ES474978A3 - A procedure for manufacturing staple fibres and high-strength, high-crimp rayon filaments. - Google Patents

Abstract

This invention's procedure for manufacturing high-crimp and high-strength rayon fibres consists of spinning a modified viscose spinning solution, of the type described in the cited patent request US no.473321, into a coagulating-type spin bath at a temperature of 18 degree to 40 degree C to obtain incompletely regenerated, coagulated viscose filaments. The coagulated viscose filaments are withdrawn from the spin bath and, while the filaments are still substantially soluble in dilute alkaline solution, they are stretched from approximately 150 to 180 percent in length and, at the same time, the filaments are treated with a hot dilute acid bath to partially regenerate the filaments. The tension of the filaments is then relaxed approximately 20 to 60 percent, while the filaments are less than 50 percent regenerated; the relaxed and partially regenerated filaments are treated with an alkaline solution having a pH of from approximately 7.5 to 10. The alkaline solution is, advantageously, a dilute aqueous solution of sodium carbonate, sodium bicarbonate or sodium hydroxide and the filaments are treated with this solution for a period of time and at a temperature ranging from approximately 2 seconds at 100 degree C to approximately 120 seconds at 20 degree C. On completion of the alkaline treatment, the regeneration of the filaments is completed by conventional procedures, without additional stretching. The completely regenerated filaments are then desulphurised and washed in the usual manner. Alternatively, on completion of the acid regeneration treatment, the filaments can be cut into staple fibres and these staple fibres then desulphurised and finished as described. The resulting filaments or staple fibres have between 12 and 35, and normally more than 10, crimps per centimetre in the relaxed condition, a conditioned tenacity of greater than 3 g.p.d., a wet tenacity of greater than 2 g.p.d., and a wet modulus of greater than 0.4 g.p.d.