Blends of (alkyl substituted) triaryl phosphate esters with phosphorus-containing flame retardants for polyurethane foams

A flame retardant additive for use in flame retarding a flexible polyurethane foam reaction mixture including at least one polyol and at least one isocyanate, the flame retardant additive comprising:

• an (alkyl substituted) triaryl phosphate ester;
• and
• a phosphorus-containing flame retardant having at least about 5 wt. % phosphorus and including at least one monomeric phosphorus-containing compound or dimeric phosphorus-containing compound, wherein the combined weight of the (alkyl substituted) triaryl phosphate ester and the phosphorus-containing flame retardant comprises about 5 to about 40% by weight of the polyol.

A method of making flame retarded flexible polyurethane compositions comprising the step of:

• adding to a flexible polyurethane foam reaction mixture about 5 to about 40% by weight of polyol of a flame retardant additive comprising:
• an (alkyl substituted) triaryl phosphate ester;
• and a phosphorus-containing flame retardant having at least about 5 wt. % phosphorus and including at least one monomeric phosphorus-containing compound or dimeric phosphorus-containing compound.