Polycarbonate composition having improved heat stability

1. A composition comprising a melt polycarbonate, and a composition for stabilization of heat ageing comprising at least one phosphine, and n-octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate employed in an amount of from 10 to 800 mg/kg, based on the total weight of the composition, wherein said at least one phosphine is a compound of formula (I):

wherein

Ar 1 and Ar 2 are, identically or differently, optionally substituted aryl radicals, and

R′ is an optionally substituted aryl radical or a radical of formula (Ia) to (Ih)

wherein

R is an optionally substituted C 6 -C 14 -aryl radical,

n and m

are, independently of one another, an integer from 1 to 7,

wherein the H atoms of the radicals of formula (Ia) to (Ic) are optionally replaced by substituents, and

with the proviso that R′ is optionally an optionally substituted 4-phenylphenyl or an optionally substituted α-naphthyl if Ar in formula (I) is in both cases likewise an optionally substituted 4-phenylphenyl or an optionally substituted α-naphthyl,

at least one alkyl phosphate, wherein said at least one alkyl phosphate is a compound of formula (II):

wherein R 1 , R 2 , and R 3 are, identically or differently, H or a linear, branched, or cyclic alkyl radical, employed in an amount of from 0.5 to 500 mg/kg, based on the total weight of said composition,

and

wherein the composition has a subsequent yellowing ΔYI, after storage for 1000 hours at 135° C. in air, of less than 4.8.

2. The composition of claim 1 , wherein said melt polycarbonate comprises a melt polycarbonate of formula (IV)

wherein

the square brackets designate repeating structural units,

M is Ar, a polyfunctional compound A, B, or C, or a compound D,

wherein Ar is optionally a compound of formula (VIII) or (IX)

wherein

Z is C 1 - to C 8 -alkylidene, C 5 - to C 12 -cycloalkylidene, S, SO 2 , or a single bond, R 13 , R 14 , and R 15

are, independently of one another, an optionally substituted C1-C18 alkyl radical, Cl, or Br,

n is 0, 1, or 2,

r, s, and t are, independently of one another, 0, 1, 2, or 3,

polyfunctional compound A is a compound of formula

polyfunctional compound B is a compound of formula

polyfunctional compound C is a compound of formula

compound D is a compound of formula

wherein the sum of said polyfunctional compounds A, B, and C and compound D is greater than or equal to 5 mg/kg,

X is Y or -[MOCOO] n —Y,

Y is H or a compound of formula (X)

wherein

R 16 is, identically or differently, H, C 1 - to C 20 -alkyl, C 6 H 5 , or C(CH 3 ) 2 C 6 H 5 and

u is 0, 1, 2 or 3.

3. The composition of claim 2 , wherein said optionally substituted C1-C18 alkyl radical is a phenyl, methyl, propyl, ethyl, or butyl group, each of which is optionally substituted.

4. The composition of claim 1 , wherein said composition further comprises at least one phosphine oxide corresponding to said at least one phosphine of formula (I).

5. The composition of claim 1 , wherein said at least one phosphine of formula (I) is triphenylphosphine.

6. The composition of claim 1 , wherein said at least one phosphine of formula (I) is employed in an amount of from 10 to 2000 mg/kg, based on the total weight of said composition.

7. A process for preparing the composition of claim 1 , comprising preparing said melt polycarbonate via the melt transesterification reaction of a bisphenol and a carbonic acid diester.

8. A process for preparing the composition of claim 1 , comprising preparing said melt polycarbonate via the condensation of carbonate oligomers comprising hydroxyl and/or carbonate terminal groups, bisphenols, and carbonic diesters.

9. A process for preparing the composition of claim 1 , comprising adding an additive to the melt of a polycarbonate melt stream via a side extruder behind the last polycondensation step of a multi-step polycondensation to form a mixture and mixing said mixture in a static mixer.

10. A process for preparing the composition of claim 1 , comprising adding a prepared mixture of said phosphine with n-octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate to the melt of a polycarbonate melt stream via a side extruder behind the last polycondensation step of a multi-step polycondensation to form a mixture and mixing said mixture in a static mixer.

11. The process of claim 10 , wherein said mixture is added in liquid form.

12. A moulding comprising the composition of claim 1 .

13. A process for preparing a composition comprising preparing a melt polycarbonate via the melt transesterification reaction of a bisphenol and a carbonic acid diester, wherein the composition comprises a melt polycarbonate, and a composition for stabilization of heat ageing comprising at least one phosphine, and n-octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate employed in an amount of from 10 to 800 mg/kg, based on the total weight of the composition, wherein said at least one phosphine is a compound of formula (I):

wherein

Ar 1 and Ar 2 are, identically or differently, optionally substituted aryl radicals, and

R′ is an optionally substituted aryl radical or a radical of formula (Ia) to (Ih)

wherein

R is an optionally substituted C 6 -C 14 -aryl radical,

n and m

are, independently of one another, an integer from 1 to 7,

wherein the H atoms of the radicals of formula (Ia) to (Ic) are optionally replaced by substituents, and

with the proviso that R′ is optionally an optionally substituted 4-phenylphenyl or an optionally substituted α-naphthyl if Ar in formula (I) is in both cases likewise an optionally substituted 4-phenylphenyl or an optionally substituted α-naphthyl,

at least one alkyl phosphate, wherein said at least one alkyl phosphate is a compound of formula (II):

wherein R 1 , R 2 , and R 3 are, identically or differently, H or a linear, branched, or cyclic alkyl radical, employed in an amount of from 0.5 to 500 mg/kg, based on the total weight of said composition,

and

wherein said composition has a subsequent yellowing ΔYI, after storage for 1000 hours at 135° C. in air, of less than 4.8.