Dual catalyst system for producing LLDPE and MDPE copolymers with long chain branching for film applications

1. An ethylene polymer having:

a melt index in a range from 0 to about 15 g/10 min;

a density in a range from about 0.91 to about 0.945 g/cm 3 ;

a CY-a parameter at 190° C. in a range from about 0.2 to about 0.6;

an average number of long chain branches (LCBs) per 1,000,000 total carbon atoms of the ethylene polymer in a molecular weight range of 500,000 to 2,000,000 g/mol of less than or equal to about 5; and

a maximum ratio of extensional viscosity to three times shear viscosity, η E /3η, at an extensional rate of 0.03 sec −1 in a range from about 3 to about 15.

2. An article of manufacture comprising the ethylene polymer of claim 1 .

3. The ethylene polymer of claim 1 , wherein:

the average number of LCBs per 1,000,000 total carbon atoms of the ethylene polymer in the molecular weight range of 500,000 to 2,000,000 g/mol is less than or equal to about 2; and

the maximum ratio of η E /3η at the extensional rate of 0.03 sec −1 is in a range from about 4 to about 12.

4. The ethylene polymer of claim 1 , wherein:

the melt index is in a range from about 0.4 to about 4 g/10 min;

the density is in a range from about 0.92 to about 0.94 g/cm 3 ; and

the CY-a parameter at 190° C. is in a range from about 0.3 to about 0.55.

5. The ethylene polymer of claim 4 , wherein the ethylene polymer comprises an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, an ethylene/1-octene copolymer, or a combination thereof.

6. The ethylene polymer of claim 5 , wherein the ethylene polymer has a ratio of HLMI/MI in a range from about 20 to about 80.

7. An article of manufacture comprising the ethylene polymer of claim 5 .

8. The ethylene polymer of claim 1 , wherein the ethylene polymer has:

a ratio of Mw/Mn in a range from about 3 to about 6; and

a ratio of Mz/Mw in a range from about 2 to about 4.5.

9. The ethylene polymer of claim 1 , wherein the ethylene polymer has:

a Mn in a range from about 10,000 to about 50,000 g/mol;

a Mw in a range from about 50,000 to about 250,000 g/mol; and

a Mz in a range from about 200,000 to about 550,000 g/mol.

10. The ethylene polymer of claim 1 , wherein the ethylene polymer contains from about 1 to about 10 LCBs per 1,000,000 total carbon atoms.

11. The ethylene polymer of claim 1 , wherein the ethylene polymer has a number of short chain branches (SCBs) per 1000 total carbon atoms of the ethylene polymer at Mn that is greater than at Mz.

12. The ethylene polymer of claim 1 , wherein the ethylene polymer has a maximum ratio of η E /3η at an extensional rate of 0.1 sec −1 in a range from about 2 to about 10.

13. The ethylene polymer of claim 1 , wherein the ethylene polymer comprises an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, an ethylene/1-octene copolymer, or a combination thereof.

14. The ethylene polymer of claim 13 , wherein:

the melt index is in a range from about 0.4 to about 4 g/10 min;

the density is in a range from about 0.91 to about 0.94 g/cm 3 ; and

the CY-a parameter at 190° C. is in a range from about 0.3 to about 0.6.

15. The ethylene polymer of claim 14 , wherein the ethylene polymer has:

an D3 parameter in a range from about 1.1 to about 1.8;

a relaxation time in a range from about 0.002 to about 0.025 sec.

16. The ethylene polymer of claim 14 , wherein the ethylene polymer has an ATREF profile characterized by:

a peak ATREF temperature in a range from about 88 to about 98° C.;

from about 0.5 to about 6 wt % of the ethylene polymer eluting below a temperature of 40° C.;

from about 12 to about 26 wt % of the ethylene polymer eluting between 40 and 76° C.;

from about 52 to about 82 wt % of the ethylene polymer eluting above a temperature of 86° C.; and

a remainder of the ethylene polymer eluting between 76 and 86° C.

17. The ethylene polymer of claim 16 , wherein:

the peak ATREF temperature is in a range from about 90 to about 96° C.;

from about 1 to about 5 wt % of the ethylene polymer is eluted below a temperature of 40° C.;

from about 13 to about 24 wt % of the ethylene polymer is eluted between 40 and 76° C.;

from about 58 to about 75 wt % of the ethylene polymer is eluted above a temperature of 86° C.; and

the remainder of the ethylene polymer is eluted between 76 and 86° C.

18. A film comprising the ethylene polymer of claim 17 .

19. The ethylene polymer of claim 14 , wherein the ethylene polymer contains less than 0.1 ppm, independently, of chromium and titanium.

20. A film comprising the ethylene polymer of claim 14 , wherein the film has:

a MD Elmendorf tear strength in a range from about 40 to about 250 g/mil;

a ratio of MD Elmendorf tear strength to TD Elmendorf tear strength (MD:TD) in a range from about 0.15:1 to about 0.55:1; and

a haze in a range from about 3 to about 10%.

21. The film of claim 20 , wherein the film has an average thickness in a range from about 0.5 to about 8 mils.

22. The ethylene polymer of claim 13 , wherein:

the melt index is in a range from about 0.1 to about 10 g/10 min;

the density is in a range from about 0.91 to about 0.94 g/cm 3 ;

the CY-a parameter at 190° C. is in a range from about 0.3 to about 0.55;

the average number of LCBs per 1,000,000 total carbon atoms of the ethylene polymer in a molecular weight range of 500,000 to 2,000,000 g/mol is less than or equal to about 3; and

the maximum ratio of η E /3η at and extensional rate of 0.03 sec −1 is in a range from about 4 to about 12.

23. The ethylene polymer of claim 13 , wherein:

the ethylene polymer has a ratio of Mw/Mn in a range from about 3.5 to about 8; and

the ethylene polymer contains from about 1 to about 10 LCBs per 1,000,000 total carbon atoms.

24. The ethylene polymer of claim 23 , wherein:

the ethylene polymer has a Mw in a range from about 70,000 to about 185,000 g/mol;

the ethylene polymer has a maximum ratio of η E /3η at an extensional rate of 0.1 sec −1 in a range from about 2 to about 10; and

the ethylene polymer contains less than 0.1 ppm, independently, of chromium and titanium.

25. An article of manufacture comprising the ethylene polymer of claim 23 .

26. The ethylene polymer of claim 13 , wherein:

the melt index is in a range from about 0.4 to about 4 g/10 min;

the density is in a range from about 0.92 to about 0.94 g/cm 3 ;

the CY-a parameter at 190° C. is in a range from about 0.3 to about 0.55;

the average number of LCBs per 1,000,000 total carbon atoms of the ethylene polymer in a molecular weight range of 500,000 to 2,000,000 g/mol is less than or equal to about 2; and

the maximum ratio of η E /3η at an extensional rate of 0.03 sec −1 is in a range from about 5 to about 9.

27. The ethylene polymer of claim 26 , wherein:

the ethylene polymer has a ratio of Mw/Mn in a range from about 3.5 to about 6;

the ethylene polymer has a relaxation time in a range from about 0.002 to about 0.025 sec;

the ethylene polymer has a maximum ratio of η E /3η at an extensional rate of 0.1 sec −1 in a range from about 3 to about 7; and

the ethylene polymer contains from about 1 to about 8 LCBs per 1,000,000 total carbon atoms.

28. An olefin polymerization process, the process comprising contacting a catalyst composition with ethylene and an olefin comonomer in a polymerization reactor system under polymerization conditions to produce an ethylene polymer, wherein:

the catalyst composition comprises:

catalyst component I comprising a single atom bridged metallocene compound with an indenyl group and a cyclopentadienyl group;

catalyst component II comprising an unbridged hafnium metallocene with two cyclopentadienyl groups;

an activator; and

optionally, a co-catalyst; and

the ethylene polymer is characterized by:

a melt index in a range from 0 to about 15 g/10 min;

a density in a range from about 0.91 to about 0.945 g/cm 3 ;

a CY-a parameter at 190° C. in a range from about 0.2 to about 0.6;

an average number of long chain branches (LCBs) per 1,000,000 total carbon atoms of the ethylene polymer in a molecular weight range of 500,000 to 2,000,000 g/mol of less than or equal to about 5; and

a maximum ratio of extensional viscosity to three times shear viscosity, η E /3η, at an extensional rate of 0.03 sec −1 in a range from about 3 to about 15.

29. The process of claim 28 , wherein the activator comprises an activator-support, an aluminoxane compound, an organoboron or organoborate compound, an ionizing ionic compound, or any combination thereof.

30. The process of claim 28 , wherein the activator comprises a fluorided solid oxide and/or a sulfated solid oxide.

31. The process of claim 30 , wherein the catalyst composition comprises an organoaluminum co-catalyst.

32. The process of claim 28 , wherein the olefin comonomer comprises a C 3 -C 10 alpha-olefin.

33. The process of claim 28 , wherein:

catalyst component I comprises a metallocene compound with a single carbon or silicon bridging atom, an unsubstituted cyclopentadienyl group, and an alkyl-substituted indenyl group; and

catalyst component II comprise an unbridged hafnium metallocene with two alkyl-substituted cyclopentadienyl groups.

34. The process of claim 33 , wherein:

the polymerization reactor system comprises a slurry reactor, a gas-phase reactor, a solution reactor, or a combination thereof; and

the ethylene polymer comprises an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, and/or an ethylene/1-octene copolymer.