| 摘要 |
PURPOSE: To eliminate the wrinkle and unevenness by absorbing moisture to a film to set a moisture content higher than a target moisture content, and then lowering the content by drying to set it to the target content. CONSTITUTION: The water absorbing velocities of a film have difference in thickness directions. A surface layer part arrives at a high water content in a short time in the moisture absorbing step, and arrives at a low water content similarly in a short time in the drying step. On the other hand, at the center, since it takes a time to diffuse water molecules to the surface layer part, the change of the content is smooth. Thus, after it is once set to the higher content than the target content, then dried to set to the target content, and hence the water content in the thickness direction becomes uniform, and hence the distortion is suppressed. As a result, the longitudinal dimension change rate and the surface external appearance change are extremely reduced, no wrinkle and no unevenness occur at the film. Even if removing and rewinding which have heretofore been conducted are eliminated and the productivity is remarkably improved. |
