Abstract
A self-dispersing pigment was produced by a diazonium coupling reaction; the pigment reacted with aromatic diazonium salts which were generated by the reaction of p-aminobenzene sulfonic acid and sodium nitrite. The surface of the pigment particles was negatively charged due to sulfonic acid groups on the pigment surface. The pigment particle size and zeta potential were, respectively, 134.5 nm and −45.4 mV at neutral pH. The wool surface was positively charged by adjusting the pH; then the anionic self-dispersing pigment dyed the cationic wool. The results show that self-dispersing pigment can adhere well without a binder, and that the K/S value is closely related to pH, dyeing time, and the amount of pigment. The color fastness of the wool was good and the light fastness of the wool was grade 5, which is better than acid dyes. Self-dispersing pigments are potential candidates for dyeing high-weather-resistance textiles.
Highlights
Wool colorants are usually acid dyes, most of which contain sulfonate groups and are soluble in water [1,2,3]
Wool is mainly composed of protein, and has many carboxyl and amino groups
When the pH is higher than the isoelectric point, the carboxyl groups on the wool surface are ionized and the wool surface is negatively charged
Summary
Wool colorants are usually acid dyes, most of which contain sulfonate groups and are soluble in water [1,2,3]. Wool is mainly composed of protein, and has many carboxyl and amino groups. The isoelectric point of wool is about 4.2 to 4.8. The wool surface will remain neutral when the pH is at isoelectric point. When the pH is lower than the isoelectric point, the amino groups on the wool surface are protonated and the wool surface becomes positive. When the pH is higher than the isoelectric point, the carboxyl groups on the wool surface are ionized and the wool surface is negatively charged
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