| 摘要 |
962,231. Heat-treatment of polyamide, polyester and polyolefin fibres. CANADIAN CELANESE Ltd. Feb. 7, 1962 [Feb. 7, 1961], No. 4596/61. Heading B5B. Melt-spun fibres of polyamides, polyesters or polyolefins are subjected to a dry heat-treatment at a temperature short of the melting temperature under such conditions that shrinkage of the fibres occurs. Heat-treatment may be effected at from 75‹ C. to 10‹ C. below the melting point of the polymer. Heat-treatment may be effected with continuous filaments or cut staple fibre in the loose state, e.g. in an oven. Polypropylene containing at least 70% of the isotactic form and preferably about 85% may be melt-spun to form filaments, the filaments subjected to a draw-down from the spinning jet of at least 20 times, preferably as much as 25-200 times, and then, without stretching, heat-treated, suitably at 85- 145‹ C., by means of hot air, infra-red or dielectric heating, or direct contact with a heated metal surface. The treatment increases the elastic recovery of the fibres.
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