Polyester-polyurethane hybrid resin molding compositions

Abstract

Polyester-polyurethane hybrid resin molding compositions having a first, soft polyurea phase within a second, more rigid polyester-polyurethane phase are disclosed. The compositions are formed by the reaction of an A side composition and a B side composition. The A side composition comprises a polyfunctional isocyanate compound and a free radical polymerization catalyst. The B side composition comprises a mixture of (i) an ethylenically unsaturated monomer solution having dissolved therein about 40-90 weight percent of a substantially water-free, unsaturated polyester polyol having at least one dicarboxylic alkene moiety and having an acid number less than five; and (ii) a polyfunctional nitrogen-containing compound having at least one active hydrogen atom on each of at least two nitrogen atoms in each molecule, which, when reacted with the A side composition, has a molecular weight sufficient to form the first, soft polyurea phase. The A and B side compositions, which are reacted at the time of molding, have a ratio of active NCO groups of the isocyanate to NH groups of the nitrogen-containing compound of between about 3:1 to about 100:1, a ratio of active NCO groups to active OH groups in the polyester polyol of between about 0.5:1 and about 6:1, such that the stoichiometric index NCO:(NH+OH) is between about 0.5 and about 2.0.