| 摘要 |
PURPOSE:To obtain the ferromagnetic metal powder applied to audio-appliances and VTRs which consists of iron mainly and has the exceedingly improved characteristics by using Fe including at least B coated with an alkylphenol polycondensate as a main component. CONSTITUTION:The ferromagnetic metal powder fine particle mainly consisting of iron for this use are manufactured by coating a surface part of the fine particle of needle oxy iron hydroxide with zinc borate as a shape retentive component and subjecting the particles to cleaning, drying, and milling followed by calcination and gas-phase catalytic reduction. The reduced iron powder fine particles preferably include B as the shape retentive component at least within a range of 0.1-5 atomic weight percentage to Fe. If the percentage is under the above range, the performance of forming a polycondensate consisting of alkylphenol group is low and the effect that the characteristic of deterioration with aging of the ferromagnetic metal powder fine particles is improved is diminished. If the percentage is over the range, the formation of the polycondensate consisting of alkylphenol group progresses too intensively so that the dispersion property during a step of conversion into coating compositions is lowered though affinity for a binder resin is improved. |
