公开(公告)号：US20210287704A1

公开(公告)日：2021-09-16

申请号：US17197211

申请日：2021-03-10

Applicant: FUJIFILM Corporation

Inventor： Eiki Ozawa ,  Norihito Kasada ,  Takashi Fujimoto

IPC: G11B5/706

Abstract: The magnetic tape includes a non-magnetic support and a magnetic layer including ferromagnetic powder, in which the ferromagnetic powder is ε-iron oxide powder, and a coefficient of variation of an anisotropic magnetic field Hk in a longitudinal direction of the magnetic tape is 2.0% or more and 10.0% or less.

公开(公告)号：US10971182B2

公开(公告)日：2021-04-06

申请号：US15992396

申请日：2018-05-30

Applicant: FUJIFILM Corporation

Inventor： Takashi Fujimoto

IPC: G11B5/712 ,  C01G49/00 ,  G11B5/706 ,  H01F1/11

Abstract: Magnetic powder includes: at least one epsilon-phase iron oxide-based compound selected from the group consisting of ε-Fe2O3 and a compound represented by Formula (1); and a surface treatment layer including a silane compound on at least a part of a surface. The magnetic powder has an average particle diameter of 8 nm to 20 nm. The content ratio of carbon atoms of the silane compound included in the surface treatment layer to iron atoms of the at least one epsilon-phase iron oxide-based compound selected from the group consisting of ε-Fe2O3 and the compound represented by Formula (1) is 0.05% to 0.5% in terms of the number of atoms. A manufacturing method thereof and applications thereof are also provided. In Formula (1), A represents at least one metal element other than Fe and a represents a number that satisfies a relationship of 0

公开(公告)号：US10703643B2

公开(公告)日：2020-07-07

申请号：US15857861

申请日：2017-12-29

Applicant: FUJIFILM Corporation

Inventor： Takao Mizoguchi ,  Takashi Fujimoto

IPC: C01G49/00 ,  G11B5/706 ,  H01F1/11 ,  C01G49/06

Abstract: The ε-iron oxide type ferromagnetic powder contains Fe, a metal element selected from the group consisting of monovalent metal elements and divalent metal elements at a content rate within a range of 0.2 to 16.5 at % with respect to 100.0 at % of Fe, and a pentavalent metal element at a content rate within a range of 0.2 to 7.5 at % with respect to 100.0 at % of Fe, in which a total content rate of metal elements other than Fe is within a range of 2.5 to 24.0 at % with respect to 100.0 at % of Fe.

公开(公告)号：US20230402060A1

公开(公告)日：2023-12-14

申请号：US18455273

申请日：2023-08-24

Applicant: FUJIFILM Corporation

Inventor： Eiki OZAWA ,  Takashi Fujimoto

IPC: G11B5/66

CPC classification number: G11B5/676

Abstract: Provided are a magnetic recording medium including a non-magnetic support, and a magnetic layer including a ferromagnetic powder. The ferromagnetic powder is an ε-iron oxide powder, and an intensity ratio (Int1/Int2) of diffraction intensities obtained by an X-ray diffraction analysis of the magnetic layer using an In-Plane method after the magnetic layer is pressed at a pressure of 70 atm is 1.0 or more and 6.5 or less, a magnetic tape cartridge and a magnetic recording and reproducing device each including the magnetic recording medium.

公开(公告)号：US11562839B2

公开(公告)日：2023-01-24

申请号：US15974797

申请日：2018-05-09

Applicant: FUJIFILM Corporation

Inventor： Kenji Naoi ,  Takashi Fujimoto ,  Masashi Shirata

IPC: H01F1/03 ,  H01F1/00 ,  C01G49/06 ,  C08L101/06 ,  C01G49/08 ,  H01F1/11 ,  G11B5/70 ,  C01G49/00

Abstract: A core-shell particle includes: a core including an iron oxyhydroxide compound represented by Formula A3a3Fe1−a3OOH (in which A3 represents at least one metal element other than Fe, and a3 satisfies 0

公开(公告)号：US11459244B2

公开(公告)日：2022-10-04

申请号：US16251097

申请日：2019-01-18

Applicant: FUJIFILM CORPORATION

Inventor： Kenji Naoi ,  Takashi Fujimoto ,  Masashi Shirata

IPC: C01G49/02 ,  H01F1/11 ,  G11B5/706

Abstract: Disclosed are a particle of a 13-iron oxyhydroxide-based compound represented by Formula (1), in which an average equivalent circle diameter of primary particles is 5 nm to 30 nm, and a coefficient of variation of equivalent circle diameters of the primary particles is 10% to 30% [In Formula (1), A represents at least one kind of metal element other than Fe, and a represents a number that satisfies a relationship of 0≤a

公开(公告)号：US11440810B2

公开(公告)日：2022-09-13

申请号：US16548307

申请日：2019-08-22

Applicant: FUJIFILM Corporation

Inventor： Takashi Fujimoto

IPC: H01F1/11 ,  H01F1/00 ,  C01G49/06 ,  G11B5/852

Abstract: Provided is a powder of a β-iron oxyhydroxide-based compound that is a group of particles of a β-iron oxyhydroxide-based compound represented by Formula (1) below; in which a surface of the particles of the β-iron oxyhydroxide-based compound is modified with a surface modifier; in which, in a case where the powder is dispersed in water to be made into a sol, a zeta potential of the powder is equal to or higher than +5 mV at pH 10; and β-AaFe1-aOOH  (1) in which, in Formula (1), A represents at least one metallic element other than Fe, and a represents a number that satisfies a relationship of 0≤a

公开(公告)号：US11200913B2

公开(公告)日：2021-12-14

申请号：US16802017

申请日：2020-02-26

Applicant: FUJIFILM Corporation

Inventor： Takashi Fujimoto

IPC: G11B5/706 ,  G11B5/714 ,  G11B5/73 ,  G11B5/84 ,  C01G49/06 ,  B82Y25/00 ,  B82Y40/00

Abstract: Embodiments include a magnetic recording medium containing ε-type iron oxide particles and having excellent SNR, a manufacturing method of ε-type iron oxide particles, and a manufacturing method of a magnetic recording medium. High SNR is achieved by a magnetic recording medium containing ε-type iron oxide particles, in which a coefficient of variation of an aspect ratio of the ε-type iron oxide particles is equal to or smaller than 18%, and a squareness ratio of the magnetic recording medium measured in a longitudinal direction of the magnetic recording medium is higher than 0.3 and equal to or lower than 0.5. The object is also achieved by the application of the magnetic recording medium.

公开(公告)号：US11100949B2

公开(公告)日：2021-08-24

申请号：US15996622

申请日：2018-06-04

Applicant: FUJIFILM Corporation

Inventor： Masashi Shirata ,  Takashi Fujimoto

IPC: G11B5/78 ,  G11B5/714 ,  G11B5/706 ,  G11B5/708

Abstract: Provided is a magnetic recording medium including: a non-magnetic support; and a magnetic layer including particles of at least one kind of epsilon type iron oxide-based compound selected from the group consisting of ε-Fe2O3 and a compound represented by Formula (1), an abrasive, and a binding agent, at least on one surface of the non-magnetic support, in which an average equivalent circle diameter of the particles of the epsilon type iron oxide-based compound is 7 nm to 18 nm, an average equivalent circle diameter of the abrasive in a plan view of the magnetic layer is 20 nm to 1,000 nm, and a coefficient of variation of the equivalent circle diameter of the abrasive is 30% to 60%. In Formula (1), A represents at least one kind of metal element other than Fe and a satisfies a relationship of 0

公开(公告)号：US11090716B2

公开(公告)日：2021-08-17

申请号：US15825469

申请日：2017-11-29

Applicant: FUJIFILM Corporation

Inventor： Masashi Shirata ,  Takashi Fujimoto

IPC: B22F1/00 ,  G11B5/706 ,  H01F1/06

Abstract: Provided is an ε-iron oxide type ferromagnetic powder with a ratio Hc173K/Hc296K between a coercive force Hc173K measured at a temperature of 173 K and a coercive force Hc296K measured at a temperature of 296 K is higher than 1.00 and less than 2.00, and a magnetic recording medium containing the ε-iron oxide type ferromagnetic powder in a magnetic layer.