Hitachi Maxell, Limited

Takeshi Matsuura

Yoshiyuki Takahira

Seiji Watatani

Akira Morioka

Hiroshi Sakamoto

Shigeyuki Hosoo

Masatoshi Terazawa

Shinjyo Higashino

Yoshitake Yamaguchi

Hirotaka Kawamura

Naoto Akahane

Takeshi Shibata

Masaaki Yasui

A magnetic recording tape comprising a nonmagnetic substrate and a magnetic layer which is formed on at least one surface of the substrate, the magnetic layer comprising a magnetic powder and a binder resin having a surface resistivity of not larger than 1.times.10.sup.9 .OMEGA./sq. cm and a thickness of not larger than 3.5 .mu.m, the magnetic recording tape having a light transmittance of not larger than 0.8% and a residual magnetic flux density of at least 1400 G, which has good light shielding, and reproduction output characteristics, a small number of dropouts and improved touch with a magnetic head.

Magnetic recording tape

A magnetic recording medium having high running stability and good magnetic characteristics without causing an abrasion problem, which comprises a base film, a magnetic layer provided on one surface (i.e. the major surface) of the base film and a back coat layer provided on the other surface (i.e. the back surface) of the base film, the back coat layer comprising a binder and non-magnetic particles dispersed therein, characterized in that the non-magnetic particles comprise at least one soft inorganic pigment having a hardness of less than 5 in Mohs' scale of hardness and at least one hard inorganic pigment of not less than 5 in Mohs' scale of hardness and of not more than 0.2 .mu.m in average particle size in a weight ratio of the soft pigment to the hard pigment of 99:1 to 50:50.

Magnetic recording medium

A magnetic recording medium comprising a non-magnetic substrate and a magnetic layer formed thereon which contains chromium oxide ferromagnetic powder comprising chromium oxide of the formula:

Magnetic recording medium and production thereof

Magnetic recording medium having a magnetic layer in which magnetic powder of the magnetic layer includes iron oxide magnetic powder with more than 30 m.sup.2 /g specific surface area measured by BET method, chromium dioxide (CrO.sub.2) magnetic powder with more than 30 m.sup.2 /g specific surface area measured by BET method, and the rate of the chromium dioxide powder is within a range more than 3% to less than 20% by weight in the total amount of the magnetic powder in the magnetic powder. Said magnetic layer further includes carbon black.

A magnetic recording medium having a high durability with good electro-magnetic properties, which comprises a base material and a magnetic layer provided thereon, the magnetic layer containing magnetic particles and a binder, characterized in that the magnetic layer further comprises alpha-Fe.sub.2 O.sub.3 particles, Al.sub.2 O.sub.3 particles and Cr.sub.2 O.sub.3 particles.

A magnetic recording medium such as a magnetic tape, which comprises a base film, a magnetic layer having an elastic modulus at 1% elongation of not less than 1,200 kg/mm.sup.2 totally in both longitudinal and width directions which is higher than that of the base film, said magnetic layer being formed on one surface of the base film, and a backcoat layer having an elastic modulus at 1% elongation of not less than 1,200 kg/mm.sup.2 totally in both longitudinal and width directions which is higher than that of the base film, said backcoat layer being formed on another surface of the base film, said magnetic recording medium having a total thickness of not more than 17.mu., said magnetic recording medium having excellent mechanical strength and being used without buckle and injury during usage even in a thin thickness.

A magnetic recording medium which comprises a base material and a magnetic layer provided thereon. The magnetic layer comprises magnetic particles, a cellulose resin and a polyurethane resin as the binders and .alpha.-Fe.sub.2 O.sub.3 particles, whereby the dispersibility of the magnetic particles in the magnetic layer is enhanced without deterioration of the durability of the magnetic layer.

A magnetic recording medium, prevented from blooming of the lubricants therein even after used at a high temperature under a high humidity for a long period of time and excellent in abrasion resistance and durability, comprising an elastic base sheet and a magnetic layer containing magnetic powders and a binder, characterized in that the magnetic layer further contains (A) at least one of esters of saturated aliphatic acids having 18 carbon atoms with aliphatic alcohols having 3 to 6 carbon atoms, (B) at least one of saturated aliphatic acids having 14 to 18 carbon atoms and (C) at least one of zinc salts of saturated aliphatic acids having 14 to 18 carbon atoms, the content of the component (A) being from 0.5 to 2.0% by weight based on the weight of the magnetic powders in the magnetic layer, the content of the component (B) being from 1/4 to 1 part by weight to one part by weight of the component (A) and the content of the component (C) being from 1/3 to 1 part by weight to one part by weight of the combined amount of the components (A) and (B).

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Kyoto, Japan

Takeshi Matsuura