Process and device for the preparation of composite reticular structures

摘要

Process for the continuous preparation of open-net shaped structures comprising the steps of fibrillating a longitudinally oriented 15-200 mu thick polymeric film by passing it over pinned rollers so as to form unfibrillated oblique bands at an angle beta o of from 0.3 DEG -50 DEG with the fibrillation direction, superimposing at least two of the thus fibrillated films, transversally stretching the assembly of said fibrillated films until the unfibrillated oblique bands form an angle beta epsilon comprised between beta o and +/- 80 DEG with respect to the fibrillation direction, and thermostabilizing the open-net shaped assembly thus obtained. Expanded and/or superficially abraded films can be used in the fibrillation step, to obtain high-surface open-net structures. A device (Fig. II) is also disclosed for the transversal stretching of fibrillated films or assembly thereof, comprising feeding system (1) for said fibrillated film or assembly, a pair of diverging guides (2), each closing upon itself in a ring, clamps (3) freely sliding on said guides to grip the film or assembly at their edges, devices (4) for feeding the clamps to the guides, pulling devices (6) for engaging the clamps, moving in the feeding direction of the film or assembly, devices (13) for opening the clamps and dragging them to the feeding devices (1) and a winder (11) for the open film or assembly.