| 摘要 |
In the manufacture of regenerated cellulose fibres having a high shrinkage potential, e.g. 20-30% when immersed in boiling water with elongation at break of about 20% (wet), viscose is spun at a speed of 70-120 metres per minute through a tube immersed in a spinning bath and coaxial with the spinneret, the acidity of the bath being 120-125 grms. of sulphuric acid per litre, sodium and zinc sulphate contents 230-250 and 125-130 grms. per litre, the salt point being above 7% and the viscose being heated to the temperature of the bath immediately on the upstream side of the spinneret, and the filaments are dried under a tension sufficient to prevent shrinkage. These filaments (then having elongation at break of about 45%) are wet stretched, e.g. in a dilute aqueous bath at 85 DEG C., in one or more stages to a degree close to their elongation at break, e.g. 60-70% thereof or 30% of their original length, before or after the drying operation. On leaving the spinneret, the filaments are drawn up to 25%. The viscose or the bath may contain one or more components e.g. thiodiglycol and polyhydroxyethylenes, which promote formation of thick-skinned filaments. The filaments may be stapled by cutting or stretching to break, e.g. by the process described in Specification 774,360, [Group IX], and the filaments or staple fibre may be blended with filaments or fibres having high tenacity, low elongation and high resistance to shrinking under the action of hot water, e.g. cellulose acetate fibres or viscose fibres obtained by the process described in Specification 650,896, and spun into yarn. Bundles of the two forms of filaments may be formed into a blended yarn which is drafted to break the filaments into staple lengths within the yarn. The composite yarn is bulked by subsequent subjection of yarn or fabric made therefrom to the shrinking action (on one yarn constituent) of a hot aqueous medium which may be combined with dyeing and followed by treatment with 5% of a ureaformaldehyde resin to render the fabric crease-and shrink-proof to washing. Specifications 655,516 and 778,746 also are referred to. |
