Polysiloxane-polycarbonate block cocondensates

1. A polysiloxane-polycarbonate block cocondensate derived from

(A) at least one hydroxyaryl-terminated siloxane of the formula (1) (siloxane component)

 in which

R 1 is H, Cl, Br or C 1 to C 4 -alkyl,

R 2 and R 3 are the same or different and each independently from one another selected from aryl, C 1 to C 10 -alkyl and C 1 to C 10 -alkylaryl,

X is a single bond, —CO—, —O—, C 1 - to C 6 -alkylene, C 2 to C 5 -alkylidene, C 5 to C 12 -cycloalkylidene or C 6 to C 12 -arylene which may optionally be fused to further aromatic rings containing heteroatoms,

n is a number from 10 to 100,

m is a number from 2 to 5, and

p is 0 or 1;

(B) and at least one polycarbonate

wherein the polysiloxane-polycarbonate block cocondensate contains at least one of the following structures (I) to (IV):

 in which

the phenyl rings are unsubstituted or independently mono- or disubstituted by C 1 to C 8 -alkyl and/or halogen,

X is a single bond, C 1 to C 6 -alkylene, C 2 to C 5 -alkylidene or C 5 to C 6 -cycloalkylidene,

the linkages indicated by—in the structural units (I) to (IV) are each part of a carboxylate group;

and wherein the amount of the structural units (I) to (IV) totals 60 to 1500 ppm (determined after hydrolysis, based on the polysiloxane-polycarbonate block cocondensate), wherein the polysiloxane-polycarbonate block cocondensate has a relative solution viscosity of 1.26 to 1.40, determined in dichloromethane at a concentration of 5 g/l at 25° C. using a Ubbelohde viscosimeter.

2. The polysiloxane-polycarbonate block cocondensate according to claim 1 , wherein the amount of the structural units (I) to (IV) totals 80 to 850 ppm (based on the polysiloxane-polycarbonate block cocondensate and determined after hydrolysis).

3. The polysiloxane-polycarbonate block cocondensate according to claim 1 , wherein the polysiloxane-polycarbonate block cocondensate is derived from a composition comprising the siloxane component of the formula (1) and the polycarbonate, which composition contains the siloxane component in an amount of 2 to 20%, based on the polycarbonate.

4. The polysiloxane-polycarbonate block cocondensate according to claim 1 , which contains structures derived from a diphenol according to general formula (2b):

wherein

R6 and R7 are independently of one another H, C 1 -C 18 -alkyl-, C 1 -C 18 -alkoxy, halogen or an optionally substituted aryl- or aralkyl, and

X is a single bond, —CO—, —O—, C 1 - to C 6 -alkylene, C 2 to C 5 -alkylidene, C 5 to C 12 -cycloalkylidene or C 6 to C 12 -arylene which may optionally be fused to further aromatic rings containing heteroatoms.

5. The polysiloxane-polycarbonate block cocondensate according to claim 1 , wherein the hydroxyaryl-terminated siloxane has a weight-average molecular weight of 3000-20000 g/mol.

6. The polysiloxane-polycarbonate block cocondensate according to claim 1 , wherein R 1 is H, p is 1 and X is isopropylidene.

7. The polysiloxane-polycarbonate block cocondensate according to claim 1 , wherein R 2 and R 3 are methyl.

8. The polysiloxane-polycarbonate block cocondensate according to claim 1 which has a sodium content within the range of from 0.1 ppm to 1000 ppm.

9. A method for the production of a moulding comprising molding the polysiloxane-polycarbonate block cocondensate according to claim 1 .

10. A moulding or extrudate comprising the polysiloxane-polycarbonate block cocondensate according to claim 1 .