| 摘要 |
PURPOSE:To prevent the bowing phenomenon from occurring by a method wherein a film, after being stretched longitudinally, is stretched laterally until 10-90% of total percent of lateral stretch is reached and thermally set and finally stretched laterally to realize 100% of total percent of lateral stretch while running the film in the reversed direction. CONSTITUTION:A fusion-extruded thermoplastic resin film is at first longitudinally stretched. Secondly, the film is laterally stretched by holding both ends of the film until 10-90% of total percent of lateral stretch is reached and thermally set. Thirdly, the running direction of the film is reversed and the film is laterally stretched by holding both its ends until 100% of total percent of lateral stretch is realized while running in the direction opposite to that during said lateral stretching and thermal setting and finally thermally set again at a temperature higher than said thermally set temperature in order to obtain a biaxially stretched thermosetting resin film with uniform physical proterties. In addition, fusion-extrusion conditions, casting conditions, stretching conditions in the machine direction and in the width direction, all of which are well-known conditions, can be employed, as a film forming and a stretching conditions. |
