| 摘要 |
<p>Polypropylene bracelets are made fom extrusion-blown tubing cut into hoops which are twisted after being drawn. Pref. film is 0.03-0.1, esp. 0.05-0.06 mm thick stretched at a temp, between ambient and 40 degrees C to a draw ratio of >4, pref. in the range 5-7, so that the flattened film is 15-50, pref. 20-50 mm wide, cut into segments 10-60 mm long, and stretched to a flattened length of 7.5-35 cm with a tensile strength of at least 6 kg typically 10-14 kg. More efficient than mfr. from longitudinally drawn extruded tape. Convenient for producing bracelets of similar dia. in a variety of widths.</p> |
