| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a biaxially-oriented polyester film hardly causing change in dimensions as a magnetic recording medium even with change of the environment, which has superior storage stability, and which is superior in a slit property and a winding posture. <P>SOLUTION: The biaxially-oriented polyester film has a laminated structure of at least two layers including a C layer configuring one surface, wherein the wave center line waviness of the C layer side surface is 0.5 nm or more and less than 10 nm, the air leakage index when the C layer side surface and the surface on the opposite side thereof are overlapped is 3,000-6,000 seconds, the humidity expansion coefficient in the width direction is 0-6 ppm/%RH, and n_bar((nMD+nTD+nZD)/3) indicated by an average of a refractive index nMD in the longitudinal direction, a refractive index nTD in the width direction, and a refractive index nZD in the thickness direction is 1.590-1.680. <P>COPYRIGHT: (C)2013,JPO&INPIT |
