Smith & Nephew Plastics Limited

Smith & Nephew Polyfabrik Limited

Other

Smith & Nephew, Inc., Research

Albert G Patchell

Ronald Lloyd

William O Murphy

Peter J Herbert

James Dow

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.

Production of net from synthetic polymeric film

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.

Embossed film product and adhesive coated strip formed therefrom

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.

Net-like product produced by stretching a film composed of two

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.

Production of filaments

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.

Polymer fabric

Interconnected fibres banded by cross-sectional orientation and morphology differences, in an array which can be bundled up to separate the fibres at least partially. A thermoplastic sheet emboding areas of different degrees of fibrillation is cold drawn to initiate longitudinally extending cracks in the areas of lower resistance to fibrillation such that the cracks terminate at the areas of higher resistance to fibrillation. The sheet is then further drawn at a higher temperature to open the cracks and to cause the cracks to propagate through the areas of higher resistance to fibrillation. Both drawing steps are performed without lateral extension.

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Welwyn Garden City, United Kingdom

Albert G Patchell