Flame-retardant polyurethane foam compositions

In a process for the in situ preparation of a flexible, nonlustrous, substantially membrane-free polyurethane foam from a reaction mixture comprising one or more polyols selected from the group consisting of polyester polyols and polyether polyols, an organic polyisocyanate, water, a hydrophilic organosilicon foam-stabilizing emulsifier-surfactant designed and adapted for use in the preparation of urethane polymer foam from a polyether polyol and an organic polyisocyanate, and a cell-opener selected from the group consisting of hydrophobic anti-foaming organosilicon compounds, and esters of the formula (RCOO).sub.n R', R and R' in the preceding formula being alkyl or alkenyl groups having from 1 to 30 carbon atoms, at least one of R and R' having at least 3 carbon atoms and n being an integar from one to three, with the proviso that when n is one at least one of R and R' has at least 8 carbon atoms, the amount of cell opener being from about 0.1 to about 3 parts by weight of hydrophobic anti-foaming organosilicon compound or from about 2 to about 10 parts per weight of ester of the formula (RCOO).sub.n R' per 100 parts total weight of said polyols, the improvement which comprises including in the reaction mixture a flame-retarding amount of tribromoneopentyl alcohol whereby a permanently flame-retardant open-cell foam is obtained.