| 摘要 |
PURPOSE:To enhance the smoothness of a polycarbonate film by making the surface speed of a pinch roll faster than that of a film flattening apparatus and holding the temp. of the polycarbonate film passing between the film flattening apparatus and the pinch roll to a specific range. CONSTITUTION:A polycarbonate resin is extruded from an annular die in a molten state and a bubble is formed by compressed gas to be flattened by a variable speed film flattening apparatus and continuously introduced into a pair of taking-up pinch rolls. At this time, an apparatus making the surface speed of the pinch rolls faster by 1-30% than that of the film flattening apparatus is used and a blow-up ratio is held to 0.8-3.0 times and the temp. of the film passing between the film flattening apparatus and the pinch rolls is held to 120-170 deg.C. By this method, a polycarbonate film having homogenous mechanical properties in longitudinal and lateral directions, no wrinkles or sag and having good smoothness can be obtained stably and continuously. |
