Magnetic recording medium

• US 20030170498A1
• Filed: 03/11/2003
• Published: 09/11/2003
• Est. Priority Date: 03/11/2002
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Inoue, Noriko
• Granted Patent: US 6,800,356 B2
• Time in Patent Office: Days
• US Class Current: 428/694BB
• CPC Class Codes: G11B 5/735 characterised by the back layer magnetic recording media substrates G11B5/739
• CPC Class Codes: G11B 5/7356 comprising non-magnetic particles in the back layer, e.g. particles of TiO2, ZnO or SiO2
• CPC Class Codes: G11B 5/7358 specially adapted for achieving a specific property, e.g. average roughness [Ra]
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/257 Iron oxide or aluminum oxide
• CPC Class Codes: Y10T 428/265 1 mil or less

Abstract

A magnetic recording medium comprising: a magnetic layer comprising a ferromagnetic powder and a binder; a non-magnetic support; and a backcoating layer comprising a non-magnetic powder and a binder, in this order, wherein the backcoating layer comprises 0.3 to 5% by weight of at least one of a fatty acid having 10 to 26 carbon atoms and an ester thereof, the backcoating layer has projections having a height of 100 nm or smaller as measured with an atomic force microscope, and a density of projections on the backcoating layer which have a height of 25 to 100 nm as measured with an atomic force microscope is 1000 or fewer per 90 μm side square.

Claims

1. A magnetic recording medium comprising:

a magnetic layer comprising a ferromagnetic powder and a binder;

a non-magnetic support; and

a backcoating layer comprising a non-magnetic powder and a binder, in this order,

wherein the backcoating layer comprises 0.3 to 5% by weight of at least one of a fatty acid having 10 to 26 carbon atoms and an ester thereof, the backcoating layer has projections having a height of 100 nm or smaller as measured with an atomic force microscope, and a density of projections on the backcoating layer which have a height of 25 to 100 nm as measured with an atomic force microscope is 1000 or fewer per 90 μ

m side square.

2. The magnetic recording medium according to claim 1, wherein the backcoating layer has a thickness of 0.1 to 1.0 μ

m.

3. The magnetic recording medium according to claim 1, wherein the non-magnetic powder has an average particle size of 5 to 300 nm.

4. The magnetic recording medium according to claim 2, wherein the non-magnetic powder has an average particle size of 5 to 300 nm.

5. The magnetic recording medium according to claim 1, wherein the non-magnetic powder has an average particle size of 10 to 250 nm.

6. The magnetic recording medium according to claim 1, wherein the backcoating layer further comprises an electrically conductive powder having an average particle size of 10 to 150 nm.

7. The magnetic recording medium according to claim 2, wherein the backcoating layer further comprises an electrically conductive powder having an average particle size of 10 to 150 nm.

8. The magnetic recording medium according to claim 3, wherein the backcoating layer further comprises an electrically conductive powder having an average particle size of 10 to 150 nm.

9. The magnetic recording medium according to claim 4, wherein the backcoating layer further comprises an electrically conductive powder having an average particle size of 10 to 150 nm.

10. The magnetic recording medium according to claim 6, wherein the electrically conductive powder is carbon black.

11. The magnetic recording medium according to claim 1, wherein the density is 500 or fewer per 90 μ

m side square.

12. The magnetic recording medium according to claim 1, wherein the non-magnetic powder is an inorganic powder.

13. The magnetic recording medium according to claim 1, wherein the inorganic powder comprises an inorganic powder having a Mohs hardness of 5 to 9.

14. The magnetic recording medium according to claim 13, wherein the inorganic powder having a Mohs hardness of 5 to 9 comprises α

-iron oxide, α

-alumina, or chromium oxide.