Tdk Corporation

Shigeharu Watase

Yutaka Takahashi

Osamu Inoue

Kiyoto Fukushima

Kazunori Tamazaki

Hiroyuki Miyabara

Yoshio Kawakami

Youichi Yoshimura

A magnetic recording medium comprising at least a lower non-magnetic layer containing at least a non-magnetic powders and a binder resin formed on a non-magnetic support and an upper magnetic layer formed on the lower non-magnetic layer, wherein the magnetic recording medium is used for a recording-reproducing system in which recorded signals are reproduced by an MR head, and a plastic deformation hardness Hv from the upper magnetic layer surface to an indentation depth of 0.1 &mgr;m is 100 to 200 mgf/&mgr;m and a Young's modulus E in a thickness direction from the upper magnetic layer surface to the indentation depth of 0.1 &mgr;m is 2000 to 3000 mgf/&mgr;m .

Magnetic recording medium

A magnetic recording medium includes a flexible substrate, a coating layer formed on the flexible substrate, and a magnetic layer formed on the coating layer. The coating layer contains a binder and nonmagnetic particles and has a thickness in the range of 0.05 to 0.7 .mu.m as a result of a stretching treatment performed at least once after application of the coating layer on the flexible substrate. The magnetic layer contains magnetic powder, a binder and an abrasive and has a thickness in the range of 0.05 to 1.0 .mu.m. The nonmagnetic particles contained in the coating layer has an average particle size in the range of 0.01 to 0.08 .mu.m. The abrasive contained in the magnetic layer has an average particle size in the range of 0.05 to 0.8 .mu.m and satisfies conditions defined by the following equations (1) and (2):

This invention concerns a magnetic recording medium which comprises a nonmagnetic support, a magnetic layer provided on one surface of the nonmagnetic support and a backcoat layer provided on the other surface of the nonmagnetic support, wherein the nonmagnetic support is provided with such physical properties as Young's moduluses in the longitudinal direction and the lateral direction thereof in the range of 1300-1600 kg/cm.sup.2, respectively, and a breaking elongation in the range of 3-10% and said magnetic recording medium is provided on the magnetic layer side thereof with a convex cupping the magnitude of which is in the range of 0.02-0.20 mm at a width of 3.8 mm. The magnetic recording medium, therefore, realizes perfect head touch even when the thickness of the nonmagnetic support and the thickness of the whole medium are small. Even when the magnetic recording medium is exposed to the mechanical influences and physical influences of aging, it suffers extremely small change in the form (such as, for example, the cupping value) and therefore conserves the head touch and other factors in highly satisfactory state. It suffers occurrence of dropout or head stain only sparingly.

Disclosed is a magnetic recording medium comprising a nonmagnetic support and a paint film layer which is provided on the support and has a lamination structure consisting of two or more layers, wherein the top surface magneticlayer of the layers constituting the paint film layer contains abrasive particles having a Mohs hardness of not less than 6 in an amount of 3 to 16 parts by weight based on 100 parts by weight of a ferromagnetic powder and has a thickness of not more than 0.5 .mu.m, a ratio of a mean particle diameter of the abrasive particles to the thickness of the top surface magnetic layer is in the range of 1.0 to 1.8, and a content of the abrasive particles each having a size larger than the thickness of the top surface magnetic layer in the particle size distribution of the abrasive particles is in the range of 50 to 90% by weight. The magnetic recording medium having such constitution is excellent in running endurance and running properties and shows high electromagnetic conversion characteristics.

Growing community of inventors

Saku, Japan

Shigeharu Watase