Dyeing property of fluorescent pigment latex on cationic knitted cotton fabrics

The recognized difficulties of pigment dyeing on cotton fabric are the large particle size of the pigment and low affinity between pigment particles and cotton fabric. The dispersion stability of the pigment and binding force between pigment particles and cotton fabric are important factors. To increase the stability of pigment dispersion, fluorescent pigment latex was prepared by encapsulating poly(methyl methacrylate-co-butyl acrylate) on the surface of C.I. Solvent Yellow 43. As a reactive emulsifier, allyloxy nonyl alcohol polyoxyethylene (10) ether sulfate can copolymerize with methyl methacrylate and butyl acrylate to endow the fluorescent pigment latex with negative charges. To improve the binding force between pigment particles and cotton fabric, the knitted cotton fabric was cationized. The prepared fluorescent pigment latex was further applied to dyeing of cationic fabrics by the exhaust dyeing process. Moreover, pseudo first- and second-order kinetic models were used to examine the adsorption kinetic data of fluorescent pigment latex on cationic cotton fabric. The results showed that the adsorption kinetic followed the pseudo second-order kinetic model, which indicated that the chemical sorption is a rate-limiting step, rather than mass transfer. The activation parameters were also evaluated to confirm the thermodynamic feasibility and spontaneous nature of cationic cotton dyeing with fluorescent pigment latex.

Research in the Cold Pad-Batch Dyeing Process for the Cationic Cotton

Cotton fabrics pretreated with cationic polyacrylamide with quaternary ammonium group were dyed with three reactive dyes in the absence of salt by cold pad-batch dyeing method. The influences of various conditions in the dyeing process, including urea dosage, selection of alkali agent and its dosage, batching time and batching temperature on colour yield, were analyzed. Fastness properties of the dyed cotton and the dye penetration were investigated between the pretreated and untreated cotton. The results showed that the dyesK/Svalues of the pretreated cotton were improved compared with those of the untreated one, in addition, the penetration and fastness properties of the dyed cationic cotton were satisfied for application.

Impact of Reactive Dye Structures on Dyeing Properties in Salt-Free Reactive Dyeing

The cationic cotton was obtained by pretreatment with tertiary amine cationic polyacrylamide, and dyed with various active groups reactive dyes in the absence of salt. The influences of reactive dye structures on dyeing properties were analyzed and the results showed that types of active groups in reactive dyes had little effect on dye exhaustion, but it was quite relative with dye reactivity and fixation. Reactive dyes with low molecular weight and more anionic groups were adsorbed more quickly on the cationic cotton and their adsorption time to reach adsorption equilibrium was shorter, compared with that with large molecular weight and less anionic groups. Moreover, exhaustion of reactive dyes with large molecular structures decreased due to sterically hindered effect in the salt-free dyeing. The results also displayed that the monochlorotriazine reactive dyes and the vinyl-sulfone ones were favorable to dye the cationic cotton without salt addition.

Application of Poly2-Methyl Acrylate-N-Methyl Pyridinium Iodide in Salt-Free Dyeing of Reactive Dyes

Poly2-methyl acrylate-N-methyl pyridinium iodide (PMAMPI) was used as a new cationic agent to pretreat cotton with dip-pad-bake method. The pretreated cationic cotton showed electropositive in the process of dyeing with reactive dye. The thesis has studied the optimized process for salt-free dyeing conditions. In the optimized salt-free dyeing process, the cotton fabrics treated with PMAMPI showed a good performance compared to those in the process of traditional salt dyeing. The results showed that color yield and color fastness of the reactive dyes on the cationic cotton were satisfied. The three dyes with best color matching performance include reactive dark red WGE, reactive navy blue WTE and reactive golden yellow WRE.