Application of polyurethane dispersant in preparation of liquid indigo

A anionic polyurethane dispersions were prepared from isophorone diisocyanate (IPDI), polyethylene glycol 200, 400, 600, 800(PEG200, PEG400, PEG600, PEG800), 2,2-dimethylpropyl acid (DMPA), 1-phenyl-1,2-glycol, neutralizer triethylamine(TEA), methylketoxime and so on. The structure and properties of dispersant were characterized by FTIR, GPC and TG. The liquid indigo dispersion was prepared by grinding method with the self-made dispersant. The influences of chain length and amount of dispersant on performance of the dispersion were discussed. After grinding for 1 h, when the amount of polyurethane dispersant synthesized with PEG400 as soft segment was 60% of the mass of dye, the particle size of prepared liquid indigo was 277.1 nm, the centrifugal stability at 1000 r/min was 93.98%, and that at 3000 r/min was 51.13%. After being placed at room temperature for 7 d, the particle size changed within 20 nm, and the color depth (K/S) value of the dyed fabric was about 10, which was about twice that of the dyed fabric with powdered indigo, The color properties of dyed fabric did not change. SEM showed that the particle size distribution of the dispersion was uniform. There was little difference in the stability of the dispersion system compared with formaldehyde condensate (MF) of sodium methylnaphthalene sulfonate and lignin 85A. © 2022, Editorial Office of FINE CHEMICALS. All right reserved.