| 摘要 |
<p>PURPOSE:To produce a double-face flexible magnetic disk which is stable and does not curl by using polyvinyl biphenyl imide as a high-polymer substrate and subjecting the substrate to a heat treatment at >=100 deg.C, then forming magnetic layers on the substrate. CONSTITUTION:The high-polymer substrate consisting of the polyvinyl biphenyl imide having the molecular structure expressed by formula I is heat-treated at >=100 deg.C and thereafter, the magnetic layers are formed on both faces of the substrate. The polyvinyl biphenyl imide is excellent in heat resistance, thermal stability and surface characteristic. Namely, the polyvinyl biphenyl imide substrate has no glass transition point and is merely gradually thermally decomposed at >=500 deg.C even if said substrate is heated up. Said substrate has the property values of 800-1,200kg/mm<2> Young's modulus and 3X10<-5>-1X10<-6>cm/ cm/ deg.C coefft. of thermal expansion. The curling is thereby stably eliminated and the flexible magnetic disk is produced at a good yield.</p> |
