Part IV. Preparation of polyetherols from (methoxymethyl)melamine
A new method of synthesis of polyetherols containing the s-triazine ring, applied for thermoresistant polyurethane foams, has been presented. N,N,N',N,N”-Pentakis(hydroxymethyl)melamine (PHMM) was an initial raw material to obtain N,N,N',N',N” -pentakis(methoxymethyl)melamine (PMMM) in the reaction of PHMM with methanol. Then PMMM was transeterified with ethylene glycol up to 75% reaction extent (to avoid crosslinking) and the re action mixture (containing a transeterification product, unreacted PMMM and ethylene glycol) was treated with an excess of oxiranes (ethylene oxide, propylene oxide or glycerol epichlorohydrine) to obtain various s-triazine polyetherols. Thus, disadvantageous condensation of hydroxymethyl groups leading to crosslinked products in the direct reaction of PHMM with oxiranes has been avoided. The elimination of solvent has also been gained, since the PMMM transeterification product is soluble in oxiranes. Some physical properties of polyetherols have been characterized, and the thermal resistance of polyurethane foams from these polyetherols has been investigated.
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