Dowa Mining Co., Ltd.

Yasuhiko Aihara

Kazushi Sano

Seiichi Hisano

Kazuhisa Saito

Yoshichika Horikawa

Shinichi Konno

Iron oxyhydroxide particles that are composed of acicular particles having an average major axis of 0.01 to 0.5 &mgr;m and containing not less than 0.1 wt. % and not more than 30 wt. % of Al in the iron oxyhydroxide and that release not less than 0.1 wt. % and not more than 2 wt. % of H,O at 100&deg; C. are used as particles of a lower layer of a coating type magnetic recording medium having a multi-layer structure. The acicular particles include ones having two or more branches whose branching direction is skewed toward a two-dimensional orientation.

Particle for lower layer of coating type magnetic recording medium

Particles for lower layer of coating type magnetic recording medium

A coating type magnetic recording medium having a multilayer structure exhibits excellent strength, surface smoothness, and weather resistance is formed on a substrate, and comprises a magnetic layer of magnetic particles dispersed in a resinous binder, and a non-magnetic layer of non-magnetic particles dispersed in a resinous binder. The magnetic particles are composed of acicular ferromagnetic metal particles of Fe containing Co, Al, rare earth elements, periodic table group 1a and 2a elements. The non-magnetic particles are composed of acicular particles of .alpha.-FeOOH.

Coating type magnetic recording medium having a multilayer structure

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Okayama, Japan

Yasuhiko Aihara