Waterborne oil-modified polyurethane coatings via hybrid miniemulsion polymerization

As part of a wider effort to develop a new class of waterborne coatings, hy brid miniemulsion polymerization was carried out with acrylic monomers (met hyl methacrylate, butyl acrylate, and acrylic acid) in the presence of oil- modified polyurethane resin. Latexes with different ratios of resin to acry lic monomers were synthesized. The monomer emulsions prepared for hybrid mi niemulsion polymerization showed excellent shelf-life stability (>5 months) and the polymerization was run free of coagulation. Solvent extraction ind icated that the grafting efficiency of polyacrylics was greater than 29% fo r all the samples produced. A C-13 solution NMR spectrum showed that a subs tantial fraction of the original carbon double bonds (>61%) in oil-modified polyurethane remained after polymerization for film curing. Films obtained from the latexes presented good adhesion properties and fair hardness prop erties. (C) 2000 John Wiley & Sons, Inc.