| 摘要 |
PURPOSE:To obtain the titled film having a flat surface and being excellent in abrasion resistance, protrusion deformation resistance and heat stability, containing a poly(alkylene glycol) and specified in centerline mean roughness of a surface. CONSTITUTION:A polyester of an intrinsic viscosity >=0.40 is mixed with 0.01-2wt% poly(alkylene glycol) of a MW of 500-5,00,000 and 0.005-2wt% inert compound (e.g., kaolin) of an average particle diameter of 0.002-4mu. The mixture is extruded through an extruder at 280-320 deg.C into a sheet, and this sheet is cooled to 70 deg.C or below to obtain an amorphous sheet. A biaxially orientated polyester film obtained by drawing the above sheet in lengthwise and lateral directions at a draw ratio >=4 is heated at 120-250 deg.C to obtain a biaxially orientated polyester film for magnetic recording media, having a centerline mean roughness of a surface of 0.009-0.023mu. |
