Process for producing composite reticular structures

Claim 1

Process for the preparation in a continuous run of composite open-net shaped structures, consisting of at least two superimposed fibrilled films, said process consisting of the following operations: (1) preparing a film formed of at least one synthetic polymer, having a thickness comprised between 35 and 1,200 microns; (2) prevailingly longitudinal orientation of the film by a monoaxial stretching, with longitudinal drawing ratios comprised between 4 and 15, and with the formation of an oriented film having a thickness comprised between 15 and 200μ; (3) fibrilling the film thus oriented by passing it on surfaces fitted with means for producing slits, with the formation of unfibrilled, oblique bands forming an angle β o with the direction of the slits of the film, comprised between about 0.30° and about 50°; (4) superimposing at least two films thus fibrilled with the crossing of the oblique bands of each film according to any desired angle; (5) transversal stretching of the pack of superimposed films, thereby obtaining a rotation on the plane of the oblique unfibrilled bands of each film, until said bands form with the original slitting direction, a new angle β.sub.ε with a value comprised between β o and ±80° with respect to the direction of slitting; and (6) thermostabilizing the assembly of stretched and superimposed films.