Anionic coloration of acrylic fibre. Part 1: Efficient pretreatment and dyeing with acid dyes

Anionic dyeable acrylic fibre has been obtained by a viable and efficient pretreatment process using hydroxylamine hydrochloride in the presence of acetate salt. The chemical modification relies on an amidoximation reaction that partially converts cyano groups present in the fibre to amidoxime groups. Different factors that may affect the pretreatment process have been investigated. The pretreated fabrics were dyed with CI Acid Red 1 and CI Acid Green 16 and gave improved dyeability over untreated fabrics due to the ion–ion interactions between the sulphonic groups present in the dye molecules and the protonated amino groups present in the fibres. The treated dyed fabrics also showed excellent fastness properties. Fibre characterisation (nitrogen content, tensile strength, shrinkage, infrared spectra and X-ray diffraction) proved the success of the amidoximation reaction.