Flame retardant polycarbonate compositions, methods of manufacture thereof and articles comprising the same
Disclosed herein is a flame retardant composition comprising 10 to 90 weight percent of a linear polycarbonate; a branched polycarbonate; 10 to 70 weight percent of a polysiloxane-polycarbonate copolymer; and 1 to 20 weight percent of a phosphazene compound; were all weight percents are based on the total weight of the composition. Disclosed herein too is a method comprising blending 10 to 90 weight percent of a linear polycarbonate; a branched polycarbonate; 10 to 70 weight percent of a polysiloxane-polycarbonate copolymer; and 1 to 20 weight percent of a phosphazene compound; to form a flame retardant composition; were all weight percents are based on the total weight of the composition.
1. A flame retardant composition comprising:
10 to 90 weight percent of a linear polycarbonate;
a branched polycarbonate;
10 to 70 weight percent of a polysiloxane-polycarbonate copolymer; where the polysiloxane-polycarbonate copolymer comprises 10 weight percent or less of polysiloxane having a weight average molecular weight of less than 30,000 Daltons; and
1 to 20 weight percent of a phosphazene compound; were all weight percents are based on the total weight of the composition.
2. The composition of claim 1 , where transmissivity in a visible wavelength region of greater than 75% for a sample thickness of 0.1 to 3.0 millimeter when measured as per ASTM D 1003.
3. The composition of claim 1 , where transmissivity in a visible wavelength region of greater than 95% for a sample thickness of 0.1 to 3.0 millimeter when measured as per ASTM D 1003.
4. The composition of claim 1 , where the linear polycarbonate is derived from bisphenol A polycarbonate and where the linear polycarbonate has a weight average molecular weight of 15,000 to 60,000 Daltons as determined by a polycarbonate standard.
5. The composition of claim 4 , where the linear polycarbonate is derived from a blend of two linear polycarbonate homopolymers, where one linear polycarbonate homopolymer has a higher molecular weight that the other linear polycarbonate homopolymer.
6. The composition of claim 1 , where the branched polycarbonate is present in an amount of 10 to 50 weight percent, based on a total weight of the flame retardant composition.
7. The composition of claim 1 , where the polysiloxane-polycarbonate copolymer comprises 8 weight percent or less of polysiloxane having a weight average molecular weight of less than 30,000 Daltons.
8. The composition of claim 1 , where the phosphazene compound is present in an amount of 3 to 10 wt %, based on a total weight of the flame retardant composition.
9. The composition of claim 1 , where the phosphazene compound has the structure of formula (16)
where in the formula (16), m represents an integer of 3 to 25, and Ph represents a phenyl group, R 1 and R 2 are the same or different and are independently a hydrogen, a hydroxyl, a C 1-12 alkoxy, or a C 1-12 alkyl.
10. The composition of claim 8 , where the phosphazene compound is phenoxy cyclotriphosphazene, octaphenoxy cyclotetraphosphazene, decaphenoxy cyclopentaphosphazene, or a combination comprising at least one of the foregoing phosphazene compounds.
11. The composition of claim 1 , where the phosphazene compound has the structure of formula (17)
where in the formula (17), 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, n represents an integer from 3 to 10000, Ph represents a phenyl group, R1 and R2 are the same or different and are independently a hydrogen, a halogen, a C 1-12 alkoxy, or a C 1-12 alkyl.
12. The composition of claim 1 , where the phosphazene compound is a crosslinked phenoxyphosphazene.
13. The composition of claim 1 , where the polysiloxane-polycarbonate copolymer has the structure shown in the Formula (15) below:
where x is 1 to 45, y is 1 to 90 and z is 1 to 90.
14. The composition of claim 13 , where the polysiloxane-polycarbonate copolymer is present in an amount of greater than 30 wt %, based on the total weight of the composition.
15. The composition of claim 14 , further comprising an antidrip agent, talc or a combination thereof.
16. The composition of claim 1 , where the composition has a flame retardancy of V-0 at a thickness of 0.3 millimeter or lower when measured as per a UL-94 protocol.
17. The composition of claim 1 , where the composition has a flame retardancy of V-0 at a thickness of 0.4 millimeter or lower when measured as per a UL-94 protocol.
18. The composition of claim 1 , where the composition has a flame retardancy of V-0 at a thickness of 0.8 millimeter or lower when measured as per a UL-94 protocol.
19. The composition of claim 1 , where the composition has a flame retardancy of V-0 at a thickness of 1.2 millimeter or lower when measured as per a UL-94 protocol.
20. The composition any one of claims 1 , where the composition has a flame retardancy of V-0 at a thickness of 1.5 millimeter or lower when measured as per a UL-94 protocol.
21. The composition any one of claims 1 , where the composition does not contain a flame retardant other than the phosphazene compound.
22. A method comprising:
blending 10 to 90 weight percent of a linear polycarbonate;
a branched polycarbonate;
10 to 70 weight percent of a polysiloxane-polycarbonate copolymer; where the polysiloxane-polycarbonate copolymer comprises 10 weight percent or less of polysiloxane having a weight average molecular weight of less than 30,000 Daltons; and
1 to 20 weight percent of a phosphazene compound; to form a flame retardant composition; were all weight percents are based on the total weight of the composition.
23. The method of claim 22 , where the blending is conducted in an extruder.
24. The method of claim 21 , further comprising injection molding the flame retardant composition.
25. An article manufactured from the composition of claim 1 .