-
公开(公告)号：US20230317337A1
公开(公告)日：2023-10-05
申请号：US18127722
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: [Problem] A hexagonal barium ferrite magnetic powder formed of fine particles, wherein the anisotropic magnetic field distribution of a magnetic recording medium can be made to fall within a range effective in both improving the recording density and improving the SNR is provided.
[Solution] A magnetic powder for a magnetic recording medium including magnetic particles in which Ba in hexagonal barium ferrite is partially substituted with Sr, wherein a Dx volume represented by the following formula (1) is 2,200 nm3 or less, an Sr/(Ba+Sr) molar ratio is 0.01 to 0.30, and an anisotropic magnetic field distribution is 1.00 or less.
Dx volume (nm3)=Dxc×Π×(Dxa/2)2 (1)
Here, 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, and n is a circular constant.-
2.发明申请公开(公告)号：US20210287713A1
公开(公告)日：2021-09-16
申请号：US17195029
申请日：2021-03-08
Applicant: FUJIFILM Corporation
Inventor： Norihito KASADA , Eiki Ozawa , Takashi Fujimoto
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 a vertical magnetization amount Φm per unit area of the magnetic recording medium measured after pressing the magnetic layer at a pressure of 70 atm is 8.0 G·μm to 80.0 G·μm.
-
公开(公告)号：US11894032B2
公开(公告)日：2024-02-06
申请号：US18191983
申请日：2023-03-29
Applicant: FUJIFILM Corporation
Inventor： Eiki Ozawa , Takashi Fujimoto
CPC classification number: G11B5/70642 , G11B5/702 , G11B5/712
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 switching field distribution SFD of the magnetic recording medium is 0.20 or more and 3.00 or less at a measurement temperature of 25° C., and an inclination of SFD obtained from SFD at a measurement temperature of 10° C., SFD at a measurement temperature of 25° C., and SFD at a measurement temperature of 40° C. is 0.003° C.−1 or more and 0.080° 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：US11508406B2
公开(公告)日：2022-11-22
申请号：US16260027
申请日：2019-01-28
Applicant: FUJIFILM CORPORATION
Inventor： Takashi Fujimoto
Abstract: Provided are a magnetic recording medium including: a non-magnetic support; and a magnetic layer which is provided on at least one surface of the non-magnetic support and includes particles of epsilon type iron oxide-based compound, and a binding agent, in which a contact angle measured regarding a surface of the magnetic layer is equal to or greater than 30.0° and smaller than 45.0° with respect to 1-bromonaphthalene and 80.0° to 95.0° with respect to water, a manufacturing method of particles of an epsilon iron oxide-based compound, and a manufacturing method of a magnetic recording medium.
-
公开(公告)号：US11367548B2
公开(公告)日：2022-06-21
申请号：US15825875
申请日：2017-11-29
Applicant: FUJIFILM Corporation
Inventor： Takashi Fujimoto
Abstract: Provided is an ε-iron oxide type ferromagnetic powder with a powder pH within a range of 4.8 to 6.8; and a method for manufacturing the ε-iron oxide type ferromagnetic powder and a composition containing at least the ε-iron oxide type ferromagnetic powder and a solvent.
-
Patent Agency Ranking
6.发明申请公开(公告)号：US20210287703A1
公开(公告)日：2021-09-16
申请号：US17195954
申请日：2021-03-09
Applicant: FUJIFILM Corporation
Inventor： Eiki OZAWA , Norihito Kasada , Takashi Fujimoto
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 transition temperature Tc of the magnetic recording medium measured after pressing the magnetic layer at a pressure of 70 atm is 80° C. to 240° C.
-
公开(公告)号：US12198841B2
公开(公告)日：2025-01-14
申请号：US17473603
申请日：2021-09-13
Applicant: FUJIFILM Corporation
Inventor： Takashi Fujimoto
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
-
8.发明授权公开(公告)号：US12131762B2
公开(公告)日：2024-10-29
申请号：US17955137
申请日：2022-09-28
Applicant: FUJIFILM Corporation
Inventor： Takashi Fujimoto , Eiki Ozawa
CPC classification number: G11B5/70642 , G11B5/714 , G11B5/7356
Abstract: A magnetic recording medium including a magnetic layer including a ferromagnetic powder. The ferromagnetic powder is an ε-iron oxide powder, and a ratio of Hr (45°) to Hr (0°) (Hr (45°)/Hr (0°)) is 0.50 or less. The Hr (0°) is a residual coercive force Hr obtained by applying a pulse magnetic field having a pulse width of 0.76 ms in an in-plane direction of the magnetic recording medium, and the Hr (45°) is a residual coercive force Hr obtained by setting an angle of the magnetic recording medium in the in-plane direction to 0°, setting an angle of the magnetic recording medium in a perpendicular direction to 90°, and making a pulse magnetic field having a pulse width of 0.76 ms be incident from a direction inclined by 45° toward the perpendicular direction from the in-plane direction and applying the pulse magnetic field to the magnetic recording medium.
-
公开(公告)号：US11670333B2
公开(公告)日：2023-06-06
申请号：US17199669
申请日：2021-03-12
Applicant: FUJIFILM Corporation
Inventor： Takashi Fujimoto , Norihito Kasada , Eiki Ozawa
CPC classification number: G11B5/70642
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：US11348711B2
公开(公告)日：2022-05-31
申请号：US16132662
申请日：2018-09-17
Applicant: FUJIFILM Corporation
Inventor： Kenji Naoi , Masashi Shirata , Takashi Fujimoto
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.
-
-
-
-
-
-
-
-
-
Search Results
27
records
(took 0.015 seconds)
