Verfahren zur Herstellung von flammfesten,Urethangruppen aufweisenden Schaumstoffen

摘要

1293237 Polyurethane foams FARBENFABRIKEN BAYER AG 13 Nov 1970 [17 Dec 1969] 54086/70 Headings C3C and C3R Polyurethane foams are prepared by reacting, in the presence of a blowing agent and a catalyst for the reaction, a hydroxyl-group containing polyether which contains at least 10% primary OH groups and has a M.W. of 3500 to 10,000 with a biuret-containing polyisocyanate dissolved in a monomeric polyisocyanate at a concentration of 1 to 85% by weight. The polyether is suitably prepared by reacting an alkylene oxide with a compound which contains reactive hydrogen atoms followed by reaction with ethylene oxide to introduce the primary hydroxyl groups. Other compounds having reactive hydrogen atoms may be used in admixture with the polyethers. The biuret containing polyisocyanates are prepared preferably by reacting a monomeric polyisocyanate with water or formic acid, and are then dissolved in monomeric polyisocyanates or are suitably prepared using excess monomeric polyisocyanate in which case the required mixture is produced in one-step. Solutions containing urethane-containing polyisocyanates or isocyanate-containing polyisocyanates as well as the biuret-containing polyisocyanate in monomeric polyisocyanates are particularly suitable. In a typical example a mixture is prepared from a propylene glycol/ trimethylolpropane/ethylene oxide polyether, ethylene glycol, monofluorotrichloromethane, 1 - dimethylaminoethyl - 4 - methylpiperazine and endoethylenepiperazine and is reacted in a closed mould with a biuret-containing polyisocyanate mixture prepared by reacting 2,4- and 2,6-toluylene diisocyanate with water.