| 摘要 |
PURPOSE:To improve reproducing output by using a hexagonal ferrite having specified particle size and coercive force as a ferromagnetic powder, polyurethane having polar groups and/or vinyl chloride resin as a binder resin, and dispersing an abrasive powder of specified particle size near the surface of a magnetic layer. CONSTITUTION:The ferromagnetic powder used is a hexagonal ferrite fine powder having 0.01-0.2mum particle size and 600-2000Oe coercive force. The binder resin consists of polyurethane having polar groups such as SO3M, etc., and/or vinyl chloride resin, and is used by 10-25 pts.wt. to 100 pts.wt. of the ferromagnetic powder. The abrasive powder consists of a fine-particle abrasive having 0.1-0.39mum average particle size and a coarse abrasive having 0.4-1.0mum average particle size. These abrasives are dispersed in each other, added and dispersed in the binder and magnetic powder to prepare a magnetic coating material. This coating material is applied on a nonmagnetic supporting body so that a larger amt. of the coarse abrasive is distributed near the surface of the magnetic layer. Thereby, the coefft. of friction is decreased while output is stably maintained high, which improves traveling durability. |
