Endless synthetic filaments of acrylic nitrile polymers and continuous process for their manufacture, and apparatus for the execution of the process and use of the filaments for the manufacture of non-textile surfaces

摘要

1,090,478. Synthetic filaments. MONSANTO CO. May 21, 1965 [May 21, 1964; July 27, 1964], No. 21641/65. Heading B5B. [Also in Division D2] Continuous synthetic filaments suitable for paper-making and other non-woven products are comprised of a multitude of loosely bonded fibrils having highly porous cross-sections, said pores comprising greater than 50% of the area thereof. Such filaments which are preferably of 40-80 deniers, may be made by preparing a slurry comprised of acrylonitrile based polymer dispersed in an aqueous solution containing a water soluble cellulose derivative, heating the slurry under pressure to convert same into a " viscous melt ", (actually a two-phase watermelt system) extruding the viscous melt through a plurality of orifices into a restricted area, and directing a high velocity stream of steam transversely against the extruded melt to form filaments. Preferably a slurry based on a polymer comprising at least 80% acrylonitrile, 0-10% vinyl acetate and 0-10% of at least one other unsaturated monomeric compound. copolymerizable therewith (styrene is preferred but many others are listed) is heated to 130-150‹ C., in a first heating zone, advanced through a second heating zone in which it is heated to 150-205‹ C. to form the " viscous melt ", the melt extruded horizontally and the high velocity stream of steam directed vertically downward against the extruded melt to form continuous filaments having crosssections characterized by cavities and fissures. Desirably, the polymers are comprised of 93% acrylonitrile and 7% vinyl acetate, the cellulose derivative is sodium carboxymethyl cellulose the slurry has 2-30% polymer solids, and the sodium carboxymethyl cellulose comprises 6- 18% of the polymer solids. In the apparatus of Fig. 1, the slurry, heated under pressure, passes through pipe 26 and spinneret plate 20, which has a plurality of obliquely-drilled orifices (Fig. 2, not reproduced) into the passage 19 where it meets a jet of steam entering at 30. The steam assists the flashing of the water contained in the slurry, and the filamentary structures formed, which pass through the restricted passage 16, have the form described above, and shown in Fig. 6 (not reproduced). Fig. 3 shows an alternative form of apparatus. The polymer composition is supplied via 43 to the chamber 42 and passes through obliquely-drilled holes 50 in the tubular spinneret 44 toits interior, where the extruded melt meets a jet of steam supplied via 54. The filaments pass through the restricted passage 58 and their form is similar to those obtained using the apparatus of Fig. 1. Paper may be made by collecting the tow, cutting into half-inch staple lengths, slurrying with water and beating. When sufficient fibrillation has occurred the sample is transferred to a sheeting machine. A soft batt may be made by subjecting the cut staple to a longitudinal scraping action, e.g. by carding to develop a fibrillous batt which can be matted to make a soft batt.