Dual component LLDPE copolymers with improved impact and tear resistance, and methods of their preparation

1. A film comprising an ethylene polymer composition, the composition comprising:

(i) a homogeneously-branched first ethylene polymer component having a ratio of HLMI/MI in a range from about 12 to about 25; and

(ii) a homogeneously-branched second ethylene polymer component of higher density than the first ethylene polymer component, the second ethylene polymer component having a ratio of HLMI/MI in a range from about 12 to about 25;

wherein the amount of the second ethylene polymer component is in a range from about 15 to about 35 wt. %, based on the total weight of the first ethylene polymer component and the second ethylene polymer component; and

wherein the composition is characterized by:

a density in a range from about 0.912 to about 0.925 g/cm 3 ;

a ratio of Mw/Mn in a range from about 2 to 3;

a melt index from about 0.3 to about 2 g/10 min;

a CY-a parameter in a range from about 0.35 to about 0.7; and

an ATREF curve containing at least two peaks, with a first peak at a temperature in a range from about 60 to about 72° C., and a second peak at a temperature in a range from about 92 to about 104° C.

2. The film of claim 1 , wherein the film has:

a ratio of MD Elmendorf tear strength to TD Elmendorf tear strength (MD:TD) in a range from about 0.25:1 to about 0.8:1; and

a MD Elmendorf tear strength in a range from about 100 to about 500 g/mil.

3. The film of claim 1 , wherein the film is a blown film having an average thickness in a range from about 0.5 to about 8 mils.

4. The film of claim 1 , wherein the film has:

a haze of less than or equal to about 10%; and

a dart impact strength of greater than or equal to about 250 g/mil.

5. The film of claim 1 , wherein the film has:

a MD Elmendorf tear strength in a range from about 125 to about 425 g/mil; and

a TD Elmendorf tear strength in a range from about 200 to about 800 g/mil.

6. The film of claim 1 , wherein:

the composition has a Mw in a range from about 100 to about 200 kg/mol;

the composition comprises an ethylene homopolymer, an ethylene/α-olefin copolymer, or a combination thereof; and

the composition contains no measurable amount of hafnium or titanium.

7. The film of claim 1 , wherein:

the density is in a range from about 0.915 to about 0.925 g/cm 3 ;

the ratio of Mw/Mn is in a range from about 2.2 to 3;

the melt index is in a range from about 0.5 to about 1.8 g/10 min; and

the CY-a parameter is in a range from about 0.4 to about 0.65.

8. The film of claim 1 , wherein the amount of the second ethylene polymer component is in a range from about 20 to about 30 wt. %, based on the total weight of the first ethylene polymer component and the second ethylene polymer component.

9. The film of claim 1 , wherein a ratio of the Mw of the first ethylene polymer component to the Mw of the second ethylene polymer component is in a range from about 0.8:1 to about 1.2:1.

10. The film of claim 1 , wherein a difference between the temperatures (ΔT) of the first peak and the second peak is in a range from about 26 to about 39° C.

11. The film of claim 1 , wherein the first peak is at a temperature in a range from about 63 to about 69° C., and the second peak is at a temperature in a range from about 94 to about 102° C.

12. An ethylene polymer composition comprising:

(i) a homogeneously-branched first ethylene polymer component having a ratio of HLMI/MI in a range from about 12 to about 25; and

(ii) a homogeneously-branched second ethylene polymer component of higher density than the first ethylene polymer component, the second ethylene polymer component having a ratio of HLMI/MI in a range from about 12 to about 25;

wherein the amount of the second ethylene polymer component is in a range from about 15 to about 35 wt. %, based on the total weight of the first ethylene polymer component and the second ethylene polymer component; and

wherein the composition is characterized by:

a density in a range from about 0.912 to about 0.925 g/cm 3 ;

a ratio of Mw/Mn in a range from about 2 to 3;

a melt index from about 0.3 to about 2 g/10 min;

a CY-a parameter in a range from about 0.35 to about 0.7; and

an ATREF curve containing at least two peaks, with a first peak at a temperature in a range from about 60 to about 72° C., and a second peak at a temperature in a range from about 92 to about 104° C.

13. The composition of claim 12 , wherein the composition:

has a Mw in a range from about 100 to about 200 kg/mol;

has a unimodal molecular weight distribution;

contains no measurable amount of hafnium or titanium; and

contains less than 10 long chain branches (LCB) per million total carbon atoms.

14. The composition of claim 12 , wherein:

the composition comprises an ethylene homopolymer, an ethylene/α-olefin copolymer, or a combination thereof;

the composition is a single reactor product; and

a difference between the temperatures (ΔT) of the first peak and the second peak is in a range from about 26 to about 39° C.

15. The composition of claim 12 , wherein:

the composition comprises an ethylene homopolymer, an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, an ethylene/1-octene copolymer, or any combination thereof;

the composition is a post-reactor blend; and

the first peak is at a temperature in a range from about 63 to about 69° C., and the second peak is at a temperature in a range from about 94 to about 102° C.

16. The composition of claim 12 , wherein:

the ratio of Mw/Mn is in a range from about 2.2 to 3;

the melt index is in a range from about 0.5 to about 1.8 g/10 min; and

the CY-a parameter is in a range from about 0.4 to about 0.65; and

the composition comprises an ethylene homopolymer, an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, an ethylene/1-octene copolymer, or any combination thereof.

17. The composition of claim 16 , wherein the first peak is at a temperature in a range from about 63 to about 69° C., and the second peak is at a temperature in a range from about 94 to about 102° C.

18. The composition of claim 16 , wherein the composition contains:

no measurable amount of hafnium or titanium; and

less than 10 long chain branches (LCB) per million total carbon atoms.

19. The composition of claim 16 , wherein the composition has a Mw in a range from about 100 to about 200 kg/mol.

20. The composition of claim 16 , wherein a difference between the temperatures (ΔT) of the first peak and the second peak is in a range from about 26 to about 39° C.

21. The composition of claim 16 , wherein the composition has:

a ratio of HLMI/MI in a range from about 12 to about 25; and

a ratio of Mz/Mw in a range from about 1.7 to about 2.2.

22. An ethylene polymer composition comprising:

(i) a homogeneously-branched first ethylene polymer component; and

(ii) a homogeneously-branched second ethylene polymer component of higher density than the first ethylene polymer component, the second ethylene polymer component having a density in a range from about 0.945 to about 0.965 g/cm 3 and a component melt index from about 0.5 to about 40 g/10 min;

wherein the amount of the second ethylene polymer component is in a range from about 15 to about 35 wt. %, based on the total weight of the first ethylene polymer component and the second ethylene polymer component; and

wherein the composition is characterized by:

a density in a range from about 0.912 to about 0.925 g/cm 3 ;

a ratio of Mw/Mn in a range from about 2 to about 5;

a melt index less than or equal to about 2 g/10 min;

a CY-a parameter in a range from about 0.35 to about 0.7; and

an ATREF curve containing at least two peaks, with a first peak at a temperature in a range from about 60 to about 72° C., and a second peak at a temperature in a range from about 92 to about 104° C.

23. The composition of claim 22 , wherein:

the ratio of Mw/Mn is in a range from about 2 to about 3.5;

the melt index is in a range from about 0.3 to about 2 g/10 min;

the CY-a parameter is in a range from about 0.4 to about 0.65; and

the composition comprises an ethylene homopolymer, an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, an ethylene/1-octene copolymer, or any combination thereof.

24. The composition of claim 23 , wherein the composition:

has a Mw in a range from about 100 to about 200 kg/mol;

has a ratio of Mz/Mw in a range from about 1.7 to about 2.2; and

contains no measurable amount of hafnium or titanium.

25. The composition of claim 24 , wherein:

the first peak is at a temperature in a range from about 63 to about 69° C., and the second peak is at a temperature in a range from about 94 to about 102° C.; and

a difference between the temperatures (ΔT) of the first peak and the second peak is in a range from about 26 to about 39° C.

26. A film comprising the ethylene polymer composition of claim 24 .

27. A film comprising the ethylene polymer composition of claim 22 , wherein the film has:

a ratio of MD Elmendorf tear strength to TD Elmendorf tear strength (MD:TD) in a range from about 0.25:1 to about 0.8:1;

a MD Elmendorf tear strength in a range from about 100 to about 500 g/mil;

a haze of less than or equal to about 10%; and

a dart impact strength of greater than or equal to about 250 g/mil.

28. An ethylene polymer composition comprising:

(i) a homogeneously-branched first ethylene polymer component containing less than 8 long chain branches (LCB) per million total carbon atoms;

(ii) a homogeneously-branched second ethylene polymer component of higher density than the first ethylene polymer component, the second ethylene polymer component having a density in a range from about 0.94 to about 0.97 g/cm 3 and a component melt index of less than or equal to about 50 g/10 min;

wherein the amount of the second ethylene polymer component is in a range from about 15 to about 35 wt. %, based on the total weight of the first ethylene polymer component and the second ethylene polymer component;

wherein the composition contains no measurable amount of titanium; and

wherein the composition is characterized by:

a density in a range from about 0.912 to about 0.925 g/cm 3 ;

a ratio of Mw/Mn in a range from about 2 to about 5;

a melt index less than or equal to about 2 g/10 min; and

an ATREF curve containing at least two peaks, with a first peak at a temperature in a range from about 60 to about 72° C., and a second peak at a temperature in a range from about 92 to about 104° C.

29. The composition of claim 28 , wherein:

the ratio of Mw/Mn is in a range from about 2 to about 3.5;

the melt index is in a range from about 0.3 to about 2 g/10 min;

a CY-a parameter of the composition is in a range from about 0.45 to about 0.7; and

the composition comprises an ethylene homopolymer, an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, an ethylene/1-octene copolymer, or any combination thereof.

30. A film comprising the ethylene polymer composition of claim 29 , wherein the film has:

a ratio of MD Elmendorf tear strength to TD Elmendorf tear strength (MD:TD) in a range from about 0.25:1 to about 0.8:1;

a MD Elmendorf tear strength in a range from about 100 to about 500 g/mil;

a haze of less than or equal to about 10%; and

a dart impact strength of greater than or equal to about 250 g/mil.

31. The composition of claim 29 , wherein the composition:

has a Mw in a range from about 100 to about 200 kg/mol;

has a ratio of Mz/Mw in a range from about 1.7 to about 2.2; and

contains less than 5 long chain branches (LCB) per million total carbon atoms.

32. A film comprising the ethylene polymer composition of claim 21 , wherein a difference between the temperatures (ΔT) of the first peak and the second peak is in a range from about 26 to about 39° C.

33. The composition of claim 22 , wherein the component melt index of the second ethylene polymer component is from about 0.5 to about 8 g/10 min.

34. The composition of claim 28 , wherein the component melt index of the second ethylene polymer component is less than or equal to about 10 g/10 min.