| 摘要 |
1,046,926. Drawing polypropylene yarn. HERCULES POWDER CO. June 18, 1964 [June 18, 1963], No. 25285/64. Heading B5B. Stereoregular (i.e. isotactic) polypropylene yarn is drawn between a heated feed roll (with which is associated an idler roll or guide bar spaced apart from and canted slightly with respect to the feed roll to prevent overlapping of yarn wraps on the feed roll) and a draw roll and heat is supplied to the yarn as it travels between the feed roll and its associated idler roll or guide bar (which may also be heated) to prevent any decrease in the temperature acquired by the yarn during its passage over and in contact with the feed roll. Heat may be supplied to the yarn as it travels between the feed roll and the idler roll or guide bar by slidably contacting the yarn with a smooth heated platen or by enclosing the feed roll and the idler roll or guide bar within a heated enclosure in which the temperature of the environment of the yarn is maintained at the same level as that of the feed roll. Alternatively heat may be supplied to the yarn by means of radiant heaters installed in the vicinity of, but out of contact with, the yarn as it travels between the feed roll and the idler roll or guide bar.
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