Ethylene-based resins for closure applications

1. A Ziegler-Natta catalyzed ethylene-based resin comprising a high molecular weight component and a low molecular weight component, wherein the high molecular weight component comprises an ethylene/alpha-olefin copolymer or ethylene homopolymer, and has a density ranging from 0.945 g/cc to 0.960 g/cc, a high load melt index (I 21.6 ) ranging from 4 g/10 min to 15 g/10 min, and a melt flow ratio (I 21.6 /I 2.16 ) ranging from 25 to 40,

wherein the ethylene-based resin has:

an overall density ranging from greater than 0.962 g/cc to less than or equal to 0.970 g/cc;

an overall melt index (I 2.16 ) ranging from 0.5 g/10 min to 6 g/10 min;

a high load melt index (I 21.6 ) ranging from 125 to 300 g/10 min;

an overall melt flow ratio (I 21.6 /I 2.16 ) ranging from 40 to 90;

less than 0.2 vinyls per 1000 carbon atoms; and

a ratio of weight average molecular weight to number average molecular weight,

Mw/Mn, ranging from 6 to 12; and

wherein the ethylene-based resin has an environmental stress crack resistance (ESCR) (F 50 ) according to ASTM D-1693, condition B at 50° C. using 100% nonylphenol ethoxylate with 9 moles of ethylene oxide, in the range of 10 to 60 hours.

2. The resin of claim 1 , wherein the ethylene-based resin comprises from 35% to about 55% by weight of the high molecular weight component.

3. The resin of claim 1 , wherein the ethylene-based resin has a flexural, 2% secant modulus greater than 200,000 psi.

4. The resin of claim 1 , wherein the low molecular weight component comprises an ethylene homopolymer.

5. The resin of claim 1 , wherein the low molecular weight component has a density that is at least 0.005 g/cc higher than the density of the high molecular weight component.

6. The resin of claim 1 , wherein the ethylene-based resin has a weight average molecular weight, Mw, of from 75,000 g/mole to 115,000 g/mole.

7. A closure comprising the ethylene-based resin of claim 1 .

8. A method of manufacturing an ethylene-based resin, the method comprising:

polymerizing a high molecular weight component comprising an ethylene/alpha-olefin copolymer or ethylene homopolymer in a reactor using a Ziegler-Natta catalyst, wherein the high molecular weight component has a density ranging from 0.945 g/cc to 0.960 g/cc, a high load melt index (I 21.6 ) ranging from 4 g/10 min to 15 g/10 min, and a melt flow ratio (I 21.6 /I 2.16 ) ranging from 25 to 40; and

polymerizing a low molecular weight component in a different reactor, thereby producing an ethylene-based resin;

wherein the two reactors are operated in series; and

wherein the ethylene-based resin has:

an overall density ranging from greater than 0.962 g/cc to less than or equal to 0.970 g/cc;

an overall melt index (I 2.16 ) ranging from 0.5 g/10 min to 6 g/10 min;

a high load melt index (I 21.6 ) ranging from 125 to 300 g/10 min;

an overall melt flow ratio (I 21.6 /I 2.16 ) ranging from 40 to 90;

less than 0.2 vinyls per 1000 carbon atoms; and

a ratio of weight average molecular weight to number average molecular weight,

Mw/Mn, ranging from 6 to 12;

wherein the ethylene-based resin has an environmental stress crack resistance (ESCR) (F 50 ) according to ASTM D-1693, condition B at 50° C. using 100% nonylphenol ethoxylate with 9 moles of ethylene oxide, in the range of 10 to 60 hours.

9. The method of claim 8 , wherein the ethylene-based resin comprises from 35% to about 55% by weight of the high molecular weight component.

10. The method of claim 8 , wherein ethylene-based resin has a flexural, 2% secant modulus greater than 200,000 psi.

11. The method of claim 8 , wherein the low molecular weight component comprises an ethylene homopolymer.

12. The method of claim 8 , wherein the low molecular weight component has a density that is at least 0.005 g/cm 3 higher than the density of the high molecular weight component.