Abstract: A film of synthetic polymer is profiled with a pattern of thick and thin areas so that it can split on stretching into a net; additionally the thin areas are likewise profiled so that either the strands of main net split clearly apart or the orifices of main net are covered by an integral fine net arising from the minor profile. Profiles based on the intersection of sets of parallel grooves on opposite surfaces are preferred for both major and minor profiles.

Abstract: A net formed integrally of blended incompatible polymers, with parallel smooth longitudinal ribs interconnected by a plurality of split strands non-uniformly interspersed with a plurality of differently sized voids, by stretching a film with a generally longitudinal set of parallel primary grooves and a transverse or angled set, on the other surface, of parallel secondary grooves.

Abstract: An extruded sheet or the like of cold-drawable polymer such as polypropylene is embossed as a molten sheet by a circumferentially multi-grooved roller and stretched in the direction of the embossed grooves to split into filaments along the grooves.

Abstract: A melt-embossed polymer film with primary parallel grooves on one surface and secondary parallel grooves on the other surface such that the combined tapes of the grooves is at least substantially equal to the film thickness, the two sets of grooves being located at an angle to each other of not less than 30.degree., is stretched at right angles to the direction of the primary grooves by a small amount to give a perforate product which can be formed into strips tearable longitudinally or transversely and thus useful as a vapor-permeable substrate for adhesive-coated tape.

Abstract: A non-woven fabric is produced by stretching the film with on one surface a regular pattern of raised areas such as spaced hexagonal bosses and on the other surface a plurality of parallel grooves. Stretching is carried out in the groove direction. Preferably the polymer is a mixture of incompatible polymers so that on stretching a fibrous structure is formed. The film can be produced by melt-embossing. The stretched non-woven fabric may be coated with various adhesives to provide a tape useful in a medical context.