| 摘要 |
A film based on thermally unstable, thermoplastic materials, the film being formed on a calender at a temperature below the thermoplastic range and subsequently subjected to a heat treatment involving heating the film up to the thermoplastic range of the plastic used, is obtained by the film being oriented under tensile stress during the heat treatment, the tensile stress being set such that an elongation of the film of at least 25 per cent to 50 per cent is achieved. An apparatus for producing an oriented film based on thermally unstable, thermoplastic materials is also described. This apparatus is characterised in that a calender (k) for producing the film (K) is provided and is followed directly downstream by at least one melt cylinder (17 to 112), in that furthermore take-off rolls (113 to 115) are provided, which draw the film off the melt cylinder or cylinders at an increased rate, it being possible in each case for a further downstream melt cylinder to serve as the take-off roll. <IMAGE> |
