| 摘要 |
1,035,471. Hot stretching polyolefine filaments. COURTAULDS Ltd. Nov. 7, 1962 [Nov. 8, 1961], No. 39941/61. Heading B5B. The tenacity of a polyolefine filament, particularly a polypropylene filament containing a major proportion of isotactic polypropylene, is increased by stretching it while it is passing through a zone of a gas which is at a temperature above the melting point of the polyolefine, the filament being in contact only with the gas in the zone, and the conditions employed being such that the degree of opacity of the filament material is not substantially increased by the process. The gas normally used is air and may be at a temperature of 180-300‹ C. and the draw ratio may be 8 to 13. The stretching may be carried out in a single zone or in two successive zones each containing a gas which is above the melting point of the polyolefine. The conditions of heating and stretching are such that the stretched filament is bright and of uniform denier. The upper limit of the draw ratios is about 14: 1. The gas may be contained in an electrically heated metal box the closed ends of which have slots to allow the passage of the filament.
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