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US 4,789,591 AGranted
Magnetic recording medium
AssigneeKonishiroku Photo Industry Co., Ltd.
InventorsIssei Nakamura, Kenji Itozawa
Life of this patent
Estimating the term…
Abstract
A magnetic recording medium comprising a support and a magnetic layer on said support. Said magnetic layer is a unitary magnetic layer comprising iron oxide powder having cobalt adsorbed on the surface thereof. The average grain size of said powder is not more than 0.5.mu., the ratio of the major axis to the minor axis (acicular ratio) of said powder is from 1.3 to 4.5 and the coercive force of said powder is from 500 to 800 Oe.
Claims19
A magnetic recording medium having improved thermal stability comprising a support and a magnetic layer on said support,
- said magnetic layer being a unitary magnetic layer comprising iron oxide powder having cobalt adsorbed on the surface thereof, the average grain size of said iron oxide powder being not more than 0.5.mu., the ratio of the major axis to the minor axis (acicular ratio) of said iron oxide powder being from 1.3 to 4.5 and the coercive force of said iron oxide powder being from 550 to 800 Oe.
Dependencies are inferred from the claim text.