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:
Aug. 15, 2000
Filed:
Sep. 10, 1998
Hiroki Kubo, Tochigi-ken, JP;
Hideyuki Kobayashi, Tochigi-ken, JP;
Kazutaka Yamashita, Tochigi-ken, JP;
Kao Corporation, Tokyo, JP;
Abstract
A magnetic recording medium comprising a nonmagnetic substrate having provided thereon an intermediate layer consisting essentially of magnetic powder having a Mohs hardness of not less than 3 and an average particle size of not greater than 0.5 .mu.m and/or nonmagnetic powder having a Mohs hardness of not less than 3, carbon black, and a binder and, as a top layer, a magnetic layer consisting essentially of ferromagnetic metal powder and a binder, in which said magnetic layer has an average center-line surface roughness (Ra) of not greater than 7 nm, and said magnetic layer has an average center-line surface roughness (Ra) of 10 to 30 nm after being immersed in a hydrochloric acid aqueous solution for 24 hours.