Patent ID: 8124665

Claim:
A fire-resistant, flexible, molded, medium density polyurethane foam comprising: a) 10 to 30 parts by weight of at least one polyester polyol having a functionality of from 1.5 to 3.0 and an OH number of from 25 to 250, and which comprises the reaction product of (i) one or more aliphatic dicarboxylic acids, with (ii) one or more diols or triols; b) 5 to 15 parts by weight of at least one highly branched polyether polyol having a functionality of 3.0 to 8.0 and an OH number of 250 to 750 c) 5 to 15 parts by weight of at least one chain extender having a functionality of from 2.0 to 2.9 and an OH number of from 400 to 1900; d) 30 to 55 parts by weight of a polymethylene poly(phenyl isocyanate), an isocyanate group containing prepolymer based on a polymethylene poly(phenyl isocyanate), or mixtures thereof, with said isocyanate component having an NCO group content of from 25 to 33% by weight; e) 10 to 35 parts by weight of solid flame retardant; and f) a sufficient quantity of water to provide blowing to achieve a free rise density from 8 to 20 pcf in the resultant polyurethane foam, with the sum of the parts by weight of components a), b), c), d) and e) totaling 100 parts by weight.