Tdk Corporation

Yuji Ishihara

Hitoshi Azegami

Kuniichi Yoda

Shigeru Takamatsu

Masahiro Takizawa

A magnetic recording medium comprising a plastic base of polyester film or the like having a magnetic coat formed on one side, the magnetic coat consisting of a dispersion of a ferromagnetic powder in a resin binder, characterized in that the magnetic coat contains a nonmagnetic composite oxide powder of a spinel structure in an amount of 0.5 to 15% by weight on the basis of the ferromagnetic powder weight. The composite oxide in powder form ranges in particle diameter from 0.1 to 0.7 .mu.m and has a Mohs hardness of not less than 5.

Magnetic recording medium

A magnetic recording medium comprises a magnetic coating material, or a dispersion of magnetic particles in a resinous binder, and a base to which the coating material is solidly applied, the resinous binder comprising as its ingredients a copolymer composed of vinyl chloride, vinylidene chloride, a vinyl alkylcarboxylate, another monomer copolymerizable with vinyl chloride, and a saponified vinyl alkylcarboxylate and having an OH/CH absorption ratio according to the infrared absorption spectrum of at least 0.2, a polyurethane resin having in its molecule a --SO.sub.3 M group wherein M represents an alkali metal atom, and a polyisocyanate.

A magnetic recording medium comprising a resinous component in which magnetic particles are dispersed and a base to which the dispersion is solidly applied, the resinous component consisting of a copolymer having an OH/CH absorption ratio according to the infrared absorption spectrum of 0.2 or more and made from (A) vinyl chloride, (B) vinylidene chloride, (C) a vinyl alkylcarboxylate, (D) an other monomer copolymerizable with vinyl chloride, and (E) a saponified vinyl alkylcarboxylate, and a rubbery binder. Alternatively, a polyisocyanate is added to the above copolymer.

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Saku, Japan

Yuji Ishihara