Improvements in or relating to the production of filamentary materials of high tenacity

摘要

Cellulose organic ester filamentary textil materials, e.g. filaments, yarns, tow and ribbon, of improved tenacity, are produced by extruding a solution of the cellulose ester, e.g. a solution of cellulose acetate, propionate, butyrate, acetatepropionate or acetate-butyrate in acetone, ethylene chloride or a mixture of methylene chloride and ethyl alcohol or of chloroform and methyl or ethyl alcohol, and setting the shaped material in such a way that it contains substantially more than 1 per cent of its weight of solvent, then reducing the solvent-content to less than 1 per cent by weight, by passing a fluid capable of removing the solvent and inert with respect to the cellulose derivative through a loose mass of the material, and finally stretching the so-treated material. The fluid may be air or other gas or a liquid miscible with the solvent and may contain a small proportion of the solvent. Following the stretching operation, the materials may be saponified, e.g. with aqueous sodium hydroxide, sodium carbonate or ammonium hydroxide. A tow of stretched material may be breaker-drafted to produce a sliver of staple fibres, the sliver twisted to a roving and the roving saponified as described in Specification 667,147. As applied to cellulose acetate threads, the thread is collected from the spinning cell in a sliver-can 14 (Fig. 6) provided with a perforated base. The filled cans are then mounted on a chamber 18 (Fig. 2) provided with a perforated upper wall 21, and air is drawn through the can by connection of conduit 23 to an exhaustion solvent recovery system. The threads are then withdrawn from the cans (Fig. 3) and passed through a stretching chamber 26, which may be of the type described in Specification 570,588, and contains steam under elevated temperature and pressure. The threads are again collected in sliver-cans 14 and the filled cans mounted between caps 32, 33 (Fig. 4). Saponifying liquid, e.g. aqueous sodium hydroxide containing sodium acetate at 60 DEG C., from a tank 37, is forced upwardly through the cans by a pump 36. The material is then washed with water introduced at 49 and discharged at 52. Finally, drying is effected by drawing air through the mass in the cans.