Polyethylene process and compositions thereof

Abstract

Embodiments of the present disclosure relate to a process for preparing a polyethylene composition, the process comprising: polymerizing ethylene in a first gas phase reactor and in a second gas phase reactor in the presence of hydrogen; wherein at least one of the first gas phase reactor or the second gas phase reactor comprises a first polymerization zone and a second polymerization zone; wherein the hydrogen pressures of the first polymerization zone and the second polymerization zone differ such that at least a portion of the second ethylene is circulated through the first polymerization zone and the second polymerization zone, and the gas mixture of each polymerization zone is partially or completely prevented from entering the other zone.

Description

[0001] Prior related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 530,208, filed August 1, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to an ethylene polymerization process and a polyethylene composition (which includes a composition having a content of 0.946 g / cm³). 3 (or those with higher densities), the polyethylene composition can be used to prepare extruded articles (including, for example, conduits, pipes and tubing). Background Technology

[0004] Processability and mechanical properties of polyethylene polymers have been achieved by blending Cr-catalyzed polyethylene materials with Ziegler-Natta-catalyzed materials, as disclosed in U.S. Patent 4,536,550 and International Patent Application WO 2005 / 097888. Mechanical blending does not always yield ideal polymer compositions, prompting the development of methods for the simultaneous production of polymers that allow for the blending of different polymers at the molecular level. Balancing the following properties remains an ongoing challenge: processability, high mold swell with high-quality surfaces, dimensional stability, melt processing at high shear rates, flow instability, and environmental stress cracking resistance (ESCR). Summary of the Invention

[0005] In some aspects, this disclosure provides a process for preparing a polyethylene composition, the process comprising the following steps performed in any order:

[0006] (a) Providing at least a first amount of ethylene and optionally a first amount of hydrogen to the first gas phase reactor;

[0007] (b) Providing at least a first amount of Ziegler-Natta catalyst to the first gas phase reactor to produce at least a first amount of polyethylene polymer in the first gas phase reactor;

[0008] (c) At least a portion of the first amount of polyethylene polymer and at least a portion of the first amount of Ziegler-Natta catalyst are transferred to a second gas-phase reactor;

[0009] (d) In the presence of a second amount of hydrogen, at least a second amount of ethylene is supplied to the second gas phase reactor to obtain a second polyethylene polymer, thereby producing a polyethylene composition comprising a first polyethylene polymer and the second polyethylene polymer.

[0010] At least one of the first gas-phase reactor or the second gas-phase reactor includes a first polymerization zone and a second polymerization zone, the first polymerization zone having a first hydrogen pressure and the second polymerization zone having a second hydrogen pressure, wherein the first hydrogen pressure and the second hydrogen pressure are different, such that at least a portion of the second amount of ethylene moves through the first polymerization zone and the second polymerization zone, and at least a portion of the gas mixture in each polymerization zone is partially or completely prevented from entering the other zone. In some embodiments, the polymerized ethylene flows upward through the first polymerization zone (also referred to herein as a "riser"); exits the first polymerization zone and enters the second polymerization zone (also referred to herein as a "downsink") through which the polymerized ethylene flows downward under gravity; exits the second polymerization zone; and is reintroduced into the first polymerization zone, thereby establishing a circulation of the polymerized ethylene between the first polymerization zone and the second polymerization zone in at least one of the first gas-phase reactor and the second gas-phase reactor. In some embodiments, the upward flow through the first polymerization zone is under rapid fluidization or transport conditions. In some embodiments, the first polymerization zone has a hydrogen to ethylene ratio of about 0.25 to about 1.9. In some embodiments, the hydrogen to ethylene ratio in the first polymerization zone is about 0.47. In some embodiments, the second polymerization zone has a hydrogen to ethylene ratio of about 0.001 to about 0.25. In some embodiments, the hydrogen to ethylene ratio is about 0.14. In some embodiments, step (c) or step (d) contains one or more comonomers. In some embodiments, steps (c) and (d) contain one or more comonomers. In some embodiments, the comonomer is a terminal olefin. （C≤20）In some embodiments, the comonomer is 1-hexene. In some embodiments, the second polymerization zone has a comonomer percentage of about 0.05% to about 0.6%. In some embodiments, the comonomer percentage is about 0.35%. In some embodiments, the second polymerization zone has a comonomer percentage of about 0.2% to about 1.2%. In some embodiments, the comonomer percentage is about 0.5%. In some embodiments, the process further includes obtaining a first polyethylene in the presence of hydrogen in the first gas-phase reactor. In some embodiments, the first gas-phase reactor has a hydrogen-to-ethylene ratio of about 0.25 to about 1.9. In some embodiments, the hydrogen-to-ethylene ratio in the first gas-phase reactor is about 1.5. In some embodiments, the process further includes obtaining polyethylene in the presence of hydrogen in both the first and second gas-phase reactors. In some embodiments, the hydrogen in the second gas-phase reactor is less than the hydrogen in the first gas-phase reactor. In some embodiments, the first or second gas-phase reactor further includes propane as an inert diluent. In some embodiments, the first gas-phase reactor and the second gas-phase reactor further comprise propane as an inert diluent. In some embodiments, the first gas-phase reactor is operated at a temperature selected from about 70°C to about 95°C. In some embodiments, the temperature is about 80°C. In some embodiments, the first gas-phase reactor is pressurized and operated at a pressure selected from between about 2.5 MPa and about 3.5 MPa. In some embodiments, the pressure is about 2.9 MPa. In some embodiments, the second gas-phase reactor is operated at a temperature selected from about 70°C to about 95°C. In some embodiments, the temperature is about 84°C. In some embodiments, the second gas-phase reactor is pressurized and operated at a pressure selected from about 2.0 MPa to about 3.0 MPa. In some embodiments, the pressure is about 2.5 MPa. In some embodiments, the Ziegler-Natta polymerization catalyst comprises a solid catalyst component and an organoaluminum compound, the solid catalyst component comprising a titanium compound on a magnesium support. In some embodiments, the solid catalyst component is produced by contacting the titanium compound with magnesium chloride or a precursor magnesium compound. In some embodiments, the solid catalyst component is heated to a temperature of about 130°C to about 150°C. In some embodiments, the temperature is about 135°C to about 150°C. In some embodiments, the solid catalyst component is produced by contacting the titanium compound with magnesium chloride or a precursor magnesium compound in the presence of an inert medium. In some embodiments, the Ziegler-Natta polymerization catalyst further includes an external electron donor compound. In some embodiments, the external electron donor compound is an alcohol. In some embodiments, the external electron donor compound is ethanol. In some embodiments, the Ziegler-Natta polymerization catalyst is prepolymerized with propylene.In some embodiments, the Ziegler-Natta polymerization catalyst is prepolymerized with about 1 gram of polypropylene per gram of solid catalyst component. In some embodiments, the polyethylene composition has a range of about 0.946 g / cm³. 3 Approximately 0.960 g / cm³ 3 Another selected site has a concentration greater than approximately 0.946 g / cm³. 3 The density, HLMI of about 20 to about 40 g / 10 min, MI2 of about 0.20 to about 0.40 g / 10 min, and M of about 15 to about 30 w / M n The ratio and a long-chain branching index below about 0.60. In some embodiments, the polyethylene composition further has a zero-shear viscosity (eta0) of about 150,000 to about 650,000 Pa × s (“Pa × s”). In some embodiments, the process produces a polyethylene composition comprising:

[0011] (A) By weight, about 40% to about 60% of an ethylene homopolymer or copolymer having a content equal to or greater than about 0.960 g / cm³. 3 The density and the melt flow index (MI2) at 190°C and a load of 2.16 kg, approximately 5 to approximately 20 g / 10 min (“g / 10 min”); and

[0012] (B) By weight about 40% to about 60% of an ethylene homopolymer or copolymer having an MI2 value lower than that of (A).

[0013] In some embodiments, the MI2 value of the ethylene copolymer in (B) is less than about 0.5 g / 10 min.

[0014] In another aspect, this disclosure provides a polyethylene composition comprising:

[0015] (a) First polyethylene produced in a first gas-phase reactor in the presence of a first amount of hydrogen; and

[0016] (b) The second polyethylene produced in a second gas-phase reactor in the presence of a second amount of hydrogen, wherein the second amount of hydrogen is less than the first amount of hydrogen.

[0017] The first polyethylene and the second polyethylene are produced in any order and in the presence of a Ziegler-Natta catalyst. At least one of the first or second gas-phase reactors includes a first polymerization zone and a second polymerization zone. The first polymerization zone has a first hydrogen pressure, and the second polymerization zone has a second hydrogen pressure, wherein the first and second hydrogen pressures differ such that at least a portion of a second amount of ethylene moves through the first and second polymerization zones, and at least a portion of the gas mixture in each polymerization zone is partially or completely prevented from entering the other zone. In some embodiments, in at least one of the first and second gas-phase reactors, the polymerized ethylene polymer: flows upward through the first polymerization zone; leaves the first polymerization zone and enters the second polymerization zone through which the polymerized ethylene polymer flows downward under gravity; leaves the second polymerization zone; and is reintroduced into the first polymerization zone, thereby establishing a cycle of the polymerized ethylene polymer between the first and second polymerization zones in at least one of the first and second gas-phase reactors. In some embodiments, the upward flow through the first polymerization zone is under rapid fluidization or transport conditions. In some embodiments, step (a) or step (b) contains one or more comonomers. In some embodiments, steps (a) and (b) contain one or more comonomers. In some embodiments, the comonomer is a terminal olefin. （C≤20）In some embodiments, the comonomer is 1-hexene. In some embodiments, the process further includes obtaining a first polyethylene in the presence of hydrogen in the first gas-phase reactor. In some embodiments, the process further includes obtaining polyethylene in the presence of hydrogen in both the first and second gas-phase reactors. In some embodiments, the hydrogen in the second gas-phase reactor is less than the hydrogen in the first gas-phase reactor. In some embodiments, the first or second gas-phase reactor further includes propane as an inert diluent. In some embodiments, both the first and second gas-phase reactors further include propane as an inert diluent. In some embodiments, the first gas-phase reactor is operated at a temperature selected from about 70°C to about 95°C. In some embodiments, the temperature is about 80°C. In some embodiments, the first gas-phase reactor is pressurized and operated at a pressure selected from between about 2.5 MPa and about 3.5 MPa. In some embodiments, the pressure is about 2.9 MPa. In some embodiments, the second gas-phase reactor is operated at a temperature selected from about 70°C to about 95°C. In some embodiments, the temperature is about 84°C. In some embodiments, the second gas-phase reactor is pressurized and operated at a pressure selected from about 2.0 MPa to about 3.0 MPa. In some embodiments, the pressure is about 2.5 MPa. In some embodiments, the Ziegler-Natta polymerization catalyst comprises a solid catalyst component and an organoaluminum compound, the solid catalyst component comprising a titanium compound on a magnesium support. In some embodiments, the solid catalyst component is generated by contacting the titanium compound with magnesium chloride or a precursor magnesium compound. In some embodiments, the solid catalyst component is heated to a temperature of about 130°C to about 150°C. In some embodiments, the temperature is about 135°C to about 150°C. In some embodiments, the solid catalyst component is generated by contacting the titanium compound with magnesium chloride or a precursor magnesium compound in the presence of an inert medium. In some embodiments, the Ziegler-Natta polymerization catalyst further comprises an external electron donor compound. In some embodiments, the external electron donor compound is an alcohol. In some embodiments, the external electron donor compound is ethanol. In some embodiments, the Ziegler-Natta polymerization catalyst is prepolymerized with propylene. In some embodiments, the solid catalyst component is prepolymerized with about 1 gram of polypropylene per gram of solid catalyst component. In some embodiments, the polyethylene composition has a content of about 0.946 g / cm³. 3 Approximately 0.960 g / cm³ 3 Another selected site has a concentration greater than approximately 0.946 g / cm³. 3 Or, alternatively, approximately 0.949 g / cm³ 3The polyethylene composition exhibits the following characteristics: density; HLMI of about 20 to about 40 g / 10 min; MI2 of about 0.20 to about 0.40 g / 10 min; and a long-chain branching index of less than about 0.60. In some embodiments, the polyethylene composition further has an eta0 of about 150,000 to about 650,000 Pa×s. In some embodiments, the polyethylene composition comprises:

[0018] (A) By weight, about 40% to about 60% of an ethylene homopolymer or copolymer having a content equal to or greater than about 0.960 g / cm³. 3 The density and the melt flow index (MI2) at 190°C and a load of 2.16 kg, approximately 5 to approximately 20 g / 10 min; and

[0019] (B) By weight about 40% to about 60% of an ethylene homopolymer or copolymer having an MI2 value lower than that of (A).

[0020] In some embodiments, the MI2 value of the ethylene copolymer in (B) is less than about 0.5 g / 10 min.

[0021] In another aspect, this disclosure provides a polyethylene composition having:

[0022] (A) The range is approximately 0.946 g / cm³. 3 Approximately 0.960 g / cm³ 3 And another selected area is greater than approximately 0.946 g / cm³ 3 The density;

[0023] (B) HLMI of approximately 20 to approximately 40 g / 10 min;

[0024] (C) MI2 of approximately 0.20 to approximately 0.40 g / 10 min;

[0025] (D) M from approximately 15 to approximately 30 w / M n than; and

[0026] (E) The long chain branching index is below approximately 0.6.

[0027] In some embodiments, the polyethylene composition further comprises:

[0028] (F) Zero shear viscosity (eta0) of approximately 150,000 to approximately 650,000 Pascals per second (“Pa×s”).

[0029] (G) Melt elasticity (ER) greater than 3.5.

[0030] In some implementations, the density is approximately 0.949 g / cm³. 3 In some implementations, the density is approximately 0.950 g / cm³. 3 In some embodiments, the long-chain branching index is equal to or less than about 0.54. In some embodiments, the long-chain branching index is equal to or less than about 0.52. In some embodiments, the long-chain branching index is between about 0.2 and about 0.6. In some embodiments, the polyethylene composition further comprises one or more ethylene copolymers. In some embodiments, the polyethylene composition comprises a comonomer content between about 0.1% and about 2.5% by weight. In some embodiments, the polyethylene composition comprises a comonomer content between about 1% and about 2.5% by weight. In some embodiments, the polyethylene composition is produced using a Ziegler-Natta polymerization catalyst. In some embodiments, the Ziegler-Natta polymerization catalyst comprises contacting a solid catalyst component with an organoaluminum compound. In some embodiments, the Ziegler-Natta polymerization catalyst further comprises adding an external electron donor compound. In some embodiments, the solid catalyst component comprises a titanium compound supported on magnesium chloride. In some embodiments, the solid catalyst component comprises contacting a titanium compound with MgCl2 or a precursor Mg compound at a temperature of about 130°C to about 150°C. In some embodiments, the temperature is about 135°C to about 150°C. In some embodiments, the solid catalyst component is produced by contacting the titanium compound with the MgCl2 or the precursor Mg compound in an inert medium. In some embodiments, the polyethylene composition further has at least one characteristic selected from the group consisting of:

[0031] (a) M equal to or less than about 225,000 g / mol (“g / mol”) w ;

[0032] (b) M of approximately 15 to approximately 30 w / M n than; and

[0033] (c) M equal to or greater than about 800,000 g / mol z .

[0034] In some implementation schemes, M w Equal to or less than approximately 210,000 g / mol. In some implementations, M w The concentration is from about 170,000 g / mol to about 210,000 g / mol. In some embodiments, the polyethylene composition comprises:

[0035] (A) By weight, about 40% to about 60% of an ethylene homopolymer or copolymer having a content equal to or greater than about 0.960 g / cm³. 3 The density and the melt flow index (MI2) at 190°C and a load of 2.16 kg, approximately 5 to approximately 20 g / 10 min; and

[0036] (B) By weight about 40% to about 60% of an ethylene homopolymer or copolymer having an MI2 value lower than that of (A).

[0037] In some embodiments, the MI2 value of the ethylene copolymer in (B) is less than about 0.5 g / 10 min.

[0038] In another aspect, this disclosure provides an article of manufacture comprising the polyethylene composition of this disclosure. In some embodiments, the article is produced by extrusion. In some embodiments, the article is a hollow article, alternatively a thin-walled article, and alternatively a conduit, pipe, or conduit. Attached Figure Description

[0039] These and other features, aspects, and advantages of this disclosure will become better understood with reference to the following description, the appended claims, and the accompanying drawings, wherein:

[0040] The attached figure is an exemplary embodiment of a simplified process flow diagram of two gas-phase reactors connected in series, which are suitable for use in various embodiments of the ethylene polymerization process disclosed herein to produce the polyethylene compositions disclosed herein.

[0041] It should be understood that the various implementation schemes are not limited to the arrangements and tools shown in the accompanying drawings. Detailed Implementation

[0042] The terms "polyethylene composition," "polyethylene," "ethylene polymer," and related terms are intended, as alternatives, to cover both single ethylene polymers and ethylene polymer compositions, particularly compositions of two or more ethylene polymer components. In some embodiments, the polyethylene composition comprises two or more ethylene polymer components with different molecular weights. In some aspects, compositions comprising two or more ethylene polymer components with different molecular weights may also be described in the relevant art as "bimodal" or "multimodal" polymers. In some embodiments, the polyethylene compositions of this disclosure comprise one or more ethylene copolymers. Unless otherwise stated, the ratios in this disclosure should be molar ratios to those skilled in the art.

[0043] When used in the context of chemical groups: "hydrogen" means -H; "hydroxyl" means -OH; and "halogen" means one or more elements independently selected from the group consisting of -F, -Cl, -Br, and -I.

[0044] For the groups and categories mentioned below, the subscripts in parentheses further define the groups / categories as follows: "(Cn)" defines the exact number (n) of carbon atoms in the group / category. "(C≤n)" defines the maximum number (n) of carbon atoms that can exist in the group / category, while the minimum number is as small as possible for the group under consideration. For example, it should be understood that the group "alkenyl" （C≤8） "or category "alkenes" （C≤8） The minimum number of carbon atoms in a compound is two. For example, "alkoxy" （C≤10） "" indicates alkoxy groups having 1 to 10 carbon atoms. (Cn-n') defines both the minimum (n) and maximum (n') number of carbon atoms in the group. Similarly, "alkyl" （C2-10） "" indicates alkyl groups having 2 to 10 carbon atoms.

[0045] As used herein, the term "saturated" means that a compound or group has been modified such that it lacks carbon-carbon double and triple bonds, unless otherwise noted below. With regard to the substitution pattern of a saturated group, one or more carbon-oxygen or carbon-nitrogen double bonds may be present. And when such bonds are present, carbon-carbon double bonds that may appear as part of a keto-enol tautomerism or an imine / enamine tautomerism are not excluded.

[0046] The term "aliphatic" when used without the modifier "substitution" indicates that a compound / group has been modified to be an acyclic or cyclic but non-aromatic hydrocarbon compound or group. In aliphatic compounds / groups, carbon atoms can be linked together in straight chains, branched chains, or non-aromatic rings (alicyclic rings). Aliphatic compounds / groups can be saturated, i.e., linked by single bonds (alkane / alkyl), or unsaturated, having one or more double bonds (alkene / alkenyl) or one or more triple bonds (alkynyl / alkynyl).

[0047] The term "alkyl" when used without the modifier "substituted" refers to a monovalent saturated aliphatic group that has a straight or branched, cyclic, cyclic, or acyclic structure with a carbon atom as the attachment point, and contains no atoms other than carbon and hydrogen. Therefore, as used herein, cycloalkyl is a subset of alkyl groups in which the carbon atom forming the attachment point is also a member of one or more non-aromatic ring structures, wherein the cycloalkyl group does not contain atoms other than carbon and hydrogen. As used herein, the term does not exclude the presence of one or more alkyl groups (carbon number restrictions allow) attached to the ring or ring system. Groups −CH3 (Me), −CH2CH3 (Et), −CH2CH2CH3 (n-Pr or propyl), −CH(CH3)2 (i-Pr, i Pr or isopropyl), −CH(CH2)2 (cyclopropyl), −CH2CH2CH2CH3 (n-Bu), −CH(CH3)CH2CH3 (sec-butyl), −CH2CH(CH3)2 (isobutyl), −C(CH3)3 (tert-butyl, t-butyl, t-Bu or t Bu), −CH2C(CH3)3 (neo-pentyl), cyclobutyl, cyclopentyl, cyclohexyl, and cyclohexylmethyl are non-limiting examples of alkyl groups. "Alkane" refers to the compound H−R, where R is an alkyl group, as the term is defined above. When any of these terms is used with the modifier "substitution," one or more hydrogen atoms have been independently replaced by: −OH, −F, −Cl, −Br, −I, −NH2, −NO2, −CO2H, −CO2CH3, −CN, −SH, −OCH3, −OCH2CH3, −C(O)CH3, −NHCH3, −NHCH2CH3, −N(CH3)2, −C(O)NH2, −OC(O)CH3, or −S(O)2NH2. The following groups are non-limiting examples of substituted alkyl groups: −CH2OH, −CH2Cl, −CF3, −CH2CN, −CH2C(O)OH, −CH2C(O)OCH3, −CH2C(O)NH2, −CH2C(O)CH3, −CH2OCH3, −CH2OC(O)CH3, −CH2NH2, −CH2N(CH3)2, and −CH2CH2Cl. The term "haloalkyl" is a subset of substituted alkyl groups in which one or more hydrogen atoms have been replaced by a halogen group, and no atoms other than carbon, hydrogen, and halogen are present. The group −CH2Cl is a non-limiting example of a haloalkyl group. The term "fluoroalkyl" is a subset of substituted alkyl groups in which one or more hydrogen atoms have been replaced by a fluorinated group, and no atoms other than carbon, hydrogen, and fluorine are present. The groups −CH2F, −CF3, and −CH2CF3 are non-limiting examples of fluoroalkyl groups.

[0048] The term "alkenyl," when used without the modifier "substitution," refers to a monovalent unsaturated aliphatic group having a straight or branched, cyclic, or acyclic structure with a carbon atom as the attachment point, having at least one non-aromatic carbon-carbon double bond, no carbon-carbon triple bond, and containing no atoms other than carbon and hydrogen. Non-limiting examples of alkenyl groups include: −CH=CH2 (vinyl), −CH=CHCH3, −CH=CHCH2CH3, −CH2CH=CH2 (allyl), −CH2CH=CHCH3, and −CH=CHCH=CH2. The term "alkenidyl," when used without the modifier "substitution," refers to a divalent unsaturated aliphatic group having a straight or branched, cyclic, or acyclic structure with two carbon atoms as attachment points, having at least one non-aromatic carbon-carbon double bond, no carbon-carbon triple bond, and containing no atoms other than carbon and hydrogen. Groups −CH=CH−, −CH=C(CH3)CH2−, −CH=CHCH2− and These are non-limiting examples of alkenyl groups. It should be noted that although alkenyl groups are aliphatic, once connected at both ends, this does not preclude the group from forming part of an aromatic structure. The terms "alkene" or "olefin" are synonymous and refer to compounds having the formula H−R, where R is an alkenyl group, as the term has been defined above. A "terminal alkene" refers to an alkene having only one carbon-carbon double bond, where this bond forms a vinyl group at one end of the molecule. When any of these terms are used with the modifier "substitution," one or more hydrogen atoms have been independently replaced by: −OH, −F, −Cl, −Br, −I, −NH2, −NO2, −CO2H, −CO2CH3, −CN, −SH, −OCH3, −OCH2CH3, −C(O)CH3, −NHCH3, −NHCH2CH3, −N(CH3)2, −C(O)NH2, −OC(O)CH3, or −S(O)2NH2. The groups −CH=CHF, −CH=CHCl, and −CH=CHBr are non-limiting examples of substituted alkenyl groups.

[0049] In some aspects of this disclosure, one or more of the following abbreviations are used: g / cm 3 g / cm³; ESCR (Environmental Stress Cracking Resistance); MPa (megapascals); °C (degrees Celsius); g or gr (grams); g / 10min (grams per 10 minutes); Pa×s (pascals per second); g / mol (grams per mole); RPM (revolutions per minute); %wt (weight percentage); ppm (parts per million); h or hr (hours); m or min (minutes); m / s (meters per second); rad / s (radians per second); kJ / m³ 2, kilojoules per square meter; dL / g, deciliters per gram; μL, microliter; mm, millimeter; K / min, Kelvin per minute; s or sec, second; mg, milligram; ml or mL, milliliter; mg / L, milligram per liter; kg / h, kilogram per hour; g / h, g per hour; or nm, nanometer.

[0050] In some embodiments, the ethylene polymer or ethylene polymer composition of this disclosure is defined by the polymer properties described herein. In some embodiments, the addition of other components (including additives commonly used in the art) may modify one or more of the said properties of the polymer, and specifically includes polymers comprising these additional components. In some embodiments, the polyethylene polymerization method of this disclosure does not require mechanical blending of the two components obtained by using different polymerization catalysts.

[0051] The measurement of molecular weight distribution is carried out by M w / M n Compared to what is provided, where M w It is the weight-average molar mass, and M n Both are number-average molar masses, measured by GPC (gel permeation chromatography). The methods for determining these measurements are defined in the Examples section and provided by standards ISO 16014-1, ISO 16014-2, and ISO 16014-4, published in 2003. In some embodiments, the M of the polyethylene composition of this disclosure... w / M n The value ranges from approximately 15 to approximately 30.

[0052] In some embodiments, the polyethylene composition according to this disclosure further has one or more of the following additional features:

[0053] - M equal to or less than about 225,000 g / mol, more preferably equal to or less than about 210,000 g / mol, particularly about 170,000 to about 210,000 g / mol w ;

[0054] - M greater than about 4, especially greater than about 4.25 z / M w ;

[0055] - M equal to or greater than about 800,000 g / mol, or equal to or greater than about 900,000 g / mol z ;

[0056] -MI2 (melt flow index according to ISO 1133 at 190°C and 2.16 kg load): less than about 1 g / 10 min, particularly less than about 0.5 g / 10 min, particularly between 0.20 and about 0.40 g / 10 min;

[0057] - Titanium content from about 0.5 parts per million (or "ppm") to about 4 parts per million by weight;

[0058] - Magnesium content of approximately 5 to approximately 15 ppm by weight;

[0059] - A comonomer content equal to or less than about 2.5% by weight, particularly about 0.1% to about 2.5% by weight, relative to the total weight of the composition.

[0060] In some embodiments, the polyethylene composition may further comprise a comonomer, or the comonomer present in the ethylene copolymer is typically selected from olefins having the formula CH2=CHR, wherein R is an alkyl group. （C≤12） Or substituted alkyl （C≤12） Some non-limiting examples of comonomers include propylene, 1-butene, 1-pentene, 4-methylpent-1-ene, 1-hexene, 1-octene, and 1-decene. In some embodiments, the comonomer is 1-hexene.

[0061] The density of a polyethylene composition can be used to determine the potential uses of the polymer. In some embodiments, the density of the polyethylene composition according to this disclosure is:

[0062] - Approximately 0.946 to approximately 0.960 g / cm³ 3 Or approximately 0.949 to approximately 0.955 g / cm³ 3 Or approximately 0.949 to approximately 0.951 g / cm³ 3 Or approximately 0.949.

[0063] In some respects, the long-chain branching index of this disclosure can affect the application of the polymer. The long-chain branching index is defined as the measured mean square radius of gyration R measured by GPC-MALLS. g The ratio of the radius of gyration to that of linear PE having the same molecular weight, or as defined in the examples. In some embodiments, the LCBI of the polyethylene compositions of this disclosure ranges from less than about 0.6 to about 0.2. In some embodiments, the LCBI ranges from about 0.58 to about 0.52. In some embodiments, the LCBI ranges from about 0.57 to about 0.55. In some embodiments, the LCBI ranges from about 0.35 to about 0.50. In some embodiments, the LCBI is about 0.56.

[0064] In some embodiments, the polyethylene composition comprises two polyethylene homopolymers or copolymers, or homopolymers and copolymers. In some embodiments, one polyethylene component comprises between about 1% and about 99% by weight of the total weight, and the other polyethylene component comprises the remaining percentage by weight of the total weight. In a preferred embodiment, the composition of the present invention comprises:

[0065] (A) By weight, about 40% to about 60% of an ethylene homopolymer or copolymer having a content equal to or greater than about 0.960 g / cm³. 3 The density and the melt flow index MI2 of about 5 to about 20 g / 10 min at 190 °C and 2.16 kg load according to ISO 1133;

[0066] (B) 40% to 60% by weight of an ethylene copolymer having an MI2 value lower than that of (A), preferably lower than about 0.5 g / 10 min.

[0067] In some embodiments, (A) comprises a homopolymer. The percentage amounts given above are given relative to the total weight of (A) + (B), provided that the total weight does not exceed 100%. The amount of comonomer in (B) is preferably from about 0.2% to about 5% by weight relative to the total weight of (B). The total amount of comonomer in (A) + (B) is preferably from about 0.1% to about 2.5% by weight relative to the total weight of (A) + (B).

[0068] In some aspects, the polyethylene compositions of the present invention are used in the preparation of extruded articles. Some non-limiting examples of extruded articles include bottles, pipes, tubes, conduits, tracks, boxes, and containers. Further uses of the polyethylene compositions disclosed herein will be known to those skilled in the art and depend on the specific properties of the resulting polyethylene compositions. In some embodiments, the polyethylene compositions have one or more of the following desired properties:

[0069] - A mold expansion ratio equal to or greater than about 145%, particularly about 150% to about 185%, preferably about 151% to about 158%;

[0070] - Approximately 80 kilojoules per square meter ("kJ / m²") 2 "" or higher tensile notch impact (T=-30℃);

[0071] - 4 or higher Charpy aCN (T=-30℃);

[0072] - Environmental stress cracking resistance for approximately 2 hours, measured by FNCT at 4MPa / 80℃;

[0073] - Environmental stress cracking resistance for approximately 13 hours, measured by FNCT 6MPa / 50℃;

[0074] - Environmental stress cracking resistance for >100 hours, measured by 10% Igepal (F10);

[0075] - Environmental stress cracking resistance >135 hours, measured by 10% Igepal (F50);

[0076] - Environmental stress cracking resistance > approximately 900 hours, measured by 100% Igepal (F50).

[0077] In some embodiments, the polyethylene compositions of this disclosure can be melt-processed at high shear rate values ​​without experiencing pressure oscillations and flow instabilities, thereby making them suitable for the preparation of extruded articles.

[0078] The polyethylene compositions described in this disclosure can be prepared using a wide variety of polymerization processes, including but not limited to gas-phase, solution-phase, multiphase, or slurry polymerization. Additionally, the polyethylene compositions can be prepared using any catalyst known to enhance polyolefin production, including but not limited to Ziegler-Natta catalysts, metallocene catalysts, or chromium-based catalysts. In some preferred embodiments, the polyethylene compositions of this disclosure can be prepared by a gas-phase polymerization process in the presence of a Ziegler-Natta catalyst.

[0079] Ziegler-Natta catalysts comprise the reaction products of organometallic compounds from Groups 1, 2, or 13 of the periodic table with transition metal compounds from Groups 4 to 10 of the periodic table (using the new numbering system). Specifically, the transition metal compound may be selected from compounds of Ti, V, Zr, Cr, and Hf, and is preferably supported on MgCl2. In some embodiments, the catalyst comprises the reaction products of the said organometallic compounds from Groups 1, 2, or 13 of the periodic table with a solid catalyst component comprising a Ti compound supported on MgCl2. In some embodiments, the organometallic compound contains Al, B, and / or Li. In some embodiments, the organometallic compound is an organoaluminum compound. In some embodiments, these organoaluminum compounds comprise aluminum oxanes or trialkylaluminum.

[0080] In some embodiments, the polyethylene composition according to this disclosure can be obtained by using a Ziegler-Natta polymerization catalyst. In some embodiments, the Ziegler-Natta catalyst is supported on MgCl2. In some embodiments, the Ziegler-Natta catalyst is a reaction product of the following substances:

[0081] (a) A solid catalyst component comprising a Ti compound supported on MgCl2;

[0082] (b) organoaluminum compounds; and optionally

[0083] (c) External electron donor compound ED ext .

[0084] In some embodiments, the titanium compound used in the Ziegler-Natta polymerization catalyst is a titanium (IV) salt. In some embodiments, the titanium compound is a tetrahalide or has the formula TiX. n (OR 1 ) 4-n Compounds in which 0 ≤ n ≤ 3, X is a halogen, and R 1 It is an alkyl group （C≤10） Group. In some embodiments, the titanium compound is titanium tetrachloride or titanium tetraalkoxy.

[0085] In the solid catalyst composition, a variety of different solid supports can be used, including magnesium salts, silica, alumina, titanium dioxide, or other porous inert materials with high specific surface areas. In some embodiments, MgCl2 is a basic support. In some embodiments, MgCl2 contains trace amounts of additional support, provided that MgCl2 comprises more than 50% of the solid support. The use of MgCl2, or MgCl2 obtained from a precursor Mg compound, is considered, which can be converted to MgCl2 by reacting with a halogenated compound. In some embodiments, the active form of MgCl2 taught by U.S. Patents 4,298,718 and 4,495,338 (which are incorporated herein by reference) is used as the support for Ziegler-Natta catalysis. Unbound by theory, the active form of magnesium dihalides used as a support or co-support is characterized by X-ray spectroscopy, in which the strongest diffraction lines appearing in the ASTM card references of the spectra of the inactive halides decrease in intensity and broaden. In some implementations, the weakening and broadening of the strongest diffracted line causes it to be replaced by a halo peak, the maximum intensity of which is shifted at a lower angle relative to the maximum intensity of the strongest diffracted line.

[0086] In some embodiments, a catalyst is used to prepare the polyethylene composition according to the present disclosure, wherein a solid catalyst component is obtained by contacting a titanium compound with MgCl2 or a precursor Mg compound at a temperature of 130 to 150°C. In some embodiments, the preparation includes contacting the titanium compound with MgCl2 or a precursor Mg compound in an inert environment. In some embodiments, the temperature is preferably from about 135 to about 150°C. The contact with the titanium compound can be performed once, twice, three times, four times, or more. In some embodiments, the contact with the titanium compound lasts for a total time period of about 1 hour to about 4 hours. The preparation of the solid catalyst may include raising the temperature for a time period of about 30 minutes to about 2 hours, and then maintaining the reaction at that temperature for a time period of about 30 minutes to about 2 hours.

[0087] In some embodiments, the contact between MgCl2 or a precursor Mg compound and titanium is carried out in the presence of an electron donor compound. Non-limiting examples of electron donor compounds include compounds containing lone pairs of electrons or net negative dipoles on the surface of the molecule. In some embodiments, the electron donor compound used to prepare the Ziegler-Natta catalyst is preferably selected from the group consisting of ethers, esters, amines, ketones, nitriles, silanes, and mixtures thereof.

[0088] In some embodiments, the MgCl2 precursor can be used as the starting Mg compound. In some embodiments, the Mg compound has the formula MgR'2, where R' is an alkyl group. （C≤20） substituted alkyl （C≤20） OR, OCOR, or chlorine, where R is an alkyl group. （C≤20） substituted alkyl （C≤20） This is provided that R' is not simultaneously chlorine. Furthermore, Lewis adducts formed by MgCl2 with suitable Lewis bases can also be used as Mg precursor compounds. A particularly preferred class consists of MgCl2(R''OH). m The adduct is formed, wherein R'' is an alkyl group. （C≤20） Or substituted alkyl （C≤20）And m is from about 0.1 to about 6. In some embodiments, m is from about 0.5 to about 3. In some embodiments, m is from about 0.5 to about 2. This type of adduct can be obtained by mixing an alcohol and MgCl2 in the presence of an inert hydrocarbon immiscible with the adduct, operating under stirring at the melting temperature of the adduct (100°C to -130°C). The emulsion is then rapidly quenched, thereby solidifying the adduct into spherical particles. Representative methods for preparing these spherical adducts are reported, for example, in U.S. Patents 4,469,648, 4,399,054, and International Patent Application WO 98 / 44009, which are incorporated herein by reference. Another available method for spheroidization is spray cooling, for example, as described in U.S. Patents 5,100,849 and 4,829,034, which are also incorporated herein by reference.

[0089] In some implementations, MgCl2·(EtOH) m The adduct (where m is from about 0.15 to about 1.7) is obtained by subjecting an adduct with a high alcohol content to a thermal dealcoholization process. The thermal dealcoholization process can be carried out in a nitrogen stream at a temperature between about 50 and about 150°C until the alcohol content is reduced to the aforementioned value. This process is described, for example, in European Patent EP395083, which is incorporated herein by reference. In some embodiments, dealcoholization can also be carried out chemically by contacting the adduct with a compound capable of reacting with an alcohol group.

[0090] In some embodiments, these dealcohol adducts are also characterized by porosity (measured by the mercury method), which has a pore radius up to about 0.1 μm and a range from about 0.15 to about 2.5 cm. 3 / g pore volume. In some embodiments, the pore volume ranges from about 0.25 to about 1.5 cm³. 3 / g.

[0091] Solids can be recovered by separating the suspension using conventional methods such as sedimentation and liquid removal, filtration, and centrifugation, and can be washed with solvents. In some embodiments, the solid residue is washed with an inert hydrocarbon liquid. In other embodiments, the solid residue is washed with a solvent of greater polarity, such as a solvent with a higher dielectric constant, including halogenated hydrocarbons.

[0092] In some embodiments, a solid catalyst component is converted into a catalyst for olefin polymerization by reacting it with an organometallic compound of Group 1, Group 2, or Group 13 of the periodic table, according to known methods. In some embodiments, the organometallic compound is an organoaluminum compound. In some embodiments, the organoaluminum compound is Al(Y1)3, wherein Y1 is an alkyl group. （C≤20）The organoaluminum compound is a trialkylaluminum compound. Some non-limiting examples of trialkylaluminum compounds include triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, and tri-n-octylaluminum. It is contemplated to use alkylaluminum halides, alkylaluminum hydrides, or alkylaluminum sesquichlorides, such as AlEt2Cl and Al2Et3Cl3, in combination with said trialkylaluminum compounds.

[0093] In some embodiments, the catalyst can be prepolymerized by producing a reduced amount of polyolefin prior to achieving the polymerization required by this disclosure, according to known techniques. In some embodiments, the polyolefin is polypropylene or polyethylene. The amount of prepolymer produced can be from about 0.5 g / g component a) to about 500 g / g component a). In some embodiments, the amount of prepolymer produced is about 1 g / g solid catalyst.

[0094] In some aspects of this disclosure, polyethylene compositions according to this disclosure can be prepared using a process including the following steps with the polyethylene catalyst described above:

[0095] (a) Providing at least a first amount of ethylene and optionally a first amount of hydrogen to the first gas phase reactor;

[0096] (b) Providing at least a first amount of Ziegler-Natta catalyst to the first gas phase reactor to produce at least a first amount of polyethylene polymer in the first gas phase reactor;

[0097] (c) At least a portion of the first amount of polyethylene polymer and at least a portion of the first amount of Ziegler-Natta catalyst are transferred to a second gas-phase reactor;

[0098] (d) In the presence of a second amount of hydrogen, at least a second amount of ethylene is supplied to the second gas phase reactor to obtain a second polyethylene polymer, thereby producing a polyethylene composition comprising a first polyethylene polymer and the second polyethylene polymer.

[0099] At least one of the first or second gas-phase reactors includes a first polymerization zone and a second polymerization zone, the first polymerization zone having a first hydrogen pressure and the second polymerization zone having a second hydrogen pressure, wherein the first hydrogen pressure and the second hydrogen pressure are different, such that at least a portion of the second amount of ethylene moves through the first and second polymerization zones, and at least a portion of the gas mixture in each polymerization zone is partially or completely prevented from entering the other zone. In some embodiments, in at least one of the first and second gas-phase reactors, the grown polymer particles flow upward through the first polymerization zone (also referred to herein as a "riser") under rapid fluidization or conveying conditions, exit the riser and enter the second polymerization zone (also referred to herein as a "downstream") through which they flow downward under gravity, exit the downstream and are reintroduced into the riser, thereby establishing a polymer cycle between the two polymerization zones. In some embodiments, the polymerization of ethylene in step (a) or step (d) further includes a comonomer. In some embodiments, the polymerization of ethylene in step (a) further includes hydrogen.

[0100] In the first polymerization zone (riser), rapid fluidization conditions are established by feeding a gas mixture comprising one or more olefins (ethylene and comonomers) at a rate higher than the conveying velocity of the polymer particles. The velocity of the gas mixture preferably comprises between about 0.5 and about 15 m / s (“m / s”), more preferably between about 0.8 and about 5 m / s. The terms “conveying velocity” and “rapid fluidization conditions” are well known in the art. For alternative definitions of these terms, see, for example, D. Geldart, 1986, which is incorporated herein by reference.

[0101] In some aspects of this disclosure, a constraint is introduced between the first polymerization zone (riser) and the second polymerization zone (downcomer). In some embodiments, this constraint results in different flux conditions in each polymerization zone. In some embodiments, the different flux conditions include variations in the hydrogen or comonomer concentration in the polymerization zone. In some embodiments, the constraint includes a separator. In some embodiments, the separator is a liquid or gaseous separator. In some embodiments, the gas mixture from the riser is partially or completely blocked from entering the downcomer by the separator. In some embodiments, the conditions required to form the separator can be achieved by introducing a gas and / or liquid mixture having a different composition from the gaseous mixture present in the riser into the upper portion of the downcomer. In some embodiments, the gas / liquid mixture fed into the upper portion of the downcomer partially or completely replaces the gas mixture containing polymer particles entering the downcomer. Furthermore, in some embodiments, the flow rate of the gas or liquid mixture can be adjusted such that the gas flow forms a countercurrent with the polymer particle flow in the upper portion of the downcomer.

[0102] In some aspects of this disclosure, the separator in the second polymerization zone is a gas separator. Unbound by theory, the countercurrent flow of gas serves as a separator for the gas mixture containing polymer particles from the riser, as the established upward gas flow prevents the gas mixture present in the riser from entering the downcomer. In some embodiments, the mixture of different compositions to be fed into the upper portion of the downcomer may be in a partially or completely liquefied form. The liquefied gas mixture may also be sprayed into the downcomer, such that the evaporation of the liquid in the polymerization zone provides the desired gas flow.

[0103] In some aspects of this disclosure, the separator in the second polymerization zone is a liquid separator. In some embodiments, the separator comprises introducing a liquid solution into a downcomer. Unbound by theory, the liquid solution prevents the gas mixture from the riser from entraining polyethylene, such that the concentrations of hydrogen and comonomer in the downcomer are close to the concentration of the liquid solution. In some embodiments, the liquid separator originates from a stream of unreacted gas molecules recovered from the riser.

[0104] In one aspect, in the second polymerization zone (downcomer), polymer particles flow in a more concentrated manner under gravity, resulting in a high solids density (mass of polymer per reactor volume). In some embodiments, these density values ​​may approach the bulk density of the polymer. The applicant currently believes that the polymer flows vertically downward through the downcomer in a "piston flow" (filled flow mode), such that only a small amount of gas is entrained between the polymer particles. In some embodiments, the process produces an ethylene polymer from step (a) with a lower molecular weight than the ethylene copolymer obtained from step (d).

[0105] In one aspect of this disclosure, ethylene polymerization is carried out upstream of copolymerization of ethylene with comonomers to produce a relatively high molecular weight ethylene copolymer (step e) to produce a relatively low molecular weight ethylene polymer (step a). In some embodiments, step (a) is a gaseous mixture comprising ethylene, hydrogen, and an inert gas fed into a first gas-phase reactor. In some embodiments, the gas-phase reactor is a gas-phase fluidized bed reactor. In some embodiments, polymerization is carried out in the presence of the Ziegler-Natta catalyst previously described. In some embodiments, no comonomer is fed into the first gas-phase reactor, and a highly crystalline ethylene homopolymer is obtained in step (a). In other embodiments, a very small amount of comonomer is fed into the first gas-phase reactor, provided that the degree of copolymerization in step a) is limited to such that the density of the ethylene polymer obtained in step (a) is not less than 0.960 g / cm³. 3 .

[0106] In some embodiments, the use and amount of hydrogen depend on the specific catalyst used. In some embodiments, the amount of hydrogen used is suitable for obtaining an ethylene polymer with a melt flow index (MI2) of 5 to 20 g / 10 min in step (a). To obtain the aforementioned MI2 range in step (a), the hydrogen / ethylene molar ratio used can be from about 0.5:1 to about 3:1, and the amount of ethylene monomer is 2% to 15% by volume based on the total gas volume present in the polymerization reactor. In some embodiments, the amount of ethylene monomer is about 5% to 10% by volume. The remainder of the feed mixture is represented by an inert gas and one or more comonomers (if any). In some embodiments, the inert gas is necessary to dissipate the heat generated by the polymerization reaction. In some embodiments, any inert gas can be used. In some embodiments, the inert gas is selected from nitrogen or saturated hydrocarbons. In some embodiments, the inert gas is propane.

[0107] In some embodiments of this disclosure, the operating conditions of the polymerization reactor in step (a) include an operating temperature of about 50 to about 120°C. In some embodiments, the operating temperature is about 65 to 100°C. In some embodiments, the operating pressure of the polymerization reactor in step (a) is about 0.5 to about 10 MPa. In some embodiments, the operating pressure is about 2.0 to about 3.5 MPa. In some embodiments, the operating temperature is about 80°C and the operating pressure is about 2.9 MPa.

[0108] In some embodiments, the ethylene polymer obtained in step (a) accounts for 40% to 60% by weight of the total ethylene polymer produced in the entire process (i.e., in the first series-connected reactor and the second series-connected reactor).

[0109] In some embodiments, the ethylene polymer and entrained gas from step (a) are passed through a solid / gas separation step, which prevents the gaseous mixture from the first polymerization reactor from entering the reactor of step (d) (the second gas-phase polymerization reactor). In some embodiments, the gaseous mixture is recycled back to the first polymerization reactor while the separated ethylene polymer is fed to the reactor of step (d). In some embodiments, a suitable point for feeding the polymer into the second reactor is at the connection between the downcomer and the riser, where the solids concentration is particularly low so that the flow conditions are not negatively affected.

[0110] In some embodiments, the operating temperature in step (d) is from about 65 to about 95°C, and the pressure is from about 1.5 to about 4.0 MPa. In some embodiments, ethylene is copolymerized with one or more comonomers in a second gas-phase reactor. Furthermore, in some embodiments, the reactor in step (d) is operated such that different monomer and hydrogen concentration conditions are established in the riser and downcomer.

[0111] In some aspects of this disclosure, the gas mixture from the riser in step (d) carrying polymer particles can be partially or completely prevented from entering the downcomer, thereby obtaining two distinct gas composition zones. In some embodiments, the two distinct gas composition zones are achieved by feeding a gas and / or liquid mixture into the downcomer via a line placed at a suitable point in the downcomer. In some embodiments, this line is placed in its upper portion. In some embodiments, the gas and / or liquid mixture has a suitable composition different from that of the gas mixture present in the riser, thus forming two distinct gas composition zones. In some embodiments, the flow of the gas and / or liquid mixture can be regulated to generate an upward airflow running counter-current to the flow generated by the polymer particles. In some embodiments, separation at its top is most effective, such that the flow acts as a separator for the gas mixture from the riser, in which polymer particles are entrained. In particular, it is particularly advantageous to be able to feed a mixture with a low hydrogen content to produce a higher molecular weight polymer fraction in the downcomer. Additionally, one or more comonomers may optionally be fed into the downcomer of step (d) along with ethylene, propane, or other inert gases.

[0112] In some embodiments, based on the total volume of gas present in the downcomer, the hydrogen / ethylene molar ratio in the downcomer of step (d) is from about 0.005 to about 0.2, the ethylene concentration is from about 1% to about 20% by volume, or the comonomer concentration is from about 0.2% to 1% by volume. In some embodiments, the ethylene concentration is from about 3% to about 10%. In some embodiments, the remainder of the gas volume is propane or other inert gas. In some embodiments, this disclosure provides the ability to incorporate a relatively large amount of comonomer into a high molecular weight polyethylene fraction.

[0113] In some embodiments, polymer particles from the downcomer are reintroduced into the riser of step (d). In some embodiments, the comonomer concentration is reduced to a range of 0.1% to 0.5% by volume based on the total volume of gas present in the riser. In some embodiments, the comonomer content and type are controlled to obtain the desired density of the final polyethylene. In some embodiments, the riser contains a hydrogen / ethylene molar ratio of about 0.25 to about 1.9, or an ethylene concentration of about 5% to about 15% by volume, based on the total volume of gas present in the riser. In some embodiments, the remainder of the total volume of gas present in the riser is propane or other inert gas.

[0114] Example

[0115] The following embodiments are included to illustrate specific implementations of this disclosure. Those skilled in the art will understand that the techniques disclosed in the following embodiments represent techniques discovered by the inventors that work well in the practice of this disclosure, and therefore can be considered to constitute specific models of their practice. However, based on this disclosure, those skilled in the art will understand that many changes can be made to the disclosed specific embodiments without departing from the spirit and scope of this disclosure, and the same or similar results can still be obtained.

[0116] Unless otherwise stated or implied, the following experimental methods described below are used to determine the characteristic features reported in the specific implementation and examples.

[0117] density

[0118] The density was determined at 23°C according to ISO 1183.

[0119] Molecular weight distribution determined

[0120] Molecular weight distribution (MWD) and average molecular weight (number average molecular weight Mn, weight average molecular weight Mw, and z-average molecular weight Mn) z ) and polydispersity index (M w / M n The determination was made using high-temperature polymeric carbon gel permeation chromatography (GPC), also known as size exclusion chromatography (SEC). The GPC system was equipped with a filter-based infrared detector (IR5), a four-capillary differential bridge viscometer, and a Wyatt 18-angle light scattering detector.

[0121] M n Atlas, M w Atlas, M zSpectra, MWD spectra, and short-chain branching (SCB) spectra were reported using an IR detector, while the long-chain branching index g' was determined using a combination of a viscometer and an IR5 detector at 145 °C. GPC fractionation was performed using three Agilent PLgel Olexis GPC columns at 145 °C with 1,2,4-trichlorobenzene (TCB) containing 300 ppm of the antioxidant di-tert-butyl-p-cresol (BHT) as the mobile phase.

[0122] For GPC measurements, 16 mg of polymer sample was weighed into a 10 mL vial and then sealed. The dissolution process was automated for 1 hour in an Agilent autosampler at 160 °C in 8 mL TCB with continuous oscillation. To label the countercurrent, 20 µL of heptane was injected into the vial during the dissolution process. After dissolution, 200 µL of the solution was injected into the GPC column.

[0123] The GPC column was calibrated using twelve monodisperse polystyrene (PS) standards covering the range from 578 g / mol to 3,510,000 g / mol, provided by PSS. Comonomer compositions (or SCB profiles) were reported based on different calibration curves obtained using a series of relatively narrow polyethylene samples with known CH3 / 1000 total carbon values. Comonomer compositions were determined using established solution NMR techniques. Specifically, calibration was performed using polyethylene samples with 1-hexene and 1-octene comonomers (provided by Polymer Char (Paterna 46980, Valencia, Spain)) and polyethylene with 1-butene (internal synthesis). Data analysis was performed using GPC One software. The long-chain branching index g' was determined by the following equation:

[0124] g'=[η] / [η] lin

[0125] Where [η] is the average intrinsic viscosity of the polymer, which is derived by summing the slices on the GPC spectrum, as follows:

[0126]

[0127] Where c i It is the concentration of a specific slice obtained from an IR detector, and It is the intrinsic viscosity of the slice measured by a viscometer detector.

[0128] [η] lin Using the Mark-Hovink equation for linear high-density polyethylene (HDPE) ) is obtained from an IR detector, where M iThe viscosity-average molecular weight is the reference linear polyethylene. K and α are the Mark-Hovink constants for linear polymers, where K = 0.000374 and α = 0.7265 for linear polyethylene and K = 0.00041 and α = 0.6570 for linear polypropylene.

[0129] Melt Flow Index

[0130] The melt flow index is determined at 190°C under a specified load according to ISO 1133. For MI2, the load is 2.16 kg. For HLMI, the load is 21.6 kg.

[0131] Zero shear viscosity (eta0 or ,)

[0132] Zero shear viscosity (or eta0) is determined by fitting the dynamic complex viscosity to the Sabia equation for the radian frequency, as described by Shroff and Mavridis (1999) in “A long chainbranching index for essentially linear polyethyl long chain branching index for essentially linear polyethylenes” (Macromolecules, Vol. 32, pp. 8454–8464) (included in Appendix B), the disclosure of which is incorporated herein by reference in its entirety.

[0133] Long Chain Branching Index (LCBI)

[0134] Use Equation 13 to determine LCBI:

[0135]

[0136] Equation 13 and its application are described in Shroff and Mavridis’s (1999) “A long chain branching index for essentially linear polyethylenes” (Macromolecules, Vol. 32, pp. 8454-8464), the contents of which are incorporated herein by reference in their entirety.

[0137] Long-chain branching frequency (characterized as the proportion of long-chain branching per million carbon atoms, or LCB / 10) 6C) The viscosity was determined using the method of Janzen and Colby (J. Janzen and RH Colby, “Diagnosis long in polyethylenes,” *Journal of Molecular Structure*, Vol. 485-486, August 10, 1999, pp. 569-583), using equations (2-3) and constants in Table 2 from the above references. Specifically, the zero-shear viscosity at 190°C was... The weight-average molecular weight (Mw) was determined by extrapolating complex viscosity data via the Sabia equation, as described separately. The weight-average molecular weight (Mw) was determined by GPC. Using these two parameters and the methods of Janzen and Colby, the long-chain branching frequency (LCB / 10) was determined. 6 C can be numerically determined such that all three parameters (η0, M) are equal. w and LCB / 10 6 C) Satisfies equations (2-3) in the above references. The Janzen and Colby method predicts the zero-shear viscosity of the material and that of a perfectly linear polymer with the same average molecular weight (LCB / 10). 6 The ratio of zero shear viscosity (C=0) In LCB / 10 6 C exhibits its maximum value at a certain point, and therefore for LCB / 10 6 Each value of C There exist two levels or values ​​that make this ratio possible. For the purposes of this calculation, LCB / 10 6 The minimum value of C is always... Choose a given ratio.

[0138] Atomic absorption spectrometry (used for determining Mg content)

[0139] This method was used to determine residual Mg using an AAS 220FS Varian (now Agilent) spectrometer. Samples were homogeneous, and double measurements were always performed. For sample preparation, 250 mg (±0.1 mg) of sample was weighed and placed in a test tube. 6 mL of concentrated HNO3 was added to the solution, and the test tube was sealed and placed in a microwave oven (MLSStart 1500). The subsequent heating process depends on the sample form.

[0140] For microparticles: 5 minutes at 50°C. 150℃ for 15 minutes 10 minutes at 200℃ 10 minutes at 210℃

[0141] For powder: 5 minutes at 50°C. 20 minutes at 150℃ 15 minutes at 200℃ 10 minutes at 210℃

[0142] The test tube was then allowed to stand to cool to at least 60°C. The dissolved sample was transferred to a 50 mL volumetric flask, and 5 mL of lanthanum chloride solution and 50 mL of ultrapure water were added. The measurement was preferably performed at a wavelength of 285.2 nm with an absorbance in the range of 0.0100 nm to 0.3500 nm. If necessary, the sample could be further diluted to reach this range. The measurement was performed using an air / acetylene flame at flow rates of 13.5 L / min and 2 L / min, respectively. For calibration, samples with concentrations between 0.01 mg / L and 1 mg / L were prepared and measured accordingly (based on a commercial reference Mg solution).

[0143] Ti content determined

[0144] The determination of Ti residues in the polymer is performed using mass balance during the polymerization process.

[0145] Comonomer content

[0146] According to ASTM D 6248 98, the comonomer content was determined by IR using a Tensor 27 FT-IR spectrometer from Bruker. This Tensor 27 FT-IR spectrometer was calibrated with a stoichiometric model used to determine the ethyl or butyl side chains of butene or hexene as comonomers in PE. The results were compared with estimates of comonomer content derived from the mass balance of the polymerization process, and the results were found to be consistent.

[0147] swelling ratio

[0148] The expansion ratio of the studied polymer was measured at T=190°C using a Göttfert Rheotester 2000 and Rheograph 25 capillary rheometer, equipped with a commercial 30 / 2 / 2 / 20 die (total length 30 mm, effective length = 2 mm, diameter = 2 mm, L / D = 2 / 2 and 20º incident angle) and an optical device (laser diode from Göttfert) for measuring the thickness of the extruded wire. The sample was melted in the capillary tube at 190°C for 6 minutes, with a melting time of 1440 seconds at the die head. -1The obtained shear rate corresponds to the piston speed during extrusion. The extrudate is cut at a distance of 150 mm from the die exit when the piston reaches a position 96 mm from the die inlet (using an automated cutting device from Göttfert). The extrudate diameter is measured as a function of time at a distance of 78 mm from the die exit using a laser diode. The maximum value corresponds to D. 挤出物 The expansion ratio is determined by the following calculation: SR = (D 挤出物 -D 模头 100% / D 模头 D 模头 The corresponding diameter is measured at the mold head exit using a laser diode.

[0149] Notched tensile impact test

[0150] Tensile impact strength was determined using a Type 1 double-notched specimen according to Method A of ISO 8256:2004. Test specimens (4 × 10 × 80 mm) were cut from a compression-molded sheet prepared according to ISO 1872-2 requirements (average cooling rate of 15 K / min and high pressure during the cooling phase). The specimens had 45° V-shaped notches on both sides. The depth was 2 ± 0.1 mm, and the radius of curvature of the notch angle was 1.0 ± 0.05 mm. The free length between the clamps was 30 ± 2 mm. All test specimens were conditioned at -30°C for 2 to 3 hours prior to measurement. The procedure for measuring tensile impact strength, including energy correction following Method A, is described in ISO 8256.

[0151] Based on the environmental stress cracking resistance test (FNCT)

[0152] The environmental stress cracking resistance of the polymer samples was determined in an aqueous surfactant solution according to the international standard ISO 16770 (FNCT). Compression-molded 10 mm thick sheets were prepared from the polymer samples. The rods, each with a square cross-section (10 × 10 × 100 mm), were notched on four sides perpendicular to the stress direction using a razor blade. The notching device described by M. Fleissner in Kunststoffe 77 (1987), page 45, was used for sharp notches with a depth of 1.6 mm. The applied load was calculated by dividing the tensile force by the initial ligament area. The ligament area is the remaining area = total cross-sectional area of ​​the specimen minus the notch area. For FNCT specimens: 10 × 10 mm 2 -4 times the area of ​​the trapezoidal cut = 46.24 mm² 2(Remaining cross-section of the failure process / crack propagation). Test specimens were loaded under the standard conditions recommended by ISO 16770 at 80°C with a constant load of 4 MPa in a 2% (by weight) aqueous solution of the nonionic surfactant ARKOPAL N100, or at 50°C with a constant load of 6 MPa in a 2% (by weight) aqueous solution of the nonionic surfactant ARKOPAL N100. The time prior to detection of specimen fracture.

[0153] Alternatively, the environmental stress cracking resistance (“ESCR”) of the resin was measured according to ASTM-D 1693-01 Method B. According to this test, the resin’s sensitivity to mechanical failure due to cracking was measured under constant strain conditions and in the presence of an aqueous solution of Igepal CO-630 (supplied by Rhone-Poulec, NJ) as a cracking accelerator. Some measurements were performed on notched specimens in 10% by volume Igepal CO-630 maintained at 50°C. The ESCR values ​​of the resin were reported as F10 (i.e., the 10% failure time calculated from the probability plot) and F50 (i.e., the 50% failure time calculated from the probability plot). Other measurements were performed on notched specimens in 100% by volume Igepal CO-630 maintained at 50°C. The ESCR values ​​of the resin were reported as F50 (i.e., the 50% failure time calculated from the probability plot).

[0154] Shabi aCN

[0155] Fracture toughness was determined by an internal method on 10×10×80 mm test bars cut from 10 mm thick compression-molded sheets. Six of these test bars were centrally notched using a razor blade from the notching device described above for FNCT. The notch depth was 1.6 mm. The measurement was performed essentially according to the Charpy method of ISO 179-1, with modified test specimens and modified impact geometry (distance between carriers). All test specimens were conditioned to a measurement temperature of -30°C over 2 to 3 hours. The test specimens were then placed without delay on the supports of a pendulum impact tester according to ISO 179-1. The distance between the supports was 60 mm. A 2J hammer drop was triggered, with a drop angle of 160°, a pendulum length of 225 mm, and an impact velocity of 2.93 m / s. Fracture toughness values ​​are expressed in kJ / m² and are given by the quotient of the impact energy consumed and the initial cross-sectional area aCN at the notch. The values ​​for complete fracture and hinge fracture can be used here as a basis for general meaning (see recommendations of ISO 179-1).

[0156] Melt elasticity

[0157] Melt elasticity (“ER”) was determined as described by R. Shroff and H. Mavridis in “New Measures of Polydispersity from Rheological Data on PolymerMelts” (J. Applied Polymer Science, Vol. 57 (1995), p. 1605). See also U.S. Patents 7,238,754, 6,171,993, and 5,534,472 (column 10, lines 20-30), the teachings of which are incorporated herein by reference. Therefore, the storage modulus (G') and loss modulus (G”) were measured. A linear equation was fitted to log G' versus log G” using nine lowest frequency points (five points per decimal frequency) and by least-squares regression. ER was then calculated according to the following formula:

[0158] ER = (1.781 x 10 -3 ) x G',

[0159] Where G" = 5,000 dyn / cm 2 The same procedures and equations used for ER calculations are applied to both linear polyolefins and long-chain branched polyolefins.

[0160] Example 1

[0161] Process settings

[0162] In Example 1, the process of this disclosure is carried out under continuous conditions in a facility comprising two gas-phase reactors connected in series, as illustrated in the figure.

[0163] In Example 1, the solid catalyst component was prepared as follows: a magnesium chloride and alcohol adduct containing about 3 mol of alcohol was prepared according to the method described in Example 2 of U.S. Patent No. 4,399,054 (which is incorporated herein by reference), but operated at 2000 RPM instead of 10000 RPM. The adduct was heat-treated under a nitrogen stream at a temperature range of 50 to -150°C until a 25% wt% alcohol content was achieved. At about 0°C, 1 liter of TiCl4 was introduced into a 2-liter four-necked round-bottom flask purged with nitrogen. Then, at the same temperature, 70 g of a spherical MgCl2 / EtOH adduct containing 25% wt. ethanol, prepared as described above, was added with stirring. The temperature was raised to about 140°C over about 2 hours and maintained for about 60 minutes. Stirring was then stopped, the solid product was allowed to settle, and the supernatant was siphoned off.

[0164] The solid residue was then washed once with heptane at 80°C, five times with hexane at 25°C, and vacuum dried at 30°C.

[0165] polymerization

[0166] According to the method described in Example 7 of International Patent Application WO 01 / 85803 (which is incorporated herein by reference), a sufficient amount of solid catalyst component prepared according to the synthetic route reported above is prepolymerized with propylene in an amount of 1 gram of polypropylene per gram of catalyst component.

[0167] As described above, a prepolymerized solid catalyst component of 8 g / h (“g / h”) was prepared and fed into a pre-contact unit using 5 kg / h (“kg / h”) of liquid propane, in which triisobutylaluminum (TIBA) was added. The weight ratio of alkylaluminum to the solid catalyst component was 2.5:1. The pre-contact step was carried out at 25°C with stirring, wherein the total residence time was 120 min.

[0168] Referring to the accompanying drawings for illustrative purposes, the catalyst enters the first gas-phase polymerization reactor 1 via line 10. In reactor 1, at least a first amount of ethylene is polymerized using H2 as a molecular weight regulator and in the presence of propane as an inert diluent. 41.5 kg / h of ethylene and 65 g / h of hydrogen are fed to reactor 1 via line 9 after passing through compressor 2 and condenser 3. No comonomer is fed to reactor 1. In an optional embodiment, hydrogen, ethylene, and propane can be reintroduced into reactor 1 from the recirculation line 13 (shown in dashed lines, as this flow is optional) via compressor 2 and condenser 3 through line 4.

[0169] Polymerization is carried out at a temperature of 80°C and a pressure of 2.9 MPa. The operating conditions of reactor 1 are summarized in Table 1. The polymer obtained in reactor 1 is discharged discontinuously via line 11, separated from the gas and fed into gas / solid separator 12, and reintroduced into the second gas phase reactor 20 via line 14. In some embodiments of this disclosure, the gas separated from separator 12 may be introduced into reactor 1 via recirculation line 13 (shown in dashed lines because this flow is optional) or discharged from the system via line 15.

[0170] The polymer produced in the first reactor has a melt index (MI2) of approximately 10 g / 10 min and a melt flow rate of 0.966 kg / dm³. 3 The density.

[0171] The second reactor 20 is operated under polymerization conditions of approximately 84°C and 2.5 MPa pressure. 20 kg / h of ethylene, 4 g / h of hydrogen, and 2.5 kg / h of 1-hexene are introduced via line 46 into the downcomer (also referred to herein as the second polymerization zone) 33 of the second reactor 20. 5 kg / h of propane, 29 kg / h of ethylene, and 21 g / h of hydrogen are fed via line 45 into line 44 of the recirculation system. After passing through the second reactor compressor 47, the propane, ethylene, and hydrogen are distributed via line 56 to the first condenser 48 and the second condenser 49 of the second reactor.

[0172] The applicant currently believes that, in order to broaden the molecular weight distribution of the final ethylene polymer, the second reactor 20 is operated under different conditions of monomer and hydrogen concentrations within the riser (also referred to herein as the first polymerization zone) 32 and the downcomer 33. The applicant currently believes that these different conditions are achieved by feeding a liquid stream (liquid separator) of 330 kg / h into the upper part (portion) or region of the downcomer 33 via line 52. The liquid stream 52 has a different composition than the gas mixture present in the riser 32. The different concentrations of monomer and hydrogen, and the composition of the liquid separator, within the riser 32 and downcomer 33 of the second reactor 20 are shown in Table 2. The liquid stream from line 52, operating at 56°C and 2.5 MPa, originates from a condensation step in the second condenser 49 of the second reactor, where a portion of the recirculated stream is cooled via line 57 and partially condensed. As shown, the separation vessel 50 and pump 51 are positioned downstream of the second condenser 49 of the second reactor in this order. In addition, hydrogen, ethylene, and / or comonomers can be recirculated through the system via line 55, entering riser 32 or downcomer 33 via compressor 47 and condenser 48. The final polymer is discharged discontinuously via line 54.

[0173] The polymerization process in the second reactor produces a relatively high molecular weight polyethylene fraction. The characteristics of the final product are specified in Table 3. The applicant currently believes that Table 3 illustrates a decrease in the melt index of the final product compared to the ethylene resin produced in the first reactor, indicating the formation of a high molecular weight fraction in the second reactor.

[0174] The first reactor produces approximately 50% by weight (separate wt.%) of the total final polyethylene resin produced by the first and second reactors. Simultaneously, the obtained polymer exhibits a relatively broad molecular weight distribution, as indicated by an M value equal to 18.18. w / M n More than what has been confirmed.

[0175] Comparative Example 1

[0176] The polymer in Comparative Example 1 is a prior art polyethylene composition prepared in a loop reactor using a Cr catalyst.

[0177] Table 1: Operating conditions of the first reactor

[0178]

[0179] Note: H2 = hydrogen; C2H4 = ethylene;

[0180] Table 2: Operating conditions of the second reactor

[0181]

[0182] Note: H2 = hydrogen; C2H4 = ethylene; C6H 12 =Hexene

[0183] Table 3: Final polymer properties of Example 1 and Comparative Example 1

[0184]

[0185] Note: *2% Arkopal N100 aqueous solution

[0186] Although this disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions, and alterations may be made herein without departing from the spirit and scope of this disclosure as defined by the appended claims. Furthermore, the scope of this application is not intended to be limited to the specific embodiments of the processes, machines, manufactures, compositions of matter, apparatuses, methods, and steps described in the specification. As will be readily understood by one of ordinary skill in the art from the content of this disclosure, processes, machines, manufactures, compositions of matter, apparatuses, methods, or steps that are currently existing or will be developed thereafter can be used to perform substantially the same function or achieve substantially the same results as the corresponding embodiments described herein. Therefore, the appended claims are intended to include such processes, machines, manufactures, compositions of matter, apparatuses, methods, or steps within their scope.

[0187] References

[0188] The following references are specifically incorporated herein by reference to the extent that they provide exemplary procedures or other details that supplement the content presented herein: U.S. Patent 4,298,718; U.S. Patent 4,399,054; U.S. Patent 4,469,648; U.S. Patent 4,495,338; U.S. Patent 4,536,550; U.S. Patent 4,829,034; U.S. Patent 5,100,849; U.S. Patent 9,023,945; International Patent Application WO 1994 / 012568; International Patent Application WO 1998 / 044009; International Patent Application WO 2001 / 085803; International Patent Application WO 2005 / 097888; European Patent 395,083; Geldart, “Gas Fluidization Technology”, J. Wiley & Sons Publishing Co. Ltd.), p. 155, 1986.; Benoit et al., Journal of Polymer Science, physical edition, 5:753, 1967; Vittorias, “Correlation among structure, processing and product properties”, Würzburger Tage, Wolfgang Kunze TA Instruments, Germany, 2010; Wo and Tanner, “The impact of blue organic and inorganic pigments on the crystallization and rheological properties of isotactic polypropylene”, Rheol. Acta, 49:75, 2010; Derakhshandeh and Hatzikiriakos, “Flow-induced crystallization of high-density polyethylene: the effects of shear and uniaxial tension”. extension), Journal of Rheology (Rheol).Acta), 51:315-327, 2012; Rubinstein and Colby, "Polymer Physics," Oxford University Press, 2003; Zimm and Stockmayer, "The dimensions of chainmolecules containing branches and rings," Journal of Chemical Physics, 17, 1949.

Claims

1. A process for making a polyethylene composition, the process comprising the steps of: (a) providing at least a first amount of ethylene and a first amount of hydrogen to a first gas phase reactor; (b) providing at least a first amount of a Ziegler-Natta catalyst to the first gas phase reactor to produce at least a first amount of polyethylene polymer within the first gas phase reactor; (c) transferring at least a portion of the first amount of polyethylene polymer and at least a portion of the first amount of Ziegler-Natta catalyst to a second gas phase reactor; (d) providing at least a second amount of ethylene to the second gas phase reactor in the presence of a second amount of hydrogen to obtain a second polyethylene polymer, thereby producing a polyethylene composition comprising the first polyethylene polymer and the second polyethylene polymer, wherein the polyethylene composition has a density greater than about 0.946 g / cm3, an Ml2 of about 0.20 to about 0.40 g / 10 min, an Mw / Mn of about 15 to about 30, and a long chain branching index lower than about 0.

60. 3 w n ​​​ wherein at least one of the first gas phase reactor or the second gas phase reactor comprises a first polymerization zone and a second polymerization zone, the first polymerization zone having a first hydrogen pressure and the second polymerization zone having a second hydrogen pressure, wherein the first hydrogen pressure and the second hydrogen pressure are different, such that at least a portion of the second amount of ethylene moves through the first polymerization zone and the second polymerization zone, and at least a portion of the gas mixture of each polymerization zone is partially or completely prevented from entering the other zone.

2. The process of claim 1, wherein the first polymerization zone is under fast fluidization or transport conditions.

3. The process of claim 1, wherein step (a) and / or step (d) further comprises one or more comonomers.

4. The process of claim 1, wherein the first gas phase reactor and / or the second gas phase reactor further comprises polymerizing ethylene in an inert diluent.

5. The process of claim 1, wherein the first gas phase reactor and the second gas phase reactor are operated at a temperature ranging from about 70 °C to about 95 °C.

6. The process of claim 1, wherein the Ziegler-Natta catalyst comprises a solid catalyst component comprising a titanium compound on a magnesium support and an organoaluminum compound.

7. The process of claim 6, wherein the solid catalyst component is produced by contacting the titanium compound with magnesium chloride or a precursor magnesium compound and heating to a temperature ranging from about 130 °C to about 150 °C.

8. The process of claim 1, wherein the polyethylene composition comprises: (A) about 40% to about 60% by weight of an ethylene homopolymer or copolymer having a density equal to or greater than about 0.960 g / cm3and a melt flow index (Ml2) of about 5 to about 20 g / 10 min at 190°C under a load of 2.16 kilograms; and 3 (B) about 40% to about 60% by weight of an ethylene homopolymer or copolymer having a density equal to or greater than about 0.960 g / cm3and a melt flow index (Ml2) of about 5 to about 20 g / 10 min at 190°C under a load of 2.16 kilograms; and (B) from about 40% to about 60% by weight of an ethylene homopolymer or copolymer having a Ml 2 value that is lower than the Ml 2 value of (A).

9. A polyethylene composition comprising: (a) a first polyethylene produced in a first gas phase reactor in the presence of a first amount of hydrogen; and (b) a second polyethylene produced in a second gas phase reactor in the presence of a second amount of hydrogen, wherein the second amount of hydrogen is less than the first amount of hydrogen; wherein the first polyethylene and the second polyethylene are produced in any order and in the presence of a Ziegler-Natta catalyst, wherein at least one of the first gas phase reactor or the second gas phase reactor includes a first polymerization zone and a second polymerization zone, the first polymerization zone having a first hydrogen pressure and the second polymerization zone having a second hydrogen pressure, wherein the first hydrogen pressure and the second hydrogen pressure are different, such that at least a portion of the second amount of ethylene moves through the first polymerization zone and the second polymerization zone, and at least a portion of the gas mixture of each polymerization zone is partially or completely prevented from entering the other zone, and wherein the polyethylene composition further has a density greater than about 0.946 g / cm 3 0.20 to about 0.40 g / 10 min. and a long chain branching index lower than about 0.

60.

10. The polyethylene composition of claim 9, wherein the first polymerization zone is under fast fluidization or transport conditions.

11. The polyethylene composition of claim 9, wherein the first polyethylene or the second polyethylene contains one or more comonomers.

12. The polyethylene composition of claim 9, wherein the first gas phase reactor and the second gas phase reactor are operated at a temperature selected from about 70°C to about 95°C.

13. The polyethylene composition of claim 9, wherein the Ziegler-Natta catalyst includes a solid catalyst component and an organoaluminum compound, the solid catalyst component including a titanium compound on a magnesium support.

14. The polyethylene composition according to claim 9, wherein the polyethylene composition has one or more of the following properties: M equal to or less than about 210,000 g / mol w M from approximately 15 to approximately 30 w / M n The ratio is approximately 20 to approximately 40 g / 10 min of HLMI and a comonomer content equal to or less than approximately 2.2% by weight.

15. The polyethylene composition of claim 9, comprising: (A) about 40% to about 60% by weight of an ethylene homopolymer or copolymer having a density equal to or greater than about 0.960 g / cm3and a melt flow index (Ml2) of about 5 to about 20 g / 10 min at 190°C under a load of 2.16 kilograms; and 3 (B) about 40% to about 60% by weight of an ethylene homopolymer or copolymer having a density equal to or greater than about 0.960 g / cm3and a melt flow index (Ml2) of about 5 to about 20 g / 10 min at 190°C under a load of 2.16 kilograms; and (B) from about 40% to about 60% by weight of an ethylene homopolymer or copolymer having a Ml2 value that is lower than the Ml2 value of (A).

16. A polyethylene composition, comprising: (A) a density greater than about 0.946 g / cm3 3 of density; (B) M of about 15 to about 30 w / M n ratio; (C) an Ml2 of from about 0.20 to about 0.40 g / 10 min; and (D) a long chain branching index of less than about 0.

60.

17. The polyethylene composition of claim 16, further having at least one feature selected from: (A) Mw equal to or less than about 225,000 g / mole w ; (B) a zero shear viscosity (etao) of from about 150,000 to about 650,000 Pascal seconds ("Pa x s"); (C) a comonomer content equal to or less than about 2.5% by weight; (D) a melt elasticity of greater than 3.5; (E) an HLMI of from about 20 to about 40 g / 10 min; (F) a Charpy a CN (T = -30°C) of 4 or higher; and (G) a tensile notched impact (T = -30°C) of about 80 kilojoules per square meter ("kJ / m 2 ") or more.

18. The polyethylene composition of claim 16, comprising: (A) about 40% to about 60% by weight of an ethylene homopolymer or copolymer having a density equal to or greater than about 0.960 g / cm3and a melt flow index (Ml2) of about 5 to about 20 g / 10 min at 190°C under a load of 2.16 kilograms; and 3 (B) about 40% to about 60% by weight of an ethylene homopolymer or copolymer having a density equal to or greater than about 0.960 g / cm3and a melt flow index (Ml2) of about 5 to about 20 g / 10 min at 190°C under a load of 2.16 kilograms; and (B) from about 40% to about 60% by weight of an ethylene homopolymer or copolymer having a Ml2 value that is lower than the Ml2 value of (A).

19. The polyethylene composition of claim 17, wherein the Ml 2 is 0.29 g / 10 min, the density is 0.949 g / cm 3 , the LCBI is 0.56, and the M w / M n ratio is 18.

18.

20. The polyethylene composition of claim 17, further having an ESCR F10 (10% Igpal) of at least equal to or greater than about 100 hours, an ESCR F50 (10% Igpal) of equal to or greater than about 139 hours, and an ESCR F50 (100% Igpal) of greater than about 900 hours.

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