BIAXIALLY ORIENTED POLYETHYLENE TEREPHTHALATE FILM

摘要

PURPOSE: To obtain such a film suitable for a base film of a digital video magnetic tape that has high resistance against cutting in the production process or in a VTR, is inexpensive and has good electromagnetic conversion characteristics and off-tracking characteristics. CONSTITUTION: This film consists of a polyester containing >85mol% ethylene terephthalate in the repeating unit. The film has 3 to 8μm total thickness and>=300kg/mm<2> modulus of elasticity (A) in the width direction and the difference B-A between (A) and the modulus of elasticity (B) in the longitudinal direction is >=200kg/mm<2> . The surface roughness (Ra) of at least one surface of the film is 0.1 to 5nm, and the total thickness of the coating layer is <=2μm. The film is used as a supporting body for a coating-type magnetic recording medium for a digital video device.