| 摘要 |
PURPOSE:To obtain a biaxially oriented polyester film excellent in abrasion resistance and running stability and suitable for a magnetic tape or the like, by specifying its surface roughness, frictional coefficient after repeated running protrusion height, flexibility coefficient of protrusion, etc. CONSTITUTION:A biaxially oriented polyester film having a surface roughness of 0.008-0.025mum, a frictional coefficient after 500 repeated runnings of 0.14-0.38, free of protrusions of a height >=0.75mum and having a flexibility coefficient of protrusion of 1.3-2 is provided. This film can be obtained by specifying the shape, particle diameter, amount, stretching temperature, stretch ratio, speed, heat-treatment temperature, time, etc. of the solid fine particles in producing a biaxially oriented polyester film by melt-extruding a polyester containing solid fine particles (e.g., silicon dioxide) into a film, biaxially stretching this film and heat-treating it. |
