Flame retardant polycarbonate compositions, methods of manufacture thereof and articles comprising the same

1. A flame retardant composition comprising:

20 to 80 weight percent of a polycarbonate composition; where the polycarbonate composition comprises a polysiloxane-carbonate copolymer;

an impact modifier in an amount of 0.5 to 25 weight percent; and

1 to 20 weight percent of a phosphazene compound; where all weight percents are based on the total weight of the flame retardant composition.

2. The flame retardant composition of claim 1 , comprising 1 to 15 weight percent of the phosphazene compound.

3. The flame retardant composition of claim 1 , where the polycarbonate composition comprises a polycarbonate having a weight average molecular weight of 15,000 to 40,000 Daltons.

4. The flame retardant composition of claim 1 , where the polycarbonate composition further comprises a copolyestercarbonate; where the copolyestercarbonate comprises a polyester derived from a reaction between sebacic acid and bisphenol A and a polycarbonate derived from a reaction between bisphenol A and phosgene.

5. The flame retardant composition of claim 1 , where the polysiloxane-carbonate copolymer comprises 10 to 20 weight percent of a polysiloxane; and where the polysiloxane-carbonate copolymer is present in an amount of 3 to 25 weight percent, based on the total weight of the flame retardant composition.

6. The flame retardant composition of claim 1 , where the polycarbonate composition comprises a linear polycarbonate, a branched polycarbonate, or a combination of a linear and a branched polycarbonate.

7. The flame retardant composition of claim 1 , where the polycarbonate composition comprises a copolycarbonate; where the copolycarbonate is a copolymer of bisphenol A and a second monomer having a structure represented by the formula (9):

or a structure represented by the formula (10):

8. The flame retardant polycarbonate composition of claim 7 , where the second monomer is present in an amount of 25 to 40 mole percent, and where the copolycarbonate has a weight average molecular weight of 15,000 to 35,000 Daltons.

9. The flame retardant polycarbonate composition of claim 1 , where the impact modifier comprises an elastomer-modified graft copolymer comprising (i) an elastomeric polymer substrate having a T g less than or equal to −10° C. and (ii) a rigid polymeric superstrate grafted to the elastomeric polymer substrate.

10. The flame retardant polycarbonate composition of claim 1 , where the impact modifier is an acrylonitrile-butadiene-styrene, methyl methacrylate butadiene styrene, methacrylate-butadiene, acrylonitrile-styrene-butyl acrylate, methyl methacrylate-acrylonitrile-butadiene-styrene, acrylonitrile-ethylene-propylene-diene-styrene, or a combination thereof.

11. The flame retardant polycarbonate composition of claim 1 , where the phosphazene compound has the structure:

where in the formula (23), m represents an integer of 3 to 25, R 1 and R 2 are the same or different and are independently a hydrogen, a hydroxyl, a C 7-30 aryl group, a C 1-12 alkoxy, or a C 1-12 alkyl.

12. The flame retardant polycarbonate composition of claim 1 , where the phosphazene compound is phenoxy cyclotriphosphazene, octaphenoxy cyclotetraphosphazene, decaphenoxy cyclopentaphosphazene, or a combination comprising at least one of the foregoing phosphazene compounds.

13. The flame retardant polycarbonate composition of claim 1 , where the phosphazene compound has the structure:

where in the formula (24), X 1 represents a —N═P(OPh) 3 group or a —N═P(O)OPh group, Y 1 represents a —P(OPh) 4 group or a —P(O) (OPh) 2 group, Ph represents a phenyl group, n represents an integer from 3 to 10000, R 1 and R 2 are the same or different and are independently a hydrogen, a hydroxyl, a C 7-30 aryl, a C 1-12 alkoxy, or a C 1-12 alkyl.

14. The flame retardant polycarbonate composition of claim 1 , where the phosphazene compound is a crosslinked phenoxyphosphazene.

15. The flame retardant polycarbonate composition of claim 1 , where the phosphazene compound has a structure

where R 1 to R 6 can be the same of different and can be an aryl group, an aralkyl group, a C 1-12 alkoxy, a C 1-12 alkyl, or a combination thereof.

16. The flame retardant polycarbonate composition of claim 1 , where the phosphazene compound has a structure

17. The flame retardant polycarbonate composition of claim 1 , displaying a flame retardancy of V-0 at a sample thickness of at least 0.6 millimeters when tested per a UL-94 protocol.

18. The flame retardant polycarbonate composition of claim 1 , displaying a flame retardancy of at least V-0 at a thickness of 0.6 millimeters when measured as per the UL-94 protocol and an impact strength of greater than or equal to 500 joules per meter, when tested as per ASTM D 256 at 23° C.

19. The flame retardant polycarbonate composition of claim 1 , further comprising bisphenol A diphosphate and resorcinol diphosphate in amounts of 1 to 15 weight percent, based on the total weight of the flame retardant composition.

20. A method comprising:

blending 20 to 80 weight percent of a polycarbonate composition; where the polycarbonate composition comprises a polysiloxane-carbonate copolymer; an impact modifier in an amount of 0.5 to 25 weight percent; and 1 to 20 weight percent of a phosphazene compound to produce a flame retardant composition; where all weight percents are based on the total weight of the flame retardant composition; and

extruding the flame retardant composition.

21. The method of claim 20 , further comprising molding the composition.

22. An article manufactured from the composition of claim 1 .