing medium being maintained in the range of from 0.5 to 3.5 and (b) following nucleation completing grain growth under conditions that maintain the {100} major faces of the tabular grains.

High chloride tabular grain emulsions and processes for their preparation

Novel tabular grain emulsions and a process for their preparation are disclosed in which silver bromoiodide tabular grains account for greater than 97 percent of total grain projected area and the coefficient of variation of the total grain population is less than 25 percent. This is achieved by forming in a first reaction vessel and transporting to a second reaction vessel a population of silver bromide grain nuclei in the form of regular octahedra having an equivalent circular diameter of less than 40 nanometers and a coefficient of variation of less than 50 percent and in the second reaction vessel converting the grain nuclei into a grain population containing parallel twin planes in more than 90 percent of the grains, so that upon further growth silver bromoiodide tabular grains of desired properties can be realized. A photographic element is disclosed comprised of a support, a first silver halide emulsion layer responsive to minus blue (500 to 700 nm) light and a second silver halide emulsion layer positioned to overlie the first emulsion layer. In the second emulsion layer greater than 97 percent of the total projected area of grains having an equivalent circular diameter of at least 0.2 .mu.m is accounted for by silver bromoiodide tabular grains having an average equivalent circular diameter of at least 0.7 .mu.m and an average thickness of less than 0.07 .mu.m.

Photographic elements including highly uniform silver bromoiodide

Growing community of inventors

Rochester, NY, United States of America

Michael G Antoniades