GB1081379A - Process for spinning polyamide filaments - Google Patents

Abstract

1,081,379. Polyamide filaments. E. I. DU PONT DE NEMOURS & CO. Dec. 23, 1965 [Dec. 23, 1964], No. 54620/65. Heading B5B. A process for preparing an undrawn, low birefringence polyamide yarn which comprises extruding a molten, synthetic fibre forming polyamide in the form of filaments, cooling the filaments and contacting the filaments with steam, is characterized by cooling the filaments to a temperature at least 15‹ C. above the forceto-draw transition temperature of the filaments and low enough to at least partially solidify the filaments, contacting the filaments with steam for a period no longer than 0À02 seconds and forwarding the said filaments from the contact with steam. Preferably the filaments are cooled to a temperature between 25‹ and 40‹ C. above the force-to-draw transition temperature of the said filaments, and are contacted with steam, preferably at a temperature above 100‹ C., for a period of from 0À004 seconds to 0À018 seconds, and are then forwarded to wind up. Thus, in Fig. 1, filaments 1 freshly extruded from spinneret 2 pass into cooling chimney 3 where they are contacted by cross flow air 4. Convergence guide 5, adjustable in position to assist control of filament temperature, leads the filament, at the desired temperature out of chimney 3 and into steamer 6 where a cross flow of steam 7 contacts the still hot filaments. The filaments in the undrawn condition are thereafter passed by suitable guides 8 on to a package 9. The duration of steaming may be varied by using steamers of various lengths, and the yarn temperature as it enters the steam zone may be varied by changing the steamer location relative to the spinneret and by converging the filaments with an additional guide at various locations in the chimney (the rate of cooling being decreased by converging the filaments). Yarns so made exhibit a low. orientation in the undrawn state, as indicated by low birefring- ence, and consequently may be drawn at a high draw ratio to produce yarn of the same tenacity and elongation as conventional yarns prepared at a lower draw ratio. Hence the undrawn yarn denier may be increased without affecting the final yarn denier and the productivity of the spinning unit is thereby increased. Yarns so made are also found to dye more deeply under the same conditions than do conventionally processed yarns. Examples are given.