公开(公告)号：US20230260544A1

公开(公告)日：2023-08-17

申请号：US18188639

申请日：2023-03-23

Applicant: FUJIFILM Corporation

Inventor： Takashi FUJIMOTO ,  Eiki Ozawa

IPC: G11B5/706 ,  G11B5/78

CPC classification number: G11B5/70689 ,  G11B5/78

Abstract: Provided are: a magnetic recording medium including a non-magnetic support and a magnetic layer containing a ferromagnetic powder, in which the ferromagnetic powder is an ε-iron oxide powder, a vertical magnetization amount Φm per unit area of the magnetic recording medium is 5 G·μm or more and 100 G·μm or less at a measurement temperature of 25° C., and an inclination of Φm obtained from Φm at a measurement temperature of 10° C., Φm at a measurement temperature of 25° C., and Φm at a measurement temperature of 40° C. is −0.20 G·μm/° C. or more and −0.03 G·μm/° C. or less; a magnetic tape cartridge including the magnetic recording medium which is a magnetic tape; and a magnetic recording and reproducing device including the magnetic recording medium.

公开(公告)号：US20230260543A1

公开(公告)日：2023-08-17

申请号：US18192386

申请日：2023-03-29

Applicant: FUJIFILM Corporation

Inventor： Takashi FUJIMOTO ,  Eiki OZAWA

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

CPC classification number: G11B5/70678 ,  G11B5/733 ,  G11B5/78

Abstract: Provided are: a magnetic recording medium including a non-magnetic support and a magnetic layer containing a ferromagnetic powder, in which the ferromagnetic powder is an ε-iron oxide powder, a vertical squareness ratio SQ of the magnetic recording medium is 0.50 or more and 0.95 or less at a measurement temperature of 25° C., and an inclination of SQ obtained from SQ at a measurement temperature of 10° C., SQ at a measurement temperature of 25° C., and SQ at a measurement temperature of 40° C. is −0.0050° C.−1 or more and −0.0003° C.−1 or less; a magnetic tape cartridge including the magnetic recording medium which is a magnetic tape; and a magnetic recording and reproducing device including the magnetic recording medium.

公开(公告)号：US20210287711A1

公开(公告)日：2021-09-16

申请号：US17199669

申请日：2021-03-12

Applicant: FUJIFILM Corporation

Inventor： Takashi FUJIMOTO ,  Norihito KASADA ,  Eiki OZAWA

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 particle size of the ε-iron oxide powder in a longitudinal direction of the magnetic layer is 0.50% or more and 5.00% or less.

公开(公告)号：US20210043228A1

公开(公告)日：2021-02-11

申请号：US16986894

申请日：2020-08-06

Applicant: FUJIFILM Corporation

Inventor： Kenji NAOI ,  Takashi FUJIMOTO

IPC: G11B5/706 ,  G11B5/714 ,  G11B5/008 ,  G11B5/735 ,  G11B5/584

Abstract: The magnetic recording medium includes a non-magnetic support; and a magnetic layer including a ferromagnetic powder, in which an anisotropic magnetic field Hk is more than 5.0 kOe and less than 7.5 kOe, an anisotropic magnetic field distribution is more than 0.75 and less than 1.20, the magnetic layer has a servo pattern, the ferromagnetic powder is a hexagonal strontium ferrite powder, and an average particle size of the hexagonal strontium ferrite powder is 9 nm to 20 nm.

公开(公告)号：US20190096551A1

公开(公告)日：2019-03-28

申请号：US16132662

申请日：2018-09-17

Applicant: FUJIFILM Corporation

Inventor： Kenji NAOI ,  Masashi SHIRATA ,  Takashi FUJIMOTO

IPC: H01F1/11 ,  C01G49/06 ,  C01G49/08

Abstract: The invention provides a core-shell particle which can provide, by being calcinated, epsilon type iron oxide-based compound particles that have a small coefficient of variation of primary particle diameter and show excellent SNR and running durability when employed in a magnetic recording medium as well as applications thereof. The core-shell particle includes: a core including at least one iron oxide selected from Fe2O3 or Fe3O4, or iron oxyhydroxide; and a shell that coats the core, the shell including a polycondensate of a metal alkoxide and a metal element other than iron, as well as applications thereof.

公开(公告)号：US20180358156A1

公开(公告)日：2018-12-13

申请号：US15993797

申请日：2018-05-31

Applicant: FUJIFILM Corporation

Inventor： Takashi FUJIMOTO

IPC: H01F1/11 ,  G11B5/65

CPC classification number: H01F1/11 ,  G11B5/653

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：US20180358045A1

公开(公告)日：2018-12-13

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

CPC classification number: G11B5/712 ,  C01G49/0045 ,  C01G49/0063 ,  C01G49/0072 ,  C01P2004/64 ,  C01P2006/42 ,  G11B5/70631 ,  G11B5/70678 ,  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：US20180358043A1

公开(公告)日：2018-12-13

申请号：US15986882

申请日：2018-05-23

Applicant: FUJIFILM Corporation

Inventor： Kenji NAOI ,  Takashi FUJIMOTO ,  Masashi SHIRATA

IPC: G11B5/706

CPC classification number: G11B5/70615

Abstract: A magnetic recording medium includes: a non-magnetic support; and a magnetic layer including a binding agent and a ferromagnetic powder including at least one epsilon-type iron oxide compound selected from the group consisting of ε-Fe2O3 and compound represented by Formula (1) (A represents at least one metal element other than Fe, and a satisfies 0

公开(公告)号：US20180147626A1

公开(公告)日：2018-05-31

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

CPC classification number: B22F1/0059 ,  B22F2999/00 ,  G11B5/70615 ,  G11B5/70642 ,  H01F1/06 ,  H01F1/065

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.