Smith & Nephew Polyfabrik Limited

James Dow

Ronald Lloyd

Albert G Patchell

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

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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Thaxted, United Kingdom

James Dow