AQUEOUS DISPERSION OF POLYURETHANES CONTAINING IONIC AND NONIONIC HYDROPHILIC SEGMENTS

Aqueous polyurethane (PU) dispersions were prepared from isophorone diisocyanate (IPDI), polytetramethylene glycol (PTMG), polypropylene glycol (PPG), polyethylene glycol (PEG), and dimethylol propionic acid (DMPA) as anionic center. The effects of the PEG/PTAd mixing ratio, type of polyether polyols, and hard segment content on the state of dispersion, surface, dynamic, and tensile properties of emulsion-cast film were determined. With more incorporation of nonionic hydrophilic PEG, particle size of the emulsion and tensile strength of the emulsion-cast film decreased, while the emulsion viscosity and elongation at break increased. Among ether type polyols, PTMG-based PU generally showed superior mechanical properties. With increasing hard segment content, particle size, storage modulus (E'), and tensile strength increased. At the lowest hard segment content (36 wt %) tested in this experiment, soft segments crystallized and water swell decreased. (C) 1994 John Wiley and Sons, Inc.