With Additional Nonmagnetic Particles Patents (Class 428/845.3)
  • Patent number: 11538495
    Abstract: A magnetic recording medium that can exhibit good traveling performance during use is provided. This magnetic recording medium is a tape-shaped magnetic recording medium, and includes a substrate, a base layer disposed on the substrate, and a magnetic layer disposed on the base layer. The substrate includes a polyester as a main component. The average thickness of the base layer is 0.9 ?m or less. The base layer and the magnetic layer each include a lubricant. The magnetic layer has a surface having a large number of holes, and the arithmetic average roughness Ra of the surface is 2.5 nm or less. The BET specific surface area of the entire magnetic recording medium is 3.5 m2/g or more in a state where the lubricant has been removed from the magnetic recording medium and the magnetic recording medium has been dried. The squareness ratio in the perpendicular direction is 65% or more. The average thickness of the magnetic layer is 90 nm or less. The average thickness of the magnetic recording medium is 5.
    Type: Grant
    Filed: October 1, 2019
    Date of Patent: December 27, 2022
    Assignee: Sony Group Corporation
    Inventors: Kazuya Hashimoto, Minoru Yamaga, Takanobu Iwama, Jun Takahashi
  • Patent number: 7186472
    Abstract: A magnetic recording medium comprising a support and a magnetic layer containing an abrasive, a binder and ferromagnetic powder dispersed in the binder, wherein the magnetic layer has a thickness of from 20 to 500 nm, the abrasive has a Mohs' hardness of 5 or more and a relative abrasive velocity of less than 200, and value A of a relational expression A=K/Z of an average particle size K of the abrasive and the thickness Z of the magnetic layer is from 0.1 to 3.0.
    Type: Grant
    Filed: May 25, 2004
    Date of Patent: March 6, 2007
    Assignee: Fuji Photo Film Co., Ltd.
    Inventor: Noboru Zinbo