| 摘要 |
In producing thermoplastic tubular films, the plastic is initially extruded into a tube, the tube is inflated to form a film bubble and the film bubble is cooled and laid flat with two longitudinally running folded edges to form the tubular film. To avoid weakening in strength along the folded edges, the film bubble is cooled before the frost line, in the region of the folded edges to be formed, by contact cooling to a temperature of at least 60 DEG C below the crystallite forming range of the thermoplastic material. For this purpose, rotatable rollers through which a coolant flows and which bear against the film bubble are used. |
