BIAXIALLY ORIENTED POLYESTER FILM

摘要

PURPOSE:To prepare the title film excellent in flatness, wear resistance, and slipperiness and suitable esp. as a magnetic tape base by forming a polyester contg. ceramic particles having specific properties into a film and biaxially orienting the film. CONSTITUTION:The title film contains 0.01-1.0wt.% thermally conductive ceramic particles having the following properties: an area ratio of circumscribed circle (%) expressed by [(projected area of particle)/(area of the circle circumscribed to particle)]X100 of 60% or higher; a degree of dispersion of particle diameter (%) expressed by [(standard deviation of particle diameter)/(mean particle diameter)]X100 of 30% or lower; a mean particle diameter of 0.01-2.0mum; and a thermal conductivity of 0.01cal/cm.sec. deg.C or higher. As the ceramic having such properties, beta-type silicon carbide and aluminum nitride are pref. in virtue of their high thermal conductivity and low toxicity.