| 摘要 |
PURPOSE:To manufacture intimate mixture which is coated with coupling agent and is excellent in performance, by adding the coupling agent to suspension liquid obtained by liquid-incorporating gamma-Fe2O3 and needle type CrO2 powder of specified percentages, and filtrating-drying the intimate mixture from the suspension liquid. CONSTITUTION:To liquid dispersion medium, 5-20wt.% of mixture of the following is added, stirred, and mixed to obtain suspension liquid; Co-coated needle type gamma-Fe2O3 particle powder whose BET specific surface is larger than 30m<2>/g, and 5-100wt.% of needle type CrO2 particle powder whose BET specific surface is larger than 20m<2>/g. Coupling agent in the liquid state is added to the above suspension liquid, and stirred and mixed. After that, the mixture is filtrated from the suspension liquid and dried, thereby obtaining mixture coated with the coupling agent. Hence magnetic particle powder which has a high saturation magnetization value, excellent dispersion and low optical transmittance is obtained, and suitably used for high density recording. |
