GB716236A - Improving the properties of cellulosic textile materials - Google Patents

Abstract

Fibres, yarns and fabrics composed of or containing natural cellulose, regenerated cellulose or cellulose derivatives, e.g., cotton, linen, viscose and acetate rayon, are given an increased wet strength, resistance to shrinkage and creasing and a reduced water imbibition by applying thereto a reaction product of an alkali metal bisulphite with an organic mono- or polyfunctional isocyanate or isothiocyanate and also, separately in either order, or simultaneously, an amide, amidine or aminotriazine and then heating at a temperature at least as high as the decomposition temperature of the reaction product, e.g., to 100 DEG -200 DEG C. The p reagents are applied in the same or different, preferably aqueous, solution or dispersion and the material then dried, or partially dried prior to heating. Alternatively the drying and heating steps may be combined. The material may be subsequently washed to remove byproducts or residues. The bisulphite reaction product may be formed in situ on the material by either applying, in any order, an aqueous solution of the bisulphite and an organic solution of the isocyanate or isothiocyanate, or by applying an emulsion of the isocyanate in an aqueous bisulphite solution. Heating may be effected with hot air, infra-red radiation, molten metal or steam. Specified amides, amidines and aminotriazines are urea, thiourea, acetamide, benzamide, benzene sulphonamide, p-toluene sulphonamide, dicyandiamide, guanidine, amino guanidine and melamine. Local or pattern effects may be obtained by printing the reagents on the material, or alternatively, by the preapplication of resists or the subsequent application of a discharge paste prior to heating. In the case of fabrics, especially crepes, they are preferably held or stretched to the desired dimensions on a stenter during drying, or are slightly over-stretched during drying after which they are heated and then relaxed in the wet condition whereby they shrink to the desired dimensions. Prior to heating, treated fabrics may be compressively shrunk on the machines of Specifications 359,759 and 372,803, [both in Group VIII]. Softening, lubricating and anti-crease agents and antiseptics may be applied to fabrics before, after or simultaneously with the above reagents. Reaction products of bisulphites with both aliphatic or aromatic isocyanates and isothiocyanates may be employed, the specified reaction products being those specified in Specification 716,233. Specifications 716,232 and 716,234 also are referred to.