Production of a polycarbonate with limited metal residuals

1. A method for producing a polycarbonate comprising:

reacting a diaryl carbonate with a dihydroxy compound to form a polycarbonate,

wherein the polycarbonate comprising a metal contaminant comprises:

less than or equal to 500 ppb of molybdenum based on the total weight of the diaryl carbonate and the metal contaminant;

less than or equal to 33 ppb of vanadium based on the total weight of the diaryl carbonate and the metal contaminant;

less than or equal to 33 ppb of chromium based on the total weight of the diaryl carbonate and the metal contaminant;

less than or equal to 75 ppb of titanium based on the total weight of the diaryl carbonate and the metal contaminant;

less than or equal to 375 ppb of niobium based on the total weight of the diaryl carbonate and the metal contaminant;

less than or equal to 33 ppb of nickel based on the total weight of the diaryl carbonate and the metal contaminant;

less than or equal to 750 ppb of zirconium based on the total weight of the diaryl carbonate and the metal contaminant; and

less or equal to 10 ppb iron based on the total weight of the diaryl carbonate and the metal contaminant.

2. The method of claim 1 , wherein the polycarbonate comprises less than or equal to 20 ppb vanadium and/or less than or equal to 20 ppb chromium and/or less than or equal to 20 ppb titanium and/or less than or equal to 20 ppb nickel and/or less than or equal to 10 ppb zirconium and/or less than or equal to 20 ppb niobium and/or less than or equal to 5 ppb iron.

3. The method of claim 1 , wherein the diaryl carbonate comprises diphenyl carbonate.

4. The method of claim 1 , wherein the dihydroxy compound is of the formula HO—R 1 —OH, wherein R 1 is a C 6-30 aromatic group.

5. The method of claim 1 , wherein the polycarbonate has a yellowness index of less than or equal to 3 as determined by ASTM D1925, after 2 hours of aging at 250° C.

6. The method of claim 1 , further comprising preparing the diaryl carbonate.

7. The method of claim 6 , wherein the preparing comprises the step of decarbonylating a diaryl oxalate in the presence of a decarbonylation catalyst.

8. The method of claim 7 , wherein the diaryl oxalate has the formula: ArO(C═O)—(C═O)OAr, where each Ar independently is an aromatic hydrocarbon group having 6 to 14 carbon atoms.

9. The method of claim 6 , wherein the preparing comprises the reacting an aromatic hydroxy compound and carbon monoxide in the presence of oxygen and a catalyst.

10. The method of claim 6 , wherein the preparing comprises reacting an aromatic hydroxy compound with phosgene in the presence of a transesterification catalyst.

11. The method of claim 6 , wherein the preparing comprises reacting an aromatic hydroxy compound with a dialkyl carbonate in the presence of a transesterification catalyst.

12. The method of claim 9 , wherein the aromatic hydroxy compound has the formula (III)

wherein n is an integer 1 to 3 and each R 2 is independently a C 1-34 alkyl, a C 1-34 alkoxy, a C 5-34 cycloalkyl, a C 7-34 alkylaryl, a C 6-34 aryl, a halogen radical, or —COO—R′, wherein R′ is H, a C 1-34 alkyl, C 1-34 alkoxy, C 5-34 cycloalkyl, C 7-34 alkylaryl, or C 6-34 aryl.

13. The method of claim 1 , wherein the diaryl carbonate has the formula (I)

wherein n is an integer 1 to 3 and each R 2 is independently, a C 1-34 alkyl, a C 1-34 alkoxy, a C 5-34 cycloalkyl, a C 7-34 alkylaryl; a C 6-34 aryl; a halogen radical, or —COO—R′, wherein R′ is H, a C 1-34 alkyl, a C 1-34 alkoxy, a C 5-34 cycloalkyl, a C 7-34 alkylaryl; or a C 6-34 aryl.

14. The method of claim 1 , further comprising adding the diaryl carbonate and the dihydroxy compound to a polymerization unit before reacting, wherein the diaryl carbonate and/or the dihydroxy compound is added to the polymerization unit as a mixture with acetone.

15. The method of claim 1 , wherein the dihydroxy compound is bisphenol A, and further comprising forming the dihydroxy compound by:

reacting phenol with acetone in the presence of a sulfur containing promoter to obtain a reaction mixture comprising bisphenol A, phenol, and the promoter;

after reacting the phenol with the acetone, cooling the reaction mixture to form a crystal stream comprising crystals of bisphenol A and phenol;

separating the crystals from the crystal steam; melting the crystals to form a molten stream of bisphenol A, phenol, and sulfur;

contacting the molten stream with a base to reduce a sulfur concentration in the molten stream and form a reduced sulfur stream; and

removing phenol from the reduced sulfur stream to form a bisphenol A product.

16. The method of claim 15 , further comprising:

prior to forming the crystal stream, cooling the reaction mixture to form an initial crystal stream comprising initial crystals of bisphenol A and phenol;

separating the initial crystals from the initial crystal steam;

melting the initial crystals to form an initial molten stream; and

then performing the cooling to form the crystal steam in accord with Embodiment 25.

17. The method of claim 1 , further comprising extruding the polycarbonate, wherein phosphorous acid is added to the extruder.

18. The polycarbonate made by the method of claim 1 .

19. A diaryl carbonate comprising a metal contaminant comprising:

less than or equal to 500 ppb of molybdenum based on the total weight of the diaryl carbonate and the metal contaminant;

less than or equal to 33 ppb of vanadium based on the total weight of the diaryl carbonate and the metal contaminant;

less than or equal to 33 ppb of chromium based on the total weight of the diaryl carbonate and the metal contaminant;

less than or equal to 75 ppb of titanium based on the total weight of the diaryl carbonate and the metal contaminant;

less than or equal to 375 ppb of niobium based on the total weight of the diaryl carbonate and the metal contaminant;

less than or equal to 33 ppb of nickel based on the total weight of the diaryl carbonate and the metal contaminant;

less than or equal to 10 ppb of zirconium based on the total weight of the diaryl carbonate and the metal contaminant; and

less or equal to 10 ppb iron based on the total weight of the diaryl carbonate and the metal contaminant.

20. The diaryl carbonate of claim 19 , wherein the diaryl carbonate comprises less than 20 ppb of vanadium based on the total weight of the diaryl carbonate and any metal contaminant.

21. A method for producing a polycarbonate comprising: reacting a diaryl carbonate with a dihydroxy compound to form a polycarbonate, wherein the polycarbonate comprises: less than or equal to 1,000 ppb of molybdenum; less than or equal to 33 ppb of vanadium; less than or equal to 33 ppb of chromium; less than or equal to 33 ppb of nickel; and less or equal to 10 ppb iron.

22. A method for producing a polycarbonate comprising:

selecting a diaryl carbonate based on a maximum contaminant content and reacting the diaryl carbonate with a dihydroxy compound to form a melt polycarbonate comprising a metal contaminant comprising less than or equal to 500 ppb of molybdenum based on the total weight of the diaryl carbonate and the metal contaminant; less than or equal to 33 ppb of vanadium based on the total weight of the diaryl carbonate and the metal contaminant; less than or equal to 33 ppb of chromium based on the total weight of the diaryl carbonate and the metal contaminant; less than or equal to 75 ppb of titanium based on the total weight of the diaryl carbonate and the metal contaminant; less than or equal to 375 ppb of niobium based on the total weight of the diaryl carbonate and the metal contaminant; less than or equal to 33 ppb of nickel based on the total weight of the diaryl carbonate and the metal contaminant; less than or equal to 10 ppb of zirconium based on the total weight of the diaryl carbonate and the metal contaminant; and less or equal to 10 ppb iron based on the total weight of the diaryl carbonate and the metal contaminant; wherein the reacting occurs in at least one reactor, and wherein the reactor comprises a reactor contaminant.