The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 06, 2024
Filed:
Nov. 14, 2019
Dowa Electronics Materials Co., Ltd., Tokyo, JP;
Fujifilm Corporation, Tokyo, JP;
Hirohisa Omoto, Tokyo, JP;
Shuji Kaneda, Tokyo, JP;
Satoshi Shiki, Tokyo, JP;
Hiroyuki Suzuki, Kanagawa, JP;
Toshio Tada, Kanagawa, JP;
DOWA ELECTRONICS MATERIALS CO., LTD., Tokyo, JP;
FUJIFILM CORPORATION, Tokyo, JP;
Abstract
Provided is an Al-containing hexagonal ferrite magnetic powder which produces an excellent durability-improving effect on a magnetic recording medium, wherein uniform pulverization of the magnetic powder can be easily achieved by dispersion treatment in preparation of a magnetic coating material even in cases where the magnetic powder has a small primary particle size or has a composition which is likely to produce hard secondary particles. The magnetic powder for a magnetic recording medium is an Al-containing hexagonal ferrite magnetic powder having an Al/Fe molar ratio of 0.030 to 0.200, and has a particle size distribution in which the volume ratio of particles having a particle size of 30 μm or more as measured by a laser diffraction particle size distribution analyzer with a dispersion pressure of 100 kPa is 5.0% or less, and an activation volume Vact of 1800 nmor less.