A bimodal polymer composition comprising a lower molecular weight homopolymer and a higher molecular weight copolymer wherein the bimodal polymer composition has a density of from about 0.930 gram per cubic centimeter (g/cc) to about 0.970 g/cc, a ratio of high load melt index:melt index of from about 10 to about 150 and an Environmental Stress Crack Resistance (ESCR) of from about 25 hours to about 300 hours when measured in accordance with ASTM D1693 or ASTM D2561. A chromium-catalyzed polymer composition comprising (i) a lower molecular weight homopolymer and (ii) a higher molecular weight copolymer, wherein the bimodal polymer composition has an Environmental Stress Crack Resistance (ESCR) of from about 25 hours to about 300 hours when measured in accordance with ASTM D1693 or ASTM D2561.

A bimodal polymer composition comprising a lower molecular weight homopolymer and a higher molecular weight copolymer wherein the bimodal polymer composition has a density of from about 0.930 gram per cubic centimeter (g/cc) to about 0.970 g/cc, a ratio of high load melt index:melt index of from about 10 to about 150 and an Environmental Stress Crack Resistance (ESCR) of from about 25 hours to about 300 hours when measured in accordance with ASTM D1693 or ASTM D2561. A chromium-catalyzed polymer composition comprising (i) a lower molecular weight homopolymer and (ii) a higher molecular weight copolymer, wherein the bimodal polymer composition has an Environmental Stress Crack Resistance (ESCR) of from about 25 hours to about 300 hours when measured in accordance with ASTM D1693 or ASTM D2561.

The present invention relates to a process for producing a propylene polymer, such as a propylene homopolymer, a propylene-ethylene random copolymer or a heterophasic propylene copolymer using a specific class of metallocene complexes in combination with a cocatalyst system comprising a boron containing cocatalyst and an aluminoxane cocatalyst, preferably in a multistage polymerization process including a gas phase polymerization step.

The present invention relates to a process for producing a propylene polymer, such as a propylene homopolymer, a propylene-ethylene random copolymer or a heterophasic propylene copolymer using a specific class of metallocene complexes in combination with a cocatalyst system comprising a boron containing cocatalyst and an aluminoxane cocatalyst, preferably in a multistage polymerization process including a gas phase polymerization step.

The present invention relates to a process for producing a propylene polymer, such as a propylene homopolymer, a propylene-ethylene random copolymer or a heterophasic propylene copolymer using a specific class of metallocene complexes in combination with a cocatalyst system comprising a boron containing cocatalyst and an aluminoxane cocatalyst, preferably in a multistage polymerization process including a gas phase polymerization step.

A method capable of stably performing continuous production of a propylene polymer with high productivity while reducing generation of agglomerates is described. In the method, a monomer(s) containing propylene is/are (co)polymerized in a presence of an olefin polymerization catalyst with a polymerization system containing two or more gas phase polymerization reactors or a polymerization system containing a liquid phase polymerization reactor(s) and a gas phase polymerization reactor(s) such that that the total number of liquid phase polymerization reactor(s) and gas phase polymerization reactor(s) is three or more. In at least one gas phase polymerization reactor, an average retention time τ.sub.G [hour] in the gas phase polymerization, an average particle diameter D.sub.pi [μm] of fed powder, and a total amount C.sub.o [wt %] of an ethylene-derived structural unit and C4-C12 α-olefin-derived structural units in a polymer in discharged powder are in a predetermined relationship.

A method capable of stably performing continuous production of a propylene polymer with high productivity while reducing generation of agglomerates is described. In the method, a monomer(s) containing propylene is/are (co)polymerized in a presence of an olefin polymerization catalyst with a polymerization system containing two or more gas phase polymerization reactors or a polymerization system containing a liquid phase polymerization reactor(s) and a gas phase polymerization reactor(s) such that that the total number of liquid phase polymerization reactor(s) and gas phase polymerization reactor(s) is three or more. In at least one gas phase polymerization reactor, an average retention time τ.sub.G [hour] in the gas phase polymerization, an average particle diameter D.sub.pi [μm] of fed powder, and a total amount C.sub.o [wt %] of an ethylene-derived structural unit and C4-C12 α-olefin-derived structural units in a polymer in discharged powder are in a predetermined relationship.

In some embodiments, a polyethylene composition includes has 80 wt % to 99.9 wt % ethylene content and 20 wt % to 0.1 wt % a C3 to C40 α-olefin comonomer content, based on ethylene content plus comonomer content. The composition has a Mw/Mn of 15 to 45, a density of 0.93 g/cm.sup.3 to 0.97 g/cm.sup.3, a complex viscosity (at 628 rad/s, 190° C.) of 600 Pa*s or less, a zero shear viscosity by Cross model of 150,000 Pa*s to 350,000 Pa*s. It may also have a V index of less than 7. In some embodiments, an article includes the polyethylene composition. In some embodiments, the article is a pipe.

In some embodiments, a polyethylene composition includes has 80 wt % to 99.9 wt % ethylene content and 20 wt % to 0.1 wt % a C3 to C40 α-olefin comonomer content, based on ethylene content plus comonomer content. The composition has a Mw/Mn of 15 to 45, a density of 0.93 g/cm.sup.3 to 0.97 g/cm.sup.3, a complex viscosity (at 628 rad/s, 190° C.) of 600 Pa*s or less, a zero shear viscosity by Cross model of 150,000 Pa*s to 350,000 Pa*s. It may also have a V index of less than 7. In some embodiments, an article includes the polyethylene composition. In some embodiments, the article is a pipe.

In some embodiments, a polyethylene composition includes has 80 wt % to 99.9 wt % ethylene content and 20 wt % to 0.1 wt % a C3 to C40 α-olefin comonomer content, based on ethylene content plus comonomer content. The composition has a Mw/Mn of 15 to 45, a density of 0.93 g/cm.sup.3 to 0.97 g/cm.sup.3, a complex viscosity (at 628 rad/s, 190° C.) of 600 Pa*s or less, a zero shear viscosity by Cross model of 150,000 Pa*s to 350,000 Pa*s. It may also have a V index of less than 7. In some embodiments, an article includes the polyethylene composition. In some embodiments, the article is a pipe.