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

Patent metadata

Field	Value
Publication number	US-2022208221-A1
Application number	US-201916649461-A
Country	US
Kind code	A1
Filing date	Oct 1, 2019
Priority date	Aug 20, 2019
Publication date	Jun 30, 2022
Grant date	—

Abstract

A magnetic recording medium that can exhibit good traveling performance during use is provided. This magnetic recording medium is a tape-shaped magnetic recording medium, and includes a substrate, a base layer disposed on the substrate, and a magnetic layer disposed on the base layer. On the surface of the magnetic layer, recesses having a depth of 20% or more of the average thickness of the magnetic layer are formed at a ratio of 20 or more and 200 or less per 1600 μm2. On the surface of the magnetic layer, a logarithmic decay rate determined by a pendulum viscoelasticity test at a temperature of 10° C. or higher and 45° C. or lower is 0.025 or more and 0.040 or less. A difference between a maximum value of the logarithmic decay rate and a minimum value of the logarithmic decay rate is 0 or more and 0.020 or less. The squareness ratio in the perpendicular direction is 65% or more. The average thickness of the magnetic layer is 80 nm or less. The average thickness of the magnetic recording medium is 5.6 μm or less.

First claim

1 - 12 . (canceled)

13 : A tape-shaped magnetic recording medium comprising:
a substrate; a base layer disposed on the substrate; and a magnetic layer disposed on the base layer, wherein on a surface of the magnetic layer, recesses having a depth of 20% or more of the average thickness of the magnetic layer are formed at a ratio of 20 or more and 200 or less per 1600 μm 2 , on the surface of the magnetic layer, a logarithmic decay rate determined by a pendulum viscoelasticity test at a temperature of 10° C. or higher and 45° C. or lower is 0.025 or more and 0.035 or less, a difference between a maximum value of the logarithmic decay rate and a minimum value of the logarithmic decay rate is 0 or more and 0.020 or less, a squareness ratio of the magnetic recording medium in a perpendicular direction is 65% or more, the magnetic layer has an average thickness of 80 nm or less, and the magnetic recording medium has an average thickness of 5.6 μm or less.

14 : The magnetic recording medium according to claim 13 , wherein
the logarithmic decay rate is 0.025 or more and 0.030 or less.

15 : The magnetic recording medium according to claim 13 , wherein
on a surface of the magnetic layer, the recesses are formed at a ratio of 40 or more and 200 or less per 1600 μm 2 .

16 : The magnetic recording medium according to claim 13 , wherein
on a surface of the magnetic layer, the recesses are formed at a ratio of 80 or more and 180 or less per 1600 μm 2 .

17 : The magnetic recording medium according to claim 13 , wherein
the substrate includes a polyester or a polyether ether ketone (PEEK) as a main component.

18 : The magnetic recording medium according to claim 13 , wherein
the magnetic layer includes magnetic powder, and the magnetic powder includes hexagonal ferrite including at least one of barium (Ba) and strontium (Sr), ε iron oxide, or cobalt (Co)-containing spinel type ferrite.

19 : The magnetic recording medium according to claim 13 , wherein
the base layer and the magnetic layer each include a lubricant, and the lubricant includes at least one of a compound represented by the following general formula <1> and a compound represented by the following general formula <2>, and at least one of a compound represented by the following general formula <3> and a compound represented by the following general formula <4>:
CH 3 (CH 2 ) k COOH  <1>

where k is an integer selected from a range of 14 or more and 22 or less;
CH 3 (CH 2 ) n CH═CH(CH 2 ) m COOH  <2>

where a sum of n and m is an integer selected from a range of 12 or more and 20 or less, more preferably a range of 14 or more and 18 or less;
CH 3 (CH 2 ) p COO(CH 2 ) q CH 3   <3>

where p is an integer selected from a range of 14 or more and 22 or less, more preferably a range of 14 or more and 18 or less, and q is an integer selected from a range of 2 or more and 5 or less, more preferably a range of 2 or more and 4 or less; and
CH 3 (CH 2 ) p COO—(CH 2 ) q CH(CH 3 ) 2   <4>

where p is an integer selected from a range of 14 or more and 22 or less, and q is an integer selected from a range of 1 or more and 3 or less.

20 : The magnetic recording medium according to claim 19 , wherein
the base layer has a large number of holes, and the recesses of the magnetic layer are connected to the holes of the base layer.

21 : A magnetic recording/reproducing device comprising:
a feeding unit that can sequentially feed out a tape-shaped magnetic recording medium; a winding unit that can wind up the magnetic recording medium fed out from the feeding unit; and a magnetic head that can write information on the magnetic recording medium and can read out information from the magnetic recording medium while being in contact with the magnetic recording medium traveling from the feeding unit toward the winding unit, wherein the magnetic recording medium includes: a substrate; a base layer disposed on the substrate; and a magnetic layer disposed on the base layer, on a surface of the magnetic layer, recesses having a depth of 20% or more of the average thickness of the magnetic layer are formed at a ratio of 20 or more and 200 or less per 1600 μm 2 , on the surface of the magnetic layer, a logarithmic decay rate determined by a pendulum viscoelasticity test at a temperature of 10° C. or higher and 45° C. or lower is 0.025 or more and 0.035 or less, a difference between a maximum value of the logarithmic decay rate and a minimum value of the logarithmic decay rate is 0 or more and 0.020 or less, a squareness ratio of the magnetic recording medium in a perpendicular direction is 65% or more, the magnetic layer has an average thickness of 80 nm or less, and the magnetic recording medium has an average thickness of 5.6 μm or less.

22 : The magnetic recording/reproducing device according to claim 21 , wherein
a tension applied to the magnetic recording medium in a longitudinal direction thereof can be adjusted.

23 : A magnetic recording medium cartridge comprising:
a tape-shaped magnetic recording medium; and a casing that houses the magnetic recording medium, wherein the magnetic recording medium includes: a substrate; a base layer disposed on the substrate; and a magnetic layer disposed on the base layer, in which on a surface of the magnetic layer, recesses having a depth of 20% or more of the average thickness of the magnetic layer are formed at a ratio of 20 or more and 200 or less per 1600 μm 2 , on the surface of the magnetic layer, a logarithmic decay rate determined by a pendulum viscoelasticity test at a temperature of 10° C. or higher and 45° C. or lower is 0.025 or more and 0.035 or less, a difference between a maximum value of the logarithmic decay rate and a minimum value of the logarithmic decay rate is 0 or more and 0.020 or less, a squareness ratio of the magnetic recording medium in a perpendicular direction is 65% or more, the magnetic layer has an average thickness of 80 nm or less, and the magnetic recording medium has an average thickness of 5.6 μm or less.

Assignees

• Sony Corp

Inventors

• Yamaga Minoru

Classifications

• G11B5/17 Primary

  Construction or disposition of windings · CPC title

• G11B5/78

  Tape carriers · CPC title

• G11B5/584

  for track following on tapes · CPC title

• G11B5/00817

  on longitudinal tracks only, e.g. for serpentine format recording · CPC title

• G11B5/70678 Primary

  Ferrites · CPC title