Macromer and Process for Making Polymer Polyols

Polymer polyols are made by polymerizing an ethylenically unsaturated monomer in a continuous polyol phase. The polymerization is stabilized with a macromer or a pre-formed polymer made by polymerizing or copolymerizing the macromer. The macromer is a random polymer of propylene oxide and ethylene oxide in defined ratios, which also contains polymerization carbon-carbon double or triple bond. Polymer polyols made in the process exhibit little viscosity rise when blended with water. Flexible polyurethane foam made from the polymer polyol exhibits excellent hardness, have good surface characteristics and, when pigmented, exhibit good, uniform coloration.