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:
Jul. 03, 2007
Filed:
Apr. 02, 2003
Kazuyuki Matsumoto, Okayama, JP;
Kenichi Inoue, Okayama, JP;
Ken Inoue, Okayama, JP;
Dowa Mining Co., Ltd., Tokyo, JP;
Abstract
A powder for an underlayer of a coating-type magnetic recording medium, which powder comprises flat-acicular iron oxide particles having an average major axis length of 20–200 nm, a short axis cross-section taken perpendicularly to the long axis that has a long width and a short width, and a short axis cross-section ratio defined as the ratio of the long width to the short width that is greater than 1.3 and substantially uniform in the long axis direction, the powder having a specific surface area measured by the BET method of 30–100 m/g. The underlayer powder preferably contains 0.1–5.0 wt % of P and, optionally, an amount of R(R representing one or more rare earth elements, defined as including Y) such that R/Fe expressed in atomic percentage (at. %) is 0.1–10 at. %.