Perforated thermoplastic sheet in which the perforation craters have sidewalls that present converging portions and diverging portions, a fibrous composite plane material including such a sheet, and methods of manufacture

摘要

PCT No. PCT/FR95/00915 Sec. 371 Date Mar. 14, 1996 Sec. 102(e) Date Mar. 14, 1996 PCT Filed Jul. 7, 1995 PCT Pub. No. WO96/02215 PCT Pub. Date Feb. 1, 1996The perforated sheet, in particular for sanitary articles, and made of a substance that is impervious to liquid, includes a multiplicity of craters each having a base in the plane of the outside face, an apex, and a sidewall that slopes between the base and the apex. The peripheral shape of the base includes at least one zone of discontinuity such that on going round the periphery of each crater, its sidewall presents non-uniform inclination with angles of inclination relative to the perpendicular to the plane of the outside face of the sheet that vary between positive values and negative values, said angle being negative at least in the zone of discontinuity. The peripheral shape of the base is preferably the result of partially overlapping a plurality of curved geometrical shapes, in particular circles and ellipses, and the zone of discontinuity corresponds to the junction between superposed shapes. The composite plane material includes said sheet covered in thermoplastic fibers on at least its outside face, which fibers are bonded to one another and to the sheet.