Polyolefin foams and methods of making the same
View Patent ↗A non-crosslinked polyolefin foam comprises a plastics component and a blowing agent. The plastics component comprises a first constituent and a second constituent. The first constituent is a Ziegler-Natta catalyzed linear low density polyolefin and the second constituent is a low density polyolefin in one embodiment. The Ziegler-Natta catalyzed linear low density polyolefin has a polydispersity of less than 10 and a melt flow index less than 10 g/10 minutes. The second constituent may be a polypropylene.
1. A non-crosslinked polyolefin foam comprising a plastics component and a blowing agent, the plastics component comprising a first constituent and a second constituent, wherein the first constituent is a Ziegler-Natta catalyzed linear low density polyolefin and the second constituent is a low density polyolefin, the Ziegler-Natta catalyzed linear low density polyolefin has a polydispersity of less than 10 and a melt flow index less than 10 g/10 minutes, and the foam has a density substantially the same as a foam made with 100% low density polyolefin under the same foaming conditions.
2. The polyolefin foam of claim 1 , wherein the second constituent is a low density polyethylene.
3. The polyolefin foam of claim 1 , wherein the plastics component comprises from 1% to 85% by weight of the first constituent, and from 99% to 15% by weight of the second constituent.
4. The polyolefin foam of claim 3 , wherein the plastics component comprises from 5% to 10% by weight of the first constituent, and from 95% to 90% by weight of the second constituent.
5. The polyolefin foam of claim 3 , wherein the plastics component comprises from 10% to 15% by weight of the first constituent, and from 90% to 85% by weight of the second constituent.
6. The polyolefin foam of claim 3 , wherein the plastics component comprises primarily of from 15% to 20% by weight of the first constituent, and from 85% to 80% by weight of the second constituent.
7. The polyolefin foam of claim 3 , wherein the plastics component comprises primarily of from 20% to 25% by weight of the first constituent, and from 80% to 75% by weight of the second constituent.
8. The polyolefin foam of claim 3 , wherein the plastics component comprises primarily of from 25% to 30% by weight of the first constituent, and from 75% to 70% by weight of the second constituent.
9. The polyolefin foam of claim 3 , wherein the plastics component comprises primarily of from 30% to 35% by weight of the first constituent, and from 70% to 65% by weight of the second constituent.
10. The polyolefin foam of claim 3 , wherein the plastics component comprises primarily of from 35% to 40% by weight of the first constituent, and from 65% to 60% by weight of the second constituent.
11. The polyolefin foam of claim 1 , wherein the foam has a density less than 90 kg/m 3 .
12. The polyolefin foam of claim 11 , wherein the foam has a density less than 30 kg/m 3 .
13. The polyolefin foam of claim 1 , wherein the polyolefin foam is a closed-cell foam.
14. The polyolefin foam of claim 1 , wherein the density of the first constituent is from 917 to 930 kg/m 3 .
15. The polyolefin foam of claim 1 , wherein the crystallization temperatures of the two constituents differ by more than 8° C.
16. The polyolefin foam of claim 15 , wherein the crystallization temperatures differ by more than 12° C.
17. The polyolefin foam of claim 1 , wherein the melt flow index of the Ziegler-Natta catalyzed linear low density polyolefin is less than 5 g/10 minutes.
18. The polyolefin foam of claim 1 , wherein the melt flow index of the Ziegler-Natta catalyzed linear low density polyolefin is less than 3 g/10 minutes.
19. The polyolefin foam of claim 1 , wherein the polydispersity of the Ziegler-Natta catalyzed linear low density polyolefin is less than 8.
20. The polyolefin foam of claim 19 , wherein the polydispersity of the Ziegler-Natta catalyzed linear low density polyolefin is less than 5.
21. The polyolefin foam of claim 1 further including nucleating agents and aging agents.
22. The polyolefin foam of claim 1 , wherein the foam has a thickness of at least about 0.8 mm.
23. The polyolefin foam of claim 1 , wherein the first and second constituents each have a different density.
24. The polyolefin foam of claim 1 , wherein the first and second constituents each have a different melt flow index.
25. The polyolefin foam of claim 23 , wherein the first and second constituents also have a different melt flow index.
26. A non-crosslinked polyolefin foam comprising a plastics component and a blowing agent, the plastics component comprising a first constituent and a second constituent, wherein the first constituent is a Ziegler-Natta catalyzed linear low density polyethylene and the second constituent is a polypropylene, the Ziegler-Natta catalyzed linear low density polyethylene has a polydispersity of less than 10 and a melt flow index less than 10 g/10 minutes, and the foam has a density substantially the same as a foam made with 100% polypropylene under the same foaming conditions.
27. The polyolefin foam of claim 26 , wherein the second constituent is a high-melt strength polypropylene.
28. The polyolefin foam of claim 26 , wherein the foam has a thickness of at least about 0.8 mm.
29. The polyolefin foam of claim 26 , wherein the first and second constituents each have a different density.
30. The polyolefin foam of claim 26 , wherein the first and second constituents each have a different melt flow index.
31. The polyolefin foam of claim 29 , wherein the first and second constituents also have a different melt flow index.
32. A method of manufacturing a non-crosslinked polyolefin foam comprising mixing a resin comprising a first constituent and a second constituent in an extruder, adding a blowing agent to the resulting mixture, and extruding the resulting mix into foam form, wherein the first constituent is a Ziegler-Natta catalyzed linear low density polyolefin and the second constituent is a low density polyolefin, the Ziegler-Natta catalyzed linear low density polyolefin has a polydispersity of less than 10 and a melt flow index less than 10 g/10 minutes, and the foam has a density substantially the same as a foam made with 100% low density polyolefin under the same foaming conditions.
33. The method of claim 32 , wherein the second constituent is a low density polyethylene.
34. The method of claim 32 , wherein the first constituent is present in an amount from 1% to 85% by weight of the total polyolefin content.
35. The method of claim 34 , wherein the first constituent is present in an amount from 5% to 10% by weight of the total polyolefin content.
36. The method of claim 32 , wherein the first constituent is present in an amount from 10% to 15% by weight of the total polyolefin content.
37. The method of claim 32 , wherein the first constituent is present in an amount from 15% to 20% by weight of the total polyolefin content.
38. The method of claim 32 , wherein the first constituent is present in an amount from 20% to 25% by weight of the total polyolefin content.
39. The method of claim 32 , wherein the first constituent is present in an amount from 25% to 30% by weight of the total polyolefin content.
40. The method of claim 32 , wherein the first constituent is present in an amount from 30% to 35% by weight of the total polyolefin content.
41. The method of claim 32 , wherein the first constituent is present in an amount from 35% to 40% by weight of the total polyolefin content.
42. The method of claim 32 , wherein the foam is extruded to a density of less than 90 kg/m 3 .
43. The method of claim 32 , wherein the foam is a closed-cell foam.
44. The method of claim 32 , wherein the density of the first constituent is from 917 to 930 kg/m 3 .
45. The method of claim 32 , wherein the crystallization temperatures of the first and second constituents differ by more than 8° C.
46. The method of claim 45 , wherein the crystallization temperatures of the first and second constituents differ by more than 12° C.
47. The method of claim 32 , wherein the first constituent has a melt flow index of less than 5 g/10 minutes.
48. The method of claim 47 , wherein the first constituent has a melt flow index of less than 3 g/10 minutes.
49. The method of claim 32 , wherein the polydispersity of the Ziegler-Natta catalyzed linear low density polyolefin is less than 8.
50. The method of claim 49 , wherein the polydispersity of the Ziegler-Natta catalyzed linear low density polyolefin is less than 5.
51. The method of claim 32 , further including mixing nucleating agents and aging agents with the first and second constituents.
52. The method of claim 32 , wherein the resultant mixture is extruded in a twin-screw extruder.
53. The method of claim 32 further including controlling the melt temperature of the mix during extruding.
54. The method of claim 53 , wherein controlling the melt temperature includes matching the melt temperature of the mix to a pre-determined datum.
55. The method of claim 54 , wherein the pre-determined datum is determined by extruding 100% of the second constituent.
56. The foam produced according to the method of claim 32 .
57. The foam produced according to the method of claim 32 , wherein the foam has a thickness of at least about 0.8 mm.
58. The foam produced according to the method of claim 32 , wherein the first and second constituents each have a different density.
59. The foam produced according to the method of claim 32 , wherein the first and second constituents each have a different melt flow index.
60. The foam produced according to the method of claim 58 , wherein the first and second constituents also have a different melt flow index.
61. A method of manufacturing a non-crosslinked polyolefin foam comprising mixing a resin comprising a first constituent and a second constituent in an extruder, adding a blowing agent to the resulting mixture, and extruding the resultant mix into foam form, wherein the first constituent is a Ziegler-Natta catalyzed linear low density polyethylene and the second constituent is a polypropylene, the Ziegler-Natta catalyzed linear low density polyethylene has a polydispersity of less than 10 and a melt flow index less than 10 g/10 minutes, and the foam has a density substantially the same as a foam made with 100% polypropylene under the same foaming conditions.
62. The method of claim 61 , wherein the second constituent is a high-melt strength polypropylene.
63. The foam produced according to the method of claim 61 , wherein the foam has a thickness of at least about 0.8 mm.
64. The foam produced according to the method of claim 61 , wherein the first and second constituents each have a different density.
65. The foam produced according to the method of claim 61 , wherein the first and second constituents each have a different melt flow index.
66. The foam produced according to the method of claim 64 , wherein the first and second constituents also have a different melt flow index.