| 摘要 |
PURPOSE:To obtain the title film excellent in travelling performance, electromagnetic transduction characteristics and abrasion resistance, by specifying the density, protrusion height and burst void density of a biaxially oriented polyester film having many fine protrusions on the surface and containing a lubricant. CONSTITUTION:A polyester comprising at least 80mol.%, based on the total repeating units, ethylene terephthalate units and containing a lubricant (e.g., TiO2) is molded into a film, and this film is biaxially oriented at 180-230 deg.C for 120-2sec to obtain a biaxially oriented film having a density of 1.385-1.395g/cm<3>, an h(max) (the height of the highest protrusion in a region of an area of 0.01mm<2>) of 0.2-0.5mum, a density of burst voids present on the surface below 1/mm<2> and having many fine protrusions on the surface. |
