| 摘要 |
<p>Polyolefin, especially polypropylene yarn, at least partly formed of stretched continuous filaments, is crimped by subjecting the yarn to the action of a swelling agent, in the form of vapour or mist at a temperature near the boiling-point of the agent, for less than 20 seconds. Suitable swelling agents are aromatic hydrocarbons, e.g. toluene, hydroaromatic hydrocarbons, e.g. cyclohexane, decalin and tetralin, and chlorinated hydrocarbons, e.g. carbon tetrachloride, dichloroethane, tri- and tetrachloroethylene and chlorobenzene. The yarn is passed through a chamber containing the swelling agent under negligible tension. The yarn may be twisted prior to the swelling treatment, and may be heat-treated, e.g. in a steamoven, subsequent to it. The crimp obtained is 20 to 100%, preferably 30 to 45%, and is irregular. In an example, isotactic polypropylene yarn of 600 den., previously drawn 5,5 times its original length, travels in a path in the form of an acute V through a vertical cylinder, filled with trichloroethylene vapour. The top of the cylinder is open, and cooled by water, the bottom is connected to a container of boiling trichloroethylene. After an immersion time of 1 second, the yarn is of 960 den. and has a 37,5% crimp. Subsequent treatment by steam at 140 DEG C. for 1 hour stabilizes the crimp against tension.</p> |
