GB821960A - Improvements in or relating to the manufacture of regenerated cellulose structures by the viscose process - Google Patents

Abstract

Regenerated cellulose structures, e.g. fibres and filaments, of high tenacity, are made by extruding viscose into an aqueous bath containing up to 10% by weight of sulphuric acid, at least 13% by weight of sodium sulphate, and at least 5% by weight of zinc sulphate, with stretching of the extruded structures, in the presence of less than 0.5 millimol. per 100 grams of viscose or spinning bath of a water-soluble quaternary ammonium compound, the viscose being prepared by xanthating alkali cellulose with at least 37 per cent by weight of carbon disulphide, based on the cellulose content of the alkali cellulose, and the percentage by weight of carbon disulphide used being at least 4.9 times the percentage by weight of sulphuric acid in the bath. Water-soluble, non-surface-active compounds of the formula R1R2R3R4N-X, where R1, R2, R3 and R4 are organic groups having not more than four aliphatic carbon atoms, at least three of the groups containing only aliphatic carbon atoms, and the fourth group, when aromatic, containing no more than one benzene nucleus, and X is an hydroxyl group or an anion having substantially no surface activity, e.g. the chloride, bromide, iodide, sulphate, bisulphate or acetate anion, are preferably used. Specified compounds are benzyltrimethyl ammonium chloride, tetraethyl ammonium hydroxide, phenyl trimethyl ammonium hydroxide, tetraethanolammonium hydroxide, tetraethylammonium bromide, tetramethylammonium iodide, tetrapropylammonium hydroxide, tetrabutylammonium chloride, tributylpropylammonium hydroxide, tri-(beta-hydroxyethyl) - methylammonium hydroxide and tributyl - (beta - hydroxyethyl) - ammonium iodide. The viscose used, which may be ripened or unripened, may be obtained by xanthation performed in the conventional manner or by a split xanthation p procedure. It may be extruded hot or cold, but is preferably heated to 40-80 DEG C. The spinning bath is also preferably heated to 40-80 DEG C. and may contain, in addition to zinc sulphate, other divalent metal salts, e.g. ferrous sulphate, manganese sulphate, nickel sulphate or chromic sulphate. After extrusion, the filaments may travel through about 25 to 150 inches in the primary bath, where they may be confined to a small area by means of multiple rollers, designed to apply tension to the travelling filaments in gradual increments and thereby orient them while still plastic. Part of the stretch is preferably applied, however, beyond the primary bath by-passing the filaments through a secondary bath or shower located between two feed-wheels. The secondary bath may consist of water, dilute (1-4%) sulphuric acid or diluted spinning bath at a temperature between 50 DEG and 100 DEG C. Total stretches of 80% or more are preferably used for producing high-tenacity yarns. The quaternary ammonium compound may be added to the viscose during dissolution of the cellulose xanthate. Specifications 652,741, 712,623 and U.S.A. Specification 2,801,998 are referred to.