Magnetic recording medium and process for producing the same

Abstract

A magnetic recording medium comprising a substrate and a magnetic layer containing ferromagnetic metal powder and a binder, wherein the ferromagnetic metal powder contains iron, cobalt and form 2 to 20 atom % of yttrium based on a total of iron and cobalt contained in the ferromagnetic metal powder and has an average length of 50 nm or smaller, and the magnetic recording medium has a test value of at least 100 passes in a magnetoresistive head resistance reduction test performed as defined herein.

Description

Claims

1. A magnetic recording medium comprising a substrate and a magnetic layer containing ferromagnetic metal powder and a binder, wherein the ferromagnetic metal powder contains iron, cobalt and from 2 to 20 atom % of yttrium based on a total of iron and cobalt contained in the ferromagnetic metal powder and has an average length of 50 nm or smaller, andthe magnetic recording medium has a test value of at least 100 passes in a magnetoresistive head resistance reduction test performed as follows:A 600 m long magnetic recording medium of tape form is recorded and repeatedly reproduced while being shuttled on a drive equipped with an MR head in a 13° C., 15% RH environment until the resistance of the MR head reduces by 40 Ω, and a number of passes of the tape at that time is a test value.

2. The magnetic recording medium according to claim 1, wherein the magnetic layer has a thickness of 100 nm or smaller.

3. The magnetic recording medium according to claim 1, wherein the ferromagnetic metal powder has an average breadth of 15 nm or smaller.

4. The magnetic recording medium according to claim 1, further comprising a nonmagnetic layer containing nonmagnetic powder and a binder between the substrate and the magnetic layer.

5. The magnetic recording medium according to claim 1, wherein a fragment intensity of fatty acid metal salt on a surface of the magnetic layer detected by use of a time-of-flight secondary ion mass spectrometer is 1% or less based on a total fragment intensity of iron and cobalt on the surface of the magnetic layer.

6. The magnetic recording medium according to claim 1, wherein a fragment intensity of fatty acid metal salt on a surface of the magnetic layer detected by use of a time-of-flight secondary ion mass spectrometer is 0.7% or less based on a total fragment intensity of iron and cobalt on the surface of the magnetic layer.

7. A process for producing the magnetic recording medium according to claim 1, comprising: detecting fragment ions of an organic compound on a surface of the magnetic layer by use of a time-of-flight secondary ion mass spectrometer.

8. The process according to claim 7, wherein the organic compound is a fatty acid metal salt.

9. The process according to claim 8, wherein a fragment intensity of the fatty acid metal salt is 1% or less based on a total fragment intensity of iron and cobalt.

10. The process according to claim 9, wherein the fatty acid metal salt is a yttrium salt, and a fragment intensity of the yttrium salt is 1% or less based on the total fragment intensity of iron and cobalt.