GB904869A - A method for the production of artificial multifilament threads from polyethylene terephthalate, and the products thus obtained - Google Patents

Abstract

<PICT:0904869/IV(a)/1> <PICT:0904869/IV(a)/2> Polyethylene terephthalate filaments of maximum titre 0,6 tex are made by melt-spinning the polymer at a temperature of at least 268 DEG C. but below that at which any substantial degradation occurs through a spinning plate held at at least 268 DEG C., the orifices in the plate being arranged in straight parallel rows, the spaces between adjacent orifices in each row being equal and at least 5,5 mm., and greater than the distances between adjacent rows, said rows being equidistant, the extruded filaments immediately after leaving the orifices being guided through a space surrounded by a closed wall of heat-insulating material and having a dimension of 7-14 cms. in the direction of movement of the filaments, and cooling gas then being passed against the filaments in a direction transverse to their direction of movement and parallel with the rows of spinning orifices at a velocity of at least 25 cms. per second, preferably at least 30 cms. per second. The filaments may be cooled by means of air or other gas at room temperature over a distance of 75-100 cms. As shown, melt is spun from a spinneret assembly 10 through orifices in a spinning plate 11. 20 is a heat-insulating member (see Fig. 3) of 7-14 cms. depth, and may be made of asbestos cement. 12 is a blow box assembly of U-shaped cross section consisting of a compartment 13, bounded by a curved side wall 15 and an air permeable filter 19, and a compartment 14 consisting of two parallel side walls, abutting wall 15, and through which the extruded filaments pass. Air or other cooling gas is supplied under slight pressure to the bottom of compartment 13 and diffuses through the filter 19, passing transversely across the compartment 14. Filaments so made are characterized by an enhanced uniformity of titre.