Polymers with improved ESCR for blow molding applications
AssigneeChevron Phillips Chemical Company LP
InventorsJeff F Greco, Qing Yang, Vivek Rohatgi, Mark L. Hlavinka, Jim B Askew
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Abstract
Disclosed herein are ethylene-based polymers generally characterized by a density greater than 0.954 g/cm3, high load melt index ranging from 10 to 45 g/10 min, a ratio of high load melt index to melt index ranging from 175 to 600, a rheological slope parameter ranging from 0.15 to 0.30, and an ESCR in 10% igepal exceeding 800 hours. These polymers have the beneficial processability and die swell features of chromium-based resins, but with improved stiffness and stress crack resistance, and can be used in blow molding and other end-use applications.
Claims22
An ethylene polymer having a density of greater than or equal to about 0.954 g/cm3, a high load melt index (HLMI) in a range from about 10 to about 45 g/10 min, a ratio of high load melt index to melt index (HLMI/MI) in a range from about 175 to about 600, a slope of a plot of the viscosity (in Pa-sec) versus shear rate (in sec−1) of the ethylene polymer at 100 sec−1 in a range from about 0.15 to about 0.30, and an environmental stress crack resistance (ESCR, 10% igepal) of greater than or equal to about 800 hours;
- wherein:
- the ethylene polymer comprises a high molecular weight component and a low molecular weight component;
- the high molecular weight component has a Mw in a range from about 1,000,000 to about 1,500,000 g/mol, and a ratio of Mw/Mn in a range from about 1.8 to about 2.7;
- and
- the low molecular weight component has a Mw in a range from about 50,000 to about 80,000 g/mol, and a ratio of Mz/Mw in a range from about 1.6 to about 2.5.
An ethylene/α-olefin copolymer having a density in a range from about 0.9545 to about 0.962 g/cm3, a HLMI in a range from about 15 to about 35 g/10 min, a ratio of HLMI/MI in a range from about 200 to about 500, a slope of a plot of the viscosity (in Pa-sec) versus shear rate (in sec−1) of the ethylene/α-olefin copolymer at 100 sec−1 in a range from about 0.16 to about 0.28, and an ESCR of greater than or equal to about 1100 hours;
- wherein the ethylene/α-olefin copolymer is characterized by less than about 0.008 long chain branches per 1000 total carbon atoms, and a number of short chain branches per 1000 total carbon atoms at Mz that is greater than at Mn.
Dependencies are inferred from the claim text.