| abstract |
Biaxially drawn, advantageously filled multilayer polyester film substrates, well adapted for the manufacture of magnetic recording tapes, are comprised of a composite of at least two adjacent layers of biaxially stretched thermoplastic polyester film, at least one of the face surfaces thereof having a roughness defined by a plurality of dome and peak protuberances extending therefrom, said domes being present in a concentration of at least 5 per mm2 and having heights of at least 9/100 of one micron, the ratio of the height of such dome protuberances to the diameter of the base thereof being less than 1/100, and the ratio of the height of such peak protuberances to the diameter of the base thereof being at least 1/100. |