| 摘要 |
PURPOSE:To obtain excellent durability and stable traveling property by incorporating a graft or block copolymer having a structural part which is compatible with a binder and a structural part which is lubricative into a magnetic layer. CONSTITUTION:This magnetic recording medium is formed with the magnetic layer contg. magnetic powder and binder on a nonmagnetic base and contains the graft or block copolymer having the structural part which is compatible with the binder and the structural part which is lubricative in the magnetic layer. Since the graft or block copolymer to be incorporated into the magnetic layer is a high polymer, the copolymer has the low mobility of the molecules in the magnetic layer and in addition, the structural part which is compatible with the binder acts as an anchor to the magnetic layer by the strong affinity to the binder. The binder is, therefore, hardly dissipated to the outside of the magnetic layer. A phase sepn. does not arise even if the binder migrates to the surface side at the time of forming the magnetic layer. The structural part which is lubricative provides a good lubricating effect on the surface of the magnetic layer. Since the copolymer is distributed in the magnetic layer as well, the lubricating effect is continuously exhibited even if the magnetic layer is gradually worn by repeated recordings and reproductions. |
