Characteristics of Aldehyde Reactive Dyes for Leather Dyeing and Retanning Process

Abstract

Dyeing and re-tanning properties of nine aldehyde reactive dyes synthesized in our previous work were studied using aluminum pretanned wet-white sheep leather as a substrate. Their washing fastness and four dyeing property indexes, i.e., substantivity (S), exhaustion (E), reactivity (R) and fixation (F) were measured. The relationship between the colormatching effect and the relative difference values of the four dyeing property indexes of the combined dyes were investigated, and the simultaneous tanning-dyeing property of reactive dyes with a glutaraldehyde backbone were tested. The results were as follows: (1) The synthesized aldehyde reactive dyes could dye wet-white leather under mild conditions (T = 35-45°C, pH =4.0-6.5) within 1.5 h, and the dyed leather possessed a satisfactory washing-fastness. (2) Reactive dyes with a glutaraldehyde backbone had better dyeing performance than mono-aldehyde reactive dyes. (3) The less the relative difference value of the dyeing property indexes of the combined dyes, the better was the color matching effect. (4) The tested reactive dyes with a glutaraldehyde backbone increased the Ts of wet-white leather to 11-17°C in addition to dyeing it to the corresponding color.