ABS compositions with improved property combinations

1. A thermoplastic molding composition comprising

A) at least one graft rubber that is the product of free-radical emulsion polymerization of at least one vinyl monomer in the presence of at least one rubber a) present in latex form having a glass transition temperature below 0° C. using at least one peroxodisulfate compound as initiator,

B) at least one graft rubber that is the product of free-radical emulsion polymerization of at least one vinyl monomer in the presence of at least one rubber b) present in latex form having a glass transition temperature below 0° C. using at least one azo compound as initiator,

C) at least one graft polymer that is the product of solution, bulk or suspension polymerization of styrene and acrylonitrile grafted phase in a weight ratio of 90:10 to 50:50 therebetween, in the presence of a rubber, wherein the rubber contains in copolymerized form 0 to 50 wt. % of a vinyl monomer and wherein the weight ratio of polymerized and grafted monomers to the rubber is 50:50 to 97:3.

2. The composition of claim 1 wherein the styrene and/or acrylonitrile of the grafted phase is at least partially replaced by a member selected from the group consisting of α-methylstyrene, methyl methacrylate and N-phenylmaleimide.

3. The composition according to claim 1 further containing a rubber-free thermoplastic vinyl polymer and/or a thermoplastic resin that contains no polymerized vinyl monomers.

4. The composition according to claim 3 wherein thermoplastic resin that contains no polymerized vinyl monomers is at least one member selected from the group consisting of aromatic polycarbonate, aromatic polyester carbonate, polyester and polyamide.

5. The composition according to claim 1 containing 1 to 50 parts by weight of the total of A) and B) and 50 to 99 parts by weight of C).

6. The composition according to claim 1 containing 2.5 to 45 parts by weight of the total of A) and B) and 55 to 97.5 parts by weight of C).

7. A thermoplastic molding composition comprising

A) at least one graft rubber that is the product of free-radical emulsion polymerization of styrene and acrylonitrile forming a grafted phase in a weight ratio of 90:10 to 50:50 therebetween in the presence of at least one butadiene rubber present in latex form, using at least one peroxodisulfate compound as initiator,

B) at least one graft rubber that is the product of free-radical emulsion polymerization of styrene and acrylonitrile forming a grafted phase in a weight ratio of 90:10 to 50:50 therebetween, in the presence of at least one butadiene rubber present in latex form, using at least one azo compound as initiator,

C) at least one graft polymer that is the product of solution, bulk or suspension polymerization of styrene and acrylonitrile forming a grafted phase in a weight ratio of 90:10 to 50:50 therebetween, in the presence of a rubber, wherein the rubber contains in copolymerized form 0 to 50 wt. % of a vinyl monomer and wherein the weight ratio of polymerized and grafted monomers to rubber is 70:30 to 95:5, and optionally,

D) at least one thermoplastic rubber-free polymer that is the product of polymerization of styrene and acrylonitrile forming a copolymer in a weight ratio of 90:10 to 50:50 therebetween.

8. The composition of claim 7 wherein the styrene and/or acrylonitrile of at least one of the grafted phase, all occurrences the copolymer is at least partially replaced by a member selected from the group consisting of α-methylstyrene, methyl methacrylate and N-phenylmaleimide.

9. The composition according to claim 1 in which azo compound is at least one member selected from the group consisting of formulae (I), (II), (III) and (IV):

where R=CH 3 , C 2 H 5 , n-C 3 H 7 , i-C 3 H 7 , n-C 4 H 9 , i-C 4 H 9 , t-C 4 H 9

10. The composition according to claim 1 wherein the rubber lattices of A) and B) have monomodal particle size distributions.

11. The composition according to claim 1 wherein the rubber lattices of A) and B) have bimodal particle size distributions.

12. The composition according to claim 1 wherein the rubber latex of A) has a momodal size distribution and the rubber latex of B) has a bimodal particle size distribution.

13. The composition according to claim 1 wherein the rubber latex of A) has a momodal size distribution and the rubber latex of B) has a trimodal particle size distribution.

14. The composition according to claim 1 wherein the rubber latex of A) has a bimodal size distribution and the rubber latex of B) has a trimodal particle size distribution.

15. The composition according to claim 1 wherein the rubber latex of A) has a bimodal size distribution and the rubber latex of B) has a monomodal particle size distribution.

16. The composition according to claim 1 wherein the lattices of graft rubbers A) and B) have mean particle diameter of (d 50 ) of 50 to 600 nm.

17. The composition according to claim 1 wherein the lattices of graft rubbers A) and B) have mean particle diameter of (d 50 ) of 100 to 500 nm.

18. The composition according to claim 16 wherein the mean particle diameter (d 50 ) of the rubber latex of graft rubber A) is less than the mean particle diameter (d 50 ) of the rubber latex of the graft rubber B).

19. The composition according to claim 1 wherein the rubber latex of the component C) has a mean particle diameter of 100 nm to 10,000 nm.

20. The composition according claim 1 wherein the rubber of the component C) has a mean particle diameter of 200 nm to 5,000 nm.

21. The composition according to claim 1 wherein the rubber of the component C) has a mean particle diameter of 400 nm to 2,000 nm.

22. A method of using the composition of claim 1 comprising producing a molded article.

23. A Molded article comprising the composition according to claim 1 .