IP Library Granted Patent US 9,767,835
Granted Patent B2
US 9,767,835 · App. 15/054,887 · Granted Sep 19, 2017

Magnetic recording medium

Inventors: Kenji Tanaka (Osaka, JP); Masao Fujita (Osaka, JP); Sadamu Kuse (Osaka, JP)
Assignee: HITACHI MAXELL, LTD.
G11B5/71G11B5/70615G11B5/70626G11B5/714G11B5/738G11B5/78
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Quick Facts
Patent No.
US 9,767,835
App. No.
15/054,887
Granted
Sep 19, 2017
Kind
B2
Abstract

A magnetic recording medium of the present invention is a magnetic recording medium including a non-magnetic substrate; a non-magnetic layer that is formed on one of principal surfaces of the non-magnetic substrate and contains a non-magnetic powder, a binder, and a lubricant; and a magnetic layer that is formed on a principal surface of the non-magnetic layer opposite to the non-magnetic substrate and contains a magnetic powder and a binder. The magnetic powder has an average particle size between 10 nm and 35 nm inclusive. The lubricant is migratable to the magnetic layer and forms a lubricant layer on a surface of the magnetic layer when a pressure is applied to the magnetic layer. When spacing of the surface of the magnetic layer before and after washing the lubricant with n-hexane is measured with a TSA (Tape Spacing Analyzer), the value of the spacing after washing is 3 to 10 nm, and the value of the spacing before washing is 1 to 5 nm smaller than the value of the spacing after washing.

Claims (8)

1. A magnetic recording medium comprising a non-magnetic substrate; a non-magnetic layer that is formed on one of principal surfaces of the non-magnetic substrate and contains a non-magnetic powder, a binder, and a lubricant; and a magnetic layer that is formed on a principal surface of the non-magnetic layer opposite to the non-magnetic substrate and contains a magnetic powder and a binder,

wherein the magnetic powder is either a platy hexagonal ferrite magnetic powder or a spherical iron nitride magnetic powder,

the magnetic layer has a thickness of 10 to 150 nm,

the magnetic layer has a surface roughness of 1 nm or more and less than 2 nm, and

when spacing of the surface of the magnetic layer before and after washing the magnetic recording medium with n-hexane is measured with a TSA (Tape Spacing Analyzer) while pressurizing the surface of the magnetic recording medium under a pressing pressure of 0.5 atm, the value of the spacing before washing is 1 to 5 nm smaller than the value of the spacing after washing, and

the value of the spacing after washing is between 5 nm and 10 nm.

2. The magnetic recording medium according to claim 1 ,

wherein the magnetic powder has an average particle size between 15 nm and 35 nm.

Assignments (1)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Sep 29, 2017
From: HITACHI MAXELL, LTD.
To: FUJIFILM CORPORATION
Reel/Frame 044053/0281 →
Priority Claims (1)
JP 2010-182373 · Aug 17, 2010 · national
Continuity (2)
Division 13211051 · Aug 16, 2011
Related Publication 20160180875A1 · Jun 23, 2016