Data recording method

• US 20010038928A1
• Filed: 01/22/2001
• Published: 11/08/2001
• Est. Priority Date: 03/14/1997
• Status: Abandoned Application

• Current Assignee: Hiroshi Hashimoto, Hitoshi Noguchi, Junichi Nakamigawa, Nobuo Yamazaki, Shinji Saito
• Original Assignee: Hiroshi Hashimoto, Hitoshi Noguchi, Junichi Nakamigawa, Nobuo Yamazaki, Shinji Saito
• Inventors: Nakamigawa, Junichi, Yamazaki, Nobuo, Hashimoto, Hiroshi, Saito, Shinji, Noguchi, Hitoshi
• Application Number:
  US09/768,373
• Publication Number:
  US 20010038928A1
• Time in Patent Office: Days
• US Class Current: 428/694BS
• CPC Class Codes: G11B 5/70 on a base layer
• CPC Class Codes: G11B 5/71 characterised by the lubricant
• CPC Class Codes: G11B 5/714 characterised by the dimension of the magnetic particles

Abstract

A magnetic recording medium is described, which comprises a support having thereon a substantially non-magnetic lower layer and a magnetic layer comprising a ferromagnetic metal powder or a ferromagnetic hexagonal ferrite powder dispersed in a binder provided on the lower layer, which is a magnetic recording medium for recording signals of from 0.17 to 2 G bit/inch² of areal recording density, wherein the dry thickness of the magnetic layer is from 0.05 to 0.30 μm, the coercive force of the magnetic layer is 1,800 Oe or more, and the lower layer and/or the magnetic layer have(has) at least three in total of a fatty acid and/or a fatty acid ester.

Claims

1. A magnetic recording medium which comprises a support having thereon a substantially nonmagnetic lower layer and a magnetic layer comprising a ferromagnetic metal powder or a ferromagnetic hexagonal ferrite powder dispersed in a binder provided on said lower layer, which is a magnetic recording medium for recording signals of from 0.17 to 2 G bit/inch² of areal recording density, wherein the dry thickness of the magnetic layer is from 0.05 to 0.30 μ

m, the coercive force of the magnetic layer is 1,800 Oe or more, and the lower layer and/or the magnetic layer have(has) at least three in total of a fatty acid and/or a fatty acid ester.

2. The magnetic recording medium as claimed in

claim 1

, wherein said magnetic layer has (m of from 8.0×

10<sup>−

3</sup> to 1.0×

10<sup>−

3</sup> emu/cm² and a coercive force of 2,100 Oe or more.

3. The magnetic recording medium as claimed in

claim 1

, wherein said fatty acid and said fatty acid ester have the same fatty acid residues with each other.

4. The magnetic recording medium as claimed in

claim 1

, wherein said fatty acid contains at least a saturated fatty acid and said fatty acid ester contains at least a saturated fatty acid ester or an unsaturated fatty acid ester.

5. The magnetic recording medium as claimed in

claim 1

, wherein said fatty acid ester contains a monoester and a diester.

6. The magnetic recording medium as claimed in

claim 1

, wherein said fatty acid ester contains a saturated fatty acid ester and an unsaturated fatty acid ester.

7. The magnetic recording medium as claimed in

claim 1

, wherein the surface of said magnetic layer has a C/Fe peak ratio of from 5 to 100 when the surface is measured by the Auger electron spectroscopy.

8. The magnetic recording medium as claimed in

claim 6

, wherein said magnetic layer contains from 8 to 30 weight parts of said fatty acid ester per 100 weight parts of said ferromagnetic powder and/or said nonmagnetic lower layer contains from 8 to 30 weight parts of said fatty acid ester per 100 weight parts of said nonmagnetic powder contained in said lower layer, and said magnetic recording medium is a disc-like medium.

9. The magnetic recording medium as claimed in

claim 1

, wherein said fatty acid ester is represented by formula R1—

COO—

R2—

OCO—

R3, R4—

COO—

(R5—

O)_m—

R6 (wherein m represents an integer of from 1 to

     10), or R7—

COO—

R8 (wherein R2 and R5 each represents —

(CH₂)_n—

, a divalent group derived from —

[CH₂)_n—

which may contain an unsaturated bond (wherein n represents an integer of from 1 to

     12), —

[CH₂CH(CH₃)]—

or —

(CH₂C(CH₃)₂CH₂]—

;

R1, R3, R4 and R7, which may be the same or different, each represents a chain-like, saturated or unsaturated hydrocarbon group having from 12 to 30 carbon atoms; and

R6 and R8, which may be the same or different, each represents a chain-like or branched, saturated or unsaturated hydrocarbon group having from 1 to 26 carbon atoms).

10. The magnetic recording medium as claimed in

claim 1

, wherein said magnetic layer has a dry thickness of from 0.05 to 0.25 μ

m and said magnetic layer contains an abrasive having an average particle size of 0.4 μ

m or less.

11. The magnetic recording medium as claimed in

claim 1

, wherein said magnetic recording medium is used for recording signals of from 0.20 to 2 G bit/inch² of areal recording density and said lower layer contains an inorganic powder having a Mohs'"'"' hardness of 4 or more.

12. The magnetic recording medium as claimed in

claim 1

, wherein said ferromagnetic metal powder comprises Fe as a main component and said ferromagnetic metal powder has a long axis length of 0.12 μ

m or less and a crystallite size of from 80 to 180 Å

.

13. The magnetic recording medium as claimed in

claim 12

, wherein the Al/Fe ratio of said ferromagnetic metal powder is from 5 atomic % to 30 atomic %.

14. The magnetic recording medium as claimed in

claim 1

, wherein said magnetic recording medium is a disc-like magnetic recording medium for a recording/reproduction system of a rotation number of 1,800 rpm or more.

15. A magnetic recording medium which comprises a support having thereon a substantially nonmagnetic lower layer and magnetic layer comprising a ferromagnetic metal powder dispersed in a binder provided on said lower layer, wherein said magnetic layer contains from 8 to 30 weight parts of a fatty acid ester per 100 weight parts of said ferromagnetic metal powder and/or said nonmagnetic lower layer contains from 8 to 30 weight parts of a fatty acid ester per 100 weight parts of said nonmagnetic powder contained in said lower layer, the surface of said magnetic layer has a C/Fe peak ratio of from 5 to 100 when the surface is measured by the Auger electron spectroscopy, and said magnetic recording medium is a disc-like medium.

16. A magnetic recording medium, comprising:

a support;

at least one lower layer disposed over the support,

at least one magnetic layer formed over the lower layer, said magnetic layer comprising a ferromagnetic metal powder or a ferromagnetic hexagonal ferrite powder dispersed in a binder, said magnetic layer having an areal recording density of from 0.17 to 2 G bit/inch² and a coercive force of 1,800 Oe or more.

17. The magnetic recording medium as claimed in

claim 16

, wherein said magnetic layer has a dry thickness of from 0.05 to 0.30 μ

m.

18. The magnetic recording medium as claimed in

claim 16

, wherein the lower layer and/or the magnetic layer comprises an effective amount of at least one fatty acid or fatty acid derivative for providing a lubricating effect.