| 摘要 |
A twisted polypropylene ring for packaging purposes with a transverse length of 7.5 to 35 cm and a tensile strength of at least 6 kg is produced by first of all blow moulding polypropylene to form a tube of approximately 15 to 50 mm diameter and approximately 0.03 to 0.1 mm strip thickness. This tube is then either first cut up into individual rings of approximately 10 to 60 mm length which are stretched transversely to their longitudinal axis to a stretch ratio of at least 4 and twisted, or else the tube is first stretched transversely to its longitudinal direction to a stretch ratio of at least 4 and then cut up into individual rings of approximately 10 to 60 mm length which are then twisted. <IMAGE>
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