A method for improving the whiteness and the receptivity for basic dyes of fibers or threads or - mixed polymers of acrylonitrile polymers are

摘要

Fibres composed of at least 80% by weight of polymerized acrylonitrile are whitened and their basic dye uptake improved by treating them with an aqueous solution of hypophosphorous acid or a mixture thereof with a water-soluble metallic salt thereof, having a pH of 7 or below. The aqueous solution may contain 0.01-1% by weight of the hypophosphorous acid and may be applied to the fibres by spraying, as an additive to the finishing bath, by wicks or by the use of rolls. The water soluble hypophosphite may be an alkali or alkaline earth metal hypophosphite. The fibres may be treated after spinning, stretching and washing prior to drying. The fibres may be made from polyacrylonitrile, from a copolymer containing at least 80% by weight of acrylonitrile or from a blend comprising polyacrylonitrile or copolymers comprising acrylonitrile with 2-50% by weight of another polymeric material, the blend having an overall polymerized acrylonitrile content of at least 80% by weight. In the copolymers the acrylonitrile may be copolymerized with acrylic, a -chloroacrylic or methacrylic acid, methyl, ethyl, butyl, methoxy-methyl or b -chloroethyl acrylate, methacrylate or chloroacrylate, vinyl chloride, fluoride or bromide, vinylidene, chloride, 1-chloro-1-bromoethylene, methacrylonitrile, acrylamide, methacrylamide, a -chloroacrylamide, methyl vinyl ketone, vinyl acetate, chloroacetate propionate or stearate, N-vinylphthalimide, N-vinyl succinimide, methylene malonic esters, itaconic acid or esters thereof, N-vinyl carbazole, vinyl furane, alkyl vinyl esters, vinyl sulphonic acid, diethyl citraconate or mesaconate, styrene, vinyl naphthalene, vinyl pyridine, alkyl substituted vinyl pyridines, 1-vinyl imidazole or alkyl substituted 1-vinyl imidazoles.