BIAXIALLY ORIENTED COMPOSITE POLYESTER FILM

摘要

PROBLEM TO BE SOLVED: To provide a biaxiaxially oriented polyester film controlled in surface roughness, made excellent in abrasion resistance and having sufficiently good characteristics as a magnetic recording medium by using specific polyester. SOLUTION: In a biaxially oriented composite polyester film having at least one film layer mainly composed of polypropylene terephthalate, the film layer (A-layer) contains 0.005-1 wt.% of particles with an average particle size of 0.3-2μm and the surface roughness Ra of at least the single surface thereof is set to 5-30 nm.