MAGNETIC RECORDING MEDIUM

• US 20130084470A1
• Filed: 10/01/2012
• Published: 04/04/2013
• Est. Priority Date: 09/30/2011
• Status: Abandoned Application

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: HATTORI, Yasushi, SUZUKI, Ryota, KASADA, Norihito
• Application Number:
  US13/632,627
• Publication Number:
  US 20130084470A1
• Time in Patent Office: Days
• US Class Current: 428/842.3
• CPC Class Codes: G11B 5/7013 characterised by the dispersing agent
• CPC Class Codes: G11B 5/70678 Ferrites
• CPC Class Codes: G11B 5/7085 non-magnetic abrasive particles

Abstract

An aspect of the present invention relates to a magnetic recording medium comprising a magnetic layer containing a ferromagnetic powder and a binder on a nonmagnetic support, wherein the ferromagnetic powder has a hexagonal ferrite structure, the magnetic layer comprises a coefficient of friction-lowering component in the form of nonmagnetic inorganic particles, and a compound in which a substituent selected from the group consisting of a hydroxyl group and a carboxyl group is directly substituted on an aromatic ring.

Claims

1. A magnetic recording medium comprising a magnetic layer containing a ferromagnetic powder and a binder on a nonmagnetic support, wherein

the ferromagnetic powder has a hexagonal ferrite structure,

the magnetic layer comprises:

a coefficient of friction-lowering component in the form of nonmagnetic inorganic particles, and

a compound in which a substituent selected from the group consisting of a hydroxyl group and a carboxyl group is directly substituted on an aromatic ring.

2. The magnetic recording medium according to claim 1, wherein the ferromagnetic powder is a hydrogen reduction product of a ferromagnetic hexagonal ferrite powder.

3. The magnetic recording medium according to claim 1, wherein the magnetic layer comprises no carbon black.

4. The magnetic recording medium according to claim 2, wherein the magnetic layer comprises no carbon black.

5. The magnetic recording medium according to claim 1, wherein the nonmagnetic inorganic particles are inorganic oxide colloid particles.

6. The magnetic recording medium according to claim 2, wherein the nonmagnetic inorganic particles are inorganic oxide colloid particles.

7. The magnetic recording medium according to claim 3, wherein the nonmagnetic inorganic particles are inorganic oxide colloid particles.

8. The magnetic recording medium according to claim 1, wherein the nonmagnetic inorganic particles are silica colloid particles.

9. The magnetic recording medium according to claim 2, wherein the nonmagnetic inorganic particles are silica colloid particles.

10. The magnetic recording medium according to claim 3, wherein the nonmagnetic inorganic particles are silica colloid particles.

11. The magnetic recording medium according to claim 1, wherein a number of aromatic ring contained in the compound is one.

12. The magnetic recording medium according to claim 2, wherein a number of aromatic ring contained in the compound is one.

13. The magnetic recording medium according to claim 3, wherein a number of aromatic ring contained in the compound is one.

14. The magnetic recording medium according to claim 1, wherein the aromatic ring is a naphthalene ring or a biphenyl ring.

15. The magnetic recording medium according to claim 1, wherein a number of the substituent contained in the aromatic ring is one or two.

16. The magnetic recording medium according to claim 1, wherein the compound is dihydroxynaphthalene or biphenylcarboxylic acid.

17. The magnetic recording medium according to claim 2, wherein the compound is dihydroxynaphthalene or biphenylcarboxylic acid.

18. The magnetic recording medium according to claim 3, wherein the compound is dihydroxynaphthalene or biphenylcarboxylic acid.

19. The magnetic recording medium according to claim 1, wherein the ferromagnetic powder has a ferrite composition denoted by general formula:

AFe₁₂O₁₉, wherein A denotes at least one element selected from the group consisting of Ba, Sr, Pb, and Ca, and has a coercive force of equal to or lower than 230 kA/m.

20. The magnetic recording medium according to claim 1, wherein the magnetic layer comprises a granular substance that is different from the nonmagnetic inorganic particles.