| CPC C08G 18/632 (2013.01) [B01J 19/0066 (2013.01); B01J 19/06 (2013.01); B01J 19/18 (2013.01); C08F 283/06 (2013.01); B01J 2219/00031 (2013.01); B01J 2219/00033 (2013.01)] | 20 Claims |

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1. A method for preparing a polymer polyol, comprising reacting a base polyol, at least one ethylenically unsaturated monomer, and a macromer or a preformed stabilizer, in the presence of a free-radical initiator and optionally a chain transfer agent in a reactor (1), wherein said reactor (1) is stirred by means of a stirring system comprising a shaft (2) rotatable about its longitudinal axis (3), and a plurality of radially extending hydrofoil impellers (4) mounted on the shaft (2) and respectively axially spaced apart and wherein the reactor (1) does not contain baffles.
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