Magnetic recording medium

• US 6,852,404 B2
• Filed: 03/27/2003
• Issued: 02/08/2005
• Est. Priority Date: 03/29/2002
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Kaizu, Akimasa, Inoue, Osamu, Kuwajima, Takayoshi
• Primary Examiner(s): Resan, Stevan A.
• Application Number:
  US10/397,519
• Publication Number:
  US 20040110033A1
• Time in Patent Office: 684 Days
• Field of Search: 428/323, 428/328, 428/336, 428/694.BA
• US Class Current: 428/839.3
• CPC Class Codes: G11B 5/70 on a base layer
• CPC Class Codes: G11B 5/70621 containing Co metal or alloys
• CPC Class Codes: G11B 5/714 characterised by the dimension of the magnetic particles
• CPC Class Codes: G11B 5/73 Base layers , i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
• CPC Class Codes: Y10T 428/256 Heavy metal or aluminum or compound thereof
• CPC Class Codes: Y10T 428/265 1 mil or less

Abstract

The average major-axis length (L) of a ferromagnetic alloy powder primarily contained together with a binder in a magnetic layer provided on at least one surface of a non-magnetic support is less than 0.10 μm, and the ferromagnetic alloy powder contains Co at a content of 15 to 28 at % relative to Fe, and furthermore, contains Y at a content of 22 μmol/m2 or more with respect to a specific surface area (Sc) calculated from the above-mentioned average major-axis length (L) and the crystallite diameter (d). A coating-type high-recording-density magnetic recording medium has excellent surface properties, an excellent electromagnetic transducing characteristic especially in short wavelength regions and high reliability.

Claims

1. A magnetic recording medium, wherein the average major-axis length (L) of a ferromagnetic alloy powder primarily contained together with a binder in a magnetic layer provided on at least one surface of a non-magnetic support is less than 0.10 μ

m, and wherein the ferromagnetic alloy powder contains Co at a content of 15 to 28 at % relative to Fe, and contains Y at a content of 22 μ

mol/m² or more with respect to a specific surface area (Sc) calculated from the average major-axis length (L) and the crystallite diameter (d).

2. The magnetic recording medium according to claim 1, wherein the ferromagnetic alloy powder contains Al at a content within the range of 27 to 45 μ

mol/m² with respect to the specific surface area (Sc).

3. The magnetic recording medium according to claim 2, wherein the average thickness of the magnetic layer is 0.03 to 0.30 μ

m, and wherein a non-magnetic layer is provided between the non-magnetic support and the magnetic layer.

4. The magnetic recording medium according to claim 1, wherein the average thickness of the magnetic layer is 0.03 to 0.30 μ

m, and wherein a non-magnetic layer is provided between the non-magnetic support and the magnetic layer.

5. The magnetic recording medium according to claim 1, wherein the average major-access length (L) of the ferromagnetic alloy powder is from 0.03 to 0.8 μ

m.

6. The magnetic recording medium according to claim 1, wherein Y is present in an amount of 24 μ

mol/m² or more.

7. The magnetic recording medium according to claim 1, wherein Y is present in an amount of 27 μ

mol/m² or more.

8. The magnetic recording medium according to claim 1, wherein the ferromagnetic alloy powder contains Al at a content within the range of 27 to 40 μ

mol/m² relative to the specific surface area (Sc).

9. The magnetic recording medium according to claim 1, wherein Co/Fe in the ferromagnetic alloy powder is from 16 to 24.

10. The magnetic recording medium according to claim 1, wherein Y/(Fe+Co) is from 7.9 to 9.8.

11. A magnetic recording medium, wherein the average major-axis length (L) of a ferromagnetic alloy powder primarily contained together with a binder in a magnetic layer provided on at least one surface of a non-magnetic support is less than 0.10 μ

m, and wherein the ferromagnetic alloy powder contains Co at a content of 15 to 28 at % relative to Fe, and contains Y at a content of 20 μ

mol/m² or more with respect to a BET specific surface area (Sbet) of the ferromagnetic alloy powder.

12. The magnetic recording medium according to claim 11, wherein the ferromagnetic alloy powder contains Al at a content within the range of 22 to 38 μ

mol/m² with respect to the BET specific surface area (Sbet) of the ferromagnetic alloy powder.

13. The magnetic recording medium according to claim 12, wherein the average thickness of the magnetic layer is 0.03 to 0.30 μ

m, and wherein a non-magnetic layer is provided between the non-magnetic support and the magnetic layer.

14. The magnetic recording medium according to claim 11, wherein the average thickness of the magnetic layer is 0.03 to 0.30 μ

m, and wherein a non-magnetic layer is provided between the non-magnetic support and the magnetic layer.

15. The magnetic recording medium according to claim 11, wherein the average major-access length (L) of the ferromagnetic alloy powder is from 0.03 to 0.8 μ

m.

16. The magnetic recording medium according to claim 11, wherein Y is present in an amount of 22 μ

mol/m² or more.

17. The magnetic recording medium according to claim 11, wherein Y is present in an amount of 24 μ

mol/m² or more.

18. The magnetic recording medium according to claim 11, wherein the ferromagnetic alloy powder contains Al at a content within the range of 22 to 34 μ

mol/m² with respect to a BET specific surface area (Sbet).

19. The magnetic recording medium according to claim 11, wherein Co/Fe in the ferromagnetic alloy powder is from 16 to 24.

20. The magnetic recording medium according to claim 11, wherein Y/(Fe+Co) is from 7.9 to 9.8.