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

Patent metadata

Field	Value
Publication number	US-12014759-B2
Application number	US-202318192386-A
Country	US
Kind code	B2
Filing date	Mar 29, 2023
Priority date	Sep 30, 2020
Publication date	Jun 18, 2024
Grant date	Jun 18, 2024

Abstract

Provided are: a magnetic recording medium including a non-magnetic support and a magnetic layer containing a ferromagnetic powder, in which the ferromagnetic powder is an ε-iron oxide powder, a vertical squareness ratio SQ of the magnetic recording medium is 0.50 or more and 0.95 or less at a measurement temperature of 25° C., and an inclination of SQ obtained from SQ at a measurement temperature of 10° C., SQ at a measurement temperature of 25° C., and SQ at a measurement temperature of 40° C. is −0.0050° C.−1 or more and −0.0003° C.−1 or less; a magnetic tape cartridge including the magnetic recording medium which is a magnetic tape; and a magnetic recording and reproducing device including the magnetic recording medium.

First claim

What is claimed is:

1. A magnetic recording medium comprising:
a non-magnetic support; and
a magnetic layer containing a ferromagnetic powder,
wherein the ferromagnetic powder is an ε-iron oxide powder,
a vertical squareness ratio SQ of the magnetic recording medium is 0.50 or more and 0.95 or less at a measurement temperature of 25° C., and
an inclination of SQ obtained from SQ at a measurement temperature of 10° C., SQ at a measurement temperature of 25° C., and SQ at a measurement temperature of 40° C. is −0.0050° C. −1 or more and −0.0003° C. −1 or less.

2. The magnetic recording medium according to claim 1 ,
wherein the inclination of SQ is −0.0030° C. −1 or more and −0.0005° C. −1 or less.

3. The magnetic recording medium according to claim 1 ,
wherein the SQ at the measurement temperature of 25° C. is 0.60 or more and 0.90 or less.

4. The magnetic recording medium according to claim 2 ,
wherein the SQ at the measurement temperature of 25° C. is 0.60 or more and 0.90 or less.

5. The magnetic recording medium according to claim 1 ,
wherein the ε-iron oxide powder contains a cobalt element.

6. The magnetic recording medium according to claim 5 ,
wherein the ε-iron oxide powder further contains an element selected from the group consisting of a gallium element and an aluminum element.

7. The magnetic recording medium according to claim 5 ,
wherein the ε-iron oxide powder further contains an element selected from the group consisting of a titanium element and a tin element.

8. The magnetic recording medium according to claim 6 ,
wherein the ε-iron oxide powder further contains an element selected from the group consisting of a titanium element and a tin element.

9. The magnetic recording medium according to claim 2 ,
wherein the ε-iron oxide powder contains a cobalt element.

10. The magnetic recording medium according to claim 9 ,
wherein the ε-iron oxide powder further contains an element selected from the group consisting of a gallium element and an aluminum element, and further contains an element selected from the group consisting of a titanium element and a tin element.

11. The magnetic recording medium according to claim 3 ,
wherein the ε-iron oxide powder contains a cobalt element.

12. The magnetic recording medium according to claim 11 ,
wherein the ε-iron oxide powder further contains an element selected from the group consisting of a gallium element and an aluminum element, and further contains an element selected from the group consisting of a titanium element and a tin element.

13. The magnetic recording medium according to claim 4 ,
wherein the ε-iron oxide powder contains a cobalt element.

14. The magnetic recording medium according to claim 13 ,
wherein the ε-iron oxide powder further contains an element selected from the group consisting of a gallium element and an aluminum element, and further contains an element selected from the group consisting of a titanium element and a tin element.

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

16. The magnetic recording medium according to claim 1 , further comprising:
a back coating layer containing 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.

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

18. A magnetic tape cartridge comprising:
the magnetic tape according to claim 17 .

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

Assignees

• Fujifilm Corp

Inventors

• Fujimoto Takashi
• Ozawa Eiki

Classifications

• G11B5/78

  Tape carriers · CPC title

• G11B5/733

  characterised by the addition of non-magnetic particles {(base layers having a non-magnetic layer under a soft magnetic layer G11B5/736; magnetic recording media substrates G11B5/739)} · CPC title

• G11B5/714

  characterised by the dimension of the magnetic particles · CPC title

• G11B5/7356

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

• G11B5/852

  Orientation in a magnetic field (G11B5/845 takes precedence) · CPC title