Magnetic particles
AssigneeEastman Kodak Company
InventorsRobert O. James, Sidney J. Bertucci, George L. Oltean
Life of this patent
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Abstract
Magnetic particles are cobalt surface treated gamma iron oxide (Fe.sub.2 O.sub.3) having a specific area of at least 30 m.sup.2 /g and a powder coercivity greater than about 450 Oe, the particles being coated with from about 10 to about 50% by weight of a material having a refractive index less than about the refractive index of a binder for the particles.
Claims12
Magnetic particles in a binder to form a transparent magnetic layer comprising a cobalt surface treated gamma iron oxide core having a specific surface area of at least 30 m.sup.2 /g and exhibiting a powder coercivity of greater than 450 Oe, the core surrounded by a shell, the shell comprising from 10 to 50 percent by weight of the total weight of the particle and being of a material having a refractive index less than the refractive index of the binder.
Magnetic particles comprising a cobalt surface treated gamma iron oxide core having a specific surface area of at least 30 m.sup.2 /g and exhibiting a powder coercivity of greater than 450 Oe, the core surrounded by a shell, the shell comprising from 10 to 50 percent by weight of the total weight of the particles of a material selected from the group consisting of silica, magnesium fluoride, calcium fluoride and fluorinated hydrocarbon resins.
Dependencies are inferred from the claim text.