Magnetic recording medium and method of manufacturing the same

Patent metadata

Field	Value
Publication number	US-9401171-B2
Application number	US-201313838996-A
Country	US
Kind code	B2
Filing date	Mar 15, 2013
Priority date	Mar 30, 2012
Publication date	Jul 26, 2016
Grant date	Jul 26, 2016

Abstract

An aspect of the present invention relates to a magnetic recording medium, which comprises a nonmagnetic layer containing a nonmagnetic powder and a binder and a magnetic layer containing a ferromagnetic powder and a binder in this order on a nonmagnetic support, wherein the nonmagnetic layer has a thickness of equal to or less than 300 nm; a composite elastic modulus as measured on a surface of the magnetic layer ranges from 6.0 to 8.0 GPa; the magnetic layer comprises an abrasive with a specific surface area by BET method ranging from 14 m 2 /g to 40 m 2 /g; and a surface abrasive occupancy on a surface of the magnetic layer ranges from 0.2% to 2%.

First claim

What is claimed is:

1. A magnetic recording medium, which comprises a nonmagnetic layer containing a nonmagnetic powder and a binder and a magnetic layer containing a ferromagnetic powder and a binder in this order on a nonmagnetic support, wherein
the nonmagnetic layer has a thickness of equal to or less than 300 nm;
a composite elastic modulus as measured on a surface of the magnetic layer ranges from 6.0 to 8.0 GPa;
the magnetic layer comprises an abrasive with a specific surface area by BET method ranging from 14 m 2 /g to 40 m 2 /g; and
a surface abrasive occupancy on a surface of the magnetic layer ranges from 0.2% to 0.9%.

2. The magnetic recording medium according to claim 1 , wherein the abrasive is alumina.

3. The magnetic recording medium according to claim 2 , wherein the magnetic layer further comprises an aromatic hydrocarbon compound having a phenolic hydroxyl group.

4. The magnetic recording medium according to claim 3 , wherein the aromatic hydrocarbon compound having a phenolic hydroxyl group is a compound denoted by general formula (1):

wherein, in general formula (1), two from among X 1 to X 8 denote hydroxyl groups and each of the remaining portions independently denotes a hydrogen atom or a substituent.

5. The magnetic recording medium according to claim 3 , wherein the aromatic hydrocarbon compound having a phenolic hydroxyl group is selected from the group consisting of 2,3-dihydroxylnaphthalene and derivatives thereof.

6. The magnetic recording medium according to claim 1 , wherein the magnetic layer further comprises a nonmagnetic particle other than the abrasive.

7. The magnetic recording medium according to claim 1 , wherein the magnetic layer further comprises a nonmagnetic particle other than the abrasive, and the nonmagnetic particle is a silica colloidal particle.

8. The magnetic recording medium according to claim 2 , wherein the magnetic layer further comprises a nonmagnetic particle other than the abrasive, and the nonmagnetic particle is a silica colloidal particle.

9. The magnetic recording medium according to claim 3 , wherein the magnetic layer further comprises a nonmagnetic particle other than the abrasive, and the nonmagnetic particle is a silica colloidal particle.

10. The magnetic recording medium according to claim 4 , wherein the magnetic layer further comprises a nonmagnetic particle other than the abrasive, and the nonmagnetic particle is a silica colloidal particle.

11. The magnetic recording medium according to claim 5 , wherein the magnetic layer further comprises a nonmagnetic particle other than the abrasive, and the nonmagnetic particle is a silica colloidal particle.

Assignees

• Fujifilm Corp

Inventors

• Kasada Norihito
• Sato Masahide
• Watanabe Isamu

Classifications

• G11B5/7085 Primary

  non-magnetic abrasive particles · CPC title

• G11B5/7013

  characterised by the dispersing agent · CPC title

• G11B5/70

  on a base layer · CPC title

• G11B5/842

  Coating a support with a liquid magnetic dispersion · CPC title