Fireproofing of polyurethanes .1. Use of an unsaturated polyol modified by1-thioethyl diethylphosphonate

A new phosphonate was used for fireproofing of polyurethane. This product, 1-thioethyl phosphonate, was synthesized in two steps. The first one was an Arbuzov reaction between 1,2-dibromoethane and triethyl phosphite. The sec ond step was a nucleophilic substitution of bromine by the -SH function of thiourea, followed by in-situ saponification and neutralization. Radical ad dition of this thiophosphonate onto hydroxy telechelic polybutadiene led to a polyol with various ratios of phosphorus. Different polyurethanes were p repared from this polyol and methylene diphenyl isocyanate (MDI) (wt% of P = 1 and 2%). Besides an increase of glass transition temperature, one can n otice, by using thermogravimetric analysis, that the amount of residue beyo nd 600 degrees C notably increases up to 8% - with the percentage of phosph orus. (C) 2000 Elsevier Science Ltd. All rights reserved.