Magnetic Layer Chemical Composition Patents (Class 428/840.6)
  • Publication number: 20140219069
    Abstract: The magnetic recording medium is a particulate magnetic recording medium for heat-assisted recording, as well as includes a magnetic layer comprising ferromagnetic powder and binder on a nonmagnetic organic material support and a heat-diffusing layer of higher thermal conductivity than the magnetic layer between the nonmagnetic organic material support and the magnetic layer.
    Type: Application
    Filed: February 4, 2014
    Publication date: August 7, 2014
    Applicant: FUJIFILM Corporation
    Inventors: Yasushi HATTORI, Hidehiro MOCHIZUKI, Toshio SASAKI
  • Publication number: 20120300339
    Abstract: According to the present invention, a magnetic recording medium is provided including a disk-shaped non-magnetic substrate and at least a perpendicular magnetic layer formed on the disk-shaped non-magnetic substrate, wherein the perpendicular magnetic layer has a structure in which an FePt or CoPt nanoparticle array is formed on a formation surface, on which a plurality of striations each having a circumferential directional component are formed, by a texturing treatment; a manufacturing method thereof; and a magnetic record/reproduction apparatus including the magnetic recording medium or a magnetic recording medium manufactured according to the manufacturing method.
    Type: Application
    Filed: May 23, 2012
    Publication date: November 29, 2012
    Applicants: WASEDA UNIVERSITY, SHOWA DENKO K.K.
    Inventors: Tetsuya OSAKA, Atsushi SUGIYAMA, Takuma HACHISU, Tomoo SHIGE, Masato FUKUSHIMA, Akira YAMANE, Akira SAKAWAKI
  • Patent number: 7722969
    Abstract: A magnetic tape comprising a non-magnetic support, a primer layer formed on one surface of the support, a magnetic layer formed on the primer layer, and a back layer formed on the other surface of the support, in which the tape has a total thickness of 4.0 to 5.4 ?m, at least one of the primer layer and the magnetic layer contains a fatty acid amide, and an amount of the fatty acid amide extracted from the side of the magnetic layer with n-hexane is from 0.5 to 1.5 mg/cm3.
    Type: Grant
    Filed: April 18, 2005
    Date of Patent: May 25, 2010
    Assignee: Hitachi Maxell, Ltd.
    Inventors: Kazuhiko Nakiri, Sadamu Kuse
  • Patent number: 7641991
    Abstract: A magnetic recording medium is provided that comprises a non-magnetic support and at least one magnetic layer above the support, the magnetic layer comprising a ferromagnetic powder dispersed in a binder, and the binder comprising a polyurethane resin having a weight-average molecular weight of 200,000 to 400,000. There is also provided a magnetic recording medium that comprises a non-magnetic support, a non-magnetic layer above the support, the non-magnetic layer comprising a non-magnetic powder dispersed in a binder, and at least one magnetic layer above the non-magnetic layer, the magnetic layer comprising a ferromagnetic powder dispersed in a binder and the binder of the magnetic layer and/or the non-magnetic layer comprising a polyurethane resin having a weight-average molecular weight of 200,000 to 400,000.
    Type: Grant
    Filed: September 14, 2006
    Date of Patent: January 5, 2010
    Assignee: FUJIFILM Corporation
    Inventors: Yuichiro Murayama, Hiroshi Hashimoto
  • Publication number: 20090142622
    Abstract: The present invention provides a magnetic recording medium comprising an undercoating layer comprising a radiation-curable compound that has been cured by irradiation with radiation, a nonmagnetic layer comprising a nonmagnetic powder and a binder, and a magnetic layer comprising a ferromagnetic powder and a binder in this order on a nonmagnetic support, wherein the magnetic layer and/or the nonmagnetic layer comprise a carbonic ester denoted by general formula (1), and the undercoating layer has an indentation hardness lower than that of the nonmagnetic support. In general formula (1), each of R1 and R2 independently denotes a saturated hydrocarbon group, with a total number of carbon atoms in R1 and R2 being equal to or higher than 12 but equal to or lower than 50.
    Type: Application
    Filed: December 3, 2008
    Publication date: June 4, 2009
    Applicant: FUJIFILM Corporation
    Inventor: Kenichi NAKAMURA
  • Publication number: 20090136783
    Abstract: The invention provides a magnetic recording medium with both weather resistance and high recording density. The magnetic recording medium of the invention has a magnetic layer comprising at least SmCo-based magnetic fine particles and a hydrophobic binder, wherein the SmCo-based magnetic fine particles include a core composed of SmCo-based nanoparticles and a hydrophilic polymer covering at least a portion of the surface of the core.
    Type: Application
    Filed: November 21, 2008
    Publication date: May 28, 2009
    Applicant: TDK Corporation
    Inventors: Nobuhiro Jingu, Mamoru Satoh, Kenichi Kitamura, Megumi Yoshimura
  • Patent number: 7264893
    Abstract: The invention provides a magnetic recording medium comprising a support having provided thereon a nonmagnetic layer containing a nonmagnetic powder, and a magnetic layer containing a ferromagnetic powder formed on the nonmagnetic layer after coating and drying thereof, wherein the ferromagnetic layer is a hexagonal ferrite powder having an average tabular diameter of 15 to 40 nm or a ferromagnetic metal powder having an average major axis length of 25 to 100 nm, the thickness of the magnetic layer is from 0.01 to 0.3 ?m, the thickness of the nonmagnetic layer is from 0.5 to 5 ?m, and the specific surface area and the total pore volume of the magnetic recording medium itself measured by a nitrogen absorption measured method are from 0.1 to 50 m2/g and from 0.001 to 1 ml/g, respectively, thereby being to provide the magnetic recording medium for high density recording remarkably improved in electromagnetic characteristics, particularly in high density recording characteristics.
    Type: Grant
    Filed: April 30, 2004
    Date of Patent: September 4, 2007
    Assignee: FUJIFILM Corporation
    Inventors: Takeshi Harasawa, Hiroaki Takano
  • Patent number: 7108927
    Abstract: The present invention relates to a magnetic recording medium comprising a magnetic layer on at least one side of a nonmagnetic substrate, the magnetic layer containing magnetic particles of a CuAu type or Cu3Au type ferromagnetic ordered phase, wherein a conductive layer is provided on at least one side of the nonmagnetic substrate.
    Type: Grant
    Filed: October 29, 2003
    Date of Patent: September 19, 2006
    Assignee: Fuji Photo Film Co., Ltd.
    Inventors: Yasushi Hattori, Koukichi Waki
  • Patent number: 7041396
    Abstract: Provided is a magnetic recording medium affording good head contact and high output in addition to excellent head abrasion characteristics acceptable to high data transmission rates. The magnetic recording medium comprises a nonmagnetic layer comprising a nonmagnetic powder and a binder and a magnetic layer comprising a ferromagnetic powder and a binder in this order on a support. Said magnetic layer comprises an abrasive in a quantity of 2 to 5 weight percent with respect to the ferromagnetic powder, the number of protrusions having a height of 3 to 7 nm per 23,000 ?m2 of a surface of the magnetic layer, measured by a non-contact three-dimensional structure analyzing microscope, ranges from 50 to 200, and said magnetic layer has a microindentation hardness ranging from 40 to 80 kg/mm2 at a load of 6 mgf.
    Type: Grant
    Filed: September 10, 2004
    Date of Patent: May 9, 2006
    Assignee: Fuji Photo Film Co., Ltd.
    Inventors: Tomohiro Ichikawa, Naoto Murao
  • Patent number: 7022424
    Abstract: A magnetic recording medium comprising, in this order, a nonmagnetic support, a lower layer containing nonmagnetic powder and a binder, and a magnetic layer containing ferromagnetic powder and a binder, wherein N/Fe of the magnetic layer measured with a fluorescent X-ray apparatus is from 0.5 to 1.9 wt %, and a number of concavities having a depth of 5 to 10 nm on a surface of the magnetic layer is from 20 to 100/100 ?m2.
    Type: Grant
    Filed: July 7, 2004
    Date of Patent: April 4, 2006
    Assignee: Fuji Photo Film Co., Ltd.
    Inventor: Shiho Kamisawa
  • Patent number: 6991862
    Abstract: In one aspect, the magnetic recording medium comprises a magnetic layer comprising a ferromagnetic powder and a binder and said binder comprises polyurethane resin having a glass transition temperature of 100 to 200° C. In a second aspect, the magnetic recording medium comprises a nonmagnetic layer comprising a nonmagnetic powder and a binder and a magnetic layer comprising a ferromagnetic powder and a binder in this order on a nonmagnetic support and at least the binder comprised in said magnetic layer comprises polyurethane resin having a glass transition temperature of 100 to 200° C. In both aspects, said magnetic layer has a thickness equal to or less than 0.15 ?m, said ferromagnetic powder has a mean major axis length or a mean plate diameter of 60 nm or less, and said magnetic layer has a coercivity of 159 to 239 kA/m in a longitudinal or in-plane direction.
    Type: Grant
    Filed: March 29, 2004
    Date of Patent: January 31, 2006
    Assignee: Fuji Photo Film Co., Ltd.
    Inventors: Mikio Ohno, Tatsuo Ishikawa
  • Patent number: 6991861
    Abstract: The coating-type magnetic recording medium has a non-magnetic layer mainly composed of a non-magnetic powder and binder, and a magnetic layer mainly composed of a ferromagnetic powder and a binder, which are stacked in this order on a non-magnetic substrate, wherein dispersion ?L/L of long-axis length of all ferromagnetic powder particles contained in the magnetic layer falls in a range of ?L/L?±10%, where L is an average long-axis length and ?L is a standard deviation thereof, and dispersion ?W/W of short-axis length of all ferromagnetic powders contained in the magnetic layer falls in a range of ?W/W?±15%, where W is an average short-axis length and ?W is a standard deviation thereof. The average long-axis length L is typically adjusted within the range of 0.08 ?m and 0.12 ?m, and the Switching Field Distribution (SFD) of the medium is adjusted to 0.25 or less.
    Type: Grant
    Filed: June 8, 2004
    Date of Patent: January 31, 2006
    Assignee: Sony Corporation
    Inventors: Akiko Watanabe, Katsunori Maeshima, Tomoo Fukuda, Noboru Sekiguchi