Salt-free reactive dyeing of betaine-modified cationic cotton fabrics with enhanced dye fixation

Novel cationic cotton fabrics were prepared by an efficient and simple one-step pad–dry–bake pretreatment process with betaine as cationic reagent. Ester bonds formed between cotton fibers and betaine hydrochloride were proved by Fourier transformed infrared attenuated total reflection (FTIR-ATR) spectra. Moreover, the properties of the cationic fabrics, including X-ray Diffraction (XRD), tensile strength and whiteness and yellowness index, were investigated in comparison with that of the untreated ones. The cationic fabrics were applied in salt-free dyeing of C.I. Reactive Red 195, C.I. Reactive Yellow 145 and C.I. Reactive Blue 19. Different dye fixation processes were applied and compared for untreated and cationic cotton. Dye fixation and color fastness properties of the dyes were tested, and the results presented that dye fixation on the cationic fabrics in the absence of salt was improved with satisfactory light fastness property and applicable wash and rub fastnesses.

Graphical abstractCationic cotton fabrics were prepared by an efficient and simple one-step pad–dry–bake process with betaine as cationic reagent. The structure of the cationic fabrics was analyzed to show formation of ester bonds. XRD, tensile strength and whiteness and yellowness index were all investigated to present good applicability of the cationic fabrics. Salt-free dyeing results showed that F% of C.I. Reactive Red 195, C.I. Reactive Yellow 145 and C.I. Reactive Blue 19 increased by 6.7%, 9.5% and 7.7%, respectively, in comparison with that of the conventional dyeing. And satisfactory light fastness and applicable wash and rub fastnesses properties were all obtained, indicating that this dyeing method showed good application prospect.Figure optionsDownload full-size imageDownload as PowerPoint slide