Reactive dyeing of synthetic fibers employing dyes containing a diazirine moiety

It is well-known that polypropylene (PP) or aramid fibers are challenging to dye by using conventional dyeing methods, which limits their further development in the textile and garment industry. Herein, we report a new methodology for deep dyeing synthetic fibers employing synthesized diazirine-containing dyestuffs. The combination of the diazirine moiety with a chromophore with heating at 150 °C produced the dye-forming carbene intermediate, which could covalently bond with the C–H bonds in the synthetic fibers. It was demonstrated that the diazirine dyes did not pose any explosive risk, although nitrogen molecules were generated along with the formation of carbene. Compared with the high-temperature–high-pressure dyeing and carrier dyeing-fixation methods, the non-aqueous solvent dyeing–fixation method was screened and certified to be suitable for the reactive dyeing of synthetic fibers. The diazirine-based dyes could efficiently react with poly (ethyleneterephthalate), nylon, PP, aramid, acrylic, and polyurethane (spandex) fibers with moderate to excellent fixation values. Particularly, the color yields of the PP, aramid, and acrylic fabrics were further improved significantly by repeating the non-aqueous solvent dyeing–fixation operation. Thereafter, the detailed dyeing and fixing mechanisms of the reactive dyeing method were proposed. Finally, the color fastness properties of these dyed fabrics were demonstrated to be excellent, thus making such a reactive dyeing method for synthetic fibers a very promising one for the future.