| 摘要 |
1475571 Stretching polymeric ribbons BARMAG BARMER MASCHINENFABRIK AG 6 June 1974 [6 June 1973] 25201/74 Heading B5B Monoaxially drawn thermoplastic ribbons are produced by feeding an extruded film over a cutter to produce a plurality of ribbons which are drawn in at least two drawing stages above room temperature and below but adjacent the crystalline melting point, followed by heat stabilization, wherein the drawing temperature increases from one stage to the next and is dependent on the previous amount of drawing undergone by the film. The temperatures used are such that very low drawing tensions, are used, i.e. not more than 1000 ponds/mm<SP>2</SP>. The preferred films are of polypropylene drawn up to 3 x in the first stage, and heating in the final stage being provided by a combination of heated rollers and convection heating.
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