| 摘要 |
<p>PURPOSE:To make a magnetic recording medium suitable for high-density recording at about <=2mum recording wavelength by forming the magnetic layer consisting of specific ferromagnetic metallic powder and having >=700Oe coercive force, <=0.015mum surface roughness and 1.5-4.5mum thickness on a specific polyester film. CONSTITUTION:The polyester film has 4-12mum thickness, >=16kg/mm.<2> F5 value in the longitudinal direction, >=25kg/mm.<2> rupture strength and >=90% breaking extension. The surface characteristic of the non-magnetic substrate is 0.015- 0.025mum surface roughness at 0.25m/m cutoff by a stylus type and the fisheyes thereof are 0 pieces of >=6H height, <=2 pieces of 5H and <=5 pieces of 4H in 100cm<2>. On the other hand the ferromagnetic metallic powder has 115-145emu/ g sigmas and 35-55m<2>/g specific surface area by BET method. The prescribed magnetic layer is obtd. by mixing, kneading and dispersing the ferromagnetic metallic powder, binder, lubricating agent, polishing agent, conductive carbon and org. solvent to prepare a magnetic coating liquid and coating said liquid on the non- magnetic substrate.</p> |
