GB640411A - Improvements in and relating to the manufacture of sheets or webs of fibrous textilematerials - Google Patents

Abstract

Sheets of fibrous textile materials are made by forming a layer consisting wholly or partly of fibrous cyanoethylated cellulose, which has been prepared by etherifying cellulose fibres with acrylonitrile while maintaining their fibrous structure, and rendering the fibrous cyanoethylated cellulose adhesive to bond the fibres together. The cyanoethylated cellulose may be prepared from natural cellulose fibres such as cotton, hemp, ramie, jute or flax, or regenerated cellulose such as continuous or discontinuous viscose rayon fibres, preferably by soaking them in an aqueous solution of an alkaline catalyst, such as a caustic alkali, an alkali metal cyanide or a quaternary ammonium hydroxide, removing the excess solution by centrifuging, and reacting the fibres heterogeneously with acrylonitrile in the presence of a non-polar inert diluent such as benzene or toluene. The cyanoethyl cellulose forms an accessible phase, surrounding, and merging into, crystalline non-etherified cellulose inclusions. Two types of cyano-ethyl cellulose are formed, either of which may be used, in conjunction with a suitable swelling agent or solvent; the first, which exists when the nitrogen content of the fibres does not exceed about 9 per cent of their dry, ash-free weight, is swollen readily by dilute aqueous solutions of caustic alkalies and quaternary ammonium hydroxides, and by moderately strong solutions of such salts as sodium, ammonium or calcium thiocyanates, or zinc chloride, but is not rendered adhesive by water or organic solvents such as acetone or meta-cresol. The second form exists when the fibres have a nitrogen content of about 9 to about 11 per cent, and is not soluble in, nor swollen by, water or aqueous caustic alkali solutions, but is swollen and rendered adhesive by organic solvents such as acetone, acetonitrile, b -ethoxy-propionitrile, dimethyl formamide, methyl formate and meta-cresol. The cyanoethylated fibres may be used alone or in admixture with other fibres, and may be carded to form a web. They may be treated with a weak aqueous solution of a surface-active agent containing an aliphatic chain of at least six carbon atoms in its molecule, e.g. cetyl trimethyl ammonium bromide, or with sodium dioctyl succinate, before carding. Specification 10246/38 (as open to inspection under Sect. 91) and U.S.A. Specification 2,375,847 are referred to.