| 摘要 |
<p>A digital recording medium having a non-magnetic support made of a polyethylene naphthalate film which is prepared by stretching the film in a longitudinal direction, coating the film with a coating liquid containing a lubricant before stretching in a transverse direction, stretching the coated film in a transverse direction and heat setting the film without restretching in a longitudinal direction and which has at least 800 kg/mm<2> of a Young's modulus in the longitudinal direction of the film; at least 700 kg/mm<2> of a Young's modulus in the transverse direction of the film; 0.008 mu m or less of a center line average roughness on the smooth surface of the film; and the number of protrusions having a height of at least 0.27 mu m on the smooth surface of the film which is measured by a multiple interference method, the recording medium having good electromagnetic conversion properties, running durability and being suitable for long-time recording.</p> |
