公开(公告)号：US20230386515A1

公开(公告)日：2023-11-30

申请号：US18449307

申请日：2023-08-14

Applicant: FUJIFILM Corporation

Inventor： Takashi FUJIMOTO ,  Eiki Ozawa

IPC: G11B5/706 ,  G11B5/735 ,  G11B5/702 ,  G11B5/78

CPC classification number: G11B5/70621 ,  G11B5/7356 ,  G11B5/7021 ,  G11B5/78

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 is 1.0 or more and 6.5 or less; and a magnetic tape cartridge and a magnetic recording and reproducing device each including the magnetic recording medium.

公开(公告)号：US20190300380A1

公开(公告)日：2019-10-03

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：US20180358155A1

公开(公告)日：2018-12-13

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 ,  C01G49/08 ,  C08L101/06

CPC classification number: H01F1/0315 ,  C01G49/06 ,  C01G49/08 ,  C01P2002/32 ,  C01P2004/64 ,  C08L101/06 ,  C08L2207/53 ,  H01F1/0054

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：US20180358044A1

公开(公告)日：2018-12-13

申请号：US15996678

申请日：2018-06-04

Applicant: FUJIFILM Corporation

Inventor： Masashi SHIRATA ,  Takashi FUJIMOTO

IPC: G11B5/706

CPC classification number: G11B5/70642 ,  G11B5/70621

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), and a binding agent, at least on one surface of the non-magnetic support, in which an average area Sdc of a magnetic cluster in a DC demagnetization state measured with a magnetic force microscope satisfies a relationship of 500 nm2

公开(公告)号：US20230352224A1

公开(公告)日：2023-11-02

申请号：US18127707

申请日：2023-03-29

Applicant: DOWA ELECTRONICS MATERIALS CO., LTD. ,  FUJIFILM CORPORATION

Inventor： Akifumi ONODERA ,  Yasuto MIYAMOTO ,  Masaki KOSHIKO ,  Toshio TADA ,  Takashi FUJIMOTO

IPC: H01F1/34

CPC classification number: H01F1/348

Abstract: A magnetic powder for a magnetic recording medium includes magnetic particles in which Ba in hexagonal barium ferrite is partially substituted with Sr, wherein a Dx volume represented by Dx volume (nm3) = Dxc × π × (Dxa/2)2 is 2,200 nm3 or less, and an Sr/(Ba+Sr) molar ratio is 0.01 to 0.15. One that satisfies Ku ≥ 0.1 × [Sr/(Ba+Sr) molar ratio] + 0.13 is more preferred. For the formulas, Dxc is a crystallite diameter (nm) in a c-axis direction of a hexagonal ferrite crystal lattice, Dxa is a crystallite diameter (nm) in an a-axis direction of the same crystal lattice, π is a circular constant, and Ku is a magnetocrystalline anisotropy constant (MJ/m3). By providing the hexagonal ferrite magnetic powder formed of fine particles, an effect of improving the perpendicular squareness ratio SQ of a magnetic recording medium is large.

公开(公告)号：US20220005634A1

公开(公告)日：2022-01-06

申请号：US17473603

申请日：2021-09-13

Applicant: FUJIFILM Corporation

Inventor： Takashi FUJIMOTO

IPC: H01F1/11 ,  G11B5/65 ,  G11B5/706

Abstract: Magnetic powder includes: an epsilon-phase iron oxide-based compound selected from ε-Fe2O3 or a compound represented by Formula (1). The magnetic powder has an average particle diameter of 8 nm to 25 nm, a ratio of Hc to Hc′ of from 0.6 to 1.0, and Hc′ satisfying Expression (II). Hc′ represents a magnetic field at which a value of Expression (I) becomes zeroin a magnetic field-magnetization curve obtained by performing measurement at a maximum applied magnetic field of 359 kA/m, a temperature of 296 K, and a magnetic field sweeping speed of 1.994 kA/m/s. M represents magnetization and H represents applied magnetic field. Hc represents a magnetic field at which magnetization becomes zero in the magnetic field-magnetization curve. 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：US20210287709A1

公开(公告)日：2021-09-16

申请号：US17196376

申请日：2021-03-09

Applicant: FUJIFILM Corporation

Inventor： Takashi FUJIMOTO ,  Norihito KASADA ,  Eiki OZAWA

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

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 particle size of the ε-iron oxide powder in a longitudinal direction of the magnetic layer is more than 5.00% and 15.00% or less.

公开(公告)号：US20210287708A1

公开(公告)日：2021-09-16

申请号：US17196349

申请日：2021-03-09

Applicant: FUJIFILM Corporation

Inventor： Eiki OZAWA ,  Norihito KASADA ,  Takashi FUJIMOTO

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

Abstract: The magnetic recording medium includes a non-magnetic support, and a magnetic layer containing a ferromagnetic powder in which the ferromagnetic powder is an ε-iron oxide powder, and a vertical squareness ratio of the magnetic recording medium measured after pressing the magnetic layer at a pressure of 70 atm is 0.50 to 0.95.

公开(公告)号：US20210287705A1

公开(公告)日：2021-09-16

申请号：US17194968

申请日：2021-03-08

Applicant: FUJIFILM Corporation

Inventor： Norihito KASADA ,  Eiki OZAWA ,  Takashi FUJIMOTO

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

Abstract: The magnetic recording medium includes a non-magnetic support, and a magnetic layer containing a ferromagnetic powder in which the ferromagnetic powder is ε-iron oxide powder, and an anisotropic magnetic field Hk of the magnetic recording medium measured after pressing the magnetic layer at a pressure of 70 atm is 15,000 Oe to 40,000 Oe.

公开(公告)号：US20200279582A1

公开(公告)日：2020-09-03

申请号：US16802017

申请日：2020-02-26

Applicant: FUJIFILM Corporation

Inventor： Takashi FUJIMOTO

IPC: G11B5/73 ,  G11B5/84 ,  C01G49/06

Abstract: An object of the present invention is to provide a magnetic recording medium, which contains ε-type iron oxide particles and has excellent SNR, a manufacturing method of ε-type iron oxide particles, and a manufacturing method of a magnetic recording medium.The object 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.