Patent ID: 6607822
Filing Date: 2003-08-19
Classification: B32B,C08J,G11B,Y10T

Abstract:
An at least single-layer, biaxially oriented film support for magnetic recording media which is predominantly composed of crystallizable polyester, having a thickness in the range from 1 to 40 &mgr;m, wherein the film has, over its total roll length and roll, width and after it has been made up into customer rolls, an electrostatic charge build-up which is in the range from about âˆ’80 kV/m to about +80 kV/m, being made by a process wherein which the molten polyester material is extruded through a slot die and quenched as a substantially amorphous prefilm on a chill roll, this film is then heated up again and is oriented in the longitudinal and transverse direction or in the transverse and longitudinal direction or in the longitudinal direction, in the transverse direction and again in the longitudinal direction and/or transverse direction, the orientation temperatures being set at values of about Tg+10 K to about Tg+60 K, the stretching ratio of the longitudinal stretching being set to a value in the range from about 2 to about 6, that of the transverse stretching being set to a value in the range from about 2 to about 5, and that of any second longitudinal stretching carried out being set to a value in the range from about 1.1 to about 3, and in which thereafter heat setting of the film is carried out at oven temperatures of from about 200 to about 260Â° C. and the film is then cooled and rolled up, wherein the rolled-up film is then wade up on a make-up machine at speeds in the range from about 300 to about 400 m/min and wherein the make-up procedure is carried out using winding tensions in the range of 90 N/m to 200 N/m and contact pressures in such a way that the contact pressure is set in the range from about 300 N/m to about 350 N/m.