Process for the preparation of stabilized polymer dispersions in polyol at low temperature

In a process for the preparation of a graft copolymer dispersion in a polyol prepared by the in situ polymerization, in the presence of a free-radical initiator, of an ethylenically unsaturated monomer or mixture of monomers in a polyol, the improvement comprises conducting said polymerization in the presence of an effective amount of a preformed polymeric stabilizer wherein said stabilizer consists of an alkylene oxide adduct of a copolymer of styreneallyl alcohol having an equivalent weight of 220 to 8000.