| 摘要 |
<p>A magnetic recording medium comprises a stretched film comprising a styrene copolymer having a highly syndiotactic structure of the compsn. thereof or a laminated film comprising the stretched film. A magnetic layer is applied to at least one surface of the base film which has a coefft. of linear expansion of smaller than 5x10power(-5)/C and a static frictional coefft. of 0.1-1.0. Also claimed are: (1) a thermoresistant magnetic tape comprising above mentioned stretched film and a magnetic layer located at one side of the base film which has elasticity (at room temp.) in both machine direction (MD) and transverse direction (TD) of more than 30,000kg/cm2 each, the ratio of of elasticity in MD to that of TD of more than 1.8, elasticity in MD at 90 deg. C of more than 10,000 kg/cm2, coefft. of linear expansion at 0-90 deg. C of smaller than and 5x10power(-5)/deg. C and surface smoothness Ra of 0.001-0.03. (2) a magnetic disc, wherein the base film has a coefft. of linear expansion in MD (2MD) or TD (2TD) of smaller than 5-10power(-5)/ deg. C, the ratio of 2MD/2TD of 0.3-3, same Ra as in (1), and thickness of 20-200 m; and (3) a magnetic card, wherein the base film has a coefft. of linear expansion of smaller than 7-10power(-5)/deg.C whiteness of more than 75 and thickness of 500-1000 micron.</p> |
