PROCESS FOR THE PRODUCTION OF FLAME-RESISTANT FOAMS BASED ON ISOCYANATES

摘要

1288688 Polyurethane foams FARBENFABRIKEN BAYER AG 17 Dec 1970 [17 Jan 1970] 59899/70 Headings C3C and C3R Polyurethane foams are prepared by reacting, in the presence of a blowing agent, a polyether polyol which has a M.W. of 750 to 10,000 and in which at least 10% of the hydroxyl groups are primary with an allophanate polyisocyanate which contains at least two NCO groups and at least one N,N1-disubstituted allophanate group and which is dissolved at a concentration of 10 to 70% by weight in one or more liquid polyisocyanates which do not contain allophanate groups. The polyether is suitably prepared by reacting a polyol or polyamine with an alkylene oxide and may be used in admixture with at least one other compound containing reactive hydrogen atoms. The allophanate polyisocyanates are suitably prepared by reacting N-substituted carbamic acid esters which may contain isocyanate groups with mono- and/or polyfunctional isocyanates. Suitably this is achieved by reacting in one stage a hydroxyl containing compound with excess polyisocyanate and heating the first formed reaction product at 100 to 160‹ C. to form the allophanate polyisocyanate which is dissolved in monomeric polyisocyanate if sufficient polyisocyanate has been added. Alternatively the allophanate polyisocyanate may be formed first and then dissolved in a monomeric polyisocyanate in a separate stage. In a typical example, a linear propylene glycol/ propylene oxide/ethylene oxide polyether, 1,4- butylene glycol, water and triethylene diamine are reacted with an isocyanate solution prepared by reacting 2,2-dimethylpropane-1,3-diol with a large excess of toluene-2,4- and -2,6-diisocyanates to first form the bis-carbamic acid ester diisocyanate dissolved in the monomeric diisocyanate which reaction mixture is then heated to 150‹C. to form a solution of allophanatepolyisocyanate in the monomeric diisocyanate. Uses:-Cushioning material, mattresses, packaging, foils for laminates, insulating material, and in construction of motor cars and aircraft.