| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a magnetic recording medium having a back coating layer which has not only low travelling friction and excellent wear resistance but can maintain the initial travelling property after the medium is stored for a long time or stored under high temp. and high humidity conditions, which does not damage the magnetic layer such as corrosion, which shows little initial dropout level and which hardly causes deterioration in the error rate. SOLUTION: This medium consists of a nonmagnetic supporting body, a magnetic layer on one surface of the nonmagnetic supporting body and a back coating layer having dispersion of a nonmagnetic powder in a binder on the other surface. The back coating layer contains carbon black and an inorg. powder as an inorg. powder. The carbon black has 40 to 60nm average primary particle size, and the inorg. powder has 40 to 150nm average primary particle size and >=3 Mohs' hardness. The weight ratio of the carbon black to the inorg. powder is controlled to 100:0.5-100:10. The binder contains a phenoxy resin, thermoplastic polyurethane having amino groups in the molecule, and a polyisocyanate compd.</p> |
