Thermoformable film
A thermoformable film including a polyethylene composition. The polyethylene composition includes a first polyethylene which is an ethylene copolymer having a weight average molecular weight of from 70,000 to 250,000 and a molecular weight distribution M w /M n of <2.3, a second polyethylene which is an ethylene copolymer or homopolymer having a weight average molecular weight of less than 75,000 and a molecular weight distribution M w /M n of <2.3, a third polyethylene which is an ethylene copolymer or homopolymer having a weight average molecular weight of less than 75,000 and a molecular weight distribution M w /M n of <2.3, and a fourth polyethylene which is an ethylene copolymer or homopolymer having a weight average molecular weight of from 100,000 to 250,000 and a molecular weight distribution M w /M n of >2.3, where the first polyethylene has more short chain branching than the second polyethylene or the third polyethylene. The polyethylene composition has a melt flow ratio (I 21 /I 2 ) of ≤55 and an area Dimensional Thermoformability Index (aDTI) at 105° C. of less than 15.
1. A thermoformable film, the film comprising a polyethylene composition comprising:
from 15 to 75 wt. % of a first polyethylene which is an ethylene copolymer, the first polyethylene having a weight average molecular weight Mw of from 70,000 to 250,000, a molecular weight distribution M w /M n of <2.3 and from 5 to 100 short chain branches per thousand carbon atoms;
from 5 to 50 wt. % of a second polyethylene which is an ethylene copolymer or an ethylene homopolymer, the second polyethylene having a weight average molecular weight Mw of less than 75,000, a molecular weight distribution M w /M n of <2.3 and from 0 to 20 short chain branches per thousand carbon atoms; and
from 5 to 50 wt. % of a third polyethylene which is an ethylene copolymer or an ethylene homopolymer, the second polyethylene having a weight average molecular weight Mw of less than 75,000, a molecular weight distribution M w /M n of <2.3 and from 0 to 20 short chain branches per thousand carbon atoms; and
at least 20 wt. % of a fourth polyethylene which is an ethylene copolymer or an ethylene homopolymer, the fourth polyethylene having a weight average molecular weight Mw of from 100,000 to 250,000, a molecular weight distribution M w /M n of >2.3 and from 0 to 75 short chain branches per thousand carbon atoms; wherein
the number of short chain branches per thousand carbon atoms in the first polyethylene (SCB PE-1 ) is greater than the number of short chain branches per thousand carbon atoms in the second polyethylene (SCB PE-2 ), the third polyethylene (SCB PE-3 ) and the fourth polyethylene (SCB PE-4 );
the number of short chain branches per thousand carbon atoms in the fourth polyethylene (SC BPE-4 ) is greater than the number of short chain branches per thousand carbon atoms in the second polyethylene (SCB PE-2 ) and the third polyethylene (SCB PE-3 );
the weight average molecular weight of the second polyethylene and the third polyethylene are less than the weight average molecular weight of the first polyethylene and the fourth polyethylene; and
the weight average molecular weight of the second polyethylene and the third polyethylene are within 20,000 units of each other; wherein,
the polyethylene composition has a density of ≤0.939 g/cm 3 , a T m 2 −T m 1 of less than 45° C., a melt index I 2 of from 0.1 to 10 dg/min, and a melt flow ratio, I 21 /I 2 of ≤55.
2. The thermoformable film of claim 1 wherein the polyethylene composition has an area Dimensional Thermoformability Index (aDTI) at 105° C. of less than 15.
3. The thermoformable film of claim 1 wherein the polyethylene composition has a soluble fraction in a crystallization elution fractionation (CEF) analysis of at least 7.5 weight percent.
4. The thermoformable film of claim 1 wherein the polyethylene composition has a soluble fraction in a crystallization elution fractionation (CEF) analysis of at least 10 weight percent.
5. The thermoformable film of claim 1 wherein the polyethylene composition has a melt flow ratio, I 21 /I 2 of greater than 40.
6. The thermoformable film of claim 1 wherein the weight average molecular weight of the second polyethylene and the third polyethylene are within 15,000 units of each other.
7. The thermoformable film of claim 1 wherein the weight average molecular weight of the second polyethylene and the third polyethylene are within 10,000 units of each other.
8. The thermoformable film of claim 1 wherein the polyethylene composition has a melting peak temperature in a differential scanning calorimetry (DSC) analysis at above 125° C.
9. The thermoformable film of claim 1 wherein the polyethylene composition has at least two melting peaks in a differential scanning calorimetry (DSC) analysis.
10. The thermoformable film of claim 1 wherein the first polyethylene has from 25 to 75 short chain branches per thousand carbon atoms.
11. The thermoformable film of claim 1 wherein the second polyethylene is an ethylene homopolymer.
12. The thermoformable film of claim 1 wherein the third polyethylene is an ethylene homopolymer.
13. The thermoformable film of claim 1 wherein the fourth polyethylene is an ethylene copolymer and has from 5 to 35 short chain branches per thousand carbon atoms.
14. The thermoformable film of claim 1 wherein the first polyethylene has a weight average molecular weight, Mw of from 75,000 to 200,000.
15. The thermoformable film of claim 1 wherein the second polyethylene has a weight average molecular weight, Mw of from 12,000 to 45,000.
16. The thermoformable film of claim 1 wherein the third polyethylene has a weight average molecular weight, Mw of from 12,000 to 40,000.
17. The thermoformable film of claim 1 wherein the fourth polyethylene has a weight average molecular weight, Mw of from 100,000 to 200,000.
18. The thermoformable film of claim 1 wherein the first polyethylene has a density of from 0.865 to 0.916 g/cm 3 .
19. The thermoformable film of claim 1 wherein the second polyethylene is an ethylene homopolymer having a density of from 0.940 to 0.980 g/cm 3 .
20. The thermoformable film of claim 1 wherein the third polyethylene is an ethylene homopolymer having a density of from 0.940 to 0.980 g/cm 3 .
21. The thermoformable film of claim 1 wherein the fourth polyethylene is an ethylene copolymer having a density of from 0.880 to 0.936 g/cm 3 .
22. The thermoformable film of claim 1 wherein the first polyethylene is present in from 20 to 70 wt. %.
23. The thermoformable film of claim 1 wherein the second polyethylene is present in from 10 to 40 wt. %.
24. The thermoformable film of claim 1 wherein the third polyethylene is present in from 10 to 40 wt. %.
25. The thermoformable film of claim 1 wherein the fourth polyethylene is present in from 20 to 60 wt. %.
26. The thermoformable film of claim 1 wherein the first polyethylene has a CDBI 50 of at least 75 wt. %.
27. The thermoformable film of claim 1 wherein the fourth polyethylene is a copolymer with a CDBI 50 of less than 75 wt. %.
28. The thermoformable film of claim 1 wherein the first polyethylene is a homogeneously branched ethylene copolymer.
29. The thermoformable film of claim 1 wherein the fourth polyethylene is a heterogeneously branched ethylene copolymer.
30. The thermoformable film of claim 1 wherein the first polyethylene is a made with a single site catalyst.
31. The thermoformable film of claim 1 wherein the second polyethylene is made with a single site catalyst.
32. The thermoformable film of claim 1 wherein the third polyethylene is made with a single site catalyst.
33. The thermoformable film of claim 1 wherein the fourth polyethylene is made with a Ziegler-Natta catalyst.
34. The thermoformable film of claim 1 wherein the polyethylene composition has a molecular weight distribution M w /M n of from 2.3 to 8.0.
35. The thermoformable film of claim 1 wherein the polyethylene composition has a molecular weight distribution M w /M n of from 2.5 to 6.5.
36. The thermoformable film of claim 1 wherein the polyethylene composition has a density of <0.935 g/cm 3 .
37. The thermoformable film of claim 1 wherein the polyethylene composition has a density of from 0.880 to 0.932 g/cm 3 .
38. The thermoformable film of claim 1 wherein the polyethylene composition has a melt index, I 2 of from 0.1 to 3.0 dg/min.
39. The thermoformable film of claim 1 wherein the polyethylene composition has a M Z /M w of less than 4.0.
40. The thermoformable film of claim 1 wherein the polyethylene composition has a melt index ratio, I 21 /I 2 of from greater than 40 to 50.
41. The thermoformable film of claim 1 wherein the polyethylene composition has a melt index ratio, I 21 /I 2 of greater than 45.
42. The thermoformable film of claim 1 wherein the film is a single layer film.
43. The thermoformable film of claim 1 wherein the film is a multilayer film.