| 摘要 |
PURPOSE:To obtain a base film suitable for a high-density recording medium by using a para-type aramid film having specified film thickness, double refractive index in the material plane, Young's modulus, thermal shrinkage coefficient and surface average roughness. CONSTITUTION:The thickness of the base film is specified to >=30mum thickness, and such a para-type aramid film is used having <=0.01 double refractive index between two directions perpendicular to each other in the film plane, >=1000kg/mm<2> Young's modulus in all directions, <=0.2 thermal shrinkage coefficient at 250 deg.C in all directions, and <0.01 center line roughness (Ra) of the film surface. This film is obtd. by providing specified treatment on a PPTA polymer. Then a magnetic layer or optical recording layer comprising a metal thin film is formed on this base film by predetermined method. The obtd. recording medium is suitable for a light-weight small-size magnetic recording medium or optical recording medium. |
