Hafnocene-titanocene catalyst system

Abstract

Hafnocene-titanocene catalyst systems including hafnocene and titanocene catalysts, polyolefins, methods for making and using same, and articles containing same.

Description

[Technical Field]

[0001] Hafnocene-titanocene catalyst systems, methods, polyolefins, and articles. [Background technology]

[0002] Patents related to this field include US 6,242,545 B1, US 6,258,903 B1, US 8,247,588 B2, US 8,404,612 B2, and US 9,045,569 B2 ("JENSEN"). The JENSEN example shows a rapid decay in catalytic activity as the molar amount of (B) titanium-containing metallocene compound increases relative to the molar amount of (A) metallocene precatalyst compound or polymerization-active metallocene compound. Thus, the polymerization of olefins such as ethylene and alpha-olefins catalyzed by hafnocene catalysts can make it difficult to produce higher molecular weight polyolefins. Summary of the Invention

[0003] A hafnocene-titanocene catalyst system comprising a hafnocene catalyst and a titanocene catalyst, wherein the hafnocene catalyst is 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl) dichloride / dibromide / dialkylhafnium with an activated alkylaluminoxane, wherein the subscript x is 1 or 2, the subscript y is 0, 1, or 2, and R 1 and R 2 are each independently methyl, ethyl, normal-(C3-C 10 ) Alkyl (straight chain), or iso-(C3-C 10A hafnocene-titanocene catalyst system, wherein the hafnocene catalyst is a bis(cyclopentadienyl)titanium dichloride and a trialkylaluminum, and the titanocene catalyst comprises the product of an activation reaction between the hafnocene catalyst and a trialkylaluminum. The hafnocene catalyst is active in a polymerization reactor to catalyze the polymerization of olefin monomers to produce polyolefins. The titanocene catalyst is simultaneously active in a polymerization reactor to catalyze the hydrogenation of olefin monomers to produce alkanes. The hafnocene and titanocene catalysts function complementary in that the olefin polymerization reaction catalyzed by the hafnocene can generate molecular hydrogen (H) as a by-product, while the hydrogenation reaction catalyzed by the titanocene catalyst can function to consume the molecular hydrogen so generated.

[0004] We also provide methods for making the (pro)catalyst systems of the present invention, along with methods for polymerizing olefin (co)monomer(s), polyolefins made by the methods, and articles of manufacture containing or made from the polyolefins. DETAILED DESCRIPTION OF THE INVENTION

[0005] The introduction, overview, and abstract are incorporated herein by reference.

[0006] Specific inventive embodiments are numbered below for cross-reference.

[0007] Aspect 1. A hafnocene-titanocene catalyst system comprising a hafnocene catalyst and a titanocene catalyst, wherein the hafnocene catalyst is ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl) dichloride / dibromide / dialkylhafnium with an activated alkylaluminoxane, wherein the subscript x is 1 or 2, the subscript y is 0, 1, or 2, and R 1 and R 2 are each independently methyl, ethyl, normal-(C3-C10 ) Alkyl (straight chain), or iso-(C3-C 10 ) alkyl, the titanocene catalyst comprises the product of an activation reaction between bis(cyclopentadienyl)titanium dichloride and a trialkylaluminum, and the hafnocene-titanocene catalyst system is characterized by a trialkylaluminum / Hf molar ratio of 0.1 to 50, alternatively 0.5 to 40, alternatively 1.0 to 34, and a Ti / Hf molar ratio of 0.1 to 5, alternatively 0.2 to 4, alternatively 0.5 to 3. The hafnocene-titanocene catalyst system may further comprise an olefin monomer (e.g., ethylene), wherein the hafnocene catalyst and the titanocene catalyst are separated from each other by the olefin monomer in the hafnocene-titanocene catalyst system.

[0008] Embodiment 2. The hafnocene-titanocene catalyst system of embodiment 1, characterized by any one of limitations (i)-(vi): (i) the subscript x is 1 and the subscript y is 0, (ii) the subscripts x and y are each 1, (iii) the subscript x is 1 and the subscript y is 2, (iv) the subscript x is 2 and the subscript y is 0, (v) the subscript x is 2 and the subscript y is 1, or (vi) the subscript x is 2 and the subscript y is 2. When the subscript y is 0, then ((R 2 ) y -cyclopentadienyl) is unsubstituted cyclopentadienyl.

[0009] Aspect 3. Limitations (i) to (xxvi), or (xxvii) to (xxxix): (i) R 1 and at least one of R2 is independently methyl; (ii) R 1 and at least one of R2 is independently ethyl; (iii) R 1 and at least one of R2 is independently normal-(C3 to C 10 ) alkyl (straight chain), (iv) R 1 and at least one of R2 is independently iso-(C3-C 10 ) alkyl, (v) R 1At least one of the following is independently normal-(C3 to C 10 ) Alkyl (straight chain) or iso-(C3-C 10 ) alkyl, and R 2 At least one of the following is independently normal-(C3 to C 10 ) Alkyl (straight chain) or iso-(C3-C 10 ) alkyl, (vi) R 1 At least one of the following is independently normal-(C3 to C 10 ) alkyl (straight chain), and R 2 At least one of the following is independently normal-(C3 to C 10 ) alkyl (straight chain), (vii) R 1 At least one of the groups is independently iso-(C3 to C 10 ) alkyl, and R 2 At least one of the groups is independently iso-(C3 to C 10 ) alkyl, (viii) ((R 1 ) x -cyclopentadienyl) and ((R 2 ) y -cyclopentadienyl) (e.g., one is propylcyclopentadienyl and the other is cyclopentadienyl or methylcyclopentadienyl), (ix) ((R 1 ) x -cyclopentadienyl) and ((R 2 ) y -cyclopentadienyl) are the same (e.g., both are propylcyclopentadienyl), (x) the subscripts x and y are each 1, and R 1 and R 2 are the same, (xi) the subscripts x and y are each 1, and R 1 and R 2 Each of the same normal (C3 to C 10 ) alkyl; (xii) the subscripts x and y are each 1; R 1 and R 2 are the same normal (C-C) alkyl; (xiii) the subscripts x and y are each 1; and R 1 and R2 each is propyl; (xiv) dichloride / dibromide / dialkyl is dichloride or dibromide, or dichloride; (xv) dichloride / dibromide / dialkyl is dialkyl, and alkyl is each independently (C1-C 10 ) alkyl, or (C2-C 10 ) alkyl, or (C1-C4) alkyl, or (C2-C6) alkyl; (xvi) the dichloride / dibromide / dialkyl is dialkyl, and the alkyls are each independently selected from methyl, ethyl, 1-methylethyl, propyl, butyl, 1-methylpropyl, and 2-methylpropyl; (xvii) the dichloride / dibromide / dialkyl is dialkyl, and the alkyls are each independently selected from methyl, ethyl, propyl, and butyl; (xviii) the dichloride / dibromide / dialkyl is dialkyl, and the alkyl is (xix) the dichloride / dibromide / dialkyl is dialkyl and the alkyl is each independently selected from methyl and propyl; (xx) the dichloride / dibromide / dialkyl is dialkyl and the alkyl is each independently selected from methyl and ethyl; (xxi) the dichloride / dibromide / dialkyl is dialkyl and the alkyl is each methyl; (xxii) the dichloride / dibromide / dialkyl is dialkyl and the alkyl is each ethyl; (xxiii) (R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl) dichloride / dibromide / dialkylhafnium is selected from bis(propylcyclopentadienyl)hafnium dichloride, bis(propylcyclopentadienyl)hafnium dibromide, bis(propylcyclopentadienyl)dimethylhafnium, and bis(propylcyclopentadienyl)diethylhafnium, (xxiv) ((R 1 ) x -cyclopentadienyl)((R 2 ) y-cyclopentadienyl)dichloride / dibromide / dialkylhafnium is bis(propylcyclopentadienyl)hafnium dichloride, (xxv) ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl)dichloride / dibromide / dialkylhafnium is bis(propylcyclopentadienyl)dimethylhafnium, (xxvi) ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl)dichloride / dibromide / dialkylhafnium is bis(propylcyclopentadienyl)diethylhafnium, or (xxvii) both of any one of (i) and (xiv) to (xxii), (xxviii) both of any one of (ii) and (xiv) to (xxii), (xxix) both of any one of (iii) and (xiv) to (xxii), (xxx) both of any one of (iv) and (xiv) to (xxii), (xxxi) both of (v) and any one of (xiv) to (xxii), (xxxii) both of any one of (vi) and (xiv) to (xxii), (xxxiii)(vii) and (xiv) to (xxii) (xxxv) both of (ix) and any one of (xiv) through (xxii), (xxxvi) both of (x) and any one of (xiv) through (xxii), (xxxvii) both of (xi) and any one of (xiv) through (xxii), (xxxviii) both of (xii) and any one of (xiv) through (xxii), and (xxxix) both of (xiii) and any one of (xiv) through (xxii), or any one of (xxiii) through (xxvi).

[0010] Embodiment 4. The hafnocene-titanocene catalyst system of any one of embodiments 1-3, wherein the trialkylaluminum is selected from any one of the following limitations (i)-(vii): (i) tri((C1-C8) alkyl)aluminum, (ii) tri((C3-C7) alkyl)aluminum, (iii) tri((C4-C6) alkyl)aluminum, (iv) tri((C4) alkyl)aluminum, (v) tri((C6) alkyl)aluminum, (vi) tri(2-methylpropyl)aluminum (i.e., tri(isobutyl)aluminum, also known as T2MPAl), and (vii) tri(hexyl)aluminum (also known as tri(n-hexyl)aluminum or TnHal or TnHAl).

[0011] Embodiment 5. The hafnocene-titanocene catalyst system of any one of Embodiments 1-4, wherein the hafnocene catalyst is supported (disposed) on a support material. The support material may comprise dehydrated untreated porous silica, and the interior and exterior surfaces are hydrophilic. The supported ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl) dichloride / dibromide / dialkyl hafnium silica (dehydrated, porous, untreated) 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl)hafnium dichloride / dibromide / dialkylhafnium ion exchange catalyst in a saturated and / or aromatic hydrocarbon (e.g., toluene and / or heptane) solution to form a mixture, and then the mixture is concentrated under vacuum to give the supported ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl) dichloride / dibromide / dialkylhafnium, which can be subsequently activated by contact with methylaluminoxane.

[0012] Embodiment 6. The hafnocene-titanocene catalyst system of any one of embodiments 1-4, wherein the hafnocene catalyst, and optionally the titanocene catalyst, are spray dried (deposited by spray drying) on ​​a support material. Alternatively, ((R 1 ) x -cyclopentadienyl)((R 2 ) y The (R -cyclopentadienyl) dichloride / dibromide / dialkylhafnium can be spray dried onto a support material in the absence of a titanocene catalyst, and then the spray dried ((R 1 ) x -cyclopentadienyl)((R 2 ) y The (R -cyclopentadienyl) dichloride / dibromide / dialkylhafnium / support material may be contacted with an alkylaluminoxane to produce a hafnocene catalyst on the spray-dried support material. The support material may comprise dehydrated untreated silica, which is porous, and the interior and exterior surfaces are hydrophilic, or the support material may comprise hydrophobic pretreated fumed silica, and the interior and exterior surfaces are rendered hydrophobic by pretreatment with a hydrophobizing agent. The spray-dried hafnocene catalyst or ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl) dichloride / dibromide / dialkylhafnium is used to prepare dehydrated untreated silica or hydrophobically pretreated silica (pretreated with a hydrophobizing agent) in the presence of a hafnocene catalyst or ((R 1 ) x -cyclopentadienyl)((R 2 ) y and suspending a solution of a hafnium dichloride / dibromide / dialkyl (R-cyclopentadienyl) in a saturated and / or aromatic hydrocarbon liquid (e.g., hexane, heptane, mineral oil, and / or toluene) to form a mixture thereof, respectively, and spray-drying the mixture to deposit a spray-dried hafnocene catalyst or a spray-dried (R-cyclopentadienyl) hafnium dichloride / dibromide / dialkyl ... 1 ) x -cyclopentadienyl)((R 2 ) yand obtaining a spray-dried ((R -cyclopentadienyl) dichloride / dibromide / dialkylhafnium. 1 ) x -cyclopentadienyl)((R 2 ) y The (R -cyclopentadienyl) dichloride / dibromide / dialkylhafnium can be activated on a support material by subsequently contacting the former with an alkylaluminoxane. The alkylaluminoxane can be methylaluminoxane (MAO), modified MAO, or silica-supported MAO. The hafnocene catalyst can be unsupported / non-spray-dried, supported, or spray-dried. Supported hafnocene catalysts can be made by a concentration method instead of a spray-drying method. The concentration method involves contacting silica (dehydrated, porous, untreated) with the hafnocene catalyst, or with the alkylaluminoxane and ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl) dichloride / dibromide / dialkylhafnium in an alkane(s) and / or aromatic hydrocarbon liquid (e.g., hexane, heptane, mineral oil, and / or toluene) solution to form a mixture, and then concentrating the mixture under vacuum to obtain the supported hafnocene catalyst.

[0013] Aspect 7. A method for making a hafnocene-titanocene catalyst system, comprising the steps of: ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl) dichloride / dibromide / dialkylhafnium in an alkylaluminoxane, and optionally a support material, and optionally a compound of formula: MQ m (O2CR) n(wherein M, Q, R, m, and n are as defined below) to obtain a hafnocene catalyst, and then contacting the hafnocene catalyst with a titanocene catalyst prepared by the activation reaction of bis(cyclopentadienyl)titanium dichloride with a trialkylaluminum, thereby obtaining a titanium catalyst and a hafnocene-titanocene catalyst system. The hafnocene-titanocene catalyst system can be any one of those described in Aspects 1-6. In some embodiments, a support material and a metal carboxylate are included in the contacting step and the resulting hafnocene-titanocene catalyst system. The hafnocene catalyst and titanocene catalyst are prepared separately from one another and then combined to obtain the hafnocene-titanocene catalyst system. The hafnocene catalyst, and optionally the titanocene catalyst, can be spray dried or supported on a support material as described above. The activation reactions may be carried out independently under an inert gas atmosphere and in a saturated and / or aromatic hydrocarbon solvent such as an alkane, a mixture of two or more alkanes, mineral oil, an alkyl-substituted benzene such as toluene, ethylbenzene, or xylene, or a mixture of any two or more thereof. The hafnocene catalyst and / or titanocene catalyst may be independently dried by removing the saturated and / or aromatic hydrocarbon solvent therefrom to obtain a dried particulate solid form thereof, and then contacted together to obtain a dried particulate solid form of the hafnocene-titanocene catalyst system. Alternatively, the hafnocene-titanocene catalyst system may be formed in a saturated and / or aromatic hydrocarbon solvent, and then the solvent removed therefrom to obtain a dried particulate solid form of the hafnocene-titanocene catalyst system.

[0014] Embodiment 8. A method of making a polyethylene composition, comprising: polymerizing ethylene (monomer) and, optionally, zero, one, or more (C3-C 20 ) alpha-olefin (comonomer) with a hafnocene-titanocene catalyst system according to any one of embodiments 1-6 or made by the method of embodiment 7 to produce polyethylene homopolymer or ethylene / (C-C 20and a hafnocene-titanocene catalyst system, or by-products thereof. Without wishing to be bound by theory, it is believed that the product polyethylene homopolymer or ethylene / (C3-C4) alpha-olefin copolymer is a hafnocene-titanocene catalyst system, or by-products thereof. 20 It is believed that hafnocene catalysts function in a manner that enhances or increases the rate of polymerization of the monomer and / or any comonomer(s), and titanocene catalysts function in a manner that enhances or increases the rate of consumption of molecular hydrogen (H), whether the H is generated in situ as a by-product of the polymerization reaction or whether externally supplied H is intentionally added to the polymerization reactor, such as to control the properties of the alpha-olefin copolymer, e.g., I. The polymerization reaction is carried out during a contacting step and under effective polymerization conditions. The polymerization reaction can be carried out in the gas phase or the liquid phase. The liquid phase can be a slurry phase or a solution phase. The method may be characterized by any one of steps (i) to (iii): (i) the hafnocene catalyst and the titanocene catalyst are premixed in separate mixing vessels, and then the premix is ​​fed to the polymerization reactor; (ii) the hafnocene catalyst and the titanocene catalyst are contacted with each other immediately prior to entering the polymerization reactor, for example, by contacting them together in feed lines entering the reactor; and (iii) the hafnocene catalyst and the titanocene catalyst are separately fed to the polymerization reactor via separate inlet locations, thereby creating a hafnocene-titanocene catalyst system in situ. In step (ii), the hafnocene catalyst and titanocene catalyst may be contacted with each other for >0-5 minutes, alternatively >0-3 minutes, alternatively >0-1 minute, and optionally with an alkane or alkalene solvent (e.g., hexane, heptane, toluene, mineral oil), but without an olefin monomer, to form a premix comprising, consisting essentially of, or consisting of the hafnocene and titanocene catalyst, which premix is ​​then reacted with ethylene, optionally (C3-C6 20 After such second contacting step, the hafnocene and titanocene catalysts are contacted with ethylene, optionally with (C3 to C4) alpha-olefins. 20The hafnocene catalyst and titanocene catalyst of the hafnocene-titanocene catalyst system made in situ in embodiment (iii) may be polymerized in a polymerization reactor with ethylene and, if present, a (C3-C) alpha-olefin. 20 In some embodiments, the method comprises the step of producing a copolymer of ethylene and one or more (C3-C) alpha-olefins (comonomer(s)). 20 ) alpha-olefin (comonomer) to produce ethylene / (C3-C 20 ) to obtain an alpha-olefin copolymer composition. 20 The alpha-olefin-derived comonomer building blocks can be derived from 1-butene, 1-hexene, 1-octene, or a combination of any two thereof. In some embodiments, the degree of increase in Mw of the polyolefins of the present invention can be, at least in part, a function of whether externally fed H2 is added to the reactor. For example, when externally fed H2 is not added to the reactor, the Mw of the present invention can be at least 5% higher than the comparative Mw when externally fed H2 is not added to the reactor. When externally fed H2 is added to the reactor, the Mw of the present invention can be at least 10% higher than the comparative Mw when externally fed H2 is added to the reactor. Without wishing to be bound by theory, it is expected that the catalytic activity of the hafnocene catalyst will decrease significantly under (co)polymerization conditions in the absence of externally added H; and prior to contacting the hafnocene-titanocene catalyst system with ethylene and an alpha-olefin, the same amount of hafnocene catalyst is premixed with increasing amounts of titanocene catalyst to form premixes having increasing molar ratios of titanocene catalyst to hafnocene catalyst, which premixes are then contacted with ethylene and an alpha-olefin under (co)polymerization conditions. Advantageously, by not premixing the hafnocene and titanocene catalysts, but instead adding the hafnocene and titanocene catalysts separately to spaced locations within the polymerization reactor, the decrease in catalytic activity of the hafnocene catalyst can be substantially attenuated or prevented.

[0015] Aspect 9. Limitations (i) to (iv): (i) externally supplied (from outside the reactor) molecular hydrogen gas (H) is not added to the polymerization reactor and is not present during the contacting step of the method; (ii) the method further comprises adding externally supplied H gas to the polymerization reactor during the contacting step of the method; (iii) the method comprises adding externally supplied H gas to the polymerization reactor during the contacting step of the method; and 20 ) produces a polyethylene homopolymer that is free of alpha-olefins (comonomer(s)) and contains constitutional units derived solely from ethylene; (iv) the method comprises the step of: 20 ) alpha-olefin (comonomer(s)), further comprising monomeric units derived from ethylene and one or more (C-C 20 ethylene / (C3-C) containing comonomer building blocks derived from alpha-olefin comonomers, 20 (v) both (i) and (iii), (vi) both (i) and (iv), (vii) both (ii) and (iii), and (viii) both (ii) and (iv). Without wishing to be bound by theory, it is believed that the ethylene / (C3-C4) copolymers produced by the methods of the present invention are 20 ) The alpha-olefin copolymer is believed to have a higher Mw than the Mw of a comparative copolymer made by a comparative process that is the same as the process of the present invention, except that the comparative process does not include a titanocene catalyst, e.g., does not include Ti.

[0016] Embodiment 10. The method of embodiment 8 or 9, comprising gas phase polymerization in one, two, or more gas phase polymerization reactors under (co)polymerization conditions, optionally in the presence of additional external molecular hydrogen gas (H), and optionally in the presence of an induced condensing agent (ICA), thereby making the polyethylene composition. The (co)polymerization conditions include a reaction temperature of 60 degrees (°) to 12 degrees Celsius (C), alternatively 80°C to 110°C, a molar ratio of molecular hydrogen gas to ethylene (H / C molar ratio) of 0.00001 to 0.25, alternatively 0.000030 to 0.00010, alternatively 0.0001 to 0.20, alternatively 0.001 to 0.050, and a molar ratio of comonomer to ethylene (C / C molar ratio) of 0.001 to 0.20, alternatively 0.002 to 0.14, alternatively 0.005 to 0.10. x / C2).

[0017] Embodiment 11. Prior to the contacting step, the method includes steps (i) to (iii): (i) premixing the hafnocene catalyst and the titanocene catalyst in separate mixing tanks to form these premixes, aging the premixes for 2 hours to 7 days to form an aged premix, and then feeding the aged premixes to the polymerization reactor; (ii) premixing the hafnocene catalyst and the titanocene catalyst with each other in a mixer (e.g., an in-line mixer) to form these unaged premixes, and (iii) feeding the hafnocene catalyst and the titanocene catalyst separately into the polymerization reactor via separate reactor inlets (separate injectors spaced apart by the reactor), thereby forming the hafnocene-titanocene catalyst system in situ within the polymerization reactor.

[0018] Embodiment 12. A polyethylene composition made by the method of embodiment 8, 9, 10, or 11.

[0019] Embodiment 13. An article of manufacture comprising a shaped form of the polyethylene composition of embodiment 12. The article of manufacture can be a coating, a film, a sheet, an extruded article, an injection-molded article, a coating layer (e.g., of a coated article), a pipe, a film (e.g., a blown film), an agricultural film, food packaging, a garment bag, a grocery bag, a heavy-duty bag, an industrial sheet, a pallet and shrink wrap, a bag, a bucket, a freezer container, a lid, and a toy.

[0020] The hafnocene-titanocene catalyst system may be a homogeneous system that does not contain finely divided solids that are not embodiments of the hafnocene or titanocene catalyst. 12 ) the hafnocene-titanocene catalyst system in an aprotic hydrocarbon liquid such as an alkane, mineral oil, alkalene (e.g., toluene or xylene), or a mixture of any two or more thereof, and is free of a support material such as MgCl2 and is free of a carrier material such as alumina, clay, or silica. Alternatively, the hafnocene-titanocene catalyst system may be a heterogeneous system comprising a hafnocene catalyst supported on, or spray-dried or in spray-dried form, a finely divided solid that is a support material such as MgCl2 and / or a carrier material such as alumina, clay, or silica, and a titanocene catalyst, independently, in unsupported, supported, or spray-dried form, on the same or a different finely divided solid. In some embodiments, the hafnocene-titanocene catalyst system further comprises silica, wherein the hafnocene catalyst is spray dried on the silica and the titanocene catalyst is silica-free, and optionally, the spray-dried hafnocene catalyst and titanocene catalyst are fed separately into a polymerization reactor via separate inlet locations, thereby making the hafnocene-titanocene catalyst system in situ.

[0021] In some embodiments, the hafnocene-titanocene catalyst system and polymerization method may further include a non-titanocene hydrogenation catalyst such as bis(1,5-cyclooctadiene)nickel, dicarbonylcyclopentadienylcobalt (CHCo(CO)), bis(cyclopentadienyl)nickel, or cobalt(II) 2-ethylhexanoate, or may further include a titanium alkoxide such as titanium tetrabutoxide.

[0022] The hafnocene-titanocene catalyst system may be zirconium-free.

[0023] The hafnocene-titanocene catalyst system may further comprise a metal carboxylate, the metal carboxylate having the formula: MQ m (O2CR) n wherein M is a metal atom of Group 2 or 13 of the Periodic Table of the Elements, Q is a halogen, hydroxy, alkyl, alkoxy, aryloxy, siloxy, silyl, or sulfonate group, and R is a (C5-C 30 ) hydrocarbyl, where the subscript m is an integer from 0 to 3, the subscript n is an integer from 1 to 3, and the sum of the subscripts m and n is the same as the valence of M. In some embodiments, M is a Group 2 metal atom, alternatively Mg or Ca, alternatively Mg, alternatively Ca, alternatively a Group 13 metal atom, alternatively B or Al, alternatively B, or Al. In some embodiments, Q is a halogen, alternatively hydroxy, alternatively an alkyl, alkoxy, or aryloxy, alternatively an alkyl, alternatively alkoxy, or aryloxy, alternatively a siloxy or silyl, alternatively a siloxy, or silyl, or alternatively a sulfonate group. In some embodiments, the subscript m is an integer from 0 to 2, alternatively 1 to 3, alternatively 1 or 2, alternatively 2 or 3, alternatively 0, alternatively 1, alternatively 2, or alternatively 3. In some embodiments, the subscript n is an integer from 1 to 3, alternatively 2 to 4, alternatively 1 or 2, alternatively 3, alternatively 1, or alternatively 2. In some embodiments, the sum of the subscripts m and n is equal to the valence of M, which is equal to two or three.

[0024] ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl)dichloride / dibromide / dialkylhafnium. ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl)hafnium dichloride, ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl)hafnium dibromide, or ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl)dialkylhafnium. ((R 1 ) x -cyclopentadienyl)((R 2 ) y The ((R -cyclopentadienyl)dichloride / dibromide / dialkylhafnium may be prepared by any suitable method, such as those described in U.S. Pat. No. 6,242,545 B1 and the U.S. patents, European patent publications, and PCT patent publications referenced in column 3, lines 48-60. In some embodiments, the ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl)hafnium dichloride / dibromide / dialkylhafnium may be obtained from commercial sources. 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl)hafnium dichlorides / dibromides / dialkylhafnium compounds can be synthesized according to any suitable method.

[0025] ((R 1 ) x -cyclopentadienyl)((R 2 ) yAn illustrative example of the synthesis of bis(propylcyclopentadienyl)dichloride / dibromide / dialkylhafnium is the synthesis of bis(propylcyclopentadienyl)dichloride / dibromide / dialkylhafnium, compounds of the formula (PrCp)2HfCl2, (PrCp)2HfBr2, or (PrCp)2Hf(CH3)2, respectively, where PrCp is a compound of the formula CH3CH2CH2-[C5H4 -1

[0023] Bis(propylcyclopentadienyl)hafnium dichloride can be synthesized by contacting two molar equivalents of propylcyclopentadiene with two molar equivalents of an alkyllithium in an aprotic solvent under conditions sufficient to produce two molar equivalents of propylcyclopentadienyl anion. The two molar equivalents of propylcyclopentadienyl anion can then be contacted with one molar equivalent of hafnium tetrachloride or hafnium tetrabromide in an aprotic solvent under conditions sufficient to produce one molar equivalent of bis(propylcyclopentadienyl)hafnium dichloride or one molar equivalent of bis(propylcyclopentadienyl)hafnium dibromide, respectively, and two molar equivalents of lithium chloride or lithium bromide, respectively, as a by-product. One molar equivalent of bis(propylcyclopentadienyl)dimethylhafnium can be prepared by contacting bis(propylcyclopentadienyl)hafnium dichloride or bis(propylcyclopentadienyl)hafnium dibromide with two molar equivalents of methyllithium in an aprotic solvent under conditions sufficient to produce one molar equivalent of bis(propylcyclopentadienyl)dimethylhafnium and, as a by-product, two additional molar equivalents of lithium chloride or lithium bromide, respectively. Propylcyclopentadiene can be obtained from commercial sources or synthesized by any suitable known method for preparing alkylcyclopentadienes. Methyllithium can be replaced with another alkyllithium, such as ethyllithium, propyllithium, or butyllithium, to synthesize bis(propylcyclopentadienyl)dialkylhafnium, such as diethyl, dipropyl, or dibutyl, respectively. The aprotic solvent can be an alkane(s) or an alkyl ether. The alkane can be hexane, heptane, cycloheptane, or mineral oil. The alkyl ether can be diethyl ether, tetrahydrofuran, or 1,4-dioxane. Conditions sufficient to make the above compounds can be an inert gas atmosphere, a suitable temperature, and appropriate techniques for handling air- and / or moisture-sensitive reactions, such as Schlenk line techniques.The inert gas in the inert gas atmosphere may be anhydrous molecular nitrogen, helium, argon, or a combination of any two or more of these. The preferred temperature may be -100°C to 25°C, alternatively -78°C to 5°C, or alternatively -50°C to -5°C.

[0026] The hafnocene-titanocene catalyst system can be used in gas phase and liquid phase olefin polymerization reactions to enhance the polymerization rate of the monomer and / or comonomer(s). Liquid phase reactions include slurry and solution phases. In some embodiments, the olefin polymerization reaction is carried out in the gas phase, or the liquid phase, or the slurry phase, or the solution phase. Conditions for gas phase and liquid phase olefin polymerization reactions are generally well known. For illustrative purposes, conditions for the gas phase olefin polymerization reaction are set forth below.

[0027] The polymerization is carried out in a high-pressure, liquid-phase, or gas-phase polymerization reactor to obtain the polyethylene composition of the present invention. Such reactors and processes are generally well known in the art. For example, the liquid-phase polymerization reactor / process can be solution-phase or slurry-phase, as described in U.S. Pat. No. 3,324,095. The gas-phase polymerization reactor / process may use a stirred-bed gas-phase polymerization reactor (SB-GPP reactor) and a fluidized-bed gas-phase polymerization reactor (FB-GPP reactor) and an induced condensing agent, and is carried out in a condensation mode polymerization, as described in U.S. Pat. Nos. 4,453,399, 4,588,790, 4,994,534, 5,352,749, 5,462,999, and 6,489,408. The gas phase polymerization reactor / process may be a fluidized bed reactor / process such as those described in U.S. Pat. No. 3,709,853, U.S. Pat. No. 4,003,712, U.S. Pat. No. 4,011,382, U.S. Pat. No. 4,302,566, U.S. Pat. No. 4,543,399, U.S. Pat. No. 4,882,400, U.S. Pat. No. 5,352,749, U.S. Pat. No. 5,541,270, EP-A-0802 202, and Belgian Patent No. 839,380. These patents disclose gas phase polymerization processes in which the polymerization medium is mechanically agitated or fluidized by a continuous flow of gaseous monomer and diluent. Other useful gas phase processes include series or multi-stage polymerization processes such as those described in US Pat. No. 5,627,242, US Pat. No. 5,665,818, US Pat. No. 5,677,375, EP-A-079420, EP-B1-0649 992, EP-A-0802202, and EP-B-634421.

[0028] In an exemplary embodiment, the polymerization method uses a pilot-scale fluidized-bed gas-phase polymerization reactor (pilot reactor) comprising a reactor vessel containing a fluidized bed of ethylene / alpha-olefin copolymer powder, a distributor plate disposed above the bottom head, defining a bottom gas inlet, and an expansion section or cyclone system at the top of the reactor vessel to reduce the amount of resin fines that may escape from the fluidized bed. The expansion section defines a gas outlet. The pilot reactor further comprises a compressor blower of sufficient power to continuously circulate or loop gas from around the gas outlet of the expansion section at the top of the reactor vessel to the gas inlet at the bottom of the pilot reactor, through the distributor plate and the fluidized bed, and back to the gas inlet. The pilot reactor further comprises a cooling system to remove heat of polymerization and maintain the fluidized bed at a target temperature. The composition of the gases fed to the pilot reactor, such as ethylene, optionally alpha-olefin, optionally hydrogen, and optionally oxygen, is monitored by an in-line gas chromatograph in the circulation loop to maintain specific concentrations that define and enable control of polymer properties. The gas can be cooled until the temperature drops below the dew point, at which point the pilot reactor operates in condensed polymerization mode (CMO) or induced condensation mode (ICMO). In CMO, the liquid is downstream of the cooler and present in the bottom head below the distributor plate. The hafnocene-titanocene catalyst system can be fed to the pilot reactor from the high-pressure unit as a slurry or dry powder; the slurry is fed via a syringe pump and the dry powder is fed via a metering disk. The catalyst system typically enters the fluidized bed in the lower third of its bed height. The pilot reactor is further equipped with a means of measuring the fluidized bed weight and a separation port (product discharge system) for discharging the ethylene / alpha-olefin copolymer powder from the reactor vessel in response to the increase in fluidized bed weight as the polymerization reaction progresses.

[0029] (Co)polymerization conditions: Any resulting variable or combination of variables, such as catalyst composition, amounts of reactants, molar ratio of two reactants, absence of interfering substances (e.g., HO and O), or process parameters (e.g., feed rates or temperatures), steps, or sequences, that are effective and useful in the copolymerization process of the present invention in the polymerization reactor(s) to obtain the polyethylene composition of the present invention.

[0030] During the production of the polyethylene composition of the present invention, at least one, or each, of the (co)polymerization conditions may be fixed (i.e., not changed). Such fixed (co)polymerization conditions may be referred to herein as steady-state (co)polymerization conditions. Steady-state (co)polymerization conditions are useful for continuously producing embodiments of the polyethylene composition of the present invention having the same polymer properties.

[0031] Alternatively, at least one, or two or more of the (co)polymerization conditions may be varied within defined operating parameters during the production of the inventive polyethylene composition to transition from producing a first embodiment of the inventive polyethylene composition having a first set of polymeric properties to a non-inventive polyethylene composition or a second embodiment of the inventive polyethylene composition having a second set of polymeric properties, the first and second sets of polymeric properties being different and each within the limits described herein for the inventive polyethylene composition. For example, all other (co)polymerization conditions being equal, the higher (C3 to C6) copolymerization in the inventive process of copolymerization may be advantageously employed. 20 ) alpha-olefin comonomer / ethylene feed molar ratio results in a lower density of the resulting product, inventive polyethylene composition. Transitioning from one set of (co)polymerization conditions to another is permissible within the meaning of "(co)polymerization conditions" since the operating parameters of both sets of (co)polymerization conditions are within the ranges defined herein. Beneficially, one skilled in the art can achieve any of the described property values ​​for the inventive polyethylene composition in view of the transitioning teachings herein.

[0032] (Co)polymerization conditions for gas-phase or liquid-phase reactors / processes may further include one or more additives, such as chain transfer agents, accelerators, or scavengers. Chain transfer agents are well known and may be alkyl metals such as diethylzinc. Accelerators are well known, such as those described in U.S. Pat. No. 4,988,783, and may include chloroform, CFCl3, trichloroethane, and difluorotetrachloroethane. Scavengers may be trialkylaluminums. Slurry or gas-phase polymerizations may be operated without (without deliberately added) scavengers. (Co)polymerization conditions for gas-phase reactors / polymerizations may further include a certain amount (e.g., 0.5 to 200 ppm based on the total feed to the reactor) of a static control agent and / or a continuity additive, such as aluminum stearate or polyethyleneimine. A static control agent may be added to a gas-phase reactor to suppress the formation or accumulation of static charge therein.

[0033] The (co)polymerization conditions may further include the use of molecular hydrogen to control the final properties of the polyethylene composition. Such use of H2 is generally described in Polypropylene Handbook 76-78 (Hanser Publishers, 1996). All else being equal, the use of hydrogen can increase its melt flow rate (MFR) or melt index (MI), which is affected by the concentration of hydrogen. The molar ratio of hydrogen to total monomers (H2 / monomer), the molar ratio of hydrogen to ethylene (H2 / C2), or the molar ratio of hydrogen to comonomer (H2 / C2) can be varied. x ) can be 0.0001 to 10, alternatively 0.0005 to 5, alternatively 0.001 to 3, alternatively 0.001 to 0.10.

[0034] The (co)polymerization conditions may independently include an ethylene partial pressure in the polymerization reactor(s) of 690 to 3450 kilopascals (kPa, 100 to 500 pounds per square inch absolute (psia)), alternatively 1030 to 2070 kPa (150 to 300 psia), alternatively 1380 to 1720 kPa (200 to 250 psia), alternatively 1450 to 1590 kPa (210 to 230 psia), for example 1520 kPa (220 psia).

[0035] In some embodiments, gas-phase polymerization is carried out in a fluidized-bed gas-phase polymerization (FB-GPP) reactor under relevant gas-phase fluidized-bed polymerization conditions. Such conditions are any variable or combination of variables that can affect the polymerization reaction in the FB-GPP reactor or the composition or properties of the ethylene / alpha-olefin copolymer product produced thereby. Variables can include reactor design and size, catalyst composition and amount, reactant composition and amount, molar ratio of two different reactants, presence or absence of feed gas such as H2 and / or O2, feed gas to reactant molar ratio, absence or concentration of interfering substances (e.g., HO), presence or absence of an induced condensing agent (ICA), average polymer residence time (avgPRT) in the reactor, component partial pressures, monomer feed rate, reactor bed temperature (e.g., fluidized-bed temperature), the nature or sequence of process steps, and transition times between steps. When carrying out the methods of the present invention, variables other than those described or altered by the methods of the present invention can be held constant.

[0036] Comonomer / ethylene gas molar ratio C of comonomer and ethylene fed to the FB-GPP reactor x / C2 can be 0.0001 to 0.20, alternatively 0.0001 to 0.1, alternatively 0.0002 to 0.05, alternatively 0.0004 to 0.02. When the comonomer is 1-hexene, C x is C6.

[0037] Ethylene partial pressure in the FB-GPP reactor: 690 to 2070 kilopascals (kPa, i.e., 100 to 300 pounds per square inch absolute (psia)), alternatively 830 to 1655 kPa (120 to 240 psia), alternatively 1300 to 1515 kPa (190 to 220 psia). Alternatively, the ethylene partial pressure can be 690 to 3450 kilopascals (kPa, 100 to 500 pounds per square inch absolute (psia)), alternatively 1030 to 2070 kPa (150 to 300 psia), alternatively 1380 to 1720 kPa (200 to 250 psia), alternatively 1450 to 1590 kPa (210 to 230 psia), for example 1520 kPa (220 psia). 1.000 psia = 6.8948 kPa.

[0038] The H2 / C2 gas molar ratio in the FB-GPP reactor can be 0.00001 to 0.25.

[0039] Oxygen (O2) concentration relative to ethylene in the FB-GPP reactor ("O2 / C2", parts O2 by volume per million parts ethylene by volume (ppmv)). In some embodiments, O2 / C2 is between 0.0000 and 0.20 ppmv, alternatively between 0.0001 and 0.200 ppmv, alternatively between 0.0000 and 0.183 ppmv, alternatively between 0.0000 and 0.163 ppmv.

[0040] The reactor bed temperature in the FB-GPP reactor can be from 80°C to 120°C, alternatively from 81°C to 115°C, alternatively from 84°C to 110°C.

[0041] Polymer mean residence time (average PRT). The average residence time in minutes or hours of the polymer product in the FB-GPP reactor. The average PRT can be from 30 minutes to 10 hours, alternatively from 60 minutes to 5 hours, alternatively from 90 minutes to 4 hours, alternatively from 1.7 to 3.0 hours.

[0042] The start-up or restart of a reactivated FB-GPP reactor (cold start) or the restart of a transitional FB-GPP reactor (hot start) involves a period before the steady-state polymerization conditions of step (a) are reached. The start-up or restart may involve the use of a polymer seed bed pre-packed or packed, respectively, into the fluidized bed reactor. The polymer seed bed may be composed of a powder of polyethylene, such as polyethylene homopolymer or ethylene / alpha-olefin copolymer.

[0043] The start-up or restart of an FB-GPP reactor may also include a gas atmosphere transition, which involves purging air or other unwanted gas(es) from the reactor with a dry (anhydrous) inert purge gas, followed by purging the dry inert purge gas from the FB-GPP reactor with dry ethylene gas. The dry inert purge gas may consist essentially of molecular nitrogen (N), argon, helium, or a mixture of any two or more thereof. When not in operation, prior to start-up (cold start), the FB-GPP reactor contains an air atmosphere. The dry inert purge gas can be used to sweep air from a restarted FB-GPP reactor during the initial stages of start-up, resulting in an FB-GPP reactor with an atmosphere consisting of the dry inert purge gas. Prior to restart (e.g., after a seed bed change), the FB-GPP reactor during the transition may contain an atmosphere of unwanted ICA or other unwanted gases or vapors. A dry inert purge gas can be used to sweep unwanted vapors or gases from the FB-GPP reactor during the initial stages of restart, resulting in an FB-GPP reactor with an atmosphere consisting of the dry inert purge gas. The optional dry inert purge gas itself can be swept from the FB-GPP reactor with dry ethylene gas. The dry ethylene gas can further contain molecular hydrogen gas, so that the dry ethylene gas is fed to the fluidized-bed reactor as a mixture. Alternatively, the dry molecular hydrogen gas can be introduced separately after the atmosphere of the fluidized-bed reactor has been transitioned to ethylene. The gas atmosphere transition can occur before, during, or after heating the FB-GPP reactor to the reaction temperature for polymerization conditions.

[0044] The start-up or restart of an FB-GPP reactor also includes introducing reactant and reagent feeds therein. The reactants include ethylene and alpha-olefins. The reagents fed to the fluidized-bed reactor include molecular hydrogen gas, an induced condensing agent (ICA), and a hafnocene-titanocene catalyst system.

[0045] In some embodiments, any compound, composition, formulation, mixture, or reaction product herein may not contain any of the chemical elements selected from the group consisting of H, Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, I, Cs, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, lanthanides, and actinides, except that chemical elements required for the compound, composition, formulation, mixture, or reaction product (e.g., Hf required for hafnocene) are not excluded.

[0046] Alternatively, different embodiments may be preceded. ASTM means ASTM International, West Conshohocken, Pennsylvania, USA, a standardization organization. IUPAC means International Union of Pure and Applied Chemistry (IUPAC Secretariat, Research Triangle Park, North Carolina, USA). Optional features are not required and allowances for choice may be given. Operable means functionally capable or effective. Optional features may be absent (or excluded), alternatively present (or included).

[0047] Alkyl: A monovalent radical of a saturated hydrocarbon, which may be straight-chained, branched-chained, or cyclic. Embodiments may be straight-chained C1 or higher or branched C3 or higher, or straight-chained C1 or higher or penultimate-branched C4 or higher, or straight-chained C1 or higher or penultimate-branched C4 or higher. Examples of penultimate-branched alkyls are 2-methylpropyl (C4), 3-methylbutyl (C5), 4-methylpentyl (C6), 5-methylhexyl (C7), 6-methylheptyl (C8), 7-methyloctyl (C9), and 8-methylnonyl (C 10 ). Penultimate branched alkyl, also known as isoalkyl, has a methyl group attached to the penultimate carbon atom of the chain. Iso-(C3-C 10 ) alkyl (penultimate branch) includes 1-methylethyl, 2-methylpropyl, 3-methylbutyl, 4-methylpentyl, 5-methylhexyl, 6-methylheptyl, 7-methyloctyl, and 8-methylnonyl and has the formula -(CH2) i C(H)(CH3)2 alkyl, where each subscript i is an integer from 0 to 7. 10 ) Alkyl (straight chain) includes propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl and has the formula -(CH2) p It is an alkyl of CH3, where each subscript p is an integer from 2 to 9.

[0048] Alkylaluminoxane: Also referred to as alkylalumoxane. Partial hydrolysis product of trialkylaluminum compounds. Embodiments include (C1-C 10The alkylaluminoxane may be a (C1-C6) alkylaluminoxane, a (C1-C4) alkylaluminoxane, a (C1-C3) alkylaluminoxane, a (C1-C2) alkylaluminoxane, a methylaluminoxane (MAO), or a modified methylaluminoxane (MMAO). In some aspects, the alkylaluminoxane is MAO. In some embodiments, the alkylaluminoxane is supported on untreated silica, such as fumed silica. The alkylaluminoxane may be obtained from commercial suppliers or prepared by any suitable method. Suitable methods for preparing alkylaluminoxanes are well known. Examples of such preparation methods are described in U.S. Pat. Nos. 4,665,208, 4,952,540, 5,091,352, 5,206,199, 5,204,419, 4,874,734, 4,924,018, 4,908,463, 4,968,827, and 5,308,815. , 5,329,032, 5,248,801, 5,235,081, 5,157,137, 5,103,031, 5,391,793, 5,391,529, and 5,693,838, as well as European Patent Publication Nos. EP-A-0561476, EP-B1-0279 586, and EP-A-0 594-218, and PCT Patent Publication No. WO 94 / 10180.

[0049] Alkyl aluminum compounds: compounds having at least one alkyl-Al group. Mono- or di-(C1-C4) alkyl-containing aluminum compounds. Mono- or di-(C1-C4) alkyl-containing aluminum compounds can be used instead of or in combination with trialkyl aluminum. The mono- or di-(C1-C4) alkyl-containing aluminum compounds can each independently contain one or two (C1-C4) alkyl groups and two or one group, each independently, selected from chloride atoms and (C1-C4) alkoxides. The C1-C4 alkyls can each independently be methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, or 1,1-dimethylethyl. The (C1-C4) alkoxides can each independently be methoxide, ethoxide, propoxide, 1-methylethoxide, butoxide, 1-methylpropoxide, 2-methylpropoxide, or 1,1-dimethylethoxide. The mono- or di-(C1-C4) alkyl-containing aluminum compound may be diethylaluminum chloride (DEAC), diethylaluminum ethoxide (DEAE), ethylaluminum dichloride (EADC), or a combination or mixture of any two or more thereof. Trialkylaluminum: a compound of the formula (C1-C 10 ) alkyl) Al compounds, wherein (C1-C 10 ) alkyl groups are each independently selected. The trialkylaluminum can be trimethylaluminum, triethylaluminum ("TEAl"), tripropylaluminum, tris(1-methylethyl)aluminum, tributylaluminum, tris(2-methylpropyl)aluminum ("T2MPAl"), tripentylaluminum, trihexylaluminum ("TnHAl"), trioctylaluminum, or a combination of any two or more thereof. In some embodiments, the trialkylaluminum is T2MPAl, which is of the formula ((CH3)2C(H)CH2)3Al.

[0050] Alpha-olefins. Compounds of formula (I), H2C=C(H)-R(I), where R is a linear alkyl group. Embodiments include (C3-C 20 ) alpha-olefins. Compounds of formula (I): H2C=C(H)-R(I), where R is a straight chain (C1-C 18 ) alkyl group. (C1-C 18) An alkyl group is a monovalent unsubstituted saturated hydrocarbon having 1 to 18 carbon atoms. Examples of R are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl. In some embodiments, (C3-C 20 ) The alpha-olefin is 1-propene, 1-butene, 1-hexene or 1-octene; alternatively 1-butene, 1-hexene or 1-octene; alternatively 1-butene or 1-hexene; alternatively 1-butene or 1-octene; alternatively 1-hexene or 1-octene; alternatively 1-butene; alternatively 1-hexene; alternatively 1-octene; alternatively a combination of any two of 1-butene, 1-hexene and 1-octene.

[0051] Support Material: A porous particulate solid having pores and interior and exterior surfaces suitable for supporting a catalyst. Embodiments may be untreated or may be treated with a hydrophobizing agent. Untreated support materials may be porous untreated silica and may have a variety of surface areas, pore volumes, and average particle sizes. Each property is measured using conventional, known techniques. Untreated silica may be amorphous silica (not quartz) or high surface area amorphous silica (e.g., 500-1000 m). 2 / g), or high surface area fumed silica. Such silica is commercially available from a number of sources. The silica may be in the form of spherical particles obtained by a spray drying process. The untreated silica may be calcined (i.e., dehydrated) or uncalcined. The treated support material is made by treating the untreated support material with a hydrophobizing agent. The treated support material may have different surface chemistry and / or dimensions than the untreated support material.

[0052] Composition: Chemical composition. The arrangement, types, and ratios of atoms in a molecule, and the types and relative amounts of molecules in a substance or material.

[0053] Compound: a molecule or collection of molecules.

[0054] Concentration: A process for slowly increasing the mass or molar amount of the less volatile chemical component(s) per unit volume of a continuous mixture containing more volatile and less volatile chemical component(s). The process involves gradually removing chemical component(s) that are more volatile than the less volatile component(s) from the continuous mixture to obtain a concentrate having a greater mass or molar amount of the less volatile chemical component(s) per unit volume than the continuous mixture. The concentrate may be a precipitated solid.

[0055] Consisting essentially of, consist(s) essentially of, etc. Partial closure expressions are permitted, but exclude those that affect the basic and novel characteristics of what is being described. In some embodiments, any of the expressions "consisting essentially of" or "consists essentially of" may alternatively be replaced with the closure expressions "consisting of" or "consists of," respectively.

[0056] (Co)polymerization: Polymerizing a monomer or copolymerizing a monomer with at least one comonomer.

[0057] Density Test Method: Measured according to ASTM D792-13, Standard Test Method for Density and Specific Gravity (Relative Density) of Plastics by Displacement, Method B (for testing solid plastics in liquids other than water, e.g., liquid 2-propanol). Results are expressed in grams per cubic centimeter (g / cm). 3 ) units.

[0058] Dry. Anhydrous. Moisture content of 0 to less than 5 parts per million, based on total weight. The materials fed to the reactor(s) during the polymerization reaction are dry.

[0059] Effective amount: An amount sufficient to achieve a significant degree of result.

[0060] Ethylene: A compound with the formula H2C=CH2.

[0061] Feed. The amount of reactants and / or reagents added or "fed" to a reactor. Each feed can be independently continuous or intermittent and can be measured, e.g., metered, to control the amounts of the various reactants and reagents.

[0062] Film: Claimed film properties are measured on a monolayer film of 25 micrometer thickness.

[0063] Flow index (190°C, 21.6 kg, FI 21 Test Method: ASTM D1238-13 Standard Test Method for Melt Flow Rate of Thermoplastics by Extrusion Platometer using 190°C / 21.6 kilograms (kg). Results are reported in grams extracted per 10 minutes (g / 10 min).

[0064] Gel permeation chromatography (GPC) method: Weight average molecular weight test method: Using a chromatogram obtained with a high temperature gel permeation chromatography measuring instrument (HTGPC, Polymer Laboratories), M w , number average molecular weight (M n ), and M w / M n The HTGPC is equipped with a transfer line, a differential refractive index detector (DRI), and three Polymer Laboratories PLgel 10 μm Mixed-B columns, all housed in an oven maintained at 160 °C. The method uses a solvent composed of BHT-treated TCB with a nominal flow rate of 1.0 milliliters per minute (mL / min) and a nominal 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 reagent-grade 1,2,4-trichlorobenzene (TCB) and filtering the resulting solution through a 0.1 micrometer (μm) Teflon filter. The solvent is degassed with an in-line degasser before entering the HTGPC instrument. The column is calibrated with a series of monodisperse polystyrene (PS) standards. Separately prepare a known concentration of test polymer dissolved in a known amount of solvent by heating the solution at 160°C for 2 hours with continuous shaking. (All amounts are weighed.) A target solution concentration c of test polymer is set at 0.5 to 2.0 milligrams of polymer per milliliter solution (mg / mL). Lower concentrations c are used for polymers with higher molecular weights. Before each sample, purge the DRI detector. The instrument flow rate is then increased to 1.0 mL / min and the DRI detector is allowed to stabilize for 8 hours before injecting the first sample. Using the universal calibration relationship with the column calibration, the M w and M n Calculate the following formula:

number

number

number

[0334] to

[0341] on pages 24-25 of US 2006 / 0173123. To obtain a GPC chromatogram, plot dW / dLog(MW) on the y-axis against Log(MW) on the x-axis, where Log(MW) and dW / dLog(MW) are as defined above.

[0065] 1-Hexene ("C6"): H2C=C(H)(CH2)4CH3.

[0066] Hydrophobizing agent: An organic or organosilicon compound that forms a stable reaction product with the surface hydroxyl groups of the fumed silica. An embodiment can be a polydiorganosiloxane compound or organosilicon monomer containing a silicon-bonded leaving group (e.g., Si-halogen, Si-acetoxy, Si-oximo (Si-ON=C<), Si-alkoxy, or Si-amino group) that reacts with the surface hydroxyl groups of the untreated fumed silica to form an Si-O-Si bond, losing a water molecule as a by-product. Polydiorganosiloxane compounds, such as polydimethylsiloxane, contain backbone Si-O-Si groups, and the oxygen atoms can form stable hydrogen bonds with the surface hydroxyl groups of the fumed silica. Silicon-based hydrophobizing agents can be trimethylsilyl chloride, dimethyldichlorosilane, polydimethylsiloxane fluid, hexamethyldisilazane, octyltrialkoxysilane (e.g., octyltrimethoxysilane), and combinations of any two or more of these.

[0067] Induced Condensing Agent (ICA): An inert liquid useful for cooling materials in gas phase polymerization reactor(s) (e.g., fluidized bed reactors). 20 ) alkanes, or (C 11 ~C 20 ) Alkanes, or (C5-C 10 In some embodiments, the ICA can be a (C5-C 10 In some embodiments, the alkane is (C5-C 10The alkane is a pentane, such as normal pentane or isopentane, hexane, heptane, octane, nonane, decane, or a combination of any two or more thereof. In some embodiments, the ICA is isopentane (i.e., 2-methylbutane). Polymerization processes of the present invention using an ICA may be referred to herein as inert condensing mode operation (ICMO). Concentrations in the gas phase measured using gas chromatography by calibrating peak area percentages to mole percent (mol%) using gas mixture standards of appropriate gas phase components of known concentration. Concentrations may range from 1 to 10 mol%, or alternatively, from 3 to 8 mol%. The use of an ICA is optional. In some embodiments, including some inventive examples described below, an ICA is used. For example, in some embodiments of the method, a mixture of ICA and catalyst is prepared and fed to the polymerization reactor. In other embodiments of the method, the use of an ICA may be omitted, and the mixed, pre-blended, dry catalyst may be fed directly to the polymerization reactor without the ICA.

[0068] Inert: Generally, not (to a significant extent) reactive or not (to a significant extent) interfering in the polymerization reactions of this invention. The term "inert" as applied to the purge gas or ethylene feed means a molecular oxygen (O) content of 0 to less than 5 parts per million, based on the total weight of the purge gas or ethylene feed.

[0069] Melt Index (190°C, 2.16 kilograms (kg), "I2") Test Method: Measured in accordance with ASTM D1238-13 using the 190°C / 2.16 kg condition, formerly known as "Condition E," also known as I2. Results are reported in grams dissolved per 10 minutes (g / 10 min).

[0070] Polyethylene: A polymer or collection of polymers composed of the following units: (A) 100 mole percent (mol%) ethylene units (homopolymer), or (B) 50 to <100 mol%, alternatively 70 to <100 mol%, alternatively 80 to <100 mol%, alternatively 90 to <100 mol%, alternatively 95 to <100 mol% ethylene, and the remaining olefinic comonomer units, e.g., at least one (C3 to C 20 ) alpha-olefins, or (C4-C 20 ) derived from alpha-olefins.

[0071] Quartz: An unprocessed, nonporous crystalline form of silicon dioxide. Granular or bulk.

[0072] Silica. A particulate form of silicon dioxide that can be amorphous, crystalline, or gel-like. Includes fused quartz, fumed silica, silica gel, and silica aerogel. Hydrophobically pretreated fumed silica: A reaction product of contacting untreated fumed silica with a hydrophobizing agent to react with surface hydroxyl groups on the untreated fumed silica, thereby modifying the surface chemistry of the fumed silica to yield hydrophobically pretreated fumed silica. The hydrophobizing agent can be silicon-based. Untreated fumed silica: A pyrogenic silica produced in a flame. Consists of an amorphous silica powder made by fusing fine droplets into branched, chain-like, three-dimensional secondary particles that agglomerate into tertiary particles. Not quartz.

[0073] Spray drying: Rapid formation of a particulate solid containing the less volatile chemical component via drawing a bulk mixture of less volatile and more volatile chemical components through a nebulizer using hot gas. The particle size and shape of the particulate solid formed by spray drying can differ from that of the precipitated solid.

[0074] Support Material: A non-porous particulate solid suitable for receiving a catalyst on its outer surface.

[0075] System: an interrelated arrangement of various chemical components that forms a functioning whole.

[0076] Transportation: Movement from place to place, including reactor to reactor, tank to reactor, reactor to tank, manufacturing plant to storage facility, and vice versa. The present invention includes the following aspects. Section 1. 1. A hafnocene-titanocene catalyst system comprising a hafnocene catalyst and a titanocene catalyst, The hafnocene catalyst is ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl) dichloride / dibromide / dialkylhafnium with an activated alkylaluminoxane, wherein the subscript x is 1 or 2, the subscript y is 0, 1, or 2, and R 1 and R 2 are each independently methyl, ethyl, normal-(C3-C 10 ) Alkyl (straight chain), or iso-(C3-C 10 ) alkyl, the titanocene catalyst comprises the product of an activation reaction between bis(cyclopentadienyl)titanium dichloride and a trialkylaluminum; the hafnocene-titanocene catalyst system is characterized by a trialkylaluminum / Hf molar ratio of 0.1 to 50 and a Ti / Hf molar ratio of 0.1 to 5; Hafnocene-titanocene catalyst system. Section 2. Limitations (i) to (vi): (i) the subscript x is 1 and the subscript y is 0, (ii) the subscripts x and y are each 1; (iii) the subscript x is 1 and the subscript y is 2; (iv) the subscript x is 2 and the subscript y is 0; (v) the subscript x is 2 and the subscript y is 1; (vi) the subscript x is 2 and the subscript y is 2; Item 1. The hafnocene-titanocene catalyst system according to item 1, characterized by any one of the following: Section 3. Limited (i)~(iv): (i) The above ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl) dichloride / dibromide / dialkylhafnium is selected from bis(propylcyclopentadienyl)hafnium dichloride, bis(propylcyclopentadienyl)hafnium dibromide, bis(propylcyclopentadienyl)dimethylhafnium, and bis(propylcyclopentadienyl)diethylhafnium; (ii) the above ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl)dichloride / dibromide / dialkylhafnium is bis(propylcyclopentadienyl)hafnium dichloride, (iii) The above ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl)dichloride / dibromide / dialkylhafnium is bis(propylcyclopentadienyl)dimethylhafnium, (iv) The above ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl)dichloride / dibromide / dialkylhafnium is bis(propylcyclopentadienyl)diethylhafnium, Item 1 or 2, characterized by any one of the hafnocene-titanocene catalyst systems. Section 4. The trialkylaluminum is selected from the group consisting of the following (i) to (vii): (i) tri((C1-C8) alkyl)aluminum, (ii) tri((C3-C7) alkyl)aluminum, (iii) tri((C4-C6) alkyl)aluminum, (iv) tri((C4) alkyl)aluminum, (v) tri((C6) alkyl)aluminum, (vi) tri(2-methylpropyl)aluminum, and (vii) Tri(hexyl)aluminum Item 4. The hafnocene-titanocene catalyst system according to any one of items 1 to 3, wherein the hafnocene-titanocene catalyst system is selected from any one of the following: Section 5. Item 5. The hafnocene-titanocene catalyst system according to any one of items 1 to 4, wherein the hafnocene catalyst is supported on a support material. Section 6. 5. The hafnocene-titanocene catalyst system of any one of paragraphs 1 to 4, wherein the hafnocene catalyst, and optionally the titanocene catalyst, are spray dried onto a support material. Section 7. 1. A method for preparing a hafnocene-titanocene catalyst system comprising: The above ((R 1 ) x -cyclopentadienyl)((R 2 ) y -cyclopentadienyl) dichloride / dibromide / dialkylhafnium with an alkylaluminoxane and optionally a support material to obtain a hafnocene catalyst; then contacting the hafnocene catalyst with a titanocene catalyst prepared by the activation reaction of bis(cyclopentadienyl)titanium dichloride with a trialkylaluminum; thereby obtaining said titanium catalyst and said hafnocene-titanocene catalyst system. Section 8. A process for making a polyethylene composition, comprising: polymerizing ethylene and, optionally, zero, one, or more (C3-C 20 ) alpha-olefin is contacted with the hafnocene-titanocene catalyst system according to any one of items 1 to 7 to produce a polyethylene homopolymer or ethylene / (C3-C 20 ) causing a polymerization reaction to occur to obtain a polyethylene composition comprising an alpha-olefin copolymer, and said hafnocene-titanocene catalyst system, or a by-product thereof. Section 9. Limited (i)~(iv): (i) externally supplied molecular hydrogen gas (H2) is not added to the polymerization reactor and is not present during the contacting step of the process; (ii) the process further comprises adding an externally supplied H gas to the polymerization reactor during the contacting step of the process; (iii) The method comprises: 20 ) preparing the polyethylene homopolymer, which is free of alpha-olefins and contains units derived only from ethylene; (iv) The method further comprises the step of: 20 ) alpha-olefins, further comprising monomeric units derived from ethylene and one or more (C3 to C 20 ) alpha-olefin comonomer(s), each of which contains comonomer building blocks derived from ethylene / (C3-C 20 ) preparing an alpha-olefin copolymer; Item 9. The method according to item 8, characterized by any one of the following: Section 10. Item 10. The method according to item 8 or 9, comprising gas phase polymerization in one, two, or more gas phase polymerization reactors under (co)polymerization conditions, optionally in the presence of additional external molecular hydrogen gas (H), and optionally in the presence of an induced condensing agent (ICA), thereby producing the polyethylene composition, wherein the (co)polymerization conditions include a reaction temperature of 60 to 120°C, a molar ratio of the molecular hydrogen gas to the ethylene of 0.00001 to 0.25, and a molar ratio of the comonomer to the ethylene of 0.001 to 0.20. Section 11. Prior to the contacting step, the method further comprises steps (i) to (iii): (i) premixing the hafnocene catalyst and the titanocene catalyst in separate mixing tanks to prepare a premixture thereof, aging the premixture for 2 hours to 7 days to prepare an aged premixture, and then feeding the aged premixture into the polymerization reactor; (ii) premixing the hafnocene catalyst and the titanocene catalyst together in a mixer to form an unaged premixture thereof, and feeding the unaged premixture to the polymerization reactor within 120 minutes of premixing; (iii) feeding the hafnocene catalyst and the titanocene catalyst separately through separate reactor inlets into the polymerization reactor, thereby preparing the hafnocene-titanocene catalyst system in situ within the polymerization reactor; Item 11. The method according to any one of items 8 to 10, further comprising any one of the following: Section 12. Item 12. A polyethylene composition produced by the method according to item 8, 9, 10, or 11. [Example]

[0077] Hafnocene Catalyst 1 (Hf1) Supported on Silica. A solution of methylalumoxane and hafnocene-ligand complex is formed by adding 11 milliliters (mL) of a 30 wt% solution of methylaluminoxane in toluene to 0.202 grams (g) of bis(n-propylcyclopentadienyl)hafnium dichloride in a vial. 40 mL of fresh toluene is added, and the resulting mixture is stirred at 25°C for 1 hour. The resulting solution is added to 10 g of Davison 948 silica that has been pre-dried at 600°C. The resulting slurry is stirred at 25°C for 1.5 hours. The slurry is then dried under vacuum at 65°C to yield silica-supported hafnocene catalyst 1 as a free-flowing powder.

[0078] Hafnocene catalyst 2 (Hf2) spray-dried on silica. A Buchi B-290 mini spray dryer was used, housed in a nitrogen-atmosphere glove box. The spray dryer temperature was set to 165°C and the outlet temperature to 60-70°C. Fumed silica (Cabosil TS-610, 3.2 g), MAO (10 wt%, 21 g) in toluene, and bis(propylcyclopentadienyl)dimethylhafnium (0.11 g) in toluene (72 g) were mixed. The resulting mixture was introduced into an atomizer, which then contacted a stream of hot nitrogen gas to generate droplets, which evaporated the liquid and produced a powder. The powder was separated from the gas mixture in a cyclone separator, and the hafnocene catalyst 2 spray-dried on silica was collected in a cone can as a powder (3.81 g).

[0079] Titanocene catalyst 1 (Ti1): Cp2TiCl2 (1.0 g) and T2MPAl (triisobutylaluminum, 20.1 mL, 1.0 M in toluene) were stirred with a magnetic stir bar for 30 minutes to give titanocene catalyst 1 as a toluene solution.

[0080] Invention Example 1 (IE1): Hafnocene-titanocene catalyst system 1. 150 mg of hafnocene catalyst 1 is added to a 40 mL vial. 0.05 mL of a solution of titanocene catalyst 1 is added to the hafnocene catalyst 1 in the vial. The contents are diluted with hexane (10 mL) and the diluted mixture is allowed to stand at room temperature for 1 hour. The resulting mixture is concentrated under vacuum to provide hafnocene-titanocene catalyst system 1 supported on silica as a solid material.

[0081] Inventive Example 2 (IE2): Hafnocene-titanocene catalyst system 2. 150 mg of hafnocene catalyst 1 is added to a 40 mL vial. 0.20 mL of a solution of titanocene catalyst 1 is added to the hafnocene catalyst 1 in the vial. The contents are diluted with hexane (10 mL) and the diluted mixture is allowed to stand at room temperature for 1 hour. The resulting mixture is concentrated under vacuum to give hafnocene-titanocene catalyst system 2 supported on silica as a solid material.

[0082] Inventive Example 3 (IE3): Hafnocene-titanocene catalyst system 3. 150 mg of hafnocene catalyst 1 is added to a 40 mL vial. 0.80 mL of a solution of titanocene catalyst 1 is added to the hafnocene catalyst 1 in the vial. The contents are diluted with hexane (10 mL) and the diluted mixture is allowed to stand at room temperature for 1 hour. The resulting mixture is concentrated under vacuum to provide hafnocene-titanocene catalyst system 3 as a solid material.

[0083] Inventive Example 4 (IE4): Hafnocene-Titanocene Catalyst System 4. A Buchi B-290 mini spray dryer was used, housed in a nitrogen-atmosphere glove box. The spray dryer temperature was set to 165°C and the outlet temperature to 60-70°C. Fumed silica (Cabosil TS-610, 3.2 g), MAO (10 wt.%, 21 g) in toluene, and bis(propylcyclopentadienyl)dimethylhafnium (0.11 g) in toluene (72 g) were mixed. To this mixture was added 0.53 g of titanocene catalyst 1. The resulting mixture was introduced into an atomizer, which then contacted a stream of hot nitrogen gas to form droplets, which evaporated the liquid and produced a powder. The powder was separated from the gas mixture in a cyclone separator, and the hafnocene-titanocene catalyst system 4 spray-dried on silica was collected in a cone can as a powder (3.61 g).

[0084] Inventive Example 5 (IE5): Hafnocene-titanocene catalyst system 5. The preparation of hafnocene-titanocene catalyst system 4 is repeated except that 1.11 g of titanocene catalyst 1 is used instead of 0.53 g of titanocene catalyst 1, and hafnocene-titanocene catalyst system 5 is spray dried onto silica and collected as a powder (3.76 g) in a corn can.

[0085] Inventive Example 6 (IE6): Hafnocene-titanocene catalyst system 6. The preparation of hafnocene-titanocene catalyst system 4 is repeated except that 2.18 g of titanocene catalyst 1 is used instead of 0.53 g of titanocene catalyst 1, and hafnocene-titanocene catalyst system 6 is spray dried onto silica and collected in a corn can as a powder (3.67 g).

[0086] Invention Example A (IE(A)): Slurry-phase copolymerization of ethylene and 1-hexene catalyzed by any one of the hafnocene-titanocene catalyst systems IE1-IE6 to yield an ethylene / 1-hexene copolymer composition. A 2-liter (L) stainless steel autoclave slurry-phase reactor equipped with a mechanical stirrer is used. The reactor is cycled through several heating and nitrogen purging steps to ensure the reactor is clean and under an inert nitrogen atmosphere. Approximately 1 L of liquid isobutane is added to the purged reactor at ambient temperature. 5 g of SMAO (silica-supported methylalumoxane) is added under nitrogen pressure as a scavenger. The reactor agitator is turned on and the rotation speed is set to 800 revolutions per minute (rpm). Molecular hydrogen and 1-hexene are added to the reactor as specified below. The reactor is heated to 80°C. Ethylene is added to achieve a differential pressure of 125 psi. Approximately 50 milligrams (mg) of hafnocene catalyst, and optionally titanocene catalyst (CpTiCl / TMPAl), are added to the reactor via a shot cylinder using nitrogen pressure, as specified below. Polymerization is allowed to proceed at 80°C, with ethylene being added continuously to maintain a constant pressure. After 1 hour, the reactor is vented and cooled to ambient temperature, and then opened to recover the ethylene / 1-hexene copolymer composition. The data are reported later in Tables 1-3.

[0087] Invention Example B (IE(B)): Gas-phase polymerization of ethylene and 1-hexene catalyzed by any one of the hafnocene-titanocene catalyst systems IE1-IE6 to yield an ethylene / 1-hexene copolymer composition. A 2-liter stainless steel autoclave gas-phase reactor equipped with a mechanical stirrer is used. The reactor is dried for 1 hour, and the dried reactor is charged with 400 g of NaCl and further dried by heating at 105°C under nitrogen for 30 minutes. 5 g of SMAO (silica-supported methylalumoxane) is then added under nitrogen pressure as a scavenger. After the SMAO addition, the reactor is sealed and the reactor contents are stirred. The reactor is charged with 1-hexene and, optionally, hydrogen, as specified below. The charged reactor is pressurized with ethylene (total pressure = 225 psi). The system is allowed to reach a steady state, and then approximately 20 mg of hafnocene catalyst and, optionally, titanocene catalyst (Cp2TiCl2 / T2MPAl) are charged to the reactor. The reactor temperature is brought to 80°C and maintained at 80°C throughout the experimental run. The C6 / C2 molar ratio and ethylene pressure are maintained constant. Polymerization is allowed to proceed for 60 minutes. The reactor is then cooled, then vented, and opened. The resulting contents are washed with water and then with methanol, and dried to obtain an ethylene / 1-hexene copolymer composition. The activity (kilograms of copolymer produced / grams of catalyst used per hour, kg / g-hr) is determined as the ratio of the polymer yield to the amount of catalyst added to the reactor. The molecular weight (Mw) is determined by GPC. The data are reported later in Table 4.

[0088] Comparative Example A (CE(A)): Repeat IE(A) except omit the titanocene catalyst. Data are reported in Tables 1-3.

[0089] Comparative Example B (CE(B)): Repeat IE(B) except omit the titanocene catalyst. Data are reported in Table 4.

[0090] In Tables 1-4, Ex. No. is the Example number. Catalyst system is the catalyst system, which is non-invention for Comparative Examples CE(A) and CE(B) and invention for Inventive Examples IE(A) and IE(B). Catalyst productivity (kg / g-hr) is the catalyst productivity in kilograms of polymer produced per gram of catalyst per hour, as described above. C6 = 1-hexene. H2 (L) is the amount of molecular hydrogen gas used, if any, in liters. Mw is the weight average molecular weight of the ethylene / 1-hexene copolymer composition produced, determined by GPC as described above. Mw / Mw(0) is the weight average molecular weight (Mw) of the ethylene / 1-hexene copolymer composition made, as determined by GPC as described above, divided by Mw(0), the weight average molecular weight of the polymer made according to CE(A) or CE(B), i.e., in the absence of titanocene catalyst, and is a way of normalizing the beneficial increases in Mw for the catalyst systems, methods, and copolymer compositions of this invention. Ti / Hf* is the weight (grams / gram) of Cp2TiCl2 divided by the weight of hafnocene catalyst. Al / Hf^ is the weight (grams / gram) of trialkylaluminum (e.g., T2MPAl) divided by the weight of hafnocene catalyst.

[0091] [Table 1]

[0092] As shown in Table 1, the hafnocene-titanocene catalyst system and related slurry phase polymerization process of the present invention produced ethylene / alpha-olefin copolymer compositions with increased weight average molecular weight (Mw) compared to comparative catalyst systems and processes having a hafnocene catalyst but lacking or not including a titanocene catalyst.

[0093] [Table 2]

[0094] As shown in Table 2, the hafnocene-titanocene catalyst systems IE1-IE3 of the present invention supported on silica and the associated slurry phase polymerization processes produced ethylene / alpha-olefin copolymer compositions with increased weight average molecular weights (Mw) compared to comparative catalyst systems and processes having a hafnocene catalyst but lacking or not including a titanocene catalyst.

[0095] [Table 3]

[0096] As shown in Table 3, the hafnocene-titanocene catalyst system of the present invention and the associated slurry phase polymerization process, in which the hafnocene catalyst and titanocene catalyst were co-spray dried onto silica, produced ethylene / alpha-olefin copolymer compositions with increased weight average molecular weight (Mw) compared to comparative catalyst systems and processes having a hafnocene catalyst but lacking or not including a titanocene catalyst.

[0097] [Table 4]

[0098] As shown in Table 4, the hafnocene-titanocene catalyst system and associated gas phase polymerization process of the present invention produced ethylene / alpha-olefin copolymer compositions with increased weight average molecular weight (Mw) compared to comparative catalyst systems and processes having a hafnocene catalyst but lacking or not including a titanocene catalyst.

[0099] Invention Example C1 (Prophetic): Hafnocene and titanocene catalysts are fed separately into a batch reactor to prepare a hafnocene-titanocene catalyst system in situ, followed by polymerization (IE(C1s)). A 2-liter (L) stainless steel autoclave slurry-phase reactor equipped with a mechanical stirrer is used. The reactor is cycled through several heating and nitrogen purging steps to ensure the reactor is clean and under an inert nitrogen atmosphere. Approximately 1 L of liquid isobutane is added to the purged reactor at ambient temperature. 5 g of SMAO (silica-supported methylalumoxane) is added under nitrogen pressure as a scavenger. The reactor agitator is turned on and the rotation speed is set to 800 revolutions per minute (rpm). Molecular hydrogen and 1-hexene are added to the reactor as specified below. The reactor is heated to 80°C. Ethylene is added to achieve a differential pressure of 862 kPa (125 psi). Titanocene catalyst (Cp2TiCl2 / T2MPAl) is added to the reactor (if necessary) as specified below, and then approximately 50 milligrams (mg) of hafnocene catalyst is added separately to the reactor. Polymerization is allowed to proceed at 80°C, and ethylene is added continuously to maintain a constant pressure. After 1 hour, the reactor is vented and cooled to ambient temperature, and then the reactor is opened to recover the ethylene / 1-hexene copolymer composition. The predicted results are shown below in Table 5.

[0100] Inventive Example C2 (Prophetic): A hafnocene catalyst and a titanocene catalyst are premixed in a mixer to obtain an unaged premixture, which is then fed to a batch reactor for subsequent polymerization (IE(C2p)). A 2 L stainless steel autoclave slurry-phase reactor equipped with a mechanical stirrer is used. The reactor is cycled through several heating and nitrogen purging steps to ensure the reactor is clean and under an inert nitrogen atmosphere. Approximately 1 L of liquid isobutane is added to the purged reactor at ambient temperature. 5 g of SMAO (silica-supported methylalumoxane) is added under nitrogen pressure as a scavenger. The reactor agitator is turned on and set to a rotation speed of 800 rpm. Molecular hydrogen and 1-hexene are added to the reactor as specified below. The reactor is heated to 80°C. Ethylene is added to achieve a differential pressure of 862 kPa (125 psi). Approximately 50 mg of hafnocene catalyst and an amount of titanocene catalyst (Cp2TiCl2 / T2MPAl) (the latter amount is indicated later by the Ti / Hf* and Al / Hf^ ratios in Table 5) are premixed together for 30 minutes, and the resulting unaged premix is ​​then added to the reactor. Polymerization is allowed to proceed at 80°C, with ethylene being added continuously to maintain a constant pressure. After 1 hour, the reactor is vented and cooled to ambient temperature, and then the reactor is opened to recover the ethylene / 1-hexene copolymer composition. The expected results are shown in Table 5 below.

[0101] Comparative Examples C (CE(C)1-CE(C)6): IE(C) is repeated except that the titanocene catalyst is omitted. The data are reported in Table 4 below.

[0102] [Table 5]

[0103] As shown in Table 5, an increase in polymer Mw is predicted by introducing the titanocene catalyst compared to the comparative example, regardless of whether the hafnocene and titanocene catalysts are added to the reactor separately or premixed for a period of time and then added to the reactor together as a premix. The embodiment in which the hafnocene and titanocene catalysts are added to the reactor separately at the same Ti / Hf* and Al / Hf^ ratios is predicted to beneficially achieve higher catalyst productivity. This trend is predicted regardless of whether the polymerization reaction is carried out in the presence of comonomer (C6) without added H2, or in the absence of comonomer (C6) without added H2, or in the presence of comonomer with added H2.

[0104] Comparative Example (D) (Prophetic) Gas-Phase Fluidized-Bed Pilot Plant Reactor, Hafnocene Catalyst, No Titanocene Catalyst, Polymerizing Ethylene and 1-Hexene, Continuous Feed (CE(D)). A syringe pump is used to feed a Hf2 catalyst slurry in mineral oil into the reactor through a catalyst injection line containing a helical static mixer. After the catalyst injection line and before the helical static mixer, 1.4 kg per hour (3 pounds per hour (lb / hr)) of isopentane is added to the catalyst injection line. After the helical static mixer, nitrogen is added to the injection line at 2.3 kg / hr (5 lb / hr). An additional 1.8 kg / hr (4 lb / hr) of nitrogen and 3.2–3.6 kg / hr (7–8 lbs / hr) of isopentane are used through the outer tube to inject the slurry catalyst from the catalyst injection line through the outer tube or shroud into the reactor. After equilibrium was reached, polymerization was carried out under the respective conditions shown later in Table 6. Polymerization was initiated by continuously feeding the Hf2 catalyst in slurry, along with ethylene and 1-hexene, to a fluidized bed of polyethylene granules. Hydrogen gas was not fed to the reactor; however, hydrogen was generated in situ during polymerization. Inert gas, nitrogen, and isopentane made up the remaining pressure in the reactor. Ethylene / 1-hexene copolymer product was continuously removed from the reactor to maintain a constant bed weight of granules in the reactor. The predicted results are shown later in Table 6.

[0105] Invention Example (D1) (Prophetic) Gas-phase fluidized bed pilot plant reactor, hafnocene and titanocene catalysts, separately fed to the reactor to create a hafnocene-titanocene catalyst system in situ, polymerizing ethylene and 1-hexene, continuous feed (IE(D1s)). The procedure of CE(D) is repeated except that an isopentane solution of titanocene catalyst Ti1 is also added directly to the reactor via a separate injection line (IE(D1s)). See Table 6 for predicted results.

[0106] Inventive Example (D2) (Prophetic) A gas-phase fluidized-bed pilot plant reactor polymerized ethylene and 1-hexene using hafnocene and titanocene catalysts. The hafnocene and titanocene catalysts were premixed in an in-line mixer to form an immature premix, and the immature premix was fed to the reactor in less than 5 minutes (approximately 1 minute). The procedure of CE(D) was repeated, except that an isopentane solution of titanocene catalyst Ti1 was added to the feed line just before the in-line spiral static mixer to form a premix with Hf2, and the premix was fed to the reactor (IE(D2p)). The predicted results are shown below in Table 6.

[0107] Invention Example (D3) (Prophetic) Gas-phase fluidized-bed pilot plant reactor, hafnocene and titanocene catalysts, premixed in a batch mixer to form a premix, premix aged for two days, then fed the resulting aged premix to the reactor, polymerizing ethylene and 1-hexene, continuous feed (IE(D1s)). The procedure of CE(D) is repeated, except that an isopentane solution of titanocene catalyst Ti1 and Hf2 are first mixed in a mixer to form a premix, the premix is ​​aged for two days, and the aged premix is ​​fed to the reactor (IE(D3a)). The predicted results are shown in Table 6 below.

[0108] [Table 6]

[0109] As shown in Table 6 for continuous polymerization operation, a lower melt flow rate FI was obtained when a titanocene hydrogenation catalyst was used. 21 Ethylene / 1-hexene copolymers with higher (higher molecular weight) are produced at lower production rates. Surprisingly, both the catalyst mixing mode (IE(D1s) in which the hafnocene and titanocene catalysts are added separately to the reactor, and the in-line premixing of these catalysts (IE(D2p)) show benefits over the premix / aging mode (IE(D3a)). These benefits include the increased ability of IE(D1s) and IE(D2p) to remove H2 evolved within the polymerization reactor compared to the ability of IE(D3a) to remove evolved H2. This increased ability to remove H2 allows the polymerization to proceed at a lower FI for a given set of reactor conditions. 21 The benefits also include IE(D1s) having higher catalyst productivity than IE(D2p). The separate addition mode (IE(D1S)) advantageously allows for the production of a product resin having a FI of the copolymer product made using catalyst premix / maturation (IE(D3a)). 21 The FI of the copolymer product is lower than 21 The in-line mixing mode (IE(D2p)) has the highest production rate, and the lowest copolymer product FI is substantially lower than that obtained from the premix / aging mode (IE(D3a)). 21 (highest molecular weight).

Claims

1. 1. A process for making a polyethylene composition, comprising: polymerizing ethylene and, optionally, zero, one, or more comonomers (C ３ ~C ２０ ) alpha-olefins are contacted with a hafnocene-titanocene catalyst system to produce polyethylene homopolymers or ethylene / (C ３ ~C ２０ ) causing a polymerization reaction to occur to obtain a polyethylene composition comprising an alpha-olefin copolymer and said hafnocene-titanocene catalyst system, or a by-product thereof; prior to said contacting step, feeding said hafnocene catalyst and said titanocene catalyst separately through separate reactor inlets to said polymerization reactor, thereby preparing said hafnocene-titanocene catalyst system in situ within said polymerization reactor; the hafnocene-titanocene catalyst system comprises a hafnocene catalyst and a titanocene catalyst, The hafnocene catalyst is ((R １ ) ｘ -cyclopentadienyl) ((R ２ ) ｙ -cyclopentadienyl) with an alkylaluminoxane, wherein the subscript x is 1 or 2, the subscript y is 0, 1, or 2, and R １ and R ２ are each independently methyl, ethyl, normal-(C ３ ~C １０ ) alkyl (straight chain), or iso-(C ３ ~C １０ ) alkyl, the titanocene catalyst comprises the product of the activation reaction of bis(cyclopentadienyl)titanium dichloride with a trialkylaluminum; the hafnocene-titanocene catalyst system is characterized by a trialkylaluminum / Hf molar ratio of 0.1 to 50 or 162.49, and a Ti / Hf molar ratio of 0.1 to 5, 8.12, or 32.47; Method for making a polyethylene composition.

2. (i) Externally supplied molecular hydrogen gas (H ２ ) is not added to the polymerization reactor and is not present during the contacting step of the process; or (ii) the method further comprises the step of contacting an externally supplied H ２ further comprising adding a gas to the polymerization reactor. The method of claim 1.

3. (iii) The method comprises using as a comonomer (C ３ ~C ２０ ) preparing said polyethylene homopolymer containing constitutional units derived only from ethylene, without containing any alpha-olefin; or (iv) the method further comprises the step of: ３ ~C ２０ ) alpha-olefins, further comprising monomeric units derived from ethylene, and one or more (C ３ ~C ２０ ) alpha-olefin comonomers, ３ ~C ２０ ) preparing an alpha-olefin copolymer; The method according to claim 1 or 2.

4. Optionally, additional external molecular hydrogen gas (H ２ 4. The process according to claim 1, comprising gas phase polymerization in one, two or more gas phase polymerization reactors under (co)polymerization conditions in the presence of a comonomer (CO), optionally in the presence of an induced condensing agent (ICA), thereby making the polyethylene composition, wherein the (co)polymerization conditions comprise a reaction temperature of from 60 to 120°C, a molar ratio of the molecular hydrogen gas to the ethylene of from 0.00001 to 0.25, and a molar ratio of the comonomer to the ethylene of from 0.001 to 0.

20.

5. Limitations (i) to (vi): (i) the subscript x is 1 and the subscript y is 0; (ii) the subscripts x and y are each 1; (iii) the subscript x is 1 and the subscript y is 2; (iv) the subscript x is 2 and the subscript y is 0; (v) the subscript x is 2 and the subscript y is 1; (vi) the subscript x is 2 and the subscript y is 2; The method according to any one of claims 1 to 4, characterized by any one of the following:

6. The above ((R １ ) ｘ -cyclopentadienyl) ((R ２ ) ｙ At least one of hafnium dichloride, hafnium dibromide, and dialkylhafnium (-cyclopentadienyl) is selected from the group consisting of hafnium dichloride, hafnium dibromide, and dialkylhafnium (-cyclopentadienyl) and hafnium dibromide, and at least one of the hafnium dichloride, hafnium dibromide, and dialkylhafnium (-cyclopentadienyl) is selected from the group consisting of hafnium dichloride, (i) selected from bis(propylcyclopentadienyl)hafnium dichloride, bis(propylcyclopentadienyl)hafnium dibromide, bis(propylcyclopentadienyl)dimethylhafnium, and bis(propylcyclopentadienyl)diethylhafnium; (ii) bis(propylcyclopentadienyl)hafnium dichloride; (iii) bis(propylcyclopentadienyl)dimethylhafnium; (iv) bis(propylcyclopentadienyl)diethylhafnium; The method according to any one of claims 1 to 5, characterized by any one of the following:

7. The trialkylaluminum is selected from the group consisting of the following (i) to (vii): (i) Bird ((C １ ~C ８ ) alkyl) aluminum, (ii) Tri((C ３ ~C ７ ) alkyl) aluminum, (iii) Tri((C ４ ~C ６ ) alkyl) aluminum, (iv) Tri((C ４ ) alkyl) aluminum, (v) Bird ((C ６ ) alkyl) aluminum, (vi) tri(2-methylpropyl)aluminum, and (vii) tri(hexyl)aluminum The method according to any one of claims 1 to 6, wherein the method is selected from any one of the following:

8. The process of any one of claims 1 to 7, wherein the hafnocene catalyst is supported on a support material.

9. A method according to any one of claims 1 to 7, wherein the hafnocene catalyst, and optionally the titanocene catalyst, are spray dried onto a support material.

Images