公开(公告)号：US10714139B2

公开(公告)日：2020-07-14

申请号：US16037564

申请日：2018-07-17

Applicant: FUJIFILM Corporation

Inventor： Takuto Kurokawa ,  Norihito Kasada ,  Toshio Tada ,  Eiki Ozawa

IPC: G11B5/70 ,  G11B5/706 ,  G11B5/708

Abstract: The magnetic recording medium includes a non-magnetic support and a magnetic layer containing ferromagnetic powder and a binder, in which the ferromagnetic powder is ferromagnetic hexagonal ferrite powder, the magnetic layer contains an abrasive, an intensity ratio of a peak intensity of a diffraction peak of (110) plane of a crystal structure of the hexagonal ferrite, determined by performing X-ray diffraction analysis on the magnetic layer by using an In-Plane method, to a peak intensity of a diffraction peak of (114) plane of the crystal structure is equal to or higher than 0.5 and equal to or lower than 4.0, a squareness ratio of the magnetic recording medium in a vertical direction is equal to or higher than 0.65 and equal to or lower than 1.00, and a contact angle with 1-bromonaphthalene measured within a surface of the magnetic layer is in a range of 50.0° to 55.0°.

公开(公告)号：US10403318B2

公开(公告)日：2019-09-03

申请号：US15625428

申请日：2017-06-16

Applicant: FUJIFILM Corporation

Inventor： Takuto Kurokawa ,  Eiki Ozawa ,  Norihito Kasada

IPC: G11B5/735 ,  G11B5/725 ,  G11B5/712 ,  G11B5/78

Abstract: A magnetic tape in which a thickness of a back coating layer is equal to or smaller than 0.20 μm. A C—H derived C concentration calculated from a C—H peak area ratio of C1s spectra obtained by X-ray photoelectron spectroscopic analysis performed on the surface of the back coating layer at a photoelectron take-off angle of 10 degrees is equal to or greater than 35 atom %. The full widths at half maximum of spacing distribution measured by optical interferometry regarding the surface of the back coating layer before and after performing a vacuum heating with respect to the magnetic tape are respectively greater than 0 nm and equal to or smaller than 10.0 nm. The difference between the spacing measured after performing the vacuum heating and a spacing measured before performing the vacuum heating is greater than 0 nm and equal to or smaller than 8.0 nm.

公开(公告)号：US11508408B2

公开(公告)日：2022-11-22

申请号：US17160535

申请日：2021-01-28

Applicant: FUJIFILM Corporation

Inventor： Takuto Kurokawa ,  Naoki Sano ,  Norihito Kasada

IPC: G11B5/706 ,  G11B5/58 ,  G11B5/714 ,  G11B5/735 ,  G11B5/008 ,  G11B5/708

Abstract: The magnetic tape in which a difference (S0.1−S1.6) between a spacing S0.1 and a spacing S1.6 obtained after n-hexane cleaning on a surface of the magnetic layer is equal to or less than 32 nm. The S0.1 is a value obtained as a spacing under a pressing force of 0.1 atm from a relational expression between a pressure and a spacing obtained by performing a spacing measurement on the surface of the magnetic layer by an optical interference method under a pressing force of each of a plurality of different pressures after the n-hexane cleaning, and S1.6 is a spacing measured on the surface of the magnetic layer by the optical interference method under the pressing force of 1.6 atm after the n-hexane cleaning.

公开(公告)号：US11302357B2

公开(公告)日：2022-04-12

申请号：US17025092

申请日：2020-09-18

Applicant: FUJIFILM Corporation

Inventor： Naoki Sano ,  Takuto Kurokawa ,  Eiki Ozawa ,  Norihito Kasada ,  Megumi Nakano

IPC: G11B5/78 ,  G11B5/733 ,  G11B5/735 ,  G11B5/706

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 12 nm or more.

公开(公告)号：US20190027180A1

公开(公告)日：2019-01-24

申请号：US16038884

申请日：2018-07-18

Applicant: FUJIFILM Corporation

Inventor： Norihito Kasada ,  Toshio Tada ,  Eiki Ozawa ,  Takuto Kurokawa

IPC: G11B5/735 ,  G11B5/733 ,  G11B5/716 ,  G11B5/706

Abstract: The magnetic tape includes a magnetic layer including ferromagnetic powder, non-magnetic powder, and a binding agent and a back coating layer including non-magnetic powder and a binding agent, in which the ferromagnetic powder is ferromagnetic hexagonal ferrite powder, an Ra measured regarding a surface of the magnetic layer is equal to or smaller than 1.8 nm, an intensity ratio of a peak intensity of a diffraction peak of a (110) plane with respect to a peak intensity of a diffraction peak of a (114) plane of a hexagonal ferrite crystal structure obtained by an X-ray diffraction analysis of the magnetic layer by using an In-Plane method is 0.5 to 4.0, a vertical squareness ratio of the magnetic tape is 0.65 to 1.00, and a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding a surface of the hack coating layer is equal to or smaller than 0.060.

公开(公告)号：US20220254373A1

公开(公告)日：2022-08-11

申请号：US17666851

申请日：2022-02-08

Applicant: FUJIFILM Corporation

Inventor： Takuto Kurokawa ,  So Matsuyama ,  Norihito Kasada

IPC: G11B5/73 ,  G11B5/78

Abstract: The magnetic tape includes a non-magnetic support, and a magnetic layer including a ferromagnetic powder. A rate of change in friction coefficient on an LTO8 head measured on a surface of the magnetic layer before and after storage of the magnetic tape is 0.7 or more.

公开(公告)号：US11373680B2

公开(公告)日：2022-06-28

申请号：US16832284

申请日：2020-03-27

Applicant: FUJIFILM Corporation

Inventor： Takahiro Iwamoto ,  Hidemasa Hosoda ,  Norihito Kasada ,  Takuto Kurokawa

IPC: G11B5/706 ,  G11B5/735 ,  G11B5/008 ,  G11B5/708 ,  G11B5/712 ,  G11B5/714

Abstract: Provided are a magnetic tape comprising a magnetic layer containing a ferromagnetic powder and a binding agent on a non-magnetic support, in which the magnetic layer contains an oxide abrasive, an average particle diameter of the oxide abrasive obtained from a secondary ion image acquired by irradiating a surface of the magnetic layer with a focused ion beam is 0.04 μm to 0.08 μm, and an absolute value ΔN of a difference between a refractive index Nxy measured with respect to an in-plane direction of the magnetic layer and a refractive index Nz measured with respect to a thickness direction of the magnetic layer is 0.25 to 0.40, and a magnetic recording and reproducing device including the magnetic tape.

公开(公告)号：US11270728B2

公开(公告)日：2022-03-08

申请号：US17022446

申请日：2020-09-16

Applicant: FUJIFILM Corporation

Inventor： Takuto Kurokawa ,  Naoki Sano ,  Norihito Kasada ,  Eiki Ozawa ,  Megumi Nakano

IPC: G11B5/735 ,  G11B5/733 ,  G11B5/73 ,  G11B5/78

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.

公开(公告)号：US11211087B2

公开(公告)日：2021-12-28

申请号：US16368044

申请日：2019-03-28

Applicant: FUJIFILM Corporation

Inventor： Eiki Ozawa ,  Takuto Kurokawa

IPC: G11B5/735 ,  G11B5/008 ,  G11B5/584 ,  G11B5/712

Abstract: The magnetic tape includes a non-magnetic support; a magnetic layer including a ferromagnetic powder and a binding agent on one surface of the non-magnetic support; and a back coating layer including a non-magnetic powder and a binding agent on the other surface of the non-magnetic support, in which a center line average surface roughness Ra measured regarding a surface of the back coating layer is equal to or smaller than 7.0 nm, and a difference between a spacing Safter measured by optical interferometry regarding the surface of the back coating layer after methyl ethyl ketone cleaning and a spacing Sbefore measured by optical interferometry regarding the surface of the back coating layer before methyl ethyl ketone cleaning is greater than 0 nm and equal to or smaller than 30.0 nm.

公开(公告)号：US10896692B2

公开(公告)日：2021-01-19

申请号：US15443094

申请日：2017-02-27

Applicant: FUJIFILM Corporation

Inventor： Takuto Kurokawa ,  Norihito Kasada ,  Masahito Oyanagi

IPC: G11B5/73 ,  G11B5/735 ,  G11B5/733 ,  G11B5/78

Abstract: The magnetic tape has a magnetic layer containing ferromagnetic powder and binder on one surface of a nonmagnetic support and has a backcoat layer containing nonmagnetic powder and binder on the other surface thereof, wherein the thickness of the backcoat layer is less than or equal to 0.20 μm, and the contact angle for 1-bromonaphthalene that is measured on the surface of the backcoat layer falls within a range of 10.0° to 30.0°.