Magnetic recording medium

Patent metadata

Field	Value
Publication number	US-10923148-B2
Application number	US-201916684234-A
Country	US
Kind code	B2
Filing date	Nov 14, 2019
Priority date	Apr 26, 2019
Publication date	Feb 16, 2021
Grant date	Feb 16, 2021

Abstract

There is provided a magnetic recording medium which has a layer structure including a magnetic layer and a base layer, and of which an average thickness tT is tT≤5.6 μm, a dimensional change amount Δw in a width direction with respect to a change in tension in a longitudinal direction is 660 ppm/N≤Δw, a servo pattern is recorded on the magnetic layer, a standard deviation σPES of a position error signal (PES) value obtained from a servo signal in which the servo pattern is reproduced is σPES≤25 nm, and a maximum value μ1M of a friction coefficient μ1 between a surface on a side of the magnetic layer and an LTO3 head in a case where measurement of the friction coefficient μ1 is performed 250 times is 0.04≤μ1M≤0.5.

First claim

The invention claimed is:

1. A magnetic recording medium
which has a layer structure including a magnetic layer and a base layer, and
of which an average thickness t T is t T ≤5.6 μm,
a dimensional change amount Δw in a width direction with respect to a change in tension in a longitudinal direction is 707 ppm/N≤Δw≤800 ppm/N,
a servo pattern is recorded on the magnetic layer,
a standard deviation σPES of a position error signal (PES) value obtained from a servo signal in which the servo pattern is reproduced is 17≤σPES≤23, and
a maximum value μ 1M of a friction coefficient μ 1 between a surface on a side of the magnetic layer and an LTO3 head in a case where measurement of the friction coefficient μ 1 is performed 250 times is 0.04≤μ 1M ≤0.5.

2. The magnetic recording medium according to claim 1 , wherein a squareness ratio of the magnetic recording medium in a vertical direction is 65% or more.

3. The magnetic recording medium according to claim 1 ,
wherein the layer structure includes a back layer on a side of the base layer opposite to the side of the magnetic layer, and
a surface roughness R ab of the back layer is 3.0 nm≤R ab ≤7.5 nm.

4. The magnetic recording medium according to claim 1 ,
wherein the layer structure includes a back layer on a side of the base layer opposite to the side of the magnetic layer, and
a friction coefficient μ between a surface on the side of the magnetic layer and a surface on a side of the back layer is 0.20≤μ≤0.80.

5. The magnetic recording medium according to claim 1 , wherein a thermal expansion coefficient α is 5.5 ppm/° C.≤α≤9 ppm/° C., and a humidity expansion coefficient β is β≤5.5 ppm/% RH.

6. The magnetic recording medium according to claim 1 , wherein a Poisson's ratio ρ is 0.25≤ρ.

7. The magnetic recording medium according to claim 1 , wherein an elastic limit value σMD in the longitudinal direction is 0.7 N≤σMD.

8. The magnetic recording medium according to claim 7 , wherein the elastic limit value σ MD does not depend on a speed V at a time of measuring an elastic limit.

9. The magnetic recording medium according to claim 1 , wherein the magnetic layer is vertically aligned.

10. The magnetic recording medium according to claim 1 , wherein the layer structure includes a back layer on a side of the base layer opposite to the side of the magnetic layer, and an average thickness t b of the back layer is t b ≤0.6 μm.

11. The magnetic recording medium according to claim 1 , wherein the magnetic layer is a sputtered layer.

12. The magnetic recording medium according to claim 11 , wherein an average thickness t m of the magnetic layer is 9 nm≤t m ≤90 nm.

13. The magnetic recording medium according to claim 1 , wherein the magnetic layer contains a magnetic powder.

14. The magnetic recording medium according to claim 13 , wherein an average thickness t m of the magnetic layer is 35 nm≤t m ≤120 nm.

15. The magnetic recording medium according to claim 13 , wherein the magnetic powder includes c iron oxide magnetic powder, barium ferrite magnetic powder, cobalt ferrite magnetic powder, or strontium ferrite magnetic powder.

16. The magnetic recording medium according to claim 2 ,
wherein the layer structure includes a back layer on a side of the base layer opposite to the side of the magnetic layer, and
a surface roughness R ab of the back layer is 3.0 nm≤R ab ≤7.5 nm.

17. The magnetic recording medium according to claim 2 ,
wherein the layer structure includes a back layer on a side of the base layer opposite to the side of the magnetic layer, and
a friction coefficient μ between a surface on the side of the magnetic layer and a surface on a side of the back layer is 0.20≤μ≤0.80.

18. The magnetic recording medium according to claim 2 , wherein a thermal expansion coefficient α is 5.5 ppm/° C.≤α<9 ppm/° C., and a humidity expansion coefficient β is β≤5.5 ppm/% RH.

19. The magnetic recording medium according to claim 2 , wherein a Poisson's ratio ρ is 0.25≤ρ.

20. The magnetic recording medium according to claim 2 , wherein an elastic limit value σ MD in the longitudinal direction is 0.7 N≤σ MD .

21. The magnetic recording medium according to claim 20 , wherein the elastic limit value σ MD does not depend on a speed V at a time of measuring an elastic limit.

22. The magnetic recording medium according to claim 2 , wherein the magnetic layer is vertically aligned.

23. The magnetic recording medium according to claim 2 ,
wherein the layer structure includes a back layer on a side of the base layer opposite to the side of the magnetic layer, and
an average thickness t b of the back layer is t b ≤0.6 μm.

24. The magnetic recording medium according to claim 2 , wherein the magnetic layer is a sputtered layer.

25. The magnetic recording medium according to claim 24 , wherein an average thickness t m of the magnetic layer is 9 nm≤t m ≤90 nm.

26. The magnetic recording medium according to claim 2 , wherein the magnetic layer contains a magnetic powder.

27. The magnetic recording medium according to claim 26 , wherein an average thickness t m of the magnetic layer is 35 nm≤t m ≤120 nm.

28. The magnetic recording medium according to claim 1 , further comprising a barrier layer provided between the base layer and a back layer, wherein the barrier layer includes a metal or metal oxide.

29. The magnetic recording medium according to claim 2 , wherein the squareness ratio ranges from 80% or more.

Assignees

• Sony Corp

Inventors

• Enomoto Taikei
• Terakawa Masaru
• Yamaga Minoru

Classifications

• G11B5/78

  Tape carriers · CPC title

• G11B5/7379

  Seed layer, e.g. at least one non-magnetic layer is specifically adapted as a seed or seeding layer · CPC title

• G11B5/716

  characterised by two or more magnetic layers · CPC title

• G11B5/7266

  comprising a lubricant over the inorganic carbon coating · CPC title

• G11B5/584 Primary

  for track following on tapes · CPC title