| 摘要 |
PURPOSE:To use the titled micro floppy disk even in a high-temp. atmosphere by specifying the thermal contraction coefficient and Young's modulus of a film to be used as the substrate of the disk. CONSTITUTION:A biaxially oriented polyethylene naphthalate film having <=0.05% thermal contraction coefficient when heated at 70 deg.C for 1hr in every direction in the plane, having 0.1-1.5% thermal contraction coefficient when heated at 150 deg.C for 1hr and having 600-750kg/mm<2> Young's modulus is used as the nonmagnetic substrate and a magnetic layer is provided on one or both surfaces of the substrate. At <600kg/mm<2> Young's modulus, the magnetic recording medium flutters when the r.p.m. of the FDD is increased, hence the uniform contact with a magnetic head is not maintained, a recording and a reproducing miss are caused and the linear density is hardly increased. Meanwhile, the contact of the magnetic recording medium with a magnetic head is excessively intensified at >750kg/mm<2> Young's modulus and the magnetic layer of the magnetic recording medium is worn out. |
