POLYESTER FILM FOR LEADER TAPE AND PROCESS FOR PRODUCING THE FILM

摘要

A polyester film that can provide a leader tape wherein the surface unevennesses of the etched part are minute and uniform and which is excellent in appearance, does not cause magnetic tape troubles, and has a high commodity value; and a process for producing a polyester film that can provide a leader tape having an arbitrary thickness distribution pattern with a good reproducibility, that can provide a leader tape wherein the surface unevennesses of the etched part are minute and uniform and which has an excellent appearance and a high commodity value, and that can further provide a leader tape having various thicknesses at a reduced production cost because it enables a number of working runs at once. This film is produced by contacting a polyester film with an alkaline liquid to etch at least one side of the film to give rise to thickness distribution. The production process is characterized by suitably controlling the extent of etching site by site to realize any arbitrary thickness distribution. Preferably the etching is conducted by immersing the film in an alkaline liquid.