| 摘要 |
PROBLEM TO BE SOLVED: To enhance the vapor deposition characteristics of a magnetic metal film having no defect, in a thermoplastic resin film used as the basis of a magnetic recording medium using a ferromagnetic metal film as a magnetic layer, by setting the foreign matter with predetermined height bonded to the surface of the film to a predetermined number or less. SOLUTION: In a thermoplastic resin film used as the basis of a magnetic recording medium using a ferromagnetic metal film as a magnetic layer, the foreign matter with a height of 5.4μm or more bonded to the surface of the film is set to one or less per 1m<2> . Ultrasonic pressure air has a purpose springing out the foreign matter bonded to the surface of the film. By this constitution, the greater part of foreign matters with a height of 5.4μm or more bonded to a base film are removed to obtain an objective film. It is not pref. that two or more large foreign matters having height larger than 5.4μm is present per 1m<2> because thermal defeat becomes easy to generate when the ferromagnetic metal film is vapor-deposited. |
