| 摘要 |
PURPOSE:To improve the oxidation resistance of ferromagnetic metallic powder and to obtain a magnetic recording medium having an improved magnetic characteristic and stability with lapse of time by incorporating trialkyl phosphine oxide into a magnetic layer formed by dispersing the ferromagnetic metallic powder into a binder. CONSTITUTION:The trialkyl phosphine oxide expressed by the formula O=PR3 (R is an alkyl) in which the alkyl of 5-20C, more particularly 8C is more preferable is incorporated into the ferromagnetic powder consisting of an Fe-Co-Ni alloy in a 0.5-10pts. range by 100pts. said powder. The suitable amt. of a polyisocyanate crosslinking agent is added to the mixture composed of such powder and a binder resin, if necessary ketone, toluene, etc. contg. an abrasive agent such as alpha-Al2O3 and dispersant such as lecitin to prepare a magnetic paint. Such paint is coated on a substrate consisting of a polyester film, etc. and is subjected to the orientation treatment of the magnetic powder. The coating is calendered after drying, by which a magnetic tape is obtd. The trialkyl phosphine oxide is adsorbed by the magnetic powder and acts as an oxidation inhibitor. Said oxide improves also the dispersibility of the magnetic powder and the moisture resistance and oxidation resistance of the magnetic layer. The excellent magnetic tape is thus obtd.
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