| 摘要 |
A process is disclosed for producing stable, agglomerate-free, low-viscosity gra ft copolymer dispersions by radical polymerization of ethylenically unsaturated monomers in a base polyol, wherein the polymerization is carried out in the presence of a free-radical catalyst, a macromer, and a chain transfer agent. Sui table chain transfer agents comprise aminocrotonic acid esters corresponding to the general formula below: (see fig. I) in which R1 represents a monovalent or divalent aliphatic hydrocarbon radical containing from 1 to 6 carbon atoms, and which may additionally contain one or more ether bridges; R2 represents a monovalent aliphatic, alicyclic, araliphatic or aromatic hydrocarbon radical containing from 1 to 12 carbon atoms, and which may additionally contain one or more ether bridges, and/or one or more hydroxyl groups and/or one or more tertiary amino groups; and n represents one or two. The use of these polymer polyols in the production of polyurethane foams is also described.
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