| 摘要 |
PURPOSE:To provide a base material excellent not only in electric characteristics, transparency and mechanical strength required for industrial products, packing, a magnetic tape or a condenser but also in flatness, printability and heat resistance by optimizing the stretching condition of a polystyrene film having a syndiotactic structure. CONSTITUTION:A film formed by stretching a polystyrenic polymer mainly composed of a syndiotactic structure at least in a uniaxial direction is characterized by that the refractive index Nz in the thickness direction of the film is 1.6200 or more and the heat shrinkage factor thereof at 150 deg.C is below 3%. |
