BIAXIALLY ORIENTED POLYESTER FILM FOR MAGNETIC RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To obtain a biaxially oriented polyester film for magnetic recording media having flat surface, excellent in lubricating property, scratch resistance and traveling durability and useful as a high-density recording base film, especially a thin base film for long time recording. SOLUTION: This polyester film contains 0.01-2.0wt.% particles having <=0.05μm average primary particle diameter and <5 average aggregation degree and 0.005-0.1wt.% inert particles having 0.2-0.8 average particle diameter and has >=0.4 and <=0.7 dichromatic index of peak which appears between 1300-1050cm<-1> derived from expansion and contraction of ester group of infrared absorption spectrum.