| 摘要 |
PURPOSE:To obtain a magnetic tape which is thin, has excellent running characteristics, and is free from distortion in recording, by using a film which is a biaxially-oriented polyester film having a specific repetitive unit as specific mol% or above and has specific property values as a substrate. CONSTITUTION:The ethylene bis alpha,beta-(2-chlorophenoxy)ethane 4,4'-dicarboxylate which is polyester contg. >=85mol% the repetitive unit expressed by the formula (X is F, Cl, Br or C1-3 alkyl, l, m are respectively 1-2, p is 2-6, q is 2-4) wherein more particularly l=m=1, p=q=2 is biaxially oriented to form a film of which the Young's modulus in at least one direction is >=550kg/cm<2>, the thermal shrinkage in the Young's modulus direction is <=4%, the intrinsic viscosity is 0.3-1.4, the refractive index ratio in the thickness direction of the film is 0.935-0.975 and the density index is 0.01-0.09 as a substrate. A magnetic layer is formed on such substrate. The magnetic tape which has good running characteristics and is entirely free from distortion in recording is thus obtd. even from a thin tape of about 0.6mu. |
