BLOW MOLDING POLYMERS WITH IMPROVED CYCLE TIME, PROCESSABILITY AND SURFACE QUALITY.

Abstract

Ethylene-based polymers have a density of 0.952 to 0.965 g / cm³, a high load melt index (HLMI) of 5 to 25 g / 10 min, a weight average molecular weight of 275,000 to 450,000 g / mol, a number average molecular weight of 15,000 to 40,000 g / mol, an HLMI viscosity of 1400 to 4000 Pa·s, and a tangent delta at 0.1 s⁻¹ of 0.65 to 0.98 degrees. These polymers have the processability of chromium-based resins, but with improved resistance to stress cracking, and can be used in blow molding applications for large parts.

Description

BLOW MOLDING POLYMERS WITH IMPROVED CYCLE TIME, PROCESSABILITY AND SURFACE QUALITY BACKGROUND OF THE INVENTION Polyolefins, such as high-density polyethylene (HDPE) homopolymer and copolymer, and linear low-density polyethylene (LLDPE) copolymer, can be produced using various combinations of catalyst systems and polymerization processes. Chromium-based catalyst systems, for example, can produce olefin polymers with good extrusion processability and polymer melt strength, typically due to their broad molecular weight distribution (MWD). In some end-use applications, it may be beneficial to have processability, cycle time, and melt strength similar to those of an olefin polymer produced from a chromium-based catalyst system, as well as improvements in one or more of hardness, impact strength, and environmental stress cracking resistance (ESCR), preferably at equivalent or higher polymer densities. Accordingly, the present invention relates generally to these purposes. BRIEF DESCRIPTION OF THE INVENTION This brief description is provided for the purpose of introducing, in a simplified manner, a selection of concepts that are described in greater detail later in the detailed description. This brief description is not intended to identify the necessary or essential characteristics of the claimed object. Nor is it intended to limit the scope of the claimed object. The present invention relates generally to ethylene polymers (e.g., ethylene / α-olefin copolymers) characterized by a density in the range of about 0.952 to about 0.965 g / cm³, a high load melt index (HLMI) in the range of about 5 to about 25 g / 10 min, a weight average molecular weight (Mw) in the range of about 275,000 to about 450,000 g / mol, a number average molecular weight (Mn) in the range of about 15,000 to about 40,000 g / mol, a viscosity at HLMI (δ at HLMI or δ at HLMI) in the range of about 1400 to about 4000 Pa-s, and a tan δ (tangent delta) at 0.1 s'1 in the range of about 0.65 to about 0.98 degrees. Also disclosed and covered herein are ethylene polymers having a density in the range of about 0.952 to about 0.965 g / cm3, an HLMI in the range of about 5 to about 25 g / 10 min, an Mw in the range of about 275,000 to about 450,000 g / mol, an Mn in the range of about 15,000 to about 28,000 g / mol, and an η at HLMI in the range of about 1400 to about 4000 Pa-s. The ethylene polymers described herein can be used to produce various manufactured articles, such as blow-molded products. Another aspect of this invention relates to a dual catalyst system, and in this aspect, the dual catalyst system may comprise catalyst component I comprising an unbridged metallocene compound, catalyst component II comprising a bridged metallocene compound, an activator, and optionally, a cocatalyst. In yet another aspect, an olefin polymerization process is provided, and in this aspect, the process may comprise contacting any catalyst composition disclosed herein with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce an olefin polymer. For example, the olefin monomer may be ethylene, and the olefin comonomer may be 1-butene, 1-hexene, 1-octene, or a mixture thereof. Both the brief description above and the detailed description below provide examples and are for explanatory purposes only. Therefore, the brief description above and the detailed description below should not be considered restrictive. Furthermore, features or variations may be provided in addition to those stated herein. For example, certain aspects and embodiments may refer to various combinations and subcombinations of the features described in the detailed description. BRIEF DESCRIPTION OF THE FIGURES Figure 1 presents a graph of the molecular weight distributions of the polymers in Examples 1-4. Figure 2 presents a graph of the molecular weight distributions of the polymers in Examples 5-8. Figure 3 presents a graph of the molecular weight distributions of the polymers from Examples 1, 5, and 9. DEFINITIONS The following definitions are provided to clarify the terms used herein. Unless otherwise stated, the following definitions apply to this disclosure. If a term is used in this disclosure but not specifically defined herein, the definition in the IUPAC Compendium of Chemical Terminology, 2nd ed. (1997), may be applied, provided that such definition does not contradict any other disclosure or definition applied herein, or render any claim in which such definition is applied undefined or unpermitted. To the extent any definition or usage provided by any document incorporated herein by reference contradicts the definition or usage provided herein, the definition or usage provided herein shall govern. This disclosure describes the characteristics of the object in such a way that, in particular aspects, it is possible to visualize a combination of different characteristics. For each and every aspect and / or characteristic disclosed herein, all combinations that do not adversely affect the designs, compositions, and / or methods described herein are considered, with or without an explicit description of the particular combination. Additionally, unless explicitly stated otherwise, it is possible to combine any aspect and / or characteristic disclosed herein to describe inventive features consistent with this disclosure. Although compositions and methods are described herein in terms of comprising various components or steps, the compositions and methods may also essentially consist of, or consist of, the various components or steps, unless otherwise stated. For example, a catalyst composition consistent with the aspects of the present invention may comprise; alternatively, may essentially consist of; or alternatively, may consist of: catalyst component I, catalyst component II, an activator, and a cocatalyst. The terms "a" and "the," etc., are intended to include plural alternatives, e.g., "at least one," unless otherwise specified. For example, the disclosure of an activator carrier or a metallocene compound is intended to cover one activator carrier or metallocene compound, respectively, or mixtures or combinations of more than one of these, unless otherwise specified. In general, groups of elements are indicated by using the numbering scheme shown in the version of the periodic table of the elements published in Chemical and Engineering News, 63(5), 27, 1985. In some cases, a group of elements may be indicated by a common name assigned to the group; for example, alkali metals for the elements in Group 1, alkaline earth metals for the elements in Group 2, transition metals for the elements in Groups 3-12, and halogens or halides for the elements in Group 17. For any particular compound disclosed herein, it is also intended that the general structure or name presented encompass all structural isomers, conformational isomers, and stereoisomers that may arise from a particular set of substituents, unless otherwise stated. Therefore, a general reference to a compound includes all structural isomers unless explicitly stated otherwise; for example, a general reference to pentane includes n-pentane, IVIA / a / ZUZZ / UUUOOU 2-methylbutane and 2,2-dimethylpropane, while a general reference to a butyl group includes an n-butyl group, a sec-butyl group, an iso-butyl group, and a tert-butyl group. Furthermore, a reference to a general structure or name encompasses all enantiomers, diastereomers, and other optical isomers in enantiomeric or racemic forms, as well as mixtures of stereoisomers, to the extent permitted or required by the context. For any particular formula or name presented, any general formula or name presented also encompasses all conformational isomers, regioisomers, and stereoisomers that can be derived from a particular set of substituents. The term "substituted," when used to describe a group—for example, when referring to a substituted analogue of a particular group—is intended to describe any portion other than hydrogen that formally replaces a hydrogen atom in that group and is intended to be non-limiting. A group or groups may also be referred to herein as "unsubstituted" or by equivalent expressions, such as "unsubstituted," which refer to the original group in which a portion other than hydrogen does not replace a hydrogen atom within that group. Unless otherwise specified, "substituted" is intended to be non-limiting and to include inorganic or organic substituents, as understood by a person of average skill. The term hydrocarbon, whenever used in this specification and in the claims, refers to a compound containing only carbon and hydrogen. Other identifiers may be used to indicate the presence of particular groups in the hydrocarbon (for example, a halogenated hydrocarbon indicates the presence of one or more halogen atoms replacing an equivalent number of hydrogen atoms in the hydrocarbon). The term hydrocarbyl group is used herein in accordance with the definition specified by IUPAC: a monovalent group formed by the removal of a hydrogen atom from a hydrocarbon (i.e., a group containing only carbon and hydrogen). Non-limiting examples of hydrocarbyl groups include alkyl, alkenyl, aryl, and aralkyl groups, among others. In this document, the term polymer is used generally to include homopolymers, copolymers, terpolymers of olefins, and the like, as well as alloys and mixtures thereof. The term polymer also includes impact, block, graft, random, and alternating copolymers. A copolymer is derived from an olefin monomer and an olefin comonomer, while a terpolymer is derived from an olefin monomer and two olefin comonomers. Accordingly, polymer encompasses copolymers and terpolymers derived from any olefin monomers and comonomers disclosed herein. Similarly, the scope of the term polymerization includes homopolymerization, copolymerization, and terpolymerization. Therefore, an ethylene polymer includes ethylene homopolymers, ethylene copolymers (e.g., ethylene / aolefin copolymers), ethylene terpolymers, and the like, as well as mixtures thereof.Therefore, an ethylene polymer encompasses polymers that are generally known in the art as LLDPE (linear low-density polyethylene) and HDPE (high-density polyethylene). As an example, an olefin copolymer, such as an ethylene copolymer, can be derived from ethylene and a comonomer, such as 1-butene, 1-hexene, or 1-octene. If the monomer and comonomer were ethylene and 1-hexene, respectively, the resulting polymer could be categorized as an ethylene / 1-hexene copolymer. The term polymer also includes all possible geometric configurations, unless otherwise stated, and such configurations may include isotactic, syndiotactic, and random symmetries. Likewise, unless otherwise stated, the term polymer is also intended to include polymers of all molecular weights, including the lowest molecular weight polymers. The term cocatalyst is generally used herein to refer to compounds such as aluminoxane compounds, organoboron or organoborate compounds, ionizing ionic compounds, organoaluminum compounds, organozinc compounds, organomagnesium compounds, organolithium compounds, and the like, which may constitute a component of a catalytic composition when used, for example, in addition to an activator support. The term cocatalyst is used without regard to the actual function of the compound or any chemical mechanism by which the compound may operate. The terms chemically treated solid oxide, treated solid oxide compound, and the like are used herein to denote a solid inorganic oxide of relatively high porosity, which may exhibit Lewis acid or Brønsted acid behavior, that has been treated with an electron-withdrawing component, usually an anion, and calcined. Typically, the electron-withdrawing component is an electron-withdrawing anion source compound. Therefore, the chemically treated solid oxide may comprise a calcined contact product of at least one solid oxide with at least one electron-withdrawing anion source compound. Typically, the chemically treated solid oxide comprises at least one acidic solid oxide compound. The activator carrier of the present invention may be a chemically treated solid oxide.The terms support and activator support do not imply that these components are inert, and they should not be interpreted as inert components of the catalyst composition. The term activator, as used herein, generally refers to a substance that can convert a metallocene component into a catalyst capable of polymerizing olefins, or convert a contact product of a metallocene component and a component providing an activatable ligand (e.g., an alkyl or hydride) to the metallocene, where the metallocene compound does not already contain such a ligand, into a catalyst capable of polymerizing olefins. This term is used without regard to the actual activation mechanism. Indicative activators include activator supports, aluminoxanes, organoboron or organoborate compounds, ionizing ionic compounds, and the like.Aluminoxanes, organoboron or organoborate compounds, and ionizing ionic compounds are generally referred to as activators if they are used in a catalyst composition where there is no activator support. If the catalyst composition contains an activator support, then the aluminoxane, organoboron or organoborate materials and the ionizing ionic materials are generally referred to as cocatalysts. The term metallocene, as used herein, describes compounds comprising at least one η3αε-cycloalkadienyl portion, wherein the η3αε-cycloalkadienyl portions include cyclopentadienyl ligands, indenyl ligands, fluorenyl ligands, and the like, including partially saturated or substituted derivatives or analogues of any of these. Possible substituents on these ligands may include hydrogen; therefore, this invention comprises ligands such as tetrahydroindenyl, tetrahydrofluorenyl, octahydrofluorenyl, partially saturated indenyl, partially saturated fluorenyl, substituted partially saturated indenyl, substituted partially saturated fluorenyl, and the like. In some contexts, the metallocene may be referred to simply as the catalyst, in the same way that the term cocatalyst may be used herein to refer, for example, to an organoaluminum compound. The terms catalytic composition, catalyst mixture, catalyst system, and the like do not depend on the actual product or composition obtained as a result of the contact or reaction of the initial components of the disclosed or claimed catalyst composition / mixture / system, the nature of the active catalytic site, or the fate of the cocatalyst, catalyst component I, catalyst component II, or the activator (e.g., activator support) after combining these components. Therefore, the expressions catalytic composition, catalyst mixture, catalyst system, and the like encompass the starting components of the composition, as well as any products that may be obtained as a result of contacting these starting components, and this includes both heterogeneous and homogeneous catalyst systems or compositions.The terms catalyst composition, catalyst mixture, catalyst system and similar terms may be used interchangeably throughout this disclosure. Unless otherwise stated, the term "contact product" is used herein to describe compositions in which the components are brought into contact in any order, in any manner, and for any period of time. For example, components may be brought into contact by mixing. Furthermore, contact of any component may occur in the presence or absence of any other component of the compositions described herein. Additional materials or components may be combined by any suitable method. In addition, the term "contact product" includes mixtures, solutions, suspensions, reaction products, and the like, or combinations thereof. Although "contact product" may include reaction products, the respective components are not required to react with each other.Similarly, the expression "to put in contact" is used herein to refer to materials that can be mixed, suspended, dissolved, reacted, treated, or otherwise combined. Although any method, device, and material similar or equivalent to those described herein may be used to implement or evaluate the invention, typical methods, devices, and materials are described herein. All publications and patents mentioned herein are incorporated herein by reference for the purpose of describing and disseminating, for example, the concepts and methodologies described in the publications, which could be used in connection with the invention described herein. Several types of ranges are disclosed in the present invention. When disclosing or claiming a range of any kind, the intention is to disclose or claim individually every possible number that such range could reasonably comprise, including the extremes of the range, as well as any subranges and combinations of subranges within it. For example, when disclosing or claiming a chemical portion with a certain number of carbon atoms, the intention is to disclose or claim individually every possible number that such range could comprise, consistent with the disclosure herein.For example, the disclosure that a portion is a Ci to C1e hydrocarbyl group, or, in other terms, a hydrocarbyl group having 1 to 18 carbon atoms, as used herein, refers to a portion that may have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18 carbon atoms, as well as any range between these two numbers (for example, a Ci to C1s hydrocarbyl group), and also includes any combination of ranges between these two numbers (for example, a C2 to C4 and C12 to C16 hydrocarbyl group). Similarly, another representative example for the Mw / Mn ratio of an ethylene polymer consistent with aspects of this invention is given below. By disclosing that the Mw / Mn ratio may be in the range of about 10 to about 20, it is intended to indicate that the Mw / Mn ratio can be any The Mw / Mn ratio in the range, for example, can be equal to approximately 10, approximately 11, approximately 12, approximately 13, approximately 14, approximately 15, approximately 16, approximately 17, approximately 18, approximately 19, or approximately 20. Furthermore, the Mw / Mn ratio can be within any range from approximately 10 to approximately 20 (for example, from approximately 10 to approximately 18), and this also includes any combination of ranges between approximately 10 and approximately 20 (for example, the Mw / Mn ratio can be in a range from approximately 10 to approximately 14 or from approximately 16 to approximately 19). In all cases, when approximately a particular value is disclosed, then that value itself is disclosed.Therefore, the disclosure that the Mw / Mn ratio can be from approximately 10 to approximately 20 also discloses an Mw / Mn ratio of 10 to 20 (e.g., 10 to 18), and this also includes any combination of ranges between 10 and 20 (e.g., the Mw / Mn ratio may be in the range of 10 to 14 or 16 to 19). Likewise, all other ranges disclosed herein should be interpreted similarly to these examples. The expression "around" means that quantities, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding, measurement errors, and the like, and other factors known to persons of average skill. In general, a quantity, size, formulation, parameter, or other quantity or characteristic is "around" or "approximate," whether or not expressly stated. The expression "around" also encompasses quantities that differ due to different equilibrium conditions for a composition resulting from a particular starting mixture. Whether or not modified by the expression "around," the claims include equivalents of the quantities.The expression "around" may mean within 10% of the reported numerical value, preferably within 5% of the reported numerical value. DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to dual metallocene catalyst systems, methods for using the catalyst systems to polymerize olefins, polymer resins produced using such catalyst systems, and articles produced using these polymer resins. In particular, the present invention relates to ethylene-based polymers that have excellent ESCR properties and strength, but with improved processability and reduced cycle times in blow molding applications. Articles produced from these ethylene-based polymers have interior and exterior surfaces that are substantially free of defects. Shear stress, for example, as reflected in η to HLMI, cannot be too high, or extrusion processability (high back pressure and melt temperature) and cycle time will be negatively affected. Furthermore, and without wishing to limit ourselves to the following theory, it is believed that the combined polymer properties of HLMI, Mw, Mn, η to HLMI, and / or tan δ can result in the desired matrix swelling and excellent surface aesthetics of blow-molded parts. ETHYLENE POLYMERS In general, the polymers disclosed herein are ethylene-based polymers, or ethylene polymers, encompassing ethylene homopolymers as well as copolymers, terpolymers, etc., of ethylene and at least one olefin comonomer. Comonomers that can be copolymerized with ethylene can often have from 3 to 20 carbon atoms in their molecular chain. For example, typical comonomers may include, but are not limited to, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and the like, or combinations thereof. In one aspect, the olefin comonomer may comprise a C3-C18 olefin; alternatively, the olefin comonomer may comprise a C3-C10 olefin. Alternatively, the olefin comonomer may comprise a C4-C10 olefin; Alternatively, the olefin comonomer may comprise a C3-C10 α-olefin; alternatively, the olefin comonomer may comprise a C4-C10 α-olefin; alternatively, the olefin comonomer may comprise 1-butene, 1-hexene, 1-octene, or any combination thereof; or, alternatively, the comonomer may comprise 1-hexene. Typically, the amount of comonomer, as a function of the total weight of monomer (ethylene) and comonomer, may range from about 0.01 to about 20% by weight, from about 0.1 to about 10% by weight, from about 0.5 to about 15% by weight, from about 0.5 to about 8% by weight, or from about 1 to about 15% by weight. In one aspect, the ethylene polymer of this invention may comprise an ethylene / α-olefin copolymer, while in another aspect, the ethylene polymer may comprise an ethylene homopolymer, and in yet another aspect, the ethylene polymer of this invention may comprise both an ethylene / α-olefin copolymer and an ethylene homopolymer. For example, the ethylene polymer may comprise an ethylene / 1-butene copolymer, an ethylene / 1-hexene copolymer, an ethylene / 1-octene copolymer, an ethylene homopolymer, or any combination thereof; alternatively, an ethylene / 1-butene copolymer, an ethylene / 1-hexene copolymer, an ethylene / 1-octene copolymer, or any combination thereof; or alternatively, an ethylene / 1-hexene copolymer. An illustrative and non-limiting example of an ethylene polymer (e.g., comprising an ethylene copolymer) consistent with the present invention may have a density in the range of about 0.952 to about 0.965 g / cm³, a high-load melt index (HLMI) in the range of about 5 to about 25 g / 10 min, a weight-average molecular weight (Mw) in the range of about 275,000 to about 450,000 g / mol, a number-average molecular weight (Mn) in the range of about 15,000 to about 40,000 g / mol, a viscosity at HLMI (η at HLMI) in the range of about 1400 to about 4000 Pa-s, and a tan δ (tangent delta) at 0.1 s-1 in the range of about 0.65 to about 0.98 degrees. Another illustrative and non-limiting example of an ethylene polymer consistent with the present invention may have a density in the range of about 0.952 to about 0.965 g / cm3, an HLMI in the range of about 5 to about 25 g / 10 min, an Mw in the range of about 275,000 to about 450,000 g / mol, an Mn in the range of about 15,000 to about 28,000 g / mol, and an η to HLMI in the range of about 1400 to about 4000 Pa-s. These illustrative and non-limiting examples of ethylene polymers consistent with the present invention may also have any of the polymer properties listed below and in any combination, unless otherwise stated. The densities of the ethylene-based polymers disclosed herein are often greater than or equal to about 0.95 g / cm3, for example, greater than or equal to about 0.952 g / cm3 or greater than or equal to about 0.954 g / cm3. However, in particular aspects, the density may be in a range of about 0.952 to about 0.962 g / cm3, about 0.952 to about 0.96 g / cm3, about 0.954 to about 0.965 g / cm3, about 0.954 to about 0.962 g / cm3 or about 0.954 to about 0.96 g / cm3. The ethylene polymers described herein can often have a melting index (MI) less than or equal to approximately 1 g / 10 min, less than or equal to approximately 0.7 g / 10 min, or less than or equal to approximately 0.6 g / 10 min. In additional aspects, the ethylene polymers described herein can have a melting index (MI) less than or equal to approximately 0.4 g / 10 min, less than or equal to approximately 0.3 g / 10 min, less than or equal to approximately 0.2 g / 10 min, or less than or equal to approximately 0.1 g / 10 min. Although not limited to this, the ethylene polymer may have a high load melt index (HLMI) in the range of about 5 to about 25 g / 10 min; alternatively, about 5 to about 20 g / 10 min; alternatively, about 5 to about 18 g / 10 min; alternatively, about 6 to about 18 g / 10 min; alternatively, about 6 to about 16 g / 10 min; or alternatively, about 7 to about 15 g / 10 min. In one respect, the ethylene polymers described herein may have an Mw / Mn ratio, or polydispersity index, in the range of about 7 to about 20, about 7 to about 18, about 8 to about 20, about 8 to about 18, about 10 to about 20, about 10 to about 18, or about 11 to about 17. Additionally or alternatively, the ethylene polymer may have an Mz / Mw ratio in the range of about 4 to about 9, about 4.5 to about 8, about 4.5 to about 7.5, or about 5 to about 7. In one respect, the ethylene polymers described herein may have a weight average molecular weight (Mw) in the range of about 275,000 to about 425,000, about 275,000 to about 400,000, about 300,000 to about 450,000, about 300,000 to about 425,000, about 300,000 to about 400,000, about 325,000 to about 450,000, about 325,000 to about 425,000, or about 325,000 to about 400,000 g / mol. Additionally or alternatively, ethylene polymers can have a number-average molecular weight (Mn) in the range of about 15,000 to about 40,000, about 15,000 to about 35,000, about 15,000 to about 28,000, about 17,000 to about 40,000, about 17,000 to about 35,000, or about 17,000 to about 27,000 g / mol.Additionally or alternatively, the ethylene polymer may have an average molecular weight z (Mz) in a range of about 1,500,000 to about 3,000,000, from about 1,750,000 to about 3,000,000, from about 1,500,000 to about 2,750,000, from about 1,750,000 to about 2,750,000, or from about 1,850,000 to about 2,750,000 g / mol. Additionally or alternatively, the ethylene copolymer may have a maximum molecular weight (Mp) in a range of about 45,000 to about 85,000, about 45,000 to about 65,000, about 50,000 to about 80,000, or about 50,000 to about 62,000 g / mol. Ethylene polymers consistent with certain aspects of the invention can often have a bimodal molecular weight distribution (as determined by gel permeation chromatography (GPC) or other related analytical techniques). Often, in a bimodal molecular weight distribution, there is a valley between the peaks, and the peaks can be separated or deconvolved. Typically, a bimodal molecular weight distribution can be characterized by having an identifiable high molecular weight component (or distribution) and an identifiable low molecular weight component (or distribution). Illustrative unimodal and bimodal MWD curves are shown in U.S. Patent No. 8,383,754, incorporated herein by reference in its entirety. MA / a / ¿U¿¿ / UUUUOOU Although not limited to this, the ethylene polymers described herein may have a zero shear viscosity at 190°C greater than or equal to about 5 x 10⁵, greater than or equal to about 7.5 x 10⁵, greater than or equal to about 1 x 10⁶, or in a range of about 1 x 10⁶ to about 1 x 10⁷ Pa-s. Additionally or alternatively, these ethylene polymers may have a CY-a parameter of about 0.1 to about 0.45, about 0.15 to about 0.4, about 0.18 to about 0.36, or about 0.2 to about 0.35, and so forth.Additionally or alternatively, these ethylene polymers can be characterized by a viscosity at HLMI (eta at HLMI or η at HLMI) at 190°C in a range of about 1400 to about 4000 Pa-s and, more often, in a range of about 1500 to about 4000, about 1600 to about 4000, about 1400 to about 3900, about 1500 to about 3900 or about 1600 to about 3900 Pa-s. Additionally or alternatively, these ethylene polymers may have a viscosity at 100 s⁻¹ (η at 100 or η at 100) at 190°C in the range of approximately 1500 to approximately 3000, approximately 1600 to approximately 2800, approximately 1700 to approximately 2700, approximately 1650 to approximately 2650, or approximately 1750 to approximately 2500 Pa·s. Additionally or alternatively, these ethylene polymers may have a ratio of η at 0.1 / η at 100 (the viscosity at 0.1 / η at 100).1 s-1 divided by the viscosity at 100 s-1) in a range of about 50 to about 150, from about 60 to about 130, from about 85 to about 130 or from about 90 to about 120. Additionally or alternatively, these ethylene polymers may have a tan δ (tan do tangent delta) at 0.1 s-1 and 190°C in a range of about 0.65 to about 0.98 degrees and, more often, from about 0.7 to about 0.98 degrees, from about 0.7 to about 0.95 degrees, from about 0.8 to about 0.98 degrees or from about 0.82 to about 0.97 degrees. The rheological parameters are determined from viscosity data measured at 190°C and by using the empirical Carreau-Yasuda (CY) model as described herein. Generally, the ethylene polymers in aspects of the present invention are essentially linear or have very low levels of long-chain branching, typically with less than about 0.01 long-chain branches (LCBs) per 1000 total carbon atoms, using the Janzen-Colby model, and often similar in LCB content to the polymers shown, for example, in U.S. Patents Nos. 7,517,939, 8,114,946, and 8,383,754, which are incorporated herein by reference in their entirety. In some aspects, the amount of LCBs per 1000 total carbon atoms may be less than about 0.008, less than about 0.007, less than about 0.005, or less than about 0.003 LCBs per 1000 total carbon atoms. Ethylene copolymers, for example, produced using the polymerization processes and catalyst systems described herein, may, in some respects, exhibit an inverse comonomer distribution; generally, the higher molecular weight components of the polymer have greater comonomer incorporation than the lower molecular weight components. Typically, comonomer incorporation increases with increasing molecular weight. In one respect, the number of short-chain branches (SCBs) per 1000 total carbon atoms of the polymer may be greater at Mw than at Mn. In another respect, the number of SCBs per 1000 total carbon atoms of the polymer may be greater at Mz than at Mw. In yet another respect, the number of SCBs per 1000 total carbon atoms of the polymer may be greater at Mz than at Mn. Consistent with aspects of this disclosure, ethylene polymers can have an ambient stress cracking resistance (ESCR) of at least 250 hours. Furthermore, in some aspects, the ethylene polymers described herein can have an ESCR of at least 500 hours, at least 750 hours, at least 1,000 hours, at least 1,500 hours, at least 1,750 hours, or at least 2,000 hours, and often can range as high as 2,500 to 4,000 hours. The ESCR test is generally stopped after a certain number of hours is reached, and given the long duration of the test, the upper limit of ESCR (in hours) is generally not determined. The ESCR tests and test results disclosed herein are in accordance with ASTM D1693, Condition B, 10% igepal, which is a much more stringent test than ESCR tests performed with a 100% igepal solution. Although not limited to this, the ethylene polymers described herein may have an IVc (intrinsic viscosity determined by GPC) that is generally within a range of about 2.9 to about 3.7, about 3 to about 3.6, or about 3.1 to about 3.5 dL / g. Additionally or alternatively, these ethylene polymers may have a Mn / IVc ratio (Mn in kg / mol and IVc in dL / g) generally in a range of about 5.5 to about 12, about 6 to about 10, about 5.5 to about 8.2, or about 6 to about 8. Aspects of this invention also relate to the performance of the ethylene polymer (e.g., an ethylene / 1-hexene copolymer) in representative blow molding equipment, as described below. The ethylene polymers described herein may have cycle times of approximately 150 to approximately 300, approximately 150 to approximately 275, approximately 160 to approximately 280, or approximately 160 to approximately 260 seconds; unexpectedly, these polymers may have shorter cycle times than comparable chromium-based resins. Additionally or alternatively, the ethylene polymers described herein may have a part by weight in a range of about 1800 to about 2500, about 1800 to about 2200, about 1800 to about 2100, about 1850 to about 2100, or about 1850 to about 2050 grams.Additionally or alternatively, the ethylene polymers described herein may have a flat (top) portion in the range of about 23.6 cm (9.3 inches) to about 26.7 cm (10.5 inches), about 24.13 cm (9.5 inches) to about 26.7 cm (10.5 inches), or about 24.4 cm (9.6 inches) to about 26.2 cm (10.3 inches). In one respect, the ethylene polymer described herein can be a reactor product (e.g., a product from a single reactor), distinct from a post-reactor blend of two polymers, for example, with different molecular weight characteristics. As someone of average skill would readily recognize, physical blends of two different polymer resins are possible, but this requires additional processing and complexity not necessary for a reactor product. Furthermore, ethylene polymers can be produced using dual metallocene catalyst systems containing zirconium and / or hafnium, which are discussed further below. Chromium-based Ziegler-Natta catalyst systems are not required. Therefore, the ethylene polymer can contain an unmeasurable amount of chromium or titanium (catalyst residue), i.e., less than 0.1 ppm by weight.In some respects, the ethylene polymer may independently contain less than 0.08 ppm, less than 0.05 ppm, or less than 0.03 ppm of chromium and titanium. ARTICLES AND PRODUCTS The manufactured articles can be formed from, and / or comprise, the polymers defined (e.g., ethylene polymers) of this invention and are therefore included herein. For example, articles that may comprise the polymers of this invention may include, but are not limited to, an agricultural film, an automotive part, a bottle, a chemical container, a drum, a fiber or fabric, a food packaging film or container, a food service article, a fuel tank, a geomembrane, a household container, a lining, a molded product, a medical device or material, an outdoor storage product (e.g., outdoor shed wall panels), outdoor play equipment (e.g., kayaks, basketball hoops), a pipe, a sheet or adhesive tape, a toy, a traffic barrier, and the like.Various processes can be employed to form these articles. Non-limiting examples of these processes include injection molding, blow molding, rotational molding, film extrusion, sheet extrusion, profile extrusion, thermoforming, and the like. In addition, additives and modifiers are frequently added to these polymers to provide beneficial polymer processing or end-use product attributes. Such processes and materials are described in Modern Plastics Encyclopedia, mid-November 1995 issue, Volume 72, No. 12, and Film Extrusion Manual - Process, Materials, Properties, TAPPI Press, 1992; both disclosures are incorporated herein by reference in their entirety.In some aspects of this invention, a manufactured article may comprise any of the olefin polymers (or ethylene polymers) described herein, and the manufactured article may be or may comprise a blow-molded product. Beneficially, articles (e.g., blow-molded articles) formed from or comprising the disclosed ethylene polymers have excellent surface quality or surface aesthetics. This can be quantified as described in the following examples. Generally, the articles (e.g., blow-molded articles) contemplated herein may have fewer than 10 bulges or serious surface defects, while in some aspects, fewer than 5 or fewer than 2 bulges or serious surface defects, and in particular aspects, only 1 bulge or serious surface defect, or zero bulges or serious surface defects. Also contemplated herein is a method for forming or preparing a manufactured article comprising any polymer disclosed herein. For example, a method may comprise (i) contacting a catalyst composition with an olefin monomer (e.g., ethylene) and an optional olefin comonomer under polymerization conditions in a polymerization reactor system to produce an olefin polymer (e.g., an ethylene polymer), wherein the catalyst composition may comprise catalyst component I, catalyst component II, an activator (e.g., an activator support comprising a solid oxide treated with an electron-withdrawing anion), and an optional cocatalyst (e.g., an organoaluminum compound); and (ii) forming a manufactured article comprising the olefin polymer (or ethylene polymer).The forming stage may include mixing, melt processing, extrusion, molding (e.g., blow molding), or thermoforming, and similar processes, including combinations thereof. Any suitable additives may be combined with the polymer during the melt processing stage (extrusion stage), such as antioxidants, acid scavengers, antiblocking agents, anti-slip agents, colorants, fillers, processing aids, UV inhibitors, and similar agents, as well as combinations thereof. CATALYTIC SYSTEMS AND POLYMERIZATION PROCESSES According to aspects of the present invention, the olefin polymer (e.g., the ethylene polymer) can be produced using a dual catalyst system. In these aspects, catalyst component I can comprise any suitable unbridged metallocene compound disclosed herein, and catalyst component II can comprise any suitable bridged metallocene compound disclosed herein. The catalyst system can also comprise any suitable activator or any activator disclosed herein and, optionally, any suitable cocatalyst or any cocatalyst disclosed herein. First, reference is made to catalyst component I, which may comprise an unbridged zirconium- or hafnium-based metallocene compound containing two cyclopentadienyl groups, two indenyl groups, or one cyclopentadienyl group and one indenyl group. Alternatively, catalyst component I may comprise an unbridged zirconium- or hafnium-based metallocene compound containing two cyclopentadienyl groups. Alternatively, catalyst component I may comprise an unbridged zirconium- or hafnium-based metallocene compound containing two indenyl groups. Finally, catalyst component I may comprise an unbridged zirconium- or hafnium-based metallocene compound containing one cyclopentadienyl group and one indenyl group. The catalyst component I may comprise, in particular aspects of this invention, a bridgeless metallocene compound having Formula (I): Within Formula (I), M, CpA, CpBy, and each X are independent elements of the unbridged metallocene compound. Consequently, it is possible to describe the unbridged metallocene compound having Formula (I) by using any combination of M, CpA, CpBy, and X disclosed herein. Unless otherwise specified, the above Formula (I), any other structural formulas disclosed herein, and any metallocene complex, compound, or species disclosed herein are not intended to show the stereochemical or isomeric position of the different portions (e.g., these formulas are not intended to exhibit cis or trans isomers, or R or S diastereomers), although such formulas and / or structures contemplate and encompass such compounds. According to aspects of this invention, the metal in Formula (I), M, can be either Zr or Hf. Therefore, M can be Zr in one aspect and Hf in another. Each X in the Formula (I) may independently be a monoanionic ligand. In some respects, suitable monoanionic ligands may include, but are not limited to, H (hydride), BH4, a halide, a C1 to C36 hydrocarbyl group, a C1 to C36 hydrocarboxyl group, a C1 to C36 hydrocarbylaminyl group, a C1 to C36 hydrocarbylaminyl group, a C1 to C36 hydrocarbylaminylsilyl group, —OBR12, or —OSO2R1, wherein R1 is a C1 to C36 hydrocarbyl group. It is contemplated that each X may be the same or a different monoanionic ligand. Suitable hydrocarbyl groups, hydrocarboxyl groups, hydrocarbylaminyl groups, hydrocarbylaminylsilyl groups, and hydrocarbylaminylsilyl groups are disclosed, for example, in U.S. Patent No. 9,758,600, incorporated herein by reference in its entirety. Generally, the hydrocarbyl group that can be an X in Formula (I) can be a C1 to C36 hydrocarbyl group, including a C1 to Ose alkyl group, a C2 to C36 alkenyl group, a C4 to C36 cycloalkyl group, a Ce to C36 aryl group, or a C7 to Csearalkyl group.For example, each X can be, independently, a C1 to C1e alkyl group, a C2 to C1e cisalkenyl group, a C4 to Cw cycloalkyl group, a Ce to C1e cis aryl group, or a C7 to C1e aralkyl group; alternatively, each X can be independently a C1 to C12 alkyl group, a C2 to C12 alkenyl group, a C4 to C12 cycloalkyl group, a Ce to C12 aryl group, or a C7 to C12 aralkyl group; alternatively, each X can be independently a C1 to C10 alkyl group, a C2 to C10 alkenyl group, a C4 to C10 cycloalkyl group, a Ce to C10 aryl group, or a C7 to C10 aralkyl group; or alternatively, each X can independently be a C1 to Cs alkyl group, a C2 to C5 alkenyl group, a C5 to Cs cycloalkyl group, a Ce to Cs aryl group, or a C7 to Cs aralkyl group. In other particular aspects of this invention, each X can independently be a halide or a C1 to C1 hydrocarbyl group. For example, each X can be Cl. In Formula (I), CpA and CpB can independently be a substituted or unsubstituted cyclopentadienyl or indenyl group. In one respect, CpA and CpB can independently be an unsubstituted cyclopentadienyl or indenyl group. Alternatively, CpA and CpB can independently be a substituted indenyl or cyclopentadienyl group, for example, one with up to 5 substituents. If present, each substituent on CpA and CpB can independently be H, a halide, a C1 to C36 hydrocarbyl group, a halogenated C1 to C36 hydrocarbyl group, a C1 to C36 hydrocarboxyl group, or a C1 to C36 hydrocarbysilyl group. It is important to note that each substituent on CpA and / or CpB can be the same or a different substituent group. Furthermore, each substituent can be in any position on the respective cyclopentadienyl or indenyl ring structure according to the rules of chemical valency. In one respect, the number of substituents on CpA and / or CpB, or the positions of each substituent on CpA and / or CpB, are independent of each other. For example, two or more substituents on CpA can be different, or alternatively, each substituent on CpA can be the same. Additionally or alternatively, two or more substituents on CpB may be different, or alternatively, all substituents on CpB may be the same.In another respect, one or more of the substituents on CpA may be different from one or more of the substituents on CpB, or alternatively, all the substituents on CpA and / or CpB may be the same. In these and other respects, each substituent may be in any position on the respective cyclopentadienyl or indenyl ring structure. If substituted, CpA and / or CpB may independently have one substituent, or two substituents, or three substituents, or four substituents, and so on. Suitable hydrocarbyl groups, halogenated hydrocarbyl groups, hydrocarboxyl groups, and hydrocarbylsilyl groups that can be substituents are disclosed, for example, in U.S. Patent No. 9,758,600, which is incorporated herein by reference in its entirety. For example, a halogenated hydrocarbyl group indicates the presence of one or more halogen atoms replacing an equivalent number of hydrogen atoms in the hydrocarbyl group. The halogenated hydrocarbyl group can often be a halogenated alkyl group, a halogenated alkenyl group, a halogenated cycloalkyl group, a halogenated aryl group, or a halogenated aralkyl group. Representative, but not limited to, halogenated hydrocarbyl groups include pentafluorophenyl, trifluoromethyl (CF3), and the like. Illustrative and non-limiting examples of unbridged metallocene compounds having Formula (I) and / or being suitable for use as catalyst component I may include the following compounds (Ph = phenyl): IVIA / a / ZUZZ / UUUOOU and similar things, as well as combinations of these. Catalytic component I is not limited solely to the unbridged metallocene compounds disclosed above. Other suitable unbridged metallocene compounds are disclosed in U.S. Patent Nos. 7,199,073, 7,226,886, 7,312,283, and 7,619,047, which are incorporated herein by reference in their entirety. With reference to catalyst component II below, this may be a bridging metallocene compound. In one aspect, for example, catalyst component II may comprise a bridging zirconium- or hafnium-based metallocene compound. In another aspect, catalyst component II may comprise a bridging zirconium- or hafnium-based metallocene compound with an alkenyl substituent. In yet another aspect, catalyst component II may comprise a bridging zirconium- or hafnium-based metallocene compound with an alkenyl substituent and a fluorenyl group. In a further aspect, catalyst component II may comprise a bridging zirconium- or hafnium-based metallocene compound with a cyclopentadienyl group and a fluorenyl group, and with an alkenyl substituent on the bridging group and / or on the cyclopentadienyl group.In addition, catalyst component II may comprise a bridging metallocene compound having an aryl group substituent on the bridging group. In particular aspects of this invention, the catalyst component II may comprise a bridging metallocene compound having Formula (II): (II). Within Formula (II), M, Cp, Rx, RY, E, and each X are independent elements of the bridging metallocene compound. Consequently, the bridging metallocene compound having Formula (II) can be described using any combination of M, Cp, Rx, RY, E, and X are disclosed herein. The selections for M and each X in Formula (II) are the same as those described above herein for Formula (I). In Formula (II), Cp may be a substituted cyclopentadienyl, indenyl, or fluorenyl group. In one aspect, Cp may be a substituted cyclopentadienyl group, while in another aspect, Cp may be a substituted indenyl group. In some respects, Cp may not contain any additional substituents, for example, other than the bridging group E, as further discussed later herein. In other respects, Cp may be further substituted with one, two, three, or four substituents, and so on. If present, each substituent on Cp may independently be H, a halide, a C1 to C36 hydrocarbyl group, a C1 to C36 halogenated hydrocarbyl group, a C1 to C36 hydrocarboxyl group, or a C1 to C36 hydrocarbysilyl group. It is noteworthy that each substituent on Cp may be the same substituent group or a different one. Furthermore, each substituent may be in any position on the respective cyclopentadienyl, indenyl, or fluorenyl ring structure according to the rules of chemical valency.In general, any substituent on Cp can be, independently, H or any halide, C1 to C36 hydrocarbyl group, C1 to Cse halogenated hydrocarbyl group, C1 to C36 hydrocarboxi group or Ci to C36 hydrocarbysilyl group described herein (e.g., with respect to the substituents on CpA and CpB in Formula (I)). Similarly, Rxy RY in Formula (II) can be, independently, H or any halide, C1 to C36 hydrocarbyl group, halogenated C1 to C36 hydrocarbyl group, C1 to C36 hydrocarboxyl group, or C1 to C36 hydrocarbysilyl group disclosed herein (e.g., with respect to the substituents on CpA and CpB in Formula (I)). In one respect, for example, Rxy RY can be independently H or a C1 to C12 hydrocarbyl group. In another respect, Rxy RY can be independently a C1 to C10 hydrocarbyl group.En aun otro aspectos, Rxy RYpueden ser independientemente H, Cl, CF3, un grupo metilo, un grupo etilo, un grupo propilo, un grupo butilo (por ejemplo, t-Bu), un grupo pentilo, un grupo hexilo, un grupo heptilo, un grupo octilo, un grupo nonilo, un grupo decilo, un grupo etenilo, un grupo propenilo, un grupo butenilo, un grupo pentenilo, un grupo hexenilo, un grupo heptenilo, un grupo octenilo, un grupo nonenilo, un grupo decenilo, un grupo fenilo, un grupo tolilo, un grupo bencilo, un grupo naftilo, un grupo trimetilsililo, un grupo triisoproilsililo, un grupo trifenilsililo o un grupo alildimetilsililo, y semelhantes.En otro aspecto adicionar, Rxy RYpueden ser independientemente un grupo metilo, un grupo etilo, un grupo propilo, un grupo butilo, un grupo pentilo, un grupo hexilo, un grupo heptilo, un grupo octilo, un grupo nonilo, un grupo decilo, un grupo etenilo, un grupo propenilo, un grupo butenilo, un grupo pentenilo, un grupo hexenilo, un grupo heptenilo, un grupo octenilo, un grupo nonenilo, un grupo decenilo, un grupo fenilo, un grupo tolilo o un grupo bencilo. The bridging group E in Formula (II) can be a bridging group of the formula EARARB, wherein EA can be C, Si, or Ge, and RA and RB can independently be H or a C1 to C2 hydrocarbyl group. In some aspects of this invention, RA and RB can independently be a C1 to C12 hydrocarbyl group; alternatively, RA and RB can independently be a C1 to C2 hydrocarbyl group; alternatively, RA and RB can independently be a phenyl group, a C1 to C2 alkyl group, or a C3 to C2 alkenyl group.alternatively, RA and RB may independently be a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an ethenyl group, a propenyl group, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, a phenyl group, a cyclohexylphenyl group, a naphthyl group, a tolyl group or a benzyl group; or, alternatively, RA and RB may independently be a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a propenyl group, a butenyl group, a pentenyl group, a hexenyl group, a phenyl group or a benzyl group. In these and other aspects, RAy RB can be the same or different. Illustrative and non-limiting examples of bridging metallocene compounds having Formula (II) and / or suitable for use as catalyst component II may include the following compounds (Me = methyl, Ph = phenyl; t-Bu = tert-butyl): IVIA / a / ZUZZ / UUUOOU and similar things, as well as combinations of these. Catalytic component I is not limited solely to the bridging metallocene compounds described above. Other suitable bridging metallocene compounds are disclosed in U.S. Patent Nos. 7,026,494, 7,041,617, 7,226,886, 7,312,283, 7,517,939, and 7,619,047, which are incorporated herein by reference in their entirety. According to one aspect of this invention, the weight ratio of catalyst component I to catalyst component II in the catalyst composition can be in the range of about 10:1 to about 1:10, about 8:1 to about 1:8, about 5:1 to about 1:5, about 4:1 to about 1:4, about 3:1 to about 1:3, about 2:1 to about 1:2, about 1.5:1 to about 1:1.5, about 1.25:1 to about 1:1.25 or about 1.1:1 to about 1:1.1. In another respect, catalyst component I is the main component of the catalyst composition, and in such respects, the weight ratio of catalyst component I to catalyst component II in the catalyst composition may be in a range of about 10:1 to about 1:1, from about 5:1 to about 1.1:1, from about 2:1 to about 1.1:1, or from about 1.8:1 to about 1.1:1. Additionally, the dual catalyst system contains an activator. For example, the catalyst system may contain an activator support, an aluminoxane compound, an organoboron or organoborate compound, an ionizing ionic compound, or any combination thereof. The catalyst system may contain one or more activators. In one aspect, the catalyst system may comprise an aluminoxane compound, an organoboron or organoborate compound, an ionizing ionic compound, and the like, or a combination thereof. Examples of such activators are disclosed, for instance, in U.S. Patent Nos. 3,242,099, 4,794,096, 4,808,561, 5,576,259, 5,807,938, 5,919,983, and 8,114,946, which are incorporated herein by reference in their entirety. In another aspect, the catalyst system may comprise an aluminoxane compound. In yet another aspect, the catalyst system may comprise an organoboron or organoborate compound. In a further aspect, the catalyst system may comprise an ionizing ionic compound. In other respects, the catalyst system may comprise an activator support, for example, an activator support comprising a solid oxide treated with an electron-withdrawing anion. Examples of such materials are disclosed, for example, in U.S. Patent Nos. 7,294,599, 7,601,665, 7,884,163, 8,309,485, 8,623,973, and 9,023,959, which are incorporated herein by reference in their entirety. For example, the activator support may comprise fluorinated alumina, chlorinated alumina, brominated alumina, sulfated alumina, fluorinated silica-alumina, chlorinated silica-alumina, brominated silica-alumina, sulfated silica-alumina, fluorinated silica-zirconia, chlorinated silica-zirconia, brominated silica-zirconia, sulfated silica-zirconia, fluorinated silica-titania, alumina coated with fluorinated silica, alumina coated with fluorinated silica, alumina coated with sulfated silica, or alumina coated with phosphated silica and the like, as well as any combination thereof.In some respects, the activator support may comprise a fluorinated solid oxide and / or a sulfated solid oxide. It is possible to employ various processes to form activator supports useful in the present invention. Methods for contacting the solid oxide with the electron-withdrawing component, suitable electron-withdrawing components and amounts of addition, impregnation with metals or metal ions (for example, zinc, nickel, vanadium, titanium, silver, copper, gallium, tin, tungsten, molybdenum, zirconium, and the like, or combinations thereof), and various calcination procedures and conditions are described in, for example, U.S. Patents Nos. 6,107,230, 6,165,929, 6,294,494, 6,300,271, 6,316,553, 6,355,594, 6,376,415, 6,388,017, 6,391,816, 6,395,666, 6,524,987, 6,548,441, 6,548,442, 6,576,583, 6,613,712, 6,632,894, 6,667,274, 6,750,302, 7,294,599, 7,601,665, 7,884,163 and 8,309,485, which are incorporated herein by reference in their entirety.People in the mid-level trade are familiar with other processes and procedures suitable for preparing activator supports (e.g., fluorinated solid oxides, sulfated solid oxides, etc.). The present invention may employ catalytic compositions comprising catalyst component I, catalyst component II, an activator (one or more of these), and optionally, a cocatalyst. When present, the cocatalyst may include, among others, metal or organometal alkyl cocatalysts, wherein the metal comprises boron, aluminum, zinc, and the like. Optionally, the catalyst systems provided herein may comprise a single cocatalyst or a combination of cocatalysts. For example, alkylboron, alkylaluminum, and alkylzinc compounds may often be used as cocatalysts in such catalyst systems. Representative boron compounds may include, among others, tri-n-butylborane, tripropylborane, triethylborane, and the like, and this includes combinations of two or more of these materials.Although not limited to this, representative aluminum compounds (e.g., organoaluminum compounds) may include trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diisobutylaluminum hydride, diethylaluminum ethoxide, diethylaluminum chloride and the like, as well as any combination thereof. Example zinc compounds (e.g., organozinc compounds) that can be used as cocatalysts may include, but are not limited to, dimethylzinc, diethylzinc, dipropylzinc, dibutylzinc, dinepentylzinc, di(trimethylsilyl)zinc, di(triethylsilyl)zinc, di(trisopropylsilyl)zinc, di(triphenylsilyl)zinc, di(allyldmethylsilyl)zinc, di(trimethylsilylmethyl)zinc and similar compounds or combinations thereof.Accordingly, in one aspect of this invention, the dual catalyst composition may comprise catalyst component I, catalyst component II, an activator support, and an organoaluminum compound (and / or an organozinc compound). In another aspect of the present invention, a catalyst composition is provided comprising catalyst component I, catalyst component II, an activator support, and an organoaluminum compound, wherein this catalyst composition is substantially free of aluminoxanes, organoboron or organoborate compounds, ionizing ionic compounds, and / or other similar materials; alternatively, it is substantially free of aluminoxanes; alternatively, it is substantially free of organoboron or organoborate compounds; or, alternatively, it is substantially free of ionizing ionic compounds. In these aspects, the catalyst composition has the catalytic activity mentioned herein in the absence of these additional materials.For example, a catalyst composition in the present invention may essentially consist of catalyst component I, catalyst component II, an activator support, and an organoaluminum compound, wherein there are no other materials in the catalyst composition that would increase / decrease the activity of the catalyst composition by more than about 10% from the catalyst activity of the catalyst composition in the absence of such materials. The catalytic compositions of the present invention generally have a catalytic activity greater than approximately 250 grams of ethylene polymer (homopolymer and / or copolymer, as the context requires) per gram of activator support per hour (abbreviated g / g / h). Alternatively, the catalytic activity may be greater than approximately 350, 450, or 550 g / g / h. Furthermore, the catalytic activity may be greater than approximately 700 g / g / h, 1000 g / g / h, 2000 g / g / h, and often as high as 5000–10,000 g / g / h. Illustrative and non-limiting ranges for catalytic activity include from about 500 to about 5000, from about 750 to about 4000, or from about 1000 to about 3500 g / g / h and the like.These activities are measured under suspension polymerization conditions, with a triisobutylaluminum cocatalyst, using isobutane as a diluent, at a temperature of. MA / a / ¿U¿¿ / UUUÜOU polymerization at around 95°C and a reactor pressure of around 40.67 bar (590 psig). In addition, in some aspects, the activator support may comprise sulfated alumina, fluorinated silica-alumina, or alumina coated with fluorinated silica, although it is not limited to these. This invention further comprises methods for preparing these catalytic compositions, such as, for example, contacting the respective catalyst components in any order or sequence. In one aspect, for example, the catalytic composition can be produced by a process comprising contacting, in any order, catalyst component I, catalyst component II, and the activator, while in another aspect, the catalytic composition can be produced by a process comprising contacting, in any order, catalyst component I, catalyst component II, the activator, and the cocatalyst. Olefin polymers (e.g., ethylene polymers) can be produced from the disclosed catalyst systems using any suitable olefin polymerization process with various types of polymerization reactors, polymerization reactor systems, and polymerization reaction conditions. One such olefin polymerization process for polymerizing olefins in the presence of a catalyst composition of the present invention may comprise contacting the catalyst composition with an olefin monomer and, optionally, an olefin comonomer (one or more) in a polymerization reactor system under polymerization conditions to produce an olefin polymer, wherein the catalyst composition may comprise, as disclosed herein, catalyst component I, catalyst component II, an activator, and an optional cocatalyst.This invention also covers any olefin polymer (e.g., ethylene polymers) produced by any of the polymerization processes disclosed herein. As used herein, a polymerization reactor includes any polymerization reactor capable of polymerizing (including oligomerizing) monomers and comonomers (one or more of a comonomer) of olefins to produce homopolymers, copolymers, terpolymers, and the like. The various types of polymerization reactors include those that may be referred to as a batch reactor, slurry reactor, gas-phase reactor, solution reactor, high-pressure reactor, tubular reactor, autoclave reactor, and the like, or combinations thereof; or alternatively, the polymerization reactor system may comprise a slurry reactor, a gas-phase reactor, a solution reactor, or a combination thereof. Persons of intermediate skill are familiar with the polymerization conditions for the various types of reactors. Gas-phase reactors may comprise fluidized bed reactors or horizontal staged reactors.Suspension reactors may comprise vertical or horizontal loops. High-pressure reactors may comprise autoclave or tubular reactors. Reactor types may include batch or continuous processes. Continuous processes may utilize intermittent or continuous product discharge. Polymerization reactor systems and processes may also include partial or complete direct recycling of the unreacted monomer, unreacted comonomer, and / or diluent. A polymerization reactor system may comprise a single reactor or multiple reactors (two reactors, more than two reactors, etc.) of the same or different types. For example, the polymerization reactor system may comprise a slurry reactor, a gas-phase reactor, a solution reactor, or a combination of two or more of these reactors. Polymer production in multiple reactors may include several stages in at least two separate polymerization reactors interconnected by a transfer device that allows the polymers produced to be transferred from the first reactor to the second. The desired polymerization conditions in one reactor may differ from the operating conditions in the other reactors. Alternatively, polymerization in multiple reactors may include the manual transfer of the polymer from one reactor to subsequent reactors for continuous polymerization.Multiple reactor systems may include any combination, including but not limited to loop reactors, gas-phase reactors, a combination of gas-phase and loop reactors, high-pressure reactors, or a combination of high-pressure loop and / or gas-phase reactors. Multiple reactors may operate in series, in parallel, or both. Accordingly, the present invention covers polymerization reactor systems comprising a single reactor, two reactors, and more than two reactors. The polymerization reactor system may comprise a suspension reactor, a gas-phase reactor, a solution reactor, or, in certain aspects of this invention, combinations of multiple reactors thereof. According to one aspect, the polymerization reactor system may comprise at least one loop slurry reactor consisting of vertical or horizontal loops. Monomers, diluents, catalysts, and comonomers may be continuously fed into a loop reactor where polymerization occurs. Typically, continuous processes may involve the continuous introduction of the monomer / comonomer, a catalyst, and a diluent into a polymerization reactor and the continuous removal from this reactor of a slurry comprising polymer particles and the diluent. The reactor effluent may be distilled to remove the solid polymer from the liquids comprising the diluent, monomer, and / or comonomer.Various technologies can be used for this separation stage, including but not limited to distillation, which may include any combination of heat addition and pressure reduction, separation by cyclonic action in a cyclone or hydrocyclone, or separation by centrifugation. A typical suspension polymerization process (also known as the particle-forming process) is disclosed, for example, in U.S. Patent Nos. 3,248,179, 4,501,885, 5,565,175, 5,575,979, 6,239,235, 6,262,191, 6,833,415 and 8,822,608, each of which is incorporated herein by reference in its entirety. Suitable diluents used in suspension polymerization include, but are not limited to, the monomer being polymerized and hydrocarbons that are liquid under the reaction conditions. Examples of suitable diluents include, but are not limited to, hydrocarbons such as propane, cyclohexane, isobutane, n-butane, n-pentane, isopentane, neopentane, and n-hexane. Some loop polymerization reactions can occur under apparent conditions where no diluent is used. According to yet another aspect, the polymerization reactor system may comprise at least one gas-phase reactor (e.g., a fluidized bed reactor). Such reactor systems may employ a continuous recycle stream containing one or more monomers continuously cycled through a fluidized bed in the presence of the catalyst under polymerization conditions. A recycle stream may be extracted from the fluidized bed and recycled back into the reactor. Simultaneously, the polymer product may be removed from the reactor, and a new monomer or raw monomer may be added to replace the polymerized monomer.Such gas-phase reactors may comprise a process for the multi-stage gas-phase polymerization of olefins, wherein the olefins are polymerized in the gas phase in at least two independent gas-phase polymerization zones while a catalyst-containing polymer formed in a first polymerization zone is fed to a second polymerization zone. Representative gas-phase reactors are disclosed in U.S. Patent Nos. 5,352,749, 4,588,790, 5,436,304, 7,531,606, and 7,598,327, each of which is incorporated herein by reference in its entirety. According to another aspect, the polymerization reactor system may comprise a high-pressure polymerization reactor, for example, a tubular reactor or an autoclave reactor. Tubular reactors may have several zones in which raw monomer, initiators, or catalysts are added. The monomer may be contained in an inert gas stream and introduced into one zone of the reactor. Initiators, catalysts, and / or catalyst components may be contained in a gas stream and introduced into another zone of the reactor. The gas streams may be intermixed for polymerization. Heat and pressure may be applied appropriately to obtain optimal polymerization reaction conditions. According to yet another aspect, the polymerization reactor system may comprise a solution polymerization reactor where the monomer / comonomer comes into contact with the catalyst composition by means of suitable stirring or other means. A carrier comprising an inert organic diluent or excess monomer may be employed. If desired, the monomer / comonomer may be contacted with the catalytic reaction product in the vapor phase in the presence or absence of liquid material. The polymerization zone may be maintained at temperatures and pressures that will result in the formation of a polymer solution in a reaction medium. Stirring may be employed to obtain better temperature control and to maintain uniform polymerization mixtures throughout the polymerization zone. Suitable means are used to dissipate the exothermic heat of polymerization. The polymerization reactor system may further comprise any combination of at least one feed system for raw materials, at least one feed system for the catalyst or catalyst components, and / or at least one polymer recovery system. Suitable reactor systems may further comprise systems for raw material purification, catalyst storage and preparation, extrusion, reactor cooling, polymer recovery, fractionation, recycling, storage, discharge, laboratory analysis, and process control. Depending on the desired properties of the olefin polymer, hydrogen may be added to the polymerization reactor as required (e.g., continuously, in pulses, etc.). The polymerization conditions that can be controlled for efficiency and to provide desired polymer properties include temperature, pressure, and the concentrations of various reactants. The polymerization temperature can affect catalyst productivity, polymer molecular weight, and molecular weight distribution. Various polymerization conditions can be kept substantially constant, for example, for the production of a particular grade of olefin polymer (or ethylene polymer). According to the Gibbs free energy equation, any temperature below the depolymerization temperature can be a suitable polymerization temperature. Typically, this includes around 60°C to around 280°C, for example, or around 60°C to around 120°C, depending on the type of polymerization reactor.In some reactor systems, the polymerization temperature can generally be within a range of around 70°C to around 100°C, or from around 75°C to around 95°C. ινΐΛ / a / zuzz / uuuoou The appropriate pressures will also vary depending on the reactor type and the type of polymerization. The pressure for liquid-phase polymerizations in a loop reactor is generally less than 1000 psig (6.9 MPa). The pressure for gas-phase polymerization is generally around 200 to 500 psig (1.4 MPa to 3.4 MPa). High-pressure polymerization in tubular reactors or autoclaves is typically run at around 20,000 to 75,000 psig (138 to 517 MPa). Polymerization reactors can also be operated in a supercritical region, which generally occurs at higher temperatures and pressures. Operating above the critical point on a pressure / temperature diagram (supercritical phase) can offer advantages to the polymerization reaction process. The olefin monomers that can be used with the catalytic compositions and polymerization processes of this invention generally include olefin compounds having 2 to 30 carbon atoms per molecule and at least one olefin double bond, such as ethylene or propylene. In one aspect, the olefin monomer may comprise a C2-C20 olefin; alternatively, a C2-C20 alpha-olefin; alternatively, a C2-C10 olefin; alternatively, a C2-C10 alpha-olefin; alternatively, the olefin monomer may comprise ethylene; or, alternatively, the olefin monomer may comprise propylene (e.g., to produce a polypropylene homopolymer or a propylene-based copolymer). When a copolymer (or alternatively, a terpolymer) is desired, the olefin monomer and the olefin comonomer may independently comprise, for example, a C2C20 alpha-olefin. In some aspects, the olefin monomer may comprise ethylene or propylene, which copolymerizes with at least one comonomer (for example, a C2-C20 alpha-olefin, a C3-C20 alpha-olefin, etc.). According to one aspect of this invention, the olefin monomer used in the polymerization process may comprise ethylene.In this respect, the comonomer may comprise a C3-C10 alpha-olefin; alternatively, the comonomer may comprise 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, styrene or any combination thereof; alternatively, the comonomer may comprise 1-butene, 1-hexene, 1-octene or any combination thereof; alternatively, the comonomer may comprise 1-butene; alternatively, the comonomer may comprise 1-hexene; or, alternatively, the comonomer may comprise 1-octene. EXAMPLES The invention is further illustrated by the following examples, which should not be interpreted in any way as limitations imposed on the scope of the present invention. After reading the description herein, a person skilled in the art may propose various additional aspects, embodiments, modifications, and equivalents thereof, without departing from the spirit of the present invention or the scope of the appended claims. The melting index (MI, g / 10 min) was determined according to ASTM D1238 at 190°C using a sample weighing 2,160 grams, and the high-load melting index (HLMI, g / 10 min) was determined according to ASTM D1238 at 190°C using a sample weighing 21,600 grams. Density in grams per cubic centimeter (g / cm³) was determined on a compression-molded sample cooled at 15°C per minute and conditioned for 40 hours at room temperature according to ASTM D1505 and ASTM D4703. The ESCR was determined according to ASTM D1693, condition B, using 10% igepal. Molecular weights and molecular weight distributions were obtained using a PL-GPC 220 system (Polymer Labs, an Agilent company) equipped with an IR4 detector (Polymer Char, Spain) and three Styragel HMW-6E GPC columns (Waters, MA) operating at 145°C. The flow rate of the 1,2,4-trichlorobenzene (TCB) mobile phase containing 0.5 g / L of 2,6-di-tert-butyl-4-methylphenol (BHT) was set at 1 mL / min, and polymer solution concentrations ranged from 1.0 to 1.5 mg / mL, depending on the molecular weight. Sample preparation was performed at 150°C for approximately 4 hours with occasional, gentle stirring before the solutions were transferred to sample vials for injection. An injection volume of approximately 200 pL was used.The integral calibration method was used to derive molecular weights and molecular weight distributions using a Chevron Phillips Chemical Company HDPE resin, MARLEX® BHB5003, as a broad standard. The integral table of the broad standard was predetermined in a separate experiment with SEC-MALS. Mn is the number-average molecular weight, Mw is the weight-average molecular weight, Mz is the z-average molecular weight, Mv is the viscosity-average molecular weight, and Mp is the maximum molecular weight (location, in molecular weight, of the highest point on the molecular weight distribution curve). IVc is the intrinsic viscosity [η], which is calculated from Equation 1: [η] = K Mva, where Mv is the viscosity-average molecular weight, and K are Mark-Houwink constants for the polymer of interest. For polyethylene, K is already 3.95E-04 (dL / g) and 0.726 (unitless), respectively. Mv is calculated based on Equation 2: l / a. Equation 2 where % and are the weight fraction and molecular weight of cut i, respectively. Rheological characterizations of fusion were carried out as follows. Oscillatory shear measurements of small strain (less than 10%) were determined on an Anton Paar MCR rheometer using parallel plate geometry. IVIA / a / ZUZZ / UUUOOU All rheological tests were performed at 190°C. The complex viscosity data |η*| versus frequency (ω) were then fitted to the curve using the modified Carreau-Yasuda (CY) three-parameter empirical model to obtain the zero-shear viscosity - ηθ, the characteristic viscous relaxation time - τη, and the amplitude parameter - a (CY-a parameter). The simplified Carreau-Yasuda (CY) empirical model is as follows. I n * (ú)) I =-------—------where: |η *(ω) | = magnitude of complex shear viscosity; ηθ = zero shear viscosity; τη = viscous relaxation time (Tau(q)); a = amplitude parameter (CY-a parameter); n = sets the final slope of the power law, sanded down by 2 / 11; and ω = angular frequency of oscillatory shear strain. 1. Details of the significance and interpretation of the CY model and derived parameters can be found in: C.A. Hieber and H.H. Chiang, Rheol. Acta, 28, 321 (1989); C.A. Hieber and H.H. Chiang, Polym. Eng. Sci., 32, 931 (1992); and R.B. Bird, R.C. Armstrong, and O. Hasseger, Dynamics of Polymeric Liquids, Volume 1, Fluid Mechanics, 2nd edition, John Wiley & Sons (1987); each of which is incorporated herein by reference in its entirety. Viscosity at HLMI (η at HLMI or η at HLMI) is the viscosity at the HLMI stress for the polymer at its HLMI.The short-chain branching content (SCB) and short-chain branching distribution (SCBD) in the molecular weight distribution can be determined using an IR5-detected GPC system (IR5-GPC), where the GPC system is a PL220 GPC / SEC system (Polymer Labs, an Agilent company) equipped with three Styragel HMW-6E columns (Waters, MA) for polymer separation. A thermoelectrically cooled IR5 MCT detector (IR5) (Polymer Char, Spain) is connected to the GPC columns via a hot-transfer line. Chromatographic data are obtained from two output ports of the IR5 detector.First, the analog signal travels from the analog output port to a digitizer before connecting to computer A to perform molecular weight determinations using Cirrus software (Polymer Labs, now an Agilent company) and the comprehensive calibration method, employing a MARLEX™ BHB5003 broad-spectrum MWD HDPE resin (Chevron Phillips Chemical) as the broad-spectrum molecular weight standard. The digital signals, on the other hand, travel via USB cable directly to computer B, where they are collected by LabVIEW data acquisition software provided by Polymer Char. The chromatographic conditions are set as follows: column oven temperature of 145°C; flow rate of 1 mL / min; injection volume of 0.4 mL; and polymer concentration of approximately 2 mg / mL, based on the sample's molecular weight.The temperatures for both the hot transfer line and the IR5 detector sample cell are set at 150°C, while the temperature of the IR5 detector electronics is set at 60°C. Short-chain branching (SCB) content is determined using an internal method based on the ratio of CH3 (Ichs) to CH2 (Ich2) intensity, along with a calibration curve. The calibration curve is a graph of SCB content (xscb) as a function of the Ich3 / Ich2 intensity ratio. To obtain a calibration curve, a group of polyethylene resins (at least five) with SCB levels ranging from zero to approximately 32 SCB / 1,000 total carbons (SCB standards) were used. All of these SCB standards have known SCB levels and predetermined flat SCBD profiles obtained separately using NMR and solvent gradient fractionation combined with NMR methods (SGF-NMR).Using the SCB calibration curves established in this way, short-chain branching distribution profiles in the molecular weight distribution for fractionated resins are obtained using the IR5GPC system under the exact same chromatographic conditions as for these SCB standards. A relationship between intensity ratio and elution volume is converted into SCB distribution as a function of MWD by using a predetermined SCB calibration curve (i.e., Ich3 / Ich2 intensity ratio versus SCB content) and an MW calibration curve (i.e., molecular weight versus elution time) to convert the Ich3 / Ich2 intensity ratio and elution time into SCB content and molecular weight, respectively. The long chain branching (LCB) per 1000 total carbon atoms of the overall polymer can be calculated using the method of Janzen and Colby (J. Mol. Struct., 485 / 486, 569-584 (1999), incorporated herein by reference in its entirety), from zero shear viscosity values, η0 (determined from the Carreau-Yasuda model, described earlier herein), and measured Mw values ​​obtained using a Dawn EOS multi-angle light scattering detector (Wyatt). The blow molding evaluations in Examples 1–10 were performed on a Sterling blow molding machine with the following specifications. These particular processing conditions and equipment were chosen because the blow molding performance and properties obtained in this manner are generally representative of those obtained from larger, commercial-scale blow molding operations. The extruder screw diameter was 7.62 cm (3”), the L / D ratio was 24:1, the drive motor was a 75 HP DC drive, and the maximum plasticizing capacity was approximately 158.8 kg (350 lb) of polyethylene per hour. The extruder was equipped with a Dynisco pressure gauge, four air-cooled heating zones, and a liquid-cooled smoothbore barrel in the feed zone. The accumulator head (FIFO design) had a maximum firing capacity of 4.53 kg (10 lb) and a maximum and minimum die bushing diameter of 20.32 cm (8 in) and 2.54 cm (1 in) (respectively), where 2.54 cm (1 in) to 8.89 cm (3.5 in) converge and 10.16 cm (4 in) to 20.32 cm (8 in) diverge. The blow molding machine was also equipped with a 100-point MACO programmer. For Examples 1-10, all extruder and die zones were set to 198.88°C (390°F). The mold was a 34.068-liter (9-gallon) bottle (Fremont Plastics Mold, 106.68 cm (42”) circumference), and a 11.43 cm (4.5”) divergent die head was used with a 30-degree tilt angle. A constant ejection speed was used. The mold temperature was 10-15.55°C (50-60°F). The timer settings were a blow delay of 0.5 seconds, a pre-blow of 0 seconds, and a gripper closing delay of 0.25 seconds. The air pressure was approximately 6.20 bar (90 psig). The minimum wall thickness of the parts was in the range of 45-50 mils and the die spacing was 0.49 cm (0.196”). The parts were produced at an extrusion speed of 30 RPM and a blow time of 90 seconds. The weight of the produced product (piece weight) was recorded, and the width of the end cap was measured at the top (flat top) and bottom (flat bottom) of the product. Die swell (parison size compared to die size) and weight swell (change in part weight at constant distance from the die and parison speed) could be determined. The melt strengths of the polymers were compared using a suspension time test with a die gap of 0.089” and an extruder speed of 20 RPM. A parison was extruded and left to suspend; the extruder speed was set to zero while the parison was suspended. The time elapsed from the end of the shot until the parison detached from the end cap was recorded as the suspension time. The fluorinated silica-coated alumina activator supports used in Examples 1-8 were prepared as follows. The boehmite was obtained from WR Grace & Company under the designation Alumina A and with a surface area of ​​300 m2 / g, a pore volume of about 1.3 mL / g and an average particle size of about 100 micrometers. IVIA / a / ZUZZ / UUUOOU The alumina was first calcined in dry air at approximately 600°C for about 6 hours, cooled to room temperature, and then contacted with tetraethyl orthosilicate in isopropanol to correspond to 25 wt% SiO₂. After drying, the silica-coated alumina was calcined at 600°C for 3 hours. Fluorinated silica-coated alumina (7 wt% F) was prepared by impregnating the calcined silica-coated alumina with a solution of ammonium bifluoride in methanol, drying it, and then calcining it for 3 hours at 600°C in dry air. The fluorinated silica-coated alumina was then collected and stored in dry nitrogen and used without exposure to the atmosphere. Pilot plant polymerizations were carried out in a 113.6-liter (30-gallon) slurry loop reactor at a production rate of approximately 14.96 kilograms (33 pounds) of polymer per hour. The polymerization work was performed under continuous particle-form process conditions in a loop reactor (also referred to as a slurry process) by contacting a dual metallocene solution in isobutane, an organoaluminum solution (triisobutylaluminum, TIBA), and an activator support (fluorinated silica-coated alumina) in a 1-L stirred autoclave with continuous outlet to the loop reactor. The TIBA and dual metallocene solutions were fed as separate streams into a T-fitting upstream of the autoclave where they came into contact with each other.The activator support was thoroughly washed with 1 / 2-isobutane at a point downstream of the aforementioned T, upon contact with the organoaluminum / metallocene mixture, as they flowed together into the autoclave. The 1 / 2-isobutane discharge used to transport the activator support to the autoclave was set at a rate that would result in a residence time of approximately 30 minutes in the autoclave. The entire autoclave flow then entered the loop reactor. The ethylene used was polymerization-grade ethylene obtained from AirGas and purified through an alumina-zeolite adsorbent column (activated at 230–290°C in nitrogen). Polymerization-grade 1-hexene (obtained from Chevron Phillips Chemical Company) was purified by distillation and passed through an alumina-zeolite adsorbent column activated at 230–290°C in nitrogen. The loop reactor was liquid-filled, 15.2 cm in diameter, and had a volume of 113.6 liters (30 gallons). Liquid isobutane was used as a diluent. Hydrogen was added at approximately 0.000453–0.00181 kg / h (0.001–0.004 lb / h) to adjust the molecular weight and / or HLMI of the polymer product. The isobutane was polymerization-grade isobutane (obtained from Enterprise) that was further purified by distillation and subsequently passed through an alumina column (activated at 230290°C in nitrogen).The TIBA cocatalyst was obtained as a 10–12 wt% hydrocarbon solution and further diluted to 2 wt% isobutane. The cocatalyst was added at a concentration of approximately 125 ppm, based on the weight of the diluent, to the polymerization reactor. The reactor conditions included a reactor pressure of approximately 40.68 bar (590 psig), an ethylene molar percentage of 11–13% (depending on the isobutane diluent), and a polymerization temperature of 93–100°C. The reactor was operated to have a residence time of approximately 0.8–1.3 h. Metallocene concentrations in the reactor ranged from approximately 1.5 to 2.5 parts per million (ppm) by weight of diluent. The activator support (fluorinated silica-coated alumina) was fed to the reactor at a rate of approximately 0.006–0.013 kg (0.015–0.03 lb) per hour. The polymer was withdrawn from the reactor at a rate of approximately 6,787 kg / h (14,963 lb / h) and passed through a flash chamber and a purge column. Nitrogen was fed into the purge column to ensure that the fluff was free of hydrocarbons. The structures for MET 1 and MET 2, used in Examples 1–8, are shown below: Table I summarizes certain information related to the polymerization experiments in Examples 1-8. Each of Examples 1-8 used a dual catalyst system containing MET 1 and MET 2 in the relative amounts listed in Table I. EXAMPLES 1-10 Example 9 was a broad monomodal copolymer resin, having a nominal HLMI of 12 and a density of 0.949, produced using a chromium-based catalyst system (Chevron-Phillips Chemical Company LP). Example 10 was a broad bimodal copolymer resin, having a nominal HLMI of 5 and a density of 0.955, produced using a metallocene-based catalyst system (Chevron-Phillips Chemical Company LP). Figure 1 illustrates the bimodal molecular weight distributions (amount of polymer compared to the logarithm of molecular weight) of the polymers in Examples 1-4, Figure 2 illustrates the bimodal molecular weight distributions of the polymers in Examples 5-8, Figure 3 illustrates the molecular weight distributions of the polymers in Examples 1, 5, and 9, Table I summarizes the HLMI, density, and ESCR properties of the polymer, and Table II summarizes certain molecular weight characteristics of the polymers in the Examples 1-9. The polymers in Examples 1-8 had densities ranging from 0.956 to 0.96 g / cm3, HLMI values ​​ranging from 9 to 14 g / 10 min, ESCR values ​​greater than 1000 hours, Mw values ​​ranging from 330,000 to 400,000 g / mol, Mn values ​​ranging from 20,000 to 33,000 g / mol, and IVc values ​​ranging from 3 to 3.6 dL / g. In contrast, the unimodal chromium polymer in Example 9 had lower Mw, Mn, and IVc values. Table III summarizes certain rheological characteristics at 190°C for the polymers in Examples 1–9. Surprisingly, many of the metallocene-based polymers (Examples 1–8) had processability approximately equivalent to that of the chromium-based polymer (Example 9). The polymers in Examples 1–8 had η values ​​at HLMI ranging from 1400 to about 4000 Pa·s, and tan δ values ​​at 0.1 s⁻¹ ranging from 0.7 to 0.96 degrees. Table IV summarizes the blow molding performance of Examples 1-4 and 9-10. Using the chromium polymer from Example 9 as a benchmark, it can be seen that the comparative Example 10, although having good melt strength, had an unacceptable high extrusion pressure (psig) and cycle time (s), and a low output rate (lb / h). Furthermore, in addition to excessive die swelling (flat dimensions much larger than 25.4 cm (10 in)), the blow-molded products produced from Example 9 had poor surface aesthetics, with noticeable surface distortions, lines, and streaks. In contrast, the polymers in Examples 1-4 performed similarly to the chromium polymer in Example 9.Examples 1-4 had excellent processability (pressure, output speed), comparable die swelling and suspension times, and unexpectedly, lower cycle times (by 5-10%), resulting in the production of more parts per hour. Examples 5-8 were also evaluated similarly, and cycle time reductions of more than 20% were found. The blow-molded products of Examples 1–10 were also evaluated for surface aesthetics. Panels of the blow-molded parts were evaluated, where panels were defined as sections of the part with a width equal to half the circumference of the mold used in the blow molding and a height of 2.54 cm (1 in.). Minor surface defects were defined as minor discrepancies in surface appearance, such as a streak, where the color and / or texture of the part varies irregularly. Major surface defects or bulges were defined as critical surface defects caused by stretched strands or thin plates of polymer; the presence of such defects can render a blow-molded part unusable.The blow-molded parts in Example 10 had over 200 minor surface defects and more than 10 bulges or major surface defects on the panel, while the blow-molded parts in Examples 1–4 were surprisingly better, with 75,150 minor surface defects and 1–9 bulges or major surface defects on the panel. The blow-molded products in Examples 5–8 were unexpectedly even better, with only 10–75 minor surface defects and no bulges (zero) or major surface defects on the panel. For reference, the blow-molded products in Example 9 also had no bulges or major surface defects on the panel, and generally fewer than 10 surface defects. Table I. Examples 1-8: polymerization and HLMI data, polymer density and ESCR Example MET 2 / MET 1 (ppm) Ib H2 / 453.6 kg (1000 Ib) C2H4 C2H4 (molar %) 1hexene (Ib / lb C2H4) TIBA (PPm) HLMI (g / 10 min) Density (g / cc) ESCR (condition B, 10%, h) 1 0.75 / 1.21 0.053 12.02 0.01 125 9.2 0.9565 >1000 2 0.67 / 1.10 0.053 11.65 0.01 125 11.0 0.9570 >1000 3 0.69 / 1.10 0.053 12.83 0.01 125 11.4 0.9582 >1000 4 0.75 / 1.22 0.053 12.47 0.01 125 10.2 0.9571 >1000 5 0.88 / 1.01 0.088 12.41 0.01 125 9.3 0.9588 >1000 6 0.88 / 1.03 0.088 12.60 0.01 125 11.9 0.9591 >1000 7 0.89 / 1.03 0.088 12.44 0.01 125 10.7 0.9586 >1000 8 0.84 / 1.08 0.088 12.01 0.01 125 13.3 0.9592 >1000 Note: The ESCR (condition B, 10%) for Example 9 was 72 hours. Table II. Examples 1-9: characterization of molecular weight (g / mol) Example 0 Mn / 100 0 Mw / 100 0 Mz / 100 0 Mv / 100 0 Mp / 100 0 Mw / M n Mz / M w IB IVc 1 31.43 377.5 2322 262.3 71.3 12.01 6.15 1.3 5 3.3 9 2 31.54 359.0 2528 244.9 73.1 11.38 7.04 1.2 7 3.2 3 3 32.83 338.4 2286 233.7 74.0 10.31 6.75 1.2 3.1 8 2 4 31.76 346.3 2192 241.7 75.0 10.90 6.33 1.3 1 3.2 0 5 23.57 394.1 2225 273.2 59.1 16.72 5.65 1.5 2 3.5 0 6 22.41 354.9 2109 245.6 57.6 15.84 5.94 1.5 0 3.2 4 7 23.77 358.3 2051 249.5 54.8 15.07 5.72 1.5 3 3.2 7 8 23.42 335.2 2019 232.0 58.3 14.31 6.02 1.4 6 3.1 0 9 20.83 183.5 1064 140.1 76.6 8.81 5.80 1.6 0 2.1 5 Table III. Examples 1-9: rheological characterization at 190°C Example 0 Zero shear (Pa-s) Tau(n) (s) CY-a parameter 0 η a 0.1 (Pa-s) Tan da 0.1 (degrees) na 100 (Pas) Tan da 100 (degrees) Π a HLM I (Pas) 1 2.86E+13 5.81 E+0 8 0.059 2.00E+0 5 0.711 246 1 0.583 3797 2 5.17E+19 1.19E+1 4 0.031 1.34E+0 5 0.762 209 1 0.682 2301 3 9.17E+18 1.47E+1 3 0.031 1.26E+0 5 0.779 203 9 0.694 2152 4 3.40E+17 2.20E+1 2 0.037 1.54E+0 5 0.742 222 2 0.650 2730 5 4.54E+06 9.00E+0 1 0.321 2.71 E+0 5 0.860 231 3 0.366 3971 6 4.34E+06 8.71 E+0 1 0.278 2.05E+0 5 0.914 206 7 0.400 2396 7 2.53E+06 4.73E+0 1 0.343 2.36E+0 5 0.952 219 2 0.368 3140 8 8.95E+06 1.99E+0 2 0.227 1.77E+0 5 0.874 189 4 0.433 1691 9 8.09E+06 2.97E+0 1 0.138 8.40E+0 4 1.210 214 0 0.692 2436 Table IV. Examples 1-4 and 9-10: Comparison of blow molding performance Example 9 10 1 2 3 4 HLMI (g / 10 min) 12.2 5.2 9.2 11.0 11.4 10.2 Density (g / cc) 0.949 0.955 0.957 0.957 0.958 0.957 Piece weight (g) 1805 2132 1884 2004 1959 1983 Flat top (cm / inches) 25.4 cm (10.00 inches) 27.15 cm (10.69 inches) 24.66 cm (9.71 inches) 25.62 cm (10.09 inches) 25.12 cm (9.89 inches) 25.83 cm (10.17 inches) Flat bottom (cm / inches) 25.62 cm (10.09 inches) 26.64 cm (10.49 inches) 23.52 cm (9.26 inches) 24.89 cm (9.80 inches) 24.73 cm (9.74 inches) 24.53 cm (9.66 inch) Cycle time (s) 229 344 213 205 212 213 Pressure (bar / psig) 118.58 bar (1720 psig) 141.34 bar (2050 psig) 143.41 bar (2080 psig) 117.90 bar (1710 psig) 113.07 bar (1640 psig) 126.86 bar (1840 psig) Output at 50 rpm (Ib / h) 78.5 kg (173 Ib) 61.7 kg (136 Ib) 74.4 kg (164 Ib) 78.5 kg (173 Ib) 78.01 kg (172 Ib) 75.7 kg (167 Ib) Time of suspension(s) 30 54 33 27 26 25 The invention has been described above with reference to numerous specific aspects and examples. Many variations will be obvious to persons of average skill in light of the detailed description above. All such obvious variations are encompassed within the entire intended scope of the appended claims. Other aspects of the invention may include, but are not limited to, the following (the aspects are described as comprising, but alternatively may essentially consist of or consist of): Aspect 1. An ethylene polymer having (or being characterized by): a density in the range of around 0.952 to around 0.965 g / cm3; a high load melting index (HLMI) in the range of about 5 to about 25 g / 10 min; an average weight molecular weight (Mw) in the range of around 275,000 to around 450,000 g / mol; an average number molecular weight (Mn) in a range of around 15,000 to around 40,000 g / mol; a viscosity at HLMI (eta at HLMI or η at HLMI) in a range of around 1400 to around 4000 Pa-s; and a tan δ (tan do tangent delta) at 0.1 s-1 in a range of around 0.65 to around 0.98 degrees. Aspect 2. An ethylene polymer having (or being characterized by): a density in the range of about 0.952 to about 0.965 g / cm3; an HLMI in a range of around 5 to around 25 g / 10 min; an Mw in a range of around 275,000 to around 450,000 g / mol; a Mn in a range of around 15,000 to around 28,000 g / mol; and an η at HLMI in a range of around 1400 to around 4000 Pa-s. Aspect 3. The polymer defined in aspect 1 or 2, wherein the ethylene polymer has an environmental stress cracking resistance (ESCR) in any range disclosed herein, for example, at least 250 hours, at least 500 hours, at least 1,000 hours, at least 1,500 hours, at least 2,000 hours, etc. Aspect 4. The polymer defined in any of the above aspects, wherein the ethylene polymer has a melt index (MI) in any range disclosed herein, e.g., from 0 to about 0.6, from 0 to about 0.3, from 0 to about 0.2, from 0 to about 0.1 g / 10 min, etc. Aspect 5. The polymer defined in any of the above aspects, wherein the ethylene polymer has an HLMI in any range disclosed herein, for example, from about 5 to about 20, from about 5 to about 18, from about 6 to about 16, from about 7 to about 15 g / 10 min, etc. Aspect 6. The polymer defined in any of the above aspects, wherein the ethylene polymer has a density in any range disclosed herein, for example, from about 0.952 to about 0.962, from about 0.952 to about 0.96, from about 0.954 to about 0.965, from about 0.954 to about 0.962, from about 0.954 to about 0.96 g / cm3, etc. Aspect 7. The polymer defined in any of the above aspects, wherein the ethylene polymer has less than about 0.008 long chain branches (LCB) per 1000 total carbon atoms, e.g., less than about 0.005 LCB, less than about 0.003 LCB, etc. Aspect 8. The polymer defined in any of the above aspects, wherein the ethylene polymer has an inverse comonomer distribution, e.g., the amount of short chain branches (SCB) per 1000 total carbon atoms of the polymer at Mw is greater than at Mn, the amount of SCB per 1000 total carbon atoms of the polymer at Mz is greater than at Mw, the amount of SCB per 1000 total carbon atoms of the polymer at Mz is greater than at Mn, etc. Aspect 9. The polymer defined in any of the above aspects, wherein the ethylene polymer has an Mp in any range disclosed herein, for example, from about 45,000 to about 85,000, from about 45,000 to about 65,000, from about 50,000 to about 80,000, from about 50,000 to about 62,000 g / mol, etc. Aspect 10. The polymer defined in any of the above aspects, wherein the ethylene polymer has an Mw in any range disclosed herein, for example, from about 275,000 to about 425,000, from about 275,000 to about 400,000, from around 300,000 to around 450,000, from around 300,000 to around 425,000, from around 300,000 to around 400,000, from around 325,000 to around 450,000, from around 325,000 to around 425,000, from around 325,000 to around 400,000 g / mol, etc. Aspect 11. The polymer defined in any of the above aspects, wherein the ethylene polymer has an Mn in any range disclosed herein, for example, from about 15,000 to about 40,000, from about 15,000 to about 35,000, from about 15,000 to about 28,000, from about 17,000 to about 40,000, from about 17,000 to about 35,000, from about 17,000 to about 27,000 g / mol, etc. Aspect 12. The polymer defined in any of the above aspects, wherein the ethylene polymer has an Mz in any range disclosed herein, for example, from about 1,500,000 to about 3,000,000, from about 1,750,000 to about 3,000,000, from about 1,500,000 to about 2,750,000, from about 1,750,000 to about 2,750,000, from about 1,850,000 to about 2,750,000 g / mol, etc. Aspect 13. The polymer defined in any of the above aspects, wherein the ethylene polymer has an Mw / Mn ratio in any range disclosed herein, for example, from about 7 to about 20, from about 7 to about 18, from about 8 to about 20, from about 8 to about 18, from about 10 to about 20, from about 10 to about 18, etc. Aspect 14. The polymer defined in any of the above aspects, wherein the ethylene polymer has an Mz / Mw ratio in any range disclosed herein, for example, from about 4.5 to about 8, from about 4.5 to about 7.5, from about 5 to about 7, etc. Aspect 15. The polymer defined in any of the above aspects, wherein the ethylene polymer has a CY-a parameter in any range disclosed herein, for example, from about 0.1 to about 0.45, from about 0.15 to about 0.4, from about 0.18 to about 0.36, from about 0.2 to about 0.35, etc. Aspect 16. The polymer defined in any of the above aspects, wherein the ethylene polymer has a viscosity at HLMI (eta at HLMI or η at HLMI) in any range disclosed herein, for example, from about 1400 to about 4000, from about 1500 to about 4000, from about 1600 to about 4000, from about 1400 to about 3900, from about 1500 to about 3900, from about 1600 to about 3900 Pa-s, etc. Aspect 17. The polymer defined in any of the above aspects, wherein the ethylene polymer has a viscosity at 100 s-1 (eta at 100 or η at 100) in any range disclosed herein, for example, from about 1500 to about 3000, from about 1600 to about 2800, from about 1700 to about 2700, from about 1650 to about 2650, from about 1750 to about 2500 Pa-s, etc. Aspect 18. The polymer defined in any of the above aspects, wherein the ethylene polymer has zero shear viscosity in any range disclosed herein, for example, greater than or equal to about 5 x 10⁵, greater than or equal to about 7.5 x 10⁵, greater than or equal to about 1 x 10⁶, in a range from about 1 x 10⁶ to about 1 x 10⁷ Pa-s, etc. Aspect 19. The polymer defined in any of the above aspects, wherein the ethylene polymer has a tan δ at 0.1 s-1 in any range disclosed herein, for example, from about 0.65 to about 0.98, from about 0.7 to about 0.97, from about 0.8 to about 0.98, from about 0.82 to about 0.97 degrees, etc. Aspect 20. The polymer defined in any of the above aspects, wherein the ethylene polymer has an IVc in any range disclosed herein, for example, from about 2.9 to about 3.7, from about 3 to about 3.6, from about 3.1 to about 3.5 dL / g, etc. Aspect 21. The polymer defined in any of the above aspects, wherein the ethylene polymer has an Mn / IVc ratio in any range disclosed herein, for example, from about 5.5 to about 12, from about 6 to about 10, from about 5.5 to about 8.2, from about 6 to about 8, etc. Aspect 22. The polymer defined in any of the above aspects, wherein the ethylene polymer has a ratio of η to 0.1 / η to 100 in any range disclosed herein, for example, from about 50 to about 150, from about 60 to about 130, from about 85 to about 130, from about 90 to about 120, etc. Aspect 23. The polymer defined in any of the above aspects, wherein the ethylene polymer has a piece weight in any range disclosed herein, for example, from about 1800 to about 2500, from about 1800 to about 2200, from about 1800 to about 2100, from about 1850 to about 2100, from about 1850 to about 2050 g, etc. Aspect 24. The polymer defined in any of the above aspects, wherein the ethylene polymer has a flat (top) portion in any range disclosed herein, e.g., from about 9.3 to about 10.5, from about 9.5 to about 10.5, from about 9.6 to about 10.3, etc. Aspect 25. The polymer defined in any of the preceding aspects, wherein the ethylene polymer has a cycle time in any range disclosed herein, for example, from about 150 to about 300, from about 150 to about 275, from about 160 to about 280, from about 160 to about 260 seconds, etc. Aspect 26. The polymer defined in any of the preceding aspects, wherein the ethylene polymer has a bimodal molecular weight distribution. Aspect 27. The polymer defined in any of the above aspects, wherein the ethylene polymer is a single reactor product, for example, distinct from a post-reactor mixture of two polymers, for example, with different molecular weight characteristics. Aspect 28. The polymer defined in any of the above aspects, wherein the ethylene polymer comprises an ethylene / α-olefin copolymer. Aspect 29. The polymer defined in any of the above aspects, wherein the ethylene polymer comprises an ethylene / 1-butene copolymer, an ethylene / 1-hexene copolymer and / or an ethylene / 1-octene copolymer. Aspect 30. The polymer defined in any of the above aspects, wherein the ethylene polymer comprises an ethylene / 1-hexene copolymer. Aspect 31. The polymer defined in any of the above aspects, wherein the ethylene polymer contains, independently, less than 0.1 ppm (by weight), less than 0.08 ppm, less than 0.05 ppm, less than 0.03 ppm, etc., of chromium and titanium. Aspect 32. An article comprising the ethylene polymer as defined in any of the above aspects. Aspect 33. An article comprising the ethylene polymer as defined in any of aspects 1-31, wherein the article is an agricultural sheet, automotive part, bottle, chemical container, drum, fiber or fabric, film or food packaging container, catering article, fuel tank, geomembrane, household container, lining, molded product, medical device or material, outdoor storage product, outdoor playground equipment, pipe, sheet or tape, toy, or traffic barrier. Aspect 34. The article defined in aspect 32 or 33, wherein the article has fewer than 10 (or fewer than 5, or fewer than 2) serious surface bulges or defects. Aspect 35. A catalyst composition comprising: catalyst component I comprising any unbridged metallocene compound disclosed herein, catalyst component II comprising any bridged metallocene compound disclosed herein, any activator disclosed herein, and optionally, any cocatalyst disclosed herein. Aspect 36. The composition defined in aspect 35, wherein catalyst component II comprises a zirconium- or hafnium-based metallocene compound in a bridge. Aspect 37. The composition defined in aspect 35, wherein catalyst component II comprises a zirconium- or hafnium-based metallocene compound bridged with an alkenyl substituent. Aspect 38. The composition defined in aspect 35, wherein catalyst component II comprises a bridged zirconium or hafnium-based metallocene compound, with an alkenyl substituent and a fluorenyl group. Aspect 39. The composition defined in aspect 35, wherein catalyst component II comprises a zirconium- or hafnium-based metallocene compound bridged with a cyclopentadienyl group and a fluorenyl group, and with an alkenyl substituent on the bridging group and / or on the cyclopentadienyl group. Aspect 40. The composition defined in aspect 35, wherein catalyst component II comprises a bridging metallocene compound having an aryl group substituent on the bridging group. Aspect 41. The composition defined in any of aspects 35-40, wherein catalyst component I comprises a bridged zirconium- or hafnium-based metallocene compound containing two cyclopentadienyl groups, two indenyl groups, or one cyclopentadienyl group and one indenyl group. Aspect 42. The composition defined in any of aspects 35-40, wherein catalyst component I comprises a bridged zirconium- or hafnium-based metallocene compound containing two cyclopentadienyl groups. Aspect 43. The composition defined in any of aspects 35-40, wherein catalyst component I comprises a bridged zirconium- or hafnium-based metallocene compound containing two indenyl groups. Aspect 44. The composition defined in any of aspects 35-40, wherein catalyst component I comprises a bridged zirconium- or hafnium-based metallocene compound containing a cyclopentadienyl group and an indenyl group. Aspect 45. The composition defined in any of aspects 35-44, wherein the activator comprises an activator support, an aluminoxane compound, an organoboron or organoborate compound, an ionizing ionic compound, or any combination thereof. Aspect 46. The composition defined in any of aspects 35-44, wherein the activator comprises an aluminoxane compound. Aspect 47. The composition defined in any of aspects 35-44, wherein the activator comprises an organoboron or organoborate compound. Aspect 48. The composition defined in any of aspects 35-44, wherein the activator comprises an ionizing ionic compound. Aspect 49. The composition defined in any of aspects 35-44, where the MA / a / ¿U¿¿ / UUUOOU activator comprises an activator support, wherein the activator support comprises any solid oxide treated with any electron-withdrawing anion disclosed herein. Aspect 50. The composition defined in any of aspects 35-44, wherein the activator comprises fluorinated alumina, chlorinated alumina, brominated alumina, sulfated alumina, fluorinated silica-alumina, chlorinated silica-alumina, brominated silica-alumina, sulfated silica-alumina, fluorinated silica-zirconia, chlorinated silica-zirconia, brominated silica-zirconia, sulfated silica-zirconia, fluorinated silica-titania, alumina coated with fluorinated-chlorinated silica, alumina coated with fluorinated silica, alumina coated with sulfated silica, alumina coated with phosphated silica, or any combination thereof. Aspect 51. The composition defined in any of aspects 35-44, wherein the activator comprises a fluorinated solid oxide and / or a sulfated solid oxide. Aspect 52. The composition defined in any of aspects 35-51, wherein the catalytic composition comprises a cocatalyst, e.g., any cocatalyst disclosed herein. Aspect 53. The composition defined in any of aspects 35-52, wherein the cocatalyst comprises any organoaluminum compound disclosed herein. Aspect 54. The composition defined in aspect 53, wherein the organoaluminum compound comprises trimethylaluminum, triethylaluminum, triisobutylaluminum or a combination thereof. Aspect 55. The composition defined in any of aspects 49-54, wherein the catalyst composition comprises catalyst component I, catalyst component II, a solid oxide treated with an electron-withdrawing anion, and an organoaluminum compound. Aspect 56. The composition defined in any of aspects 49-55, wherein the catalyst composition is substantially free of aluminoxane compounds, organoboron or organoborate compounds, ionizing ionic compounds or combinations thereof. Aspect 57. The composition defined in any of aspects 35-56, wherein a weight ratio of catalyst component I to catalyst component II in the catalyst composition is in any range disclosed herein, for example, from about 10:1 to about 1:10, from about 5:1 to about 1:5, from about 2:1 to about 1:2, etc. Aspect 58. The composition defined in any of aspects 35-57, wherein the catalytic composition is produced by a process comprising contacting, in any order, catalyst component I, catalyst component II and the activator or contacting, in any order, catalyst component I, catalyst component II, the activator and the cocatalyst. Aspect 59. The composition defined in any of aspects 35-58, wherein a catalytic activity of the catalyst composition is in any range disclosed herein, for example, from about 150 to about 10,000, from about 500 to about 7,500, from about 1,000 to about 5,000 grams, etc., of ethylene polymer per gram of activator support per hour, under suspension polymerization conditions, with a triisobutylaluminum cocatalyst, using isobutane as a diluent and with a polymerization temperature of 90°C and a reactor pressure of 26.9 bar (390 psig). Aspect 60. An olefin polymerization process, wherein the process comprises contacting the catalyst composition defined in any of aspects 35-59 with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce an olefin polymer. Aspect 61. The process defined in aspect 60, wherein the olefin monomer comprises any olefin monomer disclosed herein, e.g., any C2-C20 olefin. Aspect 62. The process defined in aspect 60 or 61, wherein the olefin monomer and the optional olefin comonomer independently comprise a C2-C2α-olefin. Aspect 63. The process defined in any of aspects 60-62, wherein the olefin monomer comprises ethylene. Aspect 64. The process defined in any of aspects 60-63, wherein the catalytic composition is contacted with ethylene and an olefin comonomer comprising a C3-C10 alpha-olefin. Aspect 65. The process defined in any of aspects 60-64, wherein the catalyst composition is contacted with ethylene and an olefin comonomer comprising 1-butene, 1-hexene, 1-octene or a mixture thereof. Aspect 66. The process defined in any of aspects 60-65, wherein the polymerization reactor system comprises a batch reactor, a suspension reactor, a gas-phase reactor, a solution reactor, a high-pressure reactor, a tubular reactor, an autoclave reactor, or a combination thereof. Aspect 67. The process defined in any of aspects 60-66, wherein the polymerization reactor system comprises a suspension reactor, a gas-phase reactor, a solution reactor, or a combination thereof. Aspect 68. The process defined in any of aspects 60-67, wherein the polymerization reactor system comprises a loop suspension reactor. Aspect 69. The process defined in any of aspects 60-68, wherein the polymerization reactor system comprises a single reactor. Aspect 70. The process defined in any of aspects 60-68, wherein the polymerization reactor system comprises 2 reactors. Aspect 71. The process defined in any of aspects 60-68, wherein the polymerization reactor system comprises more than 2 reactors. Aspect 72. The process defined in any of aspects 60-71, where the polymer defined comprises any polymer defined herein. Aspect 73. The process defined in any of aspects 60-72, wherein the polymer defined comprises an ethylene homopolymer, an ethylene / 1-butene copolymer, an ethylene / 1-hexene copolymer and / or an ethylene / 1-octene copolymer. Aspect 74. The process defined in any of aspects 60-73, wherein the olefin polymer comprises an ethylene / 1-hexene copolymer. Aspect 75. The process defined in any of aspects 60-74, wherein the polymerization conditions comprise a polymerization reaction temperature in the range of about 60°C to about 120°C and a reaction pressure in the range of about 13.8 bar (200 psig) to about 68.94 bar (1000 psig) (from about 1.4 to about 6.9MPa). Aspect 76. The process defined in any of aspects 60-75, wherein the polymerization conditions are substantially constant, for example, for a particular polymer grade. Aspect 77. The process defined in any of aspects 60-76, wherein no hydrogen is added to the polymerization reactor system. Aspect 78. The process defined in any of aspects 60-76, where hydrogen is added to the polymerization reactor system. Aspect 79. The process defined in any of aspects 60-78, wherein the olefin polymer produced is defined in any of aspects 1-31. IVIA / a / ZUZZ / UUUOOU Aspect 80. An olefin polymer produced by the olefin polymerization process defined in any of aspects 60-78. Aspect 81. An ethylene polymer as defined in any of aspects 1-31 produced by the process defined in any of aspects 60-78. Aspect 82. An article (for example, a blow-molded article) comprising the polymer defined in aspect 80 or 81.

Claims

1. An ethylene polymer having: a density in the range of about 0.952 to about 0.965 g / cm3; a high load melt index (HLMI) in the range of about 5 to about 25 g / 10 min; a weight average molecular weight (Mw) in the range of about 275,000 to about 450,000 g / mol; a number average molecular weight (Mn) in the range of about 15,000 to about 40,000 g / mol; an η at HLMI in the range of about 1400 to about 4000 Pa-s; and a tan δ at 0.1 s-1 in the range of about 0.65 to about 0.98 degrees.

2. The polymer according to claim 1, wherein the ethylene polymer has an environmental stress cracking resistance (ESCR) of at least 500 hours.

3. The polymer according to claim 1, wherein the ethylene polymer has an Mw / Mn ratio in the range of about 8 to about 20.

4. A blow-molded article comprising the ethylene polymer according to claim 1.

5. The polymer according to claim 1, wherein the ethylene polymer has: a CY-a parameter in the range of about 0.18 to about 0.36; and a viscosity at 100 s'1 in the range of about 1600 to about 2800 Pa-s.

6. The polymer according to claim 1, wherein the ethylene polymer has: less than about 0.008 long-chain branches per 1000 total carbon atoms; and an inverse comonomer distribution.

7. The polymer according to claim 1, wherein the ethylene polymer contains, independently, less than 0.08 ppm by weight of chromium and titanium.

8. The polymer according to claim 1, wherein: the density is in the range of about 0.952 to about 0.96 g / cm3; the HLMI is in the range of about 7 to about 15 g / 10 min; the Mw is in the range of about 300,000 to about 400,000 g / mol; the Mw is in the range of about 17,000 to about 40,000 g / mol; the η at HLMI is in the range of about 1500 to about 4000 Pa-s; and the tan δ at 0.1 s-1 is in the range of about 0.7 to about 0.97 degrees.

9. The polymer according to claim 8, wherein the ethylene polymer comprises an ethylene / 1-butene copolymer, an ethylene / 1-hexene copolymer and / or an ethylene / 1-octene copolymer.

10. An article comprising the ethylene polymer according to claim 9.

11. An ethylene polymer having: a density in the range of about 0.952 to about 0.965 g / cm3; an HLMI in the range of about 5 to about 25 g / 10 min; an Mw in the range of about 275,000 to about 450,000 g / mol; an Mn in the range of about 15,000 to about 28,000 g / mol; and an η at HLMI in the range of about 1400 to about 4000 Pa-s.

12. A blow-molded article comprising the ethylene polymer according to claim 11.

13. The polymer according to claim 11, wherein the ethylene polymer has: a CY-a parameter in the range of about 0.18 to about 0.36; and a viscosity at 100 s-1 in the range of about 1500 to about 3000 Pa-s.

14. The polymer according to claim 11, wherein the ethylene polymer has an ESCR of at least 1000 hours.

15. The polymer according to claim 11, wherein the ethylene polymer has: an IVc in the range of about 2.9 to about 3.7 dL / g; and a η to 0.1 / η to 100 ratio of about 85 to about 130.

16. The polymer according to claim 15, wherein: the density is in the range of about 0.952 to about 0.96 g / cm3; the HLMI is in the range of about 7 to about 15 g / 10 min; the Mw is in the range of about 300,000 to about 400,000 g / mol; the Mn is in the range of about 17,000 to about 27,000 g / mol; and the η at HLMI is in the range of about 1500 to about 4000 Pa-s.

17. An article comprising the ethylene polymer according to claim 16.

18. The article according to claim 17, wherein the ethylene polymer comprises an ethylene / 1-butene copolymer, an ethylene / 1-hexene copolymer and / or an ethylene / 1-octene copolymer.

19. A polymerization process, wherein the process comprises contacting a catalyst composition with ethylene and an α-olefin comonomer in a polymerization reactor system under polymerization conditions to produce an ethylene polymer, wherein the ethylene polymer has: a density in the range of about 0.952 to about 0.965 g / cm3; an HLMI in the range of about 5 to about 25 g / 10 min; a Mw in the range of about 275,000 to about 450,000 g / mol; a Mn in the range of about 15,000 to about 40,000 g / mol; and an η at HLMI in the range of about 1400 to about 4000 Pa-s; and a tan δ at 0.1 s-1 in a range from around 0.65 to around 0.98 degrees; and the catalyst composition comprises: an unbridged metallocene compound containing two cyclopentadienyl groups, two indenyl groups or a cyclopentadienyl group and an indenyl group; a bridged metallocene compound with a cyclopentadienyl group and a fluorenyl group, and an alkenyl substituent on the cyclopentadienyl group and / or on the bridging group; an activator support comprising a solid oxide treated with an electron-withdrawing anion; and an organoaluminum compound.

20. The process according to claim 19, wherein: the activator support comprises a fluorinated solid oxide and / or a sulfated solid oxide; and the polymerization reactor system comprises a suspension reactor, gas-phase reactor, solution reactor, or a combination thereof.