MAGNETIC POWDER FOR MAGNETIC RECORDING MEDIUM AND MANUFACTURING METHOD THEREOF

• Main Authors: SHIKI KEIJI, TADA TOSHIO, OMOTO HIROHISA, SUZUKI HIROYUKI, KANEDA HIDEHARU
• Format: Patent
• Language: English; Japanese
• Published: 04.06.2020
• Subjects: BASIC ELECTRIC ELEMENTS; CHEMISTRY; COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSESC01D OR C01F; ELECTRICITY; INDUCTANCES; INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; INORGANIC CHEMISTRY; MAGNETS; METALLURGY; PHYSICS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES; TRANSFORMERS

To provide Al-contained hexagonal crystal ferrite magnetic powder having an excellent durability improvement effect of a magnetic recording medium, which is hexagonal crystal ferrite magnetic powder that is easily and uniformly miniaturized by distribution processing when magnetic paint is made even if the magnetic powder has a small primary particle size or a composition in which the secondary particles tend to be hard.SOLUTION: Magnetic powder for a magnetic recording medium, which is Al-contained hexagonal crystal ferrite magnetic powder in which an Al/Fe mol ratio is 0.030-0.200, comprises particle size distribution in which a volume ratio of particles with a particle size of 30 μm or more measured under the condition of dispersion pressure of 100 kPa by a laser diffraction type particle size distribution measuring device is 5.0% or less, and activation volume Vact is 1800 nmor less.SELECTED DRAWING: None 【課題】磁気記録媒体の耐久性向上効果に優れるＡｌ含有六方晶フェライト磁性粉において、１次粒子のサイズが小さい磁性粉や、２次粒子が硬質となりやすい組成の磁性粉であっても、磁性塗料を作製するときの分散処理によって磁性粉の均一な微細化が容易である六方晶フェライト磁性粉を提供する。【解決手段】Ａｌ／Ｆｅモル比が０.０３０〜０.２００であるＡｌ含有六方晶フェライト磁性粉であって、レーザー回折式粒度分布測定装置により分散圧１００ｋＰａの条件で測定される粒子径３０μｍ以上の粒子の体積割合が５.０％以下である粒度分布を有し、活性化体積Ｖactが１８００ｎｍ3以下である、磁気記録媒体用磁性粉。【選択図】なし