| Reactive dye is the main dye in cellulosic fibers dyeing, but the wet rubbing fastness of reactive dyes is very poor. The international standards and domestic standards allow the wet rubbing fastness is level 2-3, but consumers have become so increasingly harsh demanding for the wet rubbing fastness in recent years that they often require the standard is above level 3. However, the present dyeing textiles, especially the textiles in deep color are not able to satisfy the consumers. Therefore, to improve the wet rubbing fastness has become a major challenge persecuting current dyeing industry.A new type of moderate aqueous polyurethane-type wet rubbing fastness improver which is called as wet rubbing fastness improver CW was synthesized. The improver is made up of diisocyanate and low molecular polyether and works with five mechanisms in one - adsorption, precipitation, film forming, fixing, and cross-linking. The synthesis process is determined as follows: n (PPG) / n (PEG) = 1:1:1; R values (-NCO/-OH of the molar ratio) = 1.05; dimethylol propionic acid (DMPA) dosage of 3.07%; the mount ratio of chain extender agent diethylene triamine, epichlorohydrin cross-linker and MDI 1:1:1; pre-polymerization temperature 70℃, pre-polymerization time 2.5h; diethylene triamine reaction temperature 50℃, reaction time 2h; the epichlorohydrin reaction temperature 50℃, reaction time 30min.Through experiments, the application process of wet rubbing fastness improver CW is established as follows: two-dip-two-nip (CW 30 g / l, pH 7 ~ 8, pick-up100% ~ 110%)→drying (100℃)→curing (150℃×120S)Application results show that through the wet rubbing fastness improver CW treatment, the wet rubbing fastness is improved obviously and reaches up to level 3. The innovation of this research is that the solvent-based polyurethane raw materials MDI are exchanged into water-based polyurethane synthetic process, as opens up a new road in the application of MDI in water-based polyurethane.
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