Tdk Corporation

Yoshio Kawakami

Kuniichi Yoda

Kiyoto Fukushima

Shigeharu Watase

Hiroyuki Miyabara

Eiji Kitaura

Tsutomu Tsunoda

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.

Magnetic recording medium having a magnetic layer containing abrasive

A magnetic recording medium comprises a light-shielding base in the form of a tape or sheet, and a magnetic layer composed of a magnetic powder of Co-coated .gamma.-Fe.sub.2 O.sub.3 dispersed in a resin binder and applied to the base. The powder has a specific surface area as determined by the BET adsorption method of at least 35 m.sup.2 /g. The light-shielding base portion contiguous to the magnetic layer is a transparent plastic film and the lower base portion is light-shielding. The light-shielding base has a light transmittance of 30% or below. The surface roughness of the base is, in terms of the center-line average surface roughness, 0.012 .mu.m or below.

Magnetic recording medium

In a magnetic recording medium comprising a substrate and a magnetic layer formed thereon and composed of magnetic powder dispersed in a polymer binder, an improvement wherein said substrate is made of a polyethylene terephthalate having a refractive index of at least 1.499 in the direction of the thickness of the substrate.

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Nagano-ken, Japan

Yoshio Kawakami