Encapsulated superparamagnetic particles
AssigneeEastman Kodak Company
InventorJoseph S. Yudelson
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Abstract
Stable, encapsulated superparamagnetic magnetite particles having a narrow particle size distribution with average particle diameters in the range of from about 50 .ANG. to about 350 .ANG. are prepared by forming an aqueous dispersion of magnetite particles having the above particle size characteristics in the presence of a surfactant, coacervating a mixture of gelatin and a carboxyl containing hydrophilic polymer such as gum arabic to form a thin coating of coacervate on the magnetite particles and crosslinking the coacervate coating with a gelatin hardener such as glutaraldehyde.
Claims33
Encapsulated superparamagnetic particles having a narrow particle size distribution, the mean diameter of the particles being within the range of from about 70 .ANG. to about 450 .ANG., said particles comprising particles of magnetite having a narrow particle size distribution, the mean diameter of the magnetite particles being between about 50 .ANG. and about 350 .ANG., said magnetite particles having a magnetization of greater than about 30 emu/gm and a coercive force of less than about 30 Oe, said magnetite particles being encapsulated with a coating of a crosslinked coacervate of gelatin and a polymeric acid and wherein the weight ratio of magnetite to coacervate in said encapsulated particles on a dry basis is from 4:1 to 1:1.
Dependencies are inferred from the claim text.