The Technology of Polymer Polyols Manufacture by Radical Processes

3 The Technology of Polymer Polyols Manufacture by Radical Processes 

One of the most common technologies for the synthesis of polymer polyols by a radical mechanism is based on the stepwise addition of a mixture of vinylic monomers (polyether polyol, initiator, transfer agent (mixture I)) to a second mixture (mixture II) of polyether polyol (identical with the polyether used for mixture I) and NAD (macromer or nonreactive NAD) under a nitrogen protective atmosphere, in the polymerisation reactor at 115- 

125 °C. After the addition of all quantities in mixture I, the reaction mass is maintained at the same reaction temperature for around one hour for digestion, followed by the vacuum distillation of unreacted monomers or steam stripping and anhydrisation. 

Of course, in order to increase the stability of mixture I, where vinylic monomers are in the presence of the initiator, the initiator is added separately, as a solution (for example as solution in the transfer agent), or as a suspension in the polyether. 

The fabrication process of polymer polyols by radical mechanism is either a batch process, or a semi-continuous or continuous process. 

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