Compositions and articles of manufacture containing branched polycarbonate

1. A composition comprising:

a first polycarbonate, wherein the first polycarbonate comprises

a repeating structural unit of the following formula

wherein at least 60 percent of the total number of R 1 groups contain aromatic groups and the balance thereof are aliphatic or alicyclic groups;

wherein the first polycarbonate was formed in the presence of an end-capping agent and the end-capping agent is not cyanophenol;

wherein the first polycarbonate has a branching level of at least about 2%;

wherein the polycarbonate has a weight average molecular weight of 20,000 g/mole to 54,843 g/mole as measured by gel permeation chromatography using polycarbonate standards; and

wherein the first polycarbonate is prepared by

selecting the branching level, the weight average molecular weight, and the end-capping agent such that the first polycarbonate has a calculated peak melt viscosity of at least 25,000 poise as calculated by a peak melt viscosity equation as follows:

calculated peak melt viscosity=−57135.91+36961.39*BL+14001.13*MW 1/3 −46944.24*pKa−322.51*BL*MW 1/3 −2669.19*BL*pKa+215.83*MW 1/3 *pKa+1125.63*BL 2 −200.11*MW 2/3 +2231.15*pKa 2 ,

wherein BL is determined by dividing a number of moles of branching agent by a total moles of bisphenol from which the first polycarbonate is derived, MW is the weight average molecular weight, and the pKa is the pKa of the end capping agent; and

wherein a molded article of the first polycarbonate has a UL94 V0 rating at a thickness of 1.0 mm;

a flame retardant; and

a second polycarbonate derived from at least bisphenol-A, wherein the second polycarbonate is different from the first polycarbonate;

wherein a molded article of the composition has a UL94 V0 rating at a thickness of 1.5 mm.

2. The composition of claim 1 , wherein the first polycarbonate has a weight average molecular weight of between about 20,000 g/mole to about 40,000 g/mole as measured by gel permeation chromatography using polycarbonate standards.

3. The composition of claim 1 , wherein the end-capping agent has a pKa between about 8.3 and about 11.

4. The composition of claim 1 , wherein the end-capping agent is at least one of the following: phenol and phenol containing one or more substitutions with at least one of the following: an aliphatic group, an olefinic group, an aromatic group, a halogen, an ester group, and an ether group.

5. The composition of claim 4 , wherein the end-capping agent is at least one of the following: phenol, p-t-butylphenol, and p-cumylphenol.

6. The composition of claim 1 , wherein the first polycarbonate of said composition has a branching level of at least about 3%.

7. The composition of claim 1 , wherein the flame retardant is at least one of the following: alkali metal salts of perfluorinated C 1-16 alkyl sulfonates; potassium perfluorobutane sulfonate; potassium perfluoroctane sulfonate; tetraethylammonium perfluorohexane sulfonate; and potassium diphenylsulfone sulfonate.

8. The composition of claim 1 , wherein the composition has a haze value of less than 1.5% at 3.2 mm thickness by ASTM D1003.

9. The composition of claim 1 , wherein the first polycarbonate is derived from bisphenol-A.

10. The composition of claim 1 , wherein the first polycarbonate at least one of the following: a homopolycarbonate derived from a bisphenol; a copolycarbonate derived from more than one bisphenol; and a copolymer derived from one or more bisphenols and containing one or more aliphatic ester units or aromatic ester units or siloxane units.

11. The composition of claim 1 , wherein the second polycarbonate comprises homopolymer derived from bisphenol A.

12. The composition of claim 1 , wherein the second polycarbonate is a polycarbonate copolymer, wherein the polycarbonate copolymer is at least one of the following: polycarbonate-polysiloxane copolymers, and polyester-polycarbonates.

13. The composition of claim 12 , wherein the second polycarbonate comprises copolycarbonate-polyester-polysiloxane terpolymer.

14. The composition of claim 11 , wherein the first polycarbonate has a branching level of at least about 3%.

15. An article comprising the composition of claim 1 .

16. A method of making a composition, comprising:

preparing a first polycarbonate by

selecting a branching level, a desired weight average molecular weight, and an end-capping agent such that the first polycarbonate has a calculated peak melt viscosity of at least 25,000 poise as calculated by a peak melt viscosity equation as follows:

calculated peak melt viscosity=−57135.91+36961.39*BL+14001.13*MW 1/3 −46944.24*pKa−322.51*BL*MW 1/3 −2669.19*BL*pKa+215.83*MW 1/3 *pKa+1125.63*BL 2 −200.11*MW 2/3 +2231.15*pKa 2 ,

wherein BL is determined by dividing a number of moles of branching agent by a total moles of bisphenol from which the first polycarbonate is derived, the MW is the weight-averaged molecular weight of the first polycarbonate and is 20,000 g/mole to 54,843 g/mole as determined by gel permeation chromatography using polycarbonate standards, and the pKa is the pKa of the end capping agent; and

reacting bisphenol, end-capping agent, branching agent, and a carbonate precursor wherein the first polycarbonate has a repeating structural unit of the following formula

wherein at least 60 percent of the total number of R 1 groups contain aromatic groups and the balance thereof are aliphatic or alicyclic groups;

wherein the end-capping agent is not cyanophenol;

wherein the pKa of the end-capping agent is from about 8.3 to about 11; and

wherein a molded article of the first polycarbonate has a UL94 V0 rating at a thickness of 1.0 mm; and

blending with the first polycarbonate a flame retardant and a second polycarbonate derived from at least bisphenol-A different than the first polycarbonate;

wherein a molded article of the composition has a UL94 V0 rating at a thickness of 1.5 mm.

17. The method of claim 16 , wherein the second polycarbonate is a homopolycarbonate derived from bisphenol-A.

18. A method of making an article of manufacture, comprising:

preparing a first polycarbonate by

selecting a branching level, BL, a desired weight average molecular weight, and an end-capping agent such that the first polycarbonate has a calculated peak melt viscosity of at least 25,000 poise is calculated by a peak melt viscosity equation as follows:

calculated peak melt viscosity=−57135.91+36961.39*BL+14001.13*MW 1/3 −46944.24*pKa−322.51*BL*MW 1/3 −2669.19*BL*pKa+215.83*MW 1/3 *pKa+1125.63*BL 2 −200.11*MW 213 +2231.15*pKa 2 ,

wherein BL is determined by dividing a number of moles of branching agent by a total moles of bisphenol from which the first polycarbonate is derived, the MW is the weight-averaged molecular weight of the first polycarbonate and is 20,000 g/mole to 54,843 g/mole as determined by gel permeation chromatography using polycarbonate standards, and the pKa is the pKa of the end capping agent;

reacting the bisphenol, the end-capping agent, the branching agent, and a carbonate precursor, wherein the first polycarbonate comprises a repeating structural unit of the following formula

wherein at least 60 percent of the total number of R 1 groups contain aromatic groups and the balance thereof are aliphatic or alicyclic groups;

wherein the end-capping agent that is not cyanophenol;

wherein an article made from the first polycarbonate has a UL94 V0 rating at a thickness of 1.0 mm;

blending with the first polycarbonate, a flame retardant, and a second polycarbonate derived from at least bisphenol-A different than the first polycarbonate to form the composition; and

forming the composition into the article;

wherein an article made from the composition has a UL94 V0 rating at a thickness of 1.5 mm.

19. The method of claim 18 , wherein the second polycarbonate comprises a bisphenol A homopolymer.