Anionic Blocked Isocyanate-Containing Urethane Prepolymer Dispersions for Coating Applications

By H. Xiao, H.X. Xiao, B. Suthar, K.C. Frisch

Anionic blocked isocyanate-containing urethane prepolymer dispersions were synthesized from poly(oxypropylene) glycol, polyarylpolyisocyanate (PAPI 2094), dimethylolpropionic acid (DMPA), and methyl-ethyl ketoxime (MEKO).

A stoichiometric amount of tetraethylenepentamine (TEPA) was added as a crosslinker to the blocked polyisocyanate dispersions resulting in one-package crosslinkable, waterborne urethane coatings.

The samples were characterized by means of mechanical properties, chemical resistance, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The deblocking kinetics of the blocked polyisocyanates at different baking temperatures we restudied.