Polycarbonate compositions with thin-wall flame retardance

1. A composition comprising:

(a) a polycarbonate/siloxane component, said polycarbonate/siloxane component being a polycarbonate siloxane copolymer, or a mixture of a polycarbonate siloxane copolymer and polycarbonate resin;

(b) a mineral filler selected from the group consisting of clay, tale, wollastonite and combinations thereof; and

(c) a flame retardant component consisting of a phosphate-based flame retardant;

wherein the composition comprises at least 50% by weight of polycarbonate taking into account the polycarbonate portion of the polycarbonate siloxane copolymer and any polycarbonate resin and from 1 to 20% of the mineral filler; and wherein the amounts of polycarbonate siloxane copolymer, mineral filler and flame retardant are effective to provide a composition with a UL94 V0 rating at a thickness of 0.8 mm, a notched Izod impact strength or of 25 k-cm/cm or greater and a flexural modulus of 29,000 kg/cm 2 or greater.

2. The composition according to claim 1 , wherein the siloxane in the polycarbonate/siloxane components is present in an amount of from 0.5 to 6% by weight of the total composition.

3. The composition of claim 2 , wherein the siloxane in the polycarbonate siloxane copolymer is polydimethylsiloxane.

4. The composition of claim 2 wherein the siloxane in the polycarbonate/siloxane components is present in an amount of from 1 to 4% by weight of the total composition.

5. The composition of claim 1 , wherein the composition further comprises an additional thermoplastic that is not a polycarbonate.

6. The composition of claim 5 , wherein the additional thermoplastic is selected from the group consisting of polymers including as structural components aromatic vinyl monomers, polymers including as structural components aromatic vinyl monomers and a vinyl cyanide monomers, polymers including as structural component an aromatic vinyl monomers, a vinyl cyanide monomers and a rubber like polymer; aromatic polyesters, polyphenylene ethers, polyether imides, and polyphenylene sulfides.

7. The composition of claim 6 , wherein the additional thermoplastic is an ABS rubber.

8. The composition of claim 7 , wherein the siloxane in the polycarbonate siloxane copolymer is polydimethylsiloxane.

9. The composition of claim 7 , wherein the siloxane in the polycarbonate/siloxane components is present in an amount of from 0.5 to 6% by weight of the total composition.

10. The composition of claim 1 , wherein the composition comprises a polycarbonate resin and therein the polycarbonate resin comprises linear and branched polycarbonates.

11. The composition according to claim 10 , wherein the siloxane in the polycarbonate/siloxane components is present in an amount of from 0.5 to 6% by weight of the total composition.

12. The composition of claim 11 , wherein the siloxane in the polycarbonate siloxane copolymer is polydimethylsiloxane.

13. The composition of claim 11 , wherein the siloxane in the polycarbonate/siloxane components is present in an amount of from 1 to 4% by weight of the total composition.

14. The composition of claim 10 , wherein the composition further comprises an additional thermoplastic that is not a polycarbonate.

15. The composition of claim 14 , wherein the additional thermoplastic is selected from the group consisting of polymers including as structural components aromatic vinyl monomers, polymers including as structural components aromatic vinyl monomers and a vinyl cyanide monomers, polymers including as structural component an aromatic vinyl monomers, a vinyl cyanide monomers and a rubber like polymer; aromatic polyesters, polyphenylene ethers, polyether imides, and polyphenylene sulfides.

16. The composition of claim 15 , wherein the additional thermoplastic is an ABS rubber.

17. The composition of claim 16 , wherein the siloxane in the polycarbonate siloxane copolymer is polydirnethylsiloxane.

18. The composition of claim 17 , wherein the siloxane in the polycarbonate/siloxane components is present in an amount of from 1 to 4% by weight of the total composition.

19. The composition of claim 1 , wherein the phosphate-based flame retardant is present in an amount of from 0.1 to 10% by weight of the total composition.

20. The composition according to claim 19 , wherein the siloxane in the polycarbonate/siloxane components is present in an amount of from 0.5 to 6% by weight of the total composition.

21. The composition of claim 20 , wherein the siloxane in the polycarbonate siloxane copolymer is polydimethylsiloxane.

22. The composition of claim 20 , wherein the siloxane in the polycarbonate/siloxane components is present in an amount of from 1 to 4% by weight of the total composition.

23. The composition of claim 19 , wherein the composition further comprises an additional thermoplastic that is not a polycarbonate.

24. The composition of claim 23 , wherein the additional thermoplastic is selected from the group consisting of polymers including as structural components aromatic vinyl monomers, polymers including as structural components aromatic vinyl monomers and a vinyl cyanide monomers, polymers including as structural component an aromatic vinyl monomers, a vinyl cyanide monomers and a rubber like polymer, aromatic polyesters, polyphenylene ethers, polyether imides, and polyphenylene sulfides.

25. The composition of claim 24 , wherein the additional thermoplastic is an ABS rubber.

26. The composition of claim 25 , wherein the siloxane in the polycarbonate siloxane copolymer is polydimethylsiloxane.

27. The composition of claim 25 , wherein the siloxane in the polycarbonate/siloxane components is present in an amount of from 0.5 to 6% by weight of the total composition.

28. The composition of claim 19 , wherein the composition comprises a polycarbonate resin and therein the polycarbonate resin comprises linear and branched polycarbonates.

29. The composition of claim 1 , wherein the composition comprises at least 60by weight of polycarbonate, taking into account the polycarbonate portion of the polycarbonate siloxane copolymer and any polycarbonate resin.

30. The composition of claim 1 , wherein the composition comprises at least 65by weight of polycarbonate, taking into account the polycarbonate portion of the polycarbonate siloxane copolymer and any polycarbonate resin.

31. The composition of claim 1 , wherein the polycarbonate/siloxane component contains both a polycarbonate siloxane copolymer and a polycarbonate resin.

32. A method for forming an article comprising the steps of:

preparing a composition comprising:

(a) a polycarbonate/siloxane component, said polycarbonate/siloxane component being a polycarbonate siloxane copolymer, or a mixture of a polycarbonate siloxane copolymer and polycarbonate resin:

(b) a mineral filler consisting of a material selected from the group consisting of clay, tale, wollastonite and combinations thereof; and

(c) a flame retardant component consisting of a phosphate-based flame retardant;

wherein the composition composes at least 50% by weight of polycarbonate taking into account the polycarbonate portion of the polycarbonate siloxane copolymer and any polycarbonate resin and from 1 to 20% by weight of the mineral filler, and wherein the amounts of polycarbonate siloxane copolymer, mineral filler and flame retardant are effective to provide a composition with a UL94 V0 rating at a thickness of 0.8 mm, a notched Izod impact strength or of 25 k-cm/cm or greater and a flexural modulus of 29,000 kg/cm 2 or greater, and

forming the composition into a thin-walled article by injection molding or extrusion.

33. The method according to claim 32 , wherein the siloxane in the polycarbonate/siloxane components is present in an amount of from 0.5 to 6% by weight of the total composition.

34. The method of claim 33 , wherein the siloxane in the polycarbonate siloxane copolymer is polydimethylsiloxane.

35. The method of claim 33 , wherein the siloxane in the polycarbonate/siloxane components is present in an amount of from 1 to 4% by weight of the total composition.

36. The method of claim 32 , wherein the composition further comprises an additional thermoplastic that is not a polycarbonate.

37. The method of claim 36 , wherein the additional thermoplastic is selected from the group consisting of polymers including as structural components aromatic vinyl monomers, polymers including as structural components aromatic vinyl monomers and a vinyl cyanide monomers, polymers including as structural component an aromatic vinyl monomers, a vinyl cyanide monomers and a rubber like polymer, aromatic polyesters, polyphenylene ethers, polyether imides, and polyphenylene sulfides.

38. The method of claim 37 , wherein the additional thermoplastic is an ABS rubber.

39. The method of claim 38 , wherein the siloxane in the polycarbonate siloxane copolymer is polydimethylsiloxane.

40. The method of claim 32 , wherein the composition comprises a polycarbonate resin and therein the polycarbonate resin comprises linear and branched polycarbonates.

41. The method according to claim 40 , wherein the siloxane in the polycarbonate/siloxane components is present in an amount of from 0.5 to 6% by weight of the total composition; and the mineral filler is present in an amount of from 1 to 20% by weight of the total composition.

42. The method of claim 41 , wherein the siloxane in the polycarbonate siloxane copolymer is polydimethylsiloxane.

43. The method of claim 32 , wherein the phosphate-based flame retardant is present in an amount of from 0.1 to 10% by weight of the total composition.

44. The method of claim 43 , wherein the siloxane in the polycarbonate/siloxane components is present in an amount of from 0.5 to 6% by weight of the total composition; and the mineral filler is present in an amount of from 1 to 20% by weight of the total composition.

45. The method of claim 44 , wherein the siloxane in the polycarbonate siloxane copolymer is polydimethylsiloxane.

46. The method of claim 44 , wherein the siloxane in the polycarbonate/siloxane components is present in an amount of from 1 to 4% by weight of the total composition.

47. The method of claim 32 , wherein the composition further comprises an additional thermoplastic that is not a polycarbonate.

48. The method of claim 47 , wherein the additional thermoplastic is selected from the group consisting of polymers including as structural components aromatic vinyl monomers, polymers including as structural components aromatic vinyl monomers and a vinyl cyanide monomers, polymers including as structural component an aromatic vinyl monomers, a vinyl cyanide monomers and a rubber like polymer, aromatic polyesters, polyphenylene ethers, polyether imides, and polyphenylene sulfides.

49. The method of claim 48 , wherein the additional thermoplastic is an ABS rubber.

50. The method of claim 49 , wherein the siloxane in the polycarbonate siloxane copolymer is polydimethylsiloxane.

51. The method of claim 49 , wherein the siloxane in the polycarbonate/siloxane components is present in an amount of from 0.5 to 6% by weight of the total composition.

52. The method of claim 32 , wherein the composition comprises a polycarbonate resin and therein the polycarbonate resin comprises linear and branched polycarbonates.

53. A thin walled article formed by the method of claim 32 .

54. A thin walled article formed by the method of claim 32 , wherein the article is formed by injection molding and has a minimum wall thickness of 1.2 mm.

55. A thin walled article formed by the method of claim 32 , wherein the article is formed by extrusion and has a minimum wall thickness of 2 mm.

56. The composition of claim 1 , wherein the mineral filler consists of a material selected from the group consisting of clay, tale, wollastonite and combinations thereof.

57. The method of claim 32 , wherein the mineral filler consists of a material selected from the group consisting of clay, tale, wollastonite and combinations thereof.