Polymer composition

1. A composition formed from a first mixture of components comprising:

(i) a first amount of an aromatic polycarbonate;

(ii) a second amount of a graft copolymer including polyacrylonitrile; and,

(iii) 3 to 25 wt % of a non-crosslinked acrylic polymer obtained by polymerising monomers consisting of 60 to 100% by weight methyl methacrylate monomer and 0 to 40% by weight of one or more alkyl (alk)acrylate comonomers, and having a weight average molecular weight (Mw) of between greater than or equal to 30,000 Daltons (Da) and less than 50,000 Daltons (Da).

2. A composition as claimed in claim 1 wherein the non-crosslinked acrylic polymer has a weight average molecular weight (Mw) of 30,000 Da to 45,000 Da.

3. A composition as claimed in claim 1 , wherein the non-crosslinked acrylic polymer comprises an acrylic copolymer obtained by polymerising 60 to 99.9% by weight of methyl methacrylate monomer and 0.1 to 40% by weight of one or more alkyl (alk)acrylate comonomers.

4. A composition as claimed in claim 3 wherein the acrylic copolymer is obtained by polymerising 80 to 99% by weight of methyl methacrylate monomer and 20 to 1% by weight of one or more alkyl (alk)acrylate comonomers.

5. A composition as claimed in claim 3 , wherein the alkyl (alk)acrylate comonomer of the acrylic copolymer comprises an alkyl acrylate comonomer.

6. A composition as claimed in claim 5 wherein the one or more alkyl acrylate comonomers of the acrylic copolymer comprises one or more C 1 to C 8 alkyl acrylate comonomers.

7. A composition as claimed in claim 6 wherein the one or more C 1 to C 8 alkyl acrylate comonomers are selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate and mixtures thereof.

8. A composition as claimed in claim 3 , wherein the acrylic copolymer is obtained by polymerizing 90 to 99% by weight of methylmethacrylate monomer and 10 to 1% by weight of one or more alkyl (alk)acrylate comonomers.

9. A composition as claimed in claim 5 , wherein the acrylic copolymer includes only one alkyl acrylate comonomer.

10. A composition as claimed in claim 1 , wherein the non-crosslinked acrylic polymer is present in an amount of less than or equal to 20% by weight, based on the total weight of the composition.

11. A composition as claimed in claim 1 , wherein the graft copolymer including polyacrylonitrile comprises an acrylic-styrene-acrylonitrile (ASA) polymer, acrylonitrile-EPDM-styrene (AES) polymer, olefin-styrene-acrylonitrile (OSA) polymer or acrylonitrile-butadiene-styrene (ABS) polymer.

12. A composition as claimed in claim 11 wherein the graft copolymer including polyacrylonitrile comprises an ASA polymer, an AES polymer or an ABS polymer.

13. A composition as claimed in claim 1 , wherein the graft copolymer including polyacrylonitrile is present in an amount of greater than or equal to 0.5% by weight, based on the total weight of the composition.

14. A composition as claimed in claim 1 , wherein the graft copolymer including polyacrylonitrile is present in an amount of less than or equal to 60% by weight, based on the total weight of the composition.

15. A composition as claimed in claim 1 , wherein the aromatic polycarbonate is derived from a bis-phenol.

16. A composition as claimed in claim 1 , wherein the aromatic polycarbonate is present in an amount of greater than or equal to 30% by weight, based on the total weight of the composition.

17. A composition as claimed in claim 1 , wherein the aromatic polycarbonate is present in an amount of less than or equal to 90% by weight, based on the total weight of the composition.

18. A composition as claimed in claim 1 , wherein the ratio by weight of the aromatic polycarbonate to the weight of the graft copolymer including polyacrylonitrile is 90:1 to 0.5:1.

19. A composition as claimed in claim 1 , further including an impact modifier.

20. A composition as claimed in claim 19 wherein the impact modifier comprises an acrylic based impact modifier or a methacrylate-butadiene-styrene (MBS) based impact modifier.

21. A composition as claimed in claim 19 , wherein the impact modifier is in the form of core-shell polymeric particles.

22. A composition as claimed in claim 19 , wherein the impact modifier is present in an amount greater than or equal to 1% by weight, based on the total weight of the composition.

23. A composition as claimed in claim 19 , wherein the impact modifier is present in an amount of less than or equal to 20% by weight, based on the total weight of the composition.

24. A composition as claimed in claim 1 , wherein the Melt Flow Index of the composition at 260° C. applying a 5 kg/cm 3 load as determined in accordance with ISO 1133:1997 is at least 5% greater than a comparable composition containing an equivalent level of aromatic polycarbonate and not including the non-crosslinked acrylic polymer.

25. A composition as claimed in claim 1 , for use in melt-processing applications.

26. A composition as claimed in claim 1 , further including a reinforcement fibre.

27. A process for manufacturing a composition as defined in claim 1 comprising mixing the aromatic polycarbonate, the graft copolymer including polyacrylonitrile, and the non-crosslinked acrylic polymer.

28. A process as claimed in claim 27 wherein the mixing comprises melt blending the aromatic polycarbonate, the graft copolymer including polyacrylonitrile, and the non-crosslinked acrylic polymer.

29. A process as claimed in claim 27 , further including the step of adding an impact modifier.

30. An article comprising a composition as defined in claim 1 .

31. A method of manufacturing an article comprising adding a composition as defined in claim 1 in molten form to a mold, allowing the molten composition to solidify in the mold to form the article and removing the article from the mold.

32. A method of forming an article comprising injection molding a composition as defined in claim 1 .

33. A method of forming the composition of claim 1 , comprising mixing the non-crosslinked acrylic polymer with a component mixture comprising the aromatic polycarbonate and the graft copolymer including polyacrylonitrile and optionally including an impact modifier and/or a reinforcement fibre, whereby the melt flow rate of the component mixture is increased compared to the component mixture not containing the non-crosslinked acrylic polymer.

34. A method of forming an article by injection molding, comprising mixing a non-crosslinked acrylic polymer having a weight average molecular weight (Mw) of between greater than or equal to 30,000 Daltons (Da) and less than 50,000 Daltons (Da) with a component mixture comprising an aromatic polycarbonate and a graft copolymer including polyacrylonitrile and optionally including an impact modifier and/or a reinforcement fibre, and forming an article from a resultant mixture by an injection molding procedure, whereby the process cycle time for forming the article is decreased compared to the component mixture not containing the non-crosslinked acrylic polymer, wherein the non-crosslinked acrylic polymer is in the amount of 3 to 25 wt % and obtained by polymerising monomers consisting of 60 to 100% by weight methyl methacrylate monomer and 0 to 40% by weight of one or more alkyl (alk)acrylate comonomers.

35. A composition as claimed in claim 8 , wherein the acrylic copolymer consists essentially of methyl methacrylate monomer and one or more alkyl acrylate comonomers.

36. A composition as claimed in claim 19 , wherein the impact modifier comprises a MBS based impact modifier.

37. A composition as claimed in claim 4 , wherein the alkyl (alk)acrylate comonomer of the acrylic copolymer comprises an alkyl acrylate comonomer.

38. A composition as claimed in claim 8 , wherein the alkyl (alk)acrylate comonomer of the acrylic copolymer comprises an alkyl acrylate comonomer.

39. A composition as claimed in claim 20 , wherein the impact modifier is in the form of core-shell polymeric particles.

40. A composition as claimed in claim 36 , wherein the impact modifier is in the form of core-shell polymeric particles.

41. A process as claimed in claim 28 , further including the step of adding an impact modifier.

42. A composition as claimed in claim 1 , wherein the aromatic polycarbonate is derived from 2,2-bis-(4-hydroxyphenyl)-propane (bisphenol A).