In-fibre formation of Fe(OH)3 - a new approach to pigment coloration of cellulose fibres

In alkaline solution a ligand exchange reaction between dissolved Fe(III)-D-gluconate complexes and cellulose fibres occurs. This reaction can be used to insert Fe(III)-ions in cellulose fibres. During rinsing the complex stability of the Fe(III)-cellulose complex is lowered and precipitation of Fe(III)-hydroxide inside the cellulose fibre occurs. This process permits pigment dyeing of cellulose fibres with in-situ in-fibre formation of the pigment. The impregnation was performed as an exhaust method at 80 degreesC using solutions Fe(III)-D-gluconate complexes with c(Fe3+) 0.25-3.75 mmol l(-1) and C(D-gluconate) 0.5-7.5 mmol l(-1). Due to the higher complex stability of the fibres iron concentrations in the fibre were determined with 2.7-14.8 mmol Fe per kg of fibre. Excellent fastness properties of the dyeings were found with light fastness of 7-8 and wet fastness of 5. (C) 2003 Elsevier Ltd. All rights reserved.