Fuji Photo Film Company, Limited

Toshichika Aoki

Hiroaki Araki

Mikio Ohno

Hiroshi Hashimoto

Masashi Aonuma

Kazutoshi Katayama

Kazuo Kato

Naoto Murao

Tsuneo Yoshida

A magnetic recording medium is provided comprising a non-magnetic support and at least one magnetic layer comprising ferromagnetic metal particles principally containing iron, having a spindle shape and having an average major axis length of 0.15 &mgr;m or less, and a binder resin, and optionally further comprising, between the support and the magnetic layer, at least one adhesive layer or at least one non-magnetic layer principally containing a non-magnetic inorganic powder and a binder, and wherein center line average surface roughness Ra of the magnetic layer surface being 2 to 6 nm, said recording medium having the following properties; steel ball wear at 23&deg; C. and 70% RH being 2&times;10 to 4&times;10 mm , surface C/Fe ratio measured by Auger electron spectroscopy being 50 to 100, and coefficient of friction between the magnetic layer surface and an SUS rod having a roughness of 8 to 10 nm being 0.2 to 0.3.

Magnetic recording medium comprising spindle-shaped ferromagnetic metal particles

A magnetic recording medium is formed from a non-magnetic support, and a magnetic layer formed on the support and including mainly a binder resin and a ferromagnetic metal powder including mainly Fe. The magnetic layer includes an abrasive and a lubricant. The abrasive present on the surface of the magnetic layer satisfies the relationship 0.01&lE;H /H &lE;0.3 where H denotes the number of particles per unit area having a height less than 10 nm (particles/&mgr;m ) and H denotes the number of particles per unit area having a height equal to or greater than 15 nm (particles/&mgr;m ). The magnetic recording medium has a surface lubricant index of 3 to 11. The height of the abrasive particles can be controlled by, for example, a blade treatment using an abrasive tape (LTBL system) or a diamond powder-studded rotating roll (DWBL system).

Magnetic recording medium

The present invention discloses a magnetic recording particulate mediumhaving amagnetic layer on anonmagnetic support, the magnetic layer containing a ferromagnetic metal powder and a binder and having a coercive force of 1,400 to 1,700 Oe, wherein the ferromagnetic metal powder is spindle-shaped particles consisting essentially of Fe and having a Co/Fe ratio of from 1 to 5 atomic %, an Al/Fe ratio of from 5 to 15 atomic %, an average major axis length of 0.1 to 0.2 .mu.m and a specific surface area of 40 to 50 m.sup.2 /g, and the binder contains a polyurethane consisting essentially of a diol component comprising a polyether polyol and a polyester polyol and a polyisocyanate component. This magnetic recording particulate medium is characterized by minimal head wear, freedom from head clogging, and satisfactory electromagnetic characteristics.

Magnetic recording particulate medium

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Kanagawa, Japan

Toshichika Aoki