Alkylphenol for adjusting the molecular weight, and polycarbonate compositions having improved properties

1. A continuous interfacial process for preparing linear or branched polycarbonate having an inhomogeneity factor comprising the step of preparing said polycarbonate from an alkylphenol of formula (1)

wherein

R1 and R2 independently of one another represent hydrogen, C1-C8-alkyl, C6-C12-aryl, phenyl-C1-C6-alkyl or naphthyl-C1-C6-alkyl, but wherein R1 and R2 cannot simultaneously be hydrogen,

wherein the inhomogeneity factor for various molecular weight ranges is as follows:

for low-viscosity polycarbonate having an average molecular weight (weight-average) of from 18,000 to 22,000 g/mol, U is 1.08 to 1.18,

for medium-viscosity polycarbonate having an average molecular weight (weight-average) of greater than 22,000 to 26,000 g/mol, U is 1.18 to 1.60,

for high-viscosity polycarbonate having an average molecular weight (weight-average) of greater than 26,000 to 40,000 g/mol, U is 1.30 to 1.75.

2. The process of claim 1 , wherein for low-viscosity polycarbonate having an average molecular weight (weight-average) of from 18,000 to 22,000 g/mol, the inhomogeneity factor U is 1.10 to 1.16.

3. The process of claim 1 , wherein for medium-viscosity polycarbonate having an average molecular weight (weight-average) of greater than 22,000 to 26,000 g/mol, the inhomogeneity factor U is 1.20 to 1.50.

4. The process of claim 1 , wherein for high-viscosity polycarbonate having an average molecular weight (weight-average) of greater than 26,000 to 40,000 g/mol, the inhomogeneity factor U is 1.35 to 1.60.

5. The process of claim 1 , wherein for medium-viscosity polycarbonate having an average molecular weight (weight-average) of greater than 22,000 to 26,000 g/mol, the inhomogeneity factor U is 1.20 to 1.50.

6. The process of claim 1 , wherein for high-viscosity polycarbonate having an average molecular weight (weight-average) of greater than 26,000 to 40,000 g/mol, the inhomogeneity factor U is 1.35 to 1.55.

7. The process of claim 1 , wherein the compound of the formula (1) is p-tert-butylphenol or n-butylphenol.

8. A composition comprising

A) polycarbonate with alkylphenol of the formula (I) according to claim 1 as an end group, wherein the inhomogeneity factor has the following values, depending on the molecular weight range:

for low-viscosity polycarbonate having an average molecular weight (weight-average) of from 18,000 to 22,000 g/mol, U is 1.08 to 1.18,

for medium-viscosity polycarbonate having an average molecular weight (weight-average) of greater than 22,000 to 26,000 g/mol, U is 1.18 to 1.60,

for high-viscosity polycarbonate having an average molecular weight (weight-average) of greater than 26,000 to 40,000 g/mol, U is 1.30 to 1.75,

B) at least one additive chosen from the group consisting of heat stabilizer, mould release agent and light stabilizer.

9. The composition of claim 8 , comprising 0.001 to 1 wt. % of at least one additive of component B), based on the total composition.

10. The composition of claim 8 , comprising 0.005 to 0.8 wt. % of at least one additive of component B), based on the total composition.

11. The composition of claim 8 , wherein the heat stabilizer, the mould release agent and light stabilizer are chosen from at least one 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, triisooctyl phosphate, pentaerythritol tetrastearat, glycerol monostearate, stearyl stearate, propanediol stearate, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)proprionate, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, triphenylphosphine, benzotriazoles, triazines, benzophenol, cyanoacrylates, cinnamic acid esters and oxalimides.

12. The composition of claim 8 , comprising triphenylphosphine and pentaerythritol tetrastearate.

13. A compound or blend comprising the composition of claim 8 .

14. A moulding comprising the composition of claim 8 .