| 摘要 |
PURPOSE:To eliminate cupping by forming a magnetic layer on a flexible substrate and by carrying out heat treatment at a temp. from the glass transition temp. of the substrate to 150 deg.C in a flatly extended state. CONSTITUTION:A layer of metallic cobalt 2 having 0.1mum thickness is vapor-deposited on a polyethylene terephthalate film 1 having 36mum thickness to form a magnetic tape. Immediately after the vapor deposition the tape is heat treated at a certain temp. for 1hr in a flatly extended state. In case of <=60 deg.C heat treatment temp., the size (d) of cupping is slightly changed from the size immediately after the vapor deposition. In case of >=80 deg.C heat treatment temp., cupping is eliminated. It is supposed that the thermal and mechanical properties of the substrate are changed by heat treating the substrate at the glass transition temp. or above, yet the substrate is shrunk by only 0.2%, and no practically troublesome deterioration of the characteristics is recognized. In case of >150 deg.C heat treatment temp., the magnetic tape undergoes remarkable thermal deformation. |
