Improved mechanism of polyester dyeing with disperse dyes in finite dyebath

Abstract

A new sorption mechanism of polyester dyeing with disperse dyes in water is proposed. It is considered dye aggregates could not be sorbed unless they turn into single molecules. However, this theory could not explain numerous sorption phenomena: sorption continues when equilibrium dye concentration exceeds its solubility; dyeing at long liquor ratio, using microencapsulated or crystal‐modified dyes do not change concentration of single dye molecules or dye solubility, but increase sorption rate and quantity in a fixed time. We demonstrate that both single and aggregated dye molecules could be sorbed using CI Disperse Blue 56. Because of the large size and low diffusion rate, dye aggregates could temporarily block sorption channel and prevent entry of other dyes. Therefore, only using extra more dyes could get a dark colour. Series of approaches could be proposed to reduce or eliminate the sorption problems caused by aggregates using the new sorption mechanism.

The roles of elevated temperature and carriers in the dyeing of polyester fibres using disperse dyes: Part 2. Analysis of conventional models of dye adsorption

“…Bearing in mind the global dominance of disperse dyes and the commercial importance of PET fibres discussed previously, 1 it is unfortunate that the molecular state of disperse dyes, both in aqueous dyebaths and dyed fibres, has attracted much less attention than that of their anionic and cationic dye counterparts and more hydrophilic fibre variants, and, indeed, remains largely unresolved (e.g., 24,[68][69][70][71][72][73][74][75][76][77] ).…”

Facile synthesis of a cardanol‐based levelling agent as a biodegradable alternative to tristyrylphenol ethoxylates for the dyeing of polyester fabric

“…As the concentration is built up, the dye molecules enter the more orientated, but still non-crystalline regions, of the polymer. [14][15][16] Because of the limited water solubility of disperse dyes at ambient temperature, they are usually milled with dispersing agents to improve their dispersibility before dyeing. 17,18 During the dyeing process, only the dye molecules dispersed by dispersing agents can be absorbed by fibres.…”

“…Precisely, the dye molecules first accumulate in the least‐orientated regions of the fibre. As the concentration is built up, the dye molecules enter the more orientated, but still non‐crystalline regions, of the polymer 14‐16 . Because of the limited water solubility of disperse dyes at ambient temperature, they are usually milled with dispersing agents to improve their dispersibility before dyeing 17,18 .…”

The roles of elevated temperature and carriers in the dyeing of polyester fibres using disperse dyes: Part 1 fundamental aspects

“…T A B L E 7 Aqueous solubility of pure disperse dyes at 130 C476,483,489,491 Solubility, mg l À1 at 80 C of purified disperse dyes in water and in 0.5% aqueous commercial dispersing agent; drawn using data from 63. Dispersol AC, disodium methylene bis naphthalene sulphonate; Dispersol VL, fatty alcohol-ethylene oxide condensate; Lissapol C, sodium oleyl sulphate; Lissapol LS, sodium oleyl-p-anisidine sulphonate.…”