| 摘要 |
When longitudinally stretching thermoplastics films in a stretching zone comprising at least one roll by the application of a stretching force thereto, width contraction of the film generally occurs. In the present invention, this is prevented by the improvement of directing compressed air against the film while it is passing over at least one of the rolls and is being stretched longitudinally. The compressed air emerges from nozzles distributed over the entire length of the rolls and retains the film in position on the roll or rolls, thereby preventing its width from contracting. The improved apparatus suitable for carrying out the improved method comprises nozzle means disposed adjacent to and directed towards the film located on the roll means and compressed-air supply means communicating with the nozzle means. |
