Thermoplastic compositions

1. A thermoplastic composition comprising;

1 to 30 weight percent, based on total weight of said thermoplastic composition, of a cycloaliphatic polyester wherein said cycloaliphatic polyester consists essentially of repeating units of formula:

 wherein R 7 and R 8 are independently at each occurrence selected from the group consisting of an aliphatic group having 6 to 20 carbon atoms and a cycloalkane having 6 to 20 carbon atoms, with the proviso that at least one of R 7 and R 8 is a cycloalkyl containing radical; and greater than or equal to 40 weight percent, based on total weight of said thermoplastic composition, of a polyorganosiloxane/polycarbonate block copolymer, wherein said composition has a B-Y span of less than or equal to 20.

2. The thermoplastic composition of claim 1 , wherein the polyorganosiloxane/polycarbonate block copolymer comprises polyorganosiloxane domains having an average domain size less than or equal to 45 nanometers.

3. The composition of claim 1 , further comprising 10 to 50 weight percent of a polycarbonate, based on total weight of said thermoplastic composition.

4. The composition of claim 1 , comprising 5 to 25 weight percent of said cycloaliphatic polyester, based on total weight of said thermoplastic composition.

5. The composition of claim 1 , comprising 10 to 20 weight percent of said cycloaliphatic polyester, based on total weight of said thermoplastic composition.

6. The composition of claim 1 , wherein the polyorganosiloxane/polycarbonate block copolymer comprises a polyorganosiloxane blocks comprising, on average, greater than or equal to ten siloxane units.

7. The composition of claim 1 , wherein the polyorganosiloxane/polycarbonate block copolymer comprises a polydimethylsiloxane/polycarbonate block copolymer comprising 0.5 to 80 weight percent by weight polydimethylsiloxane based on the total weight of the block copolymer.

8. The composition of claim 1 , wherein the cycloaliphatic polyester comprises of cycloaliphatic diacid and cycloaliphatic diol units.

9. The composition of claim 1 wherein the cycloaliphatic polyester comprises polycyclohexane dimethanol cyclohexane dicarboxylate.

10. The composition of claim 1 , wherein the polyorganosiloxane/polycarbonate block copolymer comprises a polydimethylsiloxane/bisphenol-A polycarbonate block copolymer.

11. The composition of claim 1 , wherein said composition has a percentage transmission of greater than or equal to 25 measured in accordance with ASTM E313-00.

12. The composition of claim 1 , further comprising a colorant, filler, fire retardant, UV stabilizer, antistatic agent, acid scavenger, visual effects enhancer or mixtures thereof.

13. The composition of claim 1 , wherein the composition has a notched Izod impact measured in accordance with ASTM D256-03 of greater than or equal to 420 Joules per meter at −20° C.

14. The composition of claim 1 , wherein the composition has a notched Izod impact measured in accordance with ASTM D256-03 of greater than or equal to 420 Joules per meter at 24° C.

15. The composition of claim 1 , wherein the composition has a melt volume rate measured in accordance with ASTM D1238-01 of 5 to 40 cubic centimeters/10 minutes.

16. An article comprising the composition of claim 1 .

17. A method of making a thermoplastic composition comprising:

mixing 1 to 30 weight percent, based on total weight of said thermoplastic composition, of a cycloaliphatic polyester wherein said cycloaliphatic polyester consists essentially of repeating units of formula:

 wherein R 7 and R 8 are independently at each occurrence selected from the group consisting of an aliphatic group having 6 to 20 carbon atoms and a cycloalkane having 6 to 20 carbon atoms, with the proviso that at least one of R 7 and R 8 is a cycloalkyl containing radical; and

greater than or equal to 40 weight percent, based on total weight of said thermoplastic composition, of a polyorganosiloxane/polycarbonate block copolymer comprising polyorganosiloxane domains having an average domain size less than or equal to 45 nanometers.

18. A composition comprising:

10 to 15 weight percent of a cycloaliphatic polyester based on total weight of said thermoplastic composition, wherein said cycloaliphatic polyester consists essentially of repeating units of formula:

 wherein R 7 and R 8 are independently at each occurrence selected from the group consisting of an aliphatic group having 6 to 20 carbon atoms and a cycloalkane having 6 to 20 carbon atoms, with the proviso that at least one of R 7 and R 8 is a cycloalkyl containing radical; and

greater than or equal to 40 weight percent, based on total weight of said thermoplastic composition, of a polydimethylsiloxane/bisphenol-A polycarbonate block copolymer comprising polydimethylsiloxane domains having an average domain size less than or equal to 25 nanometers.

19. The composition of claim 18 , wherein the composition has a B-Y span of less than or equal to 20.

20. A thermoplastic composition comprising;

1 to 30 weight percent, based on total weight of said thermoplastic composition, of a cycloaliphatic polyester wherein said cycloaliphatic polyester consists essentially of repeating units of formula:

 wherein R 7 and R 8 are independently at each occurrence selected from the group consisting of an aliphatic group having 6 to 20 carbons and a cyclealkane having 6 to 20 carbon atoms, with the proviso that at least one of R 7 and R 8 is a cycloalkyl containing radical; and

greater than or equal to 40 weight percent, based on total weight of said thermoplastic composition, of a polyorganosiloxane/polycarbonate block copolymer comprising polyorganosiloxane domains having an average domain size less than or equal to 45 nanometers.

21. A transparent thermoplastic composition comprising:

1 to 30 weight percent of a cycloaliphatic polyester based on total weight of said thermoplastic composition, wherein said cycloaliphatic polyester consists essentially of repeating units of formula:

 wherein R 7 and R 8 are independently at each occurrence selected from the group consisting of an aliphatic group having 6 to 20 carbon atoms and a cycloalkane having 6 to 20 carbon atoms, with the proviso that at least one of R 7 and R 8 is a cycloalkyl containing radical; and greater than or equal to 40 weight percent, based on total weight of said thermoplastic composition, of a polyorganosiloxane/polycarbonate block copolymer wherein the composition has a light transmission of greater than or equal to 25% as measured by ASTM E313-00 on a 3.2 millimeter thick plaque.

22. The composition of claim 21 , wherein the polyorganosiloxane/polycarbonate block copolymer comprises polyorganosiloxane domains having an average domain size less than or equal to 45 nanometers.

23. The composition of claim 21 , wherein the composition has a B-Y span of less than or equal to 20.