POLYESTER FILM FOR MAGNETIC RECORDING MEDIUM AND IDENTIFYING METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a polyester film for a magnetic recording medium wherein it can be easily identified that the polyester film for the magnetic recording medium is formed by using a recycled resin and which has the same quality as the polyester film consisting of dimethyl terephthalate produced from para- xylene and to provide an identifying method therefor. SOLUTION: The polyester film is provided wherein a magnetic material coating surface of it has <=10 nm central platen average roughness, and dimethyl terephthalate constituted of an isotope of carbon or/and hydrogen is added by 1-500 wt.ppm to dimethyl phthalate as an identification compound. The identifying method of the polyester film is also provided.