| 摘要 |
PURPOSE:To obtain the titled film which reduced coefficient of friction without need of back coating, excellent in output characteristics when used as a magnetic recording medium, thus suitable for magnetic tapes, by incorporating a polyester with inert inorganic particles so that the surface roughness of the resulting film fall within a specified range. CONSTITUTION:(A) A polyester constituted mainly of ethylene terephthalate unit is incorporated with (B) pref. 0.3-1.5wt.% of inert inorganic particles (e.g. of synthetic calcium carbonate) to make into the objective biaxially oriented film. This film has the following characteristics: 1, depth Rp from the maximum peak to the centerline in the standard length section in the surface roughness curve 60-190nm, 2, ratio of Rp to the average surface roughness on the centerline 4-25, 3, average interval between asperities <=20mum, 4, degree of acumination of the asperities with 30-100nm in height >=0.08. |
