DUAL-CURING OF ANIONIC AQUEOUS-BASED POLYURETHANES AT AMBIENT-TEMPERATURE

Polyurethane (PU) prepolymers are prepared by a polyaddition of isopho rone diisocyanate, polypropylene glycol-1000, and 2,2-dimethylolpropan ic acid. The anionic aqueous-based PU dispersions are derived from a w ater dispersion process of these NCO-terminated PU prepolymers togethe r with a neutralization and a chain extension. They have both terminal amino and pendent carboxylic groups which are potentially reactive si tes toward a di-functional epoxy and a tri-or di-aziridinyl compound o f a dual-curing PU system, respectively. The stabilities of the result ing PU dispersions on zeta potential and particle size distributions a re investigated. The improvements on mechanical, physical, and thermal properties of these dual-cured PU systems are also evaluated. (C) 199 8 John Wiley & Sons, Inc.