Polymers with improved ESCR for blow molding applications
AssigneeChevron Phillips Chemical Company LP
InventorsVivek Rohatgi, Jeffrey F. Greco, Yongwoo Inn, Qing Yang, Alfred E. Brown, Jr.
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Abstract
Disclosed herein are ethylene-based polymers having a higher molecular weight component and a lower molecular weight component, and characterized by a density greater than 0.945 g/cm3, a melt index less than 1.5 g/10 min, and a ratio of high load melt index to melt index ranging from 40 to 175. These polymers have the processability of chromium-based resins, but with improved stiffness and stress crack resistance, and can be used in blow molding and other end-use applications.
Claims20
A polymerization process comprising:
- contacting a catalyst composition with ethylene and an olefin comonomer in a polymerization reactor system under polymerization conditions to produce an ethylene polymer;
- wherein the ethylene polymer comprises a higher molecular weight component and a lower molecular weight component, and wherein the ethylene polymer is characterized by:
- a density in a range from about 0.95 to about 0.965 g/cm3;
- a melt index (MI) in a range from about 0.05 to about 1.5 g/10 min;
- a ratio of high load melt index to melt index (HLMI/MI) in a range from about 40 to about 175;
- a bimodal molecular weight distribution;
- less than about 0.008 long chain branches per 1000 total carbon atoms;
- a number of short chain branches per 1000 total carbon atoms at Mz that is greater than or equal to the number at Mn;
- and
- a slope of a plot of the viscosity (Pa-sec) versus shear rate (sec−1) at 190° C. of the ethylene polymer at 100 sec−1 in a range from about 0.42 to about 0.65.
A polymerization process comprising:
- contacting a catalyst composition with ethylene and an olefin comonomer in a polymerization reactor system under polymerization conditions to produce an ethylene polymer;
- wherein the ethylene polymer comprises a higher molecular weight component and a lower molecular weight component, and wherein the ethylene polymer is characterized by:
- a density in a range from about 0.95 to about 0.965 g/cm3;
- a melt index (MI) in a range from about 0.05 to about 1.5 g/10 min;
- a ratio of high load melt index to melt index (HLMI/MI) in a range from about 40 to about 175;
- a Mp of the higher molecular weight component in a range from about 650,000 to about 1,100,000 g/mol;
- a Mp of the lower molecular weight component in a range from about 40,000 to about 80,000 g/mol;
- less than about 0.008 long chain branches per 1000 total carbon atoms;
- a number of short chain branches per 1000 total carbon atoms at Mz that is greater than or equal to the number at Mn;
- and
- a ratio of Mw/Mn in a range from about 5 to about 18.
An ethylene/α-olefin copolymer comprising a higher molecular weight component and a lower molecular weight component, wherein the ethylene/α-olefin copolymer is characterized by:
- a density in a range from about 0.95 to about 0.965 g/cm3;
- a melt index (MI) in a range from about 0.05 to about 1.5 g/10 min;
- a ratio of high load melt index to melt index (HLMI/MI) in a range from about 40 to about 175;
- a bimodal molecular weight distribution;
- a Mp of the higher molecular weight component in a range from about 650,000 to about 1,100,000 g/mol;
- a Mp of the lower molecular weight component in a range from about 40,000 to about 80,000 g/mol;
- a ratio of Mw/Mn in a range from about 5 to about 18;
- less than about 0.008 long chain branches per 1000 total carbon atoms;
- a number of short chain branches per 1000 total carbon atoms at Mz that is greater than or equal to the number at Mn;
- and
- a slope of a plot of the viscosity (Pa-sec) versus shear rate (sec−1) at 190° C. of the ethylene/α-olefin copolymer at 100 sec−1 in a range from about 0.42 to about 0.65.
Dependencies are inferred from the claim text.