Single reactor bimodal polyethylene with improved modulus for extrusion blow molding drum applications
In various embodiments, a bimodal polyethylene composition may have a density (ρ) from 0.952 g/cm 3 to 0.957 g/cm 3 , a high load melt index (I 21 ) from 1 to 10 dg/min, and a z-average molecular weight (M z(GPC) ) from 3,200,000 to 5,000,000 g/mol. The bimodal polyethylene composition may also have a peak molecular weight (M p(GPC) ) defined by the equation: M p(GPC) <−2,805.3 MWD+102,688, wherein MWD is a molecular weight distribution defined by the equation: MWD=M w(GPC) /M n(GPC) , M w(GPC) is a weight average molecular weight of the bimodal polyethylene composition, M n(GPC ) is a number average molecular weight of the bimodal polyethylene composition. Additionally, the bimodal polyethylene composition has a ratio of the (Mz(GPC)) to the Mw(GPC) from 8.5 to 10.5. Articles made from the bimodal polyethylene composition, such as articles made by blow molding processes, are also provided.
1 . A bimodal polyethylene composition having:
a density (ρ) from 0.952 g/cm 3 to 0.957 g/cm 3 when measured according to ASTM D792-08, Method B;
a high load melt index (I 21 ) from 1.0 to 10 dg/min when measured according to ASTM D1238 at 190° C. and a 21.6 kg load;
a peak molecular weight (M p(GPC) ) defined by the equation: M p(GPC) <−2,805.3×MWD+102,688, wherein MWD is a molecular weight distribution defined by the equation: MWD=M w(GPC) /M n(GPC) , M w(GPC) is a weight average molecular weight of the bimodal polymer composition, and M n(GPC) is a number average molecular weight of the bimodal polymer composition, and wherein M p(GPC) , M w(GPC) , and M n(GPC) are measured using gel permeation chromatography (GPC), wherein the M n(GPC) is greater than 28,000 g/mol;
a z-average molecular weight (M z(GPC) ) greater than 3,200,000 and less than or equal to 5,000,000 g/mol as measured using GPC; and
a ratio of the (M z(GPC) ) to the M w(GPC) is from 8.5 to 10.5;
wherein the M p(GPC) is from 55,000 g/mol to 65,000 g/mol; and
wherein the bimodal polyethylene composition is a polymerized reaction product of an ethylene monomer and at least one C3-C12 α-olefin comonomer.
2 . The bimodal polyethylene composition of claim 1 , wherein the M w(GPC) is greater than 380,000 g/mol.
3 . The bimodal polyethylene composition of claim 1 having:
a secant modulus(E s ) defined by the equation: E s >−2,622+2,822×ρ+2.5×MFR 5 , wherein MFR 5 is a ratio of the high load melt index (I 21 ) to a melt index (I 5 ) of the bimodal polyethylene composition measured according to ASTM D1238 at 190° C. and a 5.0 kg load;
a secant modulus (E s ) defined by the equation: E s >−4,570.6+4,883×ρ+3.1×MWD;
or both.
4 . The bimodal polyethylene composition of claim 1 , wherein the M w(GPC) is from 380,000 g/mol to 500,000 g/mol.
5 . The bimodal polyethylene composition of claim 1 , wherein MFR 5 is from 20 to 32, wherein MFR 5 is a ratio of the high load melt index (I 21 ) to a melt index (I 5 ) of the bimodal polyethylene composition measured according to ASTM D1238 at 190° C. and a 5.0 kg load.
6 . The bimodal polyethylene composition of claim 1 , wherein the M n(GPC) is from greater than 28,000 g/mol and less than or equal to 40,000 g/mol.
7 . The bimodal polyethylene composition of claim 1 , wherein a secant modulus (E s ) of the bimodal polyethylene composition is greater than 965 MPa.
8 . The bimodal polyethylene composition of claim 1 , having an environmental stress-cracking resistance F 50 greater than 150 hours when measured according to ASTM D1693, Procedure B, 10% Igepal.
9 . An article manufactured using the bimodal polyethylene composition of claim 1 .
10 . The article of claim 9 , wherein the article is a blow molded article.
11 . A method for producing the bimodal polyethylene composition of claim 1 , comprising polymerizing via gas-phase polymerization ethylene and at least one C 3 -C 12 α-olefin comonomer in the presence of a main catalyst and a trim catalyst in a single reactor to produce the bimodal polyethylene composition.
12 . A bimodal polyethylene composition having:
a density (ρ) from 0.952 g/cm 3 to 0.957 g/cm 3 when measured according to ASTM D792-08, Method B;
a high load melt index (I 21 ) from 1.0 to 10 dg/min when measured according to ASTM D1238 at 190° C. and a 21.6 kg load;
a peak molecular weight (M p(GPC) ) defined by the equation: M p(GPC) <−2,805.3×MWD+102,688, wherein MWD is a molecular weight distribution defined by the equation: MWD=M w(GPC) /M n(GPC) , M w(GPC) is a weight average molecular weight of the bimodal polymer composition, and M n(GPC) is a number average molecular weight of the bimodal polymer composition, and wherein M p(GPC) , M w(GPC) , and M n(GPC) are measured using gel permeation chromatography (GPC), wherein the M n(GPC) is greater than 28,000 g/mol
a z-average molecular weight (M z(GPC) ) greater than 3,200,000 and less than or equal to 5,000,000 g/mol as measured using GPC;
a ratio of the (M z(GPC) ) to the M w(GPC) is from 8.5 to 10.5;
a secant modulus (E s ) defined by the equation: E s >−2,622+2,822×ρ+2.5×MFR 5 , wherein MFR 5 is a ratio of the high load melt index (I 21 ) to a melt index (I 5 ) of the bimodal polyethylene composition measured according to ASTM D1238 at 190° C. and a 5.0 kg load;
a secant modulus (E s ) defined by the equation: E s >−4,570.6+4,883×ρ+3.1×MWD;
or both.
13 . The bimodal polyethylene composition of claim 12 , wherein the M p(GPC) is from 55,000 g/mol to 65,000 g/mol.
14 . The bimodal polyethylene composition of claim 12 , wherein the M w(GPC) is greater than 380,000 g/mol.
15 . A bimodal polyethylene composition having:
a density (ρ) from 0.952 g/cm 3 to 0.957 g/cm 3 when measured according to ASTM D792-08, Method B;
a high load melt index (I 21 ) from 1.0 to 10 dg/min when measured according to ASTM D1238 at 190° C. and a 21.6 kg load;
a peak molecular weight (M p(GPC) ) defined by the equation: M p(GPC) <−2,805.3×MWD+102,688, wherein MWD is a molecular weight distribution defined by the equation: MWD=M w(GPC) /M n(GPC) , M w(GPC) is a weight average molecular weight of the bimodal polymer composition, and M n(GPC) is a number average molecular weight of the bimodal polymer composition, and wherein M p(GPC) , M w(GPC) , and M n(GPC) are measured using gel permeation chromatography (GPC), wherein the M n(GPC) is greater than 28,000 g/mol
a z-average molecular weight (M z(GPC) ) greater than 3,200,000 and less than or equal to 5,000,000 g/mol as measured using GPC; and
a ratio of the (M z(GPC) ) to the M w(GPC) is from 8.5 to 10.5;
wherein a secant modulus (E s ) of the bimodal polyethylene composition is greater than 965 MPa.
16 . The bimodal polyethylene composition of claim 15 , wherein the bimodal polyethylene composition is a polymerized reaction product of an ethylene monomer and at least one C3-C12 α-olefin comonomer.
17 . The bimodal polyethylene composition of claim 15 , wherein the M w(GPC) is from 380,000 g/mol to 500,000 g/mol.