COMPOSITE POLYESTER FILM FOR MAGNETIC RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To provide a base film for digital video tapes which has the good applicability of a magnetic metallic layer, is strong and has good electromagnetic conversion characteristics and durability. SOLUTION: This composite polyester film for magnetic recording media is the composite polyester film formed by laminating a layer A consisting of polyester into which particulates are incorporated and a layer B consisting of the polyester into which the particulates are incorporated. The SRA value of the outside surface of the layer A is 2 to 9nm and the SRa value of the outside surface of the layer B is 10 to 50nm. The number of the surface projections of >=270nm height and the total number of surface flaws on the outside surface of the layer A are <=45 pieces/100cm<2> . The outside surface of the layer A is a surface to be provided with the magnetic layer. This magnetic tape is constituted by providing the layer A side with the coating type magnetic metallic layer.