Magnetic recording medium, magnetic tape cartridge, and magnetic recording and reproducing device

Patent metadata

Field	Value
Publication number	US-12057152-B2
Application number	US-202117186470-A
Country	US
Kind code	B2
Filing date	Feb 26, 2021
Priority date	Feb 28, 2020
Publication date	Aug 6, 2024
Grant date	Aug 6, 2024

Abstract

The magnetic recording medium includes a non-magnetic support, and a magnetic layer including a ferromagnetic powder. An anisotropic magnetic field Hk is 12 kOe or more, a center line average roughness Ra of the surface of the magnetic recording medium on the magnetic layer side is 1.2 nm or less, and a ratio θr of a contact angle θ2 with respect to 1-bromonaphthalene, measured on a surface on the magnetic layer side after a 1,1,1,2,2,3,4,5,5,5-decafluoropentane immersion, to a contact angle θ1 with respect to 1-bromonaphthalene, measured on the surface on the magnetic layer side before the 1,1,1,2,2,3,4,5,5,5-decafluoropentane immersion is 0.95 or less.

First claim

What is claimed is:

1. A magnetic recording medium comprising:
a non-magnetic support; and
a magnetic layer including a ferromagnetic powder,
wherein an anisotropic magnetic field Hk is 12 kOe or more,
a center line average roughness Ra of a surface of the magnetic recording medium on a magnetic layer side is 1.2 nm or less,
a ratio θr of a contact angle θ2 with respect to 1-bromonaphthalene, measured on a surface on the magnetic layer side after a 1,1,1,2,2,3,4,5,5,5-decafluoropentane immersion of the magnetic recording medium, to a contact angle θ1 with respect to 1-bromonaphthalene, measured on the surface on the magnetic layer side before the 1,1,1,2,2,3,4,5,5,5-decafluoropentane immersion of the magnetic recording medium is 0.95 or less,
the magnetic recording medium further comprises a fluorine-containing compound in a portion of the magnetic layer side on the non-magnetic support,
and the fluorine-containing compound is one or more compounds selected from the group consisting of:
(ii) a fluorine-containing compound represented by Formula 1,

in Formula 1, n is 0 or 1, and when n is 0, Rf represents a perfluoroalkyl group and R represents an unsubstituted alkyl group having one or two carbon atoms, and
when n is 1, Rf represents a fluorine-containing hydrocarbon group, L represents an alkylene group, and R represents a fluorine-containing hydrocarbon group; and
(iii) a fluorine-containing compound represented by Formula 1,

in Formula 1, Rf represents a fluorine-containing hydrocarbon group, L represents a divalent linking group including one or more alkylene groups and one or more ester groups, R | represents a hydrogen atom, an unsubstituted alkyl group, or a fluorine-containing hydrocarbon group, and n is 1.

2. The magnetic recording medium according to claim 1 ,
wherein, in clause (ii) when n is 1 and in clause (iii), in Formula 1, Rf represents a perfluoroalkyl group.

3. The magnetic recording medium according to claim 1 , wherein the fluorine-containing compound is a compound of clause (ii) in claim 1 .

4. The magnetic recording medium according to claim 1 ,
wherein the ratio θr is 0.50 to 0.95.

5. The magnetic recording medium according to any claim 1 ,
wherein the Ra is 0.1 nm to 1.2 nm.

6. The magnetic recording medium according to claim 1 ,
wherein the Hk is 12 kOe to 50 kOe.

7. The magnetic recording medium according to claim 1 ,
wherein the ferromagnetic powder is a hexagonal ferrite powder.

8. The magnetic recording medium according to claim 7 ,
wherein the hexagonal ferrite powder is a hexagonal strontium ferrite powder.

9. The magnetic recording medium according to claim 7 ,
wherein the hexagonal ferrite powder is a hexagonal barium ferrite powder.

10. The magnetic recording medium according to claim 1 ,
wherein the ferromagnetic powder is an ε-iron oxide powder.

11. The magnetic recording medium according to claim 1 , further comprising a non-magnetic layer including a non-magnetic powder between the non-magnetic support and the magnetic layer.

12. The magnetic recording medium according to claim 1 , further comprising a back coating layer including a non-magnetic powder on a surface side of the non-magnetic support opposite to a surface side on which the magnetic layer is provided.

13. The magnetic recording medium according to claim 1 ,
wherein the magnetic recording medium is a magnetic tape.

14. A magnetic tape cartridge comprising the magnetic tape according to claim 13 .

15. A magnetic recording and reproducing device comprising the magnetic recording medium according to claim 1 .

16. The magnetic recording medium according to claim 1 , wherein the fluorine-containing compound is a compound of clause (iii) in claim 1 .

17. The magnetic recording medium according to claim 3 ,
wherein, in Formula 1, n in clause (ii) is 1.

Assignees

• Fujifilm Corp

Inventors

• Oyanagi Noriko
• Kikuchi Wataru

Classifications

• G11B5/7358

  specially adapted for achieving a specific property, e.g. average roughness [Ra] · CPC title

• G11B5/70678

  Ferrites · CPC title

• G11B5/00813

  magnetic tapes · CPC title

• G11B5/7356

  comprising non-magnetic particles in the back layer, e.g. particles of TiO2, ZnO or SiO2 · CPC title

• G11B5/73935 Primary

  characterised by roughness or surface features, e.g. by added particles · CPC title