| 摘要 |
PURPOSE: To improve the handleability, the thickness uniformity and the dielectric breakdown voltage at the time of manufacturing a film made of styrene polymer having a syndiotactic configuration by specifying the difference between the maximum value and the minimum value of its double refraction, and the mean refractive index. CONSTITUTION: Since a biaxially oriented film in which a plasticized resin containing syndiotactic styrene polymer as a main ingredient is biaxially oriented and thermally set has excellent heat resistance and electric characteristics, it is, for example, used for the dielectric material of a film capacitor. In this case, the polystyrene film is made of the styrene polymer having a syndiotactic configuration 0.01 or less of the difference (ΔnMAX-ΔnMIN) between the maximum valueΔnMAX and the minimum valueΔnMIN of the double refraction and 1.582 to 1.590 of mean refractive index. Thus, the handleability, the thickness uniformity and the dielectric breakdown voltage are obtained while satisfying the thickness reduction of the dielectric material required for the reduction in size and the increase in its electrostatic capacity. |
