| 摘要 |
<p>PURPOSE:To obtain a polyester film for a high density magnetic disk excellent in surface properties, reduced in detachment of particles and excellent in scratch resistance by laminating a polyester layer with specific thickness to at least the single surface of a polyester layer by a co-extrusion method. CONSTITUTION:A film is formed by laminating a polyester (B) layer with thickness of 3mum or less to at least the single surface of a polyester (A) layer by a co-extrusion method and the center line average roughness Ra of the surface of the polyester (B) layer is within the range of 0.002-0.015mum and no protrusion with height of 0.81mum or more is present on the surface of the polyester (B) layer. The peak count Pc of the surface of the polyester (B) layer is 50/0.8mm or more, pref., 75/0.8mm or more. By applying a magnetic layer to the film thus obtained by coating, vapor deposition or sputtering, a high density magnetic disk excellent in easy slip properties can be formed.</p> |
