Thermoplastic polycarbonate compositions with improved hydrolytic stability and electrical tracking resistance and shaped articles thereof

1. A thermoplastic polycarbonate composition comprising:

10 to 30 wt % of a brominated polycarbonate having- a bromine content of 10 to 50 wt %, based on the total weight of the brominated polycarbonate;

10 to 80 wt % of a homopolycarbonate;

optionally, 1 to 60 wt % of an aromatic poly(ester-carbonate) comprising carbonate units derived from bisphenol A, resorcinol, or a combination thereof, and ester units derived from a bisphenol, wherein a molar ratio of carbonate units to ester units ranges from 1:99 to 99:1;

5 to 15 wt % of a core-shell impact modifier;

1 to 10 wt % of an α,β-unsaturated glycidyl ester copolymer impact modifier;

0.01 to 1 wt % of a hydrostabilizer;

optionally, 0.1 to 10 wt % of an additive composition;

wherein the wt % of each component is based on the total weight of the composition, which totals 100 wt %.

2. The thermoplastic polycarbonate composition of claim 1 , wherein a molded sample of the composition

does not show tracking after at least 50 drops of an aqueous 0.1% ammonium chloride solution measured at 300 volts as determined by ASTM D-3638-85,

does not show tracking after at least 50 drops of an aqueous 0.1% ammonium chloride solution measured at 600 volts as determined by ASTM D-3638-85,

having a thickness of 3.2 millimeters has a notched Izod impact of greater than 260 joules per meter at −30° C. according to ASTM D256, and

having a thickness of 3.2 millimeters has a notched Izod impact of greater than 180 joules per meter at −40° C. according to ASTM D256.

3. The thermoplastic polycarbonate composition of claim 1 , wherein a molded sample of the composition

having a thickness of 3.2 millimeters has a heat deflection temperature of at least 123° C. according to ASTM D648 at 1.82 megapascals;

has a UL 94 flame test rating of VO at 1.5 millimeter;

or a combination thereof.

4. The thermoplastic polycarbonate composition of claim 1 , wherein a molded sample of the composition:

retains greater than 85% of a molecular weight after 1000 hours in a hydrolytic chamber at 85° C. and 85% relative humidity;

retains greater than 79% of a molecular weight after 1500 hours in a hydrolytic chamber at 85° C. and 85% relative humidity;

retains greater than 73% of a molecular weight after 2000 hours in a hydrolytic chamber at 85° C. and 85% relative humidity;

retains greater than 62% of a molecular weight after 3000 hours in a hydrolytic chamber at 85° C. and 85% relative humidity;

or a combination thereof.

5. The thermoplastic polycarbonate composition of claim 1 ,

wherein the brominated polycarbonate has a bromine content of 24 to 27.5 wt %, based on the total weight of the brominated polycarbonate.

6. The thermoplastic polycarbonate composition of claim 1 ,

wherein the aromatic poly(ester-carbonate) is present and is a poly(carbonate-bisphenol phthalate ester) comprising 1-50 wt % of aromatic carbonate units and 50-99 wt % of bisphenol phthalate ester units, each based on the sum of the weight of the carbonate units and the bisphenol phthalate ester units.

7. The thermoplastic polycarbonate composition of claim 1 , wherein the aromatic poly(ester-carbonate) is present and has the formula

wherein

a weight ratio of carbonate units x to ester units y is 10:90-45:55, and

the ester units have a molar ratio of isophthalate to terephthalate from 98:2-88:12.

8. The thermoplastic polycarbonate composition of claim 1 , wherein a weight ratio of carbonate units x to ester units y is 75:25-85:15.

9. The thermoplastic polycarbonate composition of claim 1 ,

wherein

the core-shell impact modifier comprises a silicone elastomer core and a methyl(methacrylate) copolymer shell;

the α,βunsaturated glycidyl ester copolymer impact modifier comprises poly(ethylene-co-glycidyl acrylate), poly(ethylene-co-glycidyl methacrylate), poly(ethylene-co-glycidyl methacrylate-co-methyl acrylate), poly(ethylene-co-glycidyl methacrylate-co-ethyl acrylate), poly(ethylene-co-glycidyl methacrylate-co-vinyl acetate), or a combination thereof, preferably, poly(ethylene co glycidyl methacrylate), poly(ethylene co methyl acrylate co glycidyl methacrylate), or a combination thereof;

or a combination thereof.

10. The thermoplastic polycarbonate composition of claim 1 ,

wherein

the homopolycarbonate is:

a bisphenol A homopolycarbonate having a weight average molecular weight from 18,000-35,000 grams/mole; or

a bisphenol A homopolycarbonate having a weight average molecular weight from 25,000-35,000 grams/mole;

or a combination thereof, each as measured via gel permeation chromatography using bisphenol A homopolycarbonate standards.

11. The thermoplastic polycarbonate composition of claim 1 comprising

10 to 30 wt % of a brominated polycarbonate;

10 to 30 wt % of a bisphenol A homopolycarbonate made by an interfacial process;

30 to 60 wt % of a bisphenol A homopolycarbonate made by a melt process;

5 to 15 wt % of a core-shell silicone-(meth)acrylate impact modifier;

1 to 10 wt % of the α,β-unsaturated glycidyl ester copolymer impact modifier; and

0.1 to 1.0 wt % of the epoxy hydrostabilizer;

wherein the wt % of each component is based on the total weight of the composition, which totals 100 wt %.

12. The thermoplastic polycarbonate composition of claim 1 comprising

10 to 30 wt % of the brominated polycarbonate;

20 to 40 wt % of a bisphenol A homopolycarbonate made by a melt process;

20 to 40 wt % of the aromatic poly(ester-carbonate);

5 to 15 wt % of a core-shell silicone-(meth)acrylate impact modifier;

1 to 10 wt % of the α,β-unsaturated glycidyl ester copolymer impact modifier; and

0.1 to 1.0 wt % of the epoxy hydrostabilizer;

wherein the wt % of each component is based on the total weight of the composition, which totals 100 wt %.

13. The thermoplastic polycarbonate composition of claim 1 comprising

10 to 30 wt % of the brominated polycarbonate;

30 to 50 wt % of a bisphenol A homopolycarbonate made by a melt process;

10 to 30 wt % of a bisphenol A homopolycarbonate made by an interfacial process;

35 to 55 wt % of the aromatic poly(ester-carbonate);

5 to 15 wt % of a core-shell silicone-(meth)acrylate impact modifier;

1 to 10 wt % of the α,β-unsaturated glycidyl ester copolymer impact modifier; and

0.1 to 1.0 wt % of the epoxy hydrostabilizer;

wherein the wt % of each component is based on the total weight of the composition, which totals 100 wt %.

14. An article comprising the thermoplastic polycarbonate composition of claim 1 .

15. A method for forming the article according to claim 14 ,

comprising molding, casting, or extruding the composition to provide the article.

16. The thermoplastic polycarbonate composition of claim 1 , wherein the brominated polycarbonate comprises brominated bisphenol A polycarbonate units.

17. The thermoplastic polycarbonate composition of claim 1 , wherein the hydrostabilizer is an epoxy hydrostabilizer.

18. The article of claim 14 , wherein the article is an electrical component.

19. The article of claim 14 , wherein the article is an electrical connector.