Polyethylene films and method of making the same
View Patent ↗The instant invention is a polyethylene film, and method of making the same. The polyethylene film according to instant invention includes at least one heterogeneously branched ethylene/α-olefin copolymer having a density in the range of about 0.910 to about 0.930 g/cm 3 , a molecular weight distribution in the range of about 2.8 to 3.8, a melt index (I 2 ) in the range of about 0.3 to about 4 g/10 min, and an I 10 /I 2 ratio in the range of 6.5 to about 7.8. The film has a normalized dart impact strength of equal or greater than (6666-7012*density) g/mil, a normalized tear strength of equal or greater than (440*e−(density−0.915) 2 /2*(0.00949) 2 ) g/mil, and a haze in the range of 3 to 10 percent. The method of making the polyethylene film according to instant invention includes the following steps: (1) providing at least one heterogeneously branched ethylene/α-olefin copolymer having a density in the range of about 0.910 to about 0.930 g/cm 3 , a molecular weight distribution in the range of about 2.8 to 3.8, a melt index (I 2 ) in the range of about 0.3 to about 4 g/10 min, and an I 10 /I 2 ratio in the range of 6.5 to about 7.8; (2) processing the heterogeneously branched ethylene/α-olefin copolymer via blown film extrusion process or cast film extrusion process; and (3) thereby forming a film having a normalized dart impact strength of equal or greater than (6666-7012*density) g/mil, a normalized tear strength of equal or greater than (440*e−(density−0.915) 2 /2*(0.00949) 2 ) g/mil, and a haze in the range of 3 to 10 percent.
1. A polyethylene film comprising:
at least one heterogeneously branched ethylene/α-olefin copolymer, wherein said heterogeneously branched ethylene/α-olefin copolymer was obtained via polymerization of ethylene and one or more α-olefins in the presence of a multi-constituent catalyst system in a single reactor, wherein said multi-constituent catalyst system comprises a magnesium and titanium containing pro-catalyst and a cocatalyst, wherein said cocatalyst is a modified alkyl aluminum compound, wherein said heterogeneously branched ethylene/α-olefin copolymer having a density in the range of about 0.910 to about 0.930 g/cm 3 , a molecular weight distribution in the range of about 2.8 to 3.8, a melt index (I 2 ) in the range of about 0.3 to about 4 g/10 min, and an I 10 /I 2 ratio in the range of 6.5 to about 7.8;
wherein said film having a normalized dart impact strength of equal or greater than (6666-7012*density) g/mil, a normalized tear strength of equal or greater than
(
440
*
ⅇ
-
(
density
-
0.915
)
2
2
*
(
0.00949
)
2
)
g/mil, and a haze in the range of 3 to 10 percent.
2. The polyethylene film according to claim 1 , wherein said film having a thickness in the range of 10 to 75 μm.
3. The polyethylene film according to claim 1 , wherein said film having a normalized dart impact strength of equal or greater than (6690-7012*density) g/mil, a normalized tear strength of equal or greater than
(
470
*
ⅇ
-
(
density
-
0.915
)
2
2
*
(
0.00949
)
2
)
g/mil, and a haze in the range of 3 to 8 percent.
4. The polyethylene film according to claim 1 , wherein said heterogeneously branched ethylene/α-olefin copolymer being an ethylene-1-octene copolymer.
5. An article comprising the polyethylene film of claim 1 .
6. The article according to claim 5 , wherein said film having a thickness in the range of 10 to 75 μm.
7. The article according to claim 5 , wherein said film having a normalized dart impact strength of equal or greater than (6690-7012*density) g/mil, a normalized tear strength of equal or greater than
(
470
*
ⅇ
-
(
density
-
0.915
)
2
2
*
(
0.00949
)
2
)
g/mil, and a haze in the range of 3 to 8 percent.
8. The article according to claim 5 , wherein said heterogeneously branched ethylene/α-olefin copolymer being an ethylene-1-octene copolymer.
9. A method of producing a polyethylene film comprising the steps of:
providing at least one heterogeneously branched ethylene/α-olefin copolymer, wherein said heterogeneously branched ethylene/α-olefin copolymer was obtained via polymerization of ethylene and one or more α-olefins in the presence of a multi-constituent catalyst system in a single reactor, wherein said multi-constituent catalyst system comprises a magnesium and titanium containing pro-catalyst and a cocatalyst, wherein said cocatalyst is a modified alkyl aluminum compound, wherein said heterogeneously branched ethylene/α-olefin copolymer has a density in the range of about 0.910 to about 0.930 g/cm 3 , a molecular weight distribution in the range of about 2.8 to 3.8, a melt index (I 2 ) in the range of about 0.3 to about 4 g/10 min, and an I 10 /I 2 ratio in the range of 6.5 to about 7.8;
processing said heterogeneously branched ethylene/α-olefin copolymer via blown film extrusion process or cast film extrusion process; and
thereby forming said film having a normalized dart impact strength of equal or greater than (6666-7012*density) g/mil, a
(
440
*
ⅇ
-
(
density
-
0.915
)
2
2
*
(
0.00949
)
2
)
normalized tear strength of equal or greater than g/mil, and a haze in the range of 3 to 10 percent.
10. A multilayer film comprising at least one polyethylene film of claim 1 .