Flame retardants for plastic foams

A polyurethane foam composition formed by reacting, in an NCO/OH index ranging from 1/1 to 5/4, one or more compounds having reactive-NCO groups with one or more polyol having reactive --OH groups;

• the polyurethane foam composition containing, by weight, 0.5 to 25 percent, based on the total weight of the foam compositions, of a flame retardant material represented by the formula:
• ##EQU7## wherein R.sup.1 is a divalent group selected from alkyl, alkoxy, cycloalkyl, cycloalkoxy, aryl an ester represented by the formula ##EQU8## wherein each R.sup.3 is alkyl, alkoxy, cycloalkyl, cycloalkoxy or aryl, each R.sup.3 having 1 to 20 carbon atoms, or an ether represented by the formula R.sup.3 -- O -- R.sup.3 wherein R.sup.3 is as defined above, or a combination thereof, each radical having from 1 to 20 carbon atoms;
• each R.sup.2 is an alkyl radical having 1 to 20 carbon atoms, each X is chlorine, bromine, fluorine or iodine;
• one of Y is phosphorus and the other Y is silicon and each m is the integer 2 when Y is phosphorus and the integer 3 when Y is silicon.