Constructing polyfunctional reactive dyes for printing of cotton fabrics with ultra-high fixation and ultra-low staining on the white ground

To address the challenges of low fixation and poor resistance to staining on white ground of reactive dyes in the dyeing and printing industry, two new polyfunctional reactive dyes (MFA-1 and MFA-2) were developed. These dyes, which contained m-phenylenediamine derivatives with sulfonic and methyl groups as bridge groups, demonstrated high solubility (above 350 g/L) and low affinity to fibers. Detailed investigations were conducted to understand the factors affecting printing performance. The two dyes exhibited exceptionally high fixations of 94.35% and 95.75%, respectively, on cotton fabrics at a high dye concentration of 5.0%. This represented a 24% and 43% improvement over C.I. Reactive Red 111 and C.I. Reactive Red 120, respectively. Notably, MFA-2 achieved a fixation above 95% even at a higher dye concentration of 10.0%. Additionally, both MFA-1 and MFA-2 showed minimal staining on white ground, with fastness properties of grades 3 and 4, respectively, representing 2-3 grades higher than C.I. Reactive Red 111 and C.I. Reactive Red 120. The mechanism behind the exceptional fixation and low staining properties of these dyes was proposed, suggesting that the unique structure of the bridge group disrupted the co-planarity of the dye molecule and evenly distributed the negative charge in the dye molecule. Furthermore, the cotton fabrics printed with MFA-1 and MFA-2 demonstrated good color uniformity, with low Delta E values of 0.46 and 0.32, respectively. The printed fabrics also exhibited good dry and wet rubbing fastness (grades 4 and 3, respectively), wash fastness (grades 4-5), light fastness (grade 4), and perspiration fastness (grades 4 or 4-5).