| 摘要 |
PURPOSE:To obtain a heat-treated film with favorable flatness and high rolling quality by a method wherein the widthwise tensile force is given to the film by holding both sides of the film by the specified nip force with nip rolls. CONSTITUTION:A stretched thermoplastic resin film 1 is heated by rolls 2 and 3, given thermal relaxation by a difference in the speeds of rolls 3 and 4, cooled by a cooling roll 5 and finally rolled up. In the relaxation zone between the rolls 3 and 4, cross guiders consisting of nip rolls 6 and 6', which hold both the ends of the film, are provided between the rolls 3 and 4 in order to suppress developed longitudinal wrinkles. The rolling axis of the nip roll is tilted to the width direction of the film by an angle of 5-30 deg.. A force normal to the rolling axis, the widthwise component of which acts to pull the film in the width direction, is given to the running film. It is necessary for the nip force (F:kg) of the nip roll to satisfy the formula (1) in order for the nip roll to fully shows its pulling action. |
