| 摘要 |
PURPOSE:To provide a film band free from wrinkling due to themal expansion, stretched in a longitudinal direction and a transverse direction in a range from a degree equivalent to the coefficient of linear thermal expansion in a specified temperature range intrinsic to the material constituting the film to a specified percent. CONSTITUTION:A synthetic resin film band free from thermal expansion which is treated by either a calendering method or a T-die method and is formed by stretching in the longitudinal direction and the transverse direction in the range of from a degree equivalent to the coefficient of linear thermal expansion in the temperature range of 50-120 deg.C intrinsic of the material constituting the film to 6% of the dimensions of the film band. For example, a film band F wound in a roll form is heated by feeding along a peripheral surface of a metallic roller 10 heated to 50-120 deg.C, is transferred onto a flat belt conveyor 11 moved at a velocity equal to the circumferential velocity of the roller 10 or lower than the latter by about 7% thereof, both side edges of the band F are sequentially fixed onto the conveyor 11 by press belts 13, 13, the band F is cooled to normal temperature by bringing it into contact with a cold air flow and a cooling medium in a cooling tank 14, and a fil band Fo free from thermal expansion is taken up. |
