GB360688A - Process for the production of filaments, films, foils and other products from aqueous cellulose solutions - Google Patents

Abstract

In the manufacture of artificial filaments, films, foils and other products from aqueous cellulose solutions such as viscose or cuprammonia cellulose solutions, there is employed a precipitation bath consisting of an inorganic acid and the monodi, tri- or penta-hydrates of methanol or a mixture of such hydrates. By the use of the hydrates of methanol, too rapid withdrawal of water from the coagulated product, with consequent degradation of the cellulose by the sulphuric acid or methyl hydrogen sulphate, is prevented; the filaments produced from normal ripened viscoses have a strength of above 2 grams per denier, and from viscoses prepared from unripened soda cellulose, of 3 grams or more per denier. The sodium sulphate produced during the coagulation has a favourable action on the product; similarly other salts and additions such as magnesium or zinc sulphates, and glucose dissolved in the coagulation bath, assist the precipitation process. The coagulation bath may be regenerated by cooling to low temperatures to cause separation of the excess of sodium sulphate together with a part of the water; and, during the coagulation process too great dilution of the bath is avoided by the addition of anhydrous methanol and sulphuric acid. In examples, a coagulation bath for normal viscose is prepared by forming methanol dihydrate by heating together methanol and water in the requisite proportions, and adding to this sulphuric acid and magnesium sulphate; a bath for viscose prepared from unripened soda cellulose consists of a mixture of tri- and penta-hydrates of methanol prepared by mixing methanol with the appropriate quantity of water, and an addition of sulphuric acid. Specifications 21144/06, [Class 2, Acids and salts, Organic &c.], 257,924, and 257,925, [both in Class 2 (ii), Cellulose &c.], are referred to.