Sound reducing wedge shaped polymer interlayers

1. A windshield interlayer, comprising:

a plasticized poly(vinyl butyral) polymer sheet comprising 40-90 phr plasticizer and having a glass transition temperature of less than 25° C., wherein said windshield interlayer is wedge shaped and has a first edge and a second edge, wherein said first edge has a thickness of at least 0.38 millimeters and said second edge has a thickness that is at least 0.13 millimeters greater than said thickness of said first edge, and wherein said polymer sheet shows an improved sound transmission loss of at least two decibels relative to an equivalent polymer sheet having a glass transition temperature between 30-33 ° C.

2. The windshield interlayer of claim 1 , wherein said windshield interlayer further comprises a second polymer sheet.

3. The windshield interlayer of claim 2 , wherein said second polymer sheet is not wedge shaped and said polymer sheet having a glass transition temperature of less than 25° C. is wedge shaped.

4. The windshield interlayer of claim 2 , wherein said second polymer sheet is wedge shaped and said polymer sheet having a glass transition temperature of less than 25° C. is not wedge shaped.

5. The windshield interlayer of claim 2 , further comprising a polymer film layer disposed between said polymer sheet having a glass transition temperature of less than 25° C. and said second polymer sheet.

6. The windshield interlayer of claim 1 , wherein said thickness of said second edge is 0.13 millimeters to 0.8 millimeters greater than said thickness of said first edge.

7. The windshield interlayer of claim 6 , wherein said thickness of said second edge is 0.3 millimeters to 0.8 millimeters greater than said thickness of said first edge.

8. The windshield interlayer of claim 6 , wherein said first thickness is at least 0.5 millimeters.

9. The windshield interlayer of claim 1 , wherein said wedge shaped polymer interlayer does not comprise polymer sheets other than said polymer sheet having a glass transition temperature of less than 25° C.

10. The windshield interlayer of claim 9 , wherein said polymer sheet having a glass transition temperature of less than 25° C. comprises an acoustic region and a non acoustic region.

11. The windshield interlayer of claim 1 , wherein said windshield interlayer further comprises a polymer film.

12. The windshield interlayer of claim 1 wherein said plasticized poly(vinyl butyral) polymer sheet has a residual hydroxyl content of less than 18.7%.

13. The windshield interlayer of claim 12 wherein said plasticized poly(vinyl butyral) polymer sheet has a residual hydroxyl content of less or equal to than 16%.

14. The windshield interlayer of claim 1 wherein said plasticizer is triethylene glycol di-(2-ethylhexanoate).

15. A method for manufacturing a windshield interlayer comprising:

forming a wedge shaped windshield interlayer comprising a plasticized poly(vinyl butyral) polymer sheet comprising 40 -90 phr plasticizer and having a glass transition temperature of less than 25° C. wherein said windshield interlayer has a first edge and a second edge, wherein said first edge has a thickness of at least 0.38 millimeters and said second edge has a thickness that is at least 0.13 millimeters greater than said thickness of said first edge, and wherein said polymer sheet shows an improved sound transmission loss of at least two decibels relative to an equivalent polymer sheet having a glass transition temperature between 30 -33° C.

16. The method of claim 15 , further comprising forming a second polymer sheet and laminating said second polymer sheet and said polymer sheet having a glass transition temperature of less than 25° C.

17. The method of claim 16 , wherein said second polymer sheet is not wedge shaped and said polymer sheet having a glass transition temperature of less than 25° C. is wedge shaped.

18. The method of claim 16 , wherein said second polymer sheet is wedge shaped and said polymer sheet having a glass transition temperature of less than 25° C. is not wedge shaped.

19. The method of claim 16 , further comprising a polymer film layer disposed between said polymer sheet having a glass transition temperature of less than 25° C. and said second polymer sheet.

20. The method of claim 15 , wherein said thickness of said second edge is 0.13 millimeters to 0.8 millimeters greater than said thickness of said first edge.

21. The method of claim 20 , wherein said thickness of said second edge is 0.3 millimeters to 0.8 millimeters greater than said thickness of said first edge.

22. The method of claim 21 , wherein said thickness of said first edge is at least 0.5 millimeters.

23. The method of claim 15 , wherein said wedge shaped polymer interlayer does not comprise polymer sheets other than said polymer sheet having a glass transition temperature of less than 25° C.

24. The method of claim 15 , further comprising laminating a polymer film to said polymer sheet having a glass transition temperature of less than 25° C.

25. The method of claim 16 , further comprising forming said polymer sheet having a glass transition temperature of less than 25° C. by coextruding an acoustic polymer melt and a non acoustic polymer melt to form said polymer sheet having a glass transition temperature of less than 25° C., wherein said polymer sheet is wedge shaped and comprises an acoustic region and a non acoustic region.

26. The method of manufacturing a windshield interlayer of claim 15 wherein said plasticized poly(vinyl butyral) polymer sheet has a residual hydroxyl content of less than 18.7%.

27. The method of manufacturing a windshield interlayer of claim 26 wherein said plasticized poly(vinyl butyral) polymer sheet has a residual hydroxyl content of less or equal to than 16%.

28. The method of manufacturing a windshield interlayer of claim 15 wherein said plasticizer is triethylene glycol di-(2-ethylhexanoate).

29. A windshield comprising:

a windshield interlayer, comprising:

a plasticized poly(vinyl butyral) polymer sheet comprising 40-90 phr plasticizer and having a glass transition temperature of less than 25° C., wherein said windshield interlayer is wedge shaped and has a first edge and a second edge, wherein said first edge has a thickness of at least 0.38 millimeters and said second edge has a thickness that is at least 0.13 millimeters greater than said thickness of said first edge, and wherein said polymer sheet shows an improved sound transmission loss of at least two decibels relative to an equivalent polymer sheet having a glass transition temperature between 30-33° C.

30. The windshield of claim 29 , wherein said windshield interlayer further comprises a second polymer sheet.

31. The windshield of claim 30 , wherein said second polymer sheet is not wedge shaped and said polymer sheet having a glass transition temperature of less than 25° C. is wedge shaped.

32. The windshield of claim 30 , wherein said second polymer sheet is wedge shaped and said polymer sheet having a glass transition temperature of less than 25° C. is not wedge shaped.

33. The windshield of claim 30 , further comprising a polymer film layer disposed between said polymer sheet having a glass transition temperature of less than 25° C. and said second polymer sheet.

34. The windshield of claim 29 , wherein said thickness of said second edge is 0.13 millimeters to 0.8 millimeters greater than said thickness of said first edge.

35. The windshield of claim 34 , wherein said thickness of said second edge is 0.3 millimeters to 0.8 millimeters greater than said thickness of said first edge.

36. The windshield of claim 34 , wherein said first thickness is at least 0.5 millimeters.

37. The windshield of claim 29 , wherein said wedge shaped polymer interlayer does not comprise polymer sheets other than said polymer sheet having a glass transition temperature of less than 25° C.

38. The windshield of claim 37 , wherein said polymer sheet having a glass transition temperature of less than 25° C. comprises an acoustic region and a non acoustic region.

39. The windshield of claim 29 , wherein said windshield interlayer further comprises a polymer film.

40. The windshield of claim 29 wherein said plasticized poly(vinyl butyral) polymer sheet has a residual hydroxyl content of less than 18.7%.

41. The windshield of claim 40 wherein said plasticized poly(vinyl butyral) polymer sheet has a residual hydroxyl content of less or equal to than 16%.

42. The windshield of claim 29 wherein said plasticizer is triethylene glycol di-(2-ethylhexanoate).

43. A windshield interlayer, comprising:

a coextruded multilayer plasticized poly(vinyl butyral) polymer sheet comprising 40-90 phr plasticizer and having a region with a glass transition temperature of less than 25° C. and a region with a glass transition temperature of greater than 25° C., wherein said windshield interlayer is wedge shaped and has a first edge and a second edge and wherein said first edge has a thickness of at least 0.38 millimeters and said second edge has a thickness that is at least 0.13 millimeters greater than said thickness of said first edge, and wherein said polymer sheet shows an improved sound transmission loss of at least two decibels relative to an equivalent polymer sheet having a glass transition temperature between 30-33° C.

44. The windshield interlayer of claim 43 wherein said plasticized poly vinyl butyral) polymer sheet has a residual hydroxyl content of less than 18.7%.

45. The windshield interlayer of claim 44 wherein said plasticized poly(vinyl butyral) polymer sheet has a residual hydroxyl content of less or equal to than 16%.

46. The windshield interlayer of claim 44 wherein said plasticizer is triethylene glycol di-(2-ethylhexanoate).