| 摘要 |
<p>Thermoplastic film material is perforated by passing the stretched film around at least a part of the surface of a roller whose surface has projections disposed in a desired pattern and maintained at a temp. sufficient to melt the film, the film being held against the roller solely by its own tension. The perforated film is used as a packaging material, esp. for foods, the perforations allowing moisture to escape. The film is perforated efficiently to give perforations of a desired size in a desired pattern. A wide range of thermoplastic film materials can be perforated. The perforation operation can be easily accommodated as part of a continuous packaging system.</p> |
