| 摘要 |
PURPOSE:To improve reproducing output of signals in high frequency and low frequency regions by forming a first magnetic layer and a second magnetic layer on a nonmagnetic supporting body and using a magnetic powder having a specified structure for the second magnetic layer as the uppermost layer. CONSTITUTION:The second magnetic layer 15 as the upper layer of a magnetic layer having a two-layer structure contains acicular metal iron fine particles and a binder. The acicular metal iron fine particle is an acicular material the inside of which essentially consists of iron, especially alpha-Fe, and the surface of which essentially consists of carbon. As for the state of carbon, the carbon may be present to cover the whole surface of the acicular material or may be partially present in dots on the particle surface. As for acicular iron carbide particles, Fe5C2 is used. These particles are produced by bringing a reducing agent containing no carbon atom into contact with acicular iron hydroxide or acicular iron oxide, and then bringing a reducing agent containing carbon atoms into contact. As for the binder, a binder containing amino groups or ammonium salt groups is preferably used. |
