Higher density polyolefins with improved stress crack resistance
AssigneeChevron Phillips Chemical Company LP
InventorsMark L. Hlavinka, Errun Ding, Paul DesLauriers, Yongwoo Inn, Lili Cui, Qing Yang, Ashish Sukhadia, Guylaine St. Jean, Richard M. Buck
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Abstract
Disclosed herein are polymerization processes for the production of olefin polymers. These polymerization processes can employ a catalyst system containing two or three metallocene components, resulting in ethylene-based copolymers that can have a medium density and improved stress crack resistance.
Claims19
An ethylene/α-olefin copolymer having a density from about 0.935 to about 0.947 g/cm3, a zero-shear viscosity in a range from about 1×106 to about 1×109 Pa-sec, a CY-a parameter in a range from about 0.08 to about 0.35, a peak molecular weight (Mp) in a range from about 35,000 to about 100,000 g/mol, a bimodal molecular weight distribution, and a number of short chain branches per 1000 total carbon atoms at Mz that is greater than at Mn.
An ethylene/α-olefin copolymer having a density from about 0.935 to about 0.947 g/cm3, a bimodal molecular weight distribution, a single point notched constant tensile load (SP-NCTL) of at least 8,500 hours, and a natural draw ratio (NDR) in a range from about 400 to about 525%.
An ethylene/α-olefin copolymer having a density from about 0.930 to about 0.948 g/cm3, a Mn in a range from about 5,000 to about 30,000 g/mol, a ratio of Mw/Mn in a range from about 10 to about 50, and a relationship between natural draw ratio (NDR, %) and density (g/cm3) of the copolymer defined by the equation:
- NDR<7800(density)−6800.
Dependencies are inferred from the claim text.