| 摘要 |
PURPOSE:To improve the slipperiness, wear resistance and scratching resistance of a magnetic disk and to improve electromagnetic characteristics by using a polyester film which contains Al2O3 particles of a specific grain size at spe cific % and having a specific refractive index. CONSTITUTION:The Al2O3 particles having <=5.0mum average grain size are incorporated at 0.01 to 5.0wt.% into the polyester film and the refractive index of the film is specified to >=1.604. Not only the traveling property and the wear resistance are improved but also the scratching resistance is greatly im proved if the Al2O3 particles exist in the film. The effect of improving the wear resistance, etc., decreases drastically if the content is below 0.01wt.% and there is no improvement in the effect at >=5.0%. The dislodgment of the particles arises, the degradation in the wear resistance and the increase in surface protections are resulted and the good electromagnetic conversion characteristics are not obtainable if the grain size exceeds 5mum. The extremely marked effect of improving the scratching resistance is obtd. by specifying the average refractive index to >=1.604. |
