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公开(公告)号：US11170812B2
公开(公告)日：2021-11-09
申请号：US16555571
申请日：2019-08-29
Applicant: FUJIFILM Corporation
Inventor： Kenji Naoi , Masashi Shirata , Wataru Kikuchi
Abstract: A magnetic recording medium, a composition for it, and a magnetic recording and reproducing apparatus are provided. The medium includes a non-magnetic support; and a magnetic layer including a ferromagnetic powder and a binding agent on the support. The magnetic layer also includes a compound including one or more partial structures selected from partial structures represented by Formulas 1 and 2, and a polyalkyleneimine chain. The composition for the recording medium includes a ferromagnetic powder and the compound. In Formulas 1 and 2, L1 and L2 each independently represents a divalent linking group, Z1 and Z2 each independently represents a monovalent group represented by —OM or a monovalent group represented by —O−A+, M represents a hydrogen atom or an alkali metal atom, and A+ represents an ammonium cation.
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2.发明授权公开(公告)号：US10734144B2
公开(公告)日：2020-08-04
申请号：US15627636
申请日：2017-06-20
Applicant: FUJIFILM Corporation
Inventor： Masashi Shirata , Yoichi Hosoya
Abstract: A production method for metal oxide particles includes: obtaining precursor particles of a metal oxide by performing a synthesis reaction of the precursor particles in the presence of an organic compound; and converting the obtained precursor particles into metal oxide particles by heating an aqueous solution containing the precursor particles to 300° C. or higher and pressurizing the aqueous solution at a pressure of 20 MPa or higher.
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公开(公告)号：US11315595B2
公开(公告)日：2022-04-26
申请号：US17035077
申请日：2020-09-28
Applicant: THE UNIVERSITY OF TOKYO , OSAKA UNIVERSITY , FUJIFILM Corporation
Inventor： Shin-ichi Ohkoshi , Makoto Nakajima , Masashi Shirata , Hiroaki Doshita
IPC: G11B11/105 , G11B5/706 , G11B5/012
Abstract: The present invention provides a recording method and a recording device in which information can be easily recorded even in a magnetic recording medium using epsilon iron oxide particles having a high coercive force as a magnetic recording material. A recording device of the invention applies an external magnetic field H0 that inclines magnetization of epsilon iron oxide particles to a particle dispersion element containing epsilon iron oxide particles, and irradiates the particle dispersion element with light that excites the magnetization. Accordingly, the recording device is capable of inverting magnetization that is not capable of being inverted only by the external magnetic field, in accordance with a synergetic effect between the inclination of the magnetization and the light excitation of the magnetization.
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公开(公告)号：US20220093126A1
公开(公告)日：2022-03-24
申请号：US17542561
申请日：2021-12-06
Applicant: FUJIFILM Corporation
Inventor： Kenji Naoi , Masashi Shirata
Abstract: A hexagonal strontium ferrite powder, in which an average particle size is 10.0 to 25.0 nm, a content of one or more kinds of atom selected from the group consisting of a gallium atom, a scandium atom, an indium atom, and an antimony atom is 1.0 to 15.0 atom % with respect to 100.0 atom % of an iron atom, and a coercivity Hc is greater than 2,000 Oe and smaller than 4.000 Oe. A magnetic recording medium including: a non-magnetic support; and a magnetic layer including a ferromagnetic powder and a binding agent on the non-magnetic support, in which the ferromagnetic powder is the hexagonal strontium ferrite powder. A magnetic recording and reproducing apparatus including this magnetic recording medium.
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5.发明申请公开(公告)号：US20200335247A1
公开(公告)日：2020-10-22
申请号：US16904932
申请日：2020-06-18
Applicant: FUJIFILM Corporation
Inventor： Yoichi HOSOYA , Masashi Shirata , Tatsuo Mikami
Abstract: To provide magnetoplumbite-type hexagonal ferrite particles represented by Formula (1) and having a single crystal phase, and the application. In Formula (1), A represents at least one metal element selected from the group consisting of Sr, Ba, Ca, and Pb, and x satisfies 1.5≤x≤8.0. AFe(12-x)AlxO19 Formula (1)
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Patent Agency Ranking
公开(公告)号：US20190295582A1
公开(公告)日：2019-09-26
申请号：US16357748
申请日：2019-03-19
Applicant: Fujifilm Corporation
Inventor： Kenji Naoi , Masashi Shirata
Abstract: Provided is a ferromagnetic powder for magnetic recording, in which an activation volume is 800 nm3 to 1,500 nm3, an average plate ratio is 2.0 to 5.0, a rare earth atom content is 0.5 atom % to 5.0 atom %, and an aluminum atom content is greater than 10.0 atom % and equal to or smaller than 20.0 atom %, with respect to 100 atom % of iron atom, and the ferromagnetic powder is a plate-shaped hexagonal strontium ferrite powder having a rare earth atom surface layer portion uneven distribution and an aluminum atom surface layer portion uneven distribution, and a magnetic recording medium including this ferromagnetic powder for magnetic recording in a magnetic layer.
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7.发明授权Magnetic powder for magnetic recording, magnetic recording medium, and method of manufacturing magnetic powder for magnetic recording 有权用于磁记录的磁粉，磁记录介质，以及制造用于磁记录的磁粉的方法公开(公告)号：US09589585B2
公开(公告)日：2017-03-07
申请号：US14584602
申请日：2014-12-29
Applicant: FUJIFILM CORPORATION
Inventor： Masashi Shirata
CPC classification number: G11B5/70678 , C01G49/0036 , C01P2002/50 , C01P2004/64 , C01P2006/42 , H01F1/11 , Y10T428/2982
Abstract: An aspect of the present invention relates to magnetic powder, which is magnetoplumbite hexagonal strontium ferrite magnetic powder comprising 0.05 atomic percent to 3 atomic percent of Ca per 100 atomic percent of Fe, but comprising no rare earth elements or transition metal elements other than Fe, the average particle size of which ranges from 10 nm to 25 nm, and which is magnetic powder for magnetic recording.
Abstract translation: 本发明的一个方面涉及磁性粉末，它是每100原子％Fe含0.05原子％-3原子％Ca的磁铅石六方锶铁氧体磁粉，不包含除Fe以外的稀土元素或过渡金属元素， 其平均粒径为10nm〜25nm，为磁记录用磁粉。
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公开(公告)号：US12160984B2
公开(公告)日：2024-12-03
申请号：US17518825
申请日：2021-11-04
Applicant: FUJIFILM Corporation
Inventor： Masashi Shirata , Hirokazu Hashimoto
Abstract: There is provided a radio wave absorber including a powder of a hexagonal ferrite; and a binder, in which the radio wave absorber has a squareness ratio in a range of 0.40 to 0.60.
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公开(公告)号：US11574652B2
公开(公告)日：2023-02-07
申请号：US17401326
申请日：2021-08-13
Applicant: The University of Tokyo , OSAKA UNIVERSITY , FUJIFILM Corporation
Inventor： Shin-ichi Ohkoshi , Marie Yoshikiyo , Kenta Imoto , Kosuke Nakagawa , Asuka Namai , Hiroko Tokoro , Makoto Nakajima , Masashi Shirata , Kenji Naoi
IPC: G11B5/00 , G11B11/105 , G11B5/706
Abstract: Provided is a recording device. The recording device includes: an external magnetic field application unit that is configured to apply an external magnetic field to a magnetic recording medium; a light irradiation unit that is configured to irradiate light; and a light focusing unit that is configured to focus the light from the light irradiation unit by resonating the light to generate an enhanced magnetic field in which a magnetic field of the light is enhanced, in which magnetization of the magnetic recording medium is inverted by applying the external magnetic field and the enhanced magnetic field to the magnetic recording medium.
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公开(公告)号：US11488627B2
公开(公告)日：2022-11-01
申请号：US16357748
申请日：2019-03-19
Applicant: FUJIFILM Corporation
Inventor： Kenji Naoi , Masashi Shirata
Abstract: Provided is a ferromagnetic powder for magnetic recording, in which an activation volume is 800 nm3 to 1,500 nm3, an average plate ratio is 2.0 to 5.0, a rare earth atom content is 0.5 atom % to 5.0 atom %, and an aluminum atom content is greater than 10.0 atom % and equal to or smaller than 20.0 atom %, with respect to 100 atom % of iron atom, and the ferromagnetic powder is a plate-shaped hexagonal strontium ferrite powder having a rare earth atom surface layer portion uneven distribution and an aluminum atom surface layer portion uneven distribution, and a magnetic recording medium including this ferromagnetic powder for magnetic recording in a magnetic layer.
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