Patents by Inventor Toshio Tada

Toshio Tada has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 11894171
    Abstract: Provided is an Al-containing hexagonal ferrite magnetic powder which produces an excellent durability-improving effect on a magnetic recording medium, wherein uniform pulverization of the magnetic powder can be easily achieved by dispersion treatment in preparation of a magnetic coating material even in cases where the magnetic powder has a small primary particle size or has a composition which is likely to produce hard secondary particles. The magnetic powder for a magnetic recording medium is an Al-containing hexagonal ferrite magnetic powder having an Al/Fe molar ratio of 0.030 to 0.200, and has a particle size distribution in which the volume ratio of particles having a particle size of 30 ?m or more as measured by a laser diffraction particle size distribution analyzer with a dispersion pressure of 100 kPa is 5.0% or less, and an activation volume Vact of 1800 nm3 or less.
    Type: Grant
    Filed: November 14, 2019
    Date of Patent: February 6, 2024
    Assignees: DOWA ELECTRONICS MATERIALS CO., LTD., FUJIFILM CORPORATION
    Inventors: Hirohisa Omoto, Shuji Kaneda, Satoshi Shiki, Hiroyuki Suzuki, Toshio Tada
  • Publication number: 20230352224
    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 × ? × (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, ? 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.
    Type: Application
    Filed: March 29, 2023
    Publication date: November 2, 2023
    Inventors: Akifumi ONODERA, Yasuto MIYAMOTO, Masaki KOSHIKO, Toshio TADA, Takashi FUJIMOTO
  • Publication number: 20230317337
    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×?×(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.
    Type: Application
    Filed: March 29, 2023
    Publication date: October 5, 2023
    Inventors: Akifumi ONODERA, Yasuto Miyamoto, Masaki Koshiko, Toshio Tada, Takashi Fujimoto
  • Publication number: 20230306995
    Abstract: The magnetic recording medium is used in a magnetic recording and reproducing device in which a reproduction bit size S is 40,000 nm2 or less, and a numerical value of a residual magnetic flux density Brvertical, which is expressed in a unit G, in a vertical direction of the magnetic recording medium is X or more. The X is a value calculated as X = -0.01S + 1550.
    Type: Application
    Filed: March 21, 2023
    Publication date: September 28, 2023
    Applicant: FUJIFILM Corporation
    Inventors: Toshio TADA, Hiroyuki Suzuki, Megumi Nakano
  • Patent number: 11404190
    Abstract: Provided is a hexagonal ferrite magnetic powder for a magnetic recording medium, containing hexagonal ferrite magnetic particles having aluminum hydroxide adhered on the surface thereof, the hexagonal ferrite magnetic powder having an Al/Fe molar ratio of 0.030 to 0.200, a Co/Fe molar ratio of 0.002 to 0.030, and a Nb/Fe molar ratio of 0.005 to 0.050, and having an Fe site valence AFe of 3.015 to 3.040 as calculated by AFe=(3+2×[Co/Fe]+5×[Nb/Fe])/(1+[Co/Fe]+[Nb/Fe]) wherein [Co/Fe] represents the Co/Fe molar ratio and [Nb/Fe] represents the Nb/Fe molar ratio, and preferably having an activation volume Vact of 1400 to 1800 nm3. This magnetic powder simultaneously achieves an increase in magnetic characteristics including SNR of a magnetic recording medium and a further increase in durability thereof.
    Type: Grant
    Filed: December 4, 2019
    Date of Patent: August 2, 2022
    Assignees: DOWA ELECTRONICS MATERIALS CO., LTD., FUJIFILM CORPORATION
    Inventors: Hirohisa Omoto, Shuji Kaneda, Hiroyuki Suzuki, Toshio Tada
  • Patent number: 11125652
    Abstract: A test method of accurately evaluating wear resistance performance of a rubber material when used as a tread rubber of a tire, comprises the steps of: preparing a test piece of the rubber material having a ground contact surface extending in a circumferential direction; abrading the ground contact surface by rolling the test piece on a running surface of a wear testing machine at a slip ratio of not more than 3.5%; and evaluating the wear resistance performance of the test piece by comparing the amount of wear of the test piece with a predetermined threshold value.
    Type: Grant
    Filed: June 7, 2019
    Date of Patent: September 21, 2021
    Assignee: SUMITOMO RUBBER INDUSTRIES, LTD.
    Inventors: Shinya Nakano, Toshio Tada
  • Patent number: 10910009
    Abstract: The magnetic tape has a magnetic layer containing ferromagnetic powder and binder on a nonmagnetic support, wherein the centerline average surface roughness Ra as measured on the surface on the magnetic layer side of the magnetic tape is less than or equal to 1.8 nm, and the logarithmic decrement as determined by a pendulum viscoelasticity test on the surface on the magnetic layer side of the magnetic tape is less than or equal to 0.050.
    Type: Grant
    Filed: June 19, 2018
    Date of Patent: February 2, 2021
    Assignee: FUJIFILM Corporation
    Inventors: Masahito Oyanagi, Norihito Kasada, Toshio Tada, Takuro Sugiyama
  • Patent number: 10854232
    Abstract: The magnetic recording medium includes a magnetic layer which contains ferromagnetic hexagonal ferrite powder and a binder, in which the magnetic layer contains an abrasive and a fatty acid ester, Int (110)/Int (114) of a crystal structure of the hexagonal ferrite, determined by performing XRD analysis on the magnetic layer by using an In-Plane method, is equal to or higher than 0.5 and equal to or lower than 4.0, a squareness ratio of the magnetic recording medium in a vertical direction is equal to or higher than 0.65 and equal to or lower than 1.00, FWHMbefore and FWHMafter is greater than 0 nm and equal to or smaller than 7.0 nm, and a difference between spacings measured within a surface of the magnetic layer by an optical interference method before and after the heating in a vacuum is greater than 0 nm and equal to or smaller than 8.0 nm.
    Type: Grant
    Filed: July 17, 2018
    Date of Patent: December 1, 2020
    Assignee: FUJIFILM Corporation
    Inventors: Eiki Ozawa, Norihito Kasada, Toshio Tada, Takuto Kurokawa
  • Patent number: 10854227
    Abstract: The magnetic recording medium includes a non-magnetic support and a magnetic layer which contains ferromagnetic powder and a binder, in which the ferromagnetic powder is ferromagnetic hexagonal ferrite powder, the magnetic layer contains an abrasive, Int (110)/Int (114) of a crystal structure of the hexagonal ferrite, determined by performing X-ray diffraction analysis on the magnetic layer by using an In-Plane method, to a peak intensity of a diffraction peak of (114) plane of the crystal structure is equal to or higher than 0.5 and equal to or lower than 4.0, a squareness ratio of the magnetic recording medium in a vertical direction is equal to or higher than 0.65 and equal to or lower than 1.00, and a logarithmic decrement obtained by performing a pendulum viscoelasticity test on a surface of the magnetic layer is equal to or lower than 0.050.
    Type: Grant
    Filed: July 18, 2018
    Date of Patent: December 1, 2020
    Assignee: FUJIFILM Corporation
    Inventors: Norihito Kasada, Toshio Tada, Eiki Ozawa, Takuto Kurokawa
  • Patent number: 10854228
    Abstract: The magnetic tape includes a magnetic layer including ferromagnetic powder, non-magnetic powder, and a binding agent and a back coating layer including non-magnetic powder and a binding agent, in which the ferromagnetic powder is ferromagnetic hexagonal ferrite powder, a center line average surface roughness measured regarding a surface of the magnetic layer is equal to or smaller than 1.8 nm, an intensity ratio of a peak intensity of a diffraction peak of a (110) plane with respect to a peak intensity of a diffraction peak of a (114) plane of a hexagonal ferrite crystal structure obtained by an X-ray diffraction analysis of the magnetic layer by using an In-Plane method is 0.5 to 4.0, a vertical squareness ratio of the magnetic tape is 0.65 to 1.00, and a contact angle with respect to 1-bromonaphthalene measured regarding a surface of the back coating layer is 15.0° to 30.0°.
    Type: Grant
    Filed: July 18, 2018
    Date of Patent: December 1, 2020
    Assignee: FUJIFILM Corporation
    Inventors: Takuto Kurokawa, Norihito Kasada, Toshio Tada, Eiki Ozawa
  • Patent number: 10854230
    Abstract: The magnetic tape includes a magnetic layer including ferromagnetic powder, non-magnetic powder, and a binding agent and a back coating layer including non-magnetic powder and a binding agent, in which the ferromagnetic powder is ferromagnetic hexagonal ferrite powder, an Ra measured regarding a surface of the magnetic layer is equal to or smaller than 1.8 nm, an intensity ratio of a peak intensity of a diffraction peak of a (110) plane with respect to a peak intensity of a diffraction peak of a (114) plane of a hexagonal ferrite crystal structure obtained by an X-ray diffraction analysis of the magnetic layer by using an In-Plane method is 0.5 to 4.0, a vertical squareness ratio of the magnetic tape is 0.65 to 1.00, and a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding a surface of the back coating layer is equal to or smaller than 0.060.
    Type: Grant
    Filed: July 18, 2018
    Date of Patent: December 1, 2020
    Assignee: FUJIFILM Corporation
    Inventors: Norihito Kasada, Toshio Tada, Eiki Ozawa, Takuto Kurokawa
  • Patent number: 10854229
    Abstract: Provided is a magnetic tape in which an Ra measured regarding a surface of a magnetic layer is equal to or smaller than 1.8 nm, Int(110)/Int(114) of a hexagonal ferrite crystal structure obtained by an XRD analysis of the magnetic layer by using an In-Plane method is 0.5 to 4.0, a vertical squareness ratio of the magnetic tape is 0.65 to 1.00, full widths at half maximum of spacing distribution measured by optical interferometry regarding the surface of the back coating layer before and after performing a vacuum heating with respect to the magnetic tape are greater than 0 nm and equal to or smaller than 10.0 nm, and a difference between the spacings measured by optical interferometry regarding the surface of the back coating layer before and after performing the vacuum heating is greater than 0 nm and equal to or smaller than 8.0 nm.
    Type: Grant
    Filed: July 18, 2018
    Date of Patent: December 1, 2020
    Assignee: FUJIFILM Corporation
    Inventors: Eiki Ozawa, Toshio Tada, Norihito Kasada, Takuto Kurokawa
  • Patent number: 10839850
    Abstract: Provided is a magnetic tape in which an Ra measured regarding a surface of a magnetic layer is equal to or smaller than 1.8 nm, Int(110)/Int(114) of a hexagonal ferrite crystal structure obtained by an X-ray diffraction analysis of the magnetic layer by using an In-Plane method is 0.5 to 4.0, a vertical squareness ratio of the magnetic tape is 0.65 to 1.00, the back coating layer includes one or more kinds of component selected from the group consisting of fatty acid and fatty acid amide, and a C—H derived C concentration calculated from a C—H peak area ratio of C1s spectra obtained by X-ray photoelectron spectroscopic analysis performed on the surface of the back coating layer at a photoelectron take-off angle of 10 degrees is equal to or greater than 35 atom %.
    Type: Grant
    Filed: July 17, 2018
    Date of Patent: November 17, 2020
    Assignee: FUJIFILM Corporation
    Inventors: Toshio Tada, Norihito Kasada, Eiki Ozawa, Takuto Kurokawa
  • Patent number: 10839849
    Abstract: The magnetic recording medium includes a non-magnetic support and a magnetic layer, wherein the magnetic layer contains ferromagnetic hexagonal ferrite powder and an abrasive, Int (110)/Int (114) of a crystal structure of the hexagonal ferrite determined by performing XRD analysis on the magnetic layer by using an In-Plane method is equal to or higher than 0.5 and equal to or lower than 4.0, a squareness ratio of the magnetic recording medium in a vertical direction is equal to or higher than 0.65 and equal to or lower than 1.00, one or more kinds of components selected from the group consisting of a fatty acid and a fatty acid amide is contained in a magnetic layer side portion on the support, and a C—H-derived C concentration obtained by ESCA within a surface of the magnetic layer at a photoelectron take-off angle of 10° is equal to or higher than 45 at %.
    Type: Grant
    Filed: July 18, 2018
    Date of Patent: November 17, 2020
    Assignee: FUJIFILM Corporation
    Inventors: Toshio Tada, Norihito Kasada, Eiki Ozawa, Takuto Kurokawa
  • Patent number: 10714139
    Abstract: The magnetic recording medium includes a non-magnetic support and a magnetic layer containing ferromagnetic powder and a binder, in which the ferromagnetic powder is ferromagnetic hexagonal ferrite powder, the magnetic layer contains an abrasive, an intensity ratio of a peak intensity of a diffraction peak of (110) plane of a crystal structure of the hexagonal ferrite, determined by performing X-ray diffraction analysis on the magnetic layer by using an In-Plane method, to a peak intensity of a diffraction peak of (114) plane of the crystal structure is equal to or higher than 0.5 and equal to or lower than 4.0, a squareness ratio of the magnetic recording medium in a vertical direction is equal to or higher than 0.65 and equal to or lower than 1.00, and a contact angle with 1-bromonaphthalene measured within a surface of the magnetic layer is in a range of 50.0° to 55.0°.
    Type: Grant
    Filed: July 17, 2018
    Date of Patent: July 14, 2020
    Assignee: FUJIFILM Corporation
    Inventors: Takuto Kurokawa, Norihito Kasada, Toshio Tada, Eiki Ozawa
  • Patent number: 10692522
    Abstract: The magnetic recording medium has a non-magnetic support and a magnetic layer which is provided on the support and contains ferromagnetic powder and a binder, in which the ferromagnetic powder is ferromagnetic hexagonal ferrite powder, the magnetic layer contains an abrasive, an intensity ratio (Int (110)/Int (114)) of a peak intensity Int (110) of a diffraction peak of (110) plane of a crystal structure of the hexagonal ferrite, determined by performing X-ray diffraction analysis on the magnetic layer by using an In-Plane method, to a peak intensity Int (114) of a diffraction peak of (114) plane of the crystal structure is equal to or higher than 0.5 and equal to or lower than 4.0, and a squareness ratio in a vertical direction is equal to or higher than 0.65 and equal to or lower than 1.00. The present invention also provides a method for manufacturing the magnetic recording medium.
    Type: Grant
    Filed: September 15, 2017
    Date of Patent: June 23, 2020
    Assignee: FUJIFILM Corporation
    Inventors: Toshio Tada, Norihito Kasada, Masahito Oyanagi, Akinori Sugishima, Kengo Saito
  • Publication number: 20200185135
    Abstract: Provided is a hexagonal ferrite magnetic powder for a magnetic recording medium, containing hexagonal ferrite magnetic particles having aluminum hydroxide adhered on the surface thereof, the hexagonal ferrite magnetic powder having an Al/Fe molar ratio of 0.030 to 0.200, a Co/Fe molar ratio of 0.002 to 0.030, and a Nb/Fe molar ratio of 0.005 to 0.050, and having an Fe site valence AFe of 3.015 to 3.040 as calculated by AFe=(3+2×[Co/Fe]+5×[Nb/Fe])/(1+[Co/Fe]+[Nb/Fe]) wherein [Co/Fe] represents the Co/Fe molar ratio and [Nb/Fe] represents the Nb/Fe molar ratio, and preferably having an activation volume Vact of 1400 to 1800 nm3. This magnetic powder simultaneously achieves an increase in magnetic characteristics including SNR of a magnetic recording medium and a further increase in durability thereof.
    Type: Application
    Filed: December 4, 2019
    Publication date: June 11, 2020
    Inventors: Hirohisa OMOTO, Shuji KANEDA, Hiroyuki SUZUKI, Toshio TADA
  • Publication number: 20200161035
    Abstract: Provided is an Al-containing hexagonal ferrite magnetic powder which produces an excellent durability-improving effect on a magnetic recording medium, wherein uniform pulverization of the magnetic powder can be easily achieved by dispersion treatment in preparation of a magnetic coating material even in cases where the magnetic powder has a small primary particle size or has a composition which is likely to produce hard secondary particles. The magnetic powder for a magnetic recording medium is an Al-containing hexagonal ferrite magnetic powder having an Al/Fe molar ratio of 0.030 to 0.200, and has a particle size distribution in which the volume ratio of particles having a particle size of 30 ?m or more as measured by a laser diffraction particle size distribution analyzer with a dispersion pressure of 100 kPa is 5.0% or less, and an activation volume Vact of 1800 nm3 or less.
    Type: Application
    Filed: November 14, 2019
    Publication date: May 21, 2020
    Inventors: Hirohisa OMOTO, Shuji KANEDA, Satoshi SHIKI, Hiroyuki SUZUKI, Toshio TADA
  • Patent number: 10614834
    Abstract: Provided is a magnetic tape in which a vertical direction squareness ratio and/or a longitudinal direction squareness ratio obtained by measurement performed by sweeping an external magnetic field in the magnetic tape in a predetermined range by a vibrating sample magnetometer is 0.70 to 1.00, and A calculated by Expression 1 is equal to or smaller than 5.0%. In Expression 1, n represents the number of measurement points measured at magnetic field strength of ?40 kA/m to 40 kA/m during the sweeping and is 52, Mr(Hex) represents a magnetization quantity measured at magnetic field strength Hex, and ? represents an arithmetical mean of Mr(Hex) obtained by measurement performed in the range of the magnetic field strength during the sweeping.
    Type: Grant
    Filed: September 27, 2017
    Date of Patent: April 7, 2020
    Assignee: FUJIFILM Corporation
    Inventors: Atsushi Morooka, Toshio Tada
  • Patent number: 10573341
    Abstract: The magnetic tape has a nonmagnetic layer containing nonmagnetic powder and binder on a nonmagnetic support and a magnetic layer containing ferromagnetic powder and binder on the nonmagnetic layer, wherein a fatty acid ester is contained in at least the magnetic layer, the ferromagnetic powder is ferromagnetic hexagonal ferrite powder, the ferromagnetic hexagonal ferrite powder has a crystallite volume as determined by X-ray diffraction analysis ranges from 1,000 nm3 to 2,400 nm3, and a ratio of the crystallite size Dx(107) obtained from a diffraction peak of a (107) plane to a particle size in a direction of an easy axis of magnetization DTEM as determined by observation with a transmission electron microscope, Dx(107)/DTEM, is greater than or equal to 1.1, and ?SFD in a longitudinal direction of the magnetic tape as calculated with Equation 1: ?SFD=SFD25° C.?SFD?190° C., ranges from 0.50 to 1.60.
    Type: Grant
    Filed: December 22, 2016
    Date of Patent: February 25, 2020
    Assignee: FUJIFILM Corporation
    Inventors: Toshio Tada, Norihito Kasada, Masahito Oyanagi