Magnetic recording medium having characterized magnetic layer, and magnetic recording and reproducing apparatus

Patent metadata

Field	Value
Publication number	US-11270725-B2
Application number	US-202016802768-A
Country	US
Kind code	B2
Filing date	Feb 27, 2020
Priority date	Feb 28, 2019
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

Abstract

The magnetic recording medium includes: a non-magnetic support; and a magnetic layer including ferromagnetic powder, in which a difference (S 0.5 −S 13.5 ) between a spacing S 0.5 measured on a surface of the magnetic layer by optical interferometry after n-hexane cleaning under a pressure of 0.5 atm and a spacing S 13.5 measured on the surface of the magnetic layer by optical interferometry after n-hexane cleaning under a pressure of 13.5 atm is 9.0 nm or more.

First claim

What is claimed is:

1. A magnetic recording medium comprising:
a non-magnetic support; and
a magnetic layer including ferromagnetic powder,
wherein a difference S 0.5 −S 13.5 between a spacing S 0.5 measured on a surface of the magnetic layer by optical interferometry after n-hexane cleaning under a pressure of 0.5 atm and a spacing S 13.5 measured on the surface of the magnetic layer by optical interferometry after n-hexane cleaning under a pressure of 13.5 atm is 9.0 nm or more.

2. The magnetic recording medium according to claim 1 ,
wherein the difference is 9.0 nm or more and 30.0 nm or less.

3. The magnetic recording medium according to claim 1 ,
wherein the difference is 10.0 nm or more and 30.0 nm or less.

4. The magnetic recording medium according to claim 1 ,
wherein the magnetic layer includes an organic resin particle.

5. The magnetic recording medium according to claim 1 ,
wherein the magnetic layer includes a compound which contains an alkyl group having 5 or more carbon atoms.

6. The magnetic recording medium according to claim 5 ,
wherein the compound is an organic amine compound.

7. The magnetic recording medium according to claim 5 ,
wherein the compound is an organic phosphorus compound.

8. The magnetic recording medium according to claim 1 ,
wherein the magnetic layer includes one or more lubricants selected from the group consisting of a fatty acid, a fatty acid ester, and a fatty acid amide.

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

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

11. The magnetic recording medium according to claim 1 , which is a magnetic tape.

12. A magnetic recording and reproducing apparatus comprising:
the magnetic recording medium according to claim 1 ; and
a magnetic head.

13. The magnetic recording and reproducing apparatus according to claim 12 ,
wherein the difference is 9.0 nm or more and 30.0 nm or less.

14. The magnetic recording and reproducing apparatus according to claim 12 ,
wherein the difference is 10.0 nm or more and 30.0 nm or less.

15. The magnetic recording and reproducing apparatus according to claim 12 ,
wherein the magnetic layer includes an organic resin particle.

16. The magnetic recording and reproducing apparatus according to claim 12 ,
wherein the magnetic layer includes a compound which contains an alkyl group having 5 or more carbon atoms.

17. The magnetic recording and reproducing apparatus according to claim 16 ,
wherein the compound is an organic amine compound.

18. The magnetic recording and reproducing apparatus according to claim 16 ,
wherein the compound is an organic phosphorus compound.

19. The magnetic recording and reproducing apparatus according to claim 12 ,
wherein the magnetic layer includes one or more lubricants selected from the group consisting of a fatty acid, a fatty acid ester, and a fatty acid amide.

Assignees

• Fujifilm Corp

Inventors

• Sano Naoki
• Ozawa Eiki
• Kasada Norihito
• Kurokawa Takuto

Classifications

• G11B5/7356

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

• G11B5/7085

  non-magnetic abrasive particles · CPC title

• G11B5/70678 Primary

  Ferrites · CPC title

• G11B5/71

  characterised by the lubricant · CPC title

• G11B5/70615 Primary

  containing Fe metal or alloys (G11B5/70621 takes precedence) · CPC title