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:
Mar. 14, 2000
Filed:
Jul. 06, 1998
Kazunori Kubota, Moriguchi, JP;
Fumio Echigo, Osaka, JP;
Yukihiro Shimasaki, Sanda, JP;
Takumi Haneda, Suita, JP;
Hirofumi Ito, Osaka, JP;
Tetuo Fuchi, Osaka, JP;
Kiyoshi Kobata, Takatsuki, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
The present invention provides a thin multilayer magnetic recording medium having improved electromagnetic conversion property and durability, comprising coating layers of a lower non-magnetic layer and an upper magnetic layer. The non-magnetic layer of this magnetic recording medium comprises a non-magnetic needle body having an average major axis length of 0.25 to 1.0 .mu.m and an average minor axis length of 0.005 to 0.0151 .mu.m, a first binding resin having a glass transition temperature (Tg.sub.1) of 30 to 50.degree. C., and fatty acid ester. The content of the first binding resin is 15 to 30 wt % with respect to the non-magnetic needle body. The content of the fatty acid ester is 2 to 15 wt % with respect to the first binding resin. The magnetic layer having a dry thickness of 0.5 .mu.m or less comprises ferromagnetic powder and a second binding resin having a glass transition temperature (Tg.sub.2) of 40 to 70.degree. C. Tg.sub.1 is at least 5.degree. C. lower than Tg.sub.2, and the entire thickness comprising the layers and the film is 12 .mu.m or less.