BIAXIALLY ORIENTED POLYESTER FILM

摘要

PROBLEM TO BE SOLVED: To impart excellent thermal dimensional stability and tear resistance without damaging high mechanical strength capable of corresponding to the thickness reduction of a magnetic tape and to prevent the generation of a surface defect. SOLUTION: This film is a biaxially oriented film composed of polyethylene-2,6-naphthalate. The intrinsic viscosity of the whole of the film is below 0.54 and the sum of the Young's moduli in the longitudinal and lateral directions of the film is 14GPa or more and the sum of the heat shrinkage factors at a time of 150 deg./30min treatment in the longitudinal and lateral directions of the film is below 6.0% and the sum of the tear propagation resistances in the longitudinal and lateral directions of the film is set to 3.0N/min or more.