| 摘要 |
<p>SPIRALLY CROSS-ORIENTED FILM AND METHOD FOR PRODUCING SPIRALLY CROSS-ORIENTED FILM A novel spirally oriented film is produced by a novel method comprising extruding an orientable material in tubular form and longitudinally stretching the extruded tube while simultaneously axially rotating the tube to spirally orient the molecular configuration of the tube and form a spirally oriented film. Thereafter, the tube, preferably, is collapsed and internally self-welded to form a spirally cross-oriented unitary lay-flat film.</p> |
