Magnetic recording medium

Patent metadata

Field	Value
Publication number	US-2020342902-A1
Application number	US-201916684234-A
Country	US
Kind code	A1
Filing date	Nov 14, 2019
Priority date	Apr 26, 2019
Publication date	Oct 29, 2020
Grant date	—

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

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 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 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 dimensional change amount Δw is 700 ppm/N≤Δw.

4 . The magnetic recording medium according to claim 1 , wherein the dimensional change amount Δw is 750 ppm/N≤Δw.

5 . The magnetic recording medium according to claim 1 , wherein the dimensional change amount Δw is 800 ppm/N≤Δw.

6 . 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.

7 . 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.

8 . 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.

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

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

11 . The magnetic recording medium according to claim 10 , wherein the elastic limit value σ MD does not depend on a speed V at a time of measuring an elastic limit.

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

13 . 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.

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

15 . The magnetic recording medium according to claim 14 , wherein an average thickness tm of the magnetic layer is 9 nm≤t m ≤90 nm.

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

17 . The magnetic recording medium according to claim 16 , wherein an average thickness tm of the magnetic layer is 35 nm≤t m ≤120 nm.

18 . The magnetic recording medium according to claim 16 , wherein the magnetic powder includes ε iron oxide magnetic powder, barium ferrite magnetic powder, cobalt ferrite magnetic powder, or strontium ferrite magnetic powder.

19 . 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.

20 . 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.

21 . 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.

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

23 . 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 .

24 . The magnetic recording medium according to claim 23 , wherein the elastic limit value σ MD does not depend on a speed V at a time of measuring an elastic limit.

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

26 . 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.

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

28 . The magnetic recording medium according to claim 27 , wherein an average thickness t m of the magnetic layer is 9 nm≤t m ≤90 nm.

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

30 . The magnetic recording medium according to claim 29 , wherein an average thickness t m of the magnetic layer is 35 nm≤t m ≤120 nm.

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

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

33 . The magnetic recording medium according to claim 1 , wherein the dimensional change amount Δw is 660 ppm/N≤Δw≤800 ppm/N.

34 . The magnetic recording medium according to claim 1 , wherein σPES≤21 nm.

Assignees

• Sony Corp

Inventors

• Enomoto Taikei
• Terakawa Masaru
• Yamaga Minoru

Classifications

• G11B5/7379

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

• G11B5/7266

  comprising a lubricant over the inorganic carbon coating · CPC title

• G11B5/70

  on a base layer · CPC title

• G11B5/851

  Coating a support with a magnetic layer by sputtering · CPC title

• G11B5/73929

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