GB1349019A - Dry spinning process for fibreforming polymers - Google Patents

Abstract

1349019 Dry-spinning process E I DU PONT DE NEMOURS & CO 18 Oct 1971 [19 Oet 1970] 48405/71 Heading B5B A process for dry-spinning textile filaments from a spinning solution of a fibre-forming polymer in a solvent comprises passing the solution through a spinneret assembly wherein air is removed from the said assembly before the solution is passed therethrough by replacing the air with a gas which is more soluble than air in the spinning solution. The polymer may be a "Spandex" (Registered Trade Mark) polymer, defined as a long chain synthetic elastomer comprised of at least 85% of a segmented polyurethane, an aromatic polyamide, or an acrylonitrile polymer. The term acrylonitrile polymers includes homopolymers and polymers containing at least 85% by wt. of acrylonitrile units, with suitable comonomers. Specified spinning solvents include dimethyl formamide and dimethylacetamide, and the gas more soluble than air must not be unduly corrosive to equipment, should not be toxic for safety reasons and must be inert in the solution to be spun. For solutions of acrylic or spandex polymer in dimethyl formamide or dimethylacetamide carbon dioxide is the preferred gas. Nitrogen is less soluble than air in solutions of acrylic polymer or spandex polymer in dimethyl formamide and dimethylacetamide, and is not a suitable gas according to this invention for replacement of air in spinneret assemblies or spinning fibres from a solution. Oxygen is not inert to the solution to be spun. Desirably, at starting, the solution to be spun through the spinneret should be at as low a temperature as convenient. This result is thought to be due to the increase in solubility of the soluble gas in the solution at lower temperatures. The dry spinning apparatus shown may be used. As shown, spinning solution is delivered to conduit 1 which passes through heating chamber 3. Heat transfer fluid enters chamber 3 through passage 5 and exits through passage 7. Spinning solution from conduit 1 flows through the spinneret assembly consisting of pack body 9, filter pack 11, distributer plate 13, spinneret 15, retainer plate 17, bolt 19, and threaded ring 21. Hot gas from a source not shown is delivered through conduit 23 to gas distributer chamber 25 which is insulated from the heating chamber as shown and from which it flows through turbulence suppressing means consisting of perforated plate 27 and screen 29 to contact the filaments in the spinning cell. The filaments lose the bulk of the solvent to the hot, evaporative medium as they progress through the spinning cell (not shown) position below Fig. 1, and are withdrawn at a carefully regulated speed for subsequent processing.