| 摘要 |
<p>PURPOSE:To provide the title film useful as a base film of a magnetic recording medium capable of long-time recording and high-density recording, especially an 8mm videotape, a digital audiotape (DAT) or a digital compact casette (DCC) tape. CONSTITUTION:A biaxially oriented polyethylene 2,6-naphthalate film having surface protrusions of a height distribution of the formula I: [wherein h (nm) is the height of a protrusion], satisfying formula II (wherein NS is the coefficient of plane orientation, and na is the average refractive index) and having a surface roughness Ra of 2-10nm and a heat shrinkage in the machine direction of 0.08% or below when heated at 70 deg.C for 1hr without load.</p> |
