| 摘要 |
PURPOSE:To obtain a film improved in longitudinal tearability and being side and super-thin even at a low draw ratio, by uniaxially stretching a preheated stock vinylidene fluoride resin film by means of two pairs of pinch rolls of a roll distance smaller than a specified value. CONSTITUTION:A stock vinylidene fluoride resin film preheated with a preheating roll 2 is fed to two pairs of pinch rolls 3, 3' and 4, 4', oriented uniaxially, annealed with an annealing roll 5 and wound around a take-up roll 6. The distance between the two pairs of rolls 3, 3' and 4, 4' is adjusted so that it is at most 1/8 of the width of the film. In this way, the change in the width of the film can be decreased, and a stress can be produced not only in the machine direction but also in the transverse direction. Therefore, the film can be biaxially stretched at the same time, the longitudinal tearability of the film can be improved, the volume change is remarkable in the direction of thickness due to restriction in the direction of width, and therefore it becomes possible to obtain a wide and super-thin film even at a low draw ratio. |
