Claims
- 1. A magnetic recording medium having a coercive force greater than 550 Oersteds, a ratio of the coercive force at -196.degree. C. to the coercive force at 25.degree. C. less than 1.8 and having an Fe.sup.+2 content of less than 1.0 wt.%, comprising: a magnetic powder obtained by dispersing acicular iron oxide in an aqueous solution of a cobalt salt and a reducing agent selected from the group consisting of hydrosulfite, sodium borohydride, hydrazine, hydrazine derivatives, and sodium hypophosphite, said solution being free of a chelating agent; and reacting said cobalt salt with said reducing agent thereby depositing a cobalt compound on the iron oxide base.
- 2. The magnetic recording medium of claim 1, wherein said reaction of said cobalt salt is conducted in the presence of a base at a temperature less than 100.degree. C.
- 3. The magnetic recording medium of claim 1, wherein the magnetic powder is prepared by depositing said cobalt compound on acicular .gamma.--Fe.sub.2 O.sub.3 by reacting said cobalt salt with said reducing agent in the presence of a base.
Priority Claims (1)
Number |
Date |
Country |
Kind |
53-30275 |
Mar 1978 |
JPX |
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Parent Case Info
This is a continuation, of application Ser. No. 16,008, filed Feb. 28, 1979, now abandoned.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
3958068 |
Umeki et al. |
May 1976 |
|
4069367 |
Umeki et al. |
Jan 1978 |
|
4112184 |
Umeki et al. |
Sep 1978 |
|
Continuations (1)
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Number |
Date |
Country |
Parent |
16008 |
Feb 1979 |
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