Polycarbonate molding compositions

1. A thermoplastic molding composition comprising

A) 30 to 80 parts by weight (pbw) of aromatic polycarbonate and/or polyester-carbonate

B) 5 to 60 pbw of graft polymer and

C) 10 to 60 pbw of mixture

C.1) 40 to 92 wt %, based on component C), of a first rubber-free copolymer prepared by the solution, bulk or suspension polymerization process from

C.1.1) 65 to 75 wt %. based on component C.1), of at least one monomer selected from the group consisting of vinylaromatics and vinylaromatics substituted on the nucleus and

C.1.2) 25 to 35 wt %, based on component C.1), of at least one monomer selected from the group consisting of vinyl cyanides, (meth)acrylic acid (C 1 -C 8 )-alkyl esters, unsaturated carboxylic acids

and

C.2) 8 to 60 wt %, based on component C), of a second rubber-free copolymer prepared by the solution, bulk or suspension polymerization process from

C.2.1) 75.1 to 85 wt %, based on component C.2), of at least one monomer selected from the group consisting of vinylaromatics substituted on the nucleus and

C.2.2) 15 to 24.9 wt %, based on component C.2), of at least one monomer selected from the group consisting of vinyl cyanides, (meth)acrylic acid (C 1 -C 8 )-alkyl esters, unsaturated carboxylic acids and derivatives of unsaturated carboxylic acids.

2. The composition according to claim 1 , wherein the content of monomers C.1.2) in copolymer C.1) differs from the content of monomers C.2.2) in copolymer C.2) by 2 to 10 wt %.

3. The composition according to claim 1 , wherein the content of component C.1.2) in copolymer C.1) differs from the content of component C.2.2) in copolymer C.2) differ from one another by 2.5 to 7 wt %.

4. The composition according to claim 1 , wherein B is a graft polymer of

B.1) 5 to 95 wt %, based on B), of a mixture of

B.1.1) 65 to 85 wt %, based on B.1, of at least one monomer selected from the group consisting of vinylaromatics, vinylaromatics substituted on the nucleus and methacrylic acid (C 1 -C 8 )-alkyl esters and

B.1.2) 15 to 35 wt %, based on B.1, of at least one monomer selected from the group consisting of vinyl cyanides, (meth)acrylic acid (C 1 -C 8 )-alkyl esters and derivatives of unsaturated carboxylic acids

on

B.2) 95 to 5 wt % of at least one graft base having a glass transition temperature of <0° C., the graft base of B.2 having a median particle size (d 50 value) of from 0.05 to 10 μm.

5. The composition according to claim 4 , wherein said graft base is a diene rubber.

6. The composition according to claim 4 , wherein B.1.1), C1.1) and C.2.1) are styrene and where B. 1.2), C.1.2) and C.2.2) are acrylonitrile.

7. The composition according to claim 6 comprising at least one additive selected from the group consisting of flameproofing agent, antidripping agent, lubricant, mold release agent, nucleating agent, antistatic, stabilizer, filler, reinforcing substance, dyestuff and pigment.

8. A thermoplastic molding composition comprising

A) 40 to 75 pbw or aromatic polycarbonate and/or polyester carbonate,

B) 10 to 45 pbw of a graft polymer of

B.1) 5 to 95 wt %, based on B), of a mixture of

B.1.1) 65 to 85wt %, based on B.1,of styrene and

B.1.2) 15 to 35 wt %, based on B.1, of acrylonitrile

on

B.2) 95 to 5 wt % of crossliniked polybutadiene rubber, wherein the graft base has a median particle size of (d 50 value) of from 0.2 to 1 μm,

C)15 to 40 pbw of a mixture of

C.1) 65 to 90 wt %, based on component C). of a first rubber-free copolymer prepared by the solution, bulk or suspension polymerization process from

C.1.1) 60 to 75wt %, based on component C.1.), of a styrene and

C.1.2) 25 to 35 wt %, based on component C.1), of acrylonitrile

and

C.2) 10 to 35 wt %, based on component C), of a second rubber-free copolymer prepared by the solution, bulk or suspension polymerization process from

C.2.1) 75.1 to 85 wt %, based on component C.2), of styrene and

C.2.2) 15 to 24.9 wt %, based on component C.2), of acrylonitrile.

9. The composition according to claim 1 , wherein at least some of the graft polymer B) and at least some of either C.1 or C.2 are present in the form of a precompound, said precompound prepared under vacuum devolatilization.

10. A process for the preparation of the thermoplastic molding composition of claim 1 comprising

a) compounding at least some of component B with at least some of component C under vacuum devolatilization to produce a precompound, and

b) mixing the precompound with component A to form a mixture and

c) melt compounding the mixture at 200° C. to 300° C.

11. A process for the preparation of the thermoplastic molding composition of claim 1 comprising

a) compounding at least some of component B with at least some of copolymer C.1 or C.2 in the presence of water under vacuum devolatilization to produce a precompound, and

b) mixing the precompound with a component from A to form a mixture and

c) melt compounding the mixture at 200° C. to 300° C.

12. The process according to claim 10 further comprising applying vacuum during said melt compounding step C.

13. The process according to claim 11 further comprising applying vacuum during said melt compounding step C.

14. A molded article comprising the composition of claim 1 .