| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain an upper magnetic layer which has excellent surface property, excellent electromagnetic conversion characteristics and travelling durability and which can maintain good lubricating property for a long time by specifying the particle size and surface chemical properties of a nonmagnetic powder and kinds of a binder in a lower nonmagnetic layer. SOLUTION: A lower nonmagnetic layer 2 essentially comprising a nonmagnetic powder and a binder, and an upper magnetic layer 3 essentially comprising a magnetic powder and a binder are formed on a nonmagnetic supporting body 1. As the nonmagnetic powder, a powder having <=0.2μm major axial length and having an acid surface is used. As the binder, vinyl chloride copolymers having sulfonate groups and/or quaternary ammonium salt groups, hydroxyl groups and epoxy groups, and having 100 to 220 average polymn. degree are used. Thereby, the lower nonmagnetic layer 2 and the upper magnetic layer 3 can be formed with smooth surfaces, and good electromagnetic conversion characteristics can be obtd. Further, good lubricating property and excellent travelling durability can be obtd. for a long time on the surface of the upper magnetic layer 3.</p> |
