BR112020018781B1 - SPRAY DRY ZIRCONOCENE CATALYST SYSTEM, METHOD FOR MAKING A SPRAY DRY ZIRCONOCENE CATALYST SYSTEM AND METHOD FOR MAKING A POLYETHYLENE COMPOSITION - Google Patents

Abstract

A spray-dried zirconocene catalyst system comprising a zirconocene catalyst and a hydrophobic fumed silica, which supports the zirconocene catalyst. A spray drying method to do the same. Polyolefins; methods for producing and using them; and articles containing the same.

Description

FIELD

[0001] Metallocene catalyst system, methods of making and using the same, polyolefins and films.

INTRODUCTION

[0002] A supported metallocene catalyst system comprises a metallocene catalyst disposed on surfaces of a carrier material that is a divided inorganic solid. The supported metallocene catalyst system can be made by a concentration method or a filtration method. These methods precipitate a metallocene catalyst either within pores of the porous carrier material or on the outer surface of the nonporous carrier material. The concentration method comprises steps of mixing a metallocene procatalyst, an activator and the carrier material in a hydrocarbon solvent to make the metallocene catalyst in situ and giving a suspension of the carrier material in a solution of the metallocene catalyst in the solvent. of hydrocarbon and concentrate the suspension (removing the hydrocarbon solvent from the carrier material and metallocene catalyst) to collect the supported metallocene catalyst system. The filtration method comprises steps of mixing a metallocene procatalyst, an activator and the carrier material in a hydrocarbon solvent to make the metallocene catalyst in situ and giving a suspension of the carrier material in a solution of the metallocene catalyst in the solvent. of hydrocarbon and filter the suspension to collect the supported metallocene catalyst system.

[0003] Patents and publications in the field include US 5,120,867; US 5,446,649; US 5,916,982; US 6,242,545 B1; US 6,258,903 B1; US 6,476,171 B2; US 6,982,236 B2; US 7,662,894 B2; US 8,207,280 B2; US 8,247,588 B2; US 8,404,612 B2; US 8,497,330 B2; US 9,045,569 B2; US 2006/0293470 A1; US 2015/0232589 A1; and US 2017/0114199 A1.

[0004] R. Quijada, et al. report an EtInd2ZrCl2 or Ind2ZrCl2 metallocene supported on a calcined porous silica ES-70 or EP-10 or a calcined non-porous fumed silica AEROSIL 200 (Study of metallocene supported on porous and nonporous silica for the polymerization of ethylene, Catalysis Letters, 1997, vol .46, pages 107-112). Commercial silicas ES-70 and EP-10 (Crossfield Catalyst) and AEROSIL 200 silica (Evonik) are hydrophilic and were calcined before use with the metallocene EtInd2ZrCl2 or Ind2ZrCl2. R. Quijada et al. made their metallocenes supported by modalities of the filtration method.

[0005] K. Soga, et al. report the activation of activated Cp2ZrCl2 metallocene supported on a calcined SiO2 #952 and then treated with Cl2Si(CH3)2 (Activation of SiO2-supported zirconocene catalysts by common trialkylaluminums, Makromol. Chem. 1993, vol. 194, pages 3499- 3504). Before use with the metallocene Cp2ZrCl2, Soga et al. calcined SiO2 #952 (Fuji Davison Co., Ltd.) and then treated the resulting calcined SiO2 #952 with Cl2Si(CH3)2 to give a treated calcined silica as a carrier material. Soga et al. made their metallocene supported by modalities of the filtration method.

[0006] Commercial metallocene catalysts include XCAT™ HP-100 and EZ-100 Metallocene Catalysts from Univation Technologies, LLC. Resins produced with XCAT™ Metallocene Catalysts exhibit remarkable toughness, clarity and improved processability. XCAT™ Metallocene Catalysts offer the ability to control the molecular structure of the polymer, allowing independent manipulation of MWD, CD and long chain branching. This results in resins with excellent clarity, controllable peak melting points, lower heat seal initiation temperatures and a wide sealing range. Resins made with XCAT™ Metallocene Catalysts have narrow compositional distributions, resulting in superior toughness, high hot tackiness and faster line speeds.

SUMMARY

[0007] We recognize and devise a technical solution to one or more of the introduced problems of: (a) how to increase the catalyst activity of a supported metallocene catalyst; (b) how to narrow molecular weight distribution (MWD) of an ethylene-based polymer (e.g., an ethylene/alpha-olefin copolymer); (c) how to narrow comonomer composition distribution (CCD) of an ethylene/alpha-olefin copolymer; (d) how to increase the strength (melt) of an ethylene-based polymer (e.g., an ethylene/alpha-olefin copolymer); and (e) how to improve shrinkage properties of a film of an ethylene-based polymer (e.g., an ethylene/alpha-olefin copolymer). The technical solution provides an alternative to filtered or precipitated supported metallocene catalysts.

[0008] One embodiment includes a spray-dried zirconocene catalyst system comprising a zirconocene catalyst and a hydrophobic fumed silica, which supports the zirconocene catalyst. A spray drying method to do the same is also included.

[0009] Also included is a process for polymerizing an olefin monomer, such as ethylene, and, optionally, an olefin comonomer, such as an alpha-olefin, with the spray-dried zirconocene catalyst system to make a polyolefin, such as an ethylene-based polymer, such as a polyethylene homopolymer or an ethylene/alpha-olefin copolymer. The zirconocene catalyst of the spray-dried zirconocene catalyst system can have high catalyst productivity relative to the catalyst productivity of a comparative filtered or concentrated zirconocene catalyst system that was prepared by a filtration or concentration method, respectively, in instead of the present spray drying method. Also included is polyolefin made by the inventive polymerization process. Ethylene-based polymer embodiments may have a narrow molecular weight distribution (MWD) and, for ethylene/alpha-olefin copolymers, a narrow comonomer composition distribution (CCD) with respect to MWD or CCD, respectively, of a comparative polyolefin made by a comparative polymerization process using the comparative concentrated or filtered zirconocene catalyst system instead of the spray-dried zirconocene catalyst system. Without wishing to be bound by theory, it is believed that embodiments of the ethylene-based polymer having a narrower MWD and/or narrower CCD may, all other things being equal, decrease optical haze and optical glare and may increase the tear resistance of films made from the same and composed of the same. Without wishing to be bound by theory, it is believed that polyolefin, such as ethylene-based polymer may have high melt strength and/or high strength (solid phase) and a film thereof may have improved shrinkage properties relative to to those of polyolefin or comparative film, respectively. Additional embodiments are a method for forming films of the inventive polyolefin and films made therefrom. Inventive films are useful in many different applications. The film can be particularly useful in shrink-winding applications.

DETAILED DESCRIPTION

[0010] Certain inventive embodiments are described below as numbered aspects to facilitate cross-referencing. Additional embodiments are described elsewhere in this document.

[0011] Aspect 1. Spray-dried zirconocene catalyst system comprising a zirconocene catalyst and a hydrophobic fumed silica, which transports or supports the zirconocene catalyst, wherein the zirconocene catalyst of the spray-dried zirconocene catalyst system is made from a reaction of an activator and a zirconocene procatalyst of formula (I), (II) or (III): a zirconocene procatalyst of formula (I): ((R1)x-cyclopentadienyl)(( R2)y-cyclopentadienyl)zirconium dichloride/dibromide/dialkyl (I), where the subscript x is an integer from 1 to 5; the subscript y is an integer from 0 to 5; and each R1 and R2 is independently methyl, ethyl, a normal-(C3-C10)alkyl (linear) or an iso-(C3-C10)alkyl; or a zirconocene procatalyst of formula (II): ((R3)z-(4,5,6,7-tetrahydroindenyl))((R2)y-cyclopentadienyl)zirconium dichloride/dibromide/dialkyl (II) , where the subscript z is an integer from 0 to 3; the subscript y is an integer from 0 to 5; each R3 is H or R2; and each R2 is independently methyl, ethyl, a normal-(C3-C10)alkyl (linear) or an iso-(C3-C10)alkyl; or a zirconocene procatalyst of formula (III): ((R3)z-(4,5,6,7-tetrahydroindenyl))((R4)t-(4,5,6,7- tetra- hydroindenyl))zirconium dichloride/dibromide/dialkyl (III), wherein the subscript z is an integer from 0 to 3; the subscript t is an integer from 0 to 3; and each R3 and R4 is independently H, methyl, ethyl, or a normal (C3-C10)alkyl (linear); or each of the subscripts z and t independently is an integer from 1 to 3 and a first R3 is in position 1 of the 4,5,6,7-tetrahydroindenyl to which it is attached and a first R4 is in position 1 of 4, 5,6,7-tetrahydroindenyl to which it is bonded and the first R3 is covalently bonded to the first R4 to form a divalent bridging group of formula Si(R5)2, wherein each R5 is independently a (C1-C3 )alkyl. The 1 position of 4,5,6,7-tetrahydroindenyl is on the cyclopentadienyl ring where, if protonated, it would become the CH2 carbon atom in the 5-membered ring of 4,5,6,7-tetrahydroindene. The term “dichloride/dibromide/dialkyl” means a dichloride, a dibromide or a dialkyl. In some aspects, the zirconocene procatalyst used in the reaction with the activator to make the zirconocene catalyst is the zirconocene procatalyst of formula (I) or (II), alternatively formula (I) or (III), alternatively formula (II) or (III), alternatively formula (I), alternatively formula (II), alternatively formula (III).

[0012] Aspect 2. The spray-dried zirconocene catalyst system of aspect 1 comprising a zirconocene catalyst and a hydrophobic fumed silica, which supports the zirconocene catalyst, wherein the zirconocene catalyst of the spray-dried zirconocene catalyst system spraying is made from a reaction of an activator and a zirconocene procatalyst comprising the zirconocene procatalyst of formula (I): a ((R1)x-cyclopentadienyl)((R2)y-cyclopentadienyl)zirconium dichloride/dibromide /dialkyl (I), where the subscript x is an integer from 1 to 5; the subscript y is an integer from 0 to 5; and each R1 and R2 is independently methyl, ethyl, a normal-(C3-C10)alkyl (linear) or an iso-(C3-C10)alkyl.

[0013] Aspect 3. The spray-dried zirconocene catalyst system of aspect 1 or 2, wherein the zirconium procatalyst is characterized by any of the limitations (i) to (x): (i) subscript x is 1 and subscript y is 0, (ii) subscripts x and y are each 1, (iii) subscript x is 1 and subscript y is 2, (iv) subscript x is 2 and subscript y is 0, (v) subscript x is 2 and subscript y is 1, (vi) subscript x is 2 and subscript y is 2, (vii) subscript x is 1 or 2 and subscript y is 0, 1 or 2, (viii) subscript x is 3 and subscript y is 1 , (ix) subscript x is 4 and subscript y is 1, and (x) subscript x is an integer from 1 to 4 and subscript y is 1 or 2. When the subscript y is 0, the ((R2)y-cyclopentadienyl ) is unsubstituted cyclopentadienyl. In some aspects, subscript y is 1 or 2, alternatively y is 1, alternatively y is 2. In some aspects, when R1 is methyl, subscript x is 3, 4 or 5.

[0014] Aspect 4. The spray-dried zirconocene catalyst system of any of aspects 1 to 3, wherein the zirconium procatalyst is characterized by any of the limitations (i) to (xLiii): (i) at least one of R1 and R2 is independently methyl; (ii) at least one of R1 and R2 is independently ethyl; (iii) at least one of R1 and R2 is independently a normal-(C3-C10)alkyl (linear); (iv) at least one of R1 and R2 is independently an iso-(C3-C10)alkyl; (v) at least one of R1 is independently a normal-(C3-C10)alkyl (linear) or an iso-(C3-C10)alkyl and at least one of R2 is independently a normal-(C3-C10)alkyl ( linear) or an iso-(C3-C10)alkyl; (vi) at least one of R1 is independently a normal-(C3-C10)alkyl (linear) and at least one of R2 is independently a normal-(C3-C10)alkyl (linear); (vii) at least one of R1 is independently an iso-(C3-C10)alkyl and at least one of R2 is independently an iso-(C3-C10)alkyl; (viii) the ((R1)x-cyclopentadienyl) and the ((R2)y-cyclopentadienyl) are different (for example, one is propylcyclopentadienyl and the other is cyclopentadienyl or methylcyclopentadienyl); (ix) ((R1)x-cyclopentadienyl) and ((R2)y-cyclopentadienyl) are the same (for example, both are propylcyclopentadienyl); (x) subscripts x and y are each 1 and each of R1 and R2 is the same; (xi) subscripts x and y are each 1 and each of R1 and R2 is the same normal-(C3-C10)alkyl; (xii) subscripts x and y are each 1 and each of R1 and R2 is the same normal-(C3-C4)alkyl; (xiii) subscripts x and y are each 1 and each of R1 and R2 is propyl; (xiv) the dichloride/dibromide/dialkyl is a dichloride or a dibromide, alternatively a dichloride; (xv) the dichloride/dibromide/dialkyl is a dialkyl, wherein each alkyl is independently a (C1-C10)alkyl, alternatively a (C2-C10)alkyl, alternatively a (C1-C4)alkyl, alternatively a (C2- C6)alkyl; (xvi) the dichloride/dibromide/dialkyl is a dialkyl and each alkyl independently is selected from methyl, ethyl, 1-methylethyl, propyl, butyl, 1-methylpropyl, and 2-methylpropyl; (xvii) the dichloride/dibromide/dialkyl is a dialkyl and each alkyl independently is selected from methyl, ethyl, propyl, and butyl; (xviii) the dichloride/dibromide/dialkyl is a dialkyl and each alkyl independently is selected from methyl, ethyl and propyl; (xix) dichloride/dibromide/dialkyl is a dialkyl and each alkyl independently is selected from methyl and propyl; (xx) the dichloride/dibromide/dialkyl is a dialkyl and each alkyl independently is selected from methyl and ethyl; (xxi) the dichloride/dibromide/dialkyl is a dialkyl and each alkyl is methyl; (xxii) the dichloride/dibromide/dialkyl is a dialkyl and each alkyl is ethyl; (xxiii) both (i) and any one of (xiv) to (xxii); (xxiv) both (ii) and any of (xiv) to (xxii); (xxv) both (iii) and any of (xiv) to (xxii); (xxvi) both (iv) and any of (xiv) to (xxii); (xxvii) both (v) and any of (xiv) to (xxii); (xxviii) both (vi) and any of (xiv) to (xxii); (xxix) both (vii) and any of (xiv) to (xxii); (xxx) both (viii) and any one of (xiv) to (xxii); (xxxi) both (ix) and any one of (xiv) to (xxii); (xxxii) both (x) and any one of (xiv) to (xxii); (xxxiii) both (xi) and any one of (xiv) to (xxii); (xxxiv) both (xii) and any of (xiv) to (xxii); (xxxv) both (xiii) and any of (xiv) to (xxii); (xxxvi) the zirconium procatalyst is ((R1)x-cyclopentadienyl)((R2)y-cyclopentadienyl)zirconium dichloride/dibromide/dialkyl selected from (tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconium dichloride/dibromide/dialkyl; (tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconium dichloride; (tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconium dibromide; (tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)dimethyl zirconium; bis(butylcyclopentadienyl)zirconium dichloride, bis(butylcyclopentadienyl)zirconium dibromide, bis(butylcyclopentadienyl)zirconium dimethyl, and bis(butylcyclopentadienyl)zirconium diethyl; (xxxvii) the ((R1)x-cyclopentadienyl)((R2)y-cyclopentadienyl)zirconium dichloride/dibromide/dialkyl is bis(butylcyclopentadienyl)zirconium dichloride; (xxxviii) the ((R1)x-cyclopentadienyl)((R2)y-cyclopentadienyl)zirconium dichloride/dibromide/dialkyl is bis(butylcyclopentadienyl)zirconium dimethyl; and (xxxix) the ((R1)x-cyclopentadienyl)((R2)y-cyclopentadienyl)zirconium dichloride/dibromide/dialkyl is bis(butylcyclopentadienyl)zirconium diethyl; (xL) the ((R1)x-cyclopentadienyl)((R2)y- cyclopentadienyl)zirconium dichloride/dibromide/dialkyl is selected from bis(1-methyl-3-butylcyclopentadienyl)zirconium dichloride, bis(1-methyl-3- butylcyclopentadienyl)zirconium dibromide, bis(1-methyl-3-butylcyclopentadienyl)zirconium dimethyl, and bis(1-methyl-3-butylcyclopentadienyl)zirconium diethyl; (xLi) the ((R1)x-cyclopentadienyl)((R2)y-cyclopentadienyl)zirconium dichloride/dibromide/dialkyl is bis(1-methyl-3-butylcyclopentadienyl)zirconium dichloride; (xLii) the ((R1)x-cyclopentadienyl)((R2)y-cyclopentadienyl)zirconium dichloride/dibromide/dialkyl is bis(1-methyl-3-butylcyclopentadienyl)zirconium dimethyl; and (xLiii) the ((R1)x-cyclopentadienyl)((R2)y-cyclopentadienyl)zirconium dichloride/dibromide/dialkyl is bis(1-methyl-3-butylcyclopentadienyl)diethyl zirconium. Alternatively, subscript x is an integer from 1 to 4, subscript y is 1, R1 is methyl, and R2 is ethyl, propyl, or butyl. Dimethyl zirconium procatalysts are preferred over diethyl zirconium procatalysts.

[0015] Aspect 5. The spray-dried zirconocene catalyst system of aspect 1 comprising a zirconocene catalyst and a hydrophobic fumed silica supporting the zirconocene catalyst, wherein the zirconocene catalyst of the spray-dried zirconocene catalyst system is made from a reaction of an activator and a zirconocene procatalyst comprising the zirconocene procatalyst of formula (III): ((R3)z-(4,5,6,7-tetrahydroindenyl))(( R4)t-(4,5,6,7-tetrahydroindenyl))zirconium dichloride/dibromide/dialkyl (III), where subscript z is an integer from 0 to 3; subscript t is an integer from 0 to 3; and each R3 and R4 is independently H, methyl, ethyl, or a normal (C3-C10)alkyl (linear); or each of the subscripts z and t independently is an integer from 1 to 3 and a first R3 is in position 1 of the 4,5,6,7-tetrahydroindenyl to which it is attached and a first R4 is in position 1 of 4, 5,6,7-tetrahydroindenyl to which it is bonded and the first R3 is covalently bonded to the first R4 to form a divalent bridging group of formula Si(R5)2, wherein each R5 is independently a (C1-C3 )alkyl.

[0016] Aspect 6. The spray-dried zirconocene catalyst system of aspect 5, wherein each of the subscripts z and t is 1 and a first (and only) R3 is in position 1 of the 4,5,6,7-tetra -hydroindenyl to which it is bonded and the first (and only) R4 is in position 1 of the 4,5,6,7-tetrahydroindenyl to which it is bonded and the first R3 is covalently bonded to the first R4 to form the group divalent bridge with the formula Si(R5)2, where each R5 is methyl. To remove all doubts, the 4,5,6,7-tetrahydroindenyl linked to the first R3 and the 4,5,6,7-tetrahydroindenyl linked to the first R4 are different. The zirconocene procatalyst of formula (III) of this aspect is herein called bis(4,5,6,7-tetrahydroindenyl)zirconium dichloride/dibromide/dialkyl with dimethyl-1,1'-silanilene bridge. In some aspects the zirconocene procatalyst of formula (III) of this aspect is bis(4,5,6,7-tetrahydroindenyl)zirconium dichloride with a dimethyl-1,1'-silanilene bridge, alternatively bis(4, 5,6,7-tetrahydroindenyl)zirconium dibromide with dimethyl-1,1'-silanilene bridge, bis(4,5,6,7-tetrahydroindenyl)zirconium dialkyl with dimethyl-1,1'-bridge silanylene, alternatively dimethyl bis(4,5,6,7-tetrahydroindenyl)zirconium with dimethyl-1,1'-silanilene bridge.

[0017] Aspect 7. The spray dried zirconocene catalyst system of any of aspects 1 to 6 made by mixing the activator, zirconocene procatalyst and hydrophobic fumed silica in a hydrocarbon solvent to make a suspension of the silica hydrophobic pyrogenic in a solution of the zirconocene catalyst, which is made in situ, in the hydrocarbon solvent; and spray-drying the suspension to give the spray-dried zirconocene catalyst system.

[0018] Aspect 8. The spray-dried zirconocene catalyst system of any one of aspects 1 to 7, wherein the hydrophobic fumed silica is made by contacting an untreated fumed silica, having surfaces containing silicon-bonded hydroxyl groups (SiOH groups ), with a silicon-based hydrophobic agent, containing on average per molecule one or more functional groups reactive with a SiOH group, to give hydrophobic fumed silica. Untreated fumed silica may be uncalcined. The silicon-based hydrophobic agent may be selected from (CH3)2SiCl2, a polydimethylsiloxane, hexamethyldisilazane (HMDZ), and a (C1-C10)alkylSi((C1-C10)alkoxy)3 (e.g., an octyltrialkoxysilane, such as octyltriethoxysilane, i.e. CH3(CH2)7Si(OCH2CH3)3).

[0019] Aspect 9. The spray-dried zirconocene catalyst system of any one of aspects 1 to 8, wherein the activator is an alkylaluminum, an alkylaluminoxane or a combination thereof. The activator may be a methylaluminoxane.

[0020] Aspect 10. The spray-dried zirconocene catalyst system of any of aspects 1 to 9, further comprising any of limitations (i) to (vii): (i) an olefin monomer (e.g., ethylene ) or alpha-olefin; (ii) a polyolefin; (iii) a metal carboxylate salt, wherein the metal carboxylate salt is represented by the formula: MQm(O2CR)n, where M is a metal atom from Group 2 or Group 13 of the Periodic Table of the Elements; Q is a halogen, hydroxy, alkyl, alkoxy, aryloxy, siloxy, silane or sulfonate group; R is a (C5-C30)hydrocarbyl; subscript m is an integer from 0 to 3; subscript n is an integer from 1 to 4; and the sum of the subscripts m and n is equal to the valence of M; and (iv) both (i) and (ii); (v) both (i) and (iii); (vi) both (ii) and (iii); and (vii) each of (i) to (iii). In some aspects, 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, alternatively Al. In some aspects, Q is a halogen; alternatively hydroxy; alternatively alkyl, alkoxy or aryloxy; alternatively alkyl; alternatively alkoxy; alternatively aryloxy; alternatively siloxy or silane; alternatively siloxy; alternatively silane; alternatively sulfonate group. In some aspects, 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, alternatively 3. In some aspects, the subscript n is an integer from 1 to 3, alternatively 2 to 4, alternatively 1 or 2, alternatively 3 or 4, alternatively 1, alternatively 2, alternatively 3, alternatively 4. In some respects, the sum of the subscripts m and n is equal to the valence of M, which is equal to 2, alternatively 3. The spray-dried zirconocene catalyst system further comprising a polyolefin can be used as a seed bed in a gas phase polymerization reactor and process.

[0021] Aspect 11. A method for making a spray-dried zirconocene catalyst system, the method comprising contacting in a hydrocarbon solvent an activator with a zirconocene procatalyst as defined in any one of aspects 1 to 10 and a hydrophobic fumed silica and, optionally, a metal carboxylate salt of the formula: MQm(O2CR)n, wherein M, Q, R, subscript m and subscript n are as defined in aspect 10, to give a suspension of the hydrophobic fumed silica in a zirconocene catalyst solution, which is made in situ, in the hydrocarbon solvent and then spray-dry the suspension to give the spray-dried zirconocene catalyst system. The spray-dried zirconocene catalyst system made by the method may be that of any one of aspects 1 to 10. Contacting the activator with the zirconocene procatalyst includes contacting the zirconocene procatalyst with the activator. The in situ contacting and manufacturing step of the zirconocene catalyst can be performed under an inert gas atmosphere and in the absence or presence of the hydrophobic fumed silica to make the solution of the zirconocene catalyst in the hydrocarbon solvent. In method embodiments in which the contacting step is performed in the absence of the hydrophobic fumed silica, the method further comprises contacting the solution with the hydrophobic fumed silica to make the suspension. Contacting the solution with the fumed silica includes contacting the hydrophobic fumed silica with the solution. In method embodiments in which the contacting step is performed in the presence of the hydrophobic fumed silica, the contacting step may comprise contacting the activator with a mixture of the hydrophobic fumed silica and the zirconocene procatalyst in the hydrocarbon solvent; alternatively, contact the zirconocene procatalyst with a mixture of the hydrophobic fumed silica and the activator in the hydrocarbon solvent. The hydrocarbon solvent may be a saturated and/or aromatic hydrocarbon solvent, such as an alkane; a mixture of two or more alkanes; a mineral oil; an alkyl-substituted benzene, such as toluene, ethylbenzene or xylenes; or a mixture of two or more thereof.

[0022] Aspect 12. A method for making a polyethylene composition, the method comprising contacting ethylene (monomer) and optionally zero, one or more (C3-C20)alpha-olefins (comonomer(s)) with the catalyst system of spray-dried zirconocene of any one of aspects 1 to 10 or which is made by the method of aspect 11 in a polymerization reactor to generate a polymerization reaction giving a polyethylene composition comprising a polyethylene homopolymer or ethylene/(C3- C20)alpha-olefin, respectively, and the spray-dried zirconocene catalyst system or a byproduct thereof. Without wishing to be limited by theory, it is believed that the spray-dried zirconocene catalyst functions in the method to enhance or increase the rate of polymerization of the monomer and/or any comonomer(s). In some aspects, the method further comprises adding molecular hydrogen (H2) from an external source (outside the reactor) into the polymerization reactor, such as to control a property, e.g., I2, of the product polyethylene homopolymer or ethylene copolymer. /(C3-C20)alpha-olefin. The polymerization reaction is conducted during the contact step and under effective polymerization conditions. The polymerization reaction can be conducted in a gas phase or in a liquid phase. The liquid phase can be a paste phase or solution phase. In some aspects, the method comprises copolymerizing ethylene and one or more (C3-C20)alpha-olefins (comonomer(s)) to give the ethylene/(C3-C20)alpha-olefin copolymer composition, alternatively, the method comprises copolymerize ethylene and one or more (C4-C8) alpha-olefins (comonomer(s)) to give the ethylene/(C4-C8) alpha-olefin copolymer composition. The comonomeric constituent units derived from (C3-C20)alpha-olefin and the comonomeric constituent units derived from (C4-C8)alpha-olefin can be derived from 1-butene; alternatively, 1- hexene; alternatively, 1-octene; alternatively, a combination of two of the same. In some aspects, the method is free from any olefin polymerization catalyst other than the spray-dried zirconocene catalyst system. The method may comprise a gas phase polymerization optionally in the presence of added external molecular hydrogen gas (H2), optionally in the presence of an induced condensing agent (ICA); and in one, two or more gas phase polymerization reactors under (co)polymerization conditions, thereby making the polyethylene composition; wherein the (co)polymerization conditions comprise a reaction temperature of 70 degrees (°) to 110° Celsius (C.); alternatively 80° to 110° C.; a molar ratio of molecular hydrogen gas to ethylene (H2/C2 molar ratio) of > 0 to 0.1, alternatively of 0.0001 to 0.0050; and a molar ratio of comonomer to ethylene (comonomer/C2 molar ratio, i.e., Cx/C2 molar ratio, e.g., C6/C2 molar ratio) of 0.0001 to 0.10, alternatively 0.005 to 0.10, alternatively 0.15 to 0.050, alternatively 0.020 to 0.039.

[0023] Aspect 13. A polyethylene composition produced by the method of aspect 12. The polyethylene composition may be an ethylene-based polymer which may be a polyethylene homopolymer or an ethylene/(C3-C20)alpha copolymer. olefin.

[0024] Aspect 14. A manufactured article comprising a molded form of the polyethylene composition of aspect 13. The manufactured article can be selected from: coatings, films, sheets, extruded articles and injection molded articles. The manufactured article may be a coating layer (e.g., of a coated article), tube, film (e.g., blown film), agricultural film, food packaging, garment bags, grocery bags, heavy duty bags, industrial sheets, pallets and shrink wraps, bags, buckets, freezer containers, lids and toys.

[0025] Aspect 15. A film comprising the polyethylene composition of aspect 13.

[0026] The zirconocene catalyst of the spray-dried zirconocene catalyst system can have a higher catalyst productivity than a comparative spray-dried zirconocene catalyst system prepared using a hydrophilic silica, which is porous, instead of fumed silica hydrophobic, which is non-porous. Embodiments of the polyolefin, such as the ethylene-based polymer made by the inventive polymerization process, may have a narrower molecular weight distribution, and, for ethylene/alpha-olefin copolymers, a narrower comonomer composition distribution, than those of a comparative polyolefin made in a comparative polymerization process and reactor using the comparative spray-dried zirconocene catalyst system instead of the inventive spray-dried zirconocene catalyst system.

[0027] The manufactured article may be a film comprising, alternatively consisting essentially of, alternatively consisting of polyethylene composition. The inventive film made from polyolefin may have improved properties, such as improved (decreased) optical haze, improved (decreased) optical brightness, improved (increased) tear strength, improved shrinkage properties, or a combination of any two or more thereof. Enhanced shrinkage means the high ability of polyolefin molecules in the film to shrink or recoil when a small amount of heat (e.g. heated air) is applied. The greater the shrinkage under a given amount of applied heat, the more improved the shrinkage. This characteristic of the inventive polymers allows their use in shrink-wrapping applications, also known as shrink-wrapping applications. These applications include grouping beverage bottles into multipacks. Without wishing to be limited by theory, it is believed that the inventive polyolefin, formed (e.g., blown) into a film, is in the stretched state. When a small amount of heat is applied to the film, it will “recoil,” which results in the film shrinking. Long chain branching in the inventive polyolefin or a high molecular weight tail in its molecular weight distribution (Mw/Mn) are desired molecular architectural attributes to improve shrinkage.

[0028] The spray-dried zirconocene catalyst system may be free of a finely divided solid other than hydrophobic fumed silica or the zirconocene catalyst. For example, the spray-dried zirconocene catalyst system may be free of a support material, such as MgCl2, and a carrier material, such as alumina, clay, or untreated silica. Alternatively, the spray-dried zirconocene catalyst system may further comprise a finely divided solid that is a support material, such as MgCl2, and/or a carrier material, such as an untreated alumina, clay or silica.

[0029] In some embodiments, the spray-dried zirconocene catalyst system and the polymerization method may further comprise a hafnocene catalyst, for example, a bis(propylcyclopentadienyl)hafnium dihalide. Alternatively, the spray-dried zirconocene catalyst system and polymerization method may be hafnium-free.

[0030] Alkyl: monovalent radical of a saturated hydrocarbon, which can be straight chain, branched chain or cyclic. Normal-(C3-C10)alkyl (linear) includes propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl and is an alkyl of formula -(CH2)qCH3, where the subscript q is an integer from 2 to 9, respectively.

[0031] Carrier material: a porous particulate solid having pores and surfaces suitable for transporting a catalyst.

[0032] Composition: a chemical composition. Arrangement, type and ratio of atoms in molecules and type and relative quantities of molecules in a substance or material.

[0033] Compound: a molecule or collection of molecules.

[0034] Concentration: a method of slowly increasing the mass or molar quantity of less volatile chemical constituent(s) per unit volume of a continuous mixture comprising more volatile chemical constituent(s) ) and less volatile constituent(s) by gradually removing the more volatile chemical constituent(s) from the less volatile constituent(s) of the continuous mixture to give a concentrate having a mass or higher molar quantity of the less volatile chemical constituent(s) per unit volume than continuous mixing, where the rate of gradual removal is limited by a ratio of evaporative surface area to mass relatively small (compared to spray drying). The concentrate may be a precipitated solid.

[0035] Consisting essentially of, consists(s) essentially of, and so on. Partially closed expressions that exclude anything that would affect the basic, novel features of what they describe, but otherwise allow for something else.

[0036] Consisting of and consists of. Closed expressions that exclude anything not specifically described by the limitation they modify. In some aspects either, alternatively, each expression “consisting essentially of” or “consists essentially of” may be replaced by the expression “consisting of” or “consists of”, respectively.

[0037] Dry. Anhydrous. A moisture content of 0 to less than 5 parts per million based on total parts by weight. Materials fed to the reactor (or reactors) during a polymerization reaction are dried.

[0038] Effective amount: sufficient amount to achieve an appreciable beneficial result.

[0039] Food. Quantities of reagents and/or reagents that are added or “fed” into a reactor. In continuous polymerization operation, each feed, independently, can be continuous or intermittent. Quantities or “feeds” can be measured, for example, by dosing, to control quantities and relative quantities of the various reactants and reagents in the reactor at any given time.

[0040] Film: Claimed film properties are measured on 25 micrometer thick monolayer films.

[0041] Hydrophobic pretreated fumed silica (i.e., hydrophobic fumed silica): a reaction product of contacting an untreated fumed silica with a hydrophobic agent to react with surface hydroxyl groups on the untreated fumed silica, thereby modifying the surface chemistry of the fumed silica to provide a hydrophobic pretreated fumed silica. The hydrophobic agent may be silicon based.

[0042] Untreated fumed silica (hydrophilic fumed silica): fumed silica produced in a flame. An amorphous silica powder made by fusing microscopic droplets into three-dimensional, chain-shaped, branched secondary particles that agglomerate into tertiary particles. No quartz.

[0043] Hydrophobic agent: organic or organosilicon compound that forms a stable reaction product with hydroxyl groups on the surface of fumed silica.

[0044] Induced condensation agent (ICA): an inert liquid useful for cooling materials in gas phase polymerization reactor (or reactors) (for example, a fluidized bed reactor).

[0045] Inert: Generally, not (noticeably) reactive or not (noticeably) interfering with the inventive polymerization reaction. The term “inert” as applied to the purge gas or ethylene feed means a molecular oxygen (O2) content of 0 to less than 5 parts per million based on the total parts by weight of the purge gas or ethylene feed.

[0046] Modifier: a composition that alters reactivity, stability or both of a substance on which the composition acts.

[0047] Polyethylene: a macromolecule, or collection of macromolecules, composed of constitutional units in which 50 to 100 mol percent (mol%), alternatively, 70 to 100 mol%, alternatively, 80 to 100 mol%, alternatively, 90 to 100 mol%, alternatively, 95 to 100 mol%, alternatively, any of the above ranges where the upper extreme point is < 100 mol%, of such constitutional units derived from ethylene monomer and, in aspects where there are less than 100 mol% ethylenic constitutional units, the remaining constitutional units are comonomeric units derived from at least one (C3-C20)alpha-olefin; or collection of such macromolecules.

[0048] (Pro)catalyst: a pro-catalyst and/or catalyst.

[0049] Quartz: an untreated, non-porous crystalline form of silicon dioxide. Particulate or bulk.

[0050] Silica. A particulate form of silicon dioxide that may be amorphous, crystalline, or gel-like. Includes fused quartz, fumed silica, silica gel and silica airgel.

[0051] Spray drying: rapidly forming a particulate solid comprising less volatile chemical constituents via aspiration of a bulk mixture of the less volatile chemical constituents and more volatile chemical constituents through a nebulizer using a hot gas, wherein the aspiration forms particulates having collectively a relatively large ratio of evaporative surface area to mass compared to that of concentration. The particle size and shape of the particulate solid formed by spray drying may be different from that of a precipitated solid.

[0052] Support material: a non-porous particulate solid to host a catalyst on its surfaces.

[0053] System (chemical): an interrelated arrangement of different chemical constituents, so as to form a functioning whole.

[0054] Transport: movement from location to location. It includes reactor to reactor, tank to reactor, reactor to tank, and manufacturing plant to storage facility and vice versa.

[0055] Alkylaluminoxane: also known as alkylalumoxane. A product of a partial hydrolysis of a trialkylaluminum compound. The alkylaluminoxane may be a (C1-C10)alkylaluminoxane, alternatively a (C1-C6)alkylaluminoxane, alternatively a (C1-C4)alkylaluminoxane, alternatively a (C1-C3)alkylaluminoxane, alternatively a (C1-C2)alkylaluminoxane, alternatively a methylaluminoxane (MAO), alternatively a modified methylaluminoxane (MMAO). In some aspects, alkylaluminoxane is an MAO. In some embodiments, the alkylaluminoxane is supported on untreated silica, such as untreated fumed silica. Alkylaluminoxane can be obtained from a commercial supplier or prepared by any suitable method. Suitable methods for preparing alkylaluminoxanes are well known. Examples of such preparation methods are described in US Patents. 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; 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; and in European publications EP-A-0 561 476; EP-B1-0 279 586; and EP-A-0 594-218; and in PCT publication WO 94/10180.

[0056] (C3-C20) alpha-olefin. Compound of the formula: H2C=C(H)-R, where R is a straight-chain (C1-C18)alkyl group. The (C1-C18)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, the (C3-C20)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.

[0057] Carrier material. The carrier material may be untreated or treated with a hydrophobic agent. The untreated carrier material may be untreated porous silica and has variable surface area, pore volume and average particle size. Each of the above properties is measured using conventional techniques known in the art. The untreated silica may be amorphous silica (not quartz), alternatively a high surface area amorphous silica (e.g., 500 to 1,000 m2/g), or alternatively a high surface area fumed silica. These silicas are commercially available from numerous sources. Silica can be in the form of spherical particles, which are obtained by a spray drying process. Untreated silica can be calcined (i.e., dehydrated) or uncalcined. The treated carrier material is made by treating an untreated carrier material with the hydrophobic agent. The treated carrier material may have different surface chemistry properties and/or dimensions than the untreated carrier material.

[0058] Ethylene: a compound with the formula H2C=CH2.

[0059] ((R1)x-cyclopentadienyl)((R2)y-cyclopentadienyl)zirconium dichloride/dibromide/dialkyl. A ((R1)x-cyclopentadienyl)((R2)y- cyclopentadienyl)zirconium dichloride, ((R1)x-cyclopentadienyl)((R2)y- cyclopentadienyl)zirconium dibromide or (((R1)x-cyclopentadienyl))( (R2)y- cyclopentadienyl)dialkyl zirconium. ((R1)x-cyclopentadienyl)((R2)y-cyclopentadienyl)zirconium dichloride/dibromide/dialkyl may be prepared by any suitable method, such as that described in US 6,242,545 B1 and in US patents, EP publications and PCT mentioned in column 3, in lines 48 to 60. In some embodiments, the ((R1)x-cyclopentadienyl)((R2)y-cyclopentadienyl)zirconium dichloride/dibromide/dialkyl can be obtained from a commercial source. In other embodiments, the ((R1)x-cyclopentadienyl)((R2)y-cyclopentadienyl)zirconium dichloride/dibromide/dialkyl can be synthesized according to any suitable method.

[0060] Syntheses of zirconium procatalysts with dialkylsilanilene bridge of formula (III) are known. For example, dimethyl-1,1'-silanilene-bridged bis(4,5,6,7-tetrahydroindenyl)zirconium dichloride can be synthesized by platinum-catalyzed hydrogenation of dimethyl-bridged bis(indenyl)zirconium dichloride. 1,1'-silanilene.

[0061] Silicon-based hydrophobic agent: an organosilicon compound that forms a stable reaction product with surface hydroxyl groups of a fumed silica. The organosilicon compound may be a polydiorganosiloxane compound or an organosilicon monomer, which contains silicon-bonded leaving groups (e.g., Si-halogen, Si-acetoxy, Si-oxim (Si-ON=C<), Si -alkoxy or Si-amino) which react with surface hydroxyl groups of untreated fumed silica to form Si-O-Si bonds with loss of water molecule as a by-product. The polydiorganosiloxane compound, such as a polydimethylsiloxane, contains backbone Si-O-Si groups in which the oxygen atom can form a stable hydrogen bond to a fumed silica surface hydroxyl group. The silicon-based hydrophobic agent may be trimethylsilyl chloride, dimethyldichlorosilane, a polydimethylsiloxane fluid, hexamethyldisilazane, an octyltrialkoxysilane (e.g., octyltrimethoxysilane) and a combination of two or more thereof.

[0062] Induced condensation agent or ICA. In some aspects, ICA is a (C5-C20)alkane, alternatively, a (C11-C20)alkane, alternatively, a (C5-C10)alkane. In some aspects, ICA is a (C5-C10)alkane. In some aspects, the (C5-C10)alkane is a pentane, e.g., normal pentane or isopentane; one hexane; a heptane; one octane; a nonane; a dean; or a combination of any two or more thereof. In some aspects, ICA is isopentane (i.e., 2-methylbutane). The inventive polymerization method using ICA may be referred to herein as an inert condensation mode operation (ICMO). Gas phase concentration measured using gas chromatography by calibrating the percentage peak area in mole percent (mol%) with a gas mixture standard of known concentrations of ad rem gas phase components. The concentration may be 1 to 10 mol%, alternatively 3 to 8 mol%. The use of ICA is optional. In some aspects, including some of the inventive examples described later, an ICA is used. For example, in aspects of the method to produce a mixture of ICA and catalyst can be fed into a polymerization reactor. In other aspects of the method, the use of ICA can be omitted and a mixed pre-formulated dry catalyst can be fed in this way into the polymerization reactor, which does not have ICA.

[0063] Aluminum compound containing mono or di (C1-C4)alkyl. In any of the above embodiments an aluminum compound containing mono- or di-(C1-C4)alkyl may be used instead of, alternatively, in combination with, trialkylaluminium. The aluminum compound containing mono- or di-(C1-C4)alkyl may independently contain 1 or 2 (C1-C4)alkyl groups, respectively, and 2 or 1 groups, each independently selected from chlorine atom and (C1-C4) )alkoxide. Each (C1-C4)alkyl can independently be methyl; ethyl; propyl; 1-methylethyl; butyl; 1-methylpropyl; 2- methylpropyl; or 1,1-dimethylethyl. Each (C1-C4)alkoxide can independently be methoxide; ethoxide; propoxide; 1-methylethoxide; butoxide; 1- methylpropoxide; 2-methylpropoxide; or 1,1-dimethylethoxide. The aluminum compound containing mono- or di-(C1-C4)alkyl may be diethylaluminum chloride (DEAC), diethylaluminum ethoxide (DEAE), ethylaluminum dichloride (EADC) or a combination or mixture of any two or more thereof.

[0064] Trialkylaluminum: a compound of formula ((C1-C10)alkyl)3Al, in which each (C1-C10)alkyl group is selected independently. Trialkylaluminum can be trimethylaluminum, triethylaluminum (“TEAl”), tripropylaluminum, tris(1-methylethyl)aluminum, tributylaluminum, tris(2-methylpropyl)aluminum (“TiBAl”), tripentylaluminum, trihexylaluminum (“TnHAl”), trioctylaluminum or a combination of any two or more thereof. In some aspects, trialkylaluminum is TiBAl. TiBAl has the formula ((CH3)2C(H)CH2)3Al.

[0065] The spray-dried zirconocene catalyst system can be used in gas-phase or liquid-phase olefin polymerization reactions to enhance the polymerization rate of monomer and/or comonomer(s). Liquid phase reactions include the paste phase and solution phase. In some aspects, the olefin polymerization reaction is conducted in the gas phase, alternatively in the liquid phase, alternatively in the paste phase, alternatively in the solution phase. The conditions for gas-phase and liquid-phase olefin polymerization reactions are generally well known. For illustration, the conditions for gas phase olefin polymerization reactions are described below.

[0066] Polymerization can be carried out in a high pressure liquid phase or gas phase polymerization reactor to produce the inventive polyethylene composition. Such reactors and methods are generally well known in the art. For example, the liquid phase polymerization reactor process/method may be solution phase or slurry phase, as described in US 3,324,095. The gas phase polymerization reactor/method may employ stirred bed gas phase polymerization reactors (SB-GPP reactors) and fluidized bed gas phase polymerization reactors (FB-GPP reactors) and a condensing agent induced and can be carried out in condensation mode polymerization, as described in US 4,453,399; US 4,588,790; US 4,994,534; US 5,352,749; US 5,462,999; and US 6,489,408. The gas phase polymerization reactor/method may be a fluidized bed reactor/method as described in US 3,709,853; US 4,003,712; US 4,011,382; US 4,302,566; US 4,543,399; US 4,882,400; US 5,352,749; US 5,541,270; EP-A-0 802 202; and Belgian Patent No. 839,380. These patents describe gas-phase polymerization processes in which the polymerization medium is mechanically agitated or fluidized by the continuous flow of monomer and gaseous diluent. Other useful gas phase processes include serial or multi-stage polymerization processes, such as described in US 5,627,242; US 5,665,818; US 5,677,375; EP-A-0 794 200; EP-B1-0 649 992; EP-A-0 802 202; and EP-B-634421.

[0067] (co)polymerization conditions. Any resulting effective variable or combination of such variables, such as catalyst composition; amount of reagent; molar ratio of two reactants; absence of interfering materials (e.g. H2O and O2); or a process parameter (e.g., feed rate or temperature), step or sequence that is effective and useful for the copolymerization method of the invention in the polymerization reactor (or reactors) to provide the inventive polyethylene composition.

[0068] At least one, alternatively each, of the (co)polymerization conditions can be fixed (that is, unchanged) during the production of the inventive polyethylene composition. 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 making embodiments of the inventive polyethylene composition that have the same polymeric properties.

[0069] Alternatively, at least one, alternatively two or more of the (co)polymerization conditions may vary within their defined operational parameters during the production of the inventive polyethylene composition for the transition from production of a first embodiment of the polyethylene composition invention having a first set of polymer properties for a non-inventive polyethylene composition or for a second embodiment of the inventive polyethylene composition having a second set of polymer properties, wherein the first and second sets of polymer properties are different and are within the limitations described herein for the inventive polyethylene composition. For example, all other (co)polymerization conditions being equal, a higher molar ratio of (C3-C20)alpha-olefin/ethylene comonomer feeds in the inventive copolymerization method produces a lower density of the inventive polyethylene composition. of resulting product. The transition from one set to another set of (co)polymerization conditions is permitted in the sense of “(co)polymerization conditions”, as the operating parameters of both sets of (co)polymerization conditions are within the defined ranges in this document. A beneficial consequence of the aforementioned transition is that any property value described for the inventive polyethylene composition can be achieved by a person of ordinary skill in the art in view of the teachings of the present document.

[0070] The (co)polymerization conditions for liquid or gas phase reactors/methods may additionally include one or more additives, such as a chain transfer agent, a promoter or a sequestering agent. Chain transfer agents are well known and may be alkyl metal, such as diethyl zinc. Promoters are well known, as in US 4,988,783, and may include chloroform, CFCl3, trichloroethane and difluorotetrachloroethane. Sequestering agents can be a trialkylaluminum. Gas phase or paste polymerizations can be operated without sequestering agents (not deliberately added). The (co)polymerization conditions for gas phase reactors/polymerizations may additionally include an amount (e.g., from 0.5 to 200 ppm based on all feeds into the reactor) of static control agents and/or one or more catalyst additives, such as CA-300 from Univation Technologies, LLC, Houston, Texas, USA. A catalyst additive is a compound that attenuates or decreases the activity of a catalyst and can be used with extra-active catalysts to maintain temperature or polymer production rate at a target level. Static control agents can be added to the gas phase reactor to inhibit the formation or accumulation of static charge.

[0071] The (co)polymerization conditions may additionally 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 to 78 (Hanser Publishers, 1996). All other things being equal, the use of hydrogen can increase the melt flow rate (MFR) or melt index (MI) thereof, where MFR or MI are influenced by the concentration of hydrogen. A molar ratio of hydrogen to total monomer (H2/monomer), for example hydrogen to ethylene (H2/C2) may be > 0 to 0.1, alternatively 0.0001 to 0.0050. A molar ratio of comonomer to ethylene (e.g., α-olefin/C2 molar ratio, i.e., Cx/C2 molar ratio) may be 0.0001 to 0.10, alternatively 0.005 to 0.10, alternatively 0. 15 to 0.050, alternatively 0.020 to 0.039.

[0072] The (co)polymerization conditions may include a partial pressure of ethylene in the polymerization reactor (or reactors) independently of 690 to 3,450 kilopascals (kPa, 100 to 500 pounds per square inch absolute (psia)), alternatively, 1,030 at 2,070 kPa (150 to 300 psia), alternatively, 1,380 to 1,720 kPa (200 to 250 psia), alternatively, 1,450 to 1,590 kPa (210 to 230 psia), for example, 1,520 kPa (220 psia). 1,000 psia = 6.8948 kPa.

[0073] In some aspects, gas phase polymerization is carried out in a fluidized bed gas phase polymerization reactor (FB-GPP) under relevant gas phase fluidized bed polymerization conditions. Such conditions are any variable or combination of variables that can affect a polymerization reaction in the FB-GPP reactor or a composition or property of an ethylene/alpha-olefin copolymer product produced in this way. Variables may include reactor design and size, catalyst composition and quantity; composition and quantity of reagent; molar ratio of two different reagents; presence or absence of feed gases such as H2, molar ratio of feed gases versus reactants, absence or concentration of interfering materials (e.g. H2O), absence or presence of an induced condensation agent (ICA), average time of polymer permanence (avgPRT) in the reactor, partial pressures of constituents, monomer feed rates, reactor bed temperature (e.g. fluidized bed temperature), nature or sequence of process steps, time periods for transition between the steps. When carrying out an inventive method, variables other than those that are described or changed by the inventive method can be kept constant.

[0074] The molar ratio of comonomer/ethylene gas Cx/C2 of comonomer and ethylene being fed to the FB-GPP reactor can be from 0.0001 to 0.1, alternatively 0.005 to 0.10, alternatively from 0.15 to 0.050 , alternatively from 0.020 to 0.039.

[0075] Partial pressure of ethylene in the FB-GPP reactor. From 690 to 2,070 kilopascals (kPa, that is, from 100 to 300 psia (pounds per square inch absolute)); alternatively, 830 to 1,655 kPa (120 to 240 psia), alternatively, 1,300 to 1,515 kPa (190 to 220 psia). Alternatively, the partial pressure of ethylene may be 690 to 3,450 kilopascals (kPa, 100 to 500 pounds per absolute square inch (psia)), alternatively, 1,030 to 2,070 kPa (150 to 300 psia), alternatively, 1,380 to 1,720 kPa (200 to 250 psia), alternatively, 1,450 to 1,590 kPa (210 to 230 psia), e.g. 1,520 kPa (220 psia). 1,000 psia = 6.8948 kPa.

[0076] Molar ratios of hydrogen gas to ethylene (H2/C2) in the FB-GPP reactor can be from > 0 to 0.1, alternatively from 0.0001 to 0.0050. In other embodiments the molar ratio of H2/C2 gas in the FB-GPP reactor may be from 0.0001 to 0.25, alternatively from 0.0005 to 0.200, alternatively from 0.005 to 0.149, alternatively from 0.009 to 0.109, alternatively, from 0.010 to 0.100, alternatively, from 0.0001 to 0.0050.

[0077] The reactor bed temperature in the FB-GPP reactor can be from 70° to 120°C, alternatively from 75° to 115°C, alternatively from 79° to 110°C, alternatively from 80, 0° to 89°C.

[0078] Average residence time for polymer (avgPRT). The number of minutes or hours, on average, that the polymeric product remains in the FB-GPP reactor. The avgPRT 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.

[0079] In some aspects, any compound, composition, formulation, mixture or reaction product herein may be free of 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, lanthanoids and actinoids; with the proviso that chemical elements required by the compound, composition, formulation, mixture or reaction product (e.g. Zr required by a zirconocene) are not excluded.

[0080] Density Test Method: measured in accordance with ASTM D79213, Standard Test Methods for Density and Specific Gravity (Relative Density) of Displacement Plastics, Method B (for testing solid plastics in liquids other than water, e.g. , in liquid 2-propanol). Report results in units of grams per cubic centimeter (g/cm3).

[0081] Flow Rate Test Method (190 °C, 21.6 kg, “FI21”): use ASTM D1238-13, Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Platemer, with the use conditions of 190°C/21.6 kilograms (kg). Report results in units of grams eluted for 10 minutes (g/10 min.).

[0082] Gel Permeation Chromatography (GPC) Method: Weight Average Molecular Weight Test Method: determine Mw, number average molecular weight (Mn) and Mw/Mn using chromatograms obtained on a Gel Permeation Chromatography instrument. High Temperature (HTGPC, Polymer Laboratories). The HTGPC is equipped with transfer lines, a differential refractive index (DRI) detector, and three 10 μm Polymer Laboratories PLgel Mixed-B columns, all contained in an oven maintained at 160 °C. The method uses a solvent composed of TCB treated with BHT at a nominal flow rate of 1.0 milliliter per minute (ml/min) and a nominal injection volume of 300 microliters (μ l). Prepare the solvent by dissolving 6 grams of butylated hydroxytoluene (BHT, antioxidant) in 4 liters (l) of 1,2,4-trichlorobenzene (TCB) reagent and filtering the resulting solution through a 0.1 micrometer Teflon filter (μ m) to provide the solvent. Degas the solvent with an in-line degasser before entering the HTGPC instrument. Calibrate the columns with a series of monodisperse polystyrene (PS) standards. Separately, prepare known concentrations of test polymer dissolved in solvent by heating known amounts thereof in known volumes of solvent to 160°C with continuous stirring for 2 hours to provide solutions. (Measure all quantities gravimetrically) Target solution concentrations, c, of test polymer of 0.5 to 2.0 milligrams of polymer per milliliter of solution (mg/ml), where lower concentrations, c, are used to higher molecular weight polymers. Before passing each sample, purge the DRI detector. Then increase the flow rate in the device to 1.0 ml/minute and let the DRI detector stabilize for 8 hours before injecting the first sample. Calculate Mw and Mn using universal calibration relationships with column calibrations. Calculate the MW in each elution volume with the following equation: where the subscript “X” represents the test sample, the subscript “PS” represents PS standards, APS =0.67, KPS = 0.000175, and AX and KX are obtained from published literature. For polyethylenes, ax/Kx = 0.695/0.000579. For polypropylenes, ax/Kx = 0.705/0.0002288. At each point in the resulting chromatogram, calculate the concentration, c, from a DRI signal subtracted from the reference base, IDRI, using the following equation: c = KDRIIDRI/(dn/dc), where KDRI is a constant determined by calibrating the DRI, / indicates division and dn/dc is the refractive index increment for the polymer. For polyethylene, dn/dc = 0.109. Calculate the mass recovery from the ratio of the integrated area of the concentration chromatography chromatogram over the elution volume and the injection mass that is equal to the predetermined concentration multiplied by the injection closed circuit volume. Report all molecular weights in grams per mole (g/mol) unless otherwise noted. Additional details regarding the methods for determining Mw, Mn, MWD are described in document No. US 2006/0173123, pages 24 and 25, paragraphs [0334] to [0341]. Plot dW/dLog(MW) on the y axis versus Log(MW) on the x axis to provide a GPC chromatogram, where Log(MW) and dW/dLog(MW) are as defined above.

[0083] Melt Index Test Method (190°C., 2.16 kilograms (kg), “I2”): measured in accordance with ASTM D1238-13, using conditions of 190°C./2.16 kg , formerly known as “Condition E” and also known as I2. Report results in units of grams eluted for 10 minutes (g/10 min.).

[0084] Ethylene (“C2”): a monomer; used at the partial pressure of C2 described below.

[0085] 1-hexene (“C6”): a comonomer; used in the C6/C2 molar ratio described below.

[0086] Molecular hydrogen gas (“H2”): used in a molar ratio of H2/C2 described below.

[0087] Inventive Example 1 (IE1): Spray-dried Zirconocene Catalyst System 1 (iZr1). Load 18.1 kilograms (kg) of anhydrous toluene into a stirred reactor A (reactor A). Then add 10.9 kg of a 10% by weight solution of methylalumoxane (MAO) in toluene to reactor A. Then 1.63 kg of CAB-O-SIL® TS-610 are charged into reactor A and the paste is mixed overnight. While stirring the resulting slurry at room temperature, add 221 g of a 23.9% by weight solution of bis(1-methyl-3-butylcyclopentadienyl)zirconium dichloride. Continue mixing the contents of reactor A for 60 minutes. The above slurry was then spray dried using a pilot scale spray dryer. The slurry was fed to the spray dryer at a feed rate of 120 pounds per hour. The atomizer speed was maintained at 90%. The exit temperature in the condenser was maintained at about 80°C. and the inlet temperature was maintained at about 160°C. The final spray-dried catalyst composition had a zirconium loading of 0.46 wt%, an aluminum loading of 15.5 wt%, and 2.6 wt% residual toluene.

[0088] Inventive Example 2 (IE2): Spray-dried Zirconocene Catalyst System 2 (iZr2). Load 18.1 kg of anhydrous toluene into a stirred reactor A (reactor A). Then add 10.9 kg of a 10% by weight solution of methylalumoxane (MAO) in toluene to reactor A. Then 1.63 kg of CAB-O-SIL® TS-610 are charged into reactor A and the paste is mixed overnight. While stirring the resulting paste at room temperature, add 55.9 g of bis(4,5,6,7-tetrahydroindenyl)zirconium dichloride with dimethyl-1,1'-silanilene bridge. Continue mixing the contents of reactor A for 60 minutes. The above slurry was then spray dried using a pilot scale spray dryer. The slurry was fed to the spray dryer at a feed rate of 120 pounds per hour. The atomizer speed was maintained at 90%. The exit temperature in the condenser was maintained at about 80°C. and the inlet temperature was maintained at about 160°C. The final spray-dried catalyst composition had a zirconium loading of 0.42 wt%, an aluminum loading of 15.9 wt%, and 3.2 wt% residual toluene.

[0089] Comparative Example 1 (CE1): Zirconocene Catalyst System 1 (ceZr1). Made from bis(1-methyl 3-n-butylcyclopentadienyl)zirconium dichloride or dimethyl, supplied by Univation Technologies, Inc., was used for this example.

[0090] Comparative Example 2 (CE2): spray-dried zirconocene catalyst on porous silica (ceZr2). Load 7.7 kg of anhydrous toluene into a stirred reactor (reactor A). Next, add 8.5 kg of a 10% by weight solution of methylalumoxane (MAO) in toluene into reactor A. Then, charge 245 g of a 23.9% by weight solution of bis(1-methyl- 3-butylcyclopentadienyl)zirconium dichloride in toluene in reactor A. Mix the slurry. In a separate reactor (reactor B), combine and mix 2.2 kg of SYLOPOL® 948 silica that was previously calcined at 600°C and 7.7 kg of toluene. Then, load the pre-mixed solution from reactor A into reactor B and mix the paste for one hour. Then, load 160 g of Additive B into the slurry in reactor B and mix the resulting slurry for 30 minutes. Spray dry the paste using a pilot scale spray dryer having a condenser. Feed the paste to the spray dryer at a feed rate of 45 kg per hour. Maintain atomizer speed at 90%, condenser outlet temperature at about 99°C and inlet temperature at about 165°C to give ceZr2. ceZr2 has a Zr loading of 0.44 wt%, an Al loading of 10.8 wt%, and 2.8 wt% residual toluene.

[0091] Comparative Example 3 (CE3): zirconocene catalyst on porous silica (ceZr3); not spray dried. Made from zirconium procatalyst of formula (III) bis(4,5,6,7-tetrahydroindenyl)zirconium dichloride with dimethyl-1,1'-silanilene bridge, supplied by Univation Technologies, Inc., was used for this example. ceZr2 has a Zr loading of 0.34 wt%, an Al loading of 12.8 wt%, and approximately 1.5 wt% residual toluene.

[0092] Inventive Example A (IE(A)): Gas phase fluidized bed copolymerization of ethylene and 1-hexene catalyzed by the spray-dried zirconocene catalyst system iZr1 of IE1 to give an ethylene/1 copolymer composition -hexene with nominal targets of 1.0MI and 0.918g/cm3 density. Use a gas phase fluidized bed reactor that has an internal diameter of 0.35 meter (m) and a bed height of 2.3 m and a fluidized bed composed of polymer granules. Introduce gaseous feed streams of ethylene and hydrogen together with 1-hexene comonomer introduced below the reactor bed in a recycle gas line. Control the individual flow rates of ethylene, hydrogen, and 1-hexene to maintain fixed composition targets and control the ethylene concentration to maintain a constant ethylene partial pressure. Control hydrogen to keep the molar ratio of hydrogen to ethylene (H2/C2) constant. Measure concentrations of all gases using an in-line gas chromatograph. Maintain the fluidized bed at a constant height by removing a portion of the bed at a rate equal to the rate of particulate product formation. Obtain polymer production rate in the range of 15 to 25 kg/hour. Remove product semi-continuously through a series of valves into a fixed volume chamber. Purge the removed product to remove any entrained hydrocarbons and treat with a small stream of humidified nitrogen to deactivate any trace amounts of residual catalyst and cocatalyst. For IE(A), disperse the solid catalyst in dry, degassed mineral oil as a nominal 18 wt% slurry and inject the slurry directly into the fluidized bed using purified nitrogen and isopentane as carriers. Control the relative feed rate of the catalyst to achieve a target polymer production rate, while maintaining the reaction temperature and gas compositions in the reactor to achieve the target polymer properties. Maintain the reaction bed of growing polymer particles in a fluidized state by continuously flowing the supplement feed and recycle gas through the reaction zone at a surface gas velocity approximately in the range of 0.64 to 0.64 m/s . Operate the reactor at a total pressure of approximately 2,413 kPA gauge. Maintain a constant fluidized bed temperature by continually adjusting the recycle gas temperature up or down by passing the recycle gas through a shell-and-tube heat exchanger with shell-side cooling water. In the IE(A) example, feed a slurry mixture containing 20% by weight of CA-300 catalyst additive in dry, degassed mineral oil to the reactor using isopentane as the carrier. Feed CA-300 at a rate to maintain about 30 ppmw of CA-300 in the polymer product, where ppmw here is catalyst additive flow rate in kg/hour times (x) its concentration in weight % divided by polymer reactor production rate in kg/hour.

[0093] Inventive Example B (IE(B)): Replicate the IE(A) procedure except adjust the reactor operating conditions to give an ethylene/1-hexene copolymer composition with a nominal target of 1.0 MI and density of 0.912 g/cm3.

[0094] Inventive Example C (IE(C)): Replicate the procedure of IE(A), except replace iZr1 with iZr2 of IE2 and adjust the reactor operating conditions to give an ethylene/1-hexene copolymer composition with nominal target of 1.0 MI and 0.9196 g/cm3 density.

[0095] Comparative Example A (CE(A)): replicate the IE(A) procedure, except replace the spray-dried zirconocene catalyst system iZr1 of IE(1) with the comparative zirconocene catalyst system ceZr1 of CE1. In the CE(A) example, the catalyst was fed to the reactor as a dry powder using a nitrogen carrier stream to disperse the catalyst in the fluidized bed and no catalyst additives (e.g., no CA-300) were added to the reactor.

[0096] Comparative Example B (CE(B)): replicate the IE(A) procedure, except replace the spray-dried zirconocene catalyst system iZr1 of IE(1) with the comparative spray-dried zirconocene catalyst system ceZr2 of CE2. In the CE(B) example, feed the catalyst to the reactor as a dry powder using a nitrogen carrier stream to disperse the catalyst in the fluidized bed. Do not add catalyst additive (e.g. without CA-300) to the reactor.

[0097] Comparative Example C (CE(C)): replicate the IE(A) procedure, except replace the iZr1 catalyst system of IE(1) with the ceZr1 comparative catalyst system of CE1 and adjust the reactor operating conditions to give an ethylene/1-hexene copolymer composition with a nominal target of 1.0 MI and a density of 0.912 g/cm3. Feed the catalyst into the reactor as a dry powder using a nitrogen carrier stream to disperse the catalyst in the fluidized bed. Do not add catalyst additive (e.g. without CA-300) to the reactor.

[0098] Comparative Example D (CE(D)): replicate the IE(A) procedure, except replace iZr1 of IE(1) with the comparative spray-dried zirconocene catalyst system ceZr3 of CE3. In the CE(D) example, feed the catalyst to the reactor as a dry powder using a nitrogen carrier stream to disperse the catalyst in the fluidized bed.

[0099] Ex. No. is the Example Number; sdCat. Sys. it is spray dried zirconium catalyst system; %p is percentage by weight; cm3/hour is cubic centimeters per hour; kg is kilogram; m/s is meter per second; kPa is kilopascals; mole is mole and mol/mol is mole per mole; C2 is ethylene; C6 is 1-hexene; H2 is molecular hydrogen gas; Mw is weight average molecular weight determined by GPC as previously described; g is grams; g/cm3 is grams per cubic centimeter; N/a is not determined; g/10 min. is grams per 10 minutes; Cat. Prod. (PE weight/Cat. weight) is weight of polymer product made per weight of catalyst system used; cm is centimeter. ICP is inductively coupled plasma. The ppm/mol% in relation to the H2/C2 ratio is H2 concentration in parts per million by weight in ethylene (C2) concentration in mol%.

[00100] Table 1. Catalyst characteristics in Gas Phase Polymerizations

[00101] As shown in Table 1, iZr1 of IE1 and IE(A) has a zirconium loading comparable, by ICP analysis, to that of ceZr1 and ceZr2 of CE1 and CE2, respectively. iZr1 of IE1 and IE(A) has a higher Al loading than that of ceZr1 and ceZr2. Without wishing to be limited by theory, the highest level of Al loading is achievable using the inventive spray drying method in combination with a fumed silica filler (CAB-O-SIL® TS-610), as opposed to the Al carrier. porous silica of the comparative examples and can enhance the overall catalyst productivity. Table 2. Gas Phase Polymerization Process Conditions

[00102] In Table 2, the gas phase process conditions are similar for both the inventive and comparative examples. The reactor catalyst additive, CA-300 (at a target of 30 ppmw based on bed weight), was used with iZr1 of IE1, whereas CE(A) and CE(B) did not require CA-300. Table 3. Polymer Properties of Gas Phase Polymerizations Product

[00103] In Table 3, the product properties for the inventive product are similar to those of the comparative product, except for the unexpectedly high z-average molecular weight (Mz) of IE(A) relative to the Mz of CE(A) and CE( B). Table 4. Catalyst/Process Characteristics of Gas Phase Polymerizations

[00104] In Table 4, the inventive iZr1 spray-dried zirconocene catalyst system and related gas phase polymerization methods produced ethylene/alpha-olefin copolymer compositions with beneficially higher catalyst productivity (approximately 2.5x higher) compared to catalyst productivity of the ceZr1 comparative catalyst system and methods. Table 5. Polymer Properties of Gas Phase Polymerizations Product

[00105] Table 5 shows numerical data on the distribution of short chain branching by Crystallization Elution Chromatography (CEF). IE(A) shows a significantly higher weight fraction in Zone 2 relative to CE(A) and CE(B), suggesting that IE(A) has a narrower short chain branching (SCB) distribution, which It is beneficial for inventive film properties. Table 6. Polymer Properties of Gas Phase Polymerizations Product

[00106] Table 6 summarizes low shear rate melt rheology data of the samples, measured by Dynamic Mechanical Spectroscopy (DMS). IE(A) produced by spray-dried iZr1 is more sensitive to shear compared to CE(A) and CE(B), as shown by the higher viscosity at low shear rates and lower viscosity at higher shear rates. high. This behavior for IE(A) is also reflected in the higher viscosity ratio (viscosity at 0.1 rad/s over that at 100 rad/s) and lower tan delta (or lower elasticity). The higher viscosity at very low shear rate (0.1 rad/s) seen with IE(A) is consistent with the unexpected Mz for IE(A) shown in Table 3. Table 7. Phase Polymerization Process Conditions of gas

[00107] In Table 7, the gas phase process conditions are similar for both the inventive and comparative examples. The reactor catalyst additive, CA-300 (at a target of 30 ppmw based on bed weight), used for IE(B) helped mitigate potential operability issues associated with the high activity observed with IE1 iZr1, while that CE(C) did not require CA-300. Table 8. Polymer Properties of Gas Phase Polymerizations Product

[00108] In Table 8, the properties of the inventive product are similar to those of the comparative product, with the exception of the unexpectedly narrow MWD of IE(B) relative to CE(C). Table 9. Catalyst/Process Characteristics of Gas Phase Polymerizations

[00109] In Table 9, the inventive spray-dried zirconocene catalyst systems iZr1 of IE1 and IE(B) produced ethylene/alpha-olefin copolymer compositions with beneficially higher catalyst productivity (approximately 2.5x higher) compared to with catalyst productivity of the ceZr1 comparative catalyst system of CE1 and CE(C). Table 10. Polymer Properties of Gas Phase Polymerizations Product

[00110] Table 10 shows numerical data on the distribution of short chain branching by Crystallization Elution Chromatography (CEF). IE(B) shows a significantly higher weight fraction in Zone 2 relative to CE(C), suggesting that IE(B) has a narrower SCB distribution, beneficial for films. Table 11. Polymer Properties of Gas Phase Polymerizations Product

[00111] Table 11 summarizes the low shear rate melt rheology data of the samples measured by DMS. IE(B) and CE(C) show similar absolute sensitivity. IE(B) shows a lower tan delta, suggesting lower elasticity. Table 12. Catalyst characteristics in Gas Phase Polymerizations.

[00112] As shown in Table 12, iZr2 of IE4 and IE(C) have a comparable zirconium loading and a comparable Al loading, both by ICP analysis, to those of ceZr3 of CE3. Table 13. Gas Phase Polymerization Process Conditions.

[00113] In Table 13, the gas phase process conditions are similar for both the inventive example IE(C) and the comparative example CE(D). Table 14. Polymer Properties of Gas Phase Polymerizations Product.

[00114] In Table 14, the product properties for the inventive product are similar to those of the comparative product, except for the unexpectedly lower molecular weight distribution for IE(C) versus CE(D). Table 15. Catalyst/Process Characteristics of Gas Phase Polymerizations

[00115] In Table 15, the inventive iZr2 spray-dried zirconocene catalyst system and related gas phase polymerization methods produced ethylene/alpha-olefin copolymer compositions with beneficially higher catalyst productivity (approximately 1.4 times higher ) compared to catalyst productivity of the ceZr3 comparative catalyst system and methods.

Claims (7)

1. Spray-dried zirconocene catalyst system, characterized in that it comprises a zirconocene catalyst and a hydrophobic fumed silica, which supports the zirconocene catalyst, wherein the zirconocene catalyst of the spray-dried zirconocene catalyst system is made from a reaction of an activator and a zirconocene procatalyst of formula (III): ((R3)z-(4,5,6,7-tetrahydroindenyl))((R4)t-(4, 5,6,7-tetrahydroindenyl))zirconium dichloride/dibromide/dialkyl (III), where the subscript z and t is 1; and wherein a first R3 is in position 1 of the 4,5,6,7-tetrahydroindenyl to which it is bonded and the first R3 is covalently bonded to the first R4 to form a divalent bridging group of formula Si(R5) 2, where each R5 is methyl. 2. Spray-dried zirconocene catalyst system according to claim 1, characterized in that it is made by mixing the activator, the zirconocene procatalyst, and the hydrophobic fumed silica in a hydrocarbon solvent to make a suspension of the hydrophobic fumed silica in a solution of the zirconocene catalyst, which is made IN SITU, in the hydrocarbon solvent; and spray drying the suspension to result in the spray dried zirconocene catalyst system. 3. Spray-dried zirconocene catalyst system according to any one of claims 1 or 2, characterized in that the hydrophobic fumed silica is made by contacting an untreated fumed silica, having surfaces containing silicon-bonded hydroxyl groups, with a silicon-based hydrophobic agent, containing on average per molecule one or more functional groups reactive with a SiOH group, to result in hydrophobic fumed silica. 4. Spray-dried zirconocene catalyst system according to any one of claims 1 to 3, characterized in that the activator is an alkylaluminum, an alkylaluminoxane, or a combination thereof. 5. Spray-dried zirconocene catalyst system according to any one of claims 1 to 4, further comprising any of the limitations (i) to (vii): (i) an olefin monomer (e.g. , ethylene) or alpha-olefin; (ii) a polyolefin; (iii) a metal carboxylate salt, where the metal carboxylate salt is represented by the formula: MQm(O2CR)n, where M is a metal atom from Group 2 or Group 13 of the Periodic Table of the Elements; Q is a halogen, hydroxy, alkyl, alkoxy, aryloxy, siloxy, silane or sulfonate group; R is a (C5-C30)hydrocarbyl; subscript m is an integer from 0 to 3; subscript n is an integer from 1 to 4; and the sum of the subscripts m and n is equal to the valence of M; and (iv) both (i) and (ii); (v) both (i) and (iii); (vi) both (ii) and (iii); and (vii) each of (i) to (iii). 6. Method for making a spray-dried zirconocene catalyst system, the method being characterized by the fact that it comprises contacting in a hydrocarbon solvent an activator with a zirconocene procatalyst as defined in any one of claims 1 to 5, and a hydrophobic fumed silica, and, optionally, a metal carboxylate salt of the formula: MQm(O2CR)n, wherein M,Q,R, subscript m and subscript n are as defined in claim 10, to result in a suspension of the fumed silica hydrophobic in a solution of the zirconocene catalyst, which is made IN SITU, in the hydrocarbon solvent and then spray-drying the suspension to result in the spray-dried zirconocene catalyst system. 7. Method for making a polyethylene composition, the method being characterized by contacting ethylene and optionally zero, one or more (C3-C20)alpha-olefins with the spray-dried zirconocene catalyst system as defined in any of claims 1 to 5 in a polymerization reactor to generate a polymerization reaction resulting in a polyethylene composition comprising a polyethylene homopolymer or ethylene/(C3-C20)alpha-olefin copolymer, respectively, and the zirconocene catalyst system spray dried, or a by-product thereof.