GB981467A - Improvements relating to the dyeing of polyamide fibres, impregnation liquors for use therein, and the resulting products - Google Patents

Abstract

Natural or synthetic polyamide fibres are dyed by impregnating them with an aqueous solution of acid wool dyes containing as carrier a soluble salt of a saturated aliphatic monocarboxylic acid having 8-14 carbon atoms at a temperature below the drawing temperature of the dyestuffs, followed by a heat treatment above the drawing temperature and then rinsing. As salts of the above acids are specified lithium, sodium, potassium, ammonium and substituted ammonium salts especially amine derivatives. The acids having 8-14 carbon atoms are caprylic, capric, lauric, pelargonic and myristic acids and coconut oil fatty acids. Other auxiliaries which may be present in the impregnation liquors include inorganic salts, acids, and amides of saturated aliphatic monocarboxylic acids having 8-14 carbon atoms. Preferably 10-60 grams/litre of soluble monocarboxylic acid salts are used in the impregnation liquor, the impregnation being at 40-70 DEG C. followed by squeezing to leave 40-110% by weight of liquor on weight of fibres left on the fibres. An acid shock process or hot steaming followed by rinsing may be used to finish the dyeing. Wool, silk and nylon may be dyed and continuous processes are referred to. The dyes may be metal-free, heavy metal containing dyes, metalisable dyes, mono or polyazo dyes, anthraquinone, phthalocyanine or nitro dyes. Conventional thickeners may be added to the impregnation liquors. Substituted ammonium salts of the acids include those derived from primary, secondary or tertiary amines, from monoalkylamines and hydroxyalkylamines.