Reactive Dyes Containing Phosphonic and Carboxylic Acid Reactive Groupings and Their Reactions with Cellulose

Abstract

Factors influencing the fixation efficiency on cotton of reactive dyes containing phosphonic and carboxylic acid groupings have been briefly investigated and inferences made. Reactions of some carboxylic acids with some alcohols, including acetylcellulose, in the presence of carbodiimides, including cyanamide and dicyandiamide, have also been undertaken and the reaction products analysed and quantified by n.m.r. and micro‐analytical techniques. The results of these studies have given a strong indication of the dye‐fibre product formed when a carboxylated dye is reacted with cellulose in the presence of a carbodiimide. High‐temperature steam fixation of dye in the presence of cyanamide and dicyandiamide has in addition been studied. The level of dye fixation achieved by high‐temperature steaming was found to be partly limited by hydrolytic deactivation of carbodiimide under such conditions, while loss of carbodiimide by thermal decomposition has been identified as the single most important factor which limits the optimum level of dye fixation on baking.