Patent ID: 8722551

Claim:
A flame retardant composition comprising a phosphorous-containing polymer, the phosphorous-containing polymer being produced by: (a) reacting a reactant mixture in a condensation reaction to produce a precondensate compound, the reactant mixture comprising a phosphonium compound and a nitrogen-containing compound, wherein: (i) the phosphonium compound conforms to the structure of Formula (I) wherein R 1 is selected from the group consisting of hydrogen, C 1 -C 3 alkyl, C 1 -C 3 haloalkyl, C 2 -C 3 alkenyl, and C 2 -C 3 haloalkenyl; X is an anion selected from the group consisting of chloride, sulfate, hydrogen sulfate, phosphate, acetate, carbonate, bicarbonate, borate, and hydroxide; b is the charge of the anion X; and a is equal to (−b); and (ii) the nitrogen-containing compound conforms to the structure of Formula (II) wherein R 2 , R 3 , R 4 , R 5 , R 6 , and R 7 are independently selected from the group consisting of hydrogen, hydroxymethyl, and alkoxymethyl; (b) reacting the precondensate compound from (a) and a cross-linking composition in a condensation reaction to produce a phosphorous-containing intermediate polymer, the cross-linking composition comprising an alkylene urea compound selected from the group consisting of ethylene urea, propylene urea, and mixtures thereof; and (c) reacting the phosphorous-containing intermediate polymer from (b) with an oxidizing agent to produce the phosphorous-containing polymer, wherein the phosphorous-containing intermediate polymer is reacted with the oxidizing agent under conditions sufficient to convert at least a portion of the phosphorous atoms in the phosphorous-containing intermediate polymer to a pentavalent state.