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US 5,332,645 AGranted
Low dusting carriers
AssigneeEastman Kodak Company
InventorsBijay S. Saha, James H. Anderson
Life of this patent
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AssigneeEastman Kodak Company
InventorsBijay S. Saha, James H. Anderson
Estimating the term…
A method of manufacturing improved strontium or barium ferrite carrier particles for use in two-component electrographic developer compositions for the development of electrostatic charge patterns is provided in which the tendency toward early life dusting of the strontium or barium ferrites is reduced. Such strontium or barium ferrite carrier particles are obtained by (i) mixing unreacted particles of iron oxide and barium or strontium oxide or, alternatively, a salt of barium or strontium convertible to the corresponding oxide by heat upon subsequent firing in a mole ratio of iron oxide to the metal oxide or salt of exactly 5.95 to 6.0:1 with an organic binder and a polar solvent, preferably water, to form a slurry, (ii) spray drying the slurry to obtain green beads of substantially uniform particle size and substantially spherical shape, and (iii) firing the beads at a temperature of from 1150.degree. to 1175.degree. C. for 10 hours to form magnetic strontium or barium ferrite carrier particles of substantially uniform particle size and substantially spherical shape having a reduced tendency towards early life dusting.
A method of producing hard magnetic strontium or barium ferrite carrier particles of substantially uniform particle size and substantially spherical shape suitable for magnetic brush development of electrostatic charge patterns and having a reduced tendency towards early life dusting which comprises:
A method of forming an electrographic developer composition suitable for magnetic brush development of electrostatic charge patterns containing hard magnetic strontium or barium ferrite carrier particles of substantially uniform particle size and substantially spherical shape which comprises:
An electrographic developer mixture suitable for magnetic brush development of electrostatic charge patterns having a reduced tendency towards early life dusting comprising finely-divided toner particles and hard magnetic strontium or barium ferrite carrier particles of substantially uniform particle size and substantially spherical shape, said carrier particles having been produced by:
Dependencies are inferred from the claim text.