Magnetic recording medium having characterized back coating layer and magnetic recording and reproducing apparatus

Patent metadata

Field	Value
Publication number	US-11270728-B2
Application number	US-202017022446-A
Country	US
Kind code	B2
Filing date	Sep 16, 2020
Priority date	Sep 19, 2019
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

Abstract

The magnetic recording medium includes a non-magnetic support; a magnetic layer that includes ferromagnetic powder on one surface side of the non-magnetic support; and a back coating layer that includes non-magnetic powder on the other surface side of the non-magnetic support, in which a difference between a spacing measured on a surface of the back coating layer by optical interferometry under a pressure of 0.5 atm after n-hexane cleaning and a spacing measured on the surface of the back coating layer by optical interferometry under a pressure of 13.5 atm after n-hexane cleaning is 3 nm or less.

First claim

What is claimed is:

1. A magnetic recording medium comprising:
a non-magnetic support;
a magnetic layer that includes ferromagnetic powder on one surface side of the non-magnetic support; and
a back coating layer that includes non-magnetic powder on the other surface side of the non-magnetic support,
wherein a difference S 0.5 −S 13.5 between a spacing S 0.5 measured on a surface of the back coating layer by optical interferometry under a pressure of 0.5 atm after n-hexane cleaning and a spacing S 13.5 measured on the surface of the back coating layer by optical interferometry under a pressure of 13.5 atm after n-hexane cleaning is 3 nm or less.

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

3. The magnetic recording medium according to claim 1 ,
wherein the spacing S 0.5 is 20 nm or more and 90 nm or less.

4. The magnetic recording medium according to claim 1 ,
wherein the spacing S 13.5 is 20 nm or more and 90 nm or less.

5. The magnetic recording medium according to claim 1 ,
wherein the back coating layer includes an inorganic oxide-based particle.

6. The magnetic recording medium according to claim 5 ,
wherein the inorganic oxide-based particle is a composite particle of an inorganic oxide and a polymer.

7. The magnetic recording medium according to claim 1 ,
wherein the back coating layer has a thickness of 0.5 μm or less.

8. 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.

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

10. A magnetic recording and reproducing apparatus comprising:
a magnetic recording medium; and
a magnetic head,
wherein the magnetic recording medium is a magnetic recording medium comprising:
a non-magnetic support;
a magnetic layer that includes ferromagnetic powder on one surface side of the non-magnetic support; and
a back coating layer that includes non-magnetic powder on the other surface side of the non-magnetic support,
wherein a difference S 0.5 −S 13.5 between a spacing S 0.5 measured on a surface of the back coating layer by optical interferometry under a pressure of 0.5 atm after n-hexane cleaning and a spacing S 13.5 measured on the surface of the back coating layer by optical interferometry under a pressure of 13.5 atm after n-hexane cleaning is 3 nm or less.

11. The magnetic recording and reproducing apparatus according to claim 10 ,
wherein the difference is 1 nm or more and 3 nm or less.

12. The magnetic recording and reproducing apparatus according to claim 10 ,
wherein the spacing S 0.5 is 20 nm or more and 90 nm or less.

13. The magnetic recording and reproducing apparatus according to claim 10 ,
wherein the spacing S 13.5 is 20 nm or more and 90 nm or less.

14. The magnetic recording and reproducing apparatus according to claim 10 ,
wherein the back coating layer includes an inorganic oxide-based particle.

15. The magnetic recording and reproducing apparatus according to claim 14 ,
wherein the inorganic oxide-based particle is a composite particle of an inorganic oxide and a polymer.

16. The magnetic recording and reproducing apparatus according to claim 10 ,
wherein the back coating layer has a thickness of 0.5 μm or less.

17. The magnetic recording and reproducing apparatus according to claim 10 ,
wherein the magnetic recording medium further comprises a non-magnetic layer including non-magnetic powder between the non-magnetic support and the magnetic layer.

18. The magnetic recording and reproducing apparatus according to claim 10 ,
wherein the magnetic recording medium is a magnetic tape.

Assignees

• Fujifilm Corp

Inventors

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

Classifications

• G11B5/78 Primary

  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

• G11B5/73929

  comprising naphthalene ring compounds, e.g. polyethylene naphthalate substrates · CPC title

• G11B5/7356 Primary

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