RU2821786C2 - Bimodal polyethylene copolymer composition and pipe made from said composition - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: group of inventions relates to a bimodal composition of an ethylene/1-hexene copolymer for making pipes, a method for synthesis of a bimodal composition of an ethylene/1-hexene copolymer, a pipe consisting of a bimodal composition of an ethylene/1-hexene copolymer and a method of making a pipe. Bimodal composition of an ethylene/1-hexene copolymer for making pipes consists of an ethylene/1-hexene copolymer component with a higher molecular weight (HMW component), having a molecular weight distribution from 4.05 to 4.34, a homopolymer of polyethylene with a lower molecular weight or a component of an ethylene/1-hexene copolymer with a lower molecular weight (LMW component) having a molecular weight distribution of 2.84 to 2.88; where the fractionation of the components, characterized by the weight fraction of the PMM component and the weight fraction of the LMW component, ranges from 36.9 to 49.1 wt.% and from 63.1 to 50.9 wt.%, respectively, of the total weight of the HMW and LMW components, wherein the bimodal ethylene/1-hexene copolymer composition is obtained using a combination of a bimodal catalyst system and an auxiliary catalyst in the presence of molecular hydrogen gas; wherein said bimodal catalyst system is obtained by bringing the first activator into contact with bis-(2-(pentamethylphenylamido)-ethyl)-aminozirconium dibenzyl and (methylcyclopentadienyl) (1,3-dimethyl-4,5,6,7-tetrahydroindenyl)-zirconium dimethyl, wherein said auxiliary catalyst is obtained by contacting a second activator with (methylcyclopentadienyl) (1,3-dimethyl-4,5,6,7-tetrahydroindenyl)-zirconium dimethyl; wherein the first and second activators are the same or different; and wherein the molar ratio of molecular hydrogen gas to ethylene is from 0.001 to 0.0050; and the molar ratio of 1-hexene to ethylene is from 0.00450 to 0.01000, and has density from 0.9486 to 0.9584 g per cubic centimetre (g/cm³), measured in accordance with ASTM D792-13, method B and molecular weight dispersion from 15.3 to 22.4, measured by a test method using gel permeation chromatography (GPC). Method of making the pipe includes a step for extruding the melt through an annular die, configured to form a cylinder to obtain an initial cylinder with solid walls from a bimodal composition of an ethylene/1-hexene copolymer or a step of extrusion and spiral winding of the melt around the mandrel configured to form a wall with a soldered seam, to obtain a wall with a soldered seam and soldering unsoldered seam of wall with unsoldered seam to obtain initial cylinder with walls with sealed seam.

EFFECT: providing pipes from a bimodal composition of an ethylene/1-hexene copolymer, characterized by an increased strain hardening modulus and characteristics of an accelerated creep test with a full notch.

10 cl, 4 tbl, 3 ex

Description

Technical field

Compositions of polyethylene copolymers, pipes and related methods.

State of the art

Published patent applications and patents in this or related art include US 2016/0068623 A1; US 2016/0297907 A1; WO 2016/188703 A1; WO 2017/009058 A1; WO 2017/093008 A1; WO 2017/132092 A1; EP1985660B2’ EP2285896B1; US 5,332,706; US 5,882,750; US 6 989 344 B2; US 7 078 467 B1; US 7 090 927 B2; US 7 157 531 B2; US 7 223 825 B2; US 7 300 988 B2; US 8 227 552 B2; US 8 497 329 B2; and US 9,051,458 B2.

The essence of the invention

A bimodal ethylene/1-hexene copolymer composition consisting essentially of a higher molecular weight component (HMW) and a lower molecular weight component (LMW) and melted at a temperature of 190 degrees Celsius (°C) characterized by melt properties determined by the combination of the index melt flow (5 kg), melt strength and, optionally, shear thinning properties, and, in solid form, characterized by slow cracking properties determined by a combination of strain hardening modulus and accelerated full notch creep test (ACC) characteristics ("bimodal composition ethylene/1-hexene copolymer"). The bimodal ethylene/1-hexene copolymer composition "consisting essentially of" does not contain a specific third or subsequent components when determined by gel permeation chromatography (GPC) according to the GPC test method. For example, a bimodal ethylene/1-hexene copolymer composition is not trimodal or tetramodal.

A method for synthesizing a bimodal ethylene/1-hexene copolymer composition consists essentially of polymerizing ethylene (monomer) and 1-hexene (comonomer) with one bimodal catalyst system in one gas-phase fluidized bed polymerization (GFP-PS) reactor under efficient operating conditions to produce bimodal ethylene/1-hexene copolymer composition. When indicated "essentially consisting of" the process does not contain Ziegler-Natta catalysts and chromium catalysts (containing Cr, e.g. chromium oxide catalysts), the polymerization is carried out in a single reactor (i.e., a HFP-PS reactor), and the working conditions are effective for producing a bimodal ethylene/1-hexene copolymer composition with a combination of melt flow index (5) (MFI ₅ ), melt strength, and optionally shear thinning properties and a combination of strain hardening modulus and accelerated STI properties. Effective operating conditions include reactor bed temperature, hydrogen to ethylene molar ratio (H ₂ /C ₂ ), and 1-hexene to ethylene molar ratio (C ₆ /C ₂ ). The proposed method has no special restrictions other than those indicated.

A pipe consisting essentially of a bimodal ethylene/1-hexene copolymer composition. The pipe is characterized by improved (increased) resistance to slow cracking, which is determined using the characteristics of accelerated IPP. A pipe "consisting essentially of" does not contain other polyolefin polymers, but other than that there are no special restrictions regarding its components.

A method for manufacturing a pipe, comprising the steps of melting a bimodal ethylene/1-hexene copolymer composition to form a melt of said composition; extruding the melt to form a parent pipe; optionally, changes in pipe size; and cooling the original or resized pipe. The method can be carried out using a pipe forming machine.

An industrial product containing a bimodal ethylene/1-hexene copolymer composition.

Detailed Description of the Invention

The summary and abstract are incorporated herein by reference. Some embodiments are described below in numbered aspects presented for ease of cross-referencing.

Aspect 1. A bimodal ethylene/1-hexene copolymer composition having a density of 0.945 to 0.960 grams per cubic centimeter (g/cm ³ ), measured in accordance with ASTM D792-13, Method B; molecular weight distribution ( _Mw / _Mn ), MWD, from 11.0 to 25.0, where _Mw and _Mn are measured in accordance with the gel permeation chromatography (GPC) test method; and consisting essentially of a higher molecular weight ethylene/1-hexene copolymer component (HMW component) having a molecular weight distribution (Mw/Mn) greater than 3.75 (>3.75), alternatively, from 3.76 to 10.0, alternatively, from 3.80 to 9.40 and either a lower molecular weight polyethylene homopolymer component or a lower molecular weight ethylene/1-hexene copolymer component (MMM component), wherein the MMM component has a molecular weight distribution (Mw/Mn) from 2.75 to 3.35; and having a separation according to component fractions, characterized by a mass fraction of the BMM component from 35.0 to 65.0 wt.%, alternatively, from 36.0 to 50.0 wt.%, and a mass fraction of the MMM component from 65.0 to 35, 0 wt.%, alternatively, from 64.0 to 50.0 wt.%, respectively, of the total mass of the BMM and MMM components, measured in accordance with the GPC test method; and wherein, in the molten state at a temperature of 190°C, the bimodal ethylene/1-hexene copolymer composition is characterized by the properties of (a), (b), and optionally (c): (a) melt flow index (5 kg) (MFR ₅ ) 0.15 to 0.30 grams per 10 minutes (g/10 min), (b) peak melt strength 18 to 29 centinewtons (cN) and optional (c) shear thinning index, 0.01 /100, from 96 to 125; and in solid form, the bimodal ethylene/1-hexene copolymer composition is characterized by properties (e) and (f): (e) strain hardening modulus of 50 to 75 megapascals (MPa) and (f) performance in the accelerated full-notch creep test ( IPPN) from 401 to 700.0 hours; where melt flow index (5 kg) is measured in accordance with ASTM D1238-13 (190°C, 5.0 kg), shear thinning index is measured in accordance with shear thinning index test method (190°C), peak melt strength measured for the highest peak in a graph of melt strength versus speed in the range of 10 to 50 millimeters per second (mm/s) according to the melt strength test method (described here, Göttfert Rheotens tester, 190°C), modulus strain hardening is measured in accordance with ISO 18488:2015, and the accelerated STI performance is measured in accordance with ISO 16770:2004 at 90°C and an actual stress of 5.0 MPa in 2 mass percent (wt%) lauramine oxide in water. "/" means division. Properties (a) - (c) together are the properties of the melt. In some aspects, the composition is characterized by property (c), alternatively, the specified characteristic is absent. Properties (e) and (f) are properties of the resin. A bimodal ethylene/1-hexene copolymer composition may consist essentially of a higher molecular weight ethylene/1-hexene copolymer component and a lower molecular weight polyethylene homopolymer component. The bimodal ethylene/1-hexene copolymer composition may consist essentially of a higher molecular weight ethylene/1-hexene copolymer component and a lower molecular weight ethylene/1-hexene copolymer component.

Aspect 2. The bimodal ethylene/1-hexene copolymer composition according to aspect 1 is characterized by any of the property limitations (i) to (viii): (i) the density is from 0.9450 to 0.9590 g/cm ³ , alternatively from 0 .9480 to 0.9560 g/cm ³ , alternatively, 0.9485 to 0.9585 g/cm ³ , measured in accordance with ASTM D792-13, Method B; (ii) separation into fractions of components is characterized by a mass fraction of the BMM component from 44.0 to 52.0 wt.%, alternatively, from 48 to 56.0 wt.%; and a mass fraction of the MMM component from 56.0 to 48.0 wt.%, alternatively from 52.0 to 44.0 wt.%, respectively, of the combined mass of the high and low molecular weight components, measured in accordance with the test method GPC; (iii) molecular weight distribution (Mw/Mn), MWD, is 11.0 to 23.0, alternatively 15.0 to 25, alternatively 15.0 to 22.5, where Mw and Mn are measured in accordance with the GPC test method; (iv) (a) MFI ₅ is 0.15 to 0.24 g/10 min, alternatively 0.180 to 0.30 g/10 min, alternatively 0.181 to 0.214 g/10 min, alternatively 0.181 to 0.185 g /10 min, alternatively, from 0.205 to 0.214 g/10 min; (v) (c) the shear thinning index, 0.01/100, is from 99 to 115, alternatively from 100.0 to 110.0; (vi) peak melt strength (b) is 20.0 to 28 cN, alternatively 21 to 29 cN, alternatively 22 to 28 cN, alternatively 23 to 27 cN, alternatively 24 to 26 cN; (vii) strain hardening modulus (e) ranges from 55 to 70.0 MPa; (viii) (f) the characteristics in the accelerated IPP are from 401 to 600.0 hours, alternatively, from 401 to 540 hours, alternatively, from 460 to 600 hours, alternatively, from 465 to 535 hours. Alternatively, the bimodal ethylene/1-hexene copolymer composition is characterized by a combination of two or more such restrictions in accordance with any of restrictions (ix) to (xxxviii): (ix) both (i) and (ii); (x) both (i) and (iii); (xi) both (i) and (iv); (xii) both (i) and (v); (xiii) both (i) and (vi); (xiv) both (i) and (vii); (xv) both (i) and (viii); (xvi) both (ii) and (iii); (xvii) both (ii) and (iv); (xviii) both (ii) and (v); (xix) both (ii) and (vi); (xx) both (ii) and (vii); (xxi) both (ii) and (viii); (xxii) both (iii) and (iv); (xxiii) both (iii) and (v); (xxiv) both (iii) and (vi); (xxv) both (iii) and (vii); (xxvi) both (iii) and (viii); (xxvii) both (iv) and (v); (xxviii) both (iv) and (vi); (xxix) both (iv) and (vii); (xxx) both (iv) and (viii); (xxxi) both (v) and (vi); (xxxii) both (v) and (vii); (xxxiii) both (v) and (viii); (xxxiv) both (vi) and (vii); (xxxv) both (vi) and (viii); (xxxvi) both (vii) and (viii); (xxxvii) any seven of (i) - (viii); and (xxxviii) each of (i) - (viii).

Aspect 3. The bimodal ethylene/1-hexene copolymer composition of Aspect 1 or 2 is further characterized by any of the melt property limitations (i) to (iii): (i) a high load melt flow rate of 1 to 10 g/10 min , alternatively, 4 to 10 g/10 min, alternatively, 1 to 7 g/10 min, alternatively, 5.0 to 6.0 g/10 min, when measured according to ASTM D1238-13 (190°C, 21.6 kg, PTVN or PTR ₂₁ ); (ii) the ratio of melt flow indicators PTR ₂₁ / PTR ₅ (“OPT5”) from 20 to 40, alternatively, from 26 to 40, alternatively, from 20 to 33, alternatively, from 26 to 33, where the values of PTR ₂₁ and PTR ₅ values used to calculate OPT5 are each in g/10 min and measured in accordance with ASTM D1238-13 (190°C, 21.6 kg, “PTR ₂₁ ”; and 190°C, 5.0 kg, “PTR _5” ", respectively); (iii) both (i) and (ii).

Aspect 4. The bimodal ethylene/1-hexene copolymer composition of any one of aspects 1 to 3, further characterized by any of the resin property limitations of (i) to (iv): (i) a weight average molecular weight (Mw) of 300,000 to 400 000 grams per mole (g/mol), alternatively, from 300,000 to 360,000 g/mol, alternatively, from 330,000 to 400,000 g/mol, alternatively, from 330,000.0 to 356,000 g/mol; (ii) number average molecular weight (Mn) from 10,000 to 30,000 g/mol, alternatively from 10,000 to 24,000 g/mol, alternatively from 14,000 to 30,000 g/mol, alternatively from 14,000.0 up to 24,000 g/mol; (iii) z-average molecular weight (Mz) 2,000,000 to 3,400,000 g/mol, alternatively, 2,000,000 to 3,100,000 g/mol, alternatively, 2,400,000 to 3,400,000 g/mol , alternatively, from 2,400,000 to 3,100,000 g/mol; (iv) frequency of butyl branches per 1000 carbon atoms (nbr/1000C) from 1.2 to 1.5, alternatively from 1.25 to 1.50, alternatively from 1.2 to 1.44, alternatively from 1 .27 to 1.44, when measured according to the butyl branching frequency test method; where M _w , M _n and M _z are measured according to the GPC test method. Alternatively, one of the restrictions on properties (v) to (xii): (v)both (i) and (ii); (vi) both (i) and (iii); (vii) both (i) and (iv); (viii) both (ii) and (iii); (ix) both (ii) and (iv); (x) both (iii) and (iv); (xi) any three of (i)–(iv); and (xii) all (i)–(iv).

Aspect 5. A method for synthesizing a bimodal ethylene/1-hexene copolymer composition according to any one of aspects 1-4, consisting essentially of copolymerizing ethylene (monomer) and 1-hexene (comonomer), and copolymerizing fresh ethylene and, optionally, fresh 1-hexene with a combination of a bimodal catalyst system and an auxiliary catalyst in the presence of molecular hydrogen gas (H ₂ ) and optionally an induced condensation agent (ICA) in a single polymerization reactor (for example, in a single gas-phase fluidized bed polymerization reactor (GFP-PS reactor)) under effective polymerization conditions to obtain a starting bimodal ethylene/1-hexene copolymer composition, the bimodal catalyst system being prepared by contacting the first activator with bis-(2-(pentamethylphenylamido)-ethyl)-amine zirconium dibenzyl and (methylcyclopentadienyl)(1,3-dimethyl -4,5,6,7-tetrahydroindenyl)-zirconium dimethyl; wherein the auxiliary catalyst is obtained by contacting the second activator with (methylcyclopentadienyl)(1,3-dimethyl-4,5,6,7-tetrahydroindenyl)-zirconium dimethyl; wherein the first and second activators are the same or different; and wherein effective polymerization conditions include a reaction temperature of from 90 to 110° Celsius (C), alternatively, from 98 to 107°C, alternatively, from 99 to 106°C; molar ratio of molecular hydrogen to ethylene (H ₂ /C ₂ molar ratio) from 0.001 to 0.0050, alternatively from 0.0020 to 0.0030, alternatively from 0.00220 to 0.00290; and a molar ratio of 1-hexene (“C ₆ ”) to ethylene (C ₆ /C ₂ molar ratio) from 0.00450 to 0.01000, alternatively from 0.0050 to 0.0080, alternatively from 0.0055 to 0.0075. The first activator may be an alkylaluminoxane (alkylaluminoxane), and the second activator may independently be an alkylaluminoxane or an alkylaluminum compound.

Aspect 6. The method of Aspect 5, further consisting essentially of discharging a feed bimodal ethylene/1-hexene copolymer composition from a reactor (eg, an HFP-PS reactor) to produce a discharged bimodal ethylene/1-hexene copolymer composition. In some aspects, the discharged bimodal ethylene/1-hexene copolymer composition may be purged with an inert gas (eg, N ₂ ) to remove entrapped hydrocarbons therefrom and/or treated with a stream of humidified nitrogen (N ₂ ) gas to in situ deactivate residual bimodal catalyst system contained therein to obtain a purified bimodal ethylene/1-hexene copolymer composition. In some aspects, the discharged or purified bimodal ethylene/1-hexene copolymer composition is degassed to remove volatile organic compounds therefrom to provide a degassed bimodal ethylene/1-hexene copolymer composition. In some aspects, the melt of the discharged, purified, or degassed bimodal ethylene/1-hexene copolymer composition can be treated with oxygen in an extruder to produce an oxygenated bimodal ethylene/1-hexene copolymer composition. In some aspects, the discharged, purified, degassed, or oxygenated bimodal ethylene/1-hexene copolymer composition is independently granulated to form granules (of a granular bimodal ethylene/1-hexene copolymer composition). The feed, discharged, purified, degassed, oxygenated, and granular embodiments of the bimodal ethylene/1-hexene copolymer composition are collectively referred to as a “bimodal ethylene/1-hexene copolymer composition,” which may correspond to any of aspects 1-4. The bimodal ethylene/1-hexene copolymer composition may be a virgin, discharged, purified, degassed, or granular embodiment. The method may further include the step of combining a bimodal ethylene/1-hexene copolymer composition with one or more pipe additives used in polyethylene pipes. Such combining may include melt blending one or more pipe additives with the melt of the bimodal ethylene/1-hexene copolymer composition to form a bimodal ethylene/1-hexene copolymer/additive composition. Alternatively, such combining may involve wetting or injecting one or more pipe additives into granules of the granular bimodal ethylene/1-hexene copolymer composition to form a bimodal ethylene/1-hexene copolymer/additive composition.

Aspect 7. A pipe consisting essentially of the bimodal ethylene/1-hexene copolymer composition of any one of aspects 1 to 4 (“pipe”), alternatively, of the bimodal ethylene/1-hexene copolymer/additive composition. The transitional expression "consisting essentially of" means that the pipe does not contain other polyolefin polymers, but other than that there are no special restrictions regarding its components. The pipe may be used to transport a fluid (gas and/or liquid). In some aspects, the bimodal ethylene/1-hexene copolymer composition of the pipe is not an oxygenated bimodal ethylene/1-hexene copolymer composition.

Aspect 8. A method of making a pipe, comprising a method of making a pipe, comprising the steps of (A), (B1) or (B2), optionally (C) and (D): (A) melting a bimodal ethylene/1-hexene copolymer composition to obtain melt; (B1) extruding the melt through an annular die configured to form a cylinder to produce an initial solid-walled cylinder of a bimodal ethylene/1-hexene copolymer composition, or (B2) extruding and spirally winding the melt around a mandrel configured to form a wall with an unsealed seam, to obtain a wall with an unsoldered seam, and sealing the unsoldered seam of the wall with an unsoldered seam, to obtain the original cylinder with walls with a sealed seam; (C) optionally, resizing the original solid wall cylinder or the original sealed wall cylinder to produce a resized wall cylinder of a different diameter; and (D) cooling the original solid wall cylinder, the original sealed wall cylinder, or the resized wall cylinder to produce a solid wall pipe or a sealed wall pipe, respectively. Step (B1) can be performed using a solid wall tube forming machine, and step (B2) can be done using a mandrel and a spiral wound wall forming and sealing machine. A pipe consisting essentially of the bimodal ethylene/1-hexene copolymer composition of any one of aspects 1-4 (“pipe”). The transitional expression "consisting essentially of" means that the pipe does not contain other polyolefin polymers, but other than that there are no special restrictions regarding its components.

Aspect 9. A pipe produced by the method of aspect 8 and consisting essentially of the bimodal ethylene/1-hexene copolymer composition of any of aspects 1-4 (“pipe”). A pipe "consisting essentially of" means that the pipe does not contain other polyolefin polymers, but other than that there are no special restrictions regarding its components. The pipe may exhibit improved (increased) delayed cracking. The pipe may be used to transport fluid. The pipe can be characterized as meeting the pipe industry specifications for PE100 pipe or PE100 RC pipe.

Aspect 10. An industrial product comprising a bimodal ethylene/1-hexene copolymer composition, characterized in that said industrial product is not a pipe.

The bimodal ethylene/1-hexene copolymer composition is not a physical or melt blend of two different, separately prepared copolymers, or a separately prepared copolymer and a separately prepared homopolymer. The bimodal ethylene/1-hexene copolymer composition is produced by a single reactor bimodal catalyst system process, which process advantageously produces a Mw/Mn of the BMM component higher than the Mw/Mn of the comparative BMM component produced in a staged reactor, wherein in a staged reactor The same catalyst is used to produce BMM and MMM components.

In some aspects, the bimodal ethylene/1-hexene copolymer composition may have a transition metal content, alternatively a Zr content, of less than 10 parts per million (ppm) by mass, as measured by inductively coupled plasma mass spectrometry (ICP-MS).

Definitions

Activator. A substance, other than a catalyst or one of the substrates, that increases the rate of a catalytic reaction and is not consumed in the reaction. Typically the activator contains aluminum and/or boron.

Bimodal. Two and only two modalities or modes.

Bimodal with respect to a copolymer (e.g., ethylene/1-hexene copolymer) means a composition consisting essentially of a higher molecular weight component and a lower molecular weight component, wherein the higher molecular weight component consists of a first group of polymer macromolecules produced on a first catalyst in a first reactor in a first set polymerization process conditions effective in relation to molecular weight (for example, at a first bed temperature in the reactor, a first molar gas ratio H ₂ /C ₂ , and/or a first comonomer/monomer molar ratio), and the lower molecular weight component consists of a second group of polymer macromolecules produced on a second catalyst in a second reactor under a second set of polymerization process conditions effective with respect to molecular weight (e.g., a second reactor bed temperature, a second H ₂ /C ₂ gas molar ratio, and/or a second comonomer/monomer molar ratio) , wherein at least one of the following differences is present: (a) the first catalyst differs in composition of the catalytic metal and/or ligand from the corresponding composition of the second catalyst; (b) the first reactor is different from the second reactor, or the first and second reactors are the same reactor, but the polymerization reaction to produce a higher molecular weight component is carried out for a different time than the polymerization reaction to produce a lower molecular weight component; (c) at least one of the first set of molecular weight effective polymerization process conditions is different from one of the second set of molecular weight effective polymerization process conditions. Bimodal polymer compositions include post-reactor mixtures and in-reactor mixtures (if the lower and higher molecular weight components are synthesized in the same reactor). A bimodal copolymer composition can be characterized by two peaks, separated by a noticeable local minimum distance, in a plot of dW/dLog(MM) on the y-axis versus Log(MM) on the x-axis to obtain a gel permeation chromatograph (GPC) chromatogram. where Log(MM) and dW/dLog(MM) are as described herein and measured by the gel permeation chromatograph (GPC) test method described herein.

Bimodal, with respect to a catalyst system, means a catalyst system that contains two different catalysts for catalyzing the same polymerization process (eg, olefin polymerization) and producing a bimodal polymer composition. Two catalysts are different if they differ from each other in at least one of the following characteristics: (a) their catalyst metals are different (Ti and Zr, Zr and Hf, Ti and Hf; non-activator metals such as Al); (b) one catalyst has a functional ligand covalently bound to its catalytic metal, and the other catalyst has no functional ligands bound to its catalytic metal; (b) both catalysts have functional ligands covalently bound to their catalyst metal, and the structure of at least one functional ligand of one of the catalysts is different from the structure of each of the functional ligands of the other catalyst (for example, cyclopentadienyl and propylcyclopentadienyl or butylcyclopentadienyl and ((pentamethylphenylamido)- ethyl)-amine); and (d) for catalysts supported on a support material, the compositions of the support materials are different. Functional ligands do not include leaving groups X, described below. The two catalysts of a bimodal catalyst system can be supported on the same support material, or on the same particles of the same support material, or on different particles of the same support material. If the same catalyst is used in terms of catalytic metal and ligands, with part of it supported on a support material and another part of it dissolved in an inert solvent, the two parts do not themselves form a bimodal catalyst system.

Catalyst. A material that increases the rate of a reaction (for example, the polymerization of ethylene and 1-hexene) and which is not completely consumed in the reaction.

Catalytic system. A combination of the catalyst itself and an auxiliary material, such as a modifier compound to reduce the reactivity of the catalyst, a support material on which the catalyst is applied, a support material in which the catalyst is located, or a combination of two or more of these, or a product of their interaction.

Consisting essentially of, consists essentially of, etc. Expressions with partially included boundary values that exclude everything that affects the basic and new characteristics of what they describe, but allow everything else. In some aspects, any of the expressions, alternatively each of the expressions "comprising" or "comprises" may be replaced by the expression "consisting essentially of" or "consisting essentially of", respectively; alternatively to the expression "consisting of" or "consists of", respectively.

Consisting of and consisting of. Restricted expressions, which exclude anything not specifically described by the restrictions modifying them. In some aspects, any of the expressions, alternatively each of the expressions "consisting essentially of" or "consisting essentially of" may be replaced by the expression "consisting of" or "consists of", respectively.

Dry. Typically the moisture content is from 0 to less than 5 ppm based on the total parts by weight. The materials fed to the reactor(s) during the polymerization reaction are dry.

Loading. The amount of reactant or reagent added or "loaded" into the reactor. In a continuous polymerization mode, each batch can independently be continuous or batch. The amount or "load" can be measured, for example, by dosing, to control the amount and relative amounts of various reactants and reagents in the reactor at any given time.

Loading line. The design of a pipeline or pipe for transporting raw materials.

Inert. Generally not (noticeably) reactive or (significantly) not affecting the polymerization reaction of the present invention. The term "inert" as used in relation to a purge gas or ethylene feedstock means a molecular oxygen (O ₂ ) content of from 0 to less than 5 ppm, based on the total parts by weight of the purge gas or ethylene feedstock.

Metallocene catalyst. A homogeneous or heterogeneous material that contains a cyclopentadienyl ligand-metal complex and increases the rate of olefin polymerization reaction. Essentially single-center or two-center. Each metal is a transition metal Ti, Zr or Hf. Each cyclopentadienyl ligand is independently an unsubstituted cyclopentadienyl group or a hydrocarbon-substituted cyclopentadienyl group. In some aspects, the metallocene catalyst has two cyclopentadienyl ligands, and at least one, alternatively both, cyclopentadienyl ligands are independently a hydrocarbon-substituted cyclopentadienyl group. Each hydrocarbon-substituted cyclopentadienyl group may independently contain 1, 2, 3, 4 or 5 hydrocarbon substituents. Each hydrocarbon substituent may independently be (C ₁ -C ₄ )alkyl. Two or more substituents can be bonded together to form a divalent substituent, which can form a ring with the carbon atoms of the cyclopentadienyl group.

Auxiliary catalyst. An amount of a metallocene catalyst that is identical, except for Group X, as described below, to the metallocene catalyst of the bimodal catalyst system. The auxiliary catalyst is usually loaded (for example, into a HFP-PS reactor) in the form of a solution of the catalyst dissolved in an inert liquid (in a non-polar aprotic, for example, hydrocarbon solvent). The co-catalyst is used with the bimodal catalyst system to modify at least one property of the copolymer produced therefrom. Examples of such at least one property are density, melt flow index MTR ₂ , melt flow index MTR ₂₁ , melt flow ratio (MFR ₂₁ /MTR ₂ ) and molecular weight distribution (M _w /M _n ), MWD.

Ziegler-Natta catalysts. Heterogeneous materials that increase the rate of olefin polymerization reaction and are prepared by contacting inorganic titanium compounds, such as magnesium chloride-supported titanium halides, with an activator.

Reactor and polymerization method

An exemplary process for a pilot plant for producing a bimodal ethylene/1-hexene copolymer uses a gas-phase fluidized bed polymerization reactor ("GFP-PS reactor") having a reaction zone size of 304.8 mm (twelve inches) inside diameter and a side wall height of 2 .4384 meters (8 feet) containing a fluidized bed of pellets of a bimodal ethylene/1-hexene copolymer composition. The GFP-PS reactor design has a gas recycle line for the flow of recirculation gas flow. The GFP-PS reactor is equipped with openings for gas supply and an opening for unloading the polymer product. Gaseous feed streams of ethylene and hydrogen along with a comonomer (eg, 1-hexene) are introduced under the HFP-PS reactor bed into the recycle gas supply line.

Polymerization operating conditions are any variable or combination of variables that can affect the polymerization reaction in the HFP reactor or the composition or properties of the bimodal ethylene/1-hexene copolymer composition product produced by the polymerization. Variables may include reactor design and size, catalyst composition and amount; composition and quantity of reagents; molar ratio of two different reagents; presence or absence of feed gases such as H ₂ and/or O ₂ , molar ratio of feed gases to reactants, absence or concentration of interfering materials (e.g. H ₂ O), absence or presence of induced condensation agent (ICA), average residence time polymer in the reactor, partial pressures of components, loading rates of monomers, bed temperature in the reactor (for example, fluidized bed temperature), nature or sequence of process steps, time intervals for transition between stages. Variables other than those described or modified in the proposed method or application may be held constant.

When implementing the proposed polymerization method, the individual consumption of ethylene (“ _C2 ”), hydrogen (“ _H2 ”) and 1-hexene (“ _C6 ” or “ _Cx ”, where x is 6) is regulated to maintain a fixed molar ratio of comonomer to gaseous ethylene monomer (C _x /C ₂ , e.g. C ₆ /C ₂ ), equal to the described value (e.g. 0.00560 or 0.00703), a constant molar ratio of hydrogen to ethylene gas ("H ₂ /C ₂ ") , equal to the described value (eg 0.00229 or 0.00280), and a constant partial pressure of ethylene ("C ₂ ") equal to the described value, eg 1000 kPa). Gas concentrations are measured using an in-line gas chromatograph to determine and maintain the composition of the recirculating gas stream. The reaction bed of growing polymer particles is maintained in a fluidized state by continuously passing feedstock and recycle gas through the reaction zone. A surface gas flow velocity of 0.49 to 0.67 meters per second (m/s) (1.6 to 2.2 feet per second (ft/s)) is used. Operate the HFP-PS reactor at a total pressure of about 2344 to about 2413 kilopascals (kPa) (about 340 to about 350 pounds per square inch gauge (psig)) and at the described first bed temperature in the TCP reactor . Maintain a constant height of the fluidized bed by discharging a portion of the bed at a rate equal to the particle production rate of the bimodal ethylene/1-hexene copolymer composition, and said production rate may be from 10 to 20 kilograms per hour (kg/h), alternatively from 13 to 18 kg/h. The product, a bimodal ethylene/1-hexene copolymer composition, is discharged semi-continuously through a series of valves into a constant volume chamber where the discharged bimodal ethylene/1-hexene copolymer composition is purged to remove entrapped hydrocarbons and treated with a stream of humidified nitrogen gas (N ₂ ) to deactivate trace amounts. amounts of residual catalyst. See the polymerization method described herein.

The bimodal catalyst system can be loaded into the polymerization reactor(s) in a "dry process" or a "wet process", alternatively a dry process, alternatively a wet process. The dry method involves dry powder or granules. The wet method involves suspension in an inert liquid such as mineral oil.

Induced Condensation Agent (ICA). An inert liquid suitable for cooling materials in polymerization reactor(s) (eg, fluidized bed reactor); its use is optional. ICA may be a (C ₅ -C ₂₀ )alkane, alternatively a (C ₁₁ -C ₂₀ )alkane, alternatively a (C ₅ -C ₁₀ )alkane, alternatively a (C ₅ )alkane, for example pentane or 2-methylbutane; hexane; heptane; octane; nonane; dean; or a combination of any two or more of these compounds. ICA may be 2-methylbutane (ie isopentane). Aspects and methods of polymerization that utilize ICA may be referred to as constituting induced condensation (ICC) operation. RIC is described in US 4453399; US 4588790; US 4994534; US 5352749; US 5462999; and US 6,489,408. The concentration of ICA in the gas phase is measured using gas chromatography by calibrating peak area percentage to molar percentage (mol %) using a standard gas mixture with known concentrations of the corresponding gas phase components. The concentration of ICA can be from 1 to 10 mol%, alternatively from 3 to 8 mol%.

The proposed polymerization method uses a gas-phase polymerization reactor (GFP), such as a gas-phase stirred-fluidized-bed polymerization reactor (GFP-PSP reactor) or a gas-phase fluidized-bed polymerization reactor (GFP-PS reactor), to produce a bimodal ethylene/1 copolymer composition -hexene. Such reactors and methods are generally well known in the art. For example, the HFP-PS reactor/process may be as described in US 3,709,853; US 4003712; US 4011382; US 4302566; US 4543399; US 4882400; US 5352749; US 5541270; EP-A-0 802 202; and in Belgian patent No. 839,380. These HFP-PSP and HFP-PS reactors and processes provide mechanical stirring or fluidization of the polymerization medium in the reactor, respectively, by continuously passing monomer gas and diluent. Other suitable reactors/methods contemplated include batch or multi-stage polymerization processes such as those described in US Pat. No. 5,627,242; US 5665818; US 5677375; EP-A-0 794 200; EP-B1-0 649 992; EP-A-0 802 202; and EP-B-634421.

The polymerization conditions may further include the use of one or more additives, such as a chain transfer agent or a promoter. Chain transfer agents are generally known and may be alkyl metals such as diethyl zinc. Promoters are known, such as those described in US Pat. No. 4,988,783, and may include chloroform, CFCl ₃ , trichloroethane and difluorotetrachloroethane. Before starting the reactor, a neutralizing agent can be used to react with moisture, and during reactor switching, a neutralizing agent can be used to react with excess activator. The neutralizing agent may be trialkylaluminum. Gas-phase polymerization can be carried out without neutralizing agents (without special addition). The polymerization conditions for the gas phase reactor/polymerization process may further include a specified amount (e.g., 0.5 to 200 ppm based on total reactor feed) of a static control agent and/or a stability additive such as stearate aluminum or polyethyleneimine. A static charge control agent can be added to the HFP-PS reactor to suppress the formation or accumulation of static charge therein.

Starting or restarting a HFP reactor can be illustrated with a fluidized bed HFP reactor. The restart of the HFP-PS reactor upon recommissioning (cold start) or the restart of the HFP-PS transition reactor (hot start) includes the period of time until equilibrium polymerization conditions are reached in step (a). Startup or restart may involve the use of a polymer seed bed preloaded or loaded, respectively, into the fluidized bed reactor. The polymer seed layer may consist of a polyethylene powder, such as a polyethylene homopolymer, or a pre-formulated batch of a bimodal ethylene/1-hexene copolymer composition.

Starting or restarting a HFP-PS reactor may also involve changing the gas atmosphere, including purge of air or other unwanted gas(s) from the reactor using a dry (anhydrous) inert purge gas, followed by purge of the HFP-PS reactor from the dry inert purge gas with using dry ethylene gas. The dry inert purge gas may consist essentially of molecular nitrogen (N ₂ ), argon, helium, or a mixture of any two or more of these gases. In the shutdown state, before startup (cold start), the GFP-PS reactor contains an air atmosphere. The dry inert purge gas can be used to displace air from the HFP-PS reactor during recommissioning during the early stages of startup, resulting in a HFP-PS reactor containing an atmosphere consisting of the dry inert purge gas. Before restarting (for example, after replacing the seed bed), the HFP-PS transition reactor may contain an atmosphere of unwanted ICA or other unwanted gas or vapor. The dry inert purge gas can be used to displace unwanted vapor or gas from the HFP-PS transition reactor during the early stages of restart to produce a HFP-PS reactor containing an atmosphere consisting of the dry inert purge gas. The dry inert purge gas can be displaced from the HFP-PS reactor with dry ethylene gas. The dry ethylene gas may further contain molecular hydrogen gas, so that the dry ethylene gas is supplied to the fluidized bed reactor as a mixture with hydrogen. Alternatively, dry molecular hydrogen gas can be introduced separately and after replacing the atmosphere in the fluidized bed reactor with ethylene. The replacement of the gaseous atmosphere can be carried out before, during or after heating the HFP-PS reactor to the reaction temperature under the specific polymerization conditions.

Starting up or restarting a HFP-PS reactor also involves feeding it with raw materials and reagents. Reagents include ethylene and alpha-olefin (eg, 1-hexene). The reactants fed to the fluidized bed reactor include molecular hydrogen gas and induced condensation agent (ICA), as well as a bimodal catalyst system and an auxiliary catalyst.

In one embodiment of the proposed method, a pilot scale gas phase fluidized bed polymerization reactor (pilot reactor) is used, which contains a reaction vessel containing a fluidized bed of bimodal ethylene/1-hexene copolymer composition powder and a distribution plate located above the base of the bottom, which defines the bottom opening to supply gas, and has an expanded section or cyclone system at the top of the reaction vessel to reduce the amount of fine resin particles that may escape from the fluidized bed. The expanded section forms an opening for the gas to escape. The pilot-scale reactor further comprises a compressor blower of sufficient power to continuously circulate or move gas from a gas outlet in an expanded section at the top of the reaction vessel down into a lower gas inlet of the pilot-scale reactor and through the distribution plate and fluidized bed. The pilot-scale reactor additionally contains a cooling system to remove polymerization heat and maintain a given temperature of the fluidized bed. The composition of gases such as ethylene, alpha-olefin (eg, 1-hexene) and hydrogen fed to the pilot scale reactor is monitored using an integrated gas chromatograph in the recycle loop to maintain specific concentrations that determine and enable control of polymer properties. The bimodal catalyst system can be fed into a pilot scale reactor in the form of a slurry or dry powder using high pressure devices, with the slurry being fed through a syringe pump and the dry powder being fed through a metering disc. The bimodal catalyst system typically enters the fluidized bed at the bottom 1/3 of the height of said bed. The pilot scale reactor further includes a fluidized bed weighing device and a discharge port (product discharge system) for discharging the bimodal ethylene/1-hexene copolymer composition powder from the reaction vessel in response to an increase in the mass of the fluidized bed as the polymerization reaction proceeds.

In some embodiments, the HFP-PS reactor is a commercial reactor, such as a UNIPOL™ reactor or a UNIPOL™ II reactor, available commercially from Univation Technologies, LLC, a division of The Dow Chemical Company, Midland, Michigan, USA.

Catalysts, support materials, activators

The bimodal catalyst system used in the proposed synthesis method may consist essentially of a metallocene catalyst and a non-metallocene molecular catalyst that differ in functional ligand and/or catalyst metal M. The bimodal catalyst system can also consist essentially of a solid support material and/or at least one activator, and/or at least one type of activator, which is a by-product of the reaction of a metallocene catalyst or a non-metallocene molecular catalyst with the first activator. The metallocene catalyst of the bimodal catalyst system may be (methylcyclopentadienyl)(1,3-dimethyl-4,5,6,7-tetrahydroindenyl)-zirconium dimethyl, and the non-metallocene molecular catalyst of the bimodal catalyst system may be bis-(2-(pentamethylphenylamido) -ethyl)-amine zirconium dibenzyl.

Without being limited by theory, it is believed that bis-(2-(pentamethylphenylamido)-ethyl)-amine zirconium dibenzyl is effective for preparing the BMM component of a bimodal ethylene/1-hexene copolymer composition, and (methylcyclopentadienyl)(1,3-dimethyl-4,5 ,6,7-tetrahydroindenyl)-zirconium dimethyl is effective for producing the MMM component of a bimodal ethylene/1-hexene copolymer composition. The molar ratio of said catalysts in a bimodal catalyst system may be based on the molar ratio of their respective catalytic metal atoms (M, eg Zr), which can be calculated from the weight of their ingredients or measured analytically.

Before being brought into contact with the activator, the catalysts of the bimodal catalyst system can be spray-dried onto a solid support material. The solid support material may be uncalcined or calcined before being brought into contact with the catalysts. The solid support material may be a hydrophobic fumed silica (eg, dimethyldichlorosilane treated fumed silica). The bimodal catalyst system (unsupported or supported) may be in the form of a powdery, free-flowing solid.

Substrate material. The support material may be an inorganic oxide based material. The terms "substrate" and "support material" as used herein are the same and refer to a porous inorganic substance or an organic substance. In some embodiments, the desired support materials may be inorganic oxides that include oxides of Group 2, 3, 4, 5, 13, or 14 atoms, alternatively, Group 13 or 14 atoms. Examples of inorganic oxide type support materials are silica, alumina, titanium dioxide, zirconium oxide, thorium oxide, and mixtures of any two or more of these inorganic oxides. Examples of such mixtures are silicon chromium oxide, silicon alumina and silicon titanium oxide.

The inorganic oxide support material is porous and has variable surface area, pore volume and average particle size. In some embodiments, the surface area is from 50 to 1000 square meters per gram (m ² /g) and the average particle size is from 20 to 300 micrometers (μm). Alternatively, the pore volume is from 0.5 to 6.0 cubic centimeters per gram (cm ³ /g), and the surface area is from 200 to 600 m ² /g. Alternatively, the pore volume is from 1.1 to 1.8 cm ³ /g, and the surface area is from 245 to 375 m ² /g. Alternatively, the pore volume is from 2.4 to 3.7 cm ³ /g, and the surface area is from 410 to 620 m ² /g. Alternatively, the pore volume is from 0.9 to 1.4 cm ³ /g, and the surface area is from 390 to 590 m ² /g. Each of the above properties is measured using standard techniques known in the art.

The support material may comprise silica, alternatively amorphous silica (not quartz), alternatively high surface area amorphous silica (eg, 500 to 1000 m ² /g). Such silicas are commercially available from a variety of sources, including the Davison Chemical Division of W.R. Grace and Company (eg, Davison 952 and Davison 955 products) and PQ Corporation (eg, ES70 product). The silica may be in the form of spherical particles, which are obtained by spray drying. Alternatively, MS3050 is a silica product from PQ Corporation that has not been spray dried. When sold, all silicon dioxides listed are not calcined (i.e., they are not dehydrated). Silicon dioxide, calcined before purchase, can also be used as a substrate material.

Before contacting the catalyst, the support material may be pre-treated by heating the support material in air to produce a calcined support material. Preheating includes heating the substrate material at a peak temperature of from 350 to 850°C, alternatively from 400 to 800°C, alternatively from 400 to 700°C, alternatively from 500 to 650°C and for a period of time from 2 to 24 hours, alternatively 4 to 16 hours, alternatively 8 to 12 hours, alternatively 1 to 4 hours, producing a calcined substrate material. In some aspects, the support material is a calcined support material.

The co-catalyst may be any of the aforementioned metallocene catalysts. For convenience, the auxiliary catalyst is loaded in solution in a hydrocarbon solvent (for example, mineral oil or heptane). The hydrocarbon solvent may be an alkane or a mixture of alkanes, where each alkane independently contains from 5 to 20 carbon atoms, alternatively from 5 to 12 carbon atoms, alternatively from 5 to 10 carbon atoms. Each alkane can independently be acyclic or cyclic. Each acyclic alkane may independently be straight-chain or branched. The acyclic alkane may be pentane, 1-methylbutane (isopentane), hexane, 1-methylpentane (isohexane), heptane, 1-methylhexane (isoheptane), octane, nonane, decane, or a mixture of any two or more of these. The cyclic alkane may be cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, methylcyclopentane, methylcyclohexane, dimethylcyclopentane, or a mixture of any two or more of these compounds.

To provide solubility in a hydrocarbon solvent, typically each co-catalyst group X is independently a hydrocarbon group (eg, benzyl, (C ₁ -C ₅ )alkyl or (C ₂ -C ₅ )alkenyl; eg, methyl or ethyl) or -CH ₂ Si(CH ₃ ) ₃ . The X groups of the co-catalyst may be different from the X groups of the metallocene catalyst in the bimodal catalyst system. However, when activated by contacting it with an activator, the active catalyst species resulting from the activation of the auxiliary catalyst are substantially the same as the active catalyst species resulting from the activation of the metallocene catalyst of the bimodal catalyst system. For example, the metallocene catalyst of a bimodal catalyst system may be (methylcyclopentadienyl)(1,3-dimethyl-4,5,6,7-tetrahydroindenyl)-zirconium dimethyl (each X is Cl), and the co-catalyst may be (methylcyclopentadienyl) (1,3-dimethyl-4,5,6,7-tetrahydroindenyl)-zirconium dialkyl (e.g. dimethyl, where X is CH3). When activated by treatment with an appropriate activator or cocatalyst, both (methylcyclopentadienyl)(1,3-dimethyl-4,5,6,7-tetrahydroindenyl)-zirconium dichloride, and (methylcyclopentadienyl)(1,3-dimethyl-4,5,6 ,7-Tetrahydroindenyl)-zirconium dimethyl effectively form the same activated catalytic species.

Activator. Each catalyst of the bimodal catalyst system is activated by contacting it with a first activator. The auxiliary catalyst is activated by bringing it into contact with a second activator. Additional activators can be used. Any activator may be the same or different, and may independently be a Lewis acid, a non-coordinating ionic activator or an ionizing activator, or a Lewis base, an alkylaluminum or an alkylaluminoxane (alkylaluminoxane). The alkyl aluminum may be a trialkyl aluminum, a trialkyl aluminum halide, or an alkyl aluminum alkoxide (diethylaluminum ethoxide). The trialkylaluminum may be trimethylaluminum, triethylaluminum (“TEAI”), tripropylaluminum, or tris-(2-methylpropyl)aluminum. The alkyl aluminum halide may be diethylaluminum chloride. The alkyl aluminum alkoxide may be diethylaluminum ethoxide. The alkylaluminoxane may be methylaluminoxane (MAO), ethylaluminoxane, 2-methylpropylaluminoxane, or modified methylaluminoxane (MMAO). Each alkyl of an aluminum alkyl or alkylaluminoxane may independently be a (C ₁ -C ₇ )alkyl, alternatively a (C ₁ -C ₆ )alkyl, alternatively a (C ₁ -C ₄ )alkyl. The molar ratio of the activator metal (Al) to the metal of the particular catalyst compound (catalytic metal, e.g. Zr) may be from 1000:1 to 0.5:1, alternatively from 300:1 to 1:1, alternatively from 150:1 up to 1:1. Suitable activators are commercially available.

After bringing into contact the first activator and bis-(2-(pentamethylphenylamido)-ethyl)-amine zirconium dibenzyl and methylcyclopentadienyl)(1,3-dimethyl-4,5,6,7-tetrahydroindenyl)-zirconium dimethyl of the bimodal catalytic system, the catalysts of the bimodal catalytic system the systems become activated and the first activator particles can be produced in situ. After bringing the second activator and the auxiliary catalyst (methylcyclopentadienyl)(1,3-dimethyl-4,5,6,7-tetrahydroindenyl)-zirconium dialkyl into contact, the auxiliary catalyst becomes activated and the second activator particles can be produced in situ. The activator particles may have a different structure or composition than the activator from which they are derived and may be a by-product of catalyst activation or may be a derivative of said by-product. Suitable activator species may be a derivative of a Lewis acid, a non-coordinating ionic activator, an ionizing activator, a Lewis base, an alkylaluminum or an alkylaluminoxane, respectively. An example of a derivative by-product is methylaluminoxane particles, which are formed as a result of evaporation during spray drying of a bimodal catalyst system derived from methylaluminoxane.

Each contacting step between activator and catalyst may independently be carried out (a) in a separate vessel outside the HFP reactor (e.g., outside the HFP-PS reactor), (b) in the feed line to the HFP reactor, and/or (c) within the reactor HFP (in situ). In option (a), the bimodal catalyst system, after activation of its catalysts, can be loaded into the HFP reactor in the form of a dry powder, alternatively, in the form of a suspension in a non-polar aprotic (hydrocarbon) solvent. In option (c), the bimodal catalyst system can be loaded into the reactor prior to activation via the first feed line, the first activator can be introduced into the reactor via the second feed line, the auxiliary catalyst can be introduced into the reactor via the third feed line, and the second activator can be introduced into the reactor via the fourth feed line. loading lines. Any two of the first through fourth loading lines may be the same line or may be different. The activator(s) may be supplied to the reactor "wet process" in the form of a solution thereof in an inert liquid such as mineral oil or toluene, "slurry process" in the form of a suspension, or "dry process" in the form of a powder. Each contacting step may be performed in separate vessels, feed lines or reactors at the same or different times, or in the same vessel, feed line or reactor at different times, to provide the bimodal catalyst system and the auxiliary catalyst separately. Alternatively, the contacting steps can be performed in a single vessel, feed line, or reactor at the same time to produce a mixture of the bimodal catalyst system and the co-catalyst in situ.

Bimodal ethylene/1-hexene copolymer composition

Ethylene. Monomer of the formula H ₂ C=CH ₂ .

1-Hexene. Monomer of the formula H ₂ C=C(H)CH ₂ CH ₂ CH ₂ CH ₃ .

An ethylene/1-hexene copolymer or poly(ethylene/1-hexene) copolymer is a macromolecule comprising, alternatively, essentially consisting of, alternatively consisting of, constituent units derived from an ethylene monomer and constituent units derived from a 1- comonomer. hexene. Consisting essentially of means that the macromolecule does not contain constituent units that are not derivatives of ethylene or 1-hexene. Consisting of means that the macromolecule does not contain constituent units that are not derivatives of ethylene or 1-hexene, and consists only of carbon and hydrogen atoms.

Bimodal ethylene/1-hexene copolymer composition. Macromolecule or collection of macromolecules consisting of repeating units, where from 50.0 to 100 mole percent (mol.%), alternatively, from 70.0 to 99.99 mol.%, alternatively, from 95.0 to 99.9% they say of such repeating units are derived from ethylene monomer, and from >0 to 50.0 mol.%, alternatively from 0.01 to 30.0 mol.%, alternatively from 0.1 to 5.0 mol.%. the remaining repeating units are comonomer units derived from 1-hexene; or a collection of such macromolecules. The specified set of macromolecules is characterized by two separate peaks (not shoulders) on the diagram of dW/dLog(MM) along the y-axis versus Log(MM) along the x-axis, to obtain a chromatogram from a gel permeation chromatograph (GPC), where Log(MM) and dW/ dLog(MM) are as described below and measured by the gel permeation chromatograph (GPC) test method described herein.

The bimodal ethylene/1-hexene copolymer is a high molecular weight polyethylene (HMWHDPE). The bimodal ethylene/1-hexene copolymer composition may be further characterized by one of the following limitations: weight average molecular weight ( _Mw ) from 200,000.0 to 400,000.0 grams per mole (g/mol), alternatively from 250,000.0 up to 320,000.0 g/mol; number average molecular weight ( _Mn ) from 6,000.0 to 11,000.0 g/mol, alternatively from 7,000.0 to 9,000.0 g/mol; z-average molecular weight (M _z ) from 1,200,000.0 to 2,500,000.0 g/mol; a combination of any two of them; and a combination of all three of them; All parameters are measured according to the Gel Permeation Chromatography (GPC) test method.

The bimodal ethylene/1-hexene copolymer composition, pipe, and methods for producing the same do not include the metals Ti and Cr.

The polymerization conditions in the proposed synthesis method are effective for producing a bimodal ethylene/1-hexene copolymer composition characterized by the melt region described above and optionally the specified resin properties and/or pipe properties.

Pipe

Pipe. A cylindrical wall or tube having proximal and distal ends (openings) and defining a volumetric space between them through which fluid (gas, vapor or liquid) or solid particles can be transported. The wall of a pipe is determined by its thickness, and the size of the pipe is determined by its outer diameter and length. Changing the pipe size means changing the outside diameter of the pipe. The pipe wall can have any shape, including smooth, rough, round, ovoid, variable thickness or constant thickness. The pipe can be straight, curved or curved. The volumetric space or capacity of a pipe is determined by its internal diameter and length. The pipe may be a solid wall pipe or a sealed wall pipe, depending on whether the pipe is made by (i) extruding the melt through a ring die or (ii) extruding and spirally winding the melt onto a mandrel configured to form a profile with an unsoldered seam, and sealed seam, respectively. Solid wall pipe can be manufactured with an outer diameter ranging from 1.2 to 160 centimeters (cm). A sealed-wall pipe can have an outer diameter of up to approximately 3 meters.

The pipe may optionally contain zero, one or more pipe additives. A "pipe additive" is a compound or material, other than a polyolefin polymer, that imparts one or more properties and/or enhances one or more properties of a pipe. Examples of pipe additives include antimicrobial agents, antioxidants, catalyst neutralizers (single-site catalysts), coloring agents, and light stabilizers. The pipe additive(s), if present, may be premixed with the bimodal ethylene/1-hexene copolymer composition prior to the melting step of the pipe manufacturing process. Alternatively, the pipe additive(s) may be added to the melt of the bimodal ethylene/1-hexene copolymer composition during or after the melting step and before the extrusion step in the pipe making process. When two or more pipe additives are used, one or more pipe additives may be premixed with the bimodal ethylene/1-hexene copolymer composition prior to the melting step in the pipe making process, and one or more pipe additives may be added to the melt of the bimodal composition ethylene/1-hexene copolymer during or after the melting step and before the extrusion step in the pipe production process. In some aspects, the pipe consists essentially of a bimodal ethylene/1-hexene copolymer, at least one antioxidant, and at least one catalyst scavenger.

The pipe is suitable for transporting fluids. Examples of such fluids are natural gas, crude oil, refined petroleum products, ethylene, alpha-olefins, water (cold or hot), aqueous mixtures of solutes. The pipe can be used in housing construction, infrastructure, construction, industrial plant construction and pipelines for transporting hydrocarbons.

The pipe can be described as having the properties necessary to meet ISO requirements for PE100 and/or PE100 RC pipes. The "RC" in PE100 RC stands for crack resistance. ISO requirements for PE100 pipes are specified in ISO 4427 for water pipes and ISO 4437 for gas pipes. Requirements for PE100 RC pipes are specified in PAS1075.

The term “alternatively” precedes a particular embodiment. ASTM stands for Standards Organization, ASTM International, West Conshohocken, Pennsylvania, USA. Any comparative examples used are for illustration purposes only and do not constitute prior art. “Does not contain” or “without” means complete absence; alternatively, no detectable amount. ISO is the International Organization for Standardization, Chemin de Blandonnet 8, CP 401 - 1214 Vernier, Geneva, Switzerland. IUPAC represents the International Union of Pure and Applied Chemistry (IUPAC Secretariat, Science Triangle, North Carolina, USA). "May" means a valid choice, not a required condition. "Functional" means functionally capable or effective. Optional means absent (or excluded), alternatively present (or included). PAS is a publicly available specification, Deutsches Institut für Normunng e.V. Properties can be measured using standard test methods and conditions. Ranges include endpoints, subranges, and the integer and/or fractional values contained within them, except for the integer range, which does not include fractional values. Room temperature: 23°C ± 1°C.

Examples

Accelerated Full Notch Creep Test Method: Measured in accordance with ISO 16770: 2004 at 90°C, determined at an actual stress of 5.0 MPa in a 2 wt.% solution of lauramine oxide in water. ISO 16770:2004 (last revised and reaffirmed 2014), Plastics - Determination of environmental stress cracking (ESC) of polyethylene - Full notch creep test (FNCT). 2 wt.% lauramine oxide in water can be obtained by diluting with water Dehyton PL, which is an aqueous solution of 25.0 to 50.0 wt.% lauramine oxide and sold by BASF.

Bimodality Test Method: Determine the presence or absence of resolved bimodality by plotting dWf/dLogM (mass detector data) y-axis against LogM x-axis to produce a GPC chromatogram curve containing the local maximum log(MM) values for the MMM and BMM component peaks polyethylene, and observing the presence or absence of a local minimum between the indicated peaks of the MMM and BMM components of polyethylene. dWf is the change in mass fraction, dLogM is also referred to as dLog(MM) and is the change in the logarithm of molecular weight, and LogM is also referred to as Log(MM) and is the logarithm of molecular weight.

Butyl Branch Frequency (BFR) Test Method: Comonomer content is determined by ¹³ C NMR analysis in accordance with methods described, for example, in US Pat. No. 5,292,845 (Kawasaki, et al.) and JC Randall in Rev. Macromol. Chem. Phys., C29, 201-317, ranging from homopolymer with zero short-chain branching per 1000 total carbons (0 TCB/1000 total C) to 50 TCB/1000 total C, where total C is the sum of the carbons in the polymer backbone plus carbon atoms in all polymer branches. In a poly(ethylene/1-hexene) copolymer, most or all of the branches are butyl groups (e.g., -(CH2)3CH3), and the frequency of butyl branches (BBR) is equal to the number of butyl branches per 1000 total C.

Deconvolution Test Method: A segment of the chromatogram obtained by the bimodality test is divided into nine (9) Schultz-Flory molecular weight distributions. This deconvolution method is described in US 6,534,604. The smallest four MM distributions are attributed to the MMM component of the polyethylene, and the largest five MM distributions are attributed to the BMM component of the polyethylene. Determine the corresponding mass percentages (% wt.) of each of the MMM and BMM components of polyethylene in the bimodal ethylene/1-hexene copolymer composition, using the total values of the mass fractions (W _f ) of the MMM and BMM polyethylene components, and the corresponding number-average molecular weights (M _n ) and mass-average molecular weights (M _w ) using known mathematical transformations of the cumulative MM Schultz-Flory distributions.

Density is measured in accordance with ASTM D792-13, Standard Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement Method, Method B (for testing solid plastics in liquids other than water, such as liquid 2-propanol). The results are recorded in grams per cubic centimeter (g/ ^cm3 ).

Gel Permeation Chromatography (GPC) Test Method: Mass-average molecular weight test method: Determine _Mw , number-average molecular weight ( _Mn ), and _Mw / _Mn using chromatograms obtained on a high-temperature gel permeation chromatograph (HT-GPC, Polymer Laboratories). The HT-GPC is equipped with transfer lines, a differential refractometric detector (DRD), and three Polymer Laboratories PLgel Mixed-B, 10 µm columns, which are kept in an oven at 160°C. This method uses a solvent consisting of BHT-treated TCB at a nominal flow rate of 1.0 millimeters per minute (mL/min) and a nominal sample injection volume of 300 microliters (μL). The solvent is prepared by dissolving 6 grams of butylated hydroxytoluene (BHT, an antioxidant) in 4 liters (L) of reactive grade 1,2,4-trichlorobenzene (TCB) and filtering the resulting solution through a 0.1 micrometer (µm) Teflon filter to obtain the solvent . Before being fed into the HT-GPC instrument, the solvent is degassed using a built-in degasser. The columns are calibrated using a series of monodisperse polystyrene (PS) standard samples. Separately, known concentrations of the test polymer dissolved in a solvent are obtained by heating known quantities of it in known volumes of solvent at 160°C with continuous shaking for 2 hours to obtain solutions. (All quantities are measured gravimetrically). Use the required solution concentrations, c, of the experimental polymer from 0.5 to 2.0 milligrams of polymer per milliliter of solution (mg/ml), with lower concentrations, c, being used for higher molecular weight polymers. Before testing each sample, the DRM detector is cleaned. Then increase the flow rate in the device to 1.0 ml/min and leave the DRM detector to stabilize for 8 hours before introducing the first sample. Calculate M _w and M _n using universal calibration relationships with column calibration. Calculate the MW at each elution volume using the following equation:

,

where the subscript “X” denotes the experimental sample, the subscript “PS” denotes polystyrene standards, α _PS = 0.67, K _PS = 0.000175, and α _x and K _x are obtained from published literature. For polyethylenes a _x /K _x = 0.695/0.000579. For polypropylenes a _x /K _x = 0.705/0.0002288. At each point in the resulting chromatogram, calculate the concentration, c, from the DRM signal minus the background value, IDRM, using the following equation: c = K _DRM I _DRM /(dn/dc), where K _DRM is the constant determined during DRM calibration, / means division, and dn/dc is the increment of refractive index for the polymer. For polyethylene dn/dc = 0.109. The mass of the isolated polymer is calculated based on the ratio of the integrated area of the chromatogram obtained by concentration chromatography to the elution volume and the mass of the injected sample, which is equal to a predetermined concentration multiplied by the volume of the loop dispenser. Record all molecular weights in grams per mole (g/mol) unless otherwise noted. Additional details about methods for determining _Mw , _Mn , MMP are described in US 2006/0173123 on pages 24-25, paragraphs [0334] - [0341]. Plot a curve of dW/dLog(MM) on the y-axis versus Log(MM) on the x-axis to obtain a GPC chromatogram, where Log(MM) and dW/dLog(MM) are as above.

High Shear Stress Melt Flow Test Method (HSFT) PTR ₂₁ : Uses ASTM D1238-13, Standard Method for Determining Melt Flow Index of Thermoplastics by Extrusion Plastometer, using 190°C/21.6 kilogram (kg) conditions. The results are recorded as the number of grams leaked in 10 minutes (g/10 min).

Melt Flow Test Method (“MFR2”): For ethylene-based (co)polymer, measured in accordance with ASTM D1238-13 using the 190°C/2.16 kg condition, formerly known as “Condition E”.

Melt Flow Test Method PRT5 (“MFR5”): Use ASTM D1238-13 at 190°C/5.0 kg. The results are recorded as the number of grams leaked in 10 minutes (g/10 min).

Melt flow ratio test method OPT ₅ : (“PTR ₂₁ / PTR ₅ ”): is calculated by dividing the value obtained in the test method PTVN, PTR ₂₁ by the value obtained in the melt flow rate test method PTR ₅ .

Melt strength test method: using a Göttfert Rheotens tester at a test temperature of 190°C. The test uses a die having a length of 30 mm and an internal diameter of 2 mm. The acceleration is 2.4 millimeters per second per second (mm/s ² ). The peak melt strength value is the highest value observed in the speed range from 10 to 50 mm/s). Average melt strength is the average value of melt strength measured over a speed range of 35 to 50 mm/s. The strain hardening modulus is measured in accordance with ISO 18488:2015, Polyethylene (PE) materials for piping systems - Determination of strain hardening modulus as a function of slow cracking - Test method.

Shear thinning index (STI) Test method: using dynamic mechanical spectroscopy (DMS). The test sample is pressed using a Carver Press into a 25 x 3 mm round plate at 190°C for 6.5 minutes and under a pressure of 9,070 kg in air. Remove the plate from the press and place it on the table to cool. Using a plate, a constant temperature frequency sweep is performed using a classic ARES or ARES-G2 strain-controlled rheometer equipped with 25 mm (diameter) parallel plates under a nitrogen stream. Place the polymer slab on the instrument plate and allow it to melt for 5 minutes at 190°C. The plates of the device are brought together to a gap of 2 mm, the part of the plate extending beyond the circle of the plates is cut off, and a frequency sweep with a constant temperature is started with a 5-minute delay to achieve temperature equilibrium. Perform passes at 190°C over a frequency range from 0.01 radian per second (rad/s) to 100 rad/s with 5 points per decade of range. Maintain a constant strain amplitude at 10%. The rheometer applies shear strain in the form of stress to the plate and measures torque. Record the results as complex viscosity η*, tan (δ) or tan delta, viscosity, G', G″ and G*. Calculate the shear thinning index (abbreviated as "SIR(0.01/100)" or "ƞ _0.01/100 " or "ƞ _0.01 /ƞ ₁₀₀ ") equal to the complex viscosity at 0.01 rad/s divided to complex viscosity at 100 rad/s.

Antioxidant: 1. Pentaerythritol-tetrakis-(3-(3,5-di-(1′,1′-dimethylethyl)-4-hydroxyphenyl)-propionate); purchased as IRGANOX 1010 from BASF.

Antioxidant: 2. Tris-(2,4-di-(1′,1′-dimethylethyl)phenyl)-phosphite. Purchased as IRGAFOS 168 from BASF.

Carbon black masterbatch 1: 40 wt% P-type carbon black having a particle size of less than 10 nm in a linear low density polyethylene carrier resin. Obtained as LL2590 from Cabot Corporation.

Catalyst neutralizer: 1. Calcium stearate.

Bimodal Catalyst System 1 (BCS1): spray-dried catalyst composition prepared from Cabosil™ TS-610, methyl aluminoxane, bis-(2-(pentamethylphenylamido)-ethyl)-amine zirconium dibenzyl and (methylcyclopentadienyl)(1,3-dimethyl-4 ,5,6,7-tetrahydroindenyl)-zirconium dimethyl.

Bimodal Catalyst System 2 (BCS2): Spray-dried catalyst composition prepared from Cabosil™ TS-610, methyl aluminoxane and bis-(2-(pentamethylphenylamido)-ethyl)-amine zirconium dibenzyl.

Bimodal Catalyst System 3 (BCS3): PRODIGY™ BMC-200 from Univation Technologies, LLC, Houston, TX, USA.

Auxiliary catalyst 1 (BK1): solution of 0.04 wt.% (methylcyclopentadienyl)-(1,3-dimethyl-4,5,6,7-tetrahydroindenyl)-dimethyl zirconium in isopentane.

Auxiliary Catalyst 2 (AC2): PRODIGY™ UT-TR-200 from Univation Technologies, LLC.

Comonomer: 1-hexene or H ₂ C=C(H)(CH ₂ ) ₃ CH ₃ .

Ethylene (“C ₂ ”): CH ₂ =CH ₂ .

Molecular hydrogen gas: _H2 .

Invention example 1 (PI1): polymerization procedure. Conducted in a pilot scale reactor with bimodal catalyst system 1 (BMK1), auxiliary catalyst 1 (AC1) and comonomer 1-hexene in accordance with the method described previously, adjusting the polymerization conditions, including reactor bed temperature, H ₂ /C ₂ molar ratio, molar ratio C ₆ /C ₂ and feed rate VK1, to obtain an embodiment of a bimodal ethylene/1-hexene copolymer composition in the form of granular resins. The operating conditions for polymerization are given in Table 1.

Invention example 2 (PI2): polymerization procedure. Conducted in a pilot scale reactor using bimodal catalyst system 2 (BMK2), auxiliary catalyst 1 (AC1) and 1-hexene comonomer in accordance with the previously described method for controlling polymerization conditions, including reactor bed temperature, H ₂ /C ₂ molar ratio, molar ratio C ₆ /C ₂ and feed rate BK1 to obtain an embodiment of a bimodal ethylene/1-hexene copolymer composition in the form of granular resins. The polymerization operating conditions are shown in Table 1. PI2 is excluded as an example of the invention in embodiments that include melt property (c), a shear thinning index of 96 to 125.

Control example 1 (CP1): the polymerization procedure for CP1 was carried out in a pilot-scale reactor with a system of bimodal catalysts 3 (BMK3), an auxiliary catalyst 2 (BC2) and a 1-hexene comonomer in accordance with the previously described method for adjusting the polymerization conditions, including the bed temperature in reactor, H ₂ /C ₂ molar ratio, C ₆ /C ₂ molar ratio and VK2 feed rate, obtaining a comparative bimodal ethylene/1-hexene copolymer composition in the form of granular resins. Table 1 shows the operating conditions for polymerization.

Table 1. Operating conditions for PI1 – PI2 and KP1

PI1 PI2 KP1 Reactor type O, ND, GFP-PS* O, ND, GFP-PS** O, ND, GFP-PS Reactor purge gas Anhydrous N ₂ Anhydrous N ₂ Anhydrous N ₂ Layer temperature (°C) 99.9 105.0 104.9 Reaction pressure (kPa)^ 1827 2410 1827 Partial pressure C2 (kPa) 1517 1516 1517 Molar ratio H ₂ /C ₂ 0.00229 0.00280 0.00198 Molar ratio C ₆ /C ₂ 0.00560 0.00703 0.00446 1-methylbutane (mol %) 11.4 11.4 11.4 Surface gas flow velocity (m/s) 0.643 0.555 0.643 Bimodal catalytic system BMK1 BMK2 BMK3 Auxiliary catalyst VK1 VK1 VK2 Initial seed layer = HDPE resin granules Preload Preload Preload Fluid bed mass (kg) 16,086 32.1 15 275 Productivity by polymer composition (kg/hour) 4 491 14.6 4 355 Residence time of the polymer composition (hour) 3.58 2.2 3.51 Bulk density of free-flowing polymer composition, (kg/ ^m3 ) 293 178 279

*O, ND, HFP-PS: single, continuous, for gas-phase fluidized bed polymerization. ** The pilot reactor did not operate in condensation mode. ^Reaction pressure (kPa): total pressure in the reactor in kilopascals.

As shown in Tables 1 and 2, the operating conditions used to prepare the bimodal ethylene/1-hexene copolymer compositions PI1 – PI2 include bed temperature from 99.9° to 105.0°C; partial pressure of ethylene (C ₂ ) from 1516 to 1517 kPa; molar ratio H ₂ /C ₂ from 0.00229 to 0.00280; molar ratio C ₆ /C ₂ from 0.00560 to 0.00703; surface gas flow velocity from 0.555 to 0.643 m/s (meters per second). In some embodiments, the method for synthesizing a bimodal ethylene/1-hexene copolymer composition uses the above operating conditions.

Composition and granulation procedure: Each of the different granular resins PI1 to PI2 and KP1 were separately mixed with 1500 ppm w/w. (ppm) antioxidant 1, 500 ppm antioxidant 2 and 1000 ppm catalyst neutralizer 1 and 5.6 wt% carbon black masterbatch 1 (to produce a final composition containing 2.25 wt% carbon black) in a belt mixer and then compounded into jet cut pellets using a Coperion ZSK twin screw extruder -40. The resulting granules of each resin were tested for the melt properties of PTVN (PTR ₂₁ ), PTR (5 kg), OPT5 (PTR ₂₁ / PTR ₅ ) and melt strength according to the above-mentioned relevant test methods. The results are presented below in Table 2. In some embodiments, the bimodal ethylene/1-hexene copolymer composition further comprises at least one antioxidant selected from antioxidants 1 and 2; at least one catalyst catalyst selected from catalyst catalysts 1 and 2; or a combination thereof.

Table 2. Properties of melts PI1 – PI2 and KP1.

Trial PI1 PI2 KP1 ƞ _0.01 /ƞ ₁₀₀ 107 74 119 PTR ₂₁ (190°C, 21.6 kg) (g/10 min) 5.41 5.72 5.75 PTR ₅ (190°C, 5.0 kg) (g/10 min) 0.183 0.21 0.179 OPT ₅ (PTR ₂₁ / PTR ₅ ) 29.5 27.0 32.2 melt strength (cN) OK. 20.0 19.6 OK. 20.5

As shown in Table 2, the melt properties of the bimodal ethylene/1-hexene copolymer compositions PI1 – PI2 include a melt flow index at high shear stress PTR ₂₁ (190°C, 21.6 kg) from 5.41 to 5.72 g/10 min; melt flow index PTR ₅ (190°C, 5.0 kg) from 0.183 to 0.21 g/10 min; ratio of melt flow indicators OPT ₅ (PTR ₂₁ / PTR ₅ ) from 27.0 to 29.5; and melt strength from 19 to 21 cN (from 19.6 to 20.0 cN). In some embodiments, the bimodal ethylene/1-hexene copolymer composition has any one, alternatively all but one, alternatively all of the above melt properties.

Granular resins from PI1 to PI2 and KP2 are characterized by density; frequency of butyl branches per 1000 carbon atoms (bn/1000C); molecular weight distribution (M _w /M _n ), MWD, and mass average, number average and z-average molecular weight in accordance with their respective test methods mentioned above. The results are presented below in Table 3.

Table 3. Properties of resins PI1 – PI2 and KP1.

Trial PI1 PI2 KP1 Density (g/cm ³ ) 0.9486 0.9484 0.9488 BMM component content (wt.%) 36.9 49.1 42.3 MMM component content (wt.%) 63.1 50.9 57.7 BMM Mn (kg/mol) 200.3 151.0 187.3 BMM M _w (kg/mol) 812.4 656.1 714.5 BMM Mw/Mn 4.05 4.34 3.82 MMM Mn (kg/mol) 12.5 9.6 12.2 MMM M _w (kg/mol) 35.4 27.8 33.4 MMM Mw/Mn 2.84 2.88 2.74 bhr/1000C 1.4 1.43 1.28 Mn (kg/mol) 23.1 14.9 21.2 M _w (kg/mol) 354.1 333.3 324.5 _Mw / _Mwn (MMR) 15.3 22.4 15.3 Mz (kg/mol) 3,086 2 462 2 402 BBR (at 1000C) 1.4 1.43 1.28

As shown in Table 3, the properties of resins of bimodal ethylene/1-hexene copolymer compositions PI1 – PI2 include densities from 0.9486 to 0.9584 g/cm ³ ; content of high molecular weight component (HMW) from 36.9 to 49.1% wt.; content of low molecular weight component (MMM) from 63.1 to 50.9% wt.; number-average molecular weight from 14,900 to 23,100 g/mol; weight average molecular weight from 333,300 to 354,100 g/mol; molecular weight distribution _Mw / _Mn (MWD) from 15.3 to 22.4; z-average molecular weight from 2,462,000 to 3,086,000 g/mol and butyl branch frequency from 1.4 to 1.43 per 1000 carbon atoms. In some embodiments, the bimodal ethylene/1-hexene copolymer composition has any one, alternatively all but one, alternatively all of the above resin properties.

Pipe Forming Procedure: The granular resins of the bimodal ethylene/1-hexene copolymer composition PI1 to PI2 and CP1 are separately melted at the melt temperatures specified below and individually extruded to produce 25.4 centimeter (cm, 10 in) SDR11 pipes using pipe extrusion machines Davis Standard 130 mm with grooved cylinder. SDR11 pipes were assessed for resistance to critical pressure of rapid crack propagation (ISO 13477). Resistance to slow crack growth was measured by strain hardening modulus and accelerated IPPT. See Table 4.

Table 4. Properties of pipes from PI1 - PI2 and KP1.

Trial PI1 PI2 KP1 Extruder speed (rpm) 75.7 But 75.7 Engine Load (%) 78 But 79 Speed (kg/hour) 0.891 But 0.816 Head (MPa) 33 But 36 RCP Pc ISO13477 (MPa) > 1 But > 1 Strain hardening modulus (MPa) 61 But 58 Accelerated IPP (hours) 473 531 249

N/A means not determined.

As shown in Table 4, the pipe properties of the bimodal ethylene/1-hexene copolymer compositions PI1 and PI2 include strain hardening modulus and full notch accelerated creep test performance from 473 to 531 hours. In some embodiments, the bimodal ethylene/1-hexene copolymer composition and pipes thereof independently exhibit one, alternatively all but one, alternatively all of the above pipe properties. Without wishing to be bound by theory, it is believed that a bimodal ethylene/1-hexene copolymer composition, at a given density, has improved performance in accelerated SPPI due to its combination of Mw/Mn and comonomer distribution properties. For example, a bimodal ethylene/1-hexene copolymer composition has a higher content of comonomer units in the BMM component at a given composition density than comparative bimodal ethylene/1-hexene copolymers. This improvement means that the bimodal ethylene/1-hexene copolymer composition has improved performance as a resin for PE100 pipe and PE100 RC pipe.

Claims (10)

1. A bimodal ethylene/1-hexene copolymer composition for pipes, consisting of a higher molecular weight ethylene/1-hexene copolymer component (BMM component) having a molecular weight distribution of 4.05 to 4.34, a lower molecular weight polyethylene homopolymer molecular weight or a lower molecular weight ethylene/1-hexene copolymer component (MMM component) having a molecular weight distribution of 2.84 to 2.88; where the division into fractions of components, characterized by the mass fraction of the BMM component and the mass fraction of the MMM component, ranges from 36.9 to 49.1 mass. % and from 63.1 to 50.9 wt. %, respectively, of the total mass of the BMM and MMM components, obtained using a combination of a bimodal catalyst system and an auxiliary catalyst in the presence of molecular hydrogen gas; wherein said bimodal catalytic system was obtained by bringing the first activator into contact with bis-(2-(pentamethylphenylamido)-ethyl)-amine zirconium dibenzyl and (methylcyclopentadienyl)(1,3-dimethyl-4,5,6,7-tetrahydroindenyl)-zirconium dimethyl ; wherein said auxiliary catalyst is obtained by contacting the second activator with (methylcyclopentadienyl)(1,3-dimethyl-4,5,6,7-tetrahydroindenyl)-zirconium dimethyl; wherein the first and second activators are the same or different; and wherein the molar ratio of molecular hydrogen gas to ethylene is from 0.001 to 0.0050; and a molar ratio of 1-hexene to ethylene of from 0.00450 to 0.01000, and having a density of from 0.9486 to 0.9584 grams per cubic centimeter (g/cm ³ ), measured in accordance with ASTM D792-13, method B and molecular weight dispersion from 15.3 to 22.4, measured by the gel permeation chromatography (GPC) test method. 2. Bimodal ethylene/1-hexene copolymer composition according to claim 1, which in molten form at a temperature of 190°C is characterized by properties (a), (b) and, optionally, (c): (a) melt flow index (MFR ₅ ) from 0.15 to 0.30 grams per 10 minutes (g/10 min), where MFR ₅ is measured according to ASTM D1238-13, at 190°C and 5.0 kg, (b) peak melt strength from 18 to 29 centinewtons (cN), and optionally (c) a shear thinning index, η _0.01 /η ₁₀₀ , from 96 to 125, and in solid form, said bimodal ethylene/1-hexene copolymer composition is characterized by the properties of (e) and ( f): (e) strain hardening modulus from 50.0 to 75 MPa and (f) performance in an accelerated full notch creep test (ACCT) from 401 to 700.0 h. 3. Bimodal ethylene/1-hexene copolymer composition according to claim 1, characterized by any of the property limitations from (iv) to (viii): (iv) (a) MFR ₅ is from 0.15 to 0.24 g/10 min ; (v) (c) the shear thinning index, η _0.01 /η ₁₀₀ , ranges from 99 to 115; (vi) (b) peak melt strength is between 20.0 and 28 cN; (vii) (e) the strain hardening modulus is from 55 to 70.0 MPa; and (viii) (e) the characteristic in the accelerated IPP ranges from 401 to 600.0 hours. 4. Bimodal ethylene/1-hexene copolymer composition according to any one of paragraphs. 1-3, further characterized by any of the melt property limitations from (i) to (iii): (i) high load melt flow index MFR ₂₁ from 1 to 10 g/10 min, where MFR ₂₁ is measured according to ASTM D1238-13, at 190°C and 21.6 kg; (ii) the ratio of melt flow indicators PTR ₂₁ / PTR ₅ from 20 to 40; (iii) restrictions (i) and (ii) simultaneously. 5. Bimodal ethylene/1-hexene copolymer composition according to any one of paragraphs. 1-4, further characterized by any of the resin property limitations (i) through (xii): (i) a weight average molecular weight ( _Mw ) of 300,000 to 400,000 grams per mole (g/mol); (ii) number average molecular weight (M _n ) from 10,000 to 30,000 g/mol; (iii) z-average molecular weight (M _z ) from 2000000 to 3400000 g/mol; (iv) butyl branch frequency per 1000 carbon atoms (nb/1000C) between 1.2 and 1.5, measured in accordance with the butyl branch frequency test method; and where M _w , M _n and M _z are measured according to the GPC test method. 6. A method for synthesizing a bimodal ethylene/1-hexene copolymer composition according to any one of claims. 1-5, which consists in copolymerizing ethylene and 1-hexene with a combination of a bimodal catalyst system and an auxiliary catalyst in the presence of molecular hydrogen gas; wherein said bimodal catalytic system was obtained by bringing the first activator into contact with bis-(2-(pentamethylphenylamido)-ethyl)-amine zirconium dibenzyl and (methylcyclopentadienyl)(1,3-dimethyl-4,5,6,7-tetrahydroindenyl)-zirconium dimethyl ; wherein said auxiliary catalyst is obtained by bringing the second activator into contact with (methylcyclopentadienyl)(1,3-dimethyl-4,5,6,7-tetrahydroindenyl)-zirconium dimethyl; wherein the first and second activators are the same or different; and wherein said effective polymerization conditions include a reactor bed temperature of from 99.9 to 105.0° C.; the molar ratio of molecular hydrogen gas to ethylene is from 0.001 to 0.0050; and the molar ratio of 1-hexene to ethylene is from 0.00450 to 0.01000. 7. The method of claim 6, wherein the copolymerization is carried out in the presence of an induced condensation agent in a single polymerization reactor under effective polymerization conditions to obtain a precursor bimodal ethylene/1-hexene copolymer composition. 8. A pipe consisting of a bimodal ethylene/1-hexene copolymer composition according to any one of claims. 1-5. 9. A method for manufacturing a pipe, comprising steps (A), (B1) or (B2): (A) melting a bimodal ethylene/1-hexene copolymer composition according to any one of claims. 1-5 to obtain its melt; (B1) extruding the melt through an annular die configured to form a cylinder to produce an initial solid-walled cylinder of a bimodal ethylene/1-hexene copolymer composition, or (B2) extruding and spirally winding the melt around a mandrel configured to form a wall with an unsealed seam, producing a wall with an unsoldered seam; and sealing the unsoldered seam of the wall with an unsoldered seam, obtaining the original cylinder with walls with a sealed seam. 10. The method of claim 9, further comprising steps (C) and (D): (C) resizing the original solid wall cylinder or the original sealed wall cylinder to produce a cylinder of a different diameter; and (D) cooling the original solid wall cylinder, the original sealed wall cylinder, or the resized wall cylinder to produce a solid wall pipe or a sealed wall pipe, respectively.