Alkylphenol-terminated copolycarbonates, processes for preparing the same, molding compositions containing the same, and articles prepared therefrom

1. Copolycarbonates comprising: (i) a chain terminator structural unit of the formula (1):

wherein R1 and R2 each independently represent hydrogen or a C 1-18 -alkyl, with the proviso that R1 and R2 are not simultaneously hydrogen; (ii) at least one diphenol unit of the formula (2)

wherein R 3 represents a C 1-4 -alkyl, R 4 represents hydrogen or C 1 -C 4 -alkyl, and n represents 0, 1, 2 or 3; and (iii) at least one dihydroxyaryl compound of the formula (3)

HO—Z—OH  (3)

wherein Z represents a radical of the formula (3a)

wherein each R 6 and each R 7 independently represents a moiety selected from the group consisting of H, C 1 -C 18 -alkyls, C 1 -C 18 -alkoxys, halogens, optionally substituted aryls or aralkyls, and X represents a moiety selected from the group consisting of —SO 2 —, —CO—, C 1 - to C 6 -alkylenes, C 2 - to C 5 -alkylidenes and C 6 - to C 12 -arylenes, optionally condensed with further aromatic rings containing hetero atoms;

wherein the copolycarbonates have an inhomogeneity factor of: A) 1.3 to 2.5, when the copolycarbonates have a content of ≧50 mol % and <100 mol % of the at least one diphenol unit of the formula (2), based on total diphenols, and have an average molecular weight (weight-average) of 18,000 to 35,000 g/mol; and B) 1.2 to 2.4, when the copolycarbonates have a content of greater than 0 and less than 50 mol % of the at least one diphenol unit of the formula (2), based on total diphenols, and have an average molecular weight (weight-average) of 16,000 to 35,000 g/mol.

2. The copolycarbonates according to claim 1 , wherein one of R1 and R2 represents a hydrogen and the other represents a tert-butyl substituent.

3. The copolycarbonates according to claim 1 , wherein chain terminator structural unit of the formula (1) comprises a p-tert-butylphenol residue.

4. The copolycarbonates according to claim 1 , wherein the at least one diphenol unit of the formula (2) comprises a 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane residue.

5. The copolycarbonates according to claim 3 , wherein the at least one diphenol unit of the formula (2) comprises a 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane residue.

6. The copolycarbonates according to claim 1 , wherein the copolycarbonates have an inhomogeneity factor of: A) 1.4 to 2.3, when the copolycarbonates have a content of ≧50 mol % and <100 mol % of the at least one diphenol unit of the formula (2), based on total diphenols, for linear copolycarbonates having an average molecular weight (weight-average) of 18,000 to 35,000 g/mol; and B) 1.2 to 2.0, when the copolycarbonates have a content of greater than 0 and less than 50 mol % of the at least one diphenol unit of the formula (2), based on total diphenols, for linear copolycarbonates having an average molecular weight (weight-average) of 16,000 to 35,000 g/mol.

7. The copolycarbonates according to claim 1 , having a general structure according to the formula:

wherein each R independently represents a C 1 -C 4 -alkyl, x and y each independently represent a number of 0 to 1 and the sum of x+y=1, and n is determined by molecular weight of the copolycarbonates.

8. The copolycarbonates according to claim 7 , wherein each R represents a methyl group, and x and y each independently represent a number of 0.02 to 0.98.

9. A composition comprising copolycarbonates according to claim 1 and at least one additive selected from the group consisting of heat stabilizers, mould release agents, UV stabilizers, and combinations thereof.

10. The composition according to claim 9 , wherein the at least one additive comprises a compound selected from the group consisting of tris-(2,4-di-tert-butylphenyl) phosphite, tetrakis(2,4-di-tert-butylphenyl)[1,1-biphenyl]-4,4′-diyl-bisphosphonite, trisoctylphosphate, octadecyl-3-(3,5-di-tert butyl-4-hydroxyphenyl)propionate, bis(2,4-dicumylphenyl)pentaerythritoldiphosphite, bis(2,6-di-tert.butyl-4-methylphenyl)penta-erythritoldiphosphite, triphenylphosphine, pentaerythritol tetrastearate, glycerol monostearate, stearyl stearate, propanediol mono- or distearate, 2-(2′-hydroxyphenyl)-benzotriazoles, 2-hydroxybenzophenones, esters of optionally substituted benzoic acids, acrylates, sterically hindered amines, oxamides, 2-(2-hydroxyphenyl)-1,3,5-triazines, and mixtures thereof.

11. A method comprising providing copolycarbonates according to claim 1 , and processing the copolycarbonates to provide an article selected from the group consisting of moldings, extrudates, films, sheets and containers.

12. A method comprising providing a composition according to claim 9 , and processing the composition to provide an article selected from the group consisting of moldings, extrudates, films, sheets and containers.

13. An article prepared by the method according to claim 11 .

14. An article prepared by the method according to claim 12 .

15. A process for preparing copolycarbonates according to claim 1 , the process comprising:

(i) providing at least an alkylphenol of the general formula (1a)

wherein R1 and R2 each independently represent hydrogen or a C 1-18 -alkyl, with the proviso that R1 and R2 are not simultaneously hydrogen, a diphenol of the general formula (2a)

wherein R 3 represents a C 1-4 -alkyl, R 4 represents hydrogen or C 1 -C 4 -alkyl, and n represents 0, 1, 2 or 3; and at least one dihydroxyaryl compound of the formula (3)

HO—Z—OH  (3)

wherein Z represents a radical of the formula (3a)

wherein each R 6 and each R 7 independently represents a moiety selected from the group consisting of H, C 1 -C 18 -alkyls, C 1 -C 18 -alkoxys, halogens, optionally substituted aryls or aralkyls, and X represents a moiety selected from the group consisting of —SO 2 —, —CO—, C 1 - to C 6 -alkylenes, C 2 - to C 5 -alkylidenes and C 6 - to C 12 -arylenes, optionally condensed with further aromatic rings containing hetero atoms; and

(ii) reacting the alkylphenol, the diphenol and the dihydroxyaryl compound in a continuous interfacial reaction.