Magnetic recording medium

• US 20060035114A1
• Filed: 08/11/2005
• Published: 02/16/2006
• Est. Priority Date: 08/12/2004
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Hitachi Maxell Limited (Hitachi, Ltd.)
• Inventors: Kuse, Sadamu, Nakiri, Kazuhiko
• Granted Patent: US 8,124,256 B2
• Time in Patent Office: Days
• US Class Current: 428/844
• CPC Class Codes: G11B 5/708 characterised by addition of non-magnetic particles to the layer
• CPC Class Codes: G11B 5/714 characterised by the dimension of the magnetic particles

Abstract

A magnetic recording medium with excellent high density recording performances and good durability comprising a non-magnetic substrate, a non-magnetic layer containing a non-magnetic powder and a binder formed on the non-magnetic substrate, and a magnetic layer having a thickness of less than 100 nm and containing a substantially particulate non-magnetic powder, a substantially particulate magnetic powder having an average particle size of less than 25 nm, and a binder, wherein an average particle size R of the non-magnetic powder contained in the magnetic layer and a thickness D of the magnetic powder satisfy the following relationship: 0.88≦R/D≦2.5.

Claims

1. A magnetic recording medium comprising

a non-magnetic substrate,

a non-magnetic layer containing a non-magnetic powder and a binder formed on the non-magnetic substrate, and

a magnetic layer having a thickness of less than 100 nm and containing a substantially particulate non-magnetic powder, a substantially particulate magnetic powder having an average particle size of less than 25 nm, and a binder wherein an average particle size R of the non-magnetic powder contained in the magnetic layer and a thickness D of the magnetic powder satisfy the following relationship:

0.88≦

R/D≦

2.5.

2. The magnetic recording medium according to claim 1, wherein the non-magnetic powder contained in the magnetic layer has an average particle size of less thane 200 nm.

3. The magnetic recording medium according to claim 1, wherein the non-magnetic powder contained in the magnetic layer has a Moh'"'"'s hardness of at least 6.

4. The magnetic recording medium according to claim 1, wherein the non-magnetic powder contained in the magnetic layer is at least one non-magnetic powder selected from the group of α

-alumina, β

-alumina, silicon carbide, chromium oxide, cerium oxide, α

-iron oxide, corundum, artificial diamond, silicon nitride, silicon carbide, titanium carbide, titanium oxide, silicon dioxide and boron nitride.

5. The magnetic recording medium according to claim 1, wherein the magnetic layer further comprises carbon black.