| 摘要 |
PURPOSE:To obtain a magnetic disk where unevenness will not occur at a disk due to the change of the using environment temperature by providing a clearance between the rear surface and the base of a flexible disk having thermal contraction stress, providing one air hole or above at the clearance, and sticking the disk and the base. CONSTITUTION:To a supporting bar 4 of a flexible magnetic disk 2, for example, by using a two-shaft orientating polyethylene terephthalate film, a magnetic layer 5 is formed on the supporting bar 4, and thereafter, the thermal treatment is executed for 3sec-24hr in accordance with the temperature at <=70 deg.C-120 deg.C so that the contraction ratio after the 70 deg.C and 48hr thermal treatment may come to be 0.2% or below and the longitudinal and horizontal contraction ratio difference may come to be 0.1%, and the thermal contraction stress of 0.1-200kg/m is held. For the side surface opposite to the magnetic layer 5 of the processed flexible disk, a clearance is provided at Al, glass and a base 1 which will not generate the thermal deformation at <=120 deg.C, one air hole 8 to lead to the clearance 3 is made at a circumferential part 6 of the base 1 and junctioned with the base 1. Thus, a good recordable reproducible disk is always obtained in which the unevenness will not occur at a disk 1 due to the pressuring change in the clearance 3 by the using environment temperature.
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