Patent ID: 8822581

Claim:
A method for making a polymer polyol, comprising (a) mixing a melted thermoplastic polystyrene polymer with a liquid polyol in the presence of a stabilizer under conditions sufficient to disperse the polystyrene polymer in the form of droplets within a continuous phase of the liquid polyol and (b) cooling the polymer polyol to solidify the polystyrene polymer, wherein the stabilizer includes a copolymer of (1) from 10 to 70% by weight of an unsaturated branched polyol which has a molecular weight of from 4000 to 20,000, from 0.2 to about 1.2 polymerizable ethylenically unsaturated groups per molecule and from about 3 to about 8 hydroxyl groups per molecule with (2) from 30 to 90% by weight of styrene or a mixture of styrene and one or more other low molecular weight monomers.