Polyisocyanate Polyaddition PIPA Polymer Polyols

The synthesis of polyisocyanate polyaddition (PIPA) polymer polyols is very similar to the synthesis of PHD polyols, with the difference that, instead of polyurea, a PU finely 

The preferred alkanolamines are triethanolamine and diethanolamine [8-10, 75-87], and the diisocyanates used are TDI and low functionality MDI (for example, pure MDI). 

An ideal reaction for PIPA polyols synthesis is shown in reaction 6.24  

As a first observation, the difference in reactivity between the hydroxyl groups of triethanolamine and the hydroxyl groups of liquid polyether is not so high as that between amino groups and hydroxyl groups in reaction with a diisocyanate. In order to accelerate the reaction of diisocyanate with the primary hydroxyl groups of triethanolamine in PIPA production, specific catalysts such as dibutyl tin dilaurate or stannous octoate are used [79-87]. 

The polyether polyols used most frequently are PO homopolymers or random PO-EO copolymers (MW of 3000-3600 daltons) or PO-EO block copolymers with terminal poly[EO] block (MW of 4700-5000 daltons). 

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The utilisation of the high MW aminic polyether polyols in the synthesis of polymer polyols [graft polyether polyols and polyisocyanate polyaddition (PIPA) polyols] is presented in Chapter 6 [148, 151]. 

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