| 摘要 |
PURPOSE:To provide a film combining flatness and slipperiness with resistance to scraping by a structure wherein silicon dioxide particles, which are secondary particles formed by binding primary particles and has a large internal surface area, are dispersingly contained in polyester. CONSTITUTION:The title film is formed by dispersingly containing 0.01-3wt% of silicondioxide particles, which are secondary particles having mean particle size of 0.03-3mum formed by bonding primary particles having mean particle size of 1-20mum and at the same time BET surface area of which is 250m<2>/g or more, in polyester. Because the internal surface area of the silicondioxide fine particles is large as described above, the effective contact surface area between said silicon dioxide particles and the polyester and accordingly the affinity between the particles and the polyester can be improved. Consequently, the generation of void can be suppressed to lower value, even when the areal draw ratio is made larger at the orientation of a film and the running durability in a tape as recording medium becomes extremely good. |
