| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a biaxially oriented polyester film suitable as a base film for a high-density magnetic recording medium which can have a very low humidity expansion coefficient, and a magnetic recording medium using the same. Ž<P>SOLUTION: In the biaxially oriented polyester film, at least one film layer contains (1) a polyester copolymer and (2) a polyolefin having a melting point in the range of 200 to 280°C in a proportion of 60:40 to 95:5 in weight ratio. The polyester copolymer is a polyester comprising an aromatic dicarboxylic component and a diol component, wherein (i) the dicarboxylic component contains ≥5% by mol and <50% by mol of 6,6'-(alkylenedioxy)-di-2-naphthoic acid component and >50% by mol and ≤95% by mol of another aromatic dicarbxylic acid, and (ii) the diol component contains 90 to 100% by mol of a 2-10C alkylene glycol. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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