An Improvement on Water Retaining and Agent Distribution of PET Non-woven Fabrics Treated with the Low Molecular Weight Polyurethane Solutions

Abstract

In this study, diphenylmethane diisocyanate (MDI), 2,2-bis(hydroxymethy)-propionic acid (DMPA), and polytetramethyleneglycol (PTMG) were employed to polymerize the low molecular weight polyurethane (LMWPU). The mole ratios for the LMWPUs were 4.0:1.5:0.5, 4.0:1.0:1.0, and 4.0:0.5:1.5, respectively. The three LMWPUs were dissolved in lithium chloride/tetrahydrofuran (UCV THF) to prepare the finishing solutions. The water retaining values of the treated non-woven fabrics with the solutions increased by the increase of the component of the PTMG contained in LMWPU. This higher content of PTMG in LMWPU resulted in a lower add-on value and a lower degree of the blocking deposited in the gaps among fibers. Both of these could significantly improve the water retaining property. The water retaining values for the LMWPU solutions were dramatically higher than those for commercial water soluble polyurethane and LMWPU emulsions. The functional groups of LMWPU were confirmed with the analyses of the spectra of Fourier transform infrared spectroscopy (FT-IR). The average molecular weights of the three LMMTUs ranged from 2000 to 3800 g/mole and the average particle sizes ranged from 140 to 1140 nm. The degree of polymer crystals obtained from LMWPU solutions is lower, which could also significantly improve the water retaining property.