Low viscosity polymer polyols with improved dispersion stability

Abstract

The present invention provides polymer polyols and a method for preparing polymer polyols which have (1) exceptional dispersion stability, especially at high styrene contents, and (2) substantially smaller particle sizes than polymer polyols having equivalent viscosity. In a preferred embodiment of the present invention, a first reaction product is obtained by feeding the following materials to a first continuous reactor in the presence of a free radical initiator or catalyst: (a) less than about 50 wt. % of a total monomer proportion or monomer mixture, preferably comprising styrene/acrylonitrile at a ratio preferably greater than about 50/50 wt. %; (b) at least about 50 wt. % of a total base polyol proportion; (c) a majority of a precursor stabilizer; and, (d) a polymer control agent (PCA). The product from this first reaction then is again fed through a continuous reactor, which may be the same as the first reactor, along with additional initiator, at least about 50% of the total monomer proportion, and, optionally, any balance of the total base polyol proportion, precursor stabilizer, and PCA. The product from this second reactor is a high stability, low viscosity polymer polyol.

Dependencies are inferred from the claim text.