摘要 |
PURPOSE:To manufacture titled magnetic material from which a magnetic tape having excellent dispersion properties and good performance is obtained by coating fatty acid on acicular iron oxyhydroxide and dehydrating and thereafter reducing it in the nonoxidizing atmosphere and coating a Co compound on the needle-like gamma-Fe2O3 obtained by oxidation. CONSTITUTION:After 4-24C fatty acid is coated on acicular iron oxyhydroxide, it is dehydrated at 250-300 deg.C in the nonoxidizing atmosphere and thereafter reduced at 370-500 deg.C in said atmosphere. On the occasion, when the hydrating reaction at the former stage is not finished thoroughly and thereafter the reducing reaction is performed, the homogeneity of granule surface of the obtained gamma-Fe2O3 is marred and the distribution of coercive force is spread and the distribution of inversional magnetic field is narrowed. The acicular gamma-Fe2O3 is manufactured by oxidizing the obtained reduced material at about 150-450 deg.C and coating a Co compound (e.g. CoSO4 or the like) thereon. The obtained titled magnetic material has excellent dispersion properties and the magnetic tape manufactured using the material has good rectangular ratio and ori entative properties and simultaneously good dispersion of inversional magnetic field due to uniform distribution of coercive force and erasing characteristics. |