GB603827A - Improvements relating to the manufacture of artificial fibres from highly polymeric substances - Google Patents

Abstract

An improvement in or modification of the invention claimed in the parent Specification comprises the melt-spinning of the highly polymerized polymethylene terephthalate into a filament, which is then cold-drawn to form a strong, flexible fibre showing the X-ray pattern characteristic of molecular orientation along the fibre axis. The filaments may be extruded or drawn directly from the melt after the completion of the heating during which the polyester is formed, or blocks or chips of the solidified polyester may be re-melted and formed into filaments. The cold drawing may be carried out on previously formed and cooled filaments, or it may follow directly upon the filament formation as a continuous process. Any known apparatus may be used for either filament formation or cold drawing. The latter process includes warming in hot water or steam in order to facilitate stretching before or during the cold drawing operation. The preferred polyester are those with 2-10 polymethylene groups the glycols with 2-4 methylene groups give very high melting polymers, and of these ethylene glycol is preferred because of its cost and availability. In an example highly polymerized ethylene terephthalate is heated in the absence of oxygen to 280 DEG C. and extruded through a single-hole spinneret. The filament formed was cold drawn at a draw ratio of 4.7/1 to give a strong flexible fibre of diameter 0.075 mm. This fibre at 16 DEG C. and 65 per cent relative humidity possesses a tensile strength of 40.75 kg/mm2, the extension at break being 10 per cent. Specification 527,532 is referred to.