Flame-retardant flexible polyurethane foam
A flexible polyurethane foam-forming composition and the flexible polyurethane foam obtained therefrom contain, as flame-retardant additive, a halogen-free phosphonate compound which is substantially unreactive for isocyanate, contains at least about 5 weight percent phosphorus, has an acid value of about 2 mg KOH/g or less, a volatility as measured by thermogravimetric analysis not exceeding a 5.0 percent weight loss at a temperature of about 150° C., and a weight average molecular weight of from about 200 to about 2000.
1. A flexible polyurethane foam-forming composition which, under polyurethane foam-forming conditions, provides a flame-retardant flexible polyurethane foam, the composition comprising:
a) at least one polyol;
b) at least one polyisocyanate;
c) at least one blowing agent;
d) at least one catalyst for the polyurethane-forming reaction;
e) at least one halogen-free flame retardant phosphonate compound of the general formula
wherein R 1 and R 2 each independently is an alkyl, cycloalkyl, phenyl or alkyl-substituted phenyl group of up to about 8 carbon atoms or are joined together with their respective oxygen atoms and the phosphorus atom to form a heterocyclic ring having 6 ring members; R 3 is a straight or branched chain alkylene group of from 2 to 4 carbon atoms in the main chain; Z is —C(O)O—; R 4 is a hydrocarbon residue of from 2 to 4 carbon atoms and, n is 2.
2. The flexible polyurethane foam-forming composition of claim 1 wherein halogen-free flame retardant phosphonate compound (e) is at least one member of the group consisting of:
3. The flexible polyurethane foam-forming composition of claim 1 containing at least one other flame retardant additive.
4. The flexible polyurethane foam-forming composition of claim 3 wherein the other flame retardant additive is at least one compound selected from the group consisting of phosphate ester and phosphate-phosphonate.
5. The fire-retardant flexible polyurethane foam obtained from the flexible polyurethane foam-forming composition of claim 1 .
6. The fire-retardant flexible polyurethane foam obtained from the flexible polyurethane foam-forming composition of claim 2 .
7. The fire-retardant flexible polyurethane foam obtained from the flexible polyurethane foam-forming composition of claim 3 .
8. The fire-retardant flexible polyurethane foam obtained from the flexible polyurethane foam-forming composition of claim 4 .