| 摘要 |
PURPOSE:To balance heat resistance, optical property and lateral and longitudinal mechanical properties of a tubular oriented film having 10% or lower of crystallinity by reheating the film at 60-140 deg.C, and then orienting by 4-36 times of area magnification. CONSTITUTION:Tubular unoriented polyether ketone film which is melted, extruded from an annular die and cooled to have 10% or less of crystallinity is continuously fed to between feeding and drawing nip rolls. The film is reheated at 60-140 deg.C from the circumferential direction in the meantime, expanded by internal pressure, and biaxially oriented simultaneously so that the area magnification becomes 4-36 times. The orienting temperature is preferably 80- 120 deg.C, and the orienting magnification is 9-25 times to preferably produce stable bubbles. |
