| 摘要 |
PURPOSE:To provide a polyester film excellent in cut resistance and scratch resistance, useful for magnetic recording media, etc., incorporated with aluminum oxide particles having each specific surface area, means diameter and alpha-type crystal form content and inert particles having specific mean diameter. CONSTITUTION:Pellets such as of polyethylene terephthalate incorporated with (A) 0.05-1wt.% of aluminum oxide particles 50-150m<2>/g in specific surface area, 0.05-0.3mum in means diameter and 3-30wt.% in the content of aluminum oxide with alpha-type crystal form and (B) 0.005-5wt.% of inert particles 0.3-1.2mum in mean diameter (e.g. calcium carbonate particles) are dried at 170 deg.C for 3hr and fed to a hopper followed by an extruder where the pellets are melted at 280-300 deg.C and extruded via a 1mm slit die onto a rotary cooling drum with a surface temperature of 20 deg.C into an undrawn film, which is, in turn, drawn between a low-speed roll and a high-speed roll and then further drawn transversely using a tenter, thus obtaining the objective polyester film excellent in cut and scratch resistances. |
