Method and apparatus for producing a film web from thermoplastic material and film produced thereby

摘要

The invention relates to a method and an apparatus for producing a film web made of thermoplastic material in which the thermoplastic material is extruded in at least one layer as plastic melt from a wide-slit nozzle in an extrusion direction and subsequently led away over at least roller, wherein tensile forces are exerted in the extrusion direction and transversely to the extrusion direction in order to stretch the film web longitudinally and transversely, wherein during application of the tensile forces in and transversely to the extrusion direction the film web has a temperature at least corresponding to the melting temperature of the same.

主权项

1. A method for producing a film web made of thermoplastic material in which the plastic is extruded in a layer from a wide-slit nozzle in an extrusion direction and subsequently led away over a roller, wherein tensile forces in the extrusion direction and transversely to the extrusion direction are exerted on the film web in order to stretch the film web longitudinally and transversely and wherein the layer can alternately acquire a film form or a melt form, where the film form is established during a cooling of the layer below a melting range or wherein the melt form is established during a heating of the layer above a melting range,
wherein the film web a. is initially extruded in melt form at an extrusion speed at or directly after leaving the wide-slit nozzle and b. is then guided directly afterwards in melt form to a cooling roller arrangement, wherein the film web is guided around a cooling or smoothing roller at a circumferential speed so that the film web is subjected to a longitudinal stretching, c. is subsequently guided out from the cooling roller arrangement and d. is then subjected to a transverse stretching, wherein both the longitudinal and the transverse stretching steps are carried out on the layer in the melt form so that the stretching takes place on both occasions in the form of a drawing of the melt.